5 Author: Pekka Riikonen <priikone@poseidon.pspt.fi>
7 Copyright (C) 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 the Key Agreement packet processing and actual
22 key agreement routines. This file has nothing to do with the actual
23 connection key exchange protocol, it is implemented in the client.c
24 and in protocol.c. This file implements the client-to-client key
25 agreement as defined by the SILC protocol. */
27 #include "clientlibincludes.h"
28 #include "client_internal.h"
30 SILC_TASK_CALLBACK(silc_client_key_agreement_final);
31 SILC_TASK_CALLBACK(silc_client_process_key_agreement);
32 SILC_TASK_CALLBACK(silc_client_key_agreement_timeout);
33 SILC_TASK_CALLBACK(silc_client_perform_key_agreement_start);
35 /* Key agreement context */
36 struct SilcClientKeyAgreementStruct {
38 SilcClientConnection conn;
39 int fd; /* Listening/connection socket */
40 SilcSocketConnection sock; /* Remote socket connection */
41 SilcClientEntry client_entry; /* Destination client */
42 SilcKeyAgreementCallback completion; /* Key agreement completion */
43 void *context; /* User context */
44 SilcTask timeout; /* Timeout task */
45 SilcClientKEInternalContext *proto_ctx; /* Key Exchange protocol context */
48 /* Packet sending function used by the SKE in the key agreement process. */
50 static void silc_client_key_agreement_send_packet(SilcSKE ske,
55 SilcProtocol protocol = (SilcProtocol)context;
56 SilcClientKEInternalContext *ctx =
57 (SilcClientKEInternalContext *)protocol->context;
60 /* Send the packet immediately. We will assure that the packet is not
61 encrypted by setting the socket's user_data pointer to NULL. The
62 silc_client_packet_send would take the keys (wrong keys that is,
63 because user_data is the current SilcClientConnection) from it and
64 we cannot allow that. The packets are never encrypted when doing SKE
65 with another client. */
66 tmp = ske->sock->user_data;
67 ske->sock->user_data = NULL;
68 silc_client_packet_send(ctx->client, ske->sock, type, NULL, 0, NULL, NULL,
69 packet->data, packet->len, TRUE);
70 ske->sock->user_data = tmp;
73 /* Timeout callback that is called to close the connection and free the
74 socket connection data. */
76 SILC_TASK_CALLBACK(silc_client_key_agreement_close)
78 SilcClientKeyAgreement ke = (SilcClientKeyAgreement)context;
80 silc_schedule_unset_listen_fd(ke->client->schedule, ke->sock->sock);
81 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
82 silc_net_close_connection(ke->sock->sock);
83 silc_net_close_connection(ke->fd);
84 silc_socket_free(ke->sock);
88 /* This callback is called after the key agreement protocol has been
89 performed. This calls the final completion callback for the application. */
91 SILC_TASK_CALLBACK(silc_client_key_agreement_final)
93 SilcProtocol protocol = (SilcProtocol)context;
94 SilcClientKEInternalContext *ctx =
95 (SilcClientKEInternalContext *)protocol->context;
96 SilcClient client = (SilcClient)ctx->client;
97 SilcClientKeyAgreement ke = (SilcClientKeyAgreement)ctx->context;
99 SILC_LOG_DEBUG(("Start"));
101 if (protocol->state == SILC_PROTOCOL_STATE_ERROR ||
102 protocol->state == SILC_PROTOCOL_STATE_FAILURE) {
103 /* Error occured during protocol */
104 ke->client_entry->ke = NULL;
105 ke->completion(ke->client, ke->conn, ke->client_entry,
106 SILC_KEY_AGREEMENT_ERROR, NULL, ke->context);
107 silc_ske_free_key_material(ctx->keymat);
111 /* Pass the negotiated key material to the application. The application
112 is responsible of freeing the key material. */
113 ke->client_entry->ke = NULL;
114 ke->completion(ke->client, ke->conn, ke->client_entry,
115 SILC_KEY_AGREEMENT_OK, ctx->keymat, ke->context);
118 silc_protocol_free(protocol);
120 silc_ske_free(ctx->ske);
122 silc_free(ctx->dest_id);
123 silc_task_unregister_by_fd(client->io_queue, ke->fd);
124 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
125 silc_net_close_connection(ke->fd);
127 silc_task_unregister(client->timeout_queue, ke->timeout);
128 silc_client_del_socket(ke->client, ke->sock);
130 silc_task_register(client->timeout_queue, 0,
131 silc_client_key_agreement_close,
133 SILC_TASK_TIMEOUT, SILC_TASK_PRI_NORMAL);
138 /* Key agreement callback that is called when remote end has initiated
139 the key agreement protocol. This accepts the incoming TCP/IP connection
140 for the key agreement protocol. */
142 SILC_TASK_CALLBACK(silc_client_process_key_agreement)
144 SilcClientKeyAgreement ke = (SilcClientKeyAgreement)context;
145 SilcClient client = ke->client;
146 SilcClientConnection conn = ke->conn;
147 SilcSocketConnection newsocket;
148 SilcClientKEInternalContext *proto_ctx;
151 SILC_LOG_DEBUG(("Start"));
153 sock = silc_net_accept_connection(ke->fd);
155 client->ops->say(client, conn,
156 "Could not accept key agreement connection: ",
158 ke->client_entry->ke = NULL;
159 ke->completion(ke->client, ke->conn, ke->client_entry,
160 SILC_KEY_AGREEMENT_ERROR, NULL, ke->context);
161 silc_task_unregister_by_fd(client->io_queue, ke->fd);
162 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
163 silc_net_close_connection(ke->fd);
165 silc_task_unregister(client->timeout_queue, ke->timeout);
170 /* Set socket options */
171 silc_net_set_socket_nonblock(sock);
172 silc_net_set_socket_opt(sock, SOL_SOCKET, SO_REUSEADDR, 1);
174 /* Create socket for this connection (it is of type UNKNOWN since this
175 really is not a real SILC connection. It is only for the key
176 agreement protocol). */
177 silc_socket_alloc(sock, SILC_SOCKET_TYPE_UNKNOWN, (void *)conn, &newsocket);
178 ke->sock = newsocket;
180 /* Perform name and address lookups for the remote host. */
181 silc_net_check_host_by_sock(sock, &newsocket->hostname, &newsocket->ip);
182 if (!newsocket->hostname && !newsocket->ip) {
183 client->ops->say(client, conn,
184 "Could not resolve the remote IP or hostname");
185 ke->client_entry->ke = NULL;
186 ke->completion(ke->client, ke->conn, ke->client_entry,
187 SILC_KEY_AGREEMENT_ERROR, NULL, ke->context);
188 silc_task_unregister_by_fd(client->io_queue, ke->fd);
189 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
190 silc_net_close_connection(ke->fd);
192 silc_task_unregister(client->timeout_queue, ke->timeout);
196 if (!newsocket->hostname)
197 newsocket->hostname = strdup(newsocket->ip);
198 newsocket->port = silc_net_get_remote_port(sock);
199 silc_client_add_socket(client, newsocket);
201 /* Allocate internal context for key exchange protocol. This is
202 sent as context for the protocol. */
203 proto_ctx = silc_calloc(1, sizeof(*proto_ctx));
204 proto_ctx->client = client;
205 proto_ctx->sock = silc_socket_dup(newsocket);
206 proto_ctx->rng = client->rng;
207 proto_ctx->responder = TRUE;
208 proto_ctx->context = context;
209 proto_ctx->send_packet = silc_client_key_agreement_send_packet;
210 proto_ctx->verify = silc_client_protocol_ke_verify_key;
211 ke->proto_ctx = proto_ctx;
213 /* Prepare the connection for key exchange protocol. We allocate the
214 protocol but will not start it yet. The connector will be the
215 initiator of the protocol thus we will wait for initiation from
216 there before we start the protocol. */
217 silc_protocol_alloc(SILC_PROTOCOL_CLIENT_KEY_EXCHANGE,
218 &newsocket->protocol, proto_ctx,
219 silc_client_key_agreement_final);
221 /* Register the connection for network input and output. This sets
222 that scheduler will listen for incoming packets for this connection
223 and sets that outgoing packets may be sent to this connection as well.
224 However, this doesn't set the scheduler for outgoing traffic, it
225 will be set separately by calling SILC_CLIENT_SET_CONNECTION_FOR_OUTPUT,
226 later when outgoing data is available. */
227 context = (void *)client;
228 SILC_CLIENT_REGISTER_CONNECTION_FOR_IO(sock);
231 /* Timeout occured during key agreement. This means that the key agreement
232 protocol was not completed in the specified timeout. We will call the
233 completion callback. */
235 SILC_TASK_CALLBACK(silc_client_key_agreement_timeout)
237 SilcClientKeyAgreement ke = (SilcClientKeyAgreement)context;
239 ke->client_entry->ke = NULL;
240 ke->completion(ke->client, ke->conn, ke->client_entry,
241 SILC_KEY_AGREEMENT_TIMEOUT, NULL, ke->context);
244 silc_client_del_socket(ke->client, ke->sock);
245 silc_socket_free(ke->sock);
247 if (ke->proto_ctx && ke->proto_ctx->ske)
248 silc_ske_free(ke->proto_ctx->ske);
249 ke->client_entry->ke = NULL;
251 silc_task_unregister_by_fd(ke->client->io_queue, ke->fd);
252 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
253 silc_net_close_connection(ke->fd);
257 /* Sends key agreement request to the remote client indicated by the
258 `client_entry'. If the caller provides the `hostname' and the `port'
259 arguments then the library will bind the client to that hostname and
260 that port for the key agreement protocol. It also sends the `hostname'
261 and the `port' in the key agreement packet to the remote client. This
262 would indicate that the remote client may initiate the key agreement
263 protocol to the `hostname' on the `port'. If port is zero then the
264 bound port is undefined (the operating system defines it).
266 If the `hostname' and `port' is not provided then empty key agreement
267 packet is sent to the remote client. The remote client may reply with
268 the same packet including its hostname and port. If the library receives
269 the reply from the remote client the `key_agreement' client operation
270 callback will be called to verify whether the user wants to perform the
271 key agreement or not.
273 NOTE: If the application provided the `hostname' and the `port' and the
274 remote side initiates the key agreement protocol it is not verified
275 from the user anymore whether the protocol should be executed or not.
276 By setting the `hostname' and `port' the user gives permission to
277 perform the protocol (we are responder in this case).
279 NOTE: If the remote side decides not to initiate the key agreement
280 or decides not to reply with the key agreement packet then we cannot
281 perform the key agreement at all. If the key agreement protocol is
282 performed the `completion' callback with the `context' will be called.
283 If remote side decides to ignore the request the `completion' will be
284 called after the specified timeout, `timeout_secs'.
286 NOTE: If the `hostname' and the `port' was not provided the `completion'
287 will not be called at all since this does nothing more than sending
288 a packet to the remote host.
290 NOTE: There can be only one active key agreement for one client entry.
291 Before setting new one, the old one must be finished (it is finished
292 after calling the completion callback) or the function
293 silc_client_abort_key_agreement must be called. */
295 void silc_client_send_key_agreement(SilcClient client,
296 SilcClientConnection conn,
297 SilcClientEntry client_entry,
301 SilcKeyAgreementCallback completion,
304 SilcSocketConnection sock = conn->sock;
305 SilcClientKeyAgreement ke = NULL;
308 assert(client_entry);
310 if (client_entry->ke)
313 /* Create the listener if hostname and port was provided */
315 ke = silc_calloc(1, sizeof(*ke));
316 ke->fd = silc_net_create_server(port, hostname);
319 client->ops->say(client, conn,
320 "Cannot create listener on %s on port %d: %s",
321 hostname, port, strerror(errno));
322 completion(client, conn, client_entry, SILC_KEY_AGREEMENT_FAILURE,
330 ke->client_entry = client_entry;
331 ke->completion = completion;
332 ke->context = context;
334 /* Add listener task to the queue. This task receives the key
336 silc_task_register(client->io_queue, ke->fd,
337 silc_client_process_key_agreement,
340 SILC_TASK_PRI_NORMAL);
342 /* Register a timeout task that will be executed if the connector
343 will not start the key exchange protocol within the specified
345 ke->timeout = silc_task_register(client->timeout_queue, 0,
346 silc_client_key_agreement_timeout,
347 (void *)ke, timeout_secs, 0,
348 SILC_TASK_TIMEOUT, SILC_TASK_PRI_LOW);
351 /* Encode the key agreement payload */
352 buffer = silc_key_agreement_payload_encode(hostname,
354 silc_net_get_local_port(ke->fd));
356 /* Send the key agreement packet to the client */
357 silc_client_packet_send(client, sock, SILC_PACKET_KEY_AGREEMENT,
358 client_entry->id, SILC_ID_CLIENT, NULL, NULL,
359 buffer->data, buffer->len, FALSE);
364 silc_client_connect_to_client_internal(SilcClientInternalConnectContext *ctx)
368 /* Create connection to server asynchronously */
369 sock = silc_net_create_connection_async(ctx->port, ctx->host);
373 /* Register task that will receive the async connect and will
375 ctx->task = silc_task_register(ctx->client->io_queue, sock,
376 silc_client_perform_key_agreement_start,
379 SILC_TASK_PRI_NORMAL);
380 silc_task_reset_iotype(ctx->task, SILC_TASK_WRITE);
381 silc_schedule_set_listen_fd(ctx->client->schedule, sock, ctx->task->iomask);
388 /* Routine used by silc_client_perform_key_agreement to create connection
389 to the remote client on specified port. */
392 silc_client_connect_to_client(SilcClient client,
393 SilcClientConnection conn, int port,
394 char *host, void *context)
396 SilcClientInternalConnectContext *ctx;
398 /* Allocate internal context for connection process. This is
399 needed as we are doing async connecting. */
400 ctx = silc_calloc(1, sizeof(*ctx));
401 ctx->client = client;
403 ctx->host = strdup(host);
406 ctx->context = context;
408 /* Do the actual connecting process */
409 return silc_client_connect_to_client_internal(ctx);
412 /* Callback that is called after connection has been created. This actually
413 starts the key agreement protocol. This is initiator function. */
415 SILC_TASK_CALLBACK(silc_client_perform_key_agreement_start)
417 SilcClientInternalConnectContext *ctx =
418 (SilcClientInternalConnectContext *)context;
419 SilcClient client = ctx->client;
420 SilcClientConnection conn = ctx->conn;
421 SilcClientKeyAgreement ke = (SilcClientKeyAgreement)ctx->context;
422 int opt, opt_len = sizeof(opt);
424 SILC_LOG_DEBUG(("Start"));
426 /* Check the socket status as it might be in error */
427 silc_net_get_socket_opt(fd, SOL_SOCKET, SO_ERROR, &opt, &opt_len);
429 if (ctx->tries < 2) {
430 /* Connection failed but lets try again */
431 client->ops->say(client, conn, "Could not connect to client %s: %s",
432 ctx->host, strerror(opt));
433 client->ops->say(client, conn,
434 "Connecting to port %d of client %s resumed",
435 ctx->port, ctx->host);
437 /* Unregister old connection try */
438 silc_schedule_unset_listen_fd(client->schedule, fd);
439 silc_net_close_connection(fd);
440 silc_task_unregister(client->io_queue, ctx->task);
443 silc_client_connect_to_client_internal(ctx);
446 /* Connection failed and we won't try anymore */
447 client->ops->say(client, conn, "Could not connect to client %s: %s",
448 ctx->host, strerror(opt));
449 silc_schedule_unset_listen_fd(client->schedule, fd);
450 silc_net_close_connection(fd);
451 silc_task_unregister(client->io_queue, ctx->task);
452 silc_free(ctx->host);
455 /* Call the completion callback */
456 ke->completion(ke->client, ke->conn, ke->client_entry,
457 SILC_KEY_AGREEMENT_FAILURE, NULL, ke->context);
463 silc_schedule_unset_listen_fd(client->schedule, fd);
464 silc_task_unregister(client->io_queue, ctx->task);
468 /* Now actually perform the key agreement protocol */
469 silc_client_perform_key_agreement_fd(ke->client, ke->conn,
470 ke->client_entry, ke->fd, ctx->host,
471 ke->completion, ke->context);
473 silc_free(ctx->host);
477 /* Performs the actual key agreement protocol. Application may use this
478 to initiate the key agreement protocol. This can be called for example
479 after the application has received the `key_agreement' client operation,
480 and did not return TRUE from it.
482 The `hostname' is the remote hostname (or IP address) and the `port'
483 is the remote port. The `completion' callback with the `context' will
484 be called after the key agreement protocol.
486 NOTE: If the application returns TRUE in the `key_agreement' client
487 operation the library will automatically start the key agreement. In this
488 case the application must not call this function. However, application
489 may choose to just ignore the `key_agreement' client operation (and
490 merely just print information about it on the screen) and call this
491 function when the user whishes to do so (by, for example, giving some
492 specific command). Thus, the API provides both, automatic and manual
493 initiation of the key agreement. Calling this function is the manual
494 initiation and returning TRUE in the `key_agreement' client operation
495 is the automatic initiation. */
497 void silc_client_perform_key_agreement(SilcClient client,
498 SilcClientConnection conn,
499 SilcClientEntry client_entry,
502 SilcKeyAgreementCallback completion,
505 SilcClientKeyAgreement ke;
507 SILC_LOG_DEBUG(("Start"));
509 assert(client_entry && hostname && port);
511 ke = silc_calloc(1, sizeof(*ke));
514 ke->client_entry = client_entry;
515 ke->completion = completion;
516 ke->context = context;
518 /* Connect to the remote client */
519 ke->fd = silc_client_connect_to_client(client, conn, port, hostname, ke);
521 completion(client, conn, client_entry, SILC_KEY_AGREEMENT_FAILURE,
528 /* Same as above but application has created already the connection to
529 the remote host. The `sock' is the socket to the remote connection.
530 Application can use this function if it does not want the client library
531 to create the connection. */
533 void silc_client_perform_key_agreement_fd(SilcClient client,
534 SilcClientConnection conn,
535 SilcClientEntry client_entry,
538 SilcKeyAgreementCallback completion,
541 SilcClientKeyAgreement ke;
542 SilcClientKEInternalContext *proto_ctx;
543 SilcProtocol protocol;
545 SILC_LOG_DEBUG(("Start"));
547 assert(client_entry);
549 ke = silc_calloc(1, sizeof(*ke));
552 ke->client_entry = client_entry;
554 ke->completion = completion;
555 ke->context = context;
557 /* Allocate new socket connection object */
558 silc_socket_alloc(sock, SILC_SOCKET_TYPE_UNKNOWN, (void *)conn, &ke->sock);
559 silc_client_add_socket(client, ke->sock);
560 ke->sock->hostname = strdup(hostname);
561 ke->sock->port = silc_net_get_remote_port(sock);
563 /* Allocate internal context for key exchange protocol. This is
564 sent as context for the protocol. */
565 proto_ctx = silc_calloc(1, sizeof(*proto_ctx));
566 proto_ctx->client = client;
567 proto_ctx->sock = silc_socket_dup(ke->sock);
568 proto_ctx->rng = client->rng;
569 proto_ctx->responder = FALSE;
570 proto_ctx->context = ke;
571 proto_ctx->send_packet = silc_client_key_agreement_send_packet;
572 proto_ctx->verify = silc_client_protocol_ke_verify_key;
573 ke->proto_ctx = proto_ctx;
575 /* Perform key exchange protocol. */
576 silc_protocol_alloc(SILC_PROTOCOL_CLIENT_KEY_EXCHANGE,
577 &protocol, (void *)proto_ctx,
578 silc_client_key_agreement_final);
579 ke->sock->protocol = protocol;
581 /* Register the connection for network input and output. This sets
582 that scheduler will listen for incoming packets for this connection
583 and sets that outgoing packets may be sent to this connection as well.
584 However, this doesn't set the scheduler for outgoing traffic, it will
585 be set separately by calling SILC_CLIENT_SET_CONNECTION_FOR_OUTPUT,
586 later when outgoing data is available. */
587 context = (void *)client;
588 SILC_CLIENT_REGISTER_CONNECTION_FOR_IO(sock);
590 /* Execute the protocol */
591 silc_protocol_execute(protocol, client->timeout_queue, 0, 0);
594 /* This function can be called to unbind the hostname and the port for
595 the key agreement protocol. However, this function has effect only
596 before the key agreement protocol has been performed. After it has
597 been performed the library will automatically unbind the port. The
598 `client_entry' is the client to which we sent the key agreement
601 void silc_client_abort_key_agreement(SilcClient client,
602 SilcClientConnection conn,
603 SilcClientEntry client_entry)
605 assert(client_entry);
607 if (client_entry->ke) {
608 if (client_entry->ke->sock) {
609 silc_client_del_socket(client_entry->ke->client, client_entry->ke->sock);
610 silc_socket_free(client_entry->ke->sock);
612 client_entry->ke = NULL;
613 silc_task_unregister_by_fd(client->io_queue, client_entry->ke->fd);
614 if (client_entry->ke->timeout)
615 silc_task_unregister(client->timeout_queue,
616 client_entry->ke->timeout);
617 silc_free(client_entry->ke);
621 /* Callback function that is called after we've resolved the client
622 information who sent us the key agreement packet from the server.
623 We actually call the key_agreement client operation now. */
626 silc_client_key_agreement_resolve_cb(SilcClient client,
627 SilcClientConnection conn,
628 SilcClientEntry *clients,
629 uint32 clients_count,
632 SilcPacketContext *packet = (SilcPacketContext *)context;
633 SilcKeyAgreementPayload payload;
635 SilcKeyAgreementCallback completion;
636 void *completion_context;
641 /* Parse the key agreement payload */
642 payload = silc_key_agreement_payload_parse(packet->buffer);
646 /* Call the key_agreement client operation */
647 ret = client->ops->key_agreement(client, conn, clients[0],
648 silc_key_agreement_get_hostname(payload),
649 silc_key_agreement_get_port(payload),
650 &completion, &completion_context);
652 /* If the user returned TRUE then we'll start the key agreement right
653 here and right now. */
655 silc_client_perform_key_agreement(client, conn, clients[0],
656 silc_key_agreement_get_hostname(payload),
657 silc_key_agreement_get_port(payload),
658 completion, completion_context);
660 silc_key_agreement_payload_free(payload);
663 silc_packet_context_free(packet);
666 /* Received Key Agreement packet from remote client. Process the packet
667 and resolve the client information from the server before actually
668 letting the application know that we've received this packet. Then
669 call the key_agreement client operation and let the user decide
670 whether we perform the key agreement protocol now or not. */
672 void silc_client_key_agreement(SilcClient client,
673 SilcSocketConnection sock,
674 SilcPacketContext *packet)
676 SilcClientID *remote_id;
678 if (packet->src_id_type != SILC_ID_CLIENT)
681 remote_id = silc_id_str2id(packet->src_id, packet->src_id_len,
686 silc_client_get_client_by_id_resolve(client, sock->user_data, remote_id,
687 silc_client_key_agreement_resolve_cb,
688 silc_packet_context_dup(packet));
689 silc_free(remote_id);