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 <uci.h>
  24 #include <uci_blob.h>
  25
  26 #include <libubox/vlist.h>
  27 #include <libubox/uloop.h>
  28 #include <libubox/avl-cmp.h>
  29 #include <libubox/blobmsg_json.h>
  30
  31 #include "dns.h"
  32 #include "service.h"
  33 #include "util.h"
  34 #include "interface.h"
  35
  36 enum {
  37         SERVICE_PORT,
  38         SERVICE_TXT,
  39         __SERVICE_MAX,
  40 };
  41
  42 struct service {
  43         struct vlist_node node;
  44
  45         time_t t;
  46
  47         const char *service;
  48         const char *daemon;
  49         const uint8_t *txt;
  50         int txt_len;
  51         int port;
  52         int active;
  53 };
  54
  55 static const struct blobmsg_policy service_policy[__SERVICE_MAX] = {
  56         [SERVICE_PORT] = { .name = "port", .type = BLOBMSG_TYPE_INT32 },
  57         [SERVICE_TXT] = { .name = "txt", .type = BLOBMSG_TYPE_ARRAY },
  58 };
  59
  60 static const struct uci_blob_param_list service_attr_list = {
  61         .n_params = __SERVICE_MAX,
  62         .params = service_policy,
  63 };
  64
  65 static void
  66 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
  67                struct vlist_node *node_old);
  68
  69 static struct blob_buf b;
  70 static VLIST_TREE(services, avl_strcmp, service_update, false, false);
  71 char *hostname = NULL;
  72 static char *sdudp =  "_services._dns-sd._udp.local";
  73 static char *sdtcp =  "_services._dns-sd._tcp.local";
  74
  75 char *
  76 service_name(const char *domain)
  77 {
  78         static char buffer[256];
  79
  80         snprintf(buffer, sizeof(buffer), "%s.%s", hostname, domain);
  81
  82         return buffer;
  83 }
  84
  85 static void
  86 service_add_ptr(const char *host)
  87 {
  88         unsigned char buffer[MAX_NAME_LEN];
  89         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
  90
  91         if (len < 1)
  92                 return;
  93
  94         dns_add_answer(TYPE_PTR, buffer, len);
  95 }
  96
  97 static void
  98 service_send_a(struct interface *iface)
  99 {
 100         unsigned char buffer[MAX_NAME_LEN];
 101         char *host = service_name("local");
 102         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 103
 104         if (len < 1)
 105                 return;
 106
 107         dns_add_answer(TYPE_A, (uint8_t *) &iface->v4_addr.s_addr, 4);
 108 }
 109
 110 static void
 111 service_add_srv(struct service *s)
 112 {
 113         unsigned char buffer[MAX_NAME_LEN];
 114         struct dns_srv_data *sd;
 115         char *host = service_name("local");
 116         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 117
 118         if (len < 1)
 119                 return;
 120
 121         sd = calloc(1, len + sizeof(struct dns_srv_data));
 122         if (!sd)
 123                 return;
 124
 125         sd->port = cpu_to_be16(s->port);
 126         memcpy(&sd[1], buffer, len);
 127         host = service_name(s->service);
 128         dns_add_answer(TYPE_SRV, (uint8_t *) sd, len + sizeof(struct dns_srv_data));
 129         free(sd);
 130 }
 131
 132 #define TOUT_LOOKUP     60
 133
 134 static int
 135 service_timeout(struct service *s)
 136 {
 137         time_t t = time(NULL);
 138
 139         if (t - s->t <= TOUT_LOOKUP)
 140                 return 0;
 141
 142         s->t = t;
 143
 144         return 1;
 145 }
 146
 147 void
 148 service_reply_a(struct interface *iface, int type)
 149 {
 150         if (type != TYPE_A)
 151                 return;
 152
 153         dns_init_answer();
 154         service_send_a(iface);
 155         dns_send_answer(iface, service_name("local"));
 156 }
 157
 158 void
 159 service_reply(struct interface *iface, const char *match)
 160 {
 161         struct service *s;
 162
 163         vlist_for_each_element(&services, s, node) {
 164                 char *host = service_name(s->service);
 165                 char *service = strstr(host, "._");
 166
 167                 if (!s->active || !service || !service_timeout(s))
 168                         continue;
 169
 170                 service++;
 171
 172                 if (match && strcmp(match, s->service))
 173                         continue;
 174
 175                 dns_init_answer();
 176                 service_add_ptr(service_name(s->service));
 177                 dns_send_answer(iface, service);
 178
 179                 dns_init_answer();
 180                 service_add_srv(s);
 181                 if (s->txt && s->txt_len)
 182                         dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len);
 183                 dns_send_answer(iface, host);
 184         }
 185
 186         if (match)
 187                 return;
 188
 189         dns_init_answer();
 190         service_send_a(iface);
 191         dns_send_answer(iface, service_name("local"));
 192 }
 193
 194 void
 195 service_announce_services(struct interface *iface, const char *service)
 196 {
 197         struct service *s;
 198         int tcp = 1;
 199
 200         if (!strcmp(service, sdudp))
 201                 tcp = 0;
 202         else if (strcmp(service, sdtcp))
 203                 return;
 204
 205         vlist_for_each_element(&services, s, node) {
 206                 if (!strstr(s->service, "._tcp") && tcp)
 207                         continue;
 208                 if (!strstr(s->service, "._udp") && !tcp)
 209                         continue;
 210                 s->t = 0;
 211                 dns_init_answer();
 212                 service_add_ptr(s->service);
 213                 if (tcp)
 214                         dns_send_answer(iface, sdtcp);
 215                 else
 216                         dns_send_answer(iface, sdudp);
 217                 service_reply(iface, s->service);
 218         }
 219 }
 220
 221 void
 222 service_announce(struct interface *iface)
 223 {
 224         service_announce_services(iface, sdudp);
 225         service_announce_services(iface, sdtcp);
 226 }
 227
 228 static void
 229 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 230                struct vlist_node *node_old)
 231 {
 232         struct service *s;
 233
 234         if (!node_old)
 235                 return;
 236
 237         s = container_of(node_old, struct service, node);
 238         free(s);
 239 }
 240
 241 static void
 242 service_load(char *path)
 243 {
 244         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 245         int rem, i;
 246         glob_t gl;
 247
 248         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 249                 return;
 250
 251         for (i = 0; i < gl.gl_pathc; i++) {
 252                 blob_buf_init(&b, 0);
 253
 254                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 255                         continue;
 256                 blob_for_each_attr(cur, b.head, rem) {
 257                         struct service *s;
 258                         char *d_service, *d_daemon;
 259                         uint8_t *d_txt;
 260                         int rem2;
 261                         int txt_len = 0;
 262
 263                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 264                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 265                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_TXT])
 266                                 continue;
 267
 268                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 269                                 txt_len += 1 + strlen(blobmsg_get_string(txt));
 270
 271                         s = calloc_a(sizeof(*s),
 272                                 &d_daemon, strlen(gl.gl_pathv[i]) + 1,
 273                                 &d_service, strlen(blobmsg_name(cur)) + 1,
 274                                 &d_txt, txt_len);
 275                         if (!s)
 276                                 continue;
 277
 278                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 279                         s->service = strcpy(d_service, blobmsg_name(cur));
 280                         s->daemon = strcpy(d_daemon, gl.gl_pathv[i]);
 281                         s->active = 1;
 282                         s->t = 0;
 283                         s->txt_len = txt_len;
 284                         s->txt = d_txt;
 285
 286                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 287                                 int len = strlen(blobmsg_get_string(txt));
 288                                 if (!len)
 289                                         continue;
 290                                 if (len > 0xff)
 291                                         len = 0xff;
 292                                 *d_txt = len;
 293                                 d_txt++;
 294                                 memcpy(d_txt, blobmsg_get_string(txt), len);
 295                                 d_txt += len;
 296                         }
 297
 298                         vlist_add(&services, &s->node, s->service);
 299                 }
 300         }
 301 }
 302
 303 void
 304 service_init(void)
 305 {
 306         if (!hostname)
 307                 hostname = get_hostname();
 308
 309         vlist_update(&services);
 310         service_load("/tmp/run/mdnsd/*");
 311         vlist_flush(&services);
 312 }
 313
 314 void
 315 service_cleanup(void)
 316 {
 317         vlist_flush(&services);
 318         blob_buf_free(&b);
 319 }