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https://gitlab.torproject.org/tpo/core/tor.git
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58366ffd24
we screwed up the formatting in wild and unpredictable ways. fix it before it becomes convention to format logs in wild and unpredictable ways. still need to do src/common/ someday. svn:r5551
295 lines
9.2 KiB
C
295 lines
9.2 KiB
C
/* Copyright 2004-2005 Roger Dingledine, Nick Mathewson. */
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/* See LICENSE for licensing information */
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/* $Id$ */
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const char rendmid_c_id[] = "$Id$";
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/**
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* \file rendmid.c
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* \brief Implement introductions points and rendezvous points.
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**/
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#include "or.h"
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/** Respond to an ESTABLISH_INTRO cell by checking the signed data and
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* setting the circuit's purpose and service pk digest.
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*/
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int
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rend_mid_establish_intro(circuit_t *circ, const char *request, size_t request_len)
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{
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crypto_pk_env_t *pk = NULL;
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char buf[DIGEST_LEN+9];
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char expected_digest[DIGEST_LEN];
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char pk_digest[DIGEST_LEN];
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size_t asn1len;
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circuit_t *c;
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char serviceid[REND_SERVICE_ID_LEN+1];
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info(LD_REND,
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"Received an ESTABLISH_INTRO request on circuit %d", circ->p_circ_id);
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if (circ->purpose != CIRCUIT_PURPOSE_OR || circ->n_conn) {
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warn(LD_PROTOCOL, "Rejecting ESTABLISH_INTRO on non-OR or non-edge circuit.");
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goto err;
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}
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if (request_len < 2+DIGEST_LEN)
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goto truncated;
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/* First 2 bytes: length of asn1-encoded key. */
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asn1len = ntohs(get_uint16(request));
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/* Next asn1len bytes: asn1-encoded key. */
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if (request_len < 2+DIGEST_LEN+asn1len)
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goto truncated;
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pk = crypto_pk_asn1_decode(request+2, asn1len);
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if (!pk) {
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warn(LD_PROTOCOL, "Couldn't decode public key.");
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goto err;
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}
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/* Next 20 bytes: Hash of handshake_digest | "INTRODUCE" */
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memcpy(buf, circ->handshake_digest, DIGEST_LEN);
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memcpy(buf+DIGEST_LEN, "INTRODUCE", 9);
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if (crypto_digest(expected_digest, buf, DIGEST_LEN+9) < 0) {
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warn(LD_BUG, "Internal error computing digest.");
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goto err;
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}
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if (memcmp(expected_digest, request+2+asn1len, DIGEST_LEN)) {
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warn(LD_PROTOCOL, "Hash of session info was not as expected.");
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goto err;
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}
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/* Rest of body: signature of previous data */
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if (crypto_pk_public_checksig_digest(pk, request, 2+asn1len+DIGEST_LEN,
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request+2+DIGEST_LEN+asn1len,
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request_len-(2+DIGEST_LEN+asn1len))<0) {
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warn(LD_PROTOCOL, "Incorrect signature on ESTABLISH_INTRO cell; rejecting.");
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goto err;
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}
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/* The request is valid. First, compute the hash of Bob's PK.*/
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if (crypto_pk_get_digest(pk, pk_digest)<0) {
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warn(LD_BUG, "Internal error: couldn't hash public key.");
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goto err;
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}
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crypto_free_pk_env(pk); /* don't need it anymore */
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pk = NULL; /* so we don't free it again if err */
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base32_encode(serviceid, REND_SERVICE_ID_LEN+1, pk_digest,10);
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/* Close any other intro circuits with the same pk. */
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c = NULL;
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while ((c = circuit_get_next_by_pk_and_purpose(
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c,pk_digest,CIRCUIT_PURPOSE_INTRO_POINT))) {
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info(LD_REND, "Replacing old circuit %d for service %s",
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c->p_circ_id, safe_str(serviceid));
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circuit_mark_for_close(c);
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}
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/* Acknowledge the request. */
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if (connection_edge_send_command(NULL,circ,
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RELAY_COMMAND_INTRO_ESTABLISHED,
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"", 0, NULL)<0) {
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info(LD_GENERAL, "Couldn't send INTRO_ESTABLISHED cell.");
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goto err;
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}
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/* Now, set up this circuit. */
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circ->purpose = CIRCUIT_PURPOSE_INTRO_POINT;
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memcpy(circ->rend_pk_digest, pk_digest, DIGEST_LEN);
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info(LD_REND,
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"Established introduction point on circuit %d for service %s",
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circ->p_circ_id, safe_str(serviceid));
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return 0;
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truncated:
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warn(LD_PROTOCOL, "Rejecting truncated ESTABLISH_INTRO cell.");
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err:
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if (pk) crypto_free_pk_env(pk);
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circuit_mark_for_close(circ);
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return -1;
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}
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/** Process an INTRODUCE1 cell by finding the corresponding introduction
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* circuit, and relaying the body of the INTRODUCE1 cell inside an
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* INTRODUCE2 cell.
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*/
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int
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rend_mid_introduce(circuit_t *circ, const char *request, size_t request_len)
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{
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circuit_t *intro_circ;
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char serviceid[REND_SERVICE_ID_LEN+1];
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char nak_body[1];
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if (circ->purpose != CIRCUIT_PURPOSE_OR || circ->n_conn) {
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warn(LD_PROTOCOL, "Rejecting INTRODUCE1 on non-OR or non-edge circuit %d.",
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circ->p_circ_id);
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goto err;
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}
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/* change to MAX_HEX_NICKNAME_LEN once 0.0.9.x is obsolete */
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if (request_len < (DIGEST_LEN+(MAX_NICKNAME_LEN+1)+REND_COOKIE_LEN+
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DH_KEY_LEN+CIPHER_KEY_LEN+PKCS1_OAEP_PADDING_OVERHEAD)) {
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warn(LD_PROTOCOL,
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"Impossibly short INTRODUCE1 cell on circuit %d; responding with nack.",
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circ->p_circ_id);
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goto err;
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}
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base32_encode(serviceid, REND_SERVICE_ID_LEN+1, request,10);
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/* The first 20 bytes are all we look at: they have a hash of Bob's PK. */
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intro_circ = circuit_get_next_by_pk_and_purpose(
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NULL, request, CIRCUIT_PURPOSE_INTRO_POINT);
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if (!intro_circ) {
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info(LD_REND,
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"No intro circ found for INTRODUCE1 cell (%s) from circuit %d; responding with nack.",
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safe_str(serviceid), circ->p_circ_id);
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goto err;
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}
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info(LD_REND,
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"Sending introduction request for service %s from circ %d to circ %d",
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safe_str(serviceid), circ->p_circ_id, intro_circ->p_circ_id);
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/* Great. Now we just relay the cell down the circuit. */
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if (connection_edge_send_command(NULL, intro_circ,
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RELAY_COMMAND_INTRODUCE2,
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request, request_len, NULL)) {
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warn(LD_GENERAL,
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"Unable to send INTRODUCE2 cell to Tor client.");
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goto err;
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}
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/* And sent an ack down Alice's circuit. Empty body means succeeded. */
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if (connection_edge_send_command(NULL,circ,RELAY_COMMAND_INTRODUCE_ACK,
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NULL,0,NULL)) {
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warn(LD_GENERAL, "Unable to send INTRODUCE_ACK cell to Tor client.");
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circuit_mark_for_close(circ);
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return -1;
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}
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return 0;
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err:
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/* Send the client an NACK */
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nak_body[0] = 1;
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if (connection_edge_send_command(NULL,circ,RELAY_COMMAND_INTRODUCE_ACK,
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nak_body, 1, NULL)) {
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warn(LD_GENERAL, "Unable to send NAK to Tor client.");
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circuit_mark_for_close(circ); /* Is this right? */
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}
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return -1;
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}
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/** Process an ESTABLISH_RENDEZVOUS cell by setting the circuit's purpose and
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* rendezvous cookie.
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*/
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int
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rend_mid_establish_rendezvous(circuit_t *circ, const char *request, size_t request_len)
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{
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char hexid[9];
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if (circ->purpose != CIRCUIT_PURPOSE_OR || circ->n_conn) {
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warn(LD_PROTOCOL, "Tried to establish rendezvous on non-OR or non-edge circuit.");
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goto err;
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}
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if (request_len != REND_COOKIE_LEN) {
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warn(LD_PROTOCOL, "Invalid length on ESTABLISH_RENDEZVOUS.");
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goto err;
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}
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if (circuit_get_rendezvous(request)) {
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warn(LD_PROTOCOL, "Duplicate rendezvous cookie in ESTABLISH_RENDEZVOUS.");
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goto err;
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}
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/* Acknowledge the request. */
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if (connection_edge_send_command(NULL,circ,
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RELAY_COMMAND_RENDEZVOUS_ESTABLISHED,
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"", 0, NULL)<0) {
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warn(LD_PROTOCOL, "Couldn't send RENDEZVOUS_ESTABLISHED cell.");
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goto err;
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}
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circ->purpose = CIRCUIT_PURPOSE_REND_POINT_WAITING;
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memcpy(circ->rend_cookie, request, REND_COOKIE_LEN);
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base16_encode(hexid,9,request,4);
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info(LD_REND, "Established rendezvous point on circuit %d for cookie %s",
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circ->p_circ_id, hexid);
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return 0;
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err:
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circuit_mark_for_close(circ);
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return -1;
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}
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/** Process a RENDEZVOUS1 cell by looking up the correct rendezvous
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* circuit by its relaying the cell's body in a RENDEZVOUS2 cell, and
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* connecting the two circuits.
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*/
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int
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rend_mid_rendezvous(circuit_t *circ, const char *request, size_t request_len)
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{
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circuit_t *rend_circ;
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char hexid[9];
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base16_encode(hexid,9,request,request_len<4?request_len:4);
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if (request_len>=4) {
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info(LD_REND, "Got request for rendezvous from circuit %d to cookie %s.",
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circ->p_circ_id, hexid);
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}
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if (circ->purpose != CIRCUIT_PURPOSE_OR || circ->n_conn) {
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info(LD_REND,
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"Tried to complete rendezvous on non-OR or non-edge circuit %d.",
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circ->p_circ_id);
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goto err;
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}
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if (request_len != REND_COOKIE_LEN+DH_KEY_LEN+DIGEST_LEN) {
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warn(LD_PROTOCOL,
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"Rejecting RENDEZVOUS1 cell with bad length (%d) on circuit %d.",
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(int)request_len, circ->p_circ_id);
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goto err;
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}
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rend_circ = circuit_get_rendezvous(request);
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if (!rend_circ) {
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warn(LD_PROTOCOL,
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"Rejecting RENDEZVOUS1 cell with unrecognized rendezvous cookie %s.",
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hexid);
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goto err;
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}
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/* Send the RENDEZVOUS2 cell to Alice. */
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if (connection_edge_send_command(NULL, rend_circ,
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RELAY_COMMAND_RENDEZVOUS2,
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request+REND_COOKIE_LEN,
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request_len-REND_COOKIE_LEN, NULL)) {
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warn(LD_GENERAL,
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"Unable to send RENDEZVOUS2 cell to OP on circuit %d.",
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rend_circ->p_circ_id);
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goto err;
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}
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/* Join the circuits. */
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info(LD_REND,
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"Completing rendezvous: circuit %d joins circuit %d (cookie %s)",
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circ->p_circ_id, rend_circ->p_circ_id, hexid);
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circ->purpose = CIRCUIT_PURPOSE_REND_ESTABLISHED;
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rend_circ->purpose = CIRCUIT_PURPOSE_REND_ESTABLISHED;
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memset(circ->rend_cookie, 0, REND_COOKIE_LEN);
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rend_circ->rend_splice = circ;
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circ->rend_splice = rend_circ;
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return 0;
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err:
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circuit_mark_for_close(circ);
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return -1;
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}
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