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_schedule_task_del_by_fd(client->schedule, ke->fd);
124 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
125 silc_net_close_connection(ke->fd);
127 silc_schedule_task_del(client->schedule, ke->timeout);
128 silc_client_del_socket(ke->client, ke->sock);
130 silc_schedule_task_add(client->schedule, 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, SILC_CLIENT_MESSAGE_AUDIT,
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_schedule_task_del_by_fd(client->schedule, ke->fd);
162 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
163 silc_net_close_connection(ke->fd);
165 silc_schedule_task_del(client->schedule, 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, SILC_CLIENT_MESSAGE_AUDIT,
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_schedule_task_del_by_fd(client->schedule, ke->fd);
189 silc_schedule_unset_listen_fd(ke->client->schedule, ke->fd);
190 silc_net_close_connection(ke->fd);
192 silc_schedule_task_del(client->schedule, 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_schedule_task_del_by_fd(ke->client->schedule, 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,
298 const char *hostname,
299 const char *bindhost,
302 SilcKeyAgreementCallback completion,
305 SilcSocketConnection sock = conn->sock;
306 SilcClientKeyAgreement ke = NULL;
309 assert(client_entry);
311 if (client_entry->ke)
314 /* Create the listener if hostname and port was provided.
315 * also, use bindhost if it was specified.
319 ke = silc_calloc(1, sizeof(*ke));
322 ke->fd = silc_net_create_server(port, bindhost);
324 ke->fd = silc_net_create_server(port, hostname);
327 client->ops->say(client, conn, SILC_CLIENT_MESSAGE_ERROR,
328 "Cannot create listener on %s on port %d: %s",
329 (bindhost) ? bindhost:hostname, port, strerror(errno));
330 completion(client, conn, client_entry, SILC_KEY_AGREEMENT_FAILURE,
339 ke->client_entry = client_entry;
340 ke->completion = completion;
341 ke->context = context;
343 /* Add listener task to the scheduler. This task receives the key
345 silc_schedule_task_add(client->schedule, ke->fd,
346 silc_client_process_key_agreement,
349 SILC_TASK_PRI_NORMAL);
351 /* Register a timeout task that will be executed if the connector
352 will not start the key exchange protocol within the specified
354 ke->timeout = silc_schedule_task_add(client->schedule, 0,
355 silc_client_key_agreement_timeout,
356 (void *)ke, timeout_secs, 0,
357 SILC_TASK_TIMEOUT, SILC_TASK_PRI_LOW);
360 /* Encode the key agreement payload */
361 buffer = silc_key_agreement_payload_encode(hostname,
363 silc_net_get_local_port(ke->fd));
365 /* Send the key agreement packet to the client */
366 silc_client_packet_send(client, sock, SILC_PACKET_KEY_AGREEMENT,
367 client_entry->id, SILC_ID_CLIENT, NULL, NULL,
368 buffer->data, buffer->len, FALSE);
369 silc_buffer_free(buffer);
374 silc_client_connect_to_client_internal(SilcClientInternalConnectContext *ctx)
378 /* Create connection to server asynchronously */
379 sock = silc_net_create_connection_async(NULL, ctx->port, ctx->host);
383 /* Register task that will receive the async connect and will
385 ctx->task = silc_schedule_task_add(ctx->client->schedule, sock,
386 silc_client_perform_key_agreement_start,
389 SILC_TASK_PRI_NORMAL);
390 silc_schedule_set_listen_fd(ctx->client->schedule, sock, SILC_TASK_WRITE);
397 /* Routine used by silc_client_perform_key_agreement to create connection
398 to the remote client on specified port. */
401 silc_client_connect_to_client(SilcClient client,
402 SilcClientConnection conn, int port,
403 char *host, void *context)
405 SilcClientInternalConnectContext *ctx;
407 /* Allocate internal context for connection process. This is
408 needed as we are doing async connecting. */
409 ctx = silc_calloc(1, sizeof(*ctx));
410 ctx->client = client;
412 ctx->host = strdup(host);
415 ctx->context = context;
417 /* Do the actual connecting process */
418 return silc_client_connect_to_client_internal(ctx);
421 /* Callback that is called after connection has been created. This actually
422 starts the key agreement protocol. This is initiator function. */
424 SILC_TASK_CALLBACK(silc_client_perform_key_agreement_start)
426 SilcClientInternalConnectContext *ctx =
427 (SilcClientInternalConnectContext *)context;
428 SilcClient client = ctx->client;
429 SilcClientConnection conn = ctx->conn;
430 SilcClientKeyAgreement ke = (SilcClientKeyAgreement)ctx->context;
431 int opt, opt_len = sizeof(opt);
433 SILC_LOG_DEBUG(("Start"));
435 /* Check the socket status as it might be in error */
436 silc_net_get_socket_opt(fd, SOL_SOCKET, SO_ERROR, &opt, &opt_len);
438 if (ctx->tries < 2) {
439 /* Connection failed but lets try again */
440 client->ops->say(client, conn, SILC_CLIENT_MESSAGE_ERROR,
441 "Could not connect to client %s: %s",
442 ctx->host, strerror(opt));
443 client->ops->say(client, conn, SILC_CLIENT_MESSAGE_AUDIT,
444 "Connecting to port %d of client %s resumed",
445 ctx->port, ctx->host);
447 /* Unregister old connection try */
448 silc_schedule_unset_listen_fd(client->schedule, fd);
449 silc_net_close_connection(fd);
450 silc_schedule_task_del(client->schedule, ctx->task);
453 silc_client_connect_to_client_internal(ctx);
456 /* Connection failed and we won't try anymore */
457 client->ops->say(client, conn, SILC_CLIENT_MESSAGE_ERROR,
458 "Could not connect to client %s: %s",
459 ctx->host, strerror(opt));
460 silc_schedule_unset_listen_fd(client->schedule, fd);
461 silc_net_close_connection(fd);
462 silc_schedule_task_del(client->schedule, ctx->task);
463 silc_free(ctx->host);
466 /* Call the completion callback */
467 ke->completion(ke->client, ke->conn, ke->client_entry,
468 SILC_KEY_AGREEMENT_FAILURE, NULL, ke->context);
474 silc_schedule_unset_listen_fd(client->schedule, fd);
475 silc_schedule_task_del(client->schedule, ctx->task);
479 /* Now actually perform the key agreement protocol */
480 silc_client_perform_key_agreement_fd(ke->client, ke->conn,
481 ke->client_entry, ke->fd, ctx->host,
482 ke->completion, ke->context);
484 silc_free(ctx->host);
488 /* Performs the actual key agreement protocol. Application may use this
489 to initiate the key agreement protocol. This can be called for example
490 after the application has received the `key_agreement' client operation,
491 and did not return TRUE from it.
493 The `hostname' is the remote hostname (or IP address) and the `port'
494 is the remote port. The `completion' callback with the `context' will
495 be called after the key agreement protocol.
497 NOTE: If the application returns TRUE in the `key_agreement' client
498 operation the library will automatically start the key agreement. In this
499 case the application must not call this function. However, application
500 may choose to just ignore the `key_agreement' client operation (and
501 merely just print information about it on the screen) and call this
502 function when the user whishes to do so (by, for example, giving some
503 specific command). Thus, the API provides both, automatic and manual
504 initiation of the key agreement. Calling this function is the manual
505 initiation and returning TRUE in the `key_agreement' client operation
506 is the automatic initiation. */
508 void silc_client_perform_key_agreement(SilcClient client,
509 SilcClientConnection conn,
510 SilcClientEntry client_entry,
513 SilcKeyAgreementCallback completion,
516 SilcClientKeyAgreement ke;
518 SILC_LOG_DEBUG(("Start"));
520 assert(client_entry && hostname && port);
522 ke = silc_calloc(1, sizeof(*ke));
525 ke->client_entry = client_entry;
526 ke->completion = completion;
527 ke->context = context;
529 /* Connect to the remote client */
530 ke->fd = silc_client_connect_to_client(client, conn, port, hostname, ke);
532 completion(client, conn, client_entry, SILC_KEY_AGREEMENT_FAILURE,
539 /* Same as above but application has created already the connection to
540 the remote host. The `sock' is the socket to the remote connection.
541 Application can use this function if it does not want the client library
542 to create the connection. */
544 void silc_client_perform_key_agreement_fd(SilcClient client,
545 SilcClientConnection conn,
546 SilcClientEntry client_entry,
549 SilcKeyAgreementCallback completion,
552 SilcClientKeyAgreement ke;
553 SilcClientKEInternalContext *proto_ctx;
554 SilcProtocol protocol;
556 SILC_LOG_DEBUG(("Start"));
558 assert(client_entry);
560 ke = silc_calloc(1, sizeof(*ke));
563 ke->client_entry = client_entry;
565 ke->completion = completion;
566 ke->context = context;
568 /* Allocate new socket connection object */
569 silc_socket_alloc(sock, SILC_SOCKET_TYPE_UNKNOWN, (void *)conn, &ke->sock);
570 silc_client_add_socket(client, ke->sock);
571 ke->sock->hostname = strdup(hostname);
572 ke->sock->port = silc_net_get_remote_port(sock);
574 /* Allocate internal context for key exchange protocol. This is
575 sent as context for the protocol. */
576 proto_ctx = silc_calloc(1, sizeof(*proto_ctx));
577 proto_ctx->client = client;
578 proto_ctx->sock = silc_socket_dup(ke->sock);
579 proto_ctx->rng = client->rng;
580 proto_ctx->responder = FALSE;
581 proto_ctx->context = ke;
582 proto_ctx->send_packet = silc_client_key_agreement_send_packet;
583 proto_ctx->verify = silc_client_protocol_ke_verify_key;
584 ke->proto_ctx = proto_ctx;
586 /* Perform key exchange protocol. */
587 silc_protocol_alloc(SILC_PROTOCOL_CLIENT_KEY_EXCHANGE,
588 &protocol, (void *)proto_ctx,
589 silc_client_key_agreement_final);
590 ke->sock->protocol = protocol;
592 /* Register the connection for network input and output. This sets
593 that scheduler will listen for incoming packets for this connection
594 and sets that outgoing packets may be sent to this connection as well.
595 However, this doesn't set the scheduler for outgoing traffic, it will
596 be set separately by calling SILC_CLIENT_SET_CONNECTION_FOR_OUTPUT,
597 later when outgoing data is available. */
598 context = (void *)client;
599 SILC_CLIENT_REGISTER_CONNECTION_FOR_IO(sock);
601 /* Execute the protocol */
602 silc_protocol_execute(protocol, client->schedule, 0, 0);
605 /* This function can be called to unbind the hostname and the port for
606 the key agreement protocol. However, this function has effect only
607 before the key agreement protocol has been performed. After it has
608 been performed the library will automatically unbind the port. The
609 `client_entry' is the client to which we sent the key agreement
612 void silc_client_abort_key_agreement(SilcClient client,
613 SilcClientConnection conn,
614 SilcClientEntry client_entry)
616 assert(client_entry);
618 if (client_entry->ke) {
619 SilcClientKeyAgreement ke;
621 if (client_entry->ke->sock) {
622 silc_client_del_socket(client_entry->ke->client, client_entry->ke->sock);
623 silc_socket_free(client_entry->ke->sock);
625 silc_schedule_task_del_by_fd(client->schedule, client_entry->ke->fd);
626 if (client_entry->ke->timeout)
627 silc_schedule_task_del(client->schedule,
628 client_entry->ke->timeout);
629 ke = client_entry->ke;
630 client_entry->ke = NULL;
631 ke->completion(client, conn, client_entry,
632 SILC_KEY_AGREEMENT_ABORTED, NULL, ke->context);
637 /* Callback function that is called after we've resolved the client
638 information who sent us the key agreement packet from the server.
639 We actually call the key_agreement client operation now. */
642 silc_client_key_agreement_resolve_cb(SilcClient client,
643 SilcClientConnection conn,
644 SilcClientEntry *clients,
645 uint32 clients_count,
648 SilcPacketContext *packet = (SilcPacketContext *)context;
649 SilcKeyAgreementPayload payload;
651 SilcKeyAgreementCallback completion;
652 void *completion_context;
657 /* Parse the key agreement payload */
658 payload = silc_key_agreement_payload_parse(packet->buffer);
662 /* Call the key_agreement client operation */
663 ret = client->ops->key_agreement(client, conn, clients[0],
664 silc_key_agreement_get_hostname(payload),
665 silc_key_agreement_get_port(payload),
666 &completion, &completion_context);
668 /* If the user returned TRUE then we'll start the key agreement right
669 here and right now. */
671 silc_client_perform_key_agreement(client, conn, clients[0],
672 silc_key_agreement_get_hostname(payload),
673 silc_key_agreement_get_port(payload),
674 completion, completion_context);
676 silc_key_agreement_payload_free(payload);
679 silc_packet_context_free(packet);
682 /* Received Key Agreement packet from remote client. Process the packet
683 and resolve the client information from the server before actually
684 letting the application know that we've received this packet. Then
685 call the key_agreement client operation and let the user decide
686 whether we perform the key agreement protocol now or not. */
688 void silc_client_key_agreement(SilcClient client,
689 SilcSocketConnection sock,
690 SilcPacketContext *packet)
692 SilcClientID *remote_id;
694 if (packet->src_id_type != SILC_ID_CLIENT)
697 remote_id = silc_id_str2id(packet->src_id, packet->src_id_len,
702 silc_client_get_client_by_id_resolve(client, sock->user_data, remote_id,
703 silc_client_key_agreement_resolve_cb,
704 silc_packet_context_dup(packet));
705 silc_free(remote_id);