tor/src/feature/relay/selftest.c

/* Copyright (c) 2001 Matej Pfajfar.
 * Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
 * \file selftest.c
 * \brief Relay self-testing
 *
 * Relays need to make sure that their own ports are reachable, and estimate
 * their own bandwidth, before publishing.
 */

#include "core/or/or.h"

#include "app/config/config.h"

#include "core/mainloop/connection.h"
#include "core/mainloop/mainloop.h"
#include "core/mainloop/netstatus.h"

#include "core/or/circuitbuild.h"
#include "core/or/circuitlist.h"
#include "core/or/circuituse.h"
#include "core/or/crypt_path_st.h"
#include "core/or/extend_info_st.h"
#include "core/or/origin_circuit_st.h"
#include "core/or/relay.h"

#include "feature/control/control_events.h"

#include "feature/dirclient/dirclient.h"
#include "feature/dircommon/directory.h"

#include "feature/nodelist/authority_cert_st.h"
#include "feature/nodelist/routerinfo.h"
#include "feature/nodelist/routerinfo_st.h"
#include "feature/nodelist/routerlist.h" // but...
#include "feature/nodelist/routerset.h"
#include "feature/nodelist/torcert.h"

#include "feature/relay/relay_periodic.h"
#include "feature/relay/router.h"
#include "feature/relay/selftest.h"

static bool have_orport_for_family(int family);

/** Whether we can reach our IPv4 ORPort from the outside. */
static bool can_reach_or_port_ipv4 = false;
/** Whether we can reach our IPv6 ORPort from the outside. */
static bool can_reach_or_port_ipv6 = false;
/** Whether we can reach our DirPort from the outside. */
static bool can_reach_dir_port = false;

/** Forget what we have learned about our reachability status. */
void
router_reset_reachability(void)
{
  can_reach_or_port_ipv4 = can_reach_or_port_ipv6 = can_reach_dir_port = false;
}

/** Return 1 if we won't do reachability checks, because:
 *   - AssumeReachable is set, or
 *   - the network is disabled.
 * Otherwise, return 0.
 */
static int
router_reachability_checks_disabled(const or_options_t *options)
{
  return options->AssumeReachable ||
         net_is_disabled();
}

/** Return 0 if we need to do an ORPort reachability check, because:
 *   - no reachability check has been done yet, or
 *   - we've initiated reachability checks, but none have succeeded.
 *  Return 1 if we don't need to do an ORPort reachability check, because:
 *   - we've seen a successful reachability check, or
 *   - AssumeReachable is set, or
 *   - the network is disabled.

 * If `family'`is AF_INET or AF_INET6, return true only when we should skip
 * the given family's orport check (Because it's been checked, or because we
 * aren't checking it.)  If `family` is 0, return true if we can skip _all_
 * orport checks.
 */
int
router_should_skip_orport_reachability_check_family(
                                                const or_options_t *options,
                                                int family)
{
  tor_assert_nonfatal(family == AF_INET || family == AF_INET6 || family == 0);
  int reach_checks_disabled = router_reachability_checks_disabled(options);
  if (reach_checks_disabled) {
    return true;
  }

  // Which reachability flags should we look at?
  const bool checking_ipv4 = (family == AF_INET || family == 0);
  const bool checking_ipv6 = (family == AF_INET6 || family == 0);

  if (checking_ipv4) {
    if (have_orport_for_family(AF_INET) && !can_reach_or_port_ipv4) {
      return false;
    }
  }
  if (checking_ipv6) {
    if (have_orport_for_family(AF_INET6) && !can_reach_or_port_ipv6) {
      return false;
    }
  }

  return true;
}

/** Return 0 if we need to do a DirPort reachability check, because:
 *   - no reachability check has been done yet, or
 *   - we've initiated reachability checks, but none have succeeded.
 *  Return 1 if we don't need to do a DirPort reachability check, because:
 *   - we've seen a successful reachability check, or
 *   - there is no DirPort set, or
 *   - AssumeReachable is set, or
 *   - the network is disabled.
 */
int
router_should_skip_dirport_reachability_check(const or_options_t *options)
{
  int reach_checks_disabled = router_reachability_checks_disabled(options) ||
                              !options->DirPort_set;
  return reach_checks_disabled ||
         can_reach_dir_port;
}

/** See if we currently believe our ORPort or DirPort to be
 * unreachable. If so, return 1 else return 0.
 */
static int
router_should_check_reachability(int test_or, int test_dir)
{
  const routerinfo_t *me = router_get_my_routerinfo();
  const or_options_t *options = get_options();

  if (!me)
    return 0;

  /* Doesn't check our IPv6 address, see #34065. */
  if (routerset_contains_router(options->ExcludeNodes, me, -1) &&
      options->StrictNodes) {
    /* If we've excluded ourself, and StrictNodes is set, we can't test
     * ourself. */
    if (test_or || test_dir) {
#define SELF_EXCLUDED_WARN_INTERVAL 3600
      static ratelim_t warning_limit=RATELIM_INIT(SELF_EXCLUDED_WARN_INTERVAL);
      log_fn_ratelim(&warning_limit, LOG_WARN, LD_CIRC,
                 "Can't peform self-tests for this relay: we have "
                 "listed ourself in ExcludeNodes, and StrictNodes is set. "
                 "We cannot learn whether we are usable, and will not "
                 "be able to advertise ourself.");
    }
    return 0;
  }
  return 1;
}

/**
 * Return true if we have configured an ORPort for the given family that
 * we would like to advertise.
 *
 * Like other self-testing functions, this function looks at our most
 * recently built descriptor.
 **/
static bool
have_orport_for_family(int family)
{
  const routerinfo_t *me = router_get_my_routerinfo();

  if (!me)
    return false;

  tor_addr_port_t ap;
  if (router_get_orport(me, &ap, family) < 0) {
    return false;
  }
  return true;
}

/** Allocate and return a new extend_info_t that can be used to build
 * a circuit to or through the router <b>r</b>, using an address from
 * <b>family</b> (if available).
 *
 * Clients don't have routerinfos, so this function should only be called on a
 * server.
 *
 * If the requested address is not available, returns NULL. */
static extend_info_t *
extend_info_from_router(const routerinfo_t *r, int family)
{
  crypto_pk_t *rsa_pubkey;
  extend_info_t *info;
  tor_addr_port_t ap;

  if (BUG(!r)) {
    return NULL;
  }

  /* Relays always assume that the first hop is reachable. They ignore
   * ReachableAddresses. */
  tor_assert_nonfatal(router_or_conn_should_skip_reachable_address_check(
                                                           get_options(), 0));

  const ed25519_public_key_t *ed_id_key;
  if (r->cache_info.signing_key_cert)
    ed_id_key = &r->cache_info.signing_key_cert->signing_key;
  else
    ed_id_key = NULL;

  if (router_get_orport(r, &ap, family) < 0) {
    /* We don't have an ORPort for the requested family. */
    return NULL;
  }
  rsa_pubkey = router_get_rsa_onion_pkey(r->onion_pkey, r->onion_pkey_len);
  info = extend_info_new(r->nickname, r->cache_info.identity_digest,
                         ed_id_key,
                         rsa_pubkey, r->onion_curve25519_pkey,
                         &ap.addr, ap.port);
  crypto_pk_free(rsa_pubkey);
  return info;
}

/** Launch a self-testing circuit to one of our ORPorts, using an address from
 * <b>family</b> (if available). The circuit can be used to test reachability
 * or bandwidth. <b>me</b> is our own routerinfo.
 *
 * Logs an info-level status message. If <b>orport_reachable</b> is false,
 * call it a reachability circuit. Otherwise, call it a bandwidth circuit.
 *
 * See router_do_reachability_checks() for details. */
static void
router_do_orport_reachability_checks(const routerinfo_t *me,
                                     int family,
                                     int orport_reachable)
{
  extend_info_t *ei = extend_info_from_router(me, family);
  int ipv6_flags = (family == AF_INET6 ? CIRCLAUNCH_IS_IPV6_SELFTEST : 0);

  /* If we're trying to test IPv6, but we don't have an IPv6 ORPort, ei will
   * be NULL. */
  if (ei) {
    const char *family_name = fmt_af_family(family);
    log_info(LD_CIRC, "Testing %s of my %s ORPort: %s.",
             !orport_reachable ? "reachability" : "bandwidth",
             family_name, fmt_addrport(&ei->addr, ei->port));
    circuit_launch_by_extend_info(CIRCUIT_PURPOSE_TESTING, ei,
                                  CIRCLAUNCH_NEED_CAPACITY|
                                  CIRCLAUNCH_IS_INTERNAL|
                                  ipv6_flags);
    extend_info_free(ei);
  }
}

/** Launch a self-testing circuit, and ask an exit to connect to our DirPort.
 * <b>me</b> is our own routerinfo.
 *
 * Relays don't advertise IPv6 DirPorts, so this function only supports IPv4.
 *
 * See router_do_reachability_checks() for details. */
static void
router_do_dirport_reachability_checks(const routerinfo_t *me)
{
  tor_addr_port_t my_dirport;
  tor_addr_from_ipv4h(&my_dirport.addr, me->addr);
  my_dirport.port = me->dir_port;

  /* If there is already a pending connection, don't open another one. */
  if (!connection_get_by_type_addr_port_purpose(
                  CONN_TYPE_DIR,
                  &my_dirport.addr, my_dirport.port,
                  DIR_PURPOSE_FETCH_SERVERDESC)) {
    /* ask myself, via tor, for my server descriptor. */
    directory_request_t *req =
      directory_request_new(DIR_PURPOSE_FETCH_SERVERDESC);
    directory_request_set_dir_addr_port(req, &my_dirport);
    directory_request_set_directory_id_digest(req,
                                              me->cache_info.identity_digest);
    /* ask via an anon circuit, connecting to our dirport. */
    directory_request_set_indirection(req, DIRIND_ANON_DIRPORT);
    directory_request_set_resource(req, "authority.z");
    directory_initiate_request(req);
    directory_request_free(req);
  }
}

/** Some time has passed, or we just got new directory information.
 * See if we currently believe our ORPort or DirPort to be
 * unreachable. If so, launch a new test for it.
 *
 * For ORPort, we simply try making a circuit that ends at ourselves.
 * Success is noticed in onionskin_answer().
 *
 * For DirPort, we make a connection via Tor to our DirPort and ask
 * for our own server descriptor.
 * Success is noticed in connection_dir_client_reached_eof().
 */
void
router_do_reachability_checks(int test_or, int test_dir)
{
  const routerinfo_t *me = router_get_my_routerinfo();
  const or_options_t *options = get_options();
  int orport_reachable_v4 =
    router_should_skip_orport_reachability_check_family(options, AF_INET);
  int orport_reachable_v6 =
    router_should_skip_orport_reachability_check_family(options, AF_INET6);

  if (router_should_check_reachability(test_or, test_dir)) {
    bool need_testing = !circuit_enough_testing_circs();
    /* At the moment, tor relays believe that they are reachable when they
     * receive any create cell on an inbound connection, if the address
     * family is correct.
     */
    if (test_or && (!orport_reachable_v4 || need_testing)) {
      router_do_orport_reachability_checks(me, AF_INET, orport_reachable_v4);
    }
    if (test_or && (!orport_reachable_v6 || need_testing)) {
      router_do_orport_reachability_checks(me, AF_INET6, orport_reachable_v6);
    }

    if (test_dir && !router_should_skip_dirport_reachability_check(options)) {
      router_do_dirport_reachability_checks(me);
    }
  }
}

/** If reachability testing is in progress, let the user know that it's
 * happening.
 *
 * If all is set, log a notice-level message. Return 1 if we did, or 0 if
 * we chose not to log anything, because we were unable to test reachability.
 */
int
inform_testing_reachability(void)
{
  char ipv4_or_buf[TOR_ADDRPORT_BUF_LEN];
  char ipv6_or_buf[TOR_ADDRPORT_BUF_LEN];
  char ipv4_dir_buf[TOR_ADDRPORT_BUF_LEN];

  /* There's a race condition here, between:
   *  - tor launching reachability tests,
   *  - any circuits actually completing,
   *  - routerinfo updates, and
   *  - these log messages.
   * In rare cases, we might log the wrong ports, log when we didn't actually
   * start reachability tests, or fail to log after we actually started
   * reachability tests.
   *
   * After we separate the IPv4 and IPv6 reachability flags in #34067, tor
   * will test any IPv6 address that it discovers after launching reachability
   * checks. We'll deal with late disabled IPv6 ORPorts and IPv4 DirPorts, and
   * extra or skipped log messages in #34137.
   */
  const routerinfo_t *me = router_get_my_routerinfo();
  if (!me)
    return 0;

  /* IPv4 ORPort */
  strlcpy(ipv4_or_buf, fmt_addr32_port(me->addr, me->or_port),
          sizeof(ipv4_or_buf));
  control_event_server_status(LOG_NOTICE,
                              "CHECKING_REACHABILITY ORADDRESS=%s",
                              ipv4_or_buf);
  /* IPv6 ORPort */
  const bool has_ipv6 = tor_addr_port_is_valid(&me->ipv6_addr,
                                               me->ipv6_orport, 0);
  if (has_ipv6) {
    strlcpy(ipv6_or_buf, fmt_addrport(&me->ipv6_addr, me->ipv6_orport),
            sizeof(ipv6_or_buf));
    /* We'll add an IPv6 control event in #34068. */
  }
  /* IPv4 DirPort (there are no advertised IPv6 DirPorts) */
  if (me->dir_port) {
    strlcpy(ipv4_dir_buf, fmt_addr32_port(me->addr, me->dir_port),
            sizeof(ipv4_dir_buf));
    control_event_server_status(LOG_NOTICE,
                                "CHECKING_REACHABILITY DIRADDRESS=%s",
                                ipv4_dir_buf);
  }
  log_notice(LD_OR, "Now checking whether ORPort%s %s%s%s%s%s %s reachable... "
             "(this may take up to %d minutes -- look for log "
             "messages indicating success)",
             has_ipv6 ? "s" : "",
             ipv4_or_buf,
             has_ipv6 ? " and " : "",
             has_ipv6 ? ipv6_or_buf : "",
             me->dir_port ? " and DirPort " : "",
             me->dir_port ? ipv4_dir_buf : "",
             has_ipv6 || me->dir_port ? "are" : "is",
             TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT/60);

  return 1;
}

/**
 * Return true if this module knows of no reason why we shouldn't publish
 * a server descriptor.
 **/
static bool
ready_to_publish(const or_options_t *options)
{
  return options->PublishServerDescriptor_ != NO_DIRINFO &&
    router_should_skip_dirport_reachability_check(options) &&
    router_should_skip_orport_reachability_check(options);
}

/** Annotate that we found our ORPort reachable with a given address
 * family. */
void
router_orport_found_reachable(int family)
{
  const routerinfo_t *me = router_get_my_routerinfo();
  const or_options_t *options = get_options();
  bool *can_reach_ptr;
  if (family == AF_INET) {
    can_reach_ptr = &can_reach_or_port_ipv4;
  } else if (family == AF_INET6) {
    can_reach_ptr = &can_reach_or_port_ipv6;
  } else {
    tor_assert_nonfatal_unreached();
    return;
  }
  if (!*can_reach_ptr && me) {
    tor_addr_port_t ap;
    if (router_get_orport(me, &ap, family) < 0) {
      return;
    }
    char *address = tor_strdup(fmt_addrport_ap(&ap));

    *can_reach_ptr = true;

    log_notice(LD_OR,"Self-testing indicates your ORPort %s is reachable from "
               "the outside. Excellent.%s",
               address,
               ready_to_publish(options) ?
               " Publishing server descriptor." : "");

    mark_my_descriptor_dirty("ORPort found reachable");
    /* This is a significant enough change to upload immediately,
     * at least in a test network */
    if (options->TestingTorNetwork == 1) {
      reschedule_descriptor_update_check();
    }
    control_event_server_status(LOG_NOTICE,
                                "REACHABILITY_SUCCEEDED ORADDRESS=%s",
                                address);
    tor_free(address);
  }
}

/** Annotate that we found our DirPort reachable. */
void
router_dirport_found_reachable(void)
{
  const routerinfo_t *me = router_get_my_routerinfo();
  const or_options_t *options = get_options();

  if (!can_reach_dir_port && me) {
    char *address = tor_dup_ip(me->addr);

    if (!address)
      return;

    can_reach_dir_port = true;
    log_notice(LD_DIRSERV,"Self-testing indicates your DirPort is reachable "
               "from the outside. Excellent.%s",
               ready_to_publish(options) ?
               " Publishing server descriptor." : "");

    if (router_should_advertise_dirport(options, me->dir_port)) {
      mark_my_descriptor_dirty("DirPort found reachable");
      /* This is a significant enough change to upload immediately,
       * at least in a test network */
      if (options->TestingTorNetwork == 1) {
        reschedule_descriptor_update_check();
      }
    }
    control_event_server_status(LOG_NOTICE,
                                "REACHABILITY_SUCCEEDED DIRADDRESS=%s:%d",
                                address, me->dir_port);
    tor_free(address);
  }
}

/** We have enough testing circuits open. Send a bunch of "drop"
 * cells down each of them, to exercise our bandwidth.
 *
 * May use IPv4 and IPv6 testing circuits (if available). */
void
router_perform_bandwidth_test(int num_circs, time_t now)
{
  int num_cells = (int)(get_options()->BandwidthRate * 10 /
                        CELL_MAX_NETWORK_SIZE);
  int max_cells = num_cells < CIRCWINDOW_START ?
                    num_cells : CIRCWINDOW_START;
  int cells_per_circuit = max_cells / num_circs;
  origin_circuit_t *circ = NULL;

  log_notice(LD_OR,"Performing bandwidth self-test...done.");
  while ((circ = circuit_get_next_by_pk_and_purpose(circ, NULL,
                                              CIRCUIT_PURPOSE_TESTING))) {
    /* dump cells_per_circuit drop cells onto this circ */
    int i = cells_per_circuit;
    if (circ->base_.state != CIRCUIT_STATE_OPEN)
      continue;
    circ->base_.timestamp_dirty = now;
    while (i-- > 0) {
      if (relay_send_command_from_edge(0, TO_CIRCUIT(circ),
                                       RELAY_COMMAND_DROP,
                                       NULL, 0, circ->cpath->prev)<0) {
        return; /* stop if error */
      }
    }
  }
}