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 <ifaddrs.h>
  19 #include <resolv.h>
  20 #include <glob.h>
  21 #include <stdio.h>
  22 #include <time.h>
  23
  24 #include <uci.h>
  25 #include <uci_blob.h>
  26
  27 #include <libubox/vlist.h>
  28 #include <libubox/uloop.h>
  29 #include <libubox/avl-cmp.h>
  30 #include <libubox/blobmsg_json.h>
  31
  32 #include "dns.h"
  33 #include "service.h"
  34 #include "util.h"
  35 #include "interface.h"
  36 #include "announce.h"
  37
  38 enum {
  39         SERVICE_SERVICE,
  40         SERVICE_PORT,
  41         SERVICE_TXT,
  42         __SERVICE_MAX,
  43 };
  44
  45 struct service {
  46         struct vlist_node node;
  47
  48         time_t t;
  49
  50         const char *id;
  51         const char *service;
  52         const uint8_t *txt;
  53         int txt_len;
  54         int port;
  55         int active;
  56 };
  57
  58 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
  59         [SERVICE_SERVICE] = { .name = "service", .type = BLOBMSG_TYPE_STRING },
  60         [SERVICE_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
  61         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
  62 };
  63
  64 static void
  65 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
  66                struct vlist_node *node_old);
  67
  68 static struct blob_buf b;
  69 static VLIST_TREE(services, avl_strcmp, service_update, false, false);
  70 static char *sdudp =  "_services._dns-sd._udp.local";
  71 static char *sdtcp =  "_services._dns-sd._tcp.local";
  72 static int service_init_announce;
  73
  74 static const char *
  75 service_name(const char *domain)
  76 {
  77         static char buffer[256];
  78
  79         snprintf(buffer, sizeof(buffer), "%s.%s", mdns_hostname, domain);
  80
  81         return buffer;
  82 }
  83
  84 static void
  85 service_add_ptr(const char *host, int ttl)
  86 {
  87         int len = dn_comp(host, mdns_buf, sizeof(mdns_buf), NULL, NULL);
  88
  89         if (len < 1)
  90                 return;
  91
  92         dns_add_answer(TYPE_PTR, mdns_buf, len, ttl);
  93 }
  94
  95 static void
  96 service_add_srv(struct service *s, int ttl)
  97 {
  98         struct dns_srv_data *sd = (struct dns_srv_data *) mdns_buf;
  99         int len = sizeof(*sd);
 100
 101         len += dn_comp(mdns_hostname_local, mdns_buf + len, sizeof(mdns_buf) - len, NULL, NULL);
 102         if (len <= sizeof(*sd))
 103                 return;
 104
 105         sd->port = cpu_to_be16(s->port);
 106         dns_add_answer(TYPE_SRV, mdns_buf, len, ttl);
 107 }
 108
 109 #define TOUT_LOOKUP     60
 110
 111 static int
 112 service_timeout(struct service *s)
 113 {
 114         time_t t = time(NULL);
 115
 116         if (t - s->t <= TOUT_LOOKUP)
 117                 return 0;
 118
 119         s->t = t;
 120
 121         return 1;
 122 }
 123
 124 void
 125 service_reply_a(struct interface *iface, int type, int ttl)
 126 {
 127         struct ifaddrs *ifap, *ifa;
 128         struct sockaddr_in *sa;
 129         struct sockaddr_in6 *sa6;
 130
 131         getifaddrs(&ifap);
 132
 133         dns_init_answer();
 134         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 135                 if (strcmp(ifa->ifa_name, iface->name))
 136                         continue;
 137                 if (ifa->ifa_addr->sa_family==AF_INET) {
 138                         sa = (struct sockaddr_in *) ifa->ifa_addr;
 139                         dns_add_answer(TYPE_A, (uint8_t *) &sa->sin_addr, 4, ttl);
 140                 }
 141                 if (ifa->ifa_addr->sa_family==AF_INET6) {
 142                         uint8_t ll_prefix[] = {0xfe, 0x80 };
 143                         sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
 144                         if (!memcmp(&sa6->sin6_addr, &ll_prefix, 2))
 145                                 dns_add_answer(TYPE_AAAA, (uint8_t *) &sa6->sin6_addr, 16, ttl);
 146                 }
 147         }
 148         dns_send_answer(iface, mdns_hostname_local);
 149
 150         freeifaddrs(ifap);
 151 }
 152
 153 static void
 154 service_reply_single(struct interface *iface, struct service *s, const char *match, int ttl, int force)
 155 {
 156         const char *host = service_name(s->service);
 157         char *service = strstr(host, "._");
 158
 159         if (!force && (!s->active || !service || !service_timeout(s)))
 160                 return;
 161
 162         service++;
 163
 164         if (match && strcmp(match, s->service))
 165                 return;
 166
 167         dns_init_answer();
 168         service_add_ptr(service_name(s->service), ttl);
 169         dns_send_answer(iface, service);
 170
 171         dns_init_answer();
 172         service_add_srv(s, ttl);
 173         if (s->txt && s->txt_len)
 174                 dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len, ttl);
 175         dns_send_answer(iface, host);
 176 }
 177
 178 void
 179 service_reply(struct interface *iface, const char *match, int ttl)
 180 {
 181         struct service *s;
 182
 183         vlist_for_each_element(&services, s, node)
 184                 service_reply_single(iface, s, match, ttl, 0);
 185
 186         if (match)
 187                 return;
 188
 189         service_reply_a(iface, TYPE_A, ttl);
 190 }
 191
 192 void
 193 service_announce_services(struct interface *iface, const char *service)
 194 {
 195         struct service *s;
 196         int tcp = 1;
 197
 198         if (!strcmp(service, sdudp))
 199                 tcp = 0;
 200         else if (strcmp(service, sdtcp))
 201                 return;
 202
 203         vlist_for_each_element(&services, s, node) {
 204                 if (!strstr(s->service, "._tcp") && tcp)
 205                         continue;
 206                 if (!strstr(s->service, "._udp") && !tcp)
 207                         continue;
 208                 s->t = 0;
 209                 dns_init_answer();
 210                 service_add_ptr(s->service, announce_ttl);
 211                 if (tcp)
 212                         dns_send_answer(iface, sdtcp);
 213                 else
 214                         dns_send_answer(iface, sdudp);
 215                 service_reply(iface, s->service, announce_ttl);
 216         }
 217 }
 218
 219 void
 220 service_announce(struct interface *iface)
 221 {
 222         service_announce_services(iface, sdudp);
 223         service_announce_services(iface, sdtcp);
 224 }
 225
 226 static void
 227 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 228                struct vlist_node *node_old)
 229 {
 230         struct interface *iface;
 231         struct service *s;
 232
 233         if (!node_old) {
 234                 s = container_of(node_new, struct service, node);
 235                 if (service_init_announce)
 236                         vlist_for_each_element(&interfaces, iface, node) {
 237                                 s->t = 0;
 238                                 service_reply_single(iface, s, NULL, announce_ttl, 1);
 239                         }
 240                 return;
 241         }
 242
 243         s = container_of(node_old, struct service, node);
 244         if (!node_new && service_init_announce)
 245                 vlist_for_each_element(&interfaces, iface, node)
 246                         service_reply_single(iface, s, NULL, 0, 1);
 247         free(s);
 248 }
 249
 250 static void
 251 service_load(char *path)
 252 {
 253         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 254         int rem, i;
 255         glob_t gl;
 256
 257         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 258                 return;
 259
 260         for (i = 0; i < gl.gl_pathc; i++) {
 261                 blob_buf_init(&b, 0);
 262
 263                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 264                         continue;
 265                 blob_for_each_attr(cur, b.head, rem) {
 266                         struct service *s;
 267                         char *d_service, *d_id;
 268                         uint8_t *d_txt;
 269                         int rem2;
 270                         int txt_len = 0;
 271
 272                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 273                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 274                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_SERVICE])
 275                                 continue;
 276
 277                         if (_tb[SERVICE_SERVICE])
 278                                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 279                                         txt_len += 1 + strlen(blobmsg_get_string(txt));
 280
 281                         s = calloc_a(sizeof(*s),
 282                                 &d_id, strlen(blobmsg_name(cur)) + 1,
 283                                 &d_service, strlen(blobmsg_get_string(_tb[SERVICE_SERVICE])) + 1,
 284                                 &d_txt, txt_len);
 285                         if (!s)
 286                                 continue;
 287
 288                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 289                         s->id = strcpy(d_id, blobmsg_name(cur));
 290                         s->service = strcpy(d_service, blobmsg_get_string(_tb[SERVICE_SERVICE]));
 291                         s->active = 1;
 292                         s->t = 0;
 293                         s->txt_len = txt_len;
 294                         s->txt = d_txt;
 295
 296                         if (_tb[SERVICE_SERVICE])
 297                                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 298                                         int len = strlen(blobmsg_get_string(txt));
 299                                         if (!len)
 300                                                 continue;
 301                                         if (len > 0xff)
 302                                                 len = 0xff;
 303                                         *d_txt = len;
 304                                         d_txt++;
 305                                         memcpy(d_txt, blobmsg_get_string(txt), len);
 306                                         d_txt += len;
 307                                 }
 308
 309                         vlist_add(&services, &s->node, s->id);
 310                 }
 311         }
 312 }
 313
 314 void
 315 service_init(int announce)
 316 {
 317         service_init_announce = announce;
 318
 319         get_hostname();
 320
 321         vlist_update(&services);
 322         service_load("/tmp/run/mdnsd/*");
 323         vlist_flush(&services);
 324 }
 325
 326 void
 327 service_cleanup(void)
 328 {
 329         vlist_flush(&services);
 330         blob_buf_free(&b);
 331 }