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 <netinet/in.h>
  16 #include <arpa/nameser.h>
  17 #include <sys/socket.h>
  18 #include <netinet/in.h>
  19 #include <arpa/inet.h>
  20
  21 #include <resolv.h>
  22 #include <glob.h>
  23 #include <stdio.h>
  24 #include <time.h>
  25
  26 #include <uci.h>
  27 #include <uci_blob.h>
  28
  29 #include <libubox/vlist.h>
  30 #include <libubox/uloop.h>
  31 #include <libubox/avl-cmp.h>
  32 #include <libubox/blobmsg_json.h>
  33
  34 #include "dns.h"
  35 #include "service.h"
  36 #include "util.h"
  37 #include "interface.h"
  38
  39 enum {
  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 *service;
  51         const char *daemon;
  52         const uint8_t *txt;
  53         int txt_len;
  54         int port;
  55         int active;
  56 };
  57
  58 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
  59         [SERVICE_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
  60         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
  61 };
  62
  63 static const struct uci_blob_param_list service_attr_list = {
  64         .n_params = __SERVICE_MAX,
  65         .params = service_policy,
  66 };
  67
  68 static void
  69 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
  70                struct vlist_node *node_old);
  71
  72 static struct blob_buf b;
  73 static VLIST_TREE(services, avl_strcmp, service_update, false, false);
  74 char *hostname = NULL;
  75 static char *sdudp =  "_services._dns-sd._udp.local";
  76 static char *sdtcp =  "_services._dns-sd._tcp.local";
  77
  78 char *
  79 service_name(const char *domain)
  80 {
  81         static char buffer[256];
  82
  83         snprintf(buffer, sizeof(buffer), "%s.%s", hostname, domain);
  84
  85         return buffer;
  86 }
  87
  88 static void
  89 service_send_ptr(struct uloop_fd *u, struct service *s)
  90 {
  91         unsigned char buffer[MAX_NAME_LEN];
  92         const char *host = service_name(s->service);
  93         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
  94
  95         if (len < 1)
  96                 return;
  97
  98         dns_add_answer(TYPE_PTR, buffer, len);
  99 }
 100
 101 static void
 102 service_send_ptr_c(struct uloop_fd *u, const char *host)
 103 {
 104         unsigned char buffer[MAX_NAME_LEN];
 105         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 106
 107         if (len < 1)
 108                 return;
 109
 110         dns_add_answer(TYPE_PTR, buffer, len);
 111 }
 112
 113 static void
 114 service_send_a(struct uloop_fd *u)
 115 {
 116         unsigned char buffer[MAX_NAME_LEN];
 117         char *host = service_name("local");
 118         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 119         struct in_addr in;
 120
 121         if (!inet_aton(cur_iface->ip, &in)) {
 122                 fprintf(stderr, "%s is not valid\n", cur_iface->ip);
 123                 return;
 124         }
 125
 126         if (len < 1)
 127                 return;
 128
 129         dns_add_answer(TYPE_A, (uint8_t *) &in.s_addr, 4);
 130 }
 131
 132 static void
 133 service_send_srv(struct uloop_fd *u, struct service *s)
 134 {
 135         unsigned char buffer[MAX_NAME_LEN];
 136         struct dns_srv_data *sd;
 137         char *host = service_name("local");
 138         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 139
 140         if (len < 1)
 141                 return;
 142
 143         sd = calloc(1, len + sizeof(struct dns_srv_data));
 144         if (!sd)
 145                 return;
 146
 147         sd->port = cpu_to_be16(s->port);
 148         memcpy(&sd[1], buffer, len);
 149         host = service_name(s->service);
 150         dns_add_answer(TYPE_SRV, (uint8_t *) sd, len + sizeof(struct dns_srv_data));
 151         free(sd);
 152 }
 153
 154 #define TOUT_LOOKUP     60
 155
 156 static int
 157 service_timeout(struct service *s)
 158 {
 159         time_t t = time(NULL);
 160
 161         if (t - s->t <= TOUT_LOOKUP)
 162                 return 0;
 163
 164         s->t = t;
 165
 166         return 1;
 167 }
 168
 169 void
 170 service_reply_a(struct uloop_fd *u, int type)
 171 {
 172         if (type != TYPE_A)
 173                 return;
 174
 175         dns_init_answer();
 176         service_send_a(u);
 177         dns_send_answer(u, service_name("local"));
 178 }
 179
 180 void
 181 service_reply(struct uloop_fd *u, const char *match)
 182 {
 183         struct service *s;
 184
 185         vlist_for_each_element(&services, s, node) {
 186                 char *host = service_name(s->service);
 187                 char *service = strstr(host, "._");
 188
 189                 if (!s->active || !service || !service_timeout(s))
 190                         continue;
 191
 192                 service++;
 193
 194                 if (match && strcmp(match, s->service))
 195                         continue;
 196
 197                 dns_init_answer();
 198                 service_send_ptr(u, s);
 199                 dns_send_answer(u, service);
 200
 201                 dns_init_answer();
 202                 service_send_srv(u, s);
 203                 if (s->txt && s->txt_len)
 204                         dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len);
 205                 dns_send_answer(u, host);
 206         }
 207
 208         if (match)
 209                 return;
 210
 211         dns_init_answer();
 212         service_send_a(u);
 213         dns_send_answer(u, service_name("local"));
 214 }
 215
 216 void
 217 service_announce_services(struct uloop_fd *u, const char *service)
 218 {
 219         struct service *s;
 220         int tcp = 1;
 221
 222         if (!strcmp(service, sdudp))
 223                 tcp = 0;
 224         else if (strcmp(service, sdtcp))
 225                 return;
 226
 227         vlist_for_each_element(&services, s, node) {
 228                 if (!strstr(s->service, "._tcp") && tcp)
 229                         continue;
 230                 if (!strstr(s->service, "._udp") && !tcp)
 231                         continue;
 232                 s->t = 0;
 233                 dns_init_answer();
 234                 service_send_ptr_c(u, s->service);
 235                 if (tcp)
 236                         dns_send_answer(u, sdtcp);
 237                 else
 238                         dns_send_answer(u, sdudp);
 239                 service_reply(u, s->service);
 240         }
 241 }
 242
 243 void
 244 service_announce(struct uloop_fd *u)
 245 {
 246         service_announce_services(u, sdudp);
 247         service_announce_services(u, sdtcp);
 248 }
 249
 250 static void
 251 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 252                struct vlist_node *node_old)
 253 {
 254         struct service *s;
 255
 256         if (!node_old)
 257                 return;
 258
 259         s = container_of(node_old, struct service, node);
 260         free(s);
 261 }
 262
 263 static void
 264 service_load(char *path)
 265 {
 266         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 267         int rem, i;
 268         glob_t gl;
 269
 270         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 271                 return;
 272
 273         for (i = 0; i < gl.gl_pathc; i++) {
 274                 blob_buf_init(&b, 0);
 275
 276                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 277                         continue;
 278                 blob_for_each_attr(cur, b.head, rem) {
 279                         struct service *s;
 280                         char *d_service, *d_daemon;
 281                         uint8_t *d_txt;
 282                         int rem2;
 283                         int txt_len = 0;
 284
 285                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 286                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 287                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_TXT])
 288                                 continue;
 289
 290                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 291                                 txt_len += 1 + strlen(blobmsg_get_string(txt));
 292
 293                         s = calloc_a(sizeof(*s),
 294                                 &d_daemon, strlen(gl.gl_pathv[i]) + 1,
 295                                 &d_service, strlen(blobmsg_name(cur)) + 1,
 296                                 &d_txt, txt_len);
 297                         if (!s)
 298                                 continue;
 299
 300                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 301                         s->service = strcpy(d_service, blobmsg_name(cur));
 302                         s->daemon = strcpy(d_daemon, gl.gl_pathv[i]);
 303                         s->active = 1;
 304                         s->t = 0;
 305                         s->txt_len = txt_len;
 306                         s->txt = d_txt;
 307
 308                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 309                                 int len = strlen(blobmsg_get_string(txt));
 310                                 if (!len)
 311                                         continue;
 312                                 if (len > 0xff)
 313                                         len = 0xff;
 314                                 *d_txt = len;
 315                                 d_txt++;
 316                                 memcpy(d_txt, blobmsg_get_string(txt), len);
 317                                 d_txt += len;
 318                         }
 319
 320                         vlist_add(&services, &s->node, s->service);
 321                 }
 322         }
 323 }
 324
 325 void
 326 service_init(void)
 327 {
 328         if (!hostname)
 329                 hostname = get_hostname();
 330
 331         vlist_update(&services);
 332         service_load("/tmp/run/mdnsd/*");
 333         vlist_flush(&services);
 334 }
 335
 336 void
 337 service_cleanup(void)
 338 {
 339         vlist_flush(&services);
 340 }