2 This file is part of GNUnet.
3 Copyright (C) 2007-2017 GNUnet e.V.
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU Affero General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
8 or (at your option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Affero General Public License for more details.
15 You should have received a copy of the GNU Affero General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
20 * @author Christian Grothoff
21 * @author Milan Bouchet-Valat
24 * Service for handling UPnP and NAT-PMP port forwarding
25 * and external IP address retrieval
28 #include "gnunet_nat_service.h"
34 * Entry in DLL of addresses of this peer.
42 struct AddrEntry *next;
47 struct AddrEntry *prev;
50 * Address class of the address.
52 enum GNUNET_NAT_AddressClass ac;
55 * Number of bytes that follow.
62 * Handle for active NAT registrations.
64 struct GNUNET_NAT_Handle
68 * Configuration we use.
70 const struct GNUNET_CONFIGURATION_Handle *cfg;
73 * Message queue for communicating with the NAT service.
75 struct GNUNET_MQ_Handle *mq;
78 * Our registration message.
80 struct GNUNET_MessageHeader *reg;
83 * Head of address DLL.
85 struct AddrEntry *ae_head;
88 * Tail of address DLL.
90 struct AddrEntry *ae_tail;
93 * Function to call when our addresses change.
95 GNUNET_NAT_AddressCallback address_callback;
98 * Function to call when another peer requests connection reversal.
100 GNUNET_NAT_ReversalCallback reversal_callback;
103 * Closure for the various callbacks.
108 * Task scheduled to reconnect to the service.
110 struct GNUNET_SCHEDULER_Task *reconnect_task;
113 * How long to wait until we reconnect.
115 struct GNUNET_TIME_Relative reconnect_delay;
120 * Task to connect to the NAT service.
122 * @param cls our `struct GNUNET_NAT_Handle *`
125 do_connect (void *cls);
129 * Task to connect to the NAT service.
131 * @param nh handle to reconnect
134 reconnect (struct GNUNET_NAT_Handle *nh)
136 struct AddrEntry *ae;
140 GNUNET_MQ_destroy (nh->mq);
143 while (NULL != (ae = nh->ae_head))
145 GNUNET_CONTAINER_DLL_remove (nh->ae_head,
148 nh->address_callback (nh->callback_cls,
151 (const struct sockaddr *) &ae[1],
156 = GNUNET_TIME_STD_BACKOFF (nh->reconnect_delay);
158 = GNUNET_SCHEDULER_add_delayed (nh->reconnect_delay,
165 * Check connection reversal request.
167 * @param cls our `struct GNUNET_NAT_Handle`
168 * @param crm the message
169 * @return #GNUNET_OK if @a crm is well-formed
172 check_connection_reversal_request (void *cls,
173 const struct GNUNET_NAT_ConnectionReversalRequestedMessage *crm)
175 if (ntohs (crm->header.size) !=
177 sizeof (struct sockaddr_in) )
180 return GNUNET_SYSERR;
187 * Handle connection reversal request.
189 * @param cls our `struct GNUNET_NAT_Handle`
190 * @param crm the message
193 handle_connection_reversal_request (void *cls,
194 const struct GNUNET_NAT_ConnectionReversalRequestedMessage *crm)
196 struct GNUNET_NAT_Handle *nh = cls;
198 nh->reversal_callback (nh->callback_cls,
199 (const struct sockaddr *) &crm[1],
200 sizeof (struct sockaddr_in));
205 * Check address change notification.
207 * @param cls our `struct GNUNET_NAT_Handle`
208 * @param acn the message
209 * @return #GNUNET_OK if @a crm is well-formed
212 check_address_change_notification (void *cls,
213 const struct GNUNET_NAT_AddressChangeNotificationMessage *acn)
215 size_t alen = ntohs (acn->header.size) - sizeof (*acn);
219 case sizeof (struct sockaddr_in):
221 const struct sockaddr_in *s4
222 = (const struct sockaddr_in *) &acn[1];
223 if (AF_INET != s4->sin_family)
226 return GNUNET_SYSERR;
230 case sizeof (struct sockaddr_in6):
232 const struct sockaddr_in6 *s6
233 = (const struct sockaddr_in6 *) &acn[1];
234 if (AF_INET6 != s6->sin6_family)
237 return GNUNET_SYSERR;
243 return GNUNET_SYSERR;
250 * Handle connection reversal request.
252 * @param cls our `struct GNUNET_NAT_Handle`
253 * @param acn the message
256 handle_address_change_notification (void *cls,
257 const struct GNUNET_NAT_AddressChangeNotificationMessage *acn)
259 struct GNUNET_NAT_Handle *nh = cls;
260 size_t alen = ntohs (acn->header.size) - sizeof (*acn);
261 const struct sockaddr *sa = (const struct sockaddr *) &acn[1];
262 enum GNUNET_NAT_AddressClass ac;
263 struct AddrEntry *ae;
265 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
266 "Received address change notification\n");
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_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])
435 if (sizeof (struct sockaddr_in6) != addrlens[i])
444 if (sizeof (struct sockaddr_un) != addrlens[i])
466 nh = GNUNET_new (struct GNUNET_NAT_Handle);
467 nh->reg = &rm->header;
469 nh->address_callback = address_callback;
470 nh->reversal_callback = reversal_callback;
471 nh->callback_cls = callback_cls;
478 * Check if an incoming message is a STUN message.
480 * @param data the packet
481 * @param len the length of the packet in @a data
482 * @return #GNUNET_YES if @a data is a STUN packet,
483 * #GNUNET_NO if the packet is invalid (not a stun packet)
486 test_stun_packet (const void *data,
489 const struct stun_header *hdr;
490 const struct stun_attr *attr;
491 uint32_t advertised_message_size;
492 uint32_t message_magic_cookie;
494 /* On entry, 'len' is the length of the UDP payload. After the
495 * initial checks it becomes the size of unprocessed options,
496 * while 'data' is advanced accordingly.
498 if (len < sizeof(struct stun_header))
500 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
501 "STUN packet too short (only %d, wanting at least %d)\n",
503 (int) sizeof (struct stun_header));
506 hdr = (const struct stun_header *) data;
507 /* Skip header as it is already in hdr */
508 len -= sizeof (struct stun_header);
509 data += sizeof (struct stun_header);
511 /* len as advertised in the message */
512 advertised_message_size = ntohs (hdr->msglen);
514 message_magic_cookie = ntohl (hdr->magic);
515 /* Compare if the cookie match */
516 if (STUN_MAGIC_COOKIE != message_magic_cookie)
518 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
519 "Invalid magic cookie for STUN\n");
523 if (advertised_message_size > len)
525 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
526 "Scrambled STUN packet length (got %d, expecting %d)\n",
527 advertised_message_size,
531 len = advertised_message_size;
534 if (len < sizeof (struct stun_attr))
536 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
537 "Attribute too short in STUN packet (got %d, expecting %d)\n",
539 (int) sizeof(struct stun_attr));
542 attr = (const struct stun_attr *) data;
544 /* compute total attribute length */
545 advertised_message_size = ntohs (attr->len) + sizeof(struct stun_attr);
547 /* Check if we still have space in our buffer */
548 if (advertised_message_size > len)
550 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
551 "Inconsistent Attribute (length %d exceeds remaining msg len %d)\n",
552 advertised_message_size,
556 data += advertised_message_size;
557 len -= advertised_message_size;
559 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
560 "STUN Packet, msg %04x, length: %d\n",
561 ntohs (hdr->msgtype),
562 advertised_message_size);
568 * Handle an incoming STUN message. This function is useful as
569 * some GNUnet service may be listening on a UDP port and might
570 * thus receive STUN messages while trying to receive other data.
571 * In this case, this function can be used to process replies
574 * The function does some basic sanity checks on packet size and
575 * content, try to extract a bit of information.
577 * At the moment this only processes BIND requests, and returns the
578 * externally visible address of the request to the rest of the
581 * @param nh handle to the NAT service
582 * @param sender_addr address from which we got @a data
583 * @param sender_addr_len number of bytes in @a sender_addr
584 * @param data the packet
585 * @param data_size number of bytes in @a data
586 * @return #GNUNET_OK on success
587 * #GNUNET_NO if the packet is not a STUN packet
588 * #GNUNET_SYSERR on internal error handling the packet
591 GNUNET_NAT_stun_handle_packet (struct GNUNET_NAT_Handle *nh,
592 const struct sockaddr *sender_addr,
593 size_t sender_addr_len,
597 struct GNUNET_MQ_Envelope *env;
598 struct GNUNET_NAT_HandleStunMessage *hsn;
602 test_stun_packet (data,
606 return GNUNET_SYSERR;
607 env = GNUNET_MQ_msg_extra (hsn,
608 data_size + sender_addr_len,
609 GNUNET_MESSAGE_TYPE_NAT_HANDLE_STUN);
610 hsn->sender_addr_size = htons ((uint16_t) sender_addr_len);
611 hsn->payload_size = htons ((uint16_t) data_size);
612 buf = (char *) &hsn[1];
616 buf += sender_addr_len;
620 GNUNET_MQ_send (nh->mq,
627 * Test if the given address is (currently) a plausible IP address for
628 * this peer. Mostly a convenience function so that clients do not
629 * have to explicitly track all IPs that the #GNUNET_NAT_AddressCallback
630 * has returned so far.
632 * @param nh the handle returned by register
633 * @param addr IP address to test (IPv4 or IPv6)
634 * @param addrlen number of bytes in @a addr
635 * @return #GNUNET_YES if the address is plausible,
636 * #GNUNET_NO if the address is not plausible,
637 * #GNUNET_SYSERR if the address is malformed
640 GNUNET_NAT_test_address (struct GNUNET_NAT_Handle *nh,
644 struct AddrEntry *ae;
646 if ( (addrlen != sizeof (struct sockaddr_in)) &&
647 (addrlen != sizeof (struct sockaddr_in6)) )
650 return GNUNET_SYSERR;
652 for (ae = nh->ae_head; NULL != ae; ae = ae->next)
653 if ( (addrlen == ae->addrlen) &&
663 * We learned about a peer (possibly behind NAT) so run the
664 * gnunet-nat-client to send dummy ICMP responses to cause
665 * that peer to connect to us (connection reversal).
667 * @param nh handle (used for configuration)
668 * @param local_sa our local address of the peer (IPv4-only)
669 * @param remote_sa the remote address of the peer (IPv4-only)
670 * @return #GNUNET_SYSERR on error,
671 * #GNUNET_NO if connection reversal is unavailable,
672 * #GNUNET_OK otherwise (presumably in progress)
675 GNUNET_NAT_request_reversal (struct GNUNET_NAT_Handle *nh,
676 const struct sockaddr_in *local_sa,
677 const struct sockaddr_in *remote_sa)
679 struct GNUNET_MQ_Envelope *env;
680 struct GNUNET_NAT_RequestConnectionReversalMessage *req;
684 return GNUNET_SYSERR;
685 GNUNET_break (AF_INET == local_sa->sin_family);
686 GNUNET_break (AF_INET == remote_sa->sin_family);
687 env = GNUNET_MQ_msg_extra (req,
688 2 * sizeof (struct sockaddr_in),
689 GNUNET_MESSAGE_TYPE_NAT_REQUEST_CONNECTION_REVERSAL);
690 req->local_addr_size = htons (sizeof (struct sockaddr_in));
691 req->remote_addr_size = htons (sizeof (struct sockaddr_in));
692 buf = (char *) &req[1];
695 sizeof (struct sockaddr_in));
696 buf += sizeof (struct sockaddr_in);
699 sizeof (struct sockaddr_in));
700 GNUNET_MQ_send (nh->mq,
707 * Stop port redirection and public IP address detection for the given
708 * handle. This frees the handle, after having sent the needed
709 * commands to close open ports.
711 * @param nh the handle to stop
714 GNUNET_NAT_unregister (struct GNUNET_NAT_Handle *nh)
718 GNUNET_MQ_destroy (nh->mq);
721 if (NULL != nh->reconnect_task)
723 GNUNET_SCHEDULER_cancel (nh->reconnect_task);
724 nh->reconnect_task = NULL;
726 GNUNET_free (nh->reg);
731 /* end of nat_api.c */