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tor  0.2.3.18-rc
Defines | Functions | Variables
circuituse.c File Reference

Launch the right sort of circuits and attach streams to them. More...

#include "or.h"
#include "circuitbuild.h"
#include "circuitlist.h"
#include "circuituse.h"
#include "config.h"
#include "connection.h"
#include "connection_edge.h"
#include "control.h"
#include "nodelist.h"
#include "networkstatus.h"
#include "policies.h"
#include "rendclient.h"
#include "rendcommon.h"
#include "rendservice.h"
#include "rephist.h"
#include "router.h"
#include "routerlist.h"

Go to the source code of this file.

Defines

#define SET_CUTOFF(target, msec)
#define MAX_UNUSED_OPEN_CIRCUITS   14
 Don't keep more than this many unused open circuits around.
#define TESTING_CIRCUIT_INTERVAL   300
 Build a new test circuit every 5 minutes.
#define IDLE_TIMEOUT_WHILE_LEARNING   (10*60)
 If we haven't yet decided on a good timeout value for circuit building, we close idles circuits aggressively so we can get more data points.
#define IDLE_ONE_HOP_CIRC_TIMEOUT   60
 How long do we wait before killing circuits with the properties described below?
#define NUM_PARALLEL_TESTING_CIRCS   4
 Number of testing circuits we want open before testing our bandwidth.
#define MAX_CIRCUIT_FAILURES   5
 Don't retry launching a new circuit if we try this many times with no success.

Functions

static void circuit_expire_old_circuits_clientside (void)
 Find each circuit that has been unused for too long, or dirty for too long and has no streams on it: mark it for close.
static void circuit_increment_failure_count (void)
 Record another failure at opening a general circuit.
static int circuit_is_acceptable (const origin_circuit_t *origin_circ, const entry_connection_t *conn, int must_be_open, uint8_t purpose, int need_uptime, int need_internal, time_t now)
 Return 1 if circ could be returned by circuit_get_best().
static int circuit_is_better (const origin_circuit_t *oa, const origin_circuit_t *ob, const entry_connection_t *conn)
 Return 1 if circuit a is better than circuit b for conn, and return 0 otherwise.
static origin_circuit_tcircuit_get_best (const entry_connection_t *conn, int must_be_open, uint8_t purpose, int need_uptime, int need_internal)
 Find the best circ that conn can use, preferably one which is dirty.
static int count_pending_general_client_circuits (void)
 Return the number of not-yet-open general-purpose origin circuits.
void circuit_expire_building (void)
 Close all circuits that start at us, aren't open, and were born at least CircuitBuildTimeout seconds ago.
void circuit_remove_handled_ports (smartlist_t *needed_ports)
 Remove any elements in needed_ports that are handled by an open or in-progress circuit.
int circuit_stream_is_being_handled (entry_connection_t *conn, uint16_t port, int min)
 Return 1 if at least min general-purpose non-internal circuits will have an acceptable exit node for exit stream conn if it is defined, else for "*:port".
static void circuit_predict_and_launch_new (void)
 Figure out how many circuits we have open that are clean.
void circuit_build_needed_circs (time_t now)
 This function is called once a second, if router_have_min_dir_info() is true.
void circuit_detach_stream (circuit_t *circ, edge_connection_t *conn)
 If the stream conn is a member of any of the linked lists of circ, then remove it from the list.
void circuit_expire_old_circuits_serverside (time_t now)
 Find each non-origin circuit that has been unused for too long, has no streams on it, used a create_fast, and ends here: mark it for close.
void reset_bandwidth_test (void)
 Reset have_performed_bandwidth_test, so we'll start building testing circuits again so we can exercise our bandwidth.
int circuit_enough_testing_circs (void)
 Return 1 if we've already exercised our bandwidth, or if we have fewer than NUM_PARALLEL_TESTING_CIRCS testing circuits established or on the way.
static void circuit_testing_opened (origin_circuit_t *circ)
 A testing circuit has completed.
static void circuit_testing_failed (origin_circuit_t *circ, int at_last_hop)
 A testing circuit has failed to build.
void circuit_has_opened (origin_circuit_t *circ)
 The circuit circ has just become open.
static int circuit_try_clearing_isolation_state (origin_circuit_t *circ)
 If the stream-isolation state of circ can be cleared, clear it.
void circuit_try_attaching_streams (origin_circuit_t *circ)
 Called when a circuit becomes ready for streams to be attached to it.
void circuit_build_failed (origin_circuit_t *circ)
 Called whenever a circuit could not be successfully built.
origin_circuit_tcircuit_launch (uint8_t purpose, int flags)
 Launch a new circuit; see circuit_launch_by_extend_info() for details on arguments.
origin_circuit_tcircuit_launch_by_extend_info (uint8_t purpose, extend_info_t *extend_info, int flags)
 Launch a new circuit with purpose purpose and exit node extend_info (or NULL to select a random exit node).
void circuit_reset_failure_count (int timeout)
 Reset the failure count for opening general circuits.
static int circuit_get_open_circ_or_launch (entry_connection_t *conn, uint8_t desired_circuit_purpose, origin_circuit_t **circp)
 Find an open circ that we're happy to use for conn and return 1.
static int cpath_is_on_circuit (origin_circuit_t *circ, crypt_path_t *crypt_path)
 Return true iff crypt_path is one of the crypt_paths for circ.
static int optimistic_data_enabled (void)
 Return true iff client-side optimistic data is supported.
static void link_apconn_to_circ (entry_connection_t *apconn, origin_circuit_t *circ, crypt_path_t *cpath)
 Attach the AP stream apconn to circ's linked list of p_streams.
int hostname_in_track_host_exits (const or_options_t *options, const char *address)
 Return true iff address is matched by one of the entries in TrackHostExits.
static void consider_recording_trackhost (const entry_connection_t *conn, const origin_circuit_t *circ)
 If an exit wasn't explicitly specified for conn, consider saving the exit that we did choose for use by future connections to conn's destination.
int connection_ap_handshake_attach_chosen_circuit (entry_connection_t *conn, origin_circuit_t *circ, crypt_path_t *cpath)
 Attempt to attach the connection conn to circ, and send a begin or resolve cell as appropriate.
int connection_ap_handshake_attach_circuit (entry_connection_t *conn)
 Try to find a safe live circuit for CONN_TYPE_AP connection conn.
void circuit_change_purpose (circuit_t *circ, uint8_t new_purpose)
 Change circ's purpose to new_purpose.

Variables

circuit_tglobal_circuitlist
 A global list of all circuits at this hop.
static int have_performed_bandwidth_test = 0
 True iff we've ever had enough testing circuits open to test our bandwidth.
static int n_circuit_failures = 0
 Number of consecutive failures so far; should only be touched by circuit_launch_new and circuit_*_failure_count.
static int did_circs_fail_last_period = 0
 Before the last time we called circuit_reset_failure_count(), were there a lot of failures?

Detailed Description

Launch the right sort of circuits and attach streams to them.

Definition in file circuituse.c.


Define Documentation

#define IDLE_ONE_HOP_CIRC_TIMEOUT   60

How long do we wait before killing circuits with the properties described below?

Probably we could choose a number here as low as 5 to 10 seconds, since these circs are used for begindir, and a) generally you either ask another begindir question right after or you don't for a long time, b) clients at least through 0.2.1.x choose from the whole set of directory mirrors at each choice, and c) re-establishing a one-hop circuit via create-fast is a light operation assuming the TLS conn is still there.

I expect "b" to go away one day when we move to using directory guards, but I think "a" and "c" are good enough reasons that a low number is safe even then.

Definition at line 960 of file circuituse.c.

#define IDLE_TIMEOUT_WHILE_LEARNING   (10*60)

If we haven't yet decided on a good timeout value for circuit building, we close idles circuits aggressively so we can get more data points.

Definition at line 871 of file circuituse.c.

#define MAX_CIRCUIT_FAILURES   5

Don't retry launching a new circuit if we try this many times with no success.

Definition at line 1274 of file circuituse.c.

#define MAX_UNUSED_OPEN_CIRCUITS   14

Don't keep more than this many unused open circuits around.

Definition at line 657 of file circuituse.c.

Number of testing circuits we want open before testing our bandwidth.

Definition at line 993 of file circuituse.c.

#define SET_CUTOFF (   target,
  msec 
)
Value:
do {                       \
    long ms = tor_lround(msec);                             \
    struct timeval diff;                                    \
    diff.tv_sec = ms / 1000;                                \
    diff.tv_usec = (int)((ms % 1000) * 1000);               \
    timersub(&now, &diff, &target);                         \
  } while (0)
#define TESTING_CIRCUIT_INTERVAL   300

Build a new test circuit every 5 minutes.

Definition at line 760 of file circuituse.c.


Function Documentation

Called whenever a circuit could not be successfully built.

Definition at line 1164 of file circuituse.c.

{
  /* we should examine circ and see if it failed because of
   * the last hop or an earlier hop. then use this info below.
   */
  int failed_at_last_hop = 0;
  /* If the last hop isn't open, and the second-to-last is, we failed
   * at the last hop. */
  if (circ->cpath &&
      circ->cpath->prev->state != CPATH_STATE_OPEN &&
      circ->cpath->prev->prev->state == CPATH_STATE_OPEN) {
    failed_at_last_hop = 1;
  }
  if (circ->cpath &&
      circ->cpath->state != CPATH_STATE_OPEN) {
    /* We failed at the first hop. If there's an OR connection
     * to blame, blame it. Also, avoid this relay for a while, and
     * fail any one-hop directory fetches destined for it. */
    const char *n_conn_id = circ->cpath->extend_info->identity_digest;
    int already_marked = 0;
    if (circ->_base.n_conn) {
      or_connection_t *n_conn = circ->_base.n_conn;
      if (n_conn->is_bad_for_new_circs) {
        /* We only want to blame this router when a fresh healthy
         * connection fails. So don't mark this router as newly failed,
         * since maybe this was just an old circuit attempt that's
         * finally timing out now. Also, there's no need to blow away
         * circuits/streams/etc, since the failure of an unhealthy conn
         * doesn't tell us much about whether a healthy conn would
         * succeed. */
        already_marked = 1;
      }
      log_info(LD_OR,
               "Our circuit failed to get a response from the first hop "
               "(%s:%d). I'm going to try to rotate to a better connection.",
               n_conn->_base.address, n_conn->_base.port);
      n_conn->is_bad_for_new_circs = 1;
    } else {
      log_info(LD_OR,
               "Our circuit died before the first hop with no connection");
    }
    if (n_conn_id && !already_marked) {
      entry_guard_register_connect_status(n_conn_id, 0, 1, time(NULL));
      /* if there are any one-hop streams waiting on this circuit, fail
       * them now so they can retry elsewhere. */
      connection_ap_fail_onehop(n_conn_id, circ->build_state);
    }
  }

  switch (circ->_base.purpose) {
    case CIRCUIT_PURPOSE_C_GENERAL:
      /* If we never built the circuit, note it as a failure. */
      circuit_increment_failure_count();
      if (failed_at_last_hop) {
        /* Make sure any streams that demand our last hop as their exit
         * know that it's unlikely to happen. */
        circuit_discard_optional_exit_enclaves(circ->cpath->prev->extend_info);
      }
      break;
    case CIRCUIT_PURPOSE_TESTING:
      circuit_testing_failed(circ, failed_at_last_hop);
      break;
    case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:
      /* at Bob, waiting for introductions */
      if (circ->_base.state != CIRCUIT_STATE_OPEN) {
        circuit_increment_failure_count();
      }
      /* no need to care here, because bob will rebuild intro
       * points periodically. */
      break;
    case CIRCUIT_PURPOSE_C_INTRODUCING:
      /* at Alice, connecting to intro point */
      /* Don't increment failure count, since Bob may have picked
       * the introduction point maliciously */
      /* Alice will pick a new intro point when this one dies, if
       * the stream in question still cares. No need to act here. */
      break;
    case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
      /* at Alice, waiting for Bob */
      circuit_increment_failure_count();
      /* Alice will pick a new rend point when this one dies, if
       * the stream in question still cares. No need to act here. */
      break;
    case CIRCUIT_PURPOSE_S_CONNECT_REND:
      /* at Bob, connecting to rend point */
      /* Don't increment failure count, since Alice may have picked
       * the rendezvous point maliciously */
      log_info(LD_REND,
               "Couldn't connect to Alice's chosen rend point %s "
               "(%s hop failed).",
               escaped(build_state_get_exit_nickname(circ->build_state)),
               failed_at_last_hop?"last":"non-last");
      rend_service_relaunch_rendezvous(circ);
      break;
    /* default:
     * This won't happen in normal operation, but might happen if the
     * controller did it. Just let it slide. */
  }
}

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void circuit_build_needed_circs ( time_t  now)

This function is called once a second, if router_have_min_dir_info() is true.

Its job is to make sure all services we offer have enough circuits available. Some services just want enough circuits for current tasks, whereas others want a minimum set of idle circuits hanging around.

Definition at line 768 of file circuituse.c.

{
  static time_t time_to_new_circuit = 0;
  const or_options_t *options = get_options();

  /* launch a new circ for any pending streams that need one */
  connection_ap_attach_pending();

  /* make sure any hidden services have enough intro points */
  rend_services_introduce();

  if (time_to_new_circuit < now) {
    circuit_reset_failure_count(1);
    time_to_new_circuit = now + options->NewCircuitPeriod;
    if (proxy_mode(get_options()))
      addressmap_clean(now);
    circuit_expire_old_circuits_clientside();

#if 0 /* disable for now, until predict-and-launch-new can cull leftovers */
    circ = circuit_get_youngest_clean_open(CIRCUIT_PURPOSE_C_GENERAL);
    if (get_options()->RunTesting &&
        circ &&
        circ->timestamp_created.tv_sec + TESTING_CIRCUIT_INTERVAL < now) {
      log_fn(LOG_INFO,"Creating a new testing circuit.");
      circuit_launch(CIRCUIT_PURPOSE_C_GENERAL, 0);
    }
#endif
  }
  if (!options->DisablePredictedCircuits)
    circuit_predict_and_launch_new();
}

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void circuit_change_purpose ( circuit_t circ,
uint8_t  new_purpose 
)

Change circ's purpose to new_purpose.

Definition at line 2047 of file circuituse.c.

{
  uint8_t old_purpose;
  /* Don't allow an OR circ to become an origin circ or vice versa. */
  tor_assert(!!(CIRCUIT_IS_ORIGIN(circ)) ==
             !!(CIRCUIT_PURPOSE_IS_ORIGIN(new_purpose)));

  if (circ->purpose == new_purpose) return;

  if (CIRCUIT_IS_ORIGIN(circ)) {
    char old_purpose_desc[80] = "";

    strncpy(old_purpose_desc, circuit_purpose_to_string(circ->purpose), 80-1);
    old_purpose_desc[80-1] = '\0';

    log_debug(LD_CIRC,
              "changing purpose of origin circ %d "
              "from \"%s\" (%d) to \"%s\" (%d)",
              TO_ORIGIN_CIRCUIT(circ)->global_identifier,
              old_purpose_desc,
              circ->purpose,
              circuit_purpose_to_string(new_purpose),
              new_purpose);
  }

  old_purpose = circ->purpose;
  circ->purpose = new_purpose;

  if (CIRCUIT_IS_ORIGIN(circ)) {
    control_event_circuit_purpose_changed(TO_ORIGIN_CIRCUIT(circ),
                                          old_purpose);
  }
}

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void circuit_detach_stream ( circuit_t circ,
edge_connection_t conn 
)

If the stream conn is a member of any of the linked lists of circ, then remove it from the list.

Definition at line 804 of file circuituse.c.

{
  edge_connection_t *prevconn;

  tor_assert(circ);
  tor_assert(conn);

  if (conn->_base.type == CONN_TYPE_AP) {
    entry_connection_t *entry_conn = EDGE_TO_ENTRY_CONN(conn);
    entry_conn->may_use_optimistic_data = 0;
  }
  conn->cpath_layer = NULL; /* don't keep a stale pointer */
  conn->on_circuit = NULL;

  if (CIRCUIT_IS_ORIGIN(circ)) {
    origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
    if (conn == origin_circ->p_streams) {
      origin_circ->p_streams = conn->next_stream;
      return;
    }

    for (prevconn = origin_circ->p_streams;
         prevconn && prevconn->next_stream && prevconn->next_stream != conn;
         prevconn = prevconn->next_stream)
      ;
    if (prevconn && prevconn->next_stream) {
      prevconn->next_stream = conn->next_stream;
      return;
    }
  } else {
    or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
    if (conn == or_circ->n_streams) {
      or_circ->n_streams = conn->next_stream;
      return;
    }
    if (conn == or_circ->resolving_streams) {
      or_circ->resolving_streams = conn->next_stream;
      return;
    }

    for (prevconn = or_circ->n_streams;
         prevconn && prevconn->next_stream && prevconn->next_stream != conn;
         prevconn = prevconn->next_stream)
      ;
    if (prevconn && prevconn->next_stream) {
      prevconn->next_stream = conn->next_stream;
      return;
    }

    for (prevconn = or_circ->resolving_streams;
         prevconn && prevconn->next_stream && prevconn->next_stream != conn;
         prevconn = prevconn->next_stream)
      ;
    if (prevconn && prevconn->next_stream) {
      prevconn->next_stream = conn->next_stream;
      return;
    }
  }

  log_warn(LD_BUG,"Edge connection not in circuit's list.");
  /* Don't give an error here; it's harmless. */
  tor_fragile_assert();
}

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Return 1 if we've already exercised our bandwidth, or if we have fewer than NUM_PARALLEL_TESTING_CIRCS testing circuits established or on the way.

Else return 0.

Definition at line 1012 of file circuituse.c.

{
  circuit_t *circ;
  int num = 0;

  if (have_performed_bandwidth_test)
    return 1;

  for (circ = global_circuitlist; circ; circ = circ->next) {
    if (!circ->marked_for_close && CIRCUIT_IS_ORIGIN(circ) &&
        circ->purpose == CIRCUIT_PURPOSE_TESTING &&
        circ->state == CIRCUIT_STATE_OPEN)
      num++;
  }
  return num >= NUM_PARALLEL_TESTING_CIRCS;
}

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void circuit_expire_building ( void  )

Close all circuits that start at us, aren't open, and were born at least CircuitBuildTimeout seconds ago.

Definition at line 352 of file circuituse.c.

{
  circuit_t *victim, *next_circ = global_circuitlist;
  /* circ_times.timeout_ms and circ_times.close_ms are from
   * circuit_build_times_get_initial_timeout() if we haven't computed
   * custom timeouts yet */
  struct timeval general_cutoff, begindir_cutoff, fourhop_cutoff,
    cannibalize_cutoff, close_cutoff, extremely_old_cutoff,
    hs_extremely_old_cutoff;
  const or_options_t *options = get_options();
  struct timeval now;
  cpath_build_state_t *build_state;

  tor_gettimeofday(&now);
#define SET_CUTOFF(target, msec) do {                       \
    long ms = tor_lround(msec);                             \
    struct timeval diff;                                    \
    diff.tv_sec = ms / 1000;                                \
    diff.tv_usec = (int)((ms % 1000) * 1000);               \
    timersub(&now, &diff, &target);                         \
  } while (0)

  SET_CUTOFF(general_cutoff, circ_times.timeout_ms);
  SET_CUTOFF(begindir_cutoff, circ_times.timeout_ms / 2.0);
  SET_CUTOFF(fourhop_cutoff, circ_times.timeout_ms * (4/3.0));
  SET_CUTOFF(cannibalize_cutoff, circ_times.timeout_ms / 2.0);
  SET_CUTOFF(close_cutoff, circ_times.close_ms);
  SET_CUTOFF(extremely_old_cutoff, circ_times.close_ms*2 + 1000);

  SET_CUTOFF(hs_extremely_old_cutoff,
             MAX(circ_times.close_ms*2 + 1000,
                 options->SocksTimeout * 1000));

  while (next_circ) {
    struct timeval cutoff;
    victim = next_circ;
    next_circ = next_circ->next;
    if (!CIRCUIT_IS_ORIGIN(victim) || /* didn't originate here */
        victim->marked_for_close) /* don't mess with marked circs */
      continue;

    build_state = TO_ORIGIN_CIRCUIT(victim)->build_state;
    if (build_state && build_state->onehop_tunnel)
      cutoff = begindir_cutoff;
    else if (build_state && build_state->desired_path_len == 4
             && !TO_ORIGIN_CIRCUIT(victim)->has_opened)
      cutoff = fourhop_cutoff;
    else if (TO_ORIGIN_CIRCUIT(victim)->has_opened)
      cutoff = cannibalize_cutoff;
    else if (victim->purpose == CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT)
      cutoff = close_cutoff;
    else
      cutoff = general_cutoff;

    if (TO_ORIGIN_CIRCUIT(victim)->hs_circ_has_timed_out)
      cutoff = hs_extremely_old_cutoff;

    if (timercmp(&victim->timestamp_created, &cutoff, >))
      continue; /* it's still young, leave it alone */

#if 0
    /* some debug logs, to help track bugs */
    if (victim->purpose >= CIRCUIT_PURPOSE_C_INTRODUCING &&
        victim->purpose <= CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED) {
      if (!victim->timestamp_dirty)
        log_fn(LOG_DEBUG,"Considering %sopen purpose %d to %s (circid %d)."
               "(clean).",
               victim->state == CIRCUIT_STATE_OPEN ? "" : "non",
               victim->purpose, victim->build_state->chosen_exit_name,
               victim->n_circ_id);
      else
        log_fn(LOG_DEBUG,"Considering %sopen purpose %d to %s (circid %d). "
               "%d secs since dirty.",
               victim->state == CIRCUIT_STATE_OPEN ? "" : "non",
               victim->purpose, victim->build_state->chosen_exit_name,
               victim->n_circ_id,
               (int)(now - victim->timestamp_dirty));
    }
#endif

    /* if circ is !open, or if it's open but purpose is a non-finished
     * intro or rend, then mark it for close */
    if (victim->state == CIRCUIT_STATE_OPEN) {
      switch (victim->purpose) {
        default: /* most open circuits can be left alone. */
          continue; /* yes, continue inside a switch refers to the nearest
                     * enclosing loop. C is smart. */
        case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
        case CIRCUIT_PURPOSE_C_INTRODUCING:
        case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:
          break; /* too old, need to die */
        case CIRCUIT_PURPOSE_C_REND_READY:
          /* it's a rend_ready circ -- has it already picked a query? */
          /* c_rend_ready circs measure age since timestamp_dirty,
           * because that's set when they switch purposes
           */
          if (TO_ORIGIN_CIRCUIT(victim)->rend_data ||
              victim->timestamp_dirty > cutoff.tv_sec)
            continue;
          break;
        case CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED:
        case CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT:
          /* rend and intro circs become dirty each time they
           * make an introduction attempt. so timestamp_dirty
           * will reflect the time since the last attempt.
           */
          if (victim->timestamp_dirty > cutoff.tv_sec)
            continue;
          break;
      }
    } else { /* circuit not open, consider recording failure as timeout */
      int first_hop_succeeded = TO_ORIGIN_CIRCUIT(victim)->cpath &&
            TO_ORIGIN_CIRCUIT(victim)->cpath->state == CPATH_STATE_OPEN;

      if (TO_ORIGIN_CIRCUIT(victim)->p_streams != NULL) {
        log_warn(LD_BUG, "Circuit %d (purpose %d, %s) has timed out, "
                 "yet has attached streams!",
                 TO_ORIGIN_CIRCUIT(victim)->global_identifier,
                 victim->purpose,
                 circuit_purpose_to_string(victim->purpose));
        tor_fragile_assert();
        continue;
      }

      if (circuit_timeout_want_to_count_circ(TO_ORIGIN_CIRCUIT(victim)) &&
          circuit_build_times_enough_to_compute(&circ_times)) {
        /* Circuits are allowed to last longer for measurement.
         * Switch their purpose and wait. */
        if (victim->purpose != CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT) {
          control_event_circuit_status(TO_ORIGIN_CIRCUIT(victim),
                                       CIRC_EVENT_FAILED,
                                       END_CIRC_REASON_TIMEOUT);
          circuit_change_purpose(victim, CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT);
          /* Record this failure to check for too many timeouts
           * in a row. This function does not record a time value yet
           * (we do that later); it only counts the fact that we did
           * have a timeout. */
          circuit_build_times_count_timeout(&circ_times,
                                            first_hop_succeeded);
          continue;
        }

        /*
         * If the circuit build time is much greater than we would have cut
         * it off at, we probably had a suspend event along this codepath,
         * and we should discard the value.
         */
        if (timercmp(&victim->timestamp_created, &extremely_old_cutoff, <)) {
          log_notice(LD_CIRC,
                     "Extremely large value for circuit build timeout: %lds. "
                     "Assuming clock jump. Purpose %d (%s)",
                     (long)(now.tv_sec - victim->timestamp_created.tv_sec),
                     victim->purpose,
                     circuit_purpose_to_string(victim->purpose));
        } else if (circuit_build_times_count_close(&circ_times,
                                         first_hop_succeeded,
                                         victim->timestamp_created.tv_sec)) {
          circuit_build_times_set_timeout(&circ_times);
        }
      }
    }

    /* If this is a hidden service client circuit which is far enough
     * along in connecting to its destination, and we haven't already
     * flagged it as 'timed out', and the user has not told us to
     * close such circs immediately on timeout, flag it as 'timed out'
     * so we'll launch another intro or rend circ, but don't mark it
     * for close yet.
     *
     * (Circs flagged as 'timed out' are given a much longer timeout
     * period above, so we won't close them in the next call to
     * circuit_expire_building.) */
    if (!(options->CloseHSClientCircuitsImmediatelyOnTimeout) &&
        !(TO_ORIGIN_CIRCUIT(victim)->hs_circ_has_timed_out)) {
      switch (victim->purpose) {
      case CIRCUIT_PURPOSE_C_REND_READY:
        /* We only want to spare a rend circ if it has been specified in
         * an INTRODUCE1 cell sent to a hidden service.  A circ's
         * pending_final_cpath field is non-NULL iff it is a rend circ
         * and we have tried to send an INTRODUCE1 cell specifying it.
         * Thus, if the pending_final_cpath field *is* NULL, then we
         * want to not spare it. */
        if (TO_ORIGIN_CIRCUIT(victim)->build_state->pending_final_cpath ==
            NULL)
          break;
      case CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT:
      case CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED:
        /* If we have reached this line, we want to spare the circ for now. */
        log_info(LD_CIRC,"Marking circ %d (state %d:%s, purpose %d) "
                 "as timed-out HS circ",
                 victim->n_circ_id,
                 victim->state, circuit_state_to_string(victim->state),
                 victim->purpose);
        TO_ORIGIN_CIRCUIT(victim)->hs_circ_has_timed_out = 1;
        continue;
      default:
        break;
      }
    }

    /* If this is a service-side rendezvous circuit which is far
     * enough along in connecting to its destination, consider sparing
     * it. */
    if (!(options->CloseHSServiceRendCircuitsImmediatelyOnTimeout) &&
        !(TO_ORIGIN_CIRCUIT(victim)->hs_circ_has_timed_out) &&
        victim->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND) {
      log_info(LD_CIRC,"Marking circ %d (state %d:%s, purpose %d) "
               "as timed-out HS circ; relaunching rendezvous attempt.",
               victim->n_circ_id,
               victim->state, circuit_state_to_string(victim->state),
               victim->purpose);
      TO_ORIGIN_CIRCUIT(victim)->hs_circ_has_timed_out = 1;
      rend_service_relaunch_rendezvous(TO_ORIGIN_CIRCUIT(victim));
      continue;
    }

    if (victim->n_conn)
      log_info(LD_CIRC,"Abandoning circ %s:%d:%d (state %d:%s, purpose %d)",
               victim->n_conn->_base.address, victim->n_conn->_base.port,
               victim->n_circ_id,
               victim->state, circuit_state_to_string(victim->state),
               victim->purpose);
    else
      log_info(LD_CIRC,"Abandoning circ %d (state %d:%s, purpose %d)",
               victim->n_circ_id, victim->state,
               circuit_state_to_string(victim->state), victim->purpose);

    circuit_log_path(LOG_INFO,LD_CIRC,TO_ORIGIN_CIRCUIT(victim));
    if (victim->purpose == CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT)
      circuit_mark_for_close(victim, END_CIRC_REASON_MEASUREMENT_EXPIRED);
    else
      circuit_mark_for_close(victim, END_CIRC_REASON_TIMEOUT);
  }
}

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static void circuit_expire_old_circuits_clientside ( void  ) [static]

Find each circuit that has been unused for too long, or dirty for too long and has no streams on it: mark it for close.

Definition at line 877 of file circuituse.c.

{
  circuit_t *circ;
  struct timeval cutoff, now;

  tor_gettimeofday(&now);
  cutoff = now;

  if (get_options()->LearnCircuitBuildTimeout &&
      circuit_build_times_needs_circuits(&circ_times)) {
    /* Circuits should be shorter lived if we need more of them
     * for learning a good build timeout */
    cutoff.tv_sec -= IDLE_TIMEOUT_WHILE_LEARNING;
  } else {
    cutoff.tv_sec -= get_options()->CircuitIdleTimeout;
  }

  for (circ = global_circuitlist; circ; circ = circ->next) {
    if (circ->marked_for_close || !CIRCUIT_IS_ORIGIN(circ))
      continue;
    /* If the circuit has been dirty for too long, and there are no streams
     * on it, mark it for close.
     */
    if (circ->timestamp_dirty &&
        circ->timestamp_dirty + get_options()->MaxCircuitDirtiness <
          now.tv_sec &&
        !TO_ORIGIN_CIRCUIT(circ)->p_streams /* nothing attached */ ) {
      log_debug(LD_CIRC, "Closing n_circ_id %d (dirty %ld sec ago, "
                "purpose %d)",
                circ->n_circ_id, (long)(now.tv_sec - circ->timestamp_dirty),
                circ->purpose);
      circuit_mark_for_close(circ, END_CIRC_REASON_FINISHED);
    } else if (!circ->timestamp_dirty && circ->state == CIRCUIT_STATE_OPEN) {
      if (timercmp(&circ->timestamp_created, &cutoff, <)) {
        if (circ->purpose == CIRCUIT_PURPOSE_C_GENERAL ||
                circ->purpose == CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT ||
                circ->purpose == CIRCUIT_PURPOSE_S_ESTABLISH_INTRO ||
                circ->purpose == CIRCUIT_PURPOSE_TESTING ||
                (circ->purpose >= CIRCUIT_PURPOSE_C_INTRODUCING &&
                circ->purpose <= CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED) ||
                circ->purpose == CIRCUIT_PURPOSE_S_CONNECT_REND) {
          log_debug(LD_CIRC,
                    "Closing circuit that has been unused for %ld msec.",
                    tv_mdiff(&circ->timestamp_created, &now));
          circuit_mark_for_close(circ, END_CIRC_REASON_FINISHED);
        } else if (!TO_ORIGIN_CIRCUIT(circ)->is_ancient) {
          /* Server-side rend joined circuits can end up really old, because
           * they are reused by clients for longer than normal. The client
           * controls their lifespan. (They never become dirty, because
           * connection_exit_begin_conn() never marks anything as dirty.)
           * Similarly, server-side intro circuits last a long time. */
          if (circ->purpose != CIRCUIT_PURPOSE_S_REND_JOINED &&
              circ->purpose != CIRCUIT_PURPOSE_S_INTRO) {
            log_notice(LD_CIRC,
                       "Ancient non-dirty circuit %d is still around after "
                       "%ld milliseconds. Purpose: %d (%s)",
                       TO_ORIGIN_CIRCUIT(circ)->global_identifier,
                       tv_mdiff(&circ->timestamp_created, &now),
                       circ->purpose,
                       circuit_purpose_to_string(circ->purpose));
            TO_ORIGIN_CIRCUIT(circ)->is_ancient = 1;
          }
        }
      }
    }
  }
}

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Find each non-origin circuit that has been unused for too long, has no streams on it, used a create_fast, and ends here: mark it for close.

Definition at line 967 of file circuituse.c.

{
  circuit_t *circ;
  or_circuit_t *or_circ;
  time_t cutoff = now - IDLE_ONE_HOP_CIRC_TIMEOUT;

  for (circ = global_circuitlist; circ; circ = circ->next) {
    if (circ->marked_for_close || CIRCUIT_IS_ORIGIN(circ))
      continue;
    or_circ = TO_OR_CIRCUIT(circ);
    /* If the circuit has been idle for too long, and there are no streams
     * on it, and it ends here, and it used a create_fast, mark it for close.
     */
    if (or_circ->is_first_hop && !circ->n_conn &&
        !or_circ->n_streams && !or_circ->resolving_streams &&
        or_circ->p_conn &&
        or_circ->p_conn->timestamp_last_added_nonpadding <= cutoff) {
      log_info(LD_CIRC, "Closing circ_id %d (empty %d secs ago)",
               or_circ->p_circ_id,
               (int)(now - or_circ->p_conn->timestamp_last_added_nonpadding));
      circuit_mark_for_close(circ, END_CIRC_REASON_FINISHED);
    }
  }
}

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static origin_circuit_t* circuit_get_best ( const entry_connection_t conn,
int  must_be_open,
uint8_t  purpose,
int  need_uptime,
int  need_internal 
) [static]

Find the best circ that conn can use, preferably one which is dirty.

Circ must not be too old.

Conn must be defined.

If must_be_open, ignore circs not in CIRCUIT_STATE_OPEN.

circ_purpose specifies what sort of circuit we must have. It can be C_GENERAL, C_INTRODUCE_ACK_WAIT, or C_REND_JOINED.

If it's REND_JOINED and must_be_open==0, then return the closest rendezvous-purposed circuit that you can find.

If it's INTRODUCE_ACK_WAIT and must_be_open==0, then return the closest introduce-purposed circuit that you can find.

Definition at line 250 of file circuituse.c.

{
  circuit_t *circ;
  origin_circuit_t *best=NULL;
  struct timeval now;
  int intro_going_on_but_too_old = 0;

  tor_assert(conn);

  tor_assert(purpose == CIRCUIT_PURPOSE_C_GENERAL ||
             purpose == CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT ||
             purpose == CIRCUIT_PURPOSE_C_REND_JOINED);

  tor_gettimeofday(&now);

  for (circ=global_circuitlist;circ;circ = circ->next) {
    origin_circuit_t *origin_circ;
    if (!CIRCUIT_IS_ORIGIN(circ))
      continue;
    origin_circ = TO_ORIGIN_CIRCUIT(circ);
    if (!circuit_is_acceptable(origin_circ,conn,must_be_open,purpose,
                               need_uptime,need_internal,now.tv_sec))
      continue;

    if (purpose == CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT &&
        !must_be_open && circ->state != CIRCUIT_STATE_OPEN &&
        tv_mdiff(&now, &circ->timestamp_created) > circ_times.timeout_ms) {
      intro_going_on_but_too_old = 1;
      continue;
    }

    /* now this is an acceptable circ to hand back. but that doesn't
     * mean it's the *best* circ to hand back. try to decide.
     */
    if (!best || circuit_is_better(origin_circ,best,conn))
      best = origin_circ;
  }

  if (!best && intro_going_on_but_too_old)
    log_info(LD_REND|LD_CIRC, "There is an intro circuit being created "
             "right now, but it has already taken quite a while. Starting "
             "one in parallel.");

  return best;
}

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static int circuit_get_open_circ_or_launch ( entry_connection_t conn,
uint8_t  desired_circuit_purpose,
origin_circuit_t **  circp 
) [static]

Find an open circ that we're happy to use for conn and return 1.

If there isn't one, and there isn't one on the way, launch one and return 0. If it will never work, return -1.

Write the found or in-progress or launched circ into *circp.

Definition at line 1395 of file circuituse.c.

{
  origin_circuit_t *circ;
  int check_exit_policy;
  int need_uptime, need_internal;
  int want_onehop;
  const or_options_t *options = get_options();

  tor_assert(conn);
  tor_assert(circp);
  tor_assert(ENTRY_TO_CONN(conn)->state == AP_CONN_STATE_CIRCUIT_WAIT);
  check_exit_policy =
      conn->socks_request->command == SOCKS_COMMAND_CONNECT &&
      !conn->use_begindir &&
      !connection_edge_is_rendezvous_stream(ENTRY_TO_EDGE_CONN(conn));
  want_onehop = conn->want_onehop;

  need_uptime = !conn->want_onehop && !conn->use_begindir &&
                smartlist_string_num_isin(options->LongLivedPorts,
                                          conn->socks_request->port);

  if (desired_circuit_purpose != CIRCUIT_PURPOSE_C_GENERAL)
    need_internal = 1;
  else if (conn->use_begindir || conn->want_onehop)
    need_internal = 1;
  else
    need_internal = 0;

  circ = circuit_get_best(conn, 1, desired_circuit_purpose,
                          need_uptime, need_internal);

  if (circ) {
    *circp = circ;
    return 1; /* we're happy */
  }

  if (!want_onehop && !router_have_minimum_dir_info()) {
    if (!connection_get_by_type(CONN_TYPE_DIR)) {
      int severity = LOG_NOTICE;
      /* FFFF if this is a tunneled directory fetch, don't yell
       * as loudly. the user doesn't even know it's happening. */
      if (entry_list_is_constrained(options) &&
          entries_known_but_down(options)) {
        log_fn(severity, LD_APP|LD_DIR,
               "Application request when we haven't used client functionality "
               "lately. Optimistically trying known %s again.",
               options->UseBridges ? "bridges" : "entrynodes");
        entries_retry_all(options);
      } else if (!options->UseBridges || any_bridge_descriptors_known()) {
        log_fn(severity, LD_APP|LD_DIR,
               "Application request when we haven't used client functionality "
               "lately. Optimistically trying directory fetches again.");
        routerlist_retry_directory_downloads(time(NULL));
      }
    }
    /* the stream will be dealt with when router_have_minimum_dir_info becomes
     * 1, or when all directory attempts fail and directory_all_unreachable()
     * kills it.
     */
    return 0;
  }

  /* Do we need to check exit policy? */
  if (check_exit_policy) {
    if (!conn->chosen_exit_name) {
      struct in_addr in;
      tor_addr_t addr, *addrp=NULL;
      if (tor_inet_aton(conn->socks_request->address, &in)) {
        tor_addr_from_in(&addr, &in);
        addrp = &addr;
      }
      if (router_exit_policy_all_nodes_reject(addrp,
                                              conn->socks_request->port,
                                              need_uptime)) {
        log_notice(LD_APP,
                   "No Tor server allows exit to %s:%d. Rejecting.",
                   safe_str_client(conn->socks_request->address),
                   conn->socks_request->port);
        return -1;
      }
    } else {
      /* XXXX024 Duplicates checks in connection_ap_handshake_attach_circuit:
       * refactor into a single function? */
      const node_t *node = node_get_by_nickname(conn->chosen_exit_name, 1);
      int opt = conn->chosen_exit_optional;
      if (node && !connection_ap_can_use_exit(conn, node)) {
        log_fn(opt ? LOG_INFO : LOG_WARN, LD_APP,
               "Requested exit point '%s' is excluded or "
               "would refuse request. %s.",
               conn->chosen_exit_name, opt ? "Trying others" : "Closing");
        if (opt) {
          conn->chosen_exit_optional = 0;
          tor_free(conn->chosen_exit_name);
          /* Try again. */
          return circuit_get_open_circ_or_launch(conn,
                                                 desired_circuit_purpose,
                                                 circp);
        }
        return -1;
      }
    }
  }

  /* is one already on the way? */
  circ = circuit_get_best(conn, 0, desired_circuit_purpose,
                          need_uptime, need_internal);
  if (circ)
    log_debug(LD_CIRC, "one on the way!");
  if (!circ) {
    extend_info_t *extend_info=NULL;
    uint8_t new_circ_purpose;
    const int n_pending = count_pending_general_client_circuits();

    if (n_pending >= options->MaxClientCircuitsPending) {
      static ratelim_t delay_limit = RATELIM_INIT(10*60);
      char *m;
      if ((m = rate_limit_log(&delay_limit, approx_time()))) {
        log_notice(LD_APP, "We'd like to launch a circuit to handle a "
                   "connection, but we already have %d general-purpose client "
                   "circuits pending. Waiting until some finish.",
                   n_pending);
        tor_free(m);
      }
      return 0;
    }

    if (desired_circuit_purpose == CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT) {
      /* need to pick an intro point */
      rend_data_t *rend_data = ENTRY_TO_EDGE_CONN(conn)->rend_data;
      tor_assert(rend_data);
      extend_info = rend_client_get_random_intro(rend_data);
      if (!extend_info) {
        log_info(LD_REND,
                 "No intro points for '%s': re-fetching service descriptor.",
                 safe_str_client(rend_data->onion_address));
        rend_client_refetch_v2_renddesc(rend_data);
        ENTRY_TO_CONN(conn)->state = AP_CONN_STATE_RENDDESC_WAIT;
        return 0;
      }
      log_info(LD_REND,"Chose %s as intro point for '%s'.",
               extend_info_describe(extend_info),
               safe_str_client(rend_data->onion_address));
    }

    /* If we have specified a particular exit node for our
     * connection, then be sure to open a circuit to that exit node.
     */
    if (desired_circuit_purpose == CIRCUIT_PURPOSE_C_GENERAL) {
      if (conn->chosen_exit_name) {
        const node_t *r;
        int opt = conn->chosen_exit_optional;
        r = node_get_by_nickname(conn->chosen_exit_name, 1);
        if (r && node_has_descriptor(r)) {
          /* We might want to connect to an IPv6 bridge for loading
             descriptors so we use the preferred address rather than
             the primary.  */
          extend_info = extend_info_from_node(r, conn->want_onehop ? 1 : 0);
        } else {
          log_debug(LD_DIR, "considering %d, %s",
                    want_onehop, conn->chosen_exit_name);
          if (want_onehop && conn->chosen_exit_name[0] == '$') {
            /* We're asking for a one-hop circuit to a router that
             * we don't have a routerinfo about. Make up an extend_info. */
            char digest[DIGEST_LEN];
            char *hexdigest = conn->chosen_exit_name+1;
            tor_addr_t addr;
            if (strlen(hexdigest) < HEX_DIGEST_LEN ||
                base16_decode(digest,DIGEST_LEN,hexdigest,HEX_DIGEST_LEN)<0) {
              log_info(LD_DIR, "Broken exit digest on tunnel conn. Closing.");
              return -1;
            }
            if (tor_addr_parse(&addr, conn->socks_request->address) < 0) {
              log_info(LD_DIR, "Broken address %s on tunnel conn. Closing.",
                       escaped_safe_str_client(conn->socks_request->address));
              return -1;
            }
            extend_info = extend_info_alloc(conn->chosen_exit_name+1,
                                            digest, NULL, &addr,
                                            conn->socks_request->port);
          } else {
            /* We will need an onion key for the router, and we
             * don't have one. Refuse or relax requirements. */
            log_fn(opt ? LOG_INFO : LOG_WARN, LD_APP,
                   "Requested exit point '%s' is not known. %s.",
                   conn->chosen_exit_name, opt ? "Trying others" : "Closing");
            if (opt) {
              conn->chosen_exit_optional = 0;
              tor_free(conn->chosen_exit_name);
              /* Try again with no requested exit */
              return circuit_get_open_circ_or_launch(conn,
                                                     desired_circuit_purpose,
                                                     circp);
            }
            return -1;
          }
        }
      }
    }

    if (desired_circuit_purpose == CIRCUIT_PURPOSE_C_REND_JOINED)
      new_circ_purpose = CIRCUIT_PURPOSE_C_ESTABLISH_REND;
    else if (desired_circuit_purpose == CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT)
      new_circ_purpose = CIRCUIT_PURPOSE_C_INTRODUCING;
    else
      new_circ_purpose = desired_circuit_purpose;

    if (options->Tor2webMode &&
        (new_circ_purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND ||
         new_circ_purpose == CIRCUIT_PURPOSE_C_INTRODUCING)) {
      want_onehop = 1;
    }

    {
      int flags = CIRCLAUNCH_NEED_CAPACITY;
      if (want_onehop) flags |= CIRCLAUNCH_ONEHOP_TUNNEL;
      if (need_uptime) flags |= CIRCLAUNCH_NEED_UPTIME;
      if (need_internal) flags |= CIRCLAUNCH_IS_INTERNAL;
      circ = circuit_launch_by_extend_info(new_circ_purpose, extend_info,
                                           flags);
    }

    extend_info_free(extend_info);

    if (desired_circuit_purpose == CIRCUIT_PURPOSE_C_GENERAL) {
      /* We just caused a circuit to get built because of this stream.
       * If this stream has caused a _lot_ of circuits to be built, that's
       * a bad sign: we should tell the user. */
      if (conn->num_circuits_launched < NUM_CIRCUITS_LAUNCHED_THRESHOLD &&
          ++conn->num_circuits_launched == NUM_CIRCUITS_LAUNCHED_THRESHOLD)
        log_info(LD_CIRC, "The application request to %s:%d has launched "
                 "%d circuits without finding one it likes.",
                 escaped_safe_str_client(conn->socks_request->address),
                 conn->socks_request->port,
                 conn->num_circuits_launched);
    } else {
      /* help predict this next time */
      rep_hist_note_used_internal(time(NULL), need_uptime, 1);
      if (circ) {
        /* write the service_id into circ */
        circ->rend_data = rend_data_dup(ENTRY_TO_EDGE_CONN(conn)->rend_data);
        if (circ->_base.purpose == CIRCUIT_PURPOSE_C_ESTABLISH_REND &&
            circ->_base.state == CIRCUIT_STATE_OPEN)
          rend_client_rendcirc_has_opened(circ);
      }
    }
  } /* endif (!circ) */
  if (circ) {
    /* Mark the circuit with the isolation fields for this connection.
     * When the circuit arrives, we'll clear these flags: this is
     * just some internal bookkeeping to make sure that we have
     * launched enough circuits.
     */
    connection_edge_update_circuit_isolation(conn, circ, 0);
  } else {
    log_info(LD_APP,
             "No safe circuit (purpose %d) ready for edge "
             "connection; delaying.",
             desired_circuit_purpose);
  }
  *circp = circ;
  return 0;
}

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The circuit circ has just become open.

Take the next step: for rendezvous circuits, we pass circ to the appropriate function in rendclient or rendservice. For general circuits, we call connection_ap_attach_pending, which looks for pending streams that could use circ.

Definition at line 1075 of file circuituse.c.

{
  control_event_circuit_status(circ, CIRC_EVENT_BUILT, 0);

  /* Remember that this circuit has finished building. Now if we start
   * it building again later (e.g. by extending it), we will know not
   * to consider its build time. */
  circ->has_opened = 1;

  switch (TO_CIRCUIT(circ)->purpose) {
    case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
      rend_client_rendcirc_has_opened(circ);
      /* Start building an intro circ if we don't have one yet. */
      connection_ap_attach_pending();
      /* This isn't a call to circuit_try_attaching_streams because a
       * circuit in _C_ESTABLISH_REND state isn't connected to its
       * hidden service yet, thus we can't attach streams to it yet,
       * thus circuit_try_attaching_streams would always clear the
       * circuit's isolation state.  circuit_try_attaching_streams is
       * called later, when the rend circ enters _C_REND_JOINED
       * state. */
      break;
    case CIRCUIT_PURPOSE_C_INTRODUCING:
      rend_client_introcirc_has_opened(circ);
      break;
    case CIRCUIT_PURPOSE_C_GENERAL:
      /* Tell any AP connections that have been waiting for a new
       * circuit that one is ready. */
      circuit_try_attaching_streams(circ);
      break;
    case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:
      /* at Bob, waiting for introductions */
      rend_service_intro_has_opened(circ);
      break;
    case CIRCUIT_PURPOSE_S_CONNECT_REND:
      /* at Bob, connecting to rend point */
      rend_service_rendezvous_has_opened(circ);
      break;
    case CIRCUIT_PURPOSE_TESTING:
      circuit_testing_opened(circ);
      break;
    /* default:
     * This won't happen in normal operation, but might happen if the
     * controller did it. Just let it slide. */
  }
}

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static void circuit_increment_failure_count ( void  ) [static]

Record another failure at opening a general circuit.

When we have too many, we'll stop trying for the remainder of this minute.

Definition at line 1368 of file circuituse.c.

{
  ++n_circuit_failures;
  log_debug(LD_CIRC,"n_circuit_failures now %d.",n_circuit_failures);
}

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static int circuit_is_acceptable ( const origin_circuit_t origin_circ,
const entry_connection_t conn,
int  must_be_open,
uint8_t  purpose,
int  need_uptime,
int  need_internal,
time_t  now 
) [static]

Return 1 if circ could be returned by circuit_get_best().

Else return 0.

Definition at line 43 of file circuituse.c.

{
  const circuit_t *circ = TO_CIRCUIT(origin_circ);
  const node_t *exitnode;
  cpath_build_state_t *build_state;
  tor_assert(circ);
  tor_assert(conn);
  tor_assert(conn->socks_request);

  if (must_be_open && (circ->state != CIRCUIT_STATE_OPEN || !circ->n_conn))
    return 0; /* ignore non-open circs */
  if (circ->marked_for_close)
    return 0;

  /* if this circ isn't our purpose, skip. */
  if (purpose == CIRCUIT_PURPOSE_C_REND_JOINED && !must_be_open) {
    if (circ->purpose != CIRCUIT_PURPOSE_C_ESTABLISH_REND &&
        circ->purpose != CIRCUIT_PURPOSE_C_REND_READY &&
        circ->purpose != CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED &&
        circ->purpose != CIRCUIT_PURPOSE_C_REND_JOINED)
      return 0;
  } else if (purpose == CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT &&
             !must_be_open) {
    if (circ->purpose != CIRCUIT_PURPOSE_C_INTRODUCING &&
        circ->purpose != CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT)
      return 0;
  } else {
    if (purpose != circ->purpose)
      return 0;
  }

  /* If this is a timed-out hidden service circuit, skip it. */
  if (origin_circ->hs_circ_has_timed_out) {
    return 0;
  }

  if (purpose == CIRCUIT_PURPOSE_C_GENERAL ||
      purpose == CIRCUIT_PURPOSE_C_REND_JOINED)
    if (circ->timestamp_dirty &&
       circ->timestamp_dirty+get_options()->MaxCircuitDirtiness <= now)
      return 0;

  /* decide if this circ is suitable for this conn */

  /* for rend circs, circ->cpath->prev is not the last router in the
   * circuit, it's the magical extra bob hop. so just check the nickname
   * of the one we meant to finish at.
   */
  build_state = origin_circ->build_state;
  exitnode = build_state_get_exit_node(build_state);

  if (need_uptime && !build_state->need_uptime)
    return 0;
  if (need_internal != build_state->is_internal)
    return 0;

  if (purpose == CIRCUIT_PURPOSE_C_GENERAL) {
    if (!exitnode && !build_state->onehop_tunnel) {
      log_debug(LD_CIRC,"Not considering circuit with unknown router.");
      return 0; /* this circuit is screwed and doesn't know it yet,
                 * or is a rendezvous circuit. */
    }
    if (build_state->onehop_tunnel) {
      if (!conn->want_onehop) {
        log_debug(LD_CIRC,"Skipping one-hop circuit.");
        return 0;
      }
      tor_assert(conn->chosen_exit_name);
      if (build_state->chosen_exit) {
        char digest[DIGEST_LEN];
        if (hexdigest_to_digest(conn->chosen_exit_name, digest) < 0)
          return 0; /* broken digest, we don't want it */
        if (tor_memneq(digest, build_state->chosen_exit->identity_digest,
                          DIGEST_LEN))
          return 0; /* this is a circuit to somewhere else */
        if (tor_digest_is_zero(digest)) {
          /* we don't know the digest; have to compare addr:port */
          tor_addr_t addr;
          int r = tor_addr_parse(&addr, conn->socks_request->address);
          if (r < 0 ||
              !tor_addr_eq(&build_state->chosen_exit->addr, &addr) ||
              build_state->chosen_exit->port != conn->socks_request->port)
            return 0;
        }
      }
    } else {
      if (conn->want_onehop) {
        /* don't use three-hop circuits -- that could hurt our anonymity. */
        return 0;
      }
    }
    if (exitnode && !connection_ap_can_use_exit(conn, exitnode)) {
      /* can't exit from this router */
      return 0;
    }
  } else { /* not general */
    const edge_connection_t *edge_conn = ENTRY_TO_EDGE_CONN(conn);
    if ((edge_conn->rend_data && !origin_circ->rend_data) ||
        (!edge_conn->rend_data && origin_circ->rend_data) ||
        (edge_conn->rend_data && origin_circ->rend_data &&
         rend_cmp_service_ids(edge_conn->rend_data->onion_address,
                              origin_circ->rend_data->onion_address))) {
      /* this circ is not for this conn */
      return 0;
    }
  }

  if (!connection_edge_compatible_with_circuit(conn, origin_circ)) {
    /* conn needs to be isolated from other conns that have already used
     * origin_circ */
    return 0;
  }

  return 1;
}

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static int circuit_is_better ( const origin_circuit_t oa,
const origin_circuit_t ob,
const entry_connection_t conn 
) [static]

Return 1 if circuit a is better than circuit b for conn, and return 0 otherwise.

Used by circuit_get_best.

Definition at line 167 of file circuituse.c.

{
  const circuit_t *a = TO_CIRCUIT(oa);
  const circuit_t *b = TO_CIRCUIT(ob);
  const uint8_t purpose = ENTRY_TO_CONN(conn)->purpose;
  int a_bits, b_bits;

  switch (purpose) {
    case CIRCUIT_PURPOSE_C_GENERAL:
      /* if it's used but less dirty it's best;
       * else if it's more recently created it's best
       */
      if (b->timestamp_dirty) {
        if (a->timestamp_dirty &&
            a->timestamp_dirty > b->timestamp_dirty)
          return 1;
      } else {
        if (a->timestamp_dirty ||
            timercmp(&a->timestamp_created, &b->timestamp_created, >))
          return 1;
        if (ob->build_state->is_internal)
          /* XXX023 what the heck is this internal thing doing here. I
           * think we can get rid of it. circuit_is_acceptable() already
           * makes sure that is_internal is exactly what we need it to
           * be. -RD */
          return 1;
      }
      break;
    case CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT:
      /* the closer it is to ack_wait the better it is */
      if (a->purpose > b->purpose)
        return 1;
      break;
    case CIRCUIT_PURPOSE_C_REND_JOINED:
      /* the closer it is to rend_joined the better it is */
      if (a->purpose > b->purpose)
        return 1;
      break;
  }

  /* XXXX023 Maybe this check should get a higher priority to avoid
   *   using up circuits too rapidly. */

  a_bits = connection_edge_update_circuit_isolation(conn,
                                                    (origin_circuit_t*)oa, 1);
  b_bits = connection_edge_update_circuit_isolation(conn,
                                                    (origin_circuit_t*)ob, 1);
  /* if x_bits < 0, then we have not used x for anything; better not to dirty
   * a connection if we can help it. */
  if (a_bits < 0) {
    return 0;
  } else if (b_bits < 0) {
    return 1;
  }
  a_bits &= ~ oa->isolation_flags_mixed;
  a_bits &= ~ ob->isolation_flags_mixed;
  if (n_bits_set_u8(a_bits) < n_bits_set_u8(b_bits)) {
    /* The fewer new restrictions we need to make on a circuit for stream
     * isolation, the better. */
    return 1;
  }

  return 0;
}

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origin_circuit_t* circuit_launch ( uint8_t  purpose,
int  flags 
)

Launch a new circuit; see circuit_launch_by_extend_info() for details on arguments.

Definition at line 1279 of file circuituse.c.

{
  return circuit_launch_by_extend_info(purpose, NULL, flags);
}

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origin_circuit_t* circuit_launch_by_extend_info ( uint8_t  purpose,
extend_info_t extend_info,
int  flags 
)

Launch a new circuit with purpose purpose and exit node extend_info (or NULL to select a random exit node).

If flags contains CIRCLAUNCH_NEED_UPTIME, choose among routers with high uptime. If CIRCLAUNCH_NEED_CAPACITY is set, choose among routers with high bandwidth. If CIRCLAUNCH_IS_INTERNAL is true, the last hop need not be an exit node. If CIRCLAUNCH_ONEHOP_TUNNEL is set, the circuit will have only one hop. Return the newly allocated circuit on success, or NULL on failure.

Definition at line 1292 of file circuituse.c.

{
  origin_circuit_t *circ;
  int onehop_tunnel = (flags & CIRCLAUNCH_ONEHOP_TUNNEL) != 0;

  if (!onehop_tunnel && !router_have_minimum_dir_info()) {
    log_debug(LD_CIRC,"Haven't fetched enough directory info yet; canceling "
              "circuit launch.");
    return NULL;
  }

  if ((extend_info || purpose != CIRCUIT_PURPOSE_C_GENERAL) &&
      purpose != CIRCUIT_PURPOSE_TESTING && !onehop_tunnel) {
    /* see if there are appropriate circs available to cannibalize. */
    /* XXX if we're planning to add a hop, perhaps we want to look for
     * internal circs rather than exit circs? -RD */
    circ = circuit_find_to_cannibalize(purpose, extend_info, flags);
    if (circ) {
      uint8_t old_purpose = circ->_base.purpose;
      struct timeval old_timestamp_created;

      log_info(LD_CIRC,"Cannibalizing circ '%s' for purpose %d (%s)",
               build_state_get_exit_nickname(circ->build_state), purpose,
               circuit_purpose_to_string(purpose));

      circuit_change_purpose(TO_CIRCUIT(circ), purpose);
      /* reset the birth date of this circ, else expire_building
       * will see it and think it's been trying to build since it
       * began. */
      tor_gettimeofday(&circ->_base.timestamp_created);

      control_event_circuit_cannibalized(circ, old_purpose,
                                         &old_timestamp_created);

      switch (purpose) {
        case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
        case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:
          /* it's ready right now */
          break;
        case CIRCUIT_PURPOSE_C_INTRODUCING:
        case CIRCUIT_PURPOSE_S_CONNECT_REND:
        case CIRCUIT_PURPOSE_C_GENERAL:
          /* need to add a new hop */
          tor_assert(extend_info);
          if (circuit_extend_to_new_exit(circ, extend_info) < 0)
            return NULL;
          break;
        default:
          log_warn(LD_BUG,
                   "unexpected purpose %d when cannibalizing a circ.",
                   purpose);
          tor_fragile_assert();
          return NULL;
      }
      return circ;
    }
  }

  if (did_circs_fail_last_period &&
      n_circuit_failures > MAX_CIRCUIT_FAILURES) {
    /* too many failed circs in a row. don't try. */
//    log_fn(LOG_INFO,"%d failures so far, not trying.",n_circuit_failures);
    return NULL;
  }

  /* try a circ. if it fails, circuit_mark_for_close will increment
   * n_circuit_failures */
  return circuit_establish_circuit(purpose, extend_info, flags);
}

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static void circuit_predict_and_launch_new ( void  ) [static]

Figure out how many circuits we have open that are clean.

Make sure it's enough for all the upcoming behaviors we predict we'll have. But put an upper bound on the total number of circuits.

Definition at line 664 of file circuituse.c.

{
  circuit_t *circ;
  int num=0, num_internal=0, num_uptime_internal=0;
  int hidserv_needs_uptime=0, hidserv_needs_capacity=1;
  int port_needs_uptime=0, port_needs_capacity=1;
  time_t now = time(NULL);
  int flags = 0;

  /* First, count how many of each type of circuit we have already. */
  for (circ=global_circuitlist;circ;circ = circ->next) {
    cpath_build_state_t *build_state;
    if (!CIRCUIT_IS_ORIGIN(circ))
      continue;
    if (circ->marked_for_close)
      continue; /* don't mess with marked circs */
    if (circ->timestamp_dirty)
      continue; /* only count clean circs */
    if (circ->purpose != CIRCUIT_PURPOSE_C_GENERAL)
      continue; /* only pay attention to general-purpose circs */
    build_state = TO_ORIGIN_CIRCUIT(circ)->build_state;
    if (build_state->onehop_tunnel)
      continue;
    num++;
    if (build_state->is_internal)
      num_internal++;
    if (build_state->need_uptime && build_state->is_internal)
      num_uptime_internal++;
  }

  /* If that's enough, then stop now. */
  if (num >= MAX_UNUSED_OPEN_CIRCUITS)
    return; /* we already have many, making more probably will hurt */

  /* Second, see if we need any more exit circuits. */
  /* check if we know of a port that's been requested recently
   * and no circuit is currently available that can handle it. */
  if (!circuit_all_predicted_ports_handled(now, &port_needs_uptime,
                                           &port_needs_capacity)) {
    if (port_needs_uptime)
      flags |= CIRCLAUNCH_NEED_UPTIME;
    if (port_needs_capacity)
      flags |= CIRCLAUNCH_NEED_CAPACITY;
    log_info(LD_CIRC,
             "Have %d clean circs (%d internal), need another exit circ.",
             num, num_internal);
    circuit_launch(CIRCUIT_PURPOSE_C_GENERAL, flags);
    return;
  }

  /* Third, see if we need any more hidden service (server) circuits. */
  if (num_rend_services() && num_uptime_internal < 3) {
    flags = (CIRCLAUNCH_NEED_CAPACITY | CIRCLAUNCH_NEED_UPTIME |
             CIRCLAUNCH_IS_INTERNAL);
    log_info(LD_CIRC,
             "Have %d clean circs (%d internal), need another internal "
             "circ for my hidden service.",
             num, num_internal);
    circuit_launch(CIRCUIT_PURPOSE_C_GENERAL, flags);
    return;
  }

  /* Fourth, see if we need any more hidden service (client) circuits. */
  if (rep_hist_get_predicted_internal(now, &hidserv_needs_uptime,
                                      &hidserv_needs_capacity) &&
      ((num_uptime_internal<2 && hidserv_needs_uptime) ||
        num_internal<2)) {
    if (hidserv_needs_uptime)
      flags |= CIRCLAUNCH_NEED_UPTIME;
    if (hidserv_needs_capacity)
      flags |= CIRCLAUNCH_NEED_CAPACITY;
    flags |= CIRCLAUNCH_IS_INTERNAL;
    log_info(LD_CIRC,
             "Have %d clean circs (%d uptime-internal, %d internal), need"
             " another hidden service circ.",
             num, num_uptime_internal, num_internal);
    circuit_launch(CIRCUIT_PURPOSE_C_GENERAL, flags);
    return;
  }

  /* Finally, check to see if we still need more circuits to learn
   * a good build timeout. But if we're close to our max number we
   * want, don't do another -- we want to leave a few slots open so
   * we can still build circuits preemptively as needed. */
  if (num < MAX_UNUSED_OPEN_CIRCUITS-2 &&
      get_options()->LearnCircuitBuildTimeout &&
      circuit_build_times_needs_circuits_now(&circ_times)) {
    flags = CIRCLAUNCH_NEED_CAPACITY;
    log_info(LD_CIRC,
             "Have %d clean circs need another buildtime test circ.", num);
    circuit_launch(CIRCUIT_PURPOSE_C_GENERAL, flags);
    return;
  }
}

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void circuit_remove_handled_ports ( smartlist_t needed_ports)

Remove any elements in needed_ports that are handled by an open or in-progress circuit.

Definition at line 591 of file circuituse.c.

{
  int i;
  uint16_t *port;

  for (i = 0; i < smartlist_len(needed_ports); ++i) {
    port = smartlist_get(needed_ports, i);
    tor_assert(*port);
    if (circuit_stream_is_being_handled(NULL, *port,
                                        MIN_CIRCUITS_HANDLING_STREAM)) {
//      log_debug(LD_CIRC,"Port %d is already being handled; removing.", port);
      smartlist_del(needed_ports, i--);
      tor_free(port);
    } else {
      log_debug(LD_CIRC,"Port %d is not handled.", *port);
    }
  }
}

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void circuit_reset_failure_count ( int  timeout)

Reset the failure count for opening general circuits.

This means we will try MAX_CIRCUIT_FAILURES times more (if necessary) before stopping again.

Definition at line 1379 of file circuituse.c.

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int circuit_stream_is_being_handled ( entry_connection_t conn,
uint16_t  port,
int  min 
)

Return 1 if at least min general-purpose non-internal circuits will have an acceptable exit node for exit stream conn if it is defined, else for "*:port".

Else return 0.

Definition at line 616 of file circuituse.c.

{
  circuit_t *circ;
  const node_t *exitnode;
  int num=0;
  time_t now = time(NULL);
  int need_uptime = smartlist_string_num_isin(get_options()->LongLivedPorts,
                                   conn ? conn->socks_request->port : port);

  for (circ=global_circuitlist;circ;circ = circ->next) {
    if (CIRCUIT_IS_ORIGIN(circ) &&
        !circ->marked_for_close &&
        circ->purpose == CIRCUIT_PURPOSE_C_GENERAL &&
        (!circ->timestamp_dirty ||
         circ->timestamp_dirty + get_options()->MaxCircuitDirtiness > now)) {
      cpath_build_state_t *build_state = TO_ORIGIN_CIRCUIT(circ)->build_state;
      if (build_state->is_internal || build_state->onehop_tunnel)
        continue;

      exitnode = build_state_get_exit_node(build_state);
      if (exitnode && (!need_uptime || build_state->need_uptime)) {
        int ok;
        if (conn) {
          ok = connection_ap_can_use_exit(conn, exitnode);
        } else {
          addr_policy_result_t r;
          r = compare_tor_addr_to_node_policy(NULL, port, exitnode);
          ok = r != ADDR_POLICY_REJECTED && r != ADDR_POLICY_PROBABLY_REJECTED;
        }
        if (ok) {
          if (++num >= min)
            return 1;
        }
      }
    }
  }
  return 0;
}

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static void circuit_testing_failed ( origin_circuit_t circ,
int  at_last_hop 
) [static]

A testing circuit has failed to build.

Take whatever stats we want.

Definition at line 1054 of file circuituse.c.

{
  if (server_mode(get_options()) && check_whether_orport_reachable())
    return;

  log_info(LD_GENERAL,
           "Our testing circuit (to see if your ORPort is reachable) "
           "has failed. I'll try again later.");

  /* These aren't used yet. */
  (void)circ;
  (void)at_last_hop;
}

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static void circuit_testing_opened ( origin_circuit_t circ) [static]

A testing circuit has completed.

Take whatever stats we want. Noticing reachability is taken care of in onionskin_answer(), so there's no need to record anything here. But if we still want to do the bandwidth test, and we now have enough testing circuits open, do it.

Definition at line 1036 of file circuituse.c.

{
  if (have_performed_bandwidth_test ||
      !check_whether_orport_reachable()) {
    /* either we've already done everything we want with testing circuits,
     * or this testing circuit became open due to a fluke, e.g. we picked
     * a last hop where we already had the connection open due to an
     * outgoing local circuit. */
    circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_AT_ORIGIN);
  } else if (circuit_enough_testing_circs()) {
    router_perform_bandwidth_test(NUM_PARALLEL_TESTING_CIRCS, time(NULL));
    have_performed_bandwidth_test = 1;
  } else
    consider_testing_reachability(1, 0);
}

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Called when a circuit becomes ready for streams to be attached to it.

Definition at line 1147 of file circuituse.c.

{
  /* Attach streams to this circuit if we can. */
  connection_ap_attach_pending();

  /* The call to circuit_try_clearing_isolation_state here will do
   * nothing and return 0 if we didn't attach any streams to circ
   * above. */
  if (circuit_try_clearing_isolation_state(circ)) {
    /* Maybe *now* we can attach some streams to this circuit. */
    connection_ap_attach_pending();
  }
}

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static int circuit_try_clearing_isolation_state ( origin_circuit_t circ) [static]

If the stream-isolation state of circ can be cleared, clear it.

Return non-zero iff circ's isolation state was cleared.

Definition at line 1125 of file circuituse.c.

{
  if (/* The circuit may have become non-open if it was cannibalized.*/
      circ->_base.state == CIRCUIT_STATE_OPEN &&
      /* If !isolation_values_set, there is nothing to clear. */
      circ->isolation_values_set &&
      /* It's not legal to clear a circuit's isolation info if it's ever had
       * streams attached */
      !circ->isolation_any_streams_attached) {
    /* If we have any isolation information set on this circuit, and
     * we didn't manage to attach any streams to it, then we can
     * and should clear it and try again. */
    circuit_clear_isolation(circ);
    return 1;
  } else {
    return 0;
  }
}

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Attempt to attach the connection conn to circ, and send a begin or resolve cell as appropriate.

Return values are as for connection_ap_handshake_attach_circuit. The stream will exit from the hop indicated by cpath, or from the last hop in circ's cpath if cpath is NULL.

Definition at line 1813 of file circuituse.c.

{
  connection_t *base_conn = ENTRY_TO_CONN(conn);
  tor_assert(conn);
  tor_assert(base_conn->state == AP_CONN_STATE_CIRCUIT_WAIT ||
             base_conn->state == AP_CONN_STATE_CONTROLLER_WAIT);
  tor_assert(conn->socks_request);
  tor_assert(circ);
  tor_assert(circ->_base.state == CIRCUIT_STATE_OPEN);

  base_conn->state = AP_CONN_STATE_CIRCUIT_WAIT;

  if (!circ->_base.timestamp_dirty)
    circ->_base.timestamp_dirty = time(NULL);

  link_apconn_to_circ(conn, circ, cpath);
  tor_assert(conn->socks_request);
  if (conn->socks_request->command == SOCKS_COMMAND_CONNECT) {
    if (!conn->use_begindir)
      consider_recording_trackhost(conn, circ);
    if (connection_ap_handshake_send_begin(conn) < 0)
      return -1;
  } else {
    if (connection_ap_handshake_send_resolve(conn) < 0)
      return -1;
  }

  return 1;
}

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Try to find a safe live circuit for CONN_TYPE_AP connection conn.

If we don't find one: if conn cannot be handled by any known nodes, warn and return -1 (conn needs to die, and is maybe already marked); else launch new circuit (if necessary) and return 0. Otherwise, associate conn with a safe live circuit, do the right next step, and return 1.

Definition at line 1855 of file circuituse.c.

{
  connection_t *base_conn = ENTRY_TO_CONN(conn);
  int retval;
  int conn_age;
  int want_onehop;

  tor_assert(conn);
  tor_assert(base_conn->state == AP_CONN_STATE_CIRCUIT_WAIT);
  tor_assert(conn->socks_request);
  want_onehop = conn->want_onehop;

  conn_age = (int)(time(NULL) - base_conn->timestamp_created);

  if (conn_age >= get_options()->SocksTimeout) {
    int severity = (tor_addr_is_null(&base_conn->addr) && !base_conn->port) ?
      LOG_INFO : LOG_NOTICE;
    log_fn(severity, LD_APP,
           "Tried for %d seconds to get a connection to %s:%d. Giving up.",
           conn_age, safe_str_client(conn->socks_request->address),
           conn->socks_request->port);
    return -1;
  }

  if (!connection_edge_is_rendezvous_stream(ENTRY_TO_EDGE_CONN(conn))) {
    /* we're a general conn */
    origin_circuit_t *circ=NULL;

    if (conn->chosen_exit_name) {
      const node_t *node = node_get_by_nickname(conn->chosen_exit_name, 1);
      int opt = conn->chosen_exit_optional;
      if (!node && !want_onehop) {
        /* We ran into this warning when trying to extend a circuit to a
         * hidden service directory for which we didn't have a router
         * descriptor. See flyspray task 767 for more details. We should
         * keep this in mind when deciding to use BEGIN_DIR cells for other
         * directory requests as well. -KL*/
        log_fn(opt ? LOG_INFO : LOG_WARN, LD_APP,
               "Requested exit point '%s' is not known. %s.",
               conn->chosen_exit_name, opt ? "Trying others" : "Closing");
        if (opt) {
          conn->chosen_exit_optional = 0;
          tor_free(conn->chosen_exit_name);
          return 0;
        }
        return -1;
      }
      if (node && !connection_ap_can_use_exit(conn, node)) {
        log_fn(opt ? LOG_INFO : LOG_WARN, LD_APP,
               "Requested exit point '%s' is excluded or "
               "would refuse request. %s.",
               conn->chosen_exit_name, opt ? "Trying others" : "Closing");
        if (opt) {
          conn->chosen_exit_optional = 0;
          tor_free(conn->chosen_exit_name);
          return 0;
        }
        return -1;
      }
    }

    /* find the circuit that we should use, if there is one. */
    retval = circuit_get_open_circ_or_launch(
        conn, CIRCUIT_PURPOSE_C_GENERAL, &circ);
    if (retval < 1) // XXX023 if we totally fail, this still returns 0 -RD
      return retval;

    log_debug(LD_APP|LD_CIRC,
              "Attaching apconn to circ %d (stream %d sec old).",
              circ->_base.n_circ_id, conn_age);
    /* print the circ's path, so people can figure out which circs are
     * sucking. */
    circuit_log_path(LOG_INFO,LD_APP|LD_CIRC,circ);

    /* We have found a suitable circuit for our conn. Hurray. */
    return connection_ap_handshake_attach_chosen_circuit(conn, circ, NULL);

  } else { /* we're a rendezvous conn */
    origin_circuit_t *rendcirc=NULL, *introcirc=NULL;

    tor_assert(!ENTRY_TO_EDGE_CONN(conn)->cpath_layer);

    /* start by finding a rendezvous circuit for us */

    retval = circuit_get_open_circ_or_launch(
       conn, CIRCUIT_PURPOSE_C_REND_JOINED, &rendcirc);
    if (retval < 0) return -1; /* failed */

    if (retval > 0) {
      tor_assert(rendcirc);
      /* one is already established, attach */
      log_info(LD_REND,
               "rend joined circ %d already here. attaching. "
               "(stream %d sec old)",
               rendcirc->_base.n_circ_id, conn_age);
      /* Mark rendezvous circuits as 'newly dirty' every time you use
       * them, since the process of rebuilding a rendezvous circ is so
       * expensive. There is a tradeoff between linkability and
       * feasibility, at this point.
       */
      rendcirc->_base.timestamp_dirty = time(NULL);
      link_apconn_to_circ(conn, rendcirc, NULL);
      if (connection_ap_handshake_send_begin(conn) < 0)
        return 0; /* already marked, let them fade away */
      return 1;
    }

    if (rendcirc && (rendcirc->_base.purpose ==
                     CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED)) {
      log_info(LD_REND,
               "pending-join circ %d already here, with intro ack. "
               "Stalling. (stream %d sec old)",
                rendcirc->_base.n_circ_id, conn_age);
      return 0;
    }

    /* it's on its way. find an intro circ. */
    retval = circuit_get_open_circ_or_launch(
      conn, CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT, &introcirc);
    if (retval < 0) return -1; /* failed */

    if (retval > 0) {
      /* one has already sent the intro. keep waiting. */
      circuit_t *c = NULL;
      tor_assert(introcirc);
      log_info(LD_REND, "Intro circ %d present and awaiting ack (rend %d). "
               "Stalling. (stream %d sec old)",
               introcirc->_base.n_circ_id,
               rendcirc ? rendcirc->_base.n_circ_id : 0,
               conn_age);
      /* abort parallel intro circs, if any */
      for (c = global_circuitlist; c; c = c->next) {
        if (c->purpose == CIRCUIT_PURPOSE_C_INTRODUCING &&
            !c->marked_for_close && CIRCUIT_IS_ORIGIN(c)) {
          origin_circuit_t *oc = TO_ORIGIN_CIRCUIT(c);
          if (oc->rend_data &&
              !rend_cmp_service_ids(
                            ENTRY_TO_EDGE_CONN(conn)->rend_data->onion_address,
                            oc->rend_data->onion_address)) {
            log_info(LD_REND|LD_CIRC, "Closing introduction circuit that we "
                     "built in parallel.");
            circuit_mark_for_close(c, END_CIRC_REASON_TIMEOUT);
          }
        }
      }
      return 0;
    }

    /* now rendcirc and introcirc are each either undefined or not finished */

    if (rendcirc && introcirc &&
        rendcirc->_base.purpose == CIRCUIT_PURPOSE_C_REND_READY) {
      log_info(LD_REND,
               "ready rend circ %d already here (no intro-ack yet on "
               "intro %d). (stream %d sec old)",
               rendcirc->_base.n_circ_id,
               introcirc->_base.n_circ_id, conn_age);

      tor_assert(introcirc->_base.purpose == CIRCUIT_PURPOSE_C_INTRODUCING);
      if (introcirc->_base.state == CIRCUIT_STATE_OPEN) {
        log_info(LD_REND,"found open intro circ %d (rend %d); sending "
                 "introduction. (stream %d sec old)",
                 introcirc->_base.n_circ_id, rendcirc->_base.n_circ_id,
                 conn_age);
        switch (rend_client_send_introduction(introcirc, rendcirc)) {
        case 0: /* success */
          rendcirc->_base.timestamp_dirty = time(NULL);
          introcirc->_base.timestamp_dirty = time(NULL);
          assert_circuit_ok(TO_CIRCUIT(rendcirc));
          assert_circuit_ok(TO_CIRCUIT(introcirc));
          return 0;
        case -1: /* transient error */
          return 0;
        case -2: /* permanent error */
          return -1;
        default: /* oops */
          tor_fragile_assert();
          return -1;
        }
      }
    }

    log_info(LD_REND, "Intro (%d) and rend (%d) circs are not both ready. "
             "Stalling conn. (%d sec old)",
             introcirc ? introcirc->_base.n_circ_id : 0,
             rendcirc ? rendcirc->_base.n_circ_id : 0, conn_age);
    return 0;
  }
}

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static void consider_recording_trackhost ( const entry_connection_t conn,
const origin_circuit_t circ 
) [static]

If an exit wasn't explicitly specified for conn, consider saving the exit that we did choose for use by future connections to conn's destination.

Definition at line 1775 of file circuituse.c.

{
  const or_options_t *options = get_options();
  char *new_address = NULL;
  char fp[HEX_DIGEST_LEN+1];

  /* Search the addressmap for this conn's destination. */
  /* If he's not in the address map.. */
  if (!options->TrackHostExits ||
      addressmap_have_mapping(conn->socks_request->address,
                              options->TrackHostExitsExpire))
    return; /* nothing to track, or already mapped */

  if (!hostname_in_track_host_exits(options, conn->socks_request->address) ||
      !circ->build_state->chosen_exit)
    return;

  /* write down the fingerprint of the chosen exit, not the nickname,
   * because the chosen exit might not be named. */
  base16_encode(fp, sizeof(fp),
                circ->build_state->chosen_exit->identity_digest, DIGEST_LEN);

  /* Add this exit/hostname pair to the addressmap. */
  tor_asprintf(&new_address, "%s.%s.exit",
               conn->socks_request->address, fp);

  addressmap_register(conn->socks_request->address, new_address,
                      time(NULL) + options->TrackHostExitsExpire,
                      ADDRMAPSRC_TRACKEXIT, 0, 0);
}

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static int count_pending_general_client_circuits ( void  ) [static]

Return the number of not-yet-open general-purpose origin circuits.

Definition at line 300 of file circuituse.c.

{
  const circuit_t *circ;

  int count = 0;

  for (circ = global_circuitlist; circ; circ = circ->next) {
    if (circ->marked_for_close ||
        circ->state == CIRCUIT_STATE_OPEN ||
        circ->purpose != CIRCUIT_PURPOSE_C_GENERAL ||
        !CIRCUIT_IS_ORIGIN(circ))
      continue;

    ++count;
  }

  return count;
}

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static int cpath_is_on_circuit ( origin_circuit_t circ,
crypt_path_t crypt_path 
) [static]

Return true iff crypt_path is one of the crypt_paths for circ.

Definition at line 1663 of file circuituse.c.

{
  crypt_path_t *cpath, *cpath_next = NULL;
  for (cpath = circ->cpath; cpath_next != circ->cpath; cpath = cpath_next) {
    cpath_next = cpath->next;
    if (crypt_path == cpath)
      return 1;
  }
  return 0;
}

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int hostname_in_track_host_exits ( const or_options_t options,
const char *  address 
)

Return true iff address is matched by one of the entries in TrackHostExits.

Definition at line 1753 of file circuituse.c.

{
  if (!options->TrackHostExits)
    return 0;
  SMARTLIST_FOREACH_BEGIN(options->TrackHostExits, const char *, cp) {
    if (cp[0] == '.') { /* match end */
      if (cp[1] == '\0' ||
          !strcasecmpend(address, cp) ||
          !strcasecmp(address, &cp[1]))
        return 1;
    } else if (strcasecmp(cp, address) == 0) {
      return 1;
    }
  } SMARTLIST_FOREACH_END(cp);
  return 0;
}

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static void link_apconn_to_circ ( entry_connection_t apconn,
origin_circuit_t circ,
crypt_path_t cpath 
) [static]

Attach the AP stream apconn to circ's linked list of p_streams.

Also set apconn's cpath_layer to cpath, or to the last hop in circ's cpath if cpath is NULL.

Definition at line 1694 of file circuituse.c.

{
  const node_t *exitnode;

  /* add it into the linked list of streams on this circuit */
  log_debug(LD_APP|LD_CIRC, "attaching new conn to circ. n_circ_id %d.",
            circ->_base.n_circ_id);
  /* reset it, so we can measure circ timeouts */
  ENTRY_TO_CONN(apconn)->timestamp_lastread = time(NULL);
  ENTRY_TO_EDGE_CONN(apconn)->next_stream = circ->p_streams;
  ENTRY_TO_EDGE_CONN(apconn)->on_circuit = TO_CIRCUIT(circ);
  /* assert_connection_ok(conn, time(NULL)); */
  circ->p_streams = ENTRY_TO_EDGE_CONN(apconn);

  if (connection_edge_is_rendezvous_stream(ENTRY_TO_EDGE_CONN(apconn))) {
    /* We are attaching a stream to a rendezvous circuit.  That means
     * that an attempt to connect to a hidden service just
     * succeeded.  Tell rendclient.c. */
    rend_client_note_connection_attempt_ended(
                    ENTRY_TO_EDGE_CONN(apconn)->rend_data->onion_address);
  }

  if (cpath) { /* we were given one; use it */
    tor_assert(cpath_is_on_circuit(circ, cpath));
  } else {
    /* use the last hop in the circuit */
    tor_assert(circ->cpath);
    tor_assert(circ->cpath->prev);
    tor_assert(circ->cpath->prev->state == CPATH_STATE_OPEN);
    cpath = circ->cpath->prev;
  }
  ENTRY_TO_EDGE_CONN(apconn)->cpath_layer = cpath;

  circ->isolation_any_streams_attached = 1;
  connection_edge_update_circuit_isolation(apconn, circ, 0);

  /* See if we can use optimistic data on this circuit */
  if (cpath->extend_info &&
      (exitnode = node_get_by_id(cpath->extend_info->identity_digest)) &&
      exitnode->rs) {
    /* Okay; we know what exit node this is. */
    if (optimistic_data_enabled() &&
        circ->_base.purpose == CIRCUIT_PURPOSE_C_GENERAL &&
        exitnode->rs->version_supports_optimistic_data)
      apconn->may_use_optimistic_data = 1;
    else
      apconn->may_use_optimistic_data = 0;
    log_info(LD_APP, "Looks like completed circuit to %s %s allow "
             "optimistic data for connection to %s",
             safe_str_client(node_describe(exitnode)),
             apconn->may_use_optimistic_data ? "does" : "doesn't",
             safe_str_client(apconn->socks_request->address));
  }
}

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static int optimistic_data_enabled ( void  ) [static]

Return true iff client-side optimistic data is supported.

Definition at line 1676 of file circuituse.c.

{
  const or_options_t *options = get_options();
  if (options->OptimisticData < 0) {
    /* XXX023 consider having auto default to 1 rather than 0 before
     * the 0.2.3 branch goes stable. See bug 3617. -RD */
    const int32_t enabled =
      networkstatus_get_param(NULL, "UseOptimisticData", 0, 0, 1);
    return (int)enabled;
  }
  return options->OptimisticData;
}

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void reset_bandwidth_test ( void  )

Reset have_performed_bandwidth_test, so we'll start building testing circuits again so we can exercise our bandwidth.

Definition at line 1002 of file circuituse.c.

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Variable Documentation

int did_circs_fail_last_period = 0 [static]

Before the last time we called circuit_reset_failure_count(), were there a lot of failures?

Definition at line 1270 of file circuituse.c.

A global list of all circuits at this hop.

Definition at line 34 of file circuitlist.c.

True iff we've ever had enough testing circuits open to test our bandwidth.

Definition at line 997 of file circuituse.c.

int n_circuit_failures = 0 [static]

Number of consecutive failures so far; should only be touched by circuit_launch_new and circuit_*_failure_count.

Definition at line 1267 of file circuituse.c.