2 This file is part of GNUnet.
3 (C) 2009, 2010, 2011, 2012 Christian Grothoff (and other contributing authors)
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., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file core/gnunet-service-core_kx.c
23 * @brief code for managing the key exchange (SET_KEY, PING, PONG) with other peers
24 * @author Christian Grothoff
27 #include "gnunet-service-core_kx.h"
28 #include "gnunet-service-core.h"
29 #include "gnunet-service-core_clients.h"
30 #include "gnunet-service-core_neighbours.h"
31 #include "gnunet-service-core_sessions.h"
32 #include "gnunet_statistics_service.h"
33 #include "gnunet_constants.h"
34 #include "gnunet_signatures.h"
35 #include "gnunet_protocols.h"
40 * How long do we wait for SET_KEY confirmation initially?
42 #define INITIAL_SET_KEY_RETRY_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10)
45 * What is the minimum frequency for a PING message?
47 #define MIN_PING_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
50 * How often do we rekey?
52 #define REKEY_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 12)
55 * What time difference do we tolerate?
57 #define REKEY_TOLERANCE GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)
60 * What is the maximum age of a message for us to consider processing
61 * it? Note that this looks at the timestamp used by the other peer,
62 * so clock skew between machines does come into play here. So this
63 * should be picked high enough so that a little bit of clock skew
64 * does not prevent peers from connecting to us.
66 #define MAX_MESSAGE_AGE GNUNET_TIME_UNIT_DAYS
70 GNUNET_NETWORK_STRUCT_BEGIN
73 * Message transmitted with the signed ephemeral key of a peer. The
74 * session key is then derived from the two ephemeral keys (ECDHE).
76 struct EphemeralKeyMessage
80 * Message type is CORE_EPHEMERAL_KEY.
82 struct GNUNET_MessageHeader header;
85 * Status of the sender (should be in "enum PeerStateMachine"), nbo.
87 int32_t sender_status GNUNET_PACKED;
90 * An ECC signature of the 'origin' asserting the validity of
91 * the given ephemeral key.
93 struct GNUNET_CRYPTO_EccSignature signature;
96 * Information about what is being signed.
98 struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
101 * At what time was this key created (beginning of validity).
103 struct GNUNET_TIME_AbsoluteNBO creation_time;
106 * When does the given ephemeral key expire (end of validity).
108 struct GNUNET_TIME_AbsoluteNBO expiration_time;
111 * Ephemeral public ECC key (always for NIST P-521) encoded in a format suitable
112 * for network transmission as created using 'gcry_sexp_sprint'.
114 struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded ephemeral_key;
117 * Public key of the signing peer (persistent version, not the ephemeral public key).
119 struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded origin_public_key;
125 * We're sending an (encrypted) PING to the other peer to check if he
126 * can decrypt. The other peer should respond with a PONG with the
127 * same content, except this time encrypted with the receiver's key.
132 * Message type is CORE_PING.
134 struct GNUNET_MessageHeader header;
139 uint32_t iv_seed GNUNET_PACKED;
142 * Intended target of the PING, used primarily to check
143 * that decryption actually worked.
145 struct GNUNET_PeerIdentity target;
148 * Random number chosen to make reply harder.
150 uint32_t challenge GNUNET_PACKED;
155 * Response to a PING. Includes data from the original PING.
160 * Message type is CORE_PONG.
162 struct GNUNET_MessageHeader header;
167 uint32_t iv_seed GNUNET_PACKED;
170 * Random number to make faking the reply harder. Must be
171 * first field after header (this is where we start to encrypt!).
173 uint32_t challenge GNUNET_PACKED;
176 * Reserved, always zero.
181 * Intended target of the PING, used primarily to check
182 * that decryption actually worked.
184 struct GNUNET_PeerIdentity target;
189 * Encapsulation for encrypted messages exchanged between
190 * peers. Followed by the actual encrypted data.
192 struct EncryptedMessage
195 * Message type is either CORE_ENCRYPTED_MESSAGE.
197 struct GNUNET_MessageHeader header;
200 * Random value used for IV generation.
202 uint32_t iv_seed GNUNET_PACKED;
205 * MAC of the encrypted message (starting at 'sequence_number'),
206 * used to verify message integrity. Everything after this value
207 * (excluding this value itself) will be encrypted and authenticated.
208 * ENCRYPTED_HEADER_SIZE must be set to the offset of the *next* field.
210 struct GNUNET_HashCode hmac;
213 * Sequence number, in network byte order. This field
214 * must be the first encrypted/decrypted field
216 uint32_t sequence_number GNUNET_PACKED;
219 * Reserved, always zero.
224 * Timestamp. Used to prevent reply of ancient messages
225 * (recent messages are caught with the sequence number).
227 struct GNUNET_TIME_AbsoluteNBO timestamp;
230 GNUNET_NETWORK_STRUCT_END
234 * Number of bytes (at the beginning) of "struct EncryptedMessage"
235 * that are NOT encrypted.
237 #define ENCRYPTED_HEADER_SIZE (offsetof(struct EncryptedMessage, sequence_number))
241 * State machine for our P2P encryption handshake. Everyone starts in
242 * "DOWN", if we receive the other peer's key (other peer initiated)
243 * we start in state RECEIVED (since we will immediately send our
244 * own); otherwise we start in SENT. If we get back a PONG from
245 * within either state, we move up to CONFIRMED (the PONG will always
246 * be sent back encrypted with the key we sent to the other peer).
256 * We've sent our session key.
261 * We've received the other peers session key.
263 KX_STATE_KEY_RECEIVED,
266 * The other peer has confirmed our session key + PING with a PONG
267 * message encrypted with his session key (which we got). Key
273 * We're rekeying, so we have sent the other peer our new ephemeral
274 * key, but we did not get a matching PONG yet.
282 * Information about the status of a key exchange with another peer.
284 struct GSC_KeyExchangeInfo
290 struct GSC_KeyExchangeInfo *next;
295 struct GSC_KeyExchangeInfo *prev;
298 * Identity of the peer.
300 struct GNUNET_PeerIdentity peer;
303 * PING message we transmit to the other peer.
305 struct PingMessage ping;
308 * Key we use to encrypt our messages for the other peer
309 * (initialized by us when we do the handshake).
311 struct GNUNET_CRYPTO_AesSessionKey encrypt_key;
314 * Key we use to decrypt messages from the other peer
315 * (given to us by the other peer during the handshake).
317 struct GNUNET_CRYPTO_AesSessionKey decrypt_key;
320 * At what time did the other peer generate the decryption key?
322 struct GNUNET_TIME_Absolute foreign_key_expires;
325 * When should the session time out (if there are no PONGs)?
327 struct GNUNET_TIME_Absolute timeout;
330 * At what frequency are we currently re-trying SET_KEY messages?
332 struct GNUNET_TIME_Relative set_key_retry_frequency;
335 * ID of task used for re-trying SET_KEY and PING message.
337 GNUNET_SCHEDULER_TaskIdentifier retry_set_key_task;
340 * ID of task used for sending keep-alive pings.
342 GNUNET_SCHEDULER_TaskIdentifier keep_alive_task;
345 * Bit map indicating which of the 32 sequence numbers before the last
346 * were received (good for accepting out-of-order packets and
347 * estimating reliability of the connection)
349 unsigned int last_packets_bitmap;
352 * last sequence number received on this connection (highest)
354 uint32_t last_sequence_number_received;
357 * last sequence number transmitted
359 uint32_t last_sequence_number_sent;
362 * What was our PING challenge number (for this peer)?
364 uint32_t ping_challenge;
367 * What is our connection status?
369 enum KxStateMachine status;
377 static struct GNUNET_CRYPTO_EccPrivateKey *my_private_key;
380 * Our ephemeral private key.
382 static struct GNUNET_CRYPTO_EccPrivateKey *my_ephemeral_key;
385 * Current message we send for a key exchange.
387 static struct EphemeralKeyMessage current_ekm;
392 static struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded my_public_key;
395 * Our message stream tokenizer (for encrypted payload).
397 static struct GNUNET_SERVER_MessageStreamTokenizer *mst;
402 static struct GSC_KeyExchangeInfo *kx_head;
407 static struct GSC_KeyExchangeInfo *kx_tail;
410 * Task scheduled for periodic re-generation (and thus rekeying) of our
413 static GNUNET_SCHEDULER_TaskIdentifier rekey_task;
417 * Derive an authentication key from "set key" information
419 * @param akey authentication key to derive
420 * @param skey session key to use
421 * @param seed seed to use
424 derive_auth_key (struct GNUNET_CRYPTO_AuthKey *akey,
425 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed)
427 static const char ctx[] = "authentication key";
429 GNUNET_CRYPTO_hmac_derive_key (akey, skey, &seed, sizeof (seed), &skey->key,
430 sizeof (skey->key), ctx,
436 * Derive an IV from packet information
438 * @param iv initialization vector to initialize
439 * @param skey session key to use
440 * @param seed seed to use
441 * @param identity identity of the other peer to use
444 derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
445 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
446 const struct GNUNET_PeerIdentity *identity)
448 static const char ctx[] = "initialization vector";
450 GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
451 &identity->hashPubKey.bits,
452 sizeof (identity->hashPubKey.bits), ctx,
458 * Derive an IV from pong packet information
460 * @param iv initialization vector to initialize
461 * @param skey session key to use
462 * @param seed seed to use
463 * @param challenge nonce to use
464 * @param identity identity of the other peer to use
467 derive_pong_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
468 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
469 uint32_t challenge, const struct GNUNET_PeerIdentity *identity)
471 static const char ctx[] = "pong initialization vector";
473 GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
474 &identity->hashPubKey.bits,
475 sizeof (identity->hashPubKey.bits), &challenge,
476 sizeof (challenge), ctx, sizeof (ctx), NULL);
481 * Derive an AES key from key material
483 * @param sender peer identity of the sender
484 * @param receiver peer identity of the sender
485 * @param key_material high entropy key material to use
486 * @param skey set to derived session key
489 derive_aes_key (const struct GNUNET_PeerIdentity *sender,
490 const struct GNUNET_PeerIdentity *receiver,
491 const struct GNUNET_HashCode *key_material,
492 struct GNUNET_CRYPTO_AesSessionKey *skey)
494 static const char ctx[] = "aes key generation vector";
496 GNUNET_CRYPTO_kdf (skey, sizeof (struct GNUNET_CRYPTO_AesSessionKey),
498 skey, sizeof (struct GNUNET_CRYPTO_AesSessionKey),
499 sender, sizeof (struct GNUNET_PeerIdentity),
500 receiver, sizeof (struct GNUNET_PeerIdentity),
506 * Encrypt size bytes from in and write the result to out. Use the
507 * key for outbound traffic of the given neighbour.
509 * @param kx key information context
510 * @param iv initialization vector to use
511 * @param in ciphertext
512 * @param out plaintext
513 * @param size size of in/out
514 * @return GNUNET_OK on success
517 do_encrypt (struct GSC_KeyExchangeInfo *kx,
518 const struct GNUNET_CRYPTO_AesInitializationVector *iv,
519 const void *in, void *out, size_t size)
521 if (size != (uint16_t) size)
526 GNUNET_assert (size ==
527 GNUNET_CRYPTO_aes_encrypt (in, (uint16_t) size,
528 &kx->encrypt_key, iv, out));
529 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# bytes encrypted"), size,
531 /* the following is too sensitive to write to log files by accident,
532 so we require manual intervention to get this one... */
534 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
535 "Encrypted %u bytes for `%4s' using key %u, IV %u\n",
536 (unsigned int) size, GNUNET_i2s (&kx->peer),
537 (unsigned int) kx->encrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
546 * Decrypt size bytes from in and write the result to out. Use the
547 * key for inbound traffic of the given neighbour. This function does
548 * NOT do any integrity-checks on the result.
550 * @param kx key information context
551 * @param iv initialization vector to use
552 * @param in ciphertext
553 * @param out plaintext
554 * @param size size of in/out
555 * @return GNUNET_OK on success
558 do_decrypt (struct GSC_KeyExchangeInfo *kx,
559 const struct GNUNET_CRYPTO_AesInitializationVector *iv,
560 const void *in, void *out, size_t size)
562 if (size != (uint16_t) size)
567 if ( (kx->status != KX_STATE_KEY_RECEIVED) && (kx->status != KX_STATE_UP) &&
568 (kx->status != KX_STATE_REKEY_SENT) )
571 return GNUNET_SYSERR;
574 GNUNET_CRYPTO_aes_decrypt (in, (uint16_t) size, &kx->decrypt_key, iv,
578 return GNUNET_SYSERR;
580 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# bytes decrypted"), size,
582 /* the following is too sensitive to write to log files by accident,
583 so we require manual intervention to get this one... */
585 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
586 "Decrypted %u bytes from `%4s' using key %u, IV %u\n",
587 (unsigned int) size, GNUNET_i2s (&kx->peer),
588 (unsigned int) kx->decrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
597 * Send our key (and encrypted PING) to the other peer.
599 * @param kx key exchange context
602 send_key (struct GSC_KeyExchangeInfo *kx);
606 * Task that will retry "send_key" if our previous attempt failed.
608 * @param cls our 'struct GSC_KeyExchangeInfo'
609 * @param tc scheduler context
612 set_key_retry_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
614 struct GSC_KeyExchangeInfo *kx = cls;
616 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
617 kx->set_key_retry_frequency = GNUNET_TIME_STD_BACKOFF (kx->set_key_retry_frequency);
623 * Create a fresh PING message for transmission to the other peer.
625 * @param kx key exchange context to create PING for
628 setup_fresh_ping (struct GSC_KeyExchangeInfo *kx)
630 struct PingMessage pp;
631 struct PingMessage *pm;
632 struct GNUNET_CRYPTO_AesInitializationVector iv;
635 pm->header.size = htons (sizeof (struct PingMessage));
636 pm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PING);
638 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
639 derive_iv (&iv, &kx->encrypt_key, pm->iv_seed, &kx->peer);
640 pp.challenge = kx->ping_challenge;
641 pp.target = kx->peer;
642 do_encrypt (kx, &iv, &pp.target, &pm->target,
643 sizeof (struct PingMessage) - ((void *) &pm->target -
649 * Start the key exchange with the given peer.
651 * @param pid identity of the peer to do a key exchange with
652 * @return key exchange information context
654 struct GSC_KeyExchangeInfo *
655 GSC_KX_start (const struct GNUNET_PeerIdentity *pid)
657 struct GSC_KeyExchangeInfo *kx;
659 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
660 "Initiating key exchange with `%s'\n",
662 GNUNET_STATISTICS_update (GSC_stats,
663 gettext_noop ("# key exchanges initiated"), 1,
665 kx = GNUNET_malloc (sizeof (struct GSC_KeyExchangeInfo));
667 kx->set_key_retry_frequency = INITIAL_SET_KEY_RETRY_FREQUENCY;
668 GNUNET_CONTAINER_DLL_insert (kx_head,
671 kx->status = KX_STATE_KEY_SENT;
678 * Stop key exchange with the given peer. Clean up key material.
680 * @param kx key exchange to stop
683 GSC_KX_stop (struct GSC_KeyExchangeInfo *kx)
685 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# key exchanges stopped"),
687 if (kx->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK)
689 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
690 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
692 if (kx->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
694 GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
695 kx->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
697 GNUNET_CONTAINER_DLL_remove (kx_head,
705 * Send our PING to the other peer.
707 * @param kx key exchange context
710 send_ping (struct GSC_KeyExchangeInfo *kx)
712 GSC_NEIGHBOURS_transmit (&kx->peer, &kx->ping.header,
717 * We received a SET_KEY message. Validate and update
718 * our key material and status.
720 * @param kx key exchange status for the corresponding peer
721 * @param msg the set key message we received
724 GSC_KX_handle_ephemeral_key (struct GSC_KeyExchangeInfo *kx,
725 const struct GNUNET_MessageHeader *msg)
727 const struct EphemeralKeyMessage *m;
728 struct GNUNET_TIME_Absolute start_t;
729 struct GNUNET_TIME_Absolute end_t;
730 struct GNUNET_TIME_Absolute now;
731 struct GNUNET_PeerIdentity signer_id;
732 enum KxStateMachine sender_status;
734 struct GNUNET_HashCode key_material;
736 size = ntohs (msg->size);
737 if (sizeof (struct EphemeralKeyMessage) != size)
742 m = (const struct EphemeralKeyMessage *) msg;
743 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# ephemeral keys received"),
746 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
747 "Core service receives `%s' request from `%4s'.\n", "EPHEMERAL_KEY",
748 GNUNET_i2s (&kx->peer));
749 GNUNET_CRYPTO_hash (&m->origin_public_key,
750 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded),
751 &signer_id.hashPubKey);
753 memcmp (&signer_id, &kx->peer,
754 sizeof (struct GNUNET_PeerIdentity)))
759 if ((ntohl (m->purpose.size) !=
760 sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
761 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
762 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
763 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded) +
764 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded)) ||
766 GNUNET_CRYPTO_ecc_verify (GNUNET_SIGNATURE_PURPOSE_SET_ECC_KEY,
768 &m->signature, &m->origin_public_key)))
770 /* invalid signature */
774 start_t = GNUNET_TIME_absolute_ntoh (m->creation_time);
775 end_t = GNUNET_TIME_absolute_ntoh (m->expiration_time);
776 now = GNUNET_TIME_absolute_get ();
777 if ( (end_t.abs_value < GNUNET_TIME_absolute_subtract (now, REKEY_TOLERANCE).abs_value) ||
778 (start_t.abs_value > GNUNET_TIME_absolute_add (now, REKEY_TOLERANCE).abs_value) )
780 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
781 _("Ephemeral key message rejected as its validity range does not match our system time (%llu not in [%llu,%llu]).\n"),
788 GNUNET_CRYPTO_ecc_ecdh (my_ephemeral_key,
795 GNUNET_STATISTICS_update (GSC_stats,
796 gettext_noop ("# EPHEMERAL_KEY messages decrypted"), 1,
798 derive_aes_key (&GSC_my_identity,
802 derive_aes_key (&kx->peer,
806 /* fresh key, reset sequence numbers */
807 kx->last_sequence_number_received = 0;
808 kx->last_packets_bitmap = 0;
809 kx->foreign_key_expires = end_t;
810 setup_fresh_ping (kx);
812 /* check if we still need to send the sender our key */
813 sender_status = (enum KxStateMachine) ntohl (m->sender_status);
814 switch (sender_status)
817 /* makes no sense, should be at least KX_STATE_KEY_SENT */
820 case KX_STATE_KEY_SENT:
823 case KX_STATE_KEY_RECEIVED:
825 case KX_STATE_REKEY_SENT:
826 /* other peer already got our key */
832 /* check if we need to confirm everything is fine via PING + PONG */
836 kx->status = KX_STATE_KEY_RECEIVED;
839 case KX_STATE_KEY_SENT:
840 kx->status = KX_STATE_KEY_RECEIVED;
843 case KX_STATE_KEY_RECEIVED:
847 kx->status = KX_STATE_REKEY_SENT;
848 /* we got a new key, need to reconfirm! */
851 case KX_STATE_REKEY_SENT:
852 kx->status = KX_STATE_REKEY_SENT;
853 /* we got a new key, need to reconfirm! */
864 * We received a PING message. Validate and transmit
867 * @param kx key exchange status for the corresponding peer
868 * @param msg the encrypted PING message itself
871 GSC_KX_handle_ping (struct GSC_KeyExchangeInfo *kx,
872 const struct GNUNET_MessageHeader *msg)
874 const struct PingMessage *m;
875 struct PingMessage t;
876 struct PongMessage tx;
877 struct PongMessage tp;
878 struct GNUNET_CRYPTO_AesInitializationVector iv;
881 msize = ntohs (msg->size);
882 if (msize != sizeof (struct PingMessage))
887 GNUNET_STATISTICS_update (GSC_stats,
888 gettext_noop ("# PING messages received"), 1,
890 if ( (kx->status != KX_STATE_KEY_RECEIVED) &&
891 (kx->status != KX_STATE_UP) &&
892 (kx->status != KX_STATE_REKEY_SENT))
895 GNUNET_STATISTICS_update (GSC_stats,
896 gettext_noop ("# PING messages dropped (out of order)"), 1,
900 m = (const struct PingMessage *) msg;
901 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
902 "Core service receives `%s' request from `%4s'.\n", "PING",
903 GNUNET_i2s (&kx->peer));
904 derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
906 do_decrypt (kx, &iv, &m->target, &t.target,
907 sizeof (struct PingMessage) - ((void *) &m->target -
914 memcmp (&t.target, &GSC_my_identity, sizeof (struct GNUNET_PeerIdentity)))
919 GNUNET_snprintf (sender, sizeof (sender), "%8s", GNUNET_i2s (&kx->peer));
920 GNUNET_snprintf (peer, sizeof (peer), "%8s", GNUNET_i2s (&t.target));
921 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
923 ("Received PING from `%s' for different identity: I am `%s', PONG identity: `%s'\n"),
924 sender, GNUNET_i2s (&GSC_my_identity), peer);
930 tx.challenge = t.challenge;
931 tx.target = t.target;
932 tp.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PONG);
933 tp.header.size = htons (sizeof (struct PongMessage));
935 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
936 derive_pong_iv (&iv, &kx->encrypt_key, tp.iv_seed, t.challenge, &kx->peer);
937 do_encrypt (kx, &iv, &tx.challenge, &tp.challenge,
938 sizeof (struct PongMessage) - ((void *) &tp.challenge -
940 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# PONG messages created"),
942 GSC_NEIGHBOURS_transmit (&kx->peer, &tp.header,
943 GNUNET_TIME_UNIT_FOREVER_REL /* FIXME: timeout */ );
948 * Task triggered when a neighbour entry is about to time out
949 * (and we should prevent this by sending a PING).
951 * @param cls the 'struct GSC_KeyExchangeInfo'
952 * @param tc scheduler context (not used)
955 send_keep_alive (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
957 struct GSC_KeyExchangeInfo *kx = cls;
958 struct GNUNET_TIME_Relative retry;
959 struct GNUNET_TIME_Relative left;
961 kx->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
962 left = GNUNET_TIME_absolute_get_remaining (kx->timeout);
963 if (0 == left.rel_value)
965 GNUNET_STATISTICS_update (GSC_stats,
966 gettext_noop ("# sessions terminated by timeout"),
968 GSC_SESSIONS_end (&kx->peer);
969 kx->status = KX_STATE_KEY_SENT;
973 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sending KEEPALIVE to `%s'\n",
974 GNUNET_i2s (&kx->peer));
975 GNUNET_STATISTICS_update (GSC_stats,
976 gettext_noop ("# keepalive messages sent"), 1,
978 setup_fresh_ping (kx);
979 GSC_NEIGHBOURS_transmit (&kx->peer, &kx->ping.header,
980 kx->set_key_retry_frequency);
982 GNUNET_TIME_relative_max (GNUNET_TIME_relative_divide (left, 2),
984 kx->keep_alive_task =
985 GNUNET_SCHEDULER_add_delayed (retry, &send_keep_alive, kx);
990 * We've seen a valid message from the other peer.
991 * Update the time when the session would time out
992 * and delay sending our keep alive message further.
994 * @param kx key exchange where we saw activity
997 update_timeout (struct GSC_KeyExchangeInfo *kx)
1000 GNUNET_TIME_relative_to_absolute
1001 (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
1002 if (kx->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
1003 GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
1004 kx->keep_alive_task =
1005 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_divide
1006 (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
1007 2), &send_keep_alive, kx);
1012 * We received a PONG message. Validate and update our status.
1014 * @param kx key exchange context for the the PONG
1015 * @param msg the encrypted PONG message itself
1018 GSC_KX_handle_pong (struct GSC_KeyExchangeInfo *kx,
1019 const struct GNUNET_MessageHeader *msg)
1021 const struct PongMessage *m;
1022 struct PongMessage t;
1023 struct GNUNET_CRYPTO_AesInitializationVector iv;
1026 msize = ntohs (msg->size);
1027 if (sizeof (struct PongMessage) != msize)
1029 GNUNET_break_op (0);
1032 GNUNET_STATISTICS_update (GSC_stats,
1033 gettext_noop ("# PONG messages received"), 1,
1038 GNUNET_STATISTICS_update (GSC_stats,
1039 gettext_noop ("# PONG messages dropped (connection down)"), 1,
1042 case KX_STATE_KEY_SENT:
1043 GNUNET_STATISTICS_update (GSC_stats,
1044 gettext_noop ("# PONG messages dropped (out of order)"), 1,
1047 case KX_STATE_KEY_RECEIVED:
1051 case KX_STATE_REKEY_SENT:
1057 m = (const struct PongMessage *) msg;
1058 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1059 "Core service receives `%s' response from `%4s'.\n", "PONG",
1060 GNUNET_i2s (&kx->peer));
1061 /* mark as garbage, just to be sure */
1062 memset (&t, 255, sizeof (t));
1063 derive_pong_iv (&iv, &kx->decrypt_key, m->iv_seed, kx->ping_challenge,
1066 do_decrypt (kx, &iv, &m->challenge, &t.challenge,
1067 sizeof (struct PongMessage) - ((void *) &m->challenge -
1070 GNUNET_break_op (0);
1073 GNUNET_STATISTICS_update (GSC_stats,
1074 gettext_noop ("# PONG messages decrypted"), 1,
1076 if ((0 != memcmp (&t.target, &kx->peer, sizeof (struct GNUNET_PeerIdentity)))
1077 || (kx->ping_challenge != t.challenge))
1079 /* PONG malformed */
1080 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1081 "Received malformed `%s' wanted sender `%4s' with challenge %u\n",
1082 "PONG", GNUNET_i2s (&kx->peer),
1083 (unsigned int) kx->ping_challenge);
1084 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1085 "Received malformed `%s' received from `%4s' with challenge %u\n",
1086 "PONG", GNUNET_i2s (&t.target), (unsigned int) t.challenge);
1089 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Received PONG from `%s'\n",
1090 GNUNET_i2s (&kx->peer));
1091 /* no need to resend key any longer */
1092 if (GNUNET_SCHEDULER_NO_TASK != kx->retry_set_key_task)
1094 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
1095 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
1100 GNUNET_assert (0); /* should be impossible */
1102 case KX_STATE_KEY_SENT:
1103 GNUNET_assert (0); /* should be impossible */
1105 case KX_STATE_KEY_RECEIVED:
1106 GNUNET_STATISTICS_update (GSC_stats,
1108 ("# session keys confirmed via PONG"), 1,
1110 kx->status = KX_STATE_UP;
1111 GSC_SESSIONS_create (&kx->peer, kx);
1112 GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == kx->keep_alive_task);
1113 update_timeout (kx);
1116 GNUNET_STATISTICS_update (GSC_stats,
1118 ("# timeouts prevented via PONG"), 1,
1120 update_timeout (kx);
1122 case KX_STATE_REKEY_SENT:
1123 GNUNET_STATISTICS_update (GSC_stats,
1125 ("# rekey operations confirmed via PONG"), 1,
1127 kx->status = KX_STATE_UP;
1128 update_timeout (kx);
1138 * Send our key to the other peer.
1140 * @param kx key exchange context
1143 send_key (struct GSC_KeyExchangeInfo *kx)
1145 if (GNUNET_SCHEDULER_NO_TASK != kx->retry_set_key_task)
1147 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
1148 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
1150 /* always update sender status in SET KEY message */
1151 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1152 "Sending key to `%s' (my status: %d)\n",
1153 GNUNET_i2s (&kx->peer),
1155 current_ekm.sender_status = htonl ((int32_t) (kx->status));
1156 GSC_NEIGHBOURS_transmit (&kx->peer, ¤t_ekm.header,
1157 kx->set_key_retry_frequency);
1158 kx->retry_set_key_task =
1159 GNUNET_SCHEDULER_add_delayed (kx->set_key_retry_frequency,
1160 &set_key_retry_task, kx);
1165 * Encrypt and transmit a message with the given payload.
1167 * @param kx key exchange context
1168 * @param payload payload of the message
1169 * @param payload_size number of bytes in 'payload'
1172 GSC_KX_encrypt_and_transmit (struct GSC_KeyExchangeInfo *kx,
1173 const void *payload, size_t payload_size)
1175 size_t used = payload_size + sizeof (struct EncryptedMessage);
1176 char pbuf[used]; /* plaintext */
1177 char cbuf[used]; /* ciphertext */
1178 struct EncryptedMessage *em; /* encrypted message */
1179 struct EncryptedMessage *ph; /* plaintext header */
1180 struct GNUNET_CRYPTO_AesInitializationVector iv;
1181 struct GNUNET_CRYPTO_AuthKey auth_key;
1183 ph = (struct EncryptedMessage *) pbuf;
1185 htonl (GNUNET_CRYPTO_random_u32
1186 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
1187 ph->sequence_number = htonl (++kx->last_sequence_number_sent);
1189 ph->timestamp = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
1190 memcpy (&ph[1], payload, payload_size);
1192 em = (struct EncryptedMessage *) cbuf;
1193 em->header.size = htons (used);
1194 em->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE);
1195 em->iv_seed = ph->iv_seed;
1196 derive_iv (&iv, &kx->encrypt_key, ph->iv_seed, &kx->peer);
1197 GNUNET_assert (GNUNET_OK ==
1198 do_encrypt (kx, &iv, &ph->sequence_number,
1199 &em->sequence_number,
1200 used - ENCRYPTED_HEADER_SIZE));
1201 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Encrypted %u bytes for %s\n",
1202 used - ENCRYPTED_HEADER_SIZE, GNUNET_i2s (&kx->peer));
1203 derive_auth_key (&auth_key,
1206 GNUNET_CRYPTO_hmac (&auth_key, &em->sequence_number,
1207 used - ENCRYPTED_HEADER_SIZE, &em->hmac);
1208 GSC_NEIGHBOURS_transmit (&kx->peer, &em->header,
1209 GNUNET_TIME_UNIT_FOREVER_REL);
1214 * Closure for 'deliver_message'
1216 struct DeliverMessageContext
1220 * Performance information for the connection.
1222 const struct GNUNET_ATS_Information *atsi;
1225 * Sender of the message.
1227 const struct GNUNET_PeerIdentity *peer;
1230 * Number of entries in 'atsi' array.
1232 uint32_t atsi_count;
1237 * We received an encrypted message. Decrypt, validate and
1238 * pass on to the appropriate clients.
1240 * @param kx key exchange context for encrypting the message
1241 * @param msg encrypted message
1242 * @param atsi performance data
1243 * @param atsi_count number of entries in ats (excluding 0-termination)
1246 GSC_KX_handle_encrypted_message (struct GSC_KeyExchangeInfo *kx,
1247 const struct GNUNET_MessageHeader *msg,
1248 const struct GNUNET_ATS_Information *atsi,
1249 uint32_t atsi_count)
1251 const struct EncryptedMessage *m;
1252 struct EncryptedMessage *pt; /* plaintext */
1253 struct GNUNET_HashCode ph;
1255 struct GNUNET_TIME_Absolute t;
1256 struct GNUNET_CRYPTO_AesInitializationVector iv;
1257 struct GNUNET_CRYPTO_AuthKey auth_key;
1258 struct DeliverMessageContext dmc;
1259 uint16_t size = ntohs (msg->size);
1260 char buf[size] GNUNET_ALIGN;
1263 sizeof (struct EncryptedMessage) + sizeof (struct GNUNET_MessageHeader))
1265 GNUNET_break_op (0);
1268 m = (const struct EncryptedMessage *) msg;
1269 if (kx->status != KX_STATE_UP)
1271 GNUNET_STATISTICS_update (GSC_stats,
1273 ("# DATA message dropped (out of order)"),
1277 if (0 == GNUNET_TIME_absolute_get_remaining (kx->foreign_key_expires).rel_value)
1279 kx->status = KX_STATE_KEY_SENT;
1280 GNUNET_STATISTICS_update (GSC_stats,
1282 ("# DATA message dropped (session key expired)"),
1289 derive_auth_key (&auth_key, &kx->decrypt_key, m->iv_seed);
1290 GNUNET_CRYPTO_hmac (&auth_key, &m->sequence_number,
1291 size - ENCRYPTED_HEADER_SIZE, &ph);
1292 if (0 != memcmp (&ph, &m->hmac, sizeof (struct GNUNET_HashCode)))
1294 /* checksum failed */
1295 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1296 "Failed checksum validation for a message from `%s'\n",
1297 GNUNET_i2s (&kx->peer));
1300 derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
1303 do_decrypt (kx, &iv, &m->sequence_number, &buf[ENCRYPTED_HEADER_SIZE],
1304 size - ENCRYPTED_HEADER_SIZE))
1306 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Decrypted %u bytes from %s\n",
1307 size - ENCRYPTED_HEADER_SIZE, GNUNET_i2s (&kx->peer));
1308 pt = (struct EncryptedMessage *) buf;
1310 /* validate sequence number */
1311 snum = ntohl (pt->sequence_number);
1312 if (kx->last_sequence_number_received == snum)
1314 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1315 "Received duplicate message, ignoring.\n");
1316 /* duplicate, ignore */
1317 GNUNET_STATISTICS_update (GSC_stats,
1318 gettext_noop ("# bytes dropped (duplicates)"),
1322 if ((kx->last_sequence_number_received > snum) &&
1323 (kx->last_sequence_number_received - snum > 32))
1325 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1326 "Received ancient out of sequence message, ignoring.\n");
1327 /* ancient out of sequence, ignore */
1328 GNUNET_STATISTICS_update (GSC_stats,
1330 ("# bytes dropped (out of sequence)"), size,
1334 if (kx->last_sequence_number_received > snum)
1336 unsigned int rotbit = 1 << (kx->last_sequence_number_received - snum - 1);
1338 if ((kx->last_packets_bitmap & rotbit) != 0)
1340 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1341 "Received duplicate message, ignoring.\n");
1342 GNUNET_STATISTICS_update (GSC_stats,
1343 gettext_noop ("# bytes dropped (duplicates)"),
1345 /* duplicate, ignore */
1348 kx->last_packets_bitmap |= rotbit;
1350 if (kx->last_sequence_number_received < snum)
1352 unsigned int shift = (snum - kx->last_sequence_number_received);
1354 if (shift >= 8 * sizeof (kx->last_packets_bitmap))
1355 kx->last_packets_bitmap = 0;
1357 kx->last_packets_bitmap <<= shift;
1358 kx->last_sequence_number_received = snum;
1361 /* check timestamp */
1362 t = GNUNET_TIME_absolute_ntoh (pt->timestamp);
1363 if (GNUNET_TIME_absolute_get_duration (t).rel_value >
1364 MAX_MESSAGE_AGE.rel_value)
1366 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1367 "Message received far too old (%s). Content ignored.\n",
1368 GNUNET_STRINGS_relative_time_to_string (GNUNET_TIME_absolute_get_duration (t), GNUNET_YES));
1369 GNUNET_STATISTICS_update (GSC_stats,
1371 ("# bytes dropped (ancient message)"), size,
1376 /* process decrypted message(s) */
1377 update_timeout (kx);
1378 GNUNET_STATISTICS_update (GSC_stats,
1379 gettext_noop ("# bytes of payload decrypted"),
1380 size - sizeof (struct EncryptedMessage), GNUNET_NO);
1382 dmc.atsi_count = atsi_count;
1383 dmc.peer = &kx->peer;
1385 GNUNET_SERVER_mst_receive (mst, &dmc,
1386 &buf[sizeof (struct EncryptedMessage)],
1387 size - sizeof (struct EncryptedMessage),
1388 GNUNET_YES, GNUNET_NO))
1389 GNUNET_break_op (0);
1394 * Deliver P2P message to interested clients.
1395 * Invokes send twice, once for clients that want the full message, and once
1396 * for clients that only want the header
1398 * @param cls always NULL
1399 * @param client who sent us the message (struct GSC_KeyExchangeInfo)
1400 * @param m the message
1403 deliver_message (void *cls, void *client, const struct GNUNET_MessageHeader *m)
1405 struct DeliverMessageContext *dmc = client;
1407 switch (ntohs (m->type))
1409 case GNUNET_MESSAGE_TYPE_CORE_BINARY_TYPE_MAP:
1410 case GNUNET_MESSAGE_TYPE_CORE_COMPRESSED_TYPE_MAP:
1411 GSC_SESSIONS_set_typemap (dmc->peer, m);
1414 GSC_CLIENTS_deliver_message (dmc->peer, dmc->atsi, dmc->atsi_count, m,
1416 GNUNET_CORE_OPTION_SEND_FULL_INBOUND);
1417 GSC_CLIENTS_deliver_message (dmc->peer, dmc->atsi, dmc->atsi_count, m,
1418 sizeof (struct GNUNET_MessageHeader),
1419 GNUNET_CORE_OPTION_SEND_HDR_INBOUND);
1426 * Setup the message that links the ephemeral key to our persistent
1427 * public key and generate the appropriate signature.
1430 sign_ephemeral_key ()
1432 current_ekm.header.size = htons (sizeof (struct EphemeralKeyMessage));
1433 current_ekm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_EPHEMERAL_KEY);
1434 current_ekm.sender_status = 0; /* to be set later */
1435 current_ekm.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_SET_ECC_KEY);
1436 current_ekm.purpose.size = htonl (sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
1437 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
1438 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
1439 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded) +
1440 sizeof (struct GNUNET_CRYPTO_EccPublicKeyBinaryEncoded));
1441 current_ekm.creation_time = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
1442 current_ekm.expiration_time = GNUNET_TIME_absolute_hton (GNUNET_TIME_relative_to_absolute (GNUNET_TIME_relative_add (REKEY_FREQUENCY,
1444 GNUNET_CRYPTO_ecc_key_get_public (my_ephemeral_key,
1445 ¤t_ekm.ephemeral_key);
1446 current_ekm.origin_public_key = my_public_key;
1447 GNUNET_assert (GNUNET_OK ==
1448 GNUNET_CRYPTO_ecc_sign (my_private_key,
1449 ¤t_ekm.purpose,
1450 ¤t_ekm.signature));
1455 * Task run to trigger rekeying.
1457 * @param cls closure, NULL
1458 * @param tc scheduler context
1461 do_rekey (void *cls,
1462 const struct GNUNET_SCHEDULER_TaskContext *tc)
1464 struct GSC_KeyExchangeInfo *pos;
1466 rekey_task = GNUNET_SCHEDULER_add_delayed (REKEY_FREQUENCY,
1469 if (NULL != my_ephemeral_key)
1470 GNUNET_CRYPTO_ecc_key_free (my_ephemeral_key);
1471 my_ephemeral_key = GNUNET_CRYPTO_ecc_key_create ();
1472 GNUNET_assert (NULL != my_ephemeral_key);
1473 sign_ephemeral_key ();
1474 for (pos = kx_head; NULL != pos; pos = pos->next)
1476 pos->status = KX_STATE_REKEY_SENT;
1483 * Initialize KX subsystem.
1485 * @param pk private key to use for the peer
1486 * @return GNUNET_OK on success, GNUNET_SYSERR on failure
1489 GSC_KX_init (struct GNUNET_CRYPTO_EccPrivateKey *pk)
1491 GNUNET_assert (NULL != pk);
1492 my_private_key = pk;
1493 GNUNET_CRYPTO_ecc_key_get_public (my_private_key, &my_public_key);
1494 GNUNET_CRYPTO_hash (&my_public_key, sizeof (my_public_key),
1495 &GSC_my_identity.hashPubKey);
1496 my_ephemeral_key = GNUNET_CRYPTO_ecc_key_create ();
1497 if (NULL == my_ephemeral_key)
1500 GNUNET_CRYPTO_ecc_key_free (my_private_key);
1501 my_private_key = NULL;
1502 return GNUNET_SYSERR;
1504 sign_ephemeral_key ();
1505 mst = GNUNET_SERVER_mst_create (&deliver_message, NULL);
1506 rekey_task = GNUNET_SCHEDULER_add_delayed (REKEY_FREQUENCY,
1514 * Shutdown KX subsystem.
1519 if (GNUNET_SCHEDULER_NO_TASK != rekey_task)
1521 GNUNET_SCHEDULER_cancel (rekey_task);
1522 rekey_task = GNUNET_SCHEDULER_NO_TASK;
1524 if (NULL != my_private_key)
1526 GNUNET_CRYPTO_ecc_key_free (my_private_key);
1527 my_private_key = NULL;
1529 if (NULL != my_ephemeral_key)
1531 GNUNET_CRYPTO_ecc_key_free (my_ephemeral_key);
1532 my_ephemeral_key = NULL;
1536 GNUNET_SERVER_mst_destroy (mst);
1541 /* end of gnunet-service-core_kx.c */