7 This file is part of avahi.
9 avahi is free software; you can redistribute it and/or modify it
10 under the terms of the GNU Lesser General Public License as
11 published by the Free Software Foundation; either version 2.1 of the
12 License, or (at your option) any later version.
14 avahi is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
17 Public License for more details.
19 You should have received a copy of the GNU Lesser General Public
20 License along with avahi; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
25 /** \file defs.h Some common definitions */
27 #include <avahi-common/cdecl.h>
31 * \section choose_api Choosing an API
33 * Avahi provides three programming APIs for integration of
34 * mDNS/DNS-SD features into your C progams:
36 * \li <b>avahi-core</b>: an API for embedding a complete mDNS/DNS-SD stack
37 * into your software. This is intended for developers of embedded
38 * ampliances only. We dissuade from using this API in normal desktop
39 * applications since it is not a good idea to run multiple mDNS
40 * stacks simultaneously on the same host.
41 * \li <b>the D-Bus API</b>: an extensive D-Bus interface for browsing and
42 * registering mDNS/DNS-SD services using avahi-daemon. We recommend
43 * to use this API for software written in any language but
45 * \li <b>avahi-client</b>: a simplifying C wrapper around the D-Bus API. We
46 * recommend to use this API in C or C++ progams. The D-Bus internals
47 * are hidden completely.
49 * All three APIs are very similar, however avahi-core is the most powerful.
51 * In addition to the three APIs described above Avahi supports two
52 * compatibility libraries:
54 * \li <b>avahi-compat-libdns_sd</b>: the original Bonjour API as documented
55 * in the header file "dns_sd.h" by Apple Computer, Inc.
57 * \li <b>avahi-compat-howl</b>: the HOWL API as released with HOWL 0.9.8 by
60 * Please note that these compatibility layers are incomplete and
61 * generally a waste of resources. We strongly encourage everyone to
62 * use our native APIs for newly written programs and to port older
63 * programs to avahi-client!
65 * The native APIs (avahi-client and avahi-core) can be integrated
66 * into external event loops. We provide adapters for the following
67 * event loop implementations:
69 * \li <b>avahi-glib</b>: The GLIB main loop as used by GTk+/GNOME
71 * \li <b>avahi-qt</b>: The Qt main loop as used by Qt/KDE
73 * Finally, we provide a high-level Gtk+ GUI dialog called
74 * <b>avahi-ui</b> for user-friendly browsing for services.
76 * The doxygen-generated API documentation covers avahi-client
77 * (including its auxiliary APIs), the event loop adapters and
78 * avahi-ui. For the other APIs please consult the original
79 * documentation (for the compatibility APIs) or the header files.
81 * Please note that the doxygen-generated API documentation of the
82 * native Avahi API is not complete. A few definitions that are part
83 * of the Avahi API have been removed from this documentation, either
84 * because they are only relevant in a very few low-level applications
85 * or because they are considered obsolete. Please consult the C header
86 * files for all definitions that are part of the Avahi API. Please
87 * note that these hidden definitions are considered part of the Avahi
88 * API and will stay available in the API in the future.
90 * \section error_reporting Error Reporting
92 * Some notes on the Avahi error handling:
94 * - Error codes are negative integers and defined as AVAHI_ERR_xx
95 * - If a function returns some kind of non-negative integer value on
96 * success, a failure is indicated by returning the error code
98 * - If a function returns a pointer of some kind on success, a
99 * failure is indicated by returning NULL
100 * - The last error number may be retrieved by calling
101 * avahi_client_errno()
102 * - Just like the libc errno variable the Avahi errno is NOT reset to
103 * AVAHI_OK if a function call succeeds.
104 * - You may convert a numeric error code into a human readable string
105 * using avahi_strerror()
106 * - The constructor function avahi_client_new() returns the error
107 * code in a call-by-reference argument
109 * \section event_loop Event Loop Abstraction
111 * Avahi uses a simple event loop abstraction laye. A table AvahiPoll
112 * which contains function pointers for user defined timeout and I/O
113 * condition event source implementations needs to be passed to
114 * avahi_client_new(). An adapter for this abstraction layer is
115 * available for the GLib main loop in the object AvahiGLibPoll. A
116 * simple stand-alone implementation is available under the name
117 * AvahiSimplePoll. An adpater for the Qt main loop is available from
118 * avahi_qt_poll_get().
120 * \section good_publish How to Register Services
122 * - Subscribe to server state changes. Pass a callback function
123 * pointer to avahi_client_new(). It will be called
124 * whenever the server state changes.
125 * - Only register your services when the server is in state
126 * AVAHI_SERVER_RUNNING. If you register your services in other server
127 * states they might not be accessible since the local host name might not necessarily
129 * - Remove your services when the server enters
130 * AVAHI_SERVER_COLLISION or AVAHI_SERVER_REGISTERING state. Your
131 * services may no be reachable anymore since the local host name is
132 * no longer established or is currently in the process of being
134 * - When registering services, use the following algorithm:
135 * - Create a new entry group (i.e. avahi_entry_group_new())
136 * - Add your service(s)/additional RRs/subtypes (e.g. avahi_entry_group_add_service())
137 * - Commit the entry group (i.e. avahi_entry_group_commit())
138 * - Subscribe to entry group state changes.
139 * - If the entry group enters AVAHI_ENTRY_GROUP_COLLISION state the
140 * services of the entry group are automatically removed from the
141 * server. You may immediately add your services back to the entry
142 * group (but with new names, perhaps using
143 * avahi_alternative_service_name()) and commit again. Please do not
144 * free the entry group and create a new one. This would inhibit some
145 * traffic limiting algorithms in mDNS.
146 * - When you need to modify your services (i.e. change the TXT data
147 * or the port number), use the AVAHI_PUBLISH_UPDATE flag. Please do
148 * not free the entry group and create a new one. This would inhibit
149 * some traffic limiting algorithms in mDNS. When changing just the
150 * TXT data avahi_entry_group_update_txt() is a shortcut for
151 * AVAHI_PUBLISH_UPDATE. Please note that you cannot use
152 * AVAHI_PUBLISH_UPDATE when changing the service name! Renaming a
153 * DNS-SD service is identical to deleting and creating a new one, and
154 * that's exactly what you should do in that case. First call
155 * avahi_entry_group_reset() to remove it and than readd it normally.
157 * \section good_browse How to Browse for Services
159 * - For normal applications you need to call avahi_service_browser_new()
160 * for the service type you want to browse for. Use
161 * avahi_service_resolver_new() to acquire service data for a service
163 * - You can use avahi_domain_browser_new() to get a list of announced
164 * browsing domains. Please note that not all domains whith services
165 * on the LAN are mandatorily announced.
166 * - There is no need to subscribe to server state changes.
168 * \section daemon_dies How to Write a Client That Can Deal with Daemon Restarts
170 * With Avahi it is possible to write client applications that can
171 * deal with Avahi daemon restarts. To accomplish that make sure to
172 * pass AVAHI_CLIENT_NO_FAIL to avahi_client_new()'s flags
173 * parameter. That way avahi_client_new() will succeed even when the
174 * daemon is not running. In that case the object will enter
175 * AVAHI_CLIENT_CONNECTING state. As soon as the daemon becomes
176 * available the object will enter one of the AVAHI_CLIENT_S_xxx
177 * states. Make sure to not create browsers or entry groups before the
178 * client object has entered one of those states. As usual you will be
179 * informed about state changes with the callback function supplied to
180 * avahi_client_new(). If the client is forced to disconnect from the
181 * server it will enter AVAHI_CLIENT_FAILURE state with
182 * avahi_client_errno() == AVAHI_ERR_DISCONNECTED. Free the
183 * AvahiClient object in that case and reconnect to the server anew -
184 * again with passing AVAHI_CLIENT_NO_FAIL to avahi_client_new().
186 * We encourage to implement this in all software where service
187 * discovery is not an integral part of application. e.g. use it in
188 * all kinds of background daemons, but not in software like iChat
189 * compatible IM software.
191 * For now AVAHI_CLIENT_NO_FAIL cannot deal with D-Bus daemon restarts.
193 * \section domains How to Deal Properly with Browsing Domains
195 * Due to the introduction of wide-area DNS-SD the correct handling of
196 * domains becomes more important for Avahi enabled applications. All
197 * applications that offer the user a list of services discovered with
198 * Avahi should offer some kind of editable drop down box where the
199 * user can either enter his own domain or select one of those offered
200 * by AvahiDomainBrowser. The default domain to browse should be the
201 * one returned by avahi_client_get_domain_name(). The list of domains
202 * returned by AvahiDomainBrowser is assembled by the browsing domains
203 * configured in the daemon's configuration file, the domains
204 * announced inside the default domain, the domains set with the
205 * environment variable $AVAHI_BROWSE_DOMAINS (colon-seperated) on the
206 * client side and the domains set in the XDG configuration file
207 * ~/.config/avahi/browse-domains on the client side (seperated by
208 * newlines). File managers offering some kind of "Network
209 * Neighborhood" folder should show the entries of the default domain
210 * right inside that and offer subfolders for the browsing domains
211 * returned by AvahiDomainBrowser.
216 /** @{ \name States */
218 /** States of a server object */
220 AVAHI_SERVER_INVALID, /**< Invalid state (initial) */
221 AVAHI_SERVER_REGISTERING, /**< Host RRs are being registered */
222 AVAHI_SERVER_RUNNING, /**< All host RRs have been established */
223 AVAHI_SERVER_COLLISION, /**< There is a collision with a host RR. All host RRs have been withdrawn, the user should set a new host name via avahi_server_set_host_name() */
224 AVAHI_SERVER_FAILURE /**< Some fatal failure happened, the server is unable to proceed */
227 /** States of an entry group object */
229 AVAHI_ENTRY_GROUP_UNCOMMITED, /**< The group has not yet been commited, the user must still call avahi_entry_group_commit() */
230 AVAHI_ENTRY_GROUP_REGISTERING, /**< The entries of the group are currently being registered */
231 AVAHI_ENTRY_GROUP_ESTABLISHED, /**< The entries have successfully been established */
232 AVAHI_ENTRY_GROUP_COLLISION, /**< A name collision for one of the entries in the group has been detected, the entries have been withdrawn */
233 AVAHI_ENTRY_GROUP_FAILURE /**< Some kind of failure happened, the entries have been withdrawn */
234 } AvahiEntryGroupState;
238 /** @{ \name Flags */
240 /** Some flags for publishing functions */
242 AVAHI_PUBLISH_UNIQUE = 1, /**< For raw records: The RRset is intended to be unique */
243 AVAHI_PUBLISH_NO_PROBE = 2, /**< For raw records: Though the RRset is intended to be unique no probes shall be sent */
244 AVAHI_PUBLISH_NO_ANNOUNCE = 4, /**< For raw records: Do not announce this RR to other hosts */
245 AVAHI_PUBLISH_ALLOW_MULTIPLE = 8, /**< For raw records: Allow multiple local records of this type, even if they are intended to be unique */
246 /** \cond fulldocs */
247 AVAHI_PUBLISH_NO_REVERSE = 16, /**< For address records: don't create a reverse (PTR) entry */
248 AVAHI_PUBLISH_NO_COOKIE = 32, /**< For service records: do not implicitly add the local service cookie to TXT data */
250 AVAHI_PUBLISH_UPDATE = 64, /**< Update existing records instead of adding new ones */
251 /** \cond fulldocs */
252 AVAHI_PUBLISH_USE_WIDE_AREA = 128, /**< Register the record using wide area DNS (i.e. unicast DNS update) */
253 AVAHI_PUBLISH_USE_MULTICAST = 256 /**< Register the record using multicast DNS */
257 /** Some flags for lookup functions */
259 /** \cond fulldocs */
260 AVAHI_LOOKUP_USE_WIDE_AREA = 1, /**< Force lookup via wide area DNS */
261 AVAHI_LOOKUP_USE_MULTICAST = 2, /**< Force lookup via multicast DNS */
263 AVAHI_LOOKUP_NO_TXT = 4, /**< When doing service resolving, don't lookup TXT record */
264 AVAHI_LOOKUP_NO_ADDRESS = 8 /**< When doing service resolving, don't lookup A/AAAA record */
267 /** Some flags for lookup callback functions */
269 AVAHI_LOOKUP_RESULT_CACHED = 1, /**< This response originates from the cache */
270 AVAHI_LOOKUP_RESULT_WIDE_AREA = 2, /**< This response originates from wide area DNS */
271 AVAHI_LOOKUP_RESULT_MULTICAST = 4, /**< This response originates from multicast DNS */
272 AVAHI_LOOKUP_RESULT_LOCAL = 8, /**< This record/service resides on and was announced by the local host. Only available in service and record browsers and only on AVAHI_BROWSER_NEW. */
273 AVAHI_LOOKUP_RESULT_OUR_OWN = 16, /**< This service belongs to the same local client as the browser object. Only available in avahi-client, and only for service browsers and only on AVAHI_BROWSER_NEW. */
274 AVAHI_LOOKUP_RESULT_STATIC = 32 /**< The returned data has been defined statically by some configuration option */
275 } AvahiLookupResultFlags;
279 /** @{ \name Events */
281 /** Type of callback event when browsing */
283 AVAHI_BROWSER_NEW, /**< The object is new on the network */
284 AVAHI_BROWSER_REMOVE, /**< The object has been removed from the network */
285 AVAHI_BROWSER_CACHE_EXHAUSTED, /**< One-time event, to notify the user that all entries from the caches have been send */
286 AVAHI_BROWSER_ALL_FOR_NOW, /**< One-time event, to notify the user that more records will probably not show up in the near future, i.e. all cache entries have been read and all static servers been queried */
287 AVAHI_BROWSER_FAILURE /**< Browsing failed due to some reason which can be retrieved using avahi_server_errno()/avahi_client_errno() */
290 /** Type of callback event when resolving */
292 AVAHI_RESOLVER_FOUND, /**< RR found, resolving successful */
293 AVAHI_RESOLVER_FAILURE /**< Resolving failed due to some reason which can be retrieved using avahi_server_errno()/avahi_client_errno() */
294 } AvahiResolverEvent;
298 /** @{ \name Other definitions */
300 /** The type of domain to browse for */
302 AVAHI_DOMAIN_BROWSER_BROWSE, /**< Browse for a list of available browsing domains */
303 AVAHI_DOMAIN_BROWSER_BROWSE_DEFAULT, /**< Browse for the default browsing domain */
304 AVAHI_DOMAIN_BROWSER_REGISTER, /**< Browse for a list of available registering domains */
305 AVAHI_DOMAIN_BROWSER_REGISTER_DEFAULT, /**< Browse for the default registering domain */
306 AVAHI_DOMAIN_BROWSER_BROWSE_LEGACY, /**< Legacy browse domain - see DNS-SD spec for more information */
307 AVAHI_DOMAIN_BROWSER_MAX
308 } AvahiDomainBrowserType;
312 /** \cond fulldocs */
313 /** For every service a special TXT item is implicitly added, which
314 * contains a random cookie which is private to the local daemon. This
315 * can be used by clients to determine if two services on two
316 * different subnets are effectively the same. */
317 #define AVAHI_SERVICE_COOKIE "org.freedesktop.Avahi.cookie"
319 /** In invalid cookie as special value */
320 #define AVAHI_SERVICE_COOKIE_INVALID (0)
321 /** \endcond fulldocs */
323 /** @{ \name DNS RR definitions */
325 /** DNS record types, see RFC 1035 */
327 AVAHI_DNS_TYPE_A = 0x01,
328 AVAHI_DNS_TYPE_NS = 0x02,
329 AVAHI_DNS_TYPE_CNAME = 0x05,
330 AVAHI_DNS_TYPE_SOA = 0x06,
331 AVAHI_DNS_TYPE_PTR = 0x0C,
332 AVAHI_DNS_TYPE_HINFO = 0x0D,
333 AVAHI_DNS_TYPE_MX = 0x0F,
334 AVAHI_DNS_TYPE_TXT = 0x10,
335 AVAHI_DNS_TYPE_AAAA = 0x1C,
336 AVAHI_DNS_TYPE_SRV = 0x21,
339 /** DNS record classes, see RFC 1035 */
341 AVAHI_DNS_CLASS_IN = 0x01, /**< Probably the only class we will ever use */
346 /** The default TTL for RRs which contain a host name of some kind. */
347 #define AVAHI_DEFAULT_TTL_HOST_NAME (120)
349 /** The default TTL for all other records. */
350 #define AVAHI_DEFAULT_TTL (75*60)