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_add_srv(struct service *s)
  99 {
 100         unsigned char buffer[MAX_NAME_LEN];
 101         struct dns_srv_data *sd;
 102         char *host = service_name("local");
 103         int len = dn_comp(host, buffer, MAX_NAME_LEN, NULL, NULL);
 104
 105         if (len < 1)
 106                 return;
 107
 108         sd = calloc(1, len + sizeof(struct dns_srv_data));
 109         if (!sd)
 110                 return;
 111
 112         sd->port = cpu_to_be16(s->port);
 113         memcpy(&sd[1], buffer, len);
 114         host = service_name(s->service);
 115         dns_add_answer(TYPE_SRV, (uint8_t *) sd, len + sizeof(struct dns_srv_data));
 116         free(sd);
 117 }
 118
 119 #define TOUT_LOOKUP     60
 120
 121 static int
 122 service_timeout(struct service *s)
 123 {
 124         time_t t = time(NULL);
 125
 126         if (t - s->t <= TOUT_LOOKUP)
 127                 return 0;
 128
 129         s->t = t;
 130
 131         return 1;
 132 }
 133
 134 void
 135 service_reply_a(struct interface *iface, int type)
 136 {
 137         if (type != TYPE_A)
 138                 return;
 139
 140         dns_init_answer();
 141         dns_add_answer(TYPE_A, (uint8_t *) &iface->v4_addr.s_addr, 4);
 142         dns_send_answer(iface, service_name("local"));
 143 }
 144
 145 void
 146 service_reply(struct interface *iface, const char *match)
 147 {
 148         struct service *s;
 149
 150         vlist_for_each_element(&services, s, node) {
 151                 char *host = service_name(s->service);
 152                 char *service = strstr(host, "._");
 153
 154                 if (!s->active || !service || !service_timeout(s))
 155                         continue;
 156
 157                 service++;
 158
 159                 if (match && strcmp(match, s->service))
 160                         continue;
 161
 162                 dns_init_answer();
 163                 service_add_ptr(service_name(s->service));
 164                 dns_send_answer(iface, service);
 165
 166                 dns_init_answer();
 167                 service_add_srv(s);
 168                 if (s->txt && s->txt_len)
 169                         dns_add_answer(TYPE_TXT, (uint8_t *) s->txt, s->txt_len);
 170                 dns_send_answer(iface, host);
 171         }
 172
 173         if (match)
 174                 return;
 175
 176         service_reply_a(iface, TYPE_A);
 177 }
 178
 179 void
 180 service_announce_services(struct interface *iface, const char *service)
 181 {
 182         struct service *s;
 183         int tcp = 1;
 184
 185         if (!strcmp(service, sdudp))
 186                 tcp = 0;
 187         else if (strcmp(service, sdtcp))
 188                 return;
 189
 190         vlist_for_each_element(&services, s, node) {
 191                 if (!strstr(s->service, "._tcp") && tcp)
 192                         continue;
 193                 if (!strstr(s->service, "._udp") && !tcp)
 194                         continue;
 195                 s->t = 0;
 196                 dns_init_answer();
 197                 service_add_ptr(s->service);
 198                 if (tcp)
 199                         dns_send_answer(iface, sdtcp);
 200                 else
 201                         dns_send_answer(iface, sdudp);
 202                 service_reply(iface, s->service);
 203         }
 204 }
 205
 206 void
 207 service_announce(struct interface *iface)
 208 {
 209         service_announce_services(iface, sdudp);
 210         service_announce_services(iface, sdtcp);
 211 }
 212
 213 static void
 214 service_update(struct vlist_tree *tree, struct vlist_node *node_new,
 215                struct vlist_node *node_old)
 216 {
 217         struct service *s;
 218
 219         if (!node_old)
 220                 return;
 221
 222         s = container_of(node_old, struct service, node);
 223         free(s);
 224 }
 225
 226 static void
 227 service_load(char *path)
 228 {
 229         struct blob_attr *txt, *cur, *_tb[__SERVICE_MAX];
 230         int rem, i;
 231         glob_t gl;
 232
 233         if (glob(path, GLOB_NOESCAPE | GLOB_MARK, NULL, &gl))
 234                 return;
 235
 236         for (i = 0; i < gl.gl_pathc; i++) {
 237                 blob_buf_init(&b, 0);
 238
 239                 if (!blobmsg_add_json_from_file(&b, gl.gl_pathv[i]))
 240                         continue;
 241                 blob_for_each_attr(cur, b.head, rem) {
 242                         struct service *s;
 243                         char *d_service, *d_daemon;
 244                         uint8_t *d_txt;
 245                         int rem2;
 246                         int txt_len = 0;
 247
 248                         blobmsg_parse(service_policy, ARRAY_SIZE(service_policy),
 249                                 _tb, blobmsg_data(cur), blobmsg_data_len(cur));
 250                         if (!_tb[SERVICE_PORT] || !_tb[SERVICE_TXT])
 251                                 continue;
 252
 253                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2)
 254                                 txt_len += 1 + strlen(blobmsg_get_string(txt));
 255
 256                         s = calloc_a(sizeof(*s),
 257                                 &d_daemon, strlen(gl.gl_pathv[i]) + 1,
 258                                 &d_service, strlen(blobmsg_name(cur)) + 1,
 259                                 &d_txt, txt_len);
 260                         if (!s)
 261                                 continue;
 262
 263                         s->port = blobmsg_get_u32(_tb[SERVICE_PORT]);
 264                         s->service = strcpy(d_service, blobmsg_name(cur));
 265                         s->daemon = strcpy(d_daemon, gl.gl_pathv[i]);
 266                         s->active = 1;
 267                         s->t = 0;
 268                         s->txt_len = txt_len;
 269                         s->txt = d_txt;
 270
 271                         blobmsg_for_each_attr(txt, _tb[SERVICE_TXT], rem2) {
 272                                 int len = strlen(blobmsg_get_string(txt));
 273                                 if (!len)
 274                                         continue;
 275                                 if (len > 0xff)
 276                                         len = 0xff;
 277                                 *d_txt = len;
 278                                 d_txt++;
 279                                 memcpy(d_txt, blobmsg_get_string(txt), len);
 280                                 d_txt += len;
 281                         }
 282
 283                         vlist_add(&services, &s->node, s->service);
 284                 }
 285         }
 286 }
 287
 288 void
 289 service_init(void)
 290 {
 291         if (!hostname)
 292                 hostname = get_hostname();
 293
 294         vlist_update(&services);
 295         service_load("/tmp/run/mdnsd/*");
 296         vlist_flush(&services);
 297 }
 298
 299 void
 300 service_cleanup(void)
 301 {
 302         vlist_flush(&services);
 303         blob_buf_free(&b);
 304 }