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Diffstat (limited to 'src/feature/stats/predict_ports.c')
| -rw-r--r-- | src/feature/stats/predict_ports.c | 311 |
1 files changed, 311 insertions, 0 deletions
diff --git a/src/feature/stats/predict_ports.c b/src/feature/stats/predict_ports.c new file mode 100644 index 0000000000..8abf34f50f --- /dev/null +++ b/src/feature/stats/predict_ports.c @@ -0,0 +1,311 @@ +/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file predict_ports.c + * \brief Remember what ports we've needed so we can have circuits ready. + * + * Predicted ports are used by clients to remember how long it's been + * since they opened an exit connection to each given target + * port. Clients use this information in order to try to keep circuits + * open to exit nodes that can connect to the ports that they care + * about. (The predicted ports mechanism also handles predicted circuit + * usage that _isn't_ port-specific, such as resolves, internal circuits, + * and so on.) + **/ + +#include "core/or/or.h" + +#include "app/config/config.h" +#include "core/or/channelpadding.h" +#include "core/or/circuituse.h" +#include "feature/relay/routermode.h" +#include "feature/relay/selftest.h" +#include "feature/stats/predict_ports.h" +#include "lib/container/bitarray.h" +#include "lib/time/tvdiff.h" + +static size_t predicted_ports_total_alloc = 0; + +static void predicted_ports_alloc(void); + +/** A single predicted port: used to remember which ports we've made + * connections to, so that we can try to keep making circuits that can handle + * those ports. */ +typedef struct predicted_port_t { + /** The port we connected to */ + uint16_t port; + /** The time at which we last used it */ + time_t time; +} predicted_port_t; + +/** A list of port numbers that have been used recently. */ +static smartlist_t *predicted_ports_list=NULL; +/** How long do we keep predicting circuits? */ +static time_t prediction_timeout=0; +/** When was the last time we added a prediction entry (HS or port) */ +static time_t last_prediction_add_time=0; + +/** + * How much time left until we stop predicting circuits? + */ +int +predicted_ports_prediction_time_remaining(time_t now) +{ + time_t seconds_waited; + time_t seconds_left; + + /* Protect against overflow of return value. This can happen if the clock + * jumps backwards in time. Update the last prediction time (aka last + * active time) to prevent it. This update is preferable to using monotonic + * time because it prevents clock jumps into the past from simply causing + * very long idle timeouts while the monotonic time stands still. */ + seconds_waited = time_diff(last_prediction_add_time, now); + if (seconds_waited == TIME_MAX) { + last_prediction_add_time = now; + seconds_waited = 0; + } + + /* Protect against underflow of the return value. This can happen for very + * large periods of inactivity/system sleep. */ + if (seconds_waited > prediction_timeout) + return 0; + + seconds_left = time_diff(seconds_waited, prediction_timeout); + if (BUG(seconds_left == TIME_MAX)) + return INT_MAX; + + return (int)(seconds_left); +} + +/** We just got an application request for a connection with + * port <b>port</b>. Remember it for the future, so we can keep + * some circuits open that will exit to this port. + */ +static void +add_predicted_port(time_t now, uint16_t port) +{ + predicted_port_t *pp = tor_malloc(sizeof(predicted_port_t)); + + // If the list is empty, re-randomize predicted ports lifetime + if (!any_predicted_circuits(now)) { + prediction_timeout = + (time_t)channelpadding_get_circuits_available_timeout(); + } + + last_prediction_add_time = now; + + log_info(LD_CIRC, + "New port prediction added. Will continue predictive circ building " + "for %d more seconds.", + predicted_ports_prediction_time_remaining(now)); + + pp->port = port; + pp->time = now; + predicted_ports_total_alloc += sizeof(*pp); + smartlist_add(predicted_ports_list, pp); +} + +/** Remember that <b>port</b> has been asked for as of time <b>now</b>. + * This is used for predicting what sorts of streams we'll make in the + * future and making exit circuits to anticipate that. + */ +void +rep_hist_note_used_port(time_t now, uint16_t port) +{ + tor_assert(predicted_ports_list); + + if (!port) /* record nothing */ + return; + + SMARTLIST_FOREACH_BEGIN(predicted_ports_list, predicted_port_t *, pp) { + if (pp->port == port) { + pp->time = now; + + last_prediction_add_time = now; + log_info(LD_CIRC, + "New port prediction added. Will continue predictive circ " + "building for %d more seconds.", + predicted_ports_prediction_time_remaining(now)); + return; + } + } SMARTLIST_FOREACH_END(pp); + /* it's not there yet; we need to add it */ + add_predicted_port(now, port); +} + +/** Return a newly allocated pointer to a list of uint16_t * for ports that + * are likely to be asked for in the near future. + */ +smartlist_t * +rep_hist_get_predicted_ports(time_t now) +{ + int predicted_circs_relevance_time; + smartlist_t *out = smartlist_new(); + tor_assert(predicted_ports_list); + + predicted_circs_relevance_time = (int)prediction_timeout; + + /* clean out obsolete entries */ + SMARTLIST_FOREACH_BEGIN(predicted_ports_list, predicted_port_t *, pp) { + if (pp->time + predicted_circs_relevance_time < now) { + log_debug(LD_CIRC, "Expiring predicted port %d", pp->port); + + predicted_ports_total_alloc -= sizeof(predicted_port_t); + tor_free(pp); + SMARTLIST_DEL_CURRENT(predicted_ports_list, pp); + } else { + smartlist_add(out, tor_memdup(&pp->port, sizeof(uint16_t))); + } + } SMARTLIST_FOREACH_END(pp); + return out; +} + +/** + * Take a list of uint16_t *, and remove every port in the list from the + * current list of predicted ports. + */ +void +rep_hist_remove_predicted_ports(const smartlist_t *rmv_ports) +{ + /* Let's do this on O(N), not O(N^2). */ + bitarray_t *remove_ports = bitarray_init_zero(UINT16_MAX); + SMARTLIST_FOREACH(rmv_ports, const uint16_t *, p, + bitarray_set(remove_ports, *p)); + SMARTLIST_FOREACH_BEGIN(predicted_ports_list, predicted_port_t *, pp) { + if (bitarray_is_set(remove_ports, pp->port)) { + tor_free(pp); + predicted_ports_total_alloc -= sizeof(*pp); + SMARTLIST_DEL_CURRENT(predicted_ports_list, pp); + } + } SMARTLIST_FOREACH_END(pp); + bitarray_free(remove_ports); +} + +/** The user asked us to do a resolve. Rather than keeping track of + * timings and such of resolves, we fake it for now by treating + * it the same way as a connection to port 80. This way we will continue + * to have circuits lying around if the user only uses Tor for resolves. + */ +void +rep_hist_note_used_resolve(time_t now) +{ + rep_hist_note_used_port(now, 80); +} + +/** The last time at which we needed an internal circ. */ +static time_t predicted_internal_time = 0; +/** The last time we needed an internal circ with good uptime. */ +static time_t predicted_internal_uptime_time = 0; +/** The last time we needed an internal circ with good capacity. */ +static time_t predicted_internal_capacity_time = 0; + +/** Remember that we used an internal circ at time <b>now</b>. */ +void +rep_hist_note_used_internal(time_t now, int need_uptime, int need_capacity) +{ + // If the list is empty, re-randomize predicted ports lifetime + if (!any_predicted_circuits(now)) { + prediction_timeout = channelpadding_get_circuits_available_timeout(); + } + + last_prediction_add_time = now; + + log_info(LD_CIRC, + "New port prediction added. Will continue predictive circ building " + "for %d more seconds.", + predicted_ports_prediction_time_remaining(now)); + + predicted_internal_time = now; + if (need_uptime) + predicted_internal_uptime_time = now; + if (need_capacity) + predicted_internal_capacity_time = now; +} + +/** Return 1 if we've used an internal circ recently; else return 0. */ +int +rep_hist_get_predicted_internal(time_t now, int *need_uptime, + int *need_capacity) +{ + int predicted_circs_relevance_time; + + predicted_circs_relevance_time = (int)prediction_timeout; + + if (!predicted_internal_time) { /* initialize it */ + predicted_internal_time = now; + predicted_internal_uptime_time = now; + predicted_internal_capacity_time = now; + } + if (predicted_internal_time + predicted_circs_relevance_time < now) + return 0; /* too long ago */ + if (predicted_internal_uptime_time + predicted_circs_relevance_time >= now) + *need_uptime = 1; + // Always predict that we need capacity. + *need_capacity = 1; + return 1; +} + +/** Any ports used lately? These are pre-seeded if we just started + * up or if we're running a hidden service. */ +int +any_predicted_circuits(time_t now) +{ + int predicted_circs_relevance_time; + predicted_circs_relevance_time = (int)prediction_timeout; + + return smartlist_len(predicted_ports_list) || + predicted_internal_time + predicted_circs_relevance_time >= now; +} + +/** Return 1 if we have no need for circuits currently, else return 0. */ +int +rep_hist_circbuilding_dormant(time_t now) +{ + const or_options_t *options = get_options(); + + if (any_predicted_circuits(now)) + return 0; + + /* see if we'll still need to build testing circuits */ + if (server_mode(options) && + (!check_whether_orport_reachable(options) || + !circuit_enough_testing_circs())) + return 0; + if (!check_whether_dirport_reachable(options)) + return 0; + + return 1; +} + +/** + * Allocate whatever memory and structs are needed for predicting + * which ports will be used. Also seed it with port 80, so we'll build + * circuits on start-up. + */ +static void +predicted_ports_alloc(void) +{ + predicted_ports_list = smartlist_new(); +} + +void +predicted_ports_init(void) +{ + predicted_ports_alloc(); + add_predicted_port(time(NULL), 443); // Add a port to get us started +} + +/** Free whatever memory is needed for predicting which ports will + * be used. + */ +void +predicted_ports_free_all(void) +{ + predicted_ports_total_alloc -= + smartlist_len(predicted_ports_list)*sizeof(predicted_port_t); + SMARTLIST_FOREACH(predicted_ports_list, predicted_port_t *, + pp, tor_free(pp)); + smartlist_free(predicted_ports_list); +} |