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/* Copyright 2004 Roger Dingledine */
/* See LICENSE for licensing information */
/* $Id$ */
#include "or.h"
/* Respond to an ESTABLISH_INTRO cell by setting the circuit's purpose and
* rendevous service.
*/
int
rend_mid_establish_intro(circuit_t *circ, char *request, int request_len)
{
crypto_pk_env_t *pk = NULL;
char buf[20+9];
char expected_digest[20];
char pk_digest[20];
int asn1len;
circuit_t *c;
if (circ->purpose != CIRCUIT_PURPOSE_INTERMEDIATE) {
log_fn(LOG_WARN, "Rejecting ESTABLISH_INTRO on non-intermediate circuit");
goto err;
}
if (request_len < 22)
goto truncated;
/* First 2 bytes: length of asn1-encoded key. */
asn1len = get_uint16(request);
/* Next asn1len bytes: asn1-encoded key. */
if (request_len < 22+asn1len)
goto truncated;
pk = crypto_pk_asn1_decode(request+2, asn1len);
if (!pk) {
log_fn(LOG_WARN, "Couldn't decode public key");
goto err;
}
/* Next 20 bytes: Hash of handshake_digest | "INTRODUCE" */
memcpy(buf, circ->handshake_digest, 20);
memcpy(buf+20, "INTRODUCE", 9);
if (crypto_SHA_digest(buf, 29, expected_digest)<0) {
log_fn(LOG_WARN, "Error computing digest");
goto err;
}
if (memcmp(expected_digest, buf+2+asn1len, 20)) {
log_fn(LOG_WARN, "Hash of session info was not as expected");
goto err;
}
/* Rest of body: signature of previous data */
if (crypto_pk_public_checksig_digest(pk, buf, 22+asn1len,
buf+22+asn1len, request_len-(22+asn1len))<0) {
log_fn(LOG_WARN, "Incorrect signature on ESTABLISH_INTRO cell; rejecting");
goto err;
}
/* The request is valid. First, compute the hash of Bob's PK.*/
if (crypto_pk_get_digest(pk, pk_digest)<0) {
log_fn(LOG_WARN, "Couldn't hash public key.");
goto err;
}
/* Close any other intro circuits with the same pk. */
c = NULL;
while ((c = circuit_get_next_by_service_and_purpose(
c,pk_digest,CIRCUIT_PURPOSE_INTRO_POINT))) {
circuit_mark_for_close(c);
}
/* Now, set up this circuit. */
circ->purpose = CIRCUIT_PURPOSE_INTRO_POINT;
memcpy(circ->rend_service, pk_digest, 20);
return 0;
truncated:
log_fn(LOG_WARN, "Rejecting truncated ESTABLISH_INTRO cell");
err:
if (pk) crypto_free_pk_env(pk);
circuit_mark_for_close(circ);
return -1;
}
/* Process an INTRODUCE1 cell by finding the corresponding introduction
* circuit, and relaying the body of the INTRODUCE1 cell inside an
* INTRODUCE2 cell.
*/
int
rend_mid_introduce(circuit_t *circ, char *request, int request_len)
{
circuit_t *intro_circ;
if (request_len < 276) {
log_fn(LOG_WARN, "Impossibly short INTRODUCE2 cell; dropping.");
goto err;
}
/* The first 20 bytes are all we look at: they have a hash of Bob's PK. */
intro_circ = circuit_get_next_by_service_and_purpose(
NULL, request, CIRCUIT_PURPOSE_INTRO_POINT);
if (!intro_circ) {
log_fn(LOG_WARN,
"No introduction circuit matching INTRODUCE2 cell; dropping");
goto err;
}
/* Great. Now we just relay the cell down the circuit. */
if (connection_edge_send_command(NULL, intro_circ,
RELAY_COMMAND_INTRODUCE2,
request, request_len, NULL)) {
log_fn(LOG_WARN, "Unable to send INTRODUCE2 cell to OP.");
goto err;
}
return 0;
err:
circuit_mark_for_close(circ); /* Is this right? */
return -1;
}
/* Process an ESTABLISH_RENDEZVOUS cell by settingthe circuit's purpose and
* rendezvous cookie.
*/
int
rend_mid_establish_rendezvous(circuit_t *circ, char *request, int request_len)
{
if (circ->purpose != CIRCUIT_PURPOSE_INTERMEDIATE) {
log_fn(LOG_WARN, "Tried to establish rendezvous on non-intermediate circuit");
goto err;
}
if (request_len != REND_COOKIE_LEN) {
log_fn(LOG_WARN, "Invalid length on ESTABLISH_RENDEZVOUS");
goto err;
}
if (circuit_get_rendezvous(request)) {
log_fn(LOG_WARN, "Duplicate rendezvous cookie in ESTABLISH_RENDEZVOUS");
goto err;
}
circ->purpose = CIRCUIT_PURPOSE_REND_POINT_WAITING;
memcpy(circ->rend_cookie, request, REND_COOKIE_LEN);
return 0;
err:
circuit_mark_for_close(circ);
return -1;
}
/* Process a RENDEZVOUS1 cell by looking up the correct rendezvous circuit by its
* relaying the cell's body in a RENDEZVOUS2 cell, and connecting the two circuits.
*/
int
rend_mid_rendezvous(circuit_t *circ, char *request, int request_len)
{
circuit_t *rend_circ;
if (circ->purpose != CIRCUIT_PURPOSE_INTERMEDIATE) {
log_fn(LOG_WARN, "Tried to complete rendezvous on non-intermediate circuit");
goto err;
}
if (request_len < 20+128+20) {
log_fn(LOG_WARN, "Rejecting impossibly short RENDEZVOUS1 cell");
goto err;
}
rend_circ = circuit_get_rendezvous(request);
if (!rend_circ) {
log_fn(LOG_WARN, "Rejecting RENDEZVOUS1 cell with unrecognized rendezvous cookie");
goto err;
}
/* Send the RENDEZVOUS2 cell to Alice. */
if (connection_edge_send_command(NULL, rend_circ,
RELAY_COMMAND_RENDEZVOUS2,
request+20, request_len-20, NULL)) {
log_fn(LOG_WARN, "Unable to send RENDEZVOUS2 cell to OP.");
goto err;
}
/* Join the circuits. */
circ->purpose = CIRCUIT_PURPOSE_REND_ESTABLISHED;
rend_circ->purpose = CIRCUIT_PURPOSE_REND_ESTABLISHED;
memset(circ->rend_cookie, 0, 20);
rend_circ->rend_splice = circ;
circ->rend_splice = rend_circ;
return 0;
err:
circuit_mark_for_close(circ);
return -1;
}
/*
Local Variables:
mode:c
indent-tabs-mode:nil
c-basic-offset:2
End:
*/
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