diff options
Diffstat (limited to 'src/or')
| -rw-r--r-- | src/or/directory.c | 218 | ||||
| -rw-r--r-- | src/or/directory.h | 4 | ||||
| -rw-r--r-- | src/or/main.c | 5 | ||||
| -rw-r--r-- | src/or/networkstatus.c | 34 | ||||
| -rw-r--r-- | src/or/networkstatus.h | 1 |
5 files changed, 260 insertions, 2 deletions
diff --git a/src/or/directory.c b/src/or/directory.c index 0d2a8b2459..63bbdafd3f 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -961,6 +961,12 @@ directory_initiate_command_rend(const tor_addr_t *_addr, return; } + /* ensure we don't make excess connections when we're already downloading + * a consensus during bootstrap */ + if (connection_dir_avoid_extra_connection_for_purpose(dir_purpose)) { + return; + } + conn = dir_connection_new(tor_addr_family(&addr)); /* set up conn so it's got all the data we need to remember */ @@ -1001,6 +1007,9 @@ directory_initiate_command_rend(const tor_addr_t *_addr, conn->base_.state = DIR_CONN_STATE_CLIENT_SENDING; /* fall through */ case 0: + if (connection_dir_close_consensus_conn_if_extra(conn)) { + return; + } /* queue the command on the outbuf */ directory_send_command(conn, dir_purpose, 1, resource, payload, payload_len, @@ -1044,6 +1053,9 @@ directory_initiate_command_rend(const tor_addr_t *_addr, connection_mark_for_close(TO_CONN(conn)); return; } + if (connection_dir_close_consensus_conn_if_extra(conn)) { + return; + } conn->base_.state = DIR_CONN_STATE_CLIENT_SENDING; /* queue the command on the outbuf */ directory_send_command(conn, dir_purpose, 0, resource, @@ -3426,8 +3438,205 @@ connection_dir_finished_flushing(dir_connection_t *conn) return 0; } +/* A helper function for connection_dir_close_consensus_conn_if_extra() + * and connection_dir_close_extra_consensus_conns() that returns 0 if + * we can't have, or don't want to close, excess consensus connections. */ +int +connection_dir_would_close_consensus_conn_helper(void) +{ + const or_options_t *options = get_options(); + + /* we're only interested in closing excess connections if we could + * have created any in the first place */ + if (!networkstatus_consensus_can_use_multiple_directories(options)) { + return 0; + } + + /* We want to close excess connections downloading a consensus. + * If there aren't any excess, we don't have anything to close. */ + if (!networkstatus_consensus_has_excess_connections()) { + return 0; + } + + /* If we have excess connections, but none of them are downloading a + * consensus, and we are still bootstrapping (that is, we have no usable + * consensus), we don't want to close any until one starts downloading. */ + if (!networkstatus_consensus_is_downloading_usable_flavor() + && networkstatus_consensus_is_boostrapping(time(NULL))) { + return 0; + } + + /* If we have just stopped bootstrapping (that is, just parsed a consensus), + * we might still have some excess connections hanging around. So we still + * have to check if we want to close any, even if we've stopped + * bootstrapping. */ + return 1; +} + +/* Check if we would close excess consensus connections. If we would, any + * new consensus connection would become excess immediately, so return 1. + * Otherwise, return 0. */ +int +connection_dir_avoid_extra_connection_for_purpose(unsigned int purpose) +{ + const or_options_t *options = get_options(); + + /* We're not interested in connections that aren't fetching a consensus. */ + if (purpose != DIR_PURPOSE_FETCH_CONSENSUS) { + return 0; + } + + /* we're only interested in avoiding excess connections if we could + * have created any in the first place */ + if (!networkstatus_consensus_can_use_multiple_directories(options)) { + return 0; + } + + /* If there are connections downloading a consensus, and we are still + * bootstrapping (that is, we have no usable consensus), we can be sure that + * any further connections would be excess. */ + if (networkstatus_consensus_is_downloading_usable_flavor() + && networkstatus_consensus_is_boostrapping(time(NULL))) { + return 1; + } + + return 0; +} + +/* Check if we have excess consensus download connection attempts, and close + * conn: + * - if we don't have a consensus, and we're downloading a consensus, and conn + * is not downloading a consensus yet, close it; + * - if we do have a consensus, conn is excess, close it. */ +int +connection_dir_close_consensus_conn_if_extra(dir_connection_t *conn) +{ + tor_assert(conn); + tor_assert(conn->base_.type == CONN_TYPE_DIR); + + /* We're not interested in connections that aren't fetching a consensus. */ + if (conn->base_.purpose != DIR_PURPOSE_FETCH_CONSENSUS) { + return 0; + } + + /* The connection has already been closed */ + if (conn->base_.marked_for_close) { + return 0; + } + + if (!connection_dir_would_close_consensus_conn_helper()) { + return 0; + } + + const int we_are_bootstrapping = networkstatus_consensus_is_boostrapping( + time(NULL)); + + /* We don't want to check other connections to see if they are downloading, + * as this is prone to race-conditions. So leave it for + * connection_dir_consider_close_extra_consensus_conns() to clean up. + * + * But if conn has just started connecting, or we have a consensus already, + * we can be sure it's not needed any more. */ + if (!we_are_bootstrapping + || conn->base_.state == DIR_CONN_STATE_CONNECTING) { + connection_close_immediate(&conn->base_); + connection_mark_for_close(&conn->base_); + return -1; + } + + return 0; +} + +/* Check if we have excess consensus download connection attempts, and close + * them: + * - if we don't have a consensus, and we're downloading a consensus, keep an + * earlier connection, or a connection to a fallback directory, and close + * all other connections; + * - if we do have a consensus, close all connections: they are all excess. */ +void +connection_dir_close_extra_consensus_conns(void) +{ + if (!connection_dir_would_close_consensus_conn_helper()) { + return; + } + + int we_are_bootstrapping = networkstatus_consensus_is_boostrapping( + time(NULL)); + + const char *usable_resource = networkstatus_get_flavor_name( + usable_consensus_flavor()); + smartlist_t *consens_usable_conns = + connection_dir_list_by_purpose_and_resource( + DIR_PURPOSE_FETCH_CONSENSUS, + usable_resource); + + /* If we want to keep a connection that's downloading, find a connection to + * keep, favouring: + * - connections opened earlier (they are likely to have progressed further) + * - connections to fallbacks (to reduce the load on authorities) */ + dir_connection_t *kept_download_conn = NULL; + int kept_is_authority = 0; + if (we_are_bootstrapping) { + SMARTLIST_FOREACH_BEGIN(consens_usable_conns, + dir_connection_t *, d) { + tor_assert(d); + int d_is_authority = router_digest_is_trusted_dir(d->identity_digest); + /* keep the first connection that is past the connecting state, but + * prefer fallbacks. */ + if (d->base_.state != DIR_CONN_STATE_CONNECTING) { + if (!kept_download_conn || (kept_is_authority && !d_is_authority)) { + kept_download_conn = d; + kept_is_authority = d_is_authority; + /* we've found the earliest fallback, and want to keep it regardless + * of any other connections */ + if (!kept_is_authority) + break; + } + } + } SMARTLIST_FOREACH_END(d); + } + + SMARTLIST_FOREACH_BEGIN(consens_usable_conns, + dir_connection_t *, d) { + tor_assert(d); + /* don't close this connection if it's the one we want to keep */ + if (kept_download_conn && d == kept_download_conn) + continue; + /* mark all other connections for close */ + if (!d->base_.marked_for_close) { + connection_close_immediate(&d->base_); + connection_mark_for_close(&d->base_); + } + } SMARTLIST_FOREACH_END(d); + + smartlist_free(consens_usable_conns); + consens_usable_conns = NULL; + + /* make sure we've closed all excess connections */ + const int final_connecting_conn_count = + connection_dir_count_by_purpose_resource_and_state( + DIR_PURPOSE_FETCH_CONSENSUS, + usable_resource, + DIR_CONN_STATE_CONNECTING); + if (final_connecting_conn_count > 0) { + log_warn(LD_BUG, "Expected 0 consensus connections connecting after " + "cleanup, got %d.", final_connecting_conn_count); + } + const int expected_final_conn_count = (we_are_bootstrapping ? 1 : 0); + const int final_conn_count = + connection_dir_count_by_purpose_and_resource( + DIR_PURPOSE_FETCH_CONSENSUS, + usable_resource); + if (final_conn_count > expected_final_conn_count) { + log_warn(LD_BUG, "Expected %d consensus connections after cleanup, got " + "%d.", expected_final_conn_count, final_connecting_conn_count); + } +} + /** Connected handler for directory connections: begin sending data to the - * server */ + * server, and return 0, or, if the connection is an excess bootstrap + * connection, close all excess bootstrap connections. + * Only used when connections don't immediately connect. */ int connection_dir_finished_connecting(dir_connection_t *conn) { @@ -3438,7 +3647,12 @@ connection_dir_finished_connecting(dir_connection_t *conn) log_debug(LD_HTTP,"Dir connection to router %s:%u established.", conn->base_.address,conn->base_.port); - conn->base_.state = DIR_CONN_STATE_CLIENT_SENDING; /* start flushing conn */ + if (connection_dir_close_consensus_conn_if_extra(conn)) { + return -1; + } + + /* start flushing conn */ + conn->base_.state = DIR_CONN_STATE_CLIENT_SENDING; return 0; } diff --git a/src/or/directory.h b/src/or/directory.h index 4255868d3a..37f9ab0815 100644 --- a/src/or/directory.h +++ b/src/or/directory.h @@ -74,6 +74,9 @@ void directory_initiate_command(const tor_addr_t *addr, const char *resource, const char *payload, size_t payload_len, time_t if_modified_since); +int connection_dir_avoid_extra_connection_for_purpose(unsigned int purpose); +int connection_dir_close_consensus_conn_if_extra(dir_connection_t *conn); +void connection_dir_close_extra_consensus_conns(void); #define DSR_HEX (1<<0) #define DSR_BASE64 (1<<1) @@ -139,6 +142,7 @@ STATIC int directory_handle_command_get(dir_connection_t *conn, const char *headers, const char *req_body, size_t req_body_len); +int connection_dir_would_close_consensus_conn_helper(void); STATIC int download_status_schedule_get_delay(download_status_t *dls, const smartlist_t *schedule, time_t now); diff --git a/src/or/main.c b/src/or/main.c index 60957bd6ab..455cba4513 100644 --- a/src/or/main.c +++ b/src/or/main.c @@ -1460,6 +1460,11 @@ run_scheduled_events(time_t now) dirvote_act(options, now); } + /* 2d. Cleanup excess consensus bootstrap connections every second. + * connection_dir_close_consensus_conn_if_extra() will close connections + * that are clearly excess, but this check is more thorough. */ + connection_dir_close_extra_consensus_conns(); + /* 3a. Every second, we examine pending circuits and prune the * ones which have been pending for more than a few seconds. * We do this before step 4, so it can try building more if diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c index 1d5b2f2723..173c109d60 100644 --- a/src/or/networkstatus.c +++ b/src/or/networkstatus.c @@ -1310,6 +1310,40 @@ networkstatus_consensus_can_use_extra_fallbacks(const or_options_t *options) > smartlist_len(router_get_trusted_dir_servers()))); } +/* Check if there is more than 1 consensus connection retrieving the usable + * consensus flavor. If so, return 1, if not, return 0. + * + * During normal operation, Tor only makes one consensus download + * connection. But clients can make multiple simultaneous consensus + * connections to improve bootstrap speed and reliability. + * + * If there is more than one connection, we must have connections left + * over from bootstrapping. However, some of the connections may have + * completed and been cleaned up, so it is not sufficient to check the + * return value of this function to see if a client could make multiple + * bootstrap connections. Use + * networkstatus_consensus_can_use_multiple_directories() + * and networkstatus_consensus_is_boostrapping(). */ +int +networkstatus_consensus_has_excess_connections(void) +{ + const char *usable_resource = networkstatus_get_flavor_name( + usable_consensus_flavor()); + const int consens_conn_usable_count = + connection_dir_count_by_purpose_and_resource( + DIR_PURPOSE_FETCH_CONSENSUS, + usable_resource); + /* The maximum number of connections we want downloading a usable consensus + * Always 1, whether bootstrapping or not. */ + const int max_expected_consens_conn_usable_count = 1; + + if (consens_conn_usable_count > max_expected_consens_conn_usable_count) { + return 1; + } + + return 0; +} + /* Is tor currently downloading a consensus of the usable flavor? */ int networkstatus_consensus_is_downloading_usable_flavor(void) diff --git a/src/or/networkstatus.h b/src/or/networkstatus.h index d44022c80c..4cb33c3fc0 100644 --- a/src/or/networkstatus.h +++ b/src/or/networkstatus.h @@ -75,6 +75,7 @@ int networkstatus_consensus_can_use_multiple_directories( const or_options_t *options); int networkstatus_consensus_can_use_extra_fallbacks( const or_options_t *options); +int networkstatus_consensus_has_excess_connections(void); int networkstatus_consensus_is_downloading_usable_flavor(void); #define NSSET_FROM_CACHE 1 |