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- /* Copyright 2001 Matej Pfajfar.
- * Copyright 2001-2004 Roger Dingledine.
- * Copyright 2004 Roger Dingledine, Nick Mathewson. */
- /* See LICENSE for licensing information */
- /* $Id$ */
- /**
- * \file circuitbuild.c
- * \brief The actual details of building circuits.
- **/
- #include "or.h"
- /********* START VARIABLES **********/
- /** A global list of all circuits at this hop. */
- extern circuit_t *global_circuitlist;
- /********* END VARIABLES ************/
- static int
- circuit_deliver_create_cell(circuit_t *circ, char *payload);
- static cpath_build_state_t *
- onion_new_cpath_build_state(uint8_t purpose, const char *exit_digest);
- static int
- onion_extend_cpath(crypt_path_t **head_ptr, cpath_build_state_t
- *state, routerinfo_t **router_out);
- static int decide_circ_id_type(char *local_nick, char *remote_nick);
- static int count_acceptable_routers(smartlist_t *routers);
- /** Iterate over values of circ_id, starting from conn-\>next_circ_id,
- * and with the high bit specified by circ_id_type (see
- * decide_circ_id_type()), until we get a circ_id that is not in use
- * by any other circuit on that conn.
- *
- * Return it, or 0 if can't get a unique circ_id.
- */
- static uint16_t get_unique_circ_id_by_conn(connection_t *conn, int circ_id_type) {
- uint16_t test_circ_id;
- int attempts=0;
- uint16_t high_bit;
- tor_assert(conn);
- tor_assert(conn->type == CONN_TYPE_OR);
- high_bit = (circ_id_type == CIRC_ID_TYPE_HIGHER) ? 1<<15 : 0;
- do {
- /* Sequentially iterate over test_circ_id=1...1<<15-1 until we find a
- * circID such that (high_bit|test_circ_id) is not already used. */
- test_circ_id = conn->next_circ_id++;
- if (test_circ_id == 0 || test_circ_id >= 1<<15) {
- test_circ_id = 1;
- conn->next_circ_id = 2;
- }
- if(++attempts > 1<<15) {
- /* Make sure we don't loop forever if all circ_id's are used. This
- * matters because it's an external DoS vulnerability.
- */
- log_fn(LOG_WARN,"No unused circ IDs. Failing.");
- return 0;
- }
- test_circ_id |= high_bit;
- } while(circuit_get_by_circ_id_conn(test_circ_id, conn));
- return test_circ_id;
- }
- /** Allocate and return a comma-separated list of the currently built
- * elements of circuit_t.
- */
- char *circuit_list_path(circuit_t *circ)
- {
- struct crypt_path_t *hop;
- routerinfo_t *r;
- smartlist_t *elements;
- char *s;
- tor_assert(CIRCUIT_IS_ORIGIN(circ));
- tor_assert(circ->cpath);
- elements = smartlist_create();
- for (hop = circ->cpath; hop; hop = hop->next) {
- if (hop->state != CPATH_STATE_OPEN)
- break;
- if ((r = router_get_by_digest(hop->identity_digest))) {
- smartlist_add(elements, tor_strdup(r->nickname));
- } else if (circ->purpose == CIRCUIT_PURPOSE_C_REND_JOINED) {
- smartlist_add(elements, tor_strdup("<rendezvous splice>"));
- } else {
- s = tor_malloc(HEX_DIGEST_LEN+2);
- s[0]='$';
- base16_encode(s+1,HEX_DIGEST_LEN+1,hop->identity_digest,DIGEST_LEN);
- smartlist_add(elements, s);
- }
- }
- s = smartlist_join_strings(elements, ",", 0, NULL);
- SMARTLIST_FOREACH(elements, char*, cp, tor_free(cp));
- return s;
- }
- /** Log, at severity <b>severity</b>, the nicknames of each router in
- * circ's cpath. Also log the length of the cpath, and the intended
- * exit point.
- */
- void circuit_log_path(int severity, circuit_t *circ) {
- char buf[1024];
- char *s = buf;
- struct crypt_path_t *hop;
- const char *states[] = {"closed", "waiting for keys", "open"};
- routerinfo_t *router;
- tor_assert(CIRCUIT_IS_ORIGIN(circ));
- tor_assert(circ->cpath);
- tor_snprintf(s, sizeof(buf)-1, "circ (length %d, exit %s): ",
- circ->build_state->desired_path_len, circ->build_state->chosen_exit_name);
- hop=circ->cpath;
- do {
- s = buf + strlen(buf);
- router = router_get_by_digest(hop->identity_digest);
- if(router) {
- tor_snprintf(s, sizeof(buf) - (s - buf), "%s(%s) ",
- router->nickname, states[hop->state]);
- } else {
- if(circ->purpose == CIRCUIT_PURPOSE_C_REND_JOINED) {
- tor_snprintf(s, sizeof(buf) - (s - buf), "(rendjoin hop)");
- } else {
- tor_snprintf(s, sizeof(buf) - (s - buf), "UNKNOWN ");
- }
- }
- hop=hop->next;
- } while(hop!=circ->cpath);
- log_fn(severity,"%s",buf);
- }
- /** Tell the rep(utation)hist(ory) module about the status of the links
- * in circ. Hops that have become OPEN are marked as successfully
- * extended; the _first_ hop that isn't open (if any) is marked as
- * unable to extend.
- */
- void circuit_rep_hist_note_result(circuit_t *circ) {
- struct crypt_path_t *hop;
- char *prev_digest = NULL;
- routerinfo_t *router;
- hop = circ->cpath;
- if(!hop) {
- /* XXX
- * if !hop, then we're not the beginning of this circuit.
- * for now, just forget about it. later, we should remember when
- * extends-through-us failed, too.
- */
- return;
- }
- if (server_mode(get_options())) {
- routerinfo_t *me = router_get_my_routerinfo();
- tor_assert(me);
- prev_digest = me->identity_digest;
- }
- do {
- router = router_get_by_digest(hop->identity_digest);
- if (router) {
- if (prev_digest) {
- if (hop->state == CPATH_STATE_OPEN)
- rep_hist_note_extend_succeeded(prev_digest, router->identity_digest);
- else {
- rep_hist_note_extend_failed(prev_digest, router->identity_digest);
- break;
- }
- }
- prev_digest = router->identity_digest;
- } else {
- prev_digest = NULL;
- }
- hop=hop->next;
- } while (hop!=circ->cpath);
- }
- /** A helper function for circuit_dump_by_conn() below. Log a bunch
- * of information about circuit <b>circ</b>.
- */
- static void
- circuit_dump_details(int severity, circuit_t *circ, int poll_index,
- const char *type, int this_circid, int other_circid) {
- struct crypt_path_t *hop;
- log(severity,"Conn %d has %s circuit: circID %d (other side %d), state %d (%s), born %d",
- poll_index, type, this_circid, other_circid, circ->state,
- circuit_state_to_string[circ->state], (int)circ->timestamp_created);
- if(CIRCUIT_IS_ORIGIN(circ)) { /* circ starts at this node */
- if(circ->state == CIRCUIT_STATE_BUILDING)
- log(severity,"Building: desired len %d, planned exit node %s.",
- circ->build_state->desired_path_len, circ->build_state->chosen_exit_name);
- for(hop=circ->cpath;hop->next != circ->cpath; hop=hop->next)
- log(severity,"hop: state %d, addr 0x%.8x, port %d", hop->state,
- (unsigned int)hop->addr,
- (int)hop->port);
- }
- }
- /** Log, at severity <b>severity</b>, information about each circuit
- * that is connected to <b>conn</b>.
- */
- void circuit_dump_by_conn(connection_t *conn, int severity) {
- circuit_t *circ;
- connection_t *tmpconn;
- for(circ=global_circuitlist;circ;circ = circ->next) {
- if(circ->p_conn == conn)
- circuit_dump_details(severity, circ, conn->poll_index, "App-ward",
- circ->p_circ_id, circ->n_circ_id);
- for(tmpconn=circ->p_streams; tmpconn; tmpconn=tmpconn->next_stream) {
- if(tmpconn == conn) {
- circuit_dump_details(severity, circ, conn->poll_index, "App-ward",
- circ->p_circ_id, circ->n_circ_id);
- }
- }
- if(circ->n_conn == conn)
- circuit_dump_details(severity, circ, conn->poll_index, "Exit-ward",
- circ->n_circ_id, circ->p_circ_id);
- for(tmpconn=circ->n_streams; tmpconn; tmpconn=tmpconn->next_stream) {
- if(tmpconn == conn) {
- circuit_dump_details(severity, circ, conn->poll_index, "Exit-ward",
- circ->n_circ_id, circ->p_circ_id);
- }
- }
- }
- }
- /** Build a new circuit for <b>purpose</b>. If <b>exit_digest</b>
- * is defined, then use that as your exit router, else choose a suitable
- * exit node.
- *
- * Also launch a connection to the first OR in the chosen path, if
- * it's not open already.
- */
- circuit_t *circuit_establish_circuit(uint8_t purpose,
- const char *exit_digest) {
- routerinfo_t *firsthop;
- connection_t *n_conn;
- circuit_t *circ;
- circ = circuit_new(0, NULL); /* sets circ->p_circ_id and circ->p_conn */
- circ->state = CIRCUIT_STATE_OR_WAIT;
- circ->build_state = onion_new_cpath_build_state(purpose, exit_digest);
- circ->purpose = purpose;
- if (! circ->build_state) {
- log_fn(LOG_INFO,"Generating cpath failed.");
- circuit_mark_for_close(circ);
- return NULL;
- }
- if(onion_extend_cpath(&circ->cpath, circ->build_state, &firsthop)<0 ||
- !CIRCUIT_IS_ORIGIN(circ)) {
- log_fn(LOG_INFO,"Generating first cpath hop failed.");
- circuit_mark_for_close(circ);
- return NULL;
- }
- control_event_circuit_status(circ, CIRC_EVENT_LAUNCHED);
- /* now see if we're already connected to the first OR in 'route' */
- tor_assert(firsthop);
- log_fn(LOG_DEBUG,"Looking for firsthop '%s:%u'",
- firsthop->address,firsthop->or_port);
- /* imprint the circuit with its future n_conn->id */
- memcpy(circ->n_conn_id_digest, firsthop->identity_digest, DIGEST_LEN);
- n_conn = connection_get_by_identity_digest(firsthop->identity_digest,
- CONN_TYPE_OR);
- if(!n_conn || n_conn->state != OR_CONN_STATE_OPEN) { /* not currently connected */
- circ->n_addr = firsthop->addr;
- circ->n_port = firsthop->or_port;
- if(!n_conn) { /* launch the connection */
- n_conn = connection_or_connect(firsthop->addr, firsthop->or_port,
- firsthop->identity_digest);
- if(!n_conn) { /* connect failed, forget the whole thing */
- log_fn(LOG_INFO,"connect to firsthop failed. Closing.");
- circuit_mark_for_close(circ);
- return NULL;
- }
- }
- log_fn(LOG_DEBUG,"connecting in progress (or finished). Good.");
- /* return success. The onion/circuit/etc will be taken care of automatically
- * (may already have been) whenever n_conn reaches OR_CONN_STATE_OPEN.
- */
- return circ;
- } else { /* it's already open. use it. */
- circ->n_addr = n_conn->addr;
- circ->n_port = n_conn->port;
- circ->n_conn = n_conn;
- log_fn(LOG_DEBUG,"Conn open. Delivering first onion skin.");
- if(circuit_send_next_onion_skin(circ) < 0) {
- log_fn(LOG_INFO,"circuit_send_next_onion_skin failed.");
- circuit_mark_for_close(circ);
- return NULL;
- }
- }
- return circ;
- }
- /** Find circuits that are waiting on <b>or_conn</b> to become open,
- * if any, and get them to send their create cells forward.
- */
- void circuit_n_conn_done(connection_t *or_conn, int success) {
- circuit_t *circ;
- log_fn(LOG_DEBUG,"or_conn to %s, success=%d", or_conn->nickname, success);
- for(circ=global_circuitlist;circ;circ = circ->next) {
- if (circ->marked_for_close)
- continue;
- if(!circ->n_conn &&
- circ->n_addr == or_conn->addr &&
- circ->n_port == or_conn->port &&
- !memcmp(or_conn->identity_digest, circ->n_conn_id_digest, DIGEST_LEN)) {
- tor_assert(circ->state == CIRCUIT_STATE_OR_WAIT);
- if(!success) { /* or_conn failed; close circ */
- log_fn(LOG_INFO,"or_conn failed. Closing circ.");
- circuit_mark_for_close(circ);
- continue;
- }
- log_fn(LOG_DEBUG,"Found circ %d, sending create cell.", circ->n_circ_id);
- circ->n_conn = or_conn;
- memcpy(circ->n_conn_id_digest, or_conn->identity_digest, DIGEST_LEN);
- if(CIRCUIT_IS_ORIGIN(circ)) {
- if(circuit_send_next_onion_skin(circ) < 0) {
- log_fn(LOG_INFO,"send_next_onion_skin failed; circuit marked for closing.");
- circuit_mark_for_close(circ);
- continue;
- /* XXX could this be bad, eg if next_onion_skin failed because conn died? */
- }
- } else {
- /* pull the create cell out of circ->onionskin, and send it */
- if(circuit_deliver_create_cell(circ, circ->onionskin) < 0) {
- circuit_mark_for_close(circ);
- continue;
- }
- }
- }
- }
- }
- static int
- circuit_deliver_create_cell(circuit_t *circ, char *payload) {
- int circ_id_type;
- cell_t cell;
- tor_assert(circ);
- tor_assert(circ->n_conn);
- tor_assert(circ->n_conn->type == CONN_TYPE_OR);
- tor_assert(payload);
- /* XXXX008 How can we keep a good upgrade path here? We should
- * compare keys, not nicknames...but older servers will compare nicknames.
- * Should we check server version from the most recent directory? Hm.
- */
- circ_id_type = decide_circ_id_type(get_options()->Nickname,
- circ->n_conn->nickname);
- circ->n_circ_id = get_unique_circ_id_by_conn(circ->n_conn, circ_id_type);
- if(!circ->n_circ_id) {
- log_fn(LOG_WARN,"failed to get unique circID.");
- return -1;
- }
- log_fn(LOG_DEBUG,"Chosen circID %u.",circ->n_circ_id);
- memset(&cell, 0, sizeof(cell_t));
- cell.command = CELL_CREATE;
- cell.circ_id = circ->n_circ_id;
- memcpy(cell.payload, payload, ONIONSKIN_CHALLENGE_LEN);
- connection_or_write_cell_to_buf(&cell, circ->n_conn);
- return 0;
- }
- extern int has_completed_circuit;
- /** This is the backbone function for building circuits.
- *
- * If circ's first hop is closed, then we need to build a create
- * cell and send it forward.
- *
- * Otherwise, we need to build a relay extend cell and send it
- * forward.
- *
- * Return -1 if we want to tear down circ, else return 0.
- */
- int circuit_send_next_onion_skin(circuit_t *circ) {
- crypt_path_t *hop;
- routerinfo_t *router;
- int r;
- char payload[2+4+DIGEST_LEN+ONIONSKIN_CHALLENGE_LEN];
- char *onionskin;
- size_t payload_len;
- tor_assert(circ);
- tor_assert(CIRCUIT_IS_ORIGIN(circ));
- if(circ->cpath->state == CPATH_STATE_CLOSED) {
- log_fn(LOG_DEBUG,"First skin; sending create cell.");
- router = router_get_by_digest(circ->n_conn->identity_digest);
- if (!router) {
- log_fn(LOG_WARN,"Couldn't find routerinfo for %s",
- circ->n_conn->nickname);
- return -1;
- }
- if(onion_skin_create(router->onion_pkey,
- &(circ->cpath->handshake_state),
- payload) < 0) {
- log_fn(LOG_WARN,"onion_skin_create (first hop) failed.");
- return -1;
- }
- if(circuit_deliver_create_cell(circ, payload) < 0)
- return -1;
- circ->cpath->state = CPATH_STATE_AWAITING_KEYS;
- circ->state = CIRCUIT_STATE_BUILDING;
- log_fn(LOG_DEBUG,"first skin; finished sending create cell.");
- } else {
- tor_assert(circ->cpath->state == CPATH_STATE_OPEN);
- tor_assert(circ->state == CIRCUIT_STATE_BUILDING);
- log_fn(LOG_DEBUG,"starting to send subsequent skin.");
- r = onion_extend_cpath(&circ->cpath, circ->build_state, &router);
- if (r==1) {
- /* done building the circuit. whew. */
- circ->state = CIRCUIT_STATE_OPEN;
- log_fn(LOG_INFO,"circuit built!");
- circuit_reset_failure_count(0);
- if(!has_completed_circuit) {
- has_completed_circuit=1;
- log_fn(LOG_NOTICE,"Tor has successfully opened a circuit. Looks like it's working.");
- // XXX008 put a count of known routers here
- }
- circuit_rep_hist_note_result(circ);
- circuit_has_opened(circ); /* do other actions as necessary */
- return 0;
- } else if (r<0) {
- log_fn(LOG_INFO,"Unable to extend circuit path.");
- return -1;
- }
- hop = circ->cpath->prev;
- *(uint32_t*)payload = htonl(hop->addr);
- *(uint16_t*)(payload+4) = htons(hop->port);
- onionskin = payload+2+4;
- memcpy(payload+2+4+ONIONSKIN_CHALLENGE_LEN, hop->identity_digest, DIGEST_LEN);
- payload_len = 2+4+ONIONSKIN_CHALLENGE_LEN+DIGEST_LEN;
- if(onion_skin_create(router->onion_pkey, &(hop->handshake_state), onionskin) < 0) {
- log_fn(LOG_WARN,"onion_skin_create failed.");
- return -1;
- }
- log_fn(LOG_DEBUG,"Sending extend relay cell.");
- /* send it to hop->prev, because it will transfer
- * it to a create cell and then send to hop */
- if(connection_edge_send_command(NULL, circ, RELAY_COMMAND_EXTEND,
- payload, payload_len, hop->prev) < 0)
- return 0; /* circuit is closed */
- hop->state = CPATH_STATE_AWAITING_KEYS;
- }
- return 0;
- }
- /** Take the 'extend' cell, pull out addr/port plus the onion skin. Make
- * sure we're connected to the next hop, and pass it the onion skin in
- * a create cell.
- */
- int circuit_extend(cell_t *cell, circuit_t *circ) {
- connection_t *n_conn;
- relay_header_t rh;
- char *onionskin;
- char *id_digest=NULL;
- routerinfo_t *router;
- if(circ->n_conn) {
- log_fn(LOG_WARN,"n_conn already set. Bug/attack. Closing.");
- return -1;
- }
- relay_header_unpack(&rh, cell->payload);
- if (rh.length < 4+2+ONIONSKIN_CHALLENGE_LEN+DIGEST_LEN) {
- log_fn(LOG_WARN, "Wrong length %d on extend cell. Closing circuit.", rh.length);
- return -1;
- }
- circ->n_addr = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE));
- circ->n_port = ntohs(get_uint16(cell->payload+RELAY_HEADER_SIZE+4));
- onionskin = cell->payload+RELAY_HEADER_SIZE+4+2;
- id_digest = cell->payload+RELAY_HEADER_SIZE+4+2+ONIONSKIN_CHALLENGE_LEN;
- n_conn = connection_get_by_identity_digest(id_digest, CONN_TYPE_OR);
- if(!n_conn || n_conn->state != OR_CONN_STATE_OPEN) {
- /* Note that this will close circuits where the onion has the same
- * router twice in a row in the path. I think that's ok.
- */
- struct in_addr in;
- in.s_addr = htonl(circ->n_addr);
- log_fn(LOG_INFO,"Next router (%s:%d) not connected. Connecting.",
- inet_ntoa(in), circ->n_port);
- router = router_get_by_digest(id_digest);
- memcpy(circ->onionskin, onionskin, ONIONSKIN_CHALLENGE_LEN);
- circ->state = CIRCUIT_STATE_OR_WAIT;
- /* imprint the circuit with its future n_conn->id */
- memcpy(circ->n_conn_id_digest, id_digest, DIGEST_LEN);
- if(n_conn) {
- circ->n_addr = n_conn->addr;
- circ->n_port = n_conn->port;
- } else {
- /* we should try to open a connection */
- n_conn = connection_or_connect(circ->n_addr, circ->n_port, id_digest);
- if(!n_conn) {
- log_fn(LOG_INFO,"Launching n_conn failed. Closing.");
- return -1;
- }
- log_fn(LOG_DEBUG,"connecting in progress (or finished). Good.");
- }
- /* return success. The onion/circuit/etc will be taken care of automatically
- * (may already have been) whenever n_conn reaches OR_CONN_STATE_OPEN.
- */
- return 0;
- }
- /* these may be different if the router connected to us from elsewhere */
- circ->n_addr = n_conn->addr;
- circ->n_port = n_conn->port;
- circ->n_conn = n_conn;
- memcpy(circ->n_conn_id_digest, n_conn->identity_digest, DIGEST_LEN);
- log_fn(LOG_DEBUG,"n_conn is %s:%u",n_conn->address,n_conn->port);
- if(circuit_deliver_create_cell(circ, onionskin) < 0)
- return -1;
- return 0;
- }
- /** Initialize cpath-\>{f|b}_{crypto|digest} from the key material in
- * key_data. key_data must contain CPATH_KEY_MATERIAL bytes, which are
- * used as follows:
- * - 20 to initialize f_digest
- * - 20 to initialize b_digest
- * - 16 to key f_crypto
- * - 16 to key b_crypto
- *
- * (If 'reverse' is true, then f_XX and b_XX are swapped.)
- */
- int circuit_init_cpath_crypto(crypt_path_t *cpath, char *key_data, int reverse)
- {
- crypto_digest_env_t *tmp_digest;
- crypto_cipher_env_t *tmp_crypto;
- tor_assert(cpath);
- tor_assert(key_data);
- tor_assert(!(cpath->f_crypto || cpath->b_crypto ||
- cpath->f_digest || cpath->b_digest));
- log_fn(LOG_DEBUG,"hop init digest forward 0x%.8x, backward 0x%.8x.",
- (unsigned int)*(uint32_t*)key_data, (unsigned int)*(uint32_t*)(key_data+20));
- cpath->f_digest = crypto_new_digest_env();
- crypto_digest_add_bytes(cpath->f_digest, key_data, DIGEST_LEN);
- cpath->b_digest = crypto_new_digest_env();
- crypto_digest_add_bytes(cpath->b_digest, key_data+DIGEST_LEN, DIGEST_LEN);
- log_fn(LOG_DEBUG,"hop init cipher forward 0x%.8x, backward 0x%.8x.",
- (unsigned int)*(uint32_t*)(key_data+40), (unsigned int)*(uint32_t*)(key_data+40+16));
- if (!(cpath->f_crypto =
- crypto_create_init_cipher(key_data+(2*DIGEST_LEN),1))) {
- log(LOG_WARN,"forward cipher initialization failed.");
- return -1;
- }
- if (!(cpath->b_crypto =
- crypto_create_init_cipher(key_data+(2*DIGEST_LEN)+CIPHER_KEY_LEN,0))) {
- log(LOG_WARN,"backward cipher initialization failed.");
- return -1;
- }
- if (reverse) {
- tmp_digest = cpath->f_digest;
- cpath->f_digest = cpath->b_digest;
- cpath->b_digest = tmp_digest;
- tmp_crypto = cpath->f_crypto;
- cpath->f_crypto = cpath->b_crypto;
- cpath->b_crypto = tmp_crypto;
- }
- return 0;
- }
- /** A created or extended cell came back to us on the circuit,
- * and it included <b>reply</b> (the second DH key, plus KH).
- *
- * Calculate the appropriate keys and digests, make sure KH is
- * correct, and initialize this hop of the cpath.
- *
- * Return -1 if we want to mark circ for close, else return 0.
- */
- int circuit_finish_handshake(circuit_t *circ, char *reply) {
- unsigned char keys[CPATH_KEY_MATERIAL_LEN];
- crypt_path_t *hop;
- tor_assert(CIRCUIT_IS_ORIGIN(circ));
- if(circ->cpath->state == CPATH_STATE_AWAITING_KEYS)
- hop = circ->cpath;
- else {
- for(hop=circ->cpath->next;
- hop != circ->cpath && hop->state == CPATH_STATE_OPEN;
- hop=hop->next) ;
- if(hop == circ->cpath) { /* got an extended when we're all done? */
- log_fn(LOG_WARN,"got extended when circ already built? Closing.");
- return -1;
- }
- }
- tor_assert(hop->state == CPATH_STATE_AWAITING_KEYS);
- if(onion_skin_client_handshake(hop->handshake_state, reply, keys,
- DIGEST_LEN*2+CIPHER_KEY_LEN*2) < 0) {
- log_fn(LOG_WARN,"onion_skin_client_handshake failed.");
- return -1;
- }
- crypto_dh_free(hop->handshake_state); /* don't need it anymore */
- hop->handshake_state = NULL;
- /* Remember hash of g^xy */
- memcpy(hop->handshake_digest, reply+DH_KEY_LEN, DIGEST_LEN);
- if (circuit_init_cpath_crypto(hop, keys, 0)<0) {
- return -1;
- }
- hop->state = CPATH_STATE_OPEN;
- log_fn(LOG_INFO,"finished");
- circuit_log_path(LOG_INFO,circ);
- control_event_circuit_status(circ, CIRC_EVENT_EXTENDED);
- return 0;
- }
- /** We received a relay truncated cell on circ.
- *
- * Since we don't ask for truncates currently, getting a truncated
- * means that a connection broke or an extend failed. For now,
- * just give up: for circ to close, and return 0.
- */
- int circuit_truncated(circuit_t *circ, crypt_path_t *layer) {
- // crypt_path_t *victim;
- // connection_t *stream;
- tor_assert(circ);
- tor_assert(CIRCUIT_IS_ORIGIN(circ));
- tor_assert(layer);
- /* XXX Since we don't ask for truncates currently, getting a truncated
- * means that a connection broke or an extend failed. For now,
- * just give up.
- */
- circuit_mark_for_close(circ);
- return 0;
- #if 0
- while(layer->next != circ->cpath) {
- /* we need to clear out layer->next */
- victim = layer->next;
- log_fn(LOG_DEBUG, "Killing a layer of the cpath.");
- for(stream = circ->p_streams; stream; stream=stream->next_stream) {
- if(stream->cpath_layer == victim) {
- log_fn(LOG_INFO, "Marking stream %d for close.", stream->stream_id);
- /* no need to send 'end' relay cells,
- * because the other side's already dead
- */
- stream->has_sent_end = 1;
- connection_mark_for_close(stream);
- }
- }
- layer->next = victim->next;
- circuit_free_cpath_node(victim);
- }
- log_fn(LOG_INFO, "finished");
- return 0;
- #endif
- }
- /** Decide whether the first bit of the circuit ID will be
- * 0 or 1, to avoid conflicts where each side randomly chooses
- * the same circuit ID.
- *
- * Return CIRC_ID_TYPE_LOWER if local_nick is NULL, or if
- * local_nick is lexographically smaller than remote_nick.
- * Else return CIRC_ID_TYPE_HIGHER.
- */
- static int decide_circ_id_type(char *local_nick, char *remote_nick) {
- int result;
- tor_assert(remote_nick);
- if(!local_nick)
- return CIRC_ID_TYPE_LOWER;
- result = strcasecmp(local_nick, remote_nick);
- tor_assert(result);
- if(result < 0)
- return CIRC_ID_TYPE_LOWER;
- return CIRC_ID_TYPE_HIGHER;
- }
- /** Given a response payload and keys, initialize, then send a created
- * cell back.
- */
- int onionskin_answer(circuit_t *circ, unsigned char *payload, unsigned char *keys) {
- cell_t cell;
- crypt_path_t *tmp_cpath;
- tmp_cpath = tor_malloc_zero(sizeof(crypt_path_t));
- memset(&cell, 0, sizeof(cell_t));
- cell.command = CELL_CREATED;
- cell.circ_id = circ->p_circ_id;
- circ->state = CIRCUIT_STATE_OPEN;
- log_fn(LOG_DEBUG,"Entering.");
- memcpy(cell.payload, payload, ONIONSKIN_REPLY_LEN);
- log_fn(LOG_INFO,"init digest forward 0x%.8x, backward 0x%.8x.",
- (unsigned int)*(uint32_t*)(keys), (unsigned int)*(uint32_t*)(keys+20));
- if (circuit_init_cpath_crypto(tmp_cpath, keys, 0)<0) {
- log_fn(LOG_WARN,"Circuit initialization failed");
- tor_free(tmp_cpath);
- return -1;
- }
- circ->n_digest = tmp_cpath->f_digest;
- circ->n_crypto = tmp_cpath->f_crypto;
- circ->p_digest = tmp_cpath->b_digest;
- circ->p_crypto = tmp_cpath->b_crypto;
- tor_free(tmp_cpath);
- memcpy(circ->handshake_digest, cell.payload+DH_KEY_LEN, DIGEST_LEN);
- connection_or_write_cell_to_buf(&cell, circ->p_conn);
- log_fn(LOG_DEBUG,"Finished sending 'created' cell.");
- return 0;
- }
- /** Choose a length for a circuit of purpose <b>purpose</b>.
- * Default length is 3 + the number of endpoints that would give something
- * away. If the routerlist <b>routers</b> doesn't have enough routers
- * to handle the desired path length, return as large a path length as
- * is feasible, except if it's less than 2, in which case return -1.
- */
- static int new_route_len(double cw, uint8_t purpose, smartlist_t *routers) {
- int num_acceptable_routers;
- int routelen;
- tor_assert(cw >= 0.);
- tor_assert(cw < 1.);
- tor_assert(routers);
- #ifdef TOR_PERF
- routelen = 2;
- #else
- if(purpose == CIRCUIT_PURPOSE_C_GENERAL)
- routelen = 3;
- else if(purpose == CIRCUIT_PURPOSE_C_INTRODUCING)
- routelen = 4;
- else if(purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND)
- routelen = 3;
- else if(purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO)
- routelen = 3;
- else if(purpose == CIRCUIT_PURPOSE_S_CONNECT_REND)
- routelen = 4;
- else {
- log_fn(LOG_WARN,"Unhandled purpose %d", purpose);
- return -1;
- }
- #endif
- #if 0
- for(routelen = 3; ; routelen++) { /* 3, increment until coinflip says we're done */
- if (crypto_pseudo_rand_int(255) >= cw*255) /* don't extend */
- break;
- }
- #endif
- log_fn(LOG_DEBUG,"Chosen route length %d (%d routers available).",routelen,
- smartlist_len(routers));
- num_acceptable_routers = count_acceptable_routers(routers);
- if(num_acceptable_routers < 2) {
- log_fn(LOG_INFO,"Not enough acceptable routers (%d). Discarding this circuit.",
- num_acceptable_routers);
- return -1;
- }
- if(num_acceptable_routers < routelen) {
- log_fn(LOG_INFO,"Not enough routers: cutting routelen from %d to %d.",
- routelen, num_acceptable_routers);
- routelen = num_acceptable_routers;
- }
- return routelen;
- }
- /** Return a pointer to a suitable router to be the exit node for the
- * general-purpose circuit we're about to build.
- *
- * Look through the connection array, and choose a router that maximizes
- * the number of pending streams that can exit from this router.
- *
- * Return NULL if we can't find any suitable routers.
- */
- static routerinfo_t *choose_good_exit_server_general(routerlist_t *dir)
- {
- int *n_supported;
- int i, j;
- int n_pending_connections = 0;
- connection_t **carray;
- int n_connections;
- int best_support = -1;
- int n_best_support=0;
- smartlist_t *sl, *preferredexits, *preferredentries, *excludedexits;
- routerinfo_t *router;
- or_options_t *options = get_options();
- preferredentries = smartlist_create();
- add_nickname_list_to_smartlist(preferredentries,options->EntryNodes,1);
- get_connection_array(&carray, &n_connections);
- /* Count how many connections are waiting for a circuit to be built.
- * We use this for log messages now, but in the future we may depend on it.
- */
- for (i = 0; i < n_connections; ++i) {
- if (carray[i]->type == CONN_TYPE_AP &&
- carray[i]->state == AP_CONN_STATE_CIRCUIT_WAIT &&
- !carray[i]->marked_for_close &&
- !circuit_stream_is_being_handled(carray[i]))
- ++n_pending_connections;
- }
- log_fn(LOG_DEBUG, "Choosing exit node; %d connections are pending",
- n_pending_connections);
- /* Now we count, for each of the routers in the directory, how many
- * of the pending connections could possibly exit from that
- * router (n_supported[i]). (We can't be sure about cases where we
- * don't know the IP address of the pending connection.)
- */
- n_supported = tor_malloc(sizeof(int)*smartlist_len(dir->routers));
- for (i = 0; i < smartlist_len(dir->routers); ++i) { /* iterate over routers */
- router = smartlist_get(dir->routers, i);
- if(router_is_me(router)) {
- n_supported[i] = -1;
- log_fn(LOG_DEBUG,"Skipping node %s -- it's me.", router->nickname);
- /* XXX there's probably a reverse predecessor attack here, but
- * it's slow. should we take this out? -RD
- */
- continue;
- }
- if(!router->is_running) {
- n_supported[i] = -1;
- log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- directory says it's not running.",
- router->nickname, i);
- continue; /* skip routers that are known to be down */
- }
- if(!router->is_verified &&
- (!(options->_AllowUnverified & ALLOW_UNVERIFIED_EXIT) ||
- router_is_unreliable_router(router, 1, 1))) {
- /* if it's unverified, and either we don't want it or it's unsuitable */
- n_supported[i] = -1;
- log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- unverified router.",
- router->nickname, i);
- continue; /* skip unverified routers */
- }
- if(router_exit_policy_rejects_all(router)) {
- n_supported[i] = -1;
- log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- it rejects all.",
- router->nickname, i);
- continue; /* skip routers that reject all */
- }
- if(smartlist_len(preferredentries)==1 &&
- router == (routerinfo_t*)smartlist_get(preferredentries, 0)) {
- n_supported[i] = -1;
- log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- it's our only preferred entry node.", router->nickname, i);
- continue;
- }
- n_supported[i] = 0;
- for (j = 0; j < n_connections; ++j) { /* iterate over connections */
- if (carray[j]->type != CONN_TYPE_AP ||
- carray[j]->state != AP_CONN_STATE_CIRCUIT_WAIT ||
- carray[j]->marked_for_close ||
- circuit_stream_is_being_handled(carray[j]))
- continue; /* Skip everything but APs in CIRCUIT_WAIT */
- if(connection_ap_can_use_exit(carray[j], router)) {
- ++n_supported[i];
- log_fn(LOG_DEBUG,"%s is supported. n_supported[%d] now %d.",
- router->nickname, i, n_supported[i]);
- } else {
- log_fn(LOG_DEBUG,"%s (index %d) would reject this stream.",
- router->nickname, i);
- }
- } /* End looping over connections. */
- if (n_supported[i] > best_support) {
- /* If this router is better than previous ones, remember its index
- * and goodness, and start counting how many routers are this good. */
- best_support = n_supported[i]; n_best_support=1;
- log_fn(LOG_DEBUG,"%s is new best supported option so far.",
- router->nickname);
- } else if (n_supported[i] == best_support) {
- /* If this router is _as good_ as the best one, just increment the
- * count of equally good routers.*/
- ++n_best_support;
- }
- }
- log_fn(LOG_INFO, "Found %d servers that might support %d/%d pending connections.",
- n_best_support, best_support, n_pending_connections);
- preferredexits = smartlist_create();
- add_nickname_list_to_smartlist(preferredexits,options->ExitNodes,1);
- excludedexits = smartlist_create();
- add_nickname_list_to_smartlist(excludedexits,options->ExcludeNodes,0);
- sl = smartlist_create();
- /* If any routers definitely support any pending connections, choose one
- * at random. */
- if (best_support > 0) {
- for (i = 0; i < smartlist_len(dir->routers); i++)
- if (n_supported[i] == best_support)
- smartlist_add(sl, smartlist_get(dir->routers, i));
- smartlist_subtract(sl,excludedexits);
- if (options->StrictExitNodes || smartlist_overlap(sl,preferredexits))
- smartlist_intersect(sl,preferredexits);
- router = routerlist_sl_choose_by_bandwidth(sl);
- } else {
- /* Either there are no pending connections, or no routers even seem to
- * possibly support any of them. Choose a router at random. */
- if (best_support == -1) {
- log(LOG_WARN, "All routers are down or middleman -- choosing a doomed exit at random.");
- }
- for(i = 0; i < smartlist_len(dir->routers); i++)
- if(n_supported[i] != -1)
- smartlist_add(sl, smartlist_get(dir->routers, i));
- smartlist_subtract(sl,excludedexits);
- if (options->StrictExitNodes || smartlist_overlap(sl,preferredexits))
- smartlist_intersect(sl,preferredexits);
- router = routerlist_sl_choose_by_bandwidth(sl);
- }
- smartlist_free(preferredexits);
- smartlist_free(preferredentries);
- smartlist_free(excludedexits);
- smartlist_free(sl);
- tor_free(n_supported);
- if(router) {
- log_fn(LOG_INFO, "Chose exit server '%s'", router->nickname);
- return router;
- }
- if (options->StrictExitNodes)
- log_fn(LOG_WARN, "No exit routers seem to be running; can't choose an exit.");
- return NULL;
- }
- /** Return a pointer to a suitable router to be the exit node for the
- * circuit of purpose <b>purpose</b> that we're about to build (or NULL
- * if no router is suitable).
- *
- * For general-purpose circuits, pass it off to
- * choose_good_exit_server_general()
- *
- * For client-side rendezvous circuits, choose a random node, weighted
- * toward the preferences in 'options'.
- */
- static routerinfo_t *choose_good_exit_server(uint8_t purpose, routerlist_t *dir)
- {
- routerinfo_t *r;
- or_options_t *options = get_options();
- switch(purpose) {
- case CIRCUIT_PURPOSE_C_GENERAL:
- return choose_good_exit_server_general(dir);
- case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
- r = router_choose_random_node(options->RendNodes, options->RendExcludeNodes,
- NULL, 0, 1, options->_AllowUnverified & ALLOW_UNVERIFIED_RENDEZVOUS, 0);
- return r;
- }
- log_fn(LOG_WARN,"Unhandled purpose %d", purpose);
- return NULL;
- }
- /** Allocate a cpath_build_state_t, populate it based on
- * <b>purpose</b> and <b>exit_digest</b> (if specified), and
- * return it.
- */
- static cpath_build_state_t *
- onion_new_cpath_build_state(uint8_t purpose, const char *exit_digest)
- {
- routerlist_t *rl;
- int r;
- cpath_build_state_t *info;
- routerinfo_t *exit;
- router_get_routerlist(&rl);
- if (!rl)
- return NULL;
- r = new_route_len(get_options()->PathlenCoinWeight, purpose, rl->routers);
- if (r < 1) /* must be at least 1 */
- return NULL;
- info = tor_malloc_zero(sizeof(cpath_build_state_t));
- info->desired_path_len = r;
- if(exit_digest) { /* the circuit-builder pre-requested one */
- memcpy(info->chosen_exit_digest, exit_digest, DIGEST_LEN);
- exit = router_get_by_digest(exit_digest);
- if (exit) {
- info->chosen_exit_name = tor_strdup(exit->nickname);
- } else {
- info->chosen_exit_name = tor_malloc(HEX_DIGEST_LEN+1);
- base16_encode(info->chosen_exit_name, HEX_DIGEST_LEN+1,
- exit_digest, DIGEST_LEN);
- }
- log_fn(LOG_INFO,"Using requested exit node '%s'", info->chosen_exit_name);
- } else { /* we have to decide one */
- exit = choose_good_exit_server(purpose, rl);
- if(!exit) {
- log_fn(LOG_WARN,"failed to choose an exit server");
- tor_free(info);
- return NULL;
- }
- memcpy(info->chosen_exit_digest, exit->identity_digest, DIGEST_LEN);
- info->chosen_exit_name = tor_strdup(exit->nickname);
- }
- return info;
- }
- /** Return the number of routers in <b>routers</b> that are currently up
- * and available for building circuits through.
- */
- static int count_acceptable_routers(smartlist_t *routers) {
- int i, n;
- int num=0;
- routerinfo_t *r;
- n = smartlist_len(routers);
- for(i=0;i<n;i++) {
- r = smartlist_get(routers, i);
- log_fn(LOG_DEBUG,"Contemplating whether router %d (%s) is a new option...",
- i, r->nickname);
- if(r->is_running == 0) {
- log_fn(LOG_DEBUG,"Nope, the directory says %d is not running.",i);
- goto next_i_loop;
- }
- if(r->is_verified == 0) {
- log_fn(LOG_DEBUG,"Nope, the directory says %d is not verified.",i);
- goto next_i_loop; /* XXX008 */
- }
- num++;
- log_fn(LOG_DEBUG,"I like %d. num_acceptable_routers now %d.",i, num);
- next_i_loop:
- ; /* C requires an explicit statement after the label */
- }
- return num;
- }
- /** Add <b>new_hop</b> to the end of the doubly-linked-list <b>head_ptr</b>.
- *
- * This function is used to extend cpath by another hop.
- */
- void onion_append_to_cpath(crypt_path_t **head_ptr, crypt_path_t *new_hop)
- {
- if (*head_ptr) {
- new_hop->next = (*head_ptr);
- new_hop->prev = (*head_ptr)->prev;
- (*head_ptr)->prev->next = new_hop;
- (*head_ptr)->prev = new_hop;
- } else {
- *head_ptr = new_hop;
- new_hop->prev = new_hop->next = new_hop;
- }
- }
- static routerinfo_t *choose_good_middle_server(cpath_build_state_t *state,
- crypt_path_t *head,
- int cur_len)
- {
- int i;
- routerinfo_t *r, *choice;
- crypt_path_t *cpath;
- smartlist_t *excluded = smartlist_create();
- log_fn(LOG_DEBUG, "Contemplating intermediate hop: random choice.");
- excluded = smartlist_create();
- if((r = router_get_by_digest(state->chosen_exit_digest))) {
- smartlist_add(excluded, r);
- routerlist_add_family(excluded, r);
- }
- if((r = routerlist_find_my_routerinfo())) {
- smartlist_add(excluded, r);
- routerlist_add_family(excluded, r);
- }
- for (i = 0, cpath = head; i < cur_len; ++i, cpath=cpath->next) {
- if((r = router_get_by_digest(cpath->identity_digest))) {
- smartlist_add(excluded, r);
- routerlist_add_family(excluded, r);
- }
- }
- choice = router_choose_random_node(NULL, get_options()->ExcludeNodes, excluded,
- 0, 1, get_options()->_AllowUnverified & ALLOW_UNVERIFIED_MIDDLE, 0);
- smartlist_free(excluded);
- return choice;
- }
- static routerinfo_t *choose_good_entry_server(cpath_build_state_t *state)
- {
- routerinfo_t *r, *choice;
- smartlist_t *excluded = smartlist_create();
- or_options_t *options = get_options();
- char buf[16];
- if((r = router_get_by_digest(state->chosen_exit_digest))) {
- smartlist_add(excluded, r);
- routerlist_add_family(excluded, r);
- }
- if((r = routerlist_find_my_routerinfo())) {
- smartlist_add(excluded, r);
- routerlist_add_family(excluded, r);
- }
- if(options->FascistFirewall) {
- /* exclude all ORs that listen on the wrong port */
- routerlist_t *rl;
- int i;
- router_get_routerlist(&rl);
- if(!rl)
- return NULL;
- for(i=0; i < smartlist_len(rl->routers); i++) {
- r = smartlist_get(rl->routers, i);
- tor_snprintf(buf, sizeof(buf), "%d", r->or_port);
- if (!smartlist_string_isin(options->FirewallPorts, buf))
- smartlist_add(excluded, r);
- }
- }
- choice = router_choose_random_node(options->EntryNodes, options->ExcludeNodes,
- excluded, 0, 1, options->_AllowUnverified & ALLOW_UNVERIFIED_ENTRY,
- options->StrictEntryNodes);
- smartlist_free(excluded);
- return choice;
- }
- /** Choose a suitable next hop in the cpath <b>head_ptr</b>,
- * based on <b>state</b>. Add the hop info to head_ptr, and return a
- * pointer to the chosen router in <b>router_out</b>.
- */
- static int
- onion_extend_cpath(crypt_path_t **head_ptr, cpath_build_state_t
- *state, routerinfo_t **router_out)
- {
- int cur_len;
- crypt_path_t *cpath, *hop;
- routerinfo_t *choice;
- smartlist_t *excludednodes;
- tor_assert(head_ptr);
- tor_assert(router_out);
- if (!*head_ptr) {
- cur_len = 0;
- } else {
- cur_len = 1;
- for (cpath = *head_ptr; cpath->next != *head_ptr; cpath = cpath->next) {
- ++cur_len;
- }
- }
- if (cur_len >= state->desired_path_len) {
- log_fn(LOG_DEBUG, "Path is complete: %d steps long",
- state->desired_path_len);
- return 1;
- }
- log_fn(LOG_DEBUG, "Path is %d long; we want %d", cur_len,
- state->desired_path_len);
- excludednodes = smartlist_create();
- add_nickname_list_to_smartlist(excludednodes,get_options()->ExcludeNodes,0);
- if(cur_len == state->desired_path_len - 1) { /* Picking last node */
- choice = router_get_by_digest(state->chosen_exit_digest);
- } else if(cur_len == 0) { /* picking first node */
- choice = choose_good_entry_server(state);
- } else {
- choice = choose_good_middle_server(state, *head_ptr, cur_len);
- }
- smartlist_free(excludednodes);
- if(!choice) {
- log_fn(LOG_WARN,"Failed to find node for hop %d of our path. Discarding this circuit.", cur_len);
- return -1;
- }
- log_fn(LOG_DEBUG,"Chose router %s for hop %d (exit is %s)",
- choice->nickname, cur_len+1, state->chosen_exit_name);
- hop = tor_malloc_zero(sizeof(crypt_path_t));
- /* link hop into the cpath, at the end. */
- onion_append_to_cpath(head_ptr, hop);
- hop->state = CPATH_STATE_CLOSED;
- hop->port = choice->or_port;
- hop->addr = choice->addr;
- memcpy(hop->identity_digest, choice->identity_digest, DIGEST_LEN);
- hop->package_window = CIRCWINDOW_START;
- hop->deliver_window = CIRCWINDOW_START;
- log_fn(LOG_DEBUG, "Extended circuit path with %s for hop %d",
- choice->nickname, cur_len+1);
- *router_out = choice;
- return 0;
- }
- /*
- Local Variables:
- mode:c
- indent-tabs-mode:nil
- c-basic-offset:2
- End:
- */
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