2 This file is part of GNUnet.
3 (C) 2009, 2010, 2011 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.
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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_peerinfo_service.h"
34 #include "gnunet_hello_lib.h"
35 #include "gnunet_constants.h"
36 #include "gnunet_signatures.h"
37 #include "gnunet_protocols.h"
41 * How long do we wait for SET_KEY confirmation initially?
43 #define INITIAL_SET_KEY_RETRY_FREQUENCY GNUNET_TIME_relative_multiply (MAX_SET_KEY_DELAY, 1)
46 * What is the minimum frequency for a PING message?
48 #define MIN_PING_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
51 * What is the maximum age of a message for us to consider processing
52 * it? Note that this looks at the timestamp used by the other peer,
53 * so clock skew between machines does come into play here. So this
54 * should be picked high enough so that a little bit of clock skew
55 * does not prevent peers from connecting to us.
57 #define MAX_MESSAGE_AGE GNUNET_TIME_UNIT_DAYS
60 * What is the maximum delay for a SET_KEY message?
62 #define MAX_SET_KEY_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10)
66 * We're sending an (encrypted) PING to the other peer to check if he
67 * can decrypt. The other peer should respond with a PONG with the
68 * same content, except this time encrypted with the receiver's key.
73 * Message type is CORE_PING.
75 struct GNUNET_MessageHeader header;
80 uint32_t iv_seed GNUNET_PACKED;
83 * Intended target of the PING, used primarily to check
84 * that decryption actually worked.
86 struct GNUNET_PeerIdentity target;
89 * Random number chosen to make reply harder.
91 uint32_t challenge GNUNET_PACKED;
96 * Response to a PING. Includes data from the original PING.
101 * Message type is CORE_PONG.
103 struct GNUNET_MessageHeader header;
108 uint32_t iv_seed GNUNET_PACKED;
111 * Random number to make faking the reply harder. Must be
112 * first field after header (this is where we start to encrypt!).
114 uint32_t challenge GNUNET_PACKED;
117 * Reserved, always 'GNUNET_BANDWIDTH_VALUE_MAX'.
119 struct GNUNET_BANDWIDTH_Value32NBO reserved;
122 * Intended target of the PING, used primarily to check
123 * that decryption actually worked.
125 struct GNUNET_PeerIdentity target;
130 * Message transmitted to set (or update) a session key.
136 * Message type is either CORE_SET_KEY.
138 struct GNUNET_MessageHeader header;
141 * Status of the sender (should be in "enum PeerStateMachine"), nbo.
143 int32_t sender_status GNUNET_PACKED;
146 * Purpose of the signature, will be
147 * GNUNET_SIGNATURE_PURPOSE_SET_KEY.
149 struct GNUNET_CRYPTO_RsaSignaturePurpose purpose;
152 * At what time was this key created?
154 struct GNUNET_TIME_AbsoluteNBO creation_time;
157 * The encrypted session key.
159 struct GNUNET_CRYPTO_RsaEncryptedData encrypted_key;
162 * Who is the intended recipient?
164 struct GNUNET_PeerIdentity target;
167 * Signature of the stuff above (starting at purpose).
169 struct GNUNET_CRYPTO_RsaSignature signature;
175 * Encapsulation for encrypted messages exchanged between
176 * peers. Followed by the actual encrypted data.
178 struct EncryptedMessage
181 * Message type is either CORE_ENCRYPTED_MESSAGE.
183 struct GNUNET_MessageHeader header;
186 * Random value used for IV generation.
188 uint32_t iv_seed GNUNET_PACKED;
191 * MAC of the encrypted message (starting at 'sequence_number'),
192 * used to verify message integrity. Everything after this value
193 * (excluding this value itself) will be encrypted and authenticated.
194 * ENCRYPTED_HEADER_SIZE must be set to the offset of the *next* field.
196 GNUNET_HashCode hmac;
199 * Sequence number, in network byte order. This field
200 * must be the first encrypted/decrypted field
202 uint32_t sequence_number GNUNET_PACKED;
205 * Reserved, always 'GNUNET_BANDWIDTH_VALUE_MAX'.
207 struct GNUNET_BANDWIDTH_Value32NBO reserved;
210 * Timestamp. Used to prevent reply of ancient messages
211 * (recent messages are caught with the sequence number).
213 struct GNUNET_TIME_AbsoluteNBO timestamp;
218 * Number of bytes (at the beginning) of "struct EncryptedMessage"
219 * that are NOT encrypted.
221 #define ENCRYPTED_HEADER_SIZE (offsetof(struct EncryptedMessage, sequence_number))
225 * State machine for our P2P encryption handshake. Everyone starts in
226 * "DOWN", if we receive the other peer's key (other peer initiated)
227 * we start in state RECEIVED (since we will immediately send our
228 * own); otherwise we start in SENT. If we get back a PONG from
229 * within either state, we move up to CONFIRMED (the PONG will always
230 * be sent back encrypted with the key we sent to the other peer).
240 * We've sent our session key.
245 * We've received the other peers session key.
247 KX_STATE_KEY_RECEIVED,
250 * The other peer has confirmed our session key with a message
251 * encrypted with his session key (which we got). Key exchange
259 * Information about the status of a key exchange with another peer.
261 struct GSC_KeyExchangeInfo
264 * Identity of the peer.
266 struct GNUNET_PeerIdentity peer;
269 * SetKeyMessage to transmit (initialized the first
270 * time our status goes past 'KX_STATE_KEY_SENT').
272 struct SetKeyMessage skm;
275 * PING message we transmit to the other peer.
277 struct PingMessage ping;
280 * SetKeyMessage we received and did not process yet.
282 struct SetKeyMessage *skm_received;
285 * PING message we received from the other peer and
286 * did not process yet (or NULL).
288 struct PingMessage *ping_received;
291 * PONG message we received from the other peer and
292 * did not process yet (or NULL).
294 struct PongMessage *pong_received;
297 * Encrypted message we received from the other peer and
298 * did not process yet (or NULL).
300 struct EncryptedMessage *emsg_received;
303 * Non-NULL if we are currently looking up HELLOs for this peer.
306 struct GNUNET_PEERINFO_IteratorContext *pitr;
309 * Public key of the neighbour, NULL if we don't have it yet.
311 struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded *public_key;
314 * We received a PONG message before we got the "public_key"
315 * (or the SET_KEY). We keep it here until we have a key
316 * to decrypt it. NULL if no PONG is pending.
318 struct PongMessage *pending_pong;
321 * Key we use to encrypt our messages for the other peer
322 * (initialized by us when we do the handshake).
324 struct GNUNET_CRYPTO_AesSessionKey encrypt_key;
327 * Key we use to decrypt messages from the other peer
328 * (given to us by the other peer during the handshake).
330 struct GNUNET_CRYPTO_AesSessionKey decrypt_key;
333 * At what time did we generate our encryption key?
335 struct GNUNET_TIME_Absolute encrypt_key_created;
338 * At what time did the other peer generate the decryption key?
340 struct GNUNET_TIME_Absolute decrypt_key_created;
343 * When should the session time out (if there are no PONGs)?
345 struct GNUNET_TIME_Absolute timeout;
348 * At what frequency are we currently re-trying SET_KEY messages?
350 struct GNUNET_TIME_Relative set_key_retry_frequency;
353 * ID of task used for re-trying SET_KEY and PING message.
355 GNUNET_SCHEDULER_TaskIdentifier retry_set_key_task;
358 * ID of task used for sending keep-alive pings.
360 GNUNET_SCHEDULER_TaskIdentifier keep_alive_task;
363 * Bit map indicating which of the 32 sequence numbers before the last
364 * were received (good for accepting out-of-order packets and
365 * estimating reliability of the connection)
367 unsigned int last_packets_bitmap;
370 * last sequence number received on this connection (highest)
372 uint32_t last_sequence_number_received;
375 * last sequence number transmitted
377 uint32_t last_sequence_number_sent;
380 * What was our PING challenge number (for this peer)?
382 uint32_t ping_challenge;
385 * What is our connection status?
387 enum KxStateMachine status;
394 * Handle to peerinfo service.
396 static struct GNUNET_PEERINFO_Handle *peerinfo;
401 static struct GNUNET_CRYPTO_RsaPrivateKey *my_private_key;
406 static struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded my_public_key;
409 * Our message stream tokenizer (for encrypted payload).
411 static struct GNUNET_SERVER_MessageStreamTokenizer *mst;
416 * Derive an authentication key from "set key" information
419 derive_auth_key (struct GNUNET_CRYPTO_AuthKey *akey,
420 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
421 struct GNUNET_TIME_Absolute creation_time)
423 static const char ctx[] = "authentication key";
424 struct GNUNET_TIME_AbsoluteNBO ctbe;
427 ctbe = GNUNET_TIME_absolute_hton (creation_time);
428 GNUNET_CRYPTO_hmac_derive_key (akey, skey, &seed, sizeof (seed), &skey->key,
429 sizeof (skey->key), &ctbe, sizeof (ctbe), ctx,
435 * Derive an IV from packet information
438 derive_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
439 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
440 const struct GNUNET_PeerIdentity *identity)
442 static const char ctx[] = "initialization vector";
444 GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
445 &identity->hashPubKey.bits,
446 sizeof (identity->hashPubKey.bits), ctx,
451 * Derive an IV from pong packet information
454 derive_pong_iv (struct GNUNET_CRYPTO_AesInitializationVector *iv,
455 const struct GNUNET_CRYPTO_AesSessionKey *skey, uint32_t seed,
456 uint32_t challenge, const struct GNUNET_PeerIdentity *identity)
458 static const char ctx[] = "pong initialization vector";
460 GNUNET_CRYPTO_aes_derive_iv (iv, skey, &seed, sizeof (seed),
461 &identity->hashPubKey.bits,
462 sizeof (identity->hashPubKey.bits), &challenge,
463 sizeof (challenge), ctx, sizeof (ctx), NULL);
468 * Encrypt size bytes from in and write the result to out. Use the
469 * key for outbound traffic of the given neighbour.
471 * @param kx key information context
472 * @param iv initialization vector to use
473 * @param in ciphertext
474 * @param out plaintext
475 * @param size size of in/out
476 * @return GNUNET_OK on success
479 do_encrypt (struct GSC_KeyExchangeInfo *kx,
480 const struct GNUNET_CRYPTO_AesInitializationVector *iv,
481 const void *in, void *out, size_t size)
483 if (size != (uint16_t) size)
488 GNUNET_assert (size ==
489 GNUNET_CRYPTO_aes_encrypt (in, (uint16_t) size,
490 &kx->encrypt_key, iv, out));
491 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# bytes encrypted"), size,
494 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
495 "Encrypted %u bytes for `%4s' using key %u, IV %u\n",
496 (unsigned int) size, GNUNET_i2s (&kx->peer),
497 (unsigned int) kx->encrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
508 * Decrypt size bytes from in and write the result to out. Use the
509 * key for inbound traffic of the given neighbour. This function does
510 * NOT do any integrity-checks on the result.
512 * @param kx key information context
513 * @param iv initialization vector to use
514 * @param in ciphertext
515 * @param out plaintext
516 * @param size size of in/out
517 * @return GNUNET_OK on success
520 do_decrypt (struct GSC_KeyExchangeInfo *kx,
521 const struct GNUNET_CRYPTO_AesInitializationVector *iv,
522 const void *in, void *out, size_t size)
524 if (size != (uint16_t) size)
529 if ((kx->status != KX_STATE_KEY_RECEIVED) &&
530 (kx->status != KX_STATE_UP))
533 return GNUNET_SYSERR;
536 GNUNET_CRYPTO_aes_decrypt (in, (uint16_t) size, &kx->decrypt_key, iv, out))
539 return GNUNET_SYSERR;
541 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# bytes decrypted"), size,
544 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
545 "Decrypted %u bytes from `%4s' using key %u, IV %u\n",
546 (unsigned int) size, GNUNET_i2s (&kx->peer),
547 (unsigned int) kx->decrypt_key.crc32, GNUNET_CRYPTO_crc32_n (iv,
556 * Send our key (and encrypted PING) to the other peer.
558 * @param kx key exchange context
561 send_key (struct GSC_KeyExchangeInfo *kx);
565 * Task that will retry "send_key" if our previous attempt failed.
567 * @param cls our 'struct GSC_KeyExchangeInfo'
568 * @param tc scheduler context
571 set_key_retry_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
573 struct GSC_KeyExchangeInfo *kx = cls;
575 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
576 kx->set_key_retry_frequency = GNUNET_TIME_relative_multiply (kx->set_key_retry_frequency, 2);
582 * PEERINFO is giving us a HELLO for a peer. Add the public key to
583 * the neighbour's struct and continue with the key exchange. Or, if
584 * we did not get a HELLO, just do nothing.
586 * @param cls the 'struct GSC_KeyExchangeInfo' to retry sending the key for
587 * @param peer the peer for which this is the HELLO
588 * @param hello HELLO message of that peer
589 * @param err_msg NULL if successful, otherwise contains error message
592 process_hello (void *cls, const struct GNUNET_PeerIdentity *peer,
593 const struct GNUNET_HELLO_Message *hello,
596 struct GSC_KeyExchangeInfo *kx = cls;
597 struct SetKeyMessage *skm;
601 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
602 _("Error in communication with PEERINFO service\n"));
609 if (kx->public_key != NULL)
610 return; /* done here */
612 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
613 "Failed to obtain public key for peer `%4s', delaying processing of SET_KEY\n",
614 GNUNET_i2s (&kx->peer));
616 GNUNET_STATISTICS_update (GSC_stats,
618 ("# Delayed connecting due to lack of public key"),
620 kx->retry_set_key_task =
621 GNUNET_SCHEDULER_add_delayed (kx->set_key_retry_frequency,
622 &set_key_retry_task, kx);
625 if (kx->public_key != NULL)
627 /* already have public key, why are we here? */
631 GNUNET_assert (GNUNET_SCHEDULER_NO_TASK == kx->retry_set_key_task);
633 GNUNET_malloc (sizeof (struct GNUNET_CRYPTO_RsaPublicKeyBinaryEncoded));
634 if (GNUNET_OK != GNUNET_HELLO_get_key (hello, kx->public_key))
637 GNUNET_free (kx->public_key);
638 kx->public_key = NULL;
642 if (NULL != kx->skm_received)
644 skm = kx->skm_received;
645 kx->skm_received = NULL;
646 GSC_KX_handle_set_key (kx, &skm->header);
653 * Start the key exchange with the given peer.
655 * @param pid identity of the peer to do a key exchange with
656 * @return key exchange information context
658 struct GSC_KeyExchangeInfo *
659 GSC_KX_start (const struct GNUNET_PeerIdentity *pid)
661 struct GSC_KeyExchangeInfo *kx;
664 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
665 "Initiating key exchange with `%s'\n",
668 kx = GNUNET_malloc (sizeof (struct GSC_KeyExchangeInfo));
670 kx->set_key_retry_frequency = INITIAL_SET_KEY_RETRY_FREQUENCY;
671 kx->pitr = GNUNET_PEERINFO_iterate (peerinfo,
673 GNUNET_TIME_UNIT_FOREVER_REL /* timeout? */,
681 * Stop key exchange with the given peer. Clean up key material.
683 * @param kx key exchange to stop
686 GSC_KX_stop (struct GSC_KeyExchangeInfo *kx)
688 if (kx->pitr != NULL)
690 GNUNET_PEERINFO_iterate_cancel (kx->pitr);
693 if (kx->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK)
695 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
696 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
698 if (kx->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
700 GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
701 kx->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
703 GNUNET_free_non_null (kx->skm_received);
704 GNUNET_free_non_null (kx->ping_received);
705 GNUNET_free_non_null (kx->pong_received);
706 GNUNET_free_non_null (kx->emsg_received);
707 GNUNET_free_non_null (kx->public_key);
713 * We received a SET_KEY message. Validate and update
714 * our key material and status.
716 * @param kx key exchange status for the corresponding peer
717 * @param msg the set key message we received
720 GSC_KX_handle_set_key (struct GSC_KeyExchangeInfo *kx,
721 const struct GNUNET_MessageHeader *msg)
723 const struct SetKeyMessage *m;
724 struct GNUNET_TIME_Absolute t;
725 struct GNUNET_CRYPTO_AesSessionKey k;
726 struct PingMessage *ping;
727 struct PongMessage *pong;
728 enum KxStateMachine sender_status;
731 size = ntohs (msg->size);
732 if (size != sizeof (struct SetKeyMessage))
737 m = (const struct SetKeyMessage*) msg;
738 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# session keys received"),
742 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
743 "Core service receives `%s' request from `%4s'.\n", "SET_KEY",
744 GNUNET_i2s (&kx->peer));
746 if (kx->public_key == NULL)
748 GNUNET_free_non_null (kx->skm_received);
749 kx->skm_received = (struct SetKeyMessage*) GNUNET_copy_message (msg);
753 memcmp (&m->target, &GSC_my_identity, sizeof (struct GNUNET_PeerIdentity)))
755 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
756 _("`%s' is for `%s', not for me. Ignoring.\n"),
757 "SET_KEY", GNUNET_i2s (&m->target));
760 if ((ntohl (m->purpose.size) !=
761 sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) +
762 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
763 sizeof (struct GNUNET_CRYPTO_RsaEncryptedData) +
764 sizeof (struct GNUNET_PeerIdentity)) ||
766 GNUNET_CRYPTO_rsa_verify (GNUNET_SIGNATURE_PURPOSE_SET_KEY, &m->purpose,
767 &m->signature, kx->public_key)))
769 /* invalid signature */
773 t = GNUNET_TIME_absolute_ntoh (m->creation_time);
774 if (((kx->status == KX_STATE_KEY_RECEIVED) ||
775 (kx->status == KX_STATE_UP)) &&
776 (t.abs_value < kx->decrypt_key_created.abs_value))
778 /* this could rarely happen due to massive re-ordering of
779 * messages on the network level, but is most likely either
780 * a bug or some adversary messing with us. Report. */
784 if ((GNUNET_CRYPTO_rsa_decrypt
785 (my_private_key, &m->encrypted_key, &k,
786 sizeof (struct GNUNET_CRYPTO_AesSessionKey)) !=
787 sizeof (struct GNUNET_CRYPTO_AesSessionKey)) ||
788 (GNUNET_OK != GNUNET_CRYPTO_aes_check_session_key (&k)))
790 /* failed to decrypt !? */
794 GNUNET_STATISTICS_update (GSC_stats,
795 gettext_noop ("# SET_KEY messages decrypted"), 1,
798 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
799 "Received SET_KEY from `%s'\n",
800 GNUNET_i2s (&kx->peer));
803 if (kx->decrypt_key_created.abs_value != t.abs_value)
805 /* fresh key, reset sequence numbers */
806 kx->last_sequence_number_received = 0;
807 kx->last_packets_bitmap = 0;
808 kx->decrypt_key_created = t;
810 sender_status = (enum KxStateMachine) ntohl (m->sender_status);
815 kx->status = KX_STATE_KEY_RECEIVED;
816 /* we're not up, so we are already doing 'send_key' */
818 case KX_STATE_KEY_SENT:
819 kx->status = KX_STATE_KEY_RECEIVED;
820 /* we're not up, so we are already doing 'send_key' */
822 case KX_STATE_KEY_RECEIVED:
823 /* we're not up, so we are already doing 'send_key' */
826 if ( (sender_status == KX_STATE_DOWN) ||
827 (sender_status == KX_STATE_KEY_SENT) )
828 send_key (kx); /* we are up, but other peer is not! */
834 if (kx->ping_received != NULL)
836 ping = kx->ping_received;
837 kx->ping_received = NULL;
838 GSC_KX_handle_ping (kx, &ping->header);
841 if (kx->pong_received != NULL)
843 pong = kx->pong_received;
844 kx->pong_received = NULL;
845 GSC_KX_handle_pong (kx, &pong->header);
852 * We received a PING message. Validate and transmit
855 * @param kx key exchange status for the corresponding peer
856 * @param msg the encrypted PING message itself
859 GSC_KX_handle_ping (struct GSC_KeyExchangeInfo *kx,
860 const struct GNUNET_MessageHeader *msg)
862 const struct PingMessage *m;
863 struct PingMessage t;
864 struct PongMessage tx;
865 struct PongMessage tp;
866 struct GNUNET_CRYPTO_AesInitializationVector iv;
869 msize = ntohs (msg->size);
870 if (msize != sizeof (struct PingMessage))
875 GNUNET_STATISTICS_update (GSC_stats,
876 gettext_noop ("# PING messages received"),
878 if ( (kx->status != KX_STATE_KEY_RECEIVED) &&
879 (kx->status != KX_STATE_UP) )
882 GNUNET_free_non_null (kx->ping_received);
883 kx->ping_received = (struct PingMessage*) GNUNET_copy_message (msg);
886 m = (const struct PingMessage*) msg;
888 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
889 "Core service receives `%s' request from `%4s'.\n", "PING",
890 GNUNET_i2s (&kx->peer));
892 derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
894 do_decrypt (kx, &iv, &m->target, &t.target,
895 sizeof (struct PingMessage) - ((void *) &m->target -
902 memcmp (&t.target, &GSC_my_identity, sizeof (struct GNUNET_PeerIdentity)))
907 GNUNET_snprintf (sender, sizeof (sender), "%8s", GNUNET_i2s (&kx->peer));
908 GNUNET_snprintf (peer, sizeof (peer), "%8s", GNUNET_i2s (&t.target));
909 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
910 _("Received PING from `%s' for different identity: I am `%s', PONG identity: `%s'\n"),
911 sender, GNUNET_i2s (&GSC_my_identity), peer);
916 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
917 "Received PING from `%s'\n",
918 GNUNET_i2s (&kx->peer));
921 tx.reserved = GNUNET_BANDWIDTH_VALUE_MAX;
922 tx.challenge = t.challenge;
923 tx.target = t.target;
924 tp.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PONG);
925 tp.header.size = htons (sizeof (struct PongMessage));
927 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
928 derive_pong_iv (&iv, &kx->encrypt_key, tp.iv_seed, t.challenge, &kx->peer);
929 do_encrypt (kx, &iv, &tx.challenge, &tp.challenge,
930 sizeof (struct PongMessage) - ((void *) &tp.challenge -
932 GNUNET_STATISTICS_update (GSC_stats,
933 gettext_noop ("# PONG messages created"), 1,
935 GSC_NEIGHBOURS_transmit (&kx->peer,
937 GNUNET_TIME_UNIT_FOREVER_REL /* FIXME: timeout */);
942 * Create a fresh SET KEY message for transmission to the other peer.
943 * Also creates a new key.
945 * @param kx key exchange context to create SET KEY message for
948 setup_fresh_setkey (struct GSC_KeyExchangeInfo *kx)
950 struct SetKeyMessage *skm;
952 GNUNET_CRYPTO_aes_create_session_key (&kx->encrypt_key);
953 kx->encrypt_key_created = GNUNET_TIME_absolute_get ();
955 skm->header.size = htons (sizeof (struct SetKeyMessage));
956 skm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_SET_KEY);
958 htonl (sizeof (struct GNUNET_CRYPTO_RsaSignaturePurpose) +
959 sizeof (struct GNUNET_TIME_AbsoluteNBO) +
960 sizeof (struct GNUNET_CRYPTO_RsaEncryptedData) +
961 sizeof (struct GNUNET_PeerIdentity));
962 skm->purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_SET_KEY);
963 skm->creation_time = GNUNET_TIME_absolute_hton (kx->encrypt_key_created);
964 skm->target = kx->peer;
965 GNUNET_assert (GNUNET_OK ==
966 GNUNET_CRYPTO_rsa_encrypt (&kx->encrypt_key,
968 GNUNET_CRYPTO_AesSessionKey),
969 kx->public_key, &skm->encrypted_key));
970 GNUNET_assert (GNUNET_OK ==
971 GNUNET_CRYPTO_rsa_sign (my_private_key, &skm->purpose,
977 * Create a fresh PING message for transmission to the other peer.
979 * @param kx key exchange context to create PING for
982 setup_fresh_ping (struct GSC_KeyExchangeInfo *kx)
984 struct PingMessage pp;
985 struct PingMessage *pm;
986 struct GNUNET_CRYPTO_AesInitializationVector iv;
989 pm->header.size = htons (sizeof (struct PingMessage));
990 pm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PING);
992 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX);
993 derive_iv (&iv, &kx->encrypt_key, pm->iv_seed, &kx->peer);
994 pp.challenge = kx->ping_challenge;
995 pp.target = kx->peer;
996 do_encrypt (kx, &iv, &pp.target, &pm->target,
997 sizeof (struct PingMessage) - ((void *) &pm->target -
1003 * Task triggered when a neighbour entry is about to time out
1004 * (and we should prevent this by sending a PING).
1006 * @param cls the 'struct GSC_KeyExchangeInfo'
1007 * @param tc scheduler context (not used)
1010 send_keep_alive (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
1012 struct GSC_KeyExchangeInfo *kx = cls;
1013 struct GNUNET_TIME_Relative retry;
1014 struct GNUNET_TIME_Relative left;
1016 kx->keep_alive_task = GNUNET_SCHEDULER_NO_TASK;
1017 left = GNUNET_TIME_absolute_get_remaining (kx->timeout);
1018 if (left.rel_value == 0)
1020 GSC_SESSIONS_end (&kx->peer);
1021 kx->status = KX_STATE_DOWN;
1025 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1026 "Sending KEEPALIVE to `%s'\n",
1027 GNUNET_i2s (&kx->peer));
1029 setup_fresh_ping (kx);
1030 GSC_NEIGHBOURS_transmit (&kx->peer,
1032 kx->set_key_retry_frequency);
1034 GNUNET_TIME_relative_max (GNUNET_TIME_relative_divide (left, 2),
1035 MIN_PING_FREQUENCY);
1036 kx->keep_alive_task =
1037 GNUNET_SCHEDULER_add_delayed (retry, &send_keep_alive, kx);
1042 * We've seen a valid message from the other peer.
1043 * Update the time when the session would time out
1044 * and delay sending our keep alive message further.
1046 * @param kx key exchange where we saw activity
1049 update_timeout (struct GSC_KeyExchangeInfo *kx)
1051 kx->timeout = GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
1052 if (kx->keep_alive_task != GNUNET_SCHEDULER_NO_TASK)
1053 GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
1054 kx->keep_alive_task =
1055 GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_divide
1056 (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT,
1057 2), &send_keep_alive, kx);
1062 * We received a PONG message. Validate and update our status.
1064 * @param kx key exchange context for the the PONG
1065 * @param m the encrypted PONG message itself
1068 GSC_KX_handle_pong (struct GSC_KeyExchangeInfo *kx, const struct GNUNET_MessageHeader *msg)
1070 const struct PongMessage *m;
1071 struct PongMessage t;
1072 struct EncryptedMessage *emsg;
1073 struct GNUNET_CRYPTO_AesInitializationVector iv;
1076 msize = ntohs (msg->size);
1077 if (msize != sizeof (struct PongMessage))
1079 GNUNET_break_op (0);
1082 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# PONG messages received"),
1084 if ( (kx->status != KX_STATE_KEY_RECEIVED) &&
1085 (kx->status != KX_STATE_UP) )
1087 if (kx->status == KX_STATE_KEY_SENT)
1089 GNUNET_free_non_null (kx->pong_received);
1090 kx->pong_received = (struct PongMessage*) GNUNET_copy_message (msg);
1094 m = (const struct PongMessage*) msg;
1096 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1097 "Core service receives `%s' response from `%4s'.\n", "PONG",
1098 GNUNET_i2s (&kx->peer));
1100 /* mark as garbage, just to be sure */
1101 memset (&t, 255, sizeof (t));
1102 derive_pong_iv (&iv, &kx->decrypt_key, m->iv_seed, kx->ping_challenge,
1105 do_decrypt (kx, &iv, &m->challenge, &t.challenge,
1106 sizeof (struct PongMessage) - ((void *) &m->challenge -
1109 GNUNET_break_op (0);
1112 GNUNET_STATISTICS_update (GSC_stats, gettext_noop ("# PONG messages decrypted"),
1114 if ((0 != memcmp (&t.target, &kx->peer, sizeof (struct GNUNET_PeerIdentity)))
1115 || (kx->ping_challenge != t.challenge))
1117 /* PONG malformed */
1119 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1120 "Received malformed `%s' wanted sender `%4s' with challenge %u\n",
1121 "PONG", GNUNET_i2s (&kx->peer),
1122 (unsigned int) kx->ping_challenge);
1123 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1124 "Received malformed `%s' received from `%4s' with challenge %u\n",
1125 "PONG", GNUNET_i2s (&t.target), (unsigned int) t.challenge);
1130 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1131 "Received PONG from `%s'\n",
1132 GNUNET_i2s (&kx->peer));
1137 GNUNET_break (0); /* should be impossible */
1139 case KX_STATE_KEY_SENT:
1140 GNUNET_break (0); /* should be impossible */
1142 case KX_STATE_KEY_RECEIVED:
1143 GNUNET_STATISTICS_update (GSC_stats,
1145 ("# Session keys confirmed via PONG"), 1,
1147 kx->status = KX_STATE_UP;
1148 GSC_SESSIONS_create (&kx->peer, kx);
1149 GNUNET_assert (kx->retry_set_key_task != GNUNET_SCHEDULER_NO_TASK);
1150 GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
1151 kx->retry_set_key_task = GNUNET_SCHEDULER_NO_TASK;
1152 GNUNET_assert (kx->keep_alive_task == GNUNET_SCHEDULER_NO_TASK);
1153 if (kx->emsg_received != NULL)
1155 emsg = kx->emsg_received;
1156 kx->emsg_received = NULL;
1157 GSC_KX_handle_encrypted_message (kx, &emsg->header, NULL, 0 /* FIXME: ATSI */);
1160 update_timeout (kx);
1163 update_timeout (kx);
1173 * Send our key (and encrypted PING) to the other peer.
1175 * @param kx key exchange context
1178 send_key (struct GSC_KeyExchangeInfo *kx)
1180 GNUNET_assert (kx->retry_set_key_task == GNUNET_SCHEDULER_NO_TASK);
1181 if (KX_STATE_UP == kx->status)
1182 return; /* nothing to do */
1183 if (kx->public_key == NULL)
1185 /* lookup public key, then try again */
1187 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1188 "Trying to obtain public key for `%s'\n",
1189 GNUNET_i2s (&kx->peer));
1192 GNUNET_PEERINFO_iterate (peerinfo, &kx->peer,
1193 GNUNET_TIME_UNIT_FOREVER_REL /* timeout? */,
1194 &process_hello, kx);
1202 kx->status = KX_STATE_KEY_SENT;
1203 /* setup SET KEY message */
1204 setup_fresh_setkey (kx);
1205 setup_fresh_ping (kx);
1206 GNUNET_STATISTICS_update (GSC_stats,
1208 ("# SET_KEY and PING messages created"), 1,
1211 case KX_STATE_KEY_SENT:
1213 case KX_STATE_KEY_RECEIVED:
1223 /* always update sender status in SET KEY message */
1224 kx->skm.sender_status = htonl ((int32_t) kx->status);
1226 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1227 "Sending SET_KEY and PING to `%s'\n",
1228 GNUNET_i2s (&kx->peer));
1230 GSC_NEIGHBOURS_transmit (&kx->peer,
1232 kx->set_key_retry_frequency);
1233 GSC_NEIGHBOURS_transmit (&kx->peer,
1235 kx->set_key_retry_frequency);
1236 kx->retry_set_key_task =
1237 GNUNET_SCHEDULER_add_delayed (kx->set_key_retry_frequency,
1238 &set_key_retry_task, kx);
1243 * Encrypt and transmit a message with the given payload.
1245 * @param kx key exchange context
1246 * @param payload payload of the message
1247 * @param payload_size number of bytes in 'payload'
1250 GSC_KX_encrypt_and_transmit (struct GSC_KeyExchangeInfo *kx,
1251 const void *payload,
1252 size_t payload_size)
1254 size_t used = payload_size + sizeof (struct EncryptedMessage);
1255 char pbuf[used]; /* plaintext */
1256 char cbuf[used]; /* ciphertext */
1257 struct EncryptedMessage *em; /* encrypted message */
1258 struct EncryptedMessage *ph; /* plaintext header */
1259 struct GNUNET_CRYPTO_AesInitializationVector iv;
1260 struct GNUNET_CRYPTO_AuthKey auth_key;
1262 ph = (struct EncryptedMessage*) pbuf;
1264 htonl (GNUNET_CRYPTO_random_u32
1265 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
1266 ph->sequence_number = htonl (++kx->last_sequence_number_sent);
1267 ph->reserved = GNUNET_BANDWIDTH_VALUE_MAX;
1268 ph->timestamp = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
1269 memcpy (&ph[1], payload, payload_size);
1271 em = (struct EncryptedMessage *) cbuf;
1272 em->header.size = htons (used);
1273 em->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE);
1274 em->iv_seed = ph->iv_seed;
1275 derive_iv (&iv, &kx->encrypt_key, ph->iv_seed, &kx->peer);
1276 GNUNET_assert (GNUNET_OK ==
1277 do_encrypt (kx, &iv, &ph->sequence_number, &em->sequence_number,
1278 used - ENCRYPTED_HEADER_SIZE));
1280 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1281 "Encrypted %u bytes for %s\n",
1282 used - ENCRYPTED_HEADER_SIZE,
1283 GNUNET_i2s (&kx->peer));
1285 derive_auth_key (&auth_key, &kx->encrypt_key, ph->iv_seed,
1286 kx->encrypt_key_created);
1287 GNUNET_CRYPTO_hmac (&auth_key, &em->sequence_number,
1288 used - ENCRYPTED_HEADER_SIZE, &em->hmac);
1289 GSC_NEIGHBOURS_transmit (&kx->peer,
1291 GNUNET_TIME_UNIT_FOREVER_REL);
1296 * Closure for 'deliver_message'
1298 struct DeliverMessageContext
1302 * Performance information for the connection.
1304 const struct GNUNET_ATS_Information *atsi;
1307 * Sender of the message.
1309 const struct GNUNET_PeerIdentity *peer;
1312 * Number of entries in 'atsi' array.
1314 uint32_t atsi_count;
1319 * We received an encrypted message. Decrypt, validate and
1320 * pass on to the appropriate clients.
1322 * @param kx key exchange context for encrypting the message
1323 * @param m encrypted message
1324 * @param atsi performance data
1325 * @param atsi_count number of entries in ats (excluding 0-termination)
1328 GSC_KX_handle_encrypted_message (struct GSC_KeyExchangeInfo *kx,
1329 const struct GNUNET_MessageHeader *msg,
1330 const struct GNUNET_ATS_Information *atsi,
1331 uint32_t atsi_count)
1333 const struct EncryptedMessage *m;
1334 struct EncryptedMessage *pt; /* plaintext */
1337 struct GNUNET_TIME_Absolute t;
1338 struct GNUNET_CRYPTO_AesInitializationVector iv;
1339 struct GNUNET_CRYPTO_AuthKey auth_key;
1340 struct DeliverMessageContext dmc;
1341 uint16_t size = ntohs (msg->size);
1345 sizeof (struct EncryptedMessage) + sizeof (struct GNUNET_MessageHeader))
1347 GNUNET_break_op (0);
1350 m = (const struct EncryptedMessage*) msg;
1351 if ( (kx->status != KX_STATE_KEY_RECEIVED) &&
1352 (kx->status != KX_STATE_UP) )
1354 GNUNET_STATISTICS_update (GSC_stats,
1356 ("# failed to decrypt message (no session key)"),
1360 if (kx->status == KX_STATE_KEY_RECEIVED)
1363 GNUNET_free_non_null (kx->ping_received);
1364 kx->emsg_received = (struct EncryptedMessage*) GNUNET_copy_message (msg);
1368 derive_auth_key (&auth_key, &kx->decrypt_key, m->iv_seed,
1369 kx->decrypt_key_created);
1370 GNUNET_CRYPTO_hmac (&auth_key, &m->sequence_number,
1371 size - ENCRYPTED_HEADER_SIZE, &ph);
1372 if (0 != memcmp (&ph, &m->hmac, sizeof (GNUNET_HashCode)))
1374 /* checksum failed */
1375 GNUNET_break_op (0);
1378 derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
1381 do_decrypt (kx, &iv, &m->sequence_number, &buf[ENCRYPTED_HEADER_SIZE],
1382 size - ENCRYPTED_HEADER_SIZE))
1385 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1386 "Decrypted %u bytes from %s\n",
1387 size - ENCRYPTED_HEADER_SIZE,
1388 GNUNET_i2s (&kx->peer));
1390 pt = (struct EncryptedMessage *) buf;
1392 /* validate sequence number */
1393 snum = ntohl (pt->sequence_number);
1394 if (kx->last_sequence_number_received == snum)
1396 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1397 "Received duplicate message, ignoring.\n");
1398 /* duplicate, ignore */
1399 GNUNET_STATISTICS_update (GSC_stats,
1400 gettext_noop ("# bytes dropped (duplicates)"),
1404 if ((kx->last_sequence_number_received > snum) &&
1405 (kx->last_sequence_number_received - snum > 32))
1407 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1408 "Received ancient out of sequence message, ignoring.\n");
1409 /* ancient out of sequence, ignore */
1410 GNUNET_STATISTICS_update (GSC_stats,
1412 ("# bytes dropped (out of sequence)"), size,
1416 if (kx->last_sequence_number_received > snum)
1418 unsigned int rotbit = 1 << (kx->last_sequence_number_received - snum - 1);
1420 if ((kx->last_packets_bitmap & rotbit) != 0)
1422 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1423 "Received duplicate message, ignoring.\n");
1424 GNUNET_STATISTICS_update (GSC_stats,
1425 gettext_noop ("# bytes dropped (duplicates)"),
1427 /* duplicate, ignore */
1430 kx->last_packets_bitmap |= rotbit;
1432 if (kx->last_sequence_number_received < snum)
1434 unsigned int shift = (snum - kx->last_sequence_number_received);
1436 if (shift >= 8 * sizeof (kx->last_packets_bitmap))
1437 kx->last_packets_bitmap = 0;
1439 kx->last_packets_bitmap <<= shift;
1440 kx->last_sequence_number_received = snum;
1443 /* check timestamp */
1444 t = GNUNET_TIME_absolute_ntoh (pt->timestamp);
1445 if (GNUNET_TIME_absolute_get_duration (t).rel_value >
1446 MAX_MESSAGE_AGE.rel_value)
1448 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
1449 _("Message received far too old (%llu ms). Content ignored.\n"),
1450 GNUNET_TIME_absolute_get_duration (t).rel_value);
1451 GNUNET_STATISTICS_update (GSC_stats,
1453 ("# bytes dropped (ancient message)"), size,
1458 /* process decrypted message(s) */
1459 update_timeout (kx);
1460 GNUNET_STATISTICS_update (GSC_stats,
1461 gettext_noop ("# bytes of payload decrypted"),
1462 size - sizeof (struct EncryptedMessage), GNUNET_NO);
1464 dmc.atsi_count = atsi_count;
1465 dmc.peer = &kx->peer;
1467 GNUNET_SERVER_mst_receive (mst, &dmc, &buf[sizeof (struct EncryptedMessage)],
1468 size - sizeof (struct EncryptedMessage),
1469 GNUNET_YES, GNUNET_NO))
1470 GNUNET_break_op (0);
1475 * Deliver P2P message to interested clients.
1476 * Invokes send twice, once for clients that want the full message, and once
1477 * for clients that only want the header
1479 * @param cls always NULL
1480 * @param client who sent us the message (struct GSC_KeyExchangeInfo)
1481 * @param m the message
1484 deliver_message (void *cls, void *client, const struct GNUNET_MessageHeader *m)
1486 struct DeliverMessageContext *dmc = client;
1488 switch (ntohs (m->type))
1490 case GNUNET_MESSAGE_TYPE_CORE_BINARY_TYPE_MAP:
1491 case GNUNET_MESSAGE_TYPE_CORE_COMPRESSED_TYPE_MAP:
1492 GSC_SESSIONS_set_typemap (dmc->peer,
1496 GSC_CLIENTS_deliver_message (dmc->peer,
1497 dmc->atsi, dmc->atsi_count,
1500 GNUNET_CORE_OPTION_SEND_FULL_INBOUND);
1501 GSC_CLIENTS_deliver_message (dmc->peer,
1502 dmc->atsi, dmc->atsi_count,
1504 sizeof (struct GNUNET_MessageHeader),
1505 GNUNET_CORE_OPTION_SEND_HDR_INBOUND);
1511 * Initialize KX subsystem.
1513 * @return GNUNET_OK on success, GNUNET_SYSERR on failure
1521 GNUNET_CONFIGURATION_get_value_filename (GSC_cfg, "GNUNETD", "HOSTKEY",
1524 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1525 _("Core service is lacking HOSTKEY configuration setting. Exiting.\n"));
1526 return GNUNET_SYSERR;
1528 my_private_key = GNUNET_CRYPTO_rsa_key_create_from_file (keyfile);
1529 GNUNET_free (keyfile);
1530 if (my_private_key == NULL)
1532 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1533 _("Core service could not access hostkey. Exiting.\n"));
1534 return GNUNET_SYSERR;
1536 GNUNET_CRYPTO_rsa_key_get_public (my_private_key, &my_public_key);
1537 GNUNET_CRYPTO_hash (&my_public_key, sizeof (my_public_key),
1538 &GSC_my_identity.hashPubKey);
1539 peerinfo = GNUNET_PEERINFO_connect (GSC_cfg);
1540 if (NULL == peerinfo)
1542 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1543 _("Could not access PEERINFO service. Exiting.\n"));
1544 GNUNET_CRYPTO_rsa_key_free (my_private_key);
1545 my_private_key = NULL;
1546 return GNUNET_SYSERR;
1548 mst = GNUNET_SERVER_mst_create (&deliver_message, NULL);
1554 * Shutdown KX subsystem.
1559 if (my_private_key != NULL)
1561 GNUNET_CRYPTO_rsa_key_free (my_private_key);
1562 my_private_key = NULL;
1564 if (peerinfo != NULL)
1566 GNUNET_PEERINFO_disconnect (peerinfo);
1571 GNUNET_SERVER_mst_destroy (mst);
1576 /* end of gnunet-service-core_kx.c */