mDNSResponder-567.tar.gz

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

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2002-2011 Apple Computer, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#include <mach/mach.h>
#include <mach/mach_error.h>
#include <sys/types.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>
#include <paths.h>
#include <fcntl.h>
#include <launch.h>
#include <launch_priv.h>         // for launch_socket_service_check_in()
#include <vproc.h>
#include <pwd.h>
#include <sys/event.h>
#include <pthread.h>
#include <sandbox.h>
#include <SystemConfiguration/SCDynamicStoreCopyDHCPInfo.h>
#include <asl.h>
#include <syslog.h>
#include <err.h>
#include <sysexits.h>
#include <bootstrap_priv.h>      // for bootstrap_check_in() 

#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 "xpc_services.h"           // Interface to XPC services

#include "../mDNSMacOSX/DNSServiceDiscovery.h"
#include "helper.h"

static aslclient log_client = NULL;
static aslmsg log_msg = NULL;

// Used on Embedded Side for Reading mDNSResponder Managed Preferences Profile
#if TARGET_OS_EMBEDDED
#define kmDNSEnableLoggingStr CFSTR("EnableLogging")
#define kmDNSResponderPrefIDStr "com.apple.mDNSResponder.plist"
#define kmDNSResponderPrefID CFSTR(kmDNSResponderPrefIDStr)
#endif

//*************************************************************************************************************
#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 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 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 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, mDNSNULL, mDNSInterface_Any, 0, mDNSfalse, 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, mDNSNULL);    // 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, mDNSNULL);
    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;
    si->srs.AnonData    = mDNSNULL;    

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

    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

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");
}

// 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();
    NetworkInterfaceInfoOSX     *i;
    DNSServer *s;
    McastResolver *mr;

    // Create LoggerID(Key)->com.apple.networking.mDNSResponder(Value) pair when SIGINFO is received.
    // This key-value pair is used as a condition by syslogd to Log to com.apple.networking.mDNSResponder.log file
    // present in /etc/asl/com.apple.networking.mDNSResponder.
    asl_set(log_msg, "LoggerID", "com.apple.networking.mDNSResponder");

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

    udsserver_info(&mDNSStorage);
    xpcserver_info(&mDNSStorage);

    LogMsgNoIdent("----- KQSocketEventSources -----");
    if (!gEventSources) LogMsgNoIdent("<None>");
    else
    {
        KQSocketEventSource *k;
        for (k = gEventSources; k; k=k->next)
            LogMsgNoIdent("%3d %s %s", k->fd, k->kqs.KQtask, k->fd == mDNSStorage.uds_listener_skt ? "Listener for incoming UDS clients" : " ");
    }

    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 ? "A" : " ",
                              i->ifinfo.McastTxRx ? "M" : " ",
                              !(i->ifinfo.InterfaceActive && i->ifinfo.NetWake) ? " " : !sps[0] ? "p" : "P",
                              &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(%d) ----------", NumUnicastDNSServers);
    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 %d %s %s %s %s %s",
                          s->domain.c, ifx ? ifx->ifinfo.ifname : "", ifx ? " " : "", &s->addr, mDNSVal16(s->port),
                          s->penaltyTime ? s->penaltyTime - mDNS_TimeNow(&mDNSStorage) : 0, DNSScopeToString(s->scoped),
                          s->timeout, s->resGroupID,
                          s->teststate == DNSServer_Untested ? "(Untested)" :
                          s->teststate == DNSServer_Passed   ? ""           :
                          s->teststate == DNSServer_Failed   ? "(Failed)"   :
                          s->teststate == DNSServer_Disabled ? "(Disabled)" : "(Unknown state)",
                          s->req_A ? "v4" : "!v4",  
                          s->req_AAAA ? "v6" : "!v6",
                          s->cellIntf ? "cell" : "!cell",
                          s->DNSSECAware ? "DNSSECAware" : "!DNSSECAware");
        }
    }
    mDNSs32 now = mDNS_TimeNow(&mDNSStorage);
    LogMsgNoIdent("v4answers %d", mDNSStorage.p->v4answers);
    LogMsgNoIdent("v6answers %d", mDNSStorage.p->v6answers);
    LogMsgNoIdent("Last DNS Trigger: %d ms ago", (now - mDNSStorage.p->DNSTrigger));

    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);
    }

    LogMsgNoIdent("Timenow 0x%08lX (%d)", (mDNSu32)now, now);
    LogMsg("----  END STATE LOG  ---- %s %s %d", mDNSResponderVersionString, OSXVers ? "OSXVers" : "iOSVers", OSXVers ? OSXVers : iOSVers);
    
    // If logging is disabled, only then clear the key we set at the top of this func
    if (!mDNS_LoggingEnabled)
        asl_unset(log_msg, "LoggerID");
}

mDNSlocal void DebugSetFilter()
{
    if (!log_client)
        return;

    // When USR1 is turned on, we log only the LOG_WARNING and LOG_NOTICE messages by default.
    // The user has to manually do "syslog -c mDNSResponder -i" to get the LOG_INFO messages
    // also to be logged. Most of the times, we need the INFO level messages for debugging.
    // Hence, we set the filter to INFO level when USR1 logging is turned on to avoid 
    // having the user to do this extra step manually. 

    if (mDNS_LoggingEnabled)
    {
        asl_set_filter(log_client, ASL_FILTER_MASK_UPTO(ASL_LEVEL_INFO));
        asl_set(log_msg, "LoggerID", "com.apple.networking.mDNSResponder");
        // Create LoggerID(Key)->com.apple.networking.mDNSResponder(Value) pair when USR1 Logging is Enabled.
        // This key-value pair is used as a condition by syslogd to Log to com.apple.networking.mDNSResponder.log file
        // present in /etc/asl/com.apple.networking.mDNSResponder.
    }
    else
    {
        asl_set_filter(log_client, ASL_FILTER_MASK_UPTO(ASL_LEVEL_ERR));
        asl_unset(log_msg, "LoggerID");
        // Clear the key-value pair when USR1 Logging is Disabled, as we do not want to log to 
        // com.apple.networking.mDNSResponder.log file in this case.
    }
}

mDNSexport void mDNSPlatformLogToFile(int log_level, const char *buffer)
{
    int asl_level = ASL_LEVEL_ERR;

    if (!log_client)
    {
        syslog(log_level, "%s", buffer);
        return;
    }
    switch (log_level)
    {
        case LOG_ERR:
            asl_level = ASL_LEVEL_ERR;
            break;
        case LOG_WARNING:
            asl_level = ASL_LEVEL_WARNING;
            break;
        case LOG_NOTICE:
            asl_level = ASL_LEVEL_NOTICE;
            break;
        case LOG_INFO:
            asl_level = ASL_LEVEL_INFO;
            break;
        case LOG_DEBUG:
            asl_level = ASL_LEVEL_DEBUG;
            break;
        default:
            break;
    }
    asl_log(log_client, log_msg, asl_level, "%s", buffer);
}

// Writes the state out to the dynamic store and also affects the ASL filter level
mDNSexport void UpdateDebugState()
{
    mDNSu32 one  = 1;
    mDNSu32 zero = 0;

    CFMutableDictionaryRef dict = CFDictionaryCreateMutable(NULL, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
    if (!dict)
    {
        LogMsg("UpdateDebugState: Could not create dict");
        return;
    }

    CFNumberRef numOne = CFNumberCreate(NULL, kCFNumberSInt32Type, &one);
    if (!numOne)
    {
        LogMsg("UpdateDebugState: Could not create CFNumber one");
        return;
    }
    CFNumberRef numZero = CFNumberCreate(NULL, kCFNumberSInt32Type, &zero);
    if (!numZero)
    {
        LogMsg("UpdateDebugState: Could not create CFNumber zero");
        CFRelease(numOne);
        return;
    }

    if (mDNS_LoggingEnabled)
        CFDictionarySetValue(dict, CFSTR("VerboseLogging"), numOne);
    else
        CFDictionarySetValue(dict, CFSTR("VerboseLogging"), numZero);

    if (mDNS_PacketLoggingEnabled)
        CFDictionarySetValue(dict, CFSTR("PacketLogging"), numOne);
    else
        CFDictionarySetValue(dict, CFSTR("PacketLogging"), numZero);

    if (mDNS_McastLoggingEnabled)
        CFDictionarySetValue(dict, CFSTR("McastLogging"), numOne);
    else
        CFDictionarySetValue(dict, CFSTR("McastLogging"), numZero);

    if (mDNS_McastTracingEnabled)
        CFDictionarySetValue(dict, CFSTR("McastTracing"), numOne);
    else 
        CFDictionarySetValue(dict, CFSTR("McastTracing"), numZero);

    CFRelease(numOne);
    CFRelease(numZero);
    mDNSDynamicStoreSetConfig(kmDNSDebugState, mDNSNULL, dict);
    CFRelease(dict);
    // If we turned off USR1 logging, we need to reset the filter
    DebugSetFilter();
}

#if TARGET_OS_EMBEDDED
mDNSlocal void Prefschanged()
{
    mDNSBool mDNSProf_installed;
    LogMsg("Prefschanged: mDNSResponder Managed Preferences have changed");
    mDNSProf_installed = GetmDNSManagedPref(kmDNSEnableLoggingStr);
    dispatch_async(dispatch_get_main_queue(), 
        ^{ 
            if (mDNSProf_installed)
            {
                mDNS_LoggingEnabled = mDNS_PacketLoggingEnabled = 1;
            }
            else
            {
                LogMsg("Prefschanged: mDNSDebugProfile is uninstalled -> Turning OFF USR1/USR2 Logging with SIGINFO o/p");
                INFOCallback();
                mDNS_LoggingEnabled = mDNS_PacketLoggingEnabled = 0;
            }
            UpdateDebugState();
            // If Logging Enabled: Start Logging to com.apple.networking.mDNSResponder.log (has to be LogInfo)
            LogInfo("Prefschanged: mDNSDebugProfile is installed -> Turned ON USR1/USR2 Logging");
         });
    return;
}
#endif //TARGET_OS_EMBEDDED

#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 SIGURG:
        m->mDNSOppCaching = m->mDNSOppCaching ? mDNSfalse : mDNStrue;
        LogMsg("SIGURG: Opportunistic Caching %s", m->mDNSOppCaching ? "Enabled" : "Disabled");
        // FALL THROUGH to purge the cache so that we re-do the caching based on the new setting
    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;
        UpdateDebugState();
        // If Logging Enabled: Start Logging to com.apple.networking.mDNSResponder.log 
        LogInfo("USR1 Logging Enabled: Start Logging to mDNSResponder Log file"); 
        break;
    case SIGUSR2:   mDNS_PacketLoggingEnabled = mDNS_PacketLoggingEnabled ? 0 : 1;
        LogMsg("SIGUSR2: Packet Logging %s", mDNS_PacketLoggingEnabled ? "Enabled" : "Disabled");
        mDNS_McastTracingEnabled = (mDNS_PacketLoggingEnabled && mDNS_McastLoggingEnabled) ? mDNStrue : mDNSfalse;
        LogInfo("SIGUSR2: Multicast Tracing is %s", mDNS_McastTracingEnabled ? "Enabled" : "Disabled");
        UpdateDebugState();
        break;
    case SIGPROF:  mDNS_McastLoggingEnabled = mDNS_McastLoggingEnabled ? mDNSfalse : mDNStrue;
        LogMsg("SIGPROF: Multicast Logging %s", mDNS_McastLoggingEnabled ? "Enabled" : "Disabled");
        LogMcastStateInfo(m, mDNSfalse, mDNStrue, mDNStrue);
        mDNS_McastTracingEnabled = (mDNS_PacketLoggingEnabled && mDNS_McastLoggingEnabled) ? mDNStrue : mDNSfalse;
        LogMsg("SIGPROF: Multicast Tracing is %s", mDNS_McastTracingEnabled ? "Enabled" : "Disabled");
        UpdateDebugState();
        break;
    case SIGTSTP:  mDNS_LoggingEnabled = mDNS_PacketLoggingEnabled = mDNS_McastLoggingEnabled = mDNS_McastTracingEnabled = mDNSfalse;
        LogMsg("All mDNSResponder Debug Logging/Tracing Disabled (USR1/USR2/PROF)");
        UpdateDebugState();
        break;

    default: LogMsg("SignalCallback: Unknown signal %d", msg_header->msgh_id); break;
    }
    KQueueUnlock(m, "Unix Signal");
}

// MachServerName is com.apple.mDNSResponder (Supported only till 10.9.x)
mDNSlocal kern_return_t mDNSDaemonInitialize(void)
{
    mStatus err;
    CFMachPortRef s_port;
    CFRunLoopSourceRef s_rls;
    CFRunLoopSourceRef d_rls;
    
    s_port = CFMachPortCreateWithPort(NULL, m_port, DNSserverCallback, NULL, NULL);
    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;
        UpdateDebugState();
        break;
    case SIGUSR2:   mDNS_PacketLoggingEnabled = mDNS_PacketLoggingEnabled ? 0 : 1;
        LogMsg("SIGUSR2: Packet Logging %s", mDNS_PacketLoggingEnabled ? "Enabled" : "Disabled");
        UpdateDebugState();
        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;
    dispatch_source_t mach_source;
    dispatch_queue_t queue = dispatch_get_main_queue();

    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, SIGURG);

    // 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
    {
        int ic, j;

        const void *pattern = SCDynamicStoreKeyCreateNetworkServiceEntity(NULL, kSCDynamicStoreDomainState, kSCCompAnyRegex, kSCEntNetDHCP);
        if (!pattern)
        {
            LogMsg("DHCPWakeTime: SCDynamicStoreKeyCreateNetworkServiceEntity failed\n");
            return e;
        }
        CFArrayRef dhcpinfo = CFArrayCreate(NULL, (const void **)&pattern, 1, &kCFTypeArrayCallBacks);
        CFRelease(pattern);
        if (dhcpinfo)
        {
            SCDynamicStoreRef store = SCDynamicStoreCreate(NULL, CFSTR("DHCP-LEASES"), NULL, NULL);
            if (store)
            {
                CFDictionaryRef dict = SCDynamicStoreCopyMultiple(store, NULL, dhcpinfo);
                if (dict)
                {
                    ic = CFDictionaryGetCount(dict);
                    const void *vals[ic];
                    CFDictionaryGetKeysAndValues(dict, NULL, vals);

                    for (j = 0; j < ic; j++)
                    {
                        const CFDictionaryRef dhcp = (CFDictionaryRef)vals[j];
                        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",
                                       j, start, lease, lease ? CFDataGetLength(lease) : 0);
                            else
                            {
                                const UInt8 *d = CFDataGetBytePtr(lease);
                                if (!d) LogMsg("DHCPWakeTime: CFDataGetBytePtr %d failed", j);
                                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(dict);
                }
                CFRelease(store);
            }
            CFRelease(dhcpinfo);
        }
    }
    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
    m->TimeSlept = mDNSPlatformUTC();

    // accumulate total time awake for this statistics gathering interval
    if (m->StatStartTime)
    {
        m->ActiveStatTime += (m->TimeSlept - m->StatStartTime);

        // indicate this value is invalid until reinitialzed on wakeup
        m->StatStartTime = 0;
    }

#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))
        {
            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 SetLowWater(const KQSocketSet *const k, const int r)
{
    if (setsockopt(k->sktv4, SOL_SOCKET, SO_RCVLOWAT, &r, sizeof(r)) < 0)
        LogMsg("SO_RCVLOWAT IPv4 %d error %d errno %d (%s)", k->sktv4, r, errno, strerror(errno));
    if (setsockopt(k->sktv6, SOL_SOCKET, SO_RCVLOWAT, &r, sizeof(r)) < 0)
        LogMsg("SO_RCVLOWAT IPv6 %d error %d errno %d (%s)", k->sktv6, r, errno, strerror(errno));
}

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))
            {
                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 we woke up to receive a multicast, set low-water mark to dampen excessive wakeup rate
        if (m->p->num_mcasts)
        {
            SetLowWater(&m->p->permanentsockets, 0x10000);
            if (ticks > mDNSPlatformOneSecond / 8) ticks = mDNSPlatformOneSecond / 8;
        }

#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.

        // If we changed UDP socket low-water mark, restore it, so we will be told about every packet
        if (m->p->num_mcasts)
        {
            SetLowWater(&m->p->permanentsockets, 1);
            m->p->num_mcasts = 0;
        }

        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)
{
    // Ask launchd for our socket
    launch_data_t resp_sd = launch_socket_service_check_in();
    if (!resp_sd)
    { 
        LogMsg("launch_socket_service_check_in returned NULL");
        return; 
    }
    else
    {
        launch_data_t skts = launch_data_dict_lookup(resp_sd, 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_free(resp_sd);
}

static mach_port_t RegisterMachService(const char *service_name) 
{
    mach_port_t port = MACH_PORT_NULL;
    kern_return_t kr; 

    if (KERN_SUCCESS != (kr = bootstrap_check_in(bootstrap_port, (char *)service_name, &port)))
    {   
        LogMsg("RegisterMachService: %d %X %s", kr, kr, mach_error_string(kr));
        return MACH_PORT_NULL;
    }   
    
    if (KERN_SUCCESS != (kr = mach_port_insert_right(mach_task_self(), port, port, MACH_MSG_TYPE_MAKE_SEND)))
    {   
        LogMsg("RegisterMachService: %d %X %s", kr, kr, mach_error_string(kr));
        mach_port_deallocate(mach_task_self(), port);
        return MACH_PORT_NULL;
    }   

    return port;
}

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

    if (0 == geteuid())
    {
        LogMsg("mDNSResponder cannot be run as root !! Exiting..");
        return -1;
    }

    for (i=1; i<argc; i++)
    {
        if (!strcasecmp(argv[i], "-d"                        )) mDNS_DebugMode            = 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], "-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
    signal(SIGURG,  HandleSIG);     // (Debugging) Toggle Opportunistic Caching
    signal(SIGPROF, HandleSIG);     // (Debugging) Toggle Multicast Logging
    signal(SIGTSTP, HandleSIG);     // (Debugging) Disable all Debug Logging (USR1/USR2/PROF)

#endif // MDNSRESPONDER_USES_LIB_DISPATCH_AS_PRIMARY_EVENT_LOOP_MECHANISM

    mDNSStorage.p = &PlatformStorage;   // Make sure mDNSStorage.p is set up, because validatelists uses it
    // Need to Start XPC Server Before LaunchdCheckin() (Reason: rdar11023750)
    xpc_server_init();
    LaunchdCheckin();

#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;

        int sandbox_err = sandbox_init("mDNSResponder", sandbox_flags, &sandbox_msg);
        if (sandbox_err)
        {
            LogMsg("WARNING: sandbox_init error %s", sandbox_msg);
            // If we have errors in the sandbox during development, to prevent
            // exiting, uncomment the following line.
            //sandbox_free_error(sandbox_msg);

            errx(EX_OSERR, "sandbox_init() failed: %s", sandbox_msg);
        }
        else LogInfo("Now running under Apple Sandbox restrictions");
    }
#endif // MDNS_NO_SANDBOX

    // We use BeginTransactionAtShutdown in the plist that ensures that we will
    // receive a SIGTERM during shutdown rather than a SIGKILL. But launchd (due to some
    // limitation) currently requires us to still start and end the transaction for
    // its proper initialization.
    vproc_transaction_t vt = vproc_transaction_begin(NULL);
    if (vt) vproc_transaction_end(NULL, vt);

    m_port = RegisterMachService(kmDNSResponderServName);
    // We should ALWAYS receive our Mach port from RegisterMachService() but sanity check before initializing daemon 
    if (m_port == MACH_PORT_NULL)
    {
        LogMsg("! MACH PORT IS NULL ! bootstrap_checkin failed to give a mach port");
        return -1;
    }    

    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; }

    log_client = asl_open(NULL, "mDNSResponder", 0);
    log_msg = asl_new(ASL_TYPE_MSG);
        
#if TARGET_OS_EMBEDDED
    _scprefs_observer_watch(scprefs_observer_type_global, kmDNSResponderPrefIDStr, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),  
                                                ^{   
                                                    Prefschanged();
                                                 });
#endif

    mDNSMacOSXNetworkChanged(&mDNSStorage);
    UpdateDebugState();

#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:
    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__ ")";