[tor-commits] [tor/master] Merge branch 'bug24895_031_02' into bug24895_032_02

nickm at torproject.org nickm at torproject.org
Fri Jan 19 21:32:22 UTC 2018


commit f870f9c8bcdbf2f8fd1c1e1feb9f88dc111ab25a
Merge: 44388757c f98f7ca89
Author: David Goulet <dgoulet at torproject.org>
Date:   Fri Jan 19 16:26:26 2018 -0500

    Merge branch 'bug24895_031_02' into bug24895_032_02

 changes/bug24895     |  8 ++++++++
 src/or/hs_circuit.c  |  7 ++++++-
 src/or/hs_common.c   | 17 +++++++++++++++++
 src/or/hs_common.h   |  2 ++
 src/or/rendservice.c |  4 ++--
 5 files changed, 35 insertions(+), 3 deletions(-)

diff --cc src/or/hs_circuit.c
index 11ce2a188,000000000..66c59e0dc
mode 100644,000000..100644
--- a/src/or/hs_circuit.c
+++ b/src/or/hs_circuit.c
@@@ -1,1208 -1,0 +1,1213 @@@
 +/* Copyright (c) 2017, The Tor Project, Inc. */
 +/* See LICENSE for licensing information */
 +
 +/**
 + * \file hs_circuit.c
 + **/
 +
 +#define HS_CIRCUIT_PRIVATE
 +
 +#include "or.h"
 +#include "circpathbias.h"
 +#include "circuitbuild.h"
 +#include "circuitlist.h"
 +#include "circuituse.h"
 +#include "config.h"
 +#include "policies.h"
 +#include "relay.h"
 +#include "rendservice.h"
 +#include "rephist.h"
 +#include "router.h"
 +
 +#include "hs_cell.h"
 +#include "hs_ident.h"
 +#include "hs_ntor.h"
 +#include "hs_service.h"
 +#include "hs_circuit.h"
 +
 +/* Trunnel. */
 +#include "ed25519_cert.h"
 +#include "hs/cell_common.h"
 +#include "hs/cell_establish_intro.h"
 +
 +/* A circuit is about to become an e2e rendezvous circuit. Check
 + * <b>circ_purpose</b> and ensure that it's properly set. Return true iff
 + * circuit purpose is properly set, otherwise return false. */
 +static int
 +circuit_purpose_is_correct_for_rend(unsigned int circ_purpose,
 +                                    int is_service_side)
 +{
 +  if (is_service_side) {
 +    if (circ_purpose != CIRCUIT_PURPOSE_S_CONNECT_REND) {
 +      log_warn(LD_BUG,
 +            "HS e2e circuit setup with wrong purpose (%d)", circ_purpose);
 +      return 0;
 +    }
 +  }
 +
 +  if (!is_service_side) {
 +    if (circ_purpose != CIRCUIT_PURPOSE_C_REND_READY &&
 +        circ_purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED) {
 +      log_warn(LD_BUG,
 +            "Client e2e circuit setup with wrong purpose (%d)", circ_purpose);
 +      return 0;
 +    }
 +  }
 +
 +  return 1;
 +}
 +
 +/* Create and return a crypt path for the final hop of a v3 prop224 rendezvous
 + * circuit. Initialize the crypt path crypto using the output material from the
 + * ntor key exchange at <b>ntor_key_seed</b>.
 + *
 + * If <b>is_service_side</b> is set, we are the hidden service and the final
 + * hop of the rendezvous circuit is the client on the other side. */
 +static crypt_path_t *
 +create_rend_cpath(const uint8_t *ntor_key_seed, size_t seed_len,
 +                  int is_service_side)
 +{
 +  uint8_t keys[HS_NTOR_KEY_EXPANSION_KDF_OUT_LEN];
 +  crypt_path_t *cpath = NULL;
 +
 +  /* Do the key expansion */
 +  if (hs_ntor_circuit_key_expansion(ntor_key_seed, seed_len,
 +                                    keys, sizeof(keys)) < 0) {
 +    goto err;
 +  }
 +
 +  /* Setup the cpath */
 +  cpath = tor_malloc_zero(sizeof(crypt_path_t));
 +  cpath->magic = CRYPT_PATH_MAGIC;
 +
 +  if (circuit_init_cpath_crypto(cpath, (char*)keys, sizeof(keys),
 +                                is_service_side, 1) < 0) {
 +    tor_free(cpath);
 +    goto err;
 +  }
 +
 + err:
 +  memwipe(keys, 0, sizeof(keys));
 +  return cpath;
 +}
 +
 +/* We are a v2 legacy HS client: Create and return a crypt path for the hidden
 + * service on the other side of the rendezvous circuit <b>circ</b>. Initialize
 + * the crypt path crypto using the body of the RENDEZVOUS1 cell at
 + * <b>rend_cell_body</b> (which must be at least DH_KEY_LEN+DIGEST_LEN bytes).
 + */
 +static crypt_path_t *
 +create_rend_cpath_legacy(origin_circuit_t *circ, const uint8_t *rend_cell_body)
 +{
 +  crypt_path_t *hop = NULL;
 +  char keys[DIGEST_LEN+CPATH_KEY_MATERIAL_LEN];
 +
 +  /* first DH_KEY_LEN bytes are g^y from the service. Finish the dh
 +   * handshake...*/
 +  tor_assert(circ->build_state);
 +  tor_assert(circ->build_state->pending_final_cpath);
 +  hop = circ->build_state->pending_final_cpath;
 +
 +  tor_assert(hop->rend_dh_handshake_state);
 +  if (crypto_dh_compute_secret(LOG_PROTOCOL_WARN, hop->rend_dh_handshake_state,
 +                               (char*)rend_cell_body, DH_KEY_LEN,
 +                               keys, DIGEST_LEN+CPATH_KEY_MATERIAL_LEN)<0) {
 +    log_warn(LD_GENERAL, "Couldn't complete DH handshake.");
 +    goto err;
 +  }
 +  /* ... and set up cpath. */
 +  if (circuit_init_cpath_crypto(hop,
 +                                keys+DIGEST_LEN, sizeof(keys)-DIGEST_LEN,
 +                                0, 0) < 0)
 +    goto err;
 +
 +  /* Check whether the digest is right... */
 +  if (tor_memneq(keys, rend_cell_body+DH_KEY_LEN, DIGEST_LEN)) {
 +    log_warn(LD_PROTOCOL, "Incorrect digest of key material.");
 +    goto err;
 +  }
 +
 +  /* clean up the crypto stuff we just made */
 +  crypto_dh_free(hop->rend_dh_handshake_state);
 +  hop->rend_dh_handshake_state = NULL;
 +
 +  goto done;
 +
 + err:
 +  hop = NULL;
 +
 + done:
 +  memwipe(keys, 0, sizeof(keys));
 +  return hop;
 +}
 +
 +/* Append the final <b>hop</b> to the cpath of the rend <b>circ</b>, and mark
 + * <b>circ</b> ready for use to transfer HS relay cells. */
 +static void
 +finalize_rend_circuit(origin_circuit_t *circ, crypt_path_t *hop,
 +                      int is_service_side)
 +{
 +  tor_assert(circ);
 +  tor_assert(hop);
 +
 +  /* Notify the circuit state machine that we are splicing this circuit */
 +  int new_circ_purpose = is_service_side ?
 +    CIRCUIT_PURPOSE_S_REND_JOINED : CIRCUIT_PURPOSE_C_REND_JOINED;
 +  circuit_change_purpose(TO_CIRCUIT(circ), new_circ_purpose);
 +
 +  /* All is well. Extend the circuit. */
 +  hop->state = CPATH_STATE_OPEN;
 +  /* Set the windows to default. */
 +  hop->package_window = circuit_initial_package_window();
 +  hop->deliver_window = CIRCWINDOW_START;
 +
 +  /* Now that this circuit has finished connecting to its destination,
 +   * make sure circuit_get_open_circ_or_launch is willing to return it
 +   * so we can actually use it. */
 +  circ->hs_circ_has_timed_out = 0;
 +
 +  /* Append the hop to the cpath of this circuit */
 +  onion_append_to_cpath(&circ->cpath, hop);
 +
 +  /* In legacy code, 'pending_final_cpath' points to the final hop we just
 +   * appended to the cpath. We set the original pointer to NULL so that we
 +   * don't double free it. */
 +  if (circ->build_state) {
 +    circ->build_state->pending_final_cpath = NULL;
 +  }
 +
 +  /* Finally, mark circuit as ready to be used for client streams */
 +  if (!is_service_side) {
 +    circuit_try_attaching_streams(circ);
 +  }
 +}
 +
 +/* For a given circuit and a service introduction point object, register the
 + * intro circuit to the circuitmap. This supports legacy intro point. */
 +static void
 +register_intro_circ(const hs_service_intro_point_t *ip,
 +                    origin_circuit_t *circ)
 +{
 +  tor_assert(ip);
 +  tor_assert(circ);
 +
 +  if (ip->base.is_only_legacy) {
 +    uint8_t digest[DIGEST_LEN];
 +    if (BUG(crypto_pk_get_digest(ip->legacy_key, (char *) digest) < 0)) {
 +      return;
 +    }
 +    hs_circuitmap_register_intro_circ_v2_service_side(circ, digest);
 +  } else {
 +    hs_circuitmap_register_intro_circ_v3_service_side(circ,
 +                                         &ip->auth_key_kp.pubkey);
 +  }
 +}
 +
 +/* Return the number of opened introduction circuit for the given circuit that
 + * is matching its identity key. */
 +static unsigned int
 +count_opened_desc_intro_point_circuits(const hs_service_t *service,
 +                                       const hs_service_descriptor_t *desc)
 +{
 +  unsigned int count = 0;
 +
 +  tor_assert(service);
 +  tor_assert(desc);
 +
 +  DIGEST256MAP_FOREACH(desc->intro_points.map, key,
 +                       const hs_service_intro_point_t *, ip) {
 +    const circuit_t *circ;
 +    const origin_circuit_t *ocirc = hs_circ_service_get_intro_circ(ip);
 +    if (ocirc == NULL) {
 +      continue;
 +    }
 +    circ = TO_CIRCUIT(ocirc);
 +    tor_assert(circ->purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO ||
 +               circ->purpose == CIRCUIT_PURPOSE_S_INTRO);
 +    /* Having a circuit not for the requested service is really bad. */
 +    tor_assert(ed25519_pubkey_eq(&service->keys.identity_pk,
 +                                 &ocirc->hs_ident->identity_pk));
 +    /* Only count opened circuit and skip circuit that will be closed. */
 +    if (!circ->marked_for_close && circ->state == CIRCUIT_STATE_OPEN) {
 +      count++;
 +    }
 +  } DIGEST256MAP_FOREACH_END;
 +  return count;
 +}
 +
 +/* From a given service, rendezvous cookie and handshake info, create a
 + * rendezvous point circuit identifier. This can't fail. */
 +STATIC hs_ident_circuit_t *
 +create_rp_circuit_identifier(const hs_service_t *service,
 +                             const uint8_t *rendezvous_cookie,
 +                             const curve25519_public_key_t *server_pk,
 +                             const hs_ntor_rend_cell_keys_t *keys)
 +{
 +  hs_ident_circuit_t *ident;
 +  uint8_t handshake_info[CURVE25519_PUBKEY_LEN + DIGEST256_LEN];
 +
 +  tor_assert(service);
 +  tor_assert(rendezvous_cookie);
 +  tor_assert(server_pk);
 +  tor_assert(keys);
 +
 +  ident = hs_ident_circuit_new(&service->keys.identity_pk,
 +                               HS_IDENT_CIRCUIT_RENDEZVOUS);
 +  /* Copy the RENDEZVOUS_COOKIE which is the unique identifier. */
 +  memcpy(ident->rendezvous_cookie, rendezvous_cookie,
 +         sizeof(ident->rendezvous_cookie));
 +  /* Build the HANDSHAKE_INFO which looks like this:
 +   *    SERVER_PK        [32 bytes]
 +   *    AUTH_INPUT_MAC   [32 bytes]
 +   */
 +  memcpy(handshake_info, server_pk->public_key, CURVE25519_PUBKEY_LEN);
 +  memcpy(handshake_info + CURVE25519_PUBKEY_LEN, keys->rend_cell_auth_mac,
 +         DIGEST256_LEN);
 +  tor_assert(sizeof(ident->rendezvous_handshake_info) ==
 +             sizeof(handshake_info));
 +  memcpy(ident->rendezvous_handshake_info, handshake_info,
 +         sizeof(ident->rendezvous_handshake_info));
 +  /* Finally copy the NTOR_KEY_SEED for e2e encryption on the circuit. */
 +  tor_assert(sizeof(ident->rendezvous_ntor_key_seed) ==
 +             sizeof(keys->ntor_key_seed));
 +  memcpy(ident->rendezvous_ntor_key_seed, keys->ntor_key_seed,
 +         sizeof(ident->rendezvous_ntor_key_seed));
 +  return ident;
 +}
 +
 +/* From a given service and service intro point, create an introduction point
 + * circuit identifier. This can't fail. */
 +static hs_ident_circuit_t *
 +create_intro_circuit_identifier(const hs_service_t *service,
 +                                const hs_service_intro_point_t *ip)
 +{
 +  hs_ident_circuit_t *ident;
 +
 +  tor_assert(service);
 +  tor_assert(ip);
 +
 +  ident = hs_ident_circuit_new(&service->keys.identity_pk,
 +                               HS_IDENT_CIRCUIT_INTRO);
 +  ed25519_pubkey_copy(&ident->intro_auth_pk, &ip->auth_key_kp.pubkey);
 +
 +  return ident;
 +}
 +
 +/* For a given introduction point and an introduction circuit, send the
 + * ESTABLISH_INTRO cell. The service object is used for logging. This can fail
 + * and if so, the circuit is closed and the intro point object is flagged
 + * that the circuit is not established anymore which is important for the
 + * retry mechanism. */
 +static void
 +send_establish_intro(const hs_service_t *service,
 +                     hs_service_intro_point_t *ip, origin_circuit_t *circ)
 +{
 +  ssize_t cell_len;
 +  uint8_t payload[RELAY_PAYLOAD_SIZE];
 +
 +  tor_assert(service);
 +  tor_assert(ip);
 +  tor_assert(circ);
 +
 +  /* Encode establish intro cell. */
 +  cell_len = hs_cell_build_establish_intro(circ->cpath->prev->rend_circ_nonce,
 +                                           ip, payload);
 +  if (cell_len < 0) {
 +    log_warn(LD_REND, "Unable to encode ESTABLISH_INTRO cell for service %s "
 +                      "on circuit %u. Closing circuit.",
 +             safe_str_client(service->onion_address),
 +             TO_CIRCUIT(circ)->n_circ_id);
 +    goto err;
 +  }
 +
 +  /* Send the cell on the circuit. */
 +  if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ),
 +                                   RELAY_COMMAND_ESTABLISH_INTRO,
 +                                   (char *) payload, cell_len,
 +                                   circ->cpath->prev) < 0) {
 +    log_info(LD_REND, "Unable to send ESTABLISH_INTRO cell for service %s "
 +                      "on circuit %u.",
 +             safe_str_client(service->onion_address),
 +             TO_CIRCUIT(circ)->n_circ_id);
 +    /* On error, the circuit has been closed. */
 +    goto done;
 +  }
 +
 +  /* Record the attempt to use this circuit. */
 +  pathbias_count_use_attempt(circ);
 +  goto done;
 +
 + err:
 +  circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
 + done:
 +  memwipe(payload, 0, sizeof(payload));
 +}
 +
 +/* Return a string constant describing the anonymity of service. */
 +static const char *
 +get_service_anonymity_string(const hs_service_t *service)
 +{
 +  if (service->config.is_single_onion) {
 +    return "single onion";
 +  } else {
 +    return "hidden";
 +  }
 +}
 +
 +/* For a given service, the ntor onion key and a rendezvous cookie, launch a
 + * circuit to the rendezvous point specified by the link specifiers. On
 + * success, a circuit identifier is attached to the circuit with the needed
 + * data. This function will try to open a circuit for a maximum value of
 + * MAX_REND_FAILURES then it will give up. */
 +static void
 +launch_rendezvous_point_circuit(const hs_service_t *service,
 +                                const hs_service_intro_point_t *ip,
 +                                const hs_cell_introduce2_data_t *data)
 +{
 +  int circ_needs_uptime;
 +  time_t now = time(NULL);
 +  extend_info_t *info = NULL;
 +  origin_circuit_t *circ;
 +
 +  tor_assert(service);
 +  tor_assert(ip);
 +  tor_assert(data);
 +
 +  circ_needs_uptime = hs_service_requires_uptime_circ(service->config.ports);
 +
 +  /* Get the extend info data structure for the chosen rendezvous point
 +   * specified by the given link specifiers. */
 +  info = hs_get_extend_info_from_lspecs(data->link_specifiers,
 +                                        &data->onion_pk,
 +                                        service->config.is_single_onion);
 +  if (info == NULL) {
 +    /* We are done here, we can't extend to the rendezvous point.
 +     * If you're running an IPv6-only v3 single onion service on 0.3.2 or with
 +     * 0.3.2 clients, and somehow disable the option check, it will fail here.
 +     */
 +    log_fn(LOG_PROTOCOL_WARN, LD_REND,
 +           "Not enough info to open a circuit to a rendezvous point for "
 +           "%s service %s.",
 +           get_service_anonymity_string(service),
 +           safe_str_client(service->onion_address));
 +    goto end;
 +  }
 +
 +  for (int i = 0; i < MAX_REND_FAILURES; i++) {
 +    int circ_flags = CIRCLAUNCH_NEED_CAPACITY | CIRCLAUNCH_IS_INTERNAL;
 +    if (circ_needs_uptime) {
 +      circ_flags |= CIRCLAUNCH_NEED_UPTIME;
 +    }
 +    /* Firewall and policies are checked when getting the extend info. */
 +    if (service->config.is_single_onion) {
 +      circ_flags |= CIRCLAUNCH_ONEHOP_TUNNEL;
 +    }
 +
 +    circ = circuit_launch_by_extend_info(CIRCUIT_PURPOSE_S_CONNECT_REND, info,
 +                                         circ_flags);
 +    if (circ != NULL) {
 +      /* Stop retrying, we have a circuit! */
 +      break;
 +    }
 +  }
 +  if (circ == NULL) {
 +    log_warn(LD_REND, "Giving up on launching a rendezvous circuit to %s "
 +                      "for %s service %s",
 +             safe_str_client(extend_info_describe(info)),
 +             get_service_anonymity_string(service),
 +             safe_str_client(service->onion_address));
 +    goto end;
 +  }
 +  log_info(LD_REND, "Rendezvous circuit launched to %s with cookie %s "
 +                    "for %s service %s",
 +           safe_str_client(extend_info_describe(info)),
 +           safe_str_client(hex_str((const char *) data->rendezvous_cookie,
 +                                   REND_COOKIE_LEN)),
 +           get_service_anonymity_string(service),
 +           safe_str_client(service->onion_address));
 +  tor_assert(circ->build_state);
 +  /* Rendezvous circuit have a specific timeout for the time spent on trying
 +   * to connect to the rendezvous point. */
 +  circ->build_state->expiry_time = now + MAX_REND_TIMEOUT;
 +
 +  /* Create circuit identifier and key material. */
 +  {
 +    hs_ntor_rend_cell_keys_t keys;
 +    curve25519_keypair_t ephemeral_kp;
 +    /* No need for extra strong, this is only for this circuit life time. This
 +     * key will be used for the RENDEZVOUS1 cell that will be sent on the
 +     * circuit once opened. */
 +    curve25519_keypair_generate(&ephemeral_kp, 0);
 +    if (hs_ntor_service_get_rendezvous1_keys(&ip->auth_key_kp.pubkey,
 +                                             &ip->enc_key_kp,
 +                                             &ephemeral_kp, &data->client_pk,
 +                                             &keys) < 0) {
 +      /* This should not really happened but just in case, don't make tor
 +       * freak out, close the circuit and move on. */
 +      log_info(LD_REND, "Unable to get RENDEZVOUS1 key material for "
 +                        "service %s",
 +               safe_str_client(service->onion_address));
 +      circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
 +      goto end;
 +    }
 +    circ->hs_ident = create_rp_circuit_identifier(service,
 +                                                  data->rendezvous_cookie,
 +                                                  &ephemeral_kp.pubkey, &keys);
 +    memwipe(&ephemeral_kp, 0, sizeof(ephemeral_kp));
 +    memwipe(&keys, 0, sizeof(keys));
 +    tor_assert(circ->hs_ident);
 +  }
 +
 + end:
 +  extend_info_free(info);
 +}
 +
 +/* Return true iff the given service rendezvous circuit circ is allowed for a
 + * relaunch to the rendezvous point. */
 +static int
 +can_relaunch_service_rendezvous_point(const origin_circuit_t *circ)
 +{
 +  tor_assert(circ);
 +  /* This is initialized when allocating an origin circuit. */
 +  tor_assert(circ->build_state);
 +  tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND);
 +
 +  /* XXX: Retrying under certain condition. This is related to #22455. */
 +
 +  /* Avoid to relaunch twice a circuit to the same rendezvous point at the
 +   * same time. */
 +  if (circ->hs_service_side_rend_circ_has_been_relaunched) {
 +    log_info(LD_REND, "Rendezvous circuit to %s has already been retried. "
 +                      "Skipping retry.",
 +             safe_str_client(
 +                  extend_info_describe(circ->build_state->chosen_exit)));
 +    goto disallow;
 +  }
 +
++  /* We check failure_count >= hs_get_service_max_rend_failures()-1 below, and
++   * the -1 is because we increment the failure count for our current failure
++   * *after* this clause. */
++  int max_rend_failures = hs_get_service_max_rend_failures() - 1;
++
 +  /* A failure count that has reached maximum allowed or circuit that expired,
 +   * we skip relaunching. */
-   if (circ->build_state->failure_count > MAX_REND_FAILURES ||
++  if (circ->build_state->failure_count > max_rend_failures ||
 +      circ->build_state->expiry_time <= time(NULL)) {
 +    log_info(LD_REND, "Attempt to build a rendezvous circuit to %s has "
 +                      "failed with %d attempts and expiry time %ld. "
 +                      "Giving up building.",
 +             safe_str_client(
 +                  extend_info_describe(circ->build_state->chosen_exit)),
 +             circ->build_state->failure_count,
 +             (long int) circ->build_state->expiry_time);
 +    goto disallow;
 +  }
 +
 +  /* Allowed to relaunch. */
 +  return 1;
 + disallow:
 +  return 0;
 +}
 +
 +/* Retry the rendezvous point of circ by launching a new circuit to it. */
 +static void
 +retry_service_rendezvous_point(const origin_circuit_t *circ)
 +{
 +  int flags = 0;
 +  origin_circuit_t *new_circ;
 +  cpath_build_state_t *bstate;
 +
 +  tor_assert(circ);
 +  /* This is initialized when allocating an origin circuit. */
 +  tor_assert(circ->build_state);
 +  tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND);
 +
 +  /* Ease our life. */
 +  bstate = circ->build_state;
 +
 +  log_info(LD_REND, "Retrying rendezvous point circuit to %s",
 +           safe_str_client(extend_info_describe(bstate->chosen_exit)));
 +
 +  /* Get the current build state flags for the next circuit. */
 +  flags |= (bstate->need_uptime) ? CIRCLAUNCH_NEED_UPTIME : 0;
 +  flags |= (bstate->need_capacity) ? CIRCLAUNCH_NEED_CAPACITY : 0;
 +  flags |= (bstate->is_internal) ? CIRCLAUNCH_IS_INTERNAL : 0;
 +
 +  /* We do NOT add the onehop tunnel flag even though it might be a single
 +   * onion service. The reason is that if we failed once to connect to the RP
 +   * with a direct connection, we consider that chances are that we will fail
 +   * again so try a 3-hop circuit and hope for the best. Because the service
 +   * has no anonymity (single onion), this change of behavior won't affect
 +   * security directly. */
 +
 +  new_circ = circuit_launch_by_extend_info(CIRCUIT_PURPOSE_S_CONNECT_REND,
 +                                           bstate->chosen_exit, flags);
 +  if (new_circ == NULL) {
 +    log_warn(LD_REND, "Failed to launch rendezvous circuit to %s",
 +             safe_str_client(extend_info_describe(bstate->chosen_exit)));
 +    goto done;
 +  }
 +
 +  /* Transfer build state information to the new circuit state in part to
 +   * catch any other failures. */
 +  new_circ->build_state->failure_count = bstate->failure_count+1;
 +  new_circ->build_state->expiry_time = bstate->expiry_time;
 +  new_circ->hs_ident = hs_ident_circuit_dup(circ->hs_ident);
 +
 + done:
 +  return;
 +}
 +
 +/* Using an extend info object ei, set all possible link specifiers in lspecs.
 + * legacy ID is mandatory thus MUST be present in ei. If IPv4 is not present,
 + * logs a BUG() warning, and returns an empty smartlist. Clients never make
 + * direct connections to rendezvous points, so they should always have an
 + * IPv4 address in ei. */
 +static void
 +get_lspecs_from_extend_info(const extend_info_t *ei, smartlist_t *lspecs)
 +{
 +  link_specifier_t *ls;
 +
 +  tor_assert(ei);
 +  tor_assert(lspecs);
 +
 +  /* We require IPv4, we will add IPv6 support in a later tor version */
 +  if (BUG(!tor_addr_is_v4(&ei->addr))) {
 +    return;
 +  }
 +
 +  ls = link_specifier_new();
 +  link_specifier_set_ls_type(ls, LS_IPV4);
 +  link_specifier_set_un_ipv4_addr(ls, tor_addr_to_ipv4h(&ei->addr));
 +  link_specifier_set_un_ipv4_port(ls, ei->port);
 +  /* Four bytes IPv4 and two bytes port. */
 +  link_specifier_set_ls_len(ls, sizeof(ei->addr.addr.in_addr) +
 +                            sizeof(ei->port));
 +  smartlist_add(lspecs, ls);
 +
 +  /* Legacy ID is mandatory. */
 +  ls = link_specifier_new();
 +  link_specifier_set_ls_type(ls, LS_LEGACY_ID);
 +  memcpy(link_specifier_getarray_un_legacy_id(ls), ei->identity_digest,
 +         link_specifier_getlen_un_legacy_id(ls));
 +  link_specifier_set_ls_len(ls, link_specifier_getlen_un_legacy_id(ls));
 +  smartlist_add(lspecs, ls);
 +
 +  /* ed25519 ID is only included if the extend_info has it. */
 +  if (!ed25519_public_key_is_zero(&ei->ed_identity)) {
 +    ls = link_specifier_new();
 +    link_specifier_set_ls_type(ls, LS_ED25519_ID);
 +    memcpy(link_specifier_getarray_un_ed25519_id(ls), &ei->ed_identity,
 +           link_specifier_getlen_un_ed25519_id(ls));
 +    link_specifier_set_ls_len(ls, link_specifier_getlen_un_ed25519_id(ls));
 +    smartlist_add(lspecs, ls);
 +  }
 +}
 +
 +/* Using the given descriptor intro point ip, the extend information of the
 + * rendezvous point rp_ei and the service's subcredential, populate the
 + * already allocated intro1_data object with the needed key material and link
 + * specifiers.
 + *
 + * This can't fail but the ip MUST be a valid object containing the needed
 + * keys and authentication method. */
 +static void
 +setup_introduce1_data(const hs_desc_intro_point_t *ip,
 +                      const extend_info_t *rp_ei,
 +                      const uint8_t *subcredential,
 +                      hs_cell_introduce1_data_t *intro1_data)
 +{
 +  smartlist_t *rp_lspecs;
 +
 +  tor_assert(ip);
 +  tor_assert(rp_ei);
 +  tor_assert(subcredential);
 +  tor_assert(intro1_data);
 +
 +  /* Build the link specifiers from the extend information of the rendezvous
 +   * circuit that we've picked previously. */
 +  rp_lspecs = smartlist_new();
 +  get_lspecs_from_extend_info(rp_ei, rp_lspecs);
 +
 +  /* Populate the introduce1 data object. */
 +  memset(intro1_data, 0, sizeof(hs_cell_introduce1_data_t));
 +  if (ip->legacy.key != NULL) {
 +    intro1_data->is_legacy = 1;
 +    intro1_data->legacy_key = ip->legacy.key;
 +  }
 +  intro1_data->auth_pk = &ip->auth_key_cert->signed_key;
 +  intro1_data->enc_pk = &ip->enc_key;
 +  intro1_data->subcredential = subcredential;
 +  intro1_data->onion_pk = &rp_ei->curve25519_onion_key;
 +  intro1_data->link_specifiers = rp_lspecs;
 +}
 +
 +/* ========== */
 +/* Public API */
 +/* ========== */
 +
 +/* Return an introduction point circuit matching the given intro point object.
 + * NULL is returned is no such circuit can be found. */
 +origin_circuit_t *
 +hs_circ_service_get_intro_circ(const hs_service_intro_point_t *ip)
 +{
 +  origin_circuit_t *circ = NULL;
 +
 +  tor_assert(ip);
 +
 +  if (ip->base.is_only_legacy) {
 +    uint8_t digest[DIGEST_LEN];
 +    if (BUG(crypto_pk_get_digest(ip->legacy_key, (char *) digest) < 0)) {
 +      goto end;
 +    }
 +    circ = hs_circuitmap_get_intro_circ_v2_service_side(digest);
 +  } else {
 +    circ = hs_circuitmap_get_intro_circ_v3_service_side(
 +                                        &ip->auth_key_kp.pubkey);
 +  }
 + end:
 +  return circ;
 +}
 +
 +/* Called when we fail building a rendezvous circuit at some point other than
 + * the last hop: launches a new circuit to the same rendezvous point. This
 + * supports legacy service.
 + *
 + * We currently relaunch connections to rendezvous points if:
 + * - A rendezvous circuit timed out before connecting to RP.
 + * - The redenzvous circuit failed to connect to the RP.
 + *
 + * We avoid relaunching a connection to this rendezvous point if:
 + * - We have already tried MAX_REND_FAILURES times to connect to this RP.
 + * - We've been trying to connect to this RP for more than MAX_REND_TIMEOUT
 + *   seconds
 + * - We've already retried this specific rendezvous circuit.
 + */
 +void
 +hs_circ_retry_service_rendezvous_point(origin_circuit_t *circ)
 +{
 +  tor_assert(circ);
 +  tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND);
 +
 +  /* Check if we are allowed to relaunch to the rendezvous point of circ. */
 +  if (!can_relaunch_service_rendezvous_point(circ)) {
 +    goto done;
 +  }
 +
 +  /* Flag the circuit that we are relaunching so to avoid to relaunch twice a
 +   * circuit to the same rendezvous point at the same time. */
 +  circ->hs_service_side_rend_circ_has_been_relaunched = 1;
 +
 +  /* Legacy service don't have an hidden service ident. */
 +  if (circ->hs_ident) {
 +    retry_service_rendezvous_point(circ);
 +  } else {
 +    rend_service_relaunch_rendezvous(circ);
 +  }
 +
 + done:
 +  return;
 +}
 +
 +/* For a given service and a service intro point, launch a circuit to the
 + * extend info ei. If the service is a single onion, a one-hop circuit will be
 + * requested. Return 0 if the circuit was successfully launched and tagged
 + * with the correct identifier. On error, a negative value is returned. */
 +int
 +hs_circ_launch_intro_point(hs_service_t *service,
 +                           const hs_service_intro_point_t *ip,
 +                           extend_info_t *ei)
 +{
 +  /* Standard flags for introduction circuit. */
 +  int ret = -1, circ_flags = CIRCLAUNCH_NEED_UPTIME | CIRCLAUNCH_IS_INTERNAL;
 +  origin_circuit_t *circ;
 +
 +  tor_assert(service);
 +  tor_assert(ip);
 +  tor_assert(ei);
 +
 +  /* Update circuit flags in case of a single onion service that requires a
 +   * direct connection. */
 +  if (service->config.is_single_onion) {
 +    circ_flags |= CIRCLAUNCH_ONEHOP_TUNNEL;
 +  }
 +
 +  log_info(LD_REND, "Launching a circuit to intro point %s for service %s.",
 +           safe_str_client(extend_info_describe(ei)),
 +           safe_str_client(service->onion_address));
 +
 +  /* Note down the launch for the retry period. Even if the circuit fails to
 +   * be launched, we still want to respect the retry period to avoid stress on
 +   * the circuit subsystem. */
 +  service->state.num_intro_circ_launched++;
 +  circ = circuit_launch_by_extend_info(CIRCUIT_PURPOSE_S_ESTABLISH_INTRO,
 +                                       ei, circ_flags);
 +  if (circ == NULL) {
 +    goto end;
 +  }
 +
 +  /* Setup the circuit identifier and attach it to it. */
 +  circ->hs_ident = create_intro_circuit_identifier(service, ip);
 +  tor_assert(circ->hs_ident);
 +  /* Register circuit in the global circuitmap. */
 +  register_intro_circ(ip, circ);
 +
 +  /* Success. */
 +  ret = 0;
 + end:
 +  return ret;
 +}
 +
 +/* Called when a service introduction point circuit is done building. Given
 + * the service and intro point object, this function will send the
 + * ESTABLISH_INTRO cell on the circuit. Return 0 on success. Return 1 if the
 + * circuit has been repurposed to General because we already have too many
 + * opened. */
 +int
 +hs_circ_service_intro_has_opened(hs_service_t *service,
 +                                 hs_service_intro_point_t *ip,
 +                                 const hs_service_descriptor_t *desc,
 +                                 origin_circuit_t *circ)
 +{
 +  int ret = 0;
 +  unsigned int num_intro_circ, num_needed_circ;
 +
 +  tor_assert(service);
 +  tor_assert(ip);
 +  tor_assert(desc);
 +  tor_assert(circ);
 +
 +  /* Cound opened circuits that have sent ESTABLISH_INTRO cells or are already
 +   * established introduction circuits */
 +  num_intro_circ = count_opened_desc_intro_point_circuits(service, desc);
 +  num_needed_circ = service->config.num_intro_points;
 +  if (num_intro_circ > num_needed_circ) {
 +    /* There are too many opened valid intro circuit for what the service
 +     * needs so repurpose this one. */
 +
 +    /* XXX: Legacy code checks options->ExcludeNodes and if not NULL it just
 +     * closes the circuit. I have NO idea why it does that so it hasn't been
 +     * added here. I can only assume in case our ExcludeNodes list changes but
 +     * in that case, all circuit are flagged unusable (config.c). --dgoulet */
 +
 +    log_info(LD_CIRC | LD_REND, "Introduction circuit just opened but we "
 +                                "have enough for service %s. Repurposing "
 +                                "it to general and leaving internal.",
 +             safe_str_client(service->onion_address));
 +    tor_assert(circ->build_state->is_internal);
 +    /* Remove it from the circuitmap. */
 +    hs_circuitmap_remove_circuit(TO_CIRCUIT(circ));
 +    /* Cleaning up the hidden service identifier and repurpose. */
 +    hs_ident_circuit_free(circ->hs_ident);
 +    circ->hs_ident = NULL;
 +    circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_C_GENERAL);
 +    /* Inform that this circuit just opened for this new purpose. */
 +    circuit_has_opened(circ);
 +    /* This return value indicate to the caller that the IP object should be
 +     * removed from the service because it's corresponding circuit has just
 +     * been repurposed. */
 +    ret = 1;
 +    goto done;
 +  }
 +
 +  log_info(LD_REND, "Introduction circuit %u established for service %s.",
 +           TO_CIRCUIT(circ)->n_circ_id,
 +           safe_str_client(service->onion_address));
 +  circuit_log_path(LOG_INFO, LD_REND, circ);
 +
 +  /* Time to send an ESTABLISH_INTRO cell on this circuit. On error, this call
 +   * makes sure the circuit gets closed. */
 +  send_establish_intro(service, ip, circ);
 +
 + done:
 +  return ret;
 +}
 +
 +/* Called when a service rendezvous point circuit is done building. Given the
 + * service and the circuit, this function will send a RENDEZVOUS1 cell on the
 + * circuit using the information in the circuit identifier. If the cell can't
 + * be sent, the circuit is closed. */
 +void
 +hs_circ_service_rp_has_opened(const hs_service_t *service,
 +                              origin_circuit_t *circ)
 +{
 +  size_t payload_len;
 +  uint8_t payload[RELAY_PAYLOAD_SIZE] = {0};
 +
 +  tor_assert(service);
 +  tor_assert(circ);
 +  tor_assert(circ->hs_ident);
 +
 +  /* Some useful logging. */
 +  log_info(LD_REND, "Rendezvous circuit %u has opened with cookie %s "
 +                    "for service %s",
 +           TO_CIRCUIT(circ)->n_circ_id,
 +           hex_str((const char *) circ->hs_ident->rendezvous_cookie,
 +                   REND_COOKIE_LEN),
 +           safe_str_client(service->onion_address));
 +  circuit_log_path(LOG_INFO, LD_REND, circ);
 +
 +  /* This can't fail. */
 +  payload_len = hs_cell_build_rendezvous1(
 +                        circ->hs_ident->rendezvous_cookie,
 +                        sizeof(circ->hs_ident->rendezvous_cookie),
 +                        circ->hs_ident->rendezvous_handshake_info,
 +                        sizeof(circ->hs_ident->rendezvous_handshake_info),
 +                        payload);
 +
 +  /* Pad the payload with random bytes so it matches the size of a legacy cell
 +   * which is normally always bigger. Also, the size of a legacy cell is
 +   * always smaller than the RELAY_PAYLOAD_SIZE so this is safe. */
 +  if (payload_len < HS_LEGACY_RENDEZVOUS_CELL_SIZE) {
 +    crypto_rand((char *) payload + payload_len,
 +                HS_LEGACY_RENDEZVOUS_CELL_SIZE - payload_len);
 +    payload_len = HS_LEGACY_RENDEZVOUS_CELL_SIZE;
 +  }
 +
 +  if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ),
 +                                   RELAY_COMMAND_RENDEZVOUS1,
 +                                   (const char *) payload, payload_len,
 +                                   circ->cpath->prev) < 0) {
 +    /* On error, circuit is closed. */
 +    log_warn(LD_REND, "Unable to send RENDEZVOUS1 cell on circuit %u "
 +                      "for service %s",
 +             TO_CIRCUIT(circ)->n_circ_id,
 +             safe_str_client(service->onion_address));
 +    goto done;
 +  }
 +
 +  /* Setup end-to-end rendezvous circuit between the client and us. */
 +  if (hs_circuit_setup_e2e_rend_circ(circ,
 +                       circ->hs_ident->rendezvous_ntor_key_seed,
 +                       sizeof(circ->hs_ident->rendezvous_ntor_key_seed),
 +                       1) < 0) {
 +    log_warn(LD_GENERAL, "Failed to setup circ");
 +    goto done;
 +  }
 +
 + done:
 +  memwipe(payload, 0, sizeof(payload));
 +}
 +
 +/* Circ has been expecting an INTRO_ESTABLISHED cell that just arrived. Handle
 + * the INTRO_ESTABLISHED cell payload of length payload_len arriving on the
 + * given introduction circuit circ. The service is only used for logging
 + * purposes. Return 0 on success else a negative value. */
 +int
 +hs_circ_handle_intro_established(const hs_service_t *service,
 +                                 const hs_service_intro_point_t *ip,
 +                                 origin_circuit_t *circ,
 +                                 const uint8_t *payload, size_t payload_len)
 +{
 +  int ret = -1;
 +
 +  tor_assert(service);
 +  tor_assert(ip);
 +  tor_assert(circ);
 +  tor_assert(payload);
 +
 +  if (BUG(TO_CIRCUIT(circ)->purpose != CIRCUIT_PURPOSE_S_ESTABLISH_INTRO)) {
 +    goto done;
 +  }
 +
 +  /* Try to parse the payload into a cell making sure we do actually have a
 +   * valid cell. For a legacy node, it's an empty payload so as long as we
 +   * have the cell, we are good. */
 +  if (!ip->base.is_only_legacy &&
 +      hs_cell_parse_intro_established(payload, payload_len) < 0) {
 +    log_warn(LD_REND, "Unable to parse the INTRO_ESTABLISHED cell on "
 +                      "circuit %u for service %s",
 +             TO_CIRCUIT(circ)->n_circ_id,
 +             safe_str_client(service->onion_address));
 +    goto done;
 +  }
 +
 +  /* Switch the purpose to a fully working intro point. */
 +  circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_S_INTRO);
 +  /* Getting a valid INTRODUCE_ESTABLISHED means we've successfully used the
 +   * circuit so update our pathbias subsystem. */
 +  pathbias_mark_use_success(circ);
 +  /* Success. */
 +  ret = 0;
 +
 + done:
 +  return ret;
 +}
 +
 +/* We just received an INTRODUCE2 cell on the established introduction circuit
 + * circ.  Handle the INTRODUCE2 payload of size payload_len for the given
 + * circuit and service. This cell is associated with the intro point object ip
 + * and the subcredential. Return 0 on success else a negative value. */
 +int
 +hs_circ_handle_introduce2(const hs_service_t *service,
 +                          const origin_circuit_t *circ,
 +                          hs_service_intro_point_t *ip,
 +                          const uint8_t *subcredential,
 +                          const uint8_t *payload, size_t payload_len)
 +{
 +  int ret = -1;
 +  time_t elapsed;
 +  hs_cell_introduce2_data_t data;
 +
 +  tor_assert(service);
 +  tor_assert(circ);
 +  tor_assert(ip);
 +  tor_assert(subcredential);
 +  tor_assert(payload);
 +
 +  /* Populate the data structure with everything we need for the cell to be
 +   * parsed, decrypted and key material computed correctly. */
 +  data.auth_pk = &ip->auth_key_kp.pubkey;
 +  data.enc_kp = &ip->enc_key_kp;
 +  data.subcredential = subcredential;
 +  data.payload = payload;
 +  data.payload_len = payload_len;
 +  data.link_specifiers = smartlist_new();
 +  data.replay_cache = ip->replay_cache;
 +
 +  if (hs_cell_parse_introduce2(&data, circ, service) < 0) {
 +    goto done;
 +  }
 +
 +  /* Check whether we've seen this REND_COOKIE before to detect repeats. */
 +  if (replaycache_add_test_and_elapsed(
 +           service->state.replay_cache_rend_cookie,
 +           data.rendezvous_cookie, sizeof(data.rendezvous_cookie),
 +           &elapsed)) {
 +    /* A Tor client will send a new INTRODUCE1 cell with the same REND_COOKIE
 +     * as its previous one if its intro circ times out while in state
 +     * CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT. If we received the first
 +     * INTRODUCE1 cell (the intro-point relay converts it into an INTRODUCE2
 +     * cell), we are already trying to connect to that rend point (and may
 +     * have already succeeded); drop this cell. */
 +    log_info(LD_REND, "We received an INTRODUCE2 cell with same REND_COOKIE "
 +                      "field %ld seconds ago. Dropping cell.",
 +             (long int) elapsed);
 +    goto done;
 +  }
 +
 +  /* At this point, we just confirmed that the full INTRODUCE2 cell is valid
 +   * so increment our counter that we've seen one on this intro point. */
 +  ip->introduce2_count++;
 +
 +  /* Launch rendezvous circuit with the onion key and rend cookie. */
 +  launch_rendezvous_point_circuit(service, ip, &data);
 +  /* Success. */
 +  ret = 0;
 +
 + done:
 +  SMARTLIST_FOREACH(data.link_specifiers, link_specifier_t *, lspec,
 +                    link_specifier_free(lspec));
 +  smartlist_free(data.link_specifiers);
 +  memwipe(&data, 0, sizeof(data));
 +  return ret;
 +}
 +
 +/* Circuit <b>circ</b> just finished the rend ntor key exchange. Use the key
 + * exchange output material at <b>ntor_key_seed</b> and setup <b>circ</b> to
 + * serve as a rendezvous end-to-end circuit between the client and the
 + * service. If <b>is_service_side</b> is set, then we are the hidden service
 + * and the other side is the client.
 + *
 + * Return 0 if the operation went well; in case of error return -1. */
 +int
 +hs_circuit_setup_e2e_rend_circ(origin_circuit_t *circ,
 +                               const uint8_t *ntor_key_seed, size_t seed_len,
 +                               int is_service_side)
 +{
 +  if (BUG(!circuit_purpose_is_correct_for_rend(TO_CIRCUIT(circ)->purpose,
 +                                        is_service_side))) {
 +    return -1;
 +  }
 +
 +  crypt_path_t *hop = create_rend_cpath(ntor_key_seed, seed_len,
 +                                        is_service_side);
 +  if (!hop) {
 +    log_warn(LD_REND, "Couldn't get v3 %s cpath!",
 +             is_service_side ? "service-side" : "client-side");
 +    return -1;
 +  }
 +
 +  finalize_rend_circuit(circ, hop, is_service_side);
 +
 +  return 0;
 +}
 +
 +/* We are a v2 legacy HS client and we just received a RENDEZVOUS1 cell
 + * <b>rend_cell_body</b> on <b>circ</b>. Finish up the DH key exchange and then
 + * extend the crypt path of <b>circ</b> so that the hidden service is on the
 + * other side. */
 +int
 +hs_circuit_setup_e2e_rend_circ_legacy_client(origin_circuit_t *circ,
 +                                             const uint8_t *rend_cell_body)
 +{
 +
 +  if (BUG(!circuit_purpose_is_correct_for_rend(
 +                                      TO_CIRCUIT(circ)->purpose, 0))) {
 +    return -1;
 +  }
 +
 +  crypt_path_t *hop = create_rend_cpath_legacy(circ, rend_cell_body);
 +  if (!hop) {
 +    log_warn(LD_GENERAL, "Couldn't get v2 cpath.");
 +    return -1;
 +  }
 +
 +  finalize_rend_circuit(circ, hop, 0);
 +
 +  return 0;
 +}
 +
 +/* Given the introduction circuit intro_circ, the rendezvous circuit
 + * rend_circ, a descriptor intro point object ip and the service's
 + * subcredential, send an INTRODUCE1 cell on intro_circ.
 + *
 + * This will also setup the circuit identifier on rend_circ containing the key
 + * material for the handshake and e2e encryption. Return 0 on success else
 + * negative value. Because relay_send_command_from_edge() closes the circuit
 + * on error, it is possible that intro_circ is closed on error. */
 +int
 +hs_circ_send_introduce1(origin_circuit_t *intro_circ,
 +                        origin_circuit_t *rend_circ,
 +                        const hs_desc_intro_point_t *ip,
 +                        const uint8_t *subcredential)
 +{
 +  int ret = -1;
 +  ssize_t payload_len;
 +  uint8_t payload[RELAY_PAYLOAD_SIZE] = {0};
 +  hs_cell_introduce1_data_t intro1_data;
 +
 +  tor_assert(intro_circ);
 +  tor_assert(rend_circ);
 +  tor_assert(ip);
 +  tor_assert(subcredential);
 +
 +  /* This takes various objects in order to populate the introduce1 data
 +   * object which is used to build the content of the cell. */
 +  setup_introduce1_data(ip, rend_circ->build_state->chosen_exit,
 +                        subcredential, &intro1_data);
 +  /* If we didn't get any link specifiers, it's because our extend info was
 +   * bad. */
 +  if (BUG(!intro1_data.link_specifiers) ||
 +      !smartlist_len(intro1_data.link_specifiers)) {
 +    log_warn(LD_REND, "Unable to get link specifiers for INTRODUCE1 cell on "
 +             "circuit %u.", TO_CIRCUIT(intro_circ)->n_circ_id);
 +    goto done;
 +  }
 +
 +  /* Final step before we encode a cell, we setup the circuit identifier which
 +   * will generate both the rendezvous cookie and client keypair for this
 +   * connection. Those are put in the ident. */
 +  intro1_data.rendezvous_cookie = rend_circ->hs_ident->rendezvous_cookie;
 +  intro1_data.client_kp = &rend_circ->hs_ident->rendezvous_client_kp;
 +
 +  memcpy(intro_circ->hs_ident->rendezvous_cookie,
 +         rend_circ->hs_ident->rendezvous_cookie,
 +         sizeof(intro_circ->hs_ident->rendezvous_cookie));
 +
 +  /* From the introduce1 data object, this will encode the INTRODUCE1 cell
 +   * into payload which is then ready to be sent as is. */
 +  payload_len = hs_cell_build_introduce1(&intro1_data, payload);
 +  if (BUG(payload_len < 0)) {
 +    goto done;
 +  }
 +
 +  if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(intro_circ),
 +                                   RELAY_COMMAND_INTRODUCE1,
 +                                   (const char *) payload, payload_len,
 +                                   intro_circ->cpath->prev) < 0) {
 +    /* On error, circuit is closed. */
 +    log_warn(LD_REND, "Unable to send INTRODUCE1 cell on circuit %u.",
 +             TO_CIRCUIT(intro_circ)->n_circ_id);
 +    goto done;
 +  }
 +
 +  /* Success. */
 +  ret = 0;
 +  goto done;
 +
 + done:
 +  hs_cell_introduce1_data_clear(&intro1_data);
 +  memwipe(payload, 0, sizeof(payload));
 +  return ret;
 +}
 +
 +/* Send an ESTABLISH_RENDEZVOUS cell along the rendezvous circuit circ. On
 + * success, 0 is returned else -1 and the circuit is marked for close. */
 +int
 +hs_circ_send_establish_rendezvous(origin_circuit_t *circ)
 +{
 +  ssize_t cell_len = 0;
 +  uint8_t cell[RELAY_PAYLOAD_SIZE] = {0};
 +
 +  tor_assert(circ);
 +  tor_assert(TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND);
 +
 +  log_info(LD_REND, "Send an ESTABLISH_RENDEZVOUS cell on circuit %u",
 +           TO_CIRCUIT(circ)->n_circ_id);
 +
 +  /* Set timestamp_dirty, because circuit_expire_building expects it,
 +   * and the rend cookie also means we've used the circ. */
 +  TO_CIRCUIT(circ)->timestamp_dirty = time(NULL);
 +
 +  /* We've attempted to use this circuit. Probe it if we fail */
 +  pathbias_count_use_attempt(circ);
 +
 +  /* Generate the RENDEZVOUS_COOKIE and place it in the identifier so we can
 +   * complete the handshake when receiving the acknowledgement. */
 +  crypto_rand((char *) circ->hs_ident->rendezvous_cookie, HS_REND_COOKIE_LEN);
 +  /* Generate the client keypair. No need to be extra strong, not long term */
 +  curve25519_keypair_generate(&circ->hs_ident->rendezvous_client_kp, 0);
 +
 +  cell_len =
 +    hs_cell_build_establish_rendezvous(circ->hs_ident->rendezvous_cookie,
 +                                       cell);
 +  if (BUG(cell_len < 0)) {
 +    goto err;
 +  }
 +
 +  if (relay_send_command_from_edge(CONTROL_CELL_ID, TO_CIRCUIT(circ),
 +                                   RELAY_COMMAND_ESTABLISH_RENDEZVOUS,
 +                                   (const char *) cell, cell_len,
 +                                   circ->cpath->prev) < 0) {
 +    /* Circuit has been marked for close */
 +    log_warn(LD_REND, "Unable to send ESTABLISH_RENDEZVOUS cell on "
 +                      "circuit %u", TO_CIRCUIT(circ)->n_circ_id);
 +    memwipe(cell, 0, cell_len);
 +    goto err;
 +  }
 +
 +  memwipe(cell, 0, cell_len);
 +  return 0;
 + err:
 +  return -1;
 +}
 +
 +/* We are about to close or free this <b>circ</b>. Clean it up from any
 + * related HS data structures. This function can be called multiple times
 + * safely for the same circuit. */
 +void
 +hs_circ_cleanup(circuit_t *circ)
 +{
 +  tor_assert(circ);
 +
 +  /* If it's a service-side intro circ, notify the HS subsystem for the intro
 +   * point circuit closing so it can be dealt with cleanly. */
 +  if (circ->purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO ||
 +      circ->purpose == CIRCUIT_PURPOSE_S_INTRO) {
 +    hs_service_intro_circ_has_closed(TO_ORIGIN_CIRCUIT(circ));
 +  }
 +
 +  /* Clear HS circuitmap token for this circ (if any). Very important to be
 +   * done after the HS subsystem has been notified of the close else the
 +   * circuit will not be found.
 +   *
 +   * We do this at the close if possible because from that point on, the
 +   * circuit is good as dead. We can't rely on removing it in the circuit
 +   * free() function because we open a race window between the close and free
 +   * where we can't register a new circuit for the same intro point. */
 +  if (circ->hs_token) {
 +    hs_circuitmap_remove_circuit(circ);
 +  }
 +}
 +
diff --cc src/or/hs_common.c
index a5cfaf03a,c9af3f688..e9d732331
--- a/src/or/hs_common.c
+++ b/src/or/hs_common.c
@@@ -210,6 -52,6 +210,23 @@@ hs_check_service_private_dir(const cha
    return 0;
  }
  
++/* Default, minimum and maximum values for the maximum rendezvous failures
++ * consensus parameter. */
++#define MAX_REND_FAILURES_DEFAULT 2
++#define MAX_REND_FAILURES_MIN 1
++#define MAX_REND_FAILURES_MAX 10
++
++/** How many times will a hidden service operator attempt to connect to
++ * a requested rendezvous point before giving up? */
++int
++hs_get_service_max_rend_failures(void)
++{
++  return networkstatus_get_param(NULL, "hs_service_max_rdv_failures",
++                                 MAX_REND_FAILURES_DEFAULT,
++                                 MAX_REND_FAILURES_MIN,
++                                 MAX_REND_FAILURES_MAX);
++}
++
  /** Get the default HS time period length in minutes from the consensus. */
  STATIC uint64_t
  get_time_period_length(void)
diff --cc src/or/hs_common.h
index b81c03d50,7eef5fc97..7c5ea4792
--- a/src/or/hs_common.h
+++ b/src/or/hs_common.h
@@@ -166,23 -52,8 +166,25 @@@ void hs_cleanup_circ(circuit_t *circ)
  int hs_check_service_private_dir(const char *username, const char *path,
                                   unsigned int dir_group_readable,
                                   unsigned int create);
+ int hs_get_service_max_rend_failures(void);
+ 
 +char *hs_path_from_filename(const char *directory, const char *filename);
 +void hs_build_address(const ed25519_public_key_t *key, uint8_t version,
 +                      char *addr_out);
 +int hs_address_is_valid(const char *address);
 +int hs_parse_address(const char *address, ed25519_public_key_t *key_out,
 +                     uint8_t *checksum_out, uint8_t *version_out);
 +
 +void hs_build_blinded_pubkey(const ed25519_public_key_t *pubkey,
 +                             const uint8_t *secret, size_t secret_len,
 +                             uint64_t time_period_num,
 +                             ed25519_public_key_t *pubkey_out);
 +void hs_build_blinded_keypair(const ed25519_keypair_t *kp,
 +                              const uint8_t *secret, size_t secret_len,
 +                              uint64_t time_period_num,
 +                              ed25519_keypair_t *kp_out);
 +int hs_service_requires_uptime_circ(const smartlist_t *ports);
 +
  void rend_data_free(rend_data_t *data);
  rend_data_t *rend_data_dup(const rend_data_t *data);
  rend_data_t *rend_data_client_create(const char *onion_address,
diff --cc src/or/rendservice.c
index 2cdafa666,2a3594918..2c5c5840a
--- a/src/or/rendservice.c
+++ b/src/or/rendservice.c
@@@ -2938,7 -3056,35 +2939,6 @@@ rend_service_relaunch_rendezvous(origin
    cpath_build_state_t *newstate, *oldstate;
  
    tor_assert(oldcirc->base_.purpose == CIRCUIT_PURPOSE_S_CONNECT_REND);
 -
 -  /* Don't relaunch the same rend circ twice. */
 -  if (oldcirc->hs_service_side_rend_circ_has_been_relaunched) {
 -    log_info(LD_REND, "Rendezvous circuit to %s has already been relaunched; "
 -             "not relaunching it again.",
 -             oldcirc->build_state ?
 -             safe_str(extend_info_describe(oldcirc->build_state->chosen_exit))
 -             : "*unknown*");
 -    return;
 -  }
 -  oldcirc->hs_service_side_rend_circ_has_been_relaunched = 1;
 -
 -  /* We check failure_count >= hs_get_service_max_rend_failures()-1 below, and
 -   * the -1 is because we increment the failure count for our current failure
 -   * *after* this clause. */
 -  int max_rend_failures = hs_get_service_max_rend_failures() - 1;
 -
 -  if (!oldcirc->build_state ||
 -      oldcirc->build_state->failure_count >= max_rend_failures ||
 -      oldcirc->build_state->expiry_time < time(NULL)) {
 -    log_info(LD_REND,
 -             "Attempt to build circuit to %s for rendezvous has failed "
 -             "too many times or expired; giving up.",
 -             oldcirc->build_state ?
 -             safe_str(extend_info_describe(oldcirc->build_state->chosen_exit))
 -             : "*unknown*");
 -    return;
 -  }
--
    oldstate = oldcirc->build_state;
    tor_assert(oldstate);
  





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