[apple/mdnsresponder.git] / daemon.c

/*
 * Copyright (c) 2002 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 *
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */

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

#include <mach/mach.h>
#include <mach/mach_error.h>
#include <servers/bootstrap.h>
#include <sys/types.h>
#include <unistd.h>

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

#include "mDNSClientAPI.h"                              // Defines the interface to the client layer above
#include "mDNSPlatformEnvironment.h"    // Defines the specific types needed to run mDNS on this platform
#include "mDNSsprintf.h"
#include "mDNSvsprintf.h"                               // Used to implement LogErrorMessage();

#include <DNSServiceDiscovery/DNSServiceDiscovery.h>

//*************************************************************************************************************
// Globals

static mDNS mDNSStorage;
static mDNS_PlatformSupport PlatformStorage;
#define RR_CACHE_SIZE 500
static ResourceRecord rrcachestorage[RR_CACHE_SIZE];
static const char PID_FILE[] = "/var/run/mDNSResponder.pid";

static const char kmDNSBootstrapName[] = "com.apple.mDNSResponder";
static mach_port_t client_death_port = MACH_PORT_NULL;
static mach_port_t exit_m_port       = MACH_PORT_NULL;
static mach_port_t server_priv_port  = MACH_PORT_NULL;
static CFRunLoopTimerRef DeliverInstanceTimer;

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

static int restarting_via_mach_init = 0;

#if DEBUGBREAKS
static int debug_mode = 1;
#else
static int debug_mode = 0;
#endif

//*************************************************************************************************************
// Active client list structures

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 DNSServiceBrowser_struct DNSServiceBrowser;
struct DNSServiceBrowser_struct
        {
        DNSServiceBrowser *next;
        mach_port_t ClientMachPort;
        DNSQuestion q;
        int resultType;         // Set to -1 if no outstanding reply
        char name[256], type[256], dom[256];
        };

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

typedef struct DNSServiceRegistration_struct DNSServiceRegistration;
struct DNSServiceRegistration_struct
        {
        DNSServiceRegistration *next;
        mach_port_t ClientMachPort;
        mDNSBool autoname;
        ServiceRecordSet s;
        // Don't add any fields after ServiceRecordSet.
        // This is where the implicit extra space goes if we allocate an oversized ServiceRecordSet object
        };

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

//*************************************************************************************************************
// General Utility Functions

void LogErrorMessage(const char *format, ...)
        {
        unsigned char buffer[512];
        va_list ptr;
        va_start(ptr,format);
        buffer[mDNS_vsprintf((char *)buffer, format, ptr)] = 0;
        va_end(ptr);
        openlog("mDNSResponder", LOG_CONS | LOG_PERROR | LOG_PID, LOG_DAEMON);
        fprintf(stderr, "%s\n", buffer);
        syslog(LOG_ERR, "%s", buffer);
        closelog();
        fflush(stderr);
        }

#if MACOSX_MDNS_MALLOC_DEBUGGING

char _malloc_options[] = "AXZ";

static void validatelists(mDNS *const m)
        {
        DNSServiceDomainEnumeration *e;
        DNSServiceBrowser           *b;
        DNSServiceResolver          *l;
        DNSServiceRegistration      *r;
        ResourceRecord              *rr;

        for (e = DNSServiceDomainEnumerationList; e; e=e->next)
                if (e->ClientMachPort == 0)
                        LogErrorMessage("!!!! DNSServiceDomainEnumerationList %X is garbage !!!!", e);

        for (b = DNSServiceBrowserList; b; b=b->next)
                if (b->ClientMachPort == 0)
                        LogErrorMessage("!!!! DNSServiceBrowserList %X is garbage !!!!", b);

        for (l = DNSServiceResolverList; l; l=l->next)
                if (l->ClientMachPort == 0)
                        LogErrorMessage("!!!! DNSServiceResolverList %X is garbage !!!!", l);

        for (r = DNSServiceRegistrationList; r; r=r->next)
                if (r->ClientMachPort == 0)
                        LogErrorMessage("!!!! DNSServiceRegistrationList %X is garbage !!!!", r);

        for (rr = m->ResourceRecords; rr; rr=rr->next)
                if (rr->RecordType == 0)
                        LogErrorMessage("!!!! ResourceRecords %X list is garbage !!!!");
        }

void *mallocL(char *msg, unsigned int size)
        {
        unsigned long *mem = malloc(size+8);
        if (!mem)
                { LogErrorMessage("malloc(%s:%d) failed", msg, size); return(NULL); }
        else
                {
                LogErrorMessage("malloc(%s:%d) = %X", msg, size, &mem[2]);
                mem[0] = 0xDEADBEEF;
                mem[1] = size;
                bzero(&mem[2], size);
                validatelists(&mDNSStorage);
                return(&mem[2]);
                }
        }

void freeL(char *msg, void *x)
        {
        if (!x)
                LogErrorMessage("free(%s@NULL)!", msg);
        else
                {
                unsigned long *mem = ((unsigned long *)x) - 2;
                if (mem[0] != 0xDEADBEEF)
                        { LogErrorMessage("free(%s@%X) !!!! NOT ALLOCATED !!!!", msg, &mem[2]); return; }
                if (mem[1] > 8000)
                        { LogErrorMessage("free(%s:%d@%X) too big!", msg, mem[1], &mem[2]); return; }
                LogErrorMessage("free(%s:%d@%X)", msg, mem[1], &mem[2]);
                bzero(mem, mem[1]+8);
                validatelists(&mDNSStorage);
                free(mem);
                }
        }

#endif

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

mDNSlocal void AbortClient(mach_port_t ClientMachPort)
        {
        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;
                debugf("Aborting DNSServiceDomainEnumeration %d", ClientMachPort);
                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;
                *b = (*b)->next;
                debugf("Aborting DNSServiceBrowser %d", ClientMachPort);
                mDNS_StopBrowse(&mDNSStorage, &x->q);
                freeL("DNSServiceBrowser", x);
                return;
                }

        while (*l && (*l)->ClientMachPort != ClientMachPort) l = &(*l)->next;
        if (*l)
                {
                DNSServiceResolver *x = *l;
                *l = (*l)->next;
                debugf("Aborting DNSServiceResolver %d", ClientMachPort);
                mDNS_StopResolveService(&mDNSStorage, &x->q);
                freeL("DNSServiceResolver", x);
                return;
                }

        while (*r && (*r)->ClientMachPort != ClientMachPort) r = &(*r)->next;
        if (*r)
                {
                DNSServiceRegistration *x = *r;
                *r = (*r)->next;
                mDNS_DeregisterService(&mDNSStorage, &x->s);
                // Note that we don't do the "free(x);" here -- wait for the mStatus_MemFree message
                return;
                }
        }

mDNSlocal void AbortBlockedClient(mach_port_t c, char *m)
        {
        DNSServiceDomainEnumeration **e = &DNSServiceDomainEnumerationList;
        DNSServiceBrowser           **b = &DNSServiceBrowserList;
        DNSServiceResolver          **l = &DNSServiceResolverList;
        DNSServiceRegistration      **r = &DNSServiceRegistrationList;
        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) LogErrorMessage("%5d: DomainEnumeration(%##s) stopped accepting Mach messages (%s)", c, &e[0]->dom.name, m);
        else if (*b) LogErrorMessage("%5d: Browser(%##s) stopped accepting Mach messages (%s)",      c, &b[0]->q.name, m);
        else if (*l) LogErrorMessage("%5d: Resolver(%##s) stopped accepting Mach messages (%s)",     c, &l[0]->i.name, m);
        else if (*r) LogErrorMessage("%5d: Registration(%##s) stopped accepting Mach messages (%s)", c, &r[0]->s.RR_SRV.name, m);
        else         LogErrorMessage("%5d (%s) stopped accepting Mach messages, but no record of client can be found!", c, m);

        AbortClient(c);
        }

mDNSlocal void ClientDeathCallback(CFMachPortRef unusedport, void *voidmsg, CFIndex size, void *info)
        {
        mach_msg_header_t *msg = (mach_msg_header_t *)voidmsg;
        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);

                /* Deallocate the send right that came in the dead name notification */
                mach_port_destroy( mach_task_self(), deathMessage->not_port );
                }
        }

mDNSlocal void EnableDeathNotificationForClient(mach_port_t ClientMachPort)
        {
        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)
                {
                if (ClientMachPort != (mach_port_t)-1)
                        LogErrorMessage("Client %5d died before we could enable death notification", ClientMachPort);
                AbortClient(ClientMachPort);
                }
        }

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

mDNSlocal void FoundDomain(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer)
        {
        kern_return_t status;
        #pragma unused(m)
        char buffer[256];
        DNSServiceDomainEnumerationReplyResultType rt;
        DNSServiceDomainEnumeration *x = (DNSServiceDomainEnumeration *)question->Context;

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

        if (answer->rrremainingttl > 0)
                {
                if (question == &x->dom) rt = DNSServiceDomainEnumerationReplyAddDomain;
                else                     rt = DNSServiceDomainEnumerationReplyAddDomainDefault;
                }
        else
                {
                if (question == &x->dom) rt = DNSServiceDomainEnumerationReplyRemoveDomain;
                else return;
                }

        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");
        }

mDNSexport kern_return_t provide_DNSServiceDomainEnumerationCreate_rpc(mach_port_t unusedserver, mach_port_t client,
        int regDom)
        {
        kern_return_t status;
        mStatus err;

        mDNS_DomainType dt1 = regDom ? mDNS_DomainTypeRegistration        : mDNS_DomainTypeBrowse;
        mDNS_DomainType dt2 = regDom ? mDNS_DomainTypeRegistrationDefault : mDNS_DomainTypeBrowseDefault;
        const DNSServiceDomainEnumerationReplyResultType rt = DNSServiceDomainEnumerationReplyAddDomainDefault;
        DNSServiceDomainEnumeration *x = mallocL("DNSServiceDomainEnumeration", sizeof(*x));
        if (!x) { debugf("provide_DNSServiceDomainEnumerationCreate_rpc: No memory!"); return(mStatus_NoMemoryErr); }
        x->ClientMachPort = client;
        x->next = DNSServiceDomainEnumerationList;
        DNSServiceDomainEnumerationList = x;
        
        debugf("Client %d: Enumerate %s Domains", client, regDom ? "Registration" : "Browsing");
        // We always give local. as the initial default browse domain, and then look for more
        status = DNSServiceDomainEnumerationReply_rpc(x->ClientMachPort, rt, "local.", 0, MDNS_MM_TIMEOUT);
        if (status == MACH_SEND_TIMED_OUT)
                {
                AbortBlockedClient(x->ClientMachPort, "local enumeration");
                return(mStatus_UnknownErr);
                }

        err           = mDNS_GetDomains(&mDNSStorage, &x->dom, dt1, zeroIPAddr, FoundDomain, x);
        if (!err) err = mDNS_GetDomains(&mDNSStorage, &x->def, dt2, zeroIPAddr, FoundDomain, x);

        if (err) AbortClient(client);
        else EnableDeathNotificationForClient(client);

        if (err) debugf("provide_DNSServiceDomainEnumerationCreate_rpc: mDNS_GetDomains error %d", err);
        return(err);
        }

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

mDNSlocal void DeliverInstance(DNSServiceBrowser *x, DNSServiceDiscoveryReplyFlags flags)
        {
        kern_return_t status;
        debugf("DNSServiceBrowserReply_rpc sending reply for %s (%s)", x->name,
                (flags & DNSServiceDiscoverReplyFlagsMoreComing) ? "more coming" : "last in batch");
        status = DNSServiceBrowserReply_rpc(x->ClientMachPort, x->resultType, x->name, x->type, x->dom, flags, MDNS_MM_TIMEOUT);
        x->resultType = -1;
        if (status == MACH_SEND_TIMED_OUT)
                AbortBlockedClient(x->ClientMachPort, "browse");
        }

mDNSlocal void DeliverInstanceTimerCallBack(CFRunLoopTimerRef timer, void *info)
        {
        DNSServiceBrowser *b = DNSServiceBrowserList;
        (void)timer;    // Parameter not used

        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->resultType != -1)
                        DeliverInstance(x, 0);
                }
        }

mDNSlocal void FoundInstance(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer)
        {
        DNSServiceBrowser *x = (DNSServiceBrowser *)question->Context;
        domainlabel name;
        domainname type, domain;
        
        if (answer->rrtype != kDNSType_PTR)
                {
                debugf("FoundInstance: Should not be called with rrtype %d (not a PTR record)", answer->rrtype);
                return;
                }
        
        if (!DeconstructServiceName(&answer->rdata->u.name, &name, &type, &domain))
                {
                debugf("FoundInstance: %##s PTR %##s is not valid NIAS service pointer", &answer->name, &answer->rdata->u.name);
                return;
                }

        if (x->resultType != -1) DeliverInstance(x, DNSServiceDiscoverReplyFlagsMoreComing);

        debugf("FoundInstance: %##s", answer->rdata->u.name.c);
        ConvertDomainLabelToCString_unescaped(&name, x->name);
        ConvertDomainNameToCString(&type, x->type);
        ConvertDomainNameToCString(&domain, x->dom);
        if (answer->rrremainingttl)
                 x->resultType = DNSServiceBrowserReplyAddInstance;
        else x->resultType = DNSServiceBrowserReplyRemoveInstance;

        // We schedule this timer 1/10 second in the future because CFRunLoop doesn't respect
        // the relative priority between CFSocket and CFRunLoopTimer, and continues to call
        // the timer callback even though there are packets waiting to be processed.
        CFRunLoopTimerSetNextFireDate(DeliverInstanceTimer, CFAbsoluteTimeGetCurrent() + 0.1);
        }

mDNSexport kern_return_t provide_DNSServiceBrowserCreate_rpc(mach_port_t unusedserver, mach_port_t client,
        DNSCString regtype, DNSCString domain)
        {
        mStatus err;
        domainname t, d;
        DNSServiceBrowser *x = mallocL("DNSServiceBrowser", sizeof(*x));
        if (!x) { debugf("provide_DNSServiceBrowserCreate_rpc: No memory!"); return(mStatus_NoMemoryErr); }
        x->ClientMachPort = client;
        x->resultType = -1;
        x->next = DNSServiceBrowserList;
        DNSServiceBrowserList = x;

        ConvertCStringToDomainName(regtype, &t);
        ConvertCStringToDomainName(*domain ? domain : "local.", &d);

        debugf("Client %d: provide_DNSServiceBrowserCreate_rpc", client);
        debugf("Client %d: Browse for Services: %##s%##s", client, &t, &d);
        err = mDNS_StartBrowse(&mDNSStorage, &x->q, &t, &d, zeroIPAddr, FoundInstance, x);

        if (err) AbortClient(client);
        else EnableDeathNotificationForClient(client);

        if (err) debugf("provide_DNSServiceBrowserCreate_rpc: mDNS_StartBrowse error %d", err);
        return(err);
        }

//*************************************************************************************************************
// Resolve Service Info

mDNSlocal void FoundInstanceInfo(mDNS *const m, ServiceInfoQuery *query)
        {
        kern_return_t status;
        DNSServiceResolver *x = (DNSServiceResolver *)query->Context;
        struct sockaddr_in interface;
        struct sockaddr_in address;
        char cstring[1024];
        int i, pstrlen = query->info->TXTinfo[0];

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

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

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

        interface.sin_len         = sizeof(interface);
        interface.sin_family      = AF_INET;
        interface.sin_port        = 0;
        interface.sin_addr.s_addr = query->info->InterfaceAddr.NotAnInteger;
        
        address.sin_len           = sizeof(address);
        address.sin_family        = AF_INET;
        address.sin_port          = query->info->port.NotAnInteger;
        address.sin_addr.s_addr   = query->info->ip.NotAnInteger;

        // 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
        
        status = DNSServiceResolverReply_rpc(x->ClientMachPort,
                (char*)&interface, (char*)&address, cstring, 0, MDNS_MM_TIMEOUT);
        if (status == MACH_SEND_TIMED_OUT)
                AbortBlockedClient(x->ClientMachPort, "resolve");
        }

mDNSexport kern_return_t provide_DNSServiceResolverResolve_rpc(mach_port_t unusedserver, mach_port_t client,
        DNSCString name, DNSCString regtype, DNSCString domain)
        {
        mStatus err;
        domainlabel n;
        domainname t, d;
        DNSServiceResolver *x = mallocL("DNSServiceResolver", sizeof(*x));
        if (!x) { debugf("provide_DNSServiceResolverResolve_rpc: No memory!"); return(mStatus_NoMemoryErr); }
        x->ClientMachPort = client;
        x->next = DNSServiceResolverList;
        DNSServiceResolverList = x;

        ConvertCStringToDomainLabel(name, &n);
        ConvertCStringToDomainName(regtype, &t);
        ConvertCStringToDomainName(*domain ? domain : "local.", &d);
        ConstructServiceName(&x->i.name, &n, &t, &d);
        x->i.InterfaceAddr = zeroIPAddr;

        debugf("Client %d: provide_DNSServiceResolverResolve_rpc", client);
        debugf("Client %d: Resolve Service: %##s", client, &x->i.name);
        err = mDNS_StartResolveService(&mDNSStorage, &x->q, &x->i, FoundInstanceInfo, x);

        if (err) AbortClient(client);
        else EnableDeathNotificationForClient(client);

        if (err) debugf("provide_DNSServiceResolverResolve_rpc: mDNS_StartResolveService error %d", err);
        return(err);
        }

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

mDNSlocal void FreeDNSServiceRegistration(DNSServiceRegistration *x)
        {
        while (x->s.Extras)
                {
                ExtraResourceRecord *extras = x->s.Extras;
                x->s.Extras = x->s.Extras->next;
                if (extras->r.rdata != &extras->r.rdatastorage)
                        freeL("Extra RData", extras->r.rdata);
                freeL("ExtraResourceRecord", extras);
                }

        if (x->s.RR_TXT.rdata != &x->s.RR_TXT.rdatastorage)
                        freeL("TXT RData", x->s.RR_TXT.rdata);

        freeL("DNSServiceRegistration", x);
        }

mDNSlocal void RegCallback(mDNS *const m, ServiceRecordSet *const sr, mStatus result)
        {
        DNSServiceRegistration *x = (DNSServiceRegistration*)sr->Context;

        switch (result)
                {
                case mStatus_NoError:      debugf("RegCallback: %##s Name Registered",   sr->RR_SRV.name.c); break;
                case mStatus_NameConflict: debugf("RegCallback: %##s Name Conflict",     sr->RR_SRV.name.c); break;
                case mStatus_MemFree:      debugf("RegCallback: %##s Memory Free",       sr->RR_SRV.name.c); break;
                default:                   debugf("RegCallback: %##s Unknown Result %d", sr->RR_SRV.name.c, result); break;
                }

        if (result == mStatus_NoError)
                {
                kern_return_t status = DNSServiceRegistrationReply_rpc(x->ClientMachPort, result, MDNS_MM_TIMEOUT);
                if (status == MACH_SEND_TIMED_OUT)
                        AbortBlockedClient(x->ClientMachPort, "registration success");
                }

        if (result == mStatus_NameConflict)
                {
                // 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 (x->autoname)
                        mDNS_RenameAndReregisterService(m, sr);
                else
                        {
                        kern_return_t status;
                        // AbortClient unlinks our DNSServiceRegistration from the list so we can safely free it
                        AbortClient(x->ClientMachPort);
                        status = DNSServiceRegistrationReply_rpc(x->ClientMachPort, result, MDNS_MM_TIMEOUT);
                        if (status == MACH_SEND_TIMED_OUT)
                                AbortBlockedClient(x->ClientMachPort, "registration conflict"); // Yes, this IS safe :-)
                        FreeDNSServiceRegistration(x);
                        }
                }

        if (result == mStatus_MemFree)
                {
                DNSServiceRegistration **r = &DNSServiceRegistrationList;
                while (*r && *r != x) r = &(*r)->next;
                if (*r)
                        {
                        debugf("RegCallback: %##s Still in DNSServiceRegistration list; removing now", sr->RR_SRV.name.c);
                        *r = (*r)->next;
                        }
                debugf("RegCallback: Freeing DNSServiceRegistration %##s %d", sr->RR_SRV.name.c, x->ClientMachPort);
                FreeDNSServiceRegistration(x);
                }
        }

mDNSlocal void CheckForDuplicateRegistrations(DNSServiceRegistration *x, domainlabel *n, domainname *t, domainname *d)
        {
        char name[256];
        int count = 0;
        ResourceRecord *rr;
        domainname srvname;
        ConstructServiceName(&srvname, n, t, d);
        mDNS_sprintf(name, "%##s", &srvname);

        for (rr = mDNSStorage.ResourceRecords; rr; rr=rr->next)
                if (rr->rrtype == kDNSType_SRV && SameDomainName(&rr->name, &srvname))
                        count++;

        if (count)
                {
                debugf("Client %5d   registering Service Record Set \"%##s\"; WARNING! now have %d instances",
                        x->ClientMachPort, &srvname, count+1);
                LogErrorMessage("%5d: WARNING! Bogus client application has now registered %d identical instances of service %##s",
                        x->ClientMachPort, count+1, &srvname);
                }
        }

mDNSexport kern_return_t provide_DNSServiceRegistrationCreate_rpc(mach_port_t unusedserver, mach_port_t client,
        DNSCString name, DNSCString regtype, DNSCString domain, int notAnIntPort, DNSCString txtRecord)
        {
        mStatus err;
        domainlabel n;
        domainname t, d;
        mDNSIPPort port;
        unsigned char txtinfo[1024] = "";
        int data_len = 0;
        int size = sizeof(RDataBody);
        unsigned char *pstring = &txtinfo[data_len];
        char *ptr = txtRecord;
        DNSServiceRegistration *x;

        // 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)) return(mStatus_BadParamErr);
                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) return(mStatus_BadParamErr);
                        pstring[++pstring[0]] = *ptr++;
                        }
                }

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

        x = mallocL("DNSServiceRegistration", sizeof(*x) - sizeof(RDataBody) + size);
        if (!x) { debugf("provide_DNSServiceRegistrationCreate_rpc: No memory!"); return(mStatus_NoMemoryErr); }
        x->ClientMachPort = client;
        x->next = DNSServiceRegistrationList;
        DNSServiceRegistrationList = x;

        x->autoname = (*name == 0);
        if (x->autoname) n = mDNSStorage.nicelabel;
        else ConvertCStringToDomainLabel(name, &n);
        ConvertCStringToDomainName(regtype, &t);
        ConvertCStringToDomainName(*domain ? domain : "local.", &d);
        port.NotAnInteger = notAnIntPort;

        debugf("Client %d: provide_DNSServiceRegistrationCreate_rpc", client);
        debugf("Client %d: Register Service: %#s.%##s%##s %d %.30s",
                client, &n, &t, &d, (int)port.b[0] << 8 | port.b[1], txtRecord);
        CheckForDuplicateRegistrations(x, &n, &t, &d);
        err = mDNS_RegisterService(&mDNSStorage, &x->s, &n, &t, &d, mDNSNULL, port, txtinfo, data_len, RegCallback, x);

        if (err) AbortClient(client);
        else EnableDeathNotificationForClient(client);

        if (err) debugf("provide_DNSServiceRegistrationCreate_rpc: mDNS_RegisterService error %d", err);
        else debugf("Made Service Record Set for %##s", &x->s.RR_SRV.name);

        return(err);
        }

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)
        {
        mStatus err;
        DNSServiceRegistration *x = DNSServiceRegistrationList;
        ExtraResourceRecord *extra;
        int size = sizeof(RDataBody);
        if (size < data_len)
                size = data_len;
        
        // Find this registered service
        while (x && x->ClientMachPort != client) x = x->next;
        if (!x)
                {
                debugf("provide_DNSServiceRegistrationAddRecord_rpc bad client %X", client);
                return(mStatus_BadReferenceErr);
                }

        // Allocate storage for our new record
        extra = mallocL("ExtraResourceRecord", sizeof(*extra) - sizeof(RDataBody) + size);
        if (!extra) return(mStatus_NoMemoryErr);

        // Fill in type, length, and data
        extra->r.rrtype = type;
        extra->r.rdatastorage.MaxRDLength = size;
        extra->r.rdatastorage.RDLength    = data_len;
        memcpy(&extra->r.rdatastorage.u.data, data, data_len);
        
        // And register it
        err = mDNS_AddRecordToService(&mDNSStorage, &x->s, extra, &extra->r.rdatastorage, ttl);
        *reference = (natural_t)extra;
        debugf("Received a request to add the record of type: %d length: %d; returned reference %X",
                type, data_len, *reference);
        return(err);
        }

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

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)
        {
        mStatus err;
        DNSServiceRegistration *x = DNSServiceRegistrationList;
        ResourceRecord *rr;
        RData *newrdata;
        int size = sizeof(RDataBody);
        if (size < data_len)
                size = data_len;

        // Find this registered service
        while (x && x->ClientMachPort != client) x = x->next;
        if (!x)
                {
                debugf("provide_DNSServiceRegistrationUpdateRecord_rpc bad client %X", client);
                return(mStatus_BadReferenceErr);
                }
        
        // Find the record we're updating
        if (!reference) // NULL reference means update the primary TXT record
                rr = &x->s.RR_TXT;
        else                    // Else, scan our list to make sure we're updating a valid record that was previously added
                {
                ExtraResourceRecord *e = x->s.Extras;
                while (e && e != (ExtraResourceRecord*)reference) e = e->next;
                if (!e)
                        {
                        debugf("provide_DNSServiceRegistrationUpdateRecord_rpc failed to find record %X", reference);
                        return(mStatus_BadReferenceErr);
                        }
                rr = &e->r;
                }

        // Allocate storage for our new data
        newrdata = mallocL("RData", sizeof(*newrdata) - sizeof(RDataBody) + size);
        if (!newrdata) return(mStatus_NoMemoryErr);

        // Fill in new length, and data
        newrdata->MaxRDLength = size;
        newrdata->RDLength    = data_len;
        memcpy(&newrdata->u, data, data_len);
        
        // And update our record
        err = mDNS_Update(&mDNSStorage, rr, ttl, newrdata, UpdateCallback);
        if (err)
                {
                debugf("Received a request to update the record of length: %d for reference: %X; failed %d",
                        data_len, reference, err);
                return(err);
                }

        debugf("Received a request to update the record of length: %d for reference: %X", data_len, reference);
        return(err);
        }

mDNSexport kern_return_t provide_DNSServiceRegistrationRemoveRecord_rpc(mach_port_t unusedserver, mach_port_t client,
        natural_t reference)
        {
        mStatus err;
        DNSServiceRegistration *x = DNSServiceRegistrationList;
        ExtraResourceRecord *extra = (ExtraResourceRecord*)reference;
        
        // Find this registered service
        while (x && x->ClientMachPort != client) x = x->next;
        if (!x)
                {
                LogErrorMessage("DNSServiceRegistrationRemoveRecord Client %5d not found", client);
                debugf("provide_DNSServiceRegistrationRemoveRecord_rpc bad client %X", client);
                return(mStatus_BadReferenceErr);
                }

        err = mDNS_RemoveRecordFromService(&mDNSStorage, &x->s, extra);
        if (err)
                {
                LogErrorMessage("DNSServiceRegistrationRemoveRecord Client %5d does not have record %X", client, extra);
                debugf("Received a request to remove the record of reference: %X (failed %d)", extra, err);
                return(err);
                }

        debugf("Received a request to remove the record of reference: %X", extra);
        if (extra->r.rdata != &extra->r.rdatastorage)
                freeL("Extra RData", extra->r.rdata);
        freeL("ExtraResourceRecord", extra);
        return(err);
        }

//*************************************************************************************************************
// Support Code

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;

        /* 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);
            return;
                        }

        /*
         * 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);
        return;
                }

    /*
     * 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);
        }

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

        debugf("Registering Bootstrap Service");

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

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

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

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

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

mDNSlocal void ExitCallback(CFMachPortRef port, void *msg, CFIndex size, void *info)
        {
        debugf("ExitCallback: destroyBootstrapService");
        if (!debug_mode)
                destroyBootstrapService();

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

        debugf("ExitCallback: mDNS_Close");
        mDNS_Close(&mDNSStorage);
        exit(0);
        }

mDNSlocal kern_return_t start(const char *bundleName, const char *bundleDir)
        {
        mStatus            err;
        CFRunLoopTimerContext myCFRunLoopTimerContext = { 0, &mDNSStorage, NULL, NULL, NULL };
        CFMachPortRef      d_port = CFMachPortCreate(NULL, ClientDeathCallback, NULL, NULL);
        CFMachPortRef      s_port = CFMachPortCreate(NULL, DNSserverCallback, NULL, NULL);
        CFMachPortRef      e_port = CFMachPortCreate(NULL, ExitCallback, NULL, NULL);
        mach_port_t        m_port = CFMachPortGetPort(s_port);
        kern_return_t      status = bootstrap_register(bootstrap_port, DNS_SERVICE_DISCOVERY_SERVER, m_port);
        CFRunLoopSourceRef d_rls  = CFMachPortCreateRunLoopSource(NULL, d_port, 0);
        CFRunLoopSourceRef s_rls  = CFMachPortCreateRunLoopSource(NULL, s_port, 0);
        CFRunLoopSourceRef e_rls  = CFMachPortCreateRunLoopSource(NULL, e_port, 0);
        
        if (status)
                {
                if (status == 1103)
                        LogErrorMessage("Bootstrap_register failed(): A copy of the daemon is apparently already running");
                else
                        LogErrorMessage("Bootstrap_register failed(): %s %d", mach_error_string(status), status);
                return(status);
                }

        // Note: Every CFRunLoopTimer has to be created with an initial fire time, and a repeat interval, or it becomes
        // a one-shot timer and you can't use CFRunLoopTimerSetNextFireDate(timer, when) to schedule subsequent firings.
        // Here we create it with an initial fire time 24 hours from now, and a repeat interval of 24 hours, with
        // the intention that we'll actually reschedule it using CFRunLoopTimerSetNextFireDate(timer, when) as necessary.
        DeliverInstanceTimer = CFRunLoopTimerCreate(kCFAllocatorDefault,
                                                        CFAbsoluteTimeGetCurrent() + 24.0*60.0*60.0, 24.0*60.0*60.0,
                                                        0, // no flags
                                                        9, // low priority execution (after all packets, etc., have been handled).
                                                        DeliverInstanceTimerCallBack, &myCFRunLoopTimerContext);
        if (!DeliverInstanceTimer) return(-1);
        CFRunLoopAddTimer(CFRunLoopGetCurrent(), DeliverInstanceTimer, kCFRunLoopDefaultMode);
        
        err = mDNS_Init(&mDNSStorage, &PlatformStorage, rrcachestorage, RR_CACHE_SIZE, NULL, NULL);
        if (err) { LogErrorMessage("Daemon start: mDNS_Init failed %ld", err); return(err); }

        client_death_port = CFMachPortGetPort(d_port);
        exit_m_port = CFMachPortGetPort(e_port);

        CFRunLoopAddSource(CFRunLoopGetCurrent(), d_rls, kCFRunLoopDefaultMode);
        CFRunLoopAddSource(CFRunLoopGetCurrent(), s_rls, kCFRunLoopDefaultMode);
        CFRunLoopAddSource(CFRunLoopGetCurrent(), e_rls, kCFRunLoopDefaultMode);
        CFRelease(d_rls);
        CFRelease(s_rls);
        CFRelease(e_rls);
        if (debug_mode) printf("Service registered with Mach Port %d\n", m_port);

        return(err);
        }

mDNSlocal void HandleSIG(int signal)
        {
        debugf("");
        debugf("HandleSIG");
        
        // Send a mach_msg to ourselves (since that is signal safe) telling us to cleanup and exit
        mach_msg_return_t msg_result;
        mach_msg_header_t header;

        header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND, 0);
        header.msgh_remote_port = exit_m_port;
        header.msgh_local_port = MACH_PORT_NULL;
        header.msgh_size = sizeof(header);
        header.msgh_id = 0;

        msg_result = mach_msg_send(&header);
        }

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

        for (i=1; i<argc; i++)
                {
                if (!strcmp(argv[i], "-d")) debug_mode = 1;
                }

        signal(SIGINT, HandleSIG);      // SIGINT is what you get for a Ctrl-C
        signal(SIGTERM, HandleSIG);

        // Register the server with mach_init for automatic restart only during debug mode
    if (!debug_mode)
                registerBootstrapService();

        if (!debug_mode && !restarting_via_mach_init)
                exit(0); /* mach_init will restart us immediately as a daemon */

        fp = fopen(PID_FILE, "w");
        if (fp != NULL)
                {
                fprintf(fp, "%d\n", getpid());
                fclose(fp);
                }
        
        LogErrorMessage("mDNSResponder (%s %s) starting", __DATE__, __TIME__);
        status = start(NULL, NULL);

        if (status == 0)
                {
                CFRunLoopRun();
                LogErrorMessage("CFRunLoopRun Exiting. This is bad.");
                mDNS_Close(&mDNSStorage);
                }

        destroyBootstrapService();

        return(status);
        }