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- /* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /* $Id$ */
- const char rendclient_c_id[] =
- "$Id$";
- /**
- * \file rendclient.c
- * \brief Client code to access location-hidden services.
- **/
- #include "or.h"
- /** Called when we've established a circuit to an introduction point:
- * send the introduction request. */
- void
- rend_client_introcirc_has_opened(origin_circuit_t *circ)
- {
- tor_assert(circ->_base.purpose == CIRCUIT_PURPOSE_C_INTRODUCING);
- tor_assert(circ->cpath);
- log_info(LD_REND,"introcirc is open");
- connection_ap_attach_pending();
- }
- /** Send the establish-rendezvous cell along a rendezvous circuit. if
- * it fails, mark the circ for close and return -1. else return 0.
- */
- static int
- rend_client_send_establish_rendezvous(origin_circuit_t *circ)
- {
- tor_assert(circ->_base.purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND);
- log_info(LD_REND, "Sending an ESTABLISH_RENDEZVOUS cell");
- if (crypto_rand(circ->rend_cookie, REND_COOKIE_LEN) < 0) {
- log_warn(LD_BUG, "Internal error: Couldn't produce random cookie.");
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
- return -1;
- }
- if (relay_send_command_from_edge(0, TO_CIRCUIT(circ),
- RELAY_COMMAND_ESTABLISH_RENDEZVOUS,
- circ->rend_cookie, REND_COOKIE_LEN,
- circ->cpath->prev)<0) {
- /* circ is already marked for close */
- log_warn(LD_GENERAL, "Couldn't send ESTABLISH_RENDEZVOUS cell");
- return -1;
- }
- return 0;
- }
- /** Called when we're trying to connect an ap conn; sends an INTRODUCE1 cell
- * down introcirc if possible.
- */
- int
- rend_client_send_introduction(origin_circuit_t *introcirc,
- origin_circuit_t *rendcirc)
- {
- size_t payload_len;
- int r;
- char payload[RELAY_PAYLOAD_SIZE];
- char tmp[RELAY_PAYLOAD_SIZE];
- rend_cache_entry_t *entry;
- crypt_path_t *cpath;
- off_t dh_offset;
- crypto_pk_env_t *intro_key; /* either Bob's public key or an intro key. */
- tor_assert(introcirc->_base.purpose == CIRCUIT_PURPOSE_C_INTRODUCING);
- tor_assert(rendcirc->_base.purpose == CIRCUIT_PURPOSE_C_REND_READY);
- tor_assert(!rend_cmp_service_ids(introcirc->rend_query,
- rendcirc->rend_query));
- if (rend_cache_lookup_entry(introcirc->rend_query, -1, &entry) < 1) {
- log_warn(LD_REND,
- "query %s didn't have valid rend desc in cache. Failing.",
- escaped_safe_str(introcirc->rend_query));
- goto err;
- }
- /* first 20 bytes of payload are the hash of bob's pk */
- if (entry->parsed->version == 0) { /* unversioned descriptor */
- intro_key = entry->parsed->pk;
- } else { /* versioned descriptor */
- intro_key = NULL;
- SMARTLIST_FOREACH(entry->parsed->intro_nodes, rend_intro_point_t *,
- intro, {
- if (!memcmp(introcirc->build_state->chosen_exit->identity_digest,
- intro->extend_info->identity_digest, DIGEST_LEN)) {
- intro_key = intro->intro_key;
- break;
- }
- });
- if (!intro_key) {
- log_warn(LD_BUG, "Internal error: could not find intro key.");
- goto err;
- }
- }
- if (crypto_pk_get_digest(intro_key, payload)<0) {
- log_warn(LD_BUG, "Internal error: couldn't hash public key.");
- goto err;
- }
- /* Initialize the pending_final_cpath and start the DH handshake. */
- cpath = rendcirc->build_state->pending_final_cpath;
- if (!cpath) {
- cpath = rendcirc->build_state->pending_final_cpath =
- tor_malloc_zero(sizeof(crypt_path_t));
- cpath->magic = CRYPT_PATH_MAGIC;
- if (!(cpath->dh_handshake_state = crypto_dh_new())) {
- log_warn(LD_BUG, "Internal error: couldn't allocate DH.");
- goto err;
- }
- if (crypto_dh_generate_public(cpath->dh_handshake_state)<0) {
- log_warn(LD_BUG, "Internal error: couldn't generate g^x.");
- goto err;
- }
- }
- /* write the remaining items into tmp */
- if (entry->parsed->protocols & (1<<2)) {
- /* version 2 format */
- extend_info_t *extend_info = rendcirc->build_state->chosen_exit;
- int klen;
- tmp[0] = 2; /* version 2 of the cell format */
- /* nul pads */
- set_uint32(tmp+1, htonl(extend_info->addr));
- set_uint16(tmp+5, htons(extend_info->port));
- memcpy(tmp+7, extend_info->identity_digest, DIGEST_LEN);
- klen = crypto_pk_asn1_encode(extend_info->onion_key, tmp+7+DIGEST_LEN+2,
- sizeof(tmp)-(7+DIGEST_LEN+2));
- set_uint16(tmp+7+DIGEST_LEN, htons(klen));
- memcpy(tmp+7+DIGEST_LEN+2+klen, rendcirc->rend_cookie,
- REND_COOKIE_LEN);
- dh_offset = 7+DIGEST_LEN+2+klen+REND_COOKIE_LEN;
- } else {
- /* Version 0. */
- strncpy(tmp, rendcirc->build_state->chosen_exit->nickname,
- (MAX_NICKNAME_LEN+1)); /* nul pads */
- memcpy(tmp+MAX_NICKNAME_LEN+1, rendcirc->rend_cookie,
- REND_COOKIE_LEN);
- dh_offset = MAX_NICKNAME_LEN+1+REND_COOKIE_LEN;
- }
- if (crypto_dh_get_public(cpath->dh_handshake_state, tmp+dh_offset,
- DH_KEY_LEN)<0) {
- log_warn(LD_BUG, "Internal error: couldn't extract g^x.");
- goto err;
- }
- note_crypto_pk_op(REND_CLIENT);
- /*XXX maybe give crypto_pk_public_hybrid_encrypt a max_len arg,
- * to avoid buffer overflows? */
- r = crypto_pk_public_hybrid_encrypt(intro_key, payload+DIGEST_LEN,
- tmp,
- (int)(dh_offset+DH_KEY_LEN),
- PK_PKCS1_OAEP_PADDING, 0);
- if (r<0) {
- log_warn(LD_BUG,"Internal error: hybrid pk encrypt failed.");
- goto err;
- }
- payload_len = DIGEST_LEN + r;
- tor_assert(payload_len <= RELAY_PAYLOAD_SIZE); /* we overran something */
- log_info(LD_REND, "Sending an INTRODUCE1 cell");
- if (relay_send_command_from_edge(0, TO_CIRCUIT(introcirc),
- RELAY_COMMAND_INTRODUCE1,
- payload, payload_len,
- introcirc->cpath->prev)<0) {
- /* introcirc is already marked for close. leave rendcirc alone. */
- log_warn(LD_BUG, "Couldn't send INTRODUCE1 cell");
- return -1;
- }
- /* Now, we wait for an ACK or NAK on this circuit. */
- introcirc->_base.purpose = CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT;
- return 0;
- err:
- circuit_mark_for_close(TO_CIRCUIT(introcirc), END_CIRC_REASON_INTERNAL);
- circuit_mark_for_close(TO_CIRCUIT(rendcirc), END_CIRC_REASON_INTERNAL);
- return -1;
- }
- /** Called when a rendezvous circuit is open; sends a establish
- * rendezvous circuit as appropriate. */
- void
- rend_client_rendcirc_has_opened(origin_circuit_t *circ)
- {
- tor_assert(circ->_base.purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND);
- log_info(LD_REND,"rendcirc is open");
- /* generate a rendezvous cookie, store it in circ */
- if (rend_client_send_establish_rendezvous(circ) < 0) {
- return;
- }
- }
- /** Called when get an ACK or a NAK for a REND_INTRODUCE1 cell.
- */
- int
- rend_client_introduction_acked(origin_circuit_t *circ,
- const char *request, size_t request_len)
- {
- origin_circuit_t *rendcirc;
- (void) request; // XXXX Use this.
- if (circ->_base.purpose != CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT) {
- log_warn(LD_PROTOCOL,
- "Received REND_INTRODUCE_ACK on unexpected circuit %d.",
- circ->_base.n_circ_id);
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
- return -1;
- }
- tor_assert(circ->build_state->chosen_exit);
- if (request_len == 0) {
- /* It's an ACK; the introduction point relayed our introduction request. */
- /* Locate the rend circ which is waiting to hear about this ack,
- * and tell it.
- */
- log_info(LD_REND,"Received ack. Telling rend circ...");
- rendcirc = circuit_get_by_rend_query_and_purpose(
- circ->rend_query, CIRCUIT_PURPOSE_C_REND_READY);
- if (rendcirc) { /* remember the ack */
- rendcirc->_base.purpose = CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED;
- } else {
- log_info(LD_REND,"...Found no rend circ. Dropping on the floor.");
- }
- /* close the circuit: we won't need it anymore. */
- circ->_base.purpose = CIRCUIT_PURPOSE_C_INTRODUCE_ACKED;
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_FINISHED);
- } else {
- /* It's a NAK; the introduction point didn't relay our request. */
- circ->_base.purpose = CIRCUIT_PURPOSE_C_INTRODUCING;
- /* Remove this intro point from the set of viable introduction
- * points. If any remain, extend to a new one and try again.
- * If none remain, refetch the service descriptor.
- */
- if (rend_client_remove_intro_point(circ->build_state->chosen_exit,
- circ->rend_query) > 0) {
- /* There are introduction points left. Re-extend the circuit to
- * another intro point and try again. */
- extend_info_t *extend_info;
- int result;
- extend_info = rend_client_get_random_intro(circ->rend_query);
- if (!extend_info) {
- log_warn(LD_REND, "No introduction points left for %s. Closing.",
- escaped_safe_str(circ->rend_query));
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
- return -1;
- }
- log_info(LD_REND,
- "Got nack for %s from %s. Re-extending circ %d, "
- "this time to %s.",
- escaped_safe_str(circ->rend_query),
- circ->build_state->chosen_exit->nickname, circ->_base.n_circ_id,
- extend_info->nickname);
- result = circuit_extend_to_new_exit(circ, extend_info);
- extend_info_free(extend_info);
- return result;
- }
- }
- return 0;
- }
- /** If we are not currently fetching a rendezvous service descriptor
- * for the service ID <b>query</b>, start a directory connection to fetch a
- * new one.
- */
- void
- rend_client_refetch_renddesc(const char *query)
- {
- if (!get_options()->FetchHidServDescriptors)
- return;
- log_info(LD_REND, "Fetching rendezvous descriptor for service %s", query);
- if (connection_get_by_type_state_rendquery(CONN_TYPE_DIR, 0, query)) {
- log_info(LD_REND,"Would fetch a new renddesc here (for %s), but one is "
- "already in progress.", escaped_safe_str(query));
- } else {
- /* not one already; initiate a dir rend desc lookup */
- directory_get_from_dirserver(DIR_PURPOSE_FETCH_RENDDESC,
- ROUTER_PURPOSE_GENERAL, query, 1);
- }
- }
- /** Start a connection to a hidden service directory to fetch a v2
- * rendezvous service descriptor for the base32-encoded service ID
- * <b>query</b>.
- */
- void
- rend_client_refetch_v2_renddesc(const char *query)
- {
- char descriptor_id[DIGEST_LEN];
- int replica;
- tor_assert(query);
- tor_assert(strlen(query) == REND_SERVICE_ID_LEN_BASE32);
- /* Are we configured to fetch descriptors? */
- if (!get_options()->FetchHidServDescriptors) {
- log_warn(LD_REND, "We received an onion address for a v2 rendezvous "
- "service descriptor, but are not fetching service descriptors.");
- return;
- }
- log_debug(LD_REND, "Fetching v2 rendezvous descriptor for service %s",
- query);
- replica = crypto_rand_int(REND_NUMBER_OF_NON_CONSECUTIVE_REPLICAS);
- if (rend_compute_v2_desc_id(descriptor_id, query, NULL, time(NULL),
- replica) < 0) {
- log_warn(LD_REND, "Internal error: Computing v2 rendezvous "
- "descriptor ID did not succeed.");
- return;
- }
- directory_get_from_hs_dir(descriptor_id, query);
- return;
- }
- /** Remove failed_intro from ent. If ent now has no intro points, or
- * service is unrecognized, then launch a new renddesc fetch.
- *
- * Return -1 if error, 0 if no intro points remain or service
- * unrecognized, 1 if recognized and some intro points remain.
- */
- int
- rend_client_remove_intro_point(extend_info_t *failed_intro, const char *query)
- {
- int i, r;
- rend_cache_entry_t *ent;
- connection_t *conn;
- r = rend_cache_lookup_entry(query, -1, &ent);
- if (r<0) {
- log_warn(LD_BUG, "Malformed service ID %s.", escaped_safe_str(query));
- return -1;
- }
- if (r==0) {
- log_info(LD_REND, "Unknown service %s. Re-fetching descriptor.",
- escaped_safe_str(query));
- /* Fetch both, v0 and v2 rend descriptors in parallel. Use whichever
- * arrives first. */
- rend_client_refetch_v2_renddesc(query);
- rend_client_refetch_renddesc(query);
- return 0;
- }
- for (i = 0; i < smartlist_len(ent->parsed->intro_nodes); i++) {
- rend_intro_point_t *intro = smartlist_get(ent->parsed->intro_nodes, i);
- if (!memcmp(failed_intro->identity_digest,
- intro->extend_info->identity_digest, DIGEST_LEN)) {
- rend_intro_point_free(intro);
- smartlist_del(ent->parsed->intro_nodes, i);
- break;
- }
- }
- if (smartlist_len(ent->parsed->intro_nodes) == 0) {
- log_info(LD_REND,
- "No more intro points remain for %s. Re-fetching descriptor.",
- escaped_safe_str(query));
- /* Fetch both, v0 and v2 rend descriptors in parallel. Use whichever
- * arrives first. */
- rend_client_refetch_v2_renddesc(query);
- rend_client_refetch_renddesc(query);
- /* move all pending streams back to renddesc_wait */
- while ((conn = connection_get_by_type_state_rendquery(CONN_TYPE_AP,
- AP_CONN_STATE_CIRCUIT_WAIT, query))) {
- conn->state = AP_CONN_STATE_RENDDESC_WAIT;
- }
- return 0;
- }
- log_info(LD_REND,"%d options left for %s.",
- smartlist_len(ent->parsed->intro_nodes), escaped_safe_str(query));
- return 1;
- }
- /** Called when we receive a RENDEZVOUS_ESTABLISHED cell; changes the state of
- * the circuit to C_REND_READY.
- */
- int
- rend_client_rendezvous_acked(origin_circuit_t *circ, const char *request,
- size_t request_len)
- {
- (void) request;
- (void) request_len;
- /* we just got an ack for our establish-rendezvous. switch purposes. */
- if (circ->_base.purpose != CIRCUIT_PURPOSE_C_ESTABLISH_REND) {
- log_warn(LD_PROTOCOL,"Got a rendezvous ack when we weren't expecting one. "
- "Closing circ.");
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
- return -1;
- }
- log_info(LD_REND,"Got rendezvous ack. This circuit is now ready for "
- "rendezvous.");
- circ->_base.purpose = CIRCUIT_PURPOSE_C_REND_READY;
- return 0;
- }
- /** Bob sent us a rendezvous cell; join the circuits. */
- int
- rend_client_receive_rendezvous(origin_circuit_t *circ, const char *request,
- size_t request_len)
- {
- crypt_path_t *hop;
- char keys[DIGEST_LEN+CPATH_KEY_MATERIAL_LEN];
- if ((circ->_base.purpose != CIRCUIT_PURPOSE_C_REND_READY &&
- circ->_base.purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED)
- || !circ->build_state->pending_final_cpath) {
- log_warn(LD_PROTOCOL,"Got rendezvous2 cell from hidden service, but not "
- "expecting it. Closing.");
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
- return -1;
- }
- if (request_len != DH_KEY_LEN+DIGEST_LEN) {
- log_warn(LD_PROTOCOL,"Incorrect length (%d) on RENDEZVOUS2 cell.",
- (int)request_len);
- goto err;
- }
- log_info(LD_REND,"Got RENDEZVOUS2 cell from hidden service.");
- /* first DH_KEY_LEN bytes are g^y from bob. Finish the dh handshake...*/
- tor_assert(circ->build_state);
- tor_assert(circ->build_state->pending_final_cpath);
- hop = circ->build_state->pending_final_cpath;
- tor_assert(hop->dh_handshake_state);
- if (crypto_dh_compute_secret(hop->dh_handshake_state, request, DH_KEY_LEN,
- keys, DIGEST_LEN+CPATH_KEY_MATERIAL_LEN)<0) {
- log_warn(LD_GENERAL, "Couldn't complete DH handshake.");
- goto err;
- }
- /* ... and set up cpath. */
- if (circuit_init_cpath_crypto(hop, keys+DIGEST_LEN, 0)<0)
- goto err;
- /* Check whether the digest is right... */
- if (memcmp(keys, request+DH_KEY_LEN, DIGEST_LEN)) {
- log_warn(LD_PROTOCOL, "Incorrect digest of key material.");
- goto err;
- }
- crypto_dh_free(hop->dh_handshake_state);
- hop->dh_handshake_state = NULL;
- /* All is well. Extend the circuit. */
- circ->_base.purpose = CIRCUIT_PURPOSE_C_REND_JOINED;
- hop->state = CPATH_STATE_OPEN;
- /* set the windows to default. these are the windows
- * that alice thinks bob has.
- */
- hop->package_window = CIRCWINDOW_START;
- hop->deliver_window = CIRCWINDOW_START;
- onion_append_to_cpath(&circ->cpath, hop);
- circ->build_state->pending_final_cpath = NULL; /* prevent double-free */
- return 0;
- err:
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
- return -1;
- }
- /** Find all the apconns in state AP_CONN_STATE_RENDDESC_WAIT that
- * are waiting on query. If there's a working cache entry here
- * with at least one intro point, move them to the next state;
- * else fail them.
- */
- void
- rend_client_desc_here(const char *query)
- {
- edge_connection_t *conn;
- rend_cache_entry_t *entry;
- time_t now = time(NULL);
- smartlist_t *conns = get_connection_array();
- SMARTLIST_FOREACH(conns, connection_t *, _conn,
- {
- if (_conn->type != CONN_TYPE_AP ||
- _conn->state != AP_CONN_STATE_RENDDESC_WAIT ||
- _conn->marked_for_close)
- continue;
- conn = TO_EDGE_CONN(_conn);
- if (rend_cmp_service_ids(query, conn->rend_query))
- continue;
- assert_connection_ok(TO_CONN(conn), now);
- if (rend_cache_lookup_entry(conn->rend_query, -1, &entry) == 1 &&
- smartlist_len(entry->parsed->intro_nodes) > 0) {
- /* either this fetch worked, or it failed but there was a
- * valid entry from before which we should reuse */
- log_info(LD_REND,"Rend desc is usable. Launching circuits.");
- conn->_base.state = AP_CONN_STATE_CIRCUIT_WAIT;
- /* restart their timeout values, so they get a fair shake at
- * connecting to the hidden service. */
- conn->_base.timestamp_created = now;
- conn->_base.timestamp_lastread = now;
- conn->_base.timestamp_lastwritten = now;
- if (connection_ap_handshake_attach_circuit(conn) < 0) {
- /* it will never work */
- log_warn(LD_REND,"Rendezvous attempt failed. Closing.");
- connection_mark_unattached_ap(conn, END_STREAM_REASON_CANT_ATTACH);
- }
- } else { /* 404, or fetch didn't get that far */
- log_notice(LD_REND,"Closing stream for '%s.onion': hidden service is "
- "unavailable (try again later).", safe_str(query));
- connection_mark_unattached_ap(conn, END_STREAM_REASON_RESOLVEFAILED);
- }
- });
- }
- /** Return a newly allocated extend_info_t* for a randomly chosen introduction
- * point for the named hidden service. Return NULL if all introduction points
- * have been tried and failed.
- */
- extend_info_t *
- rend_client_get_random_intro(const char *query)
- {
- int i;
- rend_cache_entry_t *entry;
- rend_intro_point_t *intro;
- routerinfo_t *router;
- if (rend_cache_lookup_entry(query, -1, &entry) < 1) {
- log_warn(LD_REND,
- "Query '%s' didn't have valid rend desc in cache. Failing.",
- safe_str(query));
- return NULL;
- }
- again:
- if (smartlist_len(entry->parsed->intro_nodes) == 0)
- return NULL;
- i = crypto_rand_int(smartlist_len(entry->parsed->intro_nodes));
- intro = smartlist_get(entry->parsed->intro_nodes, i);
- /* Do we need to look up the router or is the extend info complete? */
- if (!intro->extend_info->onion_key) {
- router = router_get_by_nickname(intro->extend_info->nickname, 0);
- if (!router) {
- log_info(LD_REND, "Unknown router with nickname '%s'; trying another.",
- intro->extend_info->nickname);
- rend_intro_point_free(intro);
- smartlist_del(entry->parsed->intro_nodes, i);
- goto again;
- }
- extend_info_free(intro->extend_info);
- intro->extend_info = extend_info_from_router(router);
- }
- return extend_info_dup(intro->extend_info);
- }
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