mDNSResponder-258.13.tar.gz

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

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2003-2004, Apple Computer, Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1.  Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of its
 *     contributors may be used to endorse or promote products derived from this
 *     software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <errno.h>
#include <stdlib.h>

#include "dnssd_ipc.h"

#if defined(_WIN32)

        #define _SSIZE_T
        #include <CommonServices.h>
        #include <DebugServices.h>
        #include <winsock2.h>
        #include <ws2tcpip.h>
        #include <windows.h>
        #include <stdarg.h>
        
        #define sockaddr_mdns sockaddr_in
        #define AF_MDNS AF_INET
        
        // Disable warning: "'type cast' : from data pointer 'void *' to function pointer"
        #pragma warning(disable:4055)
        
        // Disable warning: "nonstandard extension, function/data pointer conversion in expression"
        #pragma warning(disable:4152)
        
        extern BOOL IsSystemServiceDisabled();
        
        #define sleep(X) Sleep((X) * 1000)
        
        static int g_initWinsock = 0;
        #define LOG_WARNING kDebugLevelWarning
        static void syslog( int priority, const char * message, ...)
                {
                va_list args;
                int len;
                char * buffer;
                DWORD err = WSAGetLastError();
                (void) priority;
                va_start( args, message );
                len = _vscprintf( message, args ) + 1;
                buffer = malloc( len * sizeof(char) );
                if ( buffer ) { vsprintf( buffer, message, args ); OutputDebugString( buffer ); free( buffer ); }
                WSASetLastError( err );
                }
#else

        #include <sys/fcntl.h>          // For O_RDWR etc.
        #include <sys/time.h>
        #include <sys/socket.h>
        #include <syslog.h>
        
        #define sockaddr_mdns sockaddr_un
        #define AF_MDNS AF_LOCAL

#endif

// <rdar://problem/4096913> Specifies how many times we'll try and connect to the server.

#define DNSSD_CLIENT_MAXTRIES 4

// Uncomment the line below to use the old error return mechanism of creating a temporary named socket (e.g. in /var/tmp)
//#define USE_NAMED_ERROR_RETURN_SOCKET 1

#ifndef CTL_PATH_PREFIX
#define CTL_PATH_PREFIX "/var/tmp/dnssd_result_socket."
#endif

typedef struct
        {
        ipc_msg_hdr         ipc_hdr;
        DNSServiceFlags     cb_flags;
        uint32_t            cb_interface;
        DNSServiceErrorType cb_err;
        } CallbackHeader;

typedef struct _DNSServiceRef_t DNSServiceOp;
typedef struct _DNSRecordRef_t DNSRecord;

// client stub callback to process message from server and deliver results to client application
typedef void (*ProcessReplyFn)(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *msg, const char *const end);

#define ValidatorBits 0x12345678
#define DNSServiceRefValid(X) (dnssd_SocketValid((X)->sockfd) && (((X)->sockfd ^ (X)->validator) == ValidatorBits))

// When using kDNSServiceFlagsShareConnection, there is one primary _DNSServiceOp_t, and zero or more subordinates
// For the primary, the 'next' field points to the first subordinate, and its 'next' field points to the next, and so on.
// For the primary, the 'primary' field is NULL; for subordinates the 'primary' field points back to the associated primary
//
// _DNS_SD_LIBDISPATCH is defined where libdispatch/GCD is available. This does not mean that the application will use the
// DNSServiceSetDispatchQueue API. Hence any new code guarded with _DNS_SD_LIBDISPATCH should still be backwards compatible.
struct _DNSServiceRef_t
        {
        DNSServiceOp     *next;                         // For shared connection
        DNSServiceOp     *primary;                      // For shared connection
        dnssd_sock_t      sockfd;                       // Connected socket between client and daemon
        dnssd_sock_t      validator;            // Used to detect memory corruption, double disposals, etc.
        client_context_t  uid;                          // For shared connection requests, each subordinate DNSServiceRef has its own ID,
                                                                                // unique within the scope of the same shared parent DNSServiceRef
        uint32_t          op;                           // request_op_t or reply_op_t
        uint32_t          max_index;            // Largest assigned record index - 0 if no additional records registered
        uint32_t          logcounter;           // Counter used to control number of syslog messages we write
        int              *moreptr;                      // Set while DNSServiceProcessResult working on this particular DNSServiceRef
        ProcessReplyFn    ProcessReply;         // Function pointer to the code to handle received messages
        void             *AppCallback;          // Client callback function and context
        void             *AppContext;
        DNSRecord        *rec;
#if _DNS_SD_LIBDISPATCH
        dispatch_source_t disp_source;
        dispatch_queue_t  disp_queue;
#endif
        };

struct _DNSRecordRef_t
        {
        DNSRecord               *recnext;
        void *AppContext;
        DNSServiceRegisterRecordReply AppCallback;
        DNSRecordRef recref;
        uint32_t record_index;  // index is unique to the ServiceDiscoveryRef
        DNSServiceOp *sdr;
        };

// Write len bytes. Return 0 on success, -1 on error
static int write_all(dnssd_sock_t sd, char *buf, size_t len)
        {
        // Don't use "MSG_WAITALL"; it returns "Invalid argument" on some Linux versions; use an explicit while() loop instead.
        //if (send(sd, buf, len, MSG_WAITALL) != len) return -1;
        while (len)
                {
                ssize_t num_written = send(sd, buf, (long)len, 0);
                if (num_written < 0 || (size_t)num_written > len)
                        {
                        // Should never happen. If it does, it indicates some OS bug,
                        // or that the mDNSResponder daemon crashed (which should never happen).
                        #if !defined(__ppc__) && defined(SO_ISDEFUNCT)
                        int defunct;
                        socklen_t dlen = sizeof (defunct);
                        if (getsockopt(sd, SOL_SOCKET, SO_ISDEFUNCT, &defunct, &dlen) < 0)
                                syslog(LOG_WARNING, "dnssd_clientstub write_all: SO_ISDEFUNCT failed %d %s", dnssd_errno, dnssd_strerror(dnssd_errno));
                        if (!defunct)
                                syslog(LOG_WARNING, "dnssd_clientstub write_all(%d) failed %ld/%ld %d %s", sd,
                                        (long)num_written, (long)len,
                                        (num_written < 0) ? dnssd_errno                 : 0,
                                        (num_written < 0) ? dnssd_strerror(dnssd_errno) : "");
                        else
                                syslog(LOG_INFO, "dnssd_clientstub write_all(%d) DEFUNCT", sd);
                        #else
                        syslog(LOG_WARNING, "dnssd_clientstub write_all(%d) failed %ld/%ld %d %s", sd,
                                (long)num_written, (long)len,
                                (num_written < 0) ? dnssd_errno                 : 0,
                                (num_written < 0) ? dnssd_strerror(dnssd_errno) : "");
                        #endif
                        return -1;
                        }
                buf += num_written;
                len -= num_written;
                }
        return 0;
        }

enum { read_all_success = 0, read_all_fail = -1, read_all_wouldblock = -2 };

// Read len bytes. Return 0 on success, read_all_fail on error, or read_all_wouldblock for
static int read_all(dnssd_sock_t sd, char *buf, int len)
        {
        // Don't use "MSG_WAITALL"; it returns "Invalid argument" on some Linux versions; use an explicit while() loop instead.
        //if (recv(sd, buf, len, MSG_WAITALL) != len) return -1;

        while (len)
                {
                ssize_t num_read = recv(sd, buf, len, 0);
                if ((num_read == 0) || (num_read < 0) || (num_read > len))
                        {
                        int printWarn = 0;
                        int defunct = 0;
                        // Should never happen. If it does, it indicates some OS bug,
                        // or that the mDNSResponder daemon crashed (which should never happen).
#if defined(WIN32)
                        // <rdar://problem/7481776> Suppress logs for "A non-blocking socket operation
                        //                          could not be completed immediately"
                        if (WSAGetLastError() != WSAEWOULDBLOCK)
                                printWarn = 1;
#endif
#if !defined(__ppc__) && defined(SO_ISDEFUNCT)
                        {
                        socklen_t dlen = sizeof (defunct);
                        if (getsockopt(sd, SOL_SOCKET, SO_ISDEFUNCT, &defunct, &dlen) < 0)
                                syslog(LOG_WARNING, "dnssd_clientstub read_all: SO_ISDEFUNCT failed %d %s", dnssd_errno, dnssd_strerror(dnssd_errno));
                        }
                        if (!defunct)
                                printWarn = 1;
#endif
                        if (printWarn)
                                syslog(LOG_WARNING, "dnssd_clientstub read_all(%d) failed %ld/%ld %d %s", sd,
                                        (long)num_read, (long)len,
                                        (num_read < 0) ? dnssd_errno                 : 0,
                                        (num_read < 0) ? dnssd_strerror(dnssd_errno) : "");
                        else if (defunct)
                                syslog(LOG_INFO, "dnssd_clientstub read_all(%d) DEFUNCT", sd);
                        return (num_read < 0 && dnssd_errno == dnssd_EWOULDBLOCK) ? read_all_wouldblock : read_all_fail;
                        }
                buf += num_read;
                len -= num_read;
                }
        return read_all_success;
        }

// Returns 1 if more bytes remain to be read on socket descriptor sd, 0 otherwise
static int more_bytes(dnssd_sock_t sd)
        {
        struct timeval tv = { 0, 0 };
        fd_set readfds;
        fd_set *fs;
        int ret;

        if (sd < FD_SETSIZE)
                {
                fs = &readfds;
                FD_ZERO(fs);
                }
        else 
                {
                // Compute the number of integers needed for storing "sd". Internally fd_set is stored
                // as an array of ints with one bit for each fd and hence we need to compute
                // the number of ints needed rather than the number of bytes. If "sd" is 32, we need
                // two ints and not just one.
                int nfdbits = sizeof (int) * 8;
                int nints = (sd/nfdbits) + 1;
                fs = (fd_set *)calloc(nints, sizeof(int));
                if (fs == NULL) { syslog(LOG_WARNING, "dnssd_clientstub more_bytes: malloc failed"); return 0; }
                }
        FD_SET(sd, fs);
        ret = select((int)sd+1, fs, (fd_set*)NULL, (fd_set*)NULL, &tv);
        if (fs != &readfds) free(fs);
        return (ret > 0);
        }

/* create_hdr
 *
 * allocate and initialize an ipc message header. Value of len should initially be the
 * length of the data, and is set to the value of the data plus the header. data_start
 * is set to point to the beginning of the data section. SeparateReturnSocket should be
 * non-zero for calls that can't receive an immediate error return value on their primary
 * socket, and therefore require a separate return path for the error code result.
 * if zero, the path to a control socket is appended at the beginning of the message buffer.
 * data_start is set past this string.
 */
static ipc_msg_hdr *create_hdr(uint32_t op, size_t *len, char **data_start, int SeparateReturnSocket, DNSServiceOp *ref)
        {
        char *msg = NULL;
        ipc_msg_hdr *hdr;
        int datalen;
#if !defined(USE_TCP_LOOPBACK)
        char ctrl_path[64] = "";        // "/var/tmp/dnssd_result_socket.xxxxxxxxxx-xxx-xxxxxx"
#endif

        if (SeparateReturnSocket)
                {
#if defined(USE_TCP_LOOPBACK)
                *len += 2;  // Allocate space for two-byte port number
#elif defined(USE_NAMED_ERROR_RETURN_SOCKET)
                struct timeval tv;
                if (gettimeofday(&tv, NULL) < 0)
                        { syslog(LOG_WARNING, "dnssd_clientstub create_hdr: gettimeofday failed %d %s", dnssd_errno, dnssd_strerror(dnssd_errno)); return NULL; }
                sprintf(ctrl_path, "%s%d-%.3lx-%.6lu", CTL_PATH_PREFIX, (int)getpid(),
                        (unsigned long)(tv.tv_sec & 0xFFF), (unsigned long)(tv.tv_usec));
                *len += strlen(ctrl_path) + 1;
#else
                *len += 1;              // Allocate space for single zero byte (empty C string)
#endif
                }

        datalen = (int) *len;
        *len += sizeof(ipc_msg_hdr);

        // Write message to buffer
        msg = malloc(*len);
        if (!msg) { syslog(LOG_WARNING, "dnssd_clientstub create_hdr: malloc failed"); return NULL; }

        memset(msg, 0, *len);
        hdr = (ipc_msg_hdr *)msg;
        hdr->version                = VERSION;
        hdr->datalen                = datalen;
        hdr->ipc_flags              = 0;
        hdr->op                     = op;
        hdr->client_context         = ref->uid;
        hdr->reg_index              = 0;
        *data_start = msg + sizeof(ipc_msg_hdr);
#if defined(USE_TCP_LOOPBACK)
        // Put dummy data in for the port, since we don't know what it is yet.
        // The data will get filled in before we send the message. This happens in deliver_request().
        if (SeparateReturnSocket) put_uint16(0, data_start);
#else
        if (SeparateReturnSocket) put_string(ctrl_path, data_start);
#endif
        return hdr;
        }

static void FreeDNSRecords(DNSServiceOp *sdRef)
        {
        DNSRecord *rec = sdRef->rec;
        while (rec)
                {
                DNSRecord *next = rec->recnext;
                free(rec);
                rec = next;
                }
        }

static void FreeDNSServiceOp(DNSServiceOp *x)
        {
        // We don't use our DNSServiceRefValid macro here because if we're cleaning up after a socket() call failed
        // then sockfd could legitimately contain a failing value (e.g. dnssd_InvalidSocket)
        if ((x->sockfd ^ x->validator) != ValidatorBits)
                syslog(LOG_WARNING, "dnssd_clientstub attempt to dispose invalid DNSServiceRef %p %08X %08X", x, x->sockfd, x->validator);
        else
                {
                x->next         = NULL;
                x->primary      = NULL;
                x->sockfd       = dnssd_InvalidSocket;
                x->validator    = 0xDDDDDDDD;
                x->op           = request_op_none;
                x->max_index    = 0;
                x->logcounter   = 0;
                x->moreptr      = NULL;
                x->ProcessReply = NULL;
                x->AppCallback  = NULL;
                x->AppContext   = NULL;
                x->rec          = NULL;
#if _DNS_SD_LIBDISPATCH
                if (x->disp_source)     dispatch_release(x->disp_source);
                x->disp_source  = NULL;
                x->disp_queue   = NULL;
#endif
                // DNSRecords may have been added to subordinate sdRef e.g., DNSServiceRegister/DNSServiceAddRecord
                // or on the main sdRef e.g., DNSServiceCreateConnection/DNSServiveRegisterRecord. DNSRecords may have
                // been freed if the application called DNSRemoveRecord
                FreeDNSRecords(x);
                free(x);
                }
        }

// Return a connected service ref (deallocate with DNSServiceRefDeallocate)
static DNSServiceErrorType ConnectToServer(DNSServiceRef *ref, DNSServiceFlags flags, uint32_t op, ProcessReplyFn ProcessReply, void *AppCallback, void *AppContext)
        {
        #if APPLE_OSX_mDNSResponder
        int NumTries = DNSSD_CLIENT_MAXTRIES;
        #else
        int NumTries = 0;
        #endif

        dnssd_sockaddr_t saddr;
        DNSServiceOp *sdr;

        if (!ref) { syslog(LOG_WARNING, "dnssd_clientstub DNSService operation with NULL DNSServiceRef"); return kDNSServiceErr_BadParam; }

        if (flags & kDNSServiceFlagsShareConnection)
                {
                if (!*ref)
                        {
                        syslog(LOG_WARNING, "dnssd_clientstub kDNSServiceFlagsShareConnection used with NULL DNSServiceRef");
                        return kDNSServiceErr_BadParam;
                        }
                if (!DNSServiceRefValid(*ref) || (*ref)->op != connection_request || (*ref)->primary)
                        {
                        syslog(LOG_WARNING, "dnssd_clientstub kDNSServiceFlagsShareConnection used with invalid DNSServiceRef %p %08X %08X",
                                (*ref), (*ref)->sockfd, (*ref)->validator);
                        *ref = NULL;
                        return kDNSServiceErr_BadReference;
                        }
                }

        #if defined(_WIN32)
        if (!g_initWinsock)
                {
                WSADATA wsaData;
                g_initWinsock = 1;
                if (WSAStartup(MAKEWORD(2,2), &wsaData) != 0) { *ref = NULL; return kDNSServiceErr_ServiceNotRunning; }
                }
        // <rdar://problem/4096913> If the system service is disabled, we only want to try to connect once
        if (IsSystemServiceDisabled()) NumTries = DNSSD_CLIENT_MAXTRIES;
        #endif

        sdr = malloc(sizeof(DNSServiceOp));
        if (!sdr) { syslog(LOG_WARNING, "dnssd_clientstub ConnectToServer: malloc failed"); *ref = NULL; return kDNSServiceErr_NoMemory; }
        sdr->next          = NULL;
        sdr->primary       = NULL;
        sdr->sockfd        = dnssd_InvalidSocket;
        sdr->validator     = sdr->sockfd ^ ValidatorBits;
        sdr->op            = op;
        sdr->max_index     = 0;
        sdr->logcounter    = 0;
        sdr->moreptr       = NULL;
        sdr->uid.u32[0]    = 0;
        sdr->uid.u32[1]    = 0;
        sdr->ProcessReply  = ProcessReply;
        sdr->AppCallback   = AppCallback;
        sdr->AppContext    = AppContext;
        sdr->rec           = NULL;
#if _DNS_SD_LIBDISPATCH
        sdr->disp_source   = NULL;
        sdr->disp_queue    = NULL;
#endif

        if (flags & kDNSServiceFlagsShareConnection)
                {
                DNSServiceOp **p = &(*ref)->next;               // Append ourselves to end of primary's list
                while (*p) p = &(*p)->next;
                *p = sdr;
                // Preincrement counter before we use it -- it helps with debugging if we know the all-zeroes ID should never appear
                if (++(*ref)->uid.u32[0] == 0) ++(*ref)->uid.u32[1];    // In parent DNSServiceOp increment UID counter
                sdr->primary    = *ref;                                 // Set our primary pointer
                sdr->sockfd     = (*ref)->sockfd;               // Inherit primary's socket
                sdr->validator  = (*ref)->validator;
                sdr->uid        = (*ref)->uid;
                //printf("ConnectToServer sharing socket %d\n", sdr->sockfd);
                }
        else
                {
                #ifdef SO_NOSIGPIPE
                const unsigned long optval = 1;
                #endif
                *ref = NULL;
                sdr->sockfd    = socket(AF_DNSSD, SOCK_STREAM, 0);
                sdr->validator = sdr->sockfd ^ ValidatorBits;
                if (!dnssd_SocketValid(sdr->sockfd))
                        {
                        syslog(LOG_WARNING, "dnssd_clientstub ConnectToServer: socket failed %d %s", dnssd_errno, dnssd_strerror(dnssd_errno));
                        FreeDNSServiceOp(sdr);
                        return kDNSServiceErr_NoMemory;
                        }
                #ifdef SO_NOSIGPIPE
                // Some environments (e.g. OS X) support turning off SIGPIPE for a socket
                if (setsockopt(sdr->sockfd, SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval)) < 0)
                        syslog(LOG_WARNING, "dnssd_clientstub ConnectToServer: SO_NOSIGPIPE failed %d %s", dnssd_errno, dnssd_strerror(dnssd_errno));
                #endif
                #if defined(USE_TCP_LOOPBACK)
                saddr.sin_family      = AF_INET;
                saddr.sin_addr.s_addr = inet_addr(MDNS_TCP_SERVERADDR);
                saddr.sin_port        = htons(MDNS_TCP_SERVERPORT);
                #else
                saddr.sun_family      = AF_LOCAL;
                strcpy(saddr.sun_path, MDNS_UDS_SERVERPATH);
                #if !defined(__ppc__) && defined(SO_DEFUNCTOK)
                {
                int defunct = 1;
                if (setsockopt(sdr->sockfd, SOL_SOCKET, SO_DEFUNCTOK, &defunct, sizeof(defunct)) < 0)
                        syslog(LOG_WARNING, "dnssd_clientstub ConnectToServer: SO_DEFUNCTOK failed %d %s", dnssd_errno, dnssd_strerror(dnssd_errno));
                }
                #endif  
                #endif
        
                while (1)
                        {
                        int err = connect(sdr->sockfd, (struct sockaddr *) &saddr, sizeof(saddr));
                        if (!err) break; // If we succeeded, return sdr
                        // If we failed, then it may be because the daemon is still launching.
                        // This can happen for processes that launch early in the boot process, while the
                        // daemon is still coming up. Rather than fail here, we'll wait a bit and try again.
                        // If, after four seconds, we still can't connect to the daemon,
                        // then we give up and return a failure code.
                        if (++NumTries < DNSSD_CLIENT_MAXTRIES) sleep(1); // Sleep a bit, then try again
                        else { dnssd_close(sdr->sockfd); FreeDNSServiceOp(sdr); return kDNSServiceErr_ServiceNotRunning; }
                        }
                //printf("ConnectToServer opened socket %d\n", sdr->sockfd);
                }

        *ref = sdr;
        return kDNSServiceErr_NoError;
        }

#define deliver_request_bailout(MSG) \
        do { syslog(LOG_WARNING, "dnssd_clientstub deliver_request: %s failed %d (%s)", (MSG), dnssd_errno, dnssd_strerror(dnssd_errno)); goto cleanup; } while(0)

static DNSServiceErrorType deliver_request(ipc_msg_hdr *hdr, DNSServiceOp *sdr)
        {
        uint32_t datalen = hdr->datalen;        // We take a copy here because we're going to convert hdr->datalen to network byte order
        #if defined(USE_TCP_LOOPBACK) || defined(USE_NAMED_ERROR_RETURN_SOCKET)
        char *const data = (char *)hdr + sizeof(ipc_msg_hdr);
        #endif
        dnssd_sock_t listenfd = dnssd_InvalidSocket, errsd = dnssd_InvalidSocket;
        DNSServiceErrorType err = kDNSServiceErr_Unknown;       // Default for the "goto cleanup" cases
        int MakeSeparateReturnSocket = 0;

        // Note: need to check hdr->op, not sdr->op.
        // hdr->op contains the code for the specific operation we're currently doing, whereas sdr->op
        // contains the original parent DNSServiceOp (e.g. for an add_record_request, hdr->op will be
        // add_record_request but the parent sdr->op will be connection_request or reg_service_request)
        if (sdr->primary ||
                hdr->op == reg_record_request || hdr->op == add_record_request || hdr->op == update_record_request || hdr->op == remove_record_request)
                MakeSeparateReturnSocket = 1;

        if (!DNSServiceRefValid(sdr))
                {
                syslog(LOG_WARNING, "dnssd_clientstub deliver_request: invalid DNSServiceRef %p %08X %08X", sdr, sdr->sockfd, sdr->validator);
                return kDNSServiceErr_BadReference;
                }

        if (!hdr) { syslog(LOG_WARNING, "dnssd_clientstub deliver_request: !hdr"); return kDNSServiceErr_Unknown; }

        if (MakeSeparateReturnSocket)
                {
                #if defined(USE_TCP_LOOPBACK)
                        {
                        union { uint16_t s; u_char b[2]; } port;
                        dnssd_sockaddr_t caddr;
                        dnssd_socklen_t len = (dnssd_socklen_t) sizeof(caddr);
                        listenfd = socket(AF_DNSSD, SOCK_STREAM, 0);
                        if (!dnssd_SocketValid(listenfd)) deliver_request_bailout("TCP socket");

                        caddr.sin_family      = AF_INET;
                        caddr.sin_port        = 0;
                        caddr.sin_addr.s_addr = inet_addr(MDNS_TCP_SERVERADDR);
                        if (bind(listenfd, (struct sockaddr*) &caddr, sizeof(caddr)) < 0) deliver_request_bailout("TCP bind");
                        if (getsockname(listenfd, (struct sockaddr*) &caddr, &len)   < 0) deliver_request_bailout("TCP getsockname");
                        if (listen(listenfd, 1)                                      < 0) deliver_request_bailout("TCP listen");
                        port.s = caddr.sin_port;
                        data[0] = port.b[0];  // don't switch the byte order, as the
                        data[1] = port.b[1];  // daemon expects it in network byte order
                        }
                #elif defined(USE_NAMED_ERROR_RETURN_SOCKET)
                        {
                        mode_t mask;
                        int bindresult;
                        dnssd_sockaddr_t caddr;
                        listenfd = socket(AF_DNSSD, SOCK_STREAM, 0);
                        if (!dnssd_SocketValid(listenfd)) deliver_request_bailout("USE_NAMED_ERROR_RETURN_SOCKET socket");

                        caddr.sun_family = AF_LOCAL;
                        // According to Stevens (section 3.2), there is no portable way to
                        // determine whether sa_len is defined on a particular platform.
                        #ifndef NOT_HAVE_SA_LEN
                        caddr.sun_len = sizeof(struct sockaddr_un);
                        #endif
                        strcpy(caddr.sun_path, data);
                        mask = umask(0);
                        bindresult = bind(listenfd, (struct sockaddr *)&caddr, sizeof(caddr));
                        umask(mask);
                        if (bindresult          < 0) deliver_request_bailout("USE_NAMED_ERROR_RETURN_SOCKET bind");
                        if (listen(listenfd, 1) < 0) deliver_request_bailout("USE_NAMED_ERROR_RETURN_SOCKET listen");
                        }
                #else
                        {
                        dnssd_sock_t sp[2];
                        if (socketpair(AF_DNSSD, SOCK_STREAM, 0, sp) < 0) deliver_request_bailout("socketpair");
                        else
                                {
                                errsd    = sp[0];       // We'll read our four-byte error code from sp[0]
                                listenfd = sp[1];       // We'll send sp[1] to the daemon
                                #if !defined(__ppc__) && defined(SO_DEFUNCTOK)
                                {
                                int defunct = 1;
                                if (setsockopt(errsd, SOL_SOCKET, SO_DEFUNCTOK, &defunct, sizeof(defunct)) < 0)
                                        syslog(LOG_WARNING, "dnssd_clientstub ConnectToServer: SO_DEFUNCTOK failed %d %s", dnssd_errno, dnssd_strerror(dnssd_errno));
                                }
                                #endif  
                                }
                        }
                #endif
                }

#if !defined(USE_TCP_LOOPBACK) && !defined(USE_NAMED_ERROR_RETURN_SOCKET)
        // If we're going to make a separate error return socket, and pass it to the daemon
        // using sendmsg, then we'll hold back one data byte to go with it.
        // On some versions of Unix (including Leopard) sending a control message without
        // any associated data does not work reliably -- e.g. one particular issue we ran
        // into is that if the receiving program is in a kqueue loop waiting to be notified
        // of the received message, it doesn't get woken up when the control message arrives.
        if (MakeSeparateReturnSocket || sdr->op == send_bpf) datalen--;         // Okay to use sdr->op when checking for op == send_bpf
#endif

        // At this point, our listening socket is set up and waiting, if necessary, for the daemon to connect back to
        ConvertHeaderBytes(hdr);
        //syslog(LOG_WARNING, "dnssd_clientstub deliver_request writing %lu bytes", (unsigned long)(datalen + sizeof(ipc_msg_hdr)));
        //if (MakeSeparateReturnSocket) syslog(LOG_WARNING, "dnssd_clientstub deliver_request name is %s", data);
#if TEST_SENDING_ONE_BYTE_AT_A_TIME
        unsigned int i;
        for (i=0; i<datalen + sizeof(ipc_msg_hdr); i++)
                {
                syslog(LOG_WARNING, "dnssd_clientstub deliver_request writing %d", i);
                if (write_all(sdr->sockfd, ((char *)hdr)+i, 1) < 0)
                        { syslog(LOG_WARNING, "write_all (byte %u) failed", i); goto cleanup; }
                usleep(10000);
                }
#else
        if (write_all(sdr->sockfd, (char *)hdr, datalen + sizeof(ipc_msg_hdr)) < 0)
                {
                syslog(LOG_WARNING, "dnssd_clientstub deliver_request ERROR: write_all(%d, %lu bytes) failed",
                        sdr->sockfd, (unsigned long)(datalen + sizeof(ipc_msg_hdr)));
                goto cleanup;
                }
#endif

        if (!MakeSeparateReturnSocket) errsd = sdr->sockfd;
        if (MakeSeparateReturnSocket || sdr->op == send_bpf)    // Okay to use sdr->op when checking for op == send_bpf
                {
#if defined(USE_TCP_LOOPBACK) || defined(USE_NAMED_ERROR_RETURN_SOCKET)
                // At this point we may block in accept for a few milliseconds waiting for the daemon to connect back to us,
                // but that's okay -- the daemon is a trusted service and we know if won't take more than a few milliseconds to respond.
                dnssd_sockaddr_t daddr;
                dnssd_socklen_t len = sizeof(daddr);
                errsd = accept(listenfd, (struct sockaddr *)&daddr, &len);
                if (!dnssd_SocketValid(errsd)) deliver_request_bailout("accept");
#else

#if APPLE_OSX_mDNSResponder
// On Leopard, the stock definitions of the CMSG_* macros in /usr/include/sys/socket.h,
// while arguably correct in theory, nonetheless in practice produce code that doesn't work on 64-bit machines
// For details see <rdar://problem/5565787> Bonjour API broken for 64-bit apps (SCM_RIGHTS sendmsg fails)
#undef  CMSG_DATA
#define CMSG_DATA(cmsg) ((unsigned char *)(cmsg) + (sizeof(struct cmsghdr)))
#undef  CMSG_SPACE
#define CMSG_SPACE(l)   ((sizeof(struct cmsghdr)) + (l))
#undef  CMSG_LEN
#define CMSG_LEN(l)     ((sizeof(struct cmsghdr)) + (l))
#endif

                struct iovec vec = { ((char *)hdr) + sizeof(ipc_msg_hdr) + datalen, 1 }; // Send the last byte along with the SCM_RIGHTS
                struct msghdr msg;
                struct cmsghdr *cmsg;
                char cbuf[CMSG_SPACE(sizeof(dnssd_sock_t))];

                if (sdr->op == send_bpf)        // Okay to use sdr->op when checking for op == send_bpf
                        {
                        int i;
                        char p[12];             // Room for "/dev/bpf999" with terminating null
                        for (i=0; i<100; i++)
                                {
                                snprintf(p, sizeof(p), "/dev/bpf%d", i);
                                listenfd = open(p, O_RDWR, 0);
                                //if (dnssd_SocketValid(listenfd)) syslog(LOG_WARNING, "Sending fd %d for %s", listenfd, p);
                                if (!dnssd_SocketValid(listenfd) && dnssd_errno != EBUSY)
                                        syslog(LOG_WARNING, "Error opening %s %d (%s)", p, dnssd_errno, dnssd_strerror(dnssd_errno));
                                if (dnssd_SocketValid(listenfd) || dnssd_errno != EBUSY) break;
                                }
                        }

                msg.msg_name       = 0;
                msg.msg_namelen    = 0;
                msg.msg_iov        = &vec;
                msg.msg_iovlen     = 1;
                msg.msg_control    = cbuf;
                msg.msg_controllen = CMSG_LEN(sizeof(dnssd_sock_t));
                msg.msg_flags      = 0;
                cmsg = CMSG_FIRSTHDR(&msg);
                cmsg->cmsg_len     = CMSG_LEN(sizeof(dnssd_sock_t));
                cmsg->cmsg_level   = SOL_SOCKET;
                cmsg->cmsg_type    = SCM_RIGHTS;
                *((dnssd_sock_t *)CMSG_DATA(cmsg)) = listenfd;

#if TEST_KQUEUE_CONTROL_MESSAGE_BUG
                sleep(1);
#endif

#if DEBUG_64BIT_SCM_RIGHTS
                syslog(LOG_WARNING, "dnssd_clientstub sendmsg read sd=%d write sd=%d %ld %ld %ld/%ld/%ld/%ld",
                        errsd, listenfd, sizeof(dnssd_sock_t), sizeof(void*),
                        sizeof(struct cmsghdr) + sizeof(dnssd_sock_t),
                        CMSG_LEN(sizeof(dnssd_sock_t)), (long)CMSG_SPACE(sizeof(dnssd_sock_t)),
                        (long)((char*)CMSG_DATA(cmsg) + 4 - cbuf));
#endif // DEBUG_64BIT_SCM_RIGHTS

                if (sendmsg(sdr->sockfd, &msg, 0) < 0)
                        {
                        syslog(LOG_WARNING, "dnssd_clientstub deliver_request ERROR: sendmsg failed read sd=%d write sd=%d errno %d (%s)",
                                errsd, listenfd, dnssd_errno, dnssd_strerror(dnssd_errno));
                        err = kDNSServiceErr_Incompatible;
                        goto cleanup;
                        }

#if DEBUG_64BIT_SCM_RIGHTS
                syslog(LOG_WARNING, "dnssd_clientstub sendmsg read sd=%d write sd=%d okay", errsd, listenfd);
#endif // DEBUG_64BIT_SCM_RIGHTS

#endif
                // Close our end of the socketpair *before* blocking in read_all to get the four-byte error code.
                // Otherwise, if the daemon closes our socket (or crashes), we block in read_all() forever
                // because the socket is not closed (we still have an open reference to it ourselves).
                dnssd_close(listenfd);
                listenfd = dnssd_InvalidSocket;         // Make sure we don't close it a second time in the cleanup handling below
                }

        // At this point we may block in read_all for a few milliseconds waiting for the daemon to send us the error code,
        // but that's okay -- the daemon is a trusted service and we know if won't take more than a few milliseconds to respond.
        if (sdr->op == send_bpf)        // Okay to use sdr->op when checking for op == send_bpf
                err = kDNSServiceErr_NoError;
        else if (read_all(errsd, (char*)&err, (int)sizeof(err)) < 0)
                err = kDNSServiceErr_ServiceNotRunning; // On failure read_all will have written a message to syslog for us
        else
                err = ntohl(err);

        //syslog(LOG_WARNING, "dnssd_clientstub deliver_request: retrieved error code %d", err);

cleanup:
        if (MakeSeparateReturnSocket)
                {
                if (dnssd_SocketValid(listenfd)) dnssd_close(listenfd);
                if (dnssd_SocketValid(errsd))    dnssd_close(errsd);
#if defined(USE_NAMED_ERROR_RETURN_SOCKET)
                // syslog(LOG_WARNING, "dnssd_clientstub deliver_request: removing UDS: %s", data);
                if (unlink(data) != 0)
                        syslog(LOG_WARNING, "dnssd_clientstub WARNING: unlink(\"%s\") failed errno %d (%s)", data, dnssd_errno, dnssd_strerror(dnssd_errno));
                // else syslog(LOG_WARNING, "dnssd_clientstub deliver_request: removed UDS: %s", data);
#endif
                }

        free(hdr);
        return err;
        }

int DNSSD_API DNSServiceRefSockFD(DNSServiceRef sdRef)
        {
        if (!sdRef) { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRefSockFD called with NULL DNSServiceRef"); return dnssd_InvalidSocket; }

        if (!DNSServiceRefValid(sdRef))
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRefSockFD called with invalid DNSServiceRef %p %08X %08X",
                        sdRef, sdRef->sockfd, sdRef->validator);
                return dnssd_InvalidSocket;
                }

        if (sdRef->primary)
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRefSockFD undefined for kDNSServiceFlagsShareConnection subordinate DNSServiceRef %p", sdRef);
                return dnssd_InvalidSocket;
                }

        return (int) sdRef->sockfd;
        }

#if _DNS_SD_LIBDISPATCH
static void CallbackWithError(DNSServiceRef sdRef, DNSServiceErrorType error)
        {
        DNSServiceOp *sdr = sdRef;
        DNSServiceOp *sdrNext;
        DNSRecord *rec;
        DNSRecord *recnext;
        int morebytes;
        
        while (sdr)
                {
                // We can't touch the sdr after the callback as it can be deallocated in the callback
                sdrNext = sdr->next;
                morebytes = 1;
                sdr->moreptr = &morebytes;
                switch (sdr->op)
                        {
                        case resolve_request:
                                if (sdr->AppCallback)((DNSServiceResolveReply)    sdr->AppCallback)(sdr, 0, 0, error, NULL, 0, 0, 0, NULL,    sdr->AppContext);
                                break;
                        case query_request:
                                if (sdr->AppCallback)((DNSServiceQueryRecordReply)sdr->AppCallback)(sdr, 0, 0, error, NULL, 0, 0, 0, NULL, 0, sdr->AppContext);
                                break;
                        case addrinfo_request:
                                if (sdr->AppCallback)((DNSServiceGetAddrInfoReply)sdr->AppCallback)(sdr, 0, 0, error, NULL, NULL, 0,          sdr->AppContext);
                                break;
                        case browse_request:
                                if (sdr->AppCallback)((DNSServiceBrowseReply)     sdr->AppCallback)(sdr, 0, 0, error, NULL, 0, NULL,          sdr->AppContext);
                                break;
                        case reg_service_request:
                                if (sdr->AppCallback)((DNSServiceRegisterReply)   sdr->AppCallback)(sdr, 0,    error, NULL, 0, NULL,          sdr->AppContext);
                                break;
                        case enumeration_request:
                                if (sdr->AppCallback)((DNSServiceDomainEnumReply) sdr->AppCallback)(sdr, 0, 0, error, NULL,                   sdr->AppContext);
                                break;
                        case connection_request:
                                // This means Register Record, walk the list of DNSRecords to do the callback
                                rec = sdr->rec;
                                while (rec)
                                        {
                                        recnext = rec->recnext;
                                        if (rec->AppCallback) ((DNSServiceRegisterRecordReply)rec->AppCallback)(sdr, 0, 0, error, rec->AppContext);
                                        // The Callback can call DNSServiceRefDeallocate which in turn frees sdr and all the records.
                                        // Detect that and return early
                                        if (!morebytes){syslog(LOG_WARNING, "dnssdclientstub:Record: CallbackwithError morebytes zero"); return;}
                                        rec = recnext;
                                        }
                                break;
                        case port_mapping_request:
                                if (sdr->AppCallback)((DNSServiceNATPortMappingReply)sdr->AppCallback)(sdr, 0, 0, error, 0, 0, 0, 0, 0, sdr->AppContext);
                                break;
                        default:
                                syslog(LOG_WARNING, "dnssd_clientstub CallbackWithError called with bad op %d", sdr->op);
                        }
                // If DNSServiceRefDeallocate was called in the callback, morebytes will be zero. It means
                // all other sdrefs have been freed. This happens for shared connections where the
                // DNSServiceRefDeallocate on the first sdRef frees all other sdrefs.
                if (!morebytes){syslog(LOG_WARNING, "dnssdclientstub:sdRef: CallbackwithError morebytes zero"); return;}
                sdr = sdrNext;
                }
        }
#endif // _DNS_SD_LIBDISPATCH

// Handle reply from server, calling application client callback. If there is no reply
// from the daemon on the socket contained in sdRef, the call will block.
DNSServiceErrorType DNSSD_API DNSServiceProcessResult(DNSServiceRef sdRef)
        {
        int morebytes = 0;

        if (!sdRef) { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceProcessResult called with NULL DNSServiceRef"); return kDNSServiceErr_BadParam; }

        if (!DNSServiceRefValid(sdRef))
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceProcessResult called with invalid DNSServiceRef %p %08X %08X", sdRef, sdRef->sockfd, sdRef->validator);
                return kDNSServiceErr_BadReference;
                }

        if (sdRef->primary)
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceProcessResult undefined for kDNSServiceFlagsShareConnection subordinate DNSServiceRef %p", sdRef);
                return kDNSServiceErr_BadReference;
                }

        if (!sdRef->ProcessReply)
                {
                static int num_logs = 0;
                if (num_logs < 10) syslog(LOG_WARNING, "dnssd_clientstub DNSServiceProcessResult called with DNSServiceRef with no ProcessReply function");
                if (num_logs < 1000) num_logs++; else sleep(1);
                return kDNSServiceErr_BadReference;
                }

        do
                {
                CallbackHeader cbh;
                char *data;
        
                // return NoError on EWOULDBLOCK. This will handle the case
                // where a non-blocking socket is told there is data, but it was a false positive.
                // On error, read_all will write a message to syslog for us, so don't need to duplicate that here
                // Note: If we want to properly support using non-blocking sockets in the future
                int result = read_all(sdRef->sockfd, (void *)&cbh.ipc_hdr, sizeof(cbh.ipc_hdr));
                if (result == read_all_fail)
                        {
                        // Set the ProcessReply to NULL before callback as the sdRef can get deallocated
                        // in the callback.
                        sdRef->ProcessReply = NULL;
#if _DNS_SD_LIBDISPATCH
                        // Call the callbacks with an error if using the dispatch API, as DNSServiceProcessResult
                        // is not called by the application and hence need to communicate the error. Cancel the
                        // source so that we don't get any more events
                        if (sdRef->disp_source)
                                {
                                dispatch_source_cancel(sdRef->disp_source);
                                dispatch_release(sdRef->disp_source);
                                sdRef->disp_source = NULL;
                                CallbackWithError(sdRef, kDNSServiceErr_ServiceNotRunning);
                                }
#endif
                        // Don't touch sdRef anymore as it might have been deallocated
                        return kDNSServiceErr_ServiceNotRunning;
                        }
                else if (result == read_all_wouldblock)
                        {
                        if (morebytes && sdRef->logcounter < 100)
                                {
                                sdRef->logcounter++;
                                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceProcessResult error: select indicated data was waiting but read_all returned EWOULDBLOCK");
                                }
                        return kDNSServiceErr_NoError;
                        }
        
                ConvertHeaderBytes(&cbh.ipc_hdr);
                if (cbh.ipc_hdr.version != VERSION)
                        {
                        syslog(LOG_WARNING, "dnssd_clientstub DNSServiceProcessResult daemon version %d does not match client version %d", cbh.ipc_hdr.version, VERSION);
                        sdRef->ProcessReply = NULL;
                        return kDNSServiceErr_Incompatible;
                        }
        
                data = malloc(cbh.ipc_hdr.datalen);
                if (!data) return kDNSServiceErr_NoMemory;
                if (read_all(sdRef->sockfd, data, cbh.ipc_hdr.datalen) < 0) // On error, read_all will write a message to syslog for us
                        {
                        // Set the ProcessReply to NULL before callback as the sdRef can get deallocated
                        // in the callback.
                        sdRef->ProcessReply = NULL;
#if _DNS_SD_LIBDISPATCH
                        // Call the callbacks with an error if using the dispatch API, as DNSServiceProcessResult
                        // is not called by the application and hence need to communicate the error. Cancel the
                        // source so that we don't get any more events
                        if (sdRef->disp_source)
                                {
                                dispatch_source_cancel(sdRef->disp_source);
                                dispatch_release(sdRef->disp_source);
                                sdRef->disp_source = NULL;
                                CallbackWithError(sdRef, kDNSServiceErr_ServiceNotRunning);
                                }
#endif
                        // Don't touch sdRef anymore as it might have been deallocated
                        free(data);
                        return kDNSServiceErr_ServiceNotRunning;
                        }
                else
                        {
                        const char *ptr = data;
                        cbh.cb_flags     = get_flags     (&ptr, data + cbh.ipc_hdr.datalen);
                        cbh.cb_interface = get_uint32    (&ptr, data + cbh.ipc_hdr.datalen);
                        cbh.cb_err       = get_error_code(&ptr, data + cbh.ipc_hdr.datalen);

                        // CAUTION: We have to handle the case where the client calls DNSServiceRefDeallocate from within the callback function.
                        // To do this we set moreptr to point to morebytes. If the client does call DNSServiceRefDeallocate(),
                        // then that routine will clear morebytes for us, and cause us to exit our loop.
                        morebytes = more_bytes(sdRef->sockfd);
                        if (morebytes)
                                {
                                cbh.cb_flags |= kDNSServiceFlagsMoreComing;
                                sdRef->moreptr = &morebytes;
                                }
                        if (ptr) sdRef->ProcessReply(sdRef, &cbh, ptr, data + cbh.ipc_hdr.datalen);
                        // Careful code here:
                        // If morebytes is non-zero, that means we set sdRef->moreptr above, and the operation was not
                        // cancelled out from under us, so now we need to clear sdRef->moreptr so we don't leave a stray
                        // dangling pointer pointing to a long-gone stack variable.
                        // If morebytes is zero, then one of two thing happened:
                        // (a) morebytes was 0 above, so we didn't set sdRef->moreptr, so we don't need to clear it
                        // (b) morebytes was 1 above, and we set sdRef->moreptr, but the operation was cancelled (with DNSServiceRefDeallocate()),
                        //     so we MUST NOT try to dereference our stale sdRef pointer.
                        if (morebytes) sdRef->moreptr = NULL;
                        }
                free(data);
                } while (morebytes);

        return kDNSServiceErr_NoError;
        }

void DNSSD_API DNSServiceRefDeallocate(DNSServiceRef sdRef)
        {
        if (!sdRef) { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRefDeallocate called with NULL DNSServiceRef"); return; }

        if (!DNSServiceRefValid(sdRef))         // Also verifies dnssd_SocketValid(sdRef->sockfd) for us too
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRefDeallocate called with invalid DNSServiceRef %p %08X %08X", sdRef, sdRef->sockfd, sdRef->validator);
                return;
                }

        // If we're in the middle of a DNSServiceProcessResult() invocation for this DNSServiceRef, clear its morebytes flag to break it out of its while loop
        if (sdRef->moreptr) *(sdRef->moreptr) = 0;

        if (sdRef->primary)             // If this is a subordinate DNSServiceOp, just send a 'stop' command
                {
                DNSServiceOp **p = &sdRef->primary->next;
                while (*p && *p != sdRef) p = &(*p)->next;
                if (*p)
                        {
                        char *ptr;
                        size_t len = 0;
                        ipc_msg_hdr *hdr = create_hdr(cancel_request, &len, &ptr, 0, sdRef);
                        if (hdr)
                                {
                                ConvertHeaderBytes(hdr);
                                write_all(sdRef->sockfd, (char *)hdr, len);
                                free(hdr);
                                }
                        *p = sdRef->next;
                        FreeDNSServiceOp(sdRef);
                        }
                }
        else                                    // else, make sure to terminate all subordinates as well
                {
#if _DNS_SD_LIBDISPATCH
                // The cancel handler will close the fd if a dispatch source has been set
                if (sdRef->disp_source)
                        {
                        // By setting the ProcessReply to NULL, we make sure that we never call
                        // the application callbacks ever, after returning from this function. We
                        // assume that DNSServiceRefDeallocate is called from the serial queue
                        // that was passed to DNSServiceSetDispatchQueue. Hence, dispatch_source_cancel
                        // should cancel all the blocks on the queue and hence there should be no more
                        // callbacks when we return from this function. Setting ProcessReply to NULL
                        // provides extra protection.
                        sdRef->ProcessReply = NULL;
                        dispatch_source_cancel(sdRef->disp_source);
                        dispatch_release(sdRef->disp_source);
                        sdRef->disp_source = NULL;
                        }
                        // if disp_queue is set, it means it used the DNSServiceSetDispatchQueue API. In that case,
                        // when the source was cancelled, the fd was closed in the handler. Currently the source
                        // is cancelled only when the mDNSResponder daemon dies
                else if (!sdRef->disp_queue) dnssd_close(sdRef->sockfd);
#else
                dnssd_close(sdRef->sockfd);
#endif
                // Free DNSRecords added in DNSRegisterRecord if they have not
                // been freed in DNSRemoveRecord
                while (sdRef)
                        {
                        DNSServiceOp *p = sdRef;
                        sdRef = sdRef->next;
                        FreeDNSServiceOp(p);
                        }
                }
        }

DNSServiceErrorType DNSSD_API DNSServiceGetProperty(const char *property, void *result, uint32_t *size)
        {
        char *ptr;
        size_t len = strlen(property) + 1;
        ipc_msg_hdr *hdr;
        DNSServiceOp *tmp;
        uint32_t actualsize;

        DNSServiceErrorType err = ConnectToServer(&tmp, 0, getproperty_request, NULL, NULL, NULL);
        if (err) return err;

        hdr = create_hdr(getproperty_request, &len, &ptr, 0, tmp);
        if (!hdr) { DNSServiceRefDeallocate(tmp); return kDNSServiceErr_NoMemory; }

        put_string(property, &ptr);
        err = deliver_request(hdr, tmp);                // Will free hdr for us
        if (read_all(tmp->sockfd, (char*)&actualsize, (int)sizeof(actualsize)) < 0)
                { DNSServiceRefDeallocate(tmp); return kDNSServiceErr_ServiceNotRunning; }

        actualsize = ntohl(actualsize);
        if (read_all(tmp->sockfd, (char*)result, actualsize < *size ? actualsize : *size) < 0)
                { DNSServiceRefDeallocate(tmp); return kDNSServiceErr_ServiceNotRunning; }
        DNSServiceRefDeallocate(tmp);

        // Swap version result back to local process byte order
        if (!strcmp(property, kDNSServiceProperty_DaemonVersion) && *size >= 4)
                *(uint32_t*)result = ntohl(*(uint32_t*)result);

        *size = actualsize;
        return kDNSServiceErr_NoError;
        }

static void handle_resolve_response(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *data, const char *end)
        {
        char fullname[kDNSServiceMaxDomainName];
        char target[kDNSServiceMaxDomainName];
        uint16_t txtlen;
        union { uint16_t s; u_char b[2]; } port;
        unsigned char *txtrecord;

        get_string(&data, end, fullname, kDNSServiceMaxDomainName);
        get_string(&data, end, target,   kDNSServiceMaxDomainName);
        if (!data || data + 2 > end) goto fail;

        port.b[0] = *data++;
        port.b[1] = *data++;
        txtlen = get_uint16(&data, end);
        txtrecord = (unsigned char *)get_rdata(&data, end, txtlen);

        if (!data) goto fail;
        ((DNSServiceResolveReply)sdr->AppCallback)(sdr, cbh->cb_flags, cbh->cb_interface, cbh->cb_err, fullname, target, port.s, txtlen, txtrecord, sdr->AppContext);
        return;
        // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function
fail:
        syslog(LOG_WARNING, "dnssd_clientstub handle_resolve_response: error reading result from daemon");
        }

DNSServiceErrorType DNSSD_API DNSServiceResolve
        (
        DNSServiceRef                 *sdRef,
        DNSServiceFlags               flags,
        uint32_t                      interfaceIndex,
        const char                    *name,
        const char                    *regtype,
        const char                    *domain,
        DNSServiceResolveReply        callBack,
        void                          *context
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err;

        if (!name || !regtype || !domain || !callBack) return kDNSServiceErr_BadParam;

        err = ConnectToServer(sdRef, flags, resolve_request, handle_resolve_response, callBack, context);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL

        // Calculate total message length
        len = sizeof(flags);
        len += sizeof(interfaceIndex);
        len += strlen(name) + 1;
        len += strlen(regtype) + 1;
        len += strlen(domain) + 1;

        hdr = create_hdr(resolve_request, &len, &ptr, (*sdRef)->primary ? 1 : 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_string(name, &ptr);
        put_string(regtype, &ptr);
        put_string(domain, &ptr);

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }

static void handle_query_response(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *data, const char *const end)
        {
        uint32_t ttl;
        char name[kDNSServiceMaxDomainName];
        uint16_t rrtype, rrclass, rdlen;
        const char *rdata;

        get_string(&data, end, name, kDNSServiceMaxDomainName);
        rrtype  = get_uint16(&data, end);
        rrclass = get_uint16(&data, end);
        rdlen   = get_uint16(&data, end);
        rdata   = get_rdata(&data, end, rdlen);
        ttl     = get_uint32(&data, end);

        if (!data) syslog(LOG_WARNING, "dnssd_clientstub handle_query_response: error reading result from daemon");
        else ((DNSServiceQueryRecordReply)sdr->AppCallback)(sdr, cbh->cb_flags, cbh->cb_interface, cbh->cb_err, name, rrtype, rrclass, rdlen, rdata, ttl, sdr->AppContext);
        // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function
        }

DNSServiceErrorType DNSSD_API DNSServiceQueryRecord
        (
        DNSServiceRef              *sdRef,
        DNSServiceFlags             flags,
        uint32_t                    interfaceIndex,
        const char                 *name,
        uint16_t                    rrtype,
        uint16_t                    rrclass,
        DNSServiceQueryRecordReply  callBack,
        void                       *context
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err = ConnectToServer(sdRef, flags, query_request, handle_query_response, callBack, context);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL

        if (!name) name = "\0";

        // Calculate total message length
        len = sizeof(flags);
        len += sizeof(uint32_t);  // interfaceIndex
        len += strlen(name) + 1;
        len += 2 * sizeof(uint16_t);  // rrtype, rrclass

        hdr = create_hdr(query_request, &len, &ptr, (*sdRef)->primary ? 1 : 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_string(name, &ptr);
        put_uint16(rrtype, &ptr);
        put_uint16(rrclass, &ptr);

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }

static void handle_addrinfo_response(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *data, const char *const end)
        {
        char hostname[kDNSServiceMaxDomainName];
        uint16_t rrtype, rrclass, rdlen;
        const char *rdata;
        uint32_t ttl;

        get_string(&data, end, hostname, kDNSServiceMaxDomainName);
        rrtype  = get_uint16(&data, end);
        rrclass = get_uint16(&data, end);
        rdlen   = get_uint16(&data, end);
        rdata   = get_rdata (&data, end, rdlen);
        ttl     = get_uint32(&data, end);

        // We only generate client callbacks for A and AAAA results (including NXDOMAIN results for
        // those types, if the client has requested those with the kDNSServiceFlagsReturnIntermediates).
        // Other result types, specifically CNAME referrals, are not communicated to the client, because
        // the DNSServiceGetAddrInfoReply interface doesn't have any meaningful way to communiate CNAME referrals.
        if (!data) syslog(LOG_WARNING, "dnssd_clientstub handle_addrinfo_response: error reading result from daemon");
        else if (rrtype == kDNSServiceType_A || rrtype == kDNSServiceType_AAAA)
                {
                struct sockaddr_in  sa4;
                struct sockaddr_in6 sa6;
                const struct sockaddr *const sa = (rrtype == kDNSServiceType_A) ? (struct sockaddr*)&sa4 : (struct sockaddr*)&sa6;
                if (rrtype == kDNSServiceType_A)
                        {
                        memset(&sa4, 0, sizeof(sa4));
                        #ifndef NOT_HAVE_SA_LEN
                        sa4.sin_len = sizeof(struct sockaddr_in);
                        #endif
                        sa4.sin_family = AF_INET;
                        //  sin_port   = 0;
                        if (!cbh->cb_err) memcpy(&sa4.sin_addr, rdata, rdlen);
                        }
                else
                        {
                        memset(&sa6, 0, sizeof(sa6));
                        #ifndef NOT_HAVE_SA_LEN
                        sa6.sin6_len = sizeof(struct sockaddr_in6);
                        #endif
                        sa6.sin6_family     = AF_INET6;
                        //  sin6_port     = 0;
                        //  sin6_flowinfo = 0;
                        //  sin6_scope_id = 0;
                        if (!cbh->cb_err)
                                {
                                memcpy(&sa6.sin6_addr, rdata, rdlen);
                                if (IN6_IS_ADDR_LINKLOCAL(&sa6.sin6_addr)) sa6.sin6_scope_id = cbh->cb_interface;
                                }
                        }
                ((DNSServiceGetAddrInfoReply)sdr->AppCallback)(sdr, cbh->cb_flags, cbh->cb_interface, cbh->cb_err, hostname, sa, ttl, sdr->AppContext);
                // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function
                }
        }

DNSServiceErrorType DNSSD_API DNSServiceGetAddrInfo
        (
        DNSServiceRef                    *sdRef,
        DNSServiceFlags                  flags,
        uint32_t                         interfaceIndex,
        uint32_t                         protocol,
        const char                       *hostname,
        DNSServiceGetAddrInfoReply       callBack,
        void                             *context          /* may be NULL */
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err;

        if (!hostname) return kDNSServiceErr_BadParam;

        err = ConnectToServer(sdRef, flags, addrinfo_request, handle_addrinfo_response, callBack, context);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL

        // Calculate total message length
        len = sizeof(flags);
        len += sizeof(uint32_t);      // interfaceIndex
        len += sizeof(uint32_t);      // protocol
        len += strlen(hostname) + 1;

        hdr = create_hdr(addrinfo_request, &len, &ptr, (*sdRef)->primary ? 1 : 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_uint32(protocol, &ptr);
        put_string(hostname, &ptr);

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }
        
static void handle_browse_response(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *data, const char *const end)
        {
        char replyName[256], replyType[kDNSServiceMaxDomainName], replyDomain[kDNSServiceMaxDomainName];
        get_string(&data, end, replyName, 256);
        get_string(&data, end, replyType, kDNSServiceMaxDomainName);
        get_string(&data, end, replyDomain, kDNSServiceMaxDomainName);
        if (!data) syslog(LOG_WARNING, "dnssd_clientstub handle_browse_response: error reading result from daemon");
        else ((DNSServiceBrowseReply)sdr->AppCallback)(sdr, cbh->cb_flags, cbh->cb_interface, cbh->cb_err, replyName, replyType, replyDomain, sdr->AppContext);
        // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function
        }

DNSServiceErrorType DNSSD_API DNSServiceBrowse
        (
        DNSServiceRef         *sdRef,
        DNSServiceFlags        flags,
        uint32_t               interfaceIndex,
        const char            *regtype,
        const char            *domain,
        DNSServiceBrowseReply  callBack,
        void                  *context
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err = ConnectToServer(sdRef, flags, browse_request, handle_browse_response, callBack, context);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL

        if (!domain) domain = "";
        len = sizeof(flags);
        len += sizeof(interfaceIndex);
        len += strlen(regtype) + 1;
        len += strlen(domain) + 1;

        hdr = create_hdr(browse_request, &len, &ptr, (*sdRef)->primary ? 1 : 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_string(regtype, &ptr);
        put_string(domain, &ptr);

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }

DNSServiceErrorType DNSSD_API DNSServiceSetDefaultDomainForUser(DNSServiceFlags flags, const char *domain);
DNSServiceErrorType DNSSD_API DNSServiceSetDefaultDomainForUser(DNSServiceFlags flags, const char *domain)
        {
        DNSServiceOp *tmp;
        char *ptr;
        size_t len = sizeof(flags) + strlen(domain) + 1;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err = ConnectToServer(&tmp, 0, setdomain_request, NULL, NULL, NULL);
        if (err) return err;

        hdr = create_hdr(setdomain_request, &len, &ptr, 0, tmp);
        if (!hdr) { DNSServiceRefDeallocate(tmp); return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_string(domain, &ptr);
        err = deliver_request(hdr, tmp);                // Will free hdr for us
        DNSServiceRefDeallocate(tmp);
        return err;
        }

static void handle_regservice_response(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *data, const char *const end)
        {
        char name[256], regtype[kDNSServiceMaxDomainName], domain[kDNSServiceMaxDomainName];
        get_string(&data, end, name, 256);
        get_string(&data, end, regtype, kDNSServiceMaxDomainName);
        get_string(&data, end, domain,  kDNSServiceMaxDomainName);
        if (!data) syslog(LOG_WARNING, "dnssd_clientstub handle_regservice_response: error reading result from daemon");
        else ((DNSServiceRegisterReply)sdr->AppCallback)(sdr, cbh->cb_flags, cbh->cb_err, name, regtype, domain, sdr->AppContext);
        // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function
        }

DNSServiceErrorType DNSSD_API DNSServiceRegister
        (
        DNSServiceRef                       *sdRef,
        DNSServiceFlags                     flags,
        uint32_t                            interfaceIndex,
        const char                          *name,
        const char                          *regtype,
        const char                          *domain,
        const char                          *host,
        uint16_t                            PortInNetworkByteOrder,
        uint16_t                            txtLen,
        const void                          *txtRecord,
        DNSServiceRegisterReply             callBack,
        void                                *context
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err;
        union { uint16_t s; u_char b[2]; } port = { PortInNetworkByteOrder };

        if (!name) name = "";
        if (!regtype) return kDNSServiceErr_BadParam;
        if (!domain) domain = "";
        if (!host) host = "";
        if (!txtRecord) txtRecord = (void*)"";

        // No callback must have auto-rename
        if (!callBack && (flags & kDNSServiceFlagsNoAutoRename)) return kDNSServiceErr_BadParam;

        err = ConnectToServer(sdRef, flags, reg_service_request, callBack ? handle_regservice_response : NULL, callBack, context);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL

        len = sizeof(DNSServiceFlags);
        len += sizeof(uint32_t);  // interfaceIndex
        len += strlen(name) + strlen(regtype) + strlen(domain) + strlen(host) + 4;
        len += 2 * sizeof(uint16_t);  // port, txtLen
        len += txtLen;

        hdr = create_hdr(reg_service_request, &len, &ptr, (*sdRef)->primary ? 1 : 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }
        if (!callBack) hdr->ipc_flags |= IPC_FLAGS_NOREPLY;

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_string(name, &ptr);
        put_string(regtype, &ptr);
        put_string(domain, &ptr);
        put_string(host, &ptr);
        *ptr++ = port.b[0];
        *ptr++ = port.b[1];
        put_uint16(txtLen, &ptr);
        put_rdata(txtLen, txtRecord, &ptr);

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }

static void handle_enumeration_response(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *data, const char *const end)
        {
        char domain[kDNSServiceMaxDomainName];
        get_string(&data, end, domain, kDNSServiceMaxDomainName);
        if (!data) syslog(LOG_WARNING, "dnssd_clientstub handle_enumeration_response: error reading result from daemon");
        else ((DNSServiceDomainEnumReply)sdr->AppCallback)(sdr, cbh->cb_flags, cbh->cb_interface, cbh->cb_err, domain, sdr->AppContext);
        // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function
        }

DNSServiceErrorType DNSSD_API DNSServiceEnumerateDomains
        (
        DNSServiceRef             *sdRef,
        DNSServiceFlags            flags,
        uint32_t                   interfaceIndex,
        DNSServiceDomainEnumReply  callBack,
        void                      *context
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err;

        int f1 = (flags & kDNSServiceFlagsBrowseDomains) != 0;
        int f2 = (flags & kDNSServiceFlagsRegistrationDomains) != 0;
        if (f1 + f2 != 1) return kDNSServiceErr_BadParam;

        err = ConnectToServer(sdRef, flags, enumeration_request, handle_enumeration_response, callBack, context);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL

        len = sizeof(DNSServiceFlags);
        len += sizeof(uint32_t);

        hdr = create_hdr(enumeration_request, &len, &ptr, (*sdRef)->primary ? 1 : 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }

static void ConnectionResponse(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *const data, const char *const end)
        {
        DNSRecordRef rref = cbh->ipc_hdr.client_context.context;
        (void)data; // Unused

        //printf("ConnectionResponse got %d\n", cbh->ipc_hdr.op);
        if (cbh->ipc_hdr.op != reg_record_reply_op)
                {
                // When using kDNSServiceFlagsShareConnection, need to search the list of associated DNSServiceOps
                // to find the one this response is intended for, and then call through to its ProcessReply handler.
                // We start with our first subordinate DNSServiceRef -- don't want to accidentally match the parent DNSServiceRef.
                DNSServiceOp *op = sdr->next;
                while (op && (op->uid.u32[0] != cbh->ipc_hdr.client_context.u32[0] || op->uid.u32[1] != cbh->ipc_hdr.client_context.u32[1]))
                        op = op->next;
                // Note: We may sometimes not find a matching DNSServiceOp, in the case where the client has
                // cancelled the subordinate DNSServiceOp, but there are still messages in the pipeline from the daemon
                if (op && op->ProcessReply) op->ProcessReply(op, cbh, data, end);
                // WARNING: Don't touch op or sdr after this -- client may have called DNSServiceRefDeallocate
                return;
                }

        if (sdr->op == connection_request)
                rref->AppCallback(rref->sdr, rref, cbh->cb_flags, cbh->cb_err, rref->AppContext);
        else
                {
                syslog(LOG_WARNING, "dnssd_clientstub ConnectionResponse: sdr->op != connection_request");
                rref->AppCallback(rref->sdr, rref, 0, kDNSServiceErr_Unknown, rref->AppContext);
                }
        // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function
        }

DNSServiceErrorType DNSSD_API DNSServiceCreateConnection(DNSServiceRef *sdRef)
        {
        char *ptr;
        size_t len = 0;
        ipc_msg_hdr *hdr;
        DNSServiceErrorType err = ConnectToServer(sdRef, 0, connection_request, ConnectionResponse, NULL, NULL);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL
        
        hdr = create_hdr(connection_request, &len, &ptr, 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }

DNSServiceErrorType DNSSD_API DNSServiceRegisterRecord
        (
        DNSServiceRef                  sdRef,
        DNSRecordRef                  *RecordRef,
        DNSServiceFlags                flags,
        uint32_t                       interfaceIndex,
        const char                    *fullname,
        uint16_t                       rrtype,
        uint16_t                       rrclass,
        uint16_t                       rdlen,
        const void                    *rdata,
        uint32_t                       ttl,
        DNSServiceRegisterRecordReply  callBack,
        void                          *context
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr = NULL;
        DNSRecordRef rref = NULL;
        DNSRecord **p;
        int f1 = (flags & kDNSServiceFlagsShared) != 0;
        int f2 = (flags & kDNSServiceFlagsUnique) != 0;
        if (f1 + f2 != 1) return kDNSServiceErr_BadParam;

        if (!sdRef) { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRegisterRecord called with NULL DNSServiceRef"); return kDNSServiceErr_BadParam; }

        if (!DNSServiceRefValid(sdRef))
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRegisterRecord called with invalid DNSServiceRef %p %08X %08X", sdRef, sdRef->sockfd, sdRef->validator);
                return kDNSServiceErr_BadReference;
                }

        if (sdRef->op != connection_request)
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRegisterRecord called with non-DNSServiceCreateConnection DNSServiceRef %p %d", sdRef, sdRef->op);
                return kDNSServiceErr_BadReference;
                }

        *RecordRef = NULL;

        len = sizeof(DNSServiceFlags);
        len += 2 * sizeof(uint32_t);  // interfaceIndex, ttl
        len += 3 * sizeof(uint16_t);  // rrtype, rrclass, rdlen
        len += strlen(fullname) + 1;
        len += rdlen;

        hdr = create_hdr(reg_record_request, &len, &ptr, 1, sdRef);
        if (!hdr) return kDNSServiceErr_NoMemory;

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_string(fullname, &ptr);
        put_uint16(rrtype, &ptr);
        put_uint16(rrclass, &ptr);
        put_uint16(rdlen, &ptr);
        put_rdata(rdlen, rdata, &ptr);
        put_uint32(ttl, &ptr);

        rref = malloc(sizeof(DNSRecord));
        if (!rref) { free(hdr); return kDNSServiceErr_NoMemory; }
        rref->AppContext = context;
        rref->AppCallback = callBack;
        rref->record_index = sdRef->max_index++;
        rref->sdr = sdRef;
        rref->recnext = NULL;
        *RecordRef = rref;
        hdr->client_context.context = rref;
        hdr->reg_index = rref->record_index;

        p = &(sdRef)->rec;
        while (*p) p = &(*p)->recnext;
        *p = rref;

        return deliver_request(hdr, sdRef);             // Will free hdr for us
        }

// sdRef returned by DNSServiceRegister()
DNSServiceErrorType DNSSD_API DNSServiceAddRecord
        (
        DNSServiceRef    sdRef,
        DNSRecordRef    *RecordRef,
        DNSServiceFlags  flags,
        uint16_t         rrtype,
        uint16_t         rdlen,
        const void      *rdata,
        uint32_t         ttl
        )
        {
        ipc_msg_hdr *hdr;
        size_t len = 0;
        char *ptr;
        DNSRecordRef rref;
        DNSRecord **p;

        if (!sdRef)     { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceAddRecord called with NULL DNSServiceRef");        return kDNSServiceErr_BadParam; }
        if (!RecordRef) { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceAddRecord called with NULL DNSRecordRef pointer"); return kDNSServiceErr_BadParam; }
        if (sdRef->op != reg_service_request)
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceAddRecord called with non-DNSServiceRegister DNSServiceRef %p %d", sdRef, sdRef->op);
                return kDNSServiceErr_BadReference;
                }

        if (!DNSServiceRefValid(sdRef))
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceAddRecord called with invalid DNSServiceRef %p %08X %08X", sdRef, sdRef->sockfd, sdRef->validator);
                return kDNSServiceErr_BadReference;
                }

        *RecordRef = NULL;

        len += 2 * sizeof(uint16_t);  // rrtype, rdlen
        len += rdlen;
        len += sizeof(uint32_t);
        len += sizeof(DNSServiceFlags);

        hdr = create_hdr(add_record_request, &len, &ptr, 1, sdRef);
        if (!hdr) return kDNSServiceErr_NoMemory;
        put_flags(flags, &ptr);
        put_uint16(rrtype, &ptr);
        put_uint16(rdlen, &ptr);
        put_rdata(rdlen, rdata, &ptr);
        put_uint32(ttl, &ptr);

        rref = malloc(sizeof(DNSRecord));
        if (!rref) { free(hdr); return kDNSServiceErr_NoMemory; }
        rref->AppContext = NULL;
        rref->AppCallback = NULL;
        rref->record_index = sdRef->max_index++;
        rref->sdr = sdRef;
        rref->recnext = NULL;
        *RecordRef = rref;
        hdr->reg_index = rref->record_index;

        p = &(sdRef)->rec;
        while (*p) p = &(*p)->recnext;
        *p = rref;

        return deliver_request(hdr, sdRef);             // Will free hdr for us
        }

// DNSRecordRef returned by DNSServiceRegisterRecord or DNSServiceAddRecord
DNSServiceErrorType DNSSD_API DNSServiceUpdateRecord
        (
        DNSServiceRef    sdRef,
        DNSRecordRef     RecordRef,
        DNSServiceFlags  flags,
        uint16_t         rdlen,
        const void      *rdata,
        uint32_t         ttl
        )
        {
        ipc_msg_hdr *hdr;
        size_t len = 0;
        char *ptr;

        if (!sdRef) { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceUpdateRecord called with NULL DNSServiceRef"); return kDNSServiceErr_BadParam; }

        if (!DNSServiceRefValid(sdRef))
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceUpdateRecord called with invalid DNSServiceRef %p %08X %08X", sdRef, sdRef->sockfd, sdRef->validator);
                return kDNSServiceErr_BadReference;
                }

        // Note: RecordRef is allowed to be NULL

        len += sizeof(uint16_t);
        len += rdlen;
        len += sizeof(uint32_t);
        len += sizeof(DNSServiceFlags);

        hdr = create_hdr(update_record_request, &len, &ptr, 1, sdRef);
        if (!hdr) return kDNSServiceErr_NoMemory;
        hdr->reg_index = RecordRef ? RecordRef->record_index : TXT_RECORD_INDEX;
        put_flags(flags, &ptr);
        put_uint16(rdlen, &ptr);
        put_rdata(rdlen, rdata, &ptr);
        put_uint32(ttl, &ptr);
        return deliver_request(hdr, sdRef);             // Will free hdr for us
        }

DNSServiceErrorType DNSSD_API DNSServiceRemoveRecord
        (
        DNSServiceRef    sdRef,
        DNSRecordRef     RecordRef,
        DNSServiceFlags  flags
        )
        {
        ipc_msg_hdr *hdr;
        size_t len = 0;
        char *ptr;
        DNSServiceErrorType err;

        if (!sdRef)            { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRemoveRecord called with NULL DNSServiceRef"); return kDNSServiceErr_BadParam; }
        if (!RecordRef)        { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRemoveRecord called with NULL DNSRecordRef");  return kDNSServiceErr_BadParam; }
        if (!sdRef->max_index) { syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRemoveRecord called with bad DNSServiceRef");  return kDNSServiceErr_BadReference; }

        if (!DNSServiceRefValid(sdRef))
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceRemoveRecord called with invalid DNSServiceRef %p %08X %08X", sdRef, sdRef->sockfd, sdRef->validator);
                return kDNSServiceErr_BadReference;
                }

        len += sizeof(flags);
        hdr = create_hdr(remove_record_request, &len, &ptr, 1, sdRef);
        if (!hdr) return kDNSServiceErr_NoMemory;
        hdr->reg_index = RecordRef->record_index;
        put_flags(flags, &ptr);
        err = deliver_request(hdr, sdRef);              // Will free hdr for us
        if (!err)
                {
                // This RecordRef could have been allocated in DNSServiceRegisterRecord or DNSServiceAddRecord.
                // If so, delink from the list before freeing
                DNSRecord **p = &sdRef->rec;
                while (*p && *p != RecordRef) p = &(*p)->recnext;
                if (*p) *p = RecordRef->recnext;
                free(RecordRef);
                }
        return err;
        }

DNSServiceErrorType DNSSD_API DNSServiceReconfirmRecord
        (
        DNSServiceFlags  flags,
        uint32_t         interfaceIndex,
        const char      *fullname,
        uint16_t         rrtype,
        uint16_t         rrclass,
        uint16_t         rdlen,
        const void      *rdata
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        DNSServiceOp *tmp;

        DNSServiceErrorType err = ConnectToServer(&tmp, flags, reconfirm_record_request, NULL, NULL, NULL);
        if (err) return err;

        len = sizeof(DNSServiceFlags);
        len += sizeof(uint32_t);
        len += strlen(fullname) + 1;
        len += 3 * sizeof(uint16_t);
        len += rdlen;
        hdr = create_hdr(reconfirm_record_request, &len, &ptr, 0, tmp);
        if (!hdr) { DNSServiceRefDeallocate(tmp); return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_string(fullname, &ptr);
        put_uint16(rrtype, &ptr);
        put_uint16(rrclass, &ptr);
        put_uint16(rdlen, &ptr);
        put_rdata(rdlen, rdata, &ptr);

        err = deliver_request(hdr, tmp);                // Will free hdr for us
        DNSServiceRefDeallocate(tmp);
        return err;
        }

static void handle_port_mapping_response(DNSServiceOp *const sdr, const CallbackHeader *const cbh, const char *data, const char *const end)
        {
        union { uint32_t l; u_char b[4]; } addr;
        uint8_t protocol;
        union { uint16_t s; u_char b[2]; } internalPort;
        union { uint16_t s; u_char b[2]; } externalPort;
        uint32_t ttl;

        if (!data || data + 13 > end) goto fail;

        addr        .b[0] = *data++;
        addr        .b[1] = *data++;
        addr        .b[2] = *data++;
        addr        .b[3] = *data++;
        protocol          = *data++;
        internalPort.b[0] = *data++;
        internalPort.b[1] = *data++;
        externalPort.b[0] = *data++;
        externalPort.b[1] = *data++;
        ttl               = get_uint32(&data, end);
        if (!data) goto fail;

        ((DNSServiceNATPortMappingReply)sdr->AppCallback)(sdr, cbh->cb_flags, cbh->cb_interface, cbh->cb_err, addr.l, protocol, internalPort.s, externalPort.s, ttl, sdr->AppContext);
        return;
        // MUST NOT touch sdr after invoking AppCallback -- client is allowed to dispose it from within callback function

fail:
        syslog(LOG_WARNING, "dnssd_clientstub handle_port_mapping_response: error reading result from daemon");
        }

DNSServiceErrorType DNSSD_API DNSServiceNATPortMappingCreate
        (
        DNSServiceRef                       *sdRef,
        DNSServiceFlags                     flags,
        uint32_t                            interfaceIndex,
        uint32_t                            protocol,     /* TCP and/or UDP */
        uint16_t                            internalPortInNetworkByteOrder,
        uint16_t                            externalPortInNetworkByteOrder,
        uint32_t                            ttl,          /* time to live in seconds */
        DNSServiceNATPortMappingReply       callBack,
        void                                *context      /* may be NULL */
        )
        {
        char *ptr;
        size_t len;
        ipc_msg_hdr *hdr;
        union { uint16_t s; u_char b[2]; } internalPort = { internalPortInNetworkByteOrder };
        union { uint16_t s; u_char b[2]; } externalPort = { externalPortInNetworkByteOrder };

        DNSServiceErrorType err = ConnectToServer(sdRef, flags, port_mapping_request, handle_port_mapping_response, callBack, context);
        if (err) return err;    // On error ConnectToServer leaves *sdRef set to NULL

        len = sizeof(flags);
        len += sizeof(interfaceIndex);
        len += sizeof(protocol);
        len += sizeof(internalPort);
        len += sizeof(externalPort);
        len += sizeof(ttl);

        hdr = create_hdr(port_mapping_request, &len, &ptr, (*sdRef)->primary ? 1 : 0, *sdRef);
        if (!hdr) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; return kDNSServiceErr_NoMemory; }

        put_flags(flags, &ptr);
        put_uint32(interfaceIndex, &ptr);
        put_uint32(protocol, &ptr);
        *ptr++ = internalPort.b[0];
        *ptr++ = internalPort.b[1];
        *ptr++ = externalPort.b[0];
        *ptr++ = externalPort.b[1];
        put_uint32(ttl, &ptr);

        err = deliver_request(hdr, *sdRef);             // Will free hdr for us
        if (err) { DNSServiceRefDeallocate(*sdRef); *sdRef = NULL; }
        return err;
        }

#if _DNS_SD_LIBDISPATCH
DNSServiceErrorType DNSSD_API DNSServiceSetDispatchQueue
        (
        DNSServiceRef service,
        dispatch_queue_t queue
        )
        {
        int dnssd_fd  = DNSServiceRefSockFD(service);
        if (dnssd_fd == dnssd_InvalidSocket) return kDNSServiceErr_BadParam;
        if (!queue)
                {
                syslog(LOG_WARNING, "dnssd_clientstub: DNSServiceSetDispatchQueue dispatch queue NULL");
                return kDNSServiceErr_BadParam;
                }
        if (service->disp_queue)
                {
                syslog(LOG_WARNING, "dnssd_clientstub DNSServiceSetDispatchQueue dispatch queue set already");
                return kDNSServiceErr_BadParam;
                }
        if (service->disp_source)
                {
                syslog(LOG_WARNING, "DNSServiceSetDispatchQueue dispatch source set already");
                return kDNSServiceErr_BadParam;
                }
        service->disp_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, dnssd_fd, 0, queue);
        if (!service->disp_source)
                {
                syslog(LOG_WARNING, "DNSServiceSetDispatchQueue dispatch_source_create failed");
                return kDNSServiceErr_NoMemory;
                }
        service->disp_queue = queue;
        dispatch_source_set_event_handler(service->disp_source, ^{DNSServiceProcessResult(service);});
        dispatch_source_set_cancel_handler(service->disp_source, ^{dnssd_close(dnssd_fd);});
        dispatch_resume(service->disp_source);
        return kDNSServiceErr_NoError;
        }
#endif // _DNS_SD_LIBDISPATCH