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- /* Copyright (c) 2001 Matej Pfajfar.
- * Copyright (c) 2001-2004, Roger Dingledine.
- * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2013, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file circuitbuild.c
- * \brief The actual details of building circuits.
- **/
- #include "or.h"
- #include "channel.h"
- #include "circuitbuild.h"
- #include "circuitlist.h"
- #include "circuitstats.h"
- #include "circuituse.h"
- #include "command.h"
- #include "config.h"
- #include "confparse.h"
- #include "connection.h"
- #include "connection_edge.h"
- #include "connection_or.h"
- #include "control.h"
- #include "directory.h"
- #include "entrynodes.h"
- #include "main.h"
- #include "microdesc.h"
- #include "networkstatus.h"
- #include "nodelist.h"
- #include "onion.h"
- #include "onion_tap.h"
- #include "onion_fast.h"
- #include "policies.h"
- #include "transports.h"
- #include "relay.h"
- #include "rephist.h"
- #include "router.h"
- #include "routerlist.h"
- #include "routerparse.h"
- #include "routerset.h"
- #include "crypto.h"
- #include "connection_edge.h"
- #ifndef MIN
- #define MIN(a,b) ((a)<(b)?(a):(b))
- #endif
- static channel_t * channel_connect_for_circuit(const tor_addr_t *addr,
- uint16_t port,
- const char *id_digest);
- static int circuit_deliver_create_cell(circuit_t *circ,
- const create_cell_t *create_cell,
- int relayed);
- static int onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit);
- static crypt_path_t *onion_next_hop_in_cpath(crypt_path_t *cpath);
- static int onion_extend_cpath(origin_circuit_t *circ);
- static int count_acceptable_nodes(smartlist_t *routers);
- static int onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice);
- static int entry_guard_inc_circ_attempt_count(entry_guard_t *guard);
- static void pathbias_count_build_success(origin_circuit_t *circ);
- static void pathbias_count_successful_close(origin_circuit_t *circ);
- static void pathbias_count_collapse(origin_circuit_t *circ);
- static void pathbias_count_use_failed(origin_circuit_t *circ);
- static void pathbias_measure_use_rate(entry_guard_t *guard);
- static void pathbias_measure_close_rate(entry_guard_t *guard);
- static void pathbias_scale_use_rates(entry_guard_t *guard);
- /** This function tries to get a channel to the specified endpoint,
- * and then calls command_setup_channel() to give it the right
- * callbacks.
- */
- static channel_t *
- channel_connect_for_circuit(const tor_addr_t *addr, uint16_t port,
- const char *id_digest)
- {
- channel_t *chan;
- chan = channel_connect(addr, port, id_digest);
- if (chan) command_setup_channel(chan);
- return chan;
- }
- /** Iterate over values of circ_id, starting from conn-\>next_circ_id,
- * and with the high bit specified by conn-\>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 circid_t
- get_unique_circ_id_by_chan(channel_t *chan)
- {
- circid_t test_circ_id;
- circid_t attempts=0;
- circid_t high_bit, max_range;
- tor_assert(chan);
- if (chan->circ_id_type == CIRC_ID_TYPE_NEITHER) {
- log_warn(LD_BUG,
- "Trying to pick a circuit ID for a connection from "
- "a client with no identity.");
- return 0;
- }
- max_range = (chan->wide_circ_ids) ? (1u<<31) : (1u<<15);
- high_bit = (chan->circ_id_type == CIRC_ID_TYPE_HIGHER) ? max_range : 0;
- do {
- /* Sequentially iterate over test_circ_id=1...max_range until we find a
- * circID such that (high_bit|test_circ_id) is not already used. */
- test_circ_id = chan->next_circ_id++;
- if (test_circ_id == 0 || test_circ_id >= max_range) {
- test_circ_id = 1;
- chan->next_circ_id = 2;
- }
- if (++attempts > max_range) {
- /* Make sure we don't loop forever if all circ_id's are used. This
- * matters because it's an external DoS opportunity.
- */
- log_warn(LD_CIRC,"No unused circ IDs. Failing.");
- return 0;
- }
- test_circ_id |= high_bit;
- } while (circuit_id_in_use_on_channel(test_circ_id, chan));
- return test_circ_id;
- }
- /** If <b>verbose</b> is false, allocate and return a comma-separated list of
- * the currently built elements of <b>circ</b>. If <b>verbose</b> is true, also
- * list information about link status in a more verbose format using spaces.
- * If <b>verbose_names</b> is false, give nicknames for Named routers and hex
- * digests for others; if <b>verbose_names</b> is true, use $DIGEST=Name style
- * names.
- */
- static char *
- circuit_list_path_impl(origin_circuit_t *circ, int verbose, int verbose_names)
- {
- crypt_path_t *hop;
- smartlist_t *elements;
- const char *states[] = {"closed", "waiting for keys", "open"};
- char *s;
- elements = smartlist_new();
- if (verbose) {
- const char *nickname = build_state_get_exit_nickname(circ->build_state);
- smartlist_add_asprintf(elements, "%s%s circ (length %d%s%s):",
- circ->build_state->is_internal ? "internal" : "exit",
- circ->build_state->need_uptime ? " (high-uptime)" : "",
- circ->build_state->desired_path_len,
- circ->base_.state == CIRCUIT_STATE_OPEN ? "" : ", last hop ",
- circ->base_.state == CIRCUIT_STATE_OPEN ? "" :
- (nickname?nickname:"*unnamed*"));
- }
- hop = circ->cpath;
- do {
- char *elt;
- const char *id;
- const node_t *node;
- if (!hop)
- break;
- if (!verbose && hop->state != CPATH_STATE_OPEN)
- break;
- if (!hop->extend_info)
- break;
- id = hop->extend_info->identity_digest;
- if (verbose_names) {
- elt = tor_malloc(MAX_VERBOSE_NICKNAME_LEN+1);
- if ((node = node_get_by_id(id))) {
- node_get_verbose_nickname(node, elt);
- } else if (is_legal_nickname(hop->extend_info->nickname)) {
- elt[0] = '$';
- base16_encode(elt+1, HEX_DIGEST_LEN+1, id, DIGEST_LEN);
- elt[HEX_DIGEST_LEN+1]= '~';
- strlcpy(elt+HEX_DIGEST_LEN+2,
- hop->extend_info->nickname, MAX_NICKNAME_LEN+1);
- } else {
- elt[0] = '$';
- base16_encode(elt+1, HEX_DIGEST_LEN+1, id, DIGEST_LEN);
- }
- } else { /* ! verbose_names */
- node = node_get_by_id(id);
- if (node && node_is_named(node)) {
- elt = tor_strdup(node_get_nickname(node));
- } else {
- elt = tor_malloc(HEX_DIGEST_LEN+2);
- elt[0] = '$';
- base16_encode(elt+1, HEX_DIGEST_LEN+1, id, DIGEST_LEN);
- }
- }
- tor_assert(elt);
- if (verbose) {
- tor_assert(hop->state <= 2);
- smartlist_add_asprintf(elements,"%s(%s)",elt,states[hop->state]);
- tor_free(elt);
- } else {
- smartlist_add(elements, elt);
- }
- hop = hop->next;
- } while (hop != circ->cpath);
- s = smartlist_join_strings(elements, verbose?" ":",", 0, NULL);
- SMARTLIST_FOREACH(elements, char*, cp, tor_free(cp));
- smartlist_free(elements);
- return s;
- }
- /** If <b>verbose</b> is false, allocate and return a comma-separated
- * list of the currently built elements of <b>circ</b>. If
- * <b>verbose</b> is true, also list information about link status in
- * a more verbose format using spaces.
- */
- char *
- circuit_list_path(origin_circuit_t *circ, int verbose)
- {
- return circuit_list_path_impl(circ, verbose, 0);
- }
- /** Allocate and return a comma-separated list of the currently built elements
- * of <b>circ</b>, giving each as a verbose nickname.
- */
- char *
- circuit_list_path_for_controller(origin_circuit_t *circ)
- {
- return circuit_list_path_impl(circ, 0, 1);
- }
- /** Log, at severity <b>severity</b>, the nicknames of each router in
- * <b>circ</b>'s cpath. Also log the length of the cpath, and the intended
- * exit point.
- */
- void
- circuit_log_path(int severity, unsigned int domain, origin_circuit_t *circ)
- {
- char *s = circuit_list_path(circ,1);
- tor_log(severity,domain,"%s",s);
- tor_free(s);
- }
- /** Tell the rep(utation)hist(ory) module about the status of the links
- * in <b>circ</b>. 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.
- */
- /* XXXX Someday we should learn from OR circuits too. */
- void
- circuit_rep_hist_note_result(origin_circuit_t *circ)
- {
- crypt_path_t *hop;
- const char *prev_digest = NULL;
- hop = circ->cpath;
- if (!hop) /* circuit hasn't started building yet. */
- return;
- if (server_mode(get_options())) {
- const routerinfo_t *me = router_get_my_routerinfo();
- if (!me)
- return;
- prev_digest = me->cache_info.identity_digest;
- }
- do {
- const node_t *node = node_get_by_id(hop->extend_info->identity_digest);
- if (node) { /* Why do we check this? We know the identity. -NM XXXX */
- if (prev_digest) {
- if (hop->state == CPATH_STATE_OPEN)
- rep_hist_note_extend_succeeded(prev_digest, node->identity);
- else {
- rep_hist_note_extend_failed(prev_digest, node->identity);
- break;
- }
- }
- prev_digest = node->identity;
- } else {
- prev_digest = NULL;
- }
- hop=hop->next;
- } while (hop!=circ->cpath);
- }
- /** Pick all the entries in our cpath. Stop and return 0 when we're
- * happy, or return -1 if an error occurs. */
- static int
- onion_populate_cpath(origin_circuit_t *circ)
- {
- int r;
- again:
- r = onion_extend_cpath(circ);
- if (r < 0) {
- log_info(LD_CIRC,"Generating cpath hop failed.");
- return -1;
- }
- if (r == 0)
- goto again;
- return 0; /* if r == 1 */
- }
- /** Create and return a new origin circuit. Initialize its purpose and
- * build-state based on our arguments. The <b>flags</b> argument is a
- * bitfield of CIRCLAUNCH_* flags. */
- origin_circuit_t *
- origin_circuit_init(uint8_t purpose, int flags)
- {
- /* sets circ->p_circ_id and circ->p_chan */
- origin_circuit_t *circ = origin_circuit_new();
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_CHAN_WAIT);
- circ->build_state = tor_malloc_zero(sizeof(cpath_build_state_t));
- circ->build_state->onehop_tunnel =
- ((flags & CIRCLAUNCH_ONEHOP_TUNNEL) ? 1 : 0);
- circ->build_state->need_uptime =
- ((flags & CIRCLAUNCH_NEED_UPTIME) ? 1 : 0);
- circ->build_state->need_capacity =
- ((flags & CIRCLAUNCH_NEED_CAPACITY) ? 1 : 0);
- circ->build_state->is_internal =
- ((flags & CIRCLAUNCH_IS_INTERNAL) ? 1 : 0);
- circ->base_.purpose = purpose;
- return circ;
- }
- /** Build a new circuit for <b>purpose</b>. If <b>exit</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.
- */
- origin_circuit_t *
- circuit_establish_circuit(uint8_t purpose, extend_info_t *exit, int flags)
- {
- origin_circuit_t *circ;
- int err_reason = 0;
- circ = origin_circuit_init(purpose, flags);
- if (onion_pick_cpath_exit(circ, exit) < 0 ||
- onion_populate_cpath(circ) < 0) {
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_NOPATH);
- return NULL;
- }
- control_event_circuit_status(circ, CIRC_EVENT_LAUNCHED, 0);
- if ((err_reason = circuit_handle_first_hop(circ)) < 0) {
- circuit_mark_for_close(TO_CIRCUIT(circ), -err_reason);
- return NULL;
- }
- return circ;
- }
- /** Start establishing the first hop of our circuit. Figure out what
- * OR we should connect to, and if necessary start the connection to
- * it. If we're already connected, then send the 'create' cell.
- * Return 0 for ok, -reason if circ should be marked-for-close. */
- int
- circuit_handle_first_hop(origin_circuit_t *circ)
- {
- crypt_path_t *firsthop;
- channel_t *n_chan;
- int err_reason = 0;
- const char *msg = NULL;
- int should_launch = 0;
- firsthop = onion_next_hop_in_cpath(circ->cpath);
- tor_assert(firsthop);
- tor_assert(firsthop->extend_info);
- /* now see if we're already connected to the first OR in 'route' */
- log_debug(LD_CIRC,"Looking for firsthop '%s'",
- fmt_addrport(&firsthop->extend_info->addr,
- firsthop->extend_info->port));
- n_chan = channel_get_for_extend(firsthop->extend_info->identity_digest,
- &firsthop->extend_info->addr,
- &msg,
- &should_launch);
- if (!n_chan) {
- /* not currently connected in a useful way. */
- log_info(LD_CIRC, "Next router is %s: %s",
- safe_str_client(extend_info_describe(firsthop->extend_info)),
- msg?msg:"???");
- circ->base_.n_hop = extend_info_dup(firsthop->extend_info);
- if (should_launch) {
- if (circ->build_state->onehop_tunnel)
- control_event_bootstrap(BOOTSTRAP_STATUS_CONN_DIR, 0);
- n_chan = channel_connect_for_circuit(
- &firsthop->extend_info->addr,
- firsthop->extend_info->port,
- firsthop->extend_info->identity_digest);
- if (!n_chan) { /* connect failed, forget the whole thing */
- log_info(LD_CIRC,"connect to firsthop failed. Closing.");
- return -END_CIRC_REASON_CONNECTFAILED;
- }
- }
- log_debug(LD_CIRC,"connecting in progress (or finished). Good.");
- /* return success. The onion/circuit/etc will be taken care of
- * automatically (may already have been) whenever n_chan reaches
- * OR_CONN_STATE_OPEN.
- */
- return 0;
- } else { /* it's already open. use it. */
- tor_assert(!circ->base_.n_hop);
- circ->base_.n_chan = n_chan;
- log_debug(LD_CIRC,"Conn open. Delivering first onion skin.");
- if ((err_reason = circuit_send_next_onion_skin(circ)) < 0) {
- log_info(LD_CIRC,"circuit_send_next_onion_skin failed.");
- return err_reason;
- }
- }
- return 0;
- }
- /** Find any circuits that are waiting on <b>or_conn</b> to become
- * open and get them to send their create cells forward.
- *
- * Status is 1 if connect succeeded, or 0 if connect failed.
- */
- void
- circuit_n_chan_done(channel_t *chan, int status)
- {
- smartlist_t *pending_circs;
- int err_reason = 0;
- tor_assert(chan);
- log_debug(LD_CIRC,"chan to %s/%s, status=%d",
- chan->nickname ? chan->nickname : "NULL",
- channel_get_canonical_remote_descr(chan), status);
- pending_circs = smartlist_new();
- circuit_get_all_pending_on_channel(pending_circs, chan);
- SMARTLIST_FOREACH_BEGIN(pending_circs, circuit_t *, circ)
- {
- /* These checks are redundant wrt get_all_pending_on_or_conn, but I'm
- * leaving them in in case it's possible for the status of a circuit to
- * change as we're going down the list. */
- if (circ->marked_for_close || circ->n_chan || !circ->n_hop ||
- circ->state != CIRCUIT_STATE_CHAN_WAIT)
- continue;
- if (tor_digest_is_zero(circ->n_hop->identity_digest)) {
- /* Look at addr/port. This is an unkeyed connection. */
- if (!channel_matches_extend_info(chan, circ->n_hop))
- continue;
- } else {
- /* We expected a key. See if it's the right one. */
- if (tor_memneq(chan->identity_digest,
- circ->n_hop->identity_digest, DIGEST_LEN))
- continue;
- }
- if (!status) { /* chan failed; close circ */
- log_info(LD_CIRC,"Channel failed; closing circ.");
- circuit_mark_for_close(circ, END_CIRC_REASON_CHANNEL_CLOSED);
- continue;
- }
- log_debug(LD_CIRC, "Found circ, sending create cell.");
- /* circuit_deliver_create_cell will set n_circ_id and add us to
- * chan_circuid_circuit_map, so we don't need to call
- * set_circid_chan here. */
- circ->n_chan = chan;
- extend_info_free(circ->n_hop);
- circ->n_hop = NULL;
- if (CIRCUIT_IS_ORIGIN(circ)) {
- if ((err_reason =
- circuit_send_next_onion_skin(TO_ORIGIN_CIRCUIT(circ))) < 0) {
- log_info(LD_CIRC,
- "send_next_onion_skin failed; circuit marked for closing.");
- circuit_mark_for_close(circ, -err_reason);
- continue;
- /* XXX could this be bad, eg if next_onion_skin failed because conn
- * died? */
- }
- } else {
- /* pull the create cell out of circ->n_chan_create_cell, and send it */
- tor_assert(circ->n_chan_create_cell);
- if (circuit_deliver_create_cell(circ, circ->n_chan_create_cell, 1)<0) {
- circuit_mark_for_close(circ, END_CIRC_REASON_RESOURCELIMIT);
- continue;
- }
- tor_free(circ->n_chan_create_cell);
- circuit_set_state(circ, CIRCUIT_STATE_OPEN);
- }
- }
- SMARTLIST_FOREACH_END(circ);
- smartlist_free(pending_circs);
- }
- /** Find a new circid that isn't currently in use on the circ->n_chan
- * for the outgoing
- * circuit <b>circ</b>, and deliver the cell <b>create_cell</b> to this
- * circuit. If <b>relayed</b> is true, this is a create cell somebody
- * gave us via an EXTEND cell, so we shouldn't worry if we don't understand
- * it. Return -1 if we failed to find a suitable circid, else return 0.
- */
- static int
- circuit_deliver_create_cell(circuit_t *circ, const create_cell_t *create_cell,
- int relayed)
- {
- cell_t cell;
- circid_t id;
- int r;
- tor_assert(circ);
- tor_assert(circ->n_chan);
- tor_assert(create_cell);
- tor_assert(create_cell->cell_type == CELL_CREATE ||
- create_cell->cell_type == CELL_CREATE_FAST ||
- create_cell->cell_type == CELL_CREATE2);
- id = get_unique_circ_id_by_chan(circ->n_chan);
- if (!id) {
- log_warn(LD_CIRC,"failed to get unique circID.");
- return -1;
- }
- log_debug(LD_CIRC,"Chosen circID %u.", (unsigned)id);
- circuit_set_n_circid_chan(circ, id, circ->n_chan);
- memset(&cell, 0, sizeof(cell_t));
- r = relayed ? create_cell_format_relayed(&cell, create_cell)
- : create_cell_format(&cell, create_cell);
- if (r < 0) {
- log_warn(LD_CIRC,"Couldn't format create cell");
- return -1;
- }
- cell.circ_id = circ->n_circ_id;
- append_cell_to_circuit_queue(circ, circ->n_chan, &cell,
- CELL_DIRECTION_OUT, 0);
- if (CIRCUIT_IS_ORIGIN(circ)) {
- /* Update began timestamp for circuits starting their first hop */
- if (TO_ORIGIN_CIRCUIT(circ)->cpath->state == CPATH_STATE_CLOSED) {
- if (circ->n_chan->state != CHANNEL_STATE_OPEN) {
- log_warn(LD_CIRC,
- "Got first hop for a circuit without an opened channel. "
- "State: %s.", channel_state_to_string(circ->n_chan->state));
- tor_fragile_assert();
- }
- tor_gettimeofday(&circ->timestamp_began);
- }
- /* mark it so it gets better rate limiting treatment. */
- channel_timestamp_client(circ->n_chan);
- }
- return 0;
- }
- /** We've decided to start our reachability testing. If all
- * is set, log this to the user. Return 1 if we did, or 0 if
- * we chose not to log anything. */
- int
- inform_testing_reachability(void)
- {
- char dirbuf[128];
- const routerinfo_t *me = router_get_my_routerinfo();
- if (!me)
- return 0;
- control_event_server_status(LOG_NOTICE,
- "CHECKING_REACHABILITY ORADDRESS=%s:%d",
- me->address, me->or_port);
- if (me->dir_port) {
- tor_snprintf(dirbuf, sizeof(dirbuf), " and DirPort %s:%d",
- me->address, me->dir_port);
- control_event_server_status(LOG_NOTICE,
- "CHECKING_REACHABILITY DIRADDRESS=%s:%d",
- me->address, me->dir_port);
- }
- log_notice(LD_OR, "Now checking whether ORPort %s:%d%s %s reachable... "
- "(this may take up to %d minutes -- look for log "
- "messages indicating success)",
- me->address, me->or_port,
- me->dir_port ? dirbuf : "",
- me->dir_port ? "are" : "is",
- TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT/60);
- return 1;
- }
- /** Return true iff we should send a create_fast cell to start building a given
- * circuit */
- static INLINE int
- should_use_create_fast_for_circuit(origin_circuit_t *circ)
- {
- const or_options_t *options = get_options();
- tor_assert(circ->cpath);
- tor_assert(circ->cpath->extend_info);
- if (!circ->cpath->extend_info->onion_key)
- return 1; /* our hand is forced: only a create_fast will work. */
- if (!options->FastFirstHopPK)
- return 0; /* we prefer to avoid create_fast */
- if (public_server_mode(options)) {
- /* We're a server, and we know an onion key. We can choose.
- * Prefer to blend our circuit into the other circuits we are
- * creating on behalf of others. */
- return 0;
- }
- return 1;
- }
- /** Return true if <b>circ</b> is the type of circuit we want to count
- * timeouts from. In particular, we want it to have not completed yet
- * (already completing indicates we cannibalized it), and we want it to
- * have exactly three hops.
- */
- int
- circuit_timeout_want_to_count_circ(origin_circuit_t *circ)
- {
- return !circ->has_opened
- && circ->build_state->desired_path_len == DEFAULT_ROUTE_LEN;
- }
- #ifdef CURVE25519_ENABLED
- /** Return true if the ntor handshake is enabled in the configuration, or if
- * it's been set to "auto" in the configuration and it's enabled in the
- * consensus. */
- static int
- circuits_can_use_ntor(void)
- {
- const or_options_t *options = get_options();
- if (options->UseNTorHandshake != -1)
- return options->UseNTorHandshake;
- return networkstatus_get_param(NULL, "UseNTorHandshake", 0, 0, 1);
- }
- #endif
- /** Decide whether to use a TAP or ntor handshake for connecting to <b>ei</b>
- * directly, and set *<b>cell_type_out</b> and *<b>handshake_type_out</b>
- * accordingly. */
- static void
- circuit_pick_create_handshake(uint8_t *cell_type_out,
- uint16_t *handshake_type_out,
- const extend_info_t *ei)
- {
- #ifdef CURVE25519_ENABLED
- if (!tor_mem_is_zero((const char*)ei->curve25519_onion_key.public_key,
- CURVE25519_PUBKEY_LEN) &&
- circuits_can_use_ntor()) {
- *cell_type_out = CELL_CREATE2;
- *handshake_type_out = ONION_HANDSHAKE_TYPE_NTOR;
- return;
- }
- #else
- (void) ei;
- #endif
- *cell_type_out = CELL_CREATE;
- *handshake_type_out = ONION_HANDSHAKE_TYPE_TAP;
- }
- /** Decide whether to use a TAP or ntor handshake for connecting to <b>ei</b>
- * directly, and set *<b>handshake_type_out</b> accordingly. Decide whether,
- * in extending through <b>node</b> to do so, we should use an EXTEND2 or an
- * EXTEND cell to do so, and set *<b>cell_type_out</b> and
- * *<b>create_cell_type_out</b> accordingly. */
- static void
- circuit_pick_extend_handshake(uint8_t *cell_type_out,
- uint8_t *create_cell_type_out,
- uint16_t *handshake_type_out,
- const node_t *node_prev,
- const extend_info_t *ei)
- {
- uint8_t t;
- circuit_pick_create_handshake(&t, handshake_type_out, ei);
- /* XXXX024 The check for whether the node has a curve25519 key is a bad
- * proxy for whether it can do extend2 cells; once a version that
- * handles extend2 cells is out, remove it. */
- if (node_prev &&
- *handshake_type_out != ONION_HANDSHAKE_TYPE_TAP &&
- (node_has_curve25519_onion_key(node_prev) ||
- (node_prev->rs && node_prev->rs->version_supports_extend2_cells))) {
- *cell_type_out = RELAY_COMMAND_EXTEND2;
- *create_cell_type_out = CELL_CREATE2;
- } else {
- *cell_type_out = RELAY_COMMAND_EXTEND;
- *create_cell_type_out = CELL_CREATE;
- }
- }
- /** 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 -reason if we want to tear down circ, else return 0.
- */
- int
- circuit_send_next_onion_skin(origin_circuit_t *circ)
- {
- crypt_path_t *hop;
- const node_t *node;
- tor_assert(circ);
- if (circ->cpath->state == CPATH_STATE_CLOSED) {
- /* This is the first hop. */
- create_cell_t cc;
- int fast;
- int len;
- log_debug(LD_CIRC,"First skin; sending create cell.");
- memset(&cc, 0, sizeof(cc));
- if (circ->build_state->onehop_tunnel)
- control_event_bootstrap(BOOTSTRAP_STATUS_ONEHOP_CREATE, 0);
- else
- control_event_bootstrap(BOOTSTRAP_STATUS_CIRCUIT_CREATE, 0);
- node = node_get_by_id(circ->base_.n_chan->identity_digest);
- fast = should_use_create_fast_for_circuit(circ);
- if (!fast) {
- /* We are an OR and we know the right onion key: we should
- * send a create cell.
- */
- circuit_pick_create_handshake(&cc.cell_type, &cc.handshake_type,
- circ->cpath->extend_info);
- note_request("cell: create", 1);
- } else {
- /* We are not an OR, and we're building the first hop of a circuit to a
- * new OR: we can be speedy and use CREATE_FAST to save an RSA operation
- * and a DH operation. */
- cc.cell_type = CELL_CREATE_FAST;
- cc.handshake_type = ONION_HANDSHAKE_TYPE_FAST;
- note_request("cell: create fast", 1);
- }
- len = onion_skin_create(cc.handshake_type,
- circ->cpath->extend_info,
- &circ->cpath->handshake_state,
- cc.onionskin);
- if (len < 0) {
- log_warn(LD_CIRC,"onion_skin_create (first hop) failed.");
- return - END_CIRC_REASON_INTERNAL;
- }
- cc.handshake_len = len;
- if (circuit_deliver_create_cell(TO_CIRCUIT(circ), &cc, 0) < 0)
- return - END_CIRC_REASON_RESOURCELIMIT;
- circ->cpath->state = CPATH_STATE_AWAITING_KEYS;
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_BUILDING);
- log_info(LD_CIRC,"First hop: finished sending %s cell to '%s'",
- fast ? "CREATE_FAST" : "CREATE",
- node ? node_describe(node) : "<unnamed>");
- } else {
- extend_cell_t ec;
- int len;
- tor_assert(circ->cpath->state == CPATH_STATE_OPEN);
- tor_assert(circ->base_.state == CIRCUIT_STATE_BUILDING);
- log_debug(LD_CIRC,"starting to send subsequent skin.");
- hop = onion_next_hop_in_cpath(circ->cpath);
- memset(&ec, 0, sizeof(ec));
- if (!hop) {
- /* done building the circuit. whew. */
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_OPEN);
- if (circuit_timeout_want_to_count_circ(circ)) {
- struct timeval end;
- long timediff;
- tor_gettimeofday(&end);
- timediff = tv_mdiff(&circ->base_.timestamp_began, &end);
- /*
- * If the circuit build time is much greater than we would have cut
- * it off at, we probably had a suspend event along this codepath,
- * and we should discard the value.
- */
- if (timediff < 0 ||
- timediff > 2*get_circuit_build_close_time_ms()+1000) {
- log_notice(LD_CIRC, "Strange value for circuit build time: %ldmsec. "
- "Assuming clock jump. Purpose %d (%s)", timediff,
- circ->base_.purpose,
- circuit_purpose_to_string(circ->base_.purpose));
- } else if (!circuit_build_times_disabled()) {
- /* Only count circuit times if the network is live */
- if (circuit_build_times_network_check_live(
- get_circuit_build_times())) {
- circuit_build_times_add_time(get_circuit_build_times_mutable(),
- (build_time_t)timediff);
- circuit_build_times_set_timeout(get_circuit_build_times_mutable());
- }
- if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
- circuit_build_times_network_circ_success(
- get_circuit_build_times_mutable());
- }
- }
- }
- log_info(LD_CIRC,"circuit built!");
- circuit_reset_failure_count(0);
- if (circ->build_state->onehop_tunnel || circ->has_opened) {
- control_event_bootstrap(BOOTSTRAP_STATUS_REQUESTING_STATUS, 0);
- }
- pathbias_count_build_success(circ);
- circuit_rep_hist_note_result(circ);
- circuit_has_opened(circ); /* do other actions as necessary */
- if (!can_complete_circuit && !circ->build_state->onehop_tunnel) {
- const or_options_t *options = get_options();
- can_complete_circuit=1;
- /* FFFF Log a count of known routers here */
- log_notice(LD_GENERAL,
- "Tor has successfully opened a circuit. "
- "Looks like client functionality is working.");
- control_event_bootstrap(BOOTSTRAP_STATUS_DONE, 0);
- control_event_client_status(LOG_NOTICE, "CIRCUIT_ESTABLISHED");
- clear_broken_connection_map(1);
- if (server_mode(options) && !check_whether_orport_reachable()) {
- inform_testing_reachability();
- consider_testing_reachability(1, 1);
- }
- }
- /* We're done with measurement circuits here. Just close them */
- if (circ->base_.purpose == CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
- circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_FINISHED);
- }
- return 0;
- }
- if (tor_addr_family(&hop->extend_info->addr) != AF_INET) {
- log_warn(LD_BUG, "Trying to extend to a non-IPv4 address.");
- return - END_CIRC_REASON_INTERNAL;
- }
- {
- const node_t *prev_node;
- prev_node = node_get_by_id(hop->prev->extend_info->identity_digest);
- circuit_pick_extend_handshake(&ec.cell_type,
- &ec.create_cell.cell_type,
- &ec.create_cell.handshake_type,
- prev_node,
- hop->extend_info);
- }
- tor_addr_copy(&ec.orport_ipv4.addr, &hop->extend_info->addr);
- ec.orport_ipv4.port = hop->extend_info->port;
- tor_addr_make_unspec(&ec.orport_ipv6.addr);
- memcpy(ec.node_id, hop->extend_info->identity_digest, DIGEST_LEN);
- len = onion_skin_create(ec.create_cell.handshake_type,
- hop->extend_info,
- &hop->handshake_state,
- ec.create_cell.onionskin);
- if (len < 0) {
- log_warn(LD_CIRC,"onion_skin_create failed.");
- return - END_CIRC_REASON_INTERNAL;
- }
- ec.create_cell.handshake_len = len;
- log_info(LD_CIRC,"Sending extend relay cell.");
- note_request("cell: extend", 1);
- {
- uint8_t command = 0;
- uint16_t payload_len=0;
- uint8_t payload[RELAY_PAYLOAD_SIZE];
- if (extend_cell_format(&command, &payload_len, payload, &ec)<0) {
- log_warn(LD_CIRC,"Couldn't format extend cell");
- return -END_CIRC_REASON_INTERNAL;
- }
- /* send it to hop->prev, because it will transfer
- * it to a create cell and then send to hop */
- if (relay_send_command_from_edge(0, TO_CIRCUIT(circ),
- command,
- (char*)payload, payload_len,
- hop->prev) < 0)
- return 0; /* circuit is closed */
- }
- hop->state = CPATH_STATE_AWAITING_KEYS;
- }
- return 0;
- }
- /** Our clock just jumped by <b>seconds_elapsed</b>. Assume
- * something has also gone wrong with our network: notify the user,
- * and abandon all not-yet-used circuits. */
- void
- circuit_note_clock_jumped(int seconds_elapsed)
- {
- int severity = server_mode(get_options()) ? LOG_WARN : LOG_NOTICE;
- tor_log(severity, LD_GENERAL, "Your system clock just jumped %d seconds %s; "
- "assuming established circuits no longer work.",
- seconds_elapsed >=0 ? seconds_elapsed : -seconds_elapsed,
- seconds_elapsed >=0 ? "forward" : "backward");
- control_event_general_status(LOG_WARN, "CLOCK_JUMPED TIME=%d",
- seconds_elapsed);
- can_complete_circuit=0; /* so it'll log when it works again */
- control_event_client_status(severity, "CIRCUIT_NOT_ESTABLISHED REASON=%s",
- "CLOCK_JUMPED");
- circuit_mark_all_unused_circs();
- circuit_mark_all_dirty_circs_as_unusable();
- }
- /** Take the 'extend' <b>cell</b>, pull out addr/port plus the onion
- * skin and identity digest for the next hop. If we're already connected,
- * pass the onion skin to the next hop using a create cell; otherwise
- * launch a new OR connection, and <b>circ</b> will notice when the
- * connection succeeds or fails.
- *
- * Return -1 if we want to warn and tear down the circuit, else return 0.
- */
- int
- circuit_extend(cell_t *cell, circuit_t *circ)
- {
- channel_t *n_chan;
- relay_header_t rh;
- extend_cell_t ec;
- const char *msg = NULL;
- int should_launch = 0;
- if (circ->n_chan) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "n_chan already set. Bug/attack. Closing.");
- return -1;
- }
- if (circ->n_hop) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "conn to next hop already launched. Bug/attack. Closing.");
- return -1;
- }
- if (!server_mode(get_options())) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Got an extend cell, but running as a client. Closing.");
- return -1;
- }
- relay_header_unpack(&rh, cell->payload);
- if (extend_cell_parse(&ec, rh.command,
- cell->payload+RELAY_HEADER_SIZE,
- rh.length) < 0) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Can't parse extend cell. Closing circuit.");
- return -1;
- }
- if (!ec.orport_ipv4.port || tor_addr_is_null(&ec.orport_ipv4.addr)) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Client asked me to extend to zero destination port or addr.");
- return -1;
- }
- if (tor_addr_is_internal(&ec.orport_ipv4.addr, 0) &&
- !get_options()->ExtendAllowPrivateAddresses) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Client asked me to extend to a private address");
- return -1;
- }
- /* Check if they asked us for 0000..0000. We support using
- * an empty fingerprint for the first hop (e.g. for a bridge relay),
- * but we don't want to let people send us extend cells for empty
- * fingerprints -- a) because it opens the user up to a mitm attack,
- * and b) because it lets an attacker force the relay to hold open a
- * new TLS connection for each extend request. */
- if (tor_digest_is_zero((const char*)ec.node_id)) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Client asked me to extend without specifying an id_digest.");
- return -1;
- }
- /* Next, check if we're being asked to connect to the hop that the
- * extend cell came from. There isn't any reason for that, and it can
- * assist circular-path attacks. */
- if (tor_memeq(ec.node_id,
- TO_OR_CIRCUIT(circ)->p_chan->identity_digest,
- DIGEST_LEN)) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Client asked me to extend back to the previous hop.");
- return -1;
- }
- n_chan = channel_get_for_extend((const char*)ec.node_id,
- &ec.orport_ipv4.addr,
- &msg,
- &should_launch);
- if (!n_chan) {
- log_debug(LD_CIRC|LD_OR,"Next router (%s): %s",
- fmt_addrport(&ec.orport_ipv4.addr,ec.orport_ipv4.port),
- msg?msg:"????");
- circ->n_hop = extend_info_new(NULL /*nickname*/,
- (const char*)ec.node_id,
- NULL /*onion_key*/,
- NULL /*curve25519_key*/,
- &ec.orport_ipv4.addr,
- ec.orport_ipv4.port);
- circ->n_chan_create_cell = tor_memdup(&ec.create_cell,
- sizeof(ec.create_cell));
- circuit_set_state(circ, CIRCUIT_STATE_CHAN_WAIT);
- if (should_launch) {
- /* we should try to open a connection */
- n_chan = channel_connect_for_circuit(&ec.orport_ipv4.addr,
- ec.orport_ipv4.port,
- (const char*)ec.node_id);
- if (!n_chan) {
- log_info(LD_CIRC,"Launching n_chan failed. Closing circuit.");
- circuit_mark_for_close(circ, END_CIRC_REASON_CONNECTFAILED);
- return 0;
- }
- log_debug(LD_CIRC,"connecting in progress (or finished). Good.");
- }
- /* return success. The onion/circuit/etc will be taken care of
- * automatically (may already have been) whenever n_chan reaches
- * OR_CONN_STATE_OPEN.
- */
- return 0;
- }
- tor_assert(!circ->n_hop); /* Connection is already established. */
- circ->n_chan = n_chan;
- log_debug(LD_CIRC,
- "n_chan is %s",
- channel_get_canonical_remote_descr(n_chan));
- if (circuit_deliver_create_cell(circ, &ec.create_cell, 1) < 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, const char *key_data,
- int reverse)
- {
- crypto_digest_t *tmp_digest;
- crypto_cipher_t *tmp_crypto;
- tor_assert(cpath);
- tor_assert(key_data);
- tor_assert(!(cpath->f_crypto || cpath->b_crypto ||
- cpath->f_digest || cpath->b_digest));
- cpath->f_digest = crypto_digest_new();
- crypto_digest_add_bytes(cpath->f_digest, key_data, DIGEST_LEN);
- cpath->b_digest = crypto_digest_new();
- crypto_digest_add_bytes(cpath->b_digest, key_data+DIGEST_LEN, DIGEST_LEN);
- if (!(cpath->f_crypto =
- crypto_cipher_new(key_data+(2*DIGEST_LEN)))) {
- log_warn(LD_BUG,"Forward cipher initialization failed.");
- return -1;
- }
- if (!(cpath->b_crypto =
- crypto_cipher_new(key_data+(2*DIGEST_LEN)+CIPHER_KEY_LEN))) {
- log_warn(LD_BUG,"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;
- }
- /** The minimum number of circuit attempts before we start
- * thinking about warning about path bias and dropping guards */
- static int
- pathbias_get_min_circs(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_MIN_CIRC 150
- if (options->PathBiasCircThreshold >= 5)
- return options->PathBiasCircThreshold;
- else
- return networkstatus_get_param(NULL, "pb_mincircs",
- DFLT_PATH_BIAS_MIN_CIRC,
- 5, INT32_MAX);
- }
- /** The circuit success rate below which we issue a notice */
- static double
- pathbias_get_notice_rate(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_NOTICE_PCT 70
- if (options->PathBiasNoticeRate >= 0.0)
- return options->PathBiasNoticeRate;
- else
- return networkstatus_get_param(NULL, "pb_noticepct",
- DFLT_PATH_BIAS_NOTICE_PCT, 0, 100)/100.0;
- }
- /* XXXX024 I'd like to have this be static again, but entrynodes.c needs it. */
- /** The circuit success rate below which we issue a warn */
- static double
- pathbias_get_warn_rate(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_WARN_PCT 50
- if (options->PathBiasWarnRate >= 0.0)
- return options->PathBiasWarnRate;
- else
- return networkstatus_get_param(NULL, "pb_warnpct",
- DFLT_PATH_BIAS_WARN_PCT, 0, 100)/100.0;
- }
- /* XXXX024 I'd like to have this be static again, but entrynodes.c needs it. */
- /**
- * The extreme rate is the rate at which we would drop the guard,
- * if pb_dropguard is also set. Otherwise we just warn.
- */
- double
- pathbias_get_extreme_rate(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_EXTREME_PCT 30
- if (options->PathBiasExtremeRate >= 0.0)
- return options->PathBiasExtremeRate;
- else
- return networkstatus_get_param(NULL, "pb_extremepct",
- DFLT_PATH_BIAS_EXTREME_PCT, 0, 100)/100.0;
- }
- /* XXXX024 I'd like to have this be static again, but entrynodes.c needs it. */
- /**
- * If 1, we actually disable use of guards that fall below
- * the extreme_pct.
- */
- int
- pathbias_get_dropguards(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_DROP_GUARDS 0
- if (options->PathBiasDropGuards >= 0)
- return options->PathBiasDropGuards;
- else
- return networkstatus_get_param(NULL, "pb_dropguards",
- DFLT_PATH_BIAS_DROP_GUARDS, 0, 1);
- }
- /**
- * This is the number of circuits at which we scale our
- * counts by mult_factor/scale_factor. Note, this count is
- * not exact, as we only perform the scaling in the event
- * of no integer truncation.
- */
- static int
- pathbias_get_scale_threshold(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_SCALE_THRESHOLD 300
- if (options->PathBiasScaleThreshold >= 10)
- return options->PathBiasScaleThreshold;
- else
- return networkstatus_get_param(NULL, "pb_scalecircs",
- DFLT_PATH_BIAS_SCALE_THRESHOLD, 10,
- INT32_MAX);
- }
- /**
- * Compute the path bias scaling ratio from the consensus
- * parameters pb_multfactor/pb_scalefactor.
- *
- * Returns a value in (0, 1.0] which we multiply our pathbias
- * counts with to scale them down.
- */
- static double
- pathbias_get_scale_ratio(const or_options_t *options)
- {
- /*
- * The scale factor is the denominator for our scaling
- * of circuit counts for our path bias window.
- *
- * Note that our use of doubles for the path bias state
- * file means that powers of 2 work best here.
- */
- int denominator = networkstatus_get_param(NULL, "pb_scalefactor",
- 2, 2, INT32_MAX);
- (void) options;
- /**
- * The mult factor is the numerator for our scaling
- * of circuit counts for our path bias window. It
- * allows us to scale by fractions.
- */
- return networkstatus_get_param(NULL, "pb_multfactor",
- 1, 1, denominator)/((double)denominator);
- }
- /** The minimum number of circuit usage attempts before we start
- * thinking about warning about path use bias and dropping guards */
- static int
- pathbias_get_min_use(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_MIN_USE 20
- if (options->PathBiasUseThreshold >= 3)
- return options->PathBiasUseThreshold;
- else
- return networkstatus_get_param(NULL, "pb_minuse",
- DFLT_PATH_BIAS_MIN_USE,
- 3, INT32_MAX);
- }
- /** The circuit use success rate below which we issue a notice */
- static double
- pathbias_get_notice_use_rate(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_NOTICE_USE_PCT 80
- if (options->PathBiasNoticeUseRate >= 0.0)
- return options->PathBiasNoticeUseRate;
- else
- return networkstatus_get_param(NULL, "pb_noticeusepct",
- DFLT_PATH_BIAS_NOTICE_USE_PCT,
- 0, 100)/100.0;
- }
- /**
- * The extreme use rate is the rate at which we would drop the guard,
- * if pb_dropguard is also set. Otherwise we just warn.
- */
- double
- pathbias_get_extreme_use_rate(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_EXTREME_USE_PCT 60
- if (options->PathBiasExtremeUseRate >= 0.0)
- return options->PathBiasExtremeUseRate;
- else
- return networkstatus_get_param(NULL, "pb_extremeusepct",
- DFLT_PATH_BIAS_EXTREME_USE_PCT,
- 0, 100)/100.0;
- }
- /**
- * This is the number of circuits at which we scale our
- * use counts by mult_factor/scale_factor. Note, this count is
- * not exact, as we only perform the scaling in the event
- * of no integer truncation.
- */
- static int
- pathbias_get_scale_use_threshold(const or_options_t *options)
- {
- #define DFLT_PATH_BIAS_SCALE_USE_THRESHOLD 100
- if (options->PathBiasScaleUseThreshold >= 10)
- return options->PathBiasScaleUseThreshold;
- else
- return networkstatus_get_param(NULL, "pb_scaleuse",
- DFLT_PATH_BIAS_SCALE_USE_THRESHOLD,
- 10, INT32_MAX);
- }
- /**
- * Convert a Guard's path state to string.
- */
- const char *
- pathbias_state_to_string(path_state_t state)
- {
- switch (state) {
- case PATH_STATE_NEW_CIRC:
- return "new";
- case PATH_STATE_BUILD_ATTEMPTED:
- return "build attempted";
- case PATH_STATE_BUILD_SUCCEEDED:
- return "build succeeded";
- case PATH_STATE_USE_ATTEMPTED:
- return "use attempted";
- case PATH_STATE_USE_SUCCEEDED:
- return "use succeeded";
- case PATH_STATE_USE_FAILED:
- return "use failed";
- case PATH_STATE_ALREADY_COUNTED:
- return "already counted";
- }
- return "unknown";
- }
- /**
- * This function decides if a circuit has progressed far enough to count
- * as a circuit "attempt". As long as end-to-end tagging is possible,
- * we assume the adversary will use it over hop-to-hop failure. Therefore,
- * we only need to account bias for the last hop. This should make us
- * much more resilient to ambient circuit failure, and also make that
- * failure easier to measure (we only need to measure Exit failure rates).
- */
- static int
- pathbias_is_new_circ_attempt(origin_circuit_t *circ)
- {
- #define N2N_TAGGING_IS_POSSIBLE
- #ifdef N2N_TAGGING_IS_POSSIBLE
- /* cpath is a circular list. We want circs with more than one hop,
- * and the second hop must be waiting for keys still (it's just
- * about to get them). */
- return circ->cpath &&
- circ->cpath->next != circ->cpath &&
- circ->cpath->next->state == CPATH_STATE_AWAITING_KEYS;
- #else
- /* If tagging attacks are no longer possible, we probably want to
- * count bias from the first hop. However, one could argue that
- * timing-based tagging is still more useful than per-hop failure.
- * In which case, we'd never want to use this.
- */
- return circ->cpath &&
- circ->cpath->state == CPATH_STATE_AWAITING_KEYS;
- #endif
- }
- /**
- * Decide if the path bias code should count a circuit.
- *
- * @returns 1 if we should count it, 0 otherwise.
- */
- static int
- pathbias_should_count(origin_circuit_t *circ)
- {
- #define PATHBIAS_COUNT_INTERVAL (600)
- static ratelim_t count_limit =
- RATELIM_INIT(PATHBIAS_COUNT_INTERVAL);
- char *rate_msg = NULL;
- /* We can't do path bias accounting without entry guards.
- * Testing and controller circuits also have no guards.
- *
- * We also don't count server-side rends, because their
- * endpoint could be chosen maliciously.
- * Similarly, we can't count client-side intro attempts,
- * because clients can be manipulated into connecting to
- * malicious intro points. */
- if (get_options()->UseEntryGuards == 0 ||
- circ->base_.purpose == CIRCUIT_PURPOSE_TESTING ||
- circ->base_.purpose == CIRCUIT_PURPOSE_CONTROLLER ||
- circ->base_.purpose == CIRCUIT_PURPOSE_S_CONNECT_REND ||
- circ->base_.purpose == CIRCUIT_PURPOSE_S_REND_JOINED ||
- (circ->base_.purpose >= CIRCUIT_PURPOSE_C_INTRODUCING &&
- circ->base_.purpose <= CIRCUIT_PURPOSE_C_INTRODUCE_ACKED)) {
- /* Check to see if the shouldcount result has changed due to a
- * unexpected purpose change that would affect our results.
- *
- * The reason we check the path state too here is because for the
- * cannibalized versions of these purposes, we count them as successful
- * before their purpose change.
- */
- if (circ->pathbias_shouldcount == PATHBIAS_SHOULDCOUNT_COUNTED
- && circ->path_state != PATH_STATE_ALREADY_COUNTED) {
- log_info(LD_BUG,
- "Circuit %d is now being ignored despite being counted "
- "in the past. Purpose is %s, path state is %s",
- circ->global_identifier,
- circuit_purpose_to_string(circ->base_.purpose),
- pathbias_state_to_string(circ->path_state));
- }
- circ->pathbias_shouldcount = PATHBIAS_SHOULDCOUNT_IGNORED;
- return 0;
- }
- /* Completely ignore one hop circuits */
- if (circ->build_state->onehop_tunnel ||
- circ->build_state->desired_path_len == 1) {
- /* Check for inconsistency */
- if (circ->build_state->desired_path_len != 1 ||
- !circ->build_state->onehop_tunnel) {
- if ((rate_msg = rate_limit_log(&count_limit, approx_time()))) {
- log_info(LD_BUG,
- "One-hop circuit has length %d. Path state is %s. "
- "Circuit is a %s currently %s.%s",
- circ->build_state->desired_path_len,
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state),
- rate_msg);
- tor_free(rate_msg);
- }
- tor_fragile_assert();
- }
- /* Check to see if the shouldcount result has changed due to a
- * unexpected change that would affect our results */
- if (circ->pathbias_shouldcount == PATHBIAS_SHOULDCOUNT_COUNTED) {
- log_info(LD_BUG,
- "One-hop circuit %d is now being ignored despite being counted "
- "in the past. Purpose is %s, path state is %s",
- circ->global_identifier,
- circuit_purpose_to_string(circ->base_.purpose),
- pathbias_state_to_string(circ->path_state));
- }
- circ->pathbias_shouldcount = PATHBIAS_SHOULDCOUNT_IGNORED;
- return 0;
- }
- /* Check to see if the shouldcount result has changed due to a
- * unexpected purpose change that would affect our results */
- if (circ->pathbias_shouldcount == PATHBIAS_SHOULDCOUNT_IGNORED) {
- log_info(LD_BUG,
- "Circuit %d is now being counted despite being ignored "
- "in the past. Purpose is %s, path state is %s",
- circ->global_identifier,
- circuit_purpose_to_string(circ->base_.purpose),
- pathbias_state_to_string(circ->path_state));
- }
- circ->pathbias_shouldcount = PATHBIAS_SHOULDCOUNT_COUNTED;
- return 1;
- }
- /**
- * Check our circuit state to see if this is a successful circuit attempt.
- * If so, record it in the current guard's path bias circ_attempt count.
- *
- * Also check for several potential error cases for bug #6475.
- */
- static int
- pathbias_count_build_attempt(origin_circuit_t *circ)
- {
- #define CIRC_ATTEMPT_NOTICE_INTERVAL (600)
- static ratelim_t circ_attempt_notice_limit =
- RATELIM_INIT(CIRC_ATTEMPT_NOTICE_INTERVAL);
- char *rate_msg = NULL;
- if (!pathbias_should_count(circ)) {
- return 0;
- }
- if (pathbias_is_new_circ_attempt(circ)) {
- /* Help track down the real cause of bug #6475: */
- if (circ->has_opened && circ->path_state != PATH_STATE_BUILD_ATTEMPTED) {
- if ((rate_msg = rate_limit_log(&circ_attempt_notice_limit,
- approx_time()))) {
- log_info(LD_BUG,
- "Opened circuit is in strange path state %s. "
- "Circuit is a %s currently %s.%s",
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state),
- rate_msg);
- tor_free(rate_msg);
- }
- }
- /* Don't re-count cannibalized circs.. */
- if (!circ->has_opened) {
- entry_guard_t *guard = NULL;
- if (circ->cpath && circ->cpath->extend_info) {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- } else if (circ->base_.n_chan) {
- guard =
- entry_guard_get_by_id_digest(circ->base_.n_chan->identity_digest);
- }
- if (guard) {
- if (circ->path_state == PATH_STATE_NEW_CIRC) {
- circ->path_state = PATH_STATE_BUILD_ATTEMPTED;
- if (entry_guard_inc_circ_attempt_count(guard) < 0) {
- /* Bogus guard; we already warned. */
- return -END_CIRC_REASON_TORPROTOCOL;
- }
- } else {
- if ((rate_msg = rate_limit_log(&circ_attempt_notice_limit,
- approx_time()))) {
- log_info(LD_BUG,
- "Unopened circuit has strange path state %s. "
- "Circuit is a %s currently %s.%s",
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state),
- rate_msg);
- tor_free(rate_msg);
- }
- }
- } else {
- if ((rate_msg = rate_limit_log(&circ_attempt_notice_limit,
- approx_time()))) {
- log_info(LD_CIRC,
- "Unopened circuit has no known guard. "
- "Circuit is a %s currently %s.%s",
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state),
- rate_msg);
- tor_free(rate_msg);
- }
- }
- }
- }
- return 0;
- }
- /**
- * Check our circuit state to see if this is a successful circuit
- * completion. If so, record it in the current guard's path bias
- * success count.
- *
- * Also check for several potential error cases for bug #6475.
- */
- static void
- pathbias_count_build_success(origin_circuit_t *circ)
- {
- #define SUCCESS_NOTICE_INTERVAL (600)
- static ratelim_t success_notice_limit =
- RATELIM_INIT(SUCCESS_NOTICE_INTERVAL);
- char *rate_msg = NULL;
- entry_guard_t *guard = NULL;
- if (!pathbias_should_count(circ)) {
- return;
- }
- /* Don't count cannibalized/reused circs for path bias
- * "build" success, since they get counted under "use" success. */
- if (!circ->has_opened) {
- if (circ->cpath && circ->cpath->extend_info) {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- }
- if (guard) {
- if (circ->path_state == PATH_STATE_BUILD_ATTEMPTED) {
- circ->path_state = PATH_STATE_BUILD_SUCCEEDED;
- guard->circ_successes++;
- entry_guards_changed();
- log_info(LD_CIRC, "Got success count %f/%f for guard %s ($%s)",
- guard->circ_successes, guard->circ_attempts,
- guard->nickname, hex_str(guard->identity, DIGEST_LEN));
- } else {
- if ((rate_msg = rate_limit_log(&success_notice_limit,
- approx_time()))) {
- log_info(LD_BUG,
- "Succeeded circuit is in strange path state %s. "
- "Circuit is a %s currently %s.%s",
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state),
- rate_msg);
- tor_free(rate_msg);
- }
- }
- if (guard->circ_attempts < guard->circ_successes) {
- log_notice(LD_BUG, "Unexpectedly high successes counts (%f/%f) "
- "for guard %s ($%s)",
- guard->circ_successes, guard->circ_attempts,
- guard->nickname, hex_str(guard->identity, DIGEST_LEN));
- }
- /* In rare cases, CIRCUIT_PURPOSE_TESTING can get converted to
- * CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT and have no guards here.
- * No need to log that case. */
- } else if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
- if ((rate_msg = rate_limit_log(&success_notice_limit,
- approx_time()))) {
- log_info(LD_CIRC,
- "Completed circuit has no known guard. "
- "Circuit is a %s currently %s.%s",
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state),
- rate_msg);
- tor_free(rate_msg);
- }
- }
- } else {
- if (circ->path_state < PATH_STATE_BUILD_SUCCEEDED) {
- if ((rate_msg = rate_limit_log(&success_notice_limit,
- approx_time()))) {
- log_info(LD_BUG,
- "Opened circuit is in strange path state %s. "
- "Circuit is a %s currently %s.%s",
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state),
- rate_msg);
- tor_free(rate_msg);
- }
- }
- }
- }
- /**
- * Record an attempt to use a circuit. Changes the circuit's
- * path state and update its guard's usage counter.
- *
- * Used for path bias usage accounting.
- */
- void
- pathbias_count_use_attempt(origin_circuit_t *circ)
- {
- entry_guard_t *guard;
- if (!pathbias_should_count(circ)) {
- return;
- }
- if (circ->path_state < PATH_STATE_BUILD_SUCCEEDED) {
- log_notice(LD_BUG,
- "Used circuit is in strange path state %s. "
- "Circuit is a %s currently %s.",
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state));
- } else if (circ->path_state < PATH_STATE_USE_ATTEMPTED) {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- if (guard) {
- pathbias_measure_use_rate(guard);
- pathbias_scale_use_rates(guard);
- guard->use_attempts++;
- entry_guards_changed();
- log_debug(LD_CIRC,
- "Marked circuit %d (%f/%f) as used for guard %s ($%s).",
- circ->global_identifier,
- guard->use_successes, guard->use_attempts,
- guard->nickname, hex_str(guard->identity, DIGEST_LEN));
- }
- circ->path_state = PATH_STATE_USE_ATTEMPTED;
- } else {
- /* Harmless but educational log message */
- log_info(LD_CIRC,
- "Used circuit %d is already in path state %s. "
- "Circuit is a %s currently %s.",
- circ->global_identifier,
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state));
- }
- return;
- }
- /**
- * Check the circuit's path state is appropriate and mark it as
- * successfully used. Used for path bias usage accounting.
- *
- * We don't actually increment the guard's counters until
- * pathbias_check_close(), because the circuit can still transition
- * back to PATH_STATE_USE_ATTEMPTED if a stream fails later (this
- * is done so we can probe the circuit for liveness at close).
- */
- void
- pathbias_mark_use_success(origin_circuit_t *circ)
- {
- if (!pathbias_should_count(circ)) {
- return;
- }
- if (circ->path_state < PATH_STATE_USE_ATTEMPTED) {
- log_notice(LD_BUG,
- "Used circuit %d is in strange path state %s. "
- "Circuit is a %s currently %s.",
- circ->global_identifier,
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state));
- pathbias_count_use_attempt(circ);
- }
- /* We don't do any accounting at the guard until actual circuit close */
- circ->path_state = PATH_STATE_USE_SUCCEEDED;
- return;
- }
- /**
- * If a stream ever detatches from a circuit in a retriable way,
- * we need to mark this circuit as still needing either another
- * successful stream, or in need of a probe.
- *
- * An adversary could let the first stream request succeed (ie the
- * resolve), but then tag and timeout the remainder (via cell
- * dropping), forcing them on new circuits.
- *
- * Rolling back the state will cause us to probe such circuits, which
- * should lead to probe failures in the event of such tagging due to
- * either unrecognized cells coming in while we wait for the probe,
- * or the cipher state getting out of sync in the case of dropped cells.
- */
- void
- pathbias_mark_use_rollback(origin_circuit_t *circ)
- {
- if (circ->path_state == PATH_STATE_USE_SUCCEEDED) {
- log_info(LD_CIRC,
- "Rolling back pathbias use state to 'attempted' for detached "
- "circuit %d", circ->global_identifier);
- circ->path_state = PATH_STATE_USE_ATTEMPTED;
- }
- }
- /**
- * Actually count a circuit success towards a guard's usage counters
- * if the path state is appropriate.
- */
- static void
- pathbias_count_use_success(origin_circuit_t *circ)
- {
- entry_guard_t *guard;
- if (!pathbias_should_count(circ)) {
- return;
- }
- if (circ->path_state != PATH_STATE_USE_SUCCEEDED) {
- log_notice(LD_BUG,
- "Successfully used circuit %d is in strange path state %s. "
- "Circuit is a %s currently %s.",
- circ->global_identifier,
- pathbias_state_to_string(circ->path_state),
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state));
- } else {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- if (guard) {
- guard->use_successes++;
- entry_guards_changed();
- if (guard->use_attempts < guard->use_successes) {
- log_notice(LD_BUG, "Unexpectedly high use successes counts (%f/%f) "
- "for guard %s=%s",
- guard->use_successes, guard->use_attempts,
- guard->nickname, hex_str(guard->identity, DIGEST_LEN));
- }
- log_debug(LD_CIRC,
- "Marked circuit %d (%f/%f) as used successfully for guard "
- "%s ($%s).",
- circ->global_identifier, guard->use_successes,
- guard->use_attempts, guard->nickname,
- hex_str(guard->identity, DIGEST_LEN));
- }
- }
- return;
- }
- /**
- * Send a probe down a circuit that the client attempted to use,
- * but for which the stream timed out/failed. The probe is a
- * RELAY_BEGIN cell with a 0.a.b.c destination address, which
- * the exit will reject and reply back, echoing that address.
- *
- * The reason for such probes is because it is possible to bias
- * a user's paths simply by causing timeouts, and these timeouts
- * are not possible to differentiate from unresponsive servers.
- *
- * The probe is sent at the end of the circuit lifetime for two
- * reasons: to prevent cryptographic taggers from being able to
- * drop cells to cause timeouts, and to prevent easy recognition
- * of probes before any real client traffic happens.
- *
- * Returns -1 if we couldn't probe, 0 otherwise.
- */
- static int
- pathbias_send_usable_probe(circuit_t *circ)
- {
- /* Based on connection_ap_handshake_send_begin() */
- char payload[CELL_PAYLOAD_SIZE];
- int payload_len;
- origin_circuit_t *ocirc = TO_ORIGIN_CIRCUIT(circ);
- crypt_path_t *cpath_layer = NULL;
- char *probe_nonce = NULL;
- tor_assert(ocirc);
- cpath_layer = ocirc->cpath->prev;
- if (cpath_layer->state != CPATH_STATE_OPEN) {
- /* This can happen for cannibalized circuits. Their
- * last hop isn't yet open */
- log_info(LD_CIRC,
- "Got pathbias probe request for unopened circuit %d. "
- "Opened %d, len %d", ocirc->global_identifier,
- ocirc->has_opened, ocirc->build_state->desired_path_len);
- return -1;
- }
- /* We already went down this road. */
- if (circ->purpose == CIRCUIT_PURPOSE_PATH_BIAS_TESTING &&
- ocirc->pathbias_probe_id) {
- log_info(LD_CIRC,
- "Got pathbias probe request for circuit %d with "
- "outstanding probe", ocirc->global_identifier);
- return -1;
- }
- /* Can't probe if the channel isn't open */
- if (circ->n_chan == NULL ||
- (circ->n_chan->state != CHANNEL_STATE_OPEN
- && circ->n_chan->state != CHANNEL_STATE_MAINT)) {
- log_info(LD_CIRC,
- "Skipping pathbias probe for circuit %d: Channel is not open.",
- ocirc->global_identifier);
- return -1;
- }
- circuit_change_purpose(circ, CIRCUIT_PURPOSE_PATH_BIAS_TESTING);
- /* Update timestamp for when circuit_expire_building() should kill us */
- tor_gettimeofday(&circ->timestamp_began);
- /* Generate a random address for the nonce */
- crypto_rand((char*)ô->pathbias_probe_nonce,
- sizeof(ocirc->pathbias_probe_nonce));
- ocirc->pathbias_probe_nonce &= 0x00ffffff;
- probe_nonce = tor_dup_ip(ocirc->pathbias_probe_nonce);
- tor_snprintf(payload,RELAY_PAYLOAD_SIZE, "%s:25", probe_nonce);
- payload_len = (int)strlen(payload)+1;
- // XXX: need this? Can we assume ipv4 will always be supported?
- // If not, how do we tell?
- //if (payload_len <= RELAY_PAYLOAD_SIZE - 4 && edge_conn->begincell_flags) {
- // set_uint32(payload + payload_len, htonl(edge_conn->begincell_flags));
- // payload_len += 4;
- //}
- /* Generate+Store stream id, make sure it's non-zero */
- ocirc->pathbias_probe_id = get_unique_stream_id_by_circ(ocirc);
- if (ocirc->pathbias_probe_id==0) {
- log_warn(LD_CIRC,
- "Ran out of stream IDs on circuit %u during "
- "pathbias probe attempt.", ocirc->global_identifier);
- tor_free(probe_nonce);
- return -1;
- }
- log_info(LD_CIRC,
- "Sending pathbias testing cell to %s:25 on stream %d for circ %d.",
- probe_nonce, ocirc->pathbias_probe_id, ocirc->global_identifier);
- tor_free(probe_nonce);
- /* Send a test relay cell */
- if (relay_send_command_from_edge(ocirc->pathbias_probe_id, circ,
- RELAY_COMMAND_BEGIN, payload,
- payload_len, cpath_layer) < 0) {
- log_notice(LD_CIRC,
- "Failed to send pathbias probe cell on circuit %d.",
- ocirc->global_identifier);
- return -1;
- }
- /* Mark it freshly dirty so it doesn't get expired in the meantime */
- circ->timestamp_dirty = time(NULL);
- return 0;
- }
- /**
- * Check the response to a pathbias probe, to ensure the
- * cell is recognized and the nonce and other probe
- * characteristics are as expected.
- *
- * If the response is valid, return 0. Otherwise return < 0.
- */
- int
- pathbias_check_probe_response(circuit_t *circ, const cell_t *cell)
- {
- /* Based on connection_edge_process_relay_cell() */
- relay_header_t rh;
- int reason;
- uint32_t ipv4_host;
- origin_circuit_t *ocirc = TO_ORIGIN_CIRCUIT(circ);
- tor_assert(cell);
- tor_assert(ocirc);
- tor_assert(circ->purpose == CIRCUIT_PURPOSE_PATH_BIAS_TESTING);
- relay_header_unpack(&rh, cell->payload);
- reason = rh.length > 0 ?
- get_uint8(cell->payload+RELAY_HEADER_SIZE) : END_STREAM_REASON_MISC;
- if (rh.command == RELAY_COMMAND_END &&
- reason == END_STREAM_REASON_EXITPOLICY &&
- ocirc->pathbias_probe_id == rh.stream_id) {
- /* Check length+extract host: It is in network order after the reason code.
- * See connection_edge_end(). */
- if (rh.length < 9) { /* reason+ipv4+dns_ttl */
- log_notice(LD_PROTOCOL,
- "Short path bias probe response length field (%d).", rh.length);
- return - END_CIRC_REASON_TORPROTOCOL;
- }
- ipv4_host = ntohl(get_uint32(cell->payload+RELAY_HEADER_SIZE+1));
- /* Check nonce */
- if (ipv4_host == ocirc->pathbias_probe_nonce) {
- pathbias_mark_use_success(ocirc);
- circuit_mark_for_close(circ, END_CIRC_REASON_FINISHED);
- log_info(LD_CIRC,
- "Got valid path bias probe back for circ %d, stream %d.",
- ocirc->global_identifier, ocirc->pathbias_probe_id);
- return 0;
- } else {
- log_notice(LD_CIRC,
- "Got strange probe value 0x%x vs 0x%x back for circ %d, "
- "stream %d.", ipv4_host, ocirc->pathbias_probe_nonce,
- ocirc->global_identifier, ocirc->pathbias_probe_id);
- return -1;
- }
- }
- log_info(LD_CIRC,
- "Got another cell back back on pathbias probe circuit %d: "
- "Command: %d, Reason: %d, Stream-id: %d",
- ocirc->global_identifier, rh.command, reason, rh.stream_id);
- return -1;
- }
- /**
- * Check if a circuit was used and/or closed successfully.
- *
- * If we attempted to use the circuit to carry a stream but failed
- * for whatever reason, or if the circuit mysteriously died before
- * we could attach any streams, record these two cases.
- *
- * If we *have* successfully used the circuit, or it appears to
- * have been closed by us locally, count it as a success.
- *
- * Returns 0 if we're done making decisions with the circ,
- * or -1 if we want to probe it first.
- */
- int
- pathbias_check_close(origin_circuit_t *ocirc, int reason)
- {
- circuit_t *circ = ô->base_;
- if (!pathbias_should_count(ocirc)) {
- return 0;
- }
- switch (ocirc->path_state) {
- /* If the circuit was closed after building, but before use, we need
- * to ensure we were the ones who tried to close it (and not a remote
- * actor). */
- case PATH_STATE_BUILD_SUCCEEDED:
- if (reason & END_CIRC_REASON_FLAG_REMOTE) {
- /* Remote circ close reasons on an unused circuit all could be bias */
- log_info(LD_CIRC,
- "Circuit %d remote-closed without successful use for reason %d. "
- "Circuit purpose %d currently %d,%s. Len %d.",
- ocirc->global_identifier,
- reason, circ->purpose, ocirc->has_opened,
- circuit_state_to_string(circ->state),
- ocirc->build_state->desired_path_len);
- pathbias_count_collapse(ocirc);
- } else if ((reason & ~END_CIRC_REASON_FLAG_REMOTE)
- == END_CIRC_REASON_CHANNEL_CLOSED &&
- circ->n_chan &&
- circ->n_chan->reason_for_closing
- != CHANNEL_CLOSE_REQUESTED) {
- /* If we didn't close the channel ourselves, it could be bias */
- /* XXX: Only count bias if the network is live?
- * What about clock jumps/suspends? */
- log_info(LD_CIRC,
- "Circuit %d's channel closed without successful use for reason "
- "%d, channel reason %d. Circuit purpose %d currently %d,%s. Len "
- "%d.", ocirc->global_identifier,
- reason, circ->n_chan->reason_for_closing,
- circ->purpose, ocirc->has_opened,
- circuit_state_to_string(circ->state),
- ocirc->build_state->desired_path_len);
- pathbias_count_collapse(ocirc);
- } else {
- pathbias_count_successful_close(ocirc);
- }
- break;
- /* If we tried to use a circuit but failed, we should probe it to ensure
- * it has not been tampered with. */
- case PATH_STATE_USE_ATTEMPTED:
- /* XXX: Only probe and/or count failure if the network is live?
- * What about clock jumps/suspends? */
- if (pathbias_send_usable_probe(circ) == 0)
- return -1;
- else
- pathbias_count_use_failed(ocirc);
- /* Any circuit where there were attempted streams but no successful
- * streams could be bias */
- log_info(LD_CIRC,
- "Circuit %d closed without successful use for reason %d. "
- "Circuit purpose %d currently %d,%s. Len %d.",
- ocirc->global_identifier,
- reason, circ->purpose, ocirc->has_opened,
- circuit_state_to_string(circ->state),
- ocirc->build_state->desired_path_len);
- break;
- case PATH_STATE_USE_SUCCEEDED:
- pathbias_count_successful_close(ocirc);
- pathbias_count_use_success(ocirc);
- break;
- case PATH_STATE_USE_FAILED:
- pathbias_count_use_failed(ocirc);
- break;
- case PATH_STATE_NEW_CIRC:
- case PATH_STATE_BUILD_ATTEMPTED:
- case PATH_STATE_ALREADY_COUNTED:
- default:
- // Other states are uninteresting. No stats to count.
- break;
- }
- ocirc->path_state = PATH_STATE_ALREADY_COUNTED;
- return 0;
- }
- /**
- * Count a successfully closed circuit.
- */
- static void
- pathbias_count_successful_close(origin_circuit_t *circ)
- {
- entry_guard_t *guard = NULL;
- if (!pathbias_should_count(circ)) {
- return;
- }
- if (circ->cpath && circ->cpath->extend_info) {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- }
- if (guard) {
- /* In the long run: circuit_success ~= successful_circuit_close +
- * circ_failure + stream_failure */
- guard->successful_circuits_closed++;
- entry_guards_changed();
- } else if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
- /* In rare cases, CIRCUIT_PURPOSE_TESTING can get converted to
- * CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT and have no guards here.
- * No need to log that case. */
- log_info(LD_CIRC,
- "Successfully closed circuit has no known guard. "
- "Circuit is a %s currently %s",
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state));
- }
- }
- /**
- * Count a circuit that fails after it is built, but before it can
- * carry any traffic.
- *
- * This is needed because there are ways to destroy a
- * circuit after it has successfully completed. Right now, this is
- * used for purely informational/debugging purposes.
- */
- static void
- pathbias_count_collapse(origin_circuit_t *circ)
- {
- entry_guard_t *guard = NULL;
- if (!pathbias_should_count(circ)) {
- return;
- }
- if (circ->cpath && circ->cpath->extend_info) {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- }
- if (guard) {
- guard->collapsed_circuits++;
- entry_guards_changed();
- } else if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
- /* In rare cases, CIRCUIT_PURPOSE_TESTING can get converted to
- * CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT and have no guards here.
- * No need to log that case. */
- log_info(LD_CIRC,
- "Destroyed circuit has no known guard. "
- "Circuit is a %s currently %s",
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state));
- }
- }
- /**
- * Count a known failed circuit (because we could not probe it).
- *
- * This counter is informational.
- */
- static void
- pathbias_count_use_failed(origin_circuit_t *circ)
- {
- entry_guard_t *guard = NULL;
- if (!pathbias_should_count(circ)) {
- return;
- }
- if (circ->cpath && circ->cpath->extend_info) {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- }
- if (guard) {
- guard->unusable_circuits++;
- entry_guards_changed();
- } else if (circ->base_.purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
- /* In rare cases, CIRCUIT_PURPOSE_TESTING can get converted to
- * CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT and have no guards here.
- * No need to log that case. */
- /* XXX note cut-and-paste code in this function compared to nearby
- * functions. Would be nice to refactor. -RD */
- log_info(LD_CIRC,
- "Stream-failing circuit has no known guard. "
- "Circuit is a %s currently %s",
- circuit_purpose_to_string(circ->base_.purpose),
- circuit_state_to_string(circ->base_.state));
- }
- }
- /**
- * Count timeouts for path bias log messages.
- *
- * These counts are purely informational.
- */
- void
- pathbias_count_timeout(origin_circuit_t *circ)
- {
- entry_guard_t *guard = NULL;
- if (!pathbias_should_count(circ)) {
- return;
- }
- /* For hidden service circs, they can actually be used
- * successfully and then time out later (because
- * the other side declines to use them). */
- if (circ->path_state == PATH_STATE_USE_SUCCEEDED) {
- return;
- }
- if (circ->cpath && circ->cpath->extend_info) {
- guard = entry_guard_get_by_id_digest(
- circ->cpath->extend_info->identity_digest);
- }
- if (guard) {
- guard->timeouts++;
- entry_guards_changed();
- }
- }
- /**
- * Helper function to count all of the currently opened circuits
- * for a guard that are in a given path state range. The state
- * range is inclusive on both ends.
- */
- static int
- pathbias_count_circs_in_states(entry_guard_t *guard,
- path_state_t from,
- path_state_t to)
- {
- circuit_t *circ;
- int open_circuits = 0;
- /* Count currently open circuits. Give them the benefit of the doubt. */
- TOR_LIST_FOREACH(circ, circuit_get_global_list(), head) {
- origin_circuit_t *ocirc = NULL;
- if (!CIRCUIT_IS_ORIGIN(circ) || /* didn't originate here */
- circ->marked_for_close) /* already counted */
- continue;
- ocirc = TO_ORIGIN_CIRCUIT(circ);
- if (!ocirc->cpath || !ocirc->cpath->extend_info)
- continue;
- if (ocirc->path_state >= from &&
- ocirc->path_state <= to &&
- pathbias_should_count(ocirc) &&
- fast_memeq(guard->identity,
- ocirc->cpath->extend_info->identity_digest,
- DIGEST_LEN)) {
- log_debug(LD_CIRC, "Found opened circuit %d in path_state %s",
- ocirc->global_identifier,
- pathbias_state_to_string(ocirc->path_state));
- open_circuits++;
- }
- }
- return open_circuits;
- }
- /**
- * Return the number of circuits counted as successfully closed for
- * this guard.
- *
- * Also add in the currently open circuits to give them the benefit
- * of the doubt.
- */
- double
- pathbias_get_close_success_count(entry_guard_t *guard)
- {
- return guard->successful_circuits_closed +
- pathbias_count_circs_in_states(guard,
- PATH_STATE_BUILD_SUCCEEDED,
- PATH_STATE_USE_SUCCEEDED);
- }
- /**
- * Return the number of circuits counted as successfully used
- * this guard.
- *
- * Also add in the currently open circuits that we are attempting
- * to use to give them the benefit of the doubt.
- */
- double
- pathbias_get_use_success_count(entry_guard_t *guard)
- {
- return guard->use_successes +
- pathbias_count_circs_in_states(guard,
- PATH_STATE_USE_ATTEMPTED,
- PATH_STATE_USE_SUCCEEDED);
- }
- /**
- * Check the path bias use rate against our consensus parameter limits.
- *
- * Emits a log message if the use success rates are too low.
- *
- * If pathbias_get_dropguards() is set, we also disable the use of
- * very failure prone guards.
- */
- static void
- pathbias_measure_use_rate(entry_guard_t *guard)
- {
- const or_options_t *options = get_options();
- if (guard->use_attempts > pathbias_get_min_use(options)) {
- /* Note: We rely on the < comparison here to allow us to set a 0
- * rate and disable the feature entirely. If refactoring, don't
- * change to <= */
- if (pathbias_get_use_success_count(guard)/guard->use_attempts
- < pathbias_get_extreme_use_rate(options)) {
- /* Dropping is currently disabled by default. */
- if (pathbias_get_dropguards(options)) {
- if (!guard->path_bias_disabled) {
- log_warn(LD_CIRC,
- "Your Guard %s ($%s) is failing to carry an extremely large "
- "amount of stream on its circuits. "
- "To avoid potential route manipulation attacks, Tor has "
- "disabled use of this guard. "
- "Use counts are %ld/%ld. Success counts are %ld/%ld. "
- "%ld circuits completed, %ld were unusable, %ld collapsed, "
- "and %ld timed out. "
- "For reference, your timeout cutoff is %ld seconds.",
- guard->nickname, hex_str(guard->identity, DIGEST_LEN),
- tor_lround(pathbias_get_use_success_count(guard)),
- tor_lround(guard->use_attempts),
- tor_lround(pathbias_get_close_success_count(guard)),
- tor_lround(guard->circ_attempts),
- tor_lround(guard->circ_successes),
- tor_lround(guard->unusable_circuits),
- tor_lround(guard->collapsed_circuits),
- tor_lround(guard->timeouts),
- tor_lround(get_circuit_build_close_time_ms()/1000));
- guard->path_bias_disabled = 1;
- guard->bad_since = approx_time();
- entry_guards_changed();
- return;
- }
- } else if (!guard->path_bias_use_extreme) {
- guard->path_bias_use_extreme = 1;
- log_warn(LD_CIRC,
- "Your Guard %s ($%s) is failing to carry an extremely large "
- "amount of streams on its circuits. "
- "This could indicate a route manipulation attack, network "
- "overload, bad local network connectivity, or a bug. "
- "Use counts are %ld/%ld. Success counts are %ld/%ld. "
- "%ld circuits completed, %ld were unusable, %ld collapsed, "
- "and %ld timed out. "
- "For reference, your timeout cutoff is %ld seconds.",
- guard->nickname, hex_str(guard->identity, DIGEST_LEN),
- tor_lround(pathbias_get_use_success_count(guard)),
- tor_lround(guard->use_attempts),
- tor_lround(pathbias_get_close_success_count(guard)),
- tor_lround(guard->circ_attempts),
- tor_lround(guard->circ_successes),
- tor_lround(guard->unusable_circuits),
- tor_lround(guard->collapsed_circuits),
- tor_lround(guard->timeouts),
- tor_lround(get_circuit_build_close_time_ms()/1000));
- }
- } else if (pathbias_get_use_success_count(guard)/guard->use_attempts
- < pathbias_get_notice_use_rate(options)) {
- if (!guard->path_bias_use_noticed) {
- guard->path_bias_use_noticed = 1;
- log_notice(LD_CIRC,
- "Your Guard %s ($%s) is failing to carry more streams on its "
- "circuits than usual. "
- "Most likely this means the Tor network is overloaded "
- "or your network connection is poor. "
- "Use counts are %ld/%ld. Success counts are %ld/%ld. "
- "%ld circuits completed, %ld were unusable, %ld collapsed, "
- "and %ld timed out. "
- "For reference, your timeout cutoff is %ld seconds.",
- guard->nickname, hex_str(guard->identity, DIGEST_LEN),
- tor_lround(pathbias_get_use_success_count(guard)),
- tor_lround(guard->use_attempts),
- tor_lround(pathbias_get_close_success_count(guard)),
- tor_lround(guard->circ_attempts),
- tor_lround(guard->circ_successes),
- tor_lround(guard->unusable_circuits),
- tor_lround(guard->collapsed_circuits),
- tor_lround(guard->timeouts),
- tor_lround(get_circuit_build_close_time_ms()/1000));
- }
- }
- }
- }
- /**
- * Check the path bias circuit close status rates against our consensus
- * parameter limits.
- *
- * Emits a log message if the use success rates are too low.
- *
- * If pathbias_get_dropguards() is set, we also disable the use of
- * very failure prone guards.
- *
- * XXX: This function shares similar log messages and checks to
- * pathbias_measure_use_rate(). It may be possible to combine them
- * eventually, especially if we can ever remove the need for 3
- * levels of closure warns (if the overall circuit failure rate
- * goes down with ntor). One way to do so would be to multiply
- * the build rate with the use rate to get an idea of the total
- * fraction of the total network paths the user is able to use.
- * See ticket #8159.
- */
- static void
- pathbias_measure_close_rate(entry_guard_t *guard)
- {
- const or_options_t *options = get_options();
- if (guard->circ_attempts > pathbias_get_min_circs(options)) {
- /* Note: We rely on the < comparison here to allow us to set a 0
- * rate and disable the feature entirely. If refactoring, don't
- * change to <= */
- if (pathbias_get_close_success_count(guard)/guard->circ_attempts
- < pathbias_get_extreme_rate(options)) {
- /* Dropping is currently disabled by default. */
- if (pathbias_get_dropguards(options)) {
- if (!guard->path_bias_disabled) {
- log_warn(LD_CIRC,
- "Your Guard %s ($%s) is failing an extremely large "
- "amount of circuits. "
- "To avoid potential route manipulation attacks, Tor has "
- "disabled use of this guard. "
- "Success counts are %ld/%ld. Use counts are %ld/%ld. "
- "%ld circuits completed, %ld were unusable, %ld collapsed, "
- "and %ld timed out. "
- "For reference, your timeout cutoff is %ld seconds.",
- guard->nickname, hex_str(guard->identity, DIGEST_LEN),
- tor_lround(pathbias_get_close_success_count(guard)),
- tor_lround(guard->circ_attempts),
- tor_lround(pathbias_get_use_success_count(guard)),
- tor_lround(guard->use_attempts),
- tor_lround(guard->circ_successes),
- tor_lround(guard->unusable_circuits),
- tor_lround(guard->collapsed_circuits),
- tor_lround(guard->timeouts),
- tor_lround(get_circuit_build_close_time_ms()/1000));
- guard->path_bias_disabled = 1;
- guard->bad_since = approx_time();
- entry_guards_changed();
- return;
- }
- } else if (!guard->path_bias_extreme) {
- guard->path_bias_extreme = 1;
- log_warn(LD_CIRC,
- "Your Guard %s ($%s) is failing an extremely large "
- "amount of circuits. "
- "This could indicate a route manipulation attack, "
- "extreme network overload, or a bug. "
- "Success counts are %ld/%ld. Use counts are %ld/%ld. "
- "%ld circuits completed, %ld were unusable, %ld collapsed, "
- "and %ld timed out. "
- "For reference, your timeout cutoff is %ld seconds.",
- guard->nickname, hex_str(guard->identity, DIGEST_LEN),
- tor_lround(pathbias_get_close_success_count(guard)),
- tor_lround(guard->circ_attempts),
- tor_lround(pathbias_get_use_success_count(guard)),
- tor_lround(guard->use_attempts),
- tor_lround(guard->circ_successes),
- tor_lround(guard->unusable_circuits),
- tor_lround(guard->collapsed_circuits),
- tor_lround(guard->timeouts),
- tor_lround(get_circuit_build_close_time_ms()/1000));
- }
- } else if (pathbias_get_close_success_count(guard)/guard->circ_attempts
- < pathbias_get_warn_rate(options)) {
- if (!guard->path_bias_warned) {
- guard->path_bias_warned = 1;
- log_warn(LD_CIRC,
- "Your Guard %s ($%s) is failing a very large "
- "amount of circuits. "
- "Most likely this means the Tor network is "
- "overloaded, but it could also mean an attack against "
- "you or potentially the guard itself. "
- "Success counts are %ld/%ld. Use counts are %ld/%ld. "
- "%ld circuits completed, %ld were unusable, %ld collapsed, "
- "and %ld timed out. "
- "For reference, your timeout cutoff is %ld seconds.",
- guard->nickname, hex_str(guard->identity, DIGEST_LEN),
- tor_lround(pathbias_get_close_success_count(guard)),
- tor_lround(guard->circ_attempts),
- tor_lround(pathbias_get_use_success_count(guard)),
- tor_lround(guard->use_attempts),
- tor_lround(guard->circ_successes),
- tor_lround(guard->unusable_circuits),
- tor_lround(guard->collapsed_circuits),
- tor_lround(guard->timeouts),
- tor_lround(get_circuit_build_close_time_ms()/1000));
- }
- } else if (pathbias_get_close_success_count(guard)/guard->circ_attempts
- < pathbias_get_notice_rate(options)) {
- if (!guard->path_bias_noticed) {
- guard->path_bias_noticed = 1;
- log_notice(LD_CIRC,
- "Your Guard %s ($%s) is failing more circuits than "
- "usual. "
- "Most likely this means the Tor network is overloaded. "
- "Success counts are %ld/%ld. Use counts are %ld/%ld. "
- "%ld circuits completed, %ld were unusable, %ld collapsed, "
- "and %ld timed out. "
- "For reference, your timeout cutoff is %ld seconds.",
- guard->nickname, hex_str(guard->identity, DIGEST_LEN),
- tor_lround(pathbias_get_close_success_count(guard)),
- tor_lround(guard->circ_attempts),
- tor_lround(pathbias_get_use_success_count(guard)),
- tor_lround(guard->use_attempts),
- tor_lround(guard->circ_successes),
- tor_lround(guard->unusable_circuits),
- tor_lround(guard->collapsed_circuits),
- tor_lround(guard->timeouts),
- tor_lround(get_circuit_build_close_time_ms()/1000));
- }
- }
- }
- }
- /**
- * This function scales the path bias use rates if we have
- * more data than the scaling threshold. This allows us to
- * be more sensitive to recent measurements.
- *
- * XXX: The attempt count transfer stuff here might be done
- * better by keeping separate pending counters that get
- * transfered at circuit close. See ticket #8160.
- */
- static void
- pathbias_scale_close_rates(entry_guard_t *guard)
- {
- const or_options_t *options = get_options();
- /* If we get a ton of circuits, just scale everything down */
- if (guard->circ_attempts > pathbias_get_scale_threshold(options)) {
- double scale_ratio = pathbias_get_scale_ratio(options);
- int opened_attempts = pathbias_count_circs_in_states(guard,
- PATH_STATE_BUILD_ATTEMPTED, PATH_STATE_BUILD_ATTEMPTED);
- int opened_built = pathbias_count_circs_in_states(guard,
- PATH_STATE_BUILD_SUCCEEDED,
- PATH_STATE_USE_FAILED);
- /* Verify that the counts are sane before and after scaling */
- int counts_are_sane = (guard->circ_attempts >= guard->circ_successes);
- guard->circ_attempts -= (opened_attempts+opened_built);
- guard->circ_successes -= opened_built;
- guard->circ_attempts *= scale_ratio;
- guard->circ_successes *= scale_ratio;
- guard->timeouts *= scale_ratio;
- guard->successful_circuits_closed *= scale_ratio;
- guard->collapsed_circuits *= scale_ratio;
- guard->unusable_circuits *= scale_ratio;
- guard->circ_attempts += (opened_attempts+opened_built);
- guard->circ_successes += opened_built;
- entry_guards_changed();
- log_info(LD_CIRC,
- "Scaled pathbias counts to (%f,%f)/%f (%d/%d open) for guard "
- "%s ($%s)",
- guard->circ_successes, guard->successful_circuits_closed,
- guard->circ_attempts, opened_built, opened_attempts,
- guard->nickname, hex_str(guard->identity, DIGEST_LEN));
- /* Have the counts just become invalid by this scaling attempt? */
- if (counts_are_sane && guard->circ_attempts < guard->circ_successes) {
- log_notice(LD_BUG,
- "Scaling has mangled pathbias counts to %f/%f (%d/%d open) "
- "for guard %s ($%s)",
- guard->circ_successes, guard->circ_attempts, opened_built,
- opened_attempts, guard->nickname,
- hex_str(guard->identity, DIGEST_LEN));
- }
- }
- }
- /**
- * This function scales the path bias circuit close rates if we have
- * more data than the scaling threshold. This allows us to be more
- * sensitive to recent measurements.
- *
- * XXX: The attempt count transfer stuff here might be done
- * better by keeping separate pending counters that get
- * transfered at circuit close. See ticket #8160.
- */
- void
- pathbias_scale_use_rates(entry_guard_t *guard)
- {
- const or_options_t *options = get_options();
- /* If we get a ton of circuits, just scale everything down */
- if (guard->use_attempts > pathbias_get_scale_use_threshold(options)) {
- double scale_ratio = pathbias_get_scale_ratio(options);
- int opened_attempts = pathbias_count_circs_in_states(guard,
- PATH_STATE_USE_ATTEMPTED, PATH_STATE_USE_SUCCEEDED);
- /* Verify that the counts are sane before and after scaling */
- int counts_are_sane = (guard->use_attempts >= guard->use_successes);
- guard->use_attempts -= opened_attempts;
- guard->use_attempts *= scale_ratio;
- guard->use_successes *= scale_ratio;
- guard->use_attempts += opened_attempts;
- log_info(LD_CIRC,
- "Scaled pathbias use counts to %f/%f (%d open) for guard %s ($%s)",
- guard->use_successes, guard->use_attempts, opened_attempts,
- guard->nickname, hex_str(guard->identity, DIGEST_LEN));
- /* Have the counts just become invalid by this scaling attempt? */
- if (counts_are_sane && guard->use_attempts < guard->use_successes) {
- log_notice(LD_BUG,
- "Scaling has mangled pathbias usage counts to %f/%f "
- "(%d open) for guard %s ($%s)",
- guard->circ_successes, guard->circ_attempts,
- opened_attempts, guard->nickname,
- hex_str(guard->identity, DIGEST_LEN));
- }
- entry_guards_changed();
- }
- }
- /** Increment the number of times we successfully extended a circuit to
- * <b>guard</b>, first checking if the failure rate is high enough that
- * we should eliminate the guard. Return -1 if the guard looks no good;
- * return 0 if the guard looks fine.
- */
- static int
- entry_guard_inc_circ_attempt_count(entry_guard_t *guard)
- {
- entry_guards_changed();
- pathbias_measure_close_rate(guard);
- if (guard->path_bias_disabled)
- return -1;
- pathbias_scale_close_rates(guard);
- guard->circ_attempts++;
- log_info(LD_CIRC, "Got success count %f/%f for guard %s ($%s)",
- guard->circ_successes, guard->circ_attempts, guard->nickname,
- hex_str(guard->identity, DIGEST_LEN));
- return 0;
- }
- /** A "created" cell <b>reply</b> came back to us on circuit <b>circ</b>.
- * (The body of <b>reply</b> varies depending on what sort of handshake
- * this is.)
- *
- * Calculate the appropriate keys and digests, make sure KH is
- * correct, and initialize this hop of the cpath.
- *
- * Return - reason if we want to mark circ for close, else return 0.
- */
- int
- circuit_finish_handshake(origin_circuit_t *circ,
- const created_cell_t *reply)
- {
- char keys[CPATH_KEY_MATERIAL_LEN];
- crypt_path_t *hop;
- int rv;
- if ((rv = pathbias_count_build_attempt(circ)) < 0)
- return rv;
- if (circ->cpath->state == CPATH_STATE_AWAITING_KEYS) {
- hop = circ->cpath;
- } else {
- hop = onion_next_hop_in_cpath(circ->cpath);
- if (!hop) { /* got an extended when we're all done? */
- log_warn(LD_PROTOCOL,"got extended when circ already built? Closing.");
- return - END_CIRC_REASON_TORPROTOCOL;
- }
- }
- tor_assert(hop->state == CPATH_STATE_AWAITING_KEYS);
- {
- if (onion_skin_client_handshake(hop->handshake_state.tag,
- &hop->handshake_state,
- reply->reply, reply->handshake_len,
- (uint8_t*)keys, sizeof(keys),
- (uint8_t*)hop->rend_circ_nonce) < 0) {
- log_warn(LD_CIRC,"onion_skin_client_handshake failed.");
- return -END_CIRC_REASON_TORPROTOCOL;
- }
- }
- onion_handshake_state_release(&hop->handshake_state);
- if (circuit_init_cpath_crypto(hop, keys, 0)<0) {
- return -END_CIRC_REASON_TORPROTOCOL;
- }
- hop->state = CPATH_STATE_OPEN;
- log_info(LD_CIRC,"Finished building circuit hop:");
- circuit_log_path(LOG_INFO,LD_CIRC,circ);
- control_event_circuit_status(circ, CIRC_EVENT_EXTENDED, 0);
- return 0;
- }
- /** We received a relay truncated cell on circ.
- *
- * Since we don't send truncates currently, getting a truncated
- * means that a connection broke or an extend failed. For now,
- * just give up: force circ to close, and return 0.
- */
- int
- circuit_truncated(origin_circuit_t *circ, crypt_path_t *layer, int reason)
- {
- // crypt_path_t *victim;
- // connection_t *stream;
- tor_assert(circ);
- tor_assert(layer);
- /* XXX Since we don't send truncates currently, getting a truncated
- * means that a connection broke or an extend failed. For now,
- * just give up.
- */
- circuit_mark_for_close(TO_CIRCUIT(circ),
- END_CIRC_REASON_FLAG_REMOTE|reason);
- return 0;
- #if 0
- while (layer->next != circ->cpath) {
- /* we need to clear out layer->next */
- victim = layer->next;
- log_debug(LD_CIRC, "Killing a layer of the cpath.");
- for (stream = circ->p_streams; stream; stream=stream->next_stream) {
- if (stream->cpath_layer == victim) {
- log_info(LD_APP, "Marking stream %d for close because of truncate.",
- stream->stream_id);
- /* no need to send 'end' relay cells,
- * because the other side's already dead
- */
- connection_mark_unattached_ap(stream, END_STREAM_REASON_DESTROY);
- }
- }
- layer->next = victim->next;
- circuit_free_cpath_node(victim);
- }
- log_info(LD_CIRC, "finished");
- return 0;
- #endif
- }
- /** Given a response payload and keys, initialize, then send a created
- * cell back.
- */
- int
- onionskin_answer(or_circuit_t *circ,
- const created_cell_t *created_cell,
- const char *keys,
- const uint8_t *rend_circ_nonce)
- {
- cell_t cell;
- crypt_path_t *tmp_cpath;
- if (created_cell_format(&cell, created_cell) < 0) {
- log_warn(LD_BUG,"couldn't format created cell (type=%d, len=%d)",
- (int)created_cell->cell_type, (int)created_cell->handshake_len);
- return -1;
- }
- cell.circ_id = circ->p_circ_id;
- tmp_cpath = tor_malloc_zero(sizeof(crypt_path_t));
- tmp_cpath->magic = CRYPT_PATH_MAGIC;
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_OPEN);
- log_debug(LD_CIRC,"init digest forward 0x%.8x, backward 0x%.8x.",
- (unsigned int)get_uint32(keys),
- (unsigned int)get_uint32(keys+20));
- if (circuit_init_cpath_crypto(tmp_cpath, keys, 0)<0) {
- log_warn(LD_BUG,"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;
- tmp_cpath->magic = 0;
- tor_free(tmp_cpath);
- memcpy(circ->rend_circ_nonce, rend_circ_nonce, DIGEST_LEN);
- circ->is_first_hop = (created_cell->cell_type == CELL_CREATED_FAST);
- append_cell_to_circuit_queue(TO_CIRCUIT(circ),
- circ->p_chan, &cell, CELL_DIRECTION_IN, 0);
- log_debug(LD_CIRC,"Finished sending '%s' cell.",
- circ->is_first_hop ? "created_fast" : "created");
- if (!channel_is_local(circ->p_chan) &&
- !channel_is_outgoing(circ->p_chan)) {
- /* record that we could process create cells from a non-local conn
- * that we didn't initiate; presumably this means that create cells
- * can reach us too. */
- router_orport_found_reachable();
- }
- return 0;
- }
- /** Choose a length for a circuit of purpose <b>purpose</b>: three + the
- * number of endpoints that would give something away about our destination.
- *
- * If the routerlist <b>nodes</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.
- * XXX ^^ I think this behavior is a hold-over from back when we had only a
- * few relays in the network, and certainly back before guards existed.
- * We should very likely get rid of it. -RD
- */
- static int
- new_route_len(uint8_t purpose, extend_info_t *exit, smartlist_t *nodes)
- {
- int num_acceptable_routers;
- int routelen;
- tor_assert(nodes);
- routelen = DEFAULT_ROUTE_LEN;
- if (exit &&
- purpose != CIRCUIT_PURPOSE_TESTING &&
- purpose != CIRCUIT_PURPOSE_S_ESTABLISH_INTRO)
- routelen++;
- num_acceptable_routers = count_acceptable_nodes(nodes);
- log_debug(LD_CIRC,"Chosen route length %d (%d/%d routers suitable).",
- routelen, num_acceptable_routers, smartlist_len(nodes));
- if (num_acceptable_routers < 2) {
- log_info(LD_CIRC,
- "Not enough acceptable routers (%d). Discarding this circuit.",
- num_acceptable_routers);
- return -1;
- }
- if (num_acceptable_routers < routelen) {
- log_info(LD_CIRC,"Not enough routers: cutting routelen from %d to %d.",
- routelen, num_acceptable_routers);
- routelen = num_acceptable_routers;
- }
- return routelen;
- }
- /** Return a newly allocated list of uint16_t * for each predicted port not
- * handled by a current circuit. */
- static smartlist_t *
- circuit_get_unhandled_ports(time_t now)
- {
- smartlist_t *dest = rep_hist_get_predicted_ports(now);
- circuit_remove_handled_ports(dest);
- return dest;
- }
- /** Return 1 if we already have circuits present or on the way for
- * all anticipated ports. Return 0 if we should make more.
- *
- * If we're returning 0, set need_uptime and need_capacity to
- * indicate any requirements that the unhandled ports have.
- */
- int
- circuit_all_predicted_ports_handled(time_t now, int *need_uptime,
- int *need_capacity)
- {
- int i, enough;
- uint16_t *port;
- smartlist_t *sl = circuit_get_unhandled_ports(now);
- smartlist_t *LongLivedServices = get_options()->LongLivedPorts;
- tor_assert(need_uptime);
- tor_assert(need_capacity);
- // Always predict need_capacity
- *need_capacity = 1;
- enough = (smartlist_len(sl) == 0);
- for (i = 0; i < smartlist_len(sl); ++i) {
- port = smartlist_get(sl, i);
- if (smartlist_contains_int_as_string(LongLivedServices, *port))
- *need_uptime = 1;
- tor_free(port);
- }
- smartlist_free(sl);
- return enough;
- }
- /** Return 1 if <b>node</b> can handle one or more of the ports in
- * <b>needed_ports</b>, else return 0.
- */
- static int
- node_handles_some_port(const node_t *node, smartlist_t *needed_ports)
- { /* XXXX MOVE */
- int i;
- uint16_t port;
- for (i = 0; i < smartlist_len(needed_ports); ++i) {
- addr_policy_result_t r;
- /* alignment issues aren't a worry for this dereference, since
- needed_ports is explicitly a smartlist of uint16_t's */
- port = *(uint16_t *)smartlist_get(needed_ports, i);
- tor_assert(port);
- if (node)
- r = compare_tor_addr_to_node_policy(NULL, port, node);
- else
- continue;
- if (r != ADDR_POLICY_REJECTED && r != ADDR_POLICY_PROBABLY_REJECTED)
- return 1;
- }
- return 0;
- }
- /** Return true iff <b>conn</b> needs another general circuit to be
- * built. */
- static int
- ap_stream_wants_exit_attention(connection_t *conn)
- {
- entry_connection_t *entry;
- if (conn->type != CONN_TYPE_AP)
- return 0;
- entry = TO_ENTRY_CONN(conn);
- if (conn->state == AP_CONN_STATE_CIRCUIT_WAIT &&
- !conn->marked_for_close &&
- !(entry->want_onehop) && /* ignore one-hop streams */
- !(entry->use_begindir) && /* ignore targeted dir fetches */
- !(entry->chosen_exit_name) && /* ignore defined streams */
- !connection_edge_is_rendezvous_stream(TO_EDGE_CONN(conn)) &&
- !circuit_stream_is_being_handled(TO_ENTRY_CONN(conn), 0,
- MIN_CIRCUITS_HANDLING_STREAM))
- return 1;
- return 0;
- }
- /** 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 const node_t *
- choose_good_exit_server_general(int need_uptime, int need_capacity)
- {
- int *n_supported;
- int n_pending_connections = 0;
- smartlist_t *connections;
- int best_support = -1;
- int n_best_support=0;
- const or_options_t *options = get_options();
- const smartlist_t *the_nodes;
- const node_t *node=NULL;
- connections = get_connection_array();
- /* 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.
- */
- SMARTLIST_FOREACH(connections, connection_t *, conn,
- {
- if (ap_stream_wants_exit_attention(conn))
- ++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.)
- *
- * -1 means "Don't use this router at all."
- */
- the_nodes = nodelist_get_list();
- n_supported = tor_malloc(sizeof(int)*smartlist_len(the_nodes));
- SMARTLIST_FOREACH_BEGIN(the_nodes, const node_t *, node) {
- const int i = node_sl_idx;
- if (router_digest_is_me(node->identity)) {
- 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 (!node_has_descriptor(node)) {
- n_supported[i] = -1;
- continue;
- }
- if (!node->is_running || node->is_bad_exit) {
- n_supported[i] = -1;
- continue; /* skip routers that are known to be down or bad exits */
- }
- if (node_get_purpose(node) != ROUTER_PURPOSE_GENERAL) {
- /* never pick a non-general node as a random exit. */
- n_supported[i] = -1;
- continue;
- }
- if (routerset_contains_node(options->ExcludeExitNodesUnion_, node)) {
- n_supported[i] = -1;
- continue; /* user asked us not to use it, no matter what */
- }
- if (options->ExitNodes &&
- !routerset_contains_node(options->ExitNodes, node)) {
- n_supported[i] = -1;
- continue; /* not one of our chosen exit nodes */
- }
- if (node_is_unreliable(node, need_uptime, need_capacity, 0)) {
- n_supported[i] = -1;
- continue; /* skip routers that are not suitable. Don't worry if
- * this makes us reject all the possible routers: if so,
- * we'll retry later in this function with need_update and
- * need_capacity set to 0. */
- }
- if (!(node->is_valid || options->AllowInvalid_ & ALLOW_INVALID_EXIT)) {
- /* if it's invalid and we don't want it */
- n_supported[i] = -1;
- // log_fn(LOG_DEBUG,"Skipping node %s (index %d) -- invalid router.",
- // router->nickname, i);
- continue; /* skip invalid routers */
- }
- if (options->ExcludeSingleHopRelays &&
- node_allows_single_hop_exits(node)) {
- n_supported[i] = -1;
- continue;
- }
- if (node_exit_policy_rejects_all(node)) {
- 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 */
- }
- n_supported[i] = 0;
- /* iterate over connections */
- SMARTLIST_FOREACH_BEGIN(connections, connection_t *, conn) {
- if (!ap_stream_wants_exit_attention(conn))
- continue; /* Skip everything but APs in CIRCUIT_WAIT */
- if (connection_ap_can_use_exit(TO_ENTRY_CONN(conn), node)) {
- ++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);
- }
- } SMARTLIST_FOREACH_END(conn);
- if (n_pending_connections > 0 && n_supported[i] == 0) {
- /* Leave best_support at -1 if that's where it is, so we can
- * distinguish it later. */
- continue;
- }
- 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;
- }
- } SMARTLIST_FOREACH_END(node);
- log_info(LD_CIRC,
- "Found %d servers that might support %d/%d pending connections.",
- n_best_support, best_support >= 0 ? best_support : 0,
- n_pending_connections);
- /* If any routers definitely support any pending connections, choose one
- * at random. */
- if (best_support > 0) {
- smartlist_t *supporting = smartlist_new();
- SMARTLIST_FOREACH(the_nodes, const node_t *, node, {
- if (n_supported[node_sl_idx] == best_support)
- smartlist_add(supporting, (void*)node);
- });
- node = node_sl_choose_by_bandwidth(supporting, WEIGHT_FOR_EXIT);
- smartlist_free(supporting);
- } else {
- /* Either there are no pending connections, or no routers even seem to
- * possibly support any of them. Choose a router at random that satisfies
- * at least one predicted exit port. */
- int attempt;
- smartlist_t *needed_ports, *supporting;
- if (best_support == -1) {
- if (need_uptime || need_capacity) {
- log_info(LD_CIRC,
- "We couldn't find any live%s%s routers; falling back "
- "to list of all routers.",
- need_capacity?", fast":"",
- need_uptime?", stable":"");
- tor_free(n_supported);
- return choose_good_exit_server_general(0, 0);
- }
- log_notice(LD_CIRC, "All routers are down or won't exit%s -- "
- "choosing a doomed exit at random.",
- options->ExcludeExitNodesUnion_ ? " or are Excluded" : "");
- }
- supporting = smartlist_new();
- needed_ports = circuit_get_unhandled_ports(time(NULL));
- for (attempt = 0; attempt < 2; attempt++) {
- /* try once to pick only from routers that satisfy a needed port,
- * then if there are none, pick from any that support exiting. */
- SMARTLIST_FOREACH_BEGIN(the_nodes, const node_t *, node) {
- if (n_supported[node_sl_idx] != -1 &&
- (attempt || node_handles_some_port(node, needed_ports))) {
- // log_fn(LOG_DEBUG,"Try %d: '%s' is a possibility.",
- // try, router->nickname);
- smartlist_add(supporting, (void*)node);
- }
- } SMARTLIST_FOREACH_END(node);
- node = node_sl_choose_by_bandwidth(supporting, WEIGHT_FOR_EXIT);
- if (node)
- break;
- smartlist_clear(supporting);
- /* If we reach this point, we can't actually support any unhandled
- * predicted ports, so clear all the remaining ones. */
- if (smartlist_len(needed_ports))
- rep_hist_remove_predicted_ports(needed_ports);
- }
- SMARTLIST_FOREACH(needed_ports, uint16_t *, cp, tor_free(cp));
- smartlist_free(needed_ports);
- smartlist_free(supporting);
- }
- tor_free(n_supported);
- if (node) {
- log_info(LD_CIRC, "Chose exit server '%s'", node_describe(node));
- return node;
- }
- if (options->ExitNodes) {
- log_warn(LD_CIRC,
- "No specified %sexit routers seem to be running: "
- "can't choose an exit.",
- options->ExcludeExitNodesUnion_ ? "non-excluded " : "");
- }
- 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 const node_t *
- choose_good_exit_server(uint8_t purpose,
- int need_uptime, int need_capacity, int is_internal)
- {
- const or_options_t *options = get_options();
- router_crn_flags_t flags = CRN_NEED_DESC;
- if (need_uptime)
- flags |= CRN_NEED_UPTIME;
- if (need_capacity)
- flags |= CRN_NEED_CAPACITY;
- switch (purpose) {
- case CIRCUIT_PURPOSE_C_GENERAL:
- if (options->AllowInvalid_ & ALLOW_INVALID_MIDDLE)
- flags |= CRN_ALLOW_INVALID;
- if (is_internal) /* pick it like a middle hop */
- return router_choose_random_node(NULL, options->ExcludeNodes, flags);
- else
- return choose_good_exit_server_general(need_uptime,need_capacity);
- case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
- if (options->AllowInvalid_ & ALLOW_INVALID_RENDEZVOUS)
- flags |= CRN_ALLOW_INVALID;
- return router_choose_random_node(NULL, options->ExcludeNodes, flags);
- }
- log_warn(LD_BUG,"Unhandled purpose %d", purpose);
- tor_fragile_assert();
- return NULL;
- }
- /** Log a warning if the user specified an exit for the circuit that
- * has been excluded from use by ExcludeNodes or ExcludeExitNodes. */
- static void
- warn_if_last_router_excluded(origin_circuit_t *circ, const extend_info_t *exit)
- {
- const or_options_t *options = get_options();
- routerset_t *rs = options->ExcludeNodes;
- const char *description;
- uint8_t purpose = circ->base_.purpose;
- if (circ->build_state->onehop_tunnel)
- return;
- switch (purpose)
- {
- default:
- case CIRCUIT_PURPOSE_OR:
- case CIRCUIT_PURPOSE_INTRO_POINT:
- case CIRCUIT_PURPOSE_REND_POINT_WAITING:
- case CIRCUIT_PURPOSE_REND_ESTABLISHED:
- log_warn(LD_BUG, "Called on non-origin circuit (purpose %d, %s)",
- (int)purpose,
- circuit_purpose_to_string(purpose));
- return;
- case CIRCUIT_PURPOSE_C_GENERAL:
- if (circ->build_state->is_internal)
- return;
- description = "requested exit node";
- rs = options->ExcludeExitNodesUnion_;
- break;
- case CIRCUIT_PURPOSE_C_INTRODUCING:
- case CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT:
- case CIRCUIT_PURPOSE_C_INTRODUCE_ACKED:
- case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:
- case CIRCUIT_PURPOSE_S_CONNECT_REND:
- case CIRCUIT_PURPOSE_S_REND_JOINED:
- case CIRCUIT_PURPOSE_TESTING:
- return;
- case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
- case CIRCUIT_PURPOSE_C_REND_READY:
- case CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED:
- case CIRCUIT_PURPOSE_C_REND_JOINED:
- description = "chosen rendezvous point";
- break;
- case CIRCUIT_PURPOSE_CONTROLLER:
- rs = options->ExcludeExitNodesUnion_;
- description = "controller-selected circuit target";
- break;
- }
- if (routerset_contains_extendinfo(rs, exit)) {
- /* We should never get here if StrictNodes is set to 1. */
- if (options->StrictNodes) {
- log_warn(LD_BUG, "Using %s '%s' which is listed in ExcludeNodes%s, "
- "even though StrictNodes is set. Please report. "
- "(Circuit purpose: %s)",
- description, extend_info_describe(exit),
- rs==options->ExcludeNodes?"":" or ExcludeExitNodes",
- circuit_purpose_to_string(purpose));
- } else {
- log_warn(LD_CIRC, "Using %s '%s' which is listed in "
- "ExcludeNodes%s, because no better options were available. To "
- "prevent this (and possibly break your Tor functionality), "
- "set the StrictNodes configuration option. "
- "(Circuit purpose: %s)",
- description, extend_info_describe(exit),
- rs==options->ExcludeNodes?"":" or ExcludeExitNodes",
- circuit_purpose_to_string(purpose));
- }
- circuit_log_path(LOG_WARN, LD_CIRC, circ);
- }
- return;
- }
- /** Decide a suitable length for circ's cpath, and pick an exit
- * router (or use <b>exit</b> if provided). Store these in the
- * cpath. Return 0 if ok, -1 if circuit should be closed. */
- static int
- onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit)
- {
- cpath_build_state_t *state = circ->build_state;
- if (state->onehop_tunnel) {
- log_debug(LD_CIRC, "Launching a one-hop circuit for dir tunnel.");
- state->desired_path_len = 1;
- } else {
- int r = new_route_len(circ->base_.purpose, exit, nodelist_get_list());
- if (r < 1) /* must be at least 1 */
- return -1;
- state->desired_path_len = r;
- }
- if (exit) { /* the circuit-builder pre-requested one */
- warn_if_last_router_excluded(circ, exit);
- log_info(LD_CIRC,"Using requested exit node '%s'",
- extend_info_describe(exit));
- exit = extend_info_dup(exit);
- } else { /* we have to decide one */
- const node_t *node =
- choose_good_exit_server(circ->base_.purpose, state->need_uptime,
- state->need_capacity, state->is_internal);
- if (!node) {
- log_warn(LD_CIRC,"failed to choose an exit server");
- return -1;
- }
- exit = extend_info_from_node(node, 0);
- tor_assert(exit);
- }
- state->chosen_exit = exit;
- return 0;
- }
- /** Give <b>circ</b> a new exit destination to <b>exit</b>, and add a
- * hop to the cpath reflecting this. Don't send the next extend cell --
- * the caller will do this if it wants to.
- */
- int
- circuit_append_new_exit(origin_circuit_t *circ, extend_info_t *exit)
- {
- cpath_build_state_t *state;
- tor_assert(exit);
- tor_assert(circ);
- state = circ->build_state;
- tor_assert(state);
- extend_info_free(state->chosen_exit);
- state->chosen_exit = extend_info_dup(exit);
- ++circ->build_state->desired_path_len;
- onion_append_hop(&circ->cpath, exit);
- return 0;
- }
- /** Take an open <b>circ</b>, and add a new hop at the end, based on
- * <b>info</b>. Set its state back to CIRCUIT_STATE_BUILDING, and then
- * send the next extend cell to begin connecting to that hop.
- */
- int
- circuit_extend_to_new_exit(origin_circuit_t *circ, extend_info_t *exit)
- {
- int err_reason = 0;
- warn_if_last_router_excluded(circ, exit);
- tor_gettimeofday(&circ->base_.timestamp_began);
- circuit_append_new_exit(circ, exit);
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_BUILDING);
- if ((err_reason = circuit_send_next_onion_skin(circ))<0) {
- log_warn(LD_CIRC, "Couldn't extend circuit to new point %s.",
- extend_info_describe(exit));
- circuit_mark_for_close(TO_CIRCUIT(circ), -err_reason);
- return -1;
- }
- // XXX: Should cannibalized circuits be dirty or not? Not easy to say..
- return 0;
- }
- /** Return the number of routers in <b>routers</b> that are currently up
- * and available for building circuits through.
- */
- static int
- count_acceptable_nodes(smartlist_t *nodes)
- {
- int num=0;
- SMARTLIST_FOREACH_BEGIN(nodes, const node_t *, node) {
- // log_debug(LD_CIRC,
- // "Contemplating whether router %d (%s) is a new option.",
- // i, r->nickname);
- if (! node->is_running)
- // log_debug(LD_CIRC,"Nope, the directory says %d is not running.",i);
- continue;
- if (! node->is_valid)
- // log_debug(LD_CIRC,"Nope, the directory says %d is not valid.",i);
- continue;
- if (! node_has_descriptor(node))
- continue;
- /* XXX This clause makes us count incorrectly: if AllowInvalidRouters
- * allows this node in some places, then we're getting an inaccurate
- * count. For now, be conservative and don't count it. But later we
- * should try to be smarter. */
- ++num;
- } SMARTLIST_FOREACH_END(node);
- // log_debug(LD_CIRC,"I like %d. num_acceptable_routers now %d.",i, num);
- 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;
- }
- }
- /** A helper function used by onion_extend_cpath(). Use <b>purpose</b>
- * and <b>state</b> and the cpath <b>head</b> (currently populated only
- * to length <b>cur_len</b> to decide a suitable middle hop for a
- * circuit. In particular, make sure we don't pick the exit node or its
- * family, and make sure we don't duplicate any previous nodes or their
- * families. */
- static const node_t *
- choose_good_middle_server(uint8_t purpose,
- cpath_build_state_t *state,
- crypt_path_t *head,
- int cur_len)
- {
- int i;
- const node_t *r, *choice;
- crypt_path_t *cpath;
- smartlist_t *excluded;
- const or_options_t *options = get_options();
- router_crn_flags_t flags = CRN_NEED_DESC;
- tor_assert(CIRCUIT_PURPOSE_MIN_ <= purpose &&
- purpose <= CIRCUIT_PURPOSE_MAX_);
- log_debug(LD_CIRC, "Contemplating intermediate hop: random choice.");
- excluded = smartlist_new();
- if ((r = build_state_get_exit_node(state))) {
- nodelist_add_node_and_family(excluded, r);
- }
- for (i = 0, cpath = head; i < cur_len; ++i, cpath=cpath->next) {
- if ((r = node_get_by_id(cpath->extend_info->identity_digest))) {
- nodelist_add_node_and_family(excluded, r);
- }
- }
- if (state->need_uptime)
- flags |= CRN_NEED_UPTIME;
- if (state->need_capacity)
- flags |= CRN_NEED_CAPACITY;
- if (options->AllowInvalid_ & ALLOW_INVALID_MIDDLE)
- flags |= CRN_ALLOW_INVALID;
- choice = router_choose_random_node(excluded, options->ExcludeNodes, flags);
- smartlist_free(excluded);
- return choice;
- }
- /** Pick a good entry server for the circuit to be built according to
- * <b>state</b>. Don't reuse a chosen exit (if any), don't use this
- * router (if we're an OR), and respect firewall settings; if we're
- * configured to use entry guards, return one.
- *
- * If <b>state</b> is NULL, we're choosing a router to serve as an entry
- * guard, not for any particular circuit.
- */
- /* XXXX024 I'd like to have this be static again, but entrynodes.c needs it. */
- const node_t *
- choose_good_entry_server(uint8_t purpose, cpath_build_state_t *state)
- {
- const node_t *choice;
- smartlist_t *excluded;
- const or_options_t *options = get_options();
- router_crn_flags_t flags = CRN_NEED_GUARD|CRN_NEED_DESC;
- const node_t *node;
- if (state && options->UseEntryGuards &&
- (purpose != CIRCUIT_PURPOSE_TESTING || options->BridgeRelay)) {
- /* This request is for an entry server to use for a regular circuit,
- * and we use entry guard nodes. Just return one of the guard nodes. */
- return choose_random_entry(state);
- }
- excluded = smartlist_new();
- if (state && (node = build_state_get_exit_node(state))) {
- /* Exclude the exit node from the state, if we have one. Also exclude its
- * family. */
- nodelist_add_node_and_family(excluded, node);
- }
- if (firewall_is_fascist_or()) {
- /* Exclude all ORs that we can't reach through our firewall */
- smartlist_t *nodes = nodelist_get_list();
- SMARTLIST_FOREACH(nodes, const node_t *, node, {
- if (!fascist_firewall_allows_node(node))
- smartlist_add(excluded, (void*)node);
- });
- }
- /* and exclude current entry guards and their families, if applicable */
- /*XXXX025 use the using_as_guard flag to accomplish this.*/
- if (options->UseEntryGuards) {
- SMARTLIST_FOREACH(get_entry_guards(), const entry_guard_t *, entry,
- {
- if ((node = node_get_by_id(entry->identity))) {
- nodelist_add_node_and_family(excluded, node);
- }
- });
- }
- if (state) {
- if (state->need_uptime)
- flags |= CRN_NEED_UPTIME;
- if (state->need_capacity)
- flags |= CRN_NEED_CAPACITY;
- }
- if (options->AllowInvalid_ & ALLOW_INVALID_ENTRY)
- flags |= CRN_ALLOW_INVALID;
- choice = router_choose_random_node(excluded, options->ExcludeNodes, flags);
- smartlist_free(excluded);
- return choice;
- }
- /** Return the first non-open hop in cpath, or return NULL if all
- * hops are open. */
- static crypt_path_t *
- onion_next_hop_in_cpath(crypt_path_t *cpath)
- {
- crypt_path_t *hop = cpath;
- do {
- if (hop->state != CPATH_STATE_OPEN)
- return hop;
- hop = hop->next;
- } while (hop != cpath);
- return NULL;
- }
- /** Choose a suitable next hop in the cpath <b>head_ptr</b>,
- * based on <b>state</b>. Append the hop info to head_ptr.
- */
- static int
- onion_extend_cpath(origin_circuit_t *circ)
- {
- uint8_t purpose = circ->base_.purpose;
- cpath_build_state_t *state = circ->build_state;
- int cur_len = circuit_get_cpath_len(circ);
- extend_info_t *info = NULL;
- if (cur_len >= state->desired_path_len) {
- log_debug(LD_CIRC, "Path is complete: %d steps long",
- state->desired_path_len);
- return 1;
- }
- log_debug(LD_CIRC, "Path is %d long; we want %d", cur_len,
- state->desired_path_len);
- if (cur_len == state->desired_path_len - 1) { /* Picking last node */
- info = extend_info_dup(state->chosen_exit);
- } else if (cur_len == 0) { /* picking first node */
- const node_t *r = choose_good_entry_server(purpose, state);
- if (r) {
- /* If we're a client, use the preferred address rather than the
- primary address, for potentially connecting to an IPv6 OR
- port. */
- info = extend_info_from_node(r, server_mode(get_options()) == 0);
- tor_assert(info);
- }
- } else {
- const node_t *r =
- choose_good_middle_server(purpose, state, circ->cpath, cur_len);
- if (r) {
- info = extend_info_from_node(r, 0);
- tor_assert(info);
- }
- }
- if (!info) {
- log_warn(LD_CIRC,"Failed to find node for hop %d of our path. Discarding "
- "this circuit.", cur_len);
- return -1;
- }
- log_debug(LD_CIRC,"Chose router %s for hop %d (exit is %s)",
- extend_info_describe(info),
- cur_len+1, build_state_get_exit_nickname(state));
- onion_append_hop(&circ->cpath, info);
- extend_info_free(info);
- return 0;
- }
- /** Create a new hop, annotate it with information about its
- * corresponding router <b>choice</b>, and append it to the
- * end of the cpath <b>head_ptr</b>. */
- static int
- onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice)
- {
- crypt_path_t *hop = tor_malloc_zero(sizeof(crypt_path_t));
- /* link hop into the cpath, at the end. */
- onion_append_to_cpath(head_ptr, hop);
- hop->magic = CRYPT_PATH_MAGIC;
- hop->state = CPATH_STATE_CLOSED;
- hop->extend_info = extend_info_dup(choice);
- hop->package_window = circuit_initial_package_window();
- hop->deliver_window = CIRCWINDOW_START;
- return 0;
- }
- /** Allocate a new extend_info object based on the various arguments. */
- extend_info_t *
- extend_info_new(const char *nickname, const char *digest,
- crypto_pk_t *onion_key,
- const curve25519_public_key_t *curve25519_key,
- const tor_addr_t *addr, uint16_t port)
- {
- extend_info_t *info = tor_malloc_zero(sizeof(extend_info_t));
- memcpy(info->identity_digest, digest, DIGEST_LEN);
- if (nickname)
- strlcpy(info->nickname, nickname, sizeof(info->nickname));
- if (onion_key)
- info->onion_key = crypto_pk_dup_key(onion_key);
- #ifdef CURVE25519_ENABLED
- if (curve25519_key)
- memcpy(&info->curve25519_onion_key, curve25519_key,
- sizeof(curve25519_public_key_t));
- #else
- (void)curve25519_key;
- #endif
- tor_addr_copy(&info->addr, addr);
- info->port = port;
- return info;
- }
- /** Allocate and return a new extend_info that can be used to build a
- * circuit to or through the node <b>node</b>. Use the primary address
- * of the node (i.e. its IPv4 address) unless
- * <b>for_direct_connect</b> is true, in which case the preferred
- * address is used instead. May return NULL if there is not enough
- * info about <b>node</b> to extend to it--for example, if there is no
- * routerinfo_t or microdesc_t.
- **/
- extend_info_t *
- extend_info_from_node(const node_t *node, int for_direct_connect)
- {
- tor_addr_port_t ap;
- if (node->ri == NULL && (node->rs == NULL || node->md == NULL))
- return NULL;
- if (for_direct_connect)
- node_get_pref_orport(node, &ap);
- else
- node_get_prim_orport(node, &ap);
- log_debug(LD_CIRC, "using %s for %s",
- fmt_addrport(&ap.addr, ap.port),
- node->ri ? node->ri->nickname : node->rs->nickname);
- if (node->ri)
- return extend_info_new(node->ri->nickname,
- node->identity,
- node->ri->onion_pkey,
- node->ri->onion_curve25519_pkey,
- &ap.addr,
- ap.port);
- else if (node->rs && node->md)
- return extend_info_new(node->rs->nickname,
- node->identity,
- node->md->onion_pkey,
- node->md->onion_curve25519_pkey,
- &ap.addr,
- ap.port);
- else
- return NULL;
- }
- /** Release storage held by an extend_info_t struct. */
- void
- extend_info_free(extend_info_t *info)
- {
- if (!info)
- return;
- crypto_pk_free(info->onion_key);
- tor_free(info);
- }
- /** Allocate and return a new extend_info_t with the same contents as
- * <b>info</b>. */
- extend_info_t *
- extend_info_dup(extend_info_t *info)
- {
- extend_info_t *newinfo;
- tor_assert(info);
- newinfo = tor_malloc(sizeof(extend_info_t));
- memcpy(newinfo, info, sizeof(extend_info_t));
- if (info->onion_key)
- newinfo->onion_key = crypto_pk_dup_key(info->onion_key);
- else
- newinfo->onion_key = NULL;
- return newinfo;
- }
- /** Return the routerinfo_t for the chosen exit router in <b>state</b>.
- * If there is no chosen exit, or if we don't know the routerinfo_t for
- * the chosen exit, return NULL.
- */
- const node_t *
- build_state_get_exit_node(cpath_build_state_t *state)
- {
- if (!state || !state->chosen_exit)
- return NULL;
- return node_get_by_id(state->chosen_exit->identity_digest);
- }
- /** Return the nickname for the chosen exit router in <b>state</b>. If
- * there is no chosen exit, or if we don't know the routerinfo_t for the
- * chosen exit, return NULL.
- */
- const char *
- build_state_get_exit_nickname(cpath_build_state_t *state)
- {
- if (!state || !state->chosen_exit)
- return NULL;
- return state->chosen_exit->nickname;
- }
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