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 <stdio.h>
  21 #include <time.h>
  22
  23 #include <libubus.h>
  24 #include <libubox/vlist.h>
  25 #include <libubox/uloop.h>
  26 #include <libubox/avl-cmp.h>
  27 #include <libubox/blobmsg_json.h>
  28
  29 #include "ubus.h"
  30 #include "dns.h"
  31 #include "service.h"
  32 #include "util.h"
  33 #include "interface.h"
  34 #include "announce.h"
  35
  36 enum {
  37         SERVICE_SERVICE,
  38         SERVICE_PORT,
  39         SERVICE_TXT,
  40         __SERVICE_MAX,
  41 };
  42
  43 struct service {
  44         struct vlist_node node;
  45
  46         time_t t;
  47
  48         const char *id;
  49         const char *service;
  50         const uint8_t *txt;
  51         int txt_len;
  52         int port;
  53         int active;
  54 };
  55
  56 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
  57         [SERVICE_SERVICE] = { .name = "service", .type = BLOBMSG_TYPE_STRING },
  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 int service_init_announce;
  69
  70 /**
  71  * service_instance_name - construct Service Instance Name as in RFC 6763
  72  *
  73  * RFC 6763 specifies Service Instance Names in the following way:
  74  *
  75  * Service Instance Name = <Instance> . <Service> . <Domain>
  76  *
  77  * @service_domain: service name (a pair of labels) with domain name appended
  78  */
  79 static const char *
  80 service_instance_name(const char *service_domain)
  81 {
  82         static char buffer[256];
  83
  84         snprintf(buffer, sizeof(buffer), "%s.%s", umdns_host_label, service_domain);
  85
  86         return buffer;
  87 }
  88
  89 static void
  90 service_add_ptr(const char *host, int ttl)
  91 {
  92         int len = dn_comp(host, mdns_buf, sizeof(mdns_buf), NULL, NULL);
  93
  94         if (len < 1)
  95                 return;
  96
  97         dns_add_answer(TYPE_PTR, mdns_buf, len, ttl);
  98 }
  99
 100 static void
 101 service_add_srv(struct service *s, int ttl)
 102 {
 103         struct dns_srv_data *sd = (struct dns_srv_data *) mdns_buf;
 104         int len = sizeof(*sd);
 105
 106         len += dn_comp(mdns_hostname_local, mdns_buf + len, sizeof(mdns_buf) - len, NULL, NULL);
 107         if (len <= sizeof(*sd))
 108                 return;
 109
 110         sd->port = cpu_to_be16(s->port);
 111         dns_add_answer(TYPE_SRV, mdns_buf, len, ttl);
 112 }
 113
 114 #define TOUT_LOOKUP     60
 115
 116 static time_t
 117 service_timeout(struct service *s)
 118 {
 119         time_t t = monotonic_time();
 120
 121         if (t - s->t <= TOUT_LOOKUP)
 122                 return 0;
 123
 124         return t;
 125 }
 126
 127 static void
 128 service_reply_single(struct interface *iface, struct sockaddr *to, struct service *s, int ttl, int force)
 129 {
 130         const char *host = service_instance_name(s->service);
 131         char *service = strstr(host, "._");
 132         time_t t = service_timeout(s);
 133
 134
 135         if (!force && (!s->active || !service || !t))
 136                 return;
 137
 138         service++;
 139
 140         s->t = t;
 141
 142         dns_init_answer();
 143         service_add_ptr(service_instance_name(s->service), ttl);
 144         dns_send_answer(iface, to, service);
 145
 146         dns_init_answer();
 147         service_add_srv(s, ttl);
 148         if (s->txt && s->txt_len)
 149                 dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len, ttl);
 150         dns_send_answer(iface, to, host);
 151 }
 152
 153 void
 154 service_reply(struct interface *iface, struct sockaddr *to, const char *match, int ttl)
 155 {
 156         struct service *s;
 157
 158         vlist_for_each_element(&services, s, node) {
 159                 if (!match || !strcmp(s->service, match))
 160                         service_reply_single(iface, to, s, ttl, 0);
 161         }
 162 }
 163
 164 void
 165 service_announce_services(struct interface *iface, struct sockaddr *to, int ttl)
 166 {
 167         struct service *s;
 168
 169         vlist_for_each_element(&services, s, node) {
 170                 s->t = 0;
 171                 if (ttl) {
 172                         dns_init_answer();
 173                         service_add_ptr(s->service, ttl);
 174                         dns_send_answer(iface, to, C_DNS_SD);
 175                 }
 176                 service_reply_single(iface, to, s, ttl, 0);
 177         }
 178 }
 179
 180 static void
 181 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 182                struct vlist_node *node_old)
 183 {
 184         struct interface *iface;
 185         struct service *s;
 186
 187         if (!node_old) {
 188                 s = container_of(node_new, struct service, node);
 189                 if (service_init_announce)
 190                         vlist_for_each_element(&interfaces, iface, node) {
 191                                 s->t = 0;
 192                                 service_reply_single(iface, NULL, s, announce_ttl, 1);
 193                         }
 194                 return;
 195         }
 196
 197         s = container_of(node_old, struct service, node);
 198         if (!node_new && service_init_announce)
 199                 vlist_for_each_element(&interfaces, iface, node)
 200                         service_reply_single(iface, NULL, s, 0, 1);
 201         free(s);
 202 }
 203
 204 static void
 205 service_load_blob(struct blob_attr *b)
 206 {
 207         struct blob_attr *txt, *_tb[__SERVICE_MAX];
 208         struct service *s;
 209         char *d_service, *d_id;
 210         uint8_t *d_txt;
 211         int rem2;
 212         int txt_len = 0;
 213
 214         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 215                 _tb, blobmsg_data(b), blobmsg_data_len(b));
 216         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_SERVICE])
 217                 return;
 218
 219         if (_tb[SERVICE_TXT])
 220                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 221                         txt_len += 1 + strlen(blobmsg_get_string(txt));
 222
 223         s = calloc_a(sizeof(*s),
 224                 &d_id, strlen(blobmsg_name(b)) + 1,
 225                 &d_service, strlen(blobmsg_get_string(_tb[SERVICE_SERVICE])) + 1,
 226                 &d_txt, txt_len);
 227         if (!s)
 228                 return;
 229
 230         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 231         s->id = strcpy(d_id, blobmsg_name(b));
 232         s->service = strcpy(d_service, blobmsg_get_string(_tb[SERVICE_SERVICE]));
 233         s->active = 1;
 234         s->t = 0;
 235         s->txt_len = txt_len;
 236         s->txt = d_txt;
 237
 238         if (_tb[SERVICE_TXT])
 239                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 240                         int len = strlen(blobmsg_get_string(txt));
 241                         if (!len)
 242                                 return;
 243                         if (len > 0xff)
 244                                 len = 0xff;
 245                         *d_txt = len;
 246                         d_txt++;
 247                         memcpy(d_txt, blobmsg_get_string(txt), len);
 248                         d_txt += len;
 249                 }
 250
 251         vlist_add(&services, &s->node, s->id);
 252 }
 253
 254 static void
 255 service_load(char *path)
 256 {
 257         struct blob_attr *cur;
 258         glob_t gl;
 259         int i, rem;
 260
 261         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 262                 return;
 263
 264         for (i = 0; i < gl.gl_pathc; i++) {
 265                 blob_buf_init(&b, 0);
 266                 if (blobmsg_add_json_from_file(&b, gl.gl_pathv[i])) {
 267                         blob_for_each_attr(cur, b.head, rem)
 268                                 service_load_blob(cur);
 269                 } else {
 270                         fprintf(stderr, "Error reading %s JSON\n", gl.gl_pathv[i]);
 271                 }
 272         }
 273         globfree(&gl);
 274 }
 275
 276 static void
 277 service_init_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 278 {
 279         struct blob_attr *cur;
 280         int rem;
 281
 282         get_hostname();
 283
 284         vlist_update(&services);
 285         service_load("/etc/umdns/*");
 286
 287         blob_for_each_attr(cur, msg, rem) {
 288                 struct blob_attr *cur2;
 289                 int rem2;
 290
 291                 blobmsg_for_each_attr(cur2, cur, rem2) {
 292                         struct blob_attr *cur3;
 293                         int rem3;
 294
 295                         if (strcmp(blobmsg_name(cur2), "instances"))
 296                                 continue;
 297
 298                         blobmsg_for_each_attr(cur3, cur2, rem3) {
 299                                 struct blob_attr *cur4;
 300                                 int rem4;
 301                                 int running = 0;
 302
 303                                 blobmsg_for_each_attr(cur4, cur3, rem4) {
 304                                         const char *name = blobmsg_name(cur4);
 305
 306                                         if (!strcmp(name, "running")) {
 307                                                 running = blobmsg_get_bool(cur4);
 308                                         } else if (running && !strcmp(name, "data")) {
 309                                                 struct blob_attr *cur5;
 310                                                 int rem5;
 311
 312                                                 blobmsg_for_each_attr(cur5, cur4, rem5) {
 313                                                         struct blob_attr *cur6;
 314                                                         int rem6;
 315
 316                                                         if (strcmp(blobmsg_name(cur5), "mdns"))
 317                                                                 continue;
 318
 319                                                         blobmsg_for_each_attr(cur6, cur5, rem6)
 320                                                                 service_load_blob(cur6);
 321                                                 }
 322                                                 break;
 323                                         }
 324                                 }
 325                         }
 326                 }
 327         }
 328         vlist_flush(&services);
 329 }
 330
 331 void
 332 service_init(int announce)
 333 {
 334         get_hostname();
 335
 336         service_init_announce = announce;
 337         ubus_service_list(service_init_cb);
 338 }
 339
 340 void
 341 service_cleanup(void)
 342 {
 343         vlist_flush(&services);
 344         blob_buf_free(&b);
 345 }