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28 
29 
30 /*! @header     DNS Service Discovery
31  *
32  * @discussion  This section describes the functions, callbacks, and data structures
33  *              that make up the DNS Service Discovery API.
34  *
35  *              The DNS Service Discovery API is part of Bonjour, Apple's implementation
36  *              of zero-configuration networking (ZEROCONF).
37  *
38  *              Bonjour allows you to register a network service, such as a
39  *              printer or file server, so that it can be found by name or browsed
40  *              for by service type and domain. Using Bonjour, applications can
41  *              discover what services are available on the network, along with
42  *              all the information -- such as name, IP address, and port --
43  *              necessary to access a particular service.
44  *
45  *              In effect, Bonjour combines the functions of a local DNS server and
46  *              AppleTalk. Bonjour allows applications to provide user-friendly printer
47  *              and server browsing, among other things, over standard IP networks.
48  *              This behavior is a result of combining protocols such as multicast and
49  *              DNS to add new functionality to the network (such as multicast DNS).
50  *
51  *              Bonjour gives applications easy access to services over local IP
52  *              networks without requiring the service or the application to support
53  *              an AppleTalk or a Netbeui stack, and without requiring a DNS server
54  *              for the local network.
55  */
56 
57 /* _DNS_SD_H contains the API version number for this header file
58  * The API version defined in this header file symbol allows for compile-time
59  * checking, so that C code building with earlier versions of the header file
60  * can avoid compile errors trying to use functions that aren't even defined
61  * in those earlier versions. Similar checks may also be performed at run-time:
62  *  => weak linking -- to avoid link failures if run with an earlier
63  *     version of the library that's missing some desired symbol, or
64  *  => DNSServiceGetProperty(DaemonVersion) -- to verify whether the running daemon
65  *     ("system service" on Windows) meets some required minimum functionality level.
66  */
67 
68 #ifndef _DNS_SD_H
69 #define _DNS_SD_H 8806001
70 
71 #ifdef  __cplusplus
72 extern "C" {
73 #endif
74 
75 /* Set to 1 if libdispatch is supported
76  * Note: May also be set by project and/or Makefile
77  */
78 #if defined(__APPLE__)
79 #define _DNS_SD_LIBDISPATCH 1
80 #else
81 #define _DNS_SD_LIBDISPATCH 0
82 #endif
83 
84 /* standard calling convention under Win32 is __stdcall */
85 /* Note: When compiling Intel EFI (Extensible Firmware Interface) under MS Visual Studio, the */
86 /* _WIN32 symbol is defined by the compiler even though it's NOT compiling code for Windows32 */
87 #if defined(_WIN32) && !defined(EFI32) && !defined(EFI64)
88 #define DNSSD_API __stdcall
89 #else
90 #define DNSSD_API
91 #endif
92 
93 #if (defined(__GNUC__) && (__GNUC__ >= 4))
94 #define DNSSD_EXPORT __attribute__((visibility("default")))
95 #else
96 #define DNSSD_EXPORT
97 #endif
98 
99 #if defined(_WIN32)
100 #include <winsock2.h>
101 typedef SOCKET dnssd_sock_t;
102 #else
103 typedef int dnssd_sock_t;
104 #endif
105 
106 /* stdint.h does not exist on FreeBSD 4.x; its types are defined in sys/types.h instead */
107 #if defined(__FreeBSD__) && (__FreeBSD__ < 5)
108 #include <sys/types.h>
109 
110 /* Likewise, on Sun, standard integer types are in sys/types.h */
111 #elif defined(__sun__)
112 #include <sys/types.h>
113 
114 /* EFI does not have stdint.h, or anything else equivalent */
115 #elif defined(EFI32) || defined(EFI64) || defined(EFIX64)
116 #include "Tiano.h"
117 #if !defined(_STDINT_H_)
118 typedef UINT8 uint8_t;
119 typedef INT8 int8_t;
120 typedef UINT16 uint16_t;
121 typedef INT16 int16_t;
122 typedef UINT32 uint32_t;
123 typedef INT32 int32_t;
124 #endif
125 /* Windows has its own differences */
126 #elif defined(_WIN32)
127 #include <windows.h>
128 #define _UNUSED
129 #ifndef _MSL_STDINT_H
130 typedef UINT8 uint8_t;
131 typedef INT8 int8_t;
132 typedef UINT16 uint16_t;
133 typedef INT16 int16_t;
134 typedef UINT32 uint32_t;
135 typedef INT32 int32_t;
136 #endif
137 
138 /* All other Posix platforms use stdint.h */
139 #else
140 #include <stdint.h>
141 #endif
142 
143 #if _DNS_SD_LIBDISPATCH
144 #include <dispatch/dispatch.h>
145 #endif
146 
147 /* DNSServiceRef, DNSRecordRef
148  *
149  * Opaque internal data types.
150  * Note: client is responsible for serializing access to these structures if
151  * they are shared between concurrent threads.
152  */
153 
154 typedef struct _DNSServiceRef_t *DNSServiceRef;
155 typedef struct _DNSRecordRef_t *DNSRecordRef;
156 
157 struct sockaddr;
158 
159 /*! @enum General flags
160  * Most DNS-SD API functions and callbacks include a DNSServiceFlags parameter.
161  * As a general rule, any given bit in the 32-bit flags field has a specific fixed meaning,
162  * regardless of the function or callback being used. For any given function or callback,
163  * typically only a subset of the possible flags are meaningful, and all others should be zero.
164  * The discussion section for each API call describes which flags are valid for that call
165  * and callback. In some cases, for a particular call, it may be that no flags are currently
166  * defined, in which case the DNSServiceFlags parameter exists purely to allow future expansion.
167  * In all cases, developers should expect that in future releases, it is possible that new flag
168  * values will be defined, and write code with this in mind. For example, code that tests
169  *     if (flags == kDNSServiceFlagsAdd) ...
170  * will fail if, in a future release, another bit in the 32-bit flags field is also set.
171  * The reliable way to test whether a particular bit is set is not with an equality test,
172  * but with a bitwise mask:
173  *     if (flags & kDNSServiceFlagsAdd) ...
174  * With the exception of kDNSServiceFlagsValidate, each flag can be valid(be set)
175  * EITHER only as an input to one of the DNSService*() APIs OR only as an output
176  * (provide status) through any of the callbacks used. For example, kDNSServiceFlagsAdd
177  * can be set only as an output in the callback, whereas the kDNSServiceFlagsIncludeP2P
178  * can be set only as an input to the DNSService*() APIs. See comments on kDNSServiceFlagsValidate
179  * defined in enum below.
180  */
181 enum
182 {
183     kDNSServiceFlagsMoreComing          = 0x1,
184     /* MoreComing indicates to a callback that at least one more result is
185      * queued and will be delivered following immediately after this one.
186      * When the MoreComing flag is set, applications should not immediately
187      * update their UI, because this can result in a great deal of ugly flickering
188      * on the screen, and can waste a great deal of CPU time repeatedly updating
189      * the screen with content that is then immediately erased, over and over.
190      * Applications should wait until MoreComing is not set, and then
191      * update their UI when no more changes are imminent.
192      * When MoreComing is not set, that doesn't mean there will be no more
193      * answers EVER, just that there are no more answers immediately
194      * available right now at this instant. If more answers become available
195      * in the future they will be delivered as usual.
196      */
197 
198     kDNSServiceFlagsAutoTrigger        = 0x1,
199     /* Valid for browses using kDNSServiceInterfaceIndexAny.
200      * Will auto trigger the browse over AWDL as well once the service is discoveryed
201      * over BLE.
202      * This flag is an input value to DNSServiceBrowse(), which is why we can
203      * use the same value as kDNSServiceFlagsMoreComing, which is an output flag
204      * for various client callbacks.
205     */
206 
207     kDNSServiceFlagsAdd                 = 0x2,
208     kDNSServiceFlagsDefault             = 0x4,
209     /* Flags for domain enumeration and browse/query reply callbacks.
210      * "Default" applies only to enumeration and is only valid in
211      * conjunction with "Add". An enumeration callback with the "Add"
212      * flag NOT set indicates a "Remove", i.e. the domain is no longer
213      * valid.
214      */
215 
216     kDNSServiceFlagsNoAutoRename        = 0x8,
217     /* Flag for specifying renaming behavior on name conflict when registering
218      * non-shared records. By default, name conflicts are automatically handled
219      * by renaming the service. NoAutoRename overrides this behavior - with this
220      * flag set, name conflicts will result in a callback. The NoAutorename flag
221      * is only valid if a name is explicitly specified when registering a service
222      * (i.e. the default name is not used.)
223      */
224 
225     kDNSServiceFlagsShared              = 0x10,
226     kDNSServiceFlagsUnique              = 0x20,
227     /* Flag for registering individual records on a connected
228      * DNSServiceRef. Shared indicates that there may be multiple records
229      * with this name on the network (e.g. PTR records). Unique indicates that the
230      * record's name is to be unique on the network (e.g. SRV records).
231      */
232 
233     kDNSServiceFlagsBrowseDomains       = 0x40,
234     kDNSServiceFlagsRegistrationDomains = 0x80,
235     /* Flags for specifying domain enumeration type in DNSServiceEnumerateDomains.
236      * BrowseDomains enumerates domains recommended for browsing, RegistrationDomains
237      * enumerates domains recommended for registration.
238      */
239 
240     kDNSServiceFlagsLongLivedQuery      = 0x100,
241     /* Flag for creating a long-lived unicast query for the DNSServiceQueryRecord call. */
242 
243     kDNSServiceFlagsAllowRemoteQuery    = 0x200,
244     /* Flag for creating a record for which we will answer remote queries
245      * (queries from hosts more than one hop away; hosts not directly connected to the local link).
246      */
247 
248     kDNSServiceFlagsForceMulticast      = 0x400,
249     /* Flag for signifying that a query or registration should be performed exclusively via multicast
250      * DNS, even for a name in a domain (e.g. foo.apple.com.) that would normally imply unicast DNS.
251      */
252 
253     kDNSServiceFlagsForce               = 0x800,    // This flag is deprecated.
254 
255     kDNSServiceFlagsKnownUnique         = 0x800,
256     /*
257      * Client guarantees that record names are unique, so we can skip sending out initial
258      * probe messages.  Standard name conflict resolution is still done if a conflict is discovered.
259      * Currently only valid for a DNSServiceRegister call.
260      */
261 
262     kDNSServiceFlagsReturnIntermediates = 0x1000,
263     /* Flag for returning intermediate results.
264      * For example, if a query results in an authoritative NXDomain (name does not exist)
265      * then that result is returned to the client. However the query is not implicitly
266      * cancelled -- it remains active and if the answer subsequently changes
267      * (e.g. because a VPN tunnel is subsequently established) then that positive
268      * result will still be returned to the client.
269      * Similarly, if a query results in a CNAME record, then in addition to following
270      * the CNAME referral, the intermediate CNAME result is also returned to the client.
271      * When this flag is not set, NXDomain errors are not returned, and CNAME records
272      * are followed silently without informing the client of the intermediate steps.
273      * (In earlier builds this flag was briefly calledkDNSServiceFlagsReturnCNAME)
274      */
275 
276     kDNSServiceFlagsNonBrowsable        = 0x2000,
277     /* A service registered with the NonBrowsable flag set can be resolved using
278      * DNSServiceResolve(), but will not be discoverable using DNSServiceBrowse().
279      * This is for cases where the name is actually a GUID; it is found by other means;
280      * there is no end-user benefit to browsing to find a long list of opaque GUIDs.
281      * Using the NonBrowsable flag creates SRV+TXT without the cost of also advertising
282      * an associated PTR record.
283      */
284 
285     kDNSServiceFlagsShareConnection     = 0x4000,
286     /* For efficiency, clients that perform many concurrent operations may want to use a
287      * single Unix Domain Socket connection with the background daemon, instead of having a
288      * separate connection for each independent operation. To use this mode, clients first
289      * call DNSServiceCreateConnection(&MainRef) to initialize the main DNSServiceRef.
290      * For each subsequent operation that is to share that same connection, the client copies
291      * the MainRef, and then passes the address of that copy, setting the ShareConnection flag
292      * to tell the library that this DNSServiceRef is not a typical uninitialized DNSServiceRef;
293      * it's a copy of an existing DNSServiceRef whose connection information should be reused.
294      *
295      * For example:
296      *
297      * DNSServiceErrorType error;
298      * DNSServiceRef MainRef;
299      * error = DNSServiceCreateConnection(&MainRef);
300      * if (error) ...
301      * DNSServiceRef BrowseRef = MainRef;  // Important: COPY the primary DNSServiceRef first...
302      * error = DNSServiceBrowse(&BrowseRef, kDNSServiceFlagsShareConnection, ...); // then use the copy
303      * if (error) ...
304      * ...
305      * DNSServiceRefDeallocate(BrowseRef); // Terminate the browse operation
306      * DNSServiceRefDeallocate(MainRef);   // Terminate the shared connection
307      * Also see Point 4.(Don't Double-Deallocate if the MainRef has been Deallocated) in Notes below:
308      *
309      * Notes:
310      *
311      * 1. Collective kDNSServiceFlagsMoreComing flag
312      * When callbacks are invoked using a shared DNSServiceRef, the
313      * kDNSServiceFlagsMoreComing flag applies collectively to *all* active
314      * operations sharing the same parent DNSServiceRef. If the MoreComing flag is
315      * set it means that there are more results queued on this parent DNSServiceRef,
316      * but not necessarily more results for this particular callback function.
317      * The implication of this for client programmers is that when a callback
318      * is invoked with the MoreComing flag set, the code should update its
319      * internal data structures with the new result, and set a variable indicating
320      * that its UI needs to be updated. Then, later when a callback is eventually
321      * invoked with the MoreComing flag not set, the code should update *all*
322      * stale UI elements related to that shared parent DNSServiceRef that need
323      * updating, not just the UI elements related to the particular callback
324      * that happened to be the last one to be invoked.
325      *
326      * 2. Canceling operations and kDNSServiceFlagsMoreComing
327      * Whenever you cancel any operation for which you had deferred UI updates
328      * waiting because of a kDNSServiceFlagsMoreComing flag, you should perform
329      * those deferred UI updates. This is because, after cancelling the operation,
330      * you can no longer wait for a callback *without* MoreComing set, to tell
331      * you do perform your deferred UI updates (the operation has been canceled,
332      * so there will be no more callbacks). An implication of the collective
333      * kDNSServiceFlagsMoreComing flag for shared connections is that this
334      * guideline applies more broadly -- any time you cancel an operation on
335      * a shared connection, you should perform all deferred UI updates for all
336      * operations sharing that connection. This is because the MoreComing flag
337      * might have been referring to events coming for the operation you canceled,
338      * which will now not be coming because the operation has been canceled.
339      *
340      * 3. Only share DNSServiceRef's created with DNSServiceCreateConnection
341      * Calling DNSServiceCreateConnection(&ref) creates a special shareable DNSServiceRef.
342      * DNSServiceRef's created by other calls like DNSServiceBrowse() or DNSServiceResolve()
343      * cannot be shared by copying them and using kDNSServiceFlagsShareConnection.
344      *
345      * 4. Don't Double-Deallocate if the MainRef has been Deallocated
346      * Calling DNSServiceRefDeallocate(ref) for a particular operation's DNSServiceRef terminates
347      * just that operation. Calling DNSServiceRefDeallocate(ref) for the main shared DNSServiceRef
348      * (the parent DNSServiceRef, originally created by DNSServiceCreateConnection(&ref))
349      * automatically terminates the shared connection and all operations that were still using it.
350      * After doing this, DO NOT then attempt to deallocate any remaining subordinate DNSServiceRef's.
351      * The memory used by those subordinate DNSServiceRef's has already been freed, so any attempt
352      * to do a DNSServiceRefDeallocate (or any other operation) on them will result in accesses
353      * to freed memory, leading to crashes or other equally undesirable results.
354      *
355      * 5. Thread Safety
356      * The dns_sd.h API does not presuppose any particular threading model, and consequently
357      * does no locking internally (which would require linking with a specific threading library).
358      * If the client concurrently, from multiple threads (or contexts), calls API routines using
359      * the same DNSServiceRef, it is the client's responsibility to provide mutual exclusion for
360      * that DNSServiceRef.
361 
362      * For example, use of DNSServiceRefDeallocate requires caution. A common mistake is as follows:
363      * Thread B calls DNSServiceRefDeallocate to deallocate sdRef while Thread A is processing events
364      * using sdRef. Doing this will lead to intermittent crashes on thread A if the sdRef is used after
365      * it was deallocated.
366 
367      * A telltale sign of this crash type is to see DNSServiceProcessResult on the stack preceding the
368      * actual crash location.
369 
370      * To state this more explicitly, mDNSResponder does not queue DNSServiceRefDeallocate so
371      * that it occurs discretely before or after an event is handled.
372      */
373 
374     kDNSServiceFlagsSuppressUnusable    = 0x8000,
375     /*
376      * This flag is meaningful only in DNSServiceQueryRecord which suppresses unusable queries on the
377      * wire. If "hostname" is a wide-area unicast DNS hostname (i.e. not a ".local." name)
378      * but this host has no routable IPv6 address, then the call will not try to look up IPv6 addresses
379      * for "hostname", since any addresses it found would be unlikely to be of any use anyway. Similarly,
380      * if this host has no routable IPv4 address, the call will not try to look up IPv4 addresses for
381      * "hostname".
382      */
383 
384     kDNSServiceFlagsTimeout            = 0x10000,
385     /*
386      * When kDNServiceFlagsTimeout is passed to DNSServiceQueryRecord or DNSServiceGetAddrInfo, the query is
387      * stopped after a certain number of seconds have elapsed. The time at which the query will be stopped
388      * is determined by the system and cannot be configured by the user. The query will be stopped irrespective
389      * of whether a response was given earlier or not. When the query is stopped, the callback will be called
390      * with an error code of kDNSServiceErr_Timeout and a NULL sockaddr will be returned for DNSServiceGetAddrInfo
391      * and zero length rdata will be returned for DNSServiceQueryRecord.
392      */
393 
394     kDNSServiceFlagsIncludeP2P          = 0x20000,
395     /*
396      * Include P2P interfaces when kDNSServiceInterfaceIndexAny is specified.
397      * By default, specifying kDNSServiceInterfaceIndexAny does not include P2P interfaces.
398      */
399 
400     kDNSServiceFlagsWakeOnResolve      = 0x40000,
401     /*
402     * This flag is meaningful only in DNSServiceResolve. When set, it tries to send a magic packet
403     * to wake up the client.
404     */
405 
406     kDNSServiceFlagsBackgroundTrafficClass  = 0x80000,
407     /*
408     * This flag is meaningful for Unicast DNS queries. When set, it uses the background traffic
409     * class for packets that service the request.
410     */
411 
412     kDNSServiceFlagsIncludeAWDL      = 0x100000,
413    /*
414     * Include AWDL interface when kDNSServiceInterfaceIndexAny is specified.
415     */
416 
417     kDNSServiceFlagsValidate               = 0x200000,
418    /*
419     * This flag is meaningful in DNSServiceGetAddrInfo and DNSServiceQueryRecord. This is the ONLY flag to be valid
420     * as an input to the APIs and also an output through the callbacks in the APIs.
421     *
422     * When this flag is passed to DNSServiceQueryRecord and DNSServiceGetAddrInfo to resolve unicast names,
423     * the response  will be validated using DNSSEC. The validation results are delivered using the flags field in
424     * the callback and kDNSServiceFlagsValidate is marked in the flags to indicate that DNSSEC status is also available.
425     * When the callback is called to deliver the query results, the validation results may or may not be available.
426     * If it is not delivered along with the results, the validation status is delivered when the validation completes.
427     *
428     * When the validation results are delivered in the callback, it is indicated by marking the flags with
429     * kDNSServiceFlagsValidate and kDNSServiceFlagsAdd along with the DNSSEC status flags (described below) and a NULL
430     * sockaddr will be returned for DNSServiceGetAddrInfo and zero length rdata will be returned for DNSServiceQueryRecord.
431     * DNSSEC validation results are for the whole RRSet and not just individual records delivered in the callback. When
432     * kDNSServiceFlagsAdd is not set in the flags, applications should implicitly assume that the DNSSEC status of the
433     * RRSet that has been delivered up until that point is not valid anymore, till another callback is called with
434     * kDNSServiceFlagsAdd and kDNSServiceFlagsValidate.
435     *
436     * The following four flags indicate the status of the DNSSEC validation and marked in the flags field of the callback.
437     * When any of the four flags is set, kDNSServiceFlagsValidate will also be set. To check the validation status, the
438     * other applicable output flags should be masked. See kDNSServiceOutputFlags below.
439     */
440 
441     kDNSServiceFlagsSecure                 = 0x200010,
442    /*
443     * The response has been validated by verifying all the signatures in the response and was able to
444     * build a successful authentication chain starting from a known trust anchor.
445     */
446 
447     kDNSServiceFlagsInsecure               = 0x200020,
448    /*
449     * A chain of trust cannot be built starting from a known trust anchor to the response.
450     */
451 
452     kDNSServiceFlagsBogus                  = 0x200040,
453    /*
454     * If the response cannot be verified to be secure due to expired signatures, missing signatures etc.,
455     * then the results are considered to be bogus.
456     */
457 
458     kDNSServiceFlagsIndeterminate          = 0x200080,
459    /*
460     * There is no valid trust anchor that can be used to determine whether a response is secure or not.
461     */
462 
463     kDNSServiceFlagsUnicastResponse        = 0x400000,
464    /*
465     * Request unicast response to query.
466     */
467     kDNSServiceFlagsValidateOptional       = 0x800000,
468 
469     /*
470      * This flag is identical to kDNSServiceFlagsValidate except for the case where the response
471      * cannot be validated. If this flag is set in DNSServiceQueryRecord or DNSServiceGetAddrInfo,
472      * the DNSSEC records will be requested for validation. If they cannot be received for some reason
473      * during the validation (e.g., zone is not signed, zone is signed but cannot be traced back to
474      * root, recursive server does not understand DNSSEC etc.), then this will fallback to the default
475      * behavior where the validation will not be performed and no DNSSEC results will be provided.
476      *
477      * If the zone is signed and there is a valid path to a known trust anchor configured in the system
478      * and the application requires DNSSEC validation irrespective of the DNSSEC awareness in the current
479      * network, then this option MUST not be used. This is only intended to be used during the transition
480      * period where the different nodes participating in the DNS resolution may not understand DNSSEC or
481      * managed properly (e.g. missing DS record) but still want to be able to resolve DNS successfully.
482      */
483 
484     kDNSServiceFlagsWakeOnlyService        = 0x1000000,
485     /*
486      * This flag is meaningful only in DNSServiceRegister. When set, the service will not be registered
487      * with sleep proxy server during sleep.
488      */
489 
490     kDNSServiceFlagsThresholdOne           = 0x2000000,
491     kDNSServiceFlagsThresholdFinder        = 0x4000000,
492     kDNSServiceFlagsThresholdReached       = kDNSServiceFlagsThresholdOne,
493     /*
494      * kDNSServiceFlagsThresholdOne is meaningful only in DNSServiceBrowse. When set,
495      * the system will stop issuing browse queries on the network once the number
496      * of answers returned is one or more.  It will issue queries on the network
497      * again if the number of answers drops to zero.
498      * This flag is for Apple internal use only. Third party developers
499      * should not rely on this behavior being supported in any given software release.
500      *
501      * kDNSServiceFlagsThresholdFinder is meaningful only in DNSServiceBrowse. When set,
502      * the system will stop issuing browse queries on the network once the number
503      * of answers has reached the threshold set for Finder.
504      * It will issue queries on the network again if the number of answers drops below
505      * this threshold.
506      * This flag is for Apple internal use only. Third party developers
507      * should not rely on this behavior being supported in any given software release.
508      *
509      * When kDNSServiceFlagsThresholdReached is set in the client callback add or remove event,
510      * it indicates that the browse answer threshold has been reached and no
511      * browse requests will be generated on the network until the number of answers falls
512      * below the threshold value.  Add and remove events can still occur based
513      * on incoming Bonjour traffic observed by the system.
514      * The set of services return to the client is not guaranteed to represent the
515      * entire set of services present on the network once the threshold has been reached.
516      *
517      * Note, while kDNSServiceFlagsThresholdReached and kDNSServiceFlagsThresholdOne
518      * have the same value, there  isn't a conflict because kDNSServiceFlagsThresholdReached
519      * is only set in the callbacks and kDNSServiceFlagsThresholdOne is only set on
520      * input to a DNSServiceBrowse call.
521      */
522      kDNSServiceFlagsPrivateOne          = 0x8000000,
523     /*
524      * This flag is private and should not be used.
525      */
526 
527      kDNSServiceFlagsPrivateTwo           = 0x10000000,
528     /*
529      * This flag is private and should not be used.
530      */
531 
532      kDNSServiceFlagsPrivateThree         = 0x20000000,
533     /*
534      * This flag is private and should not be used.
535      */
536 
537      kDNSServiceFlagsPrivateFour          = 0x40000000,
538     /*
539      * This flag is private and should not be used.
540      */
541 
542     kDNSServiceFlagsAllowExpiredAnswers   = 0x80000000,
543     /*
544      * When kDNSServiceFlagsAllowExpiredAnswers is passed to DNSServiceQueryRecord or DNSServiceGetAddrInfo,
545      * if there are matching expired records still in the cache, then they are immediately returned to the
546      * client, and in parallel a network query for that name is issued. All returned records from the query will
547      * remain in the cache after expiration.
548      */
549 
550     kDNSServiceFlagsExpiredAnswer         = 0x80000000
551     /*
552      * When kDNSServiceFlagsAllowExpiredAnswers is passed to DNSServiceQueryRecord or DNSServiceGetAddrInfo,
553      * an expired answer will have this flag set.
554      */
555 
556 };
557 
558 #define kDNSServiceOutputFlags (kDNSServiceFlagsValidate | kDNSServiceFlagsValidateOptional | kDNSServiceFlagsMoreComing | kDNSServiceFlagsAdd | kDNSServiceFlagsDefault)
559    /* All the output flags excluding the DNSSEC Status flags. Typically used to check DNSSEC Status */
560 
561 /* Possible protocol values */
562 enum
563 {
564     /* for DNSServiceGetAddrInfo() */
565     kDNSServiceProtocol_IPv4 = 0x01,
566     kDNSServiceProtocol_IPv6 = 0x02,
567     /* 0x04 and 0x08 reserved for future internetwork protocols */
568 
569     /* for DNSServiceNATPortMappingCreate() */
570     kDNSServiceProtocol_UDP  = 0x10,
571     kDNSServiceProtocol_TCP  = 0x20
572                                /* 0x40 and 0x80 reserved for future transport protocols, e.g. SCTP [RFC 2960]
573                                 * or DCCP [RFC 4340]. If future NAT gateways are created that support port
574                                 * mappings for these protocols, new constants will be defined here.
575                                 */
576 };
577 
578 /*
579  * The values for DNS Classes and Types are listed in RFC 1035, and are available
580  * on every OS in its DNS header file. Unfortunately every OS does not have the
581  * same header file containing DNS Class and Type constants, and the names of
582  * the constants are not consistent. For example, BIND 8 uses "T_A",
583  * BIND 9 uses "ns_t_a", Windows uses "DNS_TYPE_A", etc.
584  * For this reason, these constants are also listed here, so that code using
585  * the DNS-SD programming APIs can use these constants, so that the same code
586  * can compile on all our supported platforms.
587  */
588 
589 enum
590 {
591     kDNSServiceClass_IN       = 1       /* Internet */
592 };
593 
594 enum
595 {
596     kDNSServiceType_A          = 1,      /* Host address. */
597     kDNSServiceType_NS         = 2,      /* Authoritative server. */
598     kDNSServiceType_MD         = 3,      /* Mail destination. */
599     kDNSServiceType_MF         = 4,      /* Mail forwarder. */
600     kDNSServiceType_CNAME      = 5,      /* Canonical name. */
601     kDNSServiceType_SOA        = 6,      /* Start of authority zone. */
602     kDNSServiceType_MB         = 7,      /* Mailbox domain name. */
603     kDNSServiceType_MG         = 8,      /* Mail group member. */
604     kDNSServiceType_MR         = 9,      /* Mail rename name. */
605     kDNSServiceType_NULL       = 10,     /* Null resource record. */
606     kDNSServiceType_WKS        = 11,     /* Well known service. */
607     kDNSServiceType_PTR        = 12,     /* Domain name pointer. */
608     kDNSServiceType_HINFO      = 13,     /* Host information. */
609     kDNSServiceType_MINFO      = 14,     /* Mailbox information. */
610     kDNSServiceType_MX         = 15,     /* Mail routing information. */
611     kDNSServiceType_TXT        = 16,     /* One or more text strings (NOT "zero or more..."). */
612     kDNSServiceType_RP         = 17,     /* Responsible person. */
613     kDNSServiceType_AFSDB      = 18,     /* AFS cell database. */
614     kDNSServiceType_X25        = 19,     /* X_25 calling address. */
615     kDNSServiceType_ISDN       = 20,     /* ISDN calling address. */
616     kDNSServiceType_RT         = 21,     /* Router. */
617     kDNSServiceType_NSAP       = 22,     /* NSAP address. */
618     kDNSServiceType_NSAP_PTR   = 23,     /* Reverse NSAP lookup (deprecated). */
619     kDNSServiceType_SIG        = 24,     /* Security signature. */
620     kDNSServiceType_KEY        = 25,     /* Security key. */
621     kDNSServiceType_PX         = 26,     /* X.400 mail mapping. */
622     kDNSServiceType_GPOS       = 27,     /* Geographical position (withdrawn). */
623     kDNSServiceType_AAAA       = 28,     /* IPv6 Address. */
624     kDNSServiceType_LOC        = 29,     /* Location Information. */
625     kDNSServiceType_NXT        = 30,     /* Next domain (security). */
626     kDNSServiceType_EID        = 31,     /* Endpoint identifier. */
627     kDNSServiceType_NIMLOC     = 32,     /* Nimrod Locator. */
628     kDNSServiceType_SRV        = 33,     /* Server Selection. */
629     kDNSServiceType_ATMA       = 34,     /* ATM Address */
630     kDNSServiceType_NAPTR      = 35,     /* Naming Authority PoinTeR */
631     kDNSServiceType_KX         = 36,     /* Key Exchange */
632     kDNSServiceType_CERT       = 37,     /* Certification record */
633     kDNSServiceType_A6         = 38,     /* IPv6 Address (deprecated) */
634     kDNSServiceType_DNAME      = 39,     /* Non-terminal DNAME (for IPv6) */
635     kDNSServiceType_SINK       = 40,     /* Kitchen sink (experimental) */
636     kDNSServiceType_OPT        = 41,     /* EDNS0 option (meta-RR) */
637     kDNSServiceType_APL        = 42,     /* Address Prefix List */
638     kDNSServiceType_DS         = 43,     /* Delegation Signer */
639     kDNSServiceType_SSHFP      = 44,     /* SSH Key Fingerprint */
640     kDNSServiceType_IPSECKEY   = 45,     /* IPSECKEY */
641     kDNSServiceType_RRSIG      = 46,     /* RRSIG */
642     kDNSServiceType_NSEC       = 47,     /* Denial of Existence */
643     kDNSServiceType_DNSKEY     = 48,     /* DNSKEY */
644     kDNSServiceType_DHCID      = 49,     /* DHCP Client Identifier */
645     kDNSServiceType_NSEC3      = 50,     /* Hashed Authenticated Denial of Existence */
646     kDNSServiceType_NSEC3PARAM = 51,     /* Hashed Authenticated Denial of Existence */
647 
648     kDNSServiceType_HIP        = 55,     /* Host Identity Protocol */
649 
650     kDNSServiceType_SPF        = 99,     /* Sender Policy Framework for E-Mail */
651     kDNSServiceType_UINFO      = 100,    /* IANA-Reserved */
652     kDNSServiceType_UID        = 101,    /* IANA-Reserved */
653     kDNSServiceType_GID        = 102,    /* IANA-Reserved */
654     kDNSServiceType_UNSPEC     = 103,    /* IANA-Reserved */
655 
656     kDNSServiceType_TKEY       = 249,    /* Transaction key */
657     kDNSServiceType_TSIG       = 250,    /* Transaction signature. */
658     kDNSServiceType_IXFR       = 251,    /* Incremental zone transfer. */
659     kDNSServiceType_AXFR       = 252,    /* Transfer zone of authority. */
660     kDNSServiceType_MAILB      = 253,    /* Transfer mailbox records. */
661     kDNSServiceType_MAILA      = 254,    /* Transfer mail agent records. */
662     kDNSServiceType_ANY        = 255     /* Wildcard match. */
663 };
664 
665 /* possible error code values */
666 enum
667 {
668     kDNSServiceErr_NoError                   = 0,
669     kDNSServiceErr_Unknown                   = -65537,  /* 0xFFFE FFFF */
670     kDNSServiceErr_NoSuchName                = -65538,
671     kDNSServiceErr_NoMemory                  = -65539,
672     kDNSServiceErr_BadParam                  = -65540,
673     kDNSServiceErr_BadReference              = -65541,
674     kDNSServiceErr_BadState                  = -65542,
675     kDNSServiceErr_BadFlags                  = -65543,
676     kDNSServiceErr_Unsupported               = -65544,
677     kDNSServiceErr_NotInitialized            = -65545,
678     kDNSServiceErr_AlreadyRegistered         = -65547,
679     kDNSServiceErr_NameConflict              = -65548,
680     kDNSServiceErr_Invalid                   = -65549,
681     kDNSServiceErr_Firewall                  = -65550,
682     kDNSServiceErr_Incompatible              = -65551,  /* client library incompatible with daemon */
683     kDNSServiceErr_BadInterfaceIndex         = -65552,
684     kDNSServiceErr_Refused                   = -65553,
685     kDNSServiceErr_NoSuchRecord              = -65554,
686     kDNSServiceErr_NoAuth                    = -65555,
687     kDNSServiceErr_NoSuchKey                 = -65556,
688     kDNSServiceErr_NATTraversal              = -65557,
689     kDNSServiceErr_DoubleNAT                 = -65558,
690     kDNSServiceErr_BadTime                   = -65559,  /* Codes up to here existed in Tiger */
691     kDNSServiceErr_BadSig                    = -65560,
692     kDNSServiceErr_BadKey                    = -65561,
693     kDNSServiceErr_Transient                 = -65562,
694     kDNSServiceErr_ServiceNotRunning         = -65563,  /* Background daemon not running */
695     kDNSServiceErr_NATPortMappingUnsupported = -65564,  /* NAT doesn't support PCP, NAT-PMP or UPnP */
696     kDNSServiceErr_NATPortMappingDisabled    = -65565,  /* NAT supports PCP, NAT-PMP or UPnP, but it's disabled by the administrator */
697     kDNSServiceErr_NoRouter                  = -65566,  /* No router currently configured (probably no network connectivity) */
698     kDNSServiceErr_PollingMode               = -65567,
699     kDNSServiceErr_Timeout                   = -65568
700 
701                                                /* mDNS Error codes are in the range
702                                                 * FFFE FF00 (-65792) to FFFE FFFF (-65537) */
703 };
704 
705 /* Maximum length, in bytes, of a service name represented as a */
706 /* literal C-String, including the terminating NULL at the end. */
707 
708 #define kDNSServiceMaxServiceName 64
709 
710 /* Maximum length, in bytes, of a domain name represented as an *escaped* C-String */
711 /* including the final trailing dot, and the C-String terminating NULL at the end. */
712 
713 #define kDNSServiceMaxDomainName 1009
714 
715 /*
716  * Notes on DNS Name Escaping
717  *   -- or --
718  * "Why is kDNSServiceMaxDomainName 1009, when the maximum legal domain name is 256 bytes?"
719  *
720  * All strings used in the DNS-SD APIs are UTF-8 strings.
721  * Apart from the exceptions noted below, the APIs expect the strings to be properly escaped, using the
722  * conventional DNS escaping rules, as used by the traditional DNS res_query() API, as described below:
723  *
724  * Generally all UTF-8 characters (which includes all US ASCII characters) represent themselves,
725  * with two exceptions, the dot ('.') character, which is the label separator,
726  * and the backslash ('\') character, which is the escape character.
727  * The escape character ('\') is interpreted as described below:
728  *
729  *   '\ddd', where ddd is a three-digit decimal value from 000 to 255,
730  *        represents a single literal byte with that value. Any byte value may be
731  *        represented in '\ddd' format, even characters that don't strictly need to be escaped.
732  *        For example, the ASCII code for 'w' is 119, and therefore '\119' is equivalent to 'w'.
733  *        Thus the command "ping '\119\119\119.apple.com'" is the equivalent to the command "ping 'www.apple.com'".
734  *        Nonprinting ASCII characters in the range 0-31 are often represented this way.
735  *        In particular, the ASCII NUL character (0) cannot appear in a C string because C uses it as the
736  *        string terminator character, so ASCII NUL in a domain name has to be represented in a C string as '\000'.
737  *        Other characters like space (ASCII code 32) are sometimes represented as '\032'
738  *        in contexts where having an actual space character in a C string would be inconvenient.
739  *
740  *   Otherwise, for all cases where a '\' is followed by anything other than a three-digit decimal value
741  *        from 000 to 255, the character sequence '\x' represents a single literal occurrence of character 'x'.
742  *        This is legal for any character, so, for example, '\w' is equivalent to 'w'.
743  *        Thus the command "ping '\w\w\w.apple.com'" is the equivalent to the command "ping 'www.apple.com'".
744  *        However, this encoding is most useful when representing the characters '.' and '\',
745  *        which otherwise would have special meaning in DNS name strings.
746  *        This means that the following encodings are particularly common:
747  *        '\\' represents a single literal '\' in the name
748  *        '\.' represents a single literal '.' in the name
749  *
750  *   A lone escape character ('\') appearing at the end of a string is not allowed, since it is
751  *        followed by neither a three-digit decimal value from 000 to 255 nor a single character.
752  *        If a lone escape character ('\') does appear as the last character of a string, it is silently ignored.
753  *
754  * The exceptions, that do not use escaping, are the routines where the full
755  * DNS name of a resource is broken, for convenience, into servicename/regtype/domain.
756  * In these routines, the "servicename" is NOT escaped. It does not need to be, since
757  * it is, by definition, just a single literal string. Any characters in that string
758  * represent exactly what they are. The "regtype" portion is, technically speaking,
759  * escaped, but since legal regtypes are only allowed to contain US ASCII letters,
760  * digits, and hyphens, there is nothing to escape, so the issue is moot.
761  * The "domain" portion is also escaped, though most domains in use on the public
762  * Internet today, like regtypes, don't contain any characters that need to be escaped.
763  * As DNS-SD becomes more popular, rich-text domains for service discovery will
764  * become common, so software should be written to cope with domains with escaping.
765  *
766  * The servicename may be up to 63 bytes of UTF-8 text (not counting the C-String
767  * terminating NULL at the end). The regtype is of the form _service._tcp or
768  * _service._udp, where the "service" part is 1-15 characters, which may be
769  * letters, digits, or hyphens. The domain part of the three-part name may be
770  * any legal domain, providing that the resulting servicename+regtype+domain
771  * name does not exceed 256 bytes.
772  *
773  * For most software, these issues are transparent. When browsing, the discovered
774  * servicenames should simply be displayed as-is. When resolving, the discovered
775  * servicename/regtype/domain are simply passed unchanged to DNSServiceResolve().
776  * When a DNSServiceResolve() succeeds, the returned fullname is already in
777  * the correct format to pass to standard system DNS APIs such as res_query().
778  * For converting from servicename/regtype/domain to a single properly-escaped
779  * full DNS name, the helper function DNSServiceConstructFullName() is provided.
780  *
781  * The following (highly contrived) example illustrates the escaping process.
782  * Suppose you have a service called "Dr. Smith\Dr. Johnson", of type "_ftp._tcp"
783  * in subdomain "4th. Floor" of subdomain "Building 2" of domain "apple.com."
784  * The full (escaped) DNS name of this service's SRV record would be:
785  * Dr\.\032Smith\\Dr\.\032Johnson._ftp._tcp.4th\.\032Floor.Building\0322.apple.com.
786  */
787 
788 
789 /*
790  * Constants for specifying an interface index
791  *
792  * Specific interface indexes are identified via a 32-bit unsigned integer returned
793  * by the if_nametoindex() family of calls.
794  *
795  * If the client passes 0 for interface index, that means "do the right thing",
796  * which (at present) means, "if the name is in an mDNS local multicast domain
797  * (e.g. 'local.', '254.169.in-addr.arpa.', '{8,9,A,B}.E.F.ip6.arpa.') then multicast
798  * on all applicable interfaces, otherwise send via unicast to the appropriate
799  * DNS server." Normally, most clients will use 0 for interface index to
800  * automatically get the default sensible behaviour.
801  *
802  * If the client passes a positive interface index, then that indicates to do the
803  * operation only on that one specified interface.
804  *
805  * If the client passes kDNSServiceInterfaceIndexLocalOnly when registering
806  * a service, then that service will be found *only* by other local clients
807  * on the same machine that are browsing using kDNSServiceInterfaceIndexLocalOnly
808  * or kDNSServiceInterfaceIndexAny.
809  * If a client has a 'private' service, accessible only to other processes
810  * running on the same machine, this allows the client to advertise that service
811  * in a way such that it does not inadvertently appear in service lists on
812  * all the other machines on the network.
813  *
814  * If the client passes kDNSServiceInterfaceIndexLocalOnly when querying or
815  * browsing, then the LocalOnly authoritative records and /etc/hosts caches
816  * are searched and will find *all* records registered or configured on that
817  * same local machine.
818  *
819  * If interested in getting negative answers to local questions while querying
820  * or browsing, then set both the kDNSServiceInterfaceIndexLocalOnly and the
821  * kDNSServiceFlagsReturnIntermediates flags. If no local answers exist at this
822  * moment in time, then the reply will return an immediate negative answer. If
823  * local records are subsequently created that answer the question, then those
824  * answers will be delivered, for as long as the question is still active.
825  *
826  * If the kDNSServiceFlagsTimeout and kDNSServiceInterfaceIndexLocalOnly flags
827  * are set simultaneously when either DNSServiceQueryRecord or DNSServiceGetAddrInfo
828  * is called then both flags take effect. However, if DNSServiceQueryRecord is called
829  * with both the kDNSServiceFlagsSuppressUnusable and kDNSServiceInterfaceIndexLocalOnly
830  * flags set, then the kDNSServiceFlagsSuppressUnusable flag is ignored.
831  *
832  * Clients explicitly wishing to discover *only* LocalOnly services during a
833  * browse may do this, without flags, by inspecting the interfaceIndex of each
834  * service reported to a DNSServiceBrowseReply() callback function, and
835  * discarding those answers where the interface index is not set to
836  * kDNSServiceInterfaceIndexLocalOnly.
837  *
838  * kDNSServiceInterfaceIndexP2P is meaningful only in Browse, QueryRecord, Register,
839  * and Resolve operations. It should not be used in other DNSService APIs.
840  *
841  * - If kDNSServiceInterfaceIndexP2P is passed to DNSServiceBrowse or
842  *   DNSServiceQueryRecord, it restricts the operation to P2P.
843  *
844  * - If kDNSServiceInterfaceIndexP2P is passed to DNSServiceRegister, it is
845  *   mapped internally to kDNSServiceInterfaceIndexAny with the kDNSServiceFlagsIncludeP2P
846  *   set.
847  *
848  * - If kDNSServiceInterfaceIndexP2P is passed to DNSServiceResolve, it is
849  *   mapped internally to kDNSServiceInterfaceIndexAny with the kDNSServiceFlagsIncludeP2P
850  *   set, because resolving a P2P service may create and/or enable an interface whose
851  *   index is not known a priori. The resolve callback will indicate the index of the
852  *   interface via which the service can be accessed.
853  *
854  * If applications pass kDNSServiceInterfaceIndexAny to DNSServiceBrowse
855  * or DNSServiceQueryRecord, they must set the kDNSServiceFlagsIncludeP2P flag
856  * to include P2P. In this case, if a service instance or the record being queried
857  * is found over P2P, the resulting ADD event will indicate kDNSServiceInterfaceIndexP2P
858  * as the interface index.
859  */
860 
861 #define kDNSServiceInterfaceIndexAny 0
862 #define kDNSServiceInterfaceIndexLocalOnly ((uint32_t)-1)
863 #define kDNSServiceInterfaceIndexUnicast   ((uint32_t)-2)
864 #define kDNSServiceInterfaceIndexP2P       ((uint32_t)-3)
865 #define kDNSServiceInterfaceIndexBLE       ((uint32_t)-4)
866 
867 typedef uint32_t DNSServiceFlags;
868 typedef uint32_t DNSServiceProtocol;
869 typedef int32_t DNSServiceErrorType;
870 
871 
872 /*********************************************************************************************
873 *
874 * Version checking
875 *
876 *********************************************************************************************/
877 
878 /* DNSServiceGetProperty() Parameters:
879  *
880  * property:        The requested property.
881  *                  Currently the only property defined is kDNSServiceProperty_DaemonVersion.
882  *
883  * result:          Place to store result.
884  *                  For retrieving DaemonVersion, this should be the address of a uint32_t.
885  *
886  * size:            Pointer to uint32_t containing size of the result location.
887  *                  For retrieving DaemonVersion, this should be sizeof(uint32_t).
888  *                  On return the uint32_t is updated to the size of the data returned.
889  *                  For DaemonVersion, the returned size is always sizeof(uint32_t), but
890  *                  future properties could be defined which return variable-sized results.
891  *
892  * return value:    Returns kDNSServiceErr_NoError on success, or kDNSServiceErr_ServiceNotRunning
893  *                  if the daemon (or "system service" on Windows) is not running.
894  */
895 
896 DNSSD_EXPORT
897 DNSServiceErrorType DNSSD_API DNSServiceGetProperty
898 (
899     const char *property,  /* Requested property (i.e. kDNSServiceProperty_DaemonVersion) */
900     void       *result,    /* Pointer to place to store result */
901     uint32_t   *size       /* size of result location */
902 );
903 
904 /*
905  * When requesting kDNSServiceProperty_DaemonVersion, the result pointer must point
906  * to a 32-bit unsigned integer, and the size parameter must be set to sizeof(uint32_t).
907  *
908  * On return, the 32-bit unsigned integer contains the API version number
909  *
910  * For example, Mac OS X 10.4.9 has API version 1080400.
911  * This allows applications to do simple greater-than and less-than comparisons:
912  * e.g. an application that requires at least API version 1080400 can check:
913  *   if (version >= 1080400) ...
914  *
915  * Example usage:
916  * uint32_t version;
917  * uint32_t size = sizeof(version);
918  * DNSServiceErrorType err = DNSServiceGetProperty(kDNSServiceProperty_DaemonVersion, &version, &size);
919  * if (!err) printf("DNS_SD API version is %d.%d\n", version / 10000, version / 100 % 100);
920  */
921 
922 #define kDNSServiceProperty_DaemonVersion "DaemonVersion"
923 
924 /*********************************************************************************************
925 *
926 * Unix Domain Socket access, DNSServiceRef deallocation, and data processing functions
927 *
928 *********************************************************************************************/
929 
930 /* DNSServiceRefSockFD()
931  *
932  * Access underlying Unix domain socket for an initialized DNSServiceRef.
933  * The DNS Service Discovery implementation uses this socket to communicate between the client and
934  * the daemon. The application MUST NOT directly read from or write to this socket.
935  * Access to the socket is provided so that it can be used as a kqueue event source, a CFRunLoop
936  * event source, in a select() loop, etc. When the underlying event management subsystem (kqueue/
937  * select/CFRunLoop etc.) indicates to the client that data is available for reading on the
938  * socket, the client should call DNSServiceProcessResult(), which will extract the daemon's
939  * reply from the socket, and pass it to the appropriate application callback. By using a run
940  * loop or select(), results from the daemon can be processed asynchronously. Alternatively,
941  * a client can choose to fork a thread and have it loop calling "DNSServiceProcessResult(ref);"
942  * If DNSServiceProcessResult() is called when no data is available for reading on the socket, it
943  * will block until data does become available, and then process the data and return to the caller.
944  * The application is responsible for checking the return value of DNSServiceProcessResult()
945  * to determine if the socket is valid and if it should continue to process data on the socket.
946  * When data arrives on the socket, the client is responsible for calling DNSServiceProcessResult(ref)
947  * in a timely fashion -- if the client allows a large backlog of data to build up the daemon
948  * may terminate the connection.
949  *
950  * sdRef:           A DNSServiceRef initialized by any of the DNSService calls.
951  *
952  * return value:    The DNSServiceRef's underlying socket descriptor, or -1 on
953  *                  error.
954  */
955 
956 DNSSD_EXPORT
957 dnssd_sock_t DNSSD_API DNSServiceRefSockFD(DNSServiceRef sdRef);
958 
959 
960 /* DNSServiceProcessResult()
961  *
962  * Read a reply from the daemon, calling the appropriate application callback. This call will
963  * block until the daemon's response is received. Use DNSServiceRefSockFD() in
964  * conjunction with a run loop or select() to determine the presence of a response from the
965  * server before calling this function to process the reply without blocking. Call this function
966  * at any point if it is acceptable to block until the daemon's response arrives. Note that the
967  * client is responsible for ensuring that DNSServiceProcessResult() is called whenever there is
968  * a reply from the daemon - the daemon may terminate its connection with a client that does not
969  * process the daemon's responses.
970  *
971  * sdRef:           A DNSServiceRef initialized by any of the DNSService calls
972  *                  that take a callback parameter.
973  *
974  * return value:    Returns kDNSServiceErr_NoError on success, otherwise returns
975  *                  an error code indicating the specific failure that occurred.
976  */
977 
978 DNSSD_EXPORT
979 DNSServiceErrorType DNSSD_API DNSServiceProcessResult(DNSServiceRef sdRef);
980 
981 
982 /* DNSServiceRefDeallocate()
983  *
984  * Terminate a connection with the daemon and free memory associated with the DNSServiceRef.
985  * Any services or records registered with this DNSServiceRef will be deregistered. Any
986  * Browse, Resolve, or Query operations called with this reference will be terminated.
987  *
988  * Note: If the reference's underlying socket is used in a run loop or select() call, it should
989  * be removed BEFORE DNSServiceRefDeallocate() is called, as this function closes the reference's
990  * socket.
991  *
992  * Note: If the reference was initialized with DNSServiceCreateConnection(), any DNSRecordRefs
993  * created via this reference will be invalidated by this call - the resource records are
994  * deregistered, and their DNSRecordRefs may not be used in subsequent functions. Similarly,
995  * if the reference was initialized with DNSServiceRegister, and an extra resource record was
996  * added to the service via DNSServiceAddRecord(), the DNSRecordRef created by the Add() call
997  * is invalidated when this function is called - the DNSRecordRef may not be used in subsequent
998  * functions.
999  *
1000  * Note: This call is to be used only with the DNSServiceRef defined by this API.
1001  *
1002  * sdRef:           A DNSServiceRef initialized by any of the DNSService calls.
1003  *
1004  */
1005 
1006 DNSSD_EXPORT
1007 void DNSSD_API DNSServiceRefDeallocate(DNSServiceRef sdRef);
1008 
1009 
1010 /*********************************************************************************************
1011 *
1012 * Domain Enumeration
1013 *
1014 *********************************************************************************************/
1015 
1016 /* DNSServiceEnumerateDomains()
1017  *
1018  * Asynchronously enumerate domains available for browsing and registration.
1019  *
1020  * The enumeration MUST be cancelled via DNSServiceRefDeallocate() when no more domains
1021  * are to be found.
1022  *
1023  * Note that the names returned are (like all of DNS-SD) UTF-8 strings,
1024  * and are escaped using standard DNS escaping rules.
1025  * (See "Notes on DNS Name Escaping" earlier in this file for more details.)
1026  * A graphical browser displaying a hierarchical tree-structured view should cut
1027  * the names at the bare dots to yield individual labels, then de-escape each
1028  * label according to the escaping rules, and then display the resulting UTF-8 text.
1029  *
1030  * DNSServiceDomainEnumReply Callback Parameters:
1031  *
1032  * sdRef:           The DNSServiceRef initialized by DNSServiceEnumerateDomains().
1033  *
1034  * flags:           Possible values are:
1035  *                  kDNSServiceFlagsMoreComing
1036  *                  kDNSServiceFlagsAdd
1037  *                  kDNSServiceFlagsDefault
1038  *
1039  * interfaceIndex:  Specifies the interface on which the domain exists. (The index for a given
1040  *                  interface is determined via the if_nametoindex() family of calls.)
1041  *
1042  * errorCode:       Will be kDNSServiceErr_NoError (0) on success, otherwise indicates
1043  *                  the failure that occurred (other parameters are undefined if errorCode is nonzero).
1044  *
1045  * replyDomain:     The name of the domain.
1046  *
1047  * context:         The context pointer passed to DNSServiceEnumerateDomains.
1048  *
1049  */
1050 
1051 typedef void (DNSSD_API *DNSServiceDomainEnumReply)
1052 (
1053     DNSServiceRef sdRef,
1054     DNSServiceFlags flags,
1055     uint32_t interfaceIndex,
1056     DNSServiceErrorType errorCode,
1057     const char                          *replyDomain,
1058     void                                *context
1059 );
1060 
1061 
1062 /* DNSServiceEnumerateDomains() Parameters:
1063  *
1064  * sdRef:           A pointer to an uninitialized DNSServiceRef. If the call succeeds
1065  *                  then it initializes the DNSServiceRef, returns kDNSServiceErr_NoError,
1066  *                  and the enumeration operation will run indefinitely until the client
1067  *                  terminates it by passing this DNSServiceRef to DNSServiceRefDeallocate().
1068  *
1069  * flags:           Possible values are:
1070  *                  kDNSServiceFlagsBrowseDomains to enumerate domains recommended for browsing.
1071  *                  kDNSServiceFlagsRegistrationDomains to enumerate domains recommended
1072  *                  for registration.
1073  *
1074  * interfaceIndex:  If non-zero, specifies the interface on which to look for domains.
1075  *                  (the index for a given interface is determined via the if_nametoindex()
1076  *                  family of calls.) Most applications will pass 0 to enumerate domains on
1077  *                  all interfaces. See "Constants for specifying an interface index" for more details.
1078  *
1079  * callBack:        The function to be called when a domain is found or the call asynchronously
1080  *                  fails.
1081  *
1082  * context:         An application context pointer which is passed to the callback function
1083  *                  (may be NULL).
1084  *
1085  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
1086  *                  errors are delivered to the callback), otherwise returns an error code indicating
1087  *                  the error that occurred (the callback is not invoked and the DNSServiceRef
1088  *                  is not initialized).
1089  */
1090 
1091 DNSSD_EXPORT
1092 DNSServiceErrorType DNSSD_API DNSServiceEnumerateDomains
1093 (
1094     DNSServiceRef                       *sdRef,
1095     DNSServiceFlags flags,
1096     uint32_t interfaceIndex,
1097     DNSServiceDomainEnumReply callBack,
1098     void                                *context  /* may be NULL */
1099 );
1100 
1101 
1102 /*********************************************************************************************
1103 *
1104 *  Service Registration
1105 *
1106 *********************************************************************************************/
1107 
1108 /* Register a service that is discovered via Browse() and Resolve() calls.
1109  *
1110  * DNSServiceRegisterReply() Callback Parameters:
1111  *
1112  * sdRef:           The DNSServiceRef initialized by DNSServiceRegister().
1113  *
1114  * flags:           When a name is successfully registered, the callback will be
1115  *                  invoked with the kDNSServiceFlagsAdd flag set. When Wide-Area
1116  *                  DNS-SD is in use, it is possible for a single service to get
1117  *                  more than one success callback (e.g. one in the "local" multicast
1118  *                  DNS domain, and another in a wide-area unicast DNS domain).
1119  *                  If a successfully-registered name later suffers a name conflict
1120  *                  or similar problem and has to be deregistered, the callback will
1121  *                  be invoked with the kDNSServiceFlagsAdd flag not set. The callback
1122  *                  is *not* invoked in the case where the caller explicitly terminates
1123  *                  the service registration by calling DNSServiceRefDeallocate(ref);
1124  *
1125  * errorCode:       Will be kDNSServiceErr_NoError on success, otherwise will
1126  *                  indicate the failure that occurred (including name conflicts,
1127  *                  if the kDNSServiceFlagsNoAutoRename flag was used when registering.)
1128  *                  Other parameters are undefined if errorCode is nonzero.
1129  *
1130  * name:            The service name registered (if the application did not specify a name in
1131  *                  DNSServiceRegister(), this indicates what name was automatically chosen).
1132  *
1133  * regtype:         The type of service registered, as it was passed to the callout.
1134  *
1135  * domain:          The domain on which the service was registered (if the application did not
1136  *                  specify a domain in DNSServiceRegister(), this indicates the default domain
1137  *                  on which the service was registered).
1138  *
1139  * context:         The context pointer that was passed to the callout.
1140  *
1141  */
1142 
1143 typedef void (DNSSD_API *DNSServiceRegisterReply)
1144 (
1145     DNSServiceRef sdRef,
1146     DNSServiceFlags flags,
1147     DNSServiceErrorType errorCode,
1148     const char                          *name,
1149     const char                          *regtype,
1150     const char                          *domain,
1151     void                                *context
1152 );
1153 
1154 
1155 /* DNSServiceRegister() Parameters:
1156  *
1157  * sdRef:           A pointer to an uninitialized DNSServiceRef. If the call succeeds
1158  *                  then it initializes the DNSServiceRef, returns kDNSServiceErr_NoError,
1159  *                  and the registration will remain active indefinitely until the client
1160  *                  terminates it by passing this DNSServiceRef to DNSServiceRefDeallocate().
1161  *
1162  * flags:           Indicates the renaming behavior on name conflict (most applications
1163  *                  will pass 0). See flag definitions above for details.
1164  *
1165  * interfaceIndex:  If non-zero, specifies the interface on which to register the service
1166  *                  (the index for a given interface is determined via the if_nametoindex()
1167  *                  family of calls.) Most applications will pass 0 to register on all
1168  *                  available interfaces. See "Constants for specifying an interface index" for more details.
1169  *
1170  * name:            If non-NULL, specifies the service name to be registered.
1171  *                  Most applications will not specify a name, in which case the computer
1172  *                  name is used (this name is communicated to the client via the callback).
1173  *                  If a name is specified, it must be 1-63 bytes of UTF-8 text.
1174  *                  If the name is longer than 63 bytes it will be automatically truncated
1175  *                  to a legal length, unless the NoAutoRename flag is set,
1176  *                  in which case kDNSServiceErr_BadParam will be returned.
1177  *
1178  * regtype:         The service type followed by the protocol, separated by a dot
1179  *                  (e.g. "_ftp._tcp"). The service type must be an underscore, followed
1180  *                  by 1-15 characters, which may be letters, digits, or hyphens.
1181  *                  The transport protocol must be "_tcp" or "_udp". New service types
1182  *                  should be registered at <http://www.dns-sd.org/ServiceTypes.html>.
1183  *
1184  *                  Additional subtypes of the primary service type (where a service
1185  *                  type has defined subtypes) follow the primary service type in a
1186  *                  comma-separated list, with no additional spaces, e.g.
1187  *                      "_primarytype._tcp,_subtype1,_subtype2,_subtype3"
1188  *                  Subtypes provide a mechanism for filtered browsing: A client browsing
1189  *                  for "_primarytype._tcp" will discover all instances of this type;
1190  *                  a client browsing for "_primarytype._tcp,_subtype2" will discover only
1191  *                  those instances that were registered with "_subtype2" in their list of
1192  *                  registered subtypes.
1193  *
1194  *                  The subtype mechanism can be illustrated with some examples using the
1195  *                  dns-sd command-line tool:
1196  *
1197  *                  % dns-sd -R Simple _test._tcp "" 1001 &
1198  *                  % dns-sd -R Better _test._tcp,HasFeatureA "" 1002 &
1199  *                  % dns-sd -R Best   _test._tcp,HasFeatureA,HasFeatureB "" 1003 &
1200  *
1201  *                  Now:
1202  *                  % dns-sd -B _test._tcp             # will find all three services
1203  *                  % dns-sd -B _test._tcp,HasFeatureA # finds "Better" and "Best"
1204  *                  % dns-sd -B _test._tcp,HasFeatureB # finds only "Best"
1205  *
1206  *                  Subtype labels may be up to 63 bytes long, and may contain any eight-
1207  *                  bit byte values, including zero bytes. However, due to the nature of
1208  *                  using a C-string-based API, conventional DNS escaping must be used for
1209  *                  dots ('.'), commas (','), backslashes ('\') and zero bytes, as shown below:
1210  *
1211  *                  % dns-sd -R Test '_test._tcp,s\.one,s\,two,s\\three,s\000four' local 123
1212  *
1213  *                  When a service is registered, all the clients browsing for the registered
1214  *                  type ("regtype") will discover it. If the discovery should be
1215  *                  restricted to a smaller set of well known peers, the service can be
1216  *                  registered with additional data (group identifier) that is known
1217  *                  only to a smaller set of peers. The group identifier should follow primary
1218  *                  service type using a colon (":") as a delimeter. If subtypes are also present,
1219  *                  it should be given before the subtype as shown below.
1220  *
1221  *                  % dns-sd -R _test1 _http._tcp:mygroup1 local 1001
1222  *                  % dns-sd -R _test2 _http._tcp:mygroup2 local 1001
1223  *                  % dns-sd -R _test3 _http._tcp:mygroup3,HasFeatureA local 1001
1224  *
1225  *                  Now:
1226  *                  % dns-sd -B _http._tcp:"mygroup1"                # will discover only test1
1227  *                  % dns-sd -B _http._tcp:"mygroup2"                # will discover only test2
1228  *                  % dns-sd -B _http._tcp:"mygroup3",HasFeatureA    # will discover only test3
1229  *
1230  *                  By specifying the group information, only the members of that group are
1231  *                  discovered.
1232  *
1233  *                  The group identifier itself is not sent in clear. Only a hash of the group
1234  *                  identifier is sent and the clients discover them anonymously. The group identifier
1235  *                  may be up to 256 bytes long and may contain any eight bit values except comma which
1236  *                  should be escaped.
1237  *
1238  * domain:          If non-NULL, specifies the domain on which to advertise the service.
1239  *                  Most applications will not specify a domain, instead automatically
1240  *                  registering in the default domain(s).
1241  *
1242  * host:            If non-NULL, specifies the SRV target host name. Most applications
1243  *                  will not specify a host, instead automatically using the machine's
1244  *                  default host name(s). Note that specifying a non-NULL host does NOT
1245  *                  create an address record for that host - the application is responsible
1246  *                  for ensuring that the appropriate address record exists, or creating it
1247  *                  via DNSServiceRegisterRecord().
1248  *
1249  * port:            The port, in network byte order, on which the service accepts connections.
1250  *                  Pass 0 for a "placeholder" service (i.e. a service that will not be discovered
1251  *                  by browsing, but will cause a name conflict if another client tries to
1252  *                  register that same name). Most clients will not use placeholder services.
1253  *
1254  * txtLen:          The length of the txtRecord, in bytes. Must be zero if the txtRecord is NULL.
1255  *
1256  * txtRecord:       The TXT record rdata. A non-NULL txtRecord MUST be a properly formatted DNS
1257  *                  TXT record, i.e. <length byte> <data> <length byte> <data> ...
1258  *                  Passing NULL for the txtRecord is allowed as a synonym for txtLen=1, txtRecord="",
1259  *                  i.e. it creates a TXT record of length one containing a single empty string.
1260  *                  RFC 1035 doesn't allow a TXT record to contain *zero* strings, so a single empty
1261  *                  string is the smallest legal DNS TXT record.
1262  *                  As with the other parameters, the DNSServiceRegister call copies the txtRecord
1263  *                  data; e.g. if you allocated the storage for the txtRecord parameter with malloc()
1264  *                  then you can safely free that memory right after the DNSServiceRegister call returns.
1265  *
1266  * callBack:        The function to be called when the registration completes or asynchronously
1267  *                  fails. The client MAY pass NULL for the callback -  The client will NOT be notified
1268  *                  of the default values picked on its behalf, and the client will NOT be notified of any
1269  *                  asynchronous errors (e.g. out of memory errors, etc.) that may prevent the registration
1270  *                  of the service. The client may NOT pass the NoAutoRename flag if the callback is NULL.
1271  *                  The client may still deregister the service at any time via DNSServiceRefDeallocate().
1272  *
1273  * context:         An application context pointer which is passed to the callback function
1274  *                  (may be NULL).
1275  *
1276  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
1277  *                  errors are delivered to the callback), otherwise returns an error code indicating
1278  *                  the error that occurred (the callback is never invoked and the DNSServiceRef
1279  *                  is not initialized).
1280  */
1281 
1282 DNSSD_EXPORT
1283 DNSServiceErrorType DNSSD_API DNSServiceRegister
1284 (
1285     DNSServiceRef                       *sdRef,
1286     DNSServiceFlags flags,
1287     uint32_t interfaceIndex,
1288     const char                          *name,         /* may be NULL */
1289     const char                          *regtype,
1290     const char                          *domain,       /* may be NULL */
1291     const char                          *host,         /* may be NULL */
1292     uint16_t port,                                     /* In network byte order */
1293     uint16_t txtLen,
1294     const void                          *txtRecord,    /* may be NULL */
1295     DNSServiceRegisterReply callBack,                  /* may be NULL */
1296     void                                *context       /* may be NULL */
1297 );
1298 
1299 
1300 /* DNSServiceAddRecord()
1301  *
1302  * Add a record to a registered service. The name of the record will be the same as the
1303  * registered service's name.
1304  * The record can later be updated or deregistered by passing the RecordRef initialized
1305  * by this function to DNSServiceUpdateRecord() or DNSServiceRemoveRecord().
1306  *
1307  * Note that the DNSServiceAddRecord/UpdateRecord/RemoveRecord are *NOT* thread-safe
1308  * with respect to a single DNSServiceRef. If you plan to have multiple threads
1309  * in your program simultaneously add, update, or remove records from the same
1310  * DNSServiceRef, then it's the caller's responsibility to use a mutex lock
1311  * or take similar appropriate precautions to serialize those calls.
1312  *
1313  * Parameters;
1314  *
1315  * sdRef:           A DNSServiceRef initialized by DNSServiceRegister().
1316  *
1317  * RecordRef:       A pointer to an uninitialized DNSRecordRef. Upon succesfull completion of this
1318  *                  call, this ref may be passed to DNSServiceUpdateRecord() or DNSServiceRemoveRecord().
1319  *                  If the above DNSServiceRef is passed to DNSServiceRefDeallocate(), RecordRef is also
1320  *                  invalidated and may not be used further.
1321  *
1322  * flags:           Currently ignored, reserved for future use.
1323  *
1324  * rrtype:          The type of the record (e.g. kDNSServiceType_TXT, kDNSServiceType_SRV, etc)
1325  *
1326  * rdlen:           The length, in bytes, of the rdata.
1327  *
1328  * rdata:           The raw rdata to be contained in the added resource record.
1329  *
1330  * ttl:             The time to live of the resource record, in seconds.
1331  *                  Most clients should pass 0 to indicate that the system should
1332  *                  select a sensible default value.
1333  *
1334  * return value:    Returns kDNSServiceErr_NoError on success, otherwise returns an
1335  *                  error code indicating the error that occurred (the RecordRef is not initialized).
1336  */
1337 
1338 DNSSD_EXPORT
1339 DNSServiceErrorType DNSSD_API DNSServiceAddRecord
1340 (
1341     DNSServiceRef sdRef,
1342     DNSRecordRef                        *RecordRef,
1343     DNSServiceFlags flags,
1344     uint16_t rrtype,
1345     uint16_t rdlen,
1346     const void                          *rdata,
1347     uint32_t ttl
1348 );
1349 
1350 
1351 /* DNSServiceUpdateRecord
1352  *
1353  * Update a registered resource record. The record must either be:
1354  *   - The primary txt record of a service registered via DNSServiceRegister()
1355  *   - A record added to a registered service via DNSServiceAddRecord()
1356  *   - An individual record registered by DNSServiceRegisterRecord()
1357  *
1358  * Parameters:
1359  *
1360  * sdRef:           A DNSServiceRef that was initialized by DNSServiceRegister()
1361  *                  or DNSServiceCreateConnection().
1362  *
1363  * RecordRef:       A DNSRecordRef initialized by DNSServiceAddRecord, or NULL to update the
1364  *                  service's primary txt record.
1365  *
1366  * flags:           Currently ignored, reserved for future use.
1367  *
1368  * rdlen:           The length, in bytes, of the new rdata.
1369  *
1370  * rdata:           The new rdata to be contained in the updated resource record.
1371  *
1372  * ttl:             The time to live of the updated resource record, in seconds.
1373  *                  Most clients should pass 0 to indicate that the system should
1374  *                  select a sensible default value.
1375  *
1376  * return value:    Returns kDNSServiceErr_NoError on success, otherwise returns an
1377  *                  error code indicating the error that occurred.
1378  */
1379 
1380 DNSSD_EXPORT
1381 DNSServiceErrorType DNSSD_API DNSServiceUpdateRecord
1382 (
1383     DNSServiceRef sdRef,
1384     DNSRecordRef RecordRef,                            /* may be NULL */
1385     DNSServiceFlags flags,
1386     uint16_t rdlen,
1387     const void                          *rdata,
1388     uint32_t ttl
1389 );
1390 
1391 
1392 /* DNSServiceRemoveRecord
1393  *
1394  * Remove a record previously added to a service record set via DNSServiceAddRecord(), or deregister
1395  * a record registered individually via DNSServiceRegisterRecord().
1396  *
1397  * Parameters:
1398  *
1399  * sdRef:           A DNSServiceRef initialized by DNSServiceRegister() (if the
1400  *                  record being removed was registered via DNSServiceAddRecord()) or by
1401  *                  DNSServiceCreateConnection() (if the record being removed was registered via
1402  *                  DNSServiceRegisterRecord()).
1403  *
1404  * recordRef:       A DNSRecordRef initialized by a successful call to DNSServiceAddRecord()
1405  *                  or DNSServiceRegisterRecord().
1406  *
1407  * flags:           Currently ignored, reserved for future use.
1408  *
1409  * return value:    Returns kDNSServiceErr_NoError on success, otherwise returns an
1410  *                  error code indicating the error that occurred.
1411  */
1412 
1413 DNSSD_EXPORT
1414 DNSServiceErrorType DNSSD_API DNSServiceRemoveRecord
1415 (
1416     DNSServiceRef sdRef,
1417     DNSRecordRef RecordRef,
1418     DNSServiceFlags flags
1419 );
1420 
1421 
1422 /*********************************************************************************************
1423 *
1424 *  Service Discovery
1425 *
1426 *********************************************************************************************/
1427 
1428 /* Browse for instances of a service.
1429  *
1430  * DNSServiceBrowseReply() Parameters:
1431  *
1432  * sdRef:           The DNSServiceRef initialized by DNSServiceBrowse().
1433  *
1434  * flags:           Possible values are kDNSServiceFlagsMoreComing and kDNSServiceFlagsAdd.
1435  *                  See flag definitions for details.
1436  *
1437  * interfaceIndex:  The interface on which the service is advertised. This index should
1438  *                  be passed to DNSServiceResolve() when resolving the service.
1439  *
1440  * errorCode:       Will be kDNSServiceErr_NoError (0) on success, otherwise will
1441  *                  indicate the failure that occurred. Other parameters are undefined if
1442  *                  the errorCode is nonzero.
1443  *
1444  * serviceName:     The discovered service name. This name should be displayed to the user,
1445  *                  and stored for subsequent use in the DNSServiceResolve() call.
1446  *
1447  * regtype:         The service type, which is usually (but not always) the same as was passed
1448  *                  to DNSServiceBrowse(). One case where the discovered service type may
1449  *                  not be the same as the requested service type is when using subtypes:
1450  *                  The client may want to browse for only those ftp servers that allow
1451  *                  anonymous connections. The client will pass the string "_ftp._tcp,_anon"
1452  *                  to DNSServiceBrowse(), but the type of the service that's discovered
1453  *                  is simply "_ftp._tcp". The regtype for each discovered service instance
1454  *                  should be stored along with the name, so that it can be passed to
1455  *                  DNSServiceResolve() when the service is later resolved.
1456  *
1457  * domain:          The domain of the discovered service instance. This may or may not be the
1458  *                  same as the domain that was passed to DNSServiceBrowse(). The domain for each
1459  *                  discovered service instance should be stored along with the name, so that
1460  *                  it can be passed to DNSServiceResolve() when the service is later resolved.
1461  *
1462  * context:         The context pointer that was passed to the callout.
1463  *
1464  */
1465 
1466 typedef void (DNSSD_API *DNSServiceBrowseReply)
1467 (
1468     DNSServiceRef sdRef,
1469     DNSServiceFlags flags,
1470     uint32_t interfaceIndex,
1471     DNSServiceErrorType errorCode,
1472     const char                          *serviceName,
1473     const char                          *regtype,
1474     const char                          *replyDomain,
1475     void                                *context
1476 );
1477 
1478 
1479 /* DNSServiceBrowse() Parameters:
1480  *
1481  * sdRef:           A pointer to an uninitialized DNSServiceRef. If the call succeeds
1482  *                  then it initializes the DNSServiceRef, returns kDNSServiceErr_NoError,
1483  *                  and the browse operation will run indefinitely until the client
1484  *                  terminates it by passing this DNSServiceRef to DNSServiceRefDeallocate().
1485  *
1486  * flags:           Currently ignored, reserved for future use.
1487  *
1488  * interfaceIndex:  If non-zero, specifies the interface on which to browse for services
1489  *                  (the index for a given interface is determined via the if_nametoindex()
1490  *                  family of calls.) Most applications will pass 0 to browse on all available
1491  *                  interfaces. See "Constants for specifying an interface index" for more details.
1492  *
1493  * regtype:         The service type being browsed for followed by the protocol, separated by a
1494  *                  dot (e.g. "_ftp._tcp"). The transport protocol must be "_tcp" or "_udp".
1495  *                  A client may optionally specify a single subtype to perform filtered browsing:
1496  *                  e.g. browsing for "_primarytype._tcp,_subtype" will discover only those
1497  *                  instances of "_primarytype._tcp" that were registered specifying "_subtype"
1498  *                  in their list of registered subtypes. Additionally, a group identifier may
1499  *                  also be specified before the subtype e.g., _primarytype._tcp:GroupID, which
1500  *                  will discover only the members that register the service with GroupID. See
1501  *                  DNSServiceRegister for more details.
1502  *
1503  * domain:          If non-NULL, specifies the domain on which to browse for services.
1504  *                  Most applications will not specify a domain, instead browsing on the
1505  *                  default domain(s).
1506  *
1507  * callBack:        The function to be called when an instance of the service being browsed for
1508  *                  is found, or if the call asynchronously fails.
1509  *
1510  * context:         An application context pointer which is passed to the callback function
1511  *                  (may be NULL).
1512  *
1513  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
1514  *                  errors are delivered to the callback), otherwise returns an error code indicating
1515  *                  the error that occurred (the callback is not invoked and the DNSServiceRef
1516  *                  is not initialized).
1517  */
1518 
1519 DNSSD_EXPORT
1520 DNSServiceErrorType DNSSD_API DNSServiceBrowse
1521 (
1522     DNSServiceRef                       *sdRef,
1523     DNSServiceFlags flags,
1524     uint32_t interfaceIndex,
1525     const char                          *regtype,
1526     const char                          *domain,    /* may be NULL */
1527     DNSServiceBrowseReply callBack,
1528     void                                *context    /* may be NULL */
1529 );
1530 
1531 
1532 /* DNSServiceResolve()
1533  *
1534  * Resolve a service name discovered via DNSServiceBrowse() to a target host name, port number, and
1535  * txt record.
1536  *
1537  * Note: Applications should NOT use DNSServiceResolve() solely for txt record monitoring - use
1538  * DNSServiceQueryRecord() instead, as it is more efficient for this task.
1539  *
1540  * Note: When the desired results have been returned, the client MUST terminate the resolve by calling
1541  * DNSServiceRefDeallocate().
1542  *
1543  * Note: DNSServiceResolve() behaves correctly for typical services that have a single SRV record
1544  * and a single TXT record. To resolve non-standard services with multiple SRV or TXT records,
1545  * DNSServiceQueryRecord() should be used.
1546  *
1547  * DNSServiceResolveReply Callback Parameters:
1548  *
1549  * sdRef:           The DNSServiceRef initialized by DNSServiceResolve().
1550  *
1551  * flags:           Possible values: kDNSServiceFlagsMoreComing
1552  *
1553  * interfaceIndex:  The interface on which the service was resolved.
1554  *
1555  * errorCode:       Will be kDNSServiceErr_NoError (0) on success, otherwise will
1556  *                  indicate the failure that occurred. Other parameters are undefined if
1557  *                  the errorCode is nonzero.
1558  *
1559  * fullname:        The full service domain name, in the form <servicename>.<protocol>.<domain>.
1560  *                  (This name is escaped following standard DNS rules, making it suitable for
1561  *                  passing to standard system DNS APIs such as res_query(), or to the
1562  *                  special-purpose functions included in this API that take fullname parameters.
1563  *                  See "Notes on DNS Name Escaping" earlier in this file for more details.)
1564  *
1565  * hosttarget:      The target hostname of the machine providing the service. This name can
1566  *                  be passed to functions like gethostbyname() to identify the host's IP address.
1567  *
1568  * port:            The port, in network byte order, on which connections are accepted for this service.
1569  *
1570  * txtLen:          The length of the txt record, in bytes.
1571  *
1572  * txtRecord:       The service's primary txt record, in standard txt record format.
1573  *
1574  * context:         The context pointer that was passed to the callout.
1575  *
1576  * NOTE: In earlier versions of this header file, the txtRecord parameter was declared "const char *"
1577  * This is incorrect, since it contains length bytes which are values in the range 0 to 255, not -128 to +127.
1578  * Depending on your compiler settings, this change may cause signed/unsigned mismatch warnings.
1579  * These should be fixed by updating your own callback function definition to match the corrected
1580  * function signature using "const unsigned char *txtRecord". Making this change may also fix inadvertent
1581  * bugs in your callback function, where it could have incorrectly interpreted a length byte with value 250
1582  * as being -6 instead, with various bad consequences ranging from incorrect operation to software crashes.
1583  * If you need to maintain portable code that will compile cleanly with both the old and new versions of
1584  * this header file, you should update your callback function definition to use the correct unsigned value,
1585  * and then in the place where you pass your callback function to DNSServiceResolve(), use a cast to eliminate
1586  * the compiler warning, e.g.:
1587  *   DNSServiceResolve(sd, flags, index, name, regtype, domain, (DNSServiceResolveReply)MyCallback, context);
1588  * This will ensure that your code compiles cleanly without warnings (and more importantly, works correctly)
1589  * with both the old header and with the new corrected version.
1590  *
1591  */
1592 
1593 typedef void (DNSSD_API *DNSServiceResolveReply)
1594 (
1595     DNSServiceRef sdRef,
1596     DNSServiceFlags flags,
1597     uint32_t interfaceIndex,
1598     DNSServiceErrorType errorCode,
1599     const char                          *fullname,
1600     const char                          *hosttarget,
1601     uint16_t port,                                   /* In network byte order */
1602     uint16_t txtLen,
1603     const unsigned char                 *txtRecord,
1604     void                                *context
1605 );
1606 
1607 
1608 /* DNSServiceResolve() Parameters
1609  *
1610  * sdRef:           A pointer to an uninitialized DNSServiceRef. If the call succeeds
1611  *                  then it initializes the DNSServiceRef, returns kDNSServiceErr_NoError,
1612  *                  and the resolve operation will run indefinitely until the client
1613  *                  terminates it by passing this DNSServiceRef to DNSServiceRefDeallocate().
1614  *
1615  * flags:           Specifying kDNSServiceFlagsForceMulticast will cause query to be
1616  *                  performed with a link-local mDNS query, even if the name is an
1617  *                  apparently non-local name (i.e. a name not ending in ".local.")
1618  *
1619  * interfaceIndex:  The interface on which to resolve the service. If this resolve call is
1620  *                  as a result of a currently active DNSServiceBrowse() operation, then the
1621  *                  interfaceIndex should be the index reported in the DNSServiceBrowseReply
1622  *                  callback. If this resolve call is using information previously saved
1623  *                  (e.g. in a preference file) for later use, then use interfaceIndex 0, because
1624  *                  the desired service may now be reachable via a different physical interface.
1625  *                  See "Constants for specifying an interface index" for more details.
1626  *
1627  * name:            The name of the service instance to be resolved, as reported to the
1628  *                  DNSServiceBrowseReply() callback.
1629  *
1630  * regtype:         The type of the service instance to be resolved, as reported to the
1631  *                  DNSServiceBrowseReply() callback.
1632  *
1633  * domain:          The domain of the service instance to be resolved, as reported to the
1634  *                  DNSServiceBrowseReply() callback.
1635  *
1636  * callBack:        The function to be called when a result is found, or if the call
1637  *                  asynchronously fails.
1638  *
1639  * context:         An application context pointer which is passed to the callback function
1640  *                  (may be NULL).
1641  *
1642  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
1643  *                  errors are delivered to the callback), otherwise returns an error code indicating
1644  *                  the error that occurred (the callback is never invoked and the DNSServiceRef
1645  *                  is not initialized).
1646  */
1647 
1648 DNSSD_EXPORT
1649 DNSServiceErrorType DNSSD_API DNSServiceResolve
1650 (
1651     DNSServiceRef                       *sdRef,
1652     DNSServiceFlags flags,
1653     uint32_t interfaceIndex,
1654     const char                          *name,
1655     const char                          *regtype,
1656     const char                          *domain,
1657     DNSServiceResolveReply callBack,
1658     void                                *context  /* may be NULL */
1659 );
1660 
1661 
1662 /*********************************************************************************************
1663 *
1664 *  Querying Individual Specific Records
1665 *
1666 *********************************************************************************************/
1667 
1668 /* DNSServiceQueryRecord
1669  *
1670  * Query for an arbitrary DNS record.
1671  *
1672  * DNSServiceQueryRecordReply() Callback Parameters:
1673  *
1674  * sdRef:           The DNSServiceRef initialized by DNSServiceQueryRecord().
1675  *
1676  * flags:           Possible values are kDNSServiceFlagsMoreComing and
1677  *                  kDNSServiceFlagsAdd. The Add flag is NOT set for PTR records
1678  *                  with a ttl of 0, i.e. "Remove" events.
1679  *
1680  * interfaceIndex:  The interface on which the query was resolved (the index for a given
1681  *                  interface is determined via the if_nametoindex() family of calls).
1682  *                  See "Constants for specifying an interface index" for more details.
1683  *
1684  * errorCode:       Will be kDNSServiceErr_NoError on success, otherwise will
1685  *                  indicate the failure that occurred. Other parameters are undefined if
1686  *                  errorCode is nonzero.
1687  *
1688  * fullname:        The resource record's full domain name.
1689  *
1690  * rrtype:          The resource record's type (e.g. kDNSServiceType_PTR, kDNSServiceType_SRV, etc)
1691  *
1692  * rrclass:         The class of the resource record (usually kDNSServiceClass_IN).
1693  *
1694  * rdlen:           The length, in bytes, of the resource record rdata.
1695  *
1696  * rdata:           The raw rdata of the resource record.
1697  *
1698  * ttl:             If the client wishes to cache the result for performance reasons,
1699  *                  the TTL indicates how long the client may legitimately hold onto
1700  *                  this result, in seconds. After the TTL expires, the client should
1701  *                  consider the result no longer valid, and if it requires this data
1702  *                  again, it should be re-fetched with a new query. Of course, this
1703  *                  only applies to clients that cancel the asynchronous operation when
1704  *                  they get a result. Clients that leave the asynchronous operation
1705  *                  running can safely assume that the data remains valid until they
1706  *                  get another callback telling them otherwise. The ttl value is not
1707  *                  updated when the daemon answers from the cache, hence relying on
1708  *                  the accuracy of the ttl value is not recommended.
1709  *
1710  * context:         The context pointer that was passed to the callout.
1711  *
1712  */
1713 
1714 typedef void (DNSSD_API *DNSServiceQueryRecordReply)
1715 (
1716     DNSServiceRef sdRef,
1717     DNSServiceFlags flags,
1718     uint32_t interfaceIndex,
1719     DNSServiceErrorType errorCode,
1720     const char                          *fullname,
1721     uint16_t rrtype,
1722     uint16_t rrclass,
1723     uint16_t rdlen,
1724     const void                          *rdata,
1725     uint32_t ttl,
1726     void                                *context
1727 );
1728 
1729 
1730 /* DNSServiceQueryRecord() Parameters:
1731  *
1732  * sdRef:           A pointer to an uninitialized DNSServiceRef. If the call succeeds
1733  *                  then it initializes the DNSServiceRef, returns kDNSServiceErr_NoError,
1734  *                  and the query operation will run indefinitely until the client
1735  *                  terminates it by passing this DNSServiceRef to DNSServiceRefDeallocate().
1736  *
1737  * flags:           kDNSServiceFlagsForceMulticast or kDNSServiceFlagsLongLivedQuery.
1738  *                  Pass kDNSServiceFlagsLongLivedQuery to create a "long-lived" unicast
1739  *                  query to a unicast DNS server that implements the protocol. This flag
1740  *                  has no effect on link-local multicast queries.
1741  *
1742  * interfaceIndex:  If non-zero, specifies the interface on which to issue the query
1743  *                  (the index for a given interface is determined via the if_nametoindex()
1744  *                  family of calls.) Passing 0 causes the name to be queried for on all
1745  *                  interfaces. See "Constants for specifying an interface index" for more details.
1746  *
1747  * fullname:        The full domain name of the resource record to be queried for.
1748  *
1749  * rrtype:          The numerical type of the resource record to be queried for
1750  *                  (e.g. kDNSServiceType_PTR, kDNSServiceType_SRV, etc)
1751  *
1752  * rrclass:         The class of the resource record (usually kDNSServiceClass_IN).
1753  *
1754  * callBack:        The function to be called when a result is found, or if the call
1755  *                  asynchronously fails.
1756  *
1757  * context:         An application context pointer which is passed to the callback function
1758  *                  (may be NULL).
1759  *
1760  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
1761  *                  errors are delivered to the callback), otherwise returns an error code indicating
1762  *                  the error that occurred (the callback is never invoked and the DNSServiceRef
1763  *                  is not initialized).
1764  */
1765 
1766 DNSSD_EXPORT
1767 DNSServiceErrorType DNSSD_API DNSServiceQueryRecord
1768 (
1769     DNSServiceRef                       *sdRef,
1770     DNSServiceFlags flags,
1771     uint32_t interfaceIndex,
1772     const char                          *fullname,
1773     uint16_t rrtype,
1774     uint16_t rrclass,
1775     DNSServiceQueryRecordReply callBack,
1776     void                                *context  /* may be NULL */
1777 );
1778 
1779 
1780 /*********************************************************************************************
1781 *
1782 *  Unified lookup of both IPv4 and IPv6 addresses for a fully qualified hostname
1783 *
1784 *********************************************************************************************/
1785 
1786 /* DNSServiceGetAddrInfo
1787  *
1788  * Queries for the IP address of a hostname by using either Multicast or Unicast DNS.
1789  *
1790  * DNSServiceGetAddrInfoReply() parameters:
1791  *
1792  * sdRef:           The DNSServiceRef initialized by DNSServiceGetAddrInfo().
1793  *
1794  * flags:           Possible values are kDNSServiceFlagsMoreComing and
1795  *                  kDNSServiceFlagsAdd.
1796  *
1797  * interfaceIndex:  The interface to which the answers pertain.
1798  *
1799  * errorCode:       Will be kDNSServiceErr_NoError on success, otherwise will
1800  *                  indicate the failure that occurred.  Other parameters are
1801  *                  undefined if errorCode is nonzero.
1802  *
1803  * hostname:        The fully qualified domain name of the host to be queried for.
1804  *
1805  * address:         IPv4 or IPv6 address.
1806  *
1807  * ttl:             If the client wishes to cache the result for performance reasons,
1808  *                  the TTL indicates how long the client may legitimately hold onto
1809  *                  this result, in seconds. After the TTL expires, the client should
1810  *                  consider the result no longer valid, and if it requires this data
1811  *                  again, it should be re-fetched with a new query. Of course, this
1812  *                  only applies to clients that cancel the asynchronous operation when
1813  *                  they get a result. Clients that leave the asynchronous operation
1814  *                  running can safely assume that the data remains valid until they
1815  *                  get another callback telling them otherwise. The ttl value is not
1816  *                  updated when the daemon answers from the cache, hence relying on
1817  *                  the accuracy of the ttl value is not recommended.
1818  *
1819  * context:         The context pointer that was passed to the callout.
1820  *
1821  */
1822 
1823 typedef void (DNSSD_API *DNSServiceGetAddrInfoReply)
1824 (
1825     DNSServiceRef sdRef,
1826     DNSServiceFlags flags,
1827     uint32_t interfaceIndex,
1828     DNSServiceErrorType errorCode,
1829     const char                       *hostname,
1830     const struct sockaddr            *address,
1831     uint32_t ttl,
1832     void                             *context
1833 );
1834 
1835 
1836 /* DNSServiceGetAddrInfo() Parameters:
1837  *
1838  * sdRef:           A pointer to an uninitialized DNSServiceRef. If the call succeeds then it
1839  *                  initializes the DNSServiceRef, returns kDNSServiceErr_NoError, and the query
1840  *                  begins and will last indefinitely until the client terminates the query
1841  *                  by passing this DNSServiceRef to DNSServiceRefDeallocate().
1842  *
1843  * flags:           kDNSServiceFlagsForceMulticast
1844  *
1845  * interfaceIndex:  The interface on which to issue the query.  Passing 0 causes the query to be
1846  *                  sent on all active interfaces via Multicast or the primary interface via Unicast.
1847  *
1848  * protocol:        Pass in kDNSServiceProtocol_IPv4 to look up IPv4 addresses, or kDNSServiceProtocol_IPv6
1849  *                  to look up IPv6 addresses, or both to look up both kinds. If neither flag is
1850  *                  set, the system will apply an intelligent heuristic, which is (currently)
1851  *                  that it will attempt to look up both, except:
1852  *
1853  *                   * If "hostname" is a wide-area unicast DNS hostname (i.e. not a ".local." name)
1854  *                     but this host has no routable IPv6 address, then the call will not try to
1855  *                     look up IPv6 addresses for "hostname", since any addresses it found would be
1856  *                     unlikely to be of any use anyway. Similarly, if this host has no routable
1857  *                     IPv4 address, the call will not try to look up IPv4 addresses for "hostname".
1858  *
1859  * hostname:        The fully qualified domain name of the host to be queried for.
1860  *
1861  * callBack:        The function to be called when the query succeeds or fails asynchronously.
1862  *
1863  * context:         An application context pointer which is passed to the callback function
1864  *                  (may be NULL).
1865  *
1866  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
1867  *                  errors are delivered to the callback), otherwise returns an error code indicating
1868  *                  the error that occurred.
1869  */
1870 
1871 DNSSD_EXPORT
1872 DNSServiceErrorType DNSSD_API DNSServiceGetAddrInfo
1873 (
1874     DNSServiceRef                    *sdRef,
1875     DNSServiceFlags flags,
1876     uint32_t interfaceIndex,
1877     DNSServiceProtocol protocol,
1878     const char                       *hostname,
1879     DNSServiceGetAddrInfoReply callBack,
1880     void                             *context          /* may be NULL */
1881 );
1882 
1883 
1884 /*********************************************************************************************
1885 *
1886 *  Special Purpose Calls:
1887 *  DNSServiceCreateConnection(), DNSServiceRegisterRecord(), DNSServiceReconfirmRecord()
1888 *  (most applications will not use these)
1889 *
1890 *********************************************************************************************/
1891 
1892 /* DNSServiceCreateConnection()
1893  *
1894  * Create a connection to the daemon allowing efficient registration of
1895  * multiple individual records.
1896  *
1897  * Parameters:
1898  *
1899  * sdRef:           A pointer to an uninitialized DNSServiceRef. Deallocating
1900  *                  the reference (via DNSServiceRefDeallocate()) severs the
1901  *                  connection and deregisters all records registered on this connection.
1902  *
1903  * return value:    Returns kDNSServiceErr_NoError on success, otherwise returns
1904  *                  an error code indicating the specific failure that occurred (in which
1905  *                  case the DNSServiceRef is not initialized).
1906  */
1907 
1908 DNSSD_EXPORT
1909 DNSServiceErrorType DNSSD_API DNSServiceCreateConnection(DNSServiceRef *sdRef);
1910 
1911 /* DNSServiceRegisterRecord
1912  *
1913  * Register an individual resource record on a connected DNSServiceRef.
1914  *
1915  * Note that name conflicts occurring for records registered via this call must be handled
1916  * by the client in the callback.
1917  *
1918  * DNSServiceRegisterRecordReply() parameters:
1919  *
1920  * sdRef:           The connected DNSServiceRef initialized by
1921  *                  DNSServiceCreateConnection().
1922  *
1923  * RecordRef:       The DNSRecordRef initialized by DNSServiceRegisterRecord(). If the above
1924  *                  DNSServiceRef is passed to DNSServiceRefDeallocate(), this DNSRecordRef is
1925  *                  invalidated, and may not be used further.
1926  *
1927  * flags:           Currently unused, reserved for future use.
1928  *
1929  * errorCode:       Will be kDNSServiceErr_NoError on success, otherwise will
1930  *                  indicate the failure that occurred (including name conflicts.)
1931  *                  Other parameters are undefined if errorCode is nonzero.
1932  *
1933  * context:         The context pointer that was passed to the callout.
1934  *
1935  */
1936 
1937 typedef void (DNSSD_API *DNSServiceRegisterRecordReply)
1938 (
1939     DNSServiceRef sdRef,
1940     DNSRecordRef RecordRef,
1941     DNSServiceFlags flags,
1942     DNSServiceErrorType errorCode,
1943     void                                *context
1944 );
1945 
1946 
1947 /* DNSServiceRegisterRecord() Parameters:
1948  *
1949  * sdRef:           A DNSServiceRef initialized by DNSServiceCreateConnection().
1950  *
1951  * RecordRef:       A pointer to an uninitialized DNSRecordRef. Upon succesfull completion of this
1952  *                  call, this ref may be passed to DNSServiceUpdateRecord() or DNSServiceRemoveRecord().
1953  *                  (To deregister ALL records registered on a single connected DNSServiceRef
1954  *                  and deallocate each of their corresponding DNSServiceRecordRefs, call
1955  *                  DNSServiceRefDeallocate()).
1956  *
1957  * flags:           Possible values are kDNSServiceFlagsShared or kDNSServiceFlagsUnique
1958  *                  (see flag type definitions for details).
1959  *
1960  * interfaceIndex:  If non-zero, specifies the interface on which to register the record
1961  *                  (the index for a given interface is determined via the if_nametoindex()
1962  *                  family of calls.) Passing 0 causes the record to be registered on all interfaces.
1963  *                  See "Constants for specifying an interface index" for more details.
1964  *
1965  * fullname:        The full domain name of the resource record.
1966  *
1967  * rrtype:          The numerical type of the resource record (e.g. kDNSServiceType_PTR, kDNSServiceType_SRV, etc)
1968  *
1969  * rrclass:         The class of the resource record (usually kDNSServiceClass_IN)
1970  *
1971  * rdlen:           Length, in bytes, of the rdata.
1972  *
1973  * rdata:           A pointer to the raw rdata, as it is to appear in the DNS record.
1974  *
1975  * ttl:             The time to live of the resource record, in seconds.
1976  *                  Most clients should pass 0 to indicate that the system should
1977  *                  select a sensible default value.
1978  *
1979  * callBack:        The function to be called when a result is found, or if the call
1980  *                  asynchronously fails (e.g. because of a name conflict.)
1981  *
1982  * context:         An application context pointer which is passed to the callback function
1983  *                  (may be NULL).
1984  *
1985  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
1986  *                  errors are delivered to the callback), otherwise returns an error code indicating
1987  *                  the error that occurred (the callback is never invoked and the DNSRecordRef is
1988  *                  not initialized).
1989  */
1990 
1991 DNSSD_EXPORT
1992 DNSServiceErrorType DNSSD_API DNSServiceRegisterRecord
1993 (
1994     DNSServiceRef sdRef,
1995     DNSRecordRef                        *RecordRef,
1996     DNSServiceFlags flags,
1997     uint32_t interfaceIndex,
1998     const char                          *fullname,
1999     uint16_t rrtype,
2000     uint16_t rrclass,
2001     uint16_t rdlen,
2002     const void                          *rdata,
2003     uint32_t ttl,
2004     DNSServiceRegisterRecordReply callBack,
2005     void                                *context    /* may be NULL */
2006 );
2007 
2008 
2009 /* DNSServiceReconfirmRecord
2010  *
2011  * Instruct the daemon to verify the validity of a resource record that appears
2012  * to be out of date (e.g. because TCP connection to a service's target failed.)
2013  * Causes the record to be flushed from the daemon's cache (as well as all other
2014  * daemons' caches on the network) if the record is determined to be invalid.
2015  * Use this routine conservatively. Reconfirming a record necessarily consumes
2016  * network bandwidth, so this should not be done indiscriminately.
2017  *
2018  * Parameters:
2019  *
2020  * flags:           Not currently used.
2021  *
2022  * interfaceIndex:  Specifies the interface of the record in question.
2023  *                  The caller must specify the interface.
2024  *                  This API (by design) causes increased network traffic, so it requires
2025  *                  the caller to be precise about which record should be reconfirmed.
2026  *                  It is not possible to pass zero for the interface index to perform
2027  *                  a "wildcard" reconfirmation, where *all* matching records are reconfirmed.
2028  *
2029  * fullname:        The resource record's full domain name.
2030  *
2031  * rrtype:          The resource record's type (e.g. kDNSServiceType_PTR, kDNSServiceType_SRV, etc)
2032  *
2033  * rrclass:         The class of the resource record (usually kDNSServiceClass_IN).
2034  *
2035  * rdlen:           The length, in bytes, of the resource record rdata.
2036  *
2037  * rdata:           The raw rdata of the resource record.
2038  *
2039  */
2040 
2041 DNSSD_EXPORT
2042 DNSServiceErrorType DNSSD_API DNSServiceReconfirmRecord
2043 (
2044     DNSServiceFlags flags,
2045     uint32_t interfaceIndex,
2046     const char                         *fullname,
2047     uint16_t rrtype,
2048     uint16_t rrclass,
2049     uint16_t rdlen,
2050     const void                         *rdata
2051 );
2052 
2053 
2054 /*********************************************************************************************
2055 *
2056 *  NAT Port Mapping
2057 *
2058 *********************************************************************************************/
2059 
2060 /* DNSServiceNATPortMappingCreate
2061  *
2062  * Request a port mapping in the NAT gateway, which maps a port on the local machine
2063  * to an external port on the NAT. The NAT should support either PCP, NAT-PMP or the
2064  * UPnP/IGD protocol for this API to create a successful mapping. Note that this API
2065  * currently supports IPv4 addresses/mappings only. If the NAT gateway supports PCP and
2066  * returns an IPv6 address (incorrectly, since this API specifically requests IPv4
2067  * addresses), the DNSServiceNATPortMappingReply callback will be invoked with errorCode
2068  * kDNSServiceErr_NATPortMappingUnsupported.
2069  *
2070  * The port mapping will be renewed indefinitely until the client process exits, or
2071  * explicitly terminates the port mapping request by calling DNSServiceRefDeallocate().
2072  * The client callback will be invoked, informing the client of the NAT gateway's
2073  * external IP address and the external port that has been allocated for this client.
2074  * The client should then record this external IP address and port using whatever
2075  * directory service mechanism it is using to enable peers to connect to it.
2076  * (Clients advertising services using Wide-Area DNS-SD DO NOT need to use this API
2077  * -- when a client calls DNSServiceRegister() NAT mappings are automatically created
2078  * and the external IP address and port for the service are recorded in the global DNS.
2079  * Only clients using some directory mechanism other than Wide-Area DNS-SD need to use
2080  * this API to explicitly map their own ports.)
2081  *
2082  * It's possible that the client callback could be called multiple times, for example
2083  * if the NAT gateway's IP address changes, or if a configuration change results in a
2084  * different external port being mapped for this client. Over the lifetime of any long-lived
2085  * port mapping, the client should be prepared to handle these notifications of changes
2086  * in the environment, and should update its recorded address and/or port as appropriate.
2087  *
2088  * NOTE: There are two unusual aspects of how the DNSServiceNATPortMappingCreate API works,
2089  * which were intentionally designed to help simplify client code:
2090  *
2091  *  1. It's not an error to request a NAT mapping when the machine is not behind a NAT gateway.
2092  *     In other NAT mapping APIs, if you request a NAT mapping and the machine is not behind a NAT
2093  *     gateway, then the API returns an error code -- it can't get you a NAT mapping if there's no
2094  *     NAT gateway. The DNSServiceNATPortMappingCreate API takes a different view. Working out
2095  *     whether or not you need a NAT mapping can be tricky and non-obvious, particularly on
2096  *     a machine with multiple active network interfaces. Rather than make every client recreate
2097  *     this logic for deciding whether a NAT mapping is required, the PortMapping API does that
2098  *     work for you. If the client calls the PortMapping API when the machine already has a
2099  *     routable public IP address, then instead of complaining about it and giving an error,
2100  *     the PortMapping API just invokes your callback, giving the machine's public address
2101  *     and your own port number. This means you don't need to write code to work out whether
2102  *     your client needs to call the PortMapping API -- just call it anyway, and if it wasn't
2103  *     necessary, no harm is done:
2104  *
2105  *     - If the machine already has a routable public IP address, then your callback
2106  *       will just be invoked giving your own address and port.
2107  *     - If a NAT mapping is required and obtained, then your callback will be invoked
2108  *       giving you the external address and port.
2109  *     - If a NAT mapping is required but not obtained from the local NAT gateway,
2110  *       or the machine has no network connectivity, then your callback will be
2111  *       invoked giving zero address and port.
2112  *
2113  *  2. In other NAT mapping APIs, if a laptop computer is put to sleep and woken up on a new
2114  *     network, it's the client's job to notice this, and work out whether a NAT mapping
2115  *     is required on the new network, and make a new NAT mapping request if necessary.
2116  *     The DNSServiceNATPortMappingCreate API does this for you, automatically.
2117  *     The client just needs to make one call to the PortMapping API, and its callback will
2118  *     be invoked any time the mapping state changes. This property complements point (1) above.
2119  *     If the client didn't make a NAT mapping request just because it determined that one was
2120  *     not required at that particular moment in time, the client would then have to monitor
2121  *     for network state changes to determine if a NAT port mapping later became necessary.
2122  *     By unconditionally making a NAT mapping request, even when a NAT mapping not to be
2123  *     necessary, the PortMapping API will then begin monitoring network state changes on behalf of
2124  *     the client, and if a NAT mapping later becomes necessary, it will automatically create a NAT
2125  *     mapping and inform the client with a new callback giving the new address and port information.
2126  *
2127  * DNSServiceNATPortMappingReply() parameters:
2128  *
2129  * sdRef:           The DNSServiceRef initialized by DNSServiceNATPortMappingCreate().
2130  *
2131  * flags:           Currently unused, reserved for future use.
2132  *
2133  * interfaceIndex:  The interface through which the NAT gateway is reached.
2134  *
2135  * errorCode:       Will be kDNSServiceErr_NoError on success.
2136  *                  Will be kDNSServiceErr_DoubleNAT when the NAT gateway is itself behind one or
2137  *                  more layers of NAT, in which case the other parameters have the defined values.
2138  *                  For other failures, will indicate the failure that occurred, and the other
2139  *                  parameters are undefined.
2140  *
2141  * externalAddress: Four byte IPv4 address in network byte order.
2142  *
2143  * protocol:        Will be kDNSServiceProtocol_UDP or kDNSServiceProtocol_TCP or both.
2144  *
2145  * internalPort:    The port on the local machine that was mapped.
2146  *
2147  * externalPort:    The actual external port in the NAT gateway that was mapped.
2148  *                  This is likely to be different than the requested external port.
2149  *
2150  * ttl:             The lifetime of the NAT port mapping created on the gateway.
2151  *                  This controls how quickly stale mappings will be garbage-collected
2152  *                  if the client machine crashes, suffers a power failure, is disconnected
2153  *                  from the network, or suffers some other unfortunate demise which
2154  *                  causes it to vanish without explicitly removing its NAT port mapping.
2155  *                  It's possible that the ttl value will differ from the requested ttl value.
2156  *
2157  * context:         The context pointer that was passed to the callout.
2158  *
2159  */
2160 
2161 typedef void (DNSSD_API *DNSServiceNATPortMappingReply)
2162 (
2163     DNSServiceRef sdRef,
2164     DNSServiceFlags flags,
2165     uint32_t interfaceIndex,
2166     DNSServiceErrorType errorCode,
2167     uint32_t externalAddress,                           /* four byte IPv4 address in network byte order */
2168     DNSServiceProtocol protocol,
2169     uint16_t internalPort,                              /* In network byte order */
2170     uint16_t externalPort,                              /* In network byte order and may be different than the requested port */
2171     uint32_t ttl,                                       /* may be different than the requested ttl */
2172     void                             *context
2173 );
2174 
2175 
2176 /* DNSServiceNATPortMappingCreate() Parameters:
2177  *
2178  * sdRef:           A pointer to an uninitialized DNSServiceRef. If the call succeeds then it
2179  *                  initializes the DNSServiceRef, returns kDNSServiceErr_NoError, and the nat
2180  *                  port mapping will last indefinitely until the client terminates the port
2181  *                  mapping request by passing this DNSServiceRef to DNSServiceRefDeallocate().
2182  *
2183  * flags:           Currently ignored, reserved for future use.
2184  *
2185  * interfaceIndex:  The interface on which to create port mappings in a NAT gateway. Passing 0 causes
2186  *                  the port mapping request to be sent on the primary interface.
2187  *
2188  * protocol:        To request a port mapping, pass in kDNSServiceProtocol_UDP, or kDNSServiceProtocol_TCP,
2189  *                  or (kDNSServiceProtocol_UDP | kDNSServiceProtocol_TCP) to map both.
2190  *                  The local listening port number must also be specified in the internalPort parameter.
2191  *                  To just discover the NAT gateway's external IP address, pass zero for protocol,
2192  *                  internalPort, externalPort and ttl.
2193  *
2194  * internalPort:    The port number in network byte order on the local machine which is listening for packets.
2195  *
2196  * externalPort:    The requested external port in network byte order in the NAT gateway that you would
2197  *                  like to map to the internal port. Pass 0 if you don't care which external port is chosen for you.
2198  *
2199  * ttl:             The requested renewal period of the NAT port mapping, in seconds.
2200  *                  If the client machine crashes, suffers a power failure, is disconnected from
2201  *                  the network, or suffers some other unfortunate demise which causes it to vanish
2202  *                  unexpectedly without explicitly removing its NAT port mappings, then the NAT gateway
2203  *                  will garbage-collect old stale NAT port mappings when their lifetime expires.
2204  *                  Requesting a short TTL causes such orphaned mappings to be garbage-collected
2205  *                  more promptly, but consumes system resources and network bandwidth with
2206  *                  frequent renewal packets to keep the mapping from expiring.
2207  *                  Requesting a long TTL is more efficient on the network, but in the event of the
2208  *                  client vanishing, stale NAT port mappings will not be garbage-collected as quickly.
2209  *                  Most clients should pass 0 to use a system-wide default value.
2210  *
2211  * callBack:        The function to be called when the port mapping request succeeds or fails asynchronously.
2212  *
2213  * context:         An application context pointer which is passed to the callback function
2214  *                  (may be NULL).
2215  *
2216  * return value:    Returns kDNSServiceErr_NoError on success (any subsequent, asynchronous
2217  *                  errors are delivered to the callback), otherwise returns an error code indicating
2218  *                  the error that occurred.
2219  *
2220  *                  If you don't actually want a port mapped, and are just calling the API
2221  *                  because you want to find out the NAT's external IP address (e.g. for UI
2222  *                  display) then pass zero for protocol, internalPort, externalPort and ttl.
2223  */
2224 
2225 DNSSD_EXPORT
2226 DNSServiceErrorType DNSSD_API DNSServiceNATPortMappingCreate
2227 (
2228     DNSServiceRef                    *sdRef,
2229     DNSServiceFlags flags,
2230     uint32_t interfaceIndex,
2231     DNSServiceProtocol protocol,                        /* TCP and/or UDP          */
2232     uint16_t internalPort,                              /* network byte order      */
2233     uint16_t externalPort,                              /* network byte order      */
2234     uint32_t ttl,                                       /* time to live in seconds */
2235     DNSServiceNATPortMappingReply callBack,
2236     void                             *context           /* may be NULL             */
2237 );
2238 
2239 
2240 /*********************************************************************************************
2241 *
2242 *  General Utility Functions
2243 *
2244 *********************************************************************************************/
2245 
2246 /* DNSServiceConstructFullName()
2247  *
2248  * Concatenate a three-part domain name (as returned by the above callbacks) into a
2249  * properly-escaped full domain name. Note that callbacks in the above functions ALREADY ESCAPE
2250  * strings where necessary.
2251  *
2252  * Parameters:
2253  *
2254  * fullName:        A pointer to a buffer that where the resulting full domain name is to be written.
2255  *                  The buffer must be kDNSServiceMaxDomainName (1009) bytes in length to
2256  *                  accommodate the longest legal domain name without buffer overrun.
2257  *
2258  * service:         The service name - any dots or backslashes must NOT be escaped.
2259  *                  May be NULL (to construct a PTR record name, e.g.
2260  *                  "_ftp._tcp.apple.com.").
2261  *
2262  * regtype:         The service type followed by the protocol, separated by a dot
2263  *                  (e.g. "_ftp._tcp").
2264  *
2265  * domain:          The domain name, e.g. "apple.com.". Literal dots or backslashes,
2266  *                  if any, must be escaped, e.g. "1st\. Floor.apple.com."
2267  *
2268  * return value:    Returns kDNSServiceErr_NoError (0) on success, kDNSServiceErr_BadParam on error.
2269  *
2270  */
2271 
2272 DNSSD_EXPORT
2273 DNSServiceErrorType DNSSD_API DNSServiceConstructFullName
2274 (
2275     char                            * const fullName,
2276     const char                      * const service,      /* may be NULL */
2277     const char                      * const regtype,
2278     const char                      * const domain
2279 );
2280 
2281 
2282 /*********************************************************************************************
2283 *
2284 *   TXT Record Construction Functions
2285 *
2286 *********************************************************************************************/
2287 
2288 /*
2289  * A typical calling sequence for TXT record construction is something like:
2290  *
2291  * Client allocates storage for TXTRecord data (e.g. declare buffer on the stack)
2292  * TXTRecordCreate();
2293  * TXTRecordSetValue();
2294  * TXTRecordSetValue();
2295  * TXTRecordSetValue();
2296  * ...
2297  * DNSServiceRegister( ... TXTRecordGetLength(), TXTRecordGetBytesPtr() ... );
2298  * TXTRecordDeallocate();
2299  * Explicitly deallocate storage for TXTRecord data (if not allocated on the stack)
2300  */
2301 
2302 
2303 /* TXTRecordRef
2304  *
2305  * Opaque internal data type.
2306  * Note: Represents a DNS-SD TXT record.
2307  */
2308 
2309 typedef union _TXTRecordRef_t { char PrivateData[16]; char *ForceNaturalAlignment; } TXTRecordRef;
2310 
2311 
2312 /* TXTRecordCreate()
2313  *
2314  * Creates a new empty TXTRecordRef referencing the specified storage.
2315  *
2316  * If the buffer parameter is NULL, or the specified storage size is not
2317  * large enough to hold a key subsequently added using TXTRecordSetValue(),
2318  * then additional memory will be added as needed using malloc().
2319  *
2320  * On some platforms, when memory is low, malloc() may fail. In this
2321  * case, TXTRecordSetValue() will return kDNSServiceErr_NoMemory, and this
2322  * error condition will need to be handled as appropriate by the caller.
2323  *
2324  * You can avoid the need to handle this error condition if you ensure
2325  * that the storage you initially provide is large enough to hold all
2326  * the key/value pairs that are to be added to the record.
2327  * The caller can precompute the exact length required for all of the
2328  * key/value pairs to be added, or simply provide a fixed-sized buffer
2329  * known in advance to be large enough.
2330  * A no-value (key-only) key requires  (1 + key length) bytes.
2331  * A key with empty value requires     (1 + key length + 1) bytes.
2332  * A key with non-empty value requires (1 + key length + 1 + value length).
2333  * For most applications, DNS-SD TXT records are generally
2334  * less than 100 bytes, so in most cases a simple fixed-sized
2335  * 256-byte buffer will be more than sufficient.
2336  * Recommended size limits for DNS-SD TXT Records are discussed in RFC 6763
2337  * <https://tools.ietf.org/html/rfc6763#section-6.2>
2338  *
2339  * Note: When passing parameters to and from these TXT record APIs,
2340  * the key name does not include the '=' character. The '=' character
2341  * is the separator between the key and value in the on-the-wire
2342  * packet format; it is not part of either the key or the value.
2343  *
2344  * txtRecord:       A pointer to an uninitialized TXTRecordRef.
2345  *
2346  * bufferLen:       The size of the storage provided in the "buffer" parameter.
2347  *
2348  * buffer:          Optional caller-supplied storage used to hold the TXTRecord data.
2349  *                  This storage must remain valid for as long as
2350  *                  the TXTRecordRef.
2351  */
2352 
2353 DNSSD_EXPORT
2354 void DNSSD_API TXTRecordCreate
2355 (
2356     TXTRecordRef     *txtRecord,
2357     uint16_t bufferLen,
2358     void             *buffer
2359 );
2360 
2361 
2362 /* TXTRecordDeallocate()
2363  *
2364  * Releases any resources allocated in the course of preparing a TXT Record
2365  * using TXTRecordCreate()/TXTRecordSetValue()/TXTRecordRemoveValue().
2366  * Ownership of the buffer provided in TXTRecordCreate() returns to the client.
2367  *
2368  * txtRecord:           A TXTRecordRef initialized by calling TXTRecordCreate().
2369  *
2370  */
2371 
2372 DNSSD_EXPORT
2373 void DNSSD_API TXTRecordDeallocate
2374 (
2375     TXTRecordRef     *txtRecord
2376 );
2377 
2378 
2379 /* TXTRecordSetValue()
2380  *
2381  * Adds a key (optionally with value) to a TXTRecordRef. If the "key" already
2382  * exists in the TXTRecordRef, then the current value will be replaced with
2383  * the new value.
2384  * Keys may exist in four states with respect to a given TXT record:
2385  *  - Absent (key does not appear at all)
2386  *  - Present with no value ("key" appears alone)
2387  *  - Present with empty value ("key=" appears in TXT record)
2388  *  - Present with non-empty value ("key=value" appears in TXT record)
2389  * For more details refer to "Data Syntax for DNS-SD TXT Records" in RFC 6763
2390  * <https://tools.ietf.org/html/rfc6763#section-6>
2391  *
2392  * txtRecord:       A TXTRecordRef initialized by calling TXTRecordCreate().
2393  *
2394  * key:             A null-terminated string which only contains printable ASCII
2395  *                  values (0x20-0x7E), excluding '=' (0x3D). Keys should be
2396  *                  9 characters or fewer (not counting the terminating null).
2397  *
2398  * valueSize:       The size of the value.
2399  *
2400  * value:           Any binary value. For values that represent
2401  *                  textual data, UTF-8 is STRONGLY recommended.
2402  *                  For values that represent textual data, valueSize
2403  *                  should NOT include the terminating null (if any)
2404  *                  at the end of the string.
2405  *                  If NULL, then "key" will be added with no value.
2406  *                  If non-NULL but valueSize is zero, then "key=" will be
2407  *                  added with empty value.
2408  *
2409  * return value:    Returns kDNSServiceErr_NoError on success.
2410  *                  Returns kDNSServiceErr_Invalid if the "key" string contains
2411  *                  illegal characters.
2412  *                  Returns kDNSServiceErr_NoMemory if adding this key would
2413  *                  exceed the available storage.
2414  */
2415 
2416 DNSSD_EXPORT
2417 DNSServiceErrorType DNSSD_API TXTRecordSetValue
2418 (
2419     TXTRecordRef     *txtRecord,
2420     const char       *key,
2421     uint8_t valueSize,                 /* may be zero */
2422     const void       *value            /* may be NULL */
2423 );
2424 
2425 
2426 /* TXTRecordRemoveValue()
2427  *
2428  * Removes a key from a TXTRecordRef. The "key" must be an
2429  * ASCII string which exists in the TXTRecordRef.
2430  *
2431  * txtRecord:       A TXTRecordRef initialized by calling TXTRecordCreate().
2432  *
2433  * key:             A key name which exists in the TXTRecordRef.
2434  *
2435  * return value:    Returns kDNSServiceErr_NoError on success.
2436  *                  Returns kDNSServiceErr_NoSuchKey if the "key" does not
2437  *                  exist in the TXTRecordRef.
2438  */
2439 
2440 DNSSD_EXPORT
2441 DNSServiceErrorType DNSSD_API TXTRecordRemoveValue
2442 (
2443     TXTRecordRef     *txtRecord,
2444     const char       *key
2445 );
2446 
2447 
2448 /* TXTRecordGetLength()
2449  *
2450  * Allows you to determine the length of the raw bytes within a TXTRecordRef.
2451  *
2452  * txtRecord:       A TXTRecordRef initialized by calling TXTRecordCreate().
2453  *
2454  * return value:    Returns the size of the raw bytes inside a TXTRecordRef
2455  *                  which you can pass directly to DNSServiceRegister() or
2456  *                  to DNSServiceUpdateRecord().
2457  *                  Returns 0 if the TXTRecordRef is empty.
2458  */
2459 
2460 DNSSD_EXPORT
2461 uint16_t DNSSD_API TXTRecordGetLength
2462 (
2463     const TXTRecordRef *txtRecord
2464 );
2465 
2466 
2467 /* TXTRecordGetBytesPtr()
2468  *
2469  * Allows you to retrieve a pointer to the raw bytes within a TXTRecordRef.
2470  *
2471  * txtRecord:       A TXTRecordRef initialized by calling TXTRecordCreate().
2472  *
2473  * return value:    Returns a pointer to the raw bytes inside the TXTRecordRef
2474  *                  which you can pass directly to DNSServiceRegister() or
2475  *                  to DNSServiceUpdateRecord().
2476  */
2477 
2478 DNSSD_EXPORT
2479 const void * DNSSD_API TXTRecordGetBytesPtr
2480 (
2481     const TXTRecordRef *txtRecord
2482 );
2483 
2484 
2485 /*********************************************************************************************
2486 *
2487 *   TXT Record Parsing Functions
2488 *
2489 *********************************************************************************************/
2490 
2491 /*
2492  * A typical calling sequence for TXT record parsing is something like:
2493  *
2494  * Receive TXT record data in DNSServiceResolve() callback
2495  * if (TXTRecordContainsKey(txtLen, txtRecord, "key")) then do something
2496  * val1ptr = TXTRecordGetValuePtr(txtLen, txtRecord, "key1", &len1);
2497  * val2ptr = TXTRecordGetValuePtr(txtLen, txtRecord, "key2", &len2);
2498  * ...
2499  * memcpy(myval1, val1ptr, len1);
2500  * memcpy(myval2, val2ptr, len2);
2501  * ...
2502  * return;
2503  *
2504  * If you wish to retain the values after return from the DNSServiceResolve()
2505  * callback, then you need to copy the data to your own storage using memcpy()
2506  * or similar, as shown in the example above.
2507  *
2508  * If for some reason you need to parse a TXT record you built yourself
2509  * using the TXT record construction functions above, then you can do
2510  * that using TXTRecordGetLength and TXTRecordGetBytesPtr calls:
2511  * TXTRecordGetValue(TXTRecordGetLength(x), TXTRecordGetBytesPtr(x), key, &len);
2512  *
2513  * Most applications only fetch keys they know about from a TXT record and
2514  * ignore the rest.
2515  * However, some debugging tools wish to fetch and display all keys.
2516  * To do that, use the TXTRecordGetCount() and TXTRecordGetItemAtIndex() calls.
2517  */
2518 
2519 /* TXTRecordContainsKey()
2520  *
2521  * Allows you to determine if a given TXT Record contains a specified key.
2522  *
2523  * txtLen:          The size of the received TXT Record.
2524  *
2525  * txtRecord:       Pointer to the received TXT Record bytes.
2526  *
2527  * key:             A null-terminated ASCII string containing the key name.
2528  *
2529  * return value:    Returns 1 if the TXT Record contains the specified key.
2530  *                  Otherwise, it returns 0.
2531  */
2532 
2533 DNSSD_EXPORT
2534 int DNSSD_API TXTRecordContainsKey
2535 (
2536     uint16_t txtLen,
2537     const void       *txtRecord,
2538     const char       *key
2539 );
2540 
2541 
2542 /* TXTRecordGetValuePtr()
2543  *
2544  * Allows you to retrieve the value for a given key from a TXT Record.
2545  *
2546  * txtLen:          The size of the received TXT Record
2547  *
2548  * txtRecord:       Pointer to the received TXT Record bytes.
2549  *
2550  * key:             A null-terminated ASCII string containing the key name.
2551  *
2552  * valueLen:        On output, will be set to the size of the "value" data.
2553  *
2554  * return value:    Returns NULL if the key does not exist in this TXT record,
2555  *                  or exists with no value (to differentiate between
2556  *                  these two cases use TXTRecordContainsKey()).
2557  *                  Returns pointer to location within TXT Record bytes
2558  *                  if the key exists with empty or non-empty value.
2559  *                  For empty value, valueLen will be zero.
2560  *                  For non-empty value, valueLen will be length of value data.
2561  */
2562 
2563 DNSSD_EXPORT
2564 const void * DNSSD_API TXTRecordGetValuePtr
2565 (
2566     uint16_t txtLen,
2567     const void       *txtRecord,
2568     const char       *key,
2569     uint8_t          *valueLen
2570 );
2571 
2572 
2573 /* TXTRecordGetCount()
2574  *
2575  * Returns the number of keys stored in the TXT Record. The count
2576  * can be used with TXTRecordGetItemAtIndex() to iterate through the keys.
2577  *
2578  * txtLen:          The size of the received TXT Record.
2579  *
2580  * txtRecord:       Pointer to the received TXT Record bytes.
2581  *
2582  * return value:    Returns the total number of keys in the TXT Record.
2583  *
2584  */
2585 
2586 DNSSD_EXPORT
2587 uint16_t DNSSD_API TXTRecordGetCount
2588 (
2589     uint16_t txtLen,
2590     const void       *txtRecord
2591 );
2592 
2593 
2594 /* TXTRecordGetItemAtIndex()
2595  *
2596  * Allows you to retrieve a key name and value pointer, given an index into
2597  * a TXT Record. Legal index values range from zero to TXTRecordGetCount()-1.
2598  * It's also possible to iterate through keys in a TXT record by simply
2599  * calling TXTRecordGetItemAtIndex() repeatedly, beginning with index zero
2600  * and increasing until TXTRecordGetItemAtIndex() returns kDNSServiceErr_Invalid.
2601  *
2602  * On return:
2603  * For keys with no value, *value is set to NULL and *valueLen is zero.
2604  * For keys with empty value, *value is non-NULL and *valueLen is zero.
2605  * For keys with non-empty value, *value is non-NULL and *valueLen is non-zero.
2606  *
2607  * txtLen:          The size of the received TXT Record.
2608  *
2609  * txtRecord:       Pointer to the received TXT Record bytes.
2610  *
2611  * itemIndex:       An index into the TXT Record.
2612  *
2613  * keyBufLen:       The size of the string buffer being supplied.
2614  *
2615  * key:             A string buffer used to store the key name.
2616  *                  On return, the buffer contains a null-terminated C string
2617  *                  giving the key name. DNS-SD TXT keys are usually
2618  *                  9 characters or fewer. To hold the maximum possible
2619  *                  key name, the buffer should be 256 bytes long.
2620  *
2621  * valueLen:        On output, will be set to the size of the "value" data.
2622  *
2623  * value:           On output, *value is set to point to location within TXT
2624  *                  Record bytes that holds the value data.
2625  *
2626  * return value:    Returns kDNSServiceErr_NoError on success.
2627  *                  Returns kDNSServiceErr_NoMemory if keyBufLen is too short.
2628  *                  Returns kDNSServiceErr_Invalid if index is greater than
2629  *                  TXTRecordGetCount()-1.
2630  */
2631 
2632 DNSSD_EXPORT
2633 DNSServiceErrorType DNSSD_API TXTRecordGetItemAtIndex
2634 (
2635     uint16_t txtLen,
2636     const void       *txtRecord,
2637     uint16_t itemIndex,
2638     uint16_t keyBufLen,
2639     char             *key,
2640     uint8_t          *valueLen,
2641     const void       **value
2642 );
2643 
2644 #if _DNS_SD_LIBDISPATCH
2645 /*
2646  * DNSServiceSetDispatchQueue
2647  *
2648  * Allows you to schedule a DNSServiceRef on a serial dispatch queue for receiving asynchronous
2649  * callbacks.  It's the clients responsibility to ensure that the provided dispatch queue is running.
2650  *
2651  * A typical application that uses CFRunLoopRun or dispatch_main on its main thread will
2652  * usually schedule DNSServiceRefs on its main queue (which is always a serial queue)
2653  * using "DNSServiceSetDispatchQueue(sdref, dispatch_get_main_queue());"
2654  *
2655  * If there is any error during the processing of events, the application callback will
2656  * be called with an error code. For shared connections, each subordinate DNSServiceRef
2657  * will get its own error callback. Currently these error callbacks only happen
2658  * if the daemon is manually terminated or crashes, and the error
2659  * code in this case is kDNSServiceErr_ServiceNotRunning. The application must call
2660  * DNSServiceRefDeallocate to free the DNSServiceRef when it gets such an error code.
2661  * These error callbacks are rare and should not normally happen on customer machines,
2662  * but application code should be written defensively to handle such error callbacks
2663  * gracefully if they occur.
2664  *
2665  * After using DNSServiceSetDispatchQueue on a DNSServiceRef, calling DNSServiceProcessResult
2666  * on the same DNSServiceRef will result in undefined behavior and should be avoided.
2667  *
2668  * Once the application successfully schedules a DNSServiceRef on a serial dispatch queue using
2669  * DNSServiceSetDispatchQueue, it cannot remove the DNSServiceRef from the dispatch queue, or use
2670  * DNSServiceSetDispatchQueue a second time to schedule the DNSServiceRef onto a different serial dispatch
2671  * queue. Once scheduled onto a dispatch queue a DNSServiceRef will deliver events to that queue until
2672  * the application no longer requires that operation and terminates it using DNSServiceRefDeallocate.
2673  *
2674  * service:         DNSServiceRef that was allocated and returned to the application, when the
2675  *                  application calls one of the DNSService API.
2676  *
2677  * queue:           dispatch queue where the application callback will be scheduled
2678  *
2679  * return value:    Returns kDNSServiceErr_NoError on success.
2680  *                  Returns kDNSServiceErr_NoMemory if it cannot create a dispatch source
2681  *                  Returns kDNSServiceErr_BadParam if the service param is invalid or the
2682  *                  queue param is invalid
2683  */
2684 
2685 DNSSD_EXPORT
2686 DNSServiceErrorType DNSSD_API DNSServiceSetDispatchQueue
2687 (
2688     DNSServiceRef service,
2689     dispatch_queue_t queue
2690 );
2691 #endif //_DNS_SD_LIBDISPATCH
2692 
2693 #if !defined(_WIN32)
2694 typedef void (DNSSD_API *DNSServiceSleepKeepaliveReply)
2695 (
2696     DNSServiceRef sdRef,
2697     DNSServiceErrorType errorCode,
2698     void                                *context
2699 );
2700 DNSSD_EXPORT
2701 DNSServiceErrorType DNSSD_API DNSServiceSleepKeepalive
2702 (
2703     DNSServiceRef                       *sdRef,
2704     DNSServiceFlags flags,
2705     int fd,
2706     unsigned int timeout,
2707     DNSServiceSleepKeepaliveReply callBack,
2708     void                                *context
2709 );
2710 #endif
2711 
2712 /* Some C compiler cleverness. We can make the compiler check certain things for us,
2713  * and report errors at compile-time if anything is wrong. The usual way to do this would
2714  * be to use a run-time "if" statement or the conventional run-time "assert" mechanism, but
2715  * then you don't find out what's wrong until you run the software. This way, if the assertion
2716  * condition is false, the array size is negative, and the complier complains immediately.
2717  */
2718 
2719 struct CompileTimeAssertionChecks_DNS_SD
2720 {
2721     char assert0[(sizeof(union _TXTRecordRef_t) == 16) ? 1 : -1];
2722 };
2723 
2724 #ifdef  __cplusplus
2725 }
2726 #endif
2727 
2728 #endif  /* _DNS_SD_H */
2729