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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) 2007-2017, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file circuitbuild.c
- *
- * \brief Implements the details of building circuits (by chosing paths,
- * constructing/sending create/extend cells, and so on).
- *
- * On the client side, this module handles launching circuits. Circuit
- * launches are srtarted from circuit_establish_circuit(), called from
- * circuit_launch_by_extend_info()). To choose the path the circuit will
- * take, onion_extend_cpath() calls into a maze of node selection functions.
- *
- * Once the circuit is ready to be launched, the first hop is treated as a
- * special case with circuit_handle_first_hop(), since it might need to open a
- * channel. As the channel opens, and later as CREATED and RELAY_EXTENDED
- * cells arrive, the client will invoke circuit_send_next_onion_skin() to send
- * CREATE or RELAY_EXTEND cells.
- *
- * On the server side, this module also handles the logic of responding to
- * RELAY_EXTEND requests, using circuit_extend().
- **/
- #define CIRCUITBUILD_PRIVATE
- #include "or.h"
- #include "bridges.h"
- #include "channel.h"
- #include "circpathbias.h"
- #define CIRCUITBUILD_PRIVATE
- #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 "crypto.h"
- #include "directory.h"
- #include "entrynodes.h"
- #include "hs_ntor.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 "relay.h"
- #include "rendcommon.h"
- #include "rephist.h"
- #include "router.h"
- #include "routerlist.h"
- #include "routerparse.h"
- #include "routerset.h"
- #include "transports.h"
- static channel_t * channel_connect_for_circuit(const tor_addr_t *addr,
- uint16_t port,
- const char *id_digest,
- const ed25519_public_key_t *ed_id);
- 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,
- int is_hs_v3_rp_circuit);
- static crypt_path_t *onion_next_hop_in_cpath(crypt_path_t *cpath);
- static int onion_extend_cpath(origin_circuit_t *circ);
- STATIC int onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice);
- static int circuit_send_first_onion_skin(origin_circuit_t *circ);
- static int circuit_build_no_more_hops(origin_circuit_t *circ);
- static int circuit_send_intermediate_onion_skin(origin_circuit_t *circ,
- crypt_path_t *hop);
- static const node_t *choose_good_middle_server(uint8_t purpose,
- cpath_build_state_t *state,
- crypt_path_t *head,
- int cur_len);
- /** 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,
- const ed25519_public_key_t *ed_id)
- {
- channel_t *chan;
- chan = channel_connect(addr, port, id_digest, ed_id);
- if (chan) command_setup_channel(chan);
- return chan;
- }
- /** Search for a value for circ_id that we can use on <b>chan</b> for an
- * outbound circuit, 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)
- {
- /* This number is chosen somewhat arbitrarily; see comment below for more
- * info. When the space is 80% full, it gives a one-in-a-million failure
- * chance; when the space is 90% full, it gives a one-in-850 chance; and when
- * the space is 95% full, it gives a one-in-26 failure chance. That seems
- * okay, though you could make a case IMO for anything between N=32 and
- * N=256. */
- #define MAX_CIRCID_ATTEMPTS 64
- int in_use;
- unsigned n_with_circ = 0, n_pending_destroy = 0, n_weird_pending_destroy = 0;
- circid_t test_circ_id;
- circid_t attempts=0;
- circid_t high_bit, max_range, mask;
- int64_t pending_destroy_time_total = 0;
- int64_t pending_destroy_time_max = 0;
- 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);
- mask = max_range - 1;
- high_bit = (chan->circ_id_type == CIRC_ID_TYPE_HIGHER) ? max_range : 0;
- do {
- if (++attempts > MAX_CIRCID_ATTEMPTS) {
- /* Make sure we don't loop forever because all circuit IDs are used.
- *
- * Once, we would try until we had tried every possible circuit ID. But
- * that's quite expensive. Instead, we try MAX_CIRCID_ATTEMPTS random
- * circuit IDs, and then give up.
- *
- * This potentially causes us to give up early if our circuit ID space
- * is nearly full. If we have N circuit IDs in use, then we will reject
- * a new circuit with probability (N / max_range) ^ MAX_CIRCID_ATTEMPTS.
- * This means that in practice, a few percent of our circuit ID capacity
- * will go unused.
- *
- * The alternative here, though, is to do a linear search over the
- * whole circuit ID space every time we extend a circuit, which is
- * not so great either.
- */
- int64_t queued_destroys;
- char *m = rate_limit_log(&chan->last_warned_circ_ids_exhausted,
- approx_time());
- if (m == NULL)
- return 0; /* This message has been rate-limited away. */
- if (n_pending_destroy)
- pending_destroy_time_total /= n_pending_destroy;
- log_warn(LD_CIRC,"No unused circIDs found on channel %s wide "
- "circID support, with %u inbound and %u outbound circuits. "
- "Found %u circuit IDs in use by circuits, and %u with "
- "pending destroy cells. (%u of those were marked bogusly.) "
- "The ones with pending destroy cells "
- "have been marked unusable for an average of %ld seconds "
- "and a maximum of %ld seconds. This channel is %ld seconds "
- "old. Failing a circuit.%s",
- chan->wide_circ_ids ? "with" : "without",
- chan->num_p_circuits, chan->num_n_circuits,
- n_with_circ, n_pending_destroy, n_weird_pending_destroy,
- (long)pending_destroy_time_total,
- (long)pending_destroy_time_max,
- (long)(approx_time() - chan->timestamp_created),
- m);
- tor_free(m);
- if (!chan->cmux) {
- /* This warning should be impossible. */
- log_warn(LD_BUG, " This channel somehow has no cmux on it!");
- return 0;
- }
- /* analysis so far on 12184 suggests that we're running out of circuit
- IDs because it looks like we have too many pending destroy
- cells. Let's see how many we really have pending.
- */
- queued_destroys = circuitmux_count_queued_destroy_cells(chan,
- chan->cmux);
- log_warn(LD_CIRC, " Circuitmux on this channel has %u circuits, "
- "of which %u are active. It says it has "I64_FORMAT
- " destroy cells queued.",
- circuitmux_num_circuits(chan->cmux),
- circuitmux_num_active_circuits(chan->cmux),
- I64_PRINTF_ARG(queued_destroys));
- /* Change this into "if (1)" in order to get more information about
- * possible failure modes here. You'll need to know how to use gdb with
- * Tor: this will make Tor exit with an assertion failure if the cmux is
- * corrupt. */
- if (0)
- circuitmux_assert_okay(chan->cmux);
- channel_dump_statistics(chan, LOG_WARN);
- return 0;
- }
- do {
- crypto_rand((char*) &test_circ_id, sizeof(test_circ_id));
- test_circ_id &= mask;
- } while (test_circ_id == 0);
- test_circ_id |= high_bit;
- in_use = circuit_id_in_use_on_channel(test_circ_id, chan);
- if (in_use == 1)
- ++n_with_circ;
- else if (in_use == 2) {
- time_t since_when;
- ++n_pending_destroy;
- since_when =
- circuit_id_when_marked_unusable_on_channel(test_circ_id, chan);
- if (since_when) {
- time_t waiting = approx_time() - since_when;
- pending_destroy_time_total += waiting;
- if (waiting > pending_destroy_time_max)
- pending_destroy_time_max = waiting;
- } else {
- ++n_weird_pending_destroy;
- }
- }
- } while (in_use);
- 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] = '$';
- base16_encode(elt+1, HEX_DIGEST_LEN+1, id, DIGEST_LEN);
- }
- } else { /* ! verbose_names */
- elt = tor_malloc(HEX_DIGEST_LEN+2);
- elt[0] = '$';
- 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);
- }
- /** Return 1 iff every node in circ's cpath definitely supports ntor. */
- static int
- circuit_cpath_supports_ntor(const origin_circuit_t *circ)
- {
- crypt_path_t *head, *cpath;
- cpath = head = circ->cpath;
- do {
- /* if the extend_info is missing, we can't tell if it supports ntor */
- if (!cpath->extend_info) {
- return 0;
- }
- /* if the key is blank, it definitely doesn't support ntor */
- if (!extend_info_supports_ntor(cpath->extend_info)) {
- return 0;
- }
- cpath = cpath->next;
- } while (cpath != head);
- return 1;
- }
- /** 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 = 0;
- /* onion_extend_cpath assumes these are non-NULL */
- tor_assert(circ);
- tor_assert(circ->build_state);
- while (r == 0) {
- r = onion_extend_cpath(circ);
- if (r < 0) {
- log_info(LD_CIRC,"Generating cpath hop failed.");
- return -1;
- }
- }
- /* The path is complete */
- tor_assert(r == 1);
- /* Does every node in this path support ntor? */
- int path_supports_ntor = circuit_cpath_supports_ntor(circ);
- /* We would like every path to support ntor, but we have to allow for some
- * edge cases. */
- tor_assert(circuit_get_cpath_len(circ));
- if (circuit_can_use_tap(circ)) {
- /* Circuits from clients to intro points, and hidden services to
- * rend points do not support ntor, because the hidden service protocol
- * does not include ntor onion keys. This is also true for Tor2web clients
- * and Single Onion Services. */
- return 0;
- }
- if (circuit_get_cpath_len(circ) == 1) {
- /* Allow for bootstrapping: when we're fetching directly from a fallback,
- * authority, or bridge, we have no way of knowing its ntor onion key
- * before we connect to it. So instead, we try connecting, and end up using
- * CREATE_FAST. */
- tor_assert(circ->cpath);
- tor_assert(circ->cpath->extend_info);
- const node_t *node = node_get_by_id(
- circ->cpath->extend_info->identity_digest);
- /* If we don't know the node and its descriptor, we must be bootstrapping.
- */
- if (!node || !node_has_descriptor(node)) {
- return 0;
- }
- }
- if (BUG(!path_supports_ntor)) {
- /* If we're building a multi-hop path, and it's not one of the HS or
- * bootstrapping exceptions, and it doesn't support ntor, something has
- * gone wrong. */
- return -1;
- }
- return 0;
- }
- /** 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_ei, int flags)
- {
- origin_circuit_t *circ;
- int err_reason = 0;
- int is_hs_v3_rp_circuit = 0;
- if (flags & CIRCLAUNCH_IS_V3_RP) {
- is_hs_v3_rp_circuit = 1;
- }
- circ = origin_circuit_init(purpose, flags);
- if (onion_pick_cpath_exit(circ, exit_ei, is_hs_v3_rp_circuit) < 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;
- }
- /** Return the guard state associated with <b>circ</b>, which may be NULL. */
- circuit_guard_state_t *
- origin_circuit_get_guard_state(origin_circuit_t *circ)
- {
- return circ->guard_state;
- }
- /** 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;
- const or_options_t *options = get_options();
- firsthop = onion_next_hop_in_cpath(circ->cpath);
- tor_assert(firsthop);
- tor_assert(firsthop->extend_info);
- /* Some bridges are on private addresses. Others pass a dummy private
- * address to the pluggable transport, which ignores it.
- * Deny the connection if:
- * - the address is internal, and
- * - we're not connecting to a configured bridge, and
- * - we're not configured to allow extends to private addresses. */
- if (tor_addr_is_internal(&firsthop->extend_info->addr, 0) &&
- !extend_info_is_a_configured_bridge(firsthop->extend_info) &&
- !options->ExtendAllowPrivateAddresses) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Client asked me to connect directly to a private address");
- return -END_CIRC_REASON_TORPROTOCOL;
- }
- /* 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->ed_identity,
- &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,
- &firsthop->extend_info->ed_identity);
- 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.");
- circ->base_.n_chan = NULL;
- 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.
- *
- * Close_origin_circuits is 1 if we should close all the origin circuits
- * through this channel, or 0 otherwise. (This happens when we want to retry
- * an older guard.)
- */
- void
- circuit_n_chan_done(channel_t *chan, int status, int close_origin_circuits)
- {
- smartlist_t *pending_circs;
- int err_reason = 0;
- tor_assert(chan);
- log_debug(LD_CIRC,"chan to %s, status=%d",
- 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;
- }
- if (close_origin_circuits && CIRCUIT_IS_ORIGIN(circ)) {
- log_info(LD_CIRC,"Channel deprecated for origin circs; 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) {
- static ratelim_t circid_warning_limit = RATELIM_INIT(9600);
- log_fn_ratelim(&circid_warning_limit, LOG_WARN, LD_CIRC,
- "failed to get unique circID.");
- goto error;
- }
- 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");
- goto error;
- }
- log_debug(LD_CIRC,"Chosen circID %u.", (unsigned)id);
- circuit_set_n_circid_chan(circ, id, circ->n_chan);
- 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 (!CHANNEL_IS_OPEN(circ->n_chan)) {
- 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;
- error:
- circ->n_chan = NULL;
- return -1;
- }
- /** 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];
- char *address;
- const routerinfo_t *me = router_get_my_routerinfo();
- if (!me)
- return 0;
- address = tor_dup_ip(me->addr);
- control_event_server_status(LOG_NOTICE,
- "CHECKING_REACHABILITY ORADDRESS=%s:%d",
- address, me->or_port);
- if (me->dir_port) {
- tor_snprintf(dirbuf, sizeof(dirbuf), " and DirPort %s:%d",
- address, me->dir_port);
- control_event_server_status(LOG_NOTICE,
- "CHECKING_REACHABILITY DIRADDRESS=%s:%d",
- 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)",
- address, me->or_port,
- me->dir_port ? dirbuf : "",
- me->dir_port ? "are" : "is",
- TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT/60);
- tor_free(address);
- 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 (!circuit_has_usable_onion_key(circ)) {
- /* We don't have ntor, and we don't have or can't use TAP,
- * so our hand is forced: only a create_fast will work. */
- return 1;
- }
- if (public_server_mode(options)) {
- /* We're a server, and we have a usable onion key. We can choose.
- * Prefer to blend our circuit into the other circuits we are
- * creating on behalf of others. */
- return 0;
- }
- return networkstatus_get_param(NULL, "usecreatefast", 0, 0, 1);
- }
- /**
- * Return true if <b>circ</b> is the type of circuit we want to count
- * timeouts from.
- *
- * In particular, we want to consider any circuit that plans to build
- * at least 3 hops (but maybe more), but has 3 or fewer hops built
- * so far.
- *
- * We still want to consider circuits before 3 hops, because we need
- * to decide if we should convert them to a measurement circuit in
- * circuit_build_times_handle_completed_hop(), rather than letting
- * slow circuits get killed right away.
- */
- int
- circuit_timeout_want_to_count_circ(const origin_circuit_t *circ)
- {
- return !circ->has_opened
- && circ->build_state->desired_path_len >= DEFAULT_ROUTE_LEN
- && circuit_get_cpath_opened_len(circ) <= DEFAULT_ROUTE_LEN;
- }
- /** 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.
- * Note that TAP handshakes in CREATE cells are only used for direct
- * connections:
- * - from Tor2web to intro points not in the client's consensus, and
- * - from Single Onions to rend points not in the service's consensus.
- * This is checked in onion_populate_cpath. */
- static void
- circuit_pick_create_handshake(uint8_t *cell_type_out,
- uint16_t *handshake_type_out,
- const extend_info_t *ei)
- {
- /* torspec says: In general, clients SHOULD use CREATE whenever they are
- * using the TAP handshake, and CREATE2 otherwise. */
- if (extend_info_supports_ntor(ei)) {
- *cell_type_out = CELL_CREATE2;
- *handshake_type_out = ONION_HANDSHAKE_TYPE_NTOR;
- } else {
- /* XXXX030 Remove support for deciding to use TAP and EXTEND. */
- *cell_type_out = CELL_CREATE;
- *handshake_type_out = ONION_HANDSHAKE_TYPE_TAP;
- }
- }
- /** Decide whether to use a TAP or ntor handshake for extending to <b>ei</b>
- * and set *<b>handshake_type_out</b> accordingly. Decide whether 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.
- * Note that TAP handshakes in EXTEND cells are only used:
- * - from clients to intro points, and
- * - from hidden services to rend points.
- * This is checked in onion_populate_cpath.
- */
- static void
- circuit_pick_extend_handshake(uint8_t *cell_type_out,
- uint8_t *create_cell_type_out,
- uint16_t *handshake_type_out,
- const extend_info_t *ei)
- {
- uint8_t t;
- circuit_pick_create_handshake(&t, handshake_type_out, ei);
- /* torspec says: Clients SHOULD use the EXTEND format whenever sending a TAP
- * handshake... In other cases, clients SHOULD use EXTEND2. */
- if (*handshake_type_out != ONION_HANDSHAKE_TYPE_TAP) {
- *cell_type_out = RELAY_COMMAND_EXTEND2;
- *create_cell_type_out = CELL_CREATE2;
- } else {
- /* XXXX030 Remove support for deciding to use TAP and EXTEND. */
- *cell_type_out = RELAY_COMMAND_EXTEND;
- *create_cell_type_out = CELL_CREATE;
- }
- }
- /**
- * Return true iff <b>purpose</b> is a purpose for a circuit which is
- * allowed to have no guard configured, even if the circuit is multihop
- * and guards are enabled.
- */
- static int
- circuit_purpose_may_omit_guard(int purpose)
- {
- switch (purpose) {
- case CIRCUIT_PURPOSE_TESTING:
- case CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT:
- /* Testing circuits may omit guards because they're measuring
- * liveness or performance, and don't want guards to interfere. */
- return 1;
- default:
- /* All other multihop circuits should use guards if guards are
- * enabled. */
- return 0;
- }
- }
- /** 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, if circ's cpath still has any non-open hops, we need to
- * build a relay extend cell and send it forward to the next non-open hop.
- *
- * If all hops on the cpath are open, we're done building the circuit
- * and we should do housekeeping for the newly opened circuit.
- *
- * Return -reason if we want to tear down circ, else return 0.
- */
- int
- circuit_send_next_onion_skin(origin_circuit_t *circ)
- {
- tor_assert(circ);
- if (circ->cpath->state == CPATH_STATE_CLOSED) {
- /* Case one: we're on the first hop. */
- return circuit_send_first_onion_skin(circ);
- }
- tor_assert(circ->cpath->state == CPATH_STATE_OPEN);
- tor_assert(circ->base_.state == CIRCUIT_STATE_BUILDING);
- crypt_path_t *hop = onion_next_hop_in_cpath(circ->cpath);
- circuit_build_times_handle_completed_hop(circ);
- if (hop) {
- /* Case two: we're on a hop after the first. */
- return circuit_send_intermediate_onion_skin(circ, hop);
- }
- /* Case three: the circuit is finished. Do housekeeping tasks on it. */
- return circuit_build_no_more_hops(circ);
- }
- /**
- * Called from circuit_send_next_onion_skin() when we find ourselves connected
- * to the first hop in <b>circ</b>: Send a CREATE or CREATE2 or CREATE_FAST
- * cell to that hop. Return 0 on success; -reason on failure (if the circuit
- * should be torn down).
- */
- static int
- circuit_send_first_onion_skin(origin_circuit_t *circ)
- {
- int fast;
- int len;
- const node_t *node;
- create_cell_t cc;
- memset(&cc, 0, sizeof(cc));
- log_debug(LD_CIRC,"First skin; sending create cell.");
- if (circ->build_state->onehop_tunnel) {
- control_event_bootstrap(BOOTSTRAP_STATUS_ONEHOP_CREATE, 0);
- } else {
- control_event_bootstrap(BOOTSTRAP_STATUS_CIRCUIT_CREATE, 0);
- /* If this is not a one-hop tunnel, the channel is being used
- * for traffic that wants anonymity and protection from traffic
- * analysis (such as netflow record retention). That means we want
- * to pad it.
- */
- if (circ->base_.n_chan->channel_usage < CHANNEL_USED_FOR_FULL_CIRCS)
- circ->base_.n_chan->channel_usage = CHANNEL_USED_FOR_FULL_CIRCS;
- }
- node = node_get_by_id(circ->base_.n_chan->identity_digest);
- fast = should_use_create_fast_for_circuit(circ);
- if (!fast) {
- /* 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);
- } else {
- /* We don't know an onion key, so we need to fall back to CREATE_FAST. */
- cc.cell_type = CELL_CREATE_FAST;
- cc.handshake_type = ONION_HANDSHAKE_TYPE_FAST;
- }
- 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>");
- return 0;
- }
- /**
- * Called from circuit_send_next_onion_skin() when we find that we have no
- * more hops: mark the circuit as finished, and perform the necessary
- * bookkeeping. Return 0 on success; -reason on failure (if the circuit
- * should be torn down).
- */
- static int
- circuit_build_no_more_hops(origin_circuit_t *circ)
- {
- guard_usable_t r;
- if (! circ->guard_state) {
- if (circuit_get_cpath_len(circ) != 1 &&
- ! circuit_purpose_may_omit_guard(circ->base_.purpose) &&
- get_options()->UseEntryGuards) {
- log_warn(LD_BUG, "%d-hop circuit %p with purpose %d has no "
- "guard state",
- circuit_get_cpath_len(circ), circ, circ->base_.purpose);
- }
- r = GUARD_USABLE_NOW;
- } else {
- r = entry_guard_succeeded(&circ->guard_state);
- }
- const int is_usable_for_streams = (r == GUARD_USABLE_NOW);
- if (r == GUARD_USABLE_NOW) {
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_OPEN);
- } else if (r == GUARD_MAYBE_USABLE_LATER) {
- // Wait till either a better guard succeeds, or till
- // all better guards fail.
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_GUARD_WAIT);
- } else {
- tor_assert_nonfatal(r == GUARD_USABLE_NEVER);
- return - END_CIRC_REASON_INTERNAL;
- }
- /* XXXX #21422 -- the rest of this branch needs careful thought!
- * Some of the things here need to happen when a circuit becomes
- * mechanically open; some need to happen when it is actually usable.
- * I think I got them right, but more checking would be wise. -NM
- */
- 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);
- if (is_usable_for_streams)
- circuit_has_opened(circ); /* do other actions as necessary */
- if (!have_completed_a_circuit() && !circ->build_state->onehop_tunnel) {
- const or_options_t *options = get_options();
- note_that_we_completed_a_circuit();
- /* FFFF Log a count of known routers here */
- log_notice(LD_GENERAL,
- "Tor has successfully opened a circuit. "
- "Looks like client functionality is working.");
- if (control_event_bootstrap(BOOTSTRAP_STATUS_DONE, 0) == 0) {
- log_notice(LD_GENERAL,
- "Tor has successfully opened a circuit. "
- "Looks like client functionality is working.");
- }
- control_event_client_status(LOG_NOTICE, "CIRCUIT_ESTABLISHED");
- clear_broken_connection_map(1);
- if (server_mode(options) && !check_whether_orport_reachable(options)) {
- 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;
- }
- /**
- * Called from circuit_send_next_onion_skin() when we find that we have a hop
- * other than the first that we need to extend to: use <b>hop</b>'s
- * information to extend the circuit another step. Return 0 on success;
- * -reason on failure (if the circuit should be torn down).
- */
- static int
- circuit_send_intermediate_onion_skin(origin_circuit_t *circ,
- crypt_path_t *hop)
- {
- int len;
- extend_cell_t ec;
- memset(&ec, 0, sizeof(ec));
- log_debug(LD_CIRC,"starting to send subsequent skin.");
- 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;
- }
- circuit_pick_extend_handshake(&ec.cell_type,
- &ec.create_cell.cell_type,
- &ec.create_cell.handshake_type,
- 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);
- /* Set the ED25519 identity too -- it will only get included
- * in the extend2 cell if we're configured to use it, though. */
- ed25519_pubkey_copy(&ec.ed_pubkey, &hop->extend_info->ed_identity);
- 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.");
- {
- 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 that relay 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);
- /* so we log when it works again */
- note_that_we_maybe_cant_complete_circuits();
- control_event_client_status(severity, "CIRCUIT_NOT_ESTABLISHED REASON=%s",
- "CLOCK_JUMPED");
- circuit_mark_all_unused_circs();
- circuit_mark_all_dirty_circs_as_unusable();
- if (seconds_elapsed < 0) {
- /* Restart all the timers in case we jumped a long way into the past. */
- reset_all_main_loop_timers();
- }
- }
- /** 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 clients 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;
- }
- /* Fill in ed_pubkey if it was not provided and we can infer it from
- * our networkstatus */
- if (ed25519_public_key_is_zero(&ec.ed_pubkey)) {
- const node_t *node = node_get_by_id((const char*)ec.node_id);
- const ed25519_public_key_t *node_ed_id = NULL;
- if (node &&
- node_supports_ed25519_link_authentication(node, 1) &&
- (node_ed_id = node_get_ed25519_id(node))) {
- ed25519_pubkey_copy(&ec.ed_pubkey, node_ed_id);
- }
- }
- /* 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;
- }
- /* Check the previous hop Ed25519 ID too */
- if (! ed25519_public_key_is_zero(&ec.ed_pubkey) &&
- ed25519_pubkey_eq(&ec.ed_pubkey,
- &TO_OR_CIRCUIT(circ)->p_chan->ed25519_identity)) {
- log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
- "Client asked me to extend back to the previous hop "
- "(by Ed25519 ID).");
- }
- n_chan = channel_get_for_extend((const char*)ec.node_id,
- &ec.ed_pubkey,
- &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,
- &ec.ed_pubkey,
- 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,
- &ec.ed_pubkey);
- 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.
- *
- * If <b>is_hs_v3</b> is set, this cpath will be used for next gen hidden
- * service circuits and <b>key_data</b> must be at least
- * HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN bytes in length.
- *
- * If <b>is_hs_v3</b> is not set, key_data must contain CPATH_KEY_MATERIAL_LEN
- * 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.)
- *
- * Return 0 if init was successful, else -1 if it failed.
- */
- int
- circuit_init_cpath_crypto(crypt_path_t *cpath,
- const char *key_data, size_t key_data_len,
- int reverse, int is_hs_v3)
- {
- crypto_digest_t *tmp_digest;
- crypto_cipher_t *tmp_crypto;
- size_t digest_len = 0;
- size_t cipher_key_len = 0;
- tor_assert(cpath);
- tor_assert(key_data);
- tor_assert(!(cpath->f_crypto || cpath->b_crypto ||
- cpath->f_digest || cpath->b_digest));
- /* Basic key size validation */
- if (is_hs_v3 && BUG(key_data_len != HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN)) {
- return -1;
- } else if (!is_hs_v3 && BUG(key_data_len != CPATH_KEY_MATERIAL_LEN)) {
- return -1;
- }
- /* If we are using this cpath for next gen onion services use SHA3-256,
- otherwise use good ol' SHA1 */
- if (is_hs_v3) {
- digest_len = DIGEST256_LEN;
- cipher_key_len = CIPHER256_KEY_LEN;
- cpath->f_digest = crypto_digest256_new(DIGEST_SHA3_256);
- cpath->b_digest = crypto_digest256_new(DIGEST_SHA3_256);
- } else {
- digest_len = DIGEST_LEN;
- cipher_key_len = CIPHER_KEY_LEN;
- cpath->f_digest = crypto_digest_new();
- cpath->b_digest = crypto_digest_new();
- }
- tor_assert(digest_len != 0);
- tor_assert(cipher_key_len != 0);
- const int cipher_key_bits = (int) cipher_key_len * 8;
- crypto_digest_add_bytes(cpath->f_digest, key_data, digest_len);
- crypto_digest_add_bytes(cpath->b_digest, key_data+digest_len, digest_len);
- cpath->f_crypto = crypto_cipher_new_with_bits(key_data+(2*digest_len),
- cipher_key_bits);
- if (!cpath->f_crypto) {
- log_warn(LD_BUG,"Forward cipher initialization failed.");
- return -1;
- }
- cpath->b_crypto = crypto_cipher_new_with_bits(
- key_data+(2*digest_len)+cipher_key_len,
- cipher_key_bits);
- if (!cpath->b_crypto) {
- 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;
- }
- /** 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) {
- log_warn(LD_CIRC, "pathbias_count_build_attempt failed: %d", rv);
- 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);
- {
- const char *msg = NULL;
- 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,
- &msg) < 0) {
- if (msg)
- log_warn(LD_CIRC,"onion_skin_client_handshake failed: %s", msg);
- return -END_CIRC_REASON_TORPROTOCOL;
- }
- }
- onion_handshake_state_release(&hop->handshake_state);
- if (circuit_init_cpath_crypto(hop, keys, sizeof(keys), 0, 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 /* 0 */
- }
- /** 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, size_t keys_len,
- const uint8_t *rend_circ_nonce)
- {
- cell_t cell;
- crypt_path_t *tmp_cpath;
- tor_assert(keys_len == CPATH_KEY_MATERIAL_LEN);
- 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, keys_len, 0, 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);
- int used_create_fast = (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.",
- used_create_fast ? "created_fast" : "created");
- /* Ignore the local bit when ExtendAllowPrivateAddresses is set:
- * it violates the assumption that private addresses are local.
- * Also, many test networks run on local addresses, and
- * TestingTorNetwork sets ExtendAllowPrivateAddresses. */
- if ((!channel_is_local(circ->p_chan)
- || get_options()->ExtendAllowPrivateAddresses)
- && !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;
- }
- /** Helper for new_route_len(). Choose a circuit length for purpose
- * <b>purpose</b>: DEFAULT_ROUTE_LEN (+ 1 if someone else chose the
- * exit). If someone else chose the exit, they could be colluding
- * with the exit, so add a randomly selected node to preserve
- * anonymity.
- *
- * Here, "exit node" sometimes means an OR acting as an internal
- * endpoint, rather than as a relay to an external endpoint. This
- * means there need to be at least DEFAULT_ROUTE_LEN routers between
- * us and the internal endpoint to preserve the same anonymity
- * properties that we would get when connecting to an external
- * endpoint. These internal endpoints can include:
- *
- * - Connections to a directory of hidden services
- * (CIRCUIT_PURPOSE_C_GENERAL)
- *
- * - A client connecting to an introduction point, which the hidden
- * service picked (CIRCUIT_PURPOSE_C_INTRODUCING, via
- * circuit_get_open_circ_or_launch() which rewrites it from
- * CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT)
- *
- * - A hidden service connecting to a rendezvous point, which the
- * client picked (CIRCUIT_PURPOSE_S_CONNECT_REND, via
- * rend_service_receive_introduction() and
- * rend_service_relaunch_rendezvous)
- *
- * There are currently two situations where we picked the exit node
- * ourselves, making DEFAULT_ROUTE_LEN a safe circuit length:
- *
- * - We are a hidden service connecting to an introduction point
- * (CIRCUIT_PURPOSE_S_ESTABLISH_INTRO, via
- * rend_service_launch_establish_intro())
- *
- * - We are a router testing its own reachabiity
- * (CIRCUIT_PURPOSE_TESTING, via consider_testing_reachability())
- *
- * onion_pick_cpath_exit() bypasses us (by not calling
- * new_route_len()) in the one-hop tunnel case, so we don't need to
- * handle that.
- */
- int
- route_len_for_purpose(uint8_t purpose, extend_info_t *exit_ei)
- {
- int routelen = DEFAULT_ROUTE_LEN;
- int known_purpose = 0;
- if (circuit_should_use_vanguards(purpose)) {
- /* Clients want an extra hop for rends to avoid linkability.
- * Services want it for intro points to avoid publishing their
- * layer3 guards. They want it for hsdir posts to use
- * their full layer3 guard set for those connections.
- * Ex: C - G - L2 - L3 - R
- * S - G - L2 - L3 - HSDIR
- * S - G - L2 - L3 - I
- */
- if (purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND ||
- purpose == CIRCUIT_PURPOSE_S_HSDIR_POST ||
- purpose == CIRCUIT_PURPOSE_HS_VANGUARDS ||
- purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO)
- return routelen+1;
- /* If we only have Layer2 vanguards, then we do not need
- * the extra hop for linkabilty reasons (see below).
- * This means all hops can be of the form:
- * S/C - G - L2 - M - R/HSDir/I
- */
- if (get_options()->HSLayer2Nodes && !get_options()->HSLayer3Nodes)
- return routelen+1;
- /* For connections to hsdirs, clients want two extra hops
- * when using layer3 guards, to avoid linkability.
- * Same goes for intro points. Note that the route len
- * includes the intro point or hsdir, hence the +2.
- * Ex: C - G - L2 - L3 - M - I
- * C - G - L2 - L3 - M - HSDIR
- * S - G - L2 - L3 - M - R
- */
- if (purpose == CIRCUIT_PURPOSE_S_CONNECT_REND ||
- purpose == CIRCUIT_PURPOSE_C_HSDIR_GET ||
- purpose == CIRCUIT_PURPOSE_C_INTRODUCING)
- return routelen+2;
- }
- if (!exit_ei)
- return routelen;
- switch (purpose) {
- /* These two purposes connect to a router that we chose, so
- * DEFAULT_ROUTE_LEN is safe. */
- case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:
- /* hidden service connecting to introduction point */
- case CIRCUIT_PURPOSE_TESTING:
- /* router reachability testing */
- known_purpose = 1;
- break;
- /* These three purposes connect to a router that someone else
- * might have chosen, so add an extra hop to protect anonymity. */
- case CIRCUIT_PURPOSE_C_GENERAL:
- case CIRCUIT_PURPOSE_C_HSDIR_GET:
- case CIRCUIT_PURPOSE_S_HSDIR_POST:
- /* connecting to hidden service directory */
- case CIRCUIT_PURPOSE_C_INTRODUCING:
- /* client connecting to introduction point */
- case CIRCUIT_PURPOSE_S_CONNECT_REND:
- /* hidden service connecting to rendezvous point */
- known_purpose = 1;
- routelen++;
- break;
- default:
- /* Got a purpose not listed above along with a chosen exit.
- * Increase the circuit length by one anyway for safety. */
- routelen++;
- break;
- }
- if (BUG(exit_ei && !known_purpose)) {
- log_warn(LD_BUG, "Unhandled purpose %d with a chosen exit; "
- "assuming routelen %d.", purpose, routelen);
- }
- return routelen;
- }
- /** Choose a length for a circuit of purpose <b>purpose</b> and check
- * if enough routers are available.
- *
- * If the routerlist <b>nodes</b> doesn't have enough routers
- * to handle the desired path length, return -1.
- */
- STATIC int
- new_route_len(uint8_t purpose, extend_info_t *exit_ei, smartlist_t *nodes)
- {
- int num_acceptable_routers;
- int routelen;
- tor_assert(nodes);
- routelen = route_len_for_purpose(purpose, exit_ei);
- 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 < routelen) {
- log_info(LD_CIRC,
- "Not enough acceptable routers (%d/%d). Discarding this circuit.",
- num_acceptable_routers, routelen);
- return -1;
- }
- 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.
- */
- MOCK_IMPL(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 *selected_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_calloc(smartlist_len(the_nodes), sizeof(int));
- 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)) {
- /* 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 */
- }
- /* We do not allow relays that allow single hop exits by default. Option
- * was deprecated in 0.2.9.2-alpha and removed in 0.3.1.0-alpha. */
- if (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);
- });
- selected_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);
- selected_node = node_sl_choose_by_bandwidth(supporting, WEIGHT_FOR_EXIT);
- if (selected_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 (selected_node) {
- log_info(LD_CIRC, "Chose exit server '%s'", node_describe(selected_node));
- return selected_node;
- }
- if (options->ExitNodes) {
- log_warn(LD_CIRC,
- "No exits in ExitNodes%s seem to be running: "
- "can't choose an exit.",
- options->ExcludeExitNodesUnion_ ?
- ", except possibly those excluded by your configuration, " : "");
- }
- return NULL;
- }
- #if defined(ENABLE_TOR2WEB_MODE) || defined(TOR_UNIT_TESTS)
- /* The config option Tor2webRendezvousPoints has been set and we need
- * to pick an RP out of that set. Make sure that the RP we choose is
- * alive, and return it. Return NULL if no usable RP could be found in
- * Tor2webRendezvousPoints. */
- STATIC const node_t *
- pick_tor2web_rendezvous_node(router_crn_flags_t flags,
- const or_options_t *options)
- {
- const node_t *rp_node = NULL;
- const int need_desc = (flags & CRN_NEED_DESC) != 0;
- const int pref_addr = (flags & CRN_PREF_ADDR) != 0;
- const int direct_conn = (flags & CRN_DIRECT_CONN) != 0;
- smartlist_t *whitelisted_live_rps = smartlist_new();
- smartlist_t *all_live_nodes = smartlist_new();
- tor_assert(options->Tor2webRendezvousPoints);
- /* Add all running nodes to all_live_nodes */
- router_add_running_nodes_to_smartlist(all_live_nodes,
- 0, 0, 0,
- need_desc,
- pref_addr,
- direct_conn);
- /* Filter all_live_nodes to only add live *and* whitelisted RPs to
- * the list whitelisted_live_rps. */
- SMARTLIST_FOREACH_BEGIN(all_live_nodes, node_t *, live_node) {
- if (routerset_contains_node(options->Tor2webRendezvousPoints, live_node)) {
- smartlist_add(whitelisted_live_rps, live_node);
- }
- } SMARTLIST_FOREACH_END(live_node);
- /* Honor ExcludeNodes */
- if (options->ExcludeNodes) {
- routerset_subtract_nodes(whitelisted_live_rps, options->ExcludeNodes);
- }
- /* Now pick randomly amongst the whitelisted RPs. No need to waste time
- doing bandwidth load balancing, for most use cases
- 'whitelisted_live_rps' contains a single OR anyway. */
- rp_node = smartlist_choose(whitelisted_live_rps);
- if (!rp_node) {
- log_warn(LD_REND, "Could not find a Rendezvous Point that suits "
- "the purposes of Tor2webRendezvousPoints. Choosing random one.");
- }
- smartlist_free(whitelisted_live_rps);
- smartlist_free(all_live_nodes);
- return rp_node;
- }
- #endif /* defined(ENABLE_TOR2WEB_MODE) || defined(TOR_UNIT_TESTS) */
- /* Pick a Rendezvous Point for our HS circuits according to <b>flags</b>. */
- static const node_t *
- pick_rendezvous_node(router_crn_flags_t flags)
- {
- const or_options_t *options = get_options();
- #ifdef ENABLE_TOR2WEB_MODE
- /* We want to connect directly to the node if we can */
- router_crn_flags_t direct_flags = flags;
- direct_flags |= CRN_PREF_ADDR;
- direct_flags |= CRN_DIRECT_CONN;
- /* The user wants us to pick specific RPs. */
- if (options->Tor2webRendezvousPoints) {
- const node_t *tor2web_rp = pick_tor2web_rendezvous_node(direct_flags,
- options);
- if (tor2web_rp) {
- return tor2web_rp;
- }
- }
- /* Else, if no direct, preferred tor2web RP was found, fall back to choosing
- * a random direct node */
- const node_t *node = router_choose_random_node(NULL, options->ExcludeNodes,
- direct_flags);
- /* Return the direct node (if found), or log a message and fall back to an
- * indirect connection. */
- if (node) {
- return node;
- } else {
- log_info(LD_REND,
- "Unable to find a random rendezvous point that is reachable via "
- "a direct connection, falling back to a 3-hop path.");
- }
- #endif /* defined(ENABLE_TOR2WEB_MODE) */
- return router_choose_random_node(NULL, options->ExcludeNodes, flags);
- }
- /*
- * Helper function to pick a configured restricted middle node
- * (either HSLayer2Nodes or HSLayer3Nodes).
- *
- * Make sure that the node we chose is alive, and not excluded,
- * and return it.
- *
- * The exclude_set is a routerset of nodes that the selected node
- * must not match, and the exclude_list is a simple list of nodes
- * that the selected node must not be in. Either or both may be
- * NULL.
- *
- * Return NULL if no usable nodes could be found. */
- static const node_t *
- pick_restricted_middle_node(router_crn_flags_t flags,
- const routerset_t *pick_from,
- const routerset_t *exclude_set,
- const smartlist_t *exclude_list,
- int position_hint)
- {
- const node_t *middle_node = NULL;
- smartlist_t *whitelisted_live_middles = smartlist_new();
- smartlist_t *all_live_nodes = smartlist_new();
- tor_assert(pick_from);
- /* Add all running nodes to all_live_nodes */
- router_add_running_nodes_to_smartlist(all_live_nodes,
- (flags & CRN_NEED_UPTIME) != 0,
- (flags & CRN_NEED_CAPACITY) != 0,
- (flags & CRN_NEED_GUARD) != 0,
- (flags & CRN_NEED_DESC) != 0,
- (flags & CRN_PREF_ADDR) != 0,
- (flags & CRN_DIRECT_CONN) != 0);
- /* Filter all_live_nodes to only add live *and* whitelisted middles
- * to the list whitelisted_live_middles. */
- SMARTLIST_FOREACH_BEGIN(all_live_nodes, node_t *, live_node) {
- if (routerset_contains_node(pick_from, live_node)) {
- smartlist_add(whitelisted_live_middles, live_node);
- }
- } SMARTLIST_FOREACH_END(live_node);
- /* Honor ExcludeNodes */
- if (exclude_set) {
- routerset_subtract_nodes(whitelisted_live_middles, exclude_set);
- }
- if (exclude_list) {
- smartlist_subtract(whitelisted_live_middles, exclude_list);
- }
- /**
- * Max number of restricted nodes before we alert the user and try
- * to load balance for them.
- *
- * The most aggressive vanguard design had 16 nodes at layer3.
- * Let's give a small ceiling above that. */
- #define MAX_SANE_RESTRICTED_NODES 20
- /* If the user (or associated tor controller) selected only a few nodes,
- * assume they took load balancing into account and don't do it for them.
- *
- * If there are a lot of nodes in here, assume they did not load balance
- * and do it for them, but also warn them that they may be Doing It Wrong.
- */
- if (smartlist_len(whitelisted_live_middles) <=
- MAX_SANE_RESTRICTED_NODES) {
- middle_node = smartlist_choose(whitelisted_live_middles);
- } else {
- static ratelim_t pinned_notice_limit = RATELIM_INIT(24*3600);
- log_fn_ratelim(&pinned_notice_limit, LOG_NOTICE, LD_CIRC,
- "Your _HSLayer%dNodes setting has resulted "
- "in %d total nodes. This is a lot of nodes. "
- "You may want to consider using a Tor controller "
- "to select and update a smaller set of nodes instead.",
- position_hint, smartlist_len(whitelisted_live_middles));
- /* NO_WEIGHTING here just means don't take node flags into account
- * (ie: use consensus measurement only). This is done so that
- * we don't further surprise the user by not using Exits that they
- * specified at all */
- middle_node = node_sl_choose_by_bandwidth(whitelisted_live_middles,
- NO_WEIGHTING);
- }
- smartlist_free(whitelisted_live_middles);
- smartlist_free(all_live_nodes);
- return middle_node;
- }
- /** 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(origin_circuit_t *circ, int need_uptime,
- int need_capacity, int is_internal, int need_hs_v3)
- {
- 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;
- if (need_hs_v3)
- flags |= CRN_RENDEZVOUS_V3;
- switch (TO_CIRCUIT(circ)->purpose) {
- case CIRCUIT_PURPOSE_C_HSDIR_GET:
- case CIRCUIT_PURPOSE_S_HSDIR_POST:
- case CIRCUIT_PURPOSE_HS_VANGUARDS:
- /* For these three, we want to pick the exit like a middle hop,
- * since it should be random. */
- tor_assert_nonfatal(is_internal);
- /* Falls through */
- case CIRCUIT_PURPOSE_C_GENERAL:
- 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:
- {
- /* Pick a new RP */
- const node_t *rendezvous_node = pick_rendezvous_node(flags);
- log_info(LD_REND, "Picked new RP: %s",
- safe_str_client(node_describe(rendezvous_node)));
- return rendezvous_node;
- }
- }
- log_warn(LD_BUG,"Unhandled purpose %d", TO_CIRCUIT(circ)->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_ei)
- {
- 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_S_HSDIR_POST:
- case CIRCUIT_PURPOSE_C_HSDIR_GET:
- 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_ei)) {
- /* 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_ei),
- 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_ei),
- 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.
- *
- * If <b>is_hs_v3_rp_circuit</b> is set, then this exit should be suitable to
- * be used as an HS v3 rendezvous point.
- *
- * Return 0 if ok, -1 if circuit should be closed. */
- static int
- onion_pick_cpath_exit(origin_circuit_t *circ, extend_info_t *exit_ei,
- int is_hs_v3_rp_circuit)
- {
- cpath_build_state_t *state = circ->build_state;
- if (state->onehop_tunnel) {
- log_debug(LD_CIRC, "Launching a one-hop circuit for dir tunnel%s.",
- (rend_allow_non_anonymous_connection(get_options()) ?
- ", or intro or rendezvous connection" : ""));
- state->desired_path_len = 1;
- } else {
- int r = new_route_len(circ->base_.purpose, exit_ei, nodelist_get_list());
- if (r < 1) /* must be at least 1 */
- return -1;
- state->desired_path_len = r;
- }
- if (exit_ei) { /* the circuit-builder pre-requested one */
- warn_if_last_router_excluded(circ, exit_ei);
- log_info(LD_CIRC,"Using requested exit node '%s'",
- extend_info_describe(exit_ei));
- exit_ei = extend_info_dup(exit_ei);
- } else { /* we have to decide one */
- const node_t *node =
- choose_good_exit_server(circ, state->need_uptime,
- state->need_capacity, state->is_internal,
- is_hs_v3_rp_circuit);
- if (!node) {
- log_warn(LD_CIRC,"Failed to choose an exit server");
- return -1;
- }
- exit_ei = extend_info_from_node(node, 0);
- if (BUG(exit_ei == NULL))
- return -1;
- }
- state->chosen_exit = exit_ei;
- 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_ei)
- {
- cpath_build_state_t *state;
- tor_assert(exit_ei);
- tor_assert(circ);
- state = circ->build_state;
- tor_assert(state);
- extend_info_free(state->chosen_exit);
- state->chosen_exit = extend_info_dup(exit_ei);
- ++circ->build_state->desired_path_len;
- onion_append_hop(&circ->cpath, exit_ei);
- 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_ei)
- {
- int err_reason = 0;
- warn_if_last_router_excluded(circ, exit_ei);
- tor_gettimeofday(&circ->base_.timestamp_began);
- circuit_append_new_exit(circ, exit_ei);
- 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_ei));
- 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.
- */
- MOCK_IMPL(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;
- /* The node has a descriptor, so we can just check the ntor key directly */
- if (!node_has_curve25519_onion_key(node))
- continue;
- ++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;
- }
- }
- #ifdef TOR_UNIT_TESTS
- /** Unittest helper function: Count number of hops in cpath linked list. */
- unsigned int
- cpath_get_n_hops(crypt_path_t **head_ptr)
- {
- unsigned int n_hops = 0;
- crypt_path_t *tmp;
- if (!*head_ptr) {
- return 0;
- }
- tmp = *head_ptr;
- do {
- n_hops++;
- tmp = tmp->next;
- } while (tmp != *head_ptr);
- return n_hops;
- }
- #endif /* defined(TOR_UNIT_TESTS) */
- /**
- * Build a list of nodes to exclude from the choice of this middle
- * hop, based on already chosen nodes.
- *
- * XXX: At present, this function does not exclude any nodes from
- * the vanguard circuits. See
- * https://trac.torproject.org/projects/tor/ticket/24487
- */
- static smartlist_t *
- build_middle_exclude_list(uint8_t purpose,
- cpath_build_state_t *state,
- crypt_path_t *head,
- int cur_len)
- {
- smartlist_t *excluded;
- const node_t *r;
- crypt_path_t *cpath;
- int i;
- excluded = smartlist_new();
- /* Add the exit to the exclude list (note that the exit/last hop is always
- * chosen first in circuit_establish_circuit()). */
- if ((r = build_state_get_exit_node(state))) {
- nodelist_add_node_and_family(excluded, r);
- }
- /* XXX: We don't apply any other previously selected node restrictions for
- * vanguards, and allow nodes to be reused for those hop positions in the
- * same circuit. This is because after many rotations, you get to learn
- * inner guard nodes through the nodes that are not selected for outer
- * hops.
- *
- * The alternative is building the circuit in reverse. Reverse calls to
- * onion_extend_cpath() (ie: select outer hops first) would then have the
- * property that you don't gain information about inner hops by observing
- * outer ones. See https://trac.torproject.org/projects/tor/ticket/24487
- * for this.
- *
- * (Note further that we can and do still exclude the exit in the block
- * above, because it is chosen first in circuit_establish_circuit()..) */
- if (circuit_should_use_vanguards(purpose)) {
- return excluded;
- }
- for (i = 0, cpath = head; cpath && 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);
- }
- }
- return excluded;
- }
- /** Return true if we MUST use vanguards for picking this middle node. */
- static int
- middle_node_must_be_vanguard(const or_options_t *options,
- uint8_t purpose, int cur_len)
- {
- /* If this is not a hidden service circuit, don't use vanguards */
- if (!circuit_purpose_is_hidden_service(purpose)) {
- return 0;
- }
- /* If we have sticky L2 nodes, and this is an L2 pick, use vanguards */
- if (options->HSLayer2Nodes && cur_len == 1) {
- return 1;
- }
- /* If we have sticky L3 nodes, and this is an L3 pick, use vanguards */
- if (options->HSLayer3Nodes && cur_len == 2) {
- return 1;
- }
- return 0;
- }
- /** Pick a sticky vanguard middle node or return NULL if not found.
- * See doc of pick_restricted_middle_node() for argument details. */
- static const node_t *
- pick_vanguard_middle_node(const or_options_t *options,
- router_crn_flags_t flags, int cur_len,
- const smartlist_t *excluded)
- {
- const routerset_t *vanguard_routerset = NULL;
- const node_t *node = NULL;
- /* Pick the right routerset based on the current hop */
- if (cur_len == 1) {
- vanguard_routerset = options->HSLayer2Nodes;
- } else if (cur_len == 2) {
- vanguard_routerset = options->HSLayer3Nodes;
- } else {
- /* guaranteed by middle_node_should_be_vanguard() */
- tor_assert_nonfatal_unreached();
- return NULL;
- }
- node = pick_restricted_middle_node(flags, vanguard_routerset,
- options->ExcludeNodes, excluded,
- cur_len+1);
- if (!node) {
- static ratelim_t pinned_warning_limit = RATELIM_INIT(300);
- log_fn_ratelim(&pinned_warning_limit, LOG_WARN, LD_CIRC,
- "Could not find a node that matches the configured "
- "_HSLayer%dNodes set", cur_len+1);
- }
- return node;
- }
- /** 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)
- {
- const node_t *choice;
- 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 #%d: random choice.",
- cur_len+1);
- excluded = build_middle_exclude_list(purpose, state, head, cur_len);
- if (state->need_uptime)
- flags |= CRN_NEED_UPTIME;
- if (state->need_capacity)
- flags |= CRN_NEED_CAPACITY;
- /** If a hidden service circuit wants a specific middle node, pin it. */
- if (middle_node_must_be_vanguard(options, purpose, cur_len)) {
- log_debug(LD_GENERAL, "Picking a sticky node (cur_len = %d)", cur_len);
- return pick_vanguard_middle_node(options, flags, cur_len, excluded);
- }
- 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.
- *
- * Set *<b>guard_state_out</b> to information about the guard that
- * we're selecting, which we'll use later to remember whether the
- * guard worked or not.
- */
- const node_t *
- choose_good_entry_server(uint8_t purpose, cpath_build_state_t *state,
- circuit_guard_state_t **guard_state_out)
- {
- const node_t *choice;
- smartlist_t *excluded;
- const or_options_t *options = get_options();
- /* If possible, choose an entry server with a preferred address,
- * otherwise, choose one with an allowed address */
- router_crn_flags_t flags = (CRN_NEED_GUARD|CRN_NEED_DESC|CRN_PREF_ADDR|
- CRN_DIRECT_CONN);
- const node_t *node;
- /* Once we used this function to select a node to be a guard. We had
- * 'state == NULL' be the signal for that. But we don't do that any more.
- */
- tor_assert_nonfatal(state);
- 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. */
- tor_assert(guard_state_out);
- return guards_choose_guard(state, guard_state_out);
- }
- 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 (state) {
- if (state->need_uptime)
- flags |= CRN_NEED_UPTIME;
- if (state->need_capacity)
- flags |= CRN_NEED_CAPACITY;
- }
- 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.
- *
- * Return 1 if the path is complete, 0 if we successfully added a hop,
- * and -1 on error.
- */
- 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,
- &circ->guard_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. Servers always want the primary (IPv4) address. */
- int client = (server_mode(get_options()) == 0);
- info = extend_info_from_node(r, client);
- /* Clients can fail to find an allowed address */
- tor_assert_nonfatal(info || client);
- }
- } 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_nonfatal(info);
- }
- }
- if (!info) {
- log_warn(LD_CIRC,"Failed to find node for hop #%d of our path. Discarding "
- "this circuit.", cur_len+1);
- 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 *rsa_id_digest,
- const ed25519_public_key_t *ed_id,
- crypto_pk_t *onion_key,
- const curve25519_public_key_t *ntor_key,
- const tor_addr_t *addr, uint16_t port)
- {
- extend_info_t *info = tor_malloc_zero(sizeof(extend_info_t));
- memcpy(info->identity_digest, rsa_id_digest, DIGEST_LEN);
- if (ed_id && !ed25519_public_key_is_zero(ed_id))
- memcpy(&info->ed_identity, ed_id, sizeof(ed25519_public_key_t));
- if (nickname)
- strlcpy(info->nickname, nickname, sizeof(info->nickname));
- if (onion_key)
- info->onion_key = crypto_pk_dup_key(onion_key);
- if (ntor_key)
- memcpy(&info->curve25519_onion_key, ntor_key,
- sizeof(curve25519_public_key_t));
- 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, or if for_direct_connect is true and none of
- * the node's addresses are allowed by tor's firewall and IP version config.
- **/
- extend_info_t *
- extend_info_from_node(const node_t *node, int for_direct_connect)
- {
- tor_addr_port_t ap;
- int valid_addr = 0;
- if (node->ri == NULL && (node->rs == NULL || node->md == NULL))
- return NULL;
- /* Choose a preferred address first, but fall back to an allowed address.
- * choose_address returns 1 on success, but get_prim_orport returns 0. */
- if (for_direct_connect)
- valid_addr = fascist_firewall_choose_address_node(node,
- FIREWALL_OR_CONNECTION,
- 0, &ap);
- else
- valid_addr = !node_get_prim_orport(node, &ap);
- if (valid_addr)
- log_debug(LD_CIRC, "using %s for %s",
- fmt_addrport(&ap.addr, ap.port),
- node->ri ? node->ri->nickname : node->rs->nickname);
- else
- log_warn(LD_CIRC, "Could not choose valid address for %s",
- node->ri ? node->ri->nickname : node->rs->nickname);
- /* Every node we connect or extend to must support ntor */
- if (!node_has_curve25519_onion_key(node)) {
- log_fn(LOG_PROTOCOL_WARN, LD_CIRC,
- "Attempted to create extend_info for a node that does not support "
- "ntor: %s", node_describe(node));
- return NULL;
- }
- const ed25519_public_key_t *ed_pubkey = NULL;
- /* Don't send the ed25519 pubkey unless the target node actually supports
- * authenticating with it. */
- if (node_supports_ed25519_link_authentication(node, 0)) {
- log_info(LD_CIRC, "Including Ed25519 ID for %s", node_describe(node));
- ed_pubkey = node_get_ed25519_id(node);
- } else if (node_get_ed25519_id(node)) {
- log_info(LD_CIRC, "Not including the ed25519 ID for %s, since it won't "
- "be able to authenticate it.",
- node_describe(node));
- }
- /* Retrieve the curve25519 pubkey. */
- const curve25519_public_key_t *curve_pubkey =
- node_get_curve25519_onion_key(node);
- if (valid_addr && node->ri)
- return extend_info_new(node->ri->nickname,
- node->identity,
- ed_pubkey,
- node->ri->onion_pkey,
- curve_pubkey,
- &ap.addr,
- ap.port);
- else if (valid_addr && node->rs && node->md)
- return extend_info_new(node->rs->nickname,
- node->identity,
- ed_pubkey,
- node->md->onion_pkey,
- curve_pubkey,
- &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 node_t for the chosen exit router in <b>state</b>.
- * If there is no chosen exit, or if we don't know the node_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 RSA ID digest for the chosen exit router in <b>state</b>.
- * If there is no chosen exit, return NULL.
- */
- const uint8_t *
- build_state_get_exit_rsa_id(cpath_build_state_t *state)
- {
- if (!state || !state->chosen_exit)
- return NULL;
- return (const uint8_t *) 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;
- }
- /** Return true iff the given address can be used to extend to. */
- int
- extend_info_addr_is_allowed(const tor_addr_t *addr)
- {
- tor_assert(addr);
- /* Check if we have a private address and if we can extend to it. */
- if ((tor_addr_is_internal(addr, 0) || tor_addr_is_multicast(addr)) &&
- !get_options()->ExtendAllowPrivateAddresses) {
- goto disallow;
- }
- /* Allowed! */
- return 1;
- disallow:
- return 0;
- }
- /* Does ei have a valid TAP key? */
- int
- extend_info_supports_tap(const extend_info_t* ei)
- {
- tor_assert(ei);
- /* Valid TAP keys are not NULL */
- return ei->onion_key != NULL;
- }
- /* Does ei have a valid ntor key? */
- int
- extend_info_supports_ntor(const extend_info_t* ei)
- {
- tor_assert(ei);
- /* Valid ntor keys have at least one non-zero byte */
- return !tor_mem_is_zero(
- (const char*)ei->curve25519_onion_key.public_key,
- CURVE25519_PUBKEY_LEN);
- }
- /* Is circuit purpose allowed to use the deprecated TAP encryption protocol?
- * The hidden service protocol still uses TAP for some connections, because
- * ntor onion keys aren't included in HS descriptors or INTRODUCE cells. */
- static int
- circuit_purpose_can_use_tap_impl(uint8_t purpose)
- {
- return (purpose == CIRCUIT_PURPOSE_S_CONNECT_REND ||
- purpose == CIRCUIT_PURPOSE_C_INTRODUCING);
- }
- /* Is circ allowed to use the deprecated TAP encryption protocol?
- * The hidden service protocol still uses TAP for some connections, because
- * ntor onion keys aren't included in HS descriptors or INTRODUCE cells. */
- int
- circuit_can_use_tap(const origin_circuit_t *circ)
- {
- tor_assert(circ);
- tor_assert(circ->cpath);
- tor_assert(circ->cpath->extend_info);
- return (circuit_purpose_can_use_tap_impl(circ->base_.purpose) &&
- extend_info_supports_tap(circ->cpath->extend_info));
- }
- /* Does circ have an onion key which it's allowed to use? */
- int
- circuit_has_usable_onion_key(const origin_circuit_t *circ)
- {
- tor_assert(circ);
- tor_assert(circ->cpath);
- tor_assert(circ->cpath->extend_info);
- return (extend_info_supports_ntor(circ->cpath->extend_info) ||
- circuit_can_use_tap(circ));
- }
- /* Does ei have an onion key which it would prefer to use?
- * Currently, we prefer ntor keys*/
- int
- extend_info_has_preferred_onion_key(const extend_info_t* ei)
- {
- tor_assert(ei);
- return extend_info_supports_ntor(ei);
- }
- /** Find the circuits that are waiting to find out whether their guards are
- * usable, and if any are ready to become usable, mark them open and try
- * attaching streams as appropriate. */
- void
- circuit_upgrade_circuits_from_guard_wait(void)
- {
- smartlist_t *to_upgrade =
- circuit_find_circuits_to_upgrade_from_guard_wait();
- if (to_upgrade == NULL)
- return;
- log_info(LD_GUARD, "Upgrading %d circuits from 'waiting for better guard' "
- "to 'open'.", smartlist_len(to_upgrade));
- SMARTLIST_FOREACH_BEGIN(to_upgrade, origin_circuit_t *, circ) {
- circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_OPEN);
- circuit_has_opened(circ);
- } SMARTLIST_FOREACH_END(circ);
- smartlist_free(to_upgrade);
- }
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