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

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2003-2006 Apple Computer, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.

        Change History (most recent first):

$Log: uds_daemon.c,v $
Revision 1.366  2007/10/10 00:48:54  cheshire
<rdar://problem/5526379> Daemon spins in an infinite loop when it doesn't get the control message it's expecting

Revision 1.365  2007/10/06 03:25:23  cheshire
<rdar://problem/5525267> MacBuddy exits abnormally when clicking "Continue" in AppleConnect pane

Revision 1.364  2007/10/06 03:20:16  cheshire
Improved LogOperation debugging messages

Revision 1.363  2007/10/05 23:24:52  cheshire
Improved LogOperation messages about separate error return socket

Revision 1.362  2007/10/05 22:11:58  cheshire
Improved "send_msg ERROR" debugging message

Revision 1.361  2007/10/04 20:45:18  cheshire
<rdar://problem/5518381> Race condition in kDNSServiceFlagsShareConnection-mode call handling

Revision 1.360  2007/10/01 23:24:46  cheshire
SIGINFO output was mislabeling mDNSInterface_Any queries as unicast queries

Revision 1.359  2007/09/30 00:09:27  cheshire
<rdar://problem/5492315> Pass socket fd via SCM_RIGHTS sendmsg instead of using named UDS in the filesystem

Revision 1.358  2007/09/29 20:08:06  cheshire
Fixed typo in comment

Revision 1.357  2007/09/27 22:10:04  cheshire
Add LogOperation line for DNSServiceRegisterRecord callbacks

Revision 1.356  2007/09/26 21:29:30  cheshire
Improved question list SIGINFO output

Revision 1.355  2007/09/26 01:54:34  mcguire
Debugging: In SIGINFO output, show ClientTunnel query interval, which is how we determine whether a query is still active

Revision 1.354  2007/09/26 01:26:31  cheshire
<rdar://problem/5501567> BTMM: mDNSResponder crashes in free_service_instance enabling/disabling BTMM
Need to call SendServiceRemovalNotification *before* backpointer is cleared

Revision 1.353  2007/09/25 20:46:33  cheshire
Include DNSServiceRegisterRecord operations in SIGINFO output

Revision 1.352  2007/09/25 20:23:40  cheshire
<rdar://problem/5501567> BTMM: mDNSResponder crashes in free_service_instance enabling/disabling BTMM
Need to clear si->request backpointer before calling mDNS_DeregisterService(&mDNSStorage, &si->srs);

Revision 1.351  2007/09/25 18:20:34  cheshire
Changed name of "free_service_instance" to more accurate "unlink_and_free_service_instance"

Revision 1.350  2007/09/24 23:54:52  mcguire
Additional list checking in uds_validatelists()

Revision 1.349  2007/09/24 06:01:00  cheshire
Debugging: In SIGINFO output, show NAT Traversal time values in seconds rather than platform ticks

Revision 1.348  2007/09/24 05:02:41  cheshire
Debugging: In SIGINFO output, indicate explicitly when a given section is empty

Revision 1.347  2007/09/21 02:04:33  cheshire
<rdar://problem/5440831> BTMM: mDNSResponder crashes in free_service_instance enabling/disabling BTMM

Revision 1.346  2007/09/19 22:47:25  cheshire
<rdar://problem/5490182> Memory corruption freeing a "no such service" service record

Revision 1.345  2007/09/19 20:32:29  cheshire
<rdar://problem/5482322> BTMM: Don't advertise SMB with BTMM because it doesn't support IPv6

Revision 1.344  2007/09/19 19:27:50  cheshire
<rdar://problem/5492182> Improved diagnostics when daemon can't connect to error return path socket

Revision 1.343  2007/09/18 21:42:30  cheshire
To reduce programming mistakes, renamed ExtPort to RequestedPort

Revision 1.342  2007/09/14 22:38:20  cheshire
Additional list checking in uds_validatelists()

Revision 1.341  2007/09/13 00:16:43  cheshire
<rdar://problem/5468706> Miscellaneous NAT Traversal improvements

Revision 1.340  2007/09/12 23:03:08  cheshire
<rdar://problem/5476978> DNSServiceNATPortMappingCreate callback not giving correct interface index

Revision 1.339  2007/09/12 19:22:21  cheshire
Variable renaming in preparation for upcoming fixes e.g. priv/pub renamed to intport/extport
Made NAT Traversal packet handlers take typed data instead of anonymous "mDNSu8 *" byte pointers

Revision 1.338  2007/09/12 01:22:13  cheshire
Improve validatelists() checking to detect when 'next' pointer gets smashed to ~0

Revision 1.337  2007/09/07 23:05:04  cheshire
Add display of client_context field in handle_cancel_request() LogOperation message
While loop was checking client_context.u32[2] instead of client_context.u32[1]

Revision 1.336  2007/09/07 20:56:03  cheshire
Renamed uint32_t field in client_context_t from "ptr64" to more accurate name "u32"

Revision 1.335  2007/09/05 22:25:01  vazquez
<rdar://problem/5400521> update_record mDNSResponder leak

Revision 1.334  2007/09/05 20:43:57  cheshire
Added LogOperation message showing fd of socket listening for incoming Unix Domain Socket client requests

Revision 1.333  2007/08/28 23:32:35  cheshire
Added LogOperation messages for DNSServiceNATPortMappingCreate() operations

Revision 1.332  2007/08/27 22:59:31  cheshire
Show reg_index in DNSServiceRegisterRecord/DNSServiceRemoveRecord messages

Revision 1.331  2007/08/27 20:29:57  cheshire
Added SIGINFO listing of TunnelClients

Revision 1.330  2007/08/24 23:46:50  cheshire
Added debugging messages and SIGINFO listing of DomainAuthInfo records

Revision 1.329  2007/08/18 01:02:04  mcguire
<rdar://problem/5415593> No Bonjour services are getting registered at boot

Revision 1.328  2007/08/15 20:18:28  vazquez
<rdar://problem/5400521> update_record mDNSResponder leak
Make sure we free all ExtraResourceRecords

Revision 1.327  2007/08/08 22:34:59  mcguire
<rdar://problem/5197869> Security: Run mDNSResponder as user id mdnsresponder instead of root

Revision 1.326  2007/08/01 16:09:14  cheshire
Removed unused NATTraversalInfo substructure from AuthRecord; reduced structure sizecheck values accordingly

Revision 1.325  2007/07/31 21:29:41  cheshire
<rdar://problem/5372207> System Default registration domain(s) not listed in Domain Enumeration ("dns-sd -E")

Revision 1.324  2007/07/31 01:56:21  cheshire
Corrected function name in log message

Revision 1.323  2007/07/27 23:57:23  cheshire
Added compile-time structure size checks

Revision 1.322  2007/07/27 19:37:19  cheshire
Moved AutomaticBrowseDomainQ into main mDNS object

Revision 1.321  2007/07/27 19:30:41  cheshire
Changed mDNSQuestionCallback parameter from mDNSBool to QC_result,
to properly reflect tri-state nature of the possible responses

Revision 1.320  2007/07/27 00:48:27  cheshire
<rdar://problem/4700198> BTMM: Services should only get registered in .Mac domain of current user
<rdar://problem/4731180> BTMM: Only browse in the current user's .Mac domain by default

Revision 1.319  2007/07/24 17:23:33  cheshire
<rdar://problem/5357133> Add list validation checks for debugging

Revision 1.318  2007/07/23 23:09:51  cheshire
<rdar://problem/5351997> Reject oversized client requests

Revision 1.317  2007/07/23 22:24:47  cheshire
<rdar://problem/5352299> Make mDNSResponder more defensive against malicious local clients
Additional refinements

Revision 1.316  2007/07/23 22:12:53  cheshire
<rdar://problem/5352299> Make mDNSResponder more defensive against malicious local clients

Revision 1.315  2007/07/21 01:36:13  cheshire
Need to also add ".local" as automatic browsing domain

Revision 1.314  2007/07/20 20:12:37  cheshire
Rename "mDNS_DomainTypeBrowseLegacy" as "mDNS_DomainTypeBrowseAutomatic"

Revision 1.313  2007/07/20 00:54:21  cheshire
<rdar://problem/4641118> Need separate SCPreferences for per-user .Mac settings

Revision 1.312  2007/07/11 03:06:43  cheshire
<rdar://problem/5303807> Register IPv6-only hostname and don't create port mappings for AutoTunnel services

Revision 1.311  2007/07/06 21:19:18  cheshire
Add list of NAT traversals to SIGINFO output

Revision 1.310  2007/07/03 19:56:50  cheshire
Add LogOperation message for DNSServiceSetDefaultDomainForUser

Revision 1.309  2007/06/29 23:12:49  vazquez
<rdar://problem/5294103> Stop using generate_final_fatal_reply_with_garbage

Revision 1.308  2007/06/29 00:10:07  vazquez
<rdar://problem/5301908> Clean up NAT state machine (necessary for 6 other fixes)

Revision 1.307  2007/05/25 00:25:44  cheshire
<rdar://problem/5227737> Need to enhance putRData to output all current known types

Revision 1.306  2007/05/24 22:31:35  vazquez
Bug #: 4272956
Reviewed by: Stuart Cheshire
<rdar://problem/4272956> WWDC API: Return ADD/REMOVE events in registration callback

Revision 1.305  2007/05/23 18:59:22  cheshire
Remove unnecessary IPC_FLAGS_REUSE_SOCKET

Revision 1.304  2007/05/22 01:07:42  cheshire
<rdar://problem/3563675> API: Need a way to get version/feature information

Revision 1.303  2007/05/22 00:32:58  cheshire
Make a send_all() subroutine -- will be helpful for implementing DNSServiceGetProperty(DaemonVersion)

Revision 1.302  2007/05/21 18:54:54  cheshire
Add "Cancel" LogOperation message when we get a cancel_request command over the UDS

Revision 1.301  2007/05/18 23:55:22  cheshire
<rdar://problem/4454655> Allow multiple register/browse/resolve operations to share single Unix Domain Socket

Revision 1.300  2007/05/18 21:27:11  cheshire
Rename connected_registration_termination to connection_termination

Revision 1.299  2007/05/18 21:24:34  cheshire
Rename rstate to request

Revision 1.298  2007/05/18 21:22:35  cheshire
Convert uint16_t etc. to their locally-defined equivalents, like the rest of the core code

Revision 1.297  2007/05/18 20:33:11  cheshire
Avoid declaring lots of uninitialized variables in read_rr_from_ipc_msg

Revision 1.296  2007/05/18 19:04:19  cheshire
Rename msgdata to msgptr (may be modified); rename (currently unused) bufsize to msgend

Revision 1.295  2007/05/18 17:57:13  cheshire
Reorder functions in file to arrange them in logical groups; added "#pragma mark" headers for each group

Revision 1.294  2007/05/17 20:58:22  cheshire
<rdar://problem/4647145> DNSServiceQueryRecord should return useful information with NXDOMAIN

Revision 1.293  2007/05/17 19:46:20  cheshire
Routine name deliver_async_error() is misleading. What it actually does is write a message header
(containing an error code) followed by 256 bytes of garbage zeroes onto a client connection,
thereby trashing it and making it useless for any subsequent communication. It's destructive,
and not very useful. Changing name to generate_final_fatal_reply_with_garbage().

Revision 1.292  2007/05/16 01:06:52  cheshire
<rdar://problem/4471320> Improve reliability of kDNSServiceFlagsMoreComing flag on multiprocessor machines

Revision 1.291  2007/05/15 21:57:16  cheshire
<rdar://problem/4608220> Use dnssd_SocketValid(x) macro instead of just
assuming that all negative values (or zero!) are invalid socket numbers

Revision 1.290  2007/05/10 23:30:57  cheshire
<rdar://problem/4084490> Only one browse gets remove events when disabling browse domain

Revision 1.289  2007/05/02 22:18:08  cheshire
Renamed NATTraversalInfo_struct context to NATTraversalContext

Revision 1.288  2007/04/30 21:33:39  cheshire
Fix crash when a callback unregisters a service while the UpdateSRVRecords() loop
is iterating through the m->ServiceRegistrations list

Revision 1.287  2007/04/27 19:03:22  cheshire
Check q->LongLived not q->llq to tell if a query is LongLived

Revision 1.286  2007/04/26 16:00:01  cheshire
Show interface number in DNSServiceBrowse RESULT output

Revision 1.285  2007/04/22 19:03:39  cheshire
Minor code tidying

Revision 1.284  2007/04/22 06:02:03  cheshire
<rdar://problem/4615977> Query should immediately return failure when no server

Revision 1.283  2007/04/21 21:47:47  cheshire
<rdar://problem/4376383> Daemon: Add watchdog timer

Revision 1.282  2007/04/20 21:17:24  cheshire
For naming consistency, kDNSRecordTypeNegative should be kDNSRecordTypePacketNegative

Revision 1.281  2007/04/19 23:25:20  cheshire
Added debugging message

Revision 1.280  2007/04/17 19:21:29  cheshire
<rdar://problem/5140339> Domain discovery not working over VPN

Revision 1.279  2007/04/16 21:53:49  cheshire
Improve display of negative cache entries

Revision 1.278  2007/04/16 20:49:40  cheshire
Fix compile errors for mDNSPosix build

Revision 1.277  2007/04/05 22:55:36  cheshire
<rdar://problem/5077076> Records are ending up in Lighthouse without expiry information

Revision 1.276  2007/04/05 19:20:13  cheshire
Non-blocking mode not being set correctly -- was clobbering other flags

Revision 1.275  2007/04/04 21:21:25  cheshire
<rdar://problem/4546810> Fix crash: In regservice_callback service_instance was being referenced after being freed

Revision 1.274  2007/04/04 01:30:42  cheshire
<rdar://problem/5075200> DNSServiceAddRecord is failing to advertise NULL record
Add SIGINFO output lising our advertised Authoritative Records

Revision 1.273  2007/04/04 00:03:27  cheshire
<rdar://problem/5089862> DNSServiceQueryRecord is returning kDNSServiceErr_NoSuchRecord for empty rdata

Revision 1.272  2007/04/03 20:10:32  cheshire
Show ADD/RMV in DNSServiceQueryRecord log message instead of just "RESULT"

Revision 1.271  2007/04/03 19:22:32  cheshire
Use mDNSSameIPv4Address (and similar) instead of accessing internal fields directly

Revision 1.270  2007/03/30 21:55:30  cheshire
Added comments

Revision 1.269  2007/03/29 01:31:44  cheshire
Faulty logic was incorrectly suppressing some NAT port mapping callbacks

Revision 1.268  2007/03/29 00:13:58  cheshire
Remove unnecessary fields from service_instance structure: autoname, autorename, allowremotequery, name

Revision 1.267  2007/03/28 20:59:27  cheshire
<rdar://problem/4743285> Remove inappropriate use of IsPrivateV4Addr()

Revision 1.266  2007/03/28 15:56:37  cheshire
<rdar://problem/5085774> Add listing of NAT port mapping and GetAddrInfo requests in SIGINFO output

Revision 1.265  2007/03/27 22:52:07  cheshire
Fix crash in udsserver_automatic_browse_domain_changed

Revision 1.264  2007/03/27 00:49:40  cheshire
Should use mallocL, not plain malloc

Revision 1.263  2007/03/27 00:45:01  cheshire
Removed unnecessary "void *termination_context" pointer

Revision 1.262  2007/03/27 00:40:43  cheshire
Eliminate resolve_termination_t as a separately-allocated structure, and make it part of the request_state union

Revision 1.261  2007/03/27 00:29:00  cheshire
Eliminate queryrecord_request data as a separately-allocated structure, and make it part of the request_state union

Revision 1.260  2007/03/27 00:18:42  cheshire
Eliminate enum_termination_t and domain_enum_t as separately-allocated structures,
and make them part of the request_state union

Revision 1.259  2007/03/26 23:48:16  cheshire
<rdar://problem/4848295> Advertise model information via Bonjour
Refinements to reduce unnecessary transmissions of the DeviceInfo TXT record

Revision 1.258  2007/03/24 00:40:04  cheshire
Minor code cleanup

Revision 1.257  2007/03/24 00:23:12  cheshire
Eliminate port_mapping_info_t as a separately-allocated structure, and make it part of the request_state union

Revision 1.256  2007/03/24 00:07:18  cheshire
Eliminate addrinfo_info_t as a separately-allocated structure, and make it part of the request_state union

Revision 1.255  2007/03/23 23:56:14  cheshire
Move list of record registrations into the request_state union

Revision 1.254  2007/03/23 23:48:56  cheshire
Eliminate service_info as a separately-allocated structure, and make it part of the request_state union

Revision 1.253  2007/03/23 23:04:29  cheshire
Eliminate browser_info_t as a separately-allocated structure, and make it part of request_state

Revision 1.252  2007/03/23 22:59:58  cheshire
<rdar://problem/4848295> Advertise model information via Bonjour
Use kStandardTTL, not kHostNameTTL

Revision 1.251  2007/03/23 22:44:07  cheshire
Instead of calling AbortUnlinkAndFree() haphazardly all over the place, make the handle* routines
return an error code, and then request_callback() does all necessary cleanup in one place.

Revision 1.250  2007/03/22 20:30:07  cheshire
Remove pointless "if (request->ts != t_complete) ..." checks

Revision 1.249  2007/03/22 20:13:27  cheshire
Delete unused client_context field

Revision 1.248  2007/03/22 20:03:37  cheshire
Rename variables for clarity: instead of using variable rs for both request_state
and reply_state, use req for request_state and rep for reply_state

Revision 1.247  2007/03/22 19:31:42  cheshire
<rdar://problem/4848295> Advertise model information via Bonjour
Add missing "model=" at start of DeviceInfo data

Revision 1.246  2007/03/22 18:31:48  cheshire
Put dst parameter first in mDNSPlatformStrCopy/mDNSPlatformMemCopy, like conventional Posix strcpy/memcpy

Revision 1.245  2007/03/22 00:49:20  cheshire
<rdar://problem/4848295> Advertise model information via Bonjour

Revision 1.244  2007/03/21 21:01:48  cheshire
<rdar://problem/4789793> Leak on error path in regrecord_callback, uds_daemon.c

Revision 1.243  2007/03/21 19:01:57  cheshire
<rdar://problem/5078494> IPC code not 64-bit-savvy: assumes long=32bits, and short=16bits

Revision 1.242  2007/03/21 18:51:21  cheshire
<rdar://problem/4549320> Code in uds_daemon.c passes function name instead of type name to mallocL/freeL

Revision 1.241  2007/03/20 00:04:50  cheshire
<rdar://problem/4837929> Should allow "udp" or "tcp" for protocol command-line arg
Fix LogOperation("DNSServiceNATPortMappingCreate(...)") message to actually show client arguments

Revision 1.240  2007/03/16 23:25:35  cheshire
<rdar://problem/5067001> NAT-PMP: Parameter validation not working correctly

Revision 1.239  2007/03/10 02:29:36  cheshire
Added comment about port_mapping_create_reply()

Revision 1.238  2007/03/07 00:26:48  cheshire
<rdar://problem/4426754> DNSServiceRemoveRecord log message should include record type

Revision 1.237  2007/02/28 01:44:29  cheshire
<rdar://problem/5027863> Byte order bugs in uDNS.c, uds_daemon.c, dnssd_clientstub.c

Revision 1.236  2007/02/14 01:58:19  cheshire
<rdar://problem/4995831> Don't delete Unix Domain Socket on exit if we didn't create it on startup

Revision 1.235  2007/02/08 21:12:28  cheshire
<rdar://problem/4386497> Stop reading /etc/mDNSResponder.conf on every sleep/wake

Revision 1.234  2007/02/06 19:06:49  cheshire
<rdar://problem/3956518> Need to go native with launchd

Revision 1.233  2007/01/10 20:49:37  cheshire
Remove unnecessary setting of q->Private fields

Revision 1.232  2007/01/09 00:03:23  cheshire
Call udsserver_handle_configchange() once at the end of udsserver_init()
to set up the automatic registration and browsing domains.

Revision 1.231  2007/01/06 02:50:19  cheshire
<rdar://problem/4632919> Instead of copying SRV and TXT record data, just store pointers to cache entities

Revision 1.230  2007/01/06 01:00:35  cheshire
Improved SIGINFO output

Revision 1.229  2007/01/05 08:30:56  cheshire
Trim excessive "$Log" checkin history from before 2006
(checkin history still available via "cvs log ..." of course)

Revision 1.228  2007/01/05 08:09:05  cheshire
Reorder code into functional sections, with "#pragma mark" headers

Revision 1.227  2007/01/05 07:04:24  cheshire
Minor code tidying

Revision 1.226  2007/01/05 05:44:35  cheshire
Move automatic browse/registration management from uDNS.c to mDNSShared/uds_daemon.c,
so that mDNSPosix embedded clients will compile again

Revision 1.225  2007/01/04 23:11:15  cheshire
<rdar://problem/4720673> uDNS: Need to start caching unicast records
When an automatic browsing domain is removed, generate appropriate "remove" events for legacy queries

Revision 1.224  2007/01/04 20:57:49  cheshire
Rename ReturnCNAME to ReturnIntermed (for ReturnIntermediates)

Revision 1.223  2006/12/21 01:25:49  cheshire
Tidy up SIGINFO state log

Revision 1.222  2006/12/21 00:15:22  cheshire
Get rid of gmDNS macro; fixed a crash in udsserver_info()

Revision 1.221  2006/12/20 04:07:38  cheshire
Remove uDNS_info substructure from AuthRecord_struct

Revision 1.220  2006/12/19 22:49:25  cheshire
Remove uDNS_info substructure from ServiceRecordSet_struct

Revision 1.219  2006/12/14 03:02:38  cheshire
<rdar://problem/4838433> Tools: dns-sd -G 0 only returns IPv6 when you have a routable IPv6 address

Revision 1.218  2006/11/18 05:01:33  cheshire
Preliminary support for unifying the uDNS and mDNS code,
including caching of uDNS answers

Revision 1.217  2006/11/15 19:27:53  mkrochma
<rdar://problem/4838433> Tools: dns-sd -G 0 only returns IPv6 when you have a routable IPv6 address

Revision 1.216  2006/11/10 00:54:16  cheshire
<rdar://problem/4816598> Changing case of Computer Name doesn't work

Revision 1.215  2006/10/27 01:30:23  cheshire
Need explicitly to set ReturnIntermed = mDNSfalse

Revision 1.214  2006/10/20 05:37:23  herscher
Display question list information in udsserver_info()

Revision 1.213  2006/10/05 03:54:31  herscher
Remove embedded uDNS_info struct from DNSQuestion_struct

Revision 1.212  2006/09/30 01:22:35  cheshire
Put back UTF-8 curly quotes in log messages

Revision 1.211  2006/09/27 00:44:55  herscher
<rdar://problem/4249761> API: Need DNSServiceGetAddrInfo()

Revision 1.210  2006/09/26 01:52:41  herscher
<rdar://problem/4245016> NAT Port Mapping API (for both NAT-PMP and UPnP Gateway Protocol)

Revision 1.209  2006/09/21 21:34:09  cheshire
<rdar://problem/4100000> Allow empty string name when using kDNSServiceFlagsNoAutoRename

Revision 1.208  2006/09/21 21:28:24  cheshire
Code cleanup to make it consistent with daemon.c: change rename_on_memfree to renameonmemfree

Revision 1.207  2006/09/15 21:20:16  cheshire
Remove uDNS_info substructure from mDNS_struct

Revision 1.206  2006/08/14 23:24:56  cheshire
Re-licensed mDNSResponder daemon source code under Apache License, Version 2.0

Revision 1.205  2006/07/20 22:07:30  mkrochma
<rdar://problem/4633196> Wide-area browsing is currently broken in TOT
More fixes for uninitialized variables

Revision 1.204  2006/07/15 02:01:33  cheshire
<rdar://problem/4472014> Add Private DNS client functionality to mDNSResponder
Fix broken "empty string" browsing

Revision 1.203  2006/07/07 01:09:13  cheshire
<rdar://problem/4472013> Add Private DNS server functionality to dnsextd
Only use mallocL/freeL debugging routines when building mDNSResponder, not dnsextd

Revision 1.202  2006/07/05 22:00:10  cheshire
Wide-area cleanup: Rename mDNSPlatformGetRegDomainList() to uDNS_GetDefaultRegDomainList()

Revision 1.201  2006/06/29 03:02:47  cheshire
<rdar://problem/4607042> mDNSResponder NXDOMAIN and CNAME support

Revision 1.200  2006/06/28 08:56:26  cheshire
Added "_op" to the end of the operation code enum values,
to differentiate them from the routines with the same names

Revision 1.199  2006/06/28 08:53:39  cheshire
Added (commented out) debugging messages

Revision 1.198  2006/06/27 20:16:07  cheshire
Fix code layout

Revision 1.197  2006/05/18 01:32:35  cheshire
<rdar://problem/4472706> iChat: Lost connection with Bonjour
(mDNSResponder insufficiently defensive against malformed browsing PTR responses)

Revision 1.196  2006/05/05 07:07:13  cheshire
<rdar://problem/4538206> mDNSResponder fails when UDS reads deliver partial data

Revision 1.195  2006/04/25 20:56:28  mkrochma
Added comment about previous checkin

Revision 1.194  2006/04/25 18:29:36  mkrochma
Workaround for warning: unused variable 'status' when building mDNSPosix

Revision 1.193  2006/03/19 17:14:38  cheshire
<rdar://problem/4483117> Need faster purging of stale records
read_rr_from_ipc_msg was not setting namehash and rdatahash

Revision 1.192  2006/03/18 20:58:32  cheshire
Misplaced curly brace

Revision 1.191  2006/03/10 22:19:43  cheshire
Update debugging message in resolve_result_callback() to indicate whether event is ADD or RMV

Revision 1.190  2006/03/10 21:56:12  cheshire
<rdar://problem/4111464> After record update, old record sometimes remains in cache
When service TXT and SRV record both change, clients with active resolve calls get *two* callbacks, one
when the TXT data changes, and then immediately afterwards a second callback with the new port number
This change suppresses the first unneccessary (and confusing) callback

Revision 1.189  2006/01/06 00:56:31  cheshire
<rdar://problem/4400573> Should remove PID file on exit

*/

#if defined(_WIN32)
#include <process.h>
#define dnssd_strerror(X) win32_strerror(X)
#define usleep(X) Sleep(((X)+999)/1000)
mDNSlocal char *win32_strerror(int inErrorCode)
        {
        static char buffer[1024];
        DWORD       n;
        memset(buffer, 0, sizeof(buffer));
        n = FormatMessageA(
                        FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                        NULL,
                        (DWORD) inErrorCode,
                        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                        buffer,
                        sizeof(buffer),
                        NULL);
        if (n > 0)
                {
                // Remove any trailing CR's or LF's since some messages have them.
                while ((n > 0) && isspace(((unsigned char *) buffer)[n - 1]))
                        buffer[--n] = '\0';
                }
        return buffer;
        }
#else
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#define dnssd_strerror(X) strerror(X)
#endif

#include <stdlib.h>
#include <stdio.h>
#include "mDNSEmbeddedAPI.h"
#include "DNSCommon.h"
#include "uDNS.h"
#include "uds_daemon.h"

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

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

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

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

typedef struct request_state request_state;

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

typedef struct registered_record_entry
        {
        struct registered_record_entry *next;
        mDNSu32 key;
        AuthRecord *rr;         // Variable-sized AuthRecord
        client_context_t client_context;
        request_state *request;
        } registered_record_entry;

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

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

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

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

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

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

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

typedef struct reply_state
        {
        dnssd_sock_t sd;
        transfer_state ts;
        mDNSu32 nwriten;
        mDNSu32 len;
        request_state *request;         // the request that this answers
        struct reply_state *next;       // if there are multiple unsent replies
        char *msgbuf;                           // pointer to malloc'd buffer
        ipc_msg_hdr *mhdr;                      // pointer into message buffer - allows fields to be changed after message is formatted
        reply_hdr *rhdr;
        char *sdata;                            // pointer to start of call-specific data
        } reply_state;

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

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

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

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

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

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

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

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

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

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

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

mDNSlocal void abort_request(request_state *req)
        {
        // First stop whatever mDNSCore operation we were doing
        if (req->terminate) req->terminate(req);

        // Now, if this request_state is not subbordinate to some other primary, close file descriptor and discard replies
        if (!req->primary)
                {
                if (req->errsd != req->sd) LogOperation("%3d: Removing FD and closing errsd %d", req->sd, req->errsd);
                else                       LogOperation("%3d: Removing FD", req->sd);
                udsSupportRemoveFDFromEventLoop(req->sd);               // Note: This also closes file descriptor req->sd for us
                if (req->errsd != req->sd) { dnssd_close(req->errsd); req->errsd = req->sd; }

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

// Set req->sd to something invalid, so that udsserver_idle knows to unlink and free this structure
#if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING
        // Don't use dnssd_InvalidSocket (-1) because that's the sentinel value MACOSX_MDNS_MALLOC_DEBUGGING uses
        // for detecting when the memory for an object is inadvertently freed while the object is still on some list
        req->sd = -2;
#else
        req->sd = dnssd_InvalidSocket;
#endif
        }

mDNSlocal void AbortUnlinkAndFree(request_state *req)
        {
        request_state **p = &all_requests;
        abort_request(req);
        while (*p && *p != req) p=&(*p)->next;
        if (*p) { *p = req->next; freeL("request_state/AbortUnlinkAndFree", req); }
        }

mDNSlocal reply_state *create_reply(const reply_op_t op, const size_t datalen, request_state *const request)
        {
        reply_state *reply;
        int totallen = (int) (datalen + sizeof(ipc_msg_hdr));

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

        reply = mallocL("reply_state", sizeof(reply_state));
        if (!reply) FatalError("ERROR: malloc");
        mDNSPlatformMemZero(reply, sizeof(reply_state));
        reply->ts      = t_morecoming;
        reply->sd      = request->sd;
        reply->request = request;
        reply->len     = totallen;
        reply->msgbuf  = mallocL("reply_state msgbuf", totallen);
        if (!reply->msgbuf) FatalError("ERROR: malloc");
        mDNSPlatformMemZero(reply->msgbuf, totallen);
        reply->mhdr    = (ipc_msg_hdr *)reply->msgbuf;
        reply->rhdr    = (reply_hdr *)(reply->msgbuf + sizeof(ipc_msg_hdr));
        reply->sdata   = reply->msgbuf + sizeof(ipc_msg_hdr) + sizeof(reply_hdr);
        reply->mhdr->version   = VERSION;
        reply->mhdr->datalen   = datalen;
        reply->mhdr->ipc_flags = 0;
        reply->mhdr->op        = op;
        reply->mhdr->client_context = request->hdr.client_context;
        reply->mhdr->reg_index = 0;
        return reply;
        }

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

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

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

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

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

                // Build reply body
                data = (*rep)->sdata;
                put_string(namestr, &data);
                put_string(typestr, &data);
                put_string(domstr, &data);

                return mStatus_NoError;
                }
        }

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

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

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

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

        rr = mallocL("AuthRecord/read_rr_from_ipc_msg", sizeof(AuthRecord) - sizeof(RDataBody) + storage_size);
        if (!rr) FatalError("ERROR: malloc");
        mDNS_SetupResourceRecord(rr, mDNSNULL, mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex),
                type, 0, (mDNSu8) ((flags & kDNSServiceFlagsShared) ? kDNSRecordTypeShared : kDNSRecordTypeUnique), mDNSNULL, mDNSNULL);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        for (s = m->ServiceRegistrations; s; s = s->uDNS_next)
                if (s->state != regState_Unregistered && SameDomainName(s->RR_SRV.resrec.name, r->name) && !SameRData(&s->RR_SRV.resrec, r))
                        count++;

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

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

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

// service registration callback performs three duties - frees memory for deregistered services,
// handles name conflicts, and delivers completed registration information to the client (via
// process_service_registraion())
mDNSlocal void regservice_callback(mDNS *const m, ServiceRecordSet *const srs, mStatus result)
        {
        mStatus err;
        mDNSBool SuppressError = mDNSfalse;
        service_instance *instance = srs->ServiceContext;
        reply_state         *rep;
        (void)m; // Unused
        if (!srs)      { LogMsg("regservice_callback: srs is NULL %d",                 result); return; }
        if (!instance) { LogMsg("regservice_callback: srs->ServiceContext is NULL %d", result); return; }

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

        if (result == mStatus_NoError)
                LogOperation("%3d: DNSServiceRegister(%##s, %u) REGISTERED",    instance->sd, srs->RR_SRV.resrec.name->c, mDNSVal16(srs->RR_SRV.resrec.rdata->u.srv.port));
        else if (result == mStatus_MemFree)
                LogOperation("%3d: DNSServiceRegister(%##s, %u) DEREGISTERED",  instance->sd, srs->RR_SRV.resrec.name->c, mDNSVal16(srs->RR_SRV.resrec.rdata->u.srv.port));
        else if (result == mStatus_NameConflict)
                LogOperation("%3d: DNSServiceRegister(%##s, %u) NAME CONFLICT", instance->sd, srs->RR_SRV.resrec.name->c, mDNSVal16(srs->RR_SRV.resrec.rdata->u.srv.port));
        else
                LogOperation("%3d: DNSServiceRegister(%##s, %u) CALLBACK %d",   instance->sd, srs->RR_SRV.resrec.name->c, mDNSVal16(srs->RR_SRV.resrec.rdata->u.srv.port), result);

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

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

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

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

mDNSlocal void regrecord_callback(mDNS *const m, AuthRecord *rr, mStatus result)
        {
        (void)m; // Unused
        if (!rr->RecordContext)         // parent struct already freed by termination callback
                {
                if (result == mStatus_NoError)
                        LogMsg("Error: regrecord_callback: successful registration of orphaned record");
                else
                        {
                        if (result != mStatus_MemFree) LogMsg("regrecord_callback: error %d received after parent termination", result);
                        freeL("AuthRecord/regrecord_callback", rr);
                        }
                }
        else
                {
                registered_record_entry *re = rr->RecordContext;
                request_state *request = re->request;
                int len = sizeof(DNSServiceFlags) + sizeof(mDNSu32) + sizeof(DNSServiceErrorType);
                reply_state *reply = create_reply(reg_record_reply_op, len, request);
                reply->mhdr->client_context = re->client_context;
                reply->rhdr->flags = dnssd_htonl(0);
                reply->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(m, rr->resrec.InterfaceID));
                reply->rhdr->error = dnssd_htonl(result);

                LogOperation("%3d: DNSServiceRegisterRecord(%u) result %d", request->sd, request->hdr.reg_index, result);
                if (result)
                        {
                        // unlink from list, free memory
                        registered_record_entry **ptr = &request->u.reg_recs;
                        while (*ptr && (*ptr) != re) ptr = &(*ptr)->next;
                        if (!*ptr) { LogMsg("regrecord_callback - record not in list!"); return; }
                        *ptr = (*ptr)->next;
                        freeL("registered_record_entry AuthRecord regrecord_callback", re->rr);
                        freeL("registered_record_entry regrecord_callback", re);
                        }
                append_reply(request, reply);
                }
        }

mDNSlocal void connection_termination(request_state *request)
        {
        request_state **req = &all_requests;
        while (*req)
                {
                if ((*req)->primary == request)
                        {
                        // Since we're already doing a list traversal, we unlink the request directly instead of using AbortUnlinkAndFree()
                        request_state *tmp = *req;
                        abort_request(tmp);
                        *req = tmp->next;
                        freeL("request_state/connection_termination", tmp);
                        }
                else
                        req = &(*req)->next;
                }

        while (request->u.reg_recs)
                {
                registered_record_entry *ptr = request->u.reg_recs;
                request->u.reg_recs = request->u.reg_recs->next;
                ptr->rr->RecordContext = NULL;
                mDNS_Deregister(&mDNSStorage, ptr->rr);         // Will free ptr->rr for us
                freeL("registered_record_entry/connection_termination", ptr);
                }
        }

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

mDNSlocal mStatus handle_regrecord_request(request_state *request)
        {
        mStatus err = mStatus_BadParamErr;
        AuthRecord *rr = read_rr_from_ipc_msg(request, 1, 1);
        if (rr)
                {
                // allocate registration entry, link into list
                registered_record_entry *re = mallocL("registered_record_entry", sizeof(registered_record_entry));
                if (!re) FatalError("ERROR: malloc");
                re->key = request->hdr.reg_index;
                re->rr = rr;
                re->request = request;
                re->client_context = request->hdr.client_context;
                rr->RecordContext = re;
                rr->RecordCallback = regrecord_callback;
                re->next = request->u.reg_recs;
                request->u.reg_recs = re;
        
                if (rr->resrec.rroriginalttl == 0)
                        rr->resrec.rroriginalttl = DefaultTTLforRRType(rr->resrec.rrtype);
        
                LogOperation("%3d: DNSServiceRegisterRecord(%u %s)", request->sd, request->hdr.reg_index, RRDisplayString(&mDNSStorage, &rr->resrec));
                err = mDNS_Register(&mDNSStorage, rr);
                }
        return(err);
        }

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

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

        result = mDNS_AddRecordToService(&mDNSStorage, srs, extra, &extra->r.rdatastorage, ttl);
        if (result) { freeL("ExtraResourceRecord/add_record_to_service", extra); return result; }

        extra->ClientID = request->hdr.reg_index;
        return result;
        }

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

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

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

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

        return(result);
        }

mDNSlocal void update_callback(mDNS *const m, AuthRecord *const rr, RData *oldrd)
        {
        (void)m; // Unused
        if (oldrd != &rr->rdatastorage) freeL("RData/update_callback", oldrd);
        }

mDNSlocal mStatus update_record(AuthRecord *rr, mDNSu16 rdlen, char *rdata, mDNSu32 ttl)
        {
        int rdsize;
        RData *newrd;
        mStatus result;

        if (rdlen > sizeof(RDataBody)) rdsize = rdlen;
        else rdsize = sizeof(RDataBody);
        newrd = mallocL("RData/update_record", sizeof(RData) - sizeof(RDataBody) + rdsize);
        if (!newrd) FatalError("ERROR: malloc");
        newrd->MaxRDLength = (mDNSu16) rdsize;
        mDNSPlatformMemCopy(&newrd->u, rdata, rdlen);

        // BIND named (name daemon) doesn't allow TXT records with zero-length rdata. This is strictly speaking correct,
        // since RFC 1035 specifies a TXT record as "One or more <character-string>s", not "Zero or more <character-string>s".
        // Since some legacy apps try to create zero-length TXT records, we'll silently correct it here.
        if (rr->resrec.rrtype == kDNSType_TXT && rdlen == 0) { rdlen = 1; newrd->u.txt.c[0] = 0; }

        result = mDNS_Update(&mDNSStorage, rr, ttl, rdlen, newrd, update_callback);
        if (result) { LogMsg("ERROR: mDNS_Update - %ld", result); freeL("RData/update_record", newrd); }
        return result;
        }

mDNSlocal mStatus handle_update_request(request_state *request)
        {
        mStatus result = mStatus_BadReferenceErr;
        service_instance *i;
        AuthRecord *rr = NULL;

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

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

        if (request->terminate == connection_termination)
                {
                // update an individually registered record
                registered_record_entry *reptr;
                for (reptr = request->u.reg_recs; reptr; reptr = reptr->next)
                        {
                        if (reptr->key == request->hdr.reg_index)
                                {
                                result = update_record(reptr->rr, rdlen, rdata, ttl);
                                goto end;
                                }
                        }
                result = mStatus_BadReferenceErr;
                goto end;
                }

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

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

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

        return(result);
        }

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

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

        LogOperation("%3d: DNSServiceRemoveRecord(%u %s)", request->sd, request->hdr.reg_index, RRDisplayString(&mDNSStorage, &e->rr->resrec));
        e->rr->RecordContext = NULL;
        err = mDNS_Deregister(&mDNSStorage, e->rr);
        if (err)
                {
                LogMsg("ERROR: remove_record, mDNS_Deregister: %ld", err);
                freeL("registered_record_entry AuthRecord remove_record", e->rr);
                }
        freeL("registered_record_entry remove_record", e);
        return err;
        }

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

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

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

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

        if (request->terminate == connection_termination)
                err = remove_record(request);  // remove individually registered record
        else
                {
                service_instance *i;
                mDNSu16 rrtype = 0;
                LogOperation("%3d: DNSServiceRemoveRecord(%##s, %s)", request->sd,
                        (request->u.servicereg.instances) ? request->u.servicereg.instances->srs.RR_SRV.resrec.name->c : NULL,
                        rrtype ? DNSTypeName(rrtype) : "<NONE>");
                for (i = request->u.servicereg.instances; i; i = i->next)
                        {
                        err = remove_extra(request, i, &rrtype);
                        if (err && i->default_local) break;
                        else err = mStatus_NoError;  // suppress non-local default errors
                        }
                }

        return(err);
        }

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

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

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

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

mDNSlocal mStatus register_service_instance(request_state *request, const domainname *domain)
        {
        service_instance **ptr, *instance;
        int instance_size;
        mStatus result;

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

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

        instance_size = sizeof(*instance);
        if (request->u.servicereg.txtlen > sizeof(RDataBody)) instance_size += (request->u.servicereg.txtlen - sizeof(RDataBody));
        instance = mallocL("service_instance", instance_size);
        if (!instance) { my_perror("ERROR: malloc"); return mStatus_NoMemoryErr; }

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

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

        LogOperation("%3d: DNSServiceRegister(%#s.%##s%##s, %u) ADDING",
                instance->sd, &request->u.servicereg.name, &request->u.servicereg.type, domain->c, mDNSVal16(request->u.servicereg.port));

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

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

        return result;
        }

mDNSlocal void UpdateDeviceInfoRecord(mDNS *const m);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        LogOperation("%3d: DNSServiceRegister(\"%s\", \"%s\", \"%s\", \"%s\", %u) START",
                request->sd, name, request->u.servicereg.type_as_string, domain, host, mDNSVal16(request->u.servicereg.port));
        err = register_service_instance(request, &d);

        // Set request->terminate first, before adding additional service instances, because the
        // uds_validatelists uses the request->terminate function pointer to determine what kind
        // of request this is, and therefore what kind of list validation is required.
        if (!err)
                {
                request->terminate = regservice_termination_callback;
                if (request->u.servicereg.autoname) UpdateDeviceInfoRecord(&mDNSStorage);
                }

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

        return(err);
        }

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

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

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

        if (GenerateNTDResponse(&answer->rdata->u.name, answer->InterfaceID, req, &rep, browse_reply_op, flags, mStatus_NoError) != mStatus_NoError)
                {
                LogMsg("%3d: FoundInstance: %##s PTR %##s received from network is not valid DNS-SD service pointer",
                        req->sd, answer->name->c, answer->rdata->u.name.c);
                return;
                }

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

        append_reply(req, rep);
        }

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

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

        b = mallocL("browser_t", sizeof(*b));
        if (!b) return mStatus_NoMemoryErr;
        AssignDomainName(&b->domain, d);
        err = mDNS_StartBrowse(&mDNSStorage, &b->q,
                &info->u.browser.regtype, d, info->u.browser.interface_id, info->u.browser.ForceMCast, FoundInstance, info);
        if (err)
                {
                LogMsg("mDNS_StartBrowse returned %d for type %##s domain %##s", err, info->u.browser.regtype.c, d->c);
                freeL("browser_t/add_domain_to_browser", b);
                }
        else
                {
                b->next = info->u.browser.browsers;
                info->u.browser.browsers = b;
                }
                return err;
        }

mDNSlocal void browse_termination_callback(request_state *info)
        {
        while (info->u.browser.browsers)
                {
                browser_t *ptr = info->u.browser.browsers;
                info->u.browser.browsers = ptr->next;
                LogOperation("%3d: DNSServiceBrowse(%##s) STOP", info->sd, ptr->q.qname.c);
                mDNS_StopBrowse(&mDNSStorage, &ptr->q);  // no need to error-check result
                freeL("browser_t/browse_termination_callback", ptr);
                }
        }

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

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

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

mDNSlocal void FreeARElemCallback(mDNS *const m, AuthRecord *const rr, mStatus result)
        {
        (void)m;  // unused
        if (result == mStatus_MemFree) mDNSPlatformMemFree(rr->RecordContext);
        }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        UpdateDeviceInfoRecord(m);

        // For autoname services, see if the default service name has changed, necessitating an automatic update
        for (req = all_requests; req; req = req->next)
                if (req->terminate == regservice_termination_callback)
                        if (req->u.servicereg.autoname && !SameDomainLabelCS(req->u.servicereg.name.c, m->nicelabel.c))
                                {
                                req->u.servicereg.name = m->nicelabel;
                                for (ptr = req->u.servicereg.instances; ptr; ptr = ptr->next)
                                        {
                                        ptr->renameonmemfree = 1;
                                        if (ptr->clientnotified) SendServiceRemovalNotification(&ptr->srs);
                                        if (mDNS_DeregisterService(m, &ptr->srs)) // If service was deregistered already
                                                regservice_callback(m, &ptr->srs, mStatus_MemFree); // we can re-register immediately
                                        }
                                }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        if (!domain || (domain[0] == '\0')) uDNS_RegisterSearchDomains(&mDNSStorage);

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

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

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

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

        LogOperation("%3d: DNSServiceBrowse(\"%##s\", \"%s\") START", request->sd, request->u.browser.regtype.c, domain);
        if (domain[0])
                {
                if (!MakeDomainNameFromDNSNameString(&d, domain)) return(mStatus_BadParamErr);
                err = add_domain_to_browser(request, &d);
                }

        else
                {
                DNameListElem *sdom;
                for (sdom = AutoBrowseDomains; sdom; sdom = sdom->next)
                        if (!sdom->uid || SystemUID(request->uid) || request->uid == sdom->uid)
                                {
                                err = add_domain_to_browser(request, &sdom->name);
                                if (err)
                                        {
                                        if (SameDomainName(&sdom->name, &localdomain)) break;
                                        else err = mStatus_NoError;  // suppress errors for non-local "default" domains
                                        }
                                }
                }

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

        return(err);
        }

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

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

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

        // This code used to do this trick of just keeping a copy of the pointer to
        // the answer record in the cache, but the unicast query code doesn't currently
        // put its answer records in the cache, so for now we can't do this.

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

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

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

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

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

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

        data = rep->sdata;

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

        append_reply(req, rep);
        }

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

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

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

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

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

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

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

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

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

        // ask the questions
        LogOperation("%3d: DNSServiceResolve(%##s) START", request->sd, request->u.resolve.qsrv.qname.c);
        err = mDNS_StartQuery(&mDNSStorage, &request->u.resolve.qsrv);
        if (!err)
                {
                err = mDNS_StartQuery(&mDNSStorage, &request->u.resolve.qtxt);
                if (err) mDNS_StopQuery(&mDNSStorage, &request->u.resolve.qsrv);
                }

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

        return(err);
        }

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

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

// query and resolve calls have separate request handlers that parse the arguments from the client and
// massage the name parameters appropriately, but the rest of the operations (making the query call,
// delivering the result to the client, and termination) are identical.

// what gets called when a resolve is completed and we need to send the data back to the client
mDNSlocal void queryrecord_result_callback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
        {
        char name[MAX_ESCAPED_DOMAIN_NAME];
        request_state *req = question->QuestionContext;
        reply_state *rep;
        char *data;
        size_t len;
        DNSServiceErrorType error = kDNSServiceErr_NoError;
        (void)m; // Unused

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

        if (answer->RecordType == kDNSRecordTypePacketNegative)
                {
                error = kDNSServiceErr_NoSuchRecord;
                ConvertDomainNameToCString(&question->qname, name);
                AddRecord = mDNStrue;
                }
        else
                ConvertDomainNameToCString(answer->name, name);

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

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

        rep->rhdr->flags = dnssd_htonl(AddRecord ? kDNSServiceFlagsAdd : 0);
        rep->rhdr->ifi   = dnssd_htonl(mDNSPlatformInterfaceIndexfromInterfaceID(m, answer->InterfaceID));
        rep->rhdr->error = dnssd_htonl(error);

        data = rep->sdata;

        put_string(name, &data);

        if (answer->RecordType == kDNSRecordTypePacketNegative)
                {
                put_uint16(question->qtype, &data);
                put_uint16(question->qclass, &data);
                put_uint16(0, &data);
                put_rdata(0, mDNSNULL, &data);
                put_uint32(0, &data);
                }
        else
                {
                put_uint16(answer->rrtype, &data);
                put_uint16(answer->rrclass, &data);
                put_uint16(answer->rdlength, &data);
                //put_rdata(answer->rdlength, answer->rdata->u.data, &data);
                if (!putRData(mDNSNULL, (mDNSu8 *)data, (mDNSu8 *)rep->rhdr + len, answer))
                        LogMsg("queryrecord_result_callback putRData failed %d", (mDNSu8 *)rep->rhdr + len - (mDNSu8 *)data);
                data += answer->rdlength;
                put_uint32(AddRecord ? answer->rroriginalttl : 0, &data);
                }

        append_reply(req, rep);
        }

mDNSlocal void queryrecord_termination_callback(request_state *request)
        {
        LogOperation("%3d: DNSServiceQueryRecord(%##s, %s) STOP",
                request->sd, request->u.queryrecord.q.qname.c, DNSTypeName(request->u.queryrecord.q.qtype));
        mDNS_StopQuery(&mDNSStorage, &request->u.queryrecord.q);  // no need to error check
        }

mDNSlocal mStatus handle_queryrecord_request(request_state *request)
        {
        char name[256];
        mDNSu16 rrtype, rrclass;
        mStatus err;

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

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

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

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

        request->u.queryrecord.q.InterfaceID      = InterfaceID;
        request->u.queryrecord.q.Target           = zeroAddr;
        if (!MakeDomainNameFromDNSNameString(&request->u.queryrecord.q.qname, name)) return(mStatus_BadParamErr);
        request->u.queryrecord.q.qtype            = rrtype;
        request->u.queryrecord.q.qclass           = rrclass;
        request->u.queryrecord.q.LongLived        = (flags & kDNSServiceFlagsLongLivedQuery     ) != 0;
        request->u.queryrecord.q.ExpectUnique     = mDNSfalse;
        request->u.queryrecord.q.ForceMCast       = (flags & kDNSServiceFlagsForceMulticast     ) != 0;
        request->u.queryrecord.q.ReturnIntermed   = (flags & kDNSServiceFlagsReturnIntermediates) != 0;
        request->u.queryrecord.q.QuestionCallback = queryrecord_result_callback;
        request->u.queryrecord.q.QuestionContext  = request;

        LogOperation("%3d: DNSServiceQueryRecord(%##s, %s, %X) START",
                request->sd, request->u.queryrecord.q.qname.c, DNSTypeName(request->u.queryrecord.q.qtype), flags);
        err = mDNS_StartQuery(&mDNSStorage, &request->u.queryrecord.q);
        if (err) LogMsg("ERROR: mDNS_StartQuery: %d", (int)err);

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

        return(err);
        }

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

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

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

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

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

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

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

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

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

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

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

        // allocate context structures
        uDNS_RegisterSearchDomains(&mDNSStorage);

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

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

        return(err);
        }

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

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

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

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

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

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

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

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

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

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

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

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

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

        rep = create_reply(port_mapping_reply_op, replyLen, request);

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

        data = rep->sdata;

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

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

        append_reply(request, rep);
        }

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

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

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

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

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

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

        return(err);
        }

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

mDNSlocal void addrinfo_termination_callback(request_state *request)
        {
        if (request->u.addrinfo.q4.QuestionContext)
                {
                mDNS_StopQuery(&mDNSStorage, &request->u.addrinfo.q4);
                request->u.addrinfo.q4.QuestionContext = mDNSNULL;
                }

        if (request->u.addrinfo.q6.QuestionContext)
                {
                mDNS_StopQuery(&mDNSStorage, &request->u.addrinfo.q6);
                request->u.addrinfo.q6.QuestionContext = mDNSNULL;
                }
        }

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

        DNSServiceFlags flags = get_flags(&request->msgptr, request->msgend);
        mDNSu32 interfaceIndex = get_uint32(&request->msgptr, request->msgend);
        request->u.addrinfo.interface_id = mDNSPlatformInterfaceIDfromInterfaceIndex(&mDNSStorage, interfaceIndex);
        if (interfaceIndex && !request->u.addrinfo.interface_id) return(mStatus_BadParamErr);
        request->u.addrinfo.flags = flags;
        request->u.addrinfo.protocol = get_uint32(&request->msgptr, request->msgend);
        if (request->u.addrinfo.protocol > (kDNSServiceProtocol_IPv4|kDNSServiceProtocol_IPv6))
                return(mStatus_BadParamErr);

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

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

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

        if (!request->u.addrinfo.protocol)
                {
                NetworkInterfaceInfo *i;
                if (IsLocalDomain(&d))
                        {
                        for (i = mDNSStorage.HostInterfaces; i; i = i->next)
                                {
                                if      ((i->ip.type == mDNSAddrType_IPv4) && !mDNSIPv4AddressIsZero(i->ip.ip.v4)) request->u.addrinfo.protocol |= kDNSServiceProtocol_IPv4;
                                else if ((i->ip.type == mDNSAddrType_IPv6) && !mDNSIPv6AddressIsZero(i->ip.ip.v6)) request->u.addrinfo.protocol |= kDNSServiceProtocol_IPv6;
                                }
                        }
                else
                        {
                        for (i = mDNSStorage.HostInterfaces; i; i = i->next)
                                {
                                if      ((i->ip.type == mDNSAddrType_IPv4) && !mDNSv4AddressIsLinkLocal(&i->ip.ip.v4)) request->u.addrinfo.protocol |= kDNSServiceProtocol_IPv4;
                                else if ((i->ip.type == mDNSAddrType_IPv6) && !mDNSv4AddressIsLinkLocal(&i->ip.ip.v6)) request->u.addrinfo.protocol |= kDNSServiceProtocol_IPv6;
                                }
                        }
                }

        if (request->u.addrinfo.protocol & kDNSServiceProtocol_IPv4)
                {
                request->u.addrinfo.q4.InterfaceID      = request->u.addrinfo.interface_id;
                request->u.addrinfo.q4.Target           = zeroAddr;
                request->u.addrinfo.q4.qname            = d;
                request->u.addrinfo.q4.qtype            = kDNSServiceType_A;
                request->u.addrinfo.q4.qclass           = kDNSServiceClass_IN;
                request->u.addrinfo.q4.LongLived        = (flags & kDNSServiceFlagsLongLivedQuery     ) != 0;
                request->u.addrinfo.q4.ExpectUnique     = mDNSfalse;
                request->u.addrinfo.q4.ForceMCast       = (flags & kDNSServiceFlagsForceMulticast     ) != 0;
                request->u.addrinfo.q4.ReturnIntermed   = (flags & kDNSServiceFlagsReturnIntermediates) != 0;
                request->u.addrinfo.q4.QuestionCallback = queryrecord_result_callback;
                request->u.addrinfo.q4.QuestionContext  = request;

                err = mDNS_StartQuery(&mDNSStorage, &request->u.addrinfo.q4);
                if (err != mStatus_NoError)
                        {
                        LogMsg("ERROR: mDNS_StartQuery: %d", (int)err);
                        request->u.addrinfo.q4.QuestionContext = mDNSNULL;
                        }
                }

        if (!err && (request->u.addrinfo.protocol & kDNSServiceProtocol_IPv6))
                {
                request->u.addrinfo.q6.InterfaceID      = request->u.addrinfo.interface_id;
                request->u.addrinfo.q6.Target           = zeroAddr;
                request->u.addrinfo.q6.qname            = d;
                request->u.addrinfo.q6.qtype            = kDNSServiceType_AAAA;
                request->u.addrinfo.q6.qclass           = kDNSServiceClass_IN;
                request->u.addrinfo.q6.LongLived        = (flags & kDNSServiceFlagsLongLivedQuery     ) != 0;
                request->u.addrinfo.q6.ExpectUnique     = mDNSfalse;
                request->u.addrinfo.q6.ForceMCast       = (flags & kDNSServiceFlagsForceMulticast     ) != 0;
                request->u.addrinfo.q6.ReturnIntermed   = (flags & kDNSServiceFlagsReturnIntermediates) != 0;
                request->u.addrinfo.q6.QuestionCallback = queryrecord_result_callback;
                request->u.addrinfo.q6.QuestionContext  = request;

                err = mDNS_StartQuery(&mDNSStorage, &request->u.addrinfo.q6);
                if (err != mStatus_NoError)
                        {
                        LogMsg("ERROR: mDNS_StartQuery: %d", (int)err);
                        request->u.addrinfo.q6.QuestionContext = mDNSNULL;
                        }
                }

        LogOperation("%3d: DNSServiceGetAddrInfo(%##s) START", request->sd, d.c);

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

        return(err);
        }

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

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

// read_msg may be called any time when the transfer state (req->ts) is t_morecoming.
// returns the current state of the request (morecoming, error, complete, terminated.)
// if there is no data on the socket, the socket will be closed and t_terminated will be returned
// *** NOTE return value is actually ignored -- should change return type to void ***
mDNSlocal int read_msg(request_state *req)
        {
        mDNSu32 nleft;
        int nread;

        if (req->ts == t_terminated || req->ts == t_error)
                {
                LogMsg("ERROR: read_msg called with transfer state terminated or error");
                req->ts = t_error;
                return t_error;
                }

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

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

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

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

                        // Largest conceivable single request is a DNSServiceRegisterRecord() or DNSServiceAddRecord()
                        // with 64kB of rdata. Adding 1005 byte for a maximal domain name, plus a safety margin
                        // for other overhead, this means any message above 70kB is definitely bogus.
                        if (req->hdr.datalen > 70000)
                                {
                                LogMsg("ERROR: read_msg - hdr.datalen %lu (%X) > 70000", req->hdr.datalen, req->hdr.datalen);
                                req->ts = t_error;
                                return t_error;
                                }
                        req->msgbuf = mallocL("request_state msgbuf", req->hdr.datalen + MSG_PAD_BYTES);
                        if (!req->msgbuf) { my_perror("ERROR: malloc"); req->ts = t_error; return t_error; }
                        req->msgptr = req->msgbuf;
                        req->msgend = req->msgbuf + req->hdr.datalen;
                        mDNSPlatformMemZero(req->msgbuf, req->hdr.datalen + MSG_PAD_BYTES);
                        }
                }

        // If our header is complete, but we're still needing more body data, then try to read it now
        // Note: For cancel_request req->hdr.datalen == 0, but there's no error return socket for cancel_request
        // Any time we need to get the error return socket we know we'll have at least one data byte
        // (even if only the one-byte empty C string placeholder for the old ctrl_path parameter)
        if (req->hdr_bytes == sizeof(ipc_msg_hdr) && req->data_bytes < req->hdr.datalen)
                {
                nleft = req->hdr.datalen - req->data_bytes;
                struct iovec vec = { req->msgbuf + req->data_bytes, nleft };    // Tell recvmsg where we want the bytes put
                struct msghdr msg;
                struct cmsghdr *cmsg;
                char cbuf[sizeof(struct cmsghdr) + sizeof(dnssd_sock_t)];
                msg.msg_name       = 0;
                msg.msg_namelen    = 0;
                msg.msg_iov        = &vec;
                msg.msg_iovlen     = 1;
                msg.msg_control    = cbuf;
                msg.msg_controllen = sizeof(cbuf);
                msg.msg_flags      = 0;
                nread = recvmsg(req->sd, &msg, 0);
                if (nread == 0) { req->ts = t_terminated; return t_terminated; }
                if (nread < 0) goto rerror;
                req->data_bytes += nread;
                if (req->data_bytes > req->hdr.datalen)
                        {
                        LogMsg("ERROR: read_msg - read too many data bytes");
                        req->ts = t_error;
                        return t_error;
                        }
                cmsg = CMSG_FIRSTHDR(&msg);
                if (msg.msg_controllen == sizeof(cbuf) &&
                        cmsg->cmsg_len     == sizeof(cbuf) &&
                        cmsg->cmsg_level   == SOL_SOCKET   &&
                        cmsg->cmsg_type    == SCM_RIGHTS)
                        {
                        req->errsd = *(dnssd_sock_t *)CMSG_DATA(cmsg);
                        if (req->data_bytes < req->hdr.datalen)
                                {
                                LogMsg("%3d: Client sent error socket %d via SCM_RIGHTS with req->data_bytes %d < req->hdr.datalen %d",
                                        req->sd, req->errsd, req->data_bytes, req->hdr.datalen);
                                req->ts = t_error;
                                return t_error;
                                }
                        }
                }

        // If our header and data are both complete, see if we need to make our separate error return socket
        if (req->hdr_bytes == sizeof(ipc_msg_hdr) && req->data_bytes == req->hdr.datalen)
                {
                if (req->terminate && req->hdr.op != cancel_request)
                        {
                        dnssd_sockaddr_t cliaddr;
#if defined(USE_TCP_LOOPBACK)
                        mDNSOpaque16 port;
                        port.b[0] = req->msgptr[0];
                        port.b[1] = req->msgptr[1];
                        req->msgptr += 2;
                        cliaddr.sin_family      = AF_INET;
                        cliaddr.sin_port        = port.NotAnInteger;
                        cliaddr.sin_addr.s_addr = inet_addr(MDNS_TCP_SERVERADDR);
#else
                        char ctrl_path[MAX_CTLPATH];
                        get_string(&req->msgptr, req->msgend, ctrl_path, MAX_CTLPATH);  // path is first element in message buffer
                        mDNSPlatformMemZero(&cliaddr, sizeof(cliaddr));
                        cliaddr.sun_family = AF_LOCAL;
                        mDNSPlatformStrCopy(cliaddr.sun_path, ctrl_path);
                        // If the error return path UDS name is empty string, that tells us
                        // that this is a new version of the library that's going to pass us
                        // the error return path socket via sendmsg/recvmsg
                        if (ctrl_path[0] == 0)
                                {
                                if (req->errsd == req->sd)
                                        { LogMsg("%3d: request_callback: ERROR failed to get errsd via SCM_RIGHTS", req->sd); req->ts = t_error; return t_error; }
                                goto got_errfd;
                                }
#endif
        
                        req->errsd = socket(AF_DNSSD, SOCK_STREAM, 0);
                        if (!dnssd_SocketValid(req->errsd)) { my_perror("ERROR: socket"); req->ts = t_error; return t_error; }
        
                        if (connect(req->errsd, (struct sockaddr *)&cliaddr, sizeof(cliaddr)) < 0)
                                {
#if !defined(USE_TCP_LOOPBACK)
                                struct stat sb;
                                LogMsg("request_callback: Couldn't connect to error return path socket “%s” errno %d %s",
                                        cliaddr.sun_path, dnssd_errno(), dnssd_strerror(dnssd_errno()));
                                if (stat(cliaddr.sun_path, &sb) < 0)
                                        LogMsg("request_callback: stat failed “%s” errno %d %s", cliaddr.sun_path, dnssd_errno(), dnssd_strerror(dnssd_errno()));
                                else
                                        LogMsg("request_callback: file “%s” mode %o (octal) uid %d gid %d", cliaddr.sun_path, sb.st_mode, sb.st_uid, sb.st_gid);
#endif
                                req->ts = t_error;
                                return t_error;
                                }
        
got_errfd:
                        LogOperation("%3d: Using separate error socket %d", req->sd, req->errsd);
#if defined(_WIN32)
                        if (ioctlsocket(req->errsd, FIONBIO, &opt) != 0)
#else
                        if (fcntl(req->errsd, F_SETFL, fcntl(req->errsd, F_GETFL, 0) | O_NONBLOCK) != 0)
#endif
                                { my_perror("ERROR: could not set control socket to non-blocking mode"); req->ts = t_error; return t_error; }
                        }
                
                req->ts = t_complete;
                }

        return req->ts;

rerror:
        if (dnssd_errno() == dnssd_EWOULDBLOCK || dnssd_errno() == dnssd_EINTR) return t_morecoming;
        my_perror("ERROR: read_msg");
        req->ts = t_error;
        return t_error;
        }

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

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

mDNSlocal void request_callback(int fd, short filter, void *info)
        {
        mStatus err = 0;
        request_state *req = info;
#if defined(_WIN32)
        u_long opt = 1;
#endif
        mDNSs32 min_size = sizeof(DNSServiceFlags);
        (void)fd; // Unused
        (void)filter; // Unused

        read_msg(req);
        if (req->ts == t_morecoming) return;
        if (req->ts == t_terminated || req->ts == t_error) { AbortUnlinkAndFree(req); return; }

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

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

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

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

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

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

        switch(req->hdr.op)
                {
                // These are all operations that have their own first-class request_state object
                case connection_request:
                        LogOperation("%3d: DNSServiceCreateConnection START", req->sd);
                        req->terminate = connection_termination;
                        break;
                case resolve_request:              err = handle_resolve_request     (req); break;
                case query_request:                err = handle_queryrecord_request (req); break;
                case browse_request:               err = handle_browse_request      (req); break;
                case reg_service_request:          err = handle_regservice_request  (req); break;
                case enumeration_request:          err = handle_enum_request        (req); break;
                case reconfirm_record_request:     err = handle_reconfirm_request   (req); break;
                case setdomain_request:            err = handle_setdomain_request   (req); break;
                case getproperty_request:                handle_getproperty_request (req); break;
                case port_mapping_request:         err = handle_port_mapping_request(req); break;
                case addrinfo_request:             err = handle_addrinfo_request    (req); break;

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

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

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

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

mDNSlocal void connect_callback(int fd, short filter, void *info)
        {
        dnssd_sockaddr_t cliaddr;
        dnssd_socklen_t len = (dnssd_socklen_t) sizeof(cliaddr);
        dnssd_sock_t sd = accept(listenfd, (struct sockaddr*) &cliaddr, &len);
        const unsigned long optval = 1;

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

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

#ifdef SO_NOSIGPIPE
        // Some environments (e.g. OS X) support turning off SIGPIPE for a socket
        if (setsockopt(sd, SOL_SOCKET, SO_NOSIGPIPE, &optval, sizeof(optval)) < 0)
                {
                my_perror("ERROR: setsockopt - SO_NOSIGPIPE - aborting client");
                dnssd_close(sd);
                return;
                }
#endif

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

mDNSexport int udsserver_init(dnssd_sock_t skt)
        {
        dnssd_sockaddr_t laddr;
        int ret;
#if defined(_WIN32)
        u_long opt = 1;
#endif

        LogOperation("udsserver_init");

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

        if (dnssd_SocketValid(skt))
                listenfd = skt;
        else
                {
                listenfd = socket(AF_DNSSD, SOCK_STREAM, 0);
                if (!dnssd_SocketValid(listenfd))
                        {
                        my_perror("ERROR: socket(AF_DNSSD, SOCK_STREAM, 0); failed");
                        goto error;
                        }

                mDNSPlatformMemZero(&laddr, sizeof(laddr));

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

#if defined(_WIN32)
        // SEH: do we even need to do this on windows?
        // This socket will be given to WSAEventSelect which will automatically set it to non-blocking
        if (ioctlsocket(listenfd, FIONBIO, &opt) != 0)
#else
        if (fcntl(listenfd, F_SETFL, fcntl(listenfd, F_GETFL, 0) | O_NONBLOCK) != 0)
#endif
                {
                my_perror("ERROR: could not set listen socket to non-blocking mode");
                goto error;
                }

        if (listen(listenfd, LISTENQ) != 0)
                {
                my_perror("ERROR: could not listen on listen socket");
                goto error;
                }

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

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

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

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

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

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

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

        udsserver_handle_configchange(&mDNSStorage);
        return 0;

error:

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

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

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

        return 0;
        }

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

mDNSexport void udsserver_info(mDNS *const m)
        {
        mDNSs32 now = mDNS_TimeNow(m);
        mDNSu32 CacheUsed = 0, CacheActive = 0;
        mDNSu32 slot;
        CacheGroup *cg;
        CacheRecord *cr;

        LogMsgNoIdent("Timenow 0x%08lX (%ld)", (mDNSu32)now, now);
        LogMsgNoIdent("------------ Cache -------------");

        LogMsgNoIdent("Slt Q     TTL if    U Type rdlen");
        for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
                for (cg = m->rrcache_hash[slot]; cg; cg=cg->next)
                        {
                        CacheUsed++;    // Count one cache entity for the CacheGroup object
                        for (cr = cg->members; cr; cr=cr->next)
                                {
                                mDNSs32 remain = cr->resrec.rroriginalttl - (now - cr->TimeRcvd) / mDNSPlatformOneSecond;
                                NetworkInterfaceInfo *info = (NetworkInterfaceInfo *)cr->resrec.InterfaceID;
                                CacheUsed++;
                                if (cr->CRActiveQuestion) CacheActive++;
                                LogMsgNoIdent("%3d %s%8ld %-6s%s %-6s%s",
                                        slot,
                                        cr->CRActiveQuestion ? "*" : " ",
                                        remain,
                                        info ? info->ifname : "-U-",
                                        (cr->resrec.RecordType == kDNSRecordTypePacketNegative)  ? "-" :
                                        (cr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) ? " " : "+",
                                        DNSTypeName(cr->resrec.rrtype),
                                        CRDisplayString(m, cr));
                                usleep(1000);   // Limit rate a little so we don't flood syslog too fast
                                }
                        }

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

        LogMsgNoIdent("--------- Auth Records ---------");
        if (!m->ResourceRecords) LogMsgNoIdent("<None>");
        else
                {
                AuthRecord *ar;
                for (ar = m->ResourceRecords; ar; ar=ar->next)
                        LogMsgNoIdent("%s", ARDisplayString(m, ar));
                }

        LogMsgNoIdent("---------- Questions -----------");
        if (!m->Questions) LogMsgNoIdent("<None>");
        else
                {
                DNSQuestion *q;
                CacheUsed = 0;
                CacheActive = 0;
                LogMsgNoIdent("   Int  Next if    T NumAns Type  Name");
                for (q = m->Questions; q; q=q->next)
                        {
                        mDNSs32 i = q->ThisQInterval / mDNSPlatformOneSecond;
                        mDNSs32 n = (q->LastQTime + q->ThisQInterval - now) / mDNSPlatformOneSecond;
                        NetworkInterfaceInfo *info = (NetworkInterfaceInfo *)q->InterfaceID;
                        CacheUsed++;
                        if (q->ThisQInterval) CacheActive++;
                        LogMsgNoIdent("%6d%6d %-6s%s %5d  %-6s%##s%s",
                                i, n,
                                info ? info->ifname : mDNSOpaque16IsZero(q->TargetQID) ? "" : "-U-",
                                mDNSOpaque16IsZero(q->TargetQID) ? " " : q->LongLived ? "L" : "O", // mDNS, long-lived, or one-shot query?
                                q->CurrentAnswers,
                                DNSTypeName(q->qtype), q->qname.c, q->DuplicateOf ? " (dup)" : "");
                        usleep(1000);   // Limit rate a little so we don't flood syslog too fast
                        }
                LogMsgNoIdent("%lu question%s; %lu active", CacheUsed, CacheUsed > 1 ? "s" : "", CacheActive);
                }

        LogMsgNoIdent("---- Active Client Requests ----");
        if (!all_requests) LogMsgNoIdent("<None>");
        else
                {
                request_state *req;
                for (req = all_requests; req; req=req->next)
                        LogClientInfo(m, req);
                }

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

        LogMsgNoIdent("--------- AuthInfoList ---------");
        if (!m->AuthInfoList) LogMsgNoIdent("<None>");
        else
                {
                DomainAuthInfo *a;
                for (a = m->AuthInfoList; a; a = a->next)
                        LogMsgNoIdent("%##s %##s%s", a->domain.c, a->keyname.c, a->AutoTunnel ? " AutoTunnel" : "");
                }

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

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

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

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

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

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

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

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

mDNSlocal int send_msg(reply_state *rep)
        {
        ssize_t nwriten;
        if (!rep->msgbuf) { LogMsg("ERROR: send_msg called with NULL message buffer"); return(rep->ts = t_error); }
        if (rep->request->no_reply) { freeL("reply_state msgbuf (no_reply)", rep->msgbuf); return(rep->ts = t_complete); }

        ConvertHeaderBytes(rep->mhdr);
        nwriten = send(rep->sd, rep->msgbuf + rep->nwriten, rep->len - rep->nwriten, 0);
        ConvertHeaderBytes(rep->mhdr);

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

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

        while (*req)
                {
                while ((*req)->replies)         // Send queued replies
                        {
                        transfer_state result;
                        if ((*req)->replies->next) (*req)->replies->rhdr->flags |= dnssd_htonl(kDNSServiceFlagsMoreComing);
                        result = send_msg((*req)->replies);     // Returns t_morecoming if buffer full because client is not reading
                        if (result == t_complete)
                                {
                                reply_state *fptr = (*req)->replies;
                                (*req)->replies = (*req)->replies->next;
                                freeL("reply_state/udsserver_idle", fptr);
                                (*req)->time_blocked = 0; // reset failure counter after successful send
                                continue;
                                }
                        else if (result == t_terminated || result == t_error) abort_request(*req);
                        break;
                        }

                if ((*req)->replies)            // If we failed to send everything, check our time_blocked timer
                        {
                        if (!(*req)->time_blocked) (*req)->time_blocked = NonZeroTime(now);
                        if (now - (*req)->time_blocked >= 60 * mDNSPlatformOneSecond)
                                {
                                LogMsg("Could not write data to client %d after %ld seconds - aborting connection",
                                        (*req)->sd, (now - (*req)->time_blocked) / mDNSPlatformOneSecond);
                                LogClientInfo(&mDNSStorage, *req);
                                abort_request(*req);
                                }
                        else if (nextevent - now > mDNSPlatformOneSecond) nextevent = now + mDNSPlatformOneSecond;
                        }

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

struct CompileTimeAssertionChecks_uds_daemon
        {
        // Check our structures are reasonable sizes. Including overly-large buffers, or embedding
        // other overly-large structures instead of having a pointer to them, can inadvertently
        // cause structure sizes (and therefore memory usage) to balloon unreasonably.
        char sizecheck_request_state          [(sizeof(request_state)           <= 1800) ? 1 : -1];
        char sizecheck_registered_record_entry[(sizeof(registered_record_entry) <=   30) ? 1 : -1];
        char sizecheck_service_instance       [(sizeof(service_instance)        <= 6000) ? 1 : -1];
        char sizecheck_browser_t              [(sizeof(browser_t)               <= 1000) ? 1 : -1];
        char sizecheck_reply_hdr              [(sizeof(reply_hdr)               <=   20) ? 1 : -1];
        char sizecheck_reply_state            [(sizeof(reply_state)             <=   40) ? 1 : -1];
        };