libpurple/stun.c

   1 /**
   2  * @file stun.c STUN (RFC3489) Implementation
   3  * @ingroup core
   4  */
   5
   6 /* purple
   7  *
   8  * STUN implementation inspired by jstun [http://jstun.javawi.de/]
   9  *
  10  * Purple is the legal property of its developers, whose names are too numerous
  11  * to list here.  Please refer to the COPYRIGHT file distributed with this
  12  * source distribution.
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, write to the Free Software
  26  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
  27  *
  28  */
  29
  30 #include "internal.h"
  31
  32 #ifndef _WIN32
  33 #include <net/if.h>
  34 #include <sys/ioctl.h>
  35 #endif
  36
  37 /* Solaris */
  38 #if defined (__SVR4) && defined (__sun)
  39 #include <sys/sockio.h>
  40 #endif
  41
  42 #include "debug.h"
  43 #include "account.h"
  44 #include "dnsquery.h"
  45 #include "dnssrv.h"
  46 #include "network.h"
  47 #include "proxy.h"
  48 #include "stun.h"
  49 #include "prefs.h"
  50
  51 #define MSGTYPE_BINDINGREQUEST 0x0001
  52 #define MSGTYPE_BINDINGRESPONSE 0x0101
  53
  54 #define ATTRIB_MAPPEDADDRESS 0x0001
  55
  56 struct stun_header {
  57         guint16 type;
  58         guint16 len;
  59         guint32 transid[4];
  60 };
  61
  62 struct stun_attrib {
  63         guint16 type;
  64         guint16 len;
  65 };
  66
  67 #ifdef NOTYET
  68 struct stun_change {
  69         struct stun_header hdr;
  70         struct stun_attrib attrib;
  71         char value[4];
  72 };
  73 #endif
  74
  75 struct stun_conn {
  76         int fd;
  77         struct sockaddr_in addr;
  78         int test;
  79         int retry;
  80         guint incb;
  81         guint timeout;
  82         struct stun_header *packet;
  83         size_t packetsize;
  84 };
  85
  86 static PurpleStunNatDiscovery nattype = {
  87         PURPLE_STUN_STATUS_UNDISCOVERED,
  88         PURPLE_STUN_NAT_TYPE_PUBLIC_IP,
  89         "\0", NULL, 0};
  90
  91 static GSList *callbacks = NULL;
  92
  93 static void close_stun_conn(struct stun_conn *sc) {
  94
  95         if (sc->incb)
  96                 purple_input_remove(sc->incb);
  97
  98         if (sc->timeout)
  99                 purple_timeout_remove(sc->timeout);
 100
 101         if (sc->fd)
 102                 close(sc->fd);
 103
 104         g_free(sc);
 105 }
 106
 107 static void do_callbacks(void) {
 108         while (callbacks) {
 109                 StunCallback cb = callbacks->data;
 110                 if (cb)
 111                         cb(&nattype);
 112                 callbacks = g_slist_delete_link(callbacks, callbacks);
 113         }
 114 }
 115
 116 static gboolean timeoutfunc(gpointer data) {
 117         struct stun_conn *sc = data;
 118         if(sc->retry >= 2) {
 119                 purple_debug_warning("stun", "request timed out, giving up.\n");
 120                 if(sc->test == 2)
 121                         nattype.type = PURPLE_STUN_NAT_TYPE_SYMMETRIC;
 122
 123                 /* set unknown */
 124                 nattype.status = PURPLE_STUN_STATUS_UNKNOWN;
 125
 126                 nattype.lookup_time = time(NULL);
 127
 128                 /* callbacks */
 129                 do_callbacks();
 130
 131                 /* we don't need to remove the timeout (returning FALSE) */
 132                 sc->timeout = 0;
 133                 close_stun_conn(sc);
 134
 135                 return FALSE;
 136         }
 137         purple_debug_info("stun", "request timed out, retrying.\n");
 138         sc->retry++;
 139         sendto(sc->fd, sc->packet, sc->packetsize, 0,
 140                 (struct sockaddr *)&(sc->addr), sizeof(struct sockaddr_in));
 141         return TRUE;
 142 }
 143
 144 #ifdef NOTYET
 145 static void do_test2(struct stun_conn *sc) {
 146         struct stun_change data;
 147         data.hdr.type = htons(0x0001);
 148         data.hdr.len = 0;
 149         data.hdr.transid[0] = rand();
 150         data.hdr.transid[1] = ntohl(((int)'g' << 24) + ((int)'a' << 16) + ((int)'i' << 8) + (int)'m');
 151         data.hdr.transid[2] = rand();
 152         data.hdr.transid[3] = rand();
 153         data.attrib.type = htons(0x003);
 154         data.attrib.len = htons(4);
 155         data.value[3] = 6;
 156         sc->packet = (struct stun_header*)&data;
 157         sc->packetsize = sizeof(struct stun_change);
 158         sc->retry = 0;
 159         sc->test = 2;
 160         sendto(sc->fd, sc->packet, sc->packetsize, 0, (struct sockaddr *)&(sc->addr), sizeof(struct sockaddr_in));
 161         sc->timeout = purple_timeout_add(500, (GSourceFunc) timeoutfunc, sc);
 162 }
 163 #endif
 164
 165 static void reply_cb(gpointer data, gint source, PurpleInputCondition cond) {
 166         struct stun_conn *sc = data;
 167         char buffer[65536];
 168         char *tmp;
 169         int len;
 170         struct in_addr in;
 171         struct stun_attrib *attrib;
 172         struct stun_header *hdr;
 173         struct ifconf ifc;
 174         struct ifreq *ifr;
 175         struct sockaddr_in *sinptr;
 176
 177         len = recv(source, buffer, sizeof(buffer) - 1, 0);
 178         if (!len) {
 179                 purple_debug_warning("stun", "unable to read stun response\n");
 180                 return;
 181         }
 182         buffer[len] = '\0';
 183
 184         if (len < sizeof(struct stun_header)) {
 185                 purple_debug_warning("stun", "got invalid response\n");
 186                 return;
 187         }
 188
 189         hdr = (struct stun_header*) buffer;
 190         if (len != (ntohs(hdr->len) + sizeof(struct stun_header))) {
 191                 purple_debug_warning("stun", "got incomplete response\n");
 192                 return;
 193         }
 194
 195         /* wrong transaction */
 196         if(hdr->transid[0] != sc->packet->transid[0]
 197                         || hdr->transid[1] != sc->packet->transid[1]
 198                         || hdr->transid[2] != sc->packet->transid[2]
 199                         || hdr->transid[3] != sc->packet->transid[3]) {
 200                 purple_debug_warning("stun", "got wrong transid\n");
 201                 return;
 202         }
 203
 204         if(sc->test==1) {
 205                 if (hdr->type != MSGTYPE_BINDINGRESPONSE) {
 206                         purple_debug_warning("stun",
 207                                 "Expected Binding Response, got %d\n",
 208                                 hdr->type);
 209                         return;
 210                 }
 211
 212                 tmp = buffer + sizeof(struct stun_header);
 213                 while((buffer + len) > (tmp + sizeof(struct stun_attrib))) {
 214                         attrib = (struct stun_attrib*) tmp;
 215                         tmp += sizeof(struct stun_attrib);
 216
 217                         if (!((buffer + len) > (tmp + ntohs(attrib->len))))
 218                                 break;
 219
 220                         if(attrib->type == htons(ATTRIB_MAPPEDADDRESS)
 221                                         && ntohs(attrib->len) == 8) {
 222                                 char *ip;
 223                                 /* Skip the first unused byte,
 224                                  * the family(1 byte), and the port(2 bytes);
 225                                  * then read the 4 byte IPv4 address */
 226                                 memcpy(&in.s_addr, tmp + 4, 4);
 227                                 ip = inet_ntoa(in);
 228                                 if(ip)
 229                                         g_strlcpy(nattype.publicip, ip, sizeof(nattype.publicip));
 230                         }
 231
 232                         tmp += ntohs(attrib->len);
 233                 }
 234                 purple_debug_info("stun", "got public ip %s\n", nattype.publicip);
 235                 nattype.status = PURPLE_STUN_STATUS_DISCOVERED;
 236                 nattype.type = PURPLE_STUN_NAT_TYPE_UNKNOWN_NAT;
 237                 nattype.lookup_time = time(NULL);
 238
 239                 /* is it a NAT? */
 240
 241                 ifc.ifc_len = sizeof(buffer);
 242                 ifc.ifc_req = (struct ifreq *) buffer;
 243                 ioctl(source, SIOCGIFCONF, &ifc);
 244
 245                 tmp = buffer;
 246                 while(tmp < buffer + ifc.ifc_len) {
 247                         ifr = (struct ifreq *) tmp;
 248
 249                         tmp += sizeof(struct ifreq);
 250
 251                         if(ifr->ifr_addr.sa_family == AF_INET) {
 252                                 /* we only care about ipv4 interfaces */
 253                                 sinptr = (struct sockaddr_in *) &ifr->ifr_addr;
 254                                 if(sinptr->sin_addr.s_addr == in.s_addr) {
 255                                         /* no NAT */
 256                                         purple_debug_info("stun", "no nat\n");
 257                                         nattype.type = PURPLE_STUN_NAT_TYPE_PUBLIC_IP;
 258                                 }
 259                         }
 260                 }
 261
 262 #ifndef NOTYET
 263                 close_stun_conn(sc);
 264                 do_callbacks();
 265 #else
 266                 purple_timeout_remove(sc->timeout);
 267                 sc->timeout = 0;
 268
 269                 do_test2(sc);
 270         } else if(sc->test == 2) {
 271                 close_stun_conn(sc);
 272                 nattype.type = PURPLE_STUN_NAT_TYPE_FULL_CONE;
 273                 do_callbacks();
 274 #endif
 275         }
 276 }
 277
 278
 279 static void hbn_listen_cb(int fd, gpointer data) {
 280         GSList *hosts = data;
 281         struct stun_conn *sc;
 282         static struct stun_header hdr_data;
 283
 284         if(fd < 0) {
 285                 nattype.status = PURPLE_STUN_STATUS_UNKNOWN;
 286                 nattype.lookup_time = time(NULL);
 287                 do_callbacks();
 288                 return;
 289         }
 290
 291         sc = g_new0(struct stun_conn, 1);
 292         sc->fd = fd;
 293
 294         sc->addr.sin_family = AF_INET;
 295         sc->addr.sin_port = htons(purple_network_get_port_from_fd(fd));
 296         sc->addr.sin_addr.s_addr = INADDR_ANY;
 297
 298         sc->incb = purple_input_add(fd, PURPLE_INPUT_READ, reply_cb, sc);
 299
 300         hosts = g_slist_delete_link(hosts, hosts);
 301         memcpy(&(sc->addr), hosts->data, sizeof(struct sockaddr_in));
 302         g_free(hosts->data);
 303         hosts = g_slist_delete_link(hosts, hosts);
 304         while (hosts) {
 305                 hosts = g_slist_delete_link(hosts, hosts);
 306                 g_free(hosts->data);
 307                 hosts = g_slist_delete_link(hosts, hosts);
 308         }
 309
 310         hdr_data.type = htons(MSGTYPE_BINDINGREQUEST);
 311         hdr_data.len = 0;
 312         hdr_data.transid[0] = rand();
 313         hdr_data.transid[1] = ntohl(((int)'g' << 24) + ((int)'a' << 16) + ((int)'i' << 8) + (int)'m');
 314         hdr_data.transid[2] = rand();
 315         hdr_data.transid[3] = rand();
 316
 317         if(sendto(sc->fd, &hdr_data, sizeof(struct stun_header), 0,
 318                         (struct sockaddr *)&(sc->addr),
 319                         sizeof(struct sockaddr_in)) < sizeof(struct stun_header)) {
 320                 nattype.status = PURPLE_STUN_STATUS_UNKNOWN;
 321                 nattype.lookup_time = time(NULL);
 322                 do_callbacks();
 323                 close_stun_conn(sc);
 324                 return;
 325         }
 326         sc->test = 1;
 327         sc->packet = &hdr_data;
 328         sc->packetsize = sizeof(struct stun_header);
 329         sc->timeout = purple_timeout_add(500, (GSourceFunc) timeoutfunc, sc);
 330 }
 331
 332 static void hbn_cb(GSList *hosts, gpointer data, const char *error_message) {
 333
 334         if(!hosts || !hosts->data) {
 335                 nattype.status = PURPLE_STUN_STATUS_UNDISCOVERED;
 336                 nattype.lookup_time = time(NULL);
 337                 do_callbacks();
 338                 return;
 339         }
 340
 341         if (!purple_network_listen_range(12108, 12208, SOCK_DGRAM, hbn_listen_cb, hosts)) {
 342                 while (hosts) {
 343                         hosts = g_slist_delete_link(hosts, hosts);
 344                         g_free(hosts->data);
 345                         hosts = g_slist_delete_link(hosts, hosts);
 346                 }
 347
 348                 nattype.status = PURPLE_STUN_STATUS_UNKNOWN;
 349                 nattype.lookup_time = time(NULL);
 350                 do_callbacks();
 351                 return;
 352         }
 353
 354
 355 }
 356
 357 static void do_test1(PurpleSrvResponse *resp, int results, gpointer sdata) {
 358         const char *servername = sdata;
 359         int port = 3478;
 360
 361         if(results) {
 362                 servername = resp[0].hostname;
 363                 port = resp[0].port;
 364         }
 365         purple_debug_info("stun", "got %d SRV responses, server: %s, port: %d\n",
 366                 results, servername, port);
 367
 368         purple_dnsquery_a_account(NULL, servername, port, hbn_cb, NULL);
 369         g_free(resp);
 370 }
 371
 372 static gboolean call_callback(gpointer data) {
 373         StunCallback cb = data;
 374         cb(&nattype);
 375         return FALSE;
 376 }
 377
 378 PurpleStunNatDiscovery *purple_stun_discover(StunCallback cb) {
 379         const char *servername = purple_prefs_get_string("/purple/network/stun_server");
 380
 381         purple_debug_info("stun", "using server %s\n", servername);
 382
 383         if(nattype.status == PURPLE_STUN_STATUS_DISCOVERING) {
 384                 if(cb)
 385                         callbacks = g_slist_append(callbacks, cb);
 386                 return &nattype;
 387         }
 388
 389         if(nattype.status != PURPLE_STUN_STATUS_UNDISCOVERED) {
 390                 gboolean use_cached_result = TRUE;
 391
 392                 /** Deal with the server name having changed since we did the
 393                     lookup */
 394                 if (servername && strlen(servername) > 1
 395                                 && !purple_strequal(servername, nattype.servername)) {
 396                         use_cached_result = FALSE;
 397                 }
 398
 399                 /* If we don't have a successful status and it has been 5
 400                    minutes since we last did a lookup, redo the lookup */
 401                 if (nattype.status != PURPLE_STUN_STATUS_DISCOVERED
 402                                 && (time(NULL) - nattype.lookup_time) > 300) {
 403                         use_cached_result = FALSE;
 404                 }
 405
 406                 if (use_cached_result) {
 407                         if(cb)
 408                                 purple_timeout_add(10, call_callback, cb);
 409                         return &nattype;
 410                 }
 411         }
 412
 413         if(!servername || (strlen(servername) < 2)) {
 414                 nattype.status = PURPLE_STUN_STATUS_UNKNOWN;
 415                 nattype.lookup_time = time(NULL);
 416                 if(cb)
 417                         purple_timeout_add(10, call_callback, cb);
 418                 return &nattype;
 419         }
 420
 421         nattype.status = PURPLE_STUN_STATUS_DISCOVERING;
 422         nattype.publicip[0] = '\0';
 423         g_free(nattype.servername);
 424         nattype.servername = g_strdup(servername);
 425
 426         callbacks = g_slist_append(callbacks, cb);
 427         purple_srv_resolve_account(NULL, "stun", "udp", servername, do_test1,
 428                 (gpointer) servername);
 429
 430         return &nattype;
 431 }
 432
 433 void purple_stun_init() {
 434         purple_prefs_add_string("/purple/network/stun_server", "");
 435 }