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