5 Author: Pekka Riikonen <priikone@poseidon.pspt.fi>
7 Copyright (C) 1997 - 2001 Pekka Riikonen
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
21 /* This file includes channel message sending and receiving routines,
22 channel key receiving and setting, and channel private key handling
25 #include "clientlibincludes.h"
26 #include "client_internal.h"
28 /* Sends packet to the `channel'. Packet to channel is always encrypted
29 differently from "normal" packets. SILC header of the packet is
30 encrypted with the next receiver's key and the rest of the packet is
31 encrypted with the channel specific key. Padding and HMAC is computed
32 with the next receiver's key. The `data' is the channel message. If
33 the `force_send' is TRUE then the packet is sent immediately. */
35 void silc_client_send_channel_message(SilcClient client,
36 SilcClientConnection conn,
37 SilcChannelEntry channel,
38 SilcChannelPrivateKey key,
39 SilcMessageFlags flags,
45 SilcSocketConnection sock = conn->sock;
47 SilcPacketContext packetdata;
50 unsigned char *id_string;
54 SILC_LOG_DEBUG(("Sending packet to channel"));
56 /* Take the key to be used */
57 if (channel->mode & SILC_CHANNEL_MODE_PRIVKEY) {
59 /* Use key application specified */
62 } else if (channel->curr_key) {
63 /* Use current private key */
64 cipher = channel->curr_key->cipher;
65 hmac = channel->curr_key->hmac;
66 } else if (!channel->curr_key && channel->private_keys) {
67 /* Use just some private key since we don't know what to use
68 and private keys are set. */
69 silc_dlist_start(channel->private_keys);
70 key = silc_dlist_get(channel->private_keys);
74 /* Use this key as current private key */
75 channel->curr_key = key;
77 /* Use normal channel key generated by the server */
78 cipher = channel->channel_key;
82 /* Use normal channel key generated by the server */
83 cipher = channel->channel_key;
90 block_len = silc_cipher_get_block_len(cipher);
93 iv_len = silc_cipher_get_block_len(cipher);
94 if (channel->iv[0] == '\0')
95 for (i = 0; i < iv_len; i++) channel->iv[i] =
96 silc_rng_get_byte(client->rng);
98 silc_hash_make(client->md5hash, channel->iv, iv_len, channel->iv);
100 /* Encode the channel payload. This also encrypts the message payload. */
101 payload = silc_channel_message_payload_encode(flags, data_len, data, iv_len,
102 channel->iv, cipher, hmac);
104 /* Get data used in packet header encryption, keys and stuff. */
105 cipher = conn->send_key;
106 hmac = conn->hmac_send;
107 id_string = silc_id_id2str(channel->id, SILC_ID_CHANNEL);
109 /* Set the packet context pointers. The destination ID is always
110 the Channel ID of the channel. Server and router will handle the
111 distribution of the packet. */
112 packetdata.flags = 0;
113 packetdata.type = SILC_PACKET_CHANNEL_MESSAGE;
114 packetdata.src_id = conn->local_id_data;
115 packetdata.src_id_len = silc_id_get_len(conn->local_id, SILC_ID_CLIENT);
116 packetdata.src_id_type = SILC_ID_CLIENT;
117 packetdata.dst_id = id_string;
118 packetdata.dst_id_len = silc_id_get_len(channel->id, SILC_ID_CHANNEL);
119 packetdata.dst_id_type = SILC_ID_CHANNEL;
120 packetdata.truelen = payload->len + SILC_PACKET_HEADER_LEN +
121 packetdata.src_id_len + packetdata.dst_id_len;
122 packetdata.padlen = SILC_PACKET_PADLEN((SILC_PACKET_HEADER_LEN +
123 packetdata.src_id_len +
124 packetdata.dst_id_len), block_len);
126 /* Prepare outgoing data buffer for packet sending */
127 silc_packet_send_prepare(sock,
128 SILC_PACKET_HEADER_LEN +
129 packetdata.src_id_len +
130 packetdata.dst_id_len,
134 packetdata.buffer = sock->outbuf;
136 /* Put the channel message payload to the outgoing data buffer */
137 silc_buffer_put(sock->outbuf, payload->data, payload->len);
139 /* Create the outgoing packet */
140 silc_packet_assemble(&packetdata, cipher);
142 /* Encrypt the header and padding of the packet. This is encrypted
143 with normal session key shared with our server. */
144 silc_packet_encrypt(cipher, hmac, conn->psn_send++,
145 sock->outbuf, SILC_PACKET_HEADER_LEN +
146 packetdata.src_id_len + packetdata.dst_id_len +
149 SILC_LOG_HEXDUMP(("Packet to channel, len %d", sock->outbuf->len),
150 sock->outbuf->data, sock->outbuf->len);
152 /* Now actually send the packet */
153 silc_client_packet_send_real(client, sock, force_send);
154 silc_buffer_free(payload);
155 silc_free(id_string);
158 static void silc_client_channel_message_cb(SilcClient client,
159 SilcClientConnection conn,
160 SilcClientEntry *clients,
161 uint32 clients_count,
164 SilcPacketContext *packet = (SilcPacketContext *)context;
167 silc_client_channel_message(client, conn->sock, packet);
168 silc_packet_context_free(packet);
171 /* Process received message to a channel (or from a channel, really). This
172 decrypts the channel message with channel specific key and parses the
173 channel payload. Finally it displays the message on the screen. */
175 void silc_client_channel_message(SilcClient client,
176 SilcSocketConnection sock,
177 SilcPacketContext *packet)
179 SilcClientConnection conn = (SilcClientConnection)sock->user_data;
180 SilcBuffer buffer = packet->buffer;
181 SilcChannelMessagePayload payload = NULL;
182 SilcChannelID *id = NULL;
183 SilcChannelEntry channel;
185 SilcIDCacheEntry id_cache = NULL;
186 SilcClientID *client_id = NULL;
188 unsigned char *message;
190 SILC_LOG_DEBUG(("Start"));
193 if (packet->dst_id_type != SILC_ID_CHANNEL)
196 client_id = silc_id_str2id(packet->src_id, packet->src_id_len,
200 id = silc_id_str2id(packet->dst_id, packet->dst_id_len, SILC_ID_CHANNEL);
204 /* Find the channel entry from channels on this connection */
205 if (!silc_idcache_find_by_id_one(conn->channel_cache, (void *)id, &id_cache))
208 channel = (SilcChannelEntry)id_cache->context;
210 /* If there is no channel private key then just decrypt the message
211 with the channel key. If private keys are set then just go through
212 all private keys and check what decrypts correctly. */
213 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY)) {
214 /* Parse the channel message payload. This also decrypts the payload */
215 payload = silc_channel_message_payload_parse(buffer, channel->channel_key,
218 /* If decryption failed and we have just performed channel key rekey
219 we will use the old key in decryption. If that fails too then we
220 cannot do more and will drop the packet. */
222 if (!channel->old_channel_key)
225 payload = silc_channel_message_payload_parse(buffer,
226 channel->old_channel_key,
231 } else if (channel->private_keys) {
232 SilcChannelPrivateKey entry;
234 silc_dlist_start(channel->private_keys);
235 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
236 /* Parse the channel message payload. This also decrypts the payload */
237 payload = silc_channel_message_payload_parse(buffer, entry->cipher,
242 if (entry == SILC_LIST_END)
248 /* Find client entry */
249 silc_list_start(channel->clients);
250 while ((chu = silc_list_get(channel->clients)) != SILC_LIST_END) {
251 if (SILC_ID_CLIENT_COMPARE(chu->client->id, client_id)) {
258 /* Resolve the client info */
259 silc_client_get_client_by_id_resolve(client, conn, client_id,
260 silc_client_channel_message_cb,
261 silc_packet_context_dup(packet));
265 message = silc_channel_message_get_data(payload, NULL);
267 /* Pass the message to application */
268 client->ops->channel_message(client, conn, chu->client, channel,
269 silc_channel_message_get_flags(payload),
276 silc_free(client_id);
278 silc_channel_message_payload_free(payload);
281 /* Timeout callback that is called after a short period of time after the
282 new channel key has been created. This removes the old channel key all
285 SILC_TASK_CALLBACK(silc_client_save_channel_key_rekey)
287 SilcChannelEntry channel = (SilcChannelEntry)context;
289 if (channel->old_channel_key)
290 silc_cipher_free(channel->old_channel_key);
291 if (channel->old_hmac)
292 silc_hmac_free(channel->old_hmac);
293 channel->old_channel_key = NULL;
294 channel->old_hmac = NULL;
295 channel->rekey_task = NULL;
298 /* Saves channel key from encoded `key_payload'. This is used when we
299 receive Channel Key Payload and when we are processing JOIN command
302 void silc_client_save_channel_key(SilcClientConnection conn,
303 SilcBuffer key_payload,
304 SilcChannelEntry channel)
306 unsigned char *id_string, *key, *cipher, *hmac, hash[32];
309 SilcIDCacheEntry id_cache = NULL;
310 SilcChannelKeyPayload payload;
312 payload = silc_channel_key_payload_parse(key_payload);
316 id_string = silc_channel_key_get_id(payload, &tmp_len);
318 silc_channel_key_payload_free(payload);
322 id = silc_id_str2id(id_string, tmp_len, SILC_ID_CHANNEL);
324 silc_channel_key_payload_free(payload);
330 if (!silc_idcache_find_by_id_one(conn->channel_cache,
331 (void *)id, &id_cache))
334 /* Get channel entry */
335 channel = (SilcChannelEntry)id_cache->context;
338 hmac = (channel->hmac ? (char *)silc_hmac_get_name(channel->hmac) :
341 /* Save the old key for a short period of time so that we can decrypt
342 channel message even after the rekey if some client would be sending
343 messages with the old key after the rekey. */
344 if (channel->old_channel_key)
345 silc_cipher_free(channel->old_channel_key);
346 if (channel->old_hmac)
347 silc_hmac_free(channel->old_hmac);
348 if (channel->rekey_task)
349 silc_schedule_task_del(conn->client->schedule, channel->rekey_task);
350 channel->old_channel_key = channel->channel_key;
351 channel->old_hmac = channel->hmac;
352 channel->rekey_task =
353 silc_schedule_task_add(conn->client->schedule, 0,
354 silc_client_save_channel_key_rekey, channel,
355 10, 0, SILC_TASK_TIMEOUT, SILC_TASK_PRI_NORMAL);
357 /* Free the old channel key data */
358 silc_free(channel->key);
361 key = silc_channel_key_get_key(payload, &tmp_len);
362 cipher = silc_channel_key_get_cipher(payload, NULL);
363 channel->key_len = tmp_len * 8;
364 channel->key = silc_calloc(tmp_len, sizeof(*channel->key));
365 memcpy(channel->key, key, tmp_len);
367 if (!silc_cipher_alloc(cipher, &channel->channel_key)) {
368 conn->client->ops->say(conn->client, conn, SILC_CLIENT_MESSAGE_AUDIT,
369 "Cannot talk to channel: unsupported cipher %s",
374 /* Set the cipher key */
375 silc_cipher_set_key(channel->channel_key, key, channel->key_len);
377 /* Generate HMAC key from the channel key data and set it */
378 silc_hmac_alloc(hmac, NULL, &channel->hmac);
379 silc_hash_make(silc_hmac_get_hash(channel->hmac), key, tmp_len, hash);
380 silc_hmac_set_key(channel->hmac, hash,
381 silc_hash_len(silc_hmac_get_hash(channel->hmac)));
382 memset(hash, 0, sizeof(hash));
386 silc_channel_key_payload_free(payload);
389 /* Processes received key for channel. The received key will be used
390 to protect the traffic on the channel for now on. Client must receive
391 the key to the channel before talking on the channel is possible.
392 This is the key that server has generated, this is not the channel
393 private key, it is entirely local setting. */
395 void silc_client_receive_channel_key(SilcClient client,
396 SilcSocketConnection sock,
399 SILC_LOG_DEBUG(("Received key for channel"));
402 silc_client_save_channel_key(sock->user_data, packet, NULL);
405 /* Adds private key for channel. This may be set only if the channel's mode
406 mask includes the SILC_CHANNEL_MODE_PRIVKEY. This returns FALSE if the
407 mode is not set. When channel has private key then the messages are
408 encrypted using that key. All clients on the channel must also know the
409 key in order to decrypt the messages. However, it is possible to have
410 several private keys per one channel. In this case only some of the
411 clients on the channel may know the one key and only some the other key.
413 If `cipher' and/or `hmac' is NULL then default values will be used
414 (aes-256-cbc for cipher and hmac-sha1-96 for hmac).
416 The private key for channel is optional. If it is not set then the
417 channel messages are encrypted using the channel key generated by the
418 server. However, setting the private key (or keys) for the channel
419 significantly adds security. If more than one key is set the library
420 will automatically try all keys at the message decryption phase. Note:
421 setting many keys slows down the decryption phase as all keys has to
422 be tried in order to find the correct decryption key. However, setting
423 a few keys does not have big impact to the decryption performace.
425 NOTE: that this is entirely local setting. The key set using this function
426 is not sent to the network at any phase.
428 NOTE: If the key material was originated by the SKE protocol (using
429 silc_client_send_key_agreement) then the `key' MUST be the
430 key->send_enc_key as this is dictated by the SILC protocol. However,
431 currently it is not expected that the SKE key material would be used
432 as channel private key. However, this API allows it. */
434 int silc_client_add_channel_private_key(SilcClient client,
435 SilcClientConnection conn,
436 SilcChannelEntry channel,
442 SilcChannelPrivateKey entry;
443 unsigned char hash[32];
444 SilcSKEKeyMaterial *keymat;
446 if (!(channel->mode & SILC_CHANNEL_MODE_PRIVKEY))
450 cipher = SILC_DEFAULT_CIPHER;
452 hmac = SILC_DEFAULT_HMAC;
454 if (!silc_cipher_is_supported(cipher))
457 if (!silc_hmac_is_supported(hmac))
460 /* Produce the key material */
461 keymat = silc_calloc(1, sizeof(*keymat));
462 if (silc_ske_process_key_material_data(key, key_len, 16, 256, 16,
463 client->md5hash, keymat)
464 != SILC_SKE_STATUS_OK)
467 /* Remove the current key, if it exists. */
468 if (channel->channel_key) {
469 silc_cipher_free(channel->channel_key);
470 memset(channel->key, 0, channel->key_len / 8);
471 silc_free(channel->key);
472 channel->channel_key = NULL;
474 channel->key_len = 0;
477 silc_hmac_free(channel->hmac);
478 channel->hmac = NULL;
481 if (!channel->private_keys)
482 channel->private_keys = silc_dlist_init();
485 entry = silc_calloc(1, sizeof(*entry));
486 entry->key = silc_calloc(keymat->enc_key_len / 8, sizeof(*entry->key));
487 memcpy(entry->key, keymat->send_enc_key, keymat->enc_key_len / 8);
488 entry->key_len = keymat->enc_key_len / 8;
490 /* Allocate the cipher and set the key*/
491 silc_cipher_alloc(cipher, &entry->cipher);
492 silc_cipher_set_key(entry->cipher, entry->key, keymat->enc_key_len);
494 /* Generate HMAC key from the channel key data and set it */
495 silc_hmac_alloc(hmac, NULL, &entry->hmac);
496 silc_hash_make(silc_hmac_get_hash(entry->hmac), entry->key,
497 entry->key_len, hash);
498 silc_hmac_set_key(entry->hmac, hash,
499 silc_hash_len(silc_hmac_get_hash(entry->hmac)));
500 memset(hash, 0, sizeof(hash));
502 /* Add to the private keys list */
503 silc_dlist_add(channel->private_keys, entry);
505 if (!channel->curr_key)
506 channel->curr_key = entry;
508 /* Free the key material */
509 silc_ske_free_key_material(keymat);
514 /* Removes all private keys from the `channel'. The old channel key is used
515 after calling this to protect the channel messages. Returns FALSE on
516 on error, TRUE otherwise. */
518 int silc_client_del_channel_private_keys(SilcClient client,
519 SilcClientConnection conn,
520 SilcChannelEntry channel)
522 SilcChannelPrivateKey entry;
524 if (!channel->private_keys)
527 silc_dlist_start(channel->private_keys);
528 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
529 silc_dlist_del(channel->private_keys, entry);
530 memset(entry->key, 0, entry->key_len);
531 silc_free(entry->key);
532 silc_cipher_free(entry->cipher);
533 silc_hmac_free(entry->hmac);
537 channel->curr_key = NULL;
539 silc_dlist_uninit(channel->private_keys);
540 channel->private_keys = NULL;
545 /* Removes and frees private key `key' from the channel `channel'. The `key'
546 is retrieved by calling the function silc_client_list_channel_private_keys.
547 The key is not used after this. If the key was last private key then the
548 old channel key is used hereafter to protect the channel messages. This
549 returns FALSE on error, TRUE otherwise. */
551 int silc_client_del_channel_private_key(SilcClient client,
552 SilcClientConnection conn,
553 SilcChannelEntry channel,
554 SilcChannelPrivateKey key)
556 SilcChannelPrivateKey entry;
558 if (!channel->private_keys)
561 silc_dlist_start(channel->private_keys);
562 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
564 if (channel->curr_key == entry)
565 channel->curr_key = NULL;
567 silc_dlist_del(channel->private_keys, entry);
568 memset(entry->key, 0, entry->key_len);
569 silc_free(entry->key);
570 silc_cipher_free(entry->cipher);
571 silc_hmac_free(entry->hmac);
574 if (silc_dlist_count(channel->private_keys) == 0) {
575 silc_dlist_uninit(channel->private_keys);
576 channel->private_keys = NULL;
586 /* Returns array (pointers) of private keys associated to the `channel'.
587 The caller must free the array by calling the function
588 silc_client_free_channel_private_keys. The pointers in the array may be
589 used to delete the specific key by giving the pointer as argument to the
590 function silc_client_del_channel_private_key. */
592 SilcChannelPrivateKey *
593 silc_client_list_channel_private_keys(SilcClient client,
594 SilcClientConnection conn,
595 SilcChannelEntry channel,
598 SilcChannelPrivateKey *keys = NULL, entry;
601 if (!channel->private_keys)
604 silc_dlist_start(channel->private_keys);
605 while ((entry = silc_dlist_get(channel->private_keys)) != SILC_LIST_END) {
606 keys = silc_realloc(keys, sizeof(*keys) * (count + 1));
617 /* Frees the SilcChannelPrivateKey array. */
619 void silc_client_free_channel_private_keys(SilcChannelPrivateKey *keys,