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/vlist.h>
  26 #include <libubox/uloop.h>
  27 #include <libubox/avl-cmp.h>
  28 #include <libubox/blobmsg_json.h>
  29
  30 #include "ubus.h"
  31 #include "dns.h"
  32 #include "service.h"
  33 #include "util.h"
  34 #include "interface.h"
  35 #include "announce.h"
  36
  37 enum {
  38         SERVICE_INSTANCE,
  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 *instance;
  52         const char *service;
  53         const uint8_t *txt;
  54         int txt_len;
  55         int port;
  56         int active;
  57 };
  58
  59 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
  60         [SERVICE_INSTANCE] = { .name = "instance", .type = BLOBMSG_TYPE_STRING },
  61         [SERVICE_SERVICE] = { .name = "service", .type = BLOBMSG_TYPE_STRING },
  62         [SERVICE_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
  63         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
  64 };
  65
  66 static void
  67 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
  68                struct vlist_node *node_old);
  69
  70 static struct blob_buf b;
  71 static VLIST_TREE(services, avl_strcmp, service_update, false, false);
  72 static int service_init_announce;
  73
  74 /**
  75  * service_instance_name - construct Service Instance Name as in RFC 6763
  76  *
  77  * RFC 6763 specifies Service Instance Names in the following way:
  78  *
  79  * Service Instance Name = <Instance> . <Service> . <Domain>
  80  *
  81  * @s: service to generate service instance name for
  82  */
  83 static const char *
  84 service_instance_name(struct service *s)
  85 {
  86         static char buffer[256];
  87
  88         snprintf(buffer, sizeof(buffer), "%s.%s", s->instance, s->service);
  89
  90         return buffer;
  91 }
  92
  93 static void
  94 service_add_ptr(const char *host, int ttl)
  95 {
  96         int len = dn_comp(host, mdns_buf, sizeof(mdns_buf), NULL, NULL);
  97
  98         if (len < 1)
  99                 return;
 100
 101         dns_add_answer(TYPE_PTR, mdns_buf, len, ttl);
 102 }
 103
 104 static void
 105 service_add_srv(struct service *s, int ttl)
 106 {
 107         struct dns_srv_data *sd = (struct dns_srv_data *) mdns_buf;
 108         int len = sizeof(*sd);
 109
 110         len += dn_comp(mdns_hostname_local, mdns_buf + len, sizeof(mdns_buf) - len, NULL, NULL);
 111         if (len <= sizeof(*sd))
 112                 return;
 113
 114         sd->port = cpu_to_be16(s->port);
 115         dns_add_answer(TYPE_SRV, mdns_buf, len, ttl);
 116 }
 117
 118 #define TOUT_LOOKUP     60
 119
 120 static time_t
 121 service_timeout(struct service *s)
 122 {
 123         time_t t = monotonic_time();
 124
 125         if (t - s->t <= TOUT_LOOKUP) {
 126                 DBG(2, "t=%" PRId64 ", s->t=%" PRId64 ", t - s->t = %" PRId64 "\n", (int64_t)t, (int64_t)s->t, (int64_t)(t - s->t));
 127                 return 0;
 128         }
 129
 130         return t;
 131 }
 132
 133 static void
 134 service_reply_single(struct interface *iface, struct sockaddr *to, struct service *s, int ttl, int force)
 135 {
 136         const char *host = service_instance_name(s);
 137         char *service = strstr(host, "._");
 138         time_t t = service_timeout(s);
 139
 140
 141         if (!force && (!s->active || !service || !t))
 142                 return;
 143
 144         service++;
 145
 146         s->t = t;
 147
 148         dns_init_answer();
 149         service_add_ptr(service_instance_name(s), ttl);
 150         dns_send_answer(iface, to, service);
 151
 152         dns_init_answer();
 153         service_add_srv(s, ttl);
 154         if (s->txt && s->txt_len)
 155                 dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len, ttl);
 156         dns_send_answer(iface, to, host);
 157 }
 158
 159 void
 160 service_reply(struct interface *iface, struct sockaddr *to, const char *instance, const char *service_domain, int ttl)
 161 {
 162         struct service *s;
 163
 164         vlist_for_each_element(&services, s, node) {
 165                 if (instance && strcmp(s->instance, instance))
 166                         continue;
 167                 if (service_domain && strcmp(s->service, service_domain))
 168                         continue;
 169                 service_reply_single(iface, to, s, ttl, 0);
 170         }
 171 }
 172
 173 void
 174 service_announce_services(struct interface *iface, struct sockaddr *to, int ttl)
 175 {
 176         struct service *s;
 177
 178         vlist_for_each_element(&services, s, node) {
 179                 s->t = 0;
 180                 if (ttl) {
 181                         dns_init_answer();
 182                         service_add_ptr(s->service, ttl);
 183                         dns_send_answer(iface, to, C_DNS_SD);
 184                 }
 185                 service_reply_single(iface, to, s, ttl, 0);
 186         }
 187 }
 188
 189 static void
 190 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 191                struct vlist_node *node_old)
 192 {
 193         struct interface *iface;
 194         struct service *s;
 195
 196         if (!node_old) {
 197                 s = container_of(node_new, struct service, node);
 198                 if (service_init_announce)
 199                         vlist_for_each_element(&interfaces, iface, node) {
 200                                 s->t = 0;
 201                                 service_reply_single(iface, NULL, s, announce_ttl, 1);
 202                         }
 203                 return;
 204         }
 205
 206         s = container_of(node_old, struct service, node);
 207         if (!node_new && service_init_announce)
 208                 vlist_for_each_element(&interfaces, iface, node)
 209                         service_reply_single(iface, NULL, s, 0, 1);
 210         free(s);
 211 }
 212
 213 static void
 214 service_load_blob(struct blob_attr *b)
 215 {
 216         struct blob_attr *txt, *_tb[__SERVICE_MAX];
 217         struct service *s;
 218         char *d_instance, *d_service, *d_id;
 219         uint8_t *d_txt;
 220         int rem2;
 221         int txt_len = 0;
 222         unsigned int n;
 223
 224         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 225                 _tb, blobmsg_data(b), blobmsg_data_len(b));
 226         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_SERVICE])
 227                 return;
 228
 229         if (_tb[SERVICE_TXT])
 230                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 231                         txt_len += 1 + strlen(blobmsg_get_string(txt));
 232
 233         n = strlen(blobmsg_name(b));
 234         s = calloc_a(sizeof(*s),
 235                 &d_id, n + 1,
 236                 &d_instance, _tb[SERVICE_INSTANCE] ? strlen(blobmsg_get_string(_tb[SERVICE_INSTANCE])) + 1 : 0,
 237                 &d_service, strlen(blobmsg_get_string(_tb[SERVICE_SERVICE])) + 1,
 238                 &d_txt, txt_len);
 239         if (!s)
 240                 return;
 241
 242         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 243         s->id = strncpy(d_id, blobmsg_name(b), n);
 244         if (_tb[SERVICE_INSTANCE])
 245                 s->instance = strcpy(d_instance, blobmsg_get_string(_tb[SERVICE_INSTANCE]));
 246         else
 247                 s->instance = umdns_host_label;
 248         s->service = strcpy(d_service, blobmsg_get_string(_tb[SERVICE_SERVICE]));
 249         s->active = 1;
 250         s->t = 0;
 251         s->txt_len = txt_len;
 252         s->txt = d_txt;
 253
 254         if (_tb[SERVICE_TXT])
 255                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 256                         int len = strlen(blobmsg_get_string(txt));
 257                         if (!len)
 258                                 return;
 259                         if (len > 0xff)
 260                                 len = 0xff;
 261                         *d_txt = len;
 262                         d_txt++;
 263                         memcpy(d_txt, blobmsg_get_string(txt), len);
 264                         d_txt += len;
 265                 }
 266
 267         vlist_add(&services, &s->node, s->id);
 268 }
 269
 270 static void
 271 service_load(char *path)
 272 {
 273         struct blob_attr *cur;
 274         glob_t gl;
 275         int i, rem;
 276
 277         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 278                 return;
 279
 280         for (i = 0; i < gl.gl_pathc; i++) {
 281                 blob_buf_init(&b, 0);
 282                 if (blobmsg_add_json_from_file(&b, gl.gl_pathv[i])) {
 283                         blob_for_each_attr(cur, b.head, rem)
 284                                 service_load_blob(cur);
 285                 } else {
 286                         fprintf(stderr, "Error reading %s JSON\n", gl.gl_pathv[i]);
 287                 }
 288         }
 289         globfree(&gl);
 290 }
 291
 292 static void
 293 service_init_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 294 {
 295         struct blob_attr *cur;
 296         int rem;
 297
 298         get_hostname();
 299
 300         vlist_update(&services);
 301         service_load("/etc/umdns/*");
 302
 303         blob_for_each_attr(cur, msg, rem) {
 304                 struct blob_attr *cur2;
 305                 int rem2;
 306
 307                 blobmsg_for_each_attr(cur2, cur, rem2) {
 308                         struct blob_attr *cur3;
 309                         int rem3;
 310
 311                         if (strcmp(blobmsg_name(cur2), "instances"))
 312                                 continue;
 313
 314                         blobmsg_for_each_attr(cur3, cur2, rem3) {
 315                                 struct blob_attr *cur4;
 316                                 int rem4;
 317                                 int running = 0;
 318
 319                                 blobmsg_for_each_attr(cur4, cur3, rem4) {
 320                                         const char *name = blobmsg_name(cur4);
 321
 322                                         if (!strcmp(name, "running")) {
 323                                                 running = blobmsg_get_bool(cur4);
 324                                         } else if (running && !strcmp(name, "data")) {
 325                                                 struct blob_attr *cur5;
 326                                                 int rem5;
 327
 328                                                 blobmsg_for_each_attr(cur5, cur4, rem5) {
 329                                                         struct blob_attr *cur6;
 330                                                         int rem6;
 331
 332                                                         if (strcmp(blobmsg_name(cur5), "mdns"))
 333                                                                 continue;
 334
 335                                                         blobmsg_for_each_attr(cur6, cur5, rem6)
 336                                                                 service_load_blob(cur6);
 337                                                 }
 338                                                 break;
 339                                         }
 340                                 }
 341                         }
 342                 }
 343         }
 344         vlist_flush(&services);
 345 }
 346
 347 void
 348 service_init(int announce)
 349 {
 350         get_hostname();
 351
 352         service_init_announce = announce;
 353         ubus_service_list(service_init_cb);
 354 }
 355
 356 void
 357 service_cleanup(void)
 358 {
 359         vlist_flush(&services);
 360         blob_buf_free(&b);
 361 }