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/avl.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
  38 enum {
  39         SERVICE_PORT,
  40         SERVICE_TXT,
  41         __SERVICE_MAX,
  42 };
  43
  44 struct service {
  45         struct avl_node avl;
  46
  47         time_t t;
  48
  49         char *service;
  50         char *daemon;
  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_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
  59         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
  60 };
  61
  62 static const struct uci_blob_param_list service_attr_list = {
  63         .n_params = __SERVICE_MAX,
  64         .params = service_policy,
  65 };
  66
  67 static struct blob_buf b;
  68 static struct avl_tree services;
  69 char *hostname = NULL;
  70 static char *sdudp =  "_services._dns-sd._udp.local";
  71 static char *sdtcp =  "_services._dns-sd._tcp.local";
  72
  73 char*
  74 service_name(char *domain)
  75 {
  76         static char buffer[256];
  77
  78         snprintf(buffer, sizeof(buffer), "%s.%s", hostname, domain);
  79
  80         return buffer;
  81 }
  82
  83 static void
  84 service_send_ptr(struct uloop_fd *u, struct service *s)
  85 {
  86         unsigned char buffer[MAX_NAME_LEN];
  87         char *host = service_name(s->service);
  88         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
  89
  90         if (len < 1)
  91                 return;
  92
  93         dns_add_answer(TYPE_PTR, buffer, len);
  94 }
  95
  96 static void
  97 service_send_ptr_c(struct uloop_fd *u, char *host)
  98 {
  99         unsigned char buffer[MAX_NAME_LEN];
 100         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 101
 102         if (len < 1)
 103                 return;
 104
 105         dns_add_answer(TYPE_PTR, buffer, len);
 106 }
 107
 108 static void
 109 service_send_a(struct uloop_fd *u)
 110 {
 111         unsigned char buffer[MAX_NAME_LEN];
 112         char *host = service_name("local");
 113         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 114         struct in_addr in;
 115
 116         if (!inet_aton(iface_ip, &in)) {
 117                 fprintf(stderr, "%s is not valid\n", iface_ip);
 118                 return;
 119         }
 120
 121         if (len < 1)
 122                 return;
 123
 124         dns_add_answer(TYPE_A, (uint8_t *) &in.s_addr, 4);
 125 }
 126
 127 static void
 128 service_send_srv(struct uloop_fd *u, struct service *s)
 129 {
 130         unsigned char buffer[MAX_NAME_LEN];
 131         struct dns_srv_data *sd;
 132         char *host = service_name("local");
 133         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 134
 135         if (len < 1)
 136                 return;
 137
 138         sd = calloc(1, len + sizeof(struct dns_srv_data));
 139         if (!sd)
 140                 return;
 141
 142         sd->port = cpu_to_be16(s->port);
 143         memcpy(&sd[1], buffer, len);
 144         host = service_name(s->service);
 145         dns_add_answer(TYPE_SRV, (uint8_t *) sd, len + sizeof(struct dns_srv_data));
 146         free(sd);
 147 }
 148
 149 #define TOUT_LOOKUP     60
 150
 151 static int
 152 service_timeout(struct service *s)
 153 {
 154         time_t t = time(NULL);
 155
 156         if (t - s->t <= TOUT_LOOKUP)
 157                 return 0;
 158
 159         s->t = t;
 160
 161         return 1;
 162 }
 163
 164 void
 165 service_reply_a(struct uloop_fd *u, int type)
 166 {
 167         if (type != TYPE_A)
 168                 return;
 169
 170         dns_init_answer();
 171         service_send_a(u);
 172         dns_send_answer(u, service_name("local"));
 173 }
 174
 175 void
 176 service_reply(struct uloop_fd *u, char *match)
 177 {
 178         struct service *s;
 179
 180         avl_for_each_element(&services, s, avl) {
 181                 char *host = service_name(s->service);
 182                 char *service = strstr(host, "._");
 183
 184                 if (!s->active || !service || !service_timeout(s))
 185                         continue;
 186
 187                 service++;
 188
 189                 if (match && strcmp(match, s->service))
 190                         continue;
 191
 192                 dns_init_answer();
 193                 service_send_ptr(u, s);
 194                 dns_send_answer(u, service);
 195
 196                 dns_init_answer();
 197                 service_send_srv(u, s);
 198                 if (s->txt && s->txt_len)
 199                         dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len);
 200                 dns_send_answer(u, host);
 201         }
 202
 203         if (match)
 204                 return;
 205
 206         dns_init_answer();
 207         service_send_a(u);
 208         dns_send_answer(u, service_name("local"));
 209 }
 210
 211 void
 212 service_announce_services(struct uloop_fd *u, char *service)
 213 {
 214         struct service *s;
 215         int tcp = 1;
 216
 217         if (!strcmp(service, sdudp))
 218                 tcp = 0;
 219         else if (strcmp(service, sdtcp))
 220                 return;
 221
 222         avl_for_each_element(&services, s, avl) {
 223                 if (!strstr(s->service, "._tcp") && tcp)
 224                         continue;
 225                 if (!strstr(s->service, "._udp") && !tcp)
 226                         continue;
 227                 s->t = 0;
 228                 dns_init_answer();
 229                 service_send_ptr_c(u, s->service);
 230                 if (tcp)
 231                         dns_send_answer(u, sdtcp);
 232                 else
 233                         dns_send_answer(u, sdudp);
 234                 service_reply(u, s->service);
 235         }
 236 }
 237
 238 void
 239 service_announce(struct uloop_fd *u)
 240 {
 241         service_announce_services(u, sdudp);
 242         service_announce_services(u, sdtcp);
 243 }
 244
 245 static void
 246 service_load(char *path)
 247 {
 248         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 249         int rem, i;
 250         glob_t gl;
 251
 252         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 253                 return;
 254
 255         for (i = 0; i < gl.gl_pathc; i++) {
 256                 blob_buf_init(&b, 0);
 257
 258                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 259                         continue;
 260                 blob_for_each_attr(cur, b.head, rem) {
 261                         struct service *s;
 262                         char *d_service, *d_daemon;
 263                         uint8_t *d_txt;
 264                         int rem2;
 265                         int txt_len = 0;
 266
 267                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 268                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 269                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_TXT])
 270                                 continue;
 271
 272                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 273                                 txt_len += 1 + strlen(blobmsg_get_string(txt));
 274
 275                         s = calloc_a(sizeof(*s),
 276                                 &d_daemon, strlen(gl.gl_pathv[i]) + 1,
 277                                 &d_service, strlen(blobmsg_name(cur)) + 1,
 278                                 &d_txt, txt_len);
 279                         if (!s)
 280                                 continue;
 281
 282                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 283                         s->service = d_service;
 284                         s->daemon = d_daemon;
 285                         strcpy(s->service, blobmsg_name(cur));
 286                         strcpy(s->daemon, gl.gl_pathv[i]);
 287                         s->avl.key = s->service;
 288                         s->active = 1;
 289                         s->t = 0;
 290                         s->txt_len = txt_len;
 291                         s->txt = d_txt;
 292                         avl_insert(&services, &s->avl);
 293
 294                         if (!s->txt_len)
 295                                 continue;
 296
 297                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 298                                 int len = strlen(blobmsg_get_string(txt));
 299                                 if (!len)
 300                                         continue;
 301                                 if (len > 0xff)
 302                                         len = 0xff;
 303                                 *d_txt = len;
 304                                 d_txt++;
 305                                 memcpy(d_txt, blobmsg_get_string(txt), len);
 306                                 d_txt += len;
 307                         }
 308                 }
 309         }
 310 }
 311
 312 void
 313 service_init(void)
 314 {
 315         if (!hostname)
 316                 hostname = get_hostname();
 317         avl_init(&services, avl_strcmp, true, NULL);
 318         service_load("/tmp/run/mdnsd/*");
 319 }
 320
 321 void
 322 service_cleanup(void)
 323 {
 324 }