2 This file is part of GNUnet.
3 Copyright (C) 2013 GNUnet e.V.
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 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 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 Boston, MA 02110-1301, USA.
22 #include "gnunet_util_lib.h"
24 #include "gnunet_signatures.h"
25 #include "gnunet_statistics_service.h"
27 #include "cadet_protocol.h"
28 #include "cadet_path.h"
30 #include "gnunet-service-cadet_tunnel.h"
31 #include "gnunet-service-cadet_connection.h"
32 #include "gnunet-service-cadet_channel.h"
33 #include "gnunet-service-cadet_peer.h"
35 #define LOG(level, ...) GNUNET_log_from(level,"cadet-tun",__VA_ARGS__)
36 #define LOG2(level, ...) GNUNET_log_from_nocheck(level,"cadet-tun",__VA_ARGS__)
38 #define REKEY_WAIT GNUNET_TIME_relative_multiply(GNUNET_TIME_UNIT_SECONDS, 5)
40 #if !defined(GNUNET_CULL_LOGGING)
41 #define DUMP_KEYS_TO_STDERR GNUNET_YES
43 #define DUMP_KEYS_TO_STDERR GNUNET_YES
46 #define MIN_TUNNEL_BUFFER 8
47 #define MAX_TUNNEL_BUFFER 64
48 #define MAX_SKIPPED_KEYS 64
49 #define MAX_KEY_GAP 256
50 #define AX_HEADER_SIZE (sizeof (uint32_t) * 2\
51 + sizeof (struct GNUNET_CRYPTO_EcdhePublicKey))
54 /******************************************************************************/
55 /******************************** STRUCTS **********************************/
56 /******************************************************************************/
60 struct CadetTChannel *next;
61 struct CadetTChannel *prev;
62 struct CadetChannel *ch;
67 * Connection list and metadata.
69 struct CadetTConnection
74 struct CadetTConnection *next;
79 struct CadetTConnection *prev;
84 struct CadetConnection *c;
87 * Creation time, to keep oldest connection alive.
89 struct GNUNET_TIME_Absolute created;
92 * Connection throughput, to keep fastest connection alive.
99 * Struct to old keys for skipped messages while advancing the Axolotl ratchet.
101 struct CadetTunnelSkippedKey
106 struct CadetTunnelSkippedKey *next;
111 struct CadetTunnelSkippedKey *prev;
114 * When was this key stored (for timeout).
116 struct GNUNET_TIME_Absolute timestamp;
121 struct GNUNET_CRYPTO_SymmetricSessionKey HK;
126 struct GNUNET_CRYPTO_SymmetricSessionKey MK;
129 * Key number for a given HK.
136 * Axolotl data, according to https://github.com/trevp/axolotl/wiki .
138 struct CadetTunnelAxolotl
141 * A (double linked) list of stored message keys and associated header keys
142 * for "skipped" messages, i.e. messages that have not been
143 * received despite the reception of more recent messages, (head).
145 struct CadetTunnelSkippedKey *skipped_head;
148 * Skipped messages' keys DLL, tail.
150 struct CadetTunnelSkippedKey *skipped_tail;
153 * Elements in @a skipped_head <-> @a skipped_tail.
155 unsigned int skipped;
158 * 32-byte root key which gets updated by DH ratchet.
160 struct GNUNET_CRYPTO_SymmetricSessionKey RK;
163 * 32-byte header key (send).
165 struct GNUNET_CRYPTO_SymmetricSessionKey HKs;
168 * 32-byte header key (recv)
170 struct GNUNET_CRYPTO_SymmetricSessionKey HKr;
173 * 32-byte next header key (send).
175 struct GNUNET_CRYPTO_SymmetricSessionKey NHKs;
178 * 32-byte next header key (recv).
180 struct GNUNET_CRYPTO_SymmetricSessionKey NHKr;
183 * 32-byte chain keys (used for forward-secrecy updating, send).
185 struct GNUNET_CRYPTO_SymmetricSessionKey CKs;
188 * 32-byte chain keys (used for forward-secrecy updating, recv).
190 struct GNUNET_CRYPTO_SymmetricSessionKey CKr;
193 * ECDH for key exchange (A0 / B0).
195 struct GNUNET_CRYPTO_EcdhePrivateKey *kx_0;
198 * ECDH Ratchet key (send).
200 struct GNUNET_CRYPTO_EcdhePrivateKey *DHRs;
203 * ECDH Ratchet key (recv).
205 struct GNUNET_CRYPTO_EcdhePublicKey DHRr;
208 * Message number (reset to 0 with each new ratchet, next message to send).
213 * Message number (reset to 0 with each new ratchet, next message to recv).
218 * Previous message numbers (# of msgs sent under prev ratchet)
223 * True (#GNUNET_YES) if we have to send a new ratchet key in next msg.
228 * Number of messages recieved since our last ratchet advance.
229 * - If this counter = 0, we cannot send a new ratchet key in next msg.
230 * - If this counter > 0, we can (but don't yet have to) send a new key.
232 unsigned int ratchet_allowed;
235 * Number of messages recieved since our last ratchet advance.
236 * - If this counter = 0, we cannot send a new ratchet key in next msg.
237 * - If this counter > 0, we can (but don't yet have to) send a new key.
239 unsigned int ratchet_counter;
242 * When does this ratchet expire and a new one is triggered.
244 struct GNUNET_TIME_Absolute ratchet_expiration;
248 * Struct containing all information regarding a tunnel to a peer.
253 * Endpoint of the tunnel.
255 struct CadetPeer *peer;
260 struct CadetTunnelAxolotl *ax;
263 * State of the tunnel connectivity.
265 enum CadetTunnelCState cstate;
268 * State of the tunnel encryption.
270 enum CadetTunnelEState estate;
273 * Peer's ephemeral key, to recreate @c e_key and @c d_key when own ephemeral
276 struct GNUNET_CRYPTO_EcdhePublicKey peers_ephemeral_key;
279 * Encryption ("our") key. It is only "confirmed" if kx_ctx is NULL.
281 struct GNUNET_CRYPTO_SymmetricSessionKey e_key;
284 * Decryption ("their") key. It is only "confirmed" if kx_ctx is NULL.
286 struct GNUNET_CRYPTO_SymmetricSessionKey d_key;
289 * Task to start the rekey process.
291 struct GNUNET_SCHEDULER_Task *rekey_task;
294 * Paths that are actively used to reach the destination peer.
296 struct CadetTConnection *connection_head;
297 struct CadetTConnection *connection_tail;
300 * Next connection number.
305 * Channels inside this tunnel.
307 struct CadetTChannel *channel_head;
308 struct CadetTChannel *channel_tail;
311 * Channel ID for the next created channel.
313 CADET_ChannelNumber next_chid;
316 * Destroy flag: if true, destroy on last message.
318 struct GNUNET_SCHEDULER_Task * destroy_task;
321 * Queued messages, to transmit once tunnel gets connected.
323 struct CadetTunnelDelayed *tq_head;
324 struct CadetTunnelDelayed *tq_tail;
327 * Task to trim connections if too many are present.
329 struct GNUNET_SCHEDULER_Task * trim_connections_task;
332 * Ephemeral message in the queue (to avoid queueing more than one).
334 struct CadetConnectionQueue *ephm_h;
337 * Pong message in the queue.
339 struct CadetConnectionQueue *pong_h;
344 * Struct used to save messages in a non-ready tunnel to send once connected.
346 struct CadetTunnelDelayed
351 struct CadetTunnelDelayed *next;
352 struct CadetTunnelDelayed *prev;
357 struct CadetTunnel *t;
360 * Tunnel queue given to the channel to cancel request. Update on send_queued.
362 struct CadetTunnelQueue *tq;
367 /* struct GNUNET_MessageHeader *msg; */
372 * Handle for messages queued but not yet sent.
374 struct CadetTunnelQueue
377 * Connection queue handle, to cancel if necessary.
379 struct CadetConnectionQueue *cq;
382 * Handle in case message hasn't been given to a connection yet.
384 struct CadetTunnelDelayed *tqd;
387 * Continuation to call once sent.
392 * Closure for @c cont.
398 /******************************************************************************/
399 /******************************* GLOBALS ***********************************/
400 /******************************************************************************/
403 * Global handle to the statistics service.
405 extern struct GNUNET_STATISTICS_Handle *stats;
408 * Local peer own ID (memory efficient handle).
410 extern GNUNET_PEER_Id myid;
413 * Local peer own ID (full value).
415 extern struct GNUNET_PeerIdentity my_full_id;
419 * Don't try to recover tunnels if shutting down.
421 extern int shutting_down;
425 * Set of all tunnels, in order to trigger a new exchange on rekey.
426 * Indexed by peer's ID.
428 static struct GNUNET_CONTAINER_MultiPeerMap *tunnels;
431 * Own Peer ID private key.
433 const static struct GNUNET_CRYPTO_EddsaPrivateKey *id_key;
436 /******************************** AXOLOTL ************************************/
439 * How many messages are needed to trigger a ratchet advance.
441 static unsigned long long ratchet_messages;
444 * How long until we trigger a ratched advance.
446 static struct GNUNET_TIME_Relative ratchet_time;
449 /******************************************************************************/
450 /******************************** STATIC ***********************************/
451 /******************************************************************************/
454 * Get string description for tunnel connectivity state.
456 * @param cs Tunnel state.
458 * @return String representation.
461 cstate2s (enum CadetTunnelCState cs)
467 case CADET_TUNNEL_NEW:
468 return "CADET_TUNNEL_NEW";
469 case CADET_TUNNEL_SEARCHING:
470 return "CADET_TUNNEL_SEARCHING";
471 case CADET_TUNNEL_WAITING:
472 return "CADET_TUNNEL_WAITING";
473 case CADET_TUNNEL_READY:
474 return "CADET_TUNNEL_READY";
475 case CADET_TUNNEL_SHUTDOWN:
476 return "CADET_TUNNEL_SHUTDOWN";
478 SPRINTF (buf, "%u (UNKNOWN STATE)", cs);
486 * Get string description for tunnel encryption state.
488 * @param es Tunnel state.
490 * @return String representation.
493 estate2s (enum CadetTunnelEState es)
499 case CADET_TUNNEL_KEY_UNINITIALIZED:
500 return "CADET_TUNNEL_KEY_UNINITIALIZED";
501 case CADET_TUNNEL_KEY_SENT:
502 return "CADET_TUNNEL_KEY_SENT";
503 case CADET_TUNNEL_KEY_PING:
504 return "CADET_TUNNEL_KEY_PING";
505 case CADET_TUNNEL_KEY_OK:
506 return "CADET_TUNNEL_KEY_OK";
507 case CADET_TUNNEL_KEY_REKEY:
508 return "CADET_TUNNEL_KEY_REKEY";
510 SPRINTF (buf, "%u (UNKNOWN STATE)", es);
518 * @brief Check if tunnel is ready to send traffic.
520 * Tunnel must be connected and with encryption correctly set up.
522 * @param t Tunnel to check.
524 * @return #GNUNET_YES if ready, #GNUNET_NO otherwise
527 is_ready (struct CadetTunnel *t)
533 conn_ok = CADET_TUNNEL_READY == t->cstate;
534 enc_ok = CADET_TUNNEL_KEY_OK == t->estate
535 || CADET_TUNNEL_KEY_REKEY == t->estate
536 || CADET_TUNNEL_KEY_PING == t->estate;
537 ready = conn_ok && enc_ok;
538 ready = ready || GCT_is_loopback (t);
544 * Get the channel's buffer. ONLY FOR NON-LOOPBACK CHANNELS!!
546 * @param tch Tunnel's channel handle.
548 * @return Amount of messages the channel can still buffer towards the client.
551 get_channel_buffer (const struct CadetTChannel *tch)
555 /* If channel is incoming, is terminal in the FWD direction and fwd is YES */
556 fwd = GCCH_is_terminal (tch->ch, GNUNET_YES);
558 return GCCH_get_buffer (tch->ch, fwd);
563 * Get the channel's allowance status.
565 * @param tch Tunnel's channel handle.
567 * @return #GNUNET_YES if we allowed the client to send data to us.
570 get_channel_allowed (const struct CadetTChannel *tch)
574 /* If channel is outgoing, is origin in the FWD direction and fwd is YES */
575 fwd = GCCH_is_origin (tch->ch, GNUNET_YES);
577 return GCCH_get_allowed (tch->ch, fwd);
582 * Get the connection's buffer.
584 * @param tc Tunnel's connection handle.
586 * @return Amount of messages the connection can still buffer.
589 get_connection_buffer (const struct CadetTConnection *tc)
593 /* If connection is outgoing, is origin in the FWD direction and fwd is YES */
594 fwd = GCC_is_origin (tc->c, GNUNET_YES);
596 return GCC_get_buffer (tc->c, fwd);
601 * Get the connection's allowance.
603 * @param tc Tunnel's connection handle.
605 * @return Amount of messages we have allowed the next peer to send us.
608 get_connection_allowed (const struct CadetTConnection *tc)
612 /* If connection is outgoing, is origin in the FWD direction and fwd is YES */
613 fwd = GCC_is_origin (tc->c, GNUNET_YES);
615 return GCC_get_allowed (tc->c, fwd);
620 * Create a new Axolotl ephemeral (ratchet) key.
625 new_ephemeral (struct CadetTunnel *t)
627 GNUNET_free_non_null (t->ax->DHRs);
628 t->ax->DHRs = GNUNET_CRYPTO_ecdhe_key_create();
629 #if DUMP_KEYS_TO_STDERR
631 struct GNUNET_CRYPTO_EcdhePublicKey pub;
632 GNUNET_CRYPTO_ecdhe_key_get_public (t->ax->DHRs, &pub);
633 LOG (GNUNET_ERROR_TYPE_DEBUG, " new DHRs generated: pub %s\n",
634 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &pub));
643 * @param plaintext Content to HMAC.
644 * @param size Size of @c plaintext.
645 * @param iv Initialization vector for the message.
646 * @param key Key to use.
647 * @param hmac[out] Destination to store the HMAC.
650 t_hmac (const void *plaintext, size_t size,
651 uint32_t iv, const struct GNUNET_CRYPTO_SymmetricSessionKey *key,
652 struct GNUNET_CADET_Hash *hmac)
654 static const char ctx[] = "cadet authentication key";
655 struct GNUNET_CRYPTO_AuthKey auth_key;
656 struct GNUNET_HashCode hash;
658 #if DUMP_KEYS_TO_STDERR
659 LOG (GNUNET_ERROR_TYPE_INFO, " HMAC %u bytes with key %s\n", size,
660 GNUNET_i2s ((struct GNUNET_PeerIdentity *) key));
662 GNUNET_CRYPTO_hmac_derive_key (&auth_key, key,
667 /* Two step: CADET_Hash is only 256 bits, HashCode is 512. */
668 GNUNET_CRYPTO_hmac (&auth_key, plaintext, size, &hash);
669 GNUNET_memcpy (hmac, &hash, sizeof (*hmac));
676 * @param key Key to use.
677 * @param hash[out] Resulting HMAC.
678 * @param source Source key material (data to HMAC).
679 * @param len Length of @a source.
682 t_ax_hmac_hash (struct GNUNET_CRYPTO_SymmetricSessionKey *key,
683 struct GNUNET_HashCode *hash,
684 void *source, unsigned int len)
686 static const char ctx[] = "axolotl HMAC-HASH";
687 struct GNUNET_CRYPTO_AuthKey auth_key;
689 GNUNET_CRYPTO_hmac_derive_key (&auth_key, key,
692 GNUNET_CRYPTO_hmac (&auth_key, source, len, hash);
697 * Derive a key from a HMAC-HASH.
699 * @param key Key to use for the HMAC.
700 * @param out Key to generate.
701 * @param source Source key material (data to HMAC).
702 * @param len Length of @a source.
705 t_hmac_derive_key (struct GNUNET_CRYPTO_SymmetricSessionKey *key,
706 struct GNUNET_CRYPTO_SymmetricSessionKey *out,
707 void *source, unsigned int len)
709 static const char ctx[] = "axolotl derive key";
710 struct GNUNET_HashCode h;
712 t_ax_hmac_hash (key, &h, source, len);
713 GNUNET_CRYPTO_kdf (out, sizeof (*out), ctx, sizeof (ctx),
714 &h, sizeof (h), NULL);
719 * Encrypt data with the axolotl tunnel key.
721 * @param t Tunnel whose key to use.
722 * @param dst Destination for the encrypted data.
723 * @param src Source of the plaintext. Can overlap with @c dst.
724 * @param size Size of the plaintext.
726 * @return Size of the encrypted data.
729 t_ax_encrypt (struct CadetTunnel *t, void *dst, const void *src, size_t size)
731 struct GNUNET_CRYPTO_SymmetricSessionKey MK;
732 struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
733 struct CadetTunnelAxolotl *ax;
735 struct GNUNET_TIME_Absolute start_time;
736 struct GNUNET_TIME_Relative duration;
738 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_ax_encrypt start\n");
739 start_time = GNUNET_TIME_absolute_get ();
743 ax->ratchet_counter++;
744 if (GNUNET_YES == ax->ratchet_allowed
745 && (ratchet_messages <= ax->ratchet_counter
746 || 0 == GNUNET_TIME_absolute_get_remaining (ax->ratchet_expiration).rel_value_us))
748 ax->ratchet_flag = GNUNET_YES;
751 if (GNUNET_YES == ax->ratchet_flag)
753 /* Advance ratchet */
754 struct GNUNET_CRYPTO_SymmetricSessionKey keys[3];
755 struct GNUNET_HashCode dh;
756 struct GNUNET_HashCode hmac;
757 static const char ctx[] = "axolotl ratchet";
762 /* RK, NHKs, CKs = KDF( HMAC-HASH(RK, DH(DHRs, DHRr)) ) */
763 GNUNET_CRYPTO_ecc_ecdh (ax->DHRs, &ax->DHRr, &dh);
764 t_ax_hmac_hash (&ax->RK, &hmac, &dh, sizeof (dh));
765 GNUNET_CRYPTO_kdf (keys, sizeof (keys), ctx, sizeof (ctx),
766 &hmac, sizeof (hmac), NULL);
773 ax->ratchet_flag = GNUNET_NO;
774 ax->ratchet_allowed = GNUNET_NO;
775 ax->ratchet_counter = 0;
776 ax->ratchet_expiration =
777 GNUNET_TIME_absolute_add (GNUNET_TIME_absolute_get(), ratchet_time);
780 t_hmac_derive_key (&ax->CKs, &MK, "0", 1);
781 GNUNET_CRYPTO_symmetric_derive_iv (&iv, &MK, NULL, 0, NULL);
783 #if DUMP_KEYS_TO_STDERR
784 LOG (GNUNET_ERROR_TYPE_DEBUG, " CKs: %s\n",
785 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->CKs));
786 LOG (GNUNET_ERROR_TYPE_INFO, " AX_ENC with key %u: %s\n", ax->Ns,
787 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &MK));
790 out_size = GNUNET_CRYPTO_symmetric_encrypt (src, size, &MK, &iv, dst);
792 t_hmac_derive_key (&ax->CKs, &ax->CKs, "1", 1);
794 duration = GNUNET_TIME_absolute_get_duration (start_time);
795 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_ax_encrypt duration %s\n",
796 GNUNET_STRINGS_relative_time_to_string (duration, GNUNET_YES));
797 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_ax_encrypt end\n");
804 * Decrypt data with the axolotl tunnel key.
806 * @param t Tunnel whose key to use.
807 * @param dst Destination for the decrypted data.
808 * @param src Source of the ciphertext. Can overlap with @c dst.
809 * @param size Size of the ciphertext.
811 * @return Size of the decrypted data.
814 t_ax_decrypt (struct CadetTunnel *t, void *dst, const void *src, size_t size)
816 struct GNUNET_CRYPTO_SymmetricSessionKey MK;
817 struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
818 struct CadetTunnelAxolotl *ax;
821 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_ax_decrypt start\n");
825 t_hmac_derive_key (&ax->CKr, &MK, "0", 1);
826 GNUNET_CRYPTO_symmetric_derive_iv (&iv, &MK, NULL, 0, NULL);
828 #if DUMP_KEYS_TO_STDERR
829 LOG (GNUNET_ERROR_TYPE_DEBUG, " CKr: %s\n",
830 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->CKr));
831 LOG (GNUNET_ERROR_TYPE_INFO, " AX_DEC with key %u: %s\n", ax->Nr,
832 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &MK));
835 GNUNET_assert (size >= sizeof (struct GNUNET_MessageHeader));
836 out_size = GNUNET_CRYPTO_symmetric_decrypt (src, size, &MK, &iv, dst);
837 GNUNET_assert (out_size == size);
839 t_hmac_derive_key (&ax->CKr, &ax->CKr, "1", 1);
841 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_ax_decrypt end\n");
848 * Encrypt header with the axolotl header key.
850 * @param t Tunnel whose key to use.
851 * @param msg Message whose header to encrypt.
854 t_h_encrypt (struct CadetTunnel *t, struct GNUNET_CADET_Encrypted *msg)
856 struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
857 struct CadetTunnelAxolotl *ax;
860 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_h_encrypt start\n");
863 GNUNET_CRYPTO_symmetric_derive_iv (&iv, &ax->HKs, NULL, 0, NULL);
865 #if DUMP_KEYS_TO_STDERR
866 LOG (GNUNET_ERROR_TYPE_INFO, " AX_ENC_H with key %s\n",
867 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->HKs));
870 out_size = GNUNET_CRYPTO_symmetric_encrypt (&msg->Ns, AX_HEADER_SIZE,
871 &ax->HKs, &iv, &msg->Ns);
873 GNUNET_assert (AX_HEADER_SIZE == out_size);
875 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_ax_encrypt end\n");
880 * Decrypt header with the current axolotl header key.
882 * @param t Tunnel whose current ax HK to use.
883 * @param src Message whose header to decrypt.
884 * @param dst Where to decrypt header to.
887 t_h_decrypt (struct CadetTunnel *t, const struct GNUNET_CADET_Encrypted *src,
888 struct GNUNET_CADET_Encrypted *dst)
890 struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
891 struct CadetTunnelAxolotl *ax;
894 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_h_decrypt start\n");
897 GNUNET_CRYPTO_symmetric_derive_iv (&iv, &ax->HKr, NULL, 0, NULL);
899 #if DUMP_KEYS_TO_STDERR
900 LOG (GNUNET_ERROR_TYPE_INFO, " AX_DEC_H with key %s\n",
901 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->HKr));
904 out_size = GNUNET_CRYPTO_symmetric_decrypt (&src->Ns, AX_HEADER_SIZE,
905 &ax->HKr, &iv, &dst->Ns);
907 GNUNET_assert (AX_HEADER_SIZE == out_size);
909 LOG (GNUNET_ERROR_TYPE_DEBUG, " t_h_decrypt end\n");
914 * Decrypt and verify data with the appropriate tunnel key and verify that the
915 * data has not been altered since it was sent by the remote peer.
917 * @param t Tunnel whose key to use.
918 * @param dst Destination for the plaintext.
919 * @param src Source of the message. Can overlap with @c dst.
920 * @param size Size of the message.
922 * @return Size of the decrypted data, -1 if an error was encountered.
925 try_old_ax_keys (struct CadetTunnel *t, void *dst,
926 const struct GNUNET_CADET_Encrypted *src, size_t size)
928 struct CadetTunnelSkippedKey *key;
929 struct GNUNET_CADET_Hash *hmac;
930 struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
931 struct GNUNET_CADET_Encrypted plaintext_header;
932 struct GNUNET_CRYPTO_SymmetricSessionKey *valid_HK;
938 LOG (GNUNET_ERROR_TYPE_DEBUG, "Trying old keys\n");
939 hmac = &plaintext_header.hmac;
940 esize = size - sizeof (struct GNUNET_CADET_Encrypted);
942 /* Find a correct Header Key */
943 for (key = t->ax->skipped_head; NULL != key; key = key->next)
945 #if DUMP_KEYS_TO_STDERR
946 LOG (GNUNET_ERROR_TYPE_DEBUG, " Trying hmac with key %s\n",
947 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &key->HK));
949 t_hmac (&src->Ns, AX_HEADER_SIZE + esize, 0, &key->HK, hmac);
950 if (0 == memcmp (hmac, &src->hmac, sizeof (*hmac)))
952 LOG (GNUNET_ERROR_TYPE_DEBUG, " hmac correct\n");
960 /* Should've been checked in -cadet_connection.c handle_cadet_encrypted. */
961 GNUNET_assert (size > sizeof (struct GNUNET_CADET_Encrypted));
962 len = size - sizeof (struct GNUNET_CADET_Encrypted);
963 GNUNET_assert (len >= sizeof (struct GNUNET_MessageHeader));
966 GNUNET_CRYPTO_symmetric_derive_iv (&iv, &key->HK, NULL, 0, NULL);
967 res = GNUNET_CRYPTO_symmetric_decrypt (&src->Ns, AX_HEADER_SIZE,
968 &key->HK, &iv, &plaintext_header.Ns);
969 GNUNET_assert (AX_HEADER_SIZE == res);
970 LOG (GNUNET_ERROR_TYPE_DEBUG, " Message %u, previous: %u\n",
971 ntohl (plaintext_header.Ns), ntohl (plaintext_header.PNs));
973 /* Find the correct Message Key */
974 N = ntohl (plaintext_header.Ns);
975 while (NULL != key && N != key->Kn)
977 if (NULL == key || 0 != memcmp (&key->HK, valid_HK, sizeof (*valid_HK)))
980 #if DUMP_KEYS_TO_STDERR
981 LOG (GNUNET_ERROR_TYPE_INFO, " AX_DEC_H with skipped key %s\n",
982 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &key->HK));
983 LOG (GNUNET_ERROR_TYPE_INFO, " AX_DEC with skipped key %u: %s\n",
984 key->Kn, GNUNET_i2s ((struct GNUNET_PeerIdentity *) &key->MK));
987 /* Decrypt payload */
988 GNUNET_CRYPTO_symmetric_derive_iv (&iv, &key->MK, NULL, 0, NULL);
989 res = GNUNET_CRYPTO_symmetric_decrypt (&src[1], len, &key->MK, &iv, dst);
992 GNUNET_CONTAINER_DLL_remove (t->ax->skipped_head, t->ax->skipped_tail, key);
994 GNUNET_free (key); /* GNUNET_free overwrites memory with 0xbaadf00d */
1001 * Delete a key from the list of skipped keys.
1003 * @param t Tunnel to delete from.
1004 * @param HKr Header Key to use.
1007 store_skipped_key (struct CadetTunnel *t,
1008 const struct GNUNET_CRYPTO_SymmetricSessionKey *HKr)
1010 struct CadetTunnelSkippedKey *key;
1012 key = GNUNET_new (struct CadetTunnelSkippedKey);
1013 key->timestamp = GNUNET_TIME_absolute_get ();
1014 key->Kn = t->ax->Nr;
1015 key->HK = t->ax->HKr;
1016 t_hmac_derive_key (&t->ax->CKr, &key->MK, "0", 1);
1017 #if DUMP_KEYS_TO_STDERR
1018 LOG (GNUNET_ERROR_TYPE_DEBUG, " storing MK for Nr %u: %s\n",
1019 key->Kn, GNUNET_i2s ((struct GNUNET_PeerIdentity *) &key->MK));
1020 LOG (GNUNET_ERROR_TYPE_DEBUG, " for CKr: %s\n",
1021 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &t->ax->CKr));
1023 t_hmac_derive_key (&t->ax->CKr, &t->ax->CKr, "1", 1);
1024 GNUNET_CONTAINER_DLL_insert (t->ax->skipped_head, t->ax->skipped_tail, key);
1031 * Delete a key from the list of skipped keys.
1033 * @param t Tunnel to delete from.
1034 * @param key Key to delete.
1037 delete_skipped_key (struct CadetTunnel *t, struct CadetTunnelSkippedKey *key)
1039 GNUNET_CONTAINER_DLL_remove (t->ax->skipped_head, t->ax->skipped_tail, key);
1046 * Stage skipped AX keys and calculate the message key.
1048 * Stores each HK and MK for skipped messages.
1050 * @param t Tunnel where to stage the keys.
1051 * @param HKr Header key.
1052 * @param Np Received meesage number.
1054 * @return GNUNET_OK if keys were stored.
1055 * GNUNET_SYSERR if an error ocurred (Np not expected).
1058 store_ax_keys (struct CadetTunnel *t,
1059 const struct GNUNET_CRYPTO_SymmetricSessionKey *HKr,
1065 gap = Np - t->ax->Nr;
1066 LOG (GNUNET_ERROR_TYPE_INFO, "Storing keys [%u, %u)\n", t->ax->Nr, Np);
1067 if (MAX_KEY_GAP < gap)
1069 /* Avoid DoS (forcing peer to do 2*33 chain HMAC operations) */
1070 /* TODO: start new key exchange on return */
1071 GNUNET_break_op (0);
1072 LOG (GNUNET_ERROR_TYPE_WARNING, "Got message %u, expected %u+\n",
1074 return GNUNET_SYSERR;
1078 /* Delayed message: don't store keys, flag to try old keys. */
1079 return GNUNET_SYSERR;
1082 while (t->ax->Nr < Np)
1083 store_skipped_key (t, HKr);
1085 while (t->ax->skipped > MAX_SKIPPED_KEYS)
1086 delete_skipped_key (t, t->ax->skipped_tail);
1093 * Decrypt and verify data with the appropriate tunnel key and verify that the
1094 * data has not been altered since it was sent by the remote peer.
1096 * @param t Tunnel whose key to use.
1097 * @param dst Destination for the plaintext.
1098 * @param src Source of the message. Can overlap with @c dst.
1099 * @param size Size of the message.
1101 * @return Size of the decrypted data, -1 if an error was encountered.
1104 t_ax_decrypt_and_validate (struct CadetTunnel *t, void *dst,
1105 const struct GNUNET_CADET_Encrypted *src,
1108 struct CadetTunnelAxolotl *ax;
1109 struct GNUNET_CADET_Hash msg_hmac;
1110 struct GNUNET_HashCode hmac;
1111 struct GNUNET_CADET_Encrypted plaintext_header;
1114 size_t esize; /* Size of encryped payload */
1115 size_t osize; /* Size of output (decrypted payload) */
1117 esize = size - sizeof (struct GNUNET_CADET_Encrypted);
1122 /* Try current HK */
1123 t_hmac (&src->Ns, AX_HEADER_SIZE + esize, 0, &ax->HKr, &msg_hmac);
1124 if (0 != memcmp (&msg_hmac, &src->hmac, sizeof (msg_hmac)))
1126 static const char ctx[] = "axolotl ratchet";
1127 struct GNUNET_CRYPTO_SymmetricSessionKey keys[3]; /* RKp, NHKp, CKp */
1128 struct GNUNET_CRYPTO_SymmetricSessionKey HK;
1129 struct GNUNET_HashCode dh;
1130 struct GNUNET_CRYPTO_EcdhePublicKey *DHRp;
1133 LOG (GNUNET_ERROR_TYPE_DEBUG, " trying next HK\n");
1134 t_hmac (&src->Ns, AX_HEADER_SIZE + esize, 0, &ax->NHKr, &msg_hmac);
1135 if (0 != memcmp (&msg_hmac, &src->hmac, sizeof (msg_hmac)))
1137 /* Try the skipped keys, if that fails, we're out of luck. */
1138 return try_old_ax_keys (t, dst, src, size);
1140 LOG (GNUNET_ERROR_TYPE_INFO, "next HK worked\n");
1144 t_h_decrypt (t, src, &plaintext_header);
1145 Np = ntohl (plaintext_header.Ns);
1146 PNp = ntohl (plaintext_header.PNs);
1147 DHRp = &plaintext_header.DHRs;
1148 store_ax_keys (t, &HK, PNp);
1150 /* RKp, NHKp, CKp = KDF (HMAC-HASH (RK, DH (DHRp, DHRs))) */
1151 GNUNET_CRYPTO_ecc_ecdh (ax->DHRs, DHRp, &dh);
1152 t_ax_hmac_hash (&ax->RK, &hmac, &dh, sizeof (dh));
1153 GNUNET_CRYPTO_kdf (keys, sizeof (keys), ctx, sizeof (ctx),
1154 &hmac, sizeof (hmac), NULL);
1156 /* Commit "purported" keys */
1162 ax->ratchet_allowed = GNUNET_YES;
1166 LOG (GNUNET_ERROR_TYPE_DEBUG, "current HK\n");
1167 t_h_decrypt (t, src, &plaintext_header);
1168 Np = ntohl (plaintext_header.Ns);
1169 PNp = ntohl (plaintext_header.PNs);
1171 LOG (GNUNET_ERROR_TYPE_INFO, " got AX Nr %u\n", Np);
1173 if (GNUNET_OK != store_ax_keys (t, &ax->HKr, Np))
1174 /* Try the skipped keys, if that fails, we're out of luck. */
1175 return try_old_ax_keys (t, dst, src, size);
1177 osize = t_ax_decrypt (t, dst, &src[1], esize);
1182 GNUNET_break_op (0);
1191 * Pick a connection on which send the next data message.
1193 * @param t Tunnel on which to send the message.
1195 * @return The connection on which to send the next message.
1197 static struct CadetConnection *
1198 tunnel_get_connection (struct CadetTunnel *t)
1200 struct CadetTConnection *iter;
1201 struct CadetConnection *best;
1203 unsigned int lowest_q;
1205 LOG (GNUNET_ERROR_TYPE_DEBUG, "tunnel_get_connection %s\n", GCT_2s (t));
1207 lowest_q = UINT_MAX;
1208 for (iter = t->connection_head; NULL != iter; iter = iter->next)
1210 LOG (GNUNET_ERROR_TYPE_DEBUG, " connection %s: %u\n",
1211 GCC_2s (iter->c), GCC_get_state (iter->c));
1212 if (CADET_CONNECTION_READY == GCC_get_state (iter->c))
1214 qn = GCC_get_qn (iter->c, GCC_is_origin (iter->c, GNUNET_YES));
1215 LOG (GNUNET_ERROR_TYPE_DEBUG, " q_n %u, \n", qn);
1223 LOG (GNUNET_ERROR_TYPE_DEBUG, " selected: connection %s\n", GCC_2s (best));
1229 * Callback called when a queued message is sent.
1231 * Calculates the average time and connection packet tracking.
1233 * @param cls Closure (TunnelQueue handle).
1234 * @param c Connection this message was on.
1235 * @param q Connection queue handle (unused).
1236 * @param type Type of message sent.
1237 * @param fwd Was this a FWD going message?
1238 * @param size Size of the message.
1241 tun_message_sent (void *cls,
1242 struct CadetConnection *c,
1243 struct CadetConnectionQueue *q,
1244 uint16_t type, int fwd, size_t size)
1246 struct CadetTunnelQueue *qt = cls;
1247 struct CadetTunnel *t;
1249 LOG (GNUNET_ERROR_TYPE_DEBUG, "tun_message_sent\n");
1251 GNUNET_assert (NULL != qt->cont);
1252 t = NULL == c ? NULL : GCC_get_tunnel (c);
1253 qt->cont (qt->cont_cls, t, qt, type, size);
1259 count_queued_data (const struct CadetTunnel *t)
1261 struct CadetTunnelDelayed *iter;
1264 for (count = 0, iter = t->tq_head; iter != NULL; iter = iter->next)
1271 * Delete a queued message: either was sent or the channel was destroyed
1272 * before the tunnel's key exchange had a chance to finish.
1274 * @param tqd Delayed queue handle.
1277 unqueue_data (struct CadetTunnelDelayed *tqd)
1279 GNUNET_CONTAINER_DLL_remove (tqd->t->tq_head, tqd->t->tq_tail, tqd);
1285 * Cache a message to be sent once tunnel is online.
1287 * @param t Tunnel to hold the message.
1288 * @param msg Message itself (copy will be made).
1290 static struct CadetTunnelDelayed *
1291 queue_data (struct CadetTunnel *t, const struct GNUNET_MessageHeader *msg)
1293 struct CadetTunnelDelayed *tqd;
1294 uint16_t size = ntohs (msg->size);
1296 LOG (GNUNET_ERROR_TYPE_DEBUG, "queue data on Tunnel %s\n", GCT_2s (t));
1298 GNUNET_assert (GNUNET_NO == is_ready (t));
1300 tqd = GNUNET_malloc (sizeof (struct CadetTunnelDelayed) + size);
1303 GNUNET_memcpy (&tqd[1], msg, size);
1304 GNUNET_CONTAINER_DLL_insert_tail (t->tq_head, t->tq_tail, tqd);
1310 * Sends an already built message on a tunnel, encrypting it and
1311 * choosing the best connection.
1313 * @param message Message to send. Function modifies it.
1314 * @param t Tunnel on which this message is transmitted.
1315 * @param c Connection to use (autoselect if NULL).
1316 * @param force Force the tunnel to take the message (buffer overfill).
1317 * @param cont Continuation to call once message is really sent.
1318 * @param cont_cls Closure for @c cont.
1319 * @param existing_q In case this a transmission of previously queued data,
1320 * this should be TunnelQueue given to the client.
1322 * @return Handle to cancel message.
1323 * NULL if @c cont is NULL or an error happens and message is dropped.
1325 static struct CadetTunnelQueue *
1326 send_prebuilt_message (const struct GNUNET_MessageHeader *message,
1327 struct CadetTunnel *t,
1328 struct CadetConnection *c,
1332 struct CadetTunnelQueue *existing_q)
1334 struct GNUNET_MessageHeader *msg;
1335 struct GNUNET_CADET_Encrypted *ax_msg;
1336 struct CadetTunnelQueue *tq;
1337 size_t size = ntohs (message->size);
1338 char cbuf[sizeof (struct GNUNET_CADET_Encrypted) + size] GNUNET_ALIGN;
1344 LOG (GNUNET_ERROR_TYPE_DEBUG, "GMT Send on Tunnel %s\n", GCT_2s (t));
1346 if (GNUNET_NO == is_ready (t))
1348 struct CadetTunnelDelayed *tqd;
1349 /* A non null existing_q indicates sending of queued data.
1350 * Should only happen after tunnel becomes ready.
1352 GNUNET_assert (NULL == existing_q);
1353 tqd = queue_data (t, message);
1356 tq = GNUNET_new (struct CadetTunnelQueue);
1360 tq->cont_cls = cont_cls;
1364 GNUNET_assert (GNUNET_NO == GCT_is_loopback (t));
1366 ax_msg = (struct GNUNET_CADET_Encrypted *) cbuf;
1367 msg = &ax_msg->header;
1368 msg->size = htons (sizeof (struct GNUNET_CADET_Encrypted) + size);
1369 msg->type = htons (GNUNET_MESSAGE_TYPE_CADET_ENCRYPTED);
1370 esize = t_ax_encrypt (t, &ax_msg[1], message, size);
1371 ax_msg->Ns = htonl (t->ax->Ns++);
1372 ax_msg->PNs = htonl (t->ax->PNs);
1373 GNUNET_CRYPTO_ecdhe_key_get_public (t->ax->DHRs, &ax_msg->DHRs);
1374 t_h_encrypt (t, ax_msg);
1375 t_hmac (&ax_msg->Ns, AX_HEADER_SIZE + esize, 0, &t->ax->HKs, &ax_msg->hmac);
1376 GNUNET_assert (esize == size);
1379 c = tunnel_get_connection (t);
1382 /* Why is tunnel 'ready'? Should have been queued! */
1383 if (NULL != t->destroy_task)
1386 GCT_debug (t, GNUNET_ERROR_TYPE_WARNING);
1388 return NULL; /* Drop... */
1390 fwd = GCC_is_origin (c, GNUNET_YES);
1391 ax_msg->cid = *GCC_get_id (c);
1392 ax_msg->pid = htonl (GCC_get_pid (c, fwd));
1395 type = ntohs (message->type);
1398 case GNUNET_MESSAGE_TYPE_CADET_DATA:
1399 case GNUNET_MESSAGE_TYPE_CADET_DATA_ACK:
1400 if (GNUNET_MESSAGE_TYPE_CADET_DATA == type)
1401 mid = ntohl (((struct GNUNET_CADET_Data *) message)->mid);
1403 mid = ntohl (((struct GNUNET_CADET_DataACK *) message)->mid);
1405 case GNUNET_MESSAGE_TYPE_CADET_KEEPALIVE:
1406 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_CREATE:
1407 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DESTROY:
1408 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_ACK:
1409 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_NACK:
1413 LOG (GNUNET_ERROR_TYPE_ERROR, "type %s not valid\n", GC_m2s (type));
1415 LOG (GNUNET_ERROR_TYPE_DEBUG, "type %s\n", GC_m2s (type));
1419 GNUNET_break (NULL == GCC_send_prebuilt_message (msg, type, mid, c, fwd,
1420 force, NULL, NULL));
1423 if (NULL == existing_q)
1425 tq = GNUNET_new (struct CadetTunnelQueue); /* FIXME valgrind: leak*/
1432 tq->cq = GCC_send_prebuilt_message (msg, type, mid, c, fwd, force,
1433 &tun_message_sent, tq);
1434 GNUNET_assert (NULL != tq->cq);
1436 tq->cont_cls = cont_cls;
1443 * Send all cached messages that we can, tunnel is online.
1445 * @param t Tunnel that holds the messages. Cannot be loopback.
1448 send_queued_data (struct CadetTunnel *t)
1450 struct CadetTunnelDelayed *tqd;
1451 struct CadetTunnelDelayed *next;
1454 LOG (GNUNET_ERROR_TYPE_INFO, "Send queued data, tunnel %s\n", GCT_2s (t));
1456 if (GCT_is_loopback (t))
1462 if (GNUNET_NO == is_ready (t))
1464 LOG (GNUNET_ERROR_TYPE_WARNING, " not ready yet: %s/%s\n",
1465 estate2s (t->estate), cstate2s (t->cstate));
1469 room = GCT_get_connections_buffer (t);
1470 LOG (GNUNET_ERROR_TYPE_DEBUG, " buffer space: %u\n", room);
1471 LOG (GNUNET_ERROR_TYPE_DEBUG, " tq head: %p\n", t->tq_head);
1472 for (tqd = t->tq_head; NULL != tqd && room > 0; tqd = next)
1474 LOG (GNUNET_ERROR_TYPE_DEBUG, " sending queued data\n");
1477 send_prebuilt_message ((struct GNUNET_MessageHeader *) &tqd[1],
1478 tqd->t, NULL, GNUNET_YES,
1479 NULL != tqd->tq ? tqd->tq->cont : NULL,
1480 NULL != tqd->tq ? tqd->tq->cont_cls : NULL,
1484 LOG (GNUNET_ERROR_TYPE_DEBUG, "GCT_send_queued_data end\n", GCP_2s (t->peer));
1489 * @brief Resend the KX until we complete the handshake.
1491 * @param cls Closure (tunnel).
1494 kx_resend (void *cls)
1496 struct CadetTunnel *t = cls;
1498 t->rekey_task = NULL;
1499 if (CADET_TUNNEL_KEY_OK == t->estate)
1501 /* Should have been canceled on estate change */
1506 GCT_send_kx (t, CADET_TUNNEL_KEY_SENT >= t->estate);
1511 * Callback called when a queued message is sent.
1513 * @param cls Closure.
1514 * @param c Connection this message was on.
1515 * @param type Type of message sent.
1516 * @param fwd Was this a FWD going message?
1517 * @param size Size of the message.
1520 ephm_sent (void *cls,
1521 struct CadetConnection *c,
1522 struct CadetConnectionQueue *q,
1523 uint16_t type, int fwd, size_t size)
1525 struct CadetTunnel *t = cls;
1526 LOG (GNUNET_ERROR_TYPE_DEBUG, "ephemeral sent %s\n", GC_m2s (type));
1530 if (CADET_TUNNEL_KEY_OK == t->estate)
1533 if (NULL != t->rekey_task)
1536 GCT_debug (t, GNUNET_ERROR_TYPE_WARNING);
1537 GNUNET_SCHEDULER_cancel (t->rekey_task);
1539 t->rekey_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
1546 * Called only on shutdown, destroy every tunnel.
1548 * @param cls Closure (unused).
1549 * @param key Current public key.
1550 * @param value Value in the hash map (tunnel).
1552 * @return #GNUNET_YES, so we should continue to iterate,
1555 destroy_iterator (void *cls,
1556 const struct GNUNET_PeerIdentity *key,
1559 struct CadetTunnel *t = value;
1561 LOG (GNUNET_ERROR_TYPE_DEBUG,
1562 "GCT_shutdown destroying tunnel at %p\n", t);
1569 * Notify remote peer that we don't know a channel he is talking about,
1570 * probably CHANNEL_DESTROY was missed.
1572 * @param t Tunnel on which to notify.
1573 * @param gid ID of the channel.
1576 send_channel_destroy (struct CadetTunnel *t, unsigned int gid)
1578 struct GNUNET_CADET_ChannelManage msg;
1580 msg.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DESTROY);
1581 msg.header.size = htons (sizeof (msg));
1582 msg.chid = htonl (gid);
1584 LOG (GNUNET_ERROR_TYPE_DEBUG,
1585 "WARNING destroying unknown channel %u on tunnel %s\n",
1587 send_prebuilt_message (&msg.header, t, NULL, GNUNET_YES, NULL, NULL, NULL);
1592 * Demultiplex data per channel and call appropriate channel handler.
1594 * @param t Tunnel on which the data came.
1595 * @param msg Data message.
1596 * @param fwd Is this message fwd? This only is meaningful in loopback channels.
1597 * #GNUNET_YES if message is FWD on the respective channel (loopback)
1598 * #GNUNET_NO if message is BCK on the respective channel (loopback)
1599 * #GNUNET_SYSERR if message on a one-ended channel (remote)
1602 handle_data (struct CadetTunnel *t,
1603 const struct GNUNET_CADET_Data *msg,
1606 struct CadetChannel *ch;
1612 size = ntohs (msg->header.size);
1614 sizeof (struct GNUNET_CADET_Data) +
1615 sizeof (struct GNUNET_MessageHeader))
1620 type = ntohs (msg[1].header.type);
1621 LOG (GNUNET_ERROR_TYPE_DEBUG, " payload of type %s\n", GC_m2s (type));
1622 SPRINTF (buf, "# received payload of type %hu", type);
1623 GNUNET_STATISTICS_update (stats, buf, 1, GNUNET_NO);
1627 ch = GCT_get_channel (t, ntohl (msg->chid));
1630 GNUNET_STATISTICS_update (stats, "# data on unknown channel",
1632 LOG (GNUNET_ERROR_TYPE_DEBUG, "channel 0x%X unknown\n", ntohl (msg->chid));
1633 send_channel_destroy (t, ntohl (msg->chid));
1637 GCCH_handle_data (ch, msg, fwd);
1642 * Demultiplex data ACKs per channel and update appropriate channel buffer info.
1644 * @param t Tunnel on which the DATA ACK came.
1645 * @param msg DATA ACK message.
1646 * @param fwd Is this message fwd? This only is meaningful in loopback channels.
1647 * #GNUNET_YES if message is FWD on the respective channel (loopback)
1648 * #GNUNET_NO if message is BCK on the respective channel (loopback)
1649 * #GNUNET_SYSERR if message on a one-ended channel (remote)
1652 handle_data_ack (struct CadetTunnel *t,
1653 const struct GNUNET_CADET_DataACK *msg,
1656 struct CadetChannel *ch;
1660 size = ntohs (msg->header.size);
1661 if (size != sizeof (struct GNUNET_CADET_DataACK))
1668 ch = GCT_get_channel (t, ntohl (msg->chid));
1671 GNUNET_STATISTICS_update (stats, "# data ack on unknown channel",
1673 LOG (GNUNET_ERROR_TYPE_DEBUG, "WARNING channel %u unknown\n",
1678 GCCH_handle_data_ack (ch, msg, fwd);
1683 * Handle channel create.
1685 * @param t Tunnel on which the message came.
1686 * @param msg ChannelCreate message.
1689 handle_ch_create (struct CadetTunnel *t,
1690 const struct GNUNET_CADET_ChannelCreate *msg)
1692 struct CadetChannel *ch;
1696 size = ntohs (msg->header.size);
1697 if (size != sizeof (struct GNUNET_CADET_ChannelCreate))
1699 GNUNET_break_op (0);
1704 ch = GCT_get_channel (t, ntohl (msg->chid));
1705 if (NULL != ch && ! GCT_is_loopback (t))
1707 /* Probably a retransmission, safe to ignore */
1708 LOG (GNUNET_ERROR_TYPE_DEBUG, " already exists...\n");
1710 ch = GCCH_handle_create (t, msg);
1712 GCT_add_channel (t, ch);
1718 * Handle channel NACK: check correctness and call channel handler for NACKs.
1720 * @param t Tunnel on which the NACK came.
1721 * @param msg NACK message.
1724 handle_ch_nack (struct CadetTunnel *t,
1725 const struct GNUNET_CADET_ChannelManage *msg)
1727 struct CadetChannel *ch;
1731 size = ntohs (msg->header.size);
1732 if (size != sizeof (struct GNUNET_CADET_ChannelManage))
1739 ch = GCT_get_channel (t, ntohl (msg->chid));
1742 GNUNET_STATISTICS_update (stats, "# channel NACK on unknown channel",
1744 LOG (GNUNET_ERROR_TYPE_DEBUG, "WARNING channel %u unknown\n",
1749 GCCH_handle_nack (ch);
1754 * Handle a CHANNEL ACK (SYNACK/ACK).
1756 * @param t Tunnel on which the CHANNEL ACK came.
1757 * @param msg CHANNEL ACK message.
1758 * @param fwd Is this message fwd? This only is meaningful in loopback channels.
1759 * #GNUNET_YES if message is FWD on the respective channel (loopback)
1760 * #GNUNET_NO if message is BCK on the respective channel (loopback)
1761 * #GNUNET_SYSERR if message on a one-ended channel (remote)
1764 handle_ch_ack (struct CadetTunnel *t,
1765 const struct GNUNET_CADET_ChannelManage *msg,
1768 struct CadetChannel *ch;
1772 size = ntohs (msg->header.size);
1773 if (size != sizeof (struct GNUNET_CADET_ChannelManage))
1780 ch = GCT_get_channel (t, ntohl (msg->chid));
1783 GNUNET_STATISTICS_update (stats, "# channel ack on unknown channel",
1785 LOG (GNUNET_ERROR_TYPE_DEBUG, "WARNING channel %u unknown\n",
1790 GCCH_handle_ack (ch, msg, fwd);
1795 * Handle a channel destruction message.
1797 * @param t Tunnel on which the message came.
1798 * @param msg Channel destroy message.
1799 * @param fwd Is this message fwd? This only is meaningful in loopback channels.
1800 * #GNUNET_YES if message is FWD on the respective channel (loopback)
1801 * #GNUNET_NO if message is BCK on the respective channel (loopback)
1802 * #GNUNET_SYSERR if message on a one-ended channel (remote)
1805 handle_ch_destroy (struct CadetTunnel *t,
1806 const struct GNUNET_CADET_ChannelManage *msg,
1809 struct CadetChannel *ch;
1813 size = ntohs (msg->header.size);
1814 if (size != sizeof (struct GNUNET_CADET_ChannelManage))
1821 ch = GCT_get_channel (t, ntohl (msg->chid));
1824 /* Probably a retransmission, safe to ignore */
1828 GCCH_handle_destroy (ch, msg, fwd);
1833 * Free Axolotl data.
1838 destroy_ax (struct CadetTunnel *t)
1843 GNUNET_free_non_null (t->ax->DHRs);
1844 GNUNET_free_non_null (t->ax->kx_0);
1845 while (NULL != t->ax->skipped_head)
1846 delete_skipped_key (t, t->ax->skipped_head);
1847 GNUNET_assert (0 == t->ax->skipped);
1849 GNUNET_free (t->ax);
1852 if (NULL != t->rekey_task)
1854 GNUNET_SCHEDULER_cancel (t->rekey_task);
1855 t->rekey_task = NULL;
1857 if (NULL != t->ephm_h)
1859 GCC_cancel (t->ephm_h);
1866 * Demultiplex by message type and call appropriate handler for a message
1867 * towards a channel of a local tunnel.
1869 * @param t Tunnel this message came on.
1870 * @param msgh Message header.
1871 * @param fwd Is this message fwd? This only is meaningful in loopback channels.
1872 * #GNUNET_YES if message is FWD on the respective channel (loopback)
1873 * #GNUNET_NO if message is BCK on the respective channel (loopback)
1874 * #GNUNET_SYSERR if message on a one-ended channel (remote)
1877 handle_decrypted (struct CadetTunnel *t,
1878 const struct GNUNET_MessageHeader *msgh,
1884 type = ntohs (msgh->type);
1885 LOG (GNUNET_ERROR_TYPE_DEBUG, "<-- %s on %s\n", GC_m2s (type), GCT_2s (t));
1886 SPRINTF (buf, "# received encrypted of type %hu (%s)", type, GC_m2s (type));
1887 GNUNET_STATISTICS_update (stats, buf, 1, GNUNET_NO);
1891 case GNUNET_MESSAGE_TYPE_CADET_KEEPALIVE:
1892 /* Do nothing, connection aleady got updated. */
1893 GNUNET_STATISTICS_update (stats, "# keepalives received", 1, GNUNET_NO);
1896 case GNUNET_MESSAGE_TYPE_CADET_DATA:
1897 /* Don't send hop ACK, wait for client to ACK */
1898 handle_data (t, (struct GNUNET_CADET_Data *) msgh, fwd);
1901 case GNUNET_MESSAGE_TYPE_CADET_DATA_ACK:
1902 handle_data_ack (t, (struct GNUNET_CADET_DataACK *) msgh, fwd);
1905 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_CREATE:
1906 handle_ch_create (t, (struct GNUNET_CADET_ChannelCreate *) msgh);
1909 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_NACK:
1910 handle_ch_nack (t, (struct GNUNET_CADET_ChannelManage *) msgh);
1913 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_ACK:
1914 handle_ch_ack (t, (struct GNUNET_CADET_ChannelManage *) msgh, fwd);
1917 case GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DESTROY:
1918 handle_ch_destroy (t, (struct GNUNET_CADET_ChannelManage *) msgh, fwd);
1922 GNUNET_break_op (0);
1923 LOG (GNUNET_ERROR_TYPE_WARNING,
1924 "end-to-end message not known (%u)\n",
1925 ntohs (msgh->type));
1926 GCT_debug (t, GNUNET_ERROR_TYPE_WARNING);
1931 /******************************************************************************/
1932 /******************************** API ***********************************/
1933 /******************************************************************************/
1936 * Decrypt and process an encrypted message.
1938 * Calls the appropriate handler for a message in a channel of a local tunnel.
1940 * @param t Tunnel this message came on.
1941 * @param msg Message header.
1944 GCT_handle_encrypted (struct CadetTunnel *t,
1945 const struct GNUNET_CADET_Encrypted *msg)
1947 uint16_t size = ntohs (msg->header.size);
1950 const struct GNUNET_MessageHeader *msgh;
1953 GNUNET_STATISTICS_update (stats, "# received encrypted", 1, GNUNET_NO);
1955 decrypted_size = t_ax_decrypt_and_validate (t, cbuf, msg, size);
1957 if (-1 == decrypted_size)
1959 GNUNET_STATISTICS_update (stats, "# unable to decrypt", 1, GNUNET_NO);
1960 if (CADET_TUNNEL_KEY_PING <= t->estate)
1962 GNUNET_break_op (0);
1963 LOG (GNUNET_ERROR_TYPE_WARNING, "Wrong crypto, tunnel %s\n", GCT_2s (t));
1964 GCT_debug (t, GNUNET_ERROR_TYPE_WARNING);
1968 GCT_change_estate (t, CADET_TUNNEL_KEY_OK);
1970 /* FIXME: this is bad, as the structs returned from
1971 this loop may be unaligned, see util's MST for
1972 how to do this right. */
1974 while (off + sizeof (struct GNUNET_MessageHeader) <= decrypted_size)
1978 msgh = (const struct GNUNET_MessageHeader *) &cbuf[off];
1979 msize = ntohs (msgh->size);
1980 if (msize < sizeof (struct GNUNET_MessageHeader))
1982 GNUNET_break_op (0);
1985 if (off + msize < decrypted_size)
1987 GNUNET_break_op (0);
1990 handle_decrypted (t, msgh, GNUNET_SYSERR);
1997 * Handle a Key eXchange message.
1999 * @param t Tunnel on which the message came.
2000 * @param msg KX message itself.
2003 GCT_handle_kx (struct CadetTunnel *t,
2004 const struct GNUNET_CADET_KX *msg)
2006 struct CadetTunnelAxolotl *ax;
2007 struct GNUNET_HashCode key_material[3];
2008 struct GNUNET_CRYPTO_SymmetricSessionKey keys[5];
2009 const char salt[] = "CADET Axolotl salt";
2010 const struct GNUNET_PeerIdentity *pid;
2013 LOG (GNUNET_ERROR_TYPE_INFO, "<== { KX} on %s\n", GCT_2s (t));
2017 /* Something is wrong if ax is NULL. Whose fault it is? */
2022 pid = GCT_get_destination (t);
2023 if (0 > GNUNET_CRYPTO_cmp_peer_identity (&my_full_id, pid))
2024 am_I_alice = GNUNET_YES;
2025 else if (0 < GNUNET_CRYPTO_cmp_peer_identity (&my_full_id, pid))
2026 am_I_alice = GNUNET_NO;
2029 GNUNET_break_op (0);
2033 if (0 != (GNUNET_CADET_KX_FLAG_FORCE_REPLY & ntohl (msg->flags)))
2035 if (NULL != t->rekey_task)
2037 GNUNET_SCHEDULER_cancel (t->rekey_task);
2038 t->rekey_task = NULL;
2040 GCT_send_kx (t, GNUNET_NO);
2043 if (0 == memcmp (&ax->DHRr, &msg->ratchet_key, sizeof(msg->ratchet_key)))
2045 LOG (GNUNET_ERROR_TYPE_INFO, " known ratchet key, exit\n");
2049 LOG (GNUNET_ERROR_TYPE_INFO, " is Alice? %s\n", am_I_alice ? "YES" : "NO");
2051 ax->DHRr = msg->ratchet_key;
2054 if (GNUNET_YES == am_I_alice)
2056 GNUNET_CRYPTO_eddsa_ecdh (id_key, /* A */
2057 &msg->ephemeral_key, /* B0 */
2062 GNUNET_CRYPTO_ecdh_eddsa (ax->kx_0, /* B0 */
2063 &pid->public_key, /* A */
2068 if (GNUNET_YES == am_I_alice)
2070 GNUNET_CRYPTO_ecdh_eddsa (ax->kx_0, /* A0 */
2071 &pid->public_key, /* B */
2076 GNUNET_CRYPTO_eddsa_ecdh (id_key, /* A */
2077 &msg->ephemeral_key, /* B0 */
2084 /* (This is the triple-DH, we could probably safely skip this,
2085 as A0/B0 are already in the key material.) */
2086 GNUNET_CRYPTO_ecc_ecdh (ax->kx_0, /* A0 or B0 */
2087 &msg->ephemeral_key, /* B0 or A0 */
2090 #if DUMP_KEYS_TO_STDERR
2093 for (i = 0; i < 3; i++)
2094 LOG (GNUNET_ERROR_TYPE_INFO, "km[%u]: %s\n",
2095 i, GNUNET_h2s (&key_material[i]));
2100 GNUNET_CRYPTO_kdf (keys, sizeof (keys),
2101 salt, sizeof (salt),
2102 &key_material, sizeof (key_material), NULL);
2104 if (0 == memcmp (&ax->RK, &keys[0], sizeof(ax->RK)))
2106 LOG (GNUNET_ERROR_TYPE_INFO, " known handshake key, exit\n");
2110 if (GNUNET_YES == am_I_alice)
2116 ax->ratchet_flag = GNUNET_YES;
2124 ax->ratchet_flag = GNUNET_NO;
2125 ax->ratchet_allowed = GNUNET_NO;
2126 ax->ratchet_counter = 0;
2127 ax->ratchet_expiration =
2128 GNUNET_TIME_absolute_add (GNUNET_TIME_absolute_get(), ratchet_time);
2133 GCT_change_estate (t, CADET_TUNNEL_KEY_PING);
2134 send_queued_data (t);
2138 * Initialize the tunnel subsystem.
2140 * @param c Configuration handle.
2141 * @param key ECC private key, to derive all other keys and do crypto.
2144 GCT_init (const struct GNUNET_CONFIGURATION_Handle *c,
2145 const struct GNUNET_CRYPTO_EddsaPrivateKey *key)
2147 unsigned int expected_overhead;
2149 LOG (GNUNET_ERROR_TYPE_DEBUG, "init\n");
2151 expected_overhead = 0;
2152 expected_overhead += sizeof (struct GNUNET_CADET_Encrypted);
2153 expected_overhead += sizeof (struct GNUNET_CADET_Data);
2154 expected_overhead += sizeof (struct GNUNET_CADET_ACK);
2155 GNUNET_assert (GNUNET_CONSTANTS_CADET_P2P_OVERHEAD == expected_overhead);
2158 GNUNET_CONFIGURATION_get_value_number (c,
2163 GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_WARNING,
2167 ratchet_messages = 64;
2170 GNUNET_CONFIGURATION_get_value_time (c,
2175 GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_WARNING,
2176 "CADET", "RATCHET_TIME", "USING DEFAULT");
2177 ratchet_time = GNUNET_TIME_UNIT_HOURS;
2182 tunnels = GNUNET_CONTAINER_multipeermap_create (128, GNUNET_YES);
2187 * Shut down the tunnel subsystem.
2192 LOG (GNUNET_ERROR_TYPE_DEBUG, "Shutting down tunnels\n");
2193 GNUNET_CONTAINER_multipeermap_iterate (tunnels, &destroy_iterator, NULL);
2194 GNUNET_CONTAINER_multipeermap_destroy (tunnels);
2201 * @param destination Peer this tunnel is towards.
2203 struct CadetTunnel *
2204 GCT_new (struct CadetPeer *destination)
2206 struct CadetTunnel *t;
2208 t = GNUNET_new (struct CadetTunnel);
2210 t->peer = destination;
2213 GNUNET_CONTAINER_multipeermap_put (tunnels, GCP_get_id (destination), t,
2214 GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST))
2220 t->ax = GNUNET_new (struct CadetTunnelAxolotl);
2222 t->ax->kx_0 = GNUNET_CRYPTO_ecdhe_key_create ();
2228 * Change the tunnel's connection state.
2230 * @param t Tunnel whose connection state to change.
2231 * @param cstate New connection state.
2234 GCT_change_cstate (struct CadetTunnel* t, enum CadetTunnelCState cstate)
2238 LOG (GNUNET_ERROR_TYPE_DEBUG, "Tunnel %s cstate %s => %s\n",
2239 GCP_2s (t->peer), cstate2s (t->cstate), cstate2s (cstate));
2240 if (myid != GCP_get_short_id (t->peer) &&
2241 CADET_TUNNEL_READY != t->cstate &&
2242 CADET_TUNNEL_READY == cstate)
2245 if (CADET_TUNNEL_KEY_OK == t->estate)
2247 LOG (GNUNET_ERROR_TYPE_DEBUG, " cstate triggered send queued data\n");
2248 send_queued_data (t);
2250 else if (CADET_TUNNEL_KEY_UNINITIALIZED == t->estate)
2252 LOG (GNUNET_ERROR_TYPE_DEBUG, " cstate triggered KX\n");
2253 GCT_send_kx (t, GNUNET_NO);
2257 LOG (GNUNET_ERROR_TYPE_DEBUG, "estate %s\n", estate2s (t->estate));
2262 if (CADET_TUNNEL_READY == cstate
2263 && CONNECTIONS_PER_TUNNEL <= GCT_count_connections (t))
2265 LOG (GNUNET_ERROR_TYPE_DEBUG, " cstate triggered stop dht\n");
2266 GCP_stop_search (t->peer);
2272 * Change the tunnel encryption state.
2274 * If the encryption state changes to OK, stop the rekey task.
2276 * @param t Tunnel whose encryption state to change, or NULL.
2277 * @param state New encryption state.
2280 GCT_change_estate (struct CadetTunnel* t, enum CadetTunnelEState state)
2282 enum CadetTunnelEState old;
2289 LOG (GNUNET_ERROR_TYPE_DEBUG, "Tunnel %s estate was %s\n",
2290 GCP_2s (t->peer), estate2s (old));
2291 LOG (GNUNET_ERROR_TYPE_DEBUG, "Tunnel %s estate is now %s\n",
2292 GCP_2s (t->peer), estate2s (t->estate));
2294 if (CADET_TUNNEL_KEY_OK != old && CADET_TUNNEL_KEY_OK == t->estate)
2296 if (NULL != t->rekey_task)
2298 GNUNET_SCHEDULER_cancel (t->rekey_task);
2299 t->rekey_task = NULL;
2301 /* Send queued data if tunnel is not loopback */
2302 if (myid != GCP_get_short_id (t->peer))
2303 send_queued_data (t);
2309 * @brief Check if tunnel has too many connections, and remove one if necessary.
2311 * Currently this means the newest connection, unless it is a direct one.
2312 * Implemented as a task to avoid freeing a connection that is in the middle
2313 * of being created/processed.
2315 * @param cls Closure (Tunnel to check).
2318 trim_connections (void *cls)
2320 struct CadetTunnel *t = cls;
2322 t->trim_connections_task = NULL;
2323 if (GCT_count_connections (t) > 2 * CONNECTIONS_PER_TUNNEL)
2325 struct CadetTConnection *iter;
2326 struct CadetTConnection *c;
2328 for (c = iter = t->connection_head; NULL != iter; iter = iter->next)
2330 if ((iter->created.abs_value_us > c->created.abs_value_us)
2331 && GNUNET_NO == GCC_is_direct (iter->c))
2338 LOG (GNUNET_ERROR_TYPE_DEBUG, "Too many connections on tunnel %s\n",
2340 LOG (GNUNET_ERROR_TYPE_DEBUG, "Destroying connection %s\n",
2353 * Add a connection to a tunnel.
2356 * @param c Connection.
2359 GCT_add_connection (struct CadetTunnel *t, struct CadetConnection *c)
2361 struct CadetTConnection *aux;
2363 GNUNET_assert (NULL != c);
2365 LOG (GNUNET_ERROR_TYPE_DEBUG, "add connection %s\n", GCC_2s (c));
2366 LOG (GNUNET_ERROR_TYPE_DEBUG, " to tunnel %s\n", GCT_2s (t));
2367 for (aux = t->connection_head; aux != NULL; aux = aux->next)
2371 aux = GNUNET_new (struct CadetTConnection);
2373 aux->created = GNUNET_TIME_absolute_get ();
2375 GNUNET_CONTAINER_DLL_insert (t->connection_head, t->connection_tail, aux);
2377 if (CADET_TUNNEL_SEARCHING == t->cstate)
2378 GCT_change_cstate (t, CADET_TUNNEL_WAITING);
2380 if (NULL != t->trim_connections_task)
2381 t->trim_connections_task = GNUNET_SCHEDULER_add_now (&trim_connections, t);
2386 * Remove a connection from a tunnel.
2389 * @param c Connection.
2392 GCT_remove_connection (struct CadetTunnel *t,
2393 struct CadetConnection *c)
2395 struct CadetTConnection *aux;
2396 struct CadetTConnection *next;
2399 LOG (GNUNET_ERROR_TYPE_DEBUG, "Removing connection %s from tunnel %s\n",
2400 GCC_2s (c), GCT_2s (t));
2401 for (aux = t->connection_head; aux != NULL; aux = next)
2406 GNUNET_CONTAINER_DLL_remove (t->connection_head, t->connection_tail, aux);
2411 conns = GCT_count_connections (t);
2413 && NULL == t->destroy_task
2414 && CADET_TUNNEL_SHUTDOWN != t->cstate
2415 && GNUNET_NO == shutting_down)
2417 if (0 == GCT_count_any_connections (t))
2418 GCT_change_cstate (t, CADET_TUNNEL_SEARCHING);
2420 GCT_change_cstate (t, CADET_TUNNEL_WAITING);
2423 /* Start new connections if needed */
2424 if (CONNECTIONS_PER_TUNNEL > conns
2425 && CADET_TUNNEL_SHUTDOWN != t->cstate
2426 && GNUNET_NO == shutting_down)
2428 LOG (GNUNET_ERROR_TYPE_DEBUG, " too few connections, getting new ones\n");
2429 GCP_connect (t->peer); /* Will change cstate to WAITING when possible */
2433 /* If not marked as ready, no change is needed */
2434 if (CADET_TUNNEL_READY != t->cstate)
2437 /* Check if any connection is ready to maintain cstate */
2438 for (aux = t->connection_head; aux != NULL; aux = aux->next)
2439 if (CADET_CONNECTION_READY == GCC_get_state (aux->c))
2445 * Add a channel to a tunnel.
2448 * @param ch Channel.
2451 GCT_add_channel (struct CadetTunnel *t, struct CadetChannel *ch)
2453 struct CadetTChannel *aux;
2455 GNUNET_assert (NULL != ch);
2457 LOG (GNUNET_ERROR_TYPE_DEBUG, "Adding channel %p to tunnel %p\n", ch, t);
2459 for (aux = t->channel_head; aux != NULL; aux = aux->next)
2461 LOG (GNUNET_ERROR_TYPE_DEBUG, " already there %p\n", aux->ch);
2466 aux = GNUNET_new (struct CadetTChannel);
2468 LOG (GNUNET_ERROR_TYPE_DEBUG,
2469 " adding %p to %p\n", aux, t->channel_head);
2470 GNUNET_CONTAINER_DLL_insert_tail (t->channel_head,
2474 if (NULL != t->destroy_task)
2476 GNUNET_SCHEDULER_cancel (t->destroy_task);
2477 t->destroy_task = NULL;
2478 LOG (GNUNET_ERROR_TYPE_DEBUG, " undo destroy!\n");
2484 * Remove a channel from a tunnel.
2487 * @param ch Channel.
2490 GCT_remove_channel (struct CadetTunnel *t, struct CadetChannel *ch)
2492 struct CadetTChannel *aux;
2494 LOG (GNUNET_ERROR_TYPE_DEBUG, "Removing channel %p from tunnel %p\n", ch, t);
2495 for (aux = t->channel_head; aux != NULL; aux = aux->next)
2499 LOG (GNUNET_ERROR_TYPE_DEBUG, " found! %s\n", GCCH_2s (ch));
2500 GNUNET_CONTAINER_DLL_remove (t->channel_head,
2511 * Search for a channel by global ID.
2513 * @param t Tunnel containing the channel.
2514 * @param chid Public channel number.
2516 * @return channel handler, NULL if doesn't exist
2518 struct CadetChannel *
2519 GCT_get_channel (struct CadetTunnel *t, CADET_ChannelNumber chid)
2521 struct CadetTChannel *iter;
2526 for (iter = t->channel_head; NULL != iter; iter = iter->next)
2528 if (GCCH_get_id (iter->ch) == chid)
2532 return NULL == iter ? NULL : iter->ch;
2537 * @brief Destroy a tunnel and free all resources.
2539 * Should only be called a while after the tunnel has been marked as destroyed,
2540 * in case there is a new channel added to the same peer shortly after marking
2541 * the tunnel. This way we avoid a new public key handshake.
2543 * @param cls Closure (tunnel to destroy).
2546 delayed_destroy (void *cls)
2548 struct CadetTunnel *t = cls;
2549 struct CadetTConnection *iter;
2551 t->destroy_task = NULL;
2552 LOG (GNUNET_ERROR_TYPE_DEBUG,
2553 "delayed destroying tunnel %p\n",
2555 t->cstate = CADET_TUNNEL_SHUTDOWN;
2556 for (iter = t->connection_head; NULL != iter; iter = iter->next)
2558 GCC_send_destroy (iter->c);
2565 * Tunnel is empty: destroy it.
2567 * Notifies all connections about the destruction.
2569 * @param t Tunnel to destroy.
2572 GCT_destroy_empty (struct CadetTunnel *t)
2574 if (GNUNET_YES == shutting_down)
2575 return; /* Will be destroyed immediately anyway */
2577 if (NULL != t->destroy_task)
2579 LOG (GNUNET_ERROR_TYPE_WARNING,
2580 "Tunnel %s is already scheduled for destruction. Tunnel debug dump:\n",
2582 GCT_debug (t, GNUNET_ERROR_TYPE_WARNING);
2584 /* should never happen, tunnel can only become empty once, and the
2585 * task identifier should be NO_TASK (cleaned when the tunnel was created
2586 * or became un-empty)
2591 LOG (GNUNET_ERROR_TYPE_DEBUG, "Tunnel %s empty: scheduling destruction\n",
2594 // FIXME make delay a config option
2595 t->destroy_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_MINUTES,
2596 &delayed_destroy, t);
2597 LOG (GNUNET_ERROR_TYPE_DEBUG, "Scheduled destroy of %p as %p\n",
2598 t, t->destroy_task);
2603 * Destroy tunnel if empty (no more channels).
2605 * @param t Tunnel to destroy if empty.
2608 GCT_destroy_if_empty (struct CadetTunnel *t)
2610 LOG (GNUNET_ERROR_TYPE_DEBUG, "Tunnel %s destroy if empty\n", GCT_2s (t));
2611 if (0 < GCT_count_channels (t))
2614 GCT_destroy_empty (t);
2619 * Destroy the tunnel.
2621 * This function does not generate any warning traffic to clients or peers.
2624 * Cancel messages belonging to this tunnel queued to neighbors.
2625 * Free any allocated resources linked to the tunnel.
2627 * @param t The tunnel to destroy.
2630 GCT_destroy (struct CadetTunnel *t)
2632 struct CadetTConnection *iter_c;
2633 struct CadetTConnection *next_c;
2634 struct CadetTChannel *iter_ch;
2635 struct CadetTChannel *next_ch;
2636 unsigned int keepalives_queued;
2641 LOG (GNUNET_ERROR_TYPE_DEBUG,
2642 "destroying tunnel %s\n",
2644 GNUNET_break (GNUNET_YES ==
2645 GNUNET_CONTAINER_multipeermap_remove (tunnels,
2646 GCP_get_id (t->peer), t));
2648 for (iter_c = t->connection_head; NULL != iter_c; iter_c = next_c)
2650 next_c = iter_c->next;
2651 GCC_destroy (iter_c->c);
2653 for (iter_ch = t->channel_head; NULL != iter_ch; iter_ch = next_ch)
2655 next_ch = iter_ch->next;
2656 GCCH_destroy (iter_ch->ch);
2657 /* Should only happen on shutdown, but it's ok. */
2659 keepalives_queued = 0;
2660 while (NULL != t->tq_head)
2662 /* Should have been cleaned by destuction of channel. */
2663 struct GNUNET_MessageHeader *mh;
2666 mh = (struct GNUNET_MessageHeader *) &t->tq_head[1];
2667 type = ntohs (mh->type);
2668 if (0 == keepalives_queued && GNUNET_MESSAGE_TYPE_CADET_KEEPALIVE == type)
2670 keepalives_queued = 1;
2671 LOG (GNUNET_ERROR_TYPE_DEBUG,
2672 "one keepalive left behind on tunnel shutdown\n");
2674 else if (GNUNET_MESSAGE_TYPE_CADET_CHANNEL_DESTROY == type)
2676 LOG (GNUNET_ERROR_TYPE_WARNING,
2677 "tunnel destroyed before a CHANNEL_DESTROY was sent to peer\n");
2682 LOG (GNUNET_ERROR_TYPE_ERROR,
2683 "message left behind on tunnel shutdown: %s\n",
2686 unqueue_data (t->tq_head);
2690 if (NULL != t->destroy_task)
2692 LOG (GNUNET_ERROR_TYPE_DEBUG,
2693 "cancelling dest: %p\n",
2695 GNUNET_SCHEDULER_cancel (t->destroy_task);
2696 t->destroy_task = NULL;
2699 if (NULL != t->trim_connections_task)
2701 LOG (GNUNET_ERROR_TYPE_DEBUG, "cancelling trim: %p\n",
2702 t->trim_connections_task);
2703 GNUNET_SCHEDULER_cancel (t->trim_connections_task);
2704 t->trim_connections_task = NULL;
2707 GNUNET_STATISTICS_update (stats, "# tunnels", -1, GNUNET_NO);
2708 GCP_set_tunnel (t->peer, NULL);
2710 if (NULL != t->rekey_task)
2712 GNUNET_SCHEDULER_cancel (t->rekey_task);
2713 t->rekey_task = NULL;
2723 * @brief Use the given path for the tunnel.
2724 * Update the next and prev hops (and RCs).
2725 * (Re)start the path refresh in case the tunnel is locally owned.
2727 * @param t Tunnel to update.
2728 * @param p Path to use.
2730 * @return Connection created.
2732 struct CadetConnection *
2733 GCT_use_path (struct CadetTunnel *t, struct CadetPeerPath *path)
2735 struct CadetConnection *c;
2736 struct GNUNET_CADET_Hash cid;
2737 unsigned int own_pos;
2739 if (NULL == t || NULL == path)
2745 if (CADET_TUNNEL_SHUTDOWN == t->cstate)
2751 for (own_pos = 0; own_pos < path->length; own_pos++)
2753 if (path->peers[own_pos] == myid)
2756 if (own_pos >= path->length)
2758 GNUNET_break_op (0);
2762 GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_NONCE, &cid, sizeof (cid));
2763 c = GCC_new (&cid, t, path, own_pos);
2766 /* Path was flawed */
2769 GCT_add_connection (t, c);
2775 * Count all created connections of a tunnel. Not necessarily ready connections!
2777 * @param t Tunnel on which to count.
2779 * @return Number of connections created, either being established or ready.
2782 GCT_count_any_connections (struct CadetTunnel *t)
2784 struct CadetTConnection *iter;
2790 for (count = 0, iter = t->connection_head; NULL != iter; iter = iter->next)
2798 * Count established (ready) connections of a tunnel.
2800 * @param t Tunnel on which to count.
2802 * @return Number of connections.
2805 GCT_count_connections (struct CadetTunnel *t)
2807 struct CadetTConnection *iter;
2813 for (count = 0, iter = t->connection_head; NULL != iter; iter = iter->next)
2814 if (CADET_CONNECTION_READY == GCC_get_state (iter->c))
2822 * Count channels of a tunnel.
2824 * @param t Tunnel on which to count.
2826 * @return Number of channels.
2829 GCT_count_channels (struct CadetTunnel *t)
2831 struct CadetTChannel *iter;
2834 for (count = 0, iter = t->channel_head;
2836 iter = iter->next, count++) /* skip */;
2843 * Get the connectivity state of a tunnel.
2847 * @return Tunnel's connectivity state.
2849 enum CadetTunnelCState
2850 GCT_get_cstate (struct CadetTunnel *t)
2855 return (enum CadetTunnelCState) -1;
2862 * Get the encryption state of a tunnel.
2866 * @return Tunnel's encryption state.
2868 enum CadetTunnelEState
2869 GCT_get_estate (struct CadetTunnel *t)
2874 return (enum CadetTunnelEState) -1;
2880 * Get the maximum buffer space for a tunnel towards a local client.
2884 * @return Biggest buffer space offered by any channel in the tunnel.
2887 GCT_get_channels_buffer (struct CadetTunnel *t)
2889 struct CadetTChannel *iter;
2890 unsigned int buffer;
2891 unsigned int ch_buf;
2893 if (NULL == t->channel_head)
2895 /* Probably getting buffer for a channel create/handshake. */
2896 LOG (GNUNET_ERROR_TYPE_DEBUG, " no channels, allow max\n");
2897 return MIN_TUNNEL_BUFFER;
2901 for (iter = t->channel_head; NULL != iter; iter = iter->next)
2903 ch_buf = get_channel_buffer (iter);
2904 if (ch_buf > buffer)
2907 if (MIN_TUNNEL_BUFFER > buffer)
2908 return MIN_TUNNEL_BUFFER;
2910 if (MAX_TUNNEL_BUFFER < buffer)
2913 return MAX_TUNNEL_BUFFER;
2920 * Get the total buffer space for a tunnel for P2P traffic.
2924 * @return Buffer space offered by all connections in the tunnel.
2927 GCT_get_connections_buffer (struct CadetTunnel *t)
2929 struct CadetTConnection *iter;
2930 unsigned int buffer;
2932 if (GNUNET_NO == is_ready (t))
2934 if (count_queued_data (t) >= 3)
2941 for (iter = t->connection_head; NULL != iter; iter = iter->next)
2943 if (GCC_get_state (iter->c) != CADET_CONNECTION_READY)
2947 buffer += get_connection_buffer (iter);
2955 * Get the tunnel's destination.
2959 * @return ID of the destination peer.
2961 const struct GNUNET_PeerIdentity *
2962 GCT_get_destination (struct CadetTunnel *t)
2964 return GCP_get_id (t->peer);
2969 * Get the tunnel's next free global channel ID.
2973 * @return GID of a channel free to use.
2976 GCT_get_next_chid (struct CadetTunnel *t)
2978 CADET_ChannelNumber chid;
2979 CADET_ChannelNumber mask;
2982 /* Set bit 30 depending on the ID relationship. Bit 31 is always 0 for GID.
2983 * If our ID is bigger or loopback tunnel, start at 0, bit 30 = 0
2984 * If peer's ID is bigger, start at 0x4... bit 30 = 1
2986 result = GNUNET_CRYPTO_cmp_peer_identity (&my_full_id, GCP_get_id (t->peer));
2991 t->next_chid |= mask;
2993 while (NULL != GCT_get_channel (t, t->next_chid))
2995 LOG (GNUNET_ERROR_TYPE_DEBUG, "Channel %u exists...\n", t->next_chid);
2996 t->next_chid = (t->next_chid + 1) & ~GNUNET_CADET_LOCAL_CHANNEL_ID_CLI;
2997 t->next_chid |= mask;
2999 chid = t->next_chid;
3000 t->next_chid = (t->next_chid + 1) & ~GNUNET_CADET_LOCAL_CHANNEL_ID_CLI;
3001 t->next_chid |= mask;
3008 * Send ACK on one or more channels due to buffer in connections.
3010 * @param t Channel which has some free buffer space.
3013 GCT_unchoke_channels (struct CadetTunnel *t)
3015 struct CadetTChannel *iter;
3016 unsigned int buffer;
3017 unsigned int channels = GCT_count_channels (t);
3018 unsigned int choked_n;
3019 struct CadetChannel *choked[channels];
3021 LOG (GNUNET_ERROR_TYPE_DEBUG, "GCT_unchoke_channels on %s\n", GCT_2s (t));
3022 LOG (GNUNET_ERROR_TYPE_DEBUG, " head: %p\n", t->channel_head);
3023 if (NULL != t->channel_head)
3024 LOG (GNUNET_ERROR_TYPE_DEBUG, " head ch: %p\n", t->channel_head->ch);
3026 if (NULL != t->tq_head)
3027 send_queued_data (t);
3029 /* Get buffer space */
3030 buffer = GCT_get_connections_buffer (t);
3036 /* Count and remember choked channels */
3038 for (iter = t->channel_head; NULL != iter; iter = iter->next)
3040 if (GNUNET_NO == get_channel_allowed (iter))
3042 choked[choked_n++] = iter->ch;
3046 /* Unchoke random channels */
3047 while (0 < buffer && 0 < choked_n)
3049 unsigned int r = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
3051 GCCH_allow_client (choked[r], GCCH_is_origin (choked[r], GNUNET_YES));
3054 choked[r] = choked[choked_n];
3060 * Send ACK on one or more connections due to buffer space to the client.
3062 * Iterates all connections of the tunnel and sends ACKs appropriately.
3067 GCT_send_connection_acks (struct CadetTunnel *t)
3069 struct CadetTConnection *iter;
3072 uint32_t allow_per_connection;
3074 unsigned int buffer;
3076 LOG (GNUNET_ERROR_TYPE_DEBUG, "Tunnel send connection ACKs on %s\n",
3085 if (CADET_TUNNEL_READY != t->cstate)
3088 buffer = GCT_get_channels_buffer (t);
3089 LOG (GNUNET_ERROR_TYPE_DEBUG, " buffer %u\n", buffer);
3091 /* Count connections, how many messages are already allowed */
3092 cs = GCT_count_connections (t);
3093 for (allowed = 0, iter = t->connection_head; NULL != iter; iter = iter->next)
3095 allowed += get_connection_allowed (iter);
3097 LOG (GNUNET_ERROR_TYPE_DEBUG, " allowed %u\n", allowed);
3099 /* Make sure there is no overflow */
3100 if (allowed > buffer)
3103 /* Authorize connections to send more data */
3104 to_allow = buffer - allowed;
3106 for (iter = t->connection_head;
3107 NULL != iter && to_allow > 0;
3110 if (CADET_CONNECTION_READY != GCC_get_state (iter->c)
3111 || get_connection_allowed (iter) > 64 / 3)
3115 GNUNET_assert(cs != 0);
3116 allow_per_connection = to_allow/cs;
3117 to_allow -= allow_per_connection;
3119 GCC_allow (iter->c, allow_per_connection,
3120 GCC_is_origin (iter->c, GNUNET_NO));
3125 /* Since we don't allow if it's allowed to send 64/3, this can happen. */
3126 LOG (GNUNET_ERROR_TYPE_DEBUG, " reminding to_allow: %u\n", to_allow);
3132 * Cancel a previously sent message while it's in the queue.
3134 * ONLY can be called before the continuation given to the send function
3135 * is called. Once the continuation is called, the message is no longer in the
3138 * @param q Handle to the queue.
3141 GCT_cancel (struct CadetTunnelQueue *q)
3145 GNUNET_assert (NULL == q->tqd);
3147 /* tun_message_sent() will be called and free q */
3149 else if (NULL != q->tqd)
3151 unqueue_data (q->tqd);
3153 if (NULL != q->cont)
3154 q->cont (q->cont_cls, NULL, q, 0, 0);
3165 * Check if the tunnel has queued traffic.
3167 * @param t Tunnel to check.
3169 * @return #GNUNET_YES if there is queued traffic
3170 * #GNUNET_NO otherwise
3173 GCT_has_queued_traffic (struct CadetTunnel *t)
3175 return (NULL != t->tq_head) ? GNUNET_YES : GNUNET_NO;
3180 * Sends an already built message on a tunnel, encrypting it and
3181 * choosing the best connection if not provided.
3183 * @param message Message to send. Function modifies it.
3184 * @param t Tunnel on which this message is transmitted.
3185 * @param c Connection to use (autoselect if NULL).
3186 * @param force Force the tunnel to take the message (buffer overfill).
3187 * @param cont Continuation to call once message is really sent.
3188 * @param cont_cls Closure for @c cont.
3190 * @return Handle to cancel message. NULL if @c cont is NULL.
3192 struct CadetTunnelQueue *
3193 GCT_send_prebuilt_message (const struct GNUNET_MessageHeader *message,
3194 struct CadetTunnel *t, struct CadetConnection *c,
3195 int force, GCT_sent cont, void *cont_cls)
3197 return send_prebuilt_message (message, t, c, force, cont, cont_cls, NULL);
3202 * Send a KX message.
3204 * @param t Tunnel on which to send it.
3205 * @param force_reply Force the other peer to reply with a KX message.
3208 GCT_send_kx (struct CadetTunnel *t, int force_reply)
3210 struct CadetConnection *c;
3211 struct GNUNET_CADET_KX msg;
3212 enum GNUNET_CADET_KX_Flags flags;
3214 LOG (GNUNET_ERROR_TYPE_INFO, "==> { KX} on %s\n", GCT_2s (t));
3215 if (NULL != t->ephm_h)
3217 LOG (GNUNET_ERROR_TYPE_INFO, " already queued, nop\n");
3220 GNUNET_assert (GNUNET_NO == GCT_is_loopback (t));
3222 c = tunnel_get_connection (t);
3225 if (NULL == t->destroy_task && CADET_TUNNEL_READY == t->cstate)
3228 GCT_debug (t, GNUNET_ERROR_TYPE_ERROR);
3233 msg.header.size = htons (sizeof (msg));
3234 msg.header.type = htons (GNUNET_MESSAGE_TYPE_CADET_KX);
3235 flags = GNUNET_CADET_KX_FLAG_NONE;
3236 if (GNUNET_YES == force_reply)
3237 flags |= GNUNET_CADET_KX_FLAG_FORCE_REPLY;
3238 msg.flags = htonl (flags);
3239 msg.cid = *GCC_get_id (c);
3240 GNUNET_CRYPTO_ecdhe_key_get_public (t->ax->kx_0, &msg.ephemeral_key);
3241 GNUNET_CRYPTO_ecdhe_key_get_public (t->ax->DHRs, &msg.ratchet_key);
3243 t->ephm_h = GCC_send_prebuilt_message (&msg.header, 0, 0,
3244 c, GCC_is_origin (c, GNUNET_YES),
3245 GNUNET_YES, &ephm_sent, t);
3246 if (CADET_TUNNEL_KEY_UNINITIALIZED == t->estate)
3247 GCT_change_estate (t, CADET_TUNNEL_KEY_SENT);
3252 * Is the tunnel directed towards the local peer?
3256 * @return #GNUNET_YES if it is loopback.
3259 GCT_is_loopback (const struct CadetTunnel *t)
3261 return (myid == GCP_get_short_id (t->peer));
3266 * Is the tunnel this path already?
3271 * @return #GNUNET_YES a connection uses this path.
3274 GCT_is_path_used (const struct CadetTunnel *t, const struct CadetPeerPath *p)
3276 struct CadetTConnection *iter;
3278 for (iter = t->connection_head; NULL != iter; iter = iter->next)
3279 if (path_equivalent (GCC_get_path (iter->c), p))
3287 * Get a cost of a path for a tunnel considering existing connections.
3290 * @param path Candidate path.
3292 * @return Cost of the path (path length + number of overlapping nodes)
3295 GCT_get_path_cost (const struct CadetTunnel *t,
3296 const struct CadetPeerPath *path)
3298 struct CadetTConnection *iter;
3299 const struct CadetPeerPath *aux;
3300 unsigned int overlap;
3308 GNUNET_assert (NULL != t);
3310 for (i = 0; i < path->length; i++)
3312 for (iter = t->connection_head; NULL != iter; iter = iter->next)
3314 aux = GCC_get_path (iter->c);
3318 for (j = 0; j < aux->length; j++)
3320 if (path->peers[i] == aux->peers[j])
3328 return path->length + overlap;
3333 * Get the static string for the peer this tunnel is directed.
3337 * @return Static string the destination peer's ID.
3340 GCT_2s (const struct CadetTunnel *t)
3345 return GCP_2s (t->peer);
3349 /******************************************************************************/
3350 /***************************** INFO/DEBUG *******************************/
3351 /******************************************************************************/
3354 ax_debug (const struct CadetTunnelAxolotl *ax, enum GNUNET_ErrorType level)
3356 struct GNUNET_CRYPTO_EcdhePublicKey pub;
3357 struct CadetTunnelSkippedKey *iter;
3359 LOG2 (level, "TTT RK \t %s\n",
3360 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->RK));
3362 LOG2 (level, "TTT HKs \t %s\n",
3363 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->HKs));
3364 LOG2 (level, "TTT HKr \t %s\n",
3365 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->HKr));
3366 LOG2 (level, "TTT NHKs\t %s\n",
3367 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->NHKs));
3368 LOG2 (level, "TTT NHKr\t %s\n",
3369 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->NHKr));
3371 LOG2 (level, "TTT CKs \t %s\n",
3372 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->CKs));
3373 LOG2 (level, "TTT CKr \t %s\n",
3374 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->CKr));
3376 GNUNET_CRYPTO_ecdhe_key_get_public (ax->DHRs, &pub);
3377 LOG2 (level, "TTT DHRs\t %s\n",
3378 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &pub));
3379 LOG2 (level, "TTT DHRr\t %s\n",
3380 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &ax->DHRr));
3382 LOG2 (level, "TTT Nr\t %u\tNs\t%u\n", ax->Nr, ax->Ns);
3383 LOG2 (level, "TTT PNs\t %u\tSkipped\t%u\n", ax->PNs, ax->skipped);
3384 LOG2 (level, "TTT Ratchet\t%u\n", ax->ratchet_flag);
3386 for (iter = ax->skipped_head; NULL != iter; iter = iter->next)
3388 LOG2 (level, "TTT HK\t %s\n",
3389 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &iter->HK));
3390 LOG2 (level, "TTT MK\t %s\n",
3391 GNUNET_i2s ((struct GNUNET_PeerIdentity *) &iter->MK));
3396 * Log all possible info about the tunnel state.
3398 * @param t Tunnel to debug.
3399 * @param level Debug level to use.
3402 GCT_debug (const struct CadetTunnel *t, enum GNUNET_ErrorType level)
3404 struct CadetTChannel *iter_ch;
3405 struct CadetTConnection *iter_c;
3408 do_log = GNUNET_get_log_call_status (level & (~GNUNET_ERROR_TYPE_BULK),
3410 __FILE__, __FUNCTION__, __LINE__);
3414 LOG2 (level, "TTT DEBUG TUNNEL TOWARDS %s\n", GCT_2s (t));
3415 LOG2 (level, "TTT cstate %s, estate %s\n",
3416 cstate2s (t->cstate), estate2s (t->estate));
3417 #if DUMP_KEYS_TO_STDERR
3418 ax_debug (t->ax, level);
3420 LOG2 (level, "TTT tq_head %p, tq_tail %p\n", t->tq_head, t->tq_tail);
3421 LOG2 (level, "TTT destroy %p\n", t->destroy_task);
3422 LOG2 (level, "TTT channels:\n");
3423 for (iter_ch = t->channel_head; NULL != iter_ch; iter_ch = iter_ch->next)
3425 GCCH_debug (iter_ch->ch, level);
3428 LOG2 (level, "TTT connections:\n");
3429 for (iter_c = t->connection_head; NULL != iter_c; iter_c = iter_c->next)
3431 GCC_debug (iter_c->c, level);
3434 LOG2 (level, "TTT DEBUG TUNNEL END\n");
3439 * Iterate all tunnels.
3441 * @param iter Iterator.
3442 * @param cls Closure for @c iter.
3445 GCT_iterate_all (GNUNET_CONTAINER_PeerMapIterator iter, void *cls)
3447 GNUNET_CONTAINER_multipeermap_iterate (tunnels, iter, cls);
3452 * Count all tunnels.
3454 * @return Number of tunnels to remote peers kept by this peer.
3457 GCT_count_all (void)
3459 return GNUNET_CONTAINER_multipeermap_size (tunnels);
3464 * Iterate all connections of a tunnel.
3466 * @param t Tunnel whose connections to iterate.
3467 * @param iter Iterator.
3468 * @param cls Closure for @c iter.
3471 GCT_iterate_connections (struct CadetTunnel *t, GCT_conn_iter iter, void *cls)
3473 struct CadetTConnection *ct;
3475 for (ct = t->connection_head; NULL != ct; ct = ct->next)
3481 * Iterate all channels of a tunnel.
3483 * @param t Tunnel whose channels to iterate.
3484 * @param iter Iterator.
3485 * @param cls Closure for @c iter.
3488 GCT_iterate_channels (struct CadetTunnel *t, GCT_chan_iter iter, void *cls)
3490 struct CadetTChannel *cht;
3492 for (cht = t->channel_head; NULL != cht; cht = cht->next)
3493 iter (cls, cht->ch);