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