mDNSResponder-333.10.tar.gz

[apple/mdnsresponder.git] / mDNSShared / uds_daemon.c

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2003-2011 Apple Computer, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#if defined(_WIN32)
#include <process.h>
#define usleep(X) Sleep(((X)+999)/1000)
#else
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#endif

#include <stdlib.h>
#include <stdio.h>

#include "mDNSEmbeddedAPI.h"
#include "DNSCommon.h"
#include "uDNS.h"
#include "uds_daemon.h"

// Normally we append search domains only for queries with a single label that are not
// fully qualified. This can be overridden to apply search domains for queries (that are
// not fully qualified) with any number of labels e.g., moon, moon.cs, moon.cs.be, etc.
mDNSBool AlwaysAppendSearchDomains = mDNSfalse;

// Apple-specific functionality, not required for other platforms
#if APPLE_OSX_mDNSResponder
#include <sys/ucred.h>
#ifndef PID_FILE
#define PID_FILE ""
#endif
#endif

#if APPLE_OSX_mDNSResponder
#include <WebFilterDNS/WebFilterDNS.h>

#if ! NO_WCF

int WCFIsServerRunning(WCFConnection *conn) __attribute__((weak_import));
int WCFNameResolvesToAddr(WCFConnection *conn, char* domainName, struct sockaddr* address, uid_t userid) __attribute__((weak_import));
int WCFNameResolvesToName(WCFConnection *conn, char* fromName, char* toName, uid_t userid) __attribute__((weak_import));

// Do we really need to define a macro for "if"?
#define CHECK_WCF_FUNCTION(X) if (X)
#endif // ! NO_WCF

#else
#define NO_WCF 1
#endif // APPLE_OSX_mDNSResponder

// User IDs 0-500 are system-wide processes, not actual users in the usual sense
// User IDs for real user accounts start at 501 and count up from there
#define SystemUID(X) ((X) <= 500)

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Types and Data Structures
#endif

typedef enum
        {
        t_uninitialized,
        t_morecoming,
        t_complete,
        t_error,
        t_terminated
        } transfer_state;

typedef struct request_state request_state;

typedef void (*req_termination_fn)(request_state *request);

typedef struct registered_record_entry
        {
        struct registered_record_entry *next;
        mDNSu32 key;
        client_context_t regrec_client_context;
        request_state *request;
        mDNSBool external_advertise;
        mDNSInterfaceID origInterfaceID;
        AuthRecord *rr;                         // Pointer to variable-sized AuthRecord (Why a pointer? Why not just embed it here?)
        } registered_record_entry;

// A single registered service: ServiceRecordSet + bookkeeping
// Note that we duplicate some fields from parent service_info object
// to facilitate cleanup, when instances and parent may be deallocated at different times.
typedef struct service_instance
        {
        struct service_instance *next;
        request_state *request;
        AuthRecord *subtypes;
        mDNSBool renameonmemfree;               // Set on config change when we deregister original name
    mDNSBool clientnotified;            // Has client been notified of successful registration yet?
        mDNSBool default_local;                 // is this the "local." from an empty-string registration?
        mDNSBool external_advertise;    // is this is being advertised externally?
        domainname domain;
        ServiceRecordSet srs;                   // note -- variable-sized object -- must be last field in struct
        } service_instance;

// for multi-domain default browsing
typedef struct browser_t
        {
        struct browser_t *next;
        domainname domain;
        DNSQuestion q;
        } browser_t;

struct request_state
        {
        request_state *next;
        request_state *primary;                 // If this operation is on a shared socket, pointer to primary
                                                                        // request_state for the original DNSServiceCreateConnection() operation
        dnssd_sock_t sd;
        dnssd_sock_t errsd;
        mDNSu32 uid;
        void * platform_data;

        // Note: On a shared connection these fields in the primary structure, including hdr, are re-used
        // for each new request. This is because, until we've read the ipc_msg_hdr to find out what the
        // operation is, we don't know if we're going to need to allocate a new request_state or not.
        transfer_state ts;
        mDNSu32        hdr_bytes;               // bytes of header already read
        ipc_msg_hdr    hdr;
        mDNSu32        data_bytes;              // bytes of message data already read
        char          *msgbuf;                  // pointer to data storage to pass to free()
        const char    *msgptr;                  // pointer to data to be read from (may be modified)
        char          *msgend;                  // pointer to byte after last byte of message

        // reply, termination, error, and client context info
        int no_reply;                                   // don't send asynchronous replies to client
        mDNSs32 time_blocked;                   // record time of a blocked client
        int unresponsiveness_reports;
        struct reply_state *replies;    // corresponding (active) reply list
        req_termination_fn terminate;
        DNSServiceFlags         flags;  

        union
                {
                registered_record_entry *reg_recs;  // list of registrations for a connection-oriented request
                struct
                        {
                        mDNSInterfaceID interface_id;
                        mDNSBool default_domain;
                        mDNSBool ForceMCast;
                        domainname regtype;
                        browser_t *browsers;
                        } browser;
                struct
                        {
                        mDNSInterfaceID InterfaceID;
                        mDNSu16 txtlen;
                        void *txtdata;
                        mDNSIPPort port;
                        domainlabel name;
                        char type_as_string[MAX_ESCAPED_DOMAIN_NAME];
                        domainname type;
                        mDNSBool default_domain;
                        domainname host;
                        mDNSBool autoname;                              // Set if this name is tied to the Computer Name
                        mDNSBool autorename;                    // Set if this client wants us to automatically rename on conflict
                        mDNSBool allowremotequery;              // Respond to unicast queries from outside the local link?
                        int num_subtypes;
                        service_instance *instances;
                        } servicereg;
                struct
                        {
                        mDNSInterfaceID      interface_id;
                        mDNSu32              flags;
                        mDNSu32              protocol;
                        DNSQuestion          q4;
                        DNSQuestion          *q42;
                        DNSQuestion          q6;
                        DNSQuestion          *q62;
                        } addrinfo;
                struct
                        {
                        mDNSIPPort           ReqExt;    // External port we originally requested, for logging purposes
                        NATTraversalInfo     NATinfo;
                        } pm;
                struct
                        {
#if 0
                        DNSServiceFlags flags;
#endif
                        DNSQuestion q_all;
                        DNSQuestion q_default;
                        } enumeration;
                struct
                        {
                        DNSQuestion q;
                        DNSQuestion *q2;
                        } queryrecord;
                struct
                        {
                        DNSQuestion qtxt;
                        DNSQuestion qsrv;
                        const ResourceRecord *txt;
                        const ResourceRecord *srv;
                        mDNSs32 ReportTime;
                        mDNSBool external_advertise;
                        } resolve;
                } u;
        };

// struct physically sits between ipc message header and call-specific fields in the message buffer
typedef struct
        {
        DNSServiceFlags flags;                  // Note: This field is in NETWORK byte order
        mDNSu32 ifi;                                    // Note: This field is in NETWORK byte order
        DNSServiceErrorType error;              // Note: This field is in NETWORK byte order
        } reply_hdr;

typedef struct reply_state
        {
        struct reply_state *next;               // If there are multiple unsent replies
        mDNSu32 totallen;
        mDNSu32 nwriten;
        ipc_msg_hdr mhdr[1];
        reply_hdr rhdr[1];
        } reply_state;

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Globals
#endif

// globals
mDNSexport mDNS mDNSStorage;
mDNSexport const char ProgramName[] = "mDNSResponder";

static dnssd_sock_t listenfd = dnssd_InvalidSocket;
static request_state *all_requests = NULL;

// Note asymmetry here between registration and browsing.
// For service registrations we only automatically register in domains that explicitly appear in local configuration data
// (so AutoRegistrationDomains could equally well be called SCPrefRegDomains)
// For service browsing we also learn automatic browsing domains from the network, so for that case we have:
// 1. SCPrefBrowseDomains (local configuration data)
// 2. LocalDomainEnumRecords (locally-generated local-only PTR records -- equivalent to slElem->AuthRecs in uDNS.c)
// 3. AutoBrowseDomains, which is populated by tracking add/rmv events in AutomaticBrowseDomainChange, the callback function for our mDNS_GetDomains call.
// By creating and removing our own LocalDomainEnumRecords, we trigger AutomaticBrowseDomainChange callbacks just like domains learned from the network would.

mDNSexport DNameListElem *AutoRegistrationDomains;      // Domains where we automatically register for empty-string registrations

static DNameListElem *SCPrefBrowseDomains;                      // List of automatic browsing domains read from SCPreferences for "empty string" browsing
static ARListElem    *LocalDomainEnumRecords;           // List of locally-generated PTR records to augment those we learn from the network
mDNSexport DNameListElem *AutoBrowseDomains;            // List created from those local-only PTR records plus records we get from the network

#define MSG_PAD_BYTES 5         // pad message buffer (read from client) with n zero'd bytes to guarantee
                                                        // n get_string() calls w/o buffer overrun
// initialization, setup/teardown functions

// If a platform specifies its own PID file name, we use that
#ifndef PID_FILE
#define PID_FILE "/var/run/mDNSResponder.pid"
#endif

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - General Utility Functions
#endif

mDNSlocal void FatalError(char *errmsg)
        {
        char* ptr = NULL;
        LogMsg("%s: %s", errmsg, dnssd_strerror(dnssd_errno));
        *ptr = 0;       // On OS X abort() doesn't generate a crash log, but writing to zero does
        abort();    // On platforms where writing to zero doesn't generate an exception, abort instead
        }

mDNSlocal mDNSu32 dnssd_htonl(mDNSu32 l)
        {
        mDNSu32 ret;
        char *data = (char*) &ret;
        put_uint32(l, &data);
        return ret;
        }

// hack to search-replace perror's to LogMsg's
mDNSlocal void my_perror(char *errmsg)
        {
        LogMsg("%s: %d (%s)", errmsg, dnssd_errno, dnssd_strerror(dnssd_errno));
        }

mDNSlocal void abort_request(request_state *req)
        {
        if (req->terminate == (req_termination_fn)~0)
                { LogMsg("abort_request: ERROR: Attempt to abort operation %p with req->terminate %p", req, req->terminate); return; }
        
        // First stop whatever mDNSCore operation we were doing
        // If this is actually a shared connection operation, then its req->terminate function will scan
        // the all_requests list and terminate any subbordinate operations sharing this file descriptor
        if (req->terminate) req->terminate(req);

        if (!dnssd_SocketValid(req->sd))
                { LogMsg("abort_request: ERROR: Attempt to abort operation %p with invalid fd %d",     req, req->sd);        return; }
        
        // Now, if this request_state is not subordinate to some other primary, close file descriptor and discard replies
        if (!req->primary)
                {
                if (req->errsd != req->sd) LogOperation("%3d: Removing FD and closing errsd %d", req->sd, req->errsd);
                else                       LogOperation("%3d: Removing FD", req->sd);
                udsSupportRemoveFDFromEventLoop(req->sd, req->platform_data);           // Note: This also closes file descriptor req->sd for us
                if (req->errsd != req->sd) { dnssd_close(req->errsd); req->errsd = req->sd; }

                while (req->replies)    // free pending replies
                        {
                        reply_state *ptr = req->replies;
                        req->replies = req->replies->next;
                        freeL("reply_state (abort)", ptr);
                        }
                }

        // Set req->sd to something invalid, so that udsserver_idle knows to unlink and free this structure
#if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING
        // Don't use dnssd_InvalidSocket (-1) because that's the sentinel value MACOSX_MDNS_MALLOC_DEBUGGING uses
        // for detecting when the memory for an object is inadvertently freed while the object is still on some list
        req->sd = req->errsd = -2;
#else
        req->sd = req->errsd = dnssd_InvalidSocket;
#endif
        // We also set req->terminate to a bogus value so we know if abort_request() gets called again for this request
        req->terminate = (req_termination_fn)~0;
        }

mDNSlocal void AbortUnlinkAndFree(request_state *req)
        {
        request_state **p = &all_requests;
        abort_request(req);
        while (*p && *p != req) p=&(*p)->next;
        if (*p) { *p = req->next; freeL("request_state/AbortUnlinkAndFree", req); }
        else LogMsg("AbortUnlinkAndFree: ERROR: Attempt to abort operation %p not in list", req);
        }

mDNSlocal reply_state *create_reply(const reply_op_t op, const size_t datalen, request_state *const request)
        {
        reply_state *reply;

        if ((unsigned)datalen < sizeof(reply_hdr))
                {
                LogMsg("ERROR: create_reply - data length less than length of required fields");
                return NULL;
                }

        reply = mallocL("reply_state", sizeof(reply_state) + datalen - sizeof(reply_hdr));
        if (!reply) FatalError("ERROR: malloc");
        
        reply->next     = mDNSNULL;
        reply->totallen = (mDNSu32)datalen + sizeof(ipc_msg_hdr);
        reply->nwriten  = 0;

        reply->mhdr->version        = VERSION;
        reply->mhdr->datalen        = (mDNSu32)datalen;
        reply->mhdr->ipc_flags      = 0;
        reply->mhdr->op             = op;
        reply->mhdr->client_context = request->hdr.client_context;
        reply->mhdr->reg_index      = 0;

        return reply;
        }

// Append a reply to the list in a request object
// If our request is sharing a connection, then we append our reply_state onto the primary's list
mDNSlocal void append_reply(request_state *req, reply_state *rep)
        {
        request_state *r = req->primary ? req->primary : req;
        reply_state **ptr = &r->replies;
        while (*ptr) ptr = &(*ptr)->next;
        *ptr = rep;
        rep->next = NULL;
        }

// Generates a response message giving name, type, domain, plus interface index,
// suitable for a browse result or service registration result.
// On successful completion rep is set to point to a malloc'd reply_state struct
mDNSlocal mStatus GenerateNTDResponse(const domainname *const servicename, const mDNSInterfaceID id,
        request_state *const request, reply_state **const rep, reply_op_t op, DNSServiceFlags flags, mStatus err)
        {
        domainlabel name;
        domainname type, dom;
        *rep = NULL;
        if (!DeconstructServiceName(servicename, &name, &type, &dom))
                return kDNSServiceErr_Invalid;
        else
                {
                char namestr[MAX_DOMAIN_LABEL+1];
                char typestr[MAX_ESCAPED_DOMAIN_NAME];
                char domstr [MAX_ESCAPED_DOMAIN_NAME];
                int len;
                char *data;

                ConvertDomainLabelToCString_unescaped(&name, namestr);
                ConvertDomainNameToCString(&type, typestr);
                ConvertDomainNameToCString(&dom, domstr);

                // Calculate reply data length
                len = sizeof(DNSServiceFlags);
                len += sizeof(mDNSu32);  // if index
                len += sizeof(DNSServiceErrorType);
                len += (int) (strlen(namestr) + 1);
                len += (int) (strlen(typestr) + 1);
                len += (int) (strlen(domstr) + 1);

                // Build reply header
                *rep = create_reply(op, len, request);
                (*rep)->rhdr->flags = dnssd_htonl(flags);
                (*rep)->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(&mDNSStorage, id, mDNSfalse));
                (*rep)->rhdr->error = dnssd_htonl(err);

                // Build reply body
                data = (char *)&(*rep)->rhdr[1];
                put_string(namestr, &data);
                put_string(typestr, &data);
                put_string(domstr, &data);

                return mStatus_NoError;
                }
        }

// Special support to enable the DNSServiceBrowse call made by Bonjour Browser
// Remove after Bonjour Browser is updated to use DNSServiceQueryRecord instead of DNSServiceBrowse
mDNSlocal void GenerateBonjourBrowserResponse(const domainname *const servicename, const mDNSInterfaceID id,
        request_state *const request, reply_state **const rep, reply_op_t op, DNSServiceFlags flags, mStatus err)
        {
        char namestr[MAX_DOMAIN_LABEL+1];
        char typestr[MAX_ESCAPED_DOMAIN_NAME];
        static const char domstr[] = ".";
        int len;
        char *data;

        *rep = NULL;

        // 1. Put first label in namestr
        ConvertDomainLabelToCString_unescaped((const domainlabel *)servicename, namestr);

        // 2. Put second label and "local" into typestr
        mDNS_snprintf(typestr, sizeof(typestr), "%#s.local.", SecondLabel(servicename));

        // Calculate reply data length
        len = sizeof(DNSServiceFlags);
        len += sizeof(mDNSu32);  // if index
        len += sizeof(DNSServiceErrorType);
        len += (int) (strlen(namestr) + 1);
        len += (int) (strlen(typestr) + 1);
        len += (int) (strlen(domstr) + 1);

        // Build reply header
        *rep = create_reply(op, len, request);
        (*rep)->rhdr->flags = dnssd_htonl(flags);
        (*rep)->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(&mDNSStorage, id, mDNSfalse));
        (*rep)->rhdr->error = dnssd_htonl(err);

        // Build reply body
        data = (char *)&(*rep)->rhdr[1];
        put_string(namestr, &data);
        put_string(typestr, &data);
        put_string(domstr, &data);
        }

// Returns a resource record (allocated w/ malloc) containing the data found in an IPC message
// Data must be in the following format: flags, interfaceIndex, name, rrtype, rrclass, rdlen, rdata, (optional) ttl
// (ttl only extracted/set if ttl argument is non-zero). Returns NULL for a bad-parameter error
mDNSlocal AuthRecord *read_rr_from_ipc_msg(request_state *request, int GetTTL, int validate_flags)
        {
        DNSServiceFlags flags  = get_flags(&request->msgptr, request->msgend);
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        char name[256];
        int         str_err = get_string(&request->msgptr, request->msgend, name, sizeof(name));
        mDNSu16     type    = get_uint16(&request->msgptr, request->msgend);
        mDNSu16     class   = get_uint16(&request->msgptr, request->msgend);
        mDNSu16     rdlen   = get_uint16(&request->msgptr, request->msgend);
        const char *rdata   = get_rdata (&request->msgptr, request->msgend, rdlen);
        mDNSu32 ttl   = GetTTL ? get_uint32(&request->msgptr, request->msgend) : 0;
        int storage_size = rdlen > sizeof(RDataBody) ? rdlen : sizeof(RDataBody);
        AuthRecord *rr;
        mDNSInterfaceID InterfaceID;
        AuthRecType artype;

        request->flags = flags;

        if (str_err) { LogMsg("ERROR: read_rr_from_ipc_msg - get_string"); return NULL; }

        if (!request->msgptr) { LogMsg("Error reading Resource Record from client"); return NULL; }

        if (validate_flags &&
                !((flags & kDNSServiceFlagsShared) == kDNSServiceFlagsShared) &&
                !((flags & kDNSServiceFlagsUnique) == kDNSServiceFlagsUnique))
                {
                LogMsg("ERROR: Bad resource record flags (must be kDNSServiceFlagsShared or kDNSServiceFlagsUnique)");
                return NULL;
                }

        rr = mallocL("AuthRecord/read_rr_from_ipc_msg", sizeof(AuthRecord) - sizeof(RDataBody) + storage_size);
        if (!rr) FatalError("ERROR: malloc");

        InterfaceID = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        if (InterfaceID == mDNSInterface_LocalOnly)
                artype = AuthRecordLocalOnly;
        else if (InterfaceID == mDNSInterface_P2P)
                artype = AuthRecordP2P;
        else if ((InterfaceID == mDNSInterface_Any) && (flags & kDNSServiceFlagsIncludeP2P))
                artype = AuthRecordAnyIncludeP2P;
        else
                artype = AuthRecordAny;

        mDNS_SetupResourceRecord(rr, mDNSNULL, InterfaceID, type, 0,
                (mDNSu8) ((flags & kDNSServiceFlagsShared) ? kDNSRecordTypeShared : kDNSRecordTypeUnique), artype, mDNSNULL, mDNSNULL);

        if (!MakeDomainNameFromDNSNameString(&rr->namestorage, name))
                {
                LogMsg("ERROR: bad name: %s", name);
                freeL("AuthRecord/read_rr_from_ipc_msg", rr);
                return NULL;
                }

        if (flags & kDNSServiceFlagsAllowRemoteQuery) rr->AllowRemoteQuery = mDNStrue;
        rr->resrec.rrclass = class;
        rr->resrec.rdlength = rdlen;
        rr->resrec.rdata->MaxRDLength = rdlen;
        mDNSPlatformMemCopy(rr->resrec.rdata->u.data, rdata, rdlen);
        if (GetTTL) rr->resrec.rroriginalttl = ttl;
        rr->resrec.namehash = DomainNameHashValue(rr->resrec.name);
        SetNewRData(&rr->resrec, mDNSNULL, 0);  // Sets rr->rdatahash for us
        return rr;
        }

mDNSlocal int build_domainname_from_strings(domainname *srv, char *name, char *regtype, char *domain)
        {
        domainlabel n;
        domainname d, t;

        if (!MakeDomainLabelFromLiteralString(&n, name)) return -1;
        if (!MakeDomainNameFromDNSNameString(&t, regtype)) return -1;
        if (!MakeDomainNameFromDNSNameString(&d, domain)) return -1;
        if (!ConstructServiceName(srv, &n, &t, &d)) return -1;
        return 0;
        }

mDNSlocal void send_all(dnssd_sock_t s, const char *ptr, int len)
        {
        int n = send(s, ptr, len, 0);
        // On a freshly-created Unix Domain Socket, the kernel should *never* fail to buffer a small write for us
        // (four bytes for a typical error code return, 12 bytes for DNSServiceGetProperty(DaemonVersion)).
        // If it does fail, we don't attempt to handle this failure, but we do log it so we know something is wrong.
        if (n < len)
                LogMsg("ERROR: send_all(%d) wrote %d of %d errno %d (%s)",
                        s, n, len, dnssd_errno, dnssd_strerror(dnssd_errno));
        }

#if 0
mDNSlocal mDNSBool AuthorizedDomain(const request_state * const request, const domainname * const d, const DNameListElem * const doms)
{
        const           DNameListElem   *delem = mDNSNULL;
        int             bestDelta       = -1;                                   // the delta of the best match, lower is better
        int             dLabels         = 0;
        mDNSBool        allow           = mDNSfalse;
        
        if (SystemUID(request->uid)) return mDNStrue;
        
        dLabels = CountLabels(d);
        for (delem = doms; delem; delem = delem->next)
                {
                if (delem->uid)
                        {
                        int     delemLabels = CountLabels(&delem->name);
                        int delta               = dLabels - delemLabels;
                        if ((bestDelta == -1 || delta <= bestDelta) && SameDomainName(&delem->name, SkipLeadingLabels(d, delta)))
                                {
                                bestDelta = delta;
                                allow = (allow || (delem->uid == request->uid));
                                }
                        }
                }
        
        return bestDelta == -1 ? mDNStrue : allow;
}
#endif

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - external helpers
#endif

mDNSlocal void external_start_advertising_helper(service_instance *const instance)
        {
        AuthRecord *st = instance->subtypes;
        ExtraResourceRecord *e;
        int i;
        
        if (mDNSIPPortIsZero(instance->request->u.servicereg.port))
                {
                LogInfo("external_start_advertising_helper: Not registering service with port number zero");
                return;
                }

#if APPLE_OSX_mDNSResponder
        // Update packet filter if p2p interface already exists, otherwise,
        // if will be updated when we get the KEV_DL_IF_ATTACHED event for
        // the interface.  Called here since we don't call external_start_advertising_service()
        // with the SRV record when advertising a service.
        mDNSInitPacketFilter();
#endif // APPLE_OSX_mDNSResponder

        if (instance->external_advertise) LogMsg("external_start_advertising_helper: external_advertise already set!");
        
        for ( i = 0; i < instance->request->u.servicereg.num_subtypes; i++)
                external_start_advertising_service(&st[i].resrec);
        
        external_start_advertising_service(&instance->srs.RR_PTR.resrec);
        external_start_advertising_service(&instance->srs.RR_TXT.resrec);
        
        for (e = instance->srs.Extras; e; e = e->next)
                external_start_advertising_service(&e->r.resrec);
        
        instance->external_advertise = mDNStrue;
        }

mDNSlocal void external_stop_advertising_helper(service_instance *const instance)
        {
        AuthRecord *st = instance->subtypes;
        ExtraResourceRecord *e;
        int i;
        
        if (!instance->external_advertise) return;

        LogInfo("external_stop_advertising_helper: calling external_stop_advertising_service");
        
        for ( i = 0; i < instance->request->u.servicereg.num_subtypes; i++)
                external_stop_advertising_service(&st[i].resrec);
        
        external_stop_advertising_service(&instance->srs.RR_PTR.resrec);
        external_stop_advertising_service(&instance->srs.RR_TXT.resrec);
        
        for (e = instance->srs.Extras; e; e = e->next)
                external_stop_advertising_service(&e->r.resrec);
        
        instance->external_advertise = mDNSfalse;
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceRegister
#endif

mDNSexport void FreeExtraRR(mDNS *const m, AuthRecord *const rr, mStatus result)
        {
        ExtraResourceRecord *extra = (ExtraResourceRecord *)rr->RecordContext;
        (void)m;  // Unused

        if (result != mStatus_MemFree) { LogMsg("Error: FreeExtraRR invoked with unexpected error %d", result); return; }

        LogInfo("     FreeExtraRR %s", RRDisplayString(m, &rr->resrec));

        if (rr->resrec.rdata != &rr->rdatastorage)
                freeL("Extra RData", rr->resrec.rdata);
        freeL("ExtraResourceRecord/FreeExtraRR", extra);
        }

mDNSlocal void unlink_and_free_service_instance(service_instance *srv)
        {
        ExtraResourceRecord *e = srv->srs.Extras, *tmp;

        external_stop_advertising_helper(srv);

        // clear pointers from parent struct
        if (srv->request)
                {
                service_instance **p = &srv->request->u.servicereg.instances;
                while (*p)
                        {
                        if (*p == srv) { *p = (*p)->next; break; }
                        p = &(*p)->next;
                        }
                }

        while (e)
                {
                e->r.RecordContext = e;
                tmp = e;
                e = e->next;
                FreeExtraRR(&mDNSStorage, &tmp->r, mStatus_MemFree);
                }

        if (srv->srs.RR_TXT.resrec.rdata != &srv->srs.RR_TXT.rdatastorage)
                freeL("TXT RData", srv->srs.RR_TXT.resrec.rdata);

        if (srv->subtypes) { freeL("ServiceSubTypes", srv->subtypes); srv->subtypes = NULL; }
        freeL("service_instance", srv);
        }

// Count how many other service records we have locally with the same name, but different rdata.
// For auto-named services, we can have at most one per machine -- if we allowed two auto-named services of
// the same type on the same machine, we'd get into an infinite autoimmune-response loop of continuous renaming.
mDNSexport int CountPeerRegistrations(mDNS *const m, ServiceRecordSet *const srs)
        {
        int count = 0;
        ResourceRecord *r = &srs->RR_SRV.resrec;
        AuthRecord *rr;

        for (rr = m->ResourceRecords; rr; rr=rr->next)
                if (rr->resrec.rrtype == kDNSType_SRV && SameDomainName(rr->resrec.name, r->name) && !IdenticalSameNameRecord(&rr->resrec, r))
                        count++;

        verbosedebugf("%d peer registrations for %##s", count, r->name->c);
        return(count);
        }

mDNSexport int CountExistingRegistrations(domainname *srv, mDNSIPPort port)
        {
        int count = 0;
        AuthRecord *rr;
        for (rr = mDNSStorage.ResourceRecords; rr; rr=rr->next)
                if (rr->resrec.rrtype == kDNSType_SRV &&
                        mDNSSameIPPort(rr->resrec.rdata->u.srv.port, port) &&
                        SameDomainName(rr->resrec.name, srv))
                        count++;
        return(count);
        }

mDNSlocal void SendServiceRemovalNotification(ServiceRecordSet *const srs)
        {
        reply_state *rep;
        service_instance *instance = srs->ServiceContext;
        if (GenerateNTDResponse(srs->RR_SRV.resrec.name, srs->RR_SRV.resrec.InterfaceID, instance->request, &rep, reg_service_reply_op, 0, mStatus_NoError) != mStatus_NoError)
                LogMsg("%3d: SendServiceRemovalNotification: %##s is not valid DNS-SD SRV name", instance->request->sd, srs->RR_SRV.resrec.name->c);
        else { append_reply(instance->request, rep); instance->clientnotified = mDNSfalse; }
        }

// service registration callback performs three duties - frees memory for deregistered services,
// handles name conflicts, and delivers completed registration information to the client
mDNSlocal void regservice_callback(mDNS *const m, ServiceRecordSet *const srs, mStatus result)
        {
        mStatus err;
        mDNSBool SuppressError = mDNSfalse;
        service_instance *instance;
        reply_state         *rep;
        (void)m; // Unused

        if (!srs)      { LogMsg("regservice_callback: srs is NULL %d",                 result); return; }

        instance = srs->ServiceContext;
        if (!instance) { LogMsg("regservice_callback: srs->ServiceContext is NULL %d", result); return; }

        // don't send errors up to client for wide-area, empty-string registrations
        if (instance->request &&
                instance->request->u.servicereg.default_domain &&
                !instance->default_local)
                SuppressError = mDNStrue;

        if (mDNS_LoggingEnabled)
                {
                const char *const fmt =
                        (result == mStatus_NoError)      ? "%s DNSServiceRegister(%##s, %u) REGISTERED"    :
                        (result == mStatus_MemFree)      ? "%s DNSServiceRegister(%##s, %u) DEREGISTERED"  :
                        (result == mStatus_NameConflict) ? "%s DNSServiceRegister(%##s, %u) NAME CONFLICT" :
                                                           "%s DNSServiceRegister(%##s, %u) %s %d";
                char prefix[16] = "---:";
                if (instance->request) mDNS_snprintf(prefix, sizeof(prefix), "%3d:", instance->request->sd);
                LogOperation(fmt, prefix, srs->RR_SRV.resrec.name->c, mDNSVal16(srs->RR_SRV.resrec.rdata->u.srv.port),
                        SuppressError ? "suppressed error" : "CALLBACK", result);
                }

        if (!instance->request && result != mStatus_MemFree) { LogMsg("regservice_callback: instance->request is NULL %d", result); return; }

        if (result == mStatus_NoError)
                {
                if (instance->request->u.servicereg.allowremotequery)
                        {
                        ExtraResourceRecord *e;
                        srs->RR_ADV.AllowRemoteQuery = mDNStrue;
                        srs->RR_PTR.AllowRemoteQuery = mDNStrue;
                        srs->RR_SRV.AllowRemoteQuery = mDNStrue;
                        srs->RR_TXT.AllowRemoteQuery = mDNStrue;
                        for (e = instance->srs.Extras; e; e = e->next) e->r.AllowRemoteQuery = mDNStrue;
                        }

                if (GenerateNTDResponse(srs->RR_SRV.resrec.name, srs->RR_SRV.resrec.InterfaceID, instance->request, &rep, reg_service_reply_op, kDNSServiceFlagsAdd, result) != mStatus_NoError)
                        LogMsg("%3d: regservice_callback: %##s is not valid DNS-SD SRV name", instance->request->sd, srs->RR_SRV.resrec.name->c);
                else { append_reply(instance->request, rep); instance->clientnotified = mDNStrue; }

                if (instance->request->u.servicereg.InterfaceID == mDNSInterface_P2P || (!instance->request->u.servicereg.InterfaceID && SameDomainName(&instance->domain, &localdomain) && (instance->request->flags & kDNSServiceFlagsIncludeP2P)))
                        {
                        LogInfo("regservice_callback: calling external_start_advertising_helper()");
                        external_start_advertising_helper(instance);
                        }
                if (instance->request->u.servicereg.autoname && CountPeerRegistrations(m, srs) == 0)
                        RecordUpdatedNiceLabel(m, 0);   // Successfully got new name, tell user immediately
                }
        else if (result == mStatus_MemFree)
                {
                if (instance->request && instance->renameonmemfree)
                        {
                        external_stop_advertising_helper(instance);
                        instance->renameonmemfree = 0;
                        err = mDNS_RenameAndReregisterService(m, srs, &instance->request->u.servicereg.name);
                        if (err) LogMsg("ERROR: regservice_callback - RenameAndReregisterService returned %d", err);
                        // error should never happen - safest to log and continue
                        }
                else
                        unlink_and_free_service_instance(instance);
                }
        else if (result == mStatus_NameConflict)
                {
                if (instance->request->u.servicereg.autorename)
                        {
                        external_stop_advertising_helper(instance);
                        if (instance->request->u.servicereg.autoname && CountPeerRegistrations(m, srs) == 0)
                                {
                                // On conflict for an autoname service, rename and reregister *all* autoname services
                                IncrementLabelSuffix(&m->nicelabel, mDNStrue);
                                mDNS_ConfigChanged(m);  // Will call back into udsserver_handle_configchange()
                                }
                        else    // On conflict for a non-autoname service, rename and reregister just that one service
                                {
                                if (instance->clientnotified) SendServiceRemovalNotification(srs);
                                mDNS_RenameAndReregisterService(m, srs, mDNSNULL);
                                }
                        }
                else
                        {
                        if (!SuppressError) 
                                {
                                if (GenerateNTDResponse(srs->RR_SRV.resrec.name, srs->RR_SRV.resrec.InterfaceID, instance->request, &rep, reg_service_reply_op, kDNSServiceFlagsAdd, result) != mStatus_NoError)
                                        LogMsg("%3d: regservice_callback: %##s is not valid DNS-SD SRV name", instance->request->sd, srs->RR_SRV.resrec.name->c);
                                else { append_reply(instance->request, rep); instance->clientnotified = mDNStrue; }
                                }
                        unlink_and_free_service_instance(instance);
                        }
                }
        else            // Not mStatus_NoError, mStatus_MemFree, or mStatus_NameConflict
                {
                if (!SuppressError) 
                        {
                        if (GenerateNTDResponse(srs->RR_SRV.resrec.name, srs->RR_SRV.resrec.InterfaceID, instance->request, &rep, reg_service_reply_op, kDNSServiceFlagsAdd, result) != mStatus_NoError)
                                LogMsg("%3d: regservice_callback: %##s is not valid DNS-SD SRV name", instance->request->sd, srs->RR_SRV.resrec.name->c);
                        else { append_reply(instance->request, rep); instance->clientnotified = mDNStrue; }
                        }
                }
        }

mDNSlocal void regrecord_callback(mDNS *const m, AuthRecord *rr, mStatus result)
        {
        (void)m; // Unused
        if (!rr->RecordContext)         // parent struct already freed by termination callback
                {
                if (result == mStatus_NoError)
                        LogMsg("Error: regrecord_callback: successful registration of orphaned record %s", ARDisplayString(m, rr));
                else
                        {
                        if (result != mStatus_MemFree) LogMsg("regrecord_callback: error %d received after parent termination", result);

                        // We come here when the record is being deregistered either from DNSServiceRemoveRecord or connection_termination.
                        // If the record has been updated, we need to free the rdata. Everytime we call mDNS_Update, it calls update_callback
                        // with the old rdata (so that we can free it) and stores the new rdata in "rr->resrec.rdata". This means, we need
                        // to free the latest rdata for which the update_callback was never called with.
                        if (rr->resrec.rdata != &rr->rdatastorage) freeL("RData/regrecord_callback", rr->resrec.rdata);
                        freeL("AuthRecord/regrecord_callback", rr);
                        }
                }
        else
                {
                registered_record_entry *re = rr->RecordContext;
                request_state *request = re->request;

                if (mDNS_LoggingEnabled)
                        {
                        char *fmt = (result == mStatus_NoError)      ? "%3d: DNSServiceRegisterRecord(%u %s) REGISTERED"    :
                                                (result == mStatus_MemFree)      ? "%3d: DNSServiceRegisterRecord(%u %s) DEREGISTERED"  :
                                                (result == mStatus_NameConflict) ? "%3d: DNSServiceRegisterRecord(%u %s) NAME CONFLICT" :
                                                                                                                   "%3d: DNSServiceRegisterRecord(%u %s) %d";
                        LogOperation(fmt, request->sd, re->key, RRDisplayString(m, &rr->resrec), result);
                        }

                if (result != mStatus_MemFree)
                        {
                        int len = sizeof(DNSServiceFlags) + sizeof(mDNSu32) + sizeof(DNSServiceErrorType);
                        reply_state *reply = create_reply(reg_record_reply_op, len, request);
                        reply->mhdr->client_context = re->regrec_client_context;
                        reply->rhdr->flags = dnssd_htonl(0);
                        reply->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(m, rr->resrec.InterfaceID, mDNSfalse));
                        reply->rhdr->error = dnssd_htonl(result);
                        append_reply(request, reply);
                        }

                if (result)
                        {
                        // unlink from list, free memory
                        registered_record_entry **ptr = &request->u.reg_recs;
                        while (*ptr && (*ptr) != re) ptr = &(*ptr)->next;
                        if (!*ptr) { LogMsg("regrecord_callback - record not in list!"); return; }
                        *ptr = (*ptr)->next;
                        freeL("registered_record_entry AuthRecord regrecord_callback", re->rr);
                        freeL("registered_record_entry regrecord_callback", re);
                        }
                else
                        {
                        if (re->external_advertise) LogMsg("regrecord_callback: external_advertise already set!");

                        if (re->origInterfaceID == mDNSInterface_P2P || (!re->origInterfaceID && IsLocalDomain(&rr->namestorage) && (request->flags & kDNSServiceFlagsIncludeP2P)))
                                {
                                LogInfo("regrecord_callback: calling external_start_advertising_service");
                                external_start_advertising_service(&rr->resrec);
                                re->external_advertise = mDNStrue;
                                }
                        }
                }
        }

mDNSlocal void connection_termination(request_state *request)
        {
        // When terminating a shared connection, we need to scan the all_requests list
        // and terminate any subbordinate operations sharing this file descriptor
        request_state **req = &all_requests;
        
        LogOperation("%3d: DNSServiceCreateConnection STOP", request->sd);
        
        while (*req)
                {
                if ((*req)->primary == request)
                        {
                        // Since we're already doing a list traversal, we unlink the request directly instead of using AbortUnlinkAndFree()
                        request_state *tmp = *req;
                        if (tmp->primary == tmp) LogMsg("connection_termination ERROR (*req)->primary == *req for %p %d",                  tmp, tmp->sd);
                        if (tmp->replies)        LogMsg("connection_termination ERROR How can subordinate req %p %d have replies queued?", tmp, tmp->sd);
                        abort_request(tmp);
                        *req = tmp->next;
                        freeL("request_state/connection_termination", tmp);
                        }
                else
                        req = &(*req)->next;
                }

        while (request->u.reg_recs)
                {
                registered_record_entry *ptr = request->u.reg_recs;
                LogOperation("%3d: DNSServiceRegisterRecord(%u %s) STOP", request->sd, ptr->key, RRDisplayString(&mDNSStorage, &ptr->rr->resrec));
                request->u.reg_recs = request->u.reg_recs->next;
                ptr->rr->RecordContext = NULL;
                if (ptr->external_advertise)
                        {
                        ptr->external_advertise = mDNSfalse;
                        external_stop_advertising_service(&ptr->rr->resrec);
                        }
                mDNS_Deregister(&mDNSStorage, ptr->rr);         // Will free ptr->rr for us
                freeL("registered_record_entry/connection_termination", ptr);
                }
        }

mDNSlocal void handle_cancel_request(request_state *request)
        {
        request_state **req = &all_requests;
        LogOperation("%3d: Cancel %08X %08X", request->sd, request->hdr.client_context.u32[1], request->hdr.client_context.u32[0]);
        while (*req)
                {
                if ((*req)->primary == request &&
                        (*req)->hdr.client_context.u32[0] == request->hdr.client_context.u32[0] &&
                        (*req)->hdr.client_context.u32[1] == request->hdr.client_context.u32[1])
                        {
                        // Since we're already doing a list traversal, we unlink the request directly instead of using AbortUnlinkAndFree()
                        request_state *tmp = *req;
                        abort_request(tmp);
                        *req = tmp->next;
                        freeL("request_state/handle_cancel_request", tmp);
                        }
                else
                        req = &(*req)->next;
                }
        }

mDNSlocal mStatus handle_regrecord_request(request_state *request)
        {
        mStatus err = mStatus_BadParamErr;
        AuthRecord *rr = read_rr_from_ipc_msg(request, 1, 1);
        if (rr)
                {
                registered_record_entry *re;
                // Don't allow non-local domains to be regsitered as LocalOnly. Allowing this would permit
                // clients to register records such as www.bigbank.com A w.x.y.z to redirect Safari.
                if (rr->resrec.InterfaceID == mDNSInterface_LocalOnly && !IsLocalDomain(rr->resrec.name) &&
                        rr->resrec.rrclass == kDNSClass_IN && (rr->resrec.rrtype == kDNSType_A || rr->resrec.rrtype == kDNSType_AAAA ||
                        rr->resrec.rrtype == kDNSType_CNAME))
                        {
                        freeL("AuthRecord/handle_regrecord_request", rr);
                        return (mStatus_BadParamErr);
                        }
                // allocate registration entry, link into list
                re = mallocL("registered_record_entry", sizeof(registered_record_entry));
                if (!re) FatalError("ERROR: malloc");
                re->key                   = request->hdr.reg_index;
                re->rr                    = rr;
                re->regrec_client_context = request->hdr.client_context;
                re->request               = request;
                re->external_advertise    = mDNSfalse;
                rr->RecordContext         = re;
                rr->RecordCallback        = regrecord_callback;

                re->origInterfaceID = rr->resrec.InterfaceID;
                if (rr->resrec.InterfaceID == mDNSInterface_P2P) rr->resrec.InterfaceID = mDNSInterface_Any;    
#if 0
                if (!AuthorizedDomain(request, rr->resrec.name, AutoRegistrationDomains))       return (mStatus_NoError);
#endif
                if (rr->resrec.rroriginalttl == 0)
                        rr->resrec.rroriginalttl = DefaultTTLforRRType(rr->resrec.rrtype);
        
                LogOperation("%3d: DNSServiceRegisterRecord(%u %s) START", request->sd, re->key, RRDisplayString(&mDNSStorage, &rr->resrec));
                err = mDNS_Register(&mDNSStorage, rr);
                if (err)
                        {
                        LogOperation("%3d: DNSServiceRegisterRecord(%u %s) ERROR (%d)", request->sd, re->key, RRDisplayString(&mDNSStorage, &rr->resrec), err);
                        freeL("registered_record_entry", re);
                        freeL("registered_record_entry/AuthRecord", rr);
                        }
                else
                        {
                        re->next = request->u.reg_recs;
                        request->u.reg_recs = re;
                        }
                }
        return(err);
        }

mDNSlocal void UpdateDeviceInfoRecord(mDNS *const m);

mDNSlocal void regservice_termination_callback(request_state *request)
        {
        if (!request) { LogMsg("regservice_termination_callback context is NULL"); return; }
        while (request->u.servicereg.instances)
                {
                service_instance *p = request->u.servicereg.instances;
                request->u.servicereg.instances = request->u.servicereg.instances->next;
                // only safe to free memory if registration is not valid, i.e. deregister fails (which invalidates p)
                LogOperation("%3d: DNSServiceRegister(%##s, %u) STOP",
                        request->sd, p->srs.RR_SRV.resrec.name->c, mDNSVal16(p->srs.RR_SRV.resrec.rdata->u.srv.port));
                
                external_stop_advertising_helper(p);

                // Clear backpointer *before* calling mDNS_DeregisterService/unlink_and_free_service_instance
                // We don't need unlink_and_free_service_instance to cut its element from the list, because we're already advancing
                // request->u.servicereg.instances as we work our way through the list, implicitly cutting one element at a time
                // We can't clear p->request *after* the calling mDNS_DeregisterService/unlink_and_free_service_instance
                // because by then we might have already freed p
                p->request = NULL;
                if (mDNS_DeregisterService(&mDNSStorage, &p->srs)) unlink_and_free_service_instance(p);
                // Don't touch service_instance *p after this -- it's likely to have been freed already
                }
        if (request->u.servicereg.txtdata)
                { freeL("service_info txtdata", request->u.servicereg.txtdata); request->u.servicereg.txtdata = NULL; }
        if (request->u.servicereg.autoname)
                {
                // Clear autoname before calling UpdateDeviceInfoRecord() so it doesn't mistakenly include this in its count of active autoname registrations
                request->u.servicereg.autoname = mDNSfalse;
                UpdateDeviceInfoRecord(&mDNSStorage);
                }
        }

mDNSlocal request_state *LocateSubordinateRequest(request_state *request)
        {
        request_state *req;
        for (req = all_requests; req; req = req->next)
                if (req->primary == request &&
                        req->hdr.client_context.u32[0] == request->hdr.client_context.u32[0] &&
                        req->hdr.client_context.u32[1] == request->hdr.client_context.u32[1]) return(req);
        return(request);
        }

mDNSlocal mStatus add_record_to_service(request_state *request, service_instance *instance, mDNSu16 rrtype, mDNSu16 rdlen, const char *rdata, mDNSu32 ttl)
        {
        ServiceRecordSet *srs = &instance->srs;
        mStatus result;
        int size = rdlen > sizeof(RDataBody) ? rdlen : sizeof(RDataBody);
        ExtraResourceRecord *extra = mallocL("ExtraResourceRecord", sizeof(*extra) - sizeof(RDataBody) + size);
        if (!extra) { my_perror("ERROR: malloc"); return mStatus_NoMemoryErr; }

        mDNSPlatformMemZero(extra, sizeof(ExtraResourceRecord));  // OK if oversized rdata not zero'd
        extra->r.resrec.rrtype = rrtype;
        extra->r.rdatastorage.MaxRDLength = (mDNSu16) size;
        extra->r.resrec.rdlength = rdlen;
        mDNSPlatformMemCopy(&extra->r.rdatastorage.u.data, rdata, rdlen);

        result = mDNS_AddRecordToService(&mDNSStorage, srs, extra, &extra->r.rdatastorage, ttl,
                                        (request->flags & kDNSServiceFlagsIncludeP2P) ? 1: 0);
        if (result) { freeL("ExtraResourceRecord/add_record_to_service", extra); return result; }

        extra->ClientID = request->hdr.reg_index;
        if (instance->external_advertise && (instance->request->u.servicereg.InterfaceID == mDNSInterface_P2P || (!instance->request->u.servicereg.InterfaceID && SameDomainName(&instance->domain, &localdomain) && (instance->request->flags & kDNSServiceFlagsIncludeP2P))))
                {
                LogInfo("add_record_to_service: calling external_start_advertising_service");
                external_start_advertising_service(&extra->r.resrec);
                }
        return result;
        }

mDNSlocal mStatus handle_add_request(request_state *request)
        {
        service_instance *i;
        mStatus result = mStatus_UnknownErr;
        DNSServiceFlags flags  = get_flags (&request->msgptr, request->msgend);
        mDNSu16         rrtype = get_uint16(&request->msgptr, request->msgend);
        mDNSu16         rdlen  = get_uint16(&request->msgptr, request->msgend);
        const char     *rdata  = get_rdata (&request->msgptr, request->msgend, rdlen);
        mDNSu32         ttl    = get_uint32(&request->msgptr, request->msgend);
        if (!ttl) ttl = DefaultTTLforRRType(rrtype);
        (void)flags; // Unused

        if (!request->msgptr) { LogMsg("%3d: DNSServiceAddRecord(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        // If this is a shared connection, check if the operation actually applies to a subordinate request_state object
        if (request->terminate == connection_termination) request = LocateSubordinateRequest(request);

        if (request->terminate != regservice_termination_callback)
                { LogMsg("%3d: DNSServiceAddRecord(not a registered service ref)", request->sd); return(mStatus_BadParamErr); }

        // For a service registered with zero port, don't allow adding records. This mostly happens due to a bug
        // in the application. See radar://9165807.
        if (mDNSIPPortIsZero(request->u.servicereg.port))
                { LogMsg("%3d: DNSServiceAddRecord: adding record to a service registered with zero port", request->sd); return(mStatus_BadParamErr); }

        LogOperation("%3d: DNSServiceAddRecord(%X, %##s, %s, %d)", request->sd, flags,
                (request->u.servicereg.instances) ? request->u.servicereg.instances->srs.RR_SRV.resrec.name->c : NULL, DNSTypeName(rrtype), rdlen);

        for (i = request->u.servicereg.instances; i; i = i->next)
                {
                result = add_record_to_service(request, i, rrtype, rdlen, rdata, ttl);
                if (result && i->default_local) break;
                else result = mStatus_NoError;  // suppress non-local default errors
                }

        return(result);
        }

mDNSlocal void update_callback(mDNS *const m, AuthRecord *const rr, RData *oldrd, mDNSu16 oldrdlen)
        {
        mDNSBool external_advertise = (rr->UpdateContext) ? *((mDNSBool *)rr->UpdateContext) : mDNSfalse;
        (void)m; // Unused
        
        // There are three cases.
        //
        // 1. We have updated the primary TXT record of the service
        // 2. We have updated the TXT record that was added to the service using DNSServiceAddRecord
        // 3. We have updated the TXT record that was registered using DNSServiceRegisterRecord
        //
        // external_advertise is set if we have advertised at least once during the initial addition
        // of the record in all of the three cases above. We should have checked for InterfaceID/LocalDomain
        // checks during the first time and hence we don't do any checks here
        if (external_advertise)
                {
                ResourceRecord ext = rr->resrec;
                if (ext.rdlength == oldrdlen && mDNSPlatformMemSame(&ext.rdata->u, &oldrd->u, oldrdlen)) goto exit;
                SetNewRData(&ext, oldrd, oldrdlen);
                external_stop_advertising_service(&ext);
                LogInfo("update_callback: calling external_start_advertising_service");
                external_start_advertising_service(&rr->resrec);
                }
exit:
        if (oldrd != &rr->rdatastorage) freeL("RData/update_callback", oldrd);
        }

mDNSlocal mStatus update_record(AuthRecord *rr, mDNSu16 rdlen, const char *rdata, mDNSu32 ttl, const mDNSBool *const external_advertise)
        {
        mStatus result;
        const int rdsize = rdlen > sizeof(RDataBody) ? rdlen : sizeof(RDataBody);
        RData *newrd = mallocL("RData/update_record", sizeof(RData) - sizeof(RDataBody) + rdsize);
        if (!newrd) FatalError("ERROR: malloc");
        newrd->MaxRDLength = (mDNSu16) rdsize;
        mDNSPlatformMemCopy(&newrd->u, rdata, rdlen);

        // BIND named (name daemon) doesn't allow TXT records with zero-length rdata. This is strictly speaking correct,
        // since RFC 1035 specifies a TXT record as "One or more <character-string>s", not "Zero or more <character-string>s".
        // Since some legacy apps try to create zero-length TXT records, we'll silently correct it here.
        if (rr->resrec.rrtype == kDNSType_TXT && rdlen == 0) { rdlen = 1; newrd->u.txt.c[0] = 0; }
        
        if (external_advertise) rr->UpdateContext = (void *)external_advertise;
        
        result = mDNS_Update(&mDNSStorage, rr, ttl, rdlen, newrd, update_callback);
        if (result) { LogMsg("update_record: Error %d for %s", (int)result, ARDisplayString(&mDNSStorage, rr)); freeL("RData/update_record", newrd); }
        return result;
        }

mDNSlocal mStatus handle_update_request(request_state *request)
        {
        const ipc_msg_hdr *const hdr = &request->hdr;
        mStatus result = mStatus_BadReferenceErr;
        service_instance *i;
        AuthRecord *rr = NULL;

        // get the message data
        DNSServiceFlags flags = get_flags (&request->msgptr, request->msgend);  // flags unused
        mDNSu16         rdlen = get_uint16(&request->msgptr, request->msgend);
        const char     *rdata = get_rdata (&request->msgptr, request->msgend, rdlen);
        mDNSu32         ttl   = get_uint32(&request->msgptr, request->msgend);
        (void)flags; // Unused

        if (!request->msgptr) { LogMsg("%3d: DNSServiceUpdateRecord(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        // If this is a shared connection, check if the operation actually applies to a subordinate request_state object
        if (request->terminate == connection_termination) request = LocateSubordinateRequest(request);

        if (request->terminate == connection_termination)
                {
                // update an individually registered record
                registered_record_entry *reptr;
                for (reptr = request->u.reg_recs; reptr; reptr = reptr->next)
                        {
                        if (reptr->key == hdr->reg_index)
                                {
                                result = update_record(reptr->rr, rdlen, rdata, ttl, &reptr->external_advertise);
                                LogOperation("%3d: DNSServiceUpdateRecord(%##s, %s)",
                                        request->sd, reptr->rr->resrec.name->c, reptr->rr ? DNSTypeName(reptr->rr->resrec.rrtype) : "<NONE>");
                                goto end;
                                }
                        }
                result = mStatus_BadReferenceErr;
                goto end;
                }

        if (request->terminate != regservice_termination_callback)
                { LogMsg("%3d: DNSServiceUpdateRecord(not a registered service ref)", request->sd); return(mStatus_BadParamErr); }

        // For a service registered with zero port, only SRV record is initialized. Don't allow any updates.
        if (mDNSIPPortIsZero(request->u.servicereg.port))
                { LogMsg("%3d: DNSServiceUpdateRecord: updating the record of a service registered with zero port", request->sd); return(mStatus_BadParamErr); }

        // update the saved off TXT data for the service
        if (hdr->reg_index == TXT_RECORD_INDEX)
                {
                if (request->u.servicereg.txtdata)
                        { freeL("service_info txtdata", request->u.servicereg.txtdata); request->u.servicereg.txtdata = NULL; }
                if (rdlen > 0)
                        {
                        request->u.servicereg.txtdata = mallocL("service_info txtdata", rdlen);
                        if (!request->u.servicereg.txtdata) FatalError("ERROR: handle_update_request - malloc");
                        mDNSPlatformMemCopy(request->u.servicereg.txtdata, rdata, rdlen);
                        }
                request->u.servicereg.txtlen = rdlen;
                }

        // update a record from a service record set
        for (i = request->u.servicereg.instances; i; i = i->next)
                {
                if (hdr->reg_index == TXT_RECORD_INDEX) rr = &i->srs.RR_TXT;
                else
                        {
                        ExtraResourceRecord *e;
                        for (e = i->srs.Extras; e; e = e->next)
                                if (e->ClientID == hdr->reg_index) { rr = &e->r; break; }
                        }

                if (!rr) { result = mStatus_BadReferenceErr; goto end; }
                result = update_record(rr, rdlen, rdata, ttl, &i->external_advertise);
                if (result && i->default_local) goto end;
                else result = mStatus_NoError;  // suppress non-local default errors
                }

end:
        if (request->terminate == regservice_termination_callback)
                LogOperation("%3d: DNSServiceUpdateRecord(%##s, %s)", request->sd,
                        (request->u.servicereg.instances) ? request->u.servicereg.instances->srs.RR_SRV.resrec.name->c : NULL,
                        rr ? DNSTypeName(rr->resrec.rrtype) : "<NONE>");

        return(result);
        }

// remove a resource record registered via DNSServiceRegisterRecord()
mDNSlocal mStatus remove_record(request_state *request)
        {
        mStatus err = mStatus_UnknownErr;
        registered_record_entry *e, **ptr = &request->u.reg_recs;

        while (*ptr && (*ptr)->key != request->hdr.reg_index) ptr = &(*ptr)->next;
        if (!*ptr) { LogMsg("%3d: DNSServiceRemoveRecord(%u) not found", request->sd, request->hdr.reg_index); return mStatus_BadReferenceErr; }
        e = *ptr;
        *ptr = e->next; // unlink

        LogOperation("%3d: DNSServiceRemoveRecord(%u %s)", request->sd, e->key, RRDisplayString(&mDNSStorage, &e->rr->resrec));
        e->rr->RecordContext = NULL;
        if (e->external_advertise)
                {
                external_stop_advertising_service(&e->rr->resrec);
                e->external_advertise = mDNSfalse;
                }
        err = mDNS_Deregister(&mDNSStorage, e->rr);             // Will free e->rr for us; we're responsible for freeing e
        if (err)
                {
                LogMsg("ERROR: remove_record, mDNS_Deregister: %d", err);
                freeL("registered_record_entry AuthRecord remove_record", e->rr);
                }
                
        freeL("registered_record_entry remove_record", e);
        return err;
        }

mDNSlocal mStatus remove_extra(const request_state *const request, service_instance *const serv, mDNSu16 *const rrtype)
        {
        mStatus err = mStatus_BadReferenceErr;
        ExtraResourceRecord *ptr;

        for (ptr = serv->srs.Extras; ptr; ptr = ptr->next)              
                {
                if (ptr->ClientID == request->hdr.reg_index) // found match
                        {
                        *rrtype = ptr->r.resrec.rrtype;
                        if (serv->external_advertise) external_stop_advertising_service(&ptr->r.resrec);
                        err = mDNS_RemoveRecordFromService(&mDNSStorage, &serv->srs, ptr, FreeExtraRR, ptr);
                        break;
                        }
                }
        return err;
        }

mDNSlocal mStatus handle_removerecord_request(request_state *request)
        {
        mStatus err = mStatus_BadReferenceErr;
        get_flags(&request->msgptr, request->msgend);   // flags unused

        if (!request->msgptr) { LogMsg("%3d: DNSServiceRemoveRecord(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        // If this is a shared connection, check if the operation actually applies to a subordinate request_state object
        if (request->terminate == connection_termination) request = LocateSubordinateRequest(request);

        if (request->terminate == connection_termination)
                err = remove_record(request);  // remove individually registered record
        else if (request->terminate != regservice_termination_callback)
                { LogMsg("%3d: DNSServiceRemoveRecord(not a registered service ref)", request->sd); return(mStatus_BadParamErr); }
        else
                {
                service_instance *i;
                mDNSu16 rrtype = 0;
                LogOperation("%3d: DNSServiceRemoveRecord(%##s, %s)", request->sd,
                        (request->u.servicereg.instances) ? request->u.servicereg.instances->srs.RR_SRV.resrec.name->c : NULL,
                        rrtype ? DNSTypeName(rrtype) : "<NONE>");
                for (i = request->u.servicereg.instances; i; i = i->next)
                        {
                        err = remove_extra(request, i, &rrtype);
                        if (err && i->default_local) break;
                        else err = mStatus_NoError;  // suppress non-local default errors
                        }
                }

        return(err);
        }

// If there's a comma followed by another character,
// FindFirstSubType overwrites the comma with a nul and returns the pointer to the next character.
// Otherwise, it returns a pointer to the final nul at the end of the string
mDNSlocal char *FindFirstSubType(char *p)
        {
        while (*p)
                {
                if (p[0] == '\\' && p[1]) p += 2;
                else if (p[0] == ',' && p[1]) { *p++ = 0; return(p); }
                else p++;
                }
        return(p);
        }

// If there's a comma followed by another character,
// FindNextSubType overwrites the comma with a nul and returns the pointer to the next character.
// If it finds an illegal unescaped dot in the subtype name, it returns mDNSNULL
// Otherwise, it returns a pointer to the final nul at the end of the string
mDNSlocal char *FindNextSubType(char *p)
        {
        while (*p)
                {
                if (p[0] == '\\' && p[1])               // If escape character
                        p += 2;                                         // ignore following character
                else if (p[0] == ',')                   // If we found a comma
                        {
                        if (p[1]) *p++ = 0;
                        return(p);
                        }
                else if (p[0] == '.')
                        return(mDNSNULL);
                else p++;
                }
        return(p);
        }

// Returns -1 if illegal subtype found
mDNSexport mDNSs32 ChopSubTypes(char *regtype)
        {
        mDNSs32 NumSubTypes = 0;
        char *stp = FindFirstSubType(regtype);
        while (stp && *stp)                                     // If we found a comma...
                {
                if (*stp == ',') return(-1);
                NumSubTypes++;
                stp = FindNextSubType(stp);
                }
        if (!stp) return(-1);
        return(NumSubTypes);
        }

mDNSexport AuthRecord *AllocateSubTypes(mDNSs32 NumSubTypes, char *p)
        {
        AuthRecord *st = mDNSNULL;
        if (NumSubTypes)
                {
                mDNSs32 i;
                st = mallocL("ServiceSubTypes", NumSubTypes * sizeof(AuthRecord));
                if (!st) return(mDNSNULL);
                for (i = 0; i < NumSubTypes; i++)
                        {
                        mDNS_SetupResourceRecord(&st[i], mDNSNULL, mDNSInterface_Any, kDNSQType_ANY, kStandardTTL, 0, AuthRecordAny, mDNSNULL, mDNSNULL);
                        while (*p) p++;
                        p++;
                        if (!MakeDomainNameFromDNSNameString(&st[i].namestorage, p))
                                { freeL("ServiceSubTypes", st); return(mDNSNULL); }
                        }
                }
        return(st);
        }

mDNSlocal mStatus register_service_instance(request_state *request, const domainname *domain)
        {
        service_instance **ptr, *instance;
        const int extra_size = (request->u.servicereg.txtlen > sizeof(RDataBody)) ? (request->u.servicereg.txtlen - sizeof(RDataBody)) : 0;
        const mDNSBool DomainIsLocal = SameDomainName(domain, &localdomain);
        mStatus result;
        mDNSInterfaceID interfaceID = request->u.servicereg.InterfaceID;
        mDNSu32 regFlags = 0;

        if (interfaceID == mDNSInterface_P2P)
                {
                interfaceID = mDNSInterface_Any;
                regFlags |= regFlagIncludeP2P;
                }
        else if (request->flags & kDNSServiceFlagsIncludeP2P)
                regFlags |= regFlagIncludeP2P;

        // client guarantees that record names are unique
        if (request->flags & kDNSServiceFlagsForce)
                regFlags |= regFlagKnownUnique;

        // If the client specified an interface, but no domain, then we honor the specified interface for the "local" (mDNS)
        // registration but for the wide-area registrations we don't (currently) have any concept of a wide-area unicast
        // registrations scoped to a specific interface, so for the automatic domains we add we must *not* specify an interface.
        // (Specifying an interface with an apparently wide-area domain (i.e. something other than "local")
        // currently forces the registration to use mDNS multicast despite the apparently wide-area domain.)
        if (request->u.servicereg.default_domain && !DomainIsLocal) interfaceID = mDNSInterface_Any;

        for (ptr = &request->u.servicereg.instances; *ptr; ptr = &(*ptr)->next)
                {
                if (SameDomainName(&(*ptr)->domain, domain))
                        {
                        LogMsg("register_service_instance: domain %##s already registered for %#s.%##s",
                                domain->c, &request->u.servicereg.name, &request->u.servicereg.type);
                        return mStatus_AlreadyRegistered;
                        }
                }

        if (mDNSStorage.KnownBugs & mDNS_KnownBug_LimitedIPv6)
                {
                // Special-case hack: On Mac OS X 10.6.x and earlier we don't advertise SMB service in AutoTunnel domains,
                // because AutoTunnel services have to support IPv6, and in Mac OS X 10.6.x the SMB server does not.
                // <rdar://problem/5482322> BTMM: Don't advertise SMB with BTMM because it doesn't support IPv6
                if (SameDomainName(&request->u.servicereg.type, (const domainname *) "\x4" "_smb" "\x4" "_tcp"))
                        {
                        DomainAuthInfo *AuthInfo = GetAuthInfoForName(&mDNSStorage, domain);
                        if (AuthInfo && AuthInfo->AutoTunnel) return(kDNSServiceErr_Unsupported);
                        }
                }

        instance = mallocL("service_instance", sizeof(*instance) + extra_size);
        if (!instance) { my_perror("ERROR: malloc"); return mStatus_NoMemoryErr; }

        instance->next                                                  = mDNSNULL;
        instance->request                                               = request;
        instance->subtypes                                              = AllocateSubTypes(request->u.servicereg.num_subtypes, request->u.servicereg.type_as_string);
        instance->renameonmemfree                               = 0;
        instance->clientnotified                                = mDNSfalse;
        instance->default_local                                 = (request->u.servicereg.default_domain && DomainIsLocal);
        instance->external_advertise            = mDNSfalse;
        AssignDomainName(&instance->domain, domain);

        if (request->u.servicereg.num_subtypes && !instance->subtypes)
                { unlink_and_free_service_instance(instance); instance = NULL; FatalError("ERROR: malloc"); }

        result = mDNS_RegisterService(&mDNSStorage, &instance->srs,
                &request->u.servicereg.name, &request->u.servicereg.type, domain,
                request->u.servicereg.host.c[0] ? &request->u.servicereg.host : NULL,
                request->u.servicereg.port,
                request->u.servicereg.txtdata, request->u.servicereg.txtlen,
                instance->subtypes, request->u.servicereg.num_subtypes,
                interfaceID, regservice_callback, instance, regFlags);

        if (!result)
                {
                *ptr = instance;                // Append this to the end of our request->u.servicereg.instances list
                LogOperation("%3d: DNSServiceRegister(%##s, %u) ADDED",
                        instance->request->sd, instance->srs.RR_SRV.resrec.name->c, mDNSVal16(request->u.servicereg.port));
                }
        else
                {
                LogMsg("register_service_instance %#s.%##s%##s error %d",
                        &request->u.servicereg.name, &request->u.servicereg.type, domain->c, result);
                unlink_and_free_service_instance(instance);
                }

        return result;
        }

mDNSlocal void udsserver_default_reg_domain_changed(const DNameListElem *const d, const mDNSBool add)
        {
        request_state *request;

#if APPLE_OSX_mDNSResponder
        machserver_automatic_registration_domain_changed(&d->name, add);
#endif // APPLE_OSX_mDNSResponder

        LogMsg("%s registration domain %##s", add ? "Adding" : "Removing", d->name.c);
        for (request = all_requests; request; request = request->next)
                {
                if (request->terminate != regservice_termination_callback) continue;
                if (!request->u.servicereg.default_domain) continue;
                if (!d->uid || SystemUID(request->uid) || request->uid == d->uid)
                        {
                        service_instance **ptr = &request->u.servicereg.instances;
                        while (*ptr && !SameDomainName(&(*ptr)->domain, &d->name)) ptr = &(*ptr)->next;
                        if (add)
                                {
                                // If we don't already have this domain in our list for this registration, add it now
                                if (!*ptr) register_service_instance(request, &d->name);
                                else debugf("udsserver_default_reg_domain_changed %##s already in list, not re-adding", &d->name);
                                }
                        else
                                {
                                // Normally we should not fail to find the specified instance
                                // One case where this can happen is if a uDNS update fails for some reason,
                                // and regservice_callback then calls unlink_and_free_service_instance and disposes of that instance.
                                if (!*ptr)
                                        LogMsg("udsserver_default_reg_domain_changed domain %##s not found for service %#s type %s",
                                                &d->name, request->u.servicereg.name.c, request->u.servicereg.type_as_string);
                                else
                                        {
                                        DNameListElem *p;
                                        for (p = AutoRegistrationDomains; p; p=p->next)
                                                if (!p->uid || SystemUID(request->uid) || request->uid == p->uid)
                                                        if (SameDomainName(&d->name, &p->name)) break;
                                        if (p) debugf("udsserver_default_reg_domain_changed %##s still in list, not removing", &d->name);
                                        else
                                                {
                                                mStatus err;
                                                service_instance *si = *ptr;
                                                *ptr = si->next;
                                                if (si->clientnotified) SendServiceRemovalNotification(&si->srs); // Do this *before* clearing si->request backpointer
                                                // Now that we've cut this service_instance from the list, we MUST clear the si->request backpointer.
                                                // Otherwise what can happen is this: While our mDNS_DeregisterService is in the
                                                // process of completing asynchronously, the client cancels the entire operation, so
                                                // regservice_termination_callback then runs through the whole list deregistering each
                                                // instance, clearing the backpointers, and then disposing the parent request_state object.
                                                // However, because this service_instance isn't in the list any more, regservice_termination_callback
                                                // has no way to find it and clear its backpointer, and then when our mDNS_DeregisterService finally
                                                // completes later with a mStatus_MemFree message, it calls unlink_and_free_service_instance() with
                                                // a service_instance with a stale si->request backpointer pointing to memory that's already been freed.
                                                si->request = NULL;
                                                err = mDNS_DeregisterService(&mDNSStorage, &si->srs);
                                                if (err) { LogMsg("udsserver_default_reg_domain_changed err %d", err); unlink_and_free_service_instance(si); }
                                                }
                                        }
                                }
                        }
                }
        }

mDNSlocal mStatus handle_regservice_request(request_state *request)
        {
        char name[256]; // Lots of spare space for extra-long names that we'll auto-truncate down to 63 bytes
        char domain[MAX_ESCAPED_DOMAIN_NAME], host[MAX_ESCAPED_DOMAIN_NAME];
        char type_as_string[MAX_ESCAPED_DOMAIN_NAME];
        domainname d, srv;
        mStatus err;

        DNSServiceFlags flags = get_flags(&request->msgptr, request->msgend);
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        mDNSInterfaceID InterfaceID = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        if (interfaceIndex && !InterfaceID)
                { LogMsg("ERROR: handle_regservice_request - Couldn't find interfaceIndex %d", interfaceIndex); return(mStatus_BadParamErr); }

        if (get_string(&request->msgptr, request->msgend, name, sizeof(name)) < 0 ||
                get_string(&request->msgptr, request->msgend, type_as_string, MAX_ESCAPED_DOMAIN_NAME) < 0 ||
                get_string(&request->msgptr, request->msgend, domain, MAX_ESCAPED_DOMAIN_NAME) < 0 ||
                get_string(&request->msgptr, request->msgend, host, MAX_ESCAPED_DOMAIN_NAME) < 0)
                { LogMsg("ERROR: handle_regservice_request - Couldn't read name/regtype/domain"); return(mStatus_BadParamErr); }

        request->flags = flags;
        request->u.servicereg.InterfaceID = InterfaceID;
        request->u.servicereg.instances = NULL;
        request->u.servicereg.txtlen  = 0;
        request->u.servicereg.txtdata = NULL;
        mDNSPlatformStrCopy(request->u.servicereg.type_as_string, type_as_string);

        if (request->msgptr + 2 > request->msgend) request->msgptr = NULL;
        else
                {
                request->u.servicereg.port.b[0] = *request->msgptr++;
                request->u.servicereg.port.b[1] = *request->msgptr++;
                }

        request->u.servicereg.txtlen = get_uint16(&request->msgptr, request->msgend);
        if (request->u.servicereg.txtlen)
                {
                request->u.servicereg.txtdata = mallocL("service_info txtdata", request->u.servicereg.txtlen);
                if (!request->u.servicereg.txtdata) FatalError("ERROR: handle_regservice_request - malloc");
                mDNSPlatformMemCopy(request->u.servicereg.txtdata, get_rdata(&request->msgptr, request->msgend, request->u.servicereg.txtlen), request->u.servicereg.txtlen);
                }

        if (!request->msgptr) { LogMsg("%3d: DNSServiceRegister(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        // Check for sub-types after the service type
        request->u.servicereg.num_subtypes = ChopSubTypes(request->u.servicereg.type_as_string);        // Note: Modifies regtype string to remove trailing subtypes
        if (request->u.servicereg.num_subtypes < 0)
                { LogMsg("ERROR: handle_regservice_request - ChopSubTypes failed %s", request->u.servicereg.type_as_string); return(mStatus_BadParamErr); }

        // Don't try to construct "domainname t" until *after* ChopSubTypes has worked its magic
        if (!*request->u.servicereg.type_as_string || !MakeDomainNameFromDNSNameString(&request->u.servicereg.type, request->u.servicereg.type_as_string))
                { LogMsg("ERROR: handle_regservice_request - type_as_string bad %s", request->u.servicereg.type_as_string); return(mStatus_BadParamErr); }

        if (!name[0])
                {
                request->u.servicereg.name = mDNSStorage.nicelabel;
                request->u.servicereg.autoname = mDNStrue;
                }
        else
                {
                // If the client is allowing AutoRename, then truncate name to legal length before converting it to a DomainLabel
                if ((flags & kDNSServiceFlagsNoAutoRename) == 0)
                        {
                        int newlen = TruncateUTF8ToLength((mDNSu8*)name, mDNSPlatformStrLen(name), MAX_DOMAIN_LABEL);
                        name[newlen] = 0;
                        }
                if (!MakeDomainLabelFromLiteralString(&request->u.servicereg.name, name))
                        { LogMsg("ERROR: handle_regservice_request - name bad %s", name); return(mStatus_BadParamErr); }
                request->u.servicereg.autoname = mDNSfalse;
                }

        if (*domain)
                {
                request->u.servicereg.default_domain = mDNSfalse;
                if (!MakeDomainNameFromDNSNameString(&d, domain))
                        { LogMsg("ERROR: handle_regservice_request - domain bad %s", domain); return(mStatus_BadParamErr); }
                }
        else
                {
                request->u.servicereg.default_domain = mDNStrue;
                MakeDomainNameFromDNSNameString(&d, "local.");
                }

        if (!ConstructServiceName(&srv, &request->u.servicereg.name, &request->u.servicereg.type, &d))
                {
                LogMsg("ERROR: handle_regservice_request - Couldn't ConstructServiceName from, “%#s” “%##s” “%##s”",
                        request->u.servicereg.name.c, request->u.servicereg.type.c, d.c); return(mStatus_BadParamErr);
                }

        if (!MakeDomainNameFromDNSNameString(&request->u.servicereg.host, host))
                { LogMsg("ERROR: handle_regservice_request - host bad %s", host); return(mStatus_BadParamErr); }
        request->u.servicereg.autorename       = (flags & kDNSServiceFlagsNoAutoRename    ) == 0;
        request->u.servicereg.allowremotequery = (flags & kDNSServiceFlagsAllowRemoteQuery) != 0;

        // Some clients use mDNS for lightweight copy protection, registering a pseudo-service with
        // a port number of zero. When two instances of the protected client are allowed to run on one
        // machine, we don't want to see misleading "Bogus client" messages in syslog and the console.
        if (!mDNSIPPortIsZero(request->u.servicereg.port))
                {
                int count = CountExistingRegistrations(&srv, request->u.servicereg.port);
                if (count)
                        LogMsg("Client application registered %d identical instances of service %##s port %u.",
                                count+1, srv.c, mDNSVal16(request->u.servicereg.port));
                }

        LogOperation("%3d: DNSServiceRegister(%X, %d, \"%s\", \"%s\", \"%s\", \"%s\", %u) START",
                request->sd, flags, interfaceIndex, name, request->u.servicereg.type_as_string, domain, host, mDNSVal16(request->u.servicereg.port));

        // We need to unconditionally set request->terminate, because even if we didn't successfully
        // start any registrations right now, subsequent configuration changes may cause successful
        // registrations to be added, and we'll need to cancel them before freeing this memory.
        // We also need to set request->terminate first, before adding additional service instances,
        // because the uds_validatelists uses the request->terminate function pointer to determine
        // what kind of request this is, and therefore what kind of list validation is required.
        request->terminate = regservice_termination_callback;

        err = register_service_instance(request, &d);

#if 0
        err = AuthorizedDomain(request, &d, AutoRegistrationDomains) ? register_service_instance(request, &d) : mStatus_NoError;
#endif
        if (!err)
                {
                if (request->u.servicereg.autoname) UpdateDeviceInfoRecord(&mDNSStorage);

                if (!*domain)
                        {
                        DNameListElem *ptr;
                        // Note that we don't report errors for non-local, non-explicit domains
                        for (ptr = AutoRegistrationDomains; ptr; ptr = ptr->next)
                                if (!ptr->uid || SystemUID(request->uid) || request->uid == ptr->uid)
                                        register_service_instance(request, &ptr->name);
                        }
                }

        return(err);
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceBrowse
#endif

mDNSlocal void FoundInstance(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
        {
        const DNSServiceFlags flags = AddRecord ? kDNSServiceFlagsAdd : 0;
        request_state *req = question->QuestionContext;
        reply_state *rep;
        (void)m; // Unused

        if (answer->rrtype != kDNSType_PTR)
                { LogMsg("%3d: FoundInstance: Should not be called with rrtype %d (not a PTR record)", req->sd, answer->rrtype); return; }

        if (GenerateNTDResponse(&answer->rdata->u.name, answer->InterfaceID, req, &rep, browse_reply_op, flags, mStatus_NoError) != mStatus_NoError)
                {
                if (SameDomainName(&req->u.browser.regtype, (const domainname*)"\x09_services\x07_dns-sd\x04_udp"))
                        {
                        // Special support to enable the DNSServiceBrowse call made by Bonjour Browser
                        // Remove after Bonjour Browser is updated to use DNSServiceQueryRecord instead of DNSServiceBrowse
                        GenerateBonjourBrowserResponse(&answer->rdata->u.name, answer->InterfaceID, req, &rep, browse_reply_op, flags, mStatus_NoError);
                        goto bonjourbrowserhack;
                        }

                LogMsg("%3d: FoundInstance: %##s PTR %##s received from network is not valid DNS-SD service pointer",
                        req->sd, answer->name->c, answer->rdata->u.name.c);
                return;
                }

bonjourbrowserhack:

        LogOperation("%3d: DNSServiceBrowse(%##s, %s) RESULT %s %d: %s",
                req->sd, question->qname.c, DNSTypeName(question->qtype), AddRecord ? "Add" : "Rmv",
                mDNSPlatformInterfaceIndexfromInterfaceID(m, answer->InterfaceID, mDNSfalse), RRDisplayString(m, answer));

        append_reply(req, rep);
        }

mDNSlocal mStatus add_domain_to_browser(request_state *info, const domainname *d)
        {
        browser_t *b, *p;
        mStatus err;

        for (p = info->u.browser.browsers; p; p = p->next)
                {
                if (SameDomainName(&p->domain, d))
                        { debugf("add_domain_to_browser %##s already in list", d->c); return mStatus_AlreadyRegistered; }
                }

        b = mallocL("browser_t", sizeof(*b));
        if (!b) return mStatus_NoMemoryErr;
        AssignDomainName(&b->domain, d);
        err = mDNS_StartBrowse(&mDNSStorage, &b->q,
                &info->u.browser.regtype, d, info->u.browser.interface_id, info->u.browser.ForceMCast, FoundInstance, info);
        if (err)
                {
                LogMsg("mDNS_StartBrowse returned %d for type %##s domain %##s", err, info->u.browser.regtype.c, d->c);
                freeL("browser_t/add_domain_to_browser", b);
                }
        else
                {
                b->next = info->u.browser.browsers;
                info->u.browser.browsers = b;
                LogOperation("%3d: DNSServiceBrowse(%##s) START", info->sd, b->q.qname.c);
                if (info->u.browser.interface_id == mDNSInterface_P2P || (!info->u.browser.interface_id && SameDomainName(&b->domain, &localdomain) && (info->flags & kDNSServiceFlagsIncludeP2P)))
                        {
                        domainname tmp;
                        ConstructServiceName(&tmp, NULL, &info->u.browser.regtype, &b->domain);
                        LogInfo("add_domain_to_browser: calling external_start_browsing_for_service()");
                        external_start_browsing_for_service(&mDNSStorage, &tmp, kDNSType_PTR);
                        }
                }
        return err;
        }

mDNSlocal void browse_termination_callback(request_state *info)
        {
        while (info->u.browser.browsers)
                {
                browser_t *ptr = info->u.browser.browsers;
                
                if (info->u.browser.interface_id == mDNSInterface_P2P || (!info->u.browser.interface_id && SameDomainName(&ptr->domain, &localdomain) && (info->flags & kDNSServiceFlagsIncludeP2P)))
                        {
                        domainname tmp;
                        ConstructServiceName(&tmp, NULL, &info->u.browser.regtype, &ptr->domain);
                        LogInfo("browse_termination_callback: calling external_stop_browsing_for_service()");
                        external_stop_browsing_for_service(&mDNSStorage, &tmp, kDNSType_PTR);
                        }
                
                info->u.browser.browsers = ptr->next;
                LogOperation("%3d: DNSServiceBrowse(%##s) STOP", info->sd, ptr->q.qname.c);
                mDNS_StopBrowse(&mDNSStorage, &ptr->q);  // no need to error-check result
                freeL("browser_t/browse_termination_callback", ptr);
                }
        }

mDNSlocal void udsserver_automatic_browse_domain_changed(const DNameListElem *const d, const mDNSBool add)
        {
        request_state *request;
        debugf("udsserver_automatic_browse_domain_changed: %s default browse domain %##s", add ? "Adding" : "Removing", d->name.c);

#if APPLE_OSX_mDNSResponder
        machserver_automatic_browse_domain_changed(&d->name, add);
#endif // APPLE_OSX_mDNSResponder

        for (request = all_requests; request; request = request->next)
                {
                if (request->terminate != browse_termination_callback) continue;        // Not a browse operation
                if (!request->u.browser.default_domain) continue;                                       // Not an auto-browse operation
                if (!d->uid || SystemUID(request->uid) || request->uid == d->uid)
                        {
                        browser_t **ptr = &request->u.browser.browsers;
                        while (*ptr && !SameDomainName(&(*ptr)->domain, &d->name)) ptr = &(*ptr)->next;
                        if (add)
                                {
                                // If we don't already have this domain in our list for this browse operation, add it now
                                if (!*ptr) add_domain_to_browser(request, &d->name);
                                else debugf("udsserver_automatic_browse_domain_changed %##s already in list, not re-adding", &d->name);
                                }
                        else
                                {
                                if (!*ptr) LogMsg("udsserver_automatic_browse_domain_changed ERROR %##s not found", &d->name);
                                else
                                        {
                                        DNameListElem *p;
                                        for (p = AutoBrowseDomains; p; p=p->next)
                                                if (!p->uid || SystemUID(request->uid) || request->uid == p->uid)
                                                        if (SameDomainName(&d->name, &p->name)) break;
                                        if (p) debugf("udsserver_automatic_browse_domain_changed %##s still in list, not removing", &d->name);
                                        else
                                                {
                                                browser_t *rem = *ptr;
                                                *ptr = (*ptr)->next;
                                                mDNS_StopQueryWithRemoves(&mDNSStorage, &rem->q);
                                                freeL("browser_t/udsserver_automatic_browse_domain_changed", rem);
                                                }
                                        }
                                }
                        }
                }
        }

mDNSlocal void FreeARElemCallback(mDNS *const m, AuthRecord *const rr, mStatus result)
        {
        (void)m;  // unused
        if (result == mStatus_MemFree)
                {
                // On shutdown, mDNS_Close automatically deregisters all records
                // Since in this case no one has called DeregisterLocalOnlyDomainEnumPTR to cut the record
                // from the LocalDomainEnumRecords list, we do this here before we free the memory.
                // (This should actually no longer be necessary, now that we do the proper cleanup in
                // udsserver_exit. To confirm this, we'll log an error message if we do find a record that
                // hasn't been cut from the list yet. If these messages don't appear, we can delete this code.)
                ARListElem **ptr = &LocalDomainEnumRecords;
                while (*ptr && &(*ptr)->ar != rr) ptr = &(*ptr)->next;
                if (*ptr) { *ptr = (*ptr)->next; LogMsg("FreeARElemCallback: Have to cut %s", ARDisplayString(m, rr)); }
                mDNSPlatformMemFree(rr->RecordContext);
                }
        }

// RegisterLocalOnlyDomainEnumPTR and DeregisterLocalOnlyDomainEnumPTR largely duplicate code in
// "FoundDomain" in uDNS.c for creating and destroying these special mDNSInterface_LocalOnly records.
// We may want to turn the common code into a subroutine.

mDNSlocal void RegisterLocalOnlyDomainEnumPTR(mDNS *m, const domainname *d, int type)
        {
        // allocate/register legacy and non-legacy _browse PTR record
        mStatus err;
        ARListElem *ptr = mDNSPlatformMemAllocate(sizeof(*ptr));

        debugf("Incrementing %s refcount for %##s",
                (type == mDNS_DomainTypeBrowse         ) ? "browse domain   " :
                (type == mDNS_DomainTypeRegistration   ) ? "registration dom" :
                (type == mDNS_DomainTypeBrowseAutomatic) ? "automatic browse" : "?", d->c);

        mDNS_SetupResourceRecord(&ptr->ar, mDNSNULL, mDNSInterface_LocalOnly, kDNSType_PTR, 7200, kDNSRecordTypeShared, AuthRecordLocalOnly, FreeARElemCallback, ptr);
        MakeDomainNameFromDNSNameString(&ptr->ar.namestorage, mDNS_DomainTypeNames[type]);
        AppendDNSNameString            (&ptr->ar.namestorage, "local");
        AssignDomainName(&ptr->ar.resrec.rdata->u.name, d);
        err = mDNS_Register(m, &ptr->ar);
        if (err)
                {
                LogMsg("SetSCPrefsBrowseDomain: mDNS_Register returned error %d", err);
                mDNSPlatformMemFree(ptr);
                }
        else
                {
                ptr->next = LocalDomainEnumRecords;
                LocalDomainEnumRecords = ptr;
                }
        }

mDNSlocal void DeregisterLocalOnlyDomainEnumPTR(mDNS *m, const domainname *d, int type)
        {
        ARListElem **ptr = &LocalDomainEnumRecords;
        domainname lhs; // left-hand side of PTR, for comparison

        debugf("Decrementing %s refcount for %##s",
                (type == mDNS_DomainTypeBrowse         ) ? "browse domain   " :
                (type == mDNS_DomainTypeRegistration   ) ? "registration dom" :
                (type == mDNS_DomainTypeBrowseAutomatic) ? "automatic browse" : "?", d->c);

        MakeDomainNameFromDNSNameString(&lhs, mDNS_DomainTypeNames[type]);
        AppendDNSNameString            (&lhs, "local");

        while (*ptr)
                {
                if (SameDomainName(&(*ptr)->ar.resrec.rdata->u.name, d) && SameDomainName((*ptr)->ar.resrec.name, &lhs))
                        {
                        ARListElem *rem = *ptr;
                        *ptr = (*ptr)->next;
                        mDNS_Deregister(m, &rem->ar);
                        return;
                        }
                else ptr = &(*ptr)->next;
                }
        }

mDNSlocal void AddAutoBrowseDomain(const mDNSu32 uid, const domainname *const name)
        {
        DNameListElem *new = mDNSPlatformMemAllocate(sizeof(DNameListElem));
        if (!new) { LogMsg("ERROR: malloc"); return; }
        AssignDomainName(&new->name, name);
        new->uid = uid;
        new->next = AutoBrowseDomains;
        AutoBrowseDomains = new;
        udsserver_automatic_browse_domain_changed(new, mDNStrue);
        }

mDNSlocal void RmvAutoBrowseDomain(const mDNSu32 uid, const domainname *const name)
        {
        DNameListElem **p = &AutoBrowseDomains;
        while (*p && (!SameDomainName(&(*p)->name, name) || (*p)->uid != uid)) p = &(*p)->next;
        if (!*p) LogMsg("RmvAutoBrowseDomain: Got remove event for domain %##s not in list", name->c);
        else
                {
                DNameListElem *ptr = *p;
                *p = ptr->next;
                udsserver_automatic_browse_domain_changed(ptr, mDNSfalse);
                mDNSPlatformMemFree(ptr);
                }
        }

mDNSlocal void SetPrefsBrowseDomains(mDNS *m, DNameListElem *browseDomains, mDNSBool add)
        {
        DNameListElem *d;
        for (d = browseDomains; d; d = d->next)
                {
                if (add)
                        {
                        RegisterLocalOnlyDomainEnumPTR(m, &d->name, mDNS_DomainTypeBrowse);
                        AddAutoBrowseDomain(d->uid, &d->name);
                        }
                else
                        {
                        DeregisterLocalOnlyDomainEnumPTR(m, &d->name, mDNS_DomainTypeBrowse);
                        RmvAutoBrowseDomain(d->uid, &d->name);
                        }
                }
        }

mDNSlocal void UpdateDeviceInfoRecord(mDNS *const m)
        {
        int num_autoname = 0;
        request_state *req;
        for (req = all_requests; req; req = req->next)
                if (req->terminate == regservice_termination_callback && req->u.servicereg.autoname)
                        num_autoname++;

        // If DeviceInfo record is currently registered, see if we need to deregister it
        if (m->DeviceInfo.resrec.RecordType != kDNSRecordTypeUnregistered)
                if (num_autoname == 0 || !SameDomainLabelCS(m->DeviceInfo.resrec.name->c, m->nicelabel.c))
                        {
                        LogOperation("UpdateDeviceInfoRecord Deregister %##s", m->DeviceInfo.resrec.name);
                        mDNS_Deregister(m, &m->DeviceInfo);
                        }

        // If DeviceInfo record is not currently registered, see if we need to register it
        if (m->DeviceInfo.resrec.RecordType == kDNSRecordTypeUnregistered)
                if (num_autoname > 0)
                        {
                        mDNSu8 len = m->HIHardware.c[0] < 255 - 6 ? m->HIHardware.c[0] : 255 - 6;
                        mDNS_SetupResourceRecord(&m->DeviceInfo, mDNSNULL, mDNSNULL, kDNSType_TXT, kStandardTTL, kDNSRecordTypeAdvisory, AuthRecordAny, mDNSNULL, mDNSNULL);
                        ConstructServiceName(&m->DeviceInfo.namestorage, &m->nicelabel, &DeviceInfoName, &localdomain);
                        mDNSPlatformMemCopy(m->DeviceInfo.resrec.rdata->u.data + 1, "model=", 6);
                        mDNSPlatformMemCopy(m->DeviceInfo.resrec.rdata->u.data + 7, m->HIHardware.c + 1, len);
                        m->DeviceInfo.resrec.rdata->u.data[0] = 6 + len;        // "model=" plus the device string
                        m->DeviceInfo.resrec.rdlength         = 7 + len;        // One extra for the length byte at the start of the string
                        LogOperation("UpdateDeviceInfoRecord   Register %##s", m->DeviceInfo.resrec.name);
                        mDNS_Register(m, &m->DeviceInfo);
                        }
        }

mDNSexport void udsserver_handle_configchange(mDNS *const m)
        {
        request_state *req;
        service_instance *ptr;
        DNameListElem *RegDomains = NULL;
        DNameListElem *BrowseDomains = NULL;
        DNameListElem *p;

        UpdateDeviceInfoRecord(m);

        // For autoname services, see if the default service name has changed, necessitating an automatic update
        for (req = all_requests; req; req = req->next)
                if (req->terminate == regservice_termination_callback)
                        if (req->u.servicereg.autoname && !SameDomainLabelCS(req->u.servicereg.name.c, m->nicelabel.c))
                                {
                                req->u.servicereg.name = m->nicelabel;
                                for (ptr = req->u.servicereg.instances; ptr; ptr = ptr->next)
                                        {
                                        ptr->renameonmemfree = 1;
                                        if (ptr->clientnotified) SendServiceRemovalNotification(&ptr->srs);
                                        LogInfo("udsserver_handle_configchange: Calling deregister for Service %##s", ptr->srs.RR_PTR.resrec.name->c);
                                        if (mDNS_DeregisterService_drt(m, &ptr->srs, mDNS_Dereg_rapid))
                                                regservice_callback(m, &ptr->srs, mStatus_MemFree);     // If service deregistered already, we can re-register immediately
                                        }
                                }

        // Let the platform layer get the current DNS information
        mDNS_Lock(m);
        mDNSPlatformSetDNSConfig(m, mDNSfalse, mDNSfalse, mDNSNULL, &RegDomains, &BrowseDomains);
        mDNS_Unlock(m);

        // Any automatic registration domains are also implicitly automatic browsing domains
        if (RegDomains) SetPrefsBrowseDomains(m, RegDomains, mDNStrue);                                                         // Add the new list first
        if (AutoRegistrationDomains) SetPrefsBrowseDomains(m, AutoRegistrationDomains, mDNSfalse);      // Then clear the old list

        // Add any new domains not already in our AutoRegistrationDomains list
        for (p=RegDomains; p; p=p->next)
                {
                DNameListElem **pp = &AutoRegistrationDomains;
                while (*pp && ((*pp)->uid != p->uid || !SameDomainName(&(*pp)->name, &p->name))) pp = &(*pp)->next;
                if (!*pp)               // If not found in our existing list, this is a new default registration domain
                        {
                        RegisterLocalOnlyDomainEnumPTR(m, &p->name, mDNS_DomainTypeRegistration);
                        udsserver_default_reg_domain_changed(p, mDNStrue);
                        }
                else                    // else found same domainname in both old and new lists, so no change, just delete old copy
                        {
                        DNameListElem *del = *pp;
                        *pp = (*pp)->next;
                        mDNSPlatformMemFree(del);
                        }
                }

        // Delete any domains in our old AutoRegistrationDomains list that are now gone
        while (AutoRegistrationDomains)
                {
                DNameListElem *del = AutoRegistrationDomains;
                AutoRegistrationDomains = AutoRegistrationDomains->next;                // Cut record from list FIRST,
                DeregisterLocalOnlyDomainEnumPTR(m, &del->name, mDNS_DomainTypeRegistration);
                udsserver_default_reg_domain_changed(del, mDNSfalse);                   // before calling udsserver_default_reg_domain_changed()
                mDNSPlatformMemFree(del);
                }

        // Now we have our new updated automatic registration domain list
        AutoRegistrationDomains = RegDomains;

        // Add new browse domains to internal list
        if (BrowseDomains) SetPrefsBrowseDomains(m, BrowseDomains, mDNStrue);

        // Remove old browse domains from internal list
        if (SCPrefBrowseDomains)
                {
                SetPrefsBrowseDomains(m, SCPrefBrowseDomains, mDNSfalse);
                while (SCPrefBrowseDomains)
                        {
                        DNameListElem *fptr = SCPrefBrowseDomains;
                        SCPrefBrowseDomains = SCPrefBrowseDomains->next;
                        mDNSPlatformMemFree(fptr);
                        }
                }

        // Replace the old browse domains array with the new array
        SCPrefBrowseDomains = BrowseDomains;
        }

mDNSlocal void AutomaticBrowseDomainChange(mDNS *const m, DNSQuestion *q, const ResourceRecord *const answer, QC_result AddRecord)
        {
        (void)m; // unused;
        (void)q; // unused

        LogOperation("AutomaticBrowseDomainChange: %s automatic browse domain %##s",
                AddRecord ? "Adding" : "Removing", answer->rdata->u.name.c);

        if (AddRecord) AddAutoBrowseDomain(0, &answer->rdata->u.name);
        else           RmvAutoBrowseDomain(0, &answer->rdata->u.name);
        }

mDNSlocal mStatus handle_browse_request(request_state *request)
        {
        char regtype[MAX_ESCAPED_DOMAIN_NAME], domain[MAX_ESCAPED_DOMAIN_NAME];
        domainname typedn, d, temp;
        mDNSs32 NumSubTypes;
        mStatus err = mStatus_NoError;

        DNSServiceFlags flags = get_flags(&request->msgptr, request->msgend);
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        mDNSInterfaceID InterfaceID = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        if (interfaceIndex && !InterfaceID) return(mStatus_BadParamErr);

        if (get_string(&request->msgptr, request->msgend, regtype, MAX_ESCAPED_DOMAIN_NAME) < 0 ||
                get_string(&request->msgptr, request->msgend, domain, MAX_ESCAPED_DOMAIN_NAME) < 0) return(mStatus_BadParamErr);

        if (!request->msgptr) { LogMsg("%3d: DNSServiceBrowse(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        if (domain[0] == '\0') uDNS_SetupSearchDomains(&mDNSStorage, UDNS_START_WAB_QUERY);

        request->flags = flags;
        typedn.c[0] = 0;
        NumSubTypes = ChopSubTypes(regtype);    // Note: Modifies regtype string to remove trailing subtypes
        if (NumSubTypes < 0 || NumSubTypes > 1) return(mStatus_BadParamErr);
        if (NumSubTypes == 1 && !AppendDNSNameString(&typedn, regtype + strlen(regtype) + 1)) return(mStatus_BadParamErr);

        if (!regtype[0] || !AppendDNSNameString(&typedn, regtype)) return(mStatus_BadParamErr);

        if (!MakeDomainNameFromDNSNameString(&temp, regtype)) return(mStatus_BadParamErr);
        // For over-long service types, we only allow domain "local"
        if (temp.c[0] > 15 && domain[0] == 0) mDNSPlatformStrCopy(domain, "local.");

        // Set up browser info
        request->u.browser.ForceMCast = (flags & kDNSServiceFlagsForceMulticast) != 0;
        request->u.browser.interface_id = InterfaceID;
        AssignDomainName(&request->u.browser.regtype, &typedn);
        request->u.browser.default_domain = !domain[0];
        request->u.browser.browsers = NULL;

        LogOperation("%3d: DNSServiceBrowse(%X, %d, \"%##s\", \"%s\") START", 
                        request->sd, request->flags, interfaceIndex, request->u.browser.regtype.c, domain);

        // We need to unconditionally set request->terminate, because even if we didn't successfully
        // start any browses right now, subsequent configuration changes may cause successful
        // browses to be added, and we'll need to cancel them before freeing this memory.
        request->terminate = browse_termination_callback;

        if (domain[0])
                {
                if (!MakeDomainNameFromDNSNameString(&d, domain)) return(mStatus_BadParamErr);
                err = add_domain_to_browser(request, &d);
#if 0
                err = AuthorizedDomain(request, &d, AutoBrowseDomains) ? add_domain_to_browser(request, &d) : mStatus_NoError;
#endif
                }
        else
                {
                DNameListElem *sdom;
                for (sdom = AutoBrowseDomains; sdom; sdom = sdom->next)
                        if (!sdom->uid || SystemUID(request->uid) || request->uid == sdom->uid)
                                {
                                err = add_domain_to_browser(request, &sdom->name);
                                if (err)
                                        {
                                        if (SameDomainName(&sdom->name, &localdomain)) break;
                                        else err = mStatus_NoError;  // suppress errors for non-local "default" domains
                                        }
                                }
                }

        return(err);
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceResolve
#endif

mDNSlocal void resolve_result_callback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
        {
        size_t len = 0;
        char fullname[MAX_ESCAPED_DOMAIN_NAME], target[MAX_ESCAPED_DOMAIN_NAME];
        char *data;
        reply_state *rep;
        request_state *req = question->QuestionContext;
        (void)m; // Unused

        LogOperation("%3d: DNSServiceResolve(%##s) %s %s", req->sd, question->qname.c, AddRecord ? "ADD" : "RMV", RRDisplayString(m, answer));

        if (!AddRecord)
                {
                if (req->u.resolve.srv == answer) req->u.resolve.srv = mDNSNULL;
                if (req->u.resolve.txt == answer) req->u.resolve.txt = mDNSNULL;
                return;
                }

        if (answer->rrtype == kDNSType_SRV) req->u.resolve.srv = answer;
        if (answer->rrtype == kDNSType_TXT) req->u.resolve.txt = answer;

        if (!req->u.resolve.txt || !req->u.resolve.srv) return;         // only deliver result to client if we have both answers

        ConvertDomainNameToCString(answer->name, fullname);
        ConvertDomainNameToCString(&req->u.resolve.srv->rdata->u.srv.target, target);

        // calculate reply length
        len += sizeof(DNSServiceFlags);
        len += sizeof(mDNSu32);  // interface index
        len += sizeof(DNSServiceErrorType);
        len += strlen(fullname) + 1;
        len += strlen(target) + 1;
        len += 2 * sizeof(mDNSu16);  // port, txtLen
        len += req->u.resolve.txt->rdlength;

        // allocate/init reply header
        rep = create_reply(resolve_reply_op, len, req);
        rep->rhdr->flags = dnssd_htonl(0);
        rep->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(m, answer->InterfaceID, mDNSfalse));
        rep->rhdr->error = dnssd_htonl(kDNSServiceErr_NoError);

        data = (char *)&rep->rhdr[1];

        // write reply data to message
        put_string(fullname, &data);
        put_string(target, &data);
        *data++ =  req->u.resolve.srv->rdata->u.srv.port.b[0];
        *data++ =  req->u.resolve.srv->rdata->u.srv.port.b[1];
        put_uint16(req->u.resolve.txt->rdlength, &data);
        put_rdata (req->u.resolve.txt->rdlength, req->u.resolve.txt->rdata->u.data, &data);

        LogOperation("%3d: DNSServiceResolve(%s) RESULT   %s:%d", req->sd, fullname, target, mDNSVal16(req->u.resolve.srv->rdata->u.srv.port));
        append_reply(req, rep);
        }

mDNSlocal void resolve_termination_callback(request_state *request)
        {
        LogOperation("%3d: DNSServiceResolve(%##s) STOP", request->sd, request->u.resolve.qtxt.qname.c);
        mDNS_StopQuery(&mDNSStorage, &request->u.resolve.qtxt);
        mDNS_StopQuery(&mDNSStorage, &request->u.resolve.qsrv);
        if (request->u.resolve.external_advertise) external_stop_resolving_service(&request->u.resolve.qsrv.qname);
        }

mDNSlocal mStatus handle_resolve_request(request_state *request)
        {
        char name[256], regtype[MAX_ESCAPED_DOMAIN_NAME], domain[MAX_ESCAPED_DOMAIN_NAME];
        domainname fqdn;
        mStatus err;

        // extract the data from the message
        DNSServiceFlags flags = get_flags(&request->msgptr, request->msgend);
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        mDNSInterfaceID InterfaceID;
        mDNSBool wasP2P = (interfaceIndex == kDNSServiceInterfaceIndexP2P);
        
        
        request->flags = flags;
        if (wasP2P) interfaceIndex = kDNSServiceInterfaceIndexAny;
        
        InterfaceID = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        if (interfaceIndex && !InterfaceID)
                { LogMsg("ERROR: handle_resolve_request bad interfaceIndex %d", interfaceIndex); return(mStatus_BadParamErr); }

        if (get_string(&request->msgptr, request->msgend, name, 256) < 0 ||
                get_string(&request->msgptr, request->msgend, regtype, MAX_ESCAPED_DOMAIN_NAME) < 0 ||
                get_string(&request->msgptr, request->msgend, domain, MAX_ESCAPED_DOMAIN_NAME) < 0)
                { LogMsg("ERROR: handle_resolve_request - Couldn't read name/regtype/domain"); return(mStatus_BadParamErr); }

        if (!request->msgptr) { LogMsg("%3d: DNSServiceResolve(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        if (build_domainname_from_strings(&fqdn, name, regtype, domain) < 0)
                { LogMsg("ERROR: handle_resolve_request bad “%s” “%s” “%s”", name, regtype, domain); return(mStatus_BadParamErr); }

        mDNSPlatformMemZero(&request->u.resolve, sizeof(request->u.resolve));

        // format questions
        request->u.resolve.qsrv.InterfaceID      = InterfaceID;
        request->u.resolve.qsrv.Target           = zeroAddr;
        AssignDomainName(&request->u.resolve.qsrv.qname, &fqdn);
        request->u.resolve.qsrv.qtype            = kDNSType_SRV;
        request->u.resolve.qsrv.qclass           = kDNSClass_IN;
        request->u.resolve.qsrv.LongLived        = (flags & kDNSServiceFlagsLongLivedQuery     ) != 0;
        request->u.resolve.qsrv.ExpectUnique     = mDNStrue;
        request->u.resolve.qsrv.ForceMCast       = (flags & kDNSServiceFlagsForceMulticast     ) != 0;
        request->u.resolve.qsrv.ReturnIntermed   = (flags & kDNSServiceFlagsReturnIntermediates) != 0;
        request->u.resolve.qsrv.SuppressUnusable = mDNSfalse;
        request->u.resolve.qsrv.SearchListIndex  = 0;
        request->u.resolve.qsrv.AppendSearchDomains = 0;
        request->u.resolve.qsrv.RetryWithSearchDomains = mDNSfalse;
        request->u.resolve.qsrv.TimeoutQuestion  = 0;
        request->u.resolve.qsrv.WakeOnResolve    = (flags & kDNSServiceFlagsWakeOnResolve) != 0;
        request->u.resolve.qsrv.qnameOrig        = mDNSNULL;
        request->u.resolve.qsrv.QuestionCallback = resolve_result_callback;
        request->u.resolve.qsrv.QuestionContext  = request;

        request->u.resolve.qtxt.InterfaceID      = InterfaceID;
        request->u.resolve.qtxt.Target           = zeroAddr;
        AssignDomainName(&request->u.resolve.qtxt.qname, &fqdn);
        request->u.resolve.qtxt.qtype            = kDNSType_TXT;
        request->u.resolve.qtxt.qclass           = kDNSClass_IN;
        request->u.resolve.qtxt.LongLived        = (flags & kDNSServiceFlagsLongLivedQuery     ) != 0;
        request->u.resolve.qtxt.ExpectUnique     = mDNStrue;
        request->u.resolve.qtxt.ForceMCast       = (flags & kDNSServiceFlagsForceMulticast     ) != 0;
        request->u.resolve.qtxt.ReturnIntermed   = (flags & kDNSServiceFlagsReturnIntermediates) != 0;
        request->u.resolve.qtxt.SuppressUnusable = mDNSfalse;
        request->u.resolve.qtxt.SearchListIndex  = 0;
        request->u.resolve.qtxt.AppendSearchDomains = 0;
        request->u.resolve.qtxt.RetryWithSearchDomains = mDNSfalse;
        request->u.resolve.qtxt.TimeoutQuestion  = 0;
        request->u.resolve.qtxt.WakeOnResolve    = 0;
        request->u.resolve.qtxt.qnameOrig        = mDNSNULL;
        request->u.resolve.qtxt.QuestionCallback = resolve_result_callback;
        request->u.resolve.qtxt.QuestionContext  = request;

        request->u.resolve.ReportTime            = NonZeroTime(mDNS_TimeNow(&mDNSStorage) + 130 * mDNSPlatformOneSecond);

        request->u.resolve.external_advertise    = mDNSfalse;

#if 0
        if (!AuthorizedDomain(request, &fqdn, AutoBrowseDomains))       return(mStatus_NoError);
#endif

        // ask the questions
        LogOperation("%3d: DNSServiceResolve(%X %d %##s) START", request->sd, flags, interfaceIndex, request->u.resolve.qsrv.qname.c);
        err = mDNS_StartQuery(&mDNSStorage, &request->u.resolve.qsrv);
        if (!err)
                {
                err = mDNS_StartQuery(&mDNSStorage, &request->u.resolve.qtxt);
                if (err) mDNS_StopQuery(&mDNSStorage, &request->u.resolve.qsrv);
                else
                        {
                        request->terminate = resolve_termination_callback;
                        // If the user explicitly passed in P2P, we don't restrict the domain in which we resolve.
                        if (wasP2P || (!InterfaceID && IsLocalDomain(&fqdn) && (request->flags & kDNSServiceFlagsIncludeP2P)))
                                { 
                                request->u.resolve.external_advertise    = mDNStrue;
                                LogInfo("handle_resolve_request: calling external_start_resolving_service()");
                                external_start_resolving_service(&fqdn);
                                }
                        }
                }

        return(err);
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceQueryRecord
#endif

// mDNS operation functions. Each operation has 3 associated functions - a request handler that parses
// the client's request and makes the appropriate mDNSCore call, a result handler (passed as a callback
// to the mDNSCore routine) that sends results back to the client, and a termination routine that aborts
// the mDNSCore operation if the client dies or closes its socket.

// Returns -1 to tell the caller that it should not try to reissue the query anymore 
// Returns 1 on successfully appending a search domain and the caller should reissue the new query
// Returns 0 when there are no more search domains and the caller should reissue the query
mDNSlocal int AppendNewSearchDomain(mDNS *const m, DNSQuestion *question)
        {
        domainname *sd;
        mStatus err;

        // Sanity check: The caller already checks this. We use -1 to indicate that we have searched all
        // the domains and should try the single label query directly on the wire. 
        if (question->SearchListIndex == -1)
                {
                LogMsg("AppendNewSearchDomain: question %##s (%s) SearchListIndex is -1", question->qname.c, DNSTypeName(question->qtype));
                return -1;
                }

        if (!question->AppendSearchDomains)
                {
                LogMsg("AppendNewSearchDomain: question %##s (%s) AppendSearchDoamins is 0", question->qname.c, DNSTypeName(question->qtype));
                return -1;
                }

        // Save the original name, before we modify them below.
        if (!question->qnameOrig)
                {
                question->qnameOrig =  mallocL("AppendNewSearchDomain", sizeof(domainname));
                if (!question->qnameOrig) { LogMsg("AppendNewSearchDomain: ERROR!!  malloc failure"); return -1; }
                question->qnameOrig->c[0] = 0;
                AssignDomainName(question->qnameOrig, &question->qname);
                LogInfo("AppendSearchDomain: qnameOrig %##s", question->qnameOrig->c);
                }

        sd = uDNS_GetNextSearchDomain(m, question->InterfaceID, &question->SearchListIndex, !question->AppendLocalSearchDomains);
        // We use -1 to indicate that we have searched all the domains and should try the single label
        // query directly on the wire. uDNS_GetNextSearchDomain should never return a negative value
        if (question->SearchListIndex == -1)
                {
                LogMsg("AppendNewSearchDomain: ERROR!! uDNS_GetNextSearchDomain returned -1");
                return -1;
                }

        // Not a common case. Perhaps, we should try the next search domain if it exceeds ?
        if (sd && (DomainNameLength(question->qnameOrig) + DomainNameLength(sd)) > MAX_DOMAIN_NAME)
                {
                LogMsg("AppendNewSearchDomain: ERROR!! exceeding max domain length for %##s (%s) SearchDomain %##s length %d, Question name length %d", question->qnameOrig->c, DNSTypeName(question->qtype), sd->c, DomainNameLength(question->qnameOrig), DomainNameLength(sd));
                return -1;
                }

        // if there are no more search domains and we have already tried this question
        // without appending search domains, then we are done.
        if (!sd && !ApplySearchDomainsFirst(question))
                {
                LogInfo("AppnedNewSearchDomain: No more search domains for question with name %##s (%s), not trying anymore", question->qname.c, DNSTypeName(question->qtype));
                return -1;
                }

        // Stop the question before changing the name as negative cache entries could be pointing at this question.
        // Even if we don't change the question in the case of returning 0, the caller is going to restart the
        // question.
        err = mDNS_StopQuery(&mDNSStorage, question);
        if (err) { LogMsg("AppendNewSearchDomain: ERROR!! %##s %s mDNS_StopQuery: %d, while retrying with search domains", question->qname.c, DNSTypeName(question->qtype), (int)err); }

        AssignDomainName(&question->qname, question->qnameOrig);
        if (sd)
                {
                AppendDomainName(&question->qname, sd);
                LogInfo("AppnedNewSearchDomain: Returning question with name %##s, SearchListIndex %d", question->qname.c, question->SearchListIndex);
                return 1;
                }

        // Try the question as single label
        LogInfo("AppnedNewSearchDomain: No more search domains for question with name %##s (%s), trying one last time", question->qname.c, DNSTypeName(question->qtype));
        return 0;
        }

#if APPLE_OSX_mDNSResponder

mDNSlocal mDNSBool DomainInSearchList(domainname *domain)
        {
        const SearchListElem *s;
        for (s=SearchList; s; s=s->next)
                if (SameDomainName(&s->domain, domain)) return mDNStrue;
        return mDNSfalse;
        }

// Workaround for networks using Microsoft Active Directory using "local" as a private internal
// top-level domain
mDNSlocal mStatus SendAdditionalQuery(DNSQuestion *q, request_state *request, mStatus err)
        {
        extern domainname ActiveDirectoryPrimaryDomain;
        DNSQuestion **question2;
        #define VALID_MSAD_SRV_TRANSPORT(T) (SameDomainLabel((T)->c, (const mDNSu8 *)"\x4_tcp") || SameDomainLabel((T)->c, (const mDNSu8 *)"\x4_udp"))
        #define VALID_MSAD_SRV(Q) ((Q)->qtype == kDNSType_SRV && VALID_MSAD_SRV_TRANSPORT(SecondLabel(&(Q)->qname)))

        question2 = mDNSNULL;
        if (request->hdr.op == query_request)
                question2 = &request->u.queryrecord.q2;
        else if (request->hdr.op == addrinfo_request)
                {
                if (q->qtype == kDNSType_A)
                        question2 = &request->u.addrinfo.q42;
                else if (q->qtype == kDNSType_AAAA)
                        question2 = &request->u.addrinfo.q62;
                }
        if (!question2)
                {
                LogMsg("SendAdditionalQuery: question2 NULL for %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
                return mStatus_BadParamErr;
                }

        // Sanity check: If we already sent an additonal query, we don't need to send one more.
        //
        // 1. When the application calls DNSServiceQueryRecord or DNSServiceGetAddrInfo with a .local name, this function
        // is called to see whether a unicast query should be sent or not.
        //
        // 2. As a result of appending search domains, the question may be end up with a .local suffix even though it
        // was not a .local name to start with. In that case, queryrecord_result_callback calls this function to
        // send the additional query.
        //
        // Thus, it should not be called more than once.
        if (*question2)
                {
                LogInfo("SendAdditionalQuery: question2 already sent for %##s (%s), no more q2", q->qname.c, DNSTypeName(q->qtype));
                return err;
                }

        if (!q->ForceMCast && SameDomainLabel(LastLabel(&q->qname), (const mDNSu8 *)&localdomain))
                if (q->qtype == kDNSType_A || q->qtype == kDNSType_AAAA || VALID_MSAD_SRV(q))
                        {
                        DNSQuestion *q2;
                        int labels = CountLabels(&q->qname);
                        q2 = mallocL("DNSQuestion", sizeof(DNSQuestion));
                        if (!q2) FatalError("ERROR: SendAdditionalQuery malloc");
                        *question2        = q2;
                        *q2               = *q;
                        q2->InterfaceID   = mDNSInterface_Unicast;
                        q2->ExpectUnique  = mDNStrue;
                        // If the query starts as a single label e.g., somehost, and we have search domains with .local,
                        // queryrecord_result_callback calls this function when .local is appended to "somehost".
                        // At that time, the name in "q" is pointing at somehost.local and its qnameOrig pointing at
                        // "somehost". We need to copy that information so that when we retry with a different search
                        // domain e.g., mycompany.local, we get "somehost.mycompany.local".
                        if (q->qnameOrig)
                                {
                                (*question2)->qnameOrig =  mallocL("SendAdditionalQuery", DomainNameLength(q->qnameOrig));
                                if (!(*question2)->qnameOrig) { LogMsg("SendAdditionalQuery: ERROR!!  malloc failure"); return mStatus_NoMemoryErr; }
                                (*question2)->qnameOrig->c[0] = 0;
                                AssignDomainName((*question2)->qnameOrig, q->qnameOrig);
                                LogInfo("SendAdditionalQuery: qnameOrig %##s", (*question2)->qnameOrig->c);
                                }
                        // For names of the form "<one-or-more-labels>.bar.local." we always do a second unicast query in parallel.
                        // For names of the form "<one-label>.local." it's less clear whether we should do a unicast query.
                        // If the name being queried is exactly the same as the name in the DHCP "domain" option (e.g. the DHCP
                        // "domain" is my-small-company.local, and the user types "my-small-company.local" into their web browser)
                        // then that's a hint that it's worth doing a unicast query. Otherwise, we first check to see if the
                        // site's DNS server claims there's an SOA record for "local", and if so, that's also a hint that queries
                        // for names in the "local" domain will be safely answered privately before they hit the root name servers.
                        // Note that in the "my-small-company.local" example above there will typically be an SOA record for
                        // "my-small-company.local" but *not* for "local", which is why the "local SOA" check would fail in that case.
                        // We need to check against both ActiveDirectoryPrimaryDomain and SearchList. If it matches against either
                        // of those, we don't want do the SOA check for the local
                        if (labels == 2 && !SameDomainName(&q->qname, &ActiveDirectoryPrimaryDomain) && !DomainInSearchList(&q->qname))
                                {
                                AssignDomainName(&q2->qname, &localdomain);
                                q2->qtype          = kDNSType_SOA;
                                q2->LongLived      = mDNSfalse;
                                q2->ForceMCast     = mDNSfalse;
                                q2->ReturnIntermed = mDNStrue;
                                // Don't append search domains for the .local SOA query
                                q2->AppendSearchDomains = 0;
                                q2->AppendLocalSearchDomains = 0;
                                q2->RetryWithSearchDomains = mDNSfalse;
                                q2->SearchListIndex = 0;
                                q2->TimeoutQuestion = 0;
                                }
                        LogOperation("%3d: DNSServiceQueryRecord(%##s, %s) unicast", request->sd, q2->qname.c, DNSTypeName(q2->qtype));
                        err = mDNS_StartQuery(&mDNSStorage, q2);
                        if (err) LogMsg("%3d: ERROR: DNSServiceQueryRecord %##s %s mDNS_StartQuery: %d", request->sd, q2->qname.c, DNSTypeName(q2->qtype), (int)err);
                        }
        return(err);
        }
#endif // APPLE_OSX_mDNSResponder

// This function tries to append a search domain if valid and possible. If so, returns true.
mDNSlocal mDNSBool RetryQuestionWithSearchDomains(mDNS *const m, DNSQuestion *question, request_state *req)
        {
        int result;
        // RetryWithSearchDomains tells the core to call us back so that we can retry with search domains if there is no
        // answer in the cache or /etc/hosts. In the first call back from the core, we clear RetryWithSearchDomains so
        // that we don't get called back repeatedly. If we got an answer from the cache or /etc/hosts, we don't touch
        // RetryWithSearchDomains which may or may not be set.
        //
        // If we get e.g., NXDOMAIN and the query is neither suppressed nor exhausted the domain search list and
        // is a valid question for appending search domains, retry by appending domains

        if (!question->SuppressQuery && question->SearchListIndex != -1 && question->AppendSearchDomains)
                {
                question->RetryWithSearchDomains = 0;
                result = AppendNewSearchDomain(m, question);
                // As long as the result is either zero or 1, we retry the question. If we exahaust the search
                // domains (result is zero) we try the original query (as it was before appending the search
                // domains) as such on the wire as a last resort if we have not tried them before. For queries
                // with more than one label, we have already tried them before appending search domains and
                // hence don't retry again
                if (result != -1)
                        {
                        mStatus err;
                        err = mDNS_StartQuery(m, question);
                        if (!err)
                                {
                                LogOperation("%3d: RetryQuestionWithSearchDomains(%##s, %s), retrying after appending search domain", req->sd, question->qname.c, DNSTypeName(question->qtype));
                                // If the result was zero, it meant that there are no search domains and we just retried the question
                                // as a single label and we should not retry with search domains anymore.
                                if (!result) question->SearchListIndex = -1;
                                return mDNStrue;
                                }
                        else
                                {
                                LogMsg("%3d: ERROR: RetryQuestionWithSearchDomains %##s %s mDNS_StartQuery: %d, while retrying with search domains", req->sd, question->qname.c, DNSTypeName(question->qtype), (int)err);
                                // We have already stopped the query and could not restart. Reset the appropriate pointers
                                // so that we don't call stop again when the question terminates
                                question->QuestionContext = mDNSNULL;
                                }
                        }
                }
        else 
                {
                LogInfo("%3d: RetryQuestionWithSearchDomains: Not appending search domains - SuppressQuery %d, SearchListIndex %d, AppendSearchDomains %d", req->sd, question->SuppressQuery, question->SearchListIndex, question->AppendSearchDomains);
                }
        return mDNSfalse;
        }

mDNSlocal void queryrecord_result_callback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
        {
        char name[MAX_ESCAPED_DOMAIN_NAME];
        request_state *req = question->QuestionContext;
        reply_state *rep;
        char *data;
        size_t len;
        DNSServiceErrorType error = kDNSServiceErr_NoError;
        DNSQuestion *q = mDNSNULL;

#if APPLE_OSX_mDNSResponder
        {
        // Sanity check: QuestionContext is set to NULL after we stop the question and hence we should not
        // get any callbacks from the core after this.
        if (!req)
                {
                LogMsg("queryrecord_result_callback: ERROR!! QuestionContext NULL for %##s (%s)", question->qname.c, DNSTypeName(question->qtype));
                return;
                }
        if (req->hdr.op == query_request && question == req->u.queryrecord.q2)
                q = &req->u.queryrecord.q;
        else if (req->hdr.op == addrinfo_request && question == req->u.addrinfo.q42)
                q = &req->u.addrinfo.q4;
        else if (req->hdr.op == addrinfo_request && question == req->u.addrinfo.q62)
                q = &req->u.addrinfo.q6;
        
        if (q && question->qtype != q->qtype && !SameDomainName(&question->qname, &q->qname))
                {
                mStatus err;
                domainname *orig = question->qnameOrig;

                LogInfo("queryrecord_result_callback: Stopping q2 local %##s", question->qname.c);
                mDNS_StopQuery(m, question);
                question->QuestionContext = mDNSNULL;

                // We got a negative response for the SOA record indicating that .local does not exist.
                // But we might have other search domains (that does not end in .local) that can be
                // appended to this question. In that case, we want to retry the question. Otherwise,
                // we don't want to try this question as unicast.
                if (answer->RecordType == kDNSRecordTypePacketNegative && !q->AppendSearchDomains)
                        {
                        LogInfo("queryrecord_result_callback: question %##s AppendSearchDomains zero", q->qname.c);
                        return;
                        }

                // If we got a non-negative answer for our "local SOA" test query, start an additional parallel unicast query
                //
                // Note: When we copy the original question, we copy everything including the AppendSearchDomains,
                // RetryWithSearchDomains except for qnameOrig which can be non-NULL if the original question is
                // e.g., somehost and then we appended e.g., ".local" and retried that question. See comment in
                // SendAdditionalQuery as to how qnameOrig gets initialized.
                *question              = *q;
                question->InterfaceID  = mDNSInterface_Unicast;
                question->ExpectUnique = mDNStrue;
                question->qnameOrig    = orig;

                LogOperation("%3d: DNSServiceQueryRecord(%##s, %s) unicast, context %p", req->sd, question->qname.c, DNSTypeName(question->qtype), question->QuestionContext);

                // If the original question timed out, its QuestionContext would already be set to NULL and that's what we copied above.
                // Hence, we need to set it explicitly here.
                question->QuestionContext = req;
                err = mDNS_StartQuery(m, question);
                if (err) LogMsg("%3d: ERROR: queryrecord_result_callback %##s %s mDNS_StartQuery: %d", req->sd, question->qname.c, DNSTypeName(question->qtype), (int)err);

                // If we got a positive response to local SOA, then try the .local question as unicast
                if (answer->RecordType != kDNSRecordTypePacketNegative) return;

                // Fall through and get the next search domain. The question is pointing at .local
                // and we don't want to try that. Try the next search domain. Don't try with local
                // search domains for the unicast question anymore.
                //
                // Note: we started the question above which will be stopped immediately (never sent on the wire)
                // before we pick the next search domain below. RetryQuestionWithSearchDomains assumes that the
                // question has already started.
                question->AppendLocalSearchDomains = 0;
                }

        if (q && AddRecord && (question->InterfaceID == mDNSInterface_Unicast) && !answer->rdlength)
                {
                // If we get a negative response to the unicast query that we sent above, retry after appending search domains
                // Note: We could have appended search domains below (where do it for regular unicast questions) instead of doing it here. 
                // As we ignore negative unicast answers below, we would never reach the code where the search domains are appended.
                // To keep things simple, we handle unicast ".local" separately here.
                LogInfo("queryrecord_result_callback: Retrying .local question %##s (%s) as unicast after appending search domains", question->qname.c, DNSTypeName(question->qtype));
                if (RetryQuestionWithSearchDomains(m, question, req))
                        return;
                if (question->AppendSearchDomains && !question->AppendLocalSearchDomains && IsLocalDomain(&question->qname))
                        {
                        // If "local" is the last search domain, we need to stop the question so that we don't send the "local"
                        // question on the wire as we got a negative response for the local SOA. But, we can't stop the question
                        // yet as we may have to timeout the question (done by the "core") for which we need to leave the question
                        // in the list. We leave it disabled so that it does not hit the wire.
                        LogInfo("queryrecord_result_callback: Disabling .local question %##s (%s)", question->qname.c, DNSTypeName(question->qtype));
                        question->ThisQInterval = 0;
                        }
                }
        // If we are here it means that either "question" is not "q2" OR we got a positive response for "q2" OR we have no more search
        // domains to append for "q2". In all cases, fall through and deliver the response
        }
#endif // APPLE_OSX_mDNSResponder

        if (answer->RecordType == kDNSRecordTypePacketNegative)
                {
                // If this question needs to be timed out and we have reached the stop time, mark
                // the error as timeout. It is possible that we might get a negative response from an
                // external DNS server at the same time when this question reaches its stop time. We
                // can't tell the difference as there is no indication in the callback. This should
                // be okay as we will be timing out this query anyway.
                mDNS_Lock(m);
                if (question->TimeoutQuestion)
                        {
                        if ((m->timenow - question->StopTime) >= 0)
                                {
                                LogInfo("queryrecord_result_callback:Question %##s (%s) timing out, InterfaceID %p", question->qname.c, DNSTypeName(question->qtype), question->InterfaceID);
                                error = kDNSServiceErr_Timeout;
                                }
                        }
                mDNS_Unlock(m);
                // When we're doing parallel unicast and multicast queries for dot-local names (for supporting Microsoft
                // Active Directory sites) we need to ignore negative unicast answers. Otherwise we'll generate negative
                // answers for just about every single multicast name we ever look up, since the Microsoft Active Directory
                // server is going to assert that pretty much every single multicast name doesn't exist.
                //
                // If we are timing out this query, we need to deliver the negative answer to the application
                if (error != kDNSServiceErr_Timeout)
                        {
                        if (!answer->InterfaceID && IsLocalDomain(answer->name))
                                {
                                LogInfo("queryrecord_result_callback:Question %##s (%s) answering local with unicast", question->qname.c, DNSTypeName(question->qtype));
                                return;
                                }
                        error = kDNSServiceErr_NoSuchRecord;
                        }
                AddRecord = mDNStrue;
                }
        // If we get a negative answer, try appending search domains. Don't append search domains
        // - if we are timing out this question
        // - if the negative response was received as a result of a multicast query
        // - if this is an additional query (q2), we already appended search domains above (indicated by "!q" below)
        if (error != kDNSServiceErr_Timeout)
                {
                if (!q && !answer->InterfaceID && !answer->rdlength && AddRecord)
                        {
                        // If the original question did not end in .local, we did not send an SOA query
                        // to figure out whether we should send an additional unicast query or not. If we just
                        // appended .local, we need to see if we need to send an additional query. This should
                        // normally happen just once because after we append .local, we ignore all negative
                        // responses for .local above.
                        LogInfo("queryrecord_result_callback: Retrying question %##s (%s) after appending search domains", question->qname.c, DNSTypeName(question->qtype));
                        if (RetryQuestionWithSearchDomains(m, question, req))
                                {
                                // Note: We need to call SendAdditionalQuery every time after appending a search domain as .local could
                                // be anywhere in the search domain list.
#if APPLE_OSX_mDNSResponder
                                mStatus err = mStatus_NoError;
                                err = SendAdditionalQuery(question, req, err);
                                if (err) LogMsg("queryrecord_result_callback: Sending .local SOA query failed, after appending domains");
#endif // APPLE_OSX_mDNSResponder
                                return;
                                }
                        }
                }

        ConvertDomainNameToCString(answer->name, name);

        LogOperation("%3d: %s(%##s, %s) %s %s", req->sd,
                req->hdr.op == query_request ? "DNSServiceQueryRecord" : "DNSServiceGetAddrInfo",
                question->qname.c, DNSTypeName(question->qtype), AddRecord ? "ADD" : "RMV", RRDisplayString(m, answer));

        len = sizeof(DNSServiceFlags);  // calculate reply data length
        len += sizeof(mDNSu32);         // interface index
        len += sizeof(DNSServiceErrorType);
        len += strlen(name) + 1;
        len += 3 * sizeof(mDNSu16);     // type, class, rdlen
        len += answer->rdlength;
        len += sizeof(mDNSu32);         // TTL

        rep = create_reply(req->hdr.op == query_request ? query_reply_op : addrinfo_reply_op, len, req);

        rep->rhdr->flags = dnssd_htonl(AddRecord ? kDNSServiceFlagsAdd : 0);
        // Call mDNSPlatformInterfaceIndexfromInterfaceID, but suppressNetworkChange (last argument). Otherwise, if the
        // InterfaceID is not valid, then it simulates a "NetworkChanged" which in turn makes questions
        // to be stopped and started including  *this* one. Normally the InterfaceID is valid. But when we
        // are using the /etc/hosts entries to answer a question, the InterfaceID may not be known to the
        // mDNS core . Eventually, we should remove the calls to "NetworkChanged" in
        // mDNSPlatformInterfaceIndexfromInterfaceID when it can't find InterfaceID as ResourceRecords
        // should not have existed to answer this question if the corresponding interface is not valid.
        rep->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(m, answer->InterfaceID, mDNStrue));
        rep->rhdr->error = dnssd_htonl(error);

        data = (char *)&rep->rhdr[1];

        put_string(name,             &data);
        put_uint16(answer->rrtype,   &data);
        put_uint16(answer->rrclass,  &data);
        put_uint16(answer->rdlength, &data);
        // We need to use putRData here instead of the crude put_rdata function, because the crude put_rdata
        // function just does a blind memory copy without regard to structures that may have holes in them.
        if (answer->rdlength)
                if (!putRData(mDNSNULL, (mDNSu8 *)data, (mDNSu8 *)rep->rhdr + len, answer))
                        LogMsg("queryrecord_result_callback putRData failed %d", (mDNSu8 *)rep->rhdr + len - (mDNSu8 *)data);
        data += answer->rdlength;
        put_uint32(AddRecord ? answer->rroriginalttl : 0, &data);

        append_reply(req, rep);
        // Stop the question, if we just timed out
        if (error == kDNSServiceErr_Timeout)
                {
                mDNS_StopQuery(m, question);
                // Reset the pointers so that we don't call stop on termination
                question->QuestionContext = mDNSNULL;
                }
#if APPLE_OSX_mDNSResponder
#if ! NO_WCF
        CHECK_WCF_FUNCTION(WCFIsServerRunning)
                {
                struct xucred x;
                socklen_t xucredlen = sizeof(x);
        
                if (WCFIsServerRunning((WCFConnection *)m->WCF) && answer->rdlength != 0)
                        {
                        if (getsockopt(req->sd, 0, LOCAL_PEERCRED, &x, &xucredlen) >= 0 &&
                                (x.cr_version == XUCRED_VERSION))
                                {
                                struct sockaddr_storage addr;
                                const RDataBody2 *const rdb = (RDataBody2 *)answer->rdata->u.data;
                                addr.ss_len = 0;
                                if (answer->rrtype == kDNSType_A || answer->rrtype == kDNSType_AAAA)
                                        {
                                        if (answer->rrtype == kDNSType_A)
                                                {
                                                struct sockaddr_in *sin = (struct sockaddr_in *)&addr;
                                                sin->sin_port = 0;
                                                if (!putRData(mDNSNULL, (mDNSu8 *)&sin->sin_addr, (mDNSu8 *)(&sin->sin_addr + sizeof(rdb->ipv4)), answer))
                                                        LogMsg("queryrecord_result_callback: WCF AF_INET putRData failed");
                                                else
                                                        {
                                                        addr.ss_len = sizeof (struct sockaddr_in);
                                                        addr.ss_family = AF_INET;
                                                        }
                                                }
                                        else if (answer->rrtype == kDNSType_AAAA)
                                                {
                                                struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&addr;
                                                sin6->sin6_port = 0;
                                                if (!putRData(mDNSNULL, (mDNSu8 *)&sin6->sin6_addr, (mDNSu8 *)(&sin6->sin6_addr + sizeof(rdb->ipv6)), answer))
                                                        LogMsg("queryrecord_result_callback: WCF AF_INET6 putRData failed");
                                                else
                                                        {
                                                        addr.ss_len = sizeof (struct sockaddr_in6);
                                                        addr.ss_family = AF_INET6;
                                                        }
                                                }
                                        if (addr.ss_len)
                                                {       
                                                debugf("queryrecord_result_callback: Name %s, uid %u, addr length %d", name, x.cr_uid, addr.ss_len);
                                                CHECK_WCF_FUNCTION((WCFConnection *)WCFNameResolvesToAddr)
                                                        {
                                                        WCFNameResolvesToAddr(m->WCF, name, (struct sockaddr *)&addr, x.cr_uid);
                                                        }
                                                }
                                        }
                                else if (answer->rrtype == kDNSType_CNAME)
                                        {
                                        domainname cname;
                                        char cname_cstr[MAX_ESCAPED_DOMAIN_NAME];
                                        if (!putRData(mDNSNULL, cname.c, (mDNSu8 *)(cname.c + MAX_DOMAIN_NAME), answer))
                                                        LogMsg("queryrecord_result_callback: WCF CNAME putRData failed");
                                        else
                                                {
                                                ConvertDomainNameToCString(&cname, cname_cstr);
                                                CHECK_WCF_FUNCTION((WCFConnection *)WCFNameResolvesToAddr)
                                                        {
                                                        WCFNameResolvesToName(m->WCF, name, cname_cstr, x.cr_uid);
                                                        }
                                                }
                                        }
                                }
                        else my_perror("queryrecord_result_callback: ERROR: getsockopt LOCAL_PEERCRED");
                        }
                }
#endif
#endif
        }

mDNSlocal void queryrecord_termination_callback(request_state *request)
        {
        LogOperation("%3d: DNSServiceQueryRecord(%##s, %s) STOP",
                request->sd, request->u.queryrecord.q.qname.c, DNSTypeName(request->u.queryrecord.q.qtype));
        if (request->u.queryrecord.q.QuestionContext)
                {
                mDNS_StopQuery(&mDNSStorage, &request->u.queryrecord.q);  // no need to error check
                request->u.queryrecord.q.QuestionContext = mDNSNULL;
                }
        else
                {
                DNSQuestion *question = &request->u.queryrecord.q;
                LogInfo("queryrecord_termination_callback: question %##s (%s) already stopped, InterfaceID %p", question->qname.c, DNSTypeName(question->qtype), question->InterfaceID);
                }

        if (request->u.queryrecord.q.qnameOrig)
                {
                freeL("QueryTermination", request->u.queryrecord.q.qnameOrig);
                request->u.queryrecord.q.qnameOrig = mDNSNULL;
                }
        if (request->u.queryrecord.q.InterfaceID == mDNSInterface_P2P || (!request->u.queryrecord.q.InterfaceID && SameDomainName((const domainname *)LastLabel(&request->u.queryrecord.q.qname), &localdomain) && (request->flags & kDNSServiceFlagsIncludeP2P)))
                {
                LogInfo("queryrecord_termination_callback: calling external_stop_browsing_for_service()");
                external_stop_browsing_for_service(&mDNSStorage, &request->u.queryrecord.q.qname, request->u.queryrecord.q.qtype);
                }
        if (request->u.queryrecord.q2)
                {
                if (request->u.queryrecord.q2->QuestionContext)
                        {
                        LogInfo("queryrecord_termination_callback: Stopping q2 %##s", request->u.queryrecord.q2->qname.c);
                        mDNS_StopQuery(&mDNSStorage, request->u.queryrecord.q2);
                        }
                else 
                        {
                        DNSQuestion *question = request->u.queryrecord.q2;
                        LogInfo("queryrecord_termination_callback: q2 %##s (%s) already stopped, InterfaceID %p", question->qname.c, DNSTypeName(question->qtype), question->InterfaceID);
                        }
                if (request->u.queryrecord.q2->qnameOrig)
                        {
                        LogInfo("queryrecord_termination_callback: freeing q2 qnameOrig %##s", request->u.queryrecord.q2->qnameOrig->c);
                        freeL("QueryTermination q2", request->u.queryrecord.q2->qnameOrig);
                        request->u.queryrecord.q2->qnameOrig = mDNSNULL;
                        }
                freeL("queryrecord Q2", request->u.queryrecord.q2);
                request->u.queryrecord.q2 = mDNSNULL;
                }
        }

mDNSlocal mStatus handle_queryrecord_request(request_state *request)
        {
        DNSQuestion *const q = &request->u.queryrecord.q;
        char name[256];
        mDNSu16 rrtype, rrclass;
        mStatus err;

        DNSServiceFlags flags = get_flags(&request->msgptr, request->msgend);
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        mDNSInterfaceID InterfaceID = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        if (interfaceIndex && !InterfaceID) return(mStatus_BadParamErr);

        if (get_string(&request->msgptr, request->msgend, name, 256) < 0) return(mStatus_BadParamErr);
        rrtype  = get_uint16(&request->msgptr, request->msgend);
        rrclass = get_uint16(&request->msgptr, request->msgend);

        if (!request->msgptr)
                { LogMsg("%3d: DNSServiceQueryRecord(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        request->flags = flags;
        mDNSPlatformMemZero(&request->u.queryrecord, sizeof(request->u.queryrecord));

        q->InterfaceID      = InterfaceID;
        q->Target           = zeroAddr;
        if (!MakeDomainNameFromDNSNameString(&q->qname, name))                  return(mStatus_BadParamErr);
#if 0
        if (!AuthorizedDomain(request, &q->qname, AutoBrowseDomains))   return (mStatus_NoError);
#endif
        q->qtype            = rrtype;
        q->qclass           = rrclass;
        q->LongLived        = (flags & kDNSServiceFlagsLongLivedQuery     ) != 0;
        q->ExpectUnique     = mDNSfalse;
        q->ForceMCast       = (flags & kDNSServiceFlagsForceMulticast     ) != 0;
        q->ReturnIntermed   = (flags & kDNSServiceFlagsReturnIntermediates) != 0;
        q->SuppressUnusable = (flags & kDNSServiceFlagsSuppressUnusable   ) != 0;
        q->TimeoutQuestion  = (flags & kDNSServiceFlagsTimeout            ) != 0;
        q->WakeOnResolve    = 0;
        q->QuestionCallback = queryrecord_result_callback;
        q->QuestionContext  = request;
        q->SearchListIndex  = 0;

        // Don't append search domains for fully qualified domain names including queries
        // such as e.g., "abc." that has only one label. We convert all names to FQDNs as internally
        // we only deal with FQDNs. Hence, we cannot look at qname to figure out whether we should
        // append search domains or not.  So, we record that information in AppendSearchDomains.
        //
        // We append search domains only for queries that are a single label. If overriden using
        // command line argument "AlwaysAppendSearchDomains", then we do it for any query which
        // is not fully qualified.

        if ((rrtype == kDNSType_A || rrtype == kDNSType_AAAA) && name[strlen(name) - 1] != '.' &&
                (AlwaysAppendSearchDomains || CountLabels(&q->qname) == 1))
                {
                q->AppendSearchDomains = 1;
                q->AppendLocalSearchDomains = 1;
                }
        else
                {
                q->AppendSearchDomains = 0;
                q->AppendLocalSearchDomains = 0;
                }

        // For single label queries that are not fully qualified, look at /etc/hosts, cache and try
        // search domains before trying them on the wire as a single label query. RetryWithSearchDomains
        // tell the core to call back into the UDS layer if there is no valid response in /etc/hosts or
        // the cache
        q->RetryWithSearchDomains = ApplySearchDomainsFirst(q) ? 1 : 0;
        q->qnameOrig        = mDNSNULL;

        LogOperation("%3d: DNSServiceQueryRecord(%X, %d, %##s, %s) START", request->sd, flags, interfaceIndex, q->qname.c, DNSTypeName(q->qtype));
        err = mDNS_StartQuery(&mDNSStorage, q);
        if (err) LogMsg("%3d: ERROR: DNSServiceQueryRecord %##s %s mDNS_StartQuery: %d", request->sd, q->qname.c, DNSTypeName(q->qtype), (int)err);
        else 
                {
                request->terminate = queryrecord_termination_callback;
                if (q->InterfaceID == mDNSInterface_P2P || (!q->InterfaceID && SameDomainName((const domainname *)LastLabel(&q->qname), &localdomain) && (flags & kDNSServiceFlagsIncludeP2P)))
                        {
                        LogInfo("handle_queryrecord_request: calling external_start_browsing_for_service()");
                        external_start_browsing_for_service(&mDNSStorage, &q->qname, q->qtype);
                        }
                }

#if APPLE_OSX_mDNSResponder
        err = SendAdditionalQuery(q, request, err);
#endif // APPLE_OSX_mDNSResponder

        return(err);
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceEnumerateDomains
#endif

mDNSlocal reply_state *format_enumeration_reply(request_state *request,
        const char *domain, DNSServiceFlags flags, mDNSu32 ifi, DNSServiceErrorType err)
        {
        size_t len;
        reply_state *reply;
        char *data;

        len = sizeof(DNSServiceFlags);
        len += sizeof(mDNSu32);
        len += sizeof(DNSServiceErrorType);
        len += strlen(domain) + 1;

        reply = create_reply(enumeration_reply_op, len, request);
        reply->rhdr->flags = dnssd_htonl(flags);
        reply->rhdr->ifi   = dnssd_htonl(ifi);
        reply->rhdr->error = dnssd_htonl(err);
        data = (char *)&reply->rhdr[1];
        put_string(domain, &data);
        return reply;
        }

mDNSlocal void enum_termination_callback(request_state *request)
        {
        mDNS_StopGetDomains(&mDNSStorage, &request->u.enumeration.q_all);
        mDNS_StopGetDomains(&mDNSStorage, &request->u.enumeration.q_default);
        }

mDNSlocal void enum_result_callback(mDNS *const m,
        DNSQuestion *const question, const ResourceRecord *const answer, QC_result AddRecord)
        {
        char domain[MAX_ESCAPED_DOMAIN_NAME];
        request_state *request = question->QuestionContext;
        DNSServiceFlags flags = 0;
        reply_state *reply;
        (void)m; // Unused

        if (answer->rrtype != kDNSType_PTR) return;

#if 0
        if (!AuthorizedDomain(request, &answer->rdata->u.name, request->u.enumeration.flags ? AutoRegistrationDomains : AutoBrowseDomains)) return;
#endif

        // We only return add/remove events for the browse and registration lists
        // For the default browse and registration answers, we only give an "ADD" event
        if (question == &request->u.enumeration.q_default && !AddRecord) return;

        if (AddRecord)
                {
                flags |= kDNSServiceFlagsAdd;
                if (question == &request->u.enumeration.q_default) flags |= kDNSServiceFlagsDefault;
                }

        ConvertDomainNameToCString(&answer->rdata->u.name, domain);
        // Note that we do NOT propagate specific interface indexes to the client - for example, a domain we learn from
        // a machine's system preferences may be discovered on the LocalOnly interface, but should be browsed on the
        // network, so we just pass kDNSServiceInterfaceIndexAny
        reply = format_enumeration_reply(request, domain, flags, kDNSServiceInterfaceIndexAny, kDNSServiceErr_NoError);
        if (!reply) { LogMsg("ERROR: enum_result_callback, format_enumeration_reply"); return; }

        LogOperation("%3d: DNSServiceEnumerateDomains(%#2s) RESULT %s: %s", request->sd, question->qname.c, AddRecord ? "Add" : "Rmv", domain);

        append_reply(request, reply);
        }

mDNSlocal mStatus handle_enum_request(request_state *request)
        {
        mStatus err;
        DNSServiceFlags flags = get_flags(&request->msgptr, request->msgend);
        DNSServiceFlags reg = flags & kDNSServiceFlagsRegistrationDomains;
        mDNS_DomainType t_all     = reg ? mDNS_DomainTypeRegistration        : mDNS_DomainTypeBrowse;
        mDNS_DomainType t_default = reg ? mDNS_DomainTypeRegistrationDefault : mDNS_DomainTypeBrowseDefault;
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        mDNSInterfaceID InterfaceID = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        if (interfaceIndex && !InterfaceID) return(mStatus_BadParamErr);

        if (!request->msgptr)
                { LogMsg("%3d: DNSServiceEnumerateDomains(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        // allocate context structures
        uDNS_SetupSearchDomains(&mDNSStorage, UDNS_START_WAB_QUERY);

#if 0
        // mark which kind of enumeration we're doing so we can (de)authorize certain domains
        request->u.enumeration.flags = reg;
#endif

        // enumeration requires multiple questions, so we must link all the context pointers so that
        // necessary context can be reached from the callbacks
        request->u.enumeration.q_all    .QuestionContext = request;
        request->u.enumeration.q_default.QuestionContext = request;
        
        // if the caller hasn't specified an explicit interface, we use local-only to get the system-wide list.
        if (!InterfaceID) InterfaceID = mDNSInterface_LocalOnly;

        // make the calls
        LogOperation("%3d: DNSServiceEnumerateDomains(%X=%s)", request->sd, flags,
                (flags & kDNSServiceFlagsBrowseDomains      ) ? "kDNSServiceFlagsBrowseDomains" :
                (flags & kDNSServiceFlagsRegistrationDomains) ? "kDNSServiceFlagsRegistrationDomains" : "<<Unknown>>");
        err = mDNS_GetDomains(&mDNSStorage, &request->u.enumeration.q_all, t_all, NULL, InterfaceID, enum_result_callback, request);
        if (!err)
                {
                err = mDNS_GetDomains(&mDNSStorage, &request->u.enumeration.q_default, t_default, NULL, InterfaceID, enum_result_callback, request);
                if (err) mDNS_StopGetDomains(&mDNSStorage, &request->u.enumeration.q_all);
                else request->terminate = enum_termination_callback;
                }

        return(err);
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceReconfirmRecord & Misc
#endif

mDNSlocal mStatus handle_reconfirm_request(request_state *request)
        {
        mStatus status = mStatus_BadParamErr;
        AuthRecord *rr = read_rr_from_ipc_msg(request, 0, 0);
        if (rr)
                {
                status = mDNS_ReconfirmByValue(&mDNSStorage, &rr->resrec);
                LogOperation(
                        (status == mStatus_NoError) ?
                        "%3d: DNSServiceReconfirmRecord(%s) interface %d initiated" :
                        "%3d: DNSServiceReconfirmRecord(%s) interface %d failed: %d",
                        request->sd, RRDisplayString(&mDNSStorage, &rr->resrec),
                        mDNSPlatformInterfaceIndexfromInterfaceID(&mDNSStorage, rr->resrec.InterfaceID, mDNSfalse), status);
                freeL("AuthRecord/handle_reconfirm_request", rr);
                }
        return(status);
        }

mDNSlocal mStatus handle_setdomain_request(request_state *request)
        {
        char domainstr[MAX_ESCAPED_DOMAIN_NAME];
        domainname domain;
        DNSServiceFlags flags = get_flags(&request->msgptr, request->msgend);
        (void)flags; // Unused
        if (get_string(&request->msgptr, request->msgend, domainstr, MAX_ESCAPED_DOMAIN_NAME) < 0 ||
                !MakeDomainNameFromDNSNameString(&domain, domainstr))
                { LogMsg("%3d: DNSServiceSetDefaultDomainForUser(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        LogOperation("%3d: DNSServiceSetDefaultDomainForUser(%##s)", request->sd, domain.c);
        return(mStatus_NoError);
        }

typedef packedstruct
        {
        mStatus err;
        mDNSu32 len;
        mDNSu32 vers;
        } DaemonVersionReply;

mDNSlocal void handle_getproperty_request(request_state *request)
        {
        const mStatus BadParamErr = dnssd_htonl((mDNSu32)mStatus_BadParamErr);
        char prop[256];
        if (get_string(&request->msgptr, request->msgend, prop, sizeof(prop)) >= 0)
                {
                LogOperation("%3d: DNSServiceGetProperty(%s)", request->sd, prop);
                if (!strcmp(prop, kDNSServiceProperty_DaemonVersion))
                        {
                        DaemonVersionReply x = { 0, dnssd_htonl(4), dnssd_htonl(_DNS_SD_H) };
                        send_all(request->sd, (const char *)&x, sizeof(x));
                        return;
                        }
                }

        // If we didn't recogize the requested property name, return BadParamErr
        send_all(request->sd, (const char *)&BadParamErr, sizeof(BadParamErr));
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceNATPortMappingCreate
#endif

#define DNSServiceProtocol(X) ((X) == NATOp_AddrRequest ? 0 : (X) == NATOp_MapUDP ? kDNSServiceProtocol_UDP : kDNSServiceProtocol_TCP)

mDNSlocal void port_mapping_termination_callback(request_state *request)
        {
        LogOperation("%3d: DNSServiceNATPortMappingCreate(%X, %u, %u, %d) STOP", request->sd,
                DNSServiceProtocol(request->u.pm.NATinfo.Protocol),
                mDNSVal16(request->u.pm.NATinfo.IntPort), mDNSVal16(request->u.pm.ReqExt), request->u.pm.NATinfo.NATLease);
        mDNS_StopNATOperation(&mDNSStorage, &request->u.pm.NATinfo);
        }

// Called via function pointer when we get a NAT-PMP address request or port mapping response
mDNSlocal void port_mapping_create_request_callback(mDNS *m, NATTraversalInfo *n)
        {
        request_state *request = (request_state *)n->clientContext;
        reply_state *rep;
        int replyLen;
        char *data;

        if (!request) { LogMsg("port_mapping_create_request_callback called with unknown request_state object"); return; }

        // calculate reply data length
        replyLen = sizeof(DNSServiceFlags);
        replyLen += 3 * sizeof(mDNSu32);  // if index + addr + ttl
        replyLen += sizeof(DNSServiceErrorType);
        replyLen += 2 * sizeof(mDNSu16);  // Internal Port + External Port
        replyLen += sizeof(mDNSu8);       // protocol

        rep = create_reply(port_mapping_reply_op, replyLen, request);

        rep->rhdr->flags = dnssd_htonl(0);
        rep->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(m, n->InterfaceID, mDNSfalse));
        rep->rhdr->error = dnssd_htonl(n->Result);

        data = (char *)&rep->rhdr[1];

        *data++ = request->u.pm.NATinfo.ExternalAddress.b[0];
        *data++ = request->u.pm.NATinfo.ExternalAddress.b[1];
        *data++ = request->u.pm.NATinfo.ExternalAddress.b[2];
        *data++ = request->u.pm.NATinfo.ExternalAddress.b[3];
        *data++ = DNSServiceProtocol(request->u.pm.NATinfo.Protocol);
        *data++ = request->u.pm.NATinfo.IntPort.b[0];
        *data++ = request->u.pm.NATinfo.IntPort.b[1];
        *data++ = request->u.pm.NATinfo.ExternalPort.b[0];
        *data++ = request->u.pm.NATinfo.ExternalPort.b[1];
        put_uint32(request->u.pm.NATinfo.Lifetime, &data);

        LogOperation("%3d: DNSServiceNATPortMappingCreate(%X, %u, %u, %d) RESULT %.4a:%u TTL %u", request->sd,
                DNSServiceProtocol(request->u.pm.NATinfo.Protocol),
                mDNSVal16(request->u.pm.NATinfo.IntPort), mDNSVal16(request->u.pm.ReqExt), request->u.pm.NATinfo.NATLease,
                &request->u.pm.NATinfo.ExternalAddress, mDNSVal16(request->u.pm.NATinfo.ExternalPort), request->u.pm.NATinfo.Lifetime);

        append_reply(request, rep);
        }

mDNSlocal mStatus handle_port_mapping_request(request_state *request)
        {
        mDNSu32 ttl = 0;
        mStatus err = mStatus_NoError;

        DNSServiceFlags flags          = get_flags(&request->msgptr, request->msgend);
        mDNSu32         interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        mDNSInterfaceID InterfaceID    = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        mDNSu8          protocol       = (mDNSu8)get_uint32(&request->msgptr, request->msgend);
        (void)flags; // Unused
        if (interfaceIndex && !InterfaceID) return(mStatus_BadParamErr);
        if (request->msgptr + 8 > request->msgend) request->msgptr = NULL;
        else
                {
                request->u.pm.NATinfo.IntPort.b[0] = *request->msgptr++;
                request->u.pm.NATinfo.IntPort.b[1] = *request->msgptr++;
                request->u.pm.ReqExt.b[0]          = *request->msgptr++;
                request->u.pm.ReqExt.b[1]          = *request->msgptr++;
                ttl = get_uint32(&request->msgptr, request->msgend);
                }

        if (!request->msgptr)
                { LogMsg("%3d: DNSServiceNATPortMappingCreate(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        if (protocol == 0)      // If protocol == 0 (i.e. just request public address) then IntPort, ExtPort, ttl must be zero too
                {
                if (!mDNSIPPortIsZero(request->u.pm.NATinfo.IntPort) || !mDNSIPPortIsZero(request->u.pm.ReqExt) || ttl) return(mStatus_BadParamErr);
                }
        else
                {
                if (mDNSIPPortIsZero(request->u.pm.NATinfo.IntPort)) return(mStatus_BadParamErr);
                if (!(protocol & (kDNSServiceProtocol_UDP | kDNSServiceProtocol_TCP))) return(mStatus_BadParamErr);
                }

        request->u.pm.NATinfo.Protocol       = !protocol ? NATOp_AddrRequest : (protocol == kDNSServiceProtocol_UDP) ? NATOp_MapUDP : NATOp_MapTCP;
        //       u.pm.NATinfo.IntPort        = already set above
        request->u.pm.NATinfo.RequestedPort  = request->u.pm.ReqExt;
        request->u.pm.NATinfo.NATLease       = ttl;
        request->u.pm.NATinfo.clientCallback = port_mapping_create_request_callback;
        request->u.pm.NATinfo.clientContext  = request;

        LogOperation("%3d: DNSServiceNATPortMappingCreate(%X, %u, %u, %d) START", request->sd,
                protocol, mDNSVal16(request->u.pm.NATinfo.IntPort), mDNSVal16(request->u.pm.ReqExt), request->u.pm.NATinfo.NATLease);
        err = mDNS_StartNATOperation(&mDNSStorage, &request->u.pm.NATinfo);
        if (err) LogMsg("ERROR: mDNS_StartNATOperation: %d", (int)err);
        else request->terminate = port_mapping_termination_callback;

        return(err);
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - DNSServiceGetAddrInfo
#endif

mDNSlocal void addrinfo_termination_callback(request_state *request)
        {
        LogOperation("%3d: DNSServiceGetAddrInfo(%##s) STOP", request->sd, request->u.addrinfo.q4.qname.c);

        if (request->u.addrinfo.q4.QuestionContext)
                {
                mDNS_StopQuery(&mDNSStorage, &request->u.addrinfo.q4);
                request->u.addrinfo.q4.QuestionContext = mDNSNULL;
                }
        if (request->u.addrinfo.q4.qnameOrig)
                {
                freeL("QueryTermination", request->u.addrinfo.q4.qnameOrig);
                request->u.addrinfo.q4.qnameOrig = mDNSNULL;
                }
        if (request->u.addrinfo.q42)
                {
                if (request->u.addrinfo.q42->QuestionContext)
                        {
                        LogInfo("addrinfo_termination_callback: Stopping q42 %##s", request->u.addrinfo.q42->qname.c);
                        mDNS_StopQuery(&mDNSStorage, request->u.addrinfo.q42);
                        }
                if (request->u.addrinfo.q42->qnameOrig)
                        {
                        LogInfo("addrinfo_termination_callback: freeing q42 qnameOrig %##s", request->u.addrinfo.q42->qnameOrig->c);
                        freeL("QueryTermination q42", request->u.addrinfo.q42->qnameOrig);
                        request->u.addrinfo.q42->qnameOrig = mDNSNULL;
                        }
                freeL("addrinfo Q42", request->u.addrinfo.q42);
                request->u.addrinfo.q42 = mDNSNULL;
                }

        if (request->u.addrinfo.q6.QuestionContext)
                {
                mDNS_StopQuery(&mDNSStorage, &request->u.addrinfo.q6);
                request->u.addrinfo.q6.QuestionContext = mDNSNULL;
                }
        if (request->u.addrinfo.q6.qnameOrig)
                {
                freeL("QueryTermination", request->u.addrinfo.q6.qnameOrig);
                request->u.addrinfo.q6.qnameOrig = mDNSNULL;
                }
        if (request->u.addrinfo.q62)
                {
                if (request->u.addrinfo.q62->QuestionContext)
                        {
                        LogInfo("addrinfo_termination_callback: Stopping q62 %##s", request->u.addrinfo.q62->qname.c);
                        mDNS_StopQuery(&mDNSStorage, request->u.addrinfo.q62);
                        }
                if (request->u.addrinfo.q62->qnameOrig)
                        {
                        LogInfo("addrinfo_termination_callback: freeing q62 qnameOrig %##s", request->u.addrinfo.q62->qnameOrig->c);
                        freeL("QueryTermination q62", request->u.addrinfo.q62->qnameOrig);
                        request->u.addrinfo.q62->qnameOrig = mDNSNULL;
                        }
                freeL("addrinfo Q62", request->u.addrinfo.q62);
                request->u.addrinfo.q62 = mDNSNULL;
                }
        }

mDNSlocal mStatus handle_addrinfo_request(request_state *request)
        {
        char hostname[256];
        domainname d;
        mStatus err = 0;

        DNSServiceFlags flags  = get_flags(&request->msgptr, request->msgend);
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);

        mDNSPlatformMemZero(&request->u.addrinfo, sizeof(request->u.addrinfo));
        request->u.addrinfo.interface_id = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        request->u.addrinfo.flags        = flags;
        request->u.addrinfo.protocol     = get_uint32(&request->msgptr, request->msgend);

        if (interfaceIndex && !request->u.addrinfo.interface_id) return(mStatus_BadParamErr);
        if (request->u.addrinfo.protocol > (kDNSServiceProtocol_IPv4|kDNSServiceProtocol_IPv6)) return(mStatus_BadParamErr);

        if (get_string(&request->msgptr, request->msgend, hostname, 256) < 0) return(mStatus_BadParamErr);

        if (!request->msgptr) { LogMsg("%3d: DNSServiceGetAddrInfo(unreadable parameters)", request->sd); return(mStatus_BadParamErr); }

        if (!MakeDomainNameFromDNSNameString(&d, hostname))
                { LogMsg("ERROR: handle_addrinfo_request: bad hostname: %s", hostname); return(mStatus_BadParamErr); }

#if 0
        if (!AuthorizedDomain(request, &d, AutoBrowseDomains))  return (mStatus_NoError);
#endif

        if (!request->u.addrinfo.protocol)
                {
                flags |= kDNSServiceFlagsSuppressUnusable;
                request->u.addrinfo.protocol = (kDNSServiceProtocol_IPv4 | kDNSServiceProtocol_IPv6);
                }

        request->u.addrinfo.q4.InterfaceID      = request->u.addrinfo.q6.InterfaceID      = request->u.addrinfo.interface_id;
        request->u.addrinfo.q4.Target           = request->u.addrinfo.q6.Target           = zeroAddr;
        request->u.addrinfo.q4.qname            = request->u.addrinfo.q6.qname            = d;
        request->u.addrinfo.q4.qclass           = request->u.addrinfo.q6.qclass           = kDNSServiceClass_IN;
        request->u.addrinfo.q4.LongLived        = request->u.addrinfo.q6.LongLived        = (flags & kDNSServiceFlagsLongLivedQuery     ) != 0;
        request->u.addrinfo.q4.ExpectUnique     = request->u.addrinfo.q6.ExpectUnique     = mDNSfalse;
        request->u.addrinfo.q4.ForceMCast       = request->u.addrinfo.q6.ForceMCast       = (flags & kDNSServiceFlagsForceMulticast     ) != 0;
        request->u.addrinfo.q4.ReturnIntermed   = request->u.addrinfo.q6.ReturnIntermed   = (flags & kDNSServiceFlagsReturnIntermediates) != 0;
        request->u.addrinfo.q4.SuppressUnusable = request->u.addrinfo.q6.SuppressUnusable = (flags & kDNSServiceFlagsSuppressUnusable   ) != 0;
        request->u.addrinfo.q4.TimeoutQuestion  = request->u.addrinfo.q6.TimeoutQuestion  = (flags & kDNSServiceFlagsTimeout            ) != 0;
        request->u.addrinfo.q4.WakeOnResolve    = request->u.addrinfo.q6.WakeOnResolve    = 0;
        request->u.addrinfo.q4.qnameOrig        = request->u.addrinfo.q6.qnameOrig        = mDNSNULL;

        if (request->u.addrinfo.protocol & kDNSServiceProtocol_IPv4)
                {
                request->u.addrinfo.q4.qtype            = kDNSServiceType_A;
                request->u.addrinfo.q4.SearchListIndex  = 0;

                // We append search domains only for queries that are a single label. If overriden using
                // command line argument "AlwaysAppendSearchDomains", then we do it for any query which
                // is not fully qualified.
                if (hostname[strlen(hostname) - 1] != '.' && (AlwaysAppendSearchDomains || CountLabels(&d) == 1))
                        {
                        request->u.addrinfo.q4.AppendSearchDomains = 1;
                        request->u.addrinfo.q4.AppendLocalSearchDomains = 1;
                        }
                else
                        {
                        request->u.addrinfo.q4.AppendSearchDomains = 0;
                        request->u.addrinfo.q4.AppendLocalSearchDomains = 0;
                        }
                request->u.addrinfo.q4.RetryWithSearchDomains = (ApplySearchDomainsFirst(&request->u.addrinfo.q4) ? 1 : 0);
                request->u.addrinfo.q4.QuestionCallback = queryrecord_result_callback;
                request->u.addrinfo.q4.QuestionContext  = request;
                err = mDNS_StartQuery(&mDNSStorage, &request->u.addrinfo.q4);
                if (err != mStatus_NoError)
                        {
                        LogMsg("ERROR: mDNS_StartQuery: %d", (int)err);
                        request->u.addrinfo.q4.QuestionContext = mDNSNULL;
                        }
                #if APPLE_OSX_mDNSResponder
                err = SendAdditionalQuery(&request->u.addrinfo.q4, request, err);
                #endif // APPLE_OSX_mDNSResponder
                }

        if (!err && (request->u.addrinfo.protocol & kDNSServiceProtocol_IPv6))
                {
                request->u.addrinfo.q6.qtype            = kDNSServiceType_AAAA;
                request->u.addrinfo.q6.SearchListIndex  = 0;
                if (hostname[strlen(hostname) - 1] != '.' && (AlwaysAppendSearchDomains || CountLabels(&d) == 1))
                        {
                        request->u.addrinfo.q6.AppendSearchDomains = 1;
                        request->u.addrinfo.q6.AppendLocalSearchDomains = 1;
                        }
                else
                        {
                        request->u.addrinfo.q6.AppendSearchDomains = 0;
                        request->u.addrinfo.q6.AppendLocalSearchDomains = 0;
                        }
                request->u.addrinfo.q6.RetryWithSearchDomains = (ApplySearchDomainsFirst(&request->u.addrinfo.q6) ? 1 : 0);
                request->u.addrinfo.q6.QuestionCallback = queryrecord_result_callback;
                request->u.addrinfo.q6.QuestionContext  = request;
                err = mDNS_StartQuery(&mDNSStorage, &request->u.addrinfo.q6);
                if (err != mStatus_NoError)
                        {
                        LogMsg("ERROR: mDNS_StartQuery: %d", (int)err);
                        request->u.addrinfo.q6.QuestionContext = mDNSNULL;
                        if (request->u.addrinfo.protocol & kDNSServiceProtocol_IPv4)
                                {
                                // If we started a query for IPv4, we need to cancel it
                                mDNS_StopQuery(&mDNSStorage, &request->u.addrinfo.q4);
                                request->u.addrinfo.q4.QuestionContext = mDNSNULL;
                                }
                        }
                #if APPLE_OSX_mDNSResponder
                err = SendAdditionalQuery(&request->u.addrinfo.q6, request, err);
                #endif // APPLE_OSX_mDNSResponder
                }

        LogOperation("%3d: DNSServiceGetAddrInfo(%X, %d, %d, %##s) START",
                request->sd, flags, interfaceIndex, request->u.addrinfo.protocol, d.c);

        if (!err) request->terminate = addrinfo_termination_callback;

        return(err);
        }

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Main Request Handler etc.
#endif

mDNSlocal request_state *NewRequest(void)
        {
        request_state **p = &all_requests;
        while (*p) p=&(*p)->next;
        *p = mallocL("request_state", sizeof(request_state));
        if (!*p) FatalError("ERROR: malloc");
        mDNSPlatformMemZero(*p, sizeof(request_state));
        return(*p);
        }

// read_msg may be called any time when the transfer state (req->ts) is t_morecoming.
// if there is no data on the socket, the socket will be closed and t_terminated will be returned
mDNSlocal void read_msg(request_state *req)
        {
        if (req->ts == t_terminated || req->ts == t_error)
                { LogMsg("%3d: ERROR: read_msg called with transfer state terminated or error", req->sd); req->ts = t_error; return; }

        if (req->ts == t_complete)      // this must be death or something is wrong
                {
                char buf[4];    // dummy for death notification
                int nread = udsSupportReadFD(req->sd, buf, 4, 0, req->platform_data);
                if (!nread) { req->ts = t_terminated; return; }
                if (nread < 0) goto rerror;
                LogMsg("%3d: ERROR: read data from a completed request", req->sd);
                req->ts = t_error;
                return;
                }

        if (req->ts != t_morecoming)
                { LogMsg("%3d: ERROR: read_msg called with invalid transfer state (%d)", req->sd, req->ts); req->ts = t_error; return; }

        if (req->hdr_bytes < sizeof(ipc_msg_hdr))
                {
                mDNSu32 nleft = sizeof(ipc_msg_hdr) - req->hdr_bytes;
                int nread = udsSupportReadFD(req->sd, (char *)&req->hdr + req->hdr_bytes, nleft, 0, req->platform_data);
                if (nread == 0) { req->ts = t_terminated; return; }
                if (nread < 0) goto rerror;
                req->hdr_bytes += nread;
                if (req->hdr_bytes > sizeof(ipc_msg_hdr))
                        { LogMsg("%3d: ERROR: read_msg - read too many header bytes", req->sd); req->ts = t_error; return; }

                // only read data if header is complete
                if (req->hdr_bytes == sizeof(ipc_msg_hdr))
                        {
                        ConvertHeaderBytes(&req->hdr);
                        if (req->hdr.version != VERSION)
                                { LogMsg("%3d: ERROR: client version 0x%08X daemon version 0x%08X", req->sd, req->hdr.version, VERSION); req->ts = t_error; return; }

                        // Largest conceivable single request is a DNSServiceRegisterRecord() or DNSServiceAddRecord()
                        // with 64kB of rdata. Adding 1009 byte for a maximal domain name, plus a safety margin
                        // for other overhead, this means any message above 70kB is definitely bogus.
                        if (req->hdr.datalen > 70000)
                                { LogMsg("%3d: ERROR: read_msg: hdr.datalen %u (0x%X) > 70000", req->sd, req->hdr.datalen, req->hdr.datalen); req->ts = t_error; return; }
                        req->msgbuf = mallocL("request_state msgbuf", req->hdr.datalen + MSG_PAD_BYTES);
                        if (!req->msgbuf) { my_perror("ERROR: malloc"); req->ts = t_error; return; }
                        req->msgptr = req->msgbuf;
                        req->msgend = req->msgbuf + req->hdr.datalen;
                        mDNSPlatformMemZero(req->msgbuf, req->hdr.datalen + MSG_PAD_BYTES);
                        }
                }

        // If our header is complete, but we're still needing more body data, then try to read it now
        // Note: For cancel_request req->hdr.datalen == 0, but there's no error return socket for cancel_request
        // Any time we need to get the error return socket we know we'll have at least one data byte
        // (even if only the one-byte empty C string placeholder for the old ctrl_path parameter)
        if (req->hdr_bytes == sizeof(ipc_msg_hdr) && req->data_bytes < req->hdr.datalen)
                {
                mDNSu32 nleft = req->hdr.datalen - req->data_bytes;
                int nread;
#if !defined(_WIN32)
                struct iovec vec = { req->msgbuf + req->data_bytes, nleft };    // Tell recvmsg where we want the bytes put
                struct msghdr msg;
                struct cmsghdr *cmsg;
                char cbuf[CMSG_SPACE(sizeof(dnssd_sock_t))];
                msg.msg_name       = 0;
                msg.msg_namelen    = 0;
                msg.msg_iov        = &vec;
                msg.msg_iovlen     = 1;
                msg.msg_control    = cbuf;
                msg.msg_controllen = sizeof(cbuf);
                msg.msg_flags      = 0;
                nread = recvmsg(req->sd, &msg, 0);
#else
                nread = udsSupportReadFD(req->sd, (char *)req->msgbuf + req->data_bytes, nleft, 0, req->platform_data);
#endif
                if (nread == 0) { req->ts = t_terminated; return; }
                if (nread < 0) goto rerror;
                req->data_bytes += nread;
                if (req->data_bytes > req->hdr.datalen)
                        { LogMsg("%3d: ERROR: read_msg - read too many data bytes", req->sd); req->ts = t_error; return; }
#if !defined(_WIN32)
                cmsg = CMSG_FIRSTHDR(&msg);
#if DEBUG_64BIT_SCM_RIGHTS
                LogMsg("%3d: Expecting %d %d %d %d", req->sd, sizeof(cbuf),       sizeof(cbuf),   SOL_SOCKET,       SCM_RIGHTS);
                LogMsg("%3d: Got       %d %d %d %d", req->sd, msg.msg_controllen, cmsg->cmsg_len, cmsg->cmsg_level, cmsg->cmsg_type);
#endif // DEBUG_64BIT_SCM_RIGHTS
                if (msg.msg_controllen == sizeof(cbuf) &&
                        cmsg->cmsg_len     == CMSG_LEN(sizeof(dnssd_sock_t)) &&
                        cmsg->cmsg_level   == SOL_SOCKET   &&
                        cmsg->cmsg_type    == SCM_RIGHTS)
                        {
#if APPLE_OSX_mDNSResponder
                        // Strictly speaking BPF_fd belongs solely in the platform support layer, but because
                        // of privilege separation on Mac OS X we need to get BPF_fd from mDNSResponderHelper,
                        // and it's convenient to repurpose the existing fd-passing code here for that task
                        if (req->hdr.op == send_bpf)
                                {
                                dnssd_sock_t x = *(dnssd_sock_t *)CMSG_DATA(cmsg);
                                LogOperation("%3d: Got BPF %d", req->sd, x);
                                mDNSPlatformReceiveBPF_fd(&mDNSStorage, x);
                                }
                        else
#endif // APPLE_OSX_mDNSResponder
                                req->errsd = *(dnssd_sock_t *)CMSG_DATA(cmsg);
#if DEBUG_64BIT_SCM_RIGHTS
                        LogMsg("%3d: read req->errsd %d", req->sd, req->errsd);
#endif // DEBUG_64BIT_SCM_RIGHTS
                        if (req->data_bytes < req->hdr.datalen)
                                {
                                LogMsg("%3d: Client sent error socket %d via SCM_RIGHTS with req->data_bytes %d < req->hdr.datalen %d",
                                        req->sd, req->errsd, req->data_bytes, req->hdr.datalen);
                                req->ts = t_error;
                                return;
                                }
                        }
#endif
                }

        // If our header and data are both complete, see if we need to make our separate error return socket
        if (req->hdr_bytes == sizeof(ipc_msg_hdr) && req->data_bytes == req->hdr.datalen)
                {
                if (req->terminate && req->hdr.op != cancel_request)
                        {
                        dnssd_sockaddr_t cliaddr;
#if defined(USE_TCP_LOOPBACK)
                        mDNSOpaque16 port;
                        u_long opt = 1;
                        port.b[0] = req->msgptr[0];
                        port.b[1] = req->msgptr[1];
                        req->msgptr += 2;
                        cliaddr.sin_family      = AF_INET;
                        cliaddr.sin_port        = port.NotAnInteger;
                        cliaddr.sin_addr.s_addr = inet_addr(MDNS_TCP_SERVERADDR);
#else
                        char ctrl_path[MAX_CTLPATH];
                        get_string(&req->msgptr, req->msgend, ctrl_path, MAX_CTLPATH);  // path is first element in message buffer
                        mDNSPlatformMemZero(&cliaddr, sizeof(cliaddr));
                        cliaddr.sun_family = AF_LOCAL;
                        mDNSPlatformStrCopy(cliaddr.sun_path, ctrl_path);
                        // If the error return path UDS name is empty string, that tells us
                        // that this is a new version of the library that's going to pass us
                        // the error return path socket via sendmsg/recvmsg
                        if (ctrl_path[0] == 0)
                                {
                                if (req->errsd == req->sd)
                                        { LogMsg("%3d: read_msg: ERROR failed to get errsd via SCM_RIGHTS", req->sd); req->ts = t_error; return; }
                                goto got_errfd;
                                }
#endif
        
                        req->errsd = socket(AF_DNSSD, SOCK_STREAM, 0);
                        if (!dnssd_SocketValid(req->errsd)) { my_perror("ERROR: socket"); req->ts = t_error; return; }

                        if (connect(req->errsd, (struct sockaddr *)&cliaddr, sizeof(cliaddr)) < 0)
                                {
#if !defined(USE_TCP_LOOPBACK)
                                struct stat sb;
                                LogMsg("%3d: read_msg: Couldn't connect to error return path socket “%s” errno %d (%s)",
                                        req->sd, cliaddr.sun_path, dnssd_errno, dnssd_strerror(dnssd_errno));
                                if (stat(cliaddr.sun_path, &sb) < 0)
                                        LogMsg("%3d: read_msg: stat failed “%s” errno %d (%s)", req->sd, cliaddr.sun_path, dnssd_errno, dnssd_strerror(dnssd_errno));
                                else
                                        LogMsg("%3d: read_msg: file “%s” mode %o (octal) uid %d gid %d", req->sd, cliaddr.sun_path, sb.st_mode, sb.st_uid, sb.st_gid);
#endif
                                req->ts = t_error;
                                return;
                                }
        
#if !defined(USE_TCP_LOOPBACK)
got_errfd:
#endif
                        LogOperation("%3d: Error socket %d created %08X %08X", req->sd, req->errsd, req->hdr.client_context.u32[1], req->hdr.client_context.u32[0]);
#if defined(_WIN32)
                        if (ioctlsocket(req->errsd, FIONBIO, &opt) != 0)
#else
                        if (fcntl(req->errsd, F_SETFL, fcntl(req->errsd, F_GETFL, 0) | O_NONBLOCK) != 0)
#endif
                                {
                                LogMsg("%3d: ERROR: could not set control socket to non-blocking mode errno %d (%s)",
                                        req->sd, dnssd_errno, dnssd_strerror(dnssd_errno));
                                req->ts = t_error;
                                return;
                                }
                        }
                
                req->ts = t_complete;
                }

        return;

rerror:
        if (dnssd_errno == dnssd_EWOULDBLOCK || dnssd_errno == dnssd_EINTR) return;
        LogMsg("%3d: ERROR: read_msg errno %d (%s)", req->sd, dnssd_errno, dnssd_strerror(dnssd_errno));
        req->ts = t_error;
        }

#define RecordOrientedOp(X) \
        ((X) == reg_record_request || (X) == add_record_request || (X) == update_record_request || (X) == remove_record_request)

// The lightweight operations are the ones that don't need a dedicated request_state structure allocated for them
#define LightweightOp(X) (RecordOrientedOp(X) || (X) == cancel_request)

mDNSlocal void request_callback(int fd, short filter, void *info)
        {
        mStatus err = 0;
        request_state *req = info;
        mDNSs32 min_size = sizeof(DNSServiceFlags);
        (void)fd; // Unused
        (void)filter; // Unused

        for (;;)
                {
                read_msg(req);
                if (req->ts == t_morecoming) return;
                if (req->ts == t_terminated || req->ts == t_error) { AbortUnlinkAndFree(req); return; }
                if (req->ts != t_complete) { LogMsg("req->ts %d != t_complete", req->ts); AbortUnlinkAndFree(req); return; }

                if (req->hdr.version != VERSION)
                        {
                        LogMsg("ERROR: client version %d incompatible with daemon version %d", req->hdr.version, VERSION);
                        AbortUnlinkAndFree(req);
                        return;
                        }

                switch(req->hdr.op)            //          Interface       + other data
                        {
                        case connection_request:       min_size = 0;                                                                           break;
                        case reg_service_request:      min_size += sizeof(mDNSu32) + 4 /* name, type, domain, host */ + 4 /* port, textlen */; break;
                        case add_record_request:       min_size +=                   4 /* type, rdlen */              + 4 /* ttl */;           break;
                        case update_record_request:    min_size +=                   2 /* rdlen */                    + 4 /* ttl */;           break;
                        case remove_record_request:                                                                                            break;
                        case browse_request:           min_size += sizeof(mDNSu32) + 2 /* type, domain */;                                     break;
                        case resolve_request:          min_size += sizeof(mDNSu32) + 3 /* type, type, domain */;                               break;
                        case query_request:            min_size += sizeof(mDNSu32) + 1 /* name */                     + 4 /* type, class*/;    break;
                        case enumeration_request:      min_size += sizeof(mDNSu32);                                                            break;
                        case reg_record_request:       min_size += sizeof(mDNSu32) + 1 /* name */ + 6 /* type, class, rdlen */ + 4 /* ttl */;  break;
                        case reconfirm_record_request: min_size += sizeof(mDNSu32) + 1 /* name */ + 6 /* type, class, rdlen */;                break;
                        case setdomain_request:        min_size +=                   1 /* domain */;                                           break;
                        case getproperty_request:      min_size = 2;                                                                           break;
                        case port_mapping_request:     min_size += sizeof(mDNSu32) + 4 /* udp/tcp */ + 4 /* int/ext port */    + 4 /* ttl */;  break;
                        case addrinfo_request:         min_size += sizeof(mDNSu32) + 4 /* v4/v6 */   + 1 /* hostname */;                       break;
                        case send_bpf:                 // Same as cancel_request below
                        case cancel_request:           min_size = 0;                                                                           break;
                        default: LogMsg("ERROR: validate_message - unsupported req type: %d", req->hdr.op); min_size = -1;                     break;
                        }

                if ((mDNSs32)req->data_bytes < min_size)
                        { LogMsg("Invalid message %d bytes; min for %d is %d", req->data_bytes, req->hdr.op, min_size); AbortUnlinkAndFree(req); return; }

                if (LightweightOp(req->hdr.op) && !req->terminate)
                        { LogMsg("Reg/Add/Update/Remove %d require existing connection", req->hdr.op);                  AbortUnlinkAndFree(req); return; }

                // check if client wants silent operation
                if (req->hdr.ipc_flags & IPC_FLAGS_NOREPLY) req->no_reply = 1;

                // If req->terminate is already set, this means this operation is sharing an existing connection
                if (req->terminate && !LightweightOp(req->hdr.op))
                        {
                        request_state *newreq = NewRequest();
                        newreq->primary = req;
                        newreq->sd      = req->sd;
                        newreq->errsd   = req->errsd;
                        newreq->uid     = req->uid;
                        newreq->hdr     = req->hdr;
                        newreq->msgbuf  = req->msgbuf;
                        newreq->msgptr  = req->msgptr;
                        newreq->msgend  = req->msgend;
                        req = newreq;
                        }

                // If we're shutting down, don't allow new client requests
                // We do allow "cancel" and "getproperty" during shutdown
                if (mDNSStorage.ShutdownTime && req->hdr.op != cancel_request && req->hdr.op != getproperty_request)
                        {
                        err = mStatus_ServiceNotRunning;
                        }
                else switch(req->hdr.op)
                        {
                        // These are all operations that have their own first-class request_state object
                        case connection_request:           LogOperation("%3d: DNSServiceCreateConnection START", req->sd);
                                                                                           req->terminate = connection_termination; break;
                        case resolve_request:              err = handle_resolve_request     (req);  break;
                        case query_request:                err = handle_queryrecord_request (req);  break;
                        case browse_request:               err = handle_browse_request      (req);  break;
                        case reg_service_request:          err = handle_regservice_request  (req);  break;
                        case enumeration_request:          err = handle_enum_request        (req);  break;
                        case reconfirm_record_request:     err = handle_reconfirm_request   (req);  break;
                        case setdomain_request:            err = handle_setdomain_request   (req);  break;
                        case getproperty_request:                handle_getproperty_request (req);  break;
                        case port_mapping_request:         err = handle_port_mapping_request(req);  break;
                        case addrinfo_request:             err = handle_addrinfo_request    (req);  break;
                        case send_bpf:                     /* Do nothing for send_bpf */            break;

                        // These are all operations that work with an existing request_state object
                        case reg_record_request:           err = handle_regrecord_request   (req);  break;
                        case add_record_request:           err = handle_add_request         (req);  break;
                        case update_record_request:        err = handle_update_request      (req);  break;
                        case remove_record_request:        err = handle_removerecord_request(req);  break;
                        case cancel_request:                     handle_cancel_request      (req);  break;
                        default: LogMsg("%3d: ERROR: Unsupported UDS req: %d", req->sd, req->hdr.op);
                        }

                // req->msgbuf may be NULL, e.g. for connection_request or remove_record_request
                if (req->msgbuf) freeL("request_state msgbuf", req->msgbuf);

                // There's no return data for a cancel request (DNSServiceRefDeallocate returns no result)
                // For a DNSServiceGetProperty call, the handler already generated the response, so no need to do it again here
                if (req->hdr.op != cancel_request && req->hdr.op != getproperty_request && req->hdr.op != send_bpf)
                        {
                        const mStatus err_netorder = dnssd_htonl(err);
                        send_all(req->errsd, (const char *)&err_netorder, sizeof(err_netorder));
                        if (req->errsd != req->sd)
                                {
                                LogOperation("%3d: Error socket %d closed  %08X %08X (%d)",
                                        req->sd, req->errsd, req->hdr.client_context.u32[1], req->hdr.client_context.u32[0], err);
                                dnssd_close(req->errsd);
                                req->errsd = req->sd;
                                // Also need to reset the parent's errsd, if this is a subordinate operation
                                if (req->primary) req->primary->errsd = req->primary->sd;
                                }
                        }

                // Reset ready to accept the next req on this pipe
                if (req->primary) req = req->primary;
                req->ts         = t_morecoming;
                req->hdr_bytes  = 0;
                req->data_bytes = 0;
                req->msgbuf     = mDNSNULL;
                req->msgptr     = mDNSNULL;
                req->msgend     = 0;
                }
        }

mDNSlocal void connect_callback(int fd, short filter, void *info)
        {
        dnssd_sockaddr_t cliaddr;
        dnssd_socklen_t len = (dnssd_socklen_t) sizeof(cliaddr);
        dnssd_sock_t sd = accept(fd, (struct sockaddr*) &cliaddr, &len);
#if defined(SO_NOSIGPIPE) || defined(_WIN32)
        unsigned long optval = 1;
#endif

        (void)filter; // Unused
        (void)info; // Unused

        if (!dnssd_SocketValid(sd))
                {
                if (dnssd_errno != dnssd_EWOULDBLOCK) my_perror("ERROR: accept");
                return;
                }

#ifdef SO_NOSIGPIPE
        // Some environments (e.g. OS X) support turning off SIGPIPE for a socket
        if (setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval)) < 0)
                LogMsg("%3d: WARNING: setsockopt - SO_NOSIGPIPE %d (%s)", sd, dnssd_errno, dnssd_strerror(dnssd_errno));
#endif

#if defined(_WIN32)
        if (ioctlsocket(sd, FIONBIO, &optval) != 0)
#else
        if (fcntl(sd, F_SETFL, fcntl(sd, F_GETFL, 0) | O_NONBLOCK) != 0)
#endif
                {
                my_perror("ERROR: fcntl(sd, F_SETFL, O_NONBLOCK) - aborting client");
                dnssd_close(sd);
                return;
                }
        else
                {
                request_state *request = NewRequest();
                request->ts    = t_morecoming;
                request->sd    = sd;
                request->errsd = sd;
#if APPLE_OSX_mDNSResponder
                struct xucred x;
                socklen_t xucredlen = sizeof(x);
                if (getsockopt(sd, 0, LOCAL_PEERCRED, &x, &xucredlen) >= 0 && x.cr_version == XUCRED_VERSION) request->uid = x.cr_uid;
                else my_perror("ERROR: getsockopt, LOCAL_PEERCRED");
                debugf("LOCAL_PEERCRED %d %u %u %d", xucredlen, x.cr_version, x.cr_uid, x.cr_ngroups);
#endif // APPLE_OSX_mDNSResponder
                LogOperation("%3d: Adding FD for uid %u", request->sd, request->uid);
                udsSupportAddFDToEventLoop(sd, request_callback, request, &request->platform_data);
                }
        }

mDNSlocal mDNSBool uds_socket_setup(dnssd_sock_t skt)
        {
#if defined(SO_NP_EXTENSIONS)
        struct          so_np_extensions sonpx;
        socklen_t       optlen = sizeof(struct so_np_extensions);
        sonpx.npx_flags = SONPX_SETOPTSHUT;
        sonpx.npx_mask  = SONPX_SETOPTSHUT;
        if (setsockopt(skt, SOL_SOCKET, SO_NP_EXTENSIONS, &sonpx, optlen) < 0)
                my_perror("WARNING: could not set sockopt - SO_NP_EXTENSIONS");
#endif
#if defined(_WIN32)
        // SEH: do we even need to do this on windows?
        // This socket will be given to WSAEventSelect which will automatically set it to non-blocking
        u_long opt = 1;
        if (ioctlsocket(skt, FIONBIO, &opt) != 0)
#else
        if (fcntl(skt, F_SETFL, fcntl(skt, F_GETFL, 0) | O_NONBLOCK) != 0)
#endif
                {
                my_perror("ERROR: could not set listen socket to non-blocking mode");
                return mDNSfalse;
                }

        if (listen(skt, LISTENQ) != 0)
                {
                my_perror("ERROR: could not listen on listen socket");
                return mDNSfalse;
                }

        if (mStatus_NoError != udsSupportAddFDToEventLoop(skt, connect_callback, (void *) NULL, (void **) NULL))
                {
                my_perror("ERROR: could not add listen socket to event loop");
                return mDNSfalse;
                }
        else LogOperation("%3d: Listening for incoming Unix Domain Socket client requests", skt);
        
        return mDNStrue;
        }

mDNSexport int udsserver_init(dnssd_sock_t skts[], mDNSu32 count)
        {
        dnssd_sockaddr_t laddr;
        int ret;
        mDNSu32 i = 0;

        LogInfo("udsserver_init");

        // If a particular platform wants to opt out of having a PID file, define PID_FILE to be ""
        if (PID_FILE[0])
                {
                FILE *fp = fopen(PID_FILE, "w");
                if (fp != NULL)
                        {
                        fprintf(fp, "%d\n", getpid());
                        fclose(fp);
                        }
                }

        if (skts)
                {
                for (i = 0; i < count; i++)
                        if (dnssd_SocketValid(skts[i]) && !uds_socket_setup(skts[i]))
                                goto error;
                }
        else
                {
                listenfd = socket(AF_DNSSD, SOCK_STREAM, 0);
                if (!dnssd_SocketValid(listenfd))
                        {
                        my_perror("ERROR: socket(AF_DNSSD, SOCK_STREAM, 0); failed");
                        goto error;
                        }

                mDNSPlatformMemZero(&laddr, sizeof(laddr));

                #if defined(USE_TCP_LOOPBACK)
                        {
                        laddr.sin_family = AF_INET;
                        laddr.sin_port = htons(MDNS_TCP_SERVERPORT);
                        laddr.sin_addr.s_addr = inet_addr(MDNS_TCP_SERVERADDR);
                        ret = bind(listenfd, (struct sockaddr *) &laddr, sizeof(laddr));
                        if (ret < 0)
                                {
                                my_perror("ERROR: bind(listenfd, (struct sockaddr *) &laddr, sizeof(laddr)); failed");
                                goto error;
                                }
                        }
                #else
                        {
                        mode_t mask = umask(0);
                        unlink(MDNS_UDS_SERVERPATH);  // OK if this fails
                        laddr.sun_family = AF_LOCAL;
                        #ifndef NOT_HAVE_SA_LEN
                        // According to Stevens (section 3.2), there is no portable way to
                        // determine whether sa_len is defined on a particular platform.
                        laddr.sun_len = sizeof(struct sockaddr_un);
                        #endif
                        mDNSPlatformStrCopy(laddr.sun_path, MDNS_UDS_SERVERPATH);
                        ret = bind(listenfd, (struct sockaddr *) &laddr, sizeof(laddr));
                        umask(mask);
                        if (ret < 0)
                                {
                                my_perror("ERROR: bind(listenfd, (struct sockaddr *) &laddr, sizeof(laddr)); failed");
                                goto error;
                                }
                        }
                #endif
                
                if (!uds_socket_setup(listenfd)) goto error;
                }

#if !defined(PLATFORM_NO_RLIMIT)
        {
        // Set maximum number of open file descriptors
        #define MIN_OPENFILES 10240
        struct rlimit maxfds, newfds;

        // Due to bugs in OS X (<rdar://problem/2941095>, <rdar://problem/3342704>, <rdar://problem/3839173>)
        // you have to get and set rlimits once before getrlimit will return sensible values
        if (getrlimit(RLIMIT_NOFILE, &maxfds) < 0) { my_perror("ERROR: Unable to get file descriptor limit"); return 0; }
        if (setrlimit(RLIMIT_NOFILE, &maxfds) < 0) my_perror("ERROR: Unable to set maximum file descriptor limit");

        if (getrlimit(RLIMIT_NOFILE, &maxfds) < 0) { my_perror("ERROR: Unable to get file descriptor limit"); return 0; }
        newfds.rlim_max = (maxfds.rlim_max > MIN_OPENFILES) ? maxfds.rlim_max : MIN_OPENFILES;
        newfds.rlim_cur = (maxfds.rlim_cur > MIN_OPENFILES) ? maxfds.rlim_cur : MIN_OPENFILES;
        if (newfds.rlim_max != maxfds.rlim_max || newfds.rlim_cur != maxfds.rlim_cur)
                if (setrlimit(RLIMIT_NOFILE, &newfds) < 0) my_perror("ERROR: Unable to set maximum file descriptor limit");

        if (getrlimit(RLIMIT_NOFILE, &maxfds) < 0) { my_perror("ERROR: Unable to get file descriptor limit"); return 0; }
        debugf("maxfds.rlim_max %d", (long)maxfds.rlim_max);
        debugf("maxfds.rlim_cur %d", (long)maxfds.rlim_cur);
        }
#endif

        // We start a "LocalOnly" query looking for Automatic Browse Domain records.
        // When Domain Enumeration in uDNS.c finds an "lb" record from the network, its "FoundDomain" routine
        // creates a "LocalOnly" record, which results in our AutomaticBrowseDomainChange callback being invoked
        mDNS_GetDomains(&mDNSStorage, &mDNSStorage.AutomaticBrowseDomainQ, mDNS_DomainTypeBrowseAutomatic,
                mDNSNULL, mDNSInterface_LocalOnly, AutomaticBrowseDomainChange, mDNSNULL);

        // Add "local" as recommended registration domain ("dns-sd -E"), recommended browsing domain ("dns-sd -F"), and automatic browsing domain
        RegisterLocalOnlyDomainEnumPTR(&mDNSStorage, &localdomain, mDNS_DomainTypeRegistration);
        RegisterLocalOnlyDomainEnumPTR(&mDNSStorage, &localdomain, mDNS_DomainTypeBrowse);
        AddAutoBrowseDomain(0, &localdomain);

        udsserver_handle_configchange(&mDNSStorage);
        return 0;

error:

        my_perror("ERROR: udsserver_init");
        return -1;
        }

mDNSexport int udsserver_exit(void)
        {
        // Cancel all outstanding client requests
        while (all_requests) AbortUnlinkAndFree(all_requests);

        // Clean up any special mDNSInterface_LocalOnly records we created, both the entries for "local" we
        // created in udsserver_init, and others we created as a result of reading local configuration data
        while (LocalDomainEnumRecords)
                {
                ARListElem *rem = LocalDomainEnumRecords;
                LocalDomainEnumRecords = LocalDomainEnumRecords->next;
                mDNS_Deregister(&mDNSStorage, &rem->ar);
                }

        // If the launching environment created no listening socket,
        // that means we created it ourselves, so we should clean it up on exit
        if (dnssd_SocketValid(listenfd))
                {
                dnssd_close(listenfd);
#if !defined(USE_TCP_LOOPBACK)
                // Currently, we're unable to remove /var/run/mdnsd because we've changed to userid "nobody"
                // to give up unnecessary privilege, but we need to be root to remove this Unix Domain Socket.
                // It would be nice if we could find a solution to this problem
                if (unlink(MDNS_UDS_SERVERPATH))
                        debugf("Unable to remove %s", MDNS_UDS_SERVERPATH);
#endif
                }

        if (PID_FILE[0]) unlink(PID_FILE);

        return 0;
        }

mDNSlocal void LogClientInfo(mDNS *const m, const request_state *req)
        {
        char prefix[16];
        if (req->primary) mDNS_snprintf(prefix, sizeof(prefix), " -> ");
        else mDNS_snprintf(prefix, sizeof(prefix), "%3d:", req->sd);

        usleep((m->KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);

        if (!req->terminate)
                LogMsgNoIdent("%s No operation yet on this socket", prefix);
        else if (req->terminate == connection_termination)
                {
                int num_records = 0, num_ops = 0;
                const registered_record_entry *p;
                const request_state *r;
                for (p = req->u.reg_recs; p; p=p->next) num_records++;
                for (r = req->next; r; r=r->next) if (r->primary == req) num_ops++;
                LogMsgNoIdent("%s DNSServiceCreateConnection: %d registered record%s, %d kDNSServiceFlagsShareConnection operation%s", prefix,
                        num_records, num_records != 1 ? "s" : "",
                        num_ops,     num_ops     != 1 ? "s" : "");
                for (p = req->u.reg_recs; p; p=p->next)
                        LogMsgNoIdent(" ->  DNSServiceRegisterRecord %3d %s", p->key, ARDisplayString(m, p->rr));
                for (r = req->next; r; r=r->next) if (r->primary == req) LogClientInfo(m, r);
                }
        else if (req->terminate == regservice_termination_callback)
                {
                service_instance *ptr;
                for (ptr = req->u.servicereg.instances; ptr; ptr = ptr->next)
                        LogMsgNoIdent("%s DNSServiceRegister         %##s %u/%u",
                                (ptr == req->u.servicereg.instances) ? prefix : "    ",
                                ptr->srs.RR_SRV.resrec.name->c, mDNSVal16(req->u.servicereg.port), SRS_PORT(&ptr->srs));
                }
        else if (req->terminate == browse_termination_callback)
                {
                browser_t *blist;
                for (blist = req->u.browser.browsers; blist; blist = blist->next)
                        LogMsgNoIdent("%s DNSServiceBrowse           %##s", (blist == req->u.browser.browsers) ? prefix : "    ", blist->q.qname.c);
                }
        else if (req->terminate == resolve_termination_callback)
                LogMsgNoIdent("%s DNSServiceResolve          %##s", prefix, req->u.resolve.qsrv.qname.c);
        else if (req->terminate == queryrecord_termination_callback)
                LogMsgNoIdent("%s DNSServiceQueryRecord      %##s (%s)", prefix, req->u.queryrecord.q.qname.c, DNSTypeName(req->u.queryrecord.q.qtype));
        else if (req->terminate == enum_termination_callback)
                LogMsgNoIdent("%s DNSServiceEnumerateDomains %##s", prefix, req->u.enumeration.q_all.qname.c);
        else if (req->terminate == port_mapping_termination_callback)
                LogMsgNoIdent("%s DNSServiceNATPortMapping   %.4a %s%s Int %d Req %d Ext %d Req TTL %d Granted TTL %d",
                        prefix,
                        &req->u.pm.NATinfo.ExternalAddress,
                        req->u.pm.NATinfo.Protocol & NATOp_MapTCP ? "TCP" : "   ",
                        req->u.pm.NATinfo.Protocol & NATOp_MapUDP ? "UDP" : "   ",
                        mDNSVal16(req->u.pm.NATinfo.IntPort),
                        mDNSVal16(req->u.pm.ReqExt),
                        mDNSVal16(req->u.pm.NATinfo.ExternalPort),
                        req->u.pm.NATinfo.NATLease,
                        req->u.pm.NATinfo.Lifetime);
        else if (req->terminate == addrinfo_termination_callback)
                LogMsgNoIdent("%s DNSServiceGetAddrInfo      %s%s %##s", prefix,
                        req->u.addrinfo.protocol & kDNSServiceProtocol_IPv4 ? "v4" : "  ",
                        req->u.addrinfo.protocol & kDNSServiceProtocol_IPv6 ? "v6" : "  ",
                        req->u.addrinfo.q4.qname.c);
        else
                LogMsgNoIdent("%s Unrecognized operation %p", prefix, req->terminate);
        }

mDNSlocal char *RecordTypeName(mDNSu8 rtype)
        {
        switch (rtype)
                {
                case kDNSRecordTypeUnregistered:  return ("Unregistered ");
                case kDNSRecordTypeDeregistering: return ("Deregistering");
                case kDNSRecordTypeUnique:        return ("Unique       ");
                case kDNSRecordTypeAdvisory:      return ("Advisory     ");
                case kDNSRecordTypeShared:        return ("Shared       ");
                case kDNSRecordTypeVerified:      return ("Verified     ");
                case kDNSRecordTypeKnownUnique:   return ("KnownUnique  ");
                default: return("Unknown");
                }
        }

mDNSlocal void LogEtcHosts(mDNS *const m)
        {
        mDNSBool showheader = mDNStrue;
        const AuthRecord *ar;
        mDNSu32 slot;
        AuthGroup *ag;
        int count = 0;
        int authslot = 0;
        mDNSBool truncated = 0;

        for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
                {
                if (m->rrauth.rrauth_hash[slot]) authslot++;
                for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next)
                        for (ar = ag->members; ar; ar = ar->next)
                                {
                                if (ar->RecordCallback != FreeEtcHosts) continue;
                                if (showheader) { showheader = mDNSfalse; LogMsgNoIdent("  State       Interface"); }
                
                                // Print a maximum of 50 records
                                if (count++ >= 50) { truncated = mDNStrue; continue; }
                                if (ar->ARType == AuthRecordLocalOnly)
                                        {
                                        if (ar->resrec.InterfaceID == mDNSInterface_LocalOnly)
                                                LogMsgNoIdent(" %s   LO %s", RecordTypeName(ar->resrec.RecordType), ARDisplayString(m, ar));
                                        else
                                                {
                                                mDNSu32 scopeid  = (mDNSu32)(uintptr_t)ar->resrec.InterfaceID;
                                                LogMsgNoIdent(" %s   %u  %s", RecordTypeName(ar->resrec.RecordType), scopeid, ARDisplayString(m, ar));
                                                }
                                        }
                                usleep((m->KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);
                                }
                }

        if (showheader) LogMsgNoIdent("<None>");
        else if (truncated) LogMsgNoIdent("<Truncated: to 50 records, Total records %d, Total Auth Groups %d, Auth Slots %d>", count, m->rrauth.rrauth_totalused, authslot);
        }

mDNSlocal void LogLocalOnlyAuthRecords(mDNS *const m)
        {
        mDNSBool showheader = mDNStrue;
        const AuthRecord *ar;
        mDNSu32 slot;
        AuthGroup *ag;

        for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
                {
                for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next)
                        for (ar = ag->members; ar; ar = ar->next)
                                {
                                if (ar->RecordCallback == FreeEtcHosts) continue;
                                if (showheader) { showheader = mDNSfalse; LogMsgNoIdent("  State       Interface"); }
                
                                // Print a maximum of 400 records
                                if (ar->ARType == AuthRecordLocalOnly)
                                        LogMsgNoIdent(" %s   LO %s", RecordTypeName(ar->resrec.RecordType), ARDisplayString(m, ar));
                                else if (ar->ARType == AuthRecordP2P)
                                        LogMsgNoIdent(" %s   PP %s", RecordTypeName(ar->resrec.RecordType), ARDisplayString(m, ar));
                                usleep((m->KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);
                                }
                }

        if (showheader) LogMsgNoIdent("<None>");
        }

mDNSlocal void LogAuthRecords(mDNS *const m, const mDNSs32 now, AuthRecord *ResourceRecords, int *proxy)
        {
        mDNSBool showheader = mDNStrue;
        const AuthRecord *ar;
        OwnerOptData owner = zeroOwner;
        for (ar = ResourceRecords; ar; ar=ar->next)
                {
                const char *const ifname = InterfaceNameForID(m, ar->resrec.InterfaceID);
                if ((ar->WakeUp.HMAC.l[0] != 0) == (proxy != mDNSNULL))
                        {
                        if (showheader) { showheader = mDNSfalse; LogMsgNoIdent("    Int    Next  Expire   State"); }
                        if (proxy) (*proxy)++;
                        if (!mDNSPlatformMemSame(&owner, &ar->WakeUp, sizeof(owner)))
                                {
                                owner = ar->WakeUp;
                                if (owner.password.l[0])
                                        LogMsgNoIdent("Proxying for H-MAC %.6a I-MAC %.6a Password %.6a seq %d", &owner.HMAC, &owner.IMAC, &owner.password, owner.seq);
                                else if (!mDNSSameEthAddress(&owner.HMAC, &owner.IMAC))
                                        LogMsgNoIdent("Proxying for H-MAC %.6a I-MAC %.6a seq %d",               &owner.HMAC, &owner.IMAC,                  owner.seq);
                                else
                                        LogMsgNoIdent("Proxying for %.6a seq %d",                                &owner.HMAC,                               owner.seq);
                                }
                        if (AuthRecord_uDNS(ar))
                                LogMsgNoIdent("%7d %7d %7d %7d %s",
                                        ar->ThisAPInterval / mDNSPlatformOneSecond,
                                        (ar->LastAPTime + ar->ThisAPInterval - now) / mDNSPlatformOneSecond,
                                        ar->expire ? (ar->expire - now) / mDNSPlatformOneSecond : 0,
                                        ar->state, ARDisplayString(m, ar));
                        else if (ar->ARType == AuthRecordLocalOnly)
                                LogMsgNoIdent("                             LO %s", ARDisplayString(m, ar));
                        else if (ar->ARType == AuthRecordP2P)
                                LogMsgNoIdent("                             PP %s", ARDisplayString(m, ar));
                        else
                                LogMsgNoIdent("%7d %7d %7d %7s %s",
                                        ar->ThisAPInterval / mDNSPlatformOneSecond,
                                        ar->AnnounceCount ? (ar->LastAPTime + ar->ThisAPInterval - now) / mDNSPlatformOneSecond : 0,
                                        ar->TimeExpire    ? (ar->TimeExpire                      - now) / mDNSPlatformOneSecond : 0,
                                        ifname ? ifname : "ALL",
                                        ARDisplayString(m, ar));
                        usleep((m->KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);
                        }
                }
        if (showheader) LogMsgNoIdent("<None>");
        }

mDNSexport void udsserver_info(mDNS *const m)
        {
        const mDNSs32 now = mDNS_TimeNow(m);
        mDNSu32 CacheUsed = 0, CacheActive = 0, slot;
        int ProxyA = 0, ProxyD = 0;
        const CacheGroup *cg;
        const CacheRecord *cr;
        const DNSQuestion *q;
        const DNameListElem *d;
        const SearchListElem *s;

        LogMsgNoIdent("Timenow 0x%08lX (%d)", (mDNSu32)now, now);

        LogMsgNoIdent("------------ Cache -------------");
        LogMsgNoIdent("Slt Q     TTL if     U Type rdlen");
        for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
                for (cg = m->rrcache_hash[slot]; cg; cg=cg->next)
                        {
                        CacheUsed++;    // Count one cache entity for the CacheGroup object
                        for (cr = cg->members; cr; cr=cr->next)
                                {
                                const mDNSs32 remain = cr->resrec.rroriginalttl - (now - cr->TimeRcvd) / mDNSPlatformOneSecond;
                                const char *ifname;
                                mDNSInterfaceID InterfaceID = cr->resrec.InterfaceID;
                                if (!InterfaceID && cr->resrec.rDNSServer)
                                        InterfaceID = cr->resrec.rDNSServer->interface;
                                ifname = InterfaceNameForID(m, InterfaceID);
                                CacheUsed++;
                                if (cr->CRActiveQuestion) CacheActive++;
                                LogMsgNoIdent("%3d %s%8ld %-7s%s %-6s%s",
                                        slot,
                                        cr->CRActiveQuestion ? "*" : " ",
                                        remain,
                                        ifname ? ifname : "-U-",
                                        (cr->resrec.RecordType == kDNSRecordTypePacketNegative)  ? "-" :
                                        (cr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) ? " " : "+",
                                        DNSTypeName(cr->resrec.rrtype),
                                        CRDisplayString(m, cr));
                                usleep((m->KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);
                                }
                        }

        if (m->rrcache_totalused != CacheUsed)
                LogMsgNoIdent("Cache use mismatch: rrcache_totalused is %lu, true count %lu", m->rrcache_totalused, CacheUsed);
        if (m->rrcache_active != CacheActive)
                LogMsgNoIdent("Cache use mismatch: rrcache_active is %lu, true count %lu", m->rrcache_active, CacheActive);
        LogMsgNoIdent("Cache currently contains %lu entities; %lu referenced by active questions", CacheUsed, CacheActive);

        LogMsgNoIdent("--------- Auth Records ---------");
        LogAuthRecords(m, now, m->ResourceRecords, mDNSNULL);

        LogMsgNoIdent("--------- LocalOnly, P2P Auth Records ---------");
        LogLocalOnlyAuthRecords(m);

        LogMsgNoIdent("--------- /etc/hosts ---------");
        LogEtcHosts(m);

        LogMsgNoIdent("------ Duplicate Records -------");
        LogAuthRecords(m, now, m->DuplicateRecords, mDNSNULL);

        LogMsgNoIdent("----- Auth Records Proxied -----");
        LogAuthRecords(m, now, m->ResourceRecords, &ProxyA);

        LogMsgNoIdent("-- Duplicate Records Proxied ---");
        LogAuthRecords(m, now, m->DuplicateRecords, &ProxyD);

        LogMsgNoIdent("---------- Questions -----------");
        if (!m->Questions) LogMsgNoIdent("<None>");
        else
                {
                CacheUsed = 0;
                CacheActive = 0;
                LogMsgNoIdent("   Int  Next if     T  NumAns VDNS    Qptr     DupOf    SU SQ Type Name");
                for (q = m->Questions; q; q=q->next)
                        {
                        mDNSs32 i = q->ThisQInterval / mDNSPlatformOneSecond;
                        mDNSs32 n = (NextQSendTime(q) - now) / mDNSPlatformOneSecond;
                        char *ifname = InterfaceNameForID(m, q->InterfaceID);
                        CacheUsed++;
                        if (q->ThisQInterval) CacheActive++;
                        LogMsgNoIdent("%6d%6d %-7s%s%s %5d 0x%x%x 0x%p 0x%p %1d %2d %-5s%##s%s",
                                i, n,
                                ifname ? ifname : mDNSOpaque16IsZero(q->TargetQID) ? "" : "-U-",
                                mDNSOpaque16IsZero(q->TargetQID) ? (q->LongLived ? "l" : " ") : (q->LongLived ? "L" : "O"),
                                PrivateQuery(q)    ? "P" : " ",
                                q->CurrentAnswers, q->validDNSServers.l[1], q->validDNSServers.l[0], q, q->DuplicateOf,
                                q->SuppressUnusable, q->SuppressQuery, DNSTypeName(q->qtype), q->qname.c, q->DuplicateOf ? " (dup)" : "");
                        usleep((m->KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);
                        }
                LogMsgNoIdent("%lu question%s; %lu active", CacheUsed, CacheUsed > 1 ? "s" : "", CacheActive);
                }

        LogMsgNoIdent("----- Local-Only Questions -----");
        if (!m->LocalOnlyQuestions) LogMsgNoIdent("<None>");
        else for (q = m->LocalOnlyQuestions; q; q=q->next)
                LogMsgNoIdent("                       %5d  %-6s%##s%s",
                        q->CurrentAnswers, DNSTypeName(q->qtype), q->qname.c, q->DuplicateOf ? " (dup)" : "");

        LogMsgNoIdent("---- Active Client Requests ----");
        if (!all_requests) LogMsgNoIdent("<None>");
        else
                {
                const request_state *req, *r;
                for (req = all_requests; req; req=req->next)
                        {
                        if (req->primary)       // If this is a subbordinate operation, check that the parent is in the list
                                {
                                for (r = all_requests; r && r != req; r=r->next) if (r == req->primary) goto foundparent;
                                LogMsgNoIdent("%3d: Orhpan operation %p; parent %p not found in request list", req->sd);
                                }
                        // For non-subbordinate operations, and subbordinate operations that have lost their parent, write out their info
                        LogClientInfo(m, req);
                        foundparent:;
                        }
                }

        LogMsgNoIdent("-------- NAT Traversals --------");
        if (!m->NATTraversals) LogMsgNoIdent("<None>");
        else
                {
                const NATTraversalInfo *nat;
                for (nat = m->NATTraversals; nat; nat=nat->next)
                        {
                        if (nat->Protocol)
                                LogMsgNoIdent("%p %s Int %5d Ext %5d Err %d Retry %5d Interval %5d Expire %5d",
                                        nat, nat->Protocol == NATOp_MapTCP ? "TCP" : "UDP",
                                        mDNSVal16(nat->IntPort), mDNSVal16(nat->ExternalPort), nat->Result,
                                        nat->retryPortMap ? (nat->retryPortMap - now) / mDNSPlatformOneSecond : 0,
                                        nat->retryInterval / mDNSPlatformOneSecond,
                                        nat->ExpiryTime ? (nat->ExpiryTime - now) / mDNSPlatformOneSecond : 0);
                        else
                                LogMsgNoIdent("%p Address Request               Retry %5d Interval %5d", nat,
                                        (m->retryGetAddr - now) / mDNSPlatformOneSecond,
                                        m->retryIntervalGetAddr / mDNSPlatformOneSecond);
                        usleep((m->KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);
                        }
                }

        LogMsgNoIdent("--------- AuthInfoList ---------");
        if (!m->AuthInfoList) LogMsgNoIdent("<None>");
        else
                {
                const DomainAuthInfo *a;
                for (a = m->AuthInfoList; a; a = a->next)
                        LogMsgNoIdent("%##s %##s %##s %d %s", a->domain.c, a->keyname.c, a->hostname.c, (a->port.b[0] << 8 | a->port.b[1]), a->AutoTunnel ? a->AutoTunnel : "");
                }

        #if APPLE_OSX_mDNSResponder
        LogMsgNoIdent("--------- TunnelClients --------");
        if (!m->TunnelClients) LogMsgNoIdent("<None>");
        else
                {
                const ClientTunnel *c;
                for (c = m->TunnelClients; c; c = c->next)
                        LogMsgNoIdent("%s %##s local %.16a %.4a %.16a remote %.16a %.4a %5d %.16a interval %d",
                                c->prefix, c->dstname.c, &c->loc_inner, &c->loc_outer, &c->loc_outer6, &c->rmt_inner, &c->rmt_outer, mDNSVal16(c->rmt_outer_port), &c->rmt_outer6, c->q.ThisQInterval);
                }
        #endif // APPLE_OSX_mDNSResponder

        LogMsgNoIdent("---------- Misc State ----------");

        LogMsgNoIdent("PrimaryMAC:   %.6a", &m->PrimaryMAC);

        LogMsgNoIdent("m->SleepState %d (%s) seq %d",
                m->SleepState,
                m->SleepState == SleepState_Awake        ? "Awake"        :
                m->SleepState == SleepState_Transferring ? "Transferring" : 
                m->SleepState == SleepState_Sleeping     ? "Sleeping"     : "?",
                m->SleepSeqNum);

        if (!m->SPSSocket) LogMsgNoIdent("Not offering Sleep Proxy Service");
        else LogMsgNoIdent("Offering Sleep Proxy Service: %#s", m->SPSRecords.RR_SRV.resrec.name->c);

        if (m->ProxyRecords == ProxyA + ProxyD) LogMsgNoIdent("ProxyRecords: %d + %d = %d", ProxyA, ProxyD, ProxyA + ProxyD);
        else LogMsgNoIdent("ProxyRecords: MISMATCH %d + %d = %d ≠ %d", ProxyA, ProxyD, ProxyA + ProxyD, m->ProxyRecords);

        LogMsgNoIdent("------ Auto Browse Domains -----");
        if (!AutoBrowseDomains) LogMsgNoIdent("<None>");
        else for (d=AutoBrowseDomains; d; d=d->next) LogMsgNoIdent("%##s", d->name.c);

        LogMsgNoIdent("--- Auto Registration Domains --");
        if (!AutoRegistrationDomains) LogMsgNoIdent("<None>");
        else for (d=AutoRegistrationDomains; d; d=d->next) LogMsgNoIdent("%##s", d->name.c);

        LogMsgNoIdent("--- Search Domains --");
        if (!SearchList) LogMsgNoIdent("<None>");
        else
                {
                for (s=SearchList; s; s=s->next)
                        {
                        char *ifname = InterfaceNameForID(m, s->InterfaceID);
                        LogMsgNoIdent("%##s %s", s->domain.c, ifname ? ifname : "");
                        }
                }

        LogMsgNoIdent("---- Task Scheduling Timers ----");

        if (!m->NewQuestions)
                LogMsgNoIdent("NewQuestion <NONE>");
        else
                LogMsgNoIdent("NewQuestion DelayAnswering %d %d %##s (%s)",
                        m->NewQuestions->DelayAnswering, m->NewQuestions->DelayAnswering-now,
                        m->NewQuestions->qname.c, DNSTypeName(m->NewQuestions->qtype));

        if (!m->NewLocalOnlyQuestions)
                LogMsgNoIdent("NewLocalOnlyQuestions <NONE>");
        else
                LogMsgNoIdent("NewLocalOnlyQuestions %##s (%s)",
                        m->NewLocalOnlyQuestions->qname.c, DNSTypeName(m->NewLocalOnlyQuestions->qtype));

        if (!m->NewLocalRecords)
                LogMsgNoIdent("NewLocalRecords <NONE>");
        else
                LogMsgNoIdent("NewLocalRecords %02X %s", m->NewLocalRecords->resrec.RecordType, ARDisplayString(m, m->NewLocalRecords));

        LogMsgNoIdent("SPSProxyListChanged%s", m->SPSProxyListChanged ? "" : " <NONE>");
        LogMsgNoIdent("LocalRemoveEvents%s",   m->LocalRemoveEvents   ? "" : " <NONE>");
        LogMsgNoIdent("m->RegisterAutoTunnel6  %08X", m->RegisterAutoTunnel6);
        LogMsgNoIdent("m->AutoTunnelRelayAddrIn  %.16a", &m->AutoTunnelRelayAddrIn);
        LogMsgNoIdent("m->AutoTunnelRelayAddrOut  %.16a", &m->AutoTunnelRelayAddrOut);

#define LogTimer(MSG,T) LogMsgNoIdent( MSG " %08X %11d  %08X %11d", (T), (T), (T)-now, (T)-now)

        LogMsgNoIdent("                         ABS (hex)  ABS (dec)  REL (hex)  REL (dec)");
        LogMsgNoIdent("m->timenow               %08X %11d", now, now);
        LogMsgNoIdent("m->timenow_adjust        %08X %11d", m->timenow_adjust, m->timenow_adjust);
        LogTimer("m->NextScheduledEvent   ", m->NextScheduledEvent);

#ifndef UNICAST_DISABLED
        LogTimer("m->NextuDNSEvent        ", m->NextuDNSEvent);
        LogTimer("m->NextSRVUpdate        ", m->NextSRVUpdate);
        LogTimer("m->NextScheduledNATOp   ", m->NextScheduledNATOp);
        LogTimer("m->retryGetAddr         ", m->retryGetAddr);
#endif

        LogTimer("m->NextCacheCheck       ", m->NextCacheCheck);
        LogTimer("m->NextScheduledSPS     ", m->NextScheduledSPS);
        LogTimer("m->NextScheduledSPRetry ", m->NextScheduledSPRetry);
        LogTimer("m->DelaySleep           ", m->DelaySleep);

        LogTimer("m->NextScheduledQuery   ", m->NextScheduledQuery);
        LogTimer("m->NextScheduledProbe   ", m->NextScheduledProbe);
        LogTimer("m->NextScheduledResponse", m->NextScheduledResponse);

        LogTimer("m->SuppressSending      ", m->SuppressSending);
        LogTimer("m->SuppressProbes       ", m->SuppressProbes);
        LogTimer("m->ProbeFailTime        ", m->ProbeFailTime);
        LogTimer("m->DelaySleep           ", m->DelaySleep);
        LogTimer("m->SleepLimit           ", m->SleepLimit);
        LogTimer("m->NextScheduledStopTime ", m->NextScheduledStopTime);
        }

#if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING
mDNSexport void uds_validatelists(void)
        {
        const request_state *req, *p;
        for (req = all_requests; req; req=req->next)
                {
                if (req->next == (request_state *)~0 || (req->sd < 0 && req->sd != -2))
                        LogMemCorruption("UDS request list: %p is garbage (%d)", req, req->sd);

                if (req->primary == req)
                        LogMemCorruption("UDS request list: req->primary should not point to self %p/%d", req, req->sd);

                if (req->primary && req->replies)
                        LogMemCorruption("UDS request list: Subordinate request %p/%d/%p should not have replies (%p)",
                                req, req->sd, req->primary && req->replies);

                p = req->primary;
                if ((long)p & 3)
                        LogMemCorruption("UDS request list: req %p primary %p is misaligned (%d)", req, p, req->sd);
                else if (p && (p->next == (request_state *)~0 || (p->sd < 0 && p->sd != -2)))
                        LogMemCorruption("UDS request list: req %p primary %p is garbage (%d)", req, p, p->sd);

                reply_state *rep;
                for (rep = req->replies; rep; rep=rep->next)
                  if (rep->next == (reply_state *)~0)
                        LogMemCorruption("UDS req->replies: %p is garbage", rep);

                if (req->terminate == connection_termination)
                        {
                        registered_record_entry *r;
                        for (r = req->u.reg_recs; r; r=r->next)
                                if (r->next == (registered_record_entry *)~0)
                                        LogMemCorruption("UDS req->u.reg_recs: %p is garbage", r);
                        }
                else if (req->terminate == regservice_termination_callback)
                        {
                        service_instance *s;
                        for (s = req->u.servicereg.instances; s; s=s->next)
                                if (s->next == (service_instance *)~0)
                                        LogMemCorruption("UDS req->u.servicereg.instances: %p is garbage", s);
                        }
                else if (req->terminate == browse_termination_callback)
                        {
                        browser_t *b;
                        for (b = req->u.browser.browsers; b; b=b->next)
                                if (b->next == (browser_t *)~0)
                                        LogMemCorruption("UDS req->u.browser.browsers: %p is garbage", b);
                        }
                }

        DNameListElem *d;
        for (d = SCPrefBrowseDomains; d; d=d->next)
                if (d->next == (DNameListElem *)~0 || d->name.c[0] > 63)
                        LogMemCorruption("SCPrefBrowseDomains: %p is garbage (%d)", d, d->name.c[0]);

        ARListElem *b;
        for (b = LocalDomainEnumRecords; b; b=b->next)
                if (b->next == (ARListElem *)~0 || b->ar.resrec.name->c[0] > 63)
                        LogMemCorruption("LocalDomainEnumRecords: %p is garbage (%d)", b, b->ar.resrec.name->c[0]);

        for (d = AutoBrowseDomains; d; d=d->next)
                if (d->next == (DNameListElem *)~0 || d->name.c[0] > 63)
                        LogMemCorruption("AutoBrowseDomains: %p is garbage (%d)", d, d->name.c[0]);

        for (d = AutoRegistrationDomains; d; d=d->next)
                if (d->next == (DNameListElem *)~0 || d->name.c[0] > 63)
                        LogMemCorruption("AutoRegistrationDomains: %p is garbage (%d)", d, d->name.c[0]);
        }
#endif // APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING

mDNSlocal int send_msg(request_state *const req)
        {
        reply_state *const rep = req->replies;          // Send the first waiting reply
        ssize_t nwriten;
        if (req->no_reply) return(t_complete);

        ConvertHeaderBytes(rep->mhdr);
        nwriten = send(req->sd, (char *)&rep->mhdr + rep->nwriten, rep->totallen - rep->nwriten, 0);
        ConvertHeaderBytes(rep->mhdr);

        if (nwriten < 0)
                {
                if (dnssd_errno == dnssd_EINTR || dnssd_errno == dnssd_EWOULDBLOCK) nwriten = 0;
                else
                        {
#if !defined(PLATFORM_NO_EPIPE)
                        if (dnssd_errno == EPIPE)
                                return(req->ts = t_terminated);
                        else
#endif
                                {
                                LogMsg("send_msg ERROR: failed to write %d of %d bytes to fd %d errno %d (%s)",
                                        rep->totallen - rep->nwriten, rep->totallen, req->sd, dnssd_errno, dnssd_strerror(dnssd_errno));
                                return(t_error);
                                }
                        }
                }
        rep->nwriten += nwriten;
        return (rep->nwriten == rep->totallen) ? t_complete : t_morecoming;
        }

mDNSexport mDNSs32 udsserver_idle(mDNSs32 nextevent)
        {
        mDNSs32 now = mDNS_TimeNow(&mDNSStorage);
        request_state **req = &all_requests;

        while (*req)
                {
                request_state *const r = *req;

                if (r->terminate == resolve_termination_callback)
                        if (r->u.resolve.ReportTime && now - r->u.resolve.ReportTime >= 0)
                                {
                                r->u.resolve.ReportTime = 0;
                                LogMsgNoIdent("Client application bug: DNSServiceResolve(%##s) active for over two minutes. "
                                        "This places considerable burden on the network.", r->u.resolve.qsrv.qname.c);
                                }

                // Note: Only primary req's have reply lists, not subordinate req's.
                while (r->replies)              // Send queued replies
                        {
                        transfer_state result;
                        if (r->replies->next) r->replies->rhdr->flags |= dnssd_htonl(kDNSServiceFlagsMoreComing);
                        result = send_msg(r);   // Returns t_morecoming if buffer full because client is not reading
                        if (result == t_complete)
                                {
                                reply_state *fptr = r->replies;
                                r->replies = r->replies->next;
                                freeL("reply_state/udsserver_idle", fptr);
                                r->time_blocked = 0; // reset failure counter after successful send
                                r->unresponsiveness_reports = 0;
                                continue;
                                }
                        else if (result == t_terminated || result == t_error)
                                {
                                LogMsg("%3d: Could not write data to client because of error - aborting connection", r->sd);
                                LogClientInfo(&mDNSStorage, r);
                                abort_request(r);
                                }
                        break;
                        }

                if (r->replies)         // If we failed to send everything, check our time_blocked timer
                        {
                        if (nextevent - now > mDNSPlatformOneSecond) nextevent = now + mDNSPlatformOneSecond;

                        if (mDNSStorage.SleepState != SleepState_Awake) r->time_blocked = 0;
                        else if (!r->time_blocked) r->time_blocked = NonZeroTime(now);
                        else if (now - r->time_blocked >= 10 * mDNSPlatformOneSecond * (r->unresponsiveness_reports+1))
                                {
                                int num = 0;
                                struct reply_state *x = r->replies;
                                while (x) { num++; x=x->next; }
                                LogMsg("%3d: Could not write data to client after %ld seconds, %d repl%s waiting",
                                        r->sd, (now - r->time_blocked) / mDNSPlatformOneSecond, num, num == 1 ? "y" : "ies");
                                if (++r->unresponsiveness_reports >= 60)
                                        {
                                        LogMsg("%3d: Client unresponsive; aborting connection", r->sd);
                                        LogClientInfo(&mDNSStorage, r);
                                        abort_request(r);
                                        }
                                }
                        }

                if (!dnssd_SocketValid(r->sd)) // If this request is finished, unlink it from the list and free the memory
                        {
                        // Since we're already doing a list traversal, we unlink the request directly instead of using AbortUnlinkAndFree()
                        *req = r->next;
                        freeL("request_state/udsserver_idle", r);
                        }
                else
                        req = &r->next;
                }
        return nextevent;
        }

struct CompileTimeAssertionChecks_uds_daemon
        {
        // Check our structures are reasonable sizes. Including overly-large buffers, or embedding
        // other overly-large structures instead of having a pointer to them, can inadvertently
        // cause structure sizes (and therefore memory usage) to balloon unreasonably.
        char sizecheck_request_state          [(sizeof(request_state)           <= 2000) ? 1 : -1];
        char sizecheck_registered_record_entry[(sizeof(registered_record_entry) <=   60) ? 1 : -1];
        char sizecheck_service_instance       [(sizeof(service_instance)        <= 6552) ? 1 : -1];
        char sizecheck_browser_t              [(sizeof(browser_t)               <= 1050) ? 1 : -1];
        char sizecheck_reply_hdr              [(sizeof(reply_hdr)               <=   12) ? 1 : -1];
        char sizecheck_reply_state            [(sizeof(reply_state)             <=   64) ? 1 : -1];
        };