1 /***
2   This file is part of avahi.
3 
4   avahi is free software; you can redistribute it and/or modify it
5   under the terms of the GNU Lesser General Public License as
6   published by the Free Software Foundation; either version 2.1 of the
7   License, or (at your option) any later version.
8 
9   avahi is distributed in the hope that it will be useful, but WITHOUT
10   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11   or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
12   Public License for more details.
13 
14   You should have received a copy of the GNU Lesser General Public
15   License along with avahi; if not, write to the Free Software
16   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
17   USA.
18 ***/
19 
20 #ifdef HAVE_CONFIG_H
21 #include <config.h>
22 #endif
23 
24 #include <time.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <assert.h>
28 
29 #include <avahi-client/client.h>
30 #include <avahi-client/publish.h>
31 
32 #include <avahi-common/alternative.h>
33 #include <avahi-common/simple-watch.h>
34 #include "avahi-common/avahi-malloc.h"
35 #include <avahi-common/error.h>
36 #include <avahi-common/timeval.h>
37 
38 static AvahiEntryGroup *group = NULL;
39 static AvahiSimplePoll *simple_poll = NULL;
40 static char *name = NULL;
41 
42 static void create_services(AvahiClient *c);
43 
entry_group_callback(AvahiEntryGroup * g,AvahiEntryGroupState state,AVAHI_GCC_UNUSED void * userdata)44 static void entry_group_callback(AvahiEntryGroup *g, AvahiEntryGroupState state, AVAHI_GCC_UNUSED void *userdata) {
45     assert(g == group || group == NULL);
46     group = g;
47 
48     /* Called whenever the entry group state changes */
49 
50     switch (state) {
51         case AVAHI_ENTRY_GROUP_ESTABLISHED :
52             /* The entry group has been established successfully */
53             fprintf(stderr, "Service '%s' successfully established.\n", name);
54             break;
55 
56         case AVAHI_ENTRY_GROUP_COLLISION : {
57             char *n;
58 
59             /* A service name collision with a remote service
60              * happened. Let's pick a new name */
61             n = avahi_alternative_service_name(name);
62             avahi_free(name);
63             name = n;
64 
65             fprintf(stderr, "Service name collision, renaming service to '%s'\n", name);
66 
67             /* And recreate the services */
68             create_services(avahi_entry_group_get_client(g));
69             break;
70         }
71 
72         case AVAHI_ENTRY_GROUP_FAILURE :
73 
74             fprintf(stderr, "Entry group failure: %s\n", avahi_strerror(avahi_client_errno(avahi_entry_group_get_client(g))));
75 
76             /* Some kind of failure happened while we were registering our services */
77             avahi_simple_poll_quit(simple_poll);
78             break;
79 
80         case AVAHI_ENTRY_GROUP_UNCOMMITED:
81         case AVAHI_ENTRY_GROUP_REGISTERING:
82             ;
83     }
84 }
85 
create_services(AvahiClient * c)86 static void create_services(AvahiClient *c) {
87     char *n, r[128];
88     int ret;
89     assert(c);
90 
91     /* If this is the first time we're called, let's create a new
92      * entry group if necessary */
93 
94     if (!group)
95         if (!(group = avahi_entry_group_new(c, entry_group_callback, NULL))) {
96             fprintf(stderr, "avahi_entry_group_new() failed: %s\n", avahi_strerror(avahi_client_errno(c)));
97             goto fail;
98         }
99 
100     /* If the group is empty (either because it was just created, or
101      * because it was reset previously, add our entries.  */
102 
103     if (avahi_entry_group_is_empty(group)) {
104         fprintf(stderr, "Adding service '%s'\n", name);
105 
106         /* Create some random TXT data */
107         snprintf(r, sizeof(r), "random=%i", rand());
108 
109         /* We will now add two services and one subtype to the entry
110          * group. The two services have the same name, but differ in
111          * the service type (IPP vs. BSD LPR). Only services with the
112          * same name should be put in the same entry group. */
113 
114         /* Add the service for IPP */
115         if ((ret = avahi_entry_group_add_service(group, AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC, 0, name, "_ipp._tcp", NULL, NULL, 651, "test=blah", r, NULL)) < 0) {
116 
117             if (ret == AVAHI_ERR_COLLISION)
118                 goto collision;
119 
120             fprintf(stderr, "Failed to add _ipp._tcp service: %s\n", avahi_strerror(ret));
121             goto fail;
122         }
123 
124         /* Add the same service for BSD LPR */
125         if ((ret = avahi_entry_group_add_service(group, AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC, 0, name, "_printer._tcp", NULL, NULL, 515, NULL)) < 0) {
126 
127             if (ret == AVAHI_ERR_COLLISION)
128                 goto collision;
129 
130             fprintf(stderr, "Failed to add _printer._tcp service: %s\n", avahi_strerror(ret));
131             goto fail;
132         }
133 
134         /* Add an additional (hypothetic) subtype */
135         if ((ret = avahi_entry_group_add_service_subtype(group, AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC, 0, name, "_printer._tcp", NULL, "_magic._sub._printer._tcp") < 0)) {
136             fprintf(stderr, "Failed to add subtype _magic._sub._printer._tcp: %s\n", avahi_strerror(ret));
137             goto fail;
138         }
139 
140         /* Tell the server to register the service */
141         if ((ret = avahi_entry_group_commit(group)) < 0) {
142             fprintf(stderr, "Failed to commit entry group: %s\n", avahi_strerror(ret));
143             goto fail;
144         }
145     }
146 
147     return;
148 
149 collision:
150 
151     /* A service name collision with a local service happened. Let's
152      * pick a new name */
153     n = avahi_alternative_service_name(name);
154     avahi_free(name);
155     name = n;
156 
157     fprintf(stderr, "Service name collision, renaming service to '%s'\n", name);
158 
159     avahi_entry_group_reset(group);
160 
161     create_services(c);
162     return;
163 
164 fail:
165     avahi_simple_poll_quit(simple_poll);
166 }
167 
client_callback(AvahiClient * c,AvahiClientState state,AVAHI_GCC_UNUSED void * userdata)168 static void client_callback(AvahiClient *c, AvahiClientState state, AVAHI_GCC_UNUSED void * userdata) {
169     assert(c);
170 
171     /* Called whenever the client or server state changes */
172 
173     switch (state) {
174         case AVAHI_CLIENT_S_RUNNING:
175 
176             /* The server has startup successfully and registered its host
177              * name on the network, so it's time to create our services */
178             create_services(c);
179             break;
180 
181         case AVAHI_CLIENT_FAILURE:
182 
183             fprintf(stderr, "Client failure: %s\n", avahi_strerror(avahi_client_errno(c)));
184             avahi_simple_poll_quit(simple_poll);
185 
186             break;
187 
188         case AVAHI_CLIENT_S_COLLISION:
189 
190             /* Let's drop our registered services. When the server is back
191              * in AVAHI_SERVER_RUNNING state we will register them
192              * again with the new host name. */
193 
194         case AVAHI_CLIENT_S_REGISTERING:
195 
196             /* The server records are now being established. This
197              * might be caused by a host name change. We need to wait
198              * for our own records to register until the host name is
199              * properly esatblished. */
200 
201             if (group)
202                 avahi_entry_group_reset(group);
203 
204             break;
205 
206         case AVAHI_CLIENT_CONNECTING:
207             ;
208     }
209 }
210 
modify_callback(AVAHI_GCC_UNUSED AvahiTimeout * e,void * userdata)211 static void modify_callback(AVAHI_GCC_UNUSED AvahiTimeout *e, void *userdata) {
212     AvahiClient *client = userdata;
213 
214     fprintf(stderr, "Doing some weird modification\n");
215 
216     avahi_free(name);
217     name = avahi_strdup("Modified MegaPrinter");
218 
219     /* If the server is currently running, we need to remove our
220      * service and create it anew */
221     if (avahi_client_get_state(client) == AVAHI_CLIENT_S_RUNNING) {
222 
223         /* Remove the old services */
224         if (group)
225             avahi_entry_group_reset(group);
226 
227         /* And create them again with the new name */
228         create_services(client);
229     }
230 }
231 
main(AVAHI_GCC_UNUSED int argc,AVAHI_GCC_UNUSED char * argv[])232 int main(AVAHI_GCC_UNUSED int argc, AVAHI_GCC_UNUSED char*argv[]) {
233     AvahiClient *client = NULL;
234     int error;
235     int ret = 1;
236     struct timeval tv;
237 
238     /* Allocate main loop object */
239     if (!(simple_poll = avahi_simple_poll_new())) {
240         fprintf(stderr, "Failed to create simple poll object.\n");
241         goto fail;
242     }
243 
244     name = avahi_strdup("MegaPrinter");
245 
246     /* Allocate a new client */
247     client = avahi_client_new(avahi_simple_poll_get(simple_poll), 0, client_callback, NULL, &error);
248 
249     /* Check wether creating the client object succeeded */
250     if (!client) {
251         fprintf(stderr, "Failed to create client: %s\n", avahi_strerror(error));
252         goto fail;
253     }
254 
255     /* After 10s do some weird modification to the service */
256     avahi_simple_poll_get(simple_poll)->timeout_new(
257         avahi_simple_poll_get(simple_poll),
258         avahi_elapse_time(&tv, 1000*10, 0),
259         modify_callback,
260         client);
261 
262     /* Run the main loop */
263     avahi_simple_poll_loop(simple_poll);
264 
265     ret = 0;
266 
267 fail:
268 
269     /* Cleanup things */
270 
271     if (client)
272         avahi_client_free(client);
273 
274     if (simple_poll)
275         avahi_simple_poll_free(simple_poll);
276 
277     avahi_free(name);
278 
279     return ret;
280 }
281