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Sources/mdnsd/service.c

  1 /*
  2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU Lesser General Public License version 2.1
  6  * as published by the Free Software Foundation
  7  *
  8  * This program is distributed in the hope that it will be useful,
  9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11  * GNU General Public License for more details.
 12  */
 13 
 14 #include <sys/types.h>
 15 #include <arpa/nameser.h>
 16 #include <sys/socket.h>
 17 
 18 #include <resolv.h>
 19 #include <glob.h>
 20 #include <inttypes.h>
 21 #include <stdio.h>
 22 #include <time.h>
 23 
 24 #include <libubus.h>
 25 #include <libubox/uloop.h>
 26 #include <libubox/blobmsg_json.h>
 27 
 28 #include "ubus.h"
 29 #include "dns.h"
 30 #include "service.h"
 31 #include "util.h"
 32 #include "interface.h"
 33 #include "announce.h"
 34 
 35 enum {
 36         SERVICE_INSTANCE,
 37         SERVICE_SERVICE,
 38         SERVICE_PORT,
 39         SERVICE_TXT,
 40         SERVICE_HOSTNAME,
 41         __SERVICE_MAX,
 42 };
 43 
 44 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
 45         [SERVICE_INSTANCE] = { .name = "instance", .type = BLOBMSG_TYPE_STRING },
 46         [SERVICE_SERVICE] = { .name = "service", .type = BLOBMSG_TYPE_STRING },
 47         [SERVICE_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
 48         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
 49         [SERVICE_HOSTNAME] = { .name = "hostname", .type = BLOBMSG_TYPE_STRING },
 50 };
 51 
 52 static void
 53 hostname_update(struct vlist_tree *tree, struct vlist_node *node_new,
 54                 struct vlist_node *node_old);
 55 
 56 static struct blob_buf b;
 57 VLIST_TREE(announced_services, avl_strcmp, service_update, false, false);
 58 VLIST_TREE(hostnames, avl_strcmp, hostname_update, false, false);
 59 static int service_init_announce;
 60 
 61 /**
 62  * service_instance_name - construct Service Instance Name as in RFC 6763
 63  *
 64  * RFC 6763 specifies Service Instance Names in the following way:
 65  *
 66  * Service Instance Name = <Instance> . <Service> . <Domain>
 67  *
 68  * @s: service to generate service instance name for
 69  */
 70 static const char *
 71 service_instance_name(struct service *s)
 72 {
 73         static char buffer[256];
 74 
 75         snprintf(buffer, sizeof(buffer), "%s.%s", s->instance, s->service);
 76 
 77         return buffer;
 78 }
 79 
 80 static void
 81 service_add_ptr(const char *name, const char *host, int ttl)
 82 {
 83         int len = dn_comp(host, mdns_buf, sizeof(mdns_buf), NULL, NULL);
 84 
 85         if (len < 1)
 86                 return;
 87 
 88         dns_packet_answer(name, TYPE_PTR, mdns_buf, len, ttl);
 89 }
 90 
 91 static void
 92 service_add_srv(const char *name, struct service *s, int ttl)
 93 {
 94         struct dns_srv_data *sd = (struct dns_srv_data *) mdns_buf;
 95         int len = sizeof(*sd);
 96 
 97         len += dn_comp(s->hostname, mdns_buf + len, sizeof(mdns_buf) - len, NULL, NULL);
 98         if (len <= sizeof(*sd))
 99                 return;
100 
101         sd->port = cpu_to_be16(s->port);
102         dns_packet_answer(name, TYPE_SRV, mdns_buf, len, ttl);
103 }
104 
105 #define TOUT_LOOKUP     60
106 
107 static time_t
108 service_timeout(struct service *s)
109 {
110         time_t t = monotonic_time();
111 
112         if (t - s->t <= TOUT_LOOKUP) {
113                 DBG(2, "t=%" PRId64 ", s->t=%" PRId64 ", t - s->t = %" PRId64 "\n", (int64_t)t, (int64_t)s->t, (int64_t)(t - s->t));
114                 return 0;
115         }
116 
117         return t;
118 }
119 
120 static void
121 service_reply_single(struct interface *iface, struct sockaddr *to, struct service *s, int ttl, int force)
122 {
123         const char *host = service_instance_name(s);
124         char *service = strstr(host, "._");
125         time_t t = service_timeout(s);
126 
127         if (!force && (!s->active || !service || !t))
128                 return;
129 
130         service++;
131 
132         s->t = t;
133 
134         dns_packet_init();
135         service_add_ptr(service, service_instance_name(s), ttl);
136         service_add_srv(host, s, ttl);
137         if (s->txt && s->txt_len)
138                 dns_packet_answer(host, TYPE_TXT, (uint8_t *) s->txt, s->txt_len, ttl);
139         dns_packet_send(iface, to, 0, 0);
140 }
141 
142 void
143 service_reply(struct interface *iface, struct sockaddr *to, const char *instance, const char *service_domain, int ttl, int force)
144 {
145         struct service *s;
146 
147         vlist_for_each_element(&announced_services, s, node) {
148                 if (instance && strcmp(s->instance, instance))
149                         continue;
150                 if (service_domain && strcmp(s->service, service_domain))
151                         continue;
152                 service_reply_single(iface, to, s, ttl, force);
153         }
154 }
155 
156 void
157 service_announce_services(struct interface *iface, struct sockaddr *to, int ttl)
158 {
159         struct service *s;
160         int count = 0;
161 
162         dns_packet_init();
163         vlist_for_each_element(&announced_services, s, node) {
164                 s->t = 0;
165                 if (ttl) {
166                         service_add_ptr(C_DNS_SD, s->service, ttl);
167                         count++;
168                 }
169         }
170         if (count)
171                 dns_packet_send(iface, to, 0, 0);
172 }
173 
174 void
175 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
176                struct vlist_node *node_old)
177 {
178         struct interface *iface;
179         struct service *s;
180 
181         if (!node_old) {
182                 s = container_of(node_new, struct service, node);
183                 if (service_init_announce)
184                         vlist_for_each_element(&interfaces, iface, node) {
185                                 s->t = 0;
186                                 service_reply_single(iface, NULL, s, announce_ttl, 1);
187                         }
188                 return;
189         }
190 
191         s = container_of(node_old, struct service, node);
192         if (!node_new && service_init_announce)
193                 vlist_for_each_element(&interfaces, iface, node)
194                         service_reply_single(iface, NULL, s, 0, 1);
195         free(s);
196 }
197 
198 static void
199 hostname_update(struct vlist_tree *tree, struct vlist_node *node_new,
200                 struct vlist_node *node_old)
201 {
202         struct interface *iface;
203         struct hostname *h;
204 
205         if (!node_old) {
206                 h = container_of(node_new, struct hostname, node);
207                 vlist_for_each_element(&interfaces, iface, node)
208                         dns_reply_a(iface, NULL, announce_ttl, h->hostname);
209                 return;
210         }
211 
212         h = container_of(node_old, struct hostname, node);
213         if (!node_new)
214                 vlist_for_each_element(&interfaces, iface, node)
215                         dns_reply_a(iface, NULL, 0, h->hostname);
216 
217         free(h);
218 }
219 
220 static void
221 service_load_hostname(struct blob_attr *b)
222 {
223         struct hostname *h;
224         char *hostname, *d_hostname;
225 
226         hostname = blobmsg_get_string(b);
227         h = calloc_a(sizeof(*h), &d_hostname, strlen(hostname) + 1);
228         if (!h)
229                 return;
230 
231         h->hostname = strcpy(d_hostname, hostname);
232 
233         vlist_add(&hostnames, &h->node, h->hostname);
234 }
235 
236 static void
237 service_load_blob(struct blob_attr *b)
238 {
239         struct blob_attr *txt, *_tb[__SERVICE_MAX];
240         struct service *s;
241         char *d_instance, *d_hostname, *d_service, *d_id;
242         uint8_t *d_txt;
243         int rem2;
244         int txt_len = 0;
245         unsigned int n;
246 
247         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
248                 _tb, blobmsg_data(b), blobmsg_data_len(b));
249 
250         if (_tb[SERVICE_HOSTNAME])
251                 service_load_hostname(_tb[SERVICE_HOSTNAME]);
252 
253         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_SERVICE])
254                 return;
255 
256         if (_tb[SERVICE_TXT])
257                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
258                         txt_len += 1 + strlen(blobmsg_get_string(txt));
259 
260         n = strlen(blobmsg_name(b));
261         s = calloc_a(sizeof(*s),
262                 &d_id, n + 1,
263                 &d_hostname, _tb[SERVICE_HOSTNAME] ? strlen(blobmsg_get_string(_tb[SERVICE_HOSTNAME])) + 1 : 0,
264                 &d_instance, _tb[SERVICE_INSTANCE] ? strlen(blobmsg_get_string(_tb[SERVICE_INSTANCE])) + 1 : 0,
265                 &d_service, strlen(blobmsg_get_string(_tb[SERVICE_SERVICE])) + 1,
266                 &d_txt, txt_len);
267         if (!s)
268                 return;
269 
270         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
271         s->id = strncpy(d_id, blobmsg_name(b), n);
272         if (_tb[SERVICE_HOSTNAME])
273                 s->hostname = strcpy(d_hostname, blobmsg_get_string(_tb[SERVICE_HOSTNAME]));
274         else
275                 s->hostname = mdns_hostname_local;
276         if (_tb[SERVICE_INSTANCE])
277                 s->instance = strcpy(d_instance, blobmsg_get_string(_tb[SERVICE_INSTANCE]));
278         else
279                 s->instance = umdns_host_label;
280         s->service = strcpy(d_service, blobmsg_get_string(_tb[SERVICE_SERVICE]));
281         s->active = 1;
282         s->t = 0;
283         s->txt_len = txt_len;
284         s->txt = d_txt;
285 
286         if (_tb[SERVICE_TXT])
287                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
288                         int len = strlen(blobmsg_get_string(txt));
289                         if (!len)
290                                 return;
291                         if (len > 0xff)
292                                 len = 0xff;
293                         *d_txt = len;
294                         d_txt++;
295                         memcpy(d_txt, blobmsg_get_string(txt), len);
296                         d_txt += len;
297                 }
298 
299         vlist_add(&announced_services, &s->node, s->id);
300 }
301 
302 static void
303 service_load(char *path)
304 {
305         struct blob_attr *cur;
306         glob_t gl;
307         int i, rem;
308 
309         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
310                 return;
311 
312         for (i = 0; i < gl.gl_pathc; i++) {
313                 blob_buf_init(&b, 0);
314                 if (blobmsg_add_json_from_file(&b, gl.gl_pathv[i])) {
315                         blob_for_each_attr(cur, b.head, rem)
316                                 service_load_blob(cur);
317                 } else {
318                         fprintf(stderr, "Error reading %s JSON\n", gl.gl_pathv[i]);
319                 }
320         }
321         globfree(&gl);
322 }
323 
324 static void
325 service_init_cb(struct ubus_request *req, int type, struct blob_attr *msg)
326 {
327         struct blob_attr *cur;
328         int rem;
329 
330         get_hostname();
331 
332         vlist_update(&announced_services);
333         vlist_update(&hostnames);
334         service_load("/etc/umdns/*");
335 
336         blob_for_each_attr(cur, msg, rem) {
337                 struct blob_attr *cur2;
338                 int rem2;
339 
340                 blobmsg_for_each_attr(cur2, cur, rem2) {
341                         struct blob_attr *cur3;
342                         int rem3;
343 
344                         if (strcmp(blobmsg_name(cur2), "instances"))
345                                 continue;
346 
347                         blobmsg_for_each_attr(cur3, cur2, rem3) {
348                                 struct blob_attr *cur4;
349                                 int rem4;
350                                 int running = 0;
351 
352                                 blobmsg_for_each_attr(cur4, cur3, rem4) {
353                                         const char *name = blobmsg_name(cur4);
354 
355                                         if (!strcmp(name, "running")) {
356                                                 running = blobmsg_get_bool(cur4);
357                                         } else if (running && !strcmp(name, "data")) {
358                                                 struct blob_attr *cur5;
359                                                 int rem5;
360 
361                                                 blobmsg_for_each_attr(cur5, cur4, rem5) {
362                                                         struct blob_attr *cur6;
363                                                         int rem6;
364 
365                                                         if (strcmp(blobmsg_name(cur5), "mdns"))
366                                                                 continue;
367 
368                                                         blobmsg_for_each_attr(cur6, cur5, rem6)
369                                                                 service_load_blob(cur6);
370                                                 }
371                                                 break;
372                                         }
373                                 }
374                         }
375                 }
376         }
377         vlist_flush(&announced_services);
378         vlist_flush(&hostnames);
379 }
380 
381 void
382 service_init(int announce)
383 {
384         get_hostname();
385 
386         service_init_announce = announce;
387         ubus_service_list(service_init_cb);
388 }
389 
390 void
391 service_cleanup(void)
392 {
393         vlist_flush(&announced_services);
394         blob_buf_free(&b);
395 }
396 

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