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