mDNSResponder-320.5.tar.gz

[apple/mdnsresponder.git] / mDNSMacOSX / daemon.c

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2002-2006 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.
 *
 * Formatting notes:
 * This code follows the "Whitesmiths style" C indentation rules. Plenty of discussion
 * on C indentation can be found on the web, such as <http://www.kafejo.com/komp/1tbs.htm>,
 * but for the sake of brevity here I will say just this: Curly braces are not syntactially
 * part of an "if" statement; they are the beginning and ending markers of a compound statement;
 * therefore common sense dictates that if they are part of a compound statement then they
 * should be indented to the same level as everything else in that compound statement.
 * Indenting curly braces at the same level as the "if" implies that curly braces are
 * part of the "if", which is false. (This is as misleading as people who write "char* x,y;"
 * thinking that variables x and y are both of type "char*" -- and anyone who doesn't
 * understand why variable y is not of type "char*" just proves the point that poor code
 * layout leads people to unfortunate misunderstandings about how the C language really works.)
 */

// We set VERSION_MIN_REQUIRED to 10.4 to avoid "bootstrap_register is deprecated" warnings from bootstrap.h
#define MAC_OS_X_VERSION_MIN_REQUIRED MAC_OS_X_VERSION_10_4

#include <mach/mach.h>
#include <mach/mach_error.h>
#include <servers/bootstrap.h>
#include <sys/types.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <paths.h>
#include <fcntl.h>
#include <launch.h>
#include <pwd.h>
#include <sys/event.h>
#include <pthread.h>
#include <sandbox.h>
#include <SystemConfiguration/SCPreferencesSetSpecific.h>
#include <SystemConfiguration/SCDynamicStoreCopyDHCPInfo.h>

#if TARGET_OS_EMBEDDED
#include <bootstrap_priv.h>

#define bootstrap_register(A,B,C) bootstrap_register2((A),(B),(C),0)
#endif

#include "DNSServiceDiscoveryRequestServer.h"
#include "DNSServiceDiscoveryReply.h"

#include "uDNS.h"
#include "DNSCommon.h"
#include "mDNSMacOSX.h"                         // Defines the specific types needed to run mDNS on this platform

#include "uds_daemon.h"                         // Interface to the server side implementation of dns_sd.h

#include <DNSServiceDiscovery/DNSServiceDiscovery.h>
#include "helper.h"
#include "safe_vproc.h"

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

static mDNS_PlatformSupport PlatformStorage;

// Start off with a default cache of 16K (99 records)
// Each time we grow the cache we add another 99 records
// 99 * 164 = 16236 bytes.
// This fits in four 4kB pages, with 148 bytes spare for memory block headers and similar overhead
#define RR_CACHE_SIZE ((16*1024) / sizeof(CacheRecord))
static CacheEntity rrcachestorage[RR_CACHE_SIZE];

static const char kmDNSBootstrapName[] = "com.apple.mDNSResponderRestart";
static mach_port_t m_port            = MACH_PORT_NULL;

#ifdef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
mDNSlocal void PrepareForIdle(void *m_param);
#else // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
static mach_port_t client_death_port = MACH_PORT_NULL;
static mach_port_t signal_port       = MACH_PORT_NULL;
#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

static mach_port_t server_priv_port  = MACH_PORT_NULL;

static dnssd_sock_t *launchd_fds = mDNSNULL;
static mDNSu32 launchd_fds_count = 0;

// mDNS Mach Message Timeout, in milliseconds.
// We need this to be short enough that we don't deadlock the mDNSResponder if a client
// fails to service its mach message queue, but long enough to give a well-written
// client a chance to service its mach message queue without getting cut off.
// Empirically, 50ms seems to work, so we set the timeout to 250ms to give
// even extra-slow clients a fair chance before we cut them off.
#define MDNS_MM_TIMEOUT 250

static int restarting_via_mach_init = 0;        // Used on Jaguar/Panther when daemon is started via mach_init mechanism
static int started_via_launchdaemon = 0;        // Indicates we're running on Tiger or later, where daemon is managed by launchd
static mDNSBool advertise = mDNS_Init_AdvertiseLocalAddresses; // By default, advertise addresses (& other records) via multicast

extern mDNSBool StrictUnicastOrdering;
extern mDNSBool AlwaysAppendSearchDomains;

//*************************************************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Active client list structures
#endif

typedef struct DNSServiceDomainEnumeration_struct DNSServiceDomainEnumeration;
struct DNSServiceDomainEnumeration_struct
        {
        DNSServiceDomainEnumeration *next;
        mach_port_t ClientMachPort;
        DNSQuestion dom;        // Question asking for domains
        DNSQuestion def;        // Question asking for default domain
        };

typedef struct DNSServiceBrowserResult_struct DNSServiceBrowserResult;
struct DNSServiceBrowserResult_struct
        {
        DNSServiceBrowserResult *next;
        int resultType;
        domainname result;
        };

typedef struct DNSServiceBrowser_struct DNSServiceBrowser;

typedef struct DNSServiceBrowserQuestion
        {
        struct DNSServiceBrowserQuestion *next;
        DNSQuestion q;
    domainname domain;
        } DNSServiceBrowserQuestion;

struct DNSServiceBrowser_struct
        {
        DNSServiceBrowser *next;
        mach_port_t ClientMachPort;
        DNSServiceBrowserQuestion *qlist;
        DNSServiceBrowserResult *results;
        mDNSs32 lastsuccess;
    mDNSBool DefaultDomain;                // was the browse started on an explicit domain?
    domainname type;                       // registration type
        };

typedef struct DNSServiceResolver_struct DNSServiceResolver;
struct DNSServiceResolver_struct
        {
        DNSServiceResolver *next;
        mach_port_t ClientMachPort;
        ServiceInfoQuery q;
        ServiceInfo      i;
        mDNSs32          ReportTime;
        };

// A single registered service: ServiceRecordSet + bookkeeping
// Note that we duplicate some fields from parent DNSServiceRegistration object
// to facilitate cleanup, when instances and parent may be deallocated at different times.
typedef struct ServiceInstance
        {
    struct ServiceInstance *next;
        mach_port_t ClientMachPort;
    mDNSBool autoname;                  // Set if this name is tied to the Computer Name
    mDNSBool renameonmemfree;   // Set if we just got a name conflict and now need to automatically pick a new name
    domainlabel name;
    domainname domain;
    ServiceRecordSet srs;
        // Don't add any fields after ServiceRecordSet.
        // This is where the implicit extra space goes if we allocate an oversized ServiceRecordSet object
        } ServiceInstance;

// A client-created service.  May reference several ServiceInstance objects if default
// settings cause registration in multiple domains.
typedef struct DNSServiceRegistration
        {
    struct DNSServiceRegistration *next;
        mach_port_t ClientMachPort;
    mDNSBool DefaultDomain;
    mDNSBool autoname;
    size_t rdsize;
    int NumSubTypes;
    char regtype[MAX_ESCAPED_DOMAIN_NAME]; // for use in AllocateSubtypes
    domainlabel name;  // used only if autoname is false
    domainname type;
    mDNSIPPort port;
    unsigned char txtinfo[1024];
    size_t txt_len;
    uint32_t NextRef;
    ServiceInstance *regs;
        } DNSServiceRegistration;

static DNSServiceDomainEnumeration *DNSServiceDomainEnumerationList = NULL;
static DNSServiceBrowser           *DNSServiceBrowserList           = NULL;
static DNSServiceResolver          *DNSServiceResolverList          = NULL;
static DNSServiceRegistration      *DNSServiceRegistrationList      = NULL;

// We keep a list of client-supplied event sources in KQSocketEventSource records
typedef struct KQSocketEventSource
        {
        struct  KQSocketEventSource *next;
        int                         fd;
        KQueueEntry                 kqs;
        } KQSocketEventSource;

static KQSocketEventSource *gEventSources;

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

#if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING

char _malloc_options[] = "AXZ";

mDNSexport void LogMemCorruption(const char *format, ...)
        {
        char buffer[512];
        va_list ptr;
        va_start(ptr,format);
        buffer[mDNS_vsnprintf((char *)buffer, sizeof(buffer), format, ptr)] = 0;
        va_end(ptr);
        LogMsg("!!!! %s !!!!", buffer);
        NotifyOfElusiveBug("Memory Corruption", buffer);
#if ForceAlerts
        *(long*)0 = 0;  // Trick to crash and get a stack trace right here, if that's what we want
#endif
        }

mDNSlocal void validatelists(mDNS *const m)
        {
        // Check local lists
        KQSocketEventSource *k;
        for (k = gEventSources; k; k=k->next)
                if (k->next == (KQSocketEventSource *)~0 || k->fd < 0)
                        LogMemCorruption("gEventSources: %p is garbage (%d)", k, k->fd);

        // Check Mach client lists
        DNSServiceDomainEnumeration *e;
        for (e = DNSServiceDomainEnumerationList; e; e=e->next)
                if (e->next == (DNSServiceDomainEnumeration *)~0 || e->ClientMachPort == 0 || e->ClientMachPort == (mach_port_t)~0)
                        LogMemCorruption("DNSServiceDomainEnumerationList: %p is garbage (%X)", e, e->ClientMachPort);

        DNSServiceBrowser           *b;
        for (b = DNSServiceBrowserList; b; b=b->next)
                if (b->next == (DNSServiceBrowser *)~0 || b->ClientMachPort == 0 || b->ClientMachPort == (mach_port_t)~0)
                        LogMemCorruption("DNSServiceBrowserList: %p is garbage (%X)", b, b->ClientMachPort);

        DNSServiceResolver          *l;
        for (l = DNSServiceResolverList; l; l=l->next)
                if (l->next == (DNSServiceResolver *)~0 || l->ClientMachPort == 0 || l->ClientMachPort == (mach_port_t)~0)
                        LogMemCorruption("DNSServiceResolverList: %p is garbage (%X)", l, l->ClientMachPort);

        DNSServiceRegistration      *r;
        for (r = DNSServiceRegistrationList; r; r=r->next)
                if (r->next == (DNSServiceRegistration *)~0 || r->ClientMachPort == 0 || r->ClientMachPort == (mach_port_t)~0)
                        LogMemCorruption("DNSServiceRegistrationList: %p is garbage (%X)", r, r->ClientMachPort);

        // Check Unix Domain Socket client lists (uds_daemon.c)
        uds_validatelists();

        // Check core mDNS lists
        AuthRecord                  *rr;
        for (rr = m->ResourceRecords; rr; rr=rr->next)
                {
                if (rr->next == (AuthRecord *)~0 || rr->resrec.RecordType == 0 || rr->resrec.RecordType == 0xFF)
                        LogMemCorruption("ResourceRecords list: %p is garbage (%X)", rr, rr->resrec.RecordType);
                if (rr->resrec.name != &rr->namestorage)
                        LogMemCorruption("ResourceRecords list: %p name %p does not point to namestorage %p %##s",
                                rr, rr->resrec.name->c, rr->namestorage.c, rr->namestorage.c);
                }

        for (rr = m->DuplicateRecords; rr; rr=rr->next)
                if (rr->next == (AuthRecord *)~0 || rr->resrec.RecordType == 0 || rr->resrec.RecordType == 0xFF)
                        LogMemCorruption("DuplicateRecords list: %p is garbage (%X)", rr, rr->resrec.RecordType);

        rr = m->NewLocalRecords;
        if (rr)
                if (rr->next == (AuthRecord *)~0 || rr->resrec.RecordType == 0 || rr->resrec.RecordType == 0xFF)
                        LogMemCorruption("NewLocalRecords: %p is garbage (%X)", rr, rr->resrec.RecordType);

        rr = m->CurrentRecord;
        if (rr)
                if (rr->next == (AuthRecord *)~0 || rr->resrec.RecordType == 0 || rr->resrec.RecordType == 0xFF)
                        LogMemCorruption("CurrentRecord: %p is garbage (%X)", rr, rr->resrec.RecordType);

        DNSQuestion                 *q;
        for (q = m->Questions; q; q=q->next)
                if (q->next == (DNSQuestion*)~0 || q->ThisQInterval == (mDNSs32)~0)
                        LogMemCorruption("Questions list: %p is garbage (%lX %p)", q, q->ThisQInterval, q->next);

        CacheGroup                  *cg;
        CacheRecord                 *cr;
        mDNSu32 slot;
        FORALL_CACHERECORDS(slot, cg, cr)
                {
                if (cr->resrec.RecordType == 0 || cr->resrec.RecordType == 0xFF)
                        LogMemCorruption("Cache slot %lu: %p is garbage (%X)", slot, cr, cr->resrec.RecordType);
                if (cr->CRActiveQuestion)
                        {
                        for (q = m->Questions; q; q=q->next) if (q == cr->CRActiveQuestion) break;
                        if (!q) LogMemCorruption("Cache slot %lu: CRActiveQuestion %p not in m->Questions list %s", slot, cr->CRActiveQuestion, CRDisplayString(m, cr));
                        }
                }

        // Check core uDNS lists
        udns_validatelists(m);

        // Check platform-layer lists
        NetworkInterfaceInfoOSX     *i;
        for (i = m->p->InterfaceList; i; i = i->next)
                if (i->next == (NetworkInterfaceInfoOSX *)~0 || !i->m || i->m == (mDNS *)~0)
                        LogMemCorruption("m->p->InterfaceList: %p is garbage (%p)", i, i->ifinfo.ifname);

        ClientTunnel *t;
        for (t = m->TunnelClients; t; t=t->next)
                if (t->next == (ClientTunnel *)~0 || t->dstname.c[0] > 63)
                        LogMemCorruption("m->TunnelClients: %p is garbage (%d)", t, t->dstname.c[0]);
        }

mDNSexport void *mallocL(char *msg, unsigned int size)
        {
        // Allocate space for two words of sanity checking data before the requested block
        mDNSu32 *mem = malloc(sizeof(mDNSu32) * 2 + size);
        if (!mem)
                { LogMsg("malloc( %s : %d ) failed", msg, size); return(NULL); }
        else
                {
                if      (size > 24000)                      LogMsg("malloc( %s : %lu ) = %p suspiciously large", msg, size, &mem[2]);
                else if (MACOSX_MDNS_MALLOC_DEBUGGING >= 2) LogMsg("malloc( %s : %lu ) = %p",                    msg, size, &mem[2]);
                mem[0] = 0xDEAD1234;
                mem[1] = size;
                //mDNSPlatformMemZero(&mem[2], size);
                memset(&mem[2], 0xFF, size);
                validatelists(&mDNSStorage);
                return(&mem[2]);
                }
        }

mDNSexport void freeL(char *msg, void *x)
        {
        if (!x)
                LogMsg("free( %s @ NULL )!", msg);
        else
                {
                mDNSu32 *mem = ((mDNSu32 *)x) - 2;
                if      (mem[0] != 0xDEAD1234)            { LogMsg("free( %s @ %p ) !!!! NOT ALLOCATED !!!!", msg, &mem[2]); return; }
                if      (mem[1] > 24000)                    LogMsg("free( %s : %ld @ %p) suspiciously large", msg, mem[1], &mem[2]);
                else if (MACOSX_MDNS_MALLOC_DEBUGGING >= 2) LogMsg("free( %s : %ld @ %p)",                    msg, mem[1], &mem[2]);
                //mDNSPlatformMemZero(mem, sizeof(mDNSu32) * 2 + mem[1]);
                memset(mem, 0xFF, sizeof(mDNSu32) * 2 + mem[1]);
                validatelists(&mDNSStorage);
                free(mem);
                }
        }

#endif

//*************************************************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Mach client request handlers
#endif

//*************************************************************************************************************
// Client Death Detection

// This gets called after ALL constituent records of the Service Record Set have been deregistered
mDNSlocal void FreeServiceInstance(ServiceInstance *x)
        {
        ServiceRecordSet *s = &x->srs;
        ExtraResourceRecord *e = x->srs.Extras, *tmp;
        
        while (e)
                {
                e->r.RecordContext = e;
                tmp = e;
                e = e->next;
                FreeExtraRR(&mDNSStorage, &tmp->r, mStatus_MemFree);
                }
        
        if (s->RR_TXT.resrec.rdata != &s->RR_TXT.rdatastorage)
                freeL("TXT RData", s->RR_TXT.resrec.rdata);

        if (s->SubTypes) freeL("ServiceSubTypes", s->SubTypes);
        freeL("ServiceInstance", x);
        }

// AbortClient finds whatever client is identified by the given Mach port,
// stops whatever operation that client was doing, and frees its memory.
// In the case of a service registration, the actual freeing may be deferred
// until we get the mStatus_MemFree message, if necessary
mDNSlocal void AbortClient(mach_port_t ClientMachPort, void *m)
        {
        DNSServiceDomainEnumeration **e = &DNSServiceDomainEnumerationList;
        DNSServiceBrowser           **b = &DNSServiceBrowserList;
        DNSServiceResolver          **l = &DNSServiceResolverList;
        DNSServiceRegistration      **r = &DNSServiceRegistrationList;

        while (*e && (*e)->ClientMachPort != ClientMachPort) e = &(*e)->next;
        if (*e)
                {
                DNSServiceDomainEnumeration *x = *e;
                *e = (*e)->next;
                if (m && m != x)
                        LogMsg("%5d: DNSServiceDomainEnumeration(%##s) STOP; WARNING m %p != x %p", ClientMachPort, x->dom.qname.c, m, x);
                else LogOperation("%5d: DNSServiceDomainEnumeration(%##s) STOP", ClientMachPort, x->dom.qname.c);
                mDNS_StopGetDomains(&mDNSStorage, &x->dom);
                mDNS_StopGetDomains(&mDNSStorage, &x->def);
                freeL("DNSServiceDomainEnumeration", x);
                return;
                }

        while (*b && (*b)->ClientMachPort != ClientMachPort) b = &(*b)->next;
        if (*b)
                {
                DNSServiceBrowser *x = *b;
                DNSServiceBrowserQuestion *freePtr, *qptr = x->qlist;
                *b = (*b)->next;
                while (qptr)
                        {
                        if (m && m != x)
                                LogMsg("%5d: DNSServiceBrowse(%##s) STOP; WARNING m %p != x %p", ClientMachPort, qptr->q.qname.c, m, x);
                        else LogOperation("%5d: DNSServiceBrowse(%##s) STOP", ClientMachPort, qptr->q.qname.c);
                        mDNS_StopBrowse(&mDNSStorage, &qptr->q);
                        freePtr = qptr;
                        qptr = qptr->next;
                        freeL("DNSServiceBrowserQuestion", freePtr);
                        }
                while (x->results)
                        {
                        DNSServiceBrowserResult *t = x->results;
                        x->results = x->results->next;
                        freeL("DNSServiceBrowserResult", t);
                        }
                freeL("DNSServiceBrowser", x);
                return;
                }

        while (*l && (*l)->ClientMachPort != ClientMachPort) l = &(*l)->next;
        if (*l)
                {
                DNSServiceResolver *x = *l;
                *l = (*l)->next;
                if (m && m != x)
                        LogMsg("%5d: DNSServiceResolve(%##s) STOP; WARNING m %p != x %p", ClientMachPort, x->i.name.c, m, x);
                else LogOperation("%5d: DNSServiceResolve(%##s) STOP", ClientMachPort, x->i.name.c);
                mDNS_StopResolveService(&mDNSStorage, &x->q);
                freeL("DNSServiceResolver", x);
                return;
                }

        while (*r && (*r)->ClientMachPort != ClientMachPort) r = &(*r)->next;
        if (*r)
                {
                ServiceInstance *si = NULL;
                DNSServiceRegistration *x = *r;
                *r = (*r)->next;

                si = x->regs;
                while (si)
                        {
                        ServiceInstance *instance = si;
                        si = si->next;
                        instance->renameonmemfree = mDNSfalse;
                        if (m && m != x) LogMsg("%5d: DNSServiceRegistration(%##s, %u) STOP; WARNING m %p != x %p", ClientMachPort, instance->srs.RR_SRV.resrec.name->c, SRS_PORT(&instance->srs), m, x);
                        else LogOperation("%5d: DNSServiceRegistration(%##s, %u) STOP", ClientMachPort, instance->srs.RR_SRV.resrec.name->c, SRS_PORT(&instance->srs));

                        // If mDNS_DeregisterService() returns mStatus_NoError, that means that the service was found in the list,
                        // is sending its goodbye packet, and we'll get an mStatus_MemFree message when we can free the memory.
                        // If mDNS_DeregisterService() returns an error, it means that the service had already been removed from
                        // the list, so we should go ahead and free the memory right now
                        if (mDNS_DeregisterService(&mDNSStorage, &instance->srs)) FreeServiceInstance(instance); // FreeServiceInstance invalidates pointer
                        }
                x->regs = NULL;
                freeL("DNSServiceRegistration", x);
                return;
                }

        LogMsg("%5d: died or deallocated, but no record of client can be found!", ClientMachPort);
        }

#define AbortBlockedClient(C,MSG,M) AbortClientWithLogMessage((C), "stopped accepting Mach messages", " (" MSG ")", (M))

mDNSlocal void AbortClientWithLogMessage(mach_port_t c, char *reason, char *msg, void *m)
        {
        DNSServiceDomainEnumeration *e = DNSServiceDomainEnumerationList;
        DNSServiceBrowser           *b = DNSServiceBrowserList;
        DNSServiceResolver          *l = DNSServiceResolverList;
        DNSServiceRegistration      *r = DNSServiceRegistrationList;
        DNSServiceBrowserQuestion   *qptr;

        while (e && e->ClientMachPort != c) e = e->next;
        while (b && b->ClientMachPort != c) b = b->next;
        while (l && l->ClientMachPort != c) l = l->next;
        while (r && r->ClientMachPort != c) r = r->next;

        if      (e) LogMsg("%5d: DomainEnumeration(%##s) %s%s",                   c, e->dom.qname.c,                reason, msg);
        else if (b)
                        {
                        for (qptr = b->qlist; qptr; qptr = qptr->next)
                                LogMsg("%5d: Browser(%##s) %s%s",                             c, qptr->q.qname.c,               reason, msg);
                        }
        else if (l) LogMsg("%5d: Resolver(%##s) %s%s",                            c, l->i.name.c,                   reason, msg);
        else if (r)
                        {
                        ServiceInstance *si;
                        for (si = r->regs; si; si = si->next)
                                LogMsg("%5d: Registration(%##s) %s%s",                        c, si->srs.RR_SRV.resrec.name->c, reason, msg);
                        }
        else        LogMsg("%5d: (%s) %s, but no record of client can be found!", c,                                reason, msg);

        AbortClient(c, m);
        }

mDNSlocal mDNSBool CheckForExistingClient(mach_port_t c)
        {
        DNSServiceDomainEnumeration *e = DNSServiceDomainEnumerationList;
        DNSServiceBrowser           *b = DNSServiceBrowserList;
        DNSServiceResolver          *l = DNSServiceResolverList;
        DNSServiceRegistration      *r = DNSServiceRegistrationList;
        DNSServiceBrowserQuestion   *qptr;

        while (e && e->ClientMachPort != c) e = e->next;
        while (b && b->ClientMachPort != c) b = b->next;
        while (l && l->ClientMachPort != c) l = l->next;
        while (r && r->ClientMachPort != c) r = r->next;
        if (e) LogMsg("%5d: DomainEnumeration(%##s) already exists!", c, e->dom.qname.c);
        if (b)
                {
                for (qptr = b->qlist; qptr; qptr = qptr->next)
                        LogMsg("%5d: Browser(%##s) already exists!",          c, qptr->q.qname.c);
                }
        if (l) LogMsg("%5d: Resolver(%##s) already exists!",          c, l->i.name.c);
        if (r) LogMsg("%5d: Registration(%##s) already exists!",      c, r->regs ? r->regs->srs.RR_SRV.resrec.name->c : NULL);
        return(e || b || l || r);
        }

#ifndef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSlocal void ClientDeathCallback(CFMachPortRef unusedport, void *voidmsg, CFIndex size, void *info)
        {
        KQueueLock(&mDNSStorage);
        mach_msg_header_t *msg = (mach_msg_header_t *)voidmsg;
        (void)unusedport; // Unused
        (void)size; // Unused
        (void)info; // Unused
        if (msg->msgh_id == MACH_NOTIFY_DEAD_NAME)
                {
                const mach_dead_name_notification_t *const deathMessage = (mach_dead_name_notification_t *)msg;
                AbortClient(deathMessage->not_port, NULL);

                /* Deallocate the send right that came in the dead name notification */
                mach_port_destroy(mach_task_self(), deathMessage->not_port);
                }
        KQueueUnlock(&mDNSStorage, "Mach AbortClient");
        }

#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSlocal void EnableDeathNotificationForClient(mach_port_t ClientMachPort, void *m)
        {
#ifdef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
        dispatch_source_t mach_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_MACH_SEND, ClientMachPort, 0, dispatch_get_main_queue());
        if (mach_source == mDNSNULL)
                {
                AbortClientWithLogMessage(ClientMachPort, "died/deallocated before we could enable death notification", "", m);
                return;
                }
        dispatch_source_set_event_handler(mach_source, ^{
                mach_port_destroy(mach_task_self(), ClientMachPort);
                });
        dispatch_resume(mach_source);
#else // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
        mach_port_t prev;
        kern_return_t r = mach_port_request_notification(mach_task_self(), ClientMachPort, MACH_NOTIFY_DEAD_NAME, 0,
                                                                                                         client_death_port, MACH_MSG_TYPE_MAKE_SEND_ONCE, &prev);
        // If the port already died while we were thinking about it, then abort the operation right away
        if (r != KERN_SUCCESS)
                AbortClientWithLogMessage(ClientMachPort, "died/deallocated before we could enable death notification", "", m);
#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
        }

//*************************************************************************************************************
// Domain Enumeration

mDNSlocal void DomainEnumFound(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
        {
        kern_return_t status;
        char buffer[MAX_ESCAPED_DOMAIN_NAME];
        DNSServiceDomainEnumerationReplyResultType rt;
        DNSServiceDomainEnumeration *x = (DNSServiceDomainEnumeration *)question->QuestionContext;
        (void)m; // Unused

        debugf("DomainEnumFound: %##s PTR %##s", answer->name->c, answer->rdata->u.name.c);
        if (answer->rrtype != kDNSType_PTR) return;
        if (!x) { debugf("DomainEnumFound: DNSServiceDomainEnumeration is NULL"); return; }

        if (AddRecord)
                {
                if (question == &x->dom) rt = DNSServiceDomainEnumerationReplyAddDomain;
                else                     rt = DNSServiceDomainEnumerationReplyAddDomainDefault;
                }
        else
                {
                if (question == &x->dom) rt = DNSServiceDomainEnumerationReplyRemoveDomain;
                else return;
                }

        LogOperation("%5d: DNSServiceDomainEnumeration(%##s) %##s %s",
                x->ClientMachPort, x->dom.qname.c, answer->rdata->u.name.c,
                !AddRecord ? "RemoveDomain" :
                question == &x->dom ? "AddDomain" : "AddDomainDefault");

        ConvertDomainNameToCString(&answer->rdata->u.name, buffer);
        status = DNSServiceDomainEnumerationReply_rpc(x->ClientMachPort, rt, buffer, 0, MDNS_MM_TIMEOUT);
        if (status == MACH_SEND_TIMED_OUT)
                AbortBlockedClient(x->ClientMachPort, "enumeration", x);
        }

mDNSexport kern_return_t provide_DNSServiceDomainEnumerationCreate_rpc(mach_port_t unusedserver, mach_port_t client,
        int regDom)
        {
        // Check client parameter
        (void)unusedserver; // Unused
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";
        if (client == (mach_port_t)-1)      { err = mStatus_Invalid; errormsg = "Client id -1 invalid";     goto fail; }
        if (CheckForExistingClient(client)) { err = mStatus_Invalid; errormsg = "Client id already in use"; goto fail; }

        mDNS_DomainType dt1 = regDom ? mDNS_DomainTypeRegistration        : mDNS_DomainTypeBrowse;
        mDNS_DomainType dt2 = regDom ? mDNS_DomainTypeRegistrationDefault : mDNS_DomainTypeBrowseDefault;

        // Allocate memory, and handle failure
        DNSServiceDomainEnumeration *x = mallocL("DNSServiceDomainEnumeration", sizeof(*x));
        if (!x) { err = mStatus_NoMemoryErr; errormsg = "No memory"; goto fail; }

        // Set up object, and link into list
        x->ClientMachPort = client;
        x->next = DNSServiceDomainEnumerationList;
        DNSServiceDomainEnumerationList = x;

        verbosedebugf("%5d: Enumerate %s Domains", client, regDom ? "Registration" : "Browsing");

        // Do the operation
        err           = mDNS_GetDomains(&mDNSStorage, &x->dom, dt1, NULL, mDNSInterface_LocalOnly, DomainEnumFound, x);
        if (!err) err = mDNS_GetDomains(&mDNSStorage, &x->def, dt2, NULL, mDNSInterface_LocalOnly, DomainEnumFound, x);
        if (err) { AbortClient(client, x); errormsg = "mDNS_GetDomains"; goto fail; }

        // Succeeded: Wrap up and return
        LogOperation("%5d: DNSServiceDomainEnumeration(%##s) START", client, x->dom.qname.c);
        EnableDeathNotificationForClient(client, x);
        return(mStatus_NoError);

fail:
        LogMsg("%5d: DNSServiceDomainEnumeration(%d) failed: %s (%d)", client, regDom, errormsg, err);
        return(err);
        }

//*************************************************************************************************************
// Browse for services

mDNSlocal void FoundInstance(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
        {
        (void)m;                // Unused

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

        domainlabel name;
        domainname type, domain;
        if (!DeconstructServiceName(&answer->rdata->u.name, &name, &type, &domain))
                {
                LogMsg("FoundInstance: %##s PTR %##s received from network is not valid DNS-SD service pointer",
                        answer->name->c, answer->rdata->u.name.c);
                return;
                }

        DNSServiceBrowserResult *x = mallocL("DNSServiceBrowserResult", sizeof(*x));
        if (!x) { LogMsg("FoundInstance: Failed to allocate memory for result %##s", answer->rdata->u.name.c); return; }

        verbosedebugf("FoundInstance: %s %##s", AddRecord ? "Add" : "Rmv", answer->rdata->u.name.c);
        AssignDomainName(&x->result, &answer->rdata->u.name);
        if (AddRecord)
                 x->resultType = DNSServiceBrowserReplyAddInstance;
        else x->resultType = DNSServiceBrowserReplyRemoveInstance;
        x->next = NULL;

        DNSServiceBrowser *browser = (DNSServiceBrowser *)question->QuestionContext;
        DNSServiceBrowserResult **p = &browser->results;
        while (*p) p = &(*p)->next;
        *p = x;

        LogOperation("%5d: DNSServiceBrowse(%##s, %s) RESULT %s %s",
                browser->ClientMachPort, question->qname.c, DNSTypeName(question->qtype), AddRecord ? "Add" : "Rmv", RRDisplayString(m, answer));
        }

mDNSlocal mStatus AddDomainToBrowser(DNSServiceBrowser *browser, const domainname *d)
        {
        mStatus err = mStatus_NoError;
        DNSServiceBrowserQuestion *ptr, *question = NULL;

        for (ptr = browser->qlist; ptr; ptr = ptr->next)
                {
                if (SameDomainName(&ptr->q.qname, d))
                        { debugf("Domain %##s already contained in browser", d->c); return mStatus_AlreadyRegistered; }
                }
        
        question = mallocL("DNSServiceBrowserQuestion", sizeof(DNSServiceBrowserQuestion));
        if (!question) { LogMsg("Error: malloc"); return mStatus_NoMemoryErr; }
        AssignDomainName(&question->domain, d);
        question->next = browser->qlist;
        LogOperation("%5d: DNSServiceBrowse(%##s%##s) START", browser->ClientMachPort, browser->type.c, d->c);
        err = mDNS_StartBrowse(&mDNSStorage, &question->q, &browser->type, d, mDNSInterface_Any, mDNSfalse, FoundInstance, browser);
        if (!err)
                browser->qlist = question;
        else
                {
                LogMsg("Error: AddDomainToBrowser: mDNS_StartBrowse %d", err);
                freeL("DNSServiceBrowserQuestion", question);
                }
        return err;
        }

mDNSexport void machserver_automatic_browse_domain_changed(const domainname *d, mDNSBool add)
        {
        DNSServiceBrowser *ptr;
        for (ptr = DNSServiceBrowserList; ptr; ptr = ptr->next)
                {
                if (ptr->DefaultDomain)
                        {
                        if (add)
                                {
                                mStatus err = AddDomainToBrowser(ptr, d);
                                if (err && err != mStatus_AlreadyRegistered) LogMsg("Default browse in domain %##s for client %5d failed. Continuing", d, ptr->ClientMachPort);
                                }
                        else
                                {
                                DNSServiceBrowserQuestion **q = &ptr->qlist;
                                while (*q)
                                        {
                                        if (SameDomainName(&(*q)->domain, d))
                                                {
                                                DNSServiceBrowserQuestion *rem = *q;
                                                *q = (*q)->next;
                                                mDNS_StopQueryWithRemoves(&mDNSStorage, &rem->q);
                                                freeL("DNSServiceBrowserQuestion", rem);
                                                return;
                                                }
                                        q = &(*q)->next;
                                        }
                            LogMsg("Requested removal of default domain %##s not in client %5d's list", d->c, ptr->ClientMachPort);
                                }
                        }
                }
        }

mDNSexport kern_return_t provide_DNSServiceBrowserCreate_rpc(mach_port_t unusedserver, mach_port_t client,
        DNSCString regtype, DNSCString domain)
        {
        // Check client parameter
        (void)unusedserver;             // Unused
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";

        if (client == (mach_port_t)-1)      { err = mStatus_Invalid; errormsg = "Client id -1 invalid";     goto fail; }
        if (CheckForExistingClient(client)) { err = mStatus_Invalid; errormsg = "Client id already in use"; goto fail; }

        // Check other parameters
        domainname t, d;
        t.c[0] = 0;
        mDNSs32 NumSubTypes = ChopSubTypes(regtype);    // Note: Modifies regtype string to remove trailing subtypes
        if (NumSubTypes < 0 || NumSubTypes > 1)               { errormsg = "Bad Service SubType"; goto badparam; }
        if (NumSubTypes == 1 && !AppendDNSNameString(&t, regtype + strlen(regtype) + 1))
                                                              { errormsg = "Bad Service SubType"; goto badparam; }
        if (!regtype[0] || !AppendDNSNameString(&t, regtype)) { errormsg = "Illegal regtype";     goto badparam; }
        domainname temp;
        if (!MakeDomainNameFromDNSNameString(&temp, regtype)) { errormsg = "Illegal regtype";     goto badparam; }
        if (temp.c[0] > 15 && (!domain || domain[0] == 0)) domain = "local."; // For over-long service types, we only allow domain "local"

        // Allocate memory, and handle failure
        DNSServiceBrowser *x = mallocL("DNSServiceBrowser", sizeof(*x));
        if (!x) { err = mStatus_NoMemoryErr; errormsg = "No memory"; goto fail; }

        // Set up object, and link into list
        AssignDomainName(&x->type, &t);
        x->ClientMachPort = client;
        x->results = NULL;
        x->lastsuccess = 0;
        x->qlist = NULL;
        x->next = DNSServiceBrowserList;
        DNSServiceBrowserList = x;

        if (domain[0])
                {
                // Start browser for an explicit domain
                x->DefaultDomain = mDNSfalse;
                if (!MakeDomainNameFromDNSNameString(&d, domain)) { errormsg = "Illegal domain";  goto badparam; }
                err = AddDomainToBrowser(x, &d);
                if (err) { AbortClient(client, x); errormsg = "AddDomainToBrowser"; goto fail; }
                }
        else
                {
                DNameListElem *sdPtr;
                // Start browser on all domains
                x->DefaultDomain = mDNStrue;
                if (!AutoBrowseDomains) { AbortClient(client, x); errormsg = "GetSearchDomainList"; goto fail; }
                for (sdPtr = AutoBrowseDomains; sdPtr; sdPtr = sdPtr->next)
                        {
                        err = AddDomainToBrowser(x, &sdPtr->name);
                        if (err)
                                {
                                // only terminally bail if .local fails
                                if (!SameDomainName(&localdomain, &sdPtr->name))
                                        LogMsg("Default browse in domain %##s failed. Continuing", sdPtr->name.c);
                                else { AbortClient(client, x); errormsg = "AddDomainToBrowser"; goto fail; }
                                }
                        }
                }
        
        // Succeeded: Wrap up and return
        EnableDeathNotificationForClient(client, x);
        return(mStatus_NoError);

        badparam:
        err = mStatus_BadParamErr;
fail:
        LogMsg("%5d: DNSServiceBrowse(\"%s\", \"%s\") failed: %s (%d)", client, regtype, domain, errormsg, err);
        return(err);
        }

//*************************************************************************************************************
// Resolve Service Info
        
mDNSlocal void FoundInstanceInfo(mDNS *const m, ServiceInfoQuery *query)
        {
        kern_return_t status;
        DNSServiceResolver *x = (DNSServiceResolver *)query->ServiceInfoQueryContext;
        NetworkInterfaceInfoOSX *ifx = IfindexToInterfaceInfoOSX(m, query->info->InterfaceID);
        if (query->info->InterfaceID == mDNSInterface_LocalOnly || query->info->InterfaceID == mDNSInterface_P2P) ifx = mDNSNULL;
        struct sockaddr_storage interface;
        struct sockaddr_storage address;
        char cstring[1024];
        int i, pstrlen = query->info->TXTinfo[0];
        (void)m;                // Unused

        //debugf("FoundInstanceInfo %.4a %.4a %##s", &query->info->InterfaceAddr, &query->info->ip, &query->info->name);

        if (query->info->TXTlen > sizeof(cstring)) return;

        mDNSPlatformMemZero(&interface, sizeof(interface));
        mDNSPlatformMemZero(&address,   sizeof(address));

        if (ifx && ifx->ifinfo.ip.type == mDNSAddrType_IPv4)
                {
                struct sockaddr_in *s = (struct sockaddr_in*)&interface;
                s->sin_len         = sizeof(*s);
                s->sin_family      = AF_INET;
                s->sin_port        = 0;
                s->sin_addr.s_addr = ifx->ifinfo.ip.ip.v4.NotAnInteger;
                }
        else if (ifx && ifx->ifinfo.ip.type == mDNSAddrType_IPv6)
                {
                struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)&interface;
                sin6->sin6_len       = sizeof(*sin6);
                sin6->sin6_family    = AF_INET6;
                sin6->sin6_flowinfo  = 0;
                sin6->sin6_port      = 0;
                sin6->sin6_addr      = *(struct in6_addr*)&ifx->ifinfo.ip.ip.v6;
                sin6->sin6_scope_id  = ifx->scope_id;
                }

        if (query->info->ip.type == mDNSAddrType_IPv4)
                {
                struct sockaddr_in *s = (struct sockaddr_in*)&address;
                s->sin_len         = sizeof(*s);
                s->sin_family      = AF_INET;
                s->sin_port        = query->info->port.NotAnInteger;
                s->sin_addr.s_addr = query->info->ip.ip.v4.NotAnInteger;
                }
        else
                {
                struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)&address;
                sin6->sin6_len           = sizeof(*sin6);
                sin6->sin6_family        = AF_INET6;
                sin6->sin6_port          = query->info->port.NotAnInteger;
                sin6->sin6_flowinfo      = 0;
                sin6->sin6_addr          = *(struct in6_addr*)&query->info->ip.ip.v6;
                sin6->sin6_scope_id      = ifx ? ifx->scope_id : 0;
                }

        // The OS X DNSServiceResolverResolve() API is defined using a C-string,
        // but the mDNS_StartResolveService() call actually returns a packed block of P-strings.
        // Hence we have to convert the P-string(s) to a C-string before returning the result to the client.
        // ASCII-1 characters are used in the C-string as boundary markers,
        // to indicate the boundaries between the original constituent P-strings.
        for (i=1; i<query->info->TXTlen; i++)
                {
                if (--pstrlen >= 0)
                        cstring[i-1] = query->info->TXTinfo[i];
                else
                        {
                        cstring[i-1] = 1;
                        pstrlen = query->info->TXTinfo[i];
                        }
                }
        cstring[i-1] = 0;               // Put the terminating NULL on the end

        LogOperation("%5d: DNSServiceResolver(%##s) -> %#a:%u", x->ClientMachPort,
                x->i.name.c, &query->info->ip, mDNSVal16(query->info->port));
        status = DNSServiceResolverReply_rpc(x->ClientMachPort,
                (char*)&interface, (char*)&address, cstring, 0, MDNS_MM_TIMEOUT);
        if (status == MACH_SEND_TIMED_OUT)
                AbortBlockedClient(x->ClientMachPort, "resolve", x);
        }

mDNSexport kern_return_t provide_DNSServiceResolverResolve_rpc(mach_port_t unusedserver, mach_port_t client,
        DNSCString name, DNSCString regtype, DNSCString domain)
        {
        // Check client parameter
        (void)unusedserver;             // Unused
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";
        if (client == (mach_port_t)-1)      { err = mStatus_Invalid; errormsg = "Client id -1 invalid";     goto fail; }
        if (CheckForExistingClient(client)) { err = mStatus_Invalid; errormsg = "Client id already in use"; goto fail; }

        // Check other parameters
        domainlabel n;
        domainname t, d, srv;
        if (!name[0]    || !MakeDomainLabelFromLiteralString(&n, name))        { errormsg = "Bad Instance Name"; goto badparam; }
        if (!regtype[0] || !MakeDomainNameFromDNSNameString(&t, regtype))      { errormsg = "Bad Service Type";  goto badparam; }
        if (!domain[0]  || !MakeDomainNameFromDNSNameString(&d, domain))       { errormsg = "Bad Domain";        goto badparam; }
        if (!ConstructServiceName(&srv, &n, &t, &d))                           { errormsg = "Bad Name";          goto badparam; }

        // Allocate memory, and handle failure
        DNSServiceResolver *x = mallocL("DNSServiceResolver", sizeof(*x));
        if (!x) { err = mStatus_NoMemoryErr; errormsg = "No memory"; goto fail; }

        // Set up object, and link into list
        x->ClientMachPort = client;
        x->i.InterfaceID = mDNSInterface_Any;
        x->i.name = srv;
        x->ReportTime = NonZeroTime(mDNS_TimeNow(&mDNSStorage) + 130 * mDNSPlatformOneSecond);
        x->next = DNSServiceResolverList;
        DNSServiceResolverList = x;

        // Do the operation
        LogOperation("%5d: DNSServiceResolve(%##s) START", client, x->i.name.c);
        err = mDNS_StartResolveService(&mDNSStorage, &x->q, &x->i, FoundInstanceInfo, x);
        if (err) { AbortClient(client, x); errormsg = "mDNS_StartResolveService"; goto fail; }

        // Succeeded: Wrap up and return
        EnableDeathNotificationForClient(client, x);
        return(mStatus_NoError);

badparam:
        err = mStatus_BadParamErr;
fail:
        LogMsg("%5d: DNSServiceResolve(\"%s\", \"%s\", \"%s\") failed: %s (%d)", client, name, regtype, domain, errormsg, err);
        return(err);
        }

//*************************************************************************************************************
// Registration

mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay)
        {
        m->p->NotifyUser = NonZeroTime(m->timenow + delay);
        }

mDNSlocal void RegCallback(mDNS *const m, ServiceRecordSet *const srs, mStatus result)
        {
        ServiceInstance *si = (ServiceInstance*)srs->ServiceContext;

        if (result == mStatus_NoError)
                {
                kern_return_t status;
                LogOperation("%5d: DNSServiceRegistration(%##s, %u) Name Registered", si->ClientMachPort, srs->RR_SRV.resrec.name->c, SRS_PORT(srs));
                status = DNSServiceRegistrationReply_rpc(si->ClientMachPort, result, MDNS_MM_TIMEOUT);
                if (status == MACH_SEND_TIMED_OUT)
                        AbortBlockedClient(si->ClientMachPort, "registration success", si);
                if (si->autoname && CountPeerRegistrations(m, srs) == 0)
                        RecordUpdatedNiceLabel(m, 0);   // Successfully got new name, tell user immediately
                }

        else if (result == mStatus_NameConflict)
                {
                LogOperation("%5d: DNSServiceRegistration(%##s, %u) Name Conflict", si->ClientMachPort, srs->RR_SRV.resrec.name->c, SRS_PORT(srs));
                // Note: By the time we get the mStatus_NameConflict message, the service is already deregistered
                // and the memory is free, so we don't have to wait for an mStatus_MemFree message as well.
                if (si->autoname && CountPeerRegistrations(m, srs) == 0)
                        {
                        // On conflict for an autoname service, rename and reregister *all* autoname services
                        IncrementLabelSuffix(&m->nicelabel, mDNStrue);
                        mDNS_ConfigChanged(m);
                        }
                else if (si->autoname)
                        {
            mDNS_RenameAndReregisterService(m, srs, mDNSNULL);
            return;
                        }
                else
                        {
                        // If we get a name conflict, we tell the client about it, and then they are expected to dispose
                        // of their registration in the usual way (which we will catch via client death notification).
                        // If the Mach queue is full, we forcibly abort the client immediately.
                        kern_return_t status = DNSServiceRegistrationReply_rpc(si->ClientMachPort, result, MDNS_MM_TIMEOUT);
                        if (status == MACH_SEND_TIMED_OUT)
                                AbortBlockedClient(si->ClientMachPort, "registration conflict", NULL);
                        }
                }

        else if (result == mStatus_MemFree)
                {
                if (si->renameonmemfree)        // We intentionally terminated registration so we could re-register with new name
                        {
                        debugf("RegCallback renaming %#s to %#s", si->name.c, m->nicelabel.c);
                        si->renameonmemfree = mDNSfalse;
                        si->name            = m->nicelabel;
                        mDNS_RenameAndReregisterService(m, srs, &si->name);
                        }
                else
                        {
                        // SANITY CHECK: make sure service instance is no longer in any ServiceRegistration's list
                        DNSServiceRegistration *r;
                        for (r = DNSServiceRegistrationList; r; r = r->next)
                                {
                                ServiceInstance **sp = &r->regs;
                                while (*sp)
                                        {
                                        if (*sp == si) { LogMsg("RegCallback: %##s Still in list; removing", srs->RR_SRV.resrec.name->c); *sp = (*sp)->next; break; }
                                        sp = &(*sp)->next;
                                        }
                            }
                        // END SANITY CHECK
                        FreeServiceInstance(si);
                        }
                }

        else if (result != mStatus_NATTraversal)
                LogMsg("%5d: DNSServiceRegistration(%##s, %u) Unknown Result %d", si->ClientMachPort, srs->RR_SRV.resrec.name->c, SRS_PORT(srs), result);
        }

mDNSlocal mStatus AddServiceInstance(DNSServiceRegistration *x, const domainname *domain)
        {
        mStatus err = 0;
        ServiceInstance *si = NULL;
        AuthRecord *SubTypes = NULL;

        for (si = x->regs; si; si = si->next)
                {
                if (SameDomainName(&si->domain, domain))
                        { LogMsg("Requested addition of domain %##s already in list", domain->c); return mStatus_AlreadyRegistered; }
                }
        
        SubTypes = AllocateSubTypes(x->NumSubTypes, x->regtype);
        if (x->NumSubTypes && !SubTypes) return mStatus_NoMemoryErr;
        
        si = mallocL("ServiceInstance", sizeof(*si) - sizeof(RDataBody) + x->rdsize);
        if (!si) return mStatus_NoMemoryErr;

        si->ClientMachPort  = x->ClientMachPort;
        si->renameonmemfree = mDNSfalse;
        si->autoname        = x->autoname;
        si->name            = x->autoname ? mDNSStorage.nicelabel : x->name;
        si->domain          = *domain;

        err = mDNS_RegisterService(&mDNSStorage, &si->srs, &si->name, &x->type, domain, NULL,
                x->port, x->txtinfo, x->txt_len, SubTypes, x->NumSubTypes, mDNSInterface_Any, RegCallback, si, 0);
        if (!err)
                {
                si->next = x->regs;
                x->regs = si;
                }
        else
                {
                LogMsg("Error %d for registration of service in domain %##s", err, domain->c);
                freeL("ServiceInstance", si);
                }
        return err;
        }

mDNSexport void machserver_automatic_registration_domain_changed(const domainname *d, mDNSBool add)
        {
        DNSServiceRegistration *reg;

        for (reg = DNSServiceRegistrationList; reg; reg = reg->next)
                {
                if (reg->DefaultDomain)
                        {
                        if (add)
                                AddServiceInstance(reg, d);
                        else
                                {
                                ServiceInstance **si = &reg->regs;
                                while (*si)
                                        {
                                        if (SameDomainName(&(*si)->domain, d))
                                                {
                                                ServiceInstance *s = *si;
                                                *si = (*si)->next;
                                                if (mDNS_DeregisterService(&mDNSStorage, &s->srs)) FreeServiceInstance(s);  // only free memory synchronously on error
                                                break;
                                                }
                                        si = &(*si)->next;
                                        }
                                if (!si) debugf("Requested removal of default domain %##s not in client %5d's list", d, reg->ClientMachPort); // normal if registration failed
                                }
                        }
                }
        }

mDNSexport kern_return_t provide_DNSServiceRegistrationCreate_rpc(mach_port_t unusedserver, mach_port_t client,
        DNSCString name, DNSCString regtype, DNSCString domain, IPPort IpPort, DNSCString txtRecord)
        {
        (void)unusedserver;             // Unused
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";

        // older versions of this code passed the port via mach IPC as an int.
        // we continue to pass it as 4 bytes to maintain binary compatibility,
        // but now ensure that the network byte order is preserved by using a struct
        mDNSIPPort port;
        port.b[0] = IpPort.bytes[2];
        port.b[1] = IpPort.bytes[3];

        if (client == (mach_port_t)-1)      { err = mStatus_Invalid; errormsg = "Client id -1 invalid";     goto fail; }
        if (CheckForExistingClient(client)) { err = mStatus_Invalid; errormsg = "Client id already in use"; goto fail; }

    // Check for sub-types after the service type
        size_t reglen = strlen(regtype) + 1;
        if (reglen > MAX_ESCAPED_DOMAIN_NAME) { errormsg = "reglen too long"; goto badparam; }
        mDNSs32 NumSubTypes = ChopSubTypes(regtype);    // Note: Modifies regtype string to remove trailing subtypes
        if (NumSubTypes < 0) { errormsg = "Bad Service SubType"; goto badparam; }

        // Check other parameters
        domainlabel n;
        domainname t, d;
        domainname srv;
        if (!name[0]) n = mDNSStorage.nicelabel;
        else if (!MakeDomainLabelFromLiteralString(&n, name))                  { errormsg = "Bad Instance Name"; goto badparam; }
        if (!regtype[0] || !MakeDomainNameFromDNSNameString(&t, regtype))      { errormsg = "Bad Service Type";  goto badparam; }
        if (!MakeDomainNameFromDNSNameString(&d, *domain ? domain : "local.")) { errormsg = "Bad Domain";        goto badparam; }
        if (!ConstructServiceName(&srv, &n, &t, &d))                           { errormsg = "Bad Name";          goto badparam; }

        unsigned char txtinfo[1024] = "";
        unsigned int data_len = 0;
        unsigned int size = sizeof(RDataBody);
        unsigned char *pstring = &txtinfo[data_len];
        char *ptr = txtRecord;

        // The OS X DNSServiceRegistrationCreate() API is defined using a C-string,
        // but the mDNS_RegisterService() call actually requires a packed block of P-strings.
        // Hence we have to convert the C-string to a P-string.
        // ASCII-1 characters are allowed in the C-string as boundary markers,
        // so that a single C-string can be used to represent one or more P-strings.
        while (*ptr)
                {
                if (++data_len >= sizeof(txtinfo)) { errormsg = "TXT record too long"; goto badtxt; }
                if (*ptr == 1)          // If this is our boundary marker, start a new P-string
                        {
                        pstring = &txtinfo[data_len];
                        pstring[0] = 0;
                        ptr++;
                        }
                else
                        {
                        if (pstring[0] == 255) { errormsg = "TXT record invalid (component longer than 255)"; goto badtxt; }
                        pstring[++pstring[0]] = *ptr++;
                        }
                }

        data_len++;
        if (size < data_len)
                size = data_len;

        // 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(port))
                {
                int count = CountExistingRegistrations(&srv, port);
                if (count)
                        LogMsg("%5d: Client application registered %d identical instances of service %##s port %u.",
                                   client, count+1, srv.c, mDNSVal16(port));
                }
        
        // Allocate memory, and handle failure
        DNSServiceRegistration *x = mallocL("DNSServiceRegistration", sizeof(*x));
        if (!x) { err = mStatus_NoMemoryErr; errormsg = "No memory"; goto fail; }
        mDNSPlatformMemZero(x, sizeof(*x));

        // Set up object, and link into list
        x->ClientMachPort = client;
        x->DefaultDomain = !domain[0];
        x->autoname = (!name[0]);
        x->rdsize = size;
        x->NumSubTypes = NumSubTypes;
        memcpy(x->regtype, regtype, reglen);
        x->name = n;
        x->type = t;
        x->port = port;
        memcpy(x->txtinfo, txtinfo, 1024);
        x->txt_len = data_len;
        x->NextRef = 0;
        x->regs = NULL;
        
        x->next = DNSServiceRegistrationList;
        DNSServiceRegistrationList = x;

        LogOperation("%5d: DNSServiceRegistration(\"%s\", \"%s\", \"%s\", %u) START",
                x->ClientMachPort, name, regtype, domain, mDNSVal16(port));

        err = AddServiceInstance(x, &d);
        if (err) { AbortClient(client, x); errormsg = "mDNS_RegisterService"; goto fail; }  // bail if .local (or explicit domain) fails

        if (x->DefaultDomain)
                {
                DNameListElem *p;
                for (p = AutoRegistrationDomains; p; p = p->next)
                        AddServiceInstance(x, &p->name);
                }

        // Succeeded: Wrap up and return
        EnableDeathNotificationForClient(client, x);
        return(mStatus_NoError);

badtxt:
        LogMsg("%5d: TXT record: %.100s...", client, txtRecord);
badparam:
        err = mStatus_BadParamErr;
fail:
        LogMsg("%5d: DNSServiceRegister(\"%s\", \"%s\", \"%s\", %d) failed: %s (%d)",
                   client, name, regtype, domain, mDNSVal16(port), errormsg, err);
        return(err);
        }

mDNSlocal void mDNSPreferencesSetNames(mDNS *const m, int key, domainlabel *old, domainlabel *new)
        {
        domainlabel *prevold, *prevnew;
        switch (key)
                {
                case kmDNSComputerName:
                case kmDNSLocalHostName:
                        if (key == kmDNSComputerName)
                                {
                                prevold = &m->p->prevoldnicelabel;
                                prevnew = &m->p->prevnewnicelabel;
                                }
                        else
                                {
                                prevold = &m->p->prevoldhostlabel;
                                prevnew = &m->p->prevnewhostlabel;
                                }
                        // There are a few cases where we need to invoke the helper.
                        //
                        // 1. If the "old" label and "new" label are not same, it means there is a conflict. We need
                        //    to invoke the helper so that it pops up a dialogue to inform the user about the
                        //    conflict
                        //
                        // 2. If the "old" label and "new" label are same, it means the user has set the host/nice label
                        //    through the preferences pane. We may have to inform the helper as it may have popped up
                        //    a dialogue previously (due to a conflict) and it needs to suppress it now. We can avoid invoking
                        //    the helper in this case if the previous values (old and new) that we told helper last time
                        //    are same. If the previous old and new values are same, helper does not care.
                        //
                        // Note: "new" can be NULL when we have repeated conflicts and we are asking helper to give up. "old"
                        // is not called with NULL today, but this makes it future proof.
                        if (!old || !new || !SameDomainLabelCS(old->c, new->c) || 
                            !SameDomainLabelCS(old->c, prevold->c) ||
                            !SameDomainLabelCS(new->c, prevnew->c))
                                {
                                if (old)
                                        *prevold = *old;
                                else
                                        prevold->c[0] = 0;
                                if (new)
                                        *prevnew = *new;
                                else
                                        prevnew->c[0] = 0;
                                mDNSPreferencesSetName(key, old, new);
                                }
                        else 
                                {
                                LogInfo("mDNSPreferencesSetNames not invoking helper %s %#s, %s %#s, old %#s, new %#s",
                                                (key == kmDNSComputerName ? "prevoldnicelabel" : "prevoldhostlabel"), prevold->c,
                                                (key == kmDNSComputerName ? "prevnewnicelabel" : "prevnewhostlabel"), prevnew->c,
                                                old->c, new->c);
                                }
                        break;
                default:
                        LogMsg("mDNSPreferencesSetNames: unrecognized key: %d", key);
                        return;
                }
        }

mDNSlocal void mDNS_StatusCallback(mDNS *const m, mStatus result)
        {
        (void)m; // Unused
        if (result == mStatus_NoError)
                {
                if (!SameDomainLabelCS(m->p->userhostlabel.c, m->hostlabel.c))
                        LogInfo("Local Hostname changed from \"%#s.local\" to \"%#s.local\"", m->p->userhostlabel.c, m->hostlabel.c);
                // One second pause in case we get a Computer Name update too -- don't want to alert the user twice
                RecordUpdatedNiceLabel(m, mDNSPlatformOneSecond);
                }
        else if (result == mStatus_NameConflict)
                {
                LogInfo("Local Hostname conflict for \"%#s.local\"", m->hostlabel.c);
                if (!m->p->HostNameConflict) m->p->HostNameConflict = NonZeroTime(m->timenow);
                else if (m->timenow - m->p->HostNameConflict > 60 * mDNSPlatformOneSecond)
                        {
                        // Tell the helper we've given up
                        mDNSPreferencesSetNames(m, kmDNSLocalHostName, &m->p->userhostlabel, NULL);
                        }
                }
        else if (result == mStatus_GrowCache)
                {
                // Allocate another chunk of cache storage
                CacheEntity *storage = mallocL("mStatus_GrowCache", sizeof(CacheEntity) * RR_CACHE_SIZE);
                //LogInfo("GrowCache %d * %d = %d", sizeof(CacheEntity), RR_CACHE_SIZE, sizeof(CacheEntity) * RR_CACHE_SIZE);
                if (storage) mDNS_GrowCache(m, storage, RR_CACHE_SIZE);
                }
        else if (result == mStatus_ConfigChanged)
                {
                // Tell the helper we've seen a change in the labels.  It will dismiss the name conflict alert if needed.
                mDNSPreferencesSetNames(m, kmDNSComputerName, &m->p->usernicelabel, &m->nicelabel);
                mDNSPreferencesSetNames(m, kmDNSLocalHostName, &m->p->userhostlabel, &m->hostlabel);

                // First we check our list of old Mach-based registered services, to see if any need to be updated to a new name
                DNSServiceRegistration *r;
                for (r = DNSServiceRegistrationList; r; r=r->next)
                        if (r->autoname)
                                {
                                ServiceInstance *si;
                                for (si = r->regs; si; si = si->next)
                                        {
                                        if (!SameDomainLabelCS(si->name.c, m->nicelabel.c))
                                                {
                                                debugf("NetworkChanged renaming %##s to %#s", si->srs.RR_SRV.resrec.name->c, m->nicelabel.c);
                                                si->renameonmemfree = mDNStrue;
                                                if (mDNS_DeregisterService_drt(m, &si->srs, mDNS_Dereg_rapid))
                                                        RegCallback(m, &si->srs, mStatus_MemFree);      // If service deregistered already, we can re-register immediately
                                                }
                                        }
                                }

                // Then we call into the UDS daemon code, to let it do the same
                udsserver_handle_configchange(m);
                }
        }

//*************************************************************************************************************
// Add / Update / Remove records from existing Registration

mDNSexport kern_return_t provide_DNSServiceRegistrationAddRecord_rpc(mach_port_t unusedserver, mach_port_t client,
        int type, const char *data, mach_msg_type_number_t data_len, uint32_t ttl, natural_t *reference)
        {
        // Check client parameter
        uint32_t id;
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";
        DNSServiceRegistration *x = DNSServiceRegistrationList;
        if (client == (mach_port_t)-1) { err = mStatus_Invalid;         errormsg = "Client id -1 invalid"; goto fail; }
        ServiceInstance *si;
        size_t size;
        (void)unusedserver;             // Unused
        while (x && x->ClientMachPort != client) x = x->next;
        if (!x)                        { err = mStatus_BadReferenceErr; errormsg = "No such client";       goto fail; }

        // Check other parameters
        if (data_len > 8192) { err = mStatus_BadParamErr; errormsg = "data_len > 8K"; goto fail; }
        if (data_len > sizeof(RDataBody)) size = data_len;
        else size = sizeof(RDataBody);
        
        id = x->NextRef++;
        *reference = (natural_t)id;
        for (si = x->regs; si; si = si->next)
                {
                // Allocate memory, and handle failure
                ExtraResourceRecord *extra = mallocL("ExtraResourceRecord", sizeof(*extra) - sizeof(RDataBody) + size);
                if (!extra) { err = mStatus_NoMemoryErr; errormsg = "No memory"; goto fail; }
                
                // Fill in type, length, and data of new record
                extra->r.resrec.rrtype = type;
                extra->r.rdatastorage.MaxRDLength = size;
                extra->r.resrec.rdlength          = data_len;
                memcpy(&extra->r.rdatastorage.u.data, data, data_len);

                // Do the operation
                LogOperation("%5d: DNSServiceRegistrationAddRecord(%##s, type %d, length %d) REF %p",
                                         client, si->srs.RR_SRV.resrec.name->c, type, data_len, extra);
                err = mDNS_AddRecordToService(&mDNSStorage, &si->srs, extra, &extra->r.rdatastorage, ttl, 0);

                if (err)
                        {
                        freeL("Extra Resource Record", extra);
                        errormsg = "mDNS_AddRecordToService";
                        goto fail;
                        }

                extra->ClientID = id;
                }

        return mStatus_NoError;

fail:
        LogMsg("%5d: DNSServiceRegistrationAddRecord(%##s, type %d, length %d) failed: %s (%d)", client, x ? x->name.c : (mDNSu8*)"\x8""«NULL»", type, data_len, errormsg, err);
        return mStatus_UnknownErr;
        }

mDNSlocal void UpdateCallback(mDNS *const m, AuthRecord *const rr, RData *OldRData, mDNSu16 OldRDLen)
        {
        (void)m;                // Unused
        (void)OldRDLen; // Unused
        if (OldRData != &rr->rdatastorage)
                freeL("Old RData", OldRData);
        }

mDNSlocal mStatus UpdateRecord(ServiceRecordSet *srs, mach_port_t client, AuthRecord *rr, const char *data, mach_msg_type_number_t data_len, uint32_t ttl)
        {
    // Check client parameter
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";
        const domainname *name = (const domainname *)"";

        name = srs->RR_SRV.resrec.name;

        unsigned int size = sizeof(RDataBody);
    if (size < data_len)
                size = data_len;

        // Allocate memory, and handle failure
        RData *newrdata = mallocL("RData", sizeof(*newrdata) - sizeof(RDataBody) + size);
        if (!newrdata) { err = mStatus_NoMemoryErr; errormsg = "No memory"; goto fail; }

        // Fill in new length, and data
        newrdata->MaxRDLength = size;
        memcpy(&newrdata->u, data, data_len);
        
        // 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 && data_len == 0) { data_len = 1; newrdata->u.txt.c[0] = 0; }

        // Do the operation
        LogOperation("%5d: DNSServiceRegistrationUpdateRecord(%##s, new length %d)",
                client, srs->RR_SRV.resrec.name->c, data_len);

        err = mDNS_Update(&mDNSStorage, rr, ttl, data_len, newrdata, UpdateCallback);
        if (err)
                {
                errormsg = "mDNS_Update";
                freeL("RData", newrdata);
                return err;
                }
        return(mStatus_NoError);

fail:
        LogMsg("%5d: DNSServiceRegistrationUpdateRecord(%##s, %d) failed: %s (%d)", client, name->c, data_len, errormsg, err);
        return(err);
        }

mDNSexport kern_return_t provide_DNSServiceRegistrationUpdateRecord_rpc(mach_port_t unusedserver, mach_port_t client,
                natural_t reference, const char *data, mach_msg_type_number_t data_len, uint32_t ttl)
        {
    // Check client parameter
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";
        const domainname *name = (const domainname *)"";
        ServiceInstance *si;

        (void)unusedserver; // unused
    if (client == (mach_port_t)-1) { err = mStatus_Invalid;         errormsg = "Client id -1 invalid"; goto fail; }
        DNSServiceRegistration *x = DNSServiceRegistrationList;
        while (x && x->ClientMachPort != client) x = x->next;
        if (!x)                        { err = mStatus_BadReferenceErr; errormsg = "No such client";       goto fail; }

        // Check other parameters
        if (data_len > 8192) { err = mStatus_BadParamErr; errormsg = "data_len > 8K"; goto fail; }

        for (si = x->regs; si; si = si->next)
                {
                AuthRecord *r = NULL;

                // Find the record we're updating. NULL reference means update the primary TXT record
                if (!reference) r = &si->srs.RR_TXT;
                else
                        {
                        ExtraResourceRecord *ptr;
                        for (ptr = si->srs.Extras; ptr; ptr = ptr->next)
                                {
                                if ((natural_t)ptr->ClientID == reference)
                                        { r = &ptr->r; break; }
                                }
                        if (!r) { err = mStatus_BadReferenceErr; errormsg = "No such record"; goto fail; }
                        }
                err = UpdateRecord(&si->srs, client, r, data, data_len, ttl);
                if (err) goto fail;  //!!!KRS this will cause failures for non-local defaults!
                }
                                        
        return mStatus_NoError;

fail:
        LogMsg("%5d: DNSServiceRegistrationUpdateRecord(%##s, %X, %d) failed: %s (%d)", client, name->c, reference, data_len, errormsg, err);
        return(err);
        }

mDNSlocal mStatus RemoveRecord(ServiceRecordSet *srs, ExtraResourceRecord *extra, mach_port_t client)
        {
        const domainname *const name = srs->RR_SRV.resrec.name;
        mStatus err = mStatus_NoError;

        // Do the operation
        LogOperation("%5d: DNSServiceRegistrationRemoveRecord(%##s)", client, srs->RR_SRV.resrec.name->c);

        err = mDNS_RemoveRecordFromService(&mDNSStorage, srs, extra, FreeExtraRR, extra);
        if (err) LogMsg("%5d: DNSServiceRegistrationRemoveRecord (%##s) failed: %d", client, name->c, err);
        
        return err;
        }

mDNSexport kern_return_t provide_DNSServiceRegistrationRemoveRecord_rpc(mach_port_t unusedserver, mach_port_t client,
        natural_t reference)
        {
        // Check client parameter
        (void)unusedserver;             // Unused
        mStatus err = mStatus_NoError;
        const char *errormsg = "Unknown";
        if (client == (mach_port_t)-1) { err = mStatus_Invalid;         errormsg = "Client id -1 invalid"; goto fail; }
        DNSServiceRegistration *x = DNSServiceRegistrationList;
        ServiceInstance *si;

        while (x && x->ClientMachPort != client) x = x->next;
        if (!x)                        { err = mStatus_BadReferenceErr; errormsg = "No such client";       goto fail; }

        for (si = x->regs; si; si = si->next)
                {
                ExtraResourceRecord *e;
                for (e = si->srs.Extras; e; e = e->next)
                        {
                        if ((natural_t)e->ClientID == reference)
                                {
                                err = RemoveRecord(&si->srs, e, client);
                                break;
                                }
                        }
                if (!e) { err = mStatus_BadReferenceErr; errormsg = "No such reference"; goto fail; }
                }

        return mStatus_NoError;

fail:
        LogMsg("%5d: DNSServiceRegistrationRemoveRecord(%X) failed: %s (%d)", client, reference, errormsg, err);
        return(err);
        }

//*************************************************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Startup, shutdown, and supporting code
#endif

mDNSlocal void DNSserverCallback(CFMachPortRef port, void *msg, CFIndex size, void *info)
        {
        mig_reply_error_t *request = msg;
        mig_reply_error_t *reply;
        mach_msg_return_t mr;
        int               options;
        (void)port;             // Unused
        (void)size;             // Unused
        (void)info;             // Unused

        KQueueLock(&mDNSStorage);
        
        /* allocate a reply buffer */
        reply = CFAllocatorAllocate(NULL, provide_DNSServiceDiscoveryRequest_subsystem.maxsize, 0);

        /* call the MiG server routine */
        (void) DNSServiceDiscoveryRequest_server(&request->Head, &reply->Head);

        if (!(reply->Head.msgh_bits & MACH_MSGH_BITS_COMPLEX) && (reply->RetCode != KERN_SUCCESS))
                {
        if (reply->RetCode == MIG_NO_REPLY)
                        {
            /*
             * This return code is a little tricky -- it appears that the
             * demux routine found an error of some sort, but since that
             * error would not normally get returned either to the local
             * user or the remote one, we pretend it's ok.
             */
            CFAllocatorDeallocate(NULL, reply);
            goto done;
                        }

        /*
         * destroy any out-of-line data in the request buffer but don't destroy
         * the reply port right (since we need that to send an error message).
         */
        request->Head.msgh_remote_port = MACH_PORT_NULL;
        mach_msg_destroy(&request->Head);
                }

    if (reply->Head.msgh_remote_port == MACH_PORT_NULL)
                {
        /* no reply port, so destroy the reply */
        if (reply->Head.msgh_bits & MACH_MSGH_BITS_COMPLEX)
            mach_msg_destroy(&reply->Head);
        CFAllocatorDeallocate(NULL, reply);
        goto done;
                }

    /*
     * send reply.
     *
     * We don't want to block indefinitely because the client
     * isn't receiving messages from the reply port.
     * If we have a send-once right for the reply port, then
     * this isn't a concern because the send won't block.
     * If we have a send right, we need to use MACH_SEND_TIMEOUT.
     * To avoid falling off the kernel's fast RPC path unnecessarily,
     * we only supply MACH_SEND_TIMEOUT when absolutely necessary.
     */

    options = MACH_SEND_MSG;
    if (MACH_MSGH_BITS_REMOTE(reply->Head.msgh_bits) == MACH_MSG_TYPE_MOVE_SEND_ONCE)
        options |= MACH_SEND_TIMEOUT;

    mr = mach_msg(&reply->Head,         /* msg */
                      options,                  /* option */
                      reply->Head.msgh_size,    /* send_size */
                      0,                        /* rcv_size */
                      MACH_PORT_NULL,           /* rcv_name */
                      MACH_MSG_TIMEOUT_NONE,    /* timeout */
                      MACH_PORT_NULL);          /* notify */

    /* Has a message error occurred? */
    switch (mr)
                {
        case MACH_SEND_INVALID_DEST:
        case MACH_SEND_TIMED_OUT:
            /* the reply can't be delivered, so destroy it */
            mach_msg_destroy(&reply->Head);
            break;

        default :
            /* Includes success case. */
            break;
                }

    CFAllocatorDeallocate(NULL, reply);
        
done:
        KQueueUnlock(&mDNSStorage, "Mach client event");
        }

mDNSlocal kern_return_t registerBootstrapService()
        {
        kern_return_t status;
        mach_port_t service_send_port, service_rcv_port;

        debugf("Registering Bootstrap Service");

        /*
         * See if our service name is already registered and if we have privilege to check in.
         */
        status = bootstrap_check_in(bootstrap_port, (char*)kmDNSBootstrapName, &service_rcv_port);
        if (status == KERN_SUCCESS)
                {
                /*
                 * If so, we must be a followup instance of an already defined server.  In that case,
                 * the bootstrap port we inherited from our parent is the server's privilege port, so set
                 * that in case we have to unregister later (which requires the privilege port).
                 */
                server_priv_port = bootstrap_port;
                restarting_via_mach_init = TRUE;
                }
        else if (status == BOOTSTRAP_UNKNOWN_SERVICE)
                {
                status = bootstrap_create_server(bootstrap_port, "/usr/sbin/mDNSResponder", getuid(),
                        FALSE /* relaunch immediately, not on demand */, &server_priv_port);
                if (status != KERN_SUCCESS) return status;

                status = bootstrap_create_service(server_priv_port, (char*)kmDNSBootstrapName, &service_send_port);
                if (status != KERN_SUCCESS)
                        {
                        mach_port_deallocate(mach_task_self(), server_priv_port);
                        return status;
                        }

                status = bootstrap_check_in(server_priv_port, (char*)kmDNSBootstrapName, &service_rcv_port);
                if (status != KERN_SUCCESS)
                        {
                        mach_port_deallocate(mach_task_self(), server_priv_port);
                        mach_port_deallocate(mach_task_self(), service_send_port);
                        return status;
                        }
                assert(service_send_port == service_rcv_port);
                }

        /*
         * We have no intention of responding to requests on the service port.  We are not otherwise
         * a Mach port-based service.  We are just using this mechanism for relaunch facilities.
         * So, we can dispose of all the rights we have for the service port.  We don't destroy the
         * send right for the server's privileged bootstrap port - in case we have to unregister later.
         */
        mach_port_destroy(mach_task_self(), service_rcv_port);
        return status;
        }

mDNSlocal kern_return_t destroyBootstrapService()
        {
        debugf("Destroying Bootstrap Service");
        return bootstrap_register(server_priv_port, (char*)kmDNSBootstrapName, MACH_PORT_NULL);
        }

mDNSlocal void ExitCallback(int sig)
        {
        (void)sig; // Unused
        LogMsg("%s stopping", mDNSResponderVersionString);

        debugf("ExitCallback");
        if (!mDNS_DebugMode && !started_via_launchdaemon)
                destroyBootstrapService();

        debugf("ExitCallback: Aborting MIG clients");
        while (DNSServiceDomainEnumerationList)
                AbortClient(DNSServiceDomainEnumerationList->ClientMachPort, DNSServiceDomainEnumerationList);
        while (DNSServiceBrowserList)
                AbortClient(DNSServiceBrowserList          ->ClientMachPort, DNSServiceBrowserList);
        while (DNSServiceResolverList)
                AbortClient(DNSServiceResolverList         ->ClientMachPort, DNSServiceResolverList);
        while (DNSServiceRegistrationList)
                AbortClient(DNSServiceRegistrationList     ->ClientMachPort, DNSServiceRegistrationList);

        if (udsserver_exit() < 0) LogMsg("ExitCallback: udsserver_exit failed");

        debugf("ExitCallback: mDNS_StartExit");
        mDNS_StartExit(&mDNSStorage);
        }

#ifndef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

// Send a mach_msg to ourselves (since that is signal safe) telling us to cleanup and exit
mDNSlocal void HandleSIG(int sig)
        {
        kern_return_t status;
        mach_msg_header_t header;

        // WARNING: can't call syslog or fprintf from signal handler
        header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND, 0);
        header.msgh_remote_port = signal_port;
        header.msgh_local_port = MACH_PORT_NULL;
        header.msgh_size = sizeof(header);
        header.msgh_id = sig;

        status = mach_msg(&header, MACH_SEND_MSG | MACH_SEND_TIMEOUT, header.msgh_size,
                0, MACH_PORT_NULL, 0, MACH_PORT_NULL);

        if (status != MACH_MSG_SUCCESS)
                {
                if (status == MACH_SEND_TIMED_OUT) mach_msg_destroy(&header);
                if (sig == SIGTERM || sig == SIGINT) exit(-1);
                }
        }

#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSlocal void INFOCallback(void)
        {
        mDNSs32 utc = mDNSPlatformUTC();
        DNSServiceDomainEnumeration *e;
        DNSServiceBrowser           *b;
        DNSServiceResolver          *l;
        DNSServiceRegistration      *r;
        NetworkInterfaceInfoOSX     *i;
        DNSServer *s;
        McastResolver *mr;

        LogMsg("---- BEGIN STATE LOG ---- %s %s %d", mDNSResponderVersionString, OSXVers ? "OSXVers" : "iOSVers", OSXVers ? OSXVers : iOSVers);
        
        udsserver_info(&mDNSStorage);

        LogMsgNoIdent("--------- Mach Clients ---------");
        if (!DNSServiceDomainEnumerationList && !DNSServiceBrowserList && !DNSServiceResolverList && !DNSServiceRegistrationList)
                LogMsgNoIdent("<None>");
        else
                {
                for (e = DNSServiceDomainEnumerationList; e; e=e->next)
                        LogMsgNoIdent("%5d: Mach DomainEnumeration   %##s", e->ClientMachPort, e->dom.qname.c);
        
                for (b = DNSServiceBrowserList; b; b=b->next)
                        {
                        DNSServiceBrowserQuestion *qptr;
                        for (qptr = b->qlist; qptr; qptr = qptr->next)
                                LogMsgNoIdent("%5d: Mach ServiceBrowse       %##s", b->ClientMachPort, qptr->q.qname.c);
                        }

                for (l = DNSServiceResolverList; l; l=l->next)
                        LogMsgNoIdent("%5d: Mach ServiceResolve      %##s", l->ClientMachPort, l->i.name.c);
        
                for (r = DNSServiceRegistrationList; r; r=r->next)
                        {
                        ServiceInstance *si;
                        for (si = r->regs; si; si = si->next)
                                LogMsgNoIdent("%5d: Mach ServiceInstance     %##s %u", si->ClientMachPort, si->srs.RR_SRV.resrec.name->c, mDNSVal16(si->srs.RR_SRV.resrec.rdata->u.srv.port));
                        }
                }

        LogMsgNoIdent("----- KQSocketEventSources -----");
        if (!gEventSources) LogMsgNoIdent("<None>");
        else
                {
                KQSocketEventSource *k;
                for (k = gEventSources; k; k=k->next)
                        {
                        LogMsgNoIdent("%3d %s", k->fd, k->kqs.KQtask);
                        usleep((mDNSStorage.KnownBugs & mDNS_KnownBug_LossySyslog) ? 3333 : 1000);
                        }
                }

        LogMsgNoIdent("------ Network Interfaces ------");
        if (!mDNSStorage.p->InterfaceList) LogMsgNoIdent("<None>");
        else
                {
                for (i = mDNSStorage.p->InterfaceList; i; i = i->next)
                        {
                        // Allow six characters for interface name, for names like "vmnet8"
                        if (!i->Exists)
                                LogMsgNoIdent("%p %2ld, Registered %p,  %s %-6s(%lu) %.6a %.6a %#-14a dormant for %d seconds",
                                        i, i->ifinfo.InterfaceID, i->Registered,
                                        i->sa_family == AF_INET ? "v4" : i->sa_family == AF_INET6 ? "v6" : "??", i->ifinfo.ifname, i->scope_id, &i->ifinfo.MAC, &i->BSSID,
                                        &i->ifinfo.ip, utc - i->LastSeen);
                        else
                                {
                                const CacheRecord *sps[3];
                                FindSPSInCache(&mDNSStorage, &i->ifinfo.NetWakeBrowse, sps);
                                LogMsgNoIdent("%p %2ld, Registered %p,  %s %-6s(%lu) %.6a %.6a %s %s %-15.4a %s %s %s %s %#a",
                                        i, i->ifinfo.InterfaceID, i->Registered,
                                        i->sa_family == AF_INET ? "v4" : i->sa_family == AF_INET6 ? "v6" : "??", i->ifinfo.ifname, i->scope_id, &i->ifinfo.MAC, &i->BSSID,
                                        i->ifinfo.InterfaceActive ? "Active" : "      ",
                                        i->ifinfo.IPv4Available ? "v4" : "  ",
                                        i->ifinfo.IPv4Available ? (mDNSv4Addr*)&i->ifa_v4addr : &zerov4Addr,
                                        i->ifinfo.IPv6Available ? "v6" : "  ",
                                        i->ifinfo.Advertise ? "⊙" : " ",
                                        i->ifinfo.McastTxRx ? "⇆" : " ",
                                        !(i->ifinfo.InterfaceActive && i->ifinfo.NetWake) ? " " : !sps[0] ? "☼" : "☀",
                                        &i->ifinfo.ip);

                                if (sps[0]) LogMsgNoIdent("  %13d %#s", SPSMetric(sps[0]->resrec.rdata->u.name.c), sps[0]->resrec.rdata->u.name.c);
                                if (sps[1]) LogMsgNoIdent("  %13d %#s", SPSMetric(sps[1]->resrec.rdata->u.name.c), sps[1]->resrec.rdata->u.name.c);
                                if (sps[2]) LogMsgNoIdent("  %13d %#s", SPSMetric(sps[2]->resrec.rdata->u.name.c), sps[2]->resrec.rdata->u.name.c);
                                }
                        }
                }

        LogMsgNoIdent("--------- DNS Servers ----------");
        if (!mDNSStorage.DNSServers) LogMsgNoIdent("<None>");
        else
                {
                for (s = mDNSStorage.DNSServers; s; s = s->next)
                        {
                        NetworkInterfaceInfoOSX *ifx = IfindexToInterfaceInfoOSX(&mDNSStorage, s->interface);
                        LogMsgNoIdent("DNS Server %##s %s%s%#a:%d %d %s %d %s",
                                s->domain.c, ifx ? ifx->ifinfo.ifname : "", ifx ? " " : "", &s->addr, mDNSVal16(s->port),
                                s->penaltyTime ? s->penaltyTime - mDNS_TimeNow(&mDNSStorage) : 0, s->scoped ? "Scoped" : "",
                                s->timeout,
                                s->teststate == DNSServer_Untested ? "(Untested)" :
                                s->teststate == DNSServer_Passed   ? ""           :
                                s->teststate == DNSServer_Failed   ? "(Failed)"   :
                                s->teststate == DNSServer_Disabled ? "(Disabled)" : "(Unknown state)");
                        }
                }

        LogMsgNoIdent("--------- Mcast Resolvers ----------");
        if (!mDNSStorage.McastResolvers) LogMsgNoIdent("<None>");
        else
                {
                for (mr = mDNSStorage.McastResolvers; mr; mr = mr->next)
                        LogMsgNoIdent("Mcast Resolver %##s timeout %u", mr->domain.c, mr->timeout);
                }

        mDNSs32 now = mDNS_TimeNow(&mDNSStorage);
        LogMsgNoIdent("Timenow 0x%08lX (%d)", (mDNSu32)now, now);

        LogMsg("----  END STATE LOG  ---- %s %s %d", mDNSResponderVersionString, OSXVers ? "OSXVers" : "iOSVers", OSXVers ? OSXVers : iOSVers);
        }

#ifndef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSlocal void SignalCallback(CFMachPortRef port, void *msg, CFIndex size, void *info)
        {
        (void)port;             // Unused
        (void)size;             // Unused
        (void)info;             // Unused
        mach_msg_header_t *msg_header = (mach_msg_header_t *)msg;
        mDNS *const m = &mDNSStorage;

        // We're running on the CFRunLoop (Mach port) thread, not the kqueue thread, so we need to grab the KQueueLock before proceeding
        KQueueLock(m);
        switch(msg_header->msgh_id)
                {
                case SIGHUP:    {
                                                mDNSu32 slot;
                                                CacheGroup *cg;
                                                CacheRecord *rr;
                                                LogMsg("SIGHUP: Purge cache");
                                                mDNS_Lock(m);
                                                FORALL_CACHERECORDS(slot, cg, rr) mDNS_PurgeCacheResourceRecord(m, rr);
                                                // Restart unicast and multicast queries
                                                mDNSCoreRestartQueries(m);
                                                mDNS_Unlock(m);
                                                } break;
                case SIGINT:
                case SIGTERM:   ExitCallback(msg_header->msgh_id); break;
                case SIGINFO:   INFOCallback(); break;
                case SIGUSR1:   mDNS_LoggingEnabled = mDNS_LoggingEnabled ? 0 : 1;
                                                LogMsg("SIGUSR1: Logging %s", mDNS_LoggingEnabled ? "Enabled" : "Disabled");
                                                WatchDogReportingThreshold = mDNS_LoggingEnabled ? 50 : 250;
                                                break;
                case SIGUSR2:   mDNS_PacketLoggingEnabled = mDNS_PacketLoggingEnabled ? 0 : 1;
                                                LogMsg("SIGUSR2: Packet Logging %s", mDNS_PacketLoggingEnabled ? "Enabled" : "Disabled");
                                                break;
                default: LogMsg("SignalCallback: Unknown signal %d", msg_header->msgh_id); break;
                }
        KQueueUnlock(m, "Unix Signal");
        }

// On 10.2 the MachServerName is DNSServiceDiscoveryServer
// On 10.3 and later, the MachServerName is com.apple.mDNSResponder
mDNSlocal kern_return_t mDNSDaemonInitialize(void)
        {
        mStatus            err;
        CFMachPortRef      s_port;
        CFRunLoopSourceRef s_rls;
        CFRunLoopSourceRef d_rls;

        // If launchd already created our Mach port for us, then use that, else we create a new one of our own
        if (m_port != MACH_PORT_NULL)
                s_port = CFMachPortCreateWithPort(NULL, m_port, DNSserverCallback, NULL, NULL);
        else
                {
                s_port = CFMachPortCreate(NULL, DNSserverCallback, NULL, NULL);
                m_port = CFMachPortGetPort(s_port);
                kern_return_t status = bootstrap_register(bootstrap_port, "com.apple.mDNSResponder", m_port);
        
                if (status)
                        {
                        if (status == 1103)
                                LogMsg("bootstrap_register() failed: A copy of the daemon is apparently already running");
                        else
                                LogMsg("bootstrap_register() failed: %d %X %s", status, status, mach_error_string(status));
                        return(status);
                        }
                }

        CFMachPortRef      d_port = CFMachPortCreate(NULL, ClientDeathCallback, NULL, NULL);

        err = mDNS_Init(&mDNSStorage, &PlatformStorage,
                rrcachestorage, RR_CACHE_SIZE,
                advertise,
                mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext);

        if (err) { LogMsg("Daemon start: mDNS_Init failed %d", err); return(err); }

        client_death_port = CFMachPortGetPort(d_port);

        s_rls  = CFMachPortCreateRunLoopSource(NULL, s_port, 0);
        CFRunLoopAddSource(PlatformStorage.CFRunLoop, s_rls, kCFRunLoopDefaultMode);
        CFRelease(s_rls);

        d_rls  = CFMachPortCreateRunLoopSource(NULL, d_port, 0);
        CFRunLoopAddSource(PlatformStorage.CFRunLoop, d_rls, kCFRunLoopDefaultMode);
        CFRelease(d_rls);

        CFMachPortRef      i_port = CFMachPortCreate(NULL, SignalCallback, NULL, NULL);
        CFRunLoopSourceRef i_rls  = CFMachPortCreateRunLoopSource(NULL, i_port, 0);
        signal_port       = CFMachPortGetPort(i_port);
        CFRunLoopAddSource(PlatformStorage.CFRunLoop, i_rls, kCFRunLoopDefaultMode);
        CFRelease(i_rls);

        if (mDNS_DebugMode) printf("Service registered with Mach Port %d\n", m_port);
        return(err);
        }

#else // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

// SignalDispatch is mostly just a copy/paste of entire code block from SignalCallback above.
// The common code should be a subroutine, or we end up having to fix bugs in two places all the time.
// The same applies to mDNSDaemonInitialize, much of which is just a copy/paste of chunks
// of code from above. Alternatively we could remove the duplicated source code by having
// single routines, with the few differing parts bracketed with "#ifndef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM"

mDNSlocal void SignalDispatch(dispatch_source_t source)
        {
        int sig = (int)dispatch_source_get_handle(source);
        mDNS *const m = &mDNSStorage;
        KQueueLock(m);
        switch(sig)
                {
                case SIGHUP:    {
                                                mDNSu32 slot;
                                                CacheGroup *cg;
                                                CacheRecord *rr;
                                                LogMsg("SIGHUP: Purge cache");
                                                mDNS_Lock(m);
                                                FORALL_CACHERECORDS(slot, cg, rr) mDNS_PurgeCacheResourceRecord(m, rr);
                                                // Restart unicast and multicast queries
                                                mDNSCoreRestartQueries(m);
                                                mDNS_Unlock(m);
                                                } break;
                case SIGINT:
                case SIGTERM:   ExitCallback(sig); break;
                case SIGINFO:   INFOCallback(); break;
                case SIGUSR1:   mDNS_LoggingEnabled = mDNS_LoggingEnabled ? 0 : 1;
                                                LogMsg("SIGUSR1: Logging %s", mDNS_LoggingEnabled ? "Enabled" : "Disabled");
                                                WatchDogReportingThreshold = mDNS_LoggingEnabled ? 50 : 250;
                                                break;
                case SIGUSR2:   mDNS_PacketLoggingEnabled = mDNS_PacketLoggingEnabled ? 0 : 1;
                                                LogMsg("SIGUSR2: Packet Logging %s", mDNS_PacketLoggingEnabled ? "Enabled" : "Disabled");
                                                break;
                default: LogMsg("SignalCallback: Unknown signal %d", sig); break;
                }
        KQueueUnlock(m, "Unix Signal");
        }

mDNSlocal void mDNSSetupSignal(dispatch_queue_t queue, int sig)
        {
        signal(sig, SIG_IGN);
        dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_SIGNAL, sig, 0, queue);

        if (source)
                {
                dispatch_source_set_event_handler(source, ^{SignalDispatch(source);});
                // Start processing signals
                dispatch_resume(source);
                }
        else
                {
                LogMsg("mDNSSetupSignal: Cannot setup signal %d", sig);
                }
        }

// On 10.2 the MachServerName is DNSServiceDiscoveryServer
// On 10.3 and later, the MachServerName is com.apple.mDNSResponder
mDNSlocal kern_return_t mDNSDaemonInitialize(void)
        {
        mStatus            err;
        CFMachPortRef      s_port;
        dispatch_source_t mach_source;
        dispatch_queue_t queue = dispatch_get_main_queue();

        // If launchd already created our Mach port for us, then use that, else we create a new one of our own
        if (m_port != MACH_PORT_NULL)
                s_port = CFMachPortCreateWithPort(NULL, m_port, DNSserverCallback, NULL, NULL);
        else
                {
                s_port = CFMachPortCreate(NULL, DNSserverCallback, NULL, NULL);
                m_port = CFMachPortGetPort(s_port);
                kern_return_t status = bootstrap_register(bootstrap_port, "com.apple.mDNSResponder", m_port);
        
                if (status)
                        {
                        if (status == 1103)
                                LogMsg("bootstrap_register() failed: A copy of the daemon is apparently already running");
                        else
                                LogMsg("bootstrap_register() failed: %d %X %s", status, status, mach_error_string(status));
                        return(status);
                        }
                }

        err = mDNS_Init(&mDNSStorage, &PlatformStorage,
                rrcachestorage, RR_CACHE_SIZE,
                advertise,
                mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext);

        if (err) { LogMsg("Daemon start: mDNS_Init failed %d", err); return(err); }

        mach_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_MACH_RECV, m_port, 0, queue);
        if (mach_source == mDNSNULL){LogMsg("mDNSDaemonInitialize: Error creating source for m_port"); return -1;}
        dispatch_source_set_event_handler(mach_source, ^{
                dispatch_mig_server(mach_source, sizeof(union __RequestUnion__DNSServiceDiscoveryReply_subsystem),
                DNSServiceDiscoveryRequest_server);
                });
        dispatch_resume(mach_source);

        mDNSSetupSignal(queue, SIGHUP);
        mDNSSetupSignal(queue, SIGINT);
        mDNSSetupSignal(queue, SIGTERM);
        mDNSSetupSignal(queue, SIGINFO);
        mDNSSetupSignal(queue, SIGUSR1);
        mDNSSetupSignal(queue, SIGUSR2);
        mDNSSetupSignal(queue, SIGHUP);

        // Create a custom handler for doing the housekeeping work. This is either triggered
        // by the timer or an event source
        PlatformStorage.custom = dispatch_source_create(DISPATCH_SOURCE_TYPE_DATA_ADD, 0, 0, queue);
        if (PlatformStorage.custom == mDNSNULL){LogMsg("mDNSDaemonInitialize: Error creating custom source"); return -1;}
        dispatch_source_set_event_handler(PlatformStorage.custom, ^{PrepareForIdle(&mDNSStorage);});
        dispatch_resume(PlatformStorage.custom);

        // Create a timer source to trigger housekeeping work. The houskeeping work itself
        // is done in the custom handler that we set below.
        
        PlatformStorage.timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
        if (PlatformStorage.timer == mDNSNULL){LogMsg("mDNSDaemonInitialize: Error creating timer source"); return -1;}

        // As the API does not support one shot timers, we pass zero for the interval. In the custom handler, we
        // always reset the time to the new time computed. In effect, we ignore the interval
        dispatch_source_set_timer(PlatformStorage.timer, DISPATCH_TIME_NOW, 1000ull * 1000000000, 0);
        dispatch_source_set_event_handler(PlatformStorage.timer, ^{
                dispatch_source_merge_data(PlatformStorage.custom, 1);
                });
        dispatch_resume(PlatformStorage.timer);

        LogMsg("DaemonIntialize done successfully");

        if (mDNS_DebugMode) printf("Service registered with Mach Port %d\n", m_port);
        return(err);
        }

#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSlocal mDNSs32 mDNSDaemonIdle(mDNS *const m)
        {
        mDNSs32 now = mDNS_TimeNow(m);

        // 1. If we need to set domain secrets, do so before handling the network change
        // Detailed reason:
        // BTMM domains listed in DynStore Setup:/Network/BackToMyMac are added to the registration domains list,
        // and we need to setup the associated AutoTunnel DomainAuthInfo entries before that happens.
        if (m->p->KeyChainTimer && now - m->p->KeyChainTimer >= 0)
                {
                m->p->KeyChainTimer = 0;
                mDNS_Lock(m);
                SetDomainSecrets(m);
                mDNS_Unlock(m);
                }

        // 2. If we have network change events to handle, do them before calling mDNS_Execute()
        // Detailed reason:
        // mDNSMacOSXNetworkChanged() currently closes and re-opens its sockets. If there are received packets waiting, they are lost.
        // mDNS_Execute() generates packets, including multicasts that are looped back to ourself.
        // If we call mDNS_Execute() first, and generate packets, and then call mDNSMacOSXNetworkChanged() immediately afterwards
        // we then systematically lose our own looped-back packets.
        if (m->p->NetworkChanged && now - m->p->NetworkChanged >= 0) mDNSMacOSXNetworkChanged(m);

        if (m->p->RequestReSleep && now - m->p->RequestReSleep >= 0) { m->p->RequestReSleep = 0; mDNSPowerRequest(0, 0); }

        // 3. Call mDNS_Execute() to let mDNSCore do what it needs to do
        mDNSs32 nextevent = mDNS_Execute(m);

        if (m->p->NetworkChanged)
                if (nextevent - m->p->NetworkChanged > 0)
                        nextevent = m->p->NetworkChanged;

        if (m->p->KeyChainTimer)
                if (nextevent - m->p->KeyChainTimer > 0)
                        nextevent = m->p->KeyChainTimer;

        if (m->p->RequestReSleep)
                if (nextevent - m->p->RequestReSleep > 0)
                        nextevent = m->p->RequestReSleep;

        // 4. Deliver any waiting browse messages to clients
        DNSServiceBrowser *b = DNSServiceBrowserList;

        while (b)
                {
                // Note: Need to advance b to the next element BEFORE we call DeliverInstance(), because in the
                // event that the client Mach queue overflows, DeliverInstance() will call AbortBlockedClient()
                // and that will cause the DNSServiceBrowser object's memory to be freed before it returns
                DNSServiceBrowser *x = b;
                b = b->next;
                if (x->results)                 // Try to deliver the list of results
                        {
                        while (x->results)
                                {
                                DNSServiceBrowserResult *const r = x->results;
                                domainlabel name;
                                domainname type, domain;
                                DeconstructServiceName(&r->result, &name, &type, &domain);      // Don't need to check result; already validated in FoundInstance()
                                char cname[MAX_DOMAIN_LABEL+1];                 // Unescaped name: up to 63 bytes plus C-string terminating NULL.
                                char ctype[MAX_ESCAPED_DOMAIN_NAME];
                                char cdom [MAX_ESCAPED_DOMAIN_NAME];
                                ConvertDomainLabelToCString_unescaped(&name, cname);
                                ConvertDomainNameToCString(&type, ctype);
                                ConvertDomainNameToCString(&domain, cdom);
                                DNSServiceDiscoveryReplyFlags flags = (r->next) ? DNSServiceDiscoverReplyFlagsMoreComing : 0;
                                kern_return_t status = DNSServiceBrowserReply_rpc(x->ClientMachPort, r->resultType, cname, ctype, cdom, flags, 1);
                                // If we failed to send the mach message, try again in one second
                                if (status == MACH_SEND_TIMED_OUT)
                                        {
                                        if (nextevent - now > mDNSPlatformOneSecond)
                                                nextevent = now + mDNSPlatformOneSecond;
                                        break;
                                        }
                                else
                                        {
                                        x->lastsuccess = now;
                                        x->results = x->results->next;
                                        freeL("DNSServiceBrowserResult", r);
                                        }
                                }
                        // If this client hasn't read a single message in the last 60 seconds, abort it
                        if (now - x->lastsuccess >= 60 * mDNSPlatformOneSecond)
                                AbortBlockedClient(x->ClientMachPort, "browse", x);
                        }
                }

        DNSServiceResolver *l;
        for (l = DNSServiceResolverList; l; l=l->next)
                if (l->ReportTime && now - l->ReportTime >= 0)
                        {
                        l->ReportTime = 0;
                        LogMsgNoIdent("Client application bug: DNSServiceResolver(%##s) active for over two minutes. "
                                "This places considerable burden on the network.", l->i.name.c);
                        }

        if (m->p->NotifyUser)
                {
                if (m->p->NotifyUser - now < 0)
                        {
                        if (!SameDomainLabelCS(m->p->usernicelabel.c, m->nicelabel.c))
                                {
                                LogMsg("Name Conflict: Updated Computer Name from \"%#s\" to \"%#s\"", m->p->usernicelabel.c, m->nicelabel.c);
                                mDNSPreferencesSetNames(m, kmDNSComputerName, &m->p->usernicelabel, &m->nicelabel);
                                m->p->usernicelabel = m->nicelabel;
                                }
                        if (!SameDomainLabelCS(m->p->userhostlabel.c, m->hostlabel.c))
                                {
                                LogMsg("Name Conflict: Updated Local Hostname from \"%#s.local\" to \"%#s.local\"", m->p->userhostlabel.c, m->hostlabel.c);
                                mDNSPreferencesSetNames(m, kmDNSLocalHostName, &m->p->userhostlabel, &m->hostlabel);
                                m->p->HostNameConflict = 0;     // Clear our indicator, now name change has been successful
                                m->p->userhostlabel = m->hostlabel;
                                }
                        m->p->NotifyUser = 0;
                        }
                else
                        if (nextevent - m->p->NotifyUser > 0)
                                nextevent = m->p->NotifyUser;
                }

        return(nextevent);
        }

// Right now we consider *ALL* of our DHCP leases
// It might make sense to be a bit more selective and only consider the leases on interfaces
// (a) that are capable and enabled for wake-on-LAN, and
// (b) where we have found (and successfully registered with) a Sleep Proxy
// If we can't be woken for traffic on a given interface, then why keep waking to renew its lease?
mDNSlocal mDNSu32 DHCPWakeTime(void)
        {
        mDNSu32 e = 24 * 3600;          // Maximum maintenance wake interval is 24 hours
        const CFAbsoluteTime now = CFAbsoluteTimeGetCurrent();
        if (!now) LogMsg("DHCPWakeTime: CFAbsoluteTimeGetCurrent failed");
        else
                {
                const SCPreferencesRef prefs = SCPreferencesCreate(NULL, CFSTR("mDNSResponder:DHCPWakeTime"), NULL);
                if (!prefs) LogMsg("DHCPWakeTime: SCPreferencesCreate failed");
                else
                        {
                        const SCNetworkSetRef currentset = SCNetworkSetCopyCurrent(prefs);
                        if (!currentset) LogMsg("DHCPWakeTime: SCNetworkSetCopyCurrent failed");
                        else
                                {
                                const CFArrayRef services = SCNetworkSetCopyServices(currentset);
                                if (!services) LogMsg("DHCPWakeTime: SCNetworkSetCopyServices failed");
                                else
                                        {
                                        int i;
                                        for (i = 0; i < CFArrayGetCount(services); i++)
                                                {
                                                const SCNetworkServiceRef service = CFArrayGetValueAtIndex(services, i);
                                                if (!service) LogMsg("DHCPWakeTime: CFArrayGetValueAtIndex %d failed", i);
                                                else
                                                        {
                                                        const CFStringRef serviceid = SCNetworkServiceGetServiceID(service);
                                                        if (!serviceid) LogMsg("DHCPWakeTime: SCNetworkServiceGetServiceID %d failed", i);
                                                        else
                                                                {
                                                                // Note: It's normal for this call to return NULL, for interfaces not using DHCP
                                                                const CFDictionaryRef dhcp = SCDynamicStoreCopyDHCPInfo(NULL, serviceid);
                                                                if (dhcp)
                                                                        {
                                                                        const CFDateRef start = DHCPInfoGetLeaseStartTime(dhcp);
                                                                        const CFDataRef lease = DHCPInfoGetOptionData(dhcp, 51);        // Option 51 = IP Address Lease Time
                                                                        if (!start || !lease || CFDataGetLength(lease) < 4)
                                                                                LogMsg("DHCPWakeTime: SCDynamicStoreCopyDHCPInfo index %d failed "
                                                                                        "CFDateRef start %p CFDataRef lease %p CFDataGetLength(lease) %d",
                                                                                        i, start, lease, lease ? CFDataGetLength(lease) : 0);
                                                                        else
                                                                                {
                                                                                const UInt8 *d = CFDataGetBytePtr(lease);
                                                                                if (!d) LogMsg("DHCPWakeTime: CFDataGetBytePtr %d failed", i);
                                                                                else
                                                                                        {
                                                                                        const mDNSu32 elapsed   = now - CFDateGetAbsoluteTime(start);
                                                                                        const mDNSu32 lifetime  = (mDNSs32) ((mDNSs32)d[0] << 24 | (mDNSs32)d[1] << 16 | (mDNSs32)d[2] << 8 | d[3]);
                                                                                        const mDNSu32 remaining = lifetime - elapsed;
                                                                                        const mDNSu32 wake      = remaining > 60 ? remaining - remaining/10 : 54;       // Wake at 90% of the lease time
                                                                                        LogSPS("DHCP Address Lease Elapsed %6u Lifetime %6u Remaining %6u Wake %6u", elapsed, lifetime, remaining, wake);
                                                                                        if (e > wake) e = wake;
                                                                                        }
                                                                                }
                                                                        CFRelease(dhcp);
                                                                        }
                                                                }
                                                        }
                                                }
                                        CFRelease(services);
                                        }
                                CFRelease(currentset);
                                }
                        CFRelease(prefs);
                        }
                }
        return(e);
        }

// We deliberately schedule our wakeup for halfway between when we'd *like* it and when we *need* it.
// For example, if our DHCP lease expires in two hours, we'll typically renew it at the halfway point, after one hour.
// If we scheduled our wakeup for the one-hour renewal time, that might be just seconds from now, and sleeping
// for a few seconds and then waking again is silly and annoying.
// If we scheduled our wakeup for the two-hour expiry time, and we were slow to wake, we might lose our lease.
// Scheduling our wakeup for halfway in between -- 90 minutes -- avoids short wakeups while still
// allowing us an adequate safety margin to renew our lease before we lose it.

mDNSlocal mDNSBool AllowSleepNow(mDNS *const m, mDNSs32 now)
        {
        mDNSBool ready = mDNSCoreReadyForSleep(m, now);
        if (m->SleepState && !ready && now - m->SleepLimit < 0) return(mDNSfalse);

        m->p->WakeAtUTC = 0;
        int result = kIOReturnSuccess;
        CFDictionaryRef opts = NULL;

        // If the sleep request was cancelled, and we're no longer planning to sleep, don't need to
        // do the stuff below, but we *DO* still need to acknowledge the sleep message we received.
        if (!m->SleepState)
                LogMsg("AllowSleepNow: Sleep request was canceled with %d ticks remaining", m->SleepLimit - now);
        else
                {
                if (!m->SystemWakeOnLANEnabled || !mDNSCoreHaveAdvertisedMulticastServices(m))
                        LogSPS("AllowSleepNow: Not scheduling wakeup: SystemWakeOnLAN %s enabled; %s advertised services",
                                m->SystemWakeOnLANEnabled                  ? "is" : "not",
                                mDNSCoreHaveAdvertisedMulticastServices(m) ? "have" : "no");
                else
                        {
                        mDNSs32 dhcp = DHCPWakeTime();
                        LogSPS("ComputeWakeTime: DHCP Wake %d", dhcp);
                        mDNSs32 interval = mDNSCoreIntervalToNextWake(m, now) / mDNSPlatformOneSecond;
                        if (interval > dhcp) interval = dhcp;
        
                        // If we're not ready to sleep (failed to register with Sleep Proxy, maybe because of
                        // transient network problem) then schedule a wakeup in one hour to try again. Otherwise,
                        // a single SPS failure could result in a remote machine falling permanently asleep, requiring
                        // someone to go to the machine in person to wake it up again, which would be unacceptable.
                        if (!ready && interval > 3600) interval = 3600;
        
                        //interval = 48; // For testing
        
#ifdef kIOPMAcknowledgmentOptionSystemCapabilityRequirements
                        if (m->p->IOPMConnection)       // If lightweight-wake capability is available, use that
                                {
                                const CFDateRef WakeDate = CFDateCreate(NULL, CFAbsoluteTimeGetCurrent() + interval);
                                if (!WakeDate) LogMsg("ScheduleNextWake: CFDateCreate failed");
                                else
                                        {
                                        const mDNSs32     reqs         = kIOPMSystemPowerStateCapabilityNetwork;
                                        const CFNumberRef Requirements = CFNumberCreate(NULL, kCFNumberSInt32Type, &reqs);
                                        if (!Requirements) LogMsg("ScheduleNextWake: CFNumberCreate failed");
                                        else
                                                {
                                                const void *OptionKeys[2] = { CFSTR("WakeDate"), CFSTR("Requirements") };
                                                const void *OptionVals[2] = {        WakeDate,          Requirements   };
                                                opts = CFDictionaryCreate(NULL, (void*)OptionKeys, (void*)OptionVals, 2, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
                                                if (!opts) LogMsg("ScheduleNextWake: CFDictionaryCreate failed");
                                                CFRelease(Requirements);
                                                }
                                        CFRelease(WakeDate);
                                        }
                                LogSPS("AllowSleepNow: Will request lightweight wakeup in %d seconds", interval);
                                }
                        else                                            // else schedule the wakeup using the old API instead to
#endif
                                {
                                // If we wake within +/- 30 seconds of our requested time we'll assume the system woke for us,
                                // so we should put it back to sleep. To avoid frustrating the user, we always request at least
                                // 60 seconds sleep, so if they immediately re-wake the system within seconds of it going to sleep,
                                // we then shouldn't hit our 30-second window, and we won't attempt to re-sleep the machine.
                                if (interval < 60) interval = 60;
        
                                result = mDNSPowerRequest(1, interval);
        
                                if (result == kIOReturnNotReady)
                                        {
                                        int r;
                                        LogMsg("AllowSleepNow: Requested wakeup in %d seconds unsuccessful; retrying with longer intervals", interval);
                                        // IOPMSchedulePowerEvent fails with kIOReturnNotReady (-536870184/0xe00002d8) if the
                                        // requested wake time is "too soon", but there's no API to find out what constitutes
                                        // "too soon" on any given OS/hardware combination, so if we get kIOReturnNotReady
                                        // we just have to iterate with successively longer intervals until it doesn't fail.
                                        // We preserve the value of "result" because if our original power request was deemed "too soon"
                                        // for the machine to get to sleep and wake back up again, we attempt to cancel the sleep request,
                                        // since the implication is that the system won't manage to be awake again at the time we need it.
                                        do
                                                {
                                                interval += (interval < 20) ? 1 : ((interval+3) / 4);
                                                r = mDNSPowerRequest(1, interval);
                                                }
                                        while (r == kIOReturnNotReady);
                                        if (r) LogMsg("AllowSleepNow: Requested wakeup in %d seconds unsuccessful: %d %X", interval, r, r);
                                        else LogSPS("AllowSleepNow: Requested later wakeup in %d seconds; will also attempt IOCancelPowerChange", interval);
                                        }
                                else
                                        {
                                        if (result) LogMsg("AllowSleepNow: Requested wakeup in %d seconds unsuccessful: %d %X", interval, result, result);
                                        else LogSPS("AllowSleepNow: Requested wakeup in %d seconds", interval);
                                        }
                                m->p->WakeAtUTC = mDNSPlatformUTC() + interval;
                                }
                        }
        
                m->SleepState = SleepState_Sleeping;
                // We used to clear our interface list to empty state here before going to sleep.
                // The applications that try to connect to an external server during maintenance wakes, saw
                // DNS resolution errors as we don't have any interfaces (most queries use SuppressUnusable
                // flag). Thus, we don't remove our interfaces anymore on sleep.
                }

        LogSPS("AllowSleepNow: %s(%lX) %s at %ld (%d ticks remaining)",
#if !TARGET_OS_EMBEDDED && defined(kIOPMAcknowledgmentOptionSystemCapabilityRequirements)
                (m->p->IOPMConnection) ? "IOPMConnectionAcknowledgeEventWithOptions" :
#endif
                (result == kIOReturnSuccess) ? "IOAllowPowerChange" : "IOCancelPowerChange",
                m->p->SleepCookie, ready ? "ready for sleep" : "giving up", now, m->SleepLimit - now);

        m->SleepLimit = 0;      // Don't clear m->SleepLimit until after we've logged it above

#if !TARGET_OS_EMBEDDED && defined(kIOPMAcknowledgmentOptionSystemCapabilityRequirements)
        if (m->p->IOPMConnection) IOPMConnectionAcknowledgeEventWithOptions(m->p->IOPMConnection, m->p->SleepCookie, opts);
        else
#endif
        if (result == kIOReturnSuccess) IOAllowPowerChange (m->p->PowerConnection, m->p->SleepCookie);
        else                            IOCancelPowerChange(m->p->PowerConnection, m->p->SleepCookie);

        if (opts) CFRelease(opts);
        return(mDNStrue);
        }

#ifdef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSexport void TriggerEventCompletion()
        {
        debugf("TriggerEventCompletion: Merge data");
        dispatch_source_merge_data(PlatformStorage.custom, 1);
        }

mDNSlocal void PrepareForIdle(void *m_param)
        {
        mDNS            *m = m_param;
        int64_t                 time_offset;
        dispatch_time_t dtime;

        const int multiplier = 1000000000 / mDNSPlatformOneSecond;
        
        // This is the main work loop:
        // (1) First we give mDNSCore a chance to finish off any of its deferred work and calculate the next sleep time
        // (2) Then we make sure we've delivered all waiting browse messages to our clients
        // (3) Then we sleep for the time requested by mDNSCore, or until the next event, whichever is sooner

        debugf("PrepareForIdle: called");
        // Run mDNS_Execute to find out the time we next need to wake up
        mDNSs32 start          = mDNSPlatformRawTime();
        mDNSs32 nextTimerEvent = udsserver_idle(mDNSDaemonIdle(m));
        mDNSs32 end            = mDNSPlatformRawTime();
        if (end - start >= WatchDogReportingThreshold)
                LogInfo("CustomSourceHandler:WARNING: Idle task took %dms to complete", end - start);

        mDNSs32 now = mDNS_TimeNow(m);

        if (m->ShutdownTime)
                {
                if (mDNSStorage.ResourceRecords)
                        {
                        LogInfo("Cannot exit yet; Resource Record still exists: %s", ARDisplayString(m, mDNSStorage.ResourceRecords));
                        if (mDNS_LoggingEnabled) usleep(10000);         // Sleep 10ms so that we don't flood syslog with too many messages
                        }
                if (mDNS_ExitNow(m, now))
                        {
                        if (!mDNSStorage.ResourceRecords)
                                safe_vproc_transaction_end();
                        LogInfo("IdleLoop: mDNS_FinalExit");
                        mDNS_FinalExit(&mDNSStorage);
                        usleep(1000);           // Little 1ms pause before exiting, so we don't lose our final syslog messages
                        exit(0);
                        }
                if (nextTimerEvent - m->ShutdownTime >= 0)
                        nextTimerEvent = m->ShutdownTime;
                }

        if (m->SleepLimit)
                if (!AllowSleepNow(m, now))
                        if (nextTimerEvent - m->SleepLimit >= 0)
                                nextTimerEvent = m->SleepLimit;

        // Convert absolute wakeup time to a relative time from now
        mDNSs32 ticks = nextTimerEvent - now;
        if (ticks < 1) ticks = 1;
        
        static mDNSs32 RepeatedBusy = 0;        // Debugging sanity check, to guard against CPU spins
        if (ticks > 1)
                RepeatedBusy = 0;
        else
                {
                ticks = 1;
                if (++RepeatedBusy >= mDNSPlatformOneSecond) { ShowTaskSchedulingError(&mDNSStorage); RepeatedBusy = 0; }
                }

        time_offset = ((mDNSu32)ticks / mDNSPlatformOneSecond) * 1000000000 + (ticks % mDNSPlatformOneSecond) * multiplier;
        dtime = dispatch_time(DISPATCH_TIME_NOW, time_offset);
        dispatch_source_set_timer(PlatformStorage.timer, dtime, 1000ull*1000000000, 0);
        debugf("PrepareForIdle: scheduling timer with ticks %d", ticks);
        return;
        }

#else // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSlocal void KQWokenFlushBytes(int fd, __unused short filter, __unused void *context)
        {
        // Read all of the bytes so we won't wake again.
        char    buffer[100];
        while (recv(fd, buffer, sizeof(buffer), MSG_DONTWAIT) > 0) continue;
        }

mDNSlocal void * KQueueLoop(void *m_param)
        {
        mDNS            *m = m_param;
        int             numevents = 0;

#if USE_SELECT_WITH_KQUEUEFD
        fd_set          readfds;
        FD_ZERO(&readfds);
        const int multiplier = 1000000    / mDNSPlatformOneSecond;
#else
        const int multiplier = 1000000000 / mDNSPlatformOneSecond;
#endif
        
        pthread_mutex_lock(&PlatformStorage.BigMutex);
        LogInfo("Starting time value 0x%08lX (%ld)", (mDNSu32)mDNSStorage.timenow_last, mDNSStorage.timenow_last);
        
        // This is the main work loop:
        // (1) First we give mDNSCore a chance to finish off any of its deferred work and calculate the next sleep time
        // (2) Then we make sure we've delivered all waiting browse messages to our clients
        // (3) Then we sleep for the time requested by mDNSCore, or until the next event, whichever is sooner
        // (4) On wakeup we first process *all* events
        // (5) then when no more events remain, we go back to (1) to finish off any deferred work and do it all again
        for ( ; ; )
                {
                #define kEventsToReadAtOnce 1
                struct kevent new_events[kEventsToReadAtOnce];

                // Run mDNS_Execute to find out the time we next need to wake up
                mDNSs32 start          = mDNSPlatformRawTime();
                mDNSs32 nextTimerEvent = udsserver_idle(mDNSDaemonIdle(m));
                mDNSs32 end            = mDNSPlatformRawTime();
                if (end - start >= WatchDogReportingThreshold)
                        LogInfo("WARNING: Idle task took %dms to complete", end - start);

                mDNSs32 now = mDNS_TimeNow(m);

                if (m->ShutdownTime)
                        {
                        if (mDNSStorage.ResourceRecords)
                                {
                                AuthRecord *rr;
                                for (rr = mDNSStorage.ResourceRecords; rr; rr=rr->next)
                                        {
                                        LogInfo("Cannot exit yet; Resource Record still exists: %s", ARDisplayString(m, rr));
                                        if (mDNS_LoggingEnabled) usleep(10000);         // Sleep 10ms so that we don't flood syslog with too many messages
                                        }
                                }
                        if (mDNS_ExitNow(m, now))
                                {
                                if (!mDNSStorage.ResourceRecords)
                                        safe_vproc_transaction_end();
                                LogInfo("mDNS_FinalExit");
                                mDNS_FinalExit(&mDNSStorage);
                                usleep(1000);           // Little 1ms pause before exiting, so we don't lose our final syslog messages
                                exit(0);
                                }
                        if (nextTimerEvent - m->ShutdownTime >= 0)
                                nextTimerEvent = m->ShutdownTime;
                        }

                if (m->SleepLimit)
                        if (!AllowSleepNow(m, now))
                                if (nextTimerEvent - m->SleepLimit >= 0)
                                        nextTimerEvent = m->SleepLimit;

                // Convert absolute wakeup time to a relative time from now
                mDNSs32 ticks = nextTimerEvent - now;
                if (ticks < 1) ticks = 1;
                
                static mDNSs32 RepeatedBusy = 0;        // Debugging sanity check, to guard against CPU spins
                if (ticks > 1)
                        RepeatedBusy = 0;
                else
                        {
                        ticks = 1;
                        if (++RepeatedBusy >= mDNSPlatformOneSecond) { ShowTaskSchedulingError(&mDNSStorage); RepeatedBusy = 0; }
                        }

                verbosedebugf("KQueueLoop: Handled %d events; now sleeping for %d ticks", numevents, ticks);
                numevents = 0;

                // Release the lock, and sleep until:
                // 1. Something interesting happens like a packet arriving, or
                // 2. The other thread writes a byte to WakeKQueueLoopFD to poke us and make us wake up, or
                // 3. The timeout expires
                pthread_mutex_unlock(&PlatformStorage.BigMutex);

#if USE_SELECT_WITH_KQUEUEFD
                struct timeval timeout;
                timeout.tv_sec = ticks / mDNSPlatformOneSecond;
                timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * multiplier;
                FD_SET(KQueueFD, &readfds);
                if (select(KQueueFD+1, &readfds, NULL, NULL, &timeout) < 0)
                        { LogMsg("select(%d) failed errno %d (%s)", KQueueFD, errno, strerror(errno)); sleep(1); }
#else
                struct timespec timeout;
                timeout.tv_sec = ticks / mDNSPlatformOneSecond;
                timeout.tv_nsec = (ticks % mDNSPlatformOneSecond) * multiplier;
                // In my opinion, you ought to be able to call kevent() with nevents set to zero,
                // and have it work similarly to the way it does with nevents non-zero --
                // i.e. it waits until either an event happens or the timeout expires, and then wakes up.
                // In fact, what happens if you do this is that it just returns immediately. So, we have
                // to pass nevents set to one, and then we just ignore the event it gives back to us. -- SC
                if (kevent(KQueueFD, NULL, 0, new_events, 1, &timeout) < 0)
                        { LogMsg("kevent(%d) failed errno %d (%s)", KQueueFD, errno, strerror(errno)); sleep(1); }
#endif

                pthread_mutex_lock(&PlatformStorage.BigMutex);
                // We have to ignore the event we may have been told about above, because that
                // was done without holding the lock, and between the time we woke up and the
                // time we reclaimed the lock the other thread could have done something that
                // makes the event no longer valid. Now we have the lock, we call kevent again
                // and this time we can safely process the events it tells us about.

                static const struct timespec zero_timeout = { 0, 0 };
                int events_found;
                while ((events_found = kevent(KQueueFD, NULL, 0, new_events, kEventsToReadAtOnce, &zero_timeout)) != 0)
                        {
                        if (events_found > kEventsToReadAtOnce || (events_found < 0 && errno != EINTR))
                                {
                                // Not sure what to do here, our kqueue has failed us - this isn't ideal
                                LogMsg("ERROR: KQueueLoop - kevent failed errno %d (%s)", errno, strerror(errno));
                                exit(errno);
                                }

                        numevents += events_found;

                        int i;
                        for (i = 0; i < events_found; i++)
                                {
                                const KQueueEntry *const kqentry = new_events[i].udata;
                                mDNSs32 stime = mDNSPlatformRawTime();
                                const char *const KQtask = kqentry->KQtask;     // Grab a copy in case KQcallback deletes the task
                                kqentry->KQcallback(new_events[i].ident, new_events[i].filter, kqentry->KQcontext);
                                mDNSs32 etime = mDNSPlatformRawTime();
                                if (etime - stime >= WatchDogReportingThreshold)
                                        LogInfo("WARNING: %s took %dms to complete", KQtask, etime - stime);
                                }
                        }
                }
        
        return NULL;
        }

#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

mDNSlocal void LaunchdCheckin(void)
        {
        launch_data_t msg  = launch_data_new_string(LAUNCH_KEY_CHECKIN);
        launch_data_t resp = launch_msg(msg);
        launch_data_free(msg);
        if (!resp) { LogMsg("launch_msg returned NULL"); return; }

        if (launch_data_get_type(resp) == LAUNCH_DATA_ERRNO)
                {
                int err = launch_data_get_errno(resp);
                // When running on Tiger with "ServiceIPC = false", we get "err == EACCES" to tell us there's no launchdata to fetch
                if (err != EACCES) LogMsg("launch_msg returned %d", err);
                else LogInfo("Launchd provided no launchdata; will open Mach port and Unix Domain Socket explicitly...", err);
                }
        else
                {
                launch_data_t skts = launch_data_dict_lookup(resp, LAUNCH_JOBKEY_SOCKETS);
                if (!skts) LogMsg("launch_data_dict_lookup LAUNCH_JOBKEY_SOCKETS returned NULL");
                else
                        {
                        launch_data_t skt = launch_data_dict_lookup(skts, "Listeners");
                        if (!skt) LogMsg("launch_data_dict_lookup Listeners returned NULL");
                        else
                                {
                                launchd_fds_count = launch_data_array_get_count(skt);
                                if (launchd_fds_count == 0) LogMsg("launch_data_array_get_count(skt) returned 0");
                                else
                                        {
                                        launchd_fds = mallocL("LaunchdCheckin", sizeof(dnssd_sock_t) * launchd_fds_count);
                                        if (!launchd_fds) LogMsg("LaunchdCheckin: malloc failed");
                                        else
                                                {
                                                size_t i;
                                                for(i = 0; i < launchd_fds_count; i++)
                                                        {                                               
                                                        launch_data_t s = launch_data_array_get_index(skt, i);
                                                        if (!s)
                                                                {
                                                                launchd_fds[i] = dnssd_InvalidSocket;
                                                                LogMsg("launch_data_array_get_index(skt, %d) returned NULL", i);
                                                                }
                                                        else
                                                                {
                                                                launchd_fds[i] = launch_data_get_fd(s);
                                                                LogInfo("Launchd Unix Domain Socket [%d]: %d", i, launchd_fds[i]);
                                                                }
                                                        }
                                                }
                                        // In some early versions of 10.4.x, the permissions on the UDS were not set correctly, so we fix them here
                                        chmod(MDNS_UDS_SERVERPATH, S_IRUSR|S_IWUSR | S_IRGRP|S_IWGRP | S_IROTH|S_IWOTH);
                                        }
                                }
                        }

                launch_data_t ports = launch_data_dict_lookup(resp, "MachServices");
                if (!ports) LogMsg("launch_data_dict_lookup MachServices returned NULL");
                else
                        {
                        launch_data_t p = launch_data_dict_lookup(ports, "com.apple.mDNSResponder");
                        if (!p) LogInfo("launch_data_dict_lookup(ports, \"com.apple.mDNSResponder\") returned NULL");
                        else
                                {
                                m_port = launch_data_get_fd(p);
                                LogInfo("Launchd Mach Port: %d", m_port);
                                if (m_port == ~0U) m_port = MACH_PORT_NULL;
                                }
                        }
                }
        launch_data_free(resp);
        }

mDNSlocal void DropPrivileges(void)
        {
        static const char login[] = "_mdnsresponder";
        struct passwd *pwd = getpwnam(login);
        if (NULL == pwd)
                LogMsg("Could not find account name \"%s\". Running as root.", login);
        else
                {
                uid_t uid = pwd->pw_uid;
                gid_t gid = pwd->pw_gid;

                LogMsg("Started as root. Switching to userid \"%s\".", login);

                if (unlink(MDNS_UDS_SERVERPATH) < 0 && errno != ENOENT) LogMsg("DropPrivileges: Could not unlink \"%s\": (%d) %s", MDNS_UDS_SERVERPATH, errno, strerror(errno));
                else
                        {
                        static char path[] = "/var/run/mdns/mDNSResponder";
                        char *p = strrchr(path, '/');
                        *p = '\0';
                        if (mkdir(path, 0755) < 0 && errno != EEXIST) LogMsg("DropPrivileges: Could not create directory \"%s\": (%d) %s", path, errno, strerror(errno));
                        else if (chown(path, uid, gid) < 0) LogMsg("DropPrivileges: Could not chown directory \"%s\": (%d) %s", path, errno, strerror(errno));
                        else
                                {
                                *p = '/';
                                if (unlink(path) < 0 && errno != ENOENT) LogMsg("DropPrivileges: Could not unlink \"%s\": (%d) %s", path, errno, strerror(errno));
                                else if (symlink(path, MDNS_UDS_SERVERPATH) < 0) LogMsg("DropPrivileges: Could not symlink \"%s\" -> \"%s\": (%d) %s", MDNS_UDS_SERVERPATH, path, errno, strerror(errno));
                                else LogInfo("DropPrivileges: Created subdirectory and symlink");
                                }
                        }

                if (0 != initgroups(login, gid)) LogMsg("initgroups(\"%s\", %lu) failed.  Continuing.", login,        (unsigned long)gid);
                if (0 != setgid(gid))            LogMsg("setgid(%lu) failed.  Continuing with group %lu privileges.", (unsigned long)getegid());
                if (0 != setuid(uid))            LogMsg("setuid(%lu) failed. Continuing as root after all.",          (unsigned long)uid);
                }
        }

extern int sandbox_init(const char *profile, uint64_t flags, char **errorbuf) __attribute__((weak_import));

mDNSexport int main(int argc, char **argv)
        {
        int i;
        kern_return_t status;

        mDNSMacOSXSystemBuildNumber(NULL);
        LogMsg("%s starting %s %d", mDNSResponderVersionString, OSXVers ? "OSXVers" : "iOSVers", OSXVers ? OSXVers : iOSVers);
        
#if 0
        LogMsg("CacheRecord %d", sizeof(CacheRecord));
        LogMsg("CacheGroup  %d", sizeof(CacheGroup));
        LogMsg("ResourceRecord  %d", sizeof(ResourceRecord));
        LogMsg("RData_small     %d", sizeof(RData_small));

        LogMsg("sizeof(CacheEntity) %d", sizeof(CacheEntity));
        LogMsg("RR_CACHE_SIZE       %d", RR_CACHE_SIZE);
        LogMsg("block usage         %d", sizeof(CacheEntity) * RR_CACHE_SIZE);
        LogMsg("block wastage       %d", 16*1024 - sizeof(CacheEntity) * RR_CACHE_SIZE);
#endif

        safe_vproc_transaction_begin();

        if (0 == geteuid()) DropPrivileges();

        for (i=1; i<argc; i++)
                {
                if (!strcasecmp(argv[i], "-d"                        )) mDNS_DebugMode            = mDNStrue;
                if (!strcasecmp(argv[i], "-launchd"                  )) started_via_launchdaemon  = mDNStrue;
                if (!strcasecmp(argv[i], "-launchdaemon"             )) started_via_launchdaemon  = mDNStrue;
                if (!strcasecmp(argv[i], "-NoMulticastAdvertisements")) advertise                 = mDNS_Init_DontAdvertiseLocalAddresses;
                if (!strcasecmp(argv[i], "-DisableSleepProxyClient"  )) DisableSleepProxyClient   = mDNStrue;
                if (!strcasecmp(argv[i], "-DebugLogging"             )) mDNS_LoggingEnabled       = mDNStrue;
                if (!strcasecmp(argv[i], "-UnicastPacketLogging"     )) mDNS_PacketLoggingEnabled = mDNStrue;
                if (!strcasecmp(argv[i], "-OfferSleepProxyService"   ))
                        OfferSleepProxyService = (i+1 < argc && mDNSIsDigit(argv[i+1][0]) && mDNSIsDigit(argv[i+1][1]) && argv[i+1][2]==0) ? atoi(argv[++i]) : 100;
                if (!strcasecmp(argv[i], "-UseInternalSleepProxy"    ))
                        UseInternalSleepProxy = (i+1<argc && mDNSIsDigit(argv[i+1][0]) && argv[i+1][1]==0) ? atoi(argv[++i]) : 1;
                if (!strcasecmp(argv[i], "-StrictUnicastOrdering"    )) StrictUnicastOrdering     = mDNStrue;
                if (!strcasecmp(argv[i], "-DisableInboundRelay"      )) DisableInboundRelayConnection = mDNStrue;
                if (!strcasecmp(argv[i], "-AlwaysAppendSearchDomains")) AlwaysAppendSearchDomains = mDNStrue;
                }
        
        // Note that mDNSPlatformInit will set DivertMulticastAdvertisements in the mDNS structure
        if (!advertise) LogMsg("Administratively prohibiting multicast advertisements");

#ifndef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

        signal(SIGHUP,  HandleSIG);             // (Debugging) Purge the cache to check for cache handling bugs
        signal(SIGINT,  HandleSIG);             // Ctrl-C: Detach from Mach BootstrapService and exit cleanly
        signal(SIGPIPE, SIG_IGN  );             // Don't want SIGPIPE signals -- we'll handle EPIPE errors directly
        signal(SIGTERM, HandleSIG);             // Machine shutting down: Detach from and exit cleanly like Ctrl-C
        signal(SIGINFO, HandleSIG);             // (Debugging) Write state snapshot to syslog
        signal(SIGUSR1, HandleSIG);             // (Debugging) Enable Logging
        signal(SIGUSR2, HandleSIG);             // (Debugging) Enable Packet Logging

#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

        mDNSStorage.p = &PlatformStorage;       // Make sure mDNSStorage.p is set up, because validatelists uses it
        LaunchdCheckin();

        // Register the server with mach_init for automatic restart only during normal (non-debug) mode
    if (!mDNS_DebugMode && !started_via_launchdaemon)
        {
        registerBootstrapService();
        if (!restarting_via_mach_init) exit(0); // mach_init will restart us immediately as a daemon
                int fd = open(_PATH_DEVNULL, O_RDWR, 0);
                if (fd < 0) LogMsg("open(_PATH_DEVNULL, O_RDWR, 0) failed errno %d (%s)", errno, strerror(errno));
                else
                        {
                        // Avoid unnecessarily duplicating a file descriptor to itself
                        if (fd != STDIN_FILENO)  if (dup2(fd, STDIN_FILENO)  < 0) LogMsg("dup2(fd, STDIN_FILENO)  failed errno %d (%s)", errno, strerror(errno));
                        if (fd != STDOUT_FILENO) if (dup2(fd, STDOUT_FILENO) < 0) LogMsg("dup2(fd, STDOUT_FILENO) failed errno %d (%s)", errno, strerror(errno));
                        if (fd != STDERR_FILENO) if (dup2(fd, STDERR_FILENO) < 0) LogMsg("dup2(fd, STDERR_FILENO) failed errno %d (%s)", errno, strerror(errno));
                        if (fd != STDIN_FILENO && fd != STDOUT_FILENO && fd != STDERR_FILENO) (void)close(fd);
                        }
                }

#ifndef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

        // Create the kqueue, mutex and thread to support KQSockets
        KQueueFD = kqueue();
        if (KQueueFD == -1) { LogMsg("kqueue() failed errno %d (%s)", errno, strerror(errno)); status = errno; goto exit; }
        
        i = pthread_mutex_init(&PlatformStorage.BigMutex, NULL);
        if (i == -1) { LogMsg("pthread_mutex_init() failed errno %d (%s)", errno, strerror(errno)); status = errno; goto exit; }
        
        int fdpair[2] = {0, 0};
        i = socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair);
        if (i == -1) { LogMsg("socketpair() failed errno %d (%s)", errno, strerror(errno)); status = errno; goto exit; }

        // Socket pair returned us two identical sockets connected to each other
        // We will use the first socket to send the second socket. The second socket
        // will be added to the kqueue so it will wake when data is sent.
        static const KQueueEntry wakeKQEntry = { KQWokenFlushBytes, NULL, "kqueue wakeup after CFRunLoop event" };

        PlatformStorage.WakeKQueueLoopFD = fdpair[0];
        KQueueSet(fdpair[1], EV_ADD, EVFILT_READ, &wakeKQEntry);

#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
        
        // Invoke sandbox profile /usr/share/sandbox/mDNSResponder.sb
#if MDNS_NO_SANDBOX
        LogMsg("Note: Compiled without Apple Sandbox support");
#else MDNS_NO_SANDBOX
        if (!sandbox_init)
                LogMsg("Note: Running without Apple Sandbox support (not available on this OS)");
        else
                {
                char *sandbox_msg;
                uint64_t sandbox_flags = SANDBOX_NAMED;

                // On Desktop, the sandbox profile always exists under /usr/share/sandbox, no need to
                // check it. stat results in calls to opendirectoryd and to avoid deadlocks with
                // opendirectoryd early on, we avoid this call.
#if TARGET_OS_EMBEDDED
                struct stat s;
                if (stat("/usr/share/sandbox/mDNSResponder.sb", &s) == 0)
                        {
                        sandbox_flags = SANDBOX_NAMED_EXTERNAL;
                        LogInfo("Will load Sandbox profile from filesystem");
                        }
#endif

                int sandbox_err = sandbox_init("mDNSResponder", sandbox_flags, &sandbox_msg);
                if (sandbox_err) { LogMsg("WARNING: sandbox_init error %s", sandbox_msg); sandbox_free_error(sandbox_msg); }
                else LogInfo("Now running under Apple Sandbox restrictions");
                }
#endif MDNS_NO_SANDBOX

        status = mDNSDaemonInitialize();
        if (status) { LogMsg("Daemon start: mDNSDaemonInitialize failed"); goto exit; }

        status = udsserver_init(launchd_fds, launchd_fds_count);
        if (status) { LogMsg("Daemon start: udsserver_init failed"); goto exit; }

        mDNSMacOSXNetworkChanged(&mDNSStorage);

#ifdef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
        LogInfo("Daemon Start: Using LibDispatch");
        // CFRunLoopRun runs both CFRunLoop sources and dispatch sources
        CFRunLoopRun();
#else // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
        // Start the kqueue thread
        pthread_t KQueueThread;
        i = pthread_create(&KQueueThread, NULL, KQueueLoop, &mDNSStorage);
        if (i == -1) { LogMsg("pthread_create() failed errno %d (%s)", errno, strerror(errno)); status = errno; goto exit; }
        if (status == 0)
                {
                CFRunLoopRun();
                LogMsg("ERROR: CFRunLoopRun Exiting.");
                mDNS_Close(&mDNSStorage);
                }
#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

        LogMsg("%s exiting", mDNSResponderVersionString);

exit:
        if (!mDNS_DebugMode && !started_via_launchdaemon) destroyBootstrapService();
        return(status);
        }

// uds_daemon.c support routines /////////////////////////////////////////////

// Arrange things so that when data appears on fd, callback is called with context
mDNSexport mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void *context, void **platform_data)
        {
        KQSocketEventSource **p = &gEventSources;
        (void) platform_data;
        while (*p && (*p)->fd != fd) p = &(*p)->next;
        if (*p) { LogMsg("udsSupportAddFDToEventLoop: ERROR fd %d already has EventLoop source entry", fd); return mStatus_AlreadyRegistered; }

        KQSocketEventSource *newSource = (KQSocketEventSource*) mallocL("KQSocketEventSource", sizeof *newSource);
        if (!newSource) return mStatus_NoMemoryErr;

        newSource->next           = mDNSNULL;
        newSource->fd             = fd;
        newSource->kqs.KQcallback = callback;
        newSource->kqs.KQcontext  = context;
        newSource->kqs.KQtask     = "UDS client";
#ifdef MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM
        newSource->kqs.readSource  = mDNSNULL;
        newSource->kqs.writeSource = mDNSNULL;
        newSource->kqs.fdClosed    = mDNSfalse;
#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

        if (KQueueSet(fd, EV_ADD, EVFILT_READ, &newSource->kqs) == 0)
                {
                *p = newSource;
                return mStatus_NoError;
                }

        LogMsg("KQueueSet failed for fd %d errno %d (%s)", fd, errno, strerror(errno));
        freeL("KQSocketEventSource", newSource);
        return mStatus_BadParamErr;
        }

int udsSupportReadFD(dnssd_sock_t fd, char *buf, int len, int flags, void *platform_data)
        {
        (void) platform_data;
        return recv(fd, buf, len, flags);
        }

mDNSexport mStatus udsSupportRemoveFDFromEventLoop(int fd, void *platform_data)         // Note: This also CLOSES the file descriptor
        {
        KQSocketEventSource **p = &gEventSources;
        (void) platform_data;
        while (*p && (*p)->fd != fd) p = &(*p)->next;
        if (*p)
                {
                KQSocketEventSource *s = *p;
                *p = (*p)->next;
                // We don't have to explicitly do a kqueue EV_DELETE here because closing the fd
                // causes the kernel to automatically remove any associated kevents
                mDNSPlatformCloseFD(&s->kqs, s->fd);
                freeL("KQSocketEventSource", s);
                return mStatus_NoError;
                }
        LogMsg("udsSupportRemoveFDFromEventLoop: ERROR fd %d not found in EventLoop source list", fd);
        return mStatus_NoSuchNameErr;
        }

#if _BUILDING_XCODE_PROJECT_
// If mDNSResponder crashes, then this string will be magically included in the automatically-generated crash log
const char *__crashreporter_info__ = mDNSResponderVersionString;
asm(".desc ___crashreporter_info__, 0x10");
#endif

// For convenience when using the "strings" command, this is the last thing in the file
// The "@(#) " pattern is a special prefix the "what" command looks for
mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder " STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")";