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 *instance, const char *service_domain, int ttl)
 156 {
 157         struct service *s;
 158
 159         vlist_for_each_element(&services, s, node) {
 160                 if (instance && strcmp(s->instance, instance))
 161                         continue;
 162                 if (service_domain && strcmp(s->service, service_domain))
 163                         continue;
 164                 service_reply_single(iface, to, s, ttl, 0);
 165         }
 166 }
 167
 168 void
 169 service_announce_services(struct interface *iface, struct sockaddr *to, int ttl)
 170 {
 171         struct service *s;
 172
 173         vlist_for_each_element(&services, s, node) {
 174                 s->t = 0;
 175                 if (ttl) {
 176                         dns_init_answer();
 177                         service_add_ptr(s->service, ttl);
 178                         dns_send_answer(iface, to, C_DNS_SD);
 179                 }
 180                 service_reply_single(iface, to, s, ttl, 0);
 181         }
 182 }
 183
 184 static void
 185 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 186                struct vlist_node *node_old)
 187 {
 188         struct interface *iface;
 189         struct service *s;
 190
 191         if (!node_old) {
 192                 s = container_of(node_new, struct service, node);
 193                 if (service_init_announce)
 194                         vlist_for_each_element(&interfaces, iface, node) {
 195                                 s->t = 0;
 196                                 service_reply_single(iface, NULL, s, announce_ttl, 1);
 197                         }
 198                 return;
 199         }
 200
 201         s = container_of(node_old, struct service, node);
 202         if (!node_new && service_init_announce)
 203                 vlist_for_each_element(&interfaces, iface, node)
 204                         service_reply_single(iface, NULL, s, 0, 1);
 205         free(s);
 206 }
 207
 208 static void
 209 service_load_blob(struct blob_attr *b)
 210 {
 211         struct blob_attr *txt, *_tb[__SERVICE_MAX];
 212         struct service *s;
 213         char *d_service, *d_id;
 214         uint8_t *d_txt;
 215         int rem2;
 216         int txt_len = 0;
 217
 218         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 219                 _tb, blobmsg_data(b), blobmsg_data_len(b));
 220         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_SERVICE])
 221                 return;
 222
 223         if (_tb[SERVICE_TXT])
 224                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 225                         txt_len += 1 + strlen(blobmsg_get_string(txt));
 226
 227         s = calloc_a(sizeof(*s),
 228                 &d_id, strlen(blobmsg_name(b)) + 1,
 229                 &d_service, strlen(blobmsg_get_string(_tb[SERVICE_SERVICE])) + 1,
 230                 &d_txt, txt_len);
 231         if (!s)
 232                 return;
 233
 234         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 235         s->id = strcpy(d_id, blobmsg_name(b));
 236         s->instance = umdns_host_label;
 237         s->service = strcpy(d_service, blobmsg_get_string(_tb[SERVICE_SERVICE]));
 238         s->active = 1;
 239         s->t = 0;
 240         s->txt_len = txt_len;
 241         s->txt = d_txt;
 242
 243         if (_tb[SERVICE_TXT])
 244                 blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 245                         int len = strlen(blobmsg_get_string(txt));
 246                         if (!len)
 247                                 return;
 248                         if (len > 0xff)
 249                                 len = 0xff;
 250                         *d_txt = len;
 251                         d_txt++;
 252                         memcpy(d_txt, blobmsg_get_string(txt), len);
 253                         d_txt += len;
 254                 }
 255
 256         vlist_add(&services, &s->node, s->id);
 257 }
 258
 259 static void
 260 service_load(char *path)
 261 {
 262         struct blob_attr *cur;
 263         glob_t gl;
 264         int i, rem;
 265
 266         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 267                 return;
 268
 269         for (i = 0; i < gl.gl_pathc; i++) {
 270                 blob_buf_init(&b, 0);
 271                 if (blobmsg_add_json_from_file(&b, gl.gl_pathv[i])) {
 272                         blob_for_each_attr(cur, b.head, rem)
 273                                 service_load_blob(cur);
 274                 } else {
 275                         fprintf(stderr, "Error reading %s JSON\n", gl.gl_pathv[i]);
 276                 }
 277         }
 278         globfree(&gl);
 279 }
 280
 281 static void
 282 service_init_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 283 {
 284         struct blob_attr *cur;
 285         int rem;
 286
 287         get_hostname();
 288
 289         vlist_update(&services);
 290         service_load("/etc/umdns/*");
 291
 292         blob_for_each_attr(cur, msg, rem) {
 293                 struct blob_attr *cur2;
 294                 int rem2;
 295
 296                 blobmsg_for_each_attr(cur2, cur, rem2) {
 297                         struct blob_attr *cur3;
 298                         int rem3;
 299
 300                         if (strcmp(blobmsg_name(cur2), "instances"))
 301                                 continue;
 302
 303                         blobmsg_for_each_attr(cur3, cur2, rem3) {
 304                                 struct blob_attr *cur4;
 305                                 int rem4;
 306                                 int running = 0;
 307
 308                                 blobmsg_for_each_attr(cur4, cur3, rem4) {
 309                                         const char *name = blobmsg_name(cur4);
 310
 311                                         if (!strcmp(name, "running")) {
 312                                                 running = blobmsg_get_bool(cur4);
 313                                         } else if (running && !strcmp(name, "data")) {
 314                                                 struct blob_attr *cur5;
 315                                                 int rem5;
 316
 317                                                 blobmsg_for_each_attr(cur5, cur4, rem5) {
 318                                                         struct blob_attr *cur6;
 319                                                         int rem6;
 320
 321                                                         if (strcmp(blobmsg_name(cur5), "mdns"))
 322                                                                 continue;
 323
 324                                                         blobmsg_for_each_attr(cur6, cur5, rem6)
 325                                                                 service_load_blob(cur6);
 326                                                 }
 327                                                 break;
 328                                         }
 329                                 }
 330                         }
 331                 }
 332         }
 333         vlist_flush(&services);
 334 }
 335
 336 void
 337 service_init(int announce)
 338 {
 339         get_hostname();
 340
 341         service_init_announce = announce;
 342         ubus_service_list(service_init_cb);
 343 }
 344
 345 void
 346 service_cleanup(void)
 347 {
 348         vlist_flush(&services);
 349         blob_buf_free(&b);
 350 }