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3 Copyright (C) 2007-2017 GNUnet e.V.
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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17 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 Boston, MA 02110-1301, USA.
22 * @author Christian Grothoff
23 * @author Milan Bouchet-Valat
26 * Service for handling UPnP and NAT-PMP port forwarding
27 * and external IP address retrieval
30 #include "gnunet_nat_service.h"
36 * Entry in DLL of addresses of this peer.
44 struct AddrEntry *next;
49 struct AddrEntry *prev;
52 * Address class of the address.
54 enum GNUNET_NAT_AddressClass ac;
57 * Number of bytes that follow.
64 * Handle for active NAT registrations.
66 struct GNUNET_NAT_Handle
70 * Configuration we use.
72 const struct GNUNET_CONFIGURATION_Handle *cfg;
75 * Message queue for communicating with the NAT service.
77 struct GNUNET_MQ_Handle *mq;
80 * Our registration message.
82 struct GNUNET_MessageHeader *reg;
85 * Head of address DLL.
87 struct AddrEntry *ae_head;
90 * Tail of address DLL.
92 struct AddrEntry *ae_tail;
95 * Function to call when our addresses change.
97 GNUNET_NAT_AddressCallback address_callback;
100 * Function to call when another peer requests connection reversal.
102 GNUNET_NAT_ReversalCallback reversal_callback;
105 * Closure for the various callbacks.
110 * Task scheduled to reconnect to the service.
112 struct GNUNET_SCHEDULER_Task *reconnect_task;
115 * How long to wait until we reconnect.
117 struct GNUNET_TIME_Relative reconnect_delay;
122 * Task to connect to the NAT service.
124 * @param cls our `struct GNUNET_NAT_Handle *`
127 do_connect (void *cls);
131 * Task to connect to the NAT service.
133 * @param nh handle to reconnect
136 reconnect (struct GNUNET_NAT_Handle *nh)
138 struct AddrEntry *ae;
142 GNUNET_MQ_destroy (nh->mq);
145 while (NULL != (ae = nh->ae_head))
147 GNUNET_CONTAINER_DLL_remove (nh->ae_head,
150 nh->address_callback (nh->callback_cls,
153 (const struct sockaddr *) &ae[1],
158 = GNUNET_TIME_STD_BACKOFF (nh->reconnect_delay);
160 = GNUNET_SCHEDULER_add_delayed (nh->reconnect_delay,
167 * Check connection reversal request.
169 * @param cls our `struct GNUNET_NAT_Handle`
170 * @param crm the message
171 * @return #GNUNET_OK if @a crm is well-formed
174 check_connection_reversal_request (void *cls,
175 const struct GNUNET_NAT_ConnectionReversalRequestedMessage *crm)
177 if (ntohs (crm->header.size) !=
179 sizeof (struct sockaddr_in) )
182 return GNUNET_SYSERR;
189 * Handle connection reversal request.
191 * @param cls our `struct GNUNET_NAT_Handle`
192 * @param crm the message
195 handle_connection_reversal_request (void *cls,
196 const struct GNUNET_NAT_ConnectionReversalRequestedMessage *crm)
198 struct GNUNET_NAT_Handle *nh = cls;
200 nh->reversal_callback (nh->callback_cls,
201 (const struct sockaddr *) &crm[1],
202 sizeof (struct sockaddr_in));
207 * Check address change notification.
209 * @param cls our `struct GNUNET_NAT_Handle`
210 * @param acn the message
211 * @return #GNUNET_OK if @a crm is well-formed
214 check_address_change_notification (void *cls,
215 const struct GNUNET_NAT_AddressChangeNotificationMessage *acn)
217 size_t alen = ntohs (acn->header.size) - sizeof (*acn);
221 case sizeof (struct sockaddr_in):
223 const struct sockaddr_in *s4
224 = (const struct sockaddr_in *) &acn[1];
225 if (AF_INET != s4->sin_family)
228 return GNUNET_SYSERR;
232 case sizeof (struct sockaddr_in6):
234 const struct sockaddr_in6 *s6
235 = (const struct sockaddr_in6 *) &acn[1];
236 if (AF_INET6 != s6->sin6_family)
239 return GNUNET_SYSERR;
245 return GNUNET_SYSERR;
252 * Handle connection reversal request.
254 * @param cls our `struct GNUNET_NAT_Handle`
255 * @param acn the message
258 handle_address_change_notification (void *cls,
259 const struct GNUNET_NAT_AddressChangeNotificationMessage *acn)
261 struct GNUNET_NAT_Handle *nh = cls;
262 size_t alen = ntohs (acn->header.size) - sizeof (*acn);
263 const struct sockaddr *sa = (const struct sockaddr *) &acn[1];
264 enum GNUNET_NAT_AddressClass ac;
265 struct AddrEntry *ae;
267 ac = (enum GNUNET_NAT_AddressClass) ntohl (acn->addr_class);
268 if (GNUNET_YES == ntohl (acn->add_remove))
270 ae = GNUNET_malloc (sizeof (*ae) + alen);
273 GNUNET_memcpy (&ae[1],
276 GNUNET_CONTAINER_DLL_insert (nh->ae_head,
282 for (ae = nh->ae_head; NULL != ae; ae = ae->next)
283 if ( (ae->addrlen == alen) &&
284 (0 == memcmp (&ae[1],
294 GNUNET_CONTAINER_DLL_remove (nh->ae_head,
299 nh->address_callback (nh->callback_cls,
300 ntohl (acn->add_remove),
308 * Handle queue errors by reconnecting to NAT.
310 * @param cls the `struct GNUNET_NAT_Handle *`
311 * @param error details about the error
314 mq_error_handler (void *cls,
315 enum GNUNET_MQ_Error error)
317 struct GNUNET_NAT_Handle *nh = cls;
324 * Task to connect to the NAT service.
326 * @param cls our `struct GNUNET_NAT_Handle *`
329 do_connect (void *cls)
331 struct GNUNET_NAT_Handle *nh = cls;
332 struct GNUNET_MQ_MessageHandler handlers[] = {
333 GNUNET_MQ_hd_var_size (connection_reversal_request,
334 GNUNET_MESSAGE_TYPE_NAT_CONNECTION_REVERSAL_REQUESTED,
335 struct GNUNET_NAT_ConnectionReversalRequestedMessage,
337 GNUNET_MQ_hd_var_size (address_change_notification,
338 GNUNET_MESSAGE_TYPE_NAT_ADDRESS_CHANGE,
339 struct GNUNET_NAT_AddressChangeNotificationMessage,
341 GNUNET_MQ_handler_end ()
343 struct GNUNET_MQ_Envelope *env;
345 nh->reconnect_task = NULL;
346 nh->mq = GNUNET_CLIENT_connect (nh->cfg,
356 env = GNUNET_MQ_msg_copy (nh->reg);
357 GNUNET_MQ_send (nh->mq,
363 * Attempt to enable port redirection and detect public IP address
364 * contacting UPnP or NAT-PMP routers on the local network. Use @a
365 * addr to specify to which of the local host's addresses should the
366 * external port be mapped. The port is taken from the corresponding
367 * sockaddr_in[6] field. The NAT module should call the given @a
368 * address_callback for any 'plausible' external address.
370 * @param cfg configuration to use
371 * @param config_section name of the configuration section for optionsx
372 * @param proto protocol this is about, IPPROTO_TCP or IPPROTO_UDP
373 * @param num_addrs number of addresses in @a addrs
374 * @param addrs list of local addresses packets should be redirected to
375 * @param addrlens actual lengths of the addresses in @a addrs
376 * @param address_callback function to call everytime the public IP address changes
377 * @param reversal_callback function to call if someone wants connection reversal from us,
378 * NULL if connection reversal is not supported
379 * @param callback_cls closure for callbacks
380 * @return NULL on error, otherwise handle that can be used to unregister
382 struct GNUNET_NAT_Handle *
383 GNUNET_NAT_register (const struct GNUNET_CONFIGURATION_Handle *cfg,
384 const char *config_section,
386 unsigned int num_addrs,
387 const struct sockaddr **addrs,
388 const socklen_t *addrlens,
389 GNUNET_NAT_AddressCallback address_callback,
390 GNUNET_NAT_ReversalCallback reversal_callback,
393 struct GNUNET_NAT_Handle *nh;
394 struct GNUNET_NAT_RegisterMessage *rm;
400 for (unsigned int i=0;i<num_addrs;i++)
402 str_len = strlen (config_section) + 1;
404 if ( (len > GNUNET_SERVER_MAX_MESSAGE_SIZE - sizeof (*rm)) ||
405 (num_addrs > UINT16_MAX) )
410 rm = GNUNET_malloc (sizeof (*rm) + len);
411 rm->header.size = htons (sizeof (*rm) + len);
412 rm->header.type = htons (GNUNET_MESSAGE_TYPE_NAT_REGISTER);
413 rm->flags = GNUNET_NAT_RF_NONE;
414 if (NULL != address_callback)
415 rm->flags |= GNUNET_NAT_RF_ADDRESSES;
416 if (NULL != reversal_callback)
417 rm->flags |= GNUNET_NAT_RF_REVERSAL;
419 rm->str_len = htons (str_len);
420 rm->num_addrs = htons ((uint16_t) num_addrs);
421 off = (char *) &rm[1];
422 for (unsigned int i=0;i<num_addrs;i++)
424 switch (addrs[i]->sa_family)
427 if (sizeof (struct sockaddr_in) != addrlens[i])
434 if (sizeof (struct sockaddr_in6) != addrlens[i])
442 if (sizeof (struct sockaddr_un) != addrlens[i])
462 nh = GNUNET_new (struct GNUNET_NAT_Handle);
463 nh->reg = &rm->header;
465 nh->address_callback = address_callback;
466 nh->reversal_callback = reversal_callback;
467 nh->callback_cls = callback_cls;
474 * Check if an incoming message is a STUN message.
476 * @param data the packet
477 * @param len the length of the packet in @a data
478 * @return #GNUNET_YES if @a data is a STUN packet,
479 * #GNUNET_NO if the packet is invalid (not a stun packet)
482 test_stun_packet (const void *data,
485 const struct stun_header *hdr;
486 const struct stun_attr *attr;
487 uint32_t advertised_message_size;
488 uint32_t message_magic_cookie;
490 /* On entry, 'len' is the length of the UDP payload. After the
491 * initial checks it becomes the size of unprocessed options,
492 * while 'data' is advanced accordingly.
494 if (len < sizeof(struct stun_header))
496 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
497 "STUN packet too short (only %d, wanting at least %d)\n",
499 (int) sizeof (struct stun_header));
502 hdr = (const struct stun_header *) data;
503 /* Skip header as it is already in hdr */
504 len -= sizeof (struct stun_header);
505 data += sizeof (struct stun_header);
507 /* len as advertised in the message */
508 advertised_message_size = ntohs (hdr->msglen);
510 message_magic_cookie = ntohl (hdr->magic);
511 /* Compare if the cookie match */
512 if (STUN_MAGIC_COOKIE != message_magic_cookie)
514 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
515 "Invalid magic cookie for STUN\n");
519 if (advertised_message_size > len)
521 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
522 "Scrambled STUN packet length (got %d, expecting %d)\n",
523 advertised_message_size,
527 len = advertised_message_size;
530 if (len < sizeof (struct stun_attr))
532 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
533 "Attribute too short in STUN packet (got %d, expecting %d)\n",
535 (int) sizeof(struct stun_attr));
538 attr = (const struct stun_attr *) data;
540 /* compute total attribute length */
541 advertised_message_size = ntohs (attr->len) + sizeof(struct stun_attr);
543 /* Check if we still have space in our buffer */
544 if (advertised_message_size > len)
546 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
547 "Inconsistent Attribute (length %d exceeds remaining msg len %d)\n",
548 advertised_message_size,
552 data += advertised_message_size;
553 len -= advertised_message_size;
555 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
556 "STUN Packet, msg %04x, length: %d\n",
557 ntohs (hdr->msgtype),
558 advertised_message_size);
564 * Handle an incoming STUN message. This function is useful as
565 * some GNUnet service may be listening on a UDP port and might
566 * thus receive STUN messages while trying to receive other data.
567 * In this case, this function can be used to process replies
570 * The function does some basic sanity checks on packet size and
571 * content, try to extract a bit of information.
573 * At the moment this only processes BIND requests, and returns the
574 * externally visible address of the request to the rest of the
577 * @param nh handle to the NAT service
578 * @param sender_addr address from which we got @a data
579 * @param sender_addr_len number of bytes in @a sender_addr
580 * @param data the packet
581 * @param data_size number of bytes in @a data
582 * @return #GNUNET_OK on success
583 * #GNUNET_NO if the packet is not a STUN packet
584 * #GNUNET_SYSERR on internal error handling the packet
587 GNUNET_NAT_stun_handle_packet (struct GNUNET_NAT_Handle *nh,
588 const struct sockaddr *sender_addr,
589 size_t sender_addr_len,
593 struct GNUNET_MQ_Envelope *env;
594 struct GNUNET_NAT_HandleStunMessage *hsn;
598 test_stun_packet (data,
602 return GNUNET_SYSERR;
603 env = GNUNET_MQ_msg_extra (hsn,
604 data_size + sender_addr_len,
605 GNUNET_MESSAGE_TYPE_NAT_HANDLE_STUN);
606 hsn->sender_addr_size = htons ((uint16_t) sender_addr_len);
607 hsn->payload_size = htons ((uint16_t) data_size);
608 buf = (char *) &hsn[1];
612 buf += sender_addr_len;
616 GNUNET_MQ_send (nh->mq,
623 * Test if the given address is (currently) a plausible IP address for
624 * this peer. Mostly a convenience function so that clients do not
625 * have to explicitly track all IPs that the #GNUNET_NAT_AddressCallback
626 * has returned so far.
628 * @param nh the handle returned by register
629 * @param addr IP address to test (IPv4 or IPv6)
630 * @param addrlen number of bytes in @a addr
631 * @return #GNUNET_YES if the address is plausible,
632 * #GNUNET_NO if the address is not plausible,
633 * #GNUNET_SYSERR if the address is malformed
636 GNUNET_NAT_test_address (struct GNUNET_NAT_Handle *nh,
640 struct AddrEntry *ae;
642 if ( (addrlen != sizeof (struct sockaddr_in)) &&
643 (addrlen != sizeof (struct sockaddr_in6)) )
646 return GNUNET_SYSERR;
648 for (ae = nh->ae_head; NULL != ae; ae = ae->next)
649 if ( (addrlen == ae->addrlen) &&
659 * We learned about a peer (possibly behind NAT) so run the
660 * gnunet-nat-client to send dummy ICMP responses to cause
661 * that peer to connect to us (connection reversal).
663 * @param nh handle (used for configuration)
664 * @param local_sa our local address of the peer (IPv4-only)
665 * @param remote_sa the remote address of the peer (IPv4-only)
666 * @return #GNUNET_SYSERR on error,
667 * #GNUNET_NO if connection reversal is unavailable,
668 * #GNUNET_OK otherwise (presumably in progress)
671 GNUNET_NAT_request_reversal (struct GNUNET_NAT_Handle *nh,
672 const struct sockaddr_in *local_sa,
673 const struct sockaddr_in *remote_sa)
675 struct GNUNET_MQ_Envelope *env;
676 struct GNUNET_NAT_RequestConnectionReversalMessage *req;
680 return GNUNET_SYSERR;
681 GNUNET_break (AF_INET == local_sa->sin_family);
682 GNUNET_break (AF_INET == remote_sa->sin_family);
683 env = GNUNET_MQ_msg_extra (req,
684 2 * sizeof (struct sockaddr_in),
685 GNUNET_MESSAGE_TYPE_NAT_REQUEST_CONNECTION_REVERSAL);
686 req->local_addr_size = htons (sizeof (struct sockaddr_in));
687 req->remote_addr_size = htons (sizeof (struct sockaddr_in));
688 buf = (char *) &req[1];
691 sizeof (struct sockaddr_in));
692 buf += sizeof (struct sockaddr_in);
695 sizeof (struct sockaddr_in));
696 GNUNET_MQ_send (nh->mq,
703 * Stop port redirection and public IP address detection for the given
704 * handle. This frees the handle, after having sent the needed
705 * commands to close open ports.
707 * @param nh the handle to stop
710 GNUNET_NAT_unregister (struct GNUNET_NAT_Handle *nh)
714 GNUNET_MQ_destroy (nh->mq);
717 if (NULL != nh->reconnect_task)
719 GNUNET_SCHEDULER_cancel (nh->reconnect_task);
720 nh->reconnect_task = NULL;
722 GNUNET_free (nh->reg);
727 /* end of nat_api.c */