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Diffstat (limited to 'src/feature/client/entrynodes.c')
| -rw-r--r-- | src/feature/client/entrynodes.c | 3694 |
1 files changed, 3694 insertions, 0 deletions
diff --git a/src/feature/client/entrynodes.c b/src/feature/client/entrynodes.c new file mode 100644 index 0000000000..ba9c30f8b3 --- /dev/null +++ b/src/feature/client/entrynodes.c @@ -0,0 +1,3694 @@ +/* Copyright (c) 2001 Matej Pfajfar. + * Copyright (c) 2001-2004, Roger Dingledine. + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file entrynodes.c + * \brief Code to manage our fixed first nodes for various functions. + * + * Entry nodes can be guards (for general use) or bridges (for censorship + * circumvention). + * + * In general, we use entry guards to prevent traffic-sampling attacks: + * if we chose every circuit independently, an adversary controlling + * some fraction of paths on the network would observe a sample of every + * user's traffic. Using guards gives users a chance of not being + * profiled. + * + * The current entry guard selection code is designed to try to avoid + * _ever_ trying every guard on the network, to try to stick to guards + * that we've used before, to handle hostile/broken networks, and + * to behave sanely when the network goes up and down. + * + * Our algorithm works as follows: First, we maintain a SAMPLE of guards + * we've seen in the networkstatus consensus. We maintain this sample + * over time, and store it persistently; it is chosen without reference + * to our configuration or firewall rules. Guards remain in the sample + * as they enter and leave the consensus. We expand this sample as + * needed, up to a maximum size. + * + * As a subset of the sample, we maintain a FILTERED SET of the guards + * that we would be willing to use if we could connect to them. The + * filter removes all the guards that we're excluding because they're + * bridges (or not bridges), because we have restrictive firewall rules, + * because of ExcludeNodes, because we of path bias restrictions, + * because they're absent from the network at present, and so on. + * + * As a subset of the filtered set, we keep a REACHABLE FILTERED SET + * (also called a "usable filtered set") of those guards that we call + * "reachable" or "maybe reachable". A guard is reachable if we've + * connected to it more recently than we've failed. A guard is "maybe + * reachable" if we have never tried to connect to it, or if we + * failed to connect to it so long ago that we no longer think our + * failure means it's down. + * + * As a persistent ordered list whose elements are taken from the + * sampled set, we track a CONFIRMED GUARDS LIST. A guard becomes + * confirmed when we successfully build a circuit through it, and decide + * to use that circuit. We order the guards on this list by the order + * in which they became confirmed. + * + * And as a final group, we have an ordered list of PRIMARY GUARDS, + * whose elements are taken from the filtered set. We prefer + * confirmed guards to non-confirmed guards for this list, and place + * other restrictions on it. The primary guards are the ones that we + * connect to "when nothing is wrong" -- circuits through them can be used + * immediately. + * + * To build circuits, we take a primary guard if possible -- or a + * reachable filtered confirmed guard if no primary guard is possible -- + * or a random reachable filtered guard otherwise. If the guard is + * primary, we can use the circuit immediately on success. Otherwise, + * the guard is now "pending" -- we won't use its circuit unless all + * of the circuits we're trying to build through better guards have + * definitely failed. + * + * While we're building circuits, we track a little "guard state" for + * each circuit. We use this to keep track of whether the circuit is + * one that we can use as soon as it's done, or whether it's one that + * we should keep around to see if we can do better. In the latter case, + * a periodic call to entry_guards_upgrade_waiting_circuits() will + * eventually upgrade it. + **/ +/* DOCDOC -- expand this. + * + * Information invariants: + * + * [x] whenever a guard becomes unreachable, clear its usable_filtered flag. + * + * [x] Whenever a guard becomes reachable or maybe-reachable, if its filtered + * flag is set, set its usable_filtered flag. + * + * [x] Whenever we get a new consensus, call update_from_consensus(). (LATER.) + * + * [x] Whenever the configuration changes in a relevant way, update the + * filtered/usable flags. (LATER.) + * + * [x] Whenever we add a guard to the sample, make sure its filtered/usable + * flags are set as possible. + * + * [x] Whenever we remove a guard from the sample, remove it from the primary + * and confirmed lists. + * + * [x] When we make a guard confirmed, update the primary list. + * + * [x] When we make a guard filtered or unfiltered, update the primary list. + * + * [x] When we are about to pick a guard, make sure that the primary list is + * full. + * + * [x] Before calling sample_reachable_filtered_entry_guards(), make sure + * that the filtered, primary, and confirmed flags are up-to-date. + * + * [x] Call entry_guard_consider_retry every time we are about to check + * is_usable_filtered or is_reachable, and every time we set + * is_filtered to 1. + * + * [x] Call entry_guards_changed_for_guard_selection() whenever we update + * a persistent field. + */ + +#define ENTRYNODES_PRIVATE + +#include "or/or.h" +#include "or/channel.h" +#include "or/bridges.h" +#include "or/circpathbias.h" +#include "or/circuitbuild.h" +#include "or/circuitlist.h" +#include "or/circuituse.h" +#include "or/circuitstats.h" +#include "or/config.h" +#include "or/confparse.h" +#include "or/connection.h" +#include "or/control.h" +#include "lib/crypt_ops/crypto_rand.h" +#include "or/directory.h" +#include "or/entrynodes.h" +#include "or/main.h" +#include "or/microdesc.h" +#include "or/networkstatus.h" +#include "or/nodelist.h" +#include "or/policies.h" +#include "or/router.h" +#include "or/routerlist.h" +#include "or/routerparse.h" +#include "or/routerset.h" +#include "or/transports.h" +#include "or/statefile.h" +#include "lib/math/fp.h" +#include "lib/encoding/confline.h" + +#include "or/node_st.h" +#include "or/origin_circuit_st.h" +#include "or/or_state_st.h" + +#include "lib/crypt_ops/digestset.h" + +/** A list of existing guard selection contexts. */ +static smartlist_t *guard_contexts = NULL; +/** The currently enabled guard selection context. */ +static guard_selection_t *curr_guard_context = NULL; + +/** A value of 1 means that at least one context has changed, + * and those changes need to be flushed to disk. */ +static int entry_guards_dirty = 0; + +static void entry_guard_set_filtered_flags(const or_options_t *options, + guard_selection_t *gs, + entry_guard_t *guard); +static void pathbias_check_use_success_count(entry_guard_t *guard); +static void pathbias_check_close_success_count(entry_guard_t *guard); +static int node_is_possible_guard(const node_t *node); +static int node_passes_guard_filter(const or_options_t *options, + const node_t *node); +static entry_guard_t *entry_guard_add_to_sample_impl(guard_selection_t *gs, + const uint8_t *rsa_id_digest, + const char *nickname, + const tor_addr_port_t *bridge_addrport); +static entry_guard_t *get_sampled_guard_by_bridge_addr(guard_selection_t *gs, + const tor_addr_port_t *addrport); +static int entry_guard_obeys_restriction(const entry_guard_t *guard, + const entry_guard_restriction_t *rst); + +/** Return 0 if we should apply guardfraction information found in the + * consensus. A specific consensus can be specified with the + * <b>ns</b> argument, if NULL the most recent one will be picked.*/ +int +should_apply_guardfraction(const networkstatus_t *ns) +{ + /* We need to check the corresponding torrc option and the consensus + * parameter if we need to. */ + const or_options_t *options = get_options(); + + /* If UseGuardFraction is 'auto' then check the same-named consensus + * parameter. If the consensus parameter is not present, default to + * "off". */ + if (options->UseGuardFraction == -1) { + return networkstatus_get_param(ns, "UseGuardFraction", + 0, /* default to "off" */ + 0, 1); + } + + return options->UseGuardFraction; +} + +/** Return true iff we know a preferred descriptor for <b>guard</b> */ +static int +guard_has_descriptor(const entry_guard_t *guard) +{ + const node_t *node = node_get_by_id(guard->identity); + if (!node) + return 0; + return node_has_preferred_descriptor(node, 1); +} + +/** + * Try to determine the correct type for a selection named "name", + * if <b>type</b> is GS_TYPE_INFER. + */ +STATIC guard_selection_type_t +guard_selection_infer_type(guard_selection_type_t type, + const char *name) +{ + if (type == GS_TYPE_INFER) { + if (!strcmp(name, "bridges")) + type = GS_TYPE_BRIDGE; + else if (!strcmp(name, "restricted")) + type = GS_TYPE_RESTRICTED; + else + type = GS_TYPE_NORMAL; + } + return type; +} + +/** + * Allocate and return a new guard_selection_t, with the name <b>name</b>. + */ +STATIC guard_selection_t * +guard_selection_new(const char *name, + guard_selection_type_t type) +{ + guard_selection_t *gs; + + type = guard_selection_infer_type(type, name); + + gs = tor_malloc_zero(sizeof(*gs)); + gs->name = tor_strdup(name); + gs->type = type; + gs->sampled_entry_guards = smartlist_new(); + gs->confirmed_entry_guards = smartlist_new(); + gs->primary_entry_guards = smartlist_new(); + + return gs; +} + +/** + * Return the guard selection called <b>name</b>. If there is none, and + * <b>create_if_absent</b> is true, then create and return it. If there + * is none, and <b>create_if_absent</b> is false, then return NULL. + */ +STATIC guard_selection_t * +get_guard_selection_by_name(const char *name, + guard_selection_type_t type, + int create_if_absent) +{ + if (!guard_contexts) { + guard_contexts = smartlist_new(); + } + SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) { + if (!strcmp(gs->name, name)) + return gs; + } SMARTLIST_FOREACH_END(gs); + + if (! create_if_absent) + return NULL; + + log_debug(LD_GUARD, "Creating a guard selection called %s", name); + guard_selection_t *new_selection = guard_selection_new(name, type); + smartlist_add(guard_contexts, new_selection); + + return new_selection; +} + +/** + * Allocate the first guard context that we're planning to use, + * and make it the current context. + */ +static void +create_initial_guard_context(void) +{ + tor_assert(! curr_guard_context); + if (!guard_contexts) { + guard_contexts = smartlist_new(); + } + guard_selection_type_t type = GS_TYPE_INFER; + const char *name = choose_guard_selection( + get_options(), + networkstatus_get_live_consensus(approx_time()), + NULL, + &type); + tor_assert(name); // "name" can only be NULL if we had an old name. + tor_assert(type != GS_TYPE_INFER); + log_notice(LD_GUARD, "Starting with guard context \"%s\"", name); + curr_guard_context = get_guard_selection_by_name(name, type, 1); +} + +/** Get current default guard_selection_t, creating it if necessary */ +guard_selection_t * +get_guard_selection_info(void) +{ + if (!curr_guard_context) { + create_initial_guard_context(); + } + + return curr_guard_context; +} + +/** Return a statically allocated human-readable description of <b>guard</b> + */ +const char * +entry_guard_describe(const entry_guard_t *guard) +{ + static char buf[256]; + tor_snprintf(buf, sizeof(buf), + "%s ($%s)", + strlen(guard->nickname) ? guard->nickname : "[bridge]", + hex_str(guard->identity, DIGEST_LEN)); + return buf; +} + +/** Return <b>guard</b>'s 20-byte RSA identity digest */ +const char * +entry_guard_get_rsa_id_digest(const entry_guard_t *guard) +{ + return guard->identity; +} + +/** Return the pathbias state associated with <b>guard</b>. */ +guard_pathbias_t * +entry_guard_get_pathbias_state(entry_guard_t *guard) +{ + return &guard->pb; +} + +HANDLE_IMPL(entry_guard, entry_guard_t, ATTR_UNUSED STATIC) + +/** Return an interval betweeen 'now' and 'max_backdate' seconds in the past, + * chosen uniformly at random. We use this before recording persistent + * dates, so that we aren't leaking exactly when we recorded it. + */ +MOCK_IMPL(STATIC time_t, +randomize_time,(time_t now, time_t max_backdate)) +{ + tor_assert(max_backdate > 0); + + time_t earliest = now - max_backdate; + time_t latest = now; + if (earliest <= 0) + earliest = 1; + if (latest <= earliest) + latest = earliest + 1; + + return crypto_rand_time_range(earliest, latest); +} + +/** + * @name parameters for networkstatus algorithm + * + * These parameters are taken from the consensus; some are overrideable in + * the torrc. + */ +/**@{*/ +/** + * We never let our sampled guard set grow larger than this fraction + * of the guards on the network. + */ +STATIC double +get_max_sample_threshold(void) +{ + int32_t pct = + networkstatus_get_param(NULL, "guard-max-sample-threshold-percent", + DFLT_MAX_SAMPLE_THRESHOLD_PERCENT, + 1, 100); + return pct / 100.0; +} +/** + * We never let our sampled guard set grow larger than this number. + */ +STATIC int +get_max_sample_size_absolute(void) +{ + return (int) networkstatus_get_param(NULL, "guard-max-sample-size", + DFLT_MAX_SAMPLE_SIZE, + 1, INT32_MAX); +} +/** + * We always try to make our sample contain at least this many guards. + */ +STATIC int +get_min_filtered_sample_size(void) +{ + return networkstatus_get_param(NULL, "guard-min-filtered-sample-size", + DFLT_MIN_FILTERED_SAMPLE_SIZE, + 1, INT32_MAX); +} +/** + * If a guard is unlisted for this many days in a row, we remove it. + */ +STATIC int +get_remove_unlisted_guards_after_days(void) +{ + return networkstatus_get_param(NULL, + "guard-remove-unlisted-guards-after-days", + DFLT_REMOVE_UNLISTED_GUARDS_AFTER_DAYS, + 1, 365*10); +} +/** + * We remove unconfirmed guards from the sample after this many days, + * regardless of whether they are listed or unlisted. + */ +STATIC int +get_guard_lifetime(void) +{ + if (get_options()->GuardLifetime >= 86400) + return get_options()->GuardLifetime; + int32_t days; + days = networkstatus_get_param(NULL, + "guard-lifetime-days", + DFLT_GUARD_LIFETIME_DAYS, 1, 365*10); + return days * 86400; +} +/** + * We remove confirmed guards from the sample if they were sampled + * GUARD_LIFETIME_DAYS ago and confirmed this many days ago. + */ +STATIC int +get_guard_confirmed_min_lifetime(void) +{ + if (get_options()->GuardLifetime >= 86400) + return get_options()->GuardLifetime; + int32_t days; + days = networkstatus_get_param(NULL, "guard-confirmed-min-lifetime-days", + DFLT_GUARD_CONFIRMED_MIN_LIFETIME_DAYS, + 1, 365*10); + return days * 86400; +} +/** + * How many guards do we try to keep on our primary guard list? + */ +STATIC int +get_n_primary_guards(void) +{ + /* If the user has explicitly configured the number of primary guards, do + * what the user wishes to do */ + const int configured_primaries = get_options()->NumPrimaryGuards; + if (configured_primaries) { + return configured_primaries; + } + + /* otherwise check for consensus parameter and if that's not set either, just + * use the default value. */ + return networkstatus_get_param(NULL, + "guard-n-primary-guards", + DFLT_N_PRIMARY_GUARDS, 1, INT32_MAX); +} +/** + * Return the number of the live primary guards we should look at when + * making a circuit. + */ +STATIC int +get_n_primary_guards_to_use(guard_usage_t usage) +{ + int configured; + const char *param_name; + int param_default; + + /* If the user has explicitly configured the amount of guards, use + that. Otherwise, fall back to the default value. */ + if (usage == GUARD_USAGE_DIRGUARD) { + configured = get_options()->NumDirectoryGuards; + param_name = "guard-n-primary-dir-guards-to-use"; + param_default = DFLT_N_PRIMARY_DIR_GUARDS_TO_USE; + } else { + configured = get_options()->NumEntryGuards; + param_name = "guard-n-primary-guards-to-use"; + param_default = DFLT_N_PRIMARY_GUARDS_TO_USE; + } + if (configured >= 1) { + return configured; + } + return networkstatus_get_param(NULL, + param_name, param_default, 1, INT32_MAX); +} +/** + * If we haven't successfully built or used a circuit in this long, then + * consider that the internet is probably down. + */ +STATIC int +get_internet_likely_down_interval(void) +{ + return networkstatus_get_param(NULL, "guard-internet-likely-down-interval", + DFLT_INTERNET_LIKELY_DOWN_INTERVAL, + 1, INT32_MAX); +} +/** + * If we're trying to connect to a nonprimary guard for at least this + * many seconds, and we haven't gotten the connection to work, we will treat + * lower-priority guards as usable. + */ +STATIC int +get_nonprimary_guard_connect_timeout(void) +{ + return networkstatus_get_param(NULL, + "guard-nonprimary-guard-connect-timeout", + DFLT_NONPRIMARY_GUARD_CONNECT_TIMEOUT, + 1, INT32_MAX); +} +/** + * If a circuit has been sitting around in 'waiting for better guard' state + * for at least this long, we'll expire it. + */ +STATIC int +get_nonprimary_guard_idle_timeout(void) +{ + return networkstatus_get_param(NULL, + "guard-nonprimary-guard-idle-timeout", + DFLT_NONPRIMARY_GUARD_IDLE_TIMEOUT, + 1, INT32_MAX); +} +/** + * If our configuration retains fewer than this fraction of guards from the + * torrc, we are in a restricted setting. + */ +STATIC double +get_meaningful_restriction_threshold(void) +{ + int32_t pct = networkstatus_get_param(NULL, + "guard-meaningful-restriction-percent", + DFLT_MEANINGFUL_RESTRICTION_PERCENT, + 1, INT32_MAX); + return pct / 100.0; +} +/** + * If our configuration retains fewer than this fraction of guards from the + * torrc, we are in an extremely restricted setting, and should warn. + */ +STATIC double +get_extreme_restriction_threshold(void) +{ + int32_t pct = networkstatus_get_param(NULL, + "guard-extreme-restriction-percent", + DFLT_EXTREME_RESTRICTION_PERCENT, + 1, INT32_MAX); + return pct / 100.0; +} + +/* Mark <b>guard</b> as maybe reachable again. */ +static void +mark_guard_maybe_reachable(entry_guard_t *guard) +{ + if (guard->is_reachable != GUARD_REACHABLE_NO) { + return; + } + + /* Note that we do not clear failing_since: this guard is now only + * _maybe-reachable_. */ + guard->is_reachable = GUARD_REACHABLE_MAYBE; + if (guard->is_filtered_guard) + guard->is_usable_filtered_guard = 1; +} + +/** + * Called when the network comes up after having seemed to be down for + * a while: Mark the primary guards as maybe-reachable so that we'll + * try them again. + */ +STATIC void +mark_primary_guards_maybe_reachable(guard_selection_t *gs) +{ + tor_assert(gs); + + if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); + + SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { + mark_guard_maybe_reachable(guard); + } SMARTLIST_FOREACH_END(guard); +} + +/* Called when we exhaust all guards in our sampled set: Marks all guards as + maybe-reachable so that we 'll try them again. */ +static void +mark_all_guards_maybe_reachable(guard_selection_t *gs) +{ + tor_assert(gs); + + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + mark_guard_maybe_reachable(guard); + } SMARTLIST_FOREACH_END(guard); +} + +/**@}*/ + +/** + * Given our options and our list of nodes, return the name of the + * guard selection that we should use. Return NULL for "use the + * same selection you were using before. + */ +STATIC const char * +choose_guard_selection(const or_options_t *options, + const networkstatus_t *live_ns, + const guard_selection_t *old_selection, + guard_selection_type_t *type_out) +{ + tor_assert(options); + tor_assert(type_out); + + if (options->UseBridges) { + *type_out = GS_TYPE_BRIDGE; + return "bridges"; + } + + if (! live_ns) { + /* without a networkstatus, we can't tell any more than that. */ + *type_out = GS_TYPE_NORMAL; + return "default"; + } + + const smartlist_t *nodes = nodelist_get_list(); + int n_guards = 0, n_passing_filter = 0; + SMARTLIST_FOREACH_BEGIN(nodes, const node_t *, node) { + if (node_is_possible_guard(node)) { + ++n_guards; + if (node_passes_guard_filter(options, node)) { + ++n_passing_filter; + } + } + } SMARTLIST_FOREACH_END(node); + + /* We use separate 'high' and 'low' thresholds here to prevent flapping + * back and forth */ + const int meaningful_threshold_high = + (int)(n_guards * get_meaningful_restriction_threshold() * 1.05); + const int meaningful_threshold_mid = + (int)(n_guards * get_meaningful_restriction_threshold()); + const int meaningful_threshold_low = + (int)(n_guards * get_meaningful_restriction_threshold() * .95); + const int extreme_threshold = + (int)(n_guards * get_extreme_restriction_threshold()); + + /* + If we have no previous selection, then we're "restricted" iff we are + below the meaningful restriction threshold. That's easy enough. + + But if we _do_ have a previous selection, we make it a little + "sticky": we only move from "restricted" to "default" when we find + that we're above the threshold plus 5%, and we only move from + "default" to "restricted" when we're below the threshold minus 5%. + That should prevent us from flapping back and forth if we happen to + be hovering very close to the default. + + The extreme threshold is for warning only. + */ + + static int have_warned_extreme_threshold = 0; + if (n_guards && + n_passing_filter < extreme_threshold && + ! have_warned_extreme_threshold) { + have_warned_extreme_threshold = 1; + const double exclude_frac = + (n_guards - n_passing_filter) / (double)n_guards; + log_warn(LD_GUARD, "Your configuration excludes %d%% of all possible " + "guards. That's likely to make you stand out from the " + "rest of the world.", (int)(exclude_frac * 100)); + } + + /* Easy case: no previous selection. Just check if we are in restricted or + normal guard selection. */ + if (old_selection == NULL) { + if (n_passing_filter >= meaningful_threshold_mid) { + *type_out = GS_TYPE_NORMAL; + return "default"; + } else { + *type_out = GS_TYPE_RESTRICTED; + return "restricted"; + } + } + + /* Trickier case: we do have a previous guard selection context. */ + tor_assert(old_selection); + + /* Use high and low thresholds to decide guard selection, and if we fall in + the middle then keep the current guard selection context. */ + if (n_passing_filter >= meaningful_threshold_high) { + *type_out = GS_TYPE_NORMAL; + return "default"; + } else if (n_passing_filter < meaningful_threshold_low) { + *type_out = GS_TYPE_RESTRICTED; + return "restricted"; + } else { + /* we are in the middle: maintain previous guard selection */ + *type_out = old_selection->type; + return old_selection->name; + } +} + +/** + * Check whether we should switch from our current guard selection to a + * different one. If so, switch and return 1. Return 0 otherwise. + * + * On a 1 return, the caller should mark all currently live circuits unusable + * for new streams, by calling circuit_mark_all_unused_circs() and + * circuit_mark_all_dirty_circs_as_unusable(). + */ +int +update_guard_selection_choice(const or_options_t *options) +{ + if (!curr_guard_context) { + create_initial_guard_context(); + return 1; + } + + guard_selection_type_t type = GS_TYPE_INFER; + const char *new_name = choose_guard_selection( + options, + networkstatus_get_live_consensus(approx_time()), + curr_guard_context, + &type); + tor_assert(new_name); + tor_assert(type != GS_TYPE_INFER); + + const char *cur_name = curr_guard_context->name; + if (! strcmp(cur_name, new_name)) { + log_debug(LD_GUARD, + "Staying with guard context \"%s\" (no change)", new_name); + return 0; // No change + } + + log_notice(LD_GUARD, "Switching to guard context \"%s\" (was using \"%s\")", + new_name, cur_name); + guard_selection_t *new_guard_context; + new_guard_context = get_guard_selection_by_name(new_name, type, 1); + tor_assert(new_guard_context); + tor_assert(new_guard_context != curr_guard_context); + curr_guard_context = new_guard_context; + + return 1; +} + +/** + * Return true iff <b>node</b> has all the flags needed for us to consider it + * a possible guard when sampling guards. + */ +static int +node_is_possible_guard(const node_t *node) +{ + /* The "GUARDS" set is all nodes in the nodelist for which this predicate + * holds. */ + + tor_assert(node); + return (node->is_possible_guard && + node->is_stable && + node->is_fast && + node->is_valid && + node_is_dir(node) && + !router_digest_is_me(node->identity)); +} + +/** + * Return the sampled guard with the RSA identity digest <b>rsa_id</b>, or + * NULL if we don't have one. */ +STATIC entry_guard_t * +get_sampled_guard_with_id(guard_selection_t *gs, + const uint8_t *rsa_id) +{ + tor_assert(gs); + tor_assert(rsa_id); + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + if (tor_memeq(guard->identity, rsa_id, DIGEST_LEN)) + return guard; + } SMARTLIST_FOREACH_END(guard); + return NULL; +} + +/** If <b>gs</b> contains a sampled entry guard matching <b>bridge</b>, + * return that guard. Otherwise return NULL. */ +static entry_guard_t * +get_sampled_guard_for_bridge(guard_selection_t *gs, + const bridge_info_t *bridge) +{ + const uint8_t *id = bridge_get_rsa_id_digest(bridge); + const tor_addr_port_t *addrport = bridge_get_addr_port(bridge); + entry_guard_t *guard; + if (BUG(!addrport)) + return NULL; // LCOV_EXCL_LINE + guard = get_sampled_guard_by_bridge_addr(gs, addrport); + if (! guard || (id && tor_memneq(id, guard->identity, DIGEST_LEN))) + return NULL; + else + return guard; +} + +/** If we know a bridge_info_t matching <b>guard</b>, return that + * bridge. Otherwise return NULL. */ +static bridge_info_t * +get_bridge_info_for_guard(const entry_guard_t *guard) +{ + const uint8_t *identity = NULL; + if (! tor_digest_is_zero(guard->identity)) { + identity = (const uint8_t *)guard->identity; + } + if (BUG(guard->bridge_addr == NULL)) + return NULL; + + return get_configured_bridge_by_exact_addr_port_digest( + &guard->bridge_addr->addr, + guard->bridge_addr->port, + (const char*)identity); +} + +/** + * Return true iff we have a sampled guard with the RSA identity digest + * <b>rsa_id</b>. */ +static inline int +have_sampled_guard_with_id(guard_selection_t *gs, const uint8_t *rsa_id) +{ + return get_sampled_guard_with_id(gs, rsa_id) != NULL; +} + +/** + * Allocate a new entry_guard_t object for <b>node</b>, add it to the + * sampled entry guards in <b>gs</b>, and return it. <b>node</b> must + * not currently be a sampled guard in <b>gs</b>. + */ +STATIC entry_guard_t * +entry_guard_add_to_sample(guard_selection_t *gs, + const node_t *node) +{ + log_info(LD_GUARD, "Adding %s to the entry guard sample set.", + node_describe(node)); + + /* make sure that the guard is not already sampled. */ + if (BUG(have_sampled_guard_with_id(gs, (const uint8_t*)node->identity))) + return NULL; // LCOV_EXCL_LINE + + return entry_guard_add_to_sample_impl(gs, + (const uint8_t*)node->identity, + node_get_nickname(node), + NULL); +} + +/** + * Backend: adds a new sampled guard to <b>gs</b>, with given identity, + * nickname, and ORPort. rsa_id_digest and bridge_addrport are optional, but + * we need one of them. nickname is optional. The caller is responsible for + * maintaining the size limit of the SAMPLED_GUARDS set. + */ +static entry_guard_t * +entry_guard_add_to_sample_impl(guard_selection_t *gs, + const uint8_t *rsa_id_digest, + const char *nickname, + const tor_addr_port_t *bridge_addrport) +{ + const int GUARD_LIFETIME = get_guard_lifetime(); + tor_assert(gs); + + // XXXX #20827 take ed25519 identity here too. + + /* Make sure we can actually identify the guard. */ + if (BUG(!rsa_id_digest && !bridge_addrport)) + return NULL; // LCOV_EXCL_LINE + + entry_guard_t *guard = tor_malloc_zero(sizeof(entry_guard_t)); + + /* persistent fields */ + guard->is_persistent = (rsa_id_digest != NULL); + guard->selection_name = tor_strdup(gs->name); + if (rsa_id_digest) + memcpy(guard->identity, rsa_id_digest, DIGEST_LEN); + if (nickname) + strlcpy(guard->nickname, nickname, sizeof(guard->nickname)); + guard->sampled_on_date = randomize_time(approx_time(), GUARD_LIFETIME/10); + tor_free(guard->sampled_by_version); + guard->sampled_by_version = tor_strdup(VERSION); + guard->currently_listed = 1; + guard->confirmed_idx = -1; + + /* non-persistent fields */ + guard->is_reachable = GUARD_REACHABLE_MAYBE; + if (bridge_addrport) + guard->bridge_addr = tor_memdup(bridge_addrport, sizeof(*bridge_addrport)); + + smartlist_add(gs->sampled_entry_guards, guard); + guard->in_selection = gs; + entry_guard_set_filtered_flags(get_options(), gs, guard); + entry_guards_changed_for_guard_selection(gs); + return guard; +} + +/** + * Add an entry guard to the "bridges" guard selection sample, with + * information taken from <b>bridge</b>. Return that entry guard. + */ +static entry_guard_t * +entry_guard_add_bridge_to_sample(guard_selection_t *gs, + const bridge_info_t *bridge) +{ + const uint8_t *id_digest = bridge_get_rsa_id_digest(bridge); + const tor_addr_port_t *addrport = bridge_get_addr_port(bridge); + + tor_assert(addrport); + + /* make sure that the guard is not already sampled. */ + if (BUG(get_sampled_guard_for_bridge(gs, bridge))) + return NULL; // LCOV_EXCL_LINE + + return entry_guard_add_to_sample_impl(gs, id_digest, NULL, addrport); +} + +/** + * Return the entry_guard_t in <b>gs</b> whose address is <b>addrport</b>, + * or NULL if none exists. +*/ +static entry_guard_t * +get_sampled_guard_by_bridge_addr(guard_selection_t *gs, + const tor_addr_port_t *addrport) +{ + if (! gs) + return NULL; + if (BUG(!addrport)) + return NULL; + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, g) { + if (g->bridge_addr && tor_addr_port_eq(addrport, g->bridge_addr)) + return g; + } SMARTLIST_FOREACH_END(g); + return NULL; +} + +/** Update the guard subsystem's knowledge of the identity of the bridge + * at <b>addrport</b>. Idempotent. + */ +void +entry_guard_learned_bridge_identity(const tor_addr_port_t *addrport, + const uint8_t *rsa_id_digest) +{ + guard_selection_t *gs = get_guard_selection_by_name("bridges", + GS_TYPE_BRIDGE, + 0); + if (!gs) + return; + + entry_guard_t *g = get_sampled_guard_by_bridge_addr(gs, addrport); + if (!g) + return; + + int make_persistent = 0; + + if (tor_digest_is_zero(g->identity)) { + memcpy(g->identity, rsa_id_digest, DIGEST_LEN); + make_persistent = 1; + } else if (tor_memeq(g->identity, rsa_id_digest, DIGEST_LEN)) { + /* Nothing to see here; we learned something we already knew. */ + if (BUG(! g->is_persistent)) + make_persistent = 1; + } else { + char old_id[HEX_DIGEST_LEN+1]; + base16_encode(old_id, sizeof(old_id), g->identity, sizeof(g->identity)); + log_warn(LD_BUG, "We 'learned' an identity %s for a bridge at %s:%d, but " + "we already knew a different one (%s). Ignoring the new info as " + "possibly bogus.", + hex_str((const char *)rsa_id_digest, DIGEST_LEN), + fmt_and_decorate_addr(&addrport->addr), addrport->port, + old_id); + return; // redundant, but let's be clear: we're not making this persistent. + } + + if (make_persistent) { + g->is_persistent = 1; + entry_guards_changed_for_guard_selection(gs); + } +} + +/** + * Return the number of sampled guards in <b>gs</b> that are "filtered" + * (that is, we're willing to connect to them) and that are "usable" + * (that is, either "reachable" or "maybe reachable"). + * + * If a restriction is provided in <b>rst</b>, do not count any guards that + * violate it. + */ +STATIC int +num_reachable_filtered_guards(const guard_selection_t *gs, + const entry_guard_restriction_t *rst) +{ + int n_reachable_filtered_guards = 0; + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + entry_guard_consider_retry(guard); + if (! entry_guard_obeys_restriction(guard, rst)) + continue; + if (guard->is_usable_filtered_guard) + ++n_reachable_filtered_guards; + } SMARTLIST_FOREACH_END(guard); + return n_reachable_filtered_guards; +} + +/** Return the actual maximum size for the sample in <b>gs</b>, + * given that we know about <b>n_guards</b> total. */ +static int +get_max_sample_size(guard_selection_t *gs, + int n_guards) +{ + const int using_bridges = (gs->type == GS_TYPE_BRIDGE); + const int min_sample = get_min_filtered_sample_size(); + + /* If we are in bridge mode, expand our sample set as needed without worrying + * about max size. We should respect the user's wishes to use many bridges if + * that's what they have specified in their configuration file. */ + if (using_bridges) + return INT_MAX; + + const int max_sample_by_pct = (int)(n_guards * get_max_sample_threshold()); + const int max_sample_absolute = get_max_sample_size_absolute(); + const int max_sample = MIN(max_sample_by_pct, max_sample_absolute); + if (max_sample < min_sample) + return min_sample; + else + return max_sample; +} + +/** + * Return a smartlist of the all the guards that are not currently + * members of the sample (GUARDS - SAMPLED_GUARDS). The elements of + * this list are node_t pointers in the non-bridge case, and + * bridge_info_t pointers in the bridge case. Set *<b>n_guards_out/b> + * to the number of guards that we found in GUARDS, including those + * that were already sampled. + */ +static smartlist_t * +get_eligible_guards(const or_options_t *options, + guard_selection_t *gs, + int *n_guards_out) +{ + /* Construct eligible_guards as GUARDS - SAMPLED_GUARDS */ + smartlist_t *eligible_guards = smartlist_new(); + int n_guards = 0; // total size of "GUARDS" + + if (gs->type == GS_TYPE_BRIDGE) { + const smartlist_t *bridges = bridge_list_get(); + SMARTLIST_FOREACH_BEGIN(bridges, bridge_info_t *, bridge) { + ++n_guards; + if (NULL != get_sampled_guard_for_bridge(gs, bridge)) { + continue; + } + smartlist_add(eligible_guards, bridge); + } SMARTLIST_FOREACH_END(bridge); + } else { + const smartlist_t *nodes = nodelist_get_list(); + const int n_sampled = smartlist_len(gs->sampled_entry_guards); + + /* Build a bloom filter of our current guards: let's keep this O(N). */ + digestset_t *sampled_guard_ids = digestset_new(n_sampled); + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, const entry_guard_t *, + guard) { + digestset_add(sampled_guard_ids, guard->identity); + } SMARTLIST_FOREACH_END(guard); + + SMARTLIST_FOREACH_BEGIN(nodes, const node_t *, node) { + if (! node_is_possible_guard(node)) + continue; + if (gs->type == GS_TYPE_RESTRICTED) { + /* In restricted mode, we apply the filter BEFORE sampling, so + * that we are sampling from the nodes that we might actually + * select. If we sampled first, we might wind up with a sample + * that didn't include any EntryNodes at all. */ + if (! node_passes_guard_filter(options, node)) + continue; + } + ++n_guards; + if (digestset_probably_contains(sampled_guard_ids, node->identity)) + continue; + smartlist_add(eligible_guards, (node_t*)node); + } SMARTLIST_FOREACH_END(node); + + /* Now we can free that bloom filter. */ + digestset_free(sampled_guard_ids); + } + + *n_guards_out = n_guards; + return eligible_guards; +} + +/** Helper: given a smartlist of either bridge_info_t (if gs->type is + * GS_TYPE_BRIDGE) or node_t (otherwise), pick one that can be a guard, + * add it as a guard, remove it from the list, and return a new + * entry_guard_t. Return NULL on failure. */ +static entry_guard_t * +select_and_add_guard_item_for_sample(guard_selection_t *gs, + smartlist_t *eligible_guards) +{ + entry_guard_t *added_guard; + if (gs->type == GS_TYPE_BRIDGE) { + const bridge_info_t *bridge = smartlist_choose(eligible_guards); + if (BUG(!bridge)) + return NULL; // LCOV_EXCL_LINE + smartlist_remove(eligible_guards, bridge); + added_guard = entry_guard_add_bridge_to_sample(gs, bridge); + } else { + const node_t *node = + node_sl_choose_by_bandwidth(eligible_guards, WEIGHT_FOR_GUARD); + if (BUG(!node)) + return NULL; // LCOV_EXCL_LINE + smartlist_remove(eligible_guards, node); + added_guard = entry_guard_add_to_sample(gs, node); + } + + return added_guard; +} + +/** + * Return true iff we need a consensus to update our guards, but we don't + * have one. (We can return 0 here either if the consensus is _not_ missing, + * or if we don't need a consensus because we're using bridges.) + */ +static int +live_consensus_is_missing(const guard_selection_t *gs) +{ + tor_assert(gs); + if (gs->type == GS_TYPE_BRIDGE) { + /* We don't update bridges from the consensus; they aren't there. */ + return 0; + } + return networkstatus_get_live_consensus(approx_time()) == NULL; +} + +/** + * Add new guards to the sampled guards in <b>gs</b> until there are + * enough usable filtered guards, but never grow the sample beyond its + * maximum size. Return the last guard added, or NULL if none were + * added. + */ +STATIC entry_guard_t * +entry_guards_expand_sample(guard_selection_t *gs) +{ + tor_assert(gs); + const or_options_t *options = get_options(); + + if (live_consensus_is_missing(gs)) { + log_info(LD_GUARD, "Not expanding the sample guard set; we have " + "no live consensus."); + return NULL; + } + + int n_sampled = smartlist_len(gs->sampled_entry_guards); + entry_guard_t *added_guard = NULL; + int n_usable_filtered_guards = num_reachable_filtered_guards(gs, NULL); + int n_guards = 0; + smartlist_t *eligible_guards = get_eligible_guards(options, gs, &n_guards); + + const int max_sample = get_max_sample_size(gs, n_guards); + const int min_filtered_sample = get_min_filtered_sample_size(); + + log_info(LD_GUARD, "Expanding the sample guard set. We have %d guards " + "in the sample, and %d eligible guards to extend it with.", + n_sampled, smartlist_len(eligible_guards)); + + while (n_usable_filtered_guards < min_filtered_sample) { + /* Has our sample grown too large to expand? */ + if (n_sampled >= max_sample) { + log_info(LD_GUARD, "Not expanding the guard sample any further; " + "just hit the maximum sample threshold of %d", + max_sample); + goto done; + } + + /* Did we run out of guards? */ + if (smartlist_len(eligible_guards) == 0) { + /* LCOV_EXCL_START + As long as MAX_SAMPLE_THRESHOLD makes can't be adjusted to + allow all guards to be sampled, this can't be reached. + */ + log_info(LD_GUARD, "Not expanding the guard sample any further; " + "just ran out of eligible guards"); + goto done; + /* LCOV_EXCL_STOP */ + } + + /* Otherwise we can add at least one new guard. */ + added_guard = select_and_add_guard_item_for_sample(gs, eligible_guards); + if (!added_guard) + goto done; // LCOV_EXCL_LINE -- only fails on BUG. + + ++n_sampled; + + if (added_guard->is_usable_filtered_guard) + ++n_usable_filtered_guards; + } + + done: + smartlist_free(eligible_guards); + return added_guard; +} + +/** + * Helper: <b>guard</b> has just been removed from the sampled guards: + * also remove it from primary and confirmed. */ +static void +remove_guard_from_confirmed_and_primary_lists(guard_selection_t *gs, + entry_guard_t *guard) +{ + if (guard->is_primary) { + guard->is_primary = 0; + smartlist_remove_keeporder(gs->primary_entry_guards, guard); + } else { + if (BUG(smartlist_contains(gs->primary_entry_guards, guard))) { + smartlist_remove_keeporder(gs->primary_entry_guards, guard); + } + } + + if (guard->confirmed_idx >= 0) { + smartlist_remove_keeporder(gs->confirmed_entry_guards, guard); + guard->confirmed_idx = -1; + guard->confirmed_on_date = 0; + } else { + if (BUG(smartlist_contains(gs->confirmed_entry_guards, guard))) { + // LCOV_EXCL_START + smartlist_remove_keeporder(gs->confirmed_entry_guards, guard); + // LCOV_EXCL_STOP + } + } +} + +/** Return true iff <b>guard</b> is currently "listed" -- that is, it + * appears in the consensus, or as a configured bridge (as + * appropriate) */ +MOCK_IMPL(STATIC int, +entry_guard_is_listed,(guard_selection_t *gs, const entry_guard_t *guard)) +{ + if (gs->type == GS_TYPE_BRIDGE) { + return NULL != get_bridge_info_for_guard(guard); + } else { + const node_t *node = node_get_by_id(guard->identity); + + return node && node_is_possible_guard(node); + } +} + +/** + * Update the status of all sampled guards based on the arrival of a + * new consensus networkstatus document. This will include marking + * some guards as listed or unlisted, and removing expired guards. */ +STATIC void +sampled_guards_update_from_consensus(guard_selection_t *gs) +{ + tor_assert(gs); + const int REMOVE_UNLISTED_GUARDS_AFTER = + (get_remove_unlisted_guards_after_days() * 86400); + const int unlisted_since_slop = REMOVE_UNLISTED_GUARDS_AFTER / 5; + + // It's important to use only a live consensus here; we don't want to + // make changes based on anything expired or old. + if (live_consensus_is_missing(gs)) { + log_info(LD_GUARD, "Not updating the sample guard set; we have " + "no live consensus."); + return; + } + log_info(LD_GUARD, "Updating sampled guard status based on received " + "consensus."); + + int n_changes = 0; + + /* First: Update listed/unlisted. */ + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + /* XXXX #20827 check ed ID too */ + const int is_listed = entry_guard_is_listed(gs, guard); + + if (is_listed && ! guard->currently_listed) { + ++n_changes; + guard->currently_listed = 1; + guard->unlisted_since_date = 0; + log_info(LD_GUARD, "Sampled guard %s is now listed again.", + entry_guard_describe(guard)); + } else if (!is_listed && guard->currently_listed) { + ++n_changes; + guard->currently_listed = 0; + guard->unlisted_since_date = randomize_time(approx_time(), + unlisted_since_slop); + log_info(LD_GUARD, "Sampled guard %s is now unlisted.", + entry_guard_describe(guard)); + } else if (is_listed && guard->currently_listed) { + log_debug(LD_GUARD, "Sampled guard %s is still listed.", + entry_guard_describe(guard)); + } else { + tor_assert(! is_listed && ! guard->currently_listed); + log_debug(LD_GUARD, "Sampled guard %s is still unlisted.", + entry_guard_describe(guard)); + } + + /* Clean up unlisted_since_date, just in case. */ + if (guard->currently_listed && guard->unlisted_since_date) { + ++n_changes; + guard->unlisted_since_date = 0; + log_warn(LD_BUG, "Sampled guard %s was listed, but with " + "unlisted_since_date set. Fixing.", + entry_guard_describe(guard)); + } else if (!guard->currently_listed && ! guard->unlisted_since_date) { + ++n_changes; + guard->unlisted_since_date = randomize_time(approx_time(), + unlisted_since_slop); + log_warn(LD_BUG, "Sampled guard %s was unlisted, but with " + "unlisted_since_date unset. Fixing.", + entry_guard_describe(guard)); + } + } SMARTLIST_FOREACH_END(guard); + + const time_t remove_if_unlisted_since = + approx_time() - REMOVE_UNLISTED_GUARDS_AFTER; + const time_t maybe_remove_if_sampled_before = + approx_time() - get_guard_lifetime(); + const time_t remove_if_confirmed_before = + approx_time() - get_guard_confirmed_min_lifetime(); + + /* Then: remove the ones that have been junk for too long */ + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + int rmv = 0; + + if (guard->currently_listed == 0 && + guard->unlisted_since_date < remove_if_unlisted_since) { + /* + "We have a live consensus, and {IS_LISTED} is false, and + {FIRST_UNLISTED_AT} is over {REMOVE_UNLISTED_GUARDS_AFTER} + days in the past." + */ + log_info(LD_GUARD, "Removing sampled guard %s: it has been unlisted " + "for over %d days", entry_guard_describe(guard), + get_remove_unlisted_guards_after_days()); + rmv = 1; + } else if (guard->sampled_on_date < maybe_remove_if_sampled_before) { + /* We have a live consensus, and {ADDED_ON_DATE} is over + {GUARD_LIFETIME} ago, *and* {CONFIRMED_ON_DATE} is either + "never", or over {GUARD_CONFIRMED_MIN_LIFETIME} ago. + */ + if (guard->confirmed_on_date == 0) { + rmv = 1; + log_info(LD_GUARD, "Removing sampled guard %s: it was sampled " + "over %d days ago, but never confirmed.", + entry_guard_describe(guard), + get_guard_lifetime() / 86400); + } else if (guard->confirmed_on_date < remove_if_confirmed_before) { + rmv = 1; + log_info(LD_GUARD, "Removing sampled guard %s: it was sampled " + "over %d days ago, and confirmed over %d days ago.", + entry_guard_describe(guard), + get_guard_lifetime() / 86400, + get_guard_confirmed_min_lifetime() / 86400); + } + } + + if (rmv) { + ++n_changes; + SMARTLIST_DEL_CURRENT(gs->sampled_entry_guards, guard); + remove_guard_from_confirmed_and_primary_lists(gs, guard); + entry_guard_free(guard); + } + } SMARTLIST_FOREACH_END(guard); + + if (n_changes) { + gs->primary_guards_up_to_date = 0; + entry_guards_update_filtered_sets(gs); + /* We don't need to rebuild the confirmed list right here -- we may have + * removed confirmed guards above, but we can't have added any new + * confirmed guards. + */ + entry_guards_changed_for_guard_selection(gs); + } +} + +/** + * Return true iff <b>node</b> is a Tor relay that we are configured to + * be able to connect to. */ +static int +node_passes_guard_filter(const or_options_t *options, + const node_t *node) +{ + /* NOTE: Make sure that this function stays in sync with + * options_transition_affects_entry_guards */ + if (routerset_contains_node(options->ExcludeNodes, node)) + return 0; + + if (options->EntryNodes && + !routerset_contains_node(options->EntryNodes, node)) + return 0; + + if (!fascist_firewall_allows_node(node, FIREWALL_OR_CONNECTION, 0)) + return 0; + + if (node_is_a_configured_bridge(node)) + return 0; + + return 1; +} + +/** Helper: Return true iff <b>bridge</b> passes our configuration + * filter-- if it is a relay that we are configured to be able to + * connect to. */ +static int +bridge_passes_guard_filter(const or_options_t *options, + const bridge_info_t *bridge) +{ + tor_assert(bridge); + if (!bridge) + return 0; + + if (routerset_contains_bridge(options->ExcludeNodes, bridge)) + return 0; + + /* Ignore entrynodes */ + const tor_addr_port_t *addrport = bridge_get_addr_port(bridge); + + if (!fascist_firewall_allows_address_addr(&addrport->addr, + addrport->port, + FIREWALL_OR_CONNECTION, + 0, 0)) + return 0; + + return 1; +} + +/** + * Return true iff <b>guard</b> is a Tor relay that we are configured to + * be able to connect to, and we haven't disabled it for omission from + * the consensus or path bias issues. */ +static int +entry_guard_passes_filter(const or_options_t *options, guard_selection_t *gs, + entry_guard_t *guard) +{ + if (guard->currently_listed == 0) + return 0; + if (guard->pb.path_bias_disabled) + return 0; + + if (gs->type == GS_TYPE_BRIDGE) { + const bridge_info_t *bridge = get_bridge_info_for_guard(guard); + if (bridge == NULL) + return 0; + return bridge_passes_guard_filter(options, bridge); + } else { + const node_t *node = node_get_by_id(guard->identity); + if (node == NULL) { + // This can happen when currently_listed is true, and we're not updating + // it because we don't have a live consensus. + return 0; + } + + return node_passes_guard_filter(options, node); + } +} + +/** Return true iff <b>guard</b> is in the same family as <b>node</b>. + */ +static int +guard_in_node_family(const entry_guard_t *guard, const node_t *node) +{ + const node_t *guard_node = node_get_by_id(guard->identity); + if (guard_node) { + return nodes_in_same_family(guard_node, node); + } else { + /* If we don't have a node_t for the guard node, we might have + * a bridge_info_t for it. So let's check to see whether the bridge + * address matches has any family issues. + * + * (Strictly speaking, I believe this check is unnecessary, since we only + * use it to avoid the exit's family when building circuits, and we don't + * build multihop circuits until we have a routerinfo_t for the + * bridge... at which point, we'll also have a node_t for the + * bridge. Nonetheless, it seems wise to include it, in case our + * assumptions change down the road. -nickm.) + */ + if (get_options()->EnforceDistinctSubnets && guard->bridge_addr) { + tor_addr_t node_addr; + node_get_addr(node, &node_addr); + if (addrs_in_same_network_family(&node_addr, + &guard->bridge_addr->addr)) { + return 1; + } + } + return 0; + } +} + +/* Allocate and return a new exit guard restriction (where <b>exit_id</b> is of + * size DIGEST_LEN) */ +STATIC entry_guard_restriction_t * +guard_create_exit_restriction(const uint8_t *exit_id) +{ + entry_guard_restriction_t *rst = NULL; + rst = tor_malloc_zero(sizeof(entry_guard_restriction_t)); + rst->type = RST_EXIT_NODE; + memcpy(rst->exclude_id, exit_id, DIGEST_LEN); + return rst; +} + +/** If we have fewer than this many possible usable guards, don't set + * MD-availability-based restrictions: we might blacklist all of them. */ +#define MIN_GUARDS_FOR_MD_RESTRICTION 10 + +/** Return true if we should set md dirserver restrictions. We might not want + * to set those if our guard options are too restricted, since we don't want + * to blacklist all of them. */ +static int +should_set_md_dirserver_restriction(void) +{ + const guard_selection_t *gs = get_guard_selection_info(); + int num_usable_guards = num_reachable_filtered_guards(gs, NULL); + + /* Don't set restriction if too few reachable filtered guards. */ + if (num_usable_guards < MIN_GUARDS_FOR_MD_RESTRICTION) { + log_info(LD_GUARD, "Not setting md restriction: only %d" + " usable guards.", num_usable_guards); + return 0; + } + + /* We have enough usable guards: set MD restriction */ + return 1; +} + +/** Allocate and return an outdated md guard restriction. Return NULL if no + * such restriction is needed. */ +STATIC entry_guard_restriction_t * +guard_create_dirserver_md_restriction(void) +{ + entry_guard_restriction_t *rst = NULL; + + if (!should_set_md_dirserver_restriction()) { + log_debug(LD_GUARD, "Not setting md restriction: too few " + "filtered guards."); + return NULL; + } + + rst = tor_malloc_zero(sizeof(entry_guard_restriction_t)); + rst->type = RST_OUTDATED_MD_DIRSERVER; + + return rst; +} + +/* Return True if <b>guard</b> obeys the exit restriction <b>rst</b>. */ +static int +guard_obeys_exit_restriction(const entry_guard_t *guard, + const entry_guard_restriction_t *rst) +{ + tor_assert(rst->type == RST_EXIT_NODE); + + // Exclude the exit ID and all of its family. + const node_t *node = node_get_by_id((const char*)rst->exclude_id); + if (node && guard_in_node_family(guard, node)) + return 0; + + return tor_memneq(guard->identity, rst->exclude_id, DIGEST_LEN); +} + +/** Return True if <b>guard</b> should be used as a dirserver for fetching + * microdescriptors. */ +static int +guard_obeys_md_dirserver_restriction(const entry_guard_t *guard) +{ + /* If this guard is an outdated dirserver, don't use it. */ + if (microdesc_relay_is_outdated_dirserver(guard->identity)) { + log_info(LD_GENERAL, "Skipping %s dirserver: outdated", + hex_str(guard->identity, DIGEST_LEN)); + return 0; + } + + log_debug(LD_GENERAL, "%s dirserver obeys md restrictions", + hex_str(guard->identity, DIGEST_LEN)); + + return 1; +} + +/** + * Return true iff <b>guard</b> obeys the restrictions defined in <b>rst</b>. + * (If <b>rst</b> is NULL, there are no restrictions.) + */ +static int +entry_guard_obeys_restriction(const entry_guard_t *guard, + const entry_guard_restriction_t *rst) +{ + tor_assert(guard); + if (! rst) + return 1; // No restriction? No problem. + + if (rst->type == RST_EXIT_NODE) { + return guard_obeys_exit_restriction(guard, rst); + } else if (rst->type == RST_OUTDATED_MD_DIRSERVER) { + return guard_obeys_md_dirserver_restriction(guard); + } + + tor_assert_nonfatal_unreached(); + return 0; +} + +/** + * Update the <b>is_filtered_guard</b> and <b>is_usable_filtered_guard</b> + * flags on <b>guard</b>. */ +void +entry_guard_set_filtered_flags(const or_options_t *options, + guard_selection_t *gs, + entry_guard_t *guard) +{ + unsigned was_filtered = guard->is_filtered_guard; + guard->is_filtered_guard = 0; + guard->is_usable_filtered_guard = 0; + + if (entry_guard_passes_filter(options, gs, guard)) { + guard->is_filtered_guard = 1; + + if (guard->is_reachable != GUARD_REACHABLE_NO) + guard->is_usable_filtered_guard = 1; + + entry_guard_consider_retry(guard); + } + log_debug(LD_GUARD, "Updated sampled guard %s: filtered=%d; " + "reachable_filtered=%d.", entry_guard_describe(guard), + guard->is_filtered_guard, guard->is_usable_filtered_guard); + + if (!bool_eq(was_filtered, guard->is_filtered_guard)) { + /* This guard might now be primary or nonprimary. */ + gs->primary_guards_up_to_date = 0; + } +} + +/** + * Update the <b>is_filtered_guard</b> and <b>is_usable_filtered_guard</b> + * flag on every guard in <b>gs</b>. */ +STATIC void +entry_guards_update_filtered_sets(guard_selection_t *gs) +{ + const or_options_t *options = get_options(); + + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + entry_guard_set_filtered_flags(options, gs, guard); + } SMARTLIST_FOREACH_END(guard); +} + +/** + * Return a random guard from the reachable filtered sample guards + * in <b>gs</b>, subject to the exclusion rules listed in <b>flags</b>. + * Return NULL if no such guard can be found. + * + * Make sure that the sample is big enough, and that all the filter flags + * are set correctly, before calling this function. + * + * If a restriction is provided in <b>rst</b>, do not return any guards that + * violate it. + **/ +STATIC entry_guard_t * +sample_reachable_filtered_entry_guards(guard_selection_t *gs, + const entry_guard_restriction_t *rst, + unsigned flags) +{ + tor_assert(gs); + entry_guard_t *result = NULL; + const unsigned exclude_confirmed = flags & SAMPLE_EXCLUDE_CONFIRMED; + const unsigned exclude_primary = flags & SAMPLE_EXCLUDE_PRIMARY; + const unsigned exclude_pending = flags & SAMPLE_EXCLUDE_PENDING; + const unsigned no_update_primary = flags & SAMPLE_NO_UPDATE_PRIMARY; + const unsigned need_descriptor = flags & SAMPLE_EXCLUDE_NO_DESCRIPTOR; + + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + entry_guard_consider_retry(guard); + } SMARTLIST_FOREACH_END(guard); + + const int n_reachable_filtered = num_reachable_filtered_guards(gs, rst); + + log_info(LD_GUARD, "Trying to sample a reachable guard: We know of %d " + "in the USABLE_FILTERED set.", n_reachable_filtered); + + const int min_filtered_sample = get_min_filtered_sample_size(); + if (n_reachable_filtered < min_filtered_sample) { + log_info(LD_GUARD, " (That isn't enough. Trying to expand the sample.)"); + entry_guards_expand_sample(gs); + } + + if (exclude_primary && !gs->primary_guards_up_to_date && !no_update_primary) + entry_guards_update_primary(gs); + + /* Build the set of reachable filtered guards. */ + smartlist_t *reachable_filtered_sample = smartlist_new(); + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + entry_guard_consider_retry(guard);// redundant, but cheap. + if (! entry_guard_obeys_restriction(guard, rst)) + continue; + if (! guard->is_usable_filtered_guard) + continue; + if (exclude_confirmed && guard->confirmed_idx >= 0) + continue; + if (exclude_primary && guard->is_primary) + continue; + if (exclude_pending && guard->is_pending) + continue; + if (need_descriptor && !guard_has_descriptor(guard)) + continue; + smartlist_add(reachable_filtered_sample, guard); + } SMARTLIST_FOREACH_END(guard); + + log_info(LD_GUARD, " (After filters [%x], we have %d guards to consider.)", + flags, smartlist_len(reachable_filtered_sample)); + + if (smartlist_len(reachable_filtered_sample)) { + result = smartlist_choose(reachable_filtered_sample); + log_info(LD_GUARD, " (Selected %s.)", + result ? entry_guard_describe(result) : "<null>"); + } + smartlist_free(reachable_filtered_sample); + + return result; +} + +/** + * Helper: compare two entry_guard_t by their confirmed_idx values. + * Used to sort the confirmed list. + */ +static int +compare_guards_by_confirmed_idx(const void **a_, const void **b_) +{ + const entry_guard_t *a = *a_, *b = *b_; + if (a->confirmed_idx < b->confirmed_idx) + return -1; + else if (a->confirmed_idx > b->confirmed_idx) + return 1; + else + return 0; +} + +/** + * Find the confirmed guards from among the sampled guards in <b>gs</b>, + * and put them in confirmed_entry_guards in the correct + * order. Recalculate their indices. + */ +STATIC void +entry_guards_update_confirmed(guard_selection_t *gs) +{ + smartlist_clear(gs->confirmed_entry_guards); + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + if (guard->confirmed_idx >= 0) + smartlist_add(gs->confirmed_entry_guards, guard); + } SMARTLIST_FOREACH_END(guard); + + smartlist_sort(gs->confirmed_entry_guards, compare_guards_by_confirmed_idx); + + int any_changed = 0; + SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) { + if (guard->confirmed_idx != guard_sl_idx) { + any_changed = 1; + guard->confirmed_idx = guard_sl_idx; + } + } SMARTLIST_FOREACH_END(guard); + + gs->next_confirmed_idx = smartlist_len(gs->confirmed_entry_guards); + + if (any_changed) { + entry_guards_changed_for_guard_selection(gs); + } +} + +/** + * Mark <b>guard</b> as a confirmed guard -- that is, one that we have + * connected to, and intend to use again. + */ +STATIC void +make_guard_confirmed(guard_selection_t *gs, entry_guard_t *guard) +{ + if (BUG(guard->confirmed_on_date && guard->confirmed_idx >= 0)) + return; // LCOV_EXCL_LINE + + if (BUG(smartlist_contains(gs->confirmed_entry_guards, guard))) + return; // LCOV_EXCL_LINE + + const int GUARD_LIFETIME = get_guard_lifetime(); + guard->confirmed_on_date = randomize_time(approx_time(), GUARD_LIFETIME/10); + + log_info(LD_GUARD, "Marking %s as a confirmed guard (index %d)", + entry_guard_describe(guard), + gs->next_confirmed_idx); + + guard->confirmed_idx = gs->next_confirmed_idx++; + smartlist_add(gs->confirmed_entry_guards, guard); + + // This confirmed guard might kick something else out of the primary + // guards. + gs->primary_guards_up_to_date = 0; + + entry_guards_changed_for_guard_selection(gs); +} + +/** + * Recalculate the list of primary guards (the ones we'd prefer to use) from + * the filtered sample and the confirmed list. + */ +STATIC void +entry_guards_update_primary(guard_selection_t *gs) +{ + tor_assert(gs); + + // prevent recursion. Recursion is potentially very bad here. + static int running = 0; + tor_assert(!running); + running = 1; + + const int N_PRIMARY_GUARDS = get_n_primary_guards(); + + smartlist_t *new_primary_guards = smartlist_new(); + smartlist_t *old_primary_guards = smartlist_new(); + smartlist_add_all(old_primary_guards, gs->primary_entry_guards); + + /* Set this flag now, to prevent the calls below from recursing. */ + gs->primary_guards_up_to_date = 1; + + /* First, can we fill it up with confirmed guards? */ + SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) { + if (smartlist_len(new_primary_guards) >= N_PRIMARY_GUARDS) + break; + if (! guard->is_filtered_guard) + continue; + guard->is_primary = 1; + smartlist_add(new_primary_guards, guard); + } SMARTLIST_FOREACH_END(guard); + + /* Can we keep any older primary guards? First remove all the ones + * that we already kept. */ + SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) { + if (smartlist_contains(new_primary_guards, guard)) { + SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard); + } + } SMARTLIST_FOREACH_END(guard); + + /* Now add any that are still good. */ + SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) { + if (smartlist_len(new_primary_guards) >= N_PRIMARY_GUARDS) + break; + if (! guard->is_filtered_guard) + continue; + guard->is_primary = 1; + smartlist_add(new_primary_guards, guard); + SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard); + } SMARTLIST_FOREACH_END(guard); + + /* Mark the remaining previous primary guards as non-primary */ + SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) { + guard->is_primary = 0; + } SMARTLIST_FOREACH_END(guard); + + /* Finally, fill out the list with sampled guards. */ + while (smartlist_len(new_primary_guards) < N_PRIMARY_GUARDS) { + entry_guard_t *guard = sample_reachable_filtered_entry_guards(gs, NULL, + SAMPLE_EXCLUDE_CONFIRMED| + SAMPLE_EXCLUDE_PRIMARY| + SAMPLE_NO_UPDATE_PRIMARY); + if (!guard) + break; + guard->is_primary = 1; + smartlist_add(new_primary_guards, guard); + } + +#if 1 + /* Debugging. */ + SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, guard, { + tor_assert_nonfatal( + bool_eq(guard->is_primary, + smartlist_contains(new_primary_guards, guard))); + }); +#endif /* 1 */ + + int any_change = 0; + if (smartlist_len(gs->primary_entry_guards) != + smartlist_len(new_primary_guards)) { + any_change = 1; + } else { + SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, g) { + if (g != smartlist_get(new_primary_guards, g_sl_idx)) { + any_change = 1; + } + } SMARTLIST_FOREACH_END(g); + } + + if (any_change) { + log_info(LD_GUARD, "Primary entry guards have changed. " + "New primary guard list is: "); + int n = smartlist_len(new_primary_guards); + SMARTLIST_FOREACH_BEGIN(new_primary_guards, entry_guard_t *, g) { + log_info(LD_GUARD, " %d/%d: %s%s%s", + g_sl_idx+1, n, entry_guard_describe(g), + g->confirmed_idx >= 0 ? " (confirmed)" : "", + g->is_filtered_guard ? "" : " (excluded by filter)"); + } SMARTLIST_FOREACH_END(g); + } + + smartlist_free(old_primary_guards); + smartlist_free(gs->primary_entry_guards); + gs->primary_entry_guards = new_primary_guards; + gs->primary_guards_up_to_date = 1; + running = 0; +} + +/** + * Return the number of seconds after the last attempt at which we should + * retry a guard that has been failing since <b>failing_since</b>. + */ +static int +get_retry_schedule(time_t failing_since, time_t now, + int is_primary) +{ + const unsigned SIX_HOURS = 6 * 3600; + const unsigned FOUR_DAYS = 4 * 86400; + const unsigned SEVEN_DAYS = 7 * 86400; + + time_t tdiff; + if (now > failing_since) { + tdiff = now - failing_since; + } else { + tdiff = 0; + } + + const struct { + time_t maximum; int primary_delay; int nonprimary_delay; + } delays[] = { + { SIX_HOURS, 10*60, 1*60*60 }, + { FOUR_DAYS, 90*60, 4*60*60 }, + { SEVEN_DAYS, 4*60*60, 18*60*60 }, + { TIME_MAX, 9*60*60, 36*60*60 } + }; + + unsigned i; + for (i = 0; i < ARRAY_LENGTH(delays); ++i) { + if (tdiff <= delays[i].maximum) { + return is_primary ? delays[i].primary_delay : delays[i].nonprimary_delay; + } + } + /* LCOV_EXCL_START -- can't reach, since delays ends with TIME_MAX. */ + tor_assert_nonfatal_unreached(); + return 36*60*60; + /* LCOV_EXCL_STOP */ +} + +/** + * If <b>guard</b> is unreachable, consider whether enough time has passed + * to consider it maybe-reachable again. + */ +STATIC void +entry_guard_consider_retry(entry_guard_t *guard) +{ + if (guard->is_reachable != GUARD_REACHABLE_NO) + return; /* No retry needed. */ + + const time_t now = approx_time(); + const int delay = + get_retry_schedule(guard->failing_since, now, guard->is_primary); + const time_t last_attempt = guard->last_tried_to_connect; + + if (BUG(last_attempt == 0) || + now >= last_attempt + delay) { + /* We should mark this retriable. */ + char tbuf[ISO_TIME_LEN+1]; + format_local_iso_time(tbuf, last_attempt); + log_info(LD_GUARD, "Marked %s%sguard %s for possible retry, since we " + "haven't tried to use it since %s.", + guard->is_primary?"primary ":"", + guard->confirmed_idx>=0?"confirmed ":"", + entry_guard_describe(guard), + tbuf); + + guard->is_reachable = GUARD_REACHABLE_MAYBE; + if (guard->is_filtered_guard) + guard->is_usable_filtered_guard = 1; + } +} + +/** Tell the entry guards subsystem that we have confirmed that as of + * just now, we're on the internet. */ +void +entry_guards_note_internet_connectivity(guard_selection_t *gs) +{ + gs->last_time_on_internet = approx_time(); +} + +/** + * Get a guard for use with a circuit. Prefer to pick a running primary + * guard; then a non-pending running filtered confirmed guard; then a + * non-pending runnable filtered guard. Update the + * <b>last_tried_to_connect</b> time and the <b>is_pending</b> fields of the + * guard as appropriate. Set <b>state_out</b> to the new guard-state + * of the circuit. + */ +STATIC entry_guard_t * +select_entry_guard_for_circuit(guard_selection_t *gs, + guard_usage_t usage, + const entry_guard_restriction_t *rst, + unsigned *state_out) +{ + const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC); + tor_assert(gs); + tor_assert(state_out); + + if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); + + int num_entry_guards = get_n_primary_guards_to_use(usage); + smartlist_t *usable_primary_guards = smartlist_new(); + + /* "If any entry in PRIMARY_GUARDS has {is_reachable} status of + <maybe> or <yes>, return the first such guard." */ + SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { + entry_guard_consider_retry(guard); + if (! entry_guard_obeys_restriction(guard, rst)) + continue; + if (guard->is_reachable != GUARD_REACHABLE_NO) { + if (need_descriptor && !guard_has_descriptor(guard)) { + continue; + } + *state_out = GUARD_CIRC_STATE_USABLE_ON_COMPLETION; + guard->last_tried_to_connect = approx_time(); + smartlist_add(usable_primary_guards, guard); + if (smartlist_len(usable_primary_guards) >= num_entry_guards) + break; + } + } SMARTLIST_FOREACH_END(guard); + + if (smartlist_len(usable_primary_guards)) { + entry_guard_t *guard = smartlist_choose(usable_primary_guards); + smartlist_free(usable_primary_guards); + log_info(LD_GUARD, "Selected primary guard %s for circuit.", + entry_guard_describe(guard)); + return guard; + } + smartlist_free(usable_primary_guards); + + /* "Otherwise, if the ordered intersection of {CONFIRMED_GUARDS} + and {USABLE_FILTERED_GUARDS} is nonempty, return the first + entry in that intersection that has {is_pending} set to + false." */ + SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) { + if (guard->is_primary) + continue; /* we already considered this one. */ + if (! entry_guard_obeys_restriction(guard, rst)) + continue; + entry_guard_consider_retry(guard); + if (guard->is_usable_filtered_guard && ! guard->is_pending) { + if (need_descriptor && !guard_has_descriptor(guard)) + continue; /* not a bug */ + guard->is_pending = 1; + guard->last_tried_to_connect = approx_time(); + *state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD; + log_info(LD_GUARD, "No primary guards available. Selected confirmed " + "guard %s for circuit. Will try other guards before using " + "this circuit.", + entry_guard_describe(guard)); + return guard; + } + } SMARTLIST_FOREACH_END(guard); + + /* "Otherwise, if there is no such entry, select a member at + random from {USABLE_FILTERED_GUARDS}." */ + { + entry_guard_t *guard; + unsigned flags = 0; + if (need_descriptor) + flags |= SAMPLE_EXCLUDE_NO_DESCRIPTOR; + guard = sample_reachable_filtered_entry_guards(gs, + rst, + SAMPLE_EXCLUDE_CONFIRMED | + SAMPLE_EXCLUDE_PRIMARY | + SAMPLE_EXCLUDE_PENDING | + flags); + if (guard == NULL) { + log_info(LD_GUARD, "Absolutely no sampled guards were available. " + "Marking all guards for retry and starting from top again."); + mark_all_guards_maybe_reachable(gs); + return NULL; + } + guard->is_pending = 1; + guard->last_tried_to_connect = approx_time(); + *state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD; + log_info(LD_GUARD, "No primary or confirmed guards available. Selected " + "random guard %s for circuit. Will try other guards before " + "using this circuit.", + entry_guard_describe(guard)); + return guard; + } +} + +/** + * Note that we failed to connect to or build circuits through <b>guard</b>. + * Use with a guard returned by select_entry_guard_for_circuit(). + */ +STATIC void +entry_guards_note_guard_failure(guard_selection_t *gs, + entry_guard_t *guard) +{ + tor_assert(gs); + + guard->is_reachable = GUARD_REACHABLE_NO; + guard->is_usable_filtered_guard = 0; + + guard->is_pending = 0; + if (guard->failing_since == 0) + guard->failing_since = approx_time(); + + log_info(LD_GUARD, "Recorded failure for %s%sguard %s", + guard->is_primary?"primary ":"", + guard->confirmed_idx>=0?"confirmed ":"", + entry_guard_describe(guard)); +} + +/** + * Note that we successfully connected to, and built a circuit through + * <b>guard</b>. Given the old guard-state of the circuit in <b>old_state</b>, + * return the new guard-state of the circuit. + * + * Be aware: the circuit is only usable when its guard-state becomes + * GUARD_CIRC_STATE_COMPLETE. + **/ +STATIC unsigned +entry_guards_note_guard_success(guard_selection_t *gs, + entry_guard_t *guard, + unsigned old_state) +{ + tor_assert(gs); + + /* Save this, since we're about to overwrite it. */ + const time_t last_time_on_internet = gs->last_time_on_internet; + gs->last_time_on_internet = approx_time(); + + guard->is_reachable = GUARD_REACHABLE_YES; + guard->failing_since = 0; + guard->is_pending = 0; + if (guard->is_filtered_guard) + guard->is_usable_filtered_guard = 1; + + if (guard->confirmed_idx < 0) { + make_guard_confirmed(gs, guard); + if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); + } + + unsigned new_state; + switch (old_state) { + case GUARD_CIRC_STATE_COMPLETE: + case GUARD_CIRC_STATE_USABLE_ON_COMPLETION: + new_state = GUARD_CIRC_STATE_COMPLETE; + break; + default: + tor_assert_nonfatal_unreached(); + /* Fall through. */ + case GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD: + if (guard->is_primary) { + /* XXXX #20832 -- I don't actually like this logic. It seems to make + * us a little more susceptible to evil-ISP attacks. The mitigations + * I'm thinking of, however, aren't local to this point, so I'll leave + * it alone. */ + /* This guard may have become primary by virtue of being confirmed. + * If so, the circuit for it is now complete. + */ + new_state = GUARD_CIRC_STATE_COMPLETE; + } else { + new_state = GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD; + } + break; + } + + if (! guard->is_primary) { + if (last_time_on_internet + get_internet_likely_down_interval() + < approx_time()) { + mark_primary_guards_maybe_reachable(gs); + } + } + + log_info(LD_GUARD, "Recorded success for %s%sguard %s", + guard->is_primary?"primary ":"", + guard->confirmed_idx>=0?"confirmed ":"", + entry_guard_describe(guard)); + + return new_state; +} + +/** + * Helper: Return true iff <b>a</b> has higher priority than <b>b</b>. + */ +STATIC int +entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b) +{ + tor_assert(a && b); + if (a == b) + return 0; + + /* Confirmed is always better than unconfirmed; lower index better + than higher */ + if (a->confirmed_idx < 0) { + if (b->confirmed_idx >= 0) + return 0; + } else { + if (b->confirmed_idx < 0) + return 1; + + /* Lower confirmed_idx is better than higher. */ + return (a->confirmed_idx < b->confirmed_idx); + } + + /* If we reach this point, both are unconfirmed. If one is pending, it + * has higher priority. */ + if (a->is_pending) { + if (! b->is_pending) + return 1; + + /* Both are pending: earlier last_tried_connect wins. */ + return a->last_tried_to_connect < b->last_tried_to_connect; + } else { + if (b->is_pending) + return 0; + + /* Neither is pending: priorities are equal. */ + return 0; + } +} + +/** Release all storage held in <b>restriction</b> */ +STATIC void +entry_guard_restriction_free_(entry_guard_restriction_t *rst) +{ + tor_free(rst); +} + +/** + * Release all storage held in <b>state</b>. + */ +void +circuit_guard_state_free_(circuit_guard_state_t *state) +{ + if (!state) + return; + entry_guard_restriction_free(state->restrictions); + entry_guard_handle_free(state->guard); + tor_free(state); +} + +/** Allocate and return a new circuit_guard_state_t to track the result + * of using <b>guard</b> for a given operation. */ +MOCK_IMPL(STATIC circuit_guard_state_t *, +circuit_guard_state_new,(entry_guard_t *guard, unsigned state, + entry_guard_restriction_t *rst)) +{ + circuit_guard_state_t *result; + + result = tor_malloc_zero(sizeof(circuit_guard_state_t)); + result->guard = entry_guard_handle_new(guard); + result->state = state; + result->state_set_at = approx_time(); + result->restrictions = rst; + + return result; +} + +/** + * Pick a suitable entry guard for a circuit in, and place that guard + * in *<b>chosen_node_out</b>. Set *<b>guard_state_out</b> to an opaque + * state object that will record whether the circuit is ready to be used + * or not. Return 0 on success; on failure, return -1. + * + * If a restriction is provided in <b>rst</b>, do not return any guards that + * violate it, and remember that restriction in <b>guard_state_out</b> for + * later use. (Takes ownership of the <b>rst</b> object.) + */ +int +entry_guard_pick_for_circuit(guard_selection_t *gs, + guard_usage_t usage, + entry_guard_restriction_t *rst, + const node_t **chosen_node_out, + circuit_guard_state_t **guard_state_out) +{ + tor_assert(gs); + tor_assert(chosen_node_out); + tor_assert(guard_state_out); + *chosen_node_out = NULL; + *guard_state_out = NULL; + + unsigned state = 0; + entry_guard_t *guard = + select_entry_guard_for_circuit(gs, usage, rst, &state); + if (! guard) + goto fail; + if (BUG(state == 0)) + goto fail; + const node_t *node = node_get_by_id(guard->identity); + // XXXX #20827 check Ed ID. + if (! node) + goto fail; + if (BUG(usage != GUARD_USAGE_DIRGUARD && + !node_has_preferred_descriptor(node, 1))) + goto fail; + + *chosen_node_out = node; + *guard_state_out = circuit_guard_state_new(guard, state, rst); + + return 0; + fail: + entry_guard_restriction_free(rst); + return -1; +} + +/** + * Called by the circuit building module when a circuit has succeeded: informs + * the guards code that the guard in *<b>guard_state_p</b> is working, and + * advances the state of the guard module. On a GUARD_USABLE_NEVER return + * value, the circuit is broken and should not be used. On a GUARD_USABLE_NOW + * return value, the circuit is ready to use. On a GUARD_MAYBE_USABLE_LATER + * return value, the circuit should not be used until we find out whether + * preferred guards will work for us. + */ +guard_usable_t +entry_guard_succeeded(circuit_guard_state_t **guard_state_p) +{ + if (BUG(*guard_state_p == NULL)) + return GUARD_USABLE_NEVER; + + entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard); + if (! guard || BUG(guard->in_selection == NULL)) + return GUARD_USABLE_NEVER; + + unsigned newstate = + entry_guards_note_guard_success(guard->in_selection, guard, + (*guard_state_p)->state); + + (*guard_state_p)->state = newstate; + (*guard_state_p)->state_set_at = approx_time(); + + if (newstate == GUARD_CIRC_STATE_COMPLETE) { + return GUARD_USABLE_NOW; + } else { + return GUARD_MAYBE_USABLE_LATER; + } +} + +/** Cancel the selection of *<b>guard_state_p</b> without declaring + * success or failure. It is safe to call this function if success or + * failure _has_ already been declared. */ +void +entry_guard_cancel(circuit_guard_state_t **guard_state_p) +{ + if (BUG(*guard_state_p == NULL)) + return; + entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard); + if (! guard) + return; + + /* XXXX prop271 -- last_tried_to_connect_at will be erroneous here, but this + * function will only get called in "bug" cases anyway. */ + guard->is_pending = 0; + circuit_guard_state_free(*guard_state_p); + *guard_state_p = NULL; +} + +/** + * Called by the circuit building module when a circuit has failed: + * informs the guards code that the guard in *<b>guard_state_p</b> is + * not working, and advances the state of the guard module. + */ +void +entry_guard_failed(circuit_guard_state_t **guard_state_p) +{ + if (BUG(*guard_state_p == NULL)) + return; + + entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard); + if (! guard || BUG(guard->in_selection == NULL)) + return; + + entry_guards_note_guard_failure(guard->in_selection, guard); + + (*guard_state_p)->state = GUARD_CIRC_STATE_DEAD; + (*guard_state_p)->state_set_at = approx_time(); +} + +/** + * Run the entry_guard_failed() function on every circuit that is + * pending on <b>chan</b>. + */ +void +entry_guard_chan_failed(channel_t *chan) +{ + if (!chan) + return; + + smartlist_t *pending = smartlist_new(); + circuit_get_all_pending_on_channel(pending, chan); + SMARTLIST_FOREACH_BEGIN(pending, circuit_t *, circ) { + if (!CIRCUIT_IS_ORIGIN(circ)) + continue; + + origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ); + if (origin_circ->guard_state) { + /* We might have no guard state if we didn't use a guard on this + * circuit (eg it's for a fallback directory). */ + entry_guard_failed(&origin_circ->guard_state); + } + } SMARTLIST_FOREACH_END(circ); + smartlist_free(pending); +} + +/** + * Return true iff every primary guard in <b>gs</b> is believed to + * be unreachable. + */ +STATIC int +entry_guards_all_primary_guards_are_down(guard_selection_t *gs) +{ + tor_assert(gs); + if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); + SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { + entry_guard_consider_retry(guard); + if (guard->is_reachable != GUARD_REACHABLE_NO) + return 0; + } SMARTLIST_FOREACH_END(guard); + return 1; +} + +/** Wrapper for entry_guard_has_higher_priority that compares the + * guard-priorities of a pair of circuits. Return 1 if <b>a</b> has higher + * priority than <b>b</b>. + * + * If a restriction is provided in <b>rst</b>, then do not consider + * <b>a</b> to have higher priority if it violates the restriction. + */ +static int +circ_state_has_higher_priority(origin_circuit_t *a, + const entry_guard_restriction_t *rst, + origin_circuit_t *b) +{ + circuit_guard_state_t *state_a = origin_circuit_get_guard_state(a); + circuit_guard_state_t *state_b = origin_circuit_get_guard_state(b); + + tor_assert(state_a); + tor_assert(state_b); + + entry_guard_t *guard_a = entry_guard_handle_get(state_a->guard); + entry_guard_t *guard_b = entry_guard_handle_get(state_b->guard); + + if (! guard_a) { + /* Unknown guard -- never higher priority. */ + return 0; + } else if (! guard_b) { + /* Known guard -- higher priority than any unknown guard. */ + return 1; + } else if (! entry_guard_obeys_restriction(guard_a, rst)) { + /* Restriction violated; guard_a cannot have higher priority. */ + return 0; + } else { + /* Both known -- compare.*/ + return entry_guard_has_higher_priority(guard_a, guard_b); + } +} + +/** + * Look at all of the origin_circuit_t * objects in <b>all_circuits_in</b>, + * and see if any of them that were previously not ready to use for + * guard-related reasons are now ready to use. Place those circuits + * in <b>newly_complete_out</b>, and mark them COMPLETE. + * + * Return 1 if we upgraded any circuits, and 0 otherwise. + */ +int +entry_guards_upgrade_waiting_circuits(guard_selection_t *gs, + const smartlist_t *all_circuits_in, + smartlist_t *newly_complete_out) +{ + tor_assert(gs); + tor_assert(all_circuits_in); + tor_assert(newly_complete_out); + + if (! entry_guards_all_primary_guards_are_down(gs)) { + /* We only upgrade a waiting circuit if the primary guards are all + * down. */ + log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, " + "but not all primary guards were definitely down."); + return 0; + } + + int n_waiting = 0; + int n_complete = 0; + int n_complete_blocking = 0; + origin_circuit_t *best_waiting_circuit = NULL; + smartlist_t *all_circuits = smartlist_new(); + SMARTLIST_FOREACH_BEGIN(all_circuits_in, origin_circuit_t *, circ) { + // We filter out circuits that aren't ours, or which we can't + // reason about. + circuit_guard_state_t *state = origin_circuit_get_guard_state(circ); + if (state == NULL) + continue; + entry_guard_t *guard = entry_guard_handle_get(state->guard); + if (!guard || guard->in_selection != gs) + continue; + + smartlist_add(all_circuits, circ); + } SMARTLIST_FOREACH_END(circ); + + SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) { + circuit_guard_state_t *state = origin_circuit_get_guard_state(circ); + if (BUG(state == NULL)) + continue; + + if (state->state == GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD) { + ++n_waiting; + if (! best_waiting_circuit || + circ_state_has_higher_priority(circ, NULL, best_waiting_circuit)) { + best_waiting_circuit = circ; + } + } + } SMARTLIST_FOREACH_END(circ); + + if (! best_waiting_circuit) { + log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, " + "but didn't find any."); + goto no_change; + } + + /* We'll need to keep track of what restrictions were used when picking this + * circuit, so that we don't allow any circuit without those restrictions to + * block it. */ + const entry_guard_restriction_t *rst_on_best_waiting = + origin_circuit_get_guard_state(best_waiting_circuit)->restrictions; + + /* First look at the complete circuits: Do any block this circuit? */ + SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) { + /* "C2 "blocks" C1 if: + * C2 obeys all the restrictions that C1 had to obey, AND + * C2 has higher priority than C1, AND + * Either C2 is <complete>, or C2 is <waiting_for_better_guard>, + or C2 has been <usable_if_no_better_guard> for no more than + {NONPRIMARY_GUARD_CONNECT_TIMEOUT} seconds." + */ + circuit_guard_state_t *state = origin_circuit_get_guard_state(circ); + if BUG((state == NULL)) + continue; + if (state->state != GUARD_CIRC_STATE_COMPLETE) + continue; + ++n_complete; + if (circ_state_has_higher_priority(circ, rst_on_best_waiting, + best_waiting_circuit)) + ++n_complete_blocking; + } SMARTLIST_FOREACH_END(circ); + + if (n_complete_blocking) { + log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found " + "%d complete and %d guard-stalled. At least one complete " + "circuit had higher priority, so not upgrading.", + n_complete, n_waiting); + goto no_change; + } + + /* " * If any circuit C1 is <waiting_for_better_guard>, AND: + * All primary guards have reachable status of <no>. + * There is no circuit C2 that "blocks" C1. + Then, upgrade C1 to <complete>."" + */ + int n_blockers_found = 0; + const time_t state_set_at_cutoff = + approx_time() - get_nonprimary_guard_connect_timeout(); + SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) { + circuit_guard_state_t *state = origin_circuit_get_guard_state(circ); + if (BUG(state == NULL)) + continue; + if (state->state != GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD) + continue; + if (state->state_set_at <= state_set_at_cutoff) + continue; + if (circ_state_has_higher_priority(circ, rst_on_best_waiting, + best_waiting_circuit)) + ++n_blockers_found; + } SMARTLIST_FOREACH_END(circ); + + if (n_blockers_found) { + log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found " + "%d guard-stalled, but %d pending circuit(s) had higher " + "guard priority, so not upgrading.", + n_waiting, n_blockers_found); + goto no_change; + } + + /* Okay. We have a best waiting circuit, and we aren't waiting for + anything better. Add all circuits with that priority to the + list, and call them COMPLETE. */ + int n_succeeded = 0; + SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) { + circuit_guard_state_t *state = origin_circuit_get_guard_state(circ); + if (BUG(state == NULL)) + continue; + if (circ != best_waiting_circuit && rst_on_best_waiting) { + /* Can't upgrade other circ with same priority as best; might + be blocked. */ + continue; + } + if (state->state != GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD) + continue; + if (circ_state_has_higher_priority(best_waiting_circuit, NULL, circ)) + continue; + + state->state = GUARD_CIRC_STATE_COMPLETE; + state->state_set_at = approx_time(); + smartlist_add(newly_complete_out, circ); + ++n_succeeded; + } SMARTLIST_FOREACH_END(circ); + + log_info(LD_GUARD, "Considered upgrading guard-stalled circuits: found " + "%d guard-stalled, %d complete. %d of the guard-stalled " + "circuit(s) had high enough priority to upgrade.", + n_waiting, n_complete, n_succeeded); + + tor_assert_nonfatal(n_succeeded >= 1); + smartlist_free(all_circuits); + return 1; + + no_change: + smartlist_free(all_circuits); + return 0; +} + +/** + * Return true iff the circuit whose state is <b>guard_state</b> should + * expire. + */ +int +entry_guard_state_should_expire(circuit_guard_state_t *guard_state) +{ + if (guard_state == NULL) + return 0; + const time_t expire_if_waiting_since = + approx_time() - get_nonprimary_guard_idle_timeout(); + return (guard_state->state == GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD + && guard_state->state_set_at < expire_if_waiting_since); +} + +/** + * Update all derived pieces of the guard selection state in <b>gs</b>. + * Return true iff we should stop using all previously generated circuits. + */ +int +entry_guards_update_all(guard_selection_t *gs) +{ + sampled_guards_update_from_consensus(gs); + entry_guards_update_filtered_sets(gs); + entry_guards_update_confirmed(gs); + entry_guards_update_primary(gs); + return 0; +} + +/** + * Return a newly allocated string for encoding the persistent parts of + * <b>guard</b> to the state file. + */ +STATIC char * +entry_guard_encode_for_state(entry_guard_t *guard) +{ + /* + * The meta-format we use is K=V K=V K=V... where K can be any + * characters excepts space and =, and V can be any characters except + * space. The order of entries is not allowed to matter. + * Unrecognized K=V entries are persisted; recognized but erroneous + * entries are corrected. + */ + + smartlist_t *result = smartlist_new(); + char tbuf[ISO_TIME_LEN+1]; + + tor_assert(guard); + + smartlist_add_asprintf(result, "in=%s", guard->selection_name); + smartlist_add_asprintf(result, "rsa_id=%s", + hex_str(guard->identity, DIGEST_LEN)); + if (guard->bridge_addr) { + smartlist_add_asprintf(result, "bridge_addr=%s:%d", + fmt_and_decorate_addr(&guard->bridge_addr->addr), + guard->bridge_addr->port); + } + if (strlen(guard->nickname) && is_legal_nickname(guard->nickname)) { + smartlist_add_asprintf(result, "nickname=%s", guard->nickname); + } + + format_iso_time_nospace(tbuf, guard->sampled_on_date); + smartlist_add_asprintf(result, "sampled_on=%s", tbuf); + + if (guard->sampled_by_version) { + smartlist_add_asprintf(result, "sampled_by=%s", + guard->sampled_by_version); + } + + if (guard->unlisted_since_date > 0) { + format_iso_time_nospace(tbuf, guard->unlisted_since_date); + smartlist_add_asprintf(result, "unlisted_since=%s", tbuf); + } + + smartlist_add_asprintf(result, "listed=%d", + (int)guard->currently_listed); + + if (guard->confirmed_idx >= 0) { + format_iso_time_nospace(tbuf, guard->confirmed_on_date); + smartlist_add_asprintf(result, "confirmed_on=%s", tbuf); + + smartlist_add_asprintf(result, "confirmed_idx=%d", guard->confirmed_idx); + } + + const double EPSILON = 1.0e-6; + + /* Make a copy of the pathbias object, since we will want to update + some of them */ + guard_pathbias_t *pb = tor_memdup(&guard->pb, sizeof(*pb)); + pb->use_successes = pathbias_get_use_success_count(guard); + pb->successful_circuits_closed = pathbias_get_close_success_count(guard); + + #define PB_FIELD(field) do { \ + if (pb->field >= EPSILON) { \ + smartlist_add_asprintf(result, "pb_" #field "=%f", pb->field); \ + } \ + } while (0) + PB_FIELD(use_attempts); + PB_FIELD(use_successes); + PB_FIELD(circ_attempts); + PB_FIELD(circ_successes); + PB_FIELD(successful_circuits_closed); + PB_FIELD(collapsed_circuits); + PB_FIELD(unusable_circuits); + PB_FIELD(timeouts); + tor_free(pb); +#undef PB_FIELD + + if (guard->extra_state_fields) + smartlist_add_strdup(result, guard->extra_state_fields); + + char *joined = smartlist_join_strings(result, " ", 0, NULL); + SMARTLIST_FOREACH(result, char *, cp, tor_free(cp)); + smartlist_free(result); + + return joined; +} + +/** + * Given a string generated by entry_guard_encode_for_state(), parse it + * (if possible) and return an entry_guard_t object for it. Return NULL + * on complete failure. + */ +STATIC entry_guard_t * +entry_guard_parse_from_state(const char *s) +{ + /* Unrecognized entries get put in here. */ + smartlist_t *extra = smartlist_new(); + + /* These fields get parsed from the string. */ + char *in = NULL; + char *rsa_id = NULL; + char *nickname = NULL; + char *sampled_on = NULL; + char *sampled_by = NULL; + char *unlisted_since = NULL; + char *listed = NULL; + char *confirmed_on = NULL; + char *confirmed_idx = NULL; + char *bridge_addr = NULL; + + // pathbias + char *pb_use_attempts = NULL; + char *pb_use_successes = NULL; + char *pb_circ_attempts = NULL; + char *pb_circ_successes = NULL; + char *pb_successful_circuits_closed = NULL; + char *pb_collapsed_circuits = NULL; + char *pb_unusable_circuits = NULL; + char *pb_timeouts = NULL; + + /* Split up the entries. Put the ones we know about in strings and the + * rest in "extra". */ + { + smartlist_t *entries = smartlist_new(); + + strmap_t *vals = strmap_new(); // Maps keyword to location +#define FIELD(f) \ + strmap_set(vals, #f, &f); + FIELD(in); + FIELD(rsa_id); + FIELD(nickname); + FIELD(sampled_on); + FIELD(sampled_by); + FIELD(unlisted_since); + FIELD(listed); + FIELD(confirmed_on); + FIELD(confirmed_idx); + FIELD(bridge_addr); + FIELD(pb_use_attempts); + FIELD(pb_use_successes); + FIELD(pb_circ_attempts); + FIELD(pb_circ_successes); + FIELD(pb_successful_circuits_closed); + FIELD(pb_collapsed_circuits); + FIELD(pb_unusable_circuits); + FIELD(pb_timeouts); +#undef FIELD + + smartlist_split_string(entries, s, " ", + SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0); + + SMARTLIST_FOREACH_BEGIN(entries, char *, entry) { + const char *eq = strchr(entry, '='); + if (!eq) { + smartlist_add(extra, entry); + continue; + } + char *key = tor_strndup(entry, eq-entry); + char **target = strmap_get(vals, key); + if (target == NULL || *target != NULL) { + /* unrecognized or already set */ + smartlist_add(extra, entry); + tor_free(key); + continue; + } + + *target = tor_strdup(eq+1); + tor_free(key); + tor_free(entry); + } SMARTLIST_FOREACH_END(entry); + + smartlist_free(entries); + strmap_free(vals, NULL); + } + + entry_guard_t *guard = tor_malloc_zero(sizeof(entry_guard_t)); + guard->is_persistent = 1; + + if (in == NULL) { + log_warn(LD_CIRC, "Guard missing 'in' field"); + goto err; + } + + guard->selection_name = in; + in = NULL; + + if (rsa_id == NULL) { + log_warn(LD_CIRC, "Guard missing RSA ID field"); + goto err; + } + + /* Process the identity and nickname. */ + if (base16_decode(guard->identity, sizeof(guard->identity), + rsa_id, strlen(rsa_id)) != DIGEST_LEN) { + log_warn(LD_CIRC, "Unable to decode guard identity %s", escaped(rsa_id)); + goto err; + } + + if (nickname) { + strlcpy(guard->nickname, nickname, sizeof(guard->nickname)); + } else { + guard->nickname[0]='$'; + base16_encode(guard->nickname+1, sizeof(guard->nickname)-1, + guard->identity, DIGEST_LEN); + } + + if (bridge_addr) { + tor_addr_port_t res; + memset(&res, 0, sizeof(res)); + int r = tor_addr_port_parse(LOG_WARN, bridge_addr, + &res.addr, &res.port, -1); + if (r == 0) + guard->bridge_addr = tor_memdup(&res, sizeof(res)); + /* On error, we already warned. */ + } + + /* Process the various time fields. */ + +#define HANDLE_TIME(field) do { \ + if (field) { \ + int r = parse_iso_time_nospace(field, &field ## _time); \ + if (r < 0) { \ + log_warn(LD_CIRC, "Unable to parse %s %s from guard", \ + #field, escaped(field)); \ + field##_time = -1; \ + } \ + } \ + } while (0) + + time_t sampled_on_time = 0; + time_t unlisted_since_time = 0; + time_t confirmed_on_time = 0; + + HANDLE_TIME(sampled_on); + HANDLE_TIME(unlisted_since); + HANDLE_TIME(confirmed_on); + + if (sampled_on_time <= 0) + sampled_on_time = approx_time(); + if (unlisted_since_time < 0) + unlisted_since_time = 0; + if (confirmed_on_time < 0) + confirmed_on_time = 0; + + #undef HANDLE_TIME + + guard->sampled_on_date = sampled_on_time; + guard->unlisted_since_date = unlisted_since_time; + guard->confirmed_on_date = confirmed_on_time; + + /* Take sampled_by_version verbatim. */ + guard->sampled_by_version = sampled_by; + sampled_by = NULL; /* prevent free */ + + /* Listed is a boolean */ + if (listed && strcmp(listed, "0")) + guard->currently_listed = 1; + + /* The index is a nonnegative integer. */ + guard->confirmed_idx = -1; + if (confirmed_idx) { + int ok=1; + long idx = tor_parse_long(confirmed_idx, 10, 0, INT_MAX, &ok, NULL); + if (! ok) { + log_warn(LD_GUARD, "Guard has invalid confirmed_idx %s", + escaped(confirmed_idx)); + } else { + guard->confirmed_idx = (int)idx; + } + } + + /* Anything we didn't recognize gets crammed together */ + if (smartlist_len(extra) > 0) { + guard->extra_state_fields = smartlist_join_strings(extra, " ", 0, NULL); + } + + /* initialize non-persistent fields */ + guard->is_reachable = GUARD_REACHABLE_MAYBE; + +#define PB_FIELD(field) \ + do { \ + if (pb_ ## field) { \ + int ok = 1; \ + double r = tor_parse_double(pb_ ## field, 0.0, 1e9, &ok, NULL); \ + if (! ok) { \ + log_warn(LD_CIRC, "Guard has invalid pb_%s %s", \ + #field, pb_ ## field); \ + } else { \ + guard->pb.field = r; \ + } \ + } \ + } while (0) + PB_FIELD(use_attempts); + PB_FIELD(use_successes); + PB_FIELD(circ_attempts); + PB_FIELD(circ_successes); + PB_FIELD(successful_circuits_closed); + PB_FIELD(collapsed_circuits); + PB_FIELD(unusable_circuits); + PB_FIELD(timeouts); +#undef PB_FIELD + + pathbias_check_use_success_count(guard); + pathbias_check_close_success_count(guard); + + /* We update everything on this guard later, after we've parsed + * everything. */ + + goto done; + + err: + // only consider it an error if the guard state was totally unparseable. + entry_guard_free(guard); + guard = NULL; + + done: + tor_free(in); + tor_free(rsa_id); + tor_free(nickname); + tor_free(sampled_on); + tor_free(sampled_by); + tor_free(unlisted_since); + tor_free(listed); + tor_free(confirmed_on); + tor_free(confirmed_idx); + tor_free(bridge_addr); + tor_free(pb_use_attempts); + tor_free(pb_use_successes); + tor_free(pb_circ_attempts); + tor_free(pb_circ_successes); + tor_free(pb_successful_circuits_closed); + tor_free(pb_collapsed_circuits); + tor_free(pb_unusable_circuits); + tor_free(pb_timeouts); + + SMARTLIST_FOREACH(extra, char *, cp, tor_free(cp)); + smartlist_free(extra); + + return guard; +} + +/** + * Replace the Guards entries in <b>state</b> with a list of all our sampled + * guards. + */ +static void +entry_guards_update_guards_in_state(or_state_t *state) +{ + if (!guard_contexts) + return; + config_line_t *lines = NULL; + config_line_t **nextline = &lines; + + SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) { + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + if (guard->is_persistent == 0) + continue; + *nextline = tor_malloc_zero(sizeof(config_line_t)); + (*nextline)->key = tor_strdup("Guard"); + (*nextline)->value = entry_guard_encode_for_state(guard); + nextline = &(*nextline)->next; + } SMARTLIST_FOREACH_END(guard); + } SMARTLIST_FOREACH_END(gs); + + config_free_lines(state->Guard); + state->Guard = lines; +} + +/** + * Replace our sampled guards from the Guards entries in <b>state</b>. Return 0 + * on success, -1 on failure. (If <b>set</b> is true, replace nothing -- only + * check whether replacing would work.) + */ +static int +entry_guards_load_guards_from_state(or_state_t *state, int set) +{ + const config_line_t *line = state->Guard; + int n_errors = 0; + + if (!guard_contexts) + guard_contexts = smartlist_new(); + + /* Wipe all our existing guard info. (we shouldn't have any, but + * let's be safe.) */ + if (set) { + SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) { + guard_selection_free(gs); + if (curr_guard_context == gs) + curr_guard_context = NULL; + SMARTLIST_DEL_CURRENT(guard_contexts, gs); + } SMARTLIST_FOREACH_END(gs); + } + + for ( ; line != NULL; line = line->next) { + entry_guard_t *guard = entry_guard_parse_from_state(line->value); + if (guard == NULL) { + ++n_errors; + continue; + } + tor_assert(guard->selection_name); + if (!strcmp(guard->selection_name, "legacy")) { + ++n_errors; + entry_guard_free(guard); + continue; + } + + if (set) { + guard_selection_t *gs; + gs = get_guard_selection_by_name(guard->selection_name, + GS_TYPE_INFER, 1); + tor_assert(gs); + smartlist_add(gs->sampled_entry_guards, guard); + guard->in_selection = gs; + } else { + entry_guard_free(guard); + } + } + + if (set) { + SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) { + entry_guards_update_all(gs); + } SMARTLIST_FOREACH_END(gs); + } + return n_errors ? -1 : 0; +} + +/** If <b>digest</b> matches the identity of any node in the + * entry_guards list for the provided guard selection state, + return that node. Else return NULL. */ +entry_guard_t * +entry_guard_get_by_id_digest_for_guard_selection(guard_selection_t *gs, + const char *digest) +{ + return get_sampled_guard_with_id(gs, (const uint8_t*)digest); +} + +/** Return the node_t associated with a single entry_guard_t. May + * return NULL if the guard is not currently in the consensus. */ +const node_t * +entry_guard_find_node(const entry_guard_t *guard) +{ + tor_assert(guard); + return node_get_by_id(guard->identity); +} + +/** If <b>digest</b> matches the identity of any node in the + * entry_guards list for the default guard selection state, + return that node. Else return NULL. */ +entry_guard_t * +entry_guard_get_by_id_digest(const char *digest) +{ + return entry_guard_get_by_id_digest_for_guard_selection( + get_guard_selection_info(), digest); +} + +/** We are about to connect to bridge with identity <b>digest</b> to fetch its + * descriptor. Create a new guard state for this connection and return it. */ +circuit_guard_state_t * +get_guard_state_for_bridge_desc_fetch(const char *digest) +{ + circuit_guard_state_t *guard_state = NULL; + entry_guard_t *guard = NULL; + + guard = entry_guard_get_by_id_digest_for_guard_selection( + get_guard_selection_info(), digest); + if (!guard) { + return NULL; + } + + /* Update the guard last_tried_to_connect time since it's checked by the + * guard susbsystem. */ + guard->last_tried_to_connect = approx_time(); + + /* Create the guard state */ + guard_state = circuit_guard_state_new(guard, + GUARD_CIRC_STATE_USABLE_ON_COMPLETION, + NULL); + + return guard_state; +} + +/** Release all storage held by <b>e</b>. */ +STATIC void +entry_guard_free_(entry_guard_t *e) +{ + if (!e) + return; + entry_guard_handles_clear(e); + tor_free(e->sampled_by_version); + tor_free(e->extra_state_fields); + tor_free(e->selection_name); + tor_free(e->bridge_addr); + tor_free(e); +} + +/** Return 0 if we're fine adding arbitrary routers out of the + * directory to our entry guard list, or return 1 if we have a + * list already and we must stick to it. + */ +int +entry_list_is_constrained(const or_options_t *options) +{ + // XXXX #21425 look at the current selection. + if (options->EntryNodes) + return 1; + if (options->UseBridges) + return 1; + return 0; +} + +/** Return the number of bridges that have descriptors that are marked with + * purpose 'bridge' and are running. If use_maybe_reachable is + * true, include bridges that might be reachable in the count. + * Otherwise, if it is false, only include bridges that have recently been + * found running in the count. + * + * We use this function to decide if we're ready to start building + * circuits through our bridges, or if we need to wait until the + * directory "server/authority" requests finish. */ +MOCK_IMPL(int, +num_bridges_usable,(int use_maybe_reachable)) +{ + int n_options = 0; + + if (BUG(!get_options()->UseBridges)) { + return 0; + } + guard_selection_t *gs = get_guard_selection_info(); + if (BUG(gs->type != GS_TYPE_BRIDGE)) { + return 0; + } + + SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) { + /* Definitely not usable */ + if (guard->is_reachable == GUARD_REACHABLE_NO) + continue; + /* If we want to be really sure the bridges will work, skip maybes */ + if (!use_maybe_reachable && guard->is_reachable == GUARD_REACHABLE_MAYBE) + continue; + if (tor_digest_is_zero(guard->identity)) + continue; + const node_t *node = node_get_by_id(guard->identity); + if (node && node->ri) + ++n_options; + } SMARTLIST_FOREACH_END(guard); + + return n_options; +} + +/** Check the pathbias use success count of <b>node</b> and disable it if it + * goes over our thresholds. */ +static void +pathbias_check_use_success_count(entry_guard_t *node) +{ + const or_options_t *options = get_options(); + const double EPSILON = 1.0e-9; + + /* Note: We rely on the < comparison here to allow us to set a 0 + * rate and disable the feature entirely. If refactoring, don't + * change to <= */ + if (node->pb.use_attempts > EPSILON && + pathbias_get_use_success_count(node)/node->pb.use_attempts + < pathbias_get_extreme_use_rate(options) && + pathbias_get_dropguards(options)) { + node->pb.path_bias_disabled = 1; + log_info(LD_GENERAL, + "Path use bias is too high (%f/%f); disabling node %s", + node->pb.circ_successes, node->pb.circ_attempts, + node->nickname); + } +} + +/** Check the pathbias close count of <b>node</b> and disable it if it goes + * over our thresholds. */ +static void +pathbias_check_close_success_count(entry_guard_t *node) +{ + const or_options_t *options = get_options(); + const double EPSILON = 1.0e-9; + + /* Note: We rely on the < comparison here to allow us to set a 0 + * rate and disable the feature entirely. If refactoring, don't + * change to <= */ + if (node->pb.circ_attempts > EPSILON && + pathbias_get_close_success_count(node)/node->pb.circ_attempts + < pathbias_get_extreme_rate(options) && + pathbias_get_dropguards(options)) { + node->pb.path_bias_disabled = 1; + log_info(LD_GENERAL, + "Path bias is too high (%f/%f); disabling node %s", + node->pb.circ_successes, node->pb.circ_attempts, + node->nickname); + } +} + +/** Parse <b>state</b> and learn about the entry guards it describes. + * If <b>set</b> is true, and there are no errors, replace the guard + * list in the default guard selection context with what we find. + * On success, return 0. On failure, alloc into *<b>msg</b> a string + * describing the error, and return -1. + */ +int +entry_guards_parse_state(or_state_t *state, int set, char **msg) +{ + entry_guards_dirty = 0; + int r1 = entry_guards_load_guards_from_state(state, set); + entry_guards_dirty = 0; + + if (r1 < 0) { + if (msg && *msg == NULL) { + *msg = tor_strdup("parsing error"); + } + return -1; + } + return 0; +} + +/** How long will we let a change in our guard nodes stay un-saved + * when we are trying to avoid disk writes? */ +#define SLOW_GUARD_STATE_FLUSH_TIME 600 +/** How long will we let a change in our guard nodes stay un-saved + * when we are not trying to avoid disk writes? */ +#define FAST_GUARD_STATE_FLUSH_TIME 30 + +/** Our list of entry guards has changed for a particular guard selection + * context, or some element of one of our entry guards has changed for one. + * Write the changes to disk within the next few minutes. + */ +void +entry_guards_changed_for_guard_selection(guard_selection_t *gs) +{ + time_t when; + + tor_assert(gs != NULL); + + entry_guards_dirty = 1; + + if (get_options()->AvoidDiskWrites) + when = time(NULL) + SLOW_GUARD_STATE_FLUSH_TIME; + else + when = time(NULL) + FAST_GUARD_STATE_FLUSH_TIME; + + /* or_state_save() will call entry_guards_update_state() and + entry_guards_update_guards_in_state() + */ + or_state_mark_dirty(get_or_state(), when); +} + +/** Our list of entry guards has changed for the default guard selection + * context, or some element of one of our entry guards has changed. Write + * the changes to disk within the next few minutes. + */ +void +entry_guards_changed(void) +{ + entry_guards_changed_for_guard_selection(get_guard_selection_info()); +} + +/** If the entry guard info has not changed, do nothing and return. + * Otherwise, free the EntryGuards piece of <b>state</b> and create + * a new one out of the global entry_guards list, and then mark + * <b>state</b> dirty so it will get saved to disk. + */ +void +entry_guards_update_state(or_state_t *state) +{ + entry_guards_dirty = 0; + + // Handles all guard info. + entry_guards_update_guards_in_state(state); + + entry_guards_dirty = 0; + + if (!get_options()->AvoidDiskWrites) + or_state_mark_dirty(get_or_state(), 0); + entry_guards_dirty = 0; +} + +/** Return true iff the circuit's guard can succeed that is can be used. */ +int +entry_guard_could_succeed(const circuit_guard_state_t *guard_state) +{ + if (!guard_state) { + return 0; + } + + entry_guard_t *guard = entry_guard_handle_get(guard_state->guard); + if (!guard || BUG(guard->in_selection == NULL)) { + return 0; + } + + return 1; +} + +/** + * Format a single entry guard in the format expected by the controller. + * Return a newly allocated string. + */ +STATIC char * +getinfo_helper_format_single_entry_guard(const entry_guard_t *e) +{ + const char *status = NULL; + time_t when = 0; + const node_t *node; + char tbuf[ISO_TIME_LEN+1]; + char nbuf[MAX_VERBOSE_NICKNAME_LEN+1]; + + /* This is going to be a bit tricky, since the status + * codes weren't really intended for prop271 guards. + * + * XXXX use a more appropriate format for exporting this information + */ + if (e->confirmed_idx < 0) { + status = "never-connected"; + } else if (! e->currently_listed) { + when = e->unlisted_since_date; + status = "unusable"; + } else if (! e->is_filtered_guard) { + status = "unusable"; + } else if (e->is_reachable == GUARD_REACHABLE_NO) { + when = e->failing_since; + status = "down"; + } else { + status = "up"; + } + + node = entry_guard_find_node(e); + if (node) { + node_get_verbose_nickname(node, nbuf); + } else { + nbuf[0] = '$'; + base16_encode(nbuf+1, sizeof(nbuf)-1, e->identity, DIGEST_LEN); + /* e->nickname field is not very reliable if we don't know about + * this router any longer; don't include it. */ + } + + char *result = NULL; + if (when) { + format_iso_time(tbuf, when); + tor_asprintf(&result, "%s %s %s\n", nbuf, status, tbuf); + } else { + tor_asprintf(&result, "%s %s\n", nbuf, status); + } + return result; +} + +/** If <b>question</b> is the string "entry-guards", then dump + * to *<b>answer</b> a newly allocated string describing all of + * the nodes in the global entry_guards list. See control-spec.txt + * for details. + * For backward compatibility, we also handle the string "helper-nodes". + * + * XXX this should be totally redesigned after prop 271 too, and that's + * going to take some control spec work. + * */ +int +getinfo_helper_entry_guards(control_connection_t *conn, + const char *question, char **answer, + const char **errmsg) +{ + guard_selection_t *gs = get_guard_selection_info(); + + tor_assert(gs != NULL); + + (void) conn; + (void) errmsg; + + if (!strcmp(question,"entry-guards") || + !strcmp(question,"helper-nodes")) { + const smartlist_t *guards; + guards = gs->sampled_entry_guards; + + smartlist_t *sl = smartlist_new(); + + SMARTLIST_FOREACH_BEGIN(guards, const entry_guard_t *, e) { + char *cp = getinfo_helper_format_single_entry_guard(e); + smartlist_add(sl, cp); + } SMARTLIST_FOREACH_END(e); + *answer = smartlist_join_strings(sl, "", 0, NULL); + SMARTLIST_FOREACH(sl, char *, c, tor_free(c)); + smartlist_free(sl); + } + return 0; +} + +/* Given the original bandwidth of a guard and its guardfraction, + * calculate how much bandwidth the guard should have as a guard and + * as a non-guard. + * + * Quoting from proposal236: + * + * Let Wpf denote the weight from the 'bandwidth-weights' line a + * client would apply to N for position p if it had the guard + * flag, Wpn the weight if it did not have the guard flag, and B the + * measured bandwidth of N in the consensus. Then instead of choosing + * N for position p proportionally to Wpf*B or Wpn*B, clients should + * choose N proportionally to F*Wpf*B + (1-F)*Wpn*B. + * + * This function fills the <b>guardfraction_bw</b> structure. It sets + * <b>guard_bw</b> to F*B and <b>non_guard_bw</b> to (1-F)*B. + */ +void +guard_get_guardfraction_bandwidth(guardfraction_bandwidth_t *guardfraction_bw, + int orig_bandwidth, + uint32_t guardfraction_percentage) +{ + double guardfraction_fraction; + + /* Turn the percentage into a fraction. */ + tor_assert(guardfraction_percentage <= 100); + guardfraction_fraction = guardfraction_percentage / 100.0; + + long guard_bw = tor_lround(guardfraction_fraction * orig_bandwidth); + tor_assert(guard_bw <= INT_MAX); + + guardfraction_bw->guard_bw = (int) guard_bw; + + guardfraction_bw->non_guard_bw = orig_bandwidth - (int) guard_bw; +} + +/** Helper: Update the status of all entry guards, in whatever algorithm + * is used. Return true if we should stop using all previously generated + * circuits, by calling circuit_mark_all_unused_circs() and + * circuit_mark_all_dirty_circs_as_unusable(). + */ +int +guards_update_all(void) +{ + int mark_circuits = 0; + if (update_guard_selection_choice(get_options())) + mark_circuits = 1; + + tor_assert(curr_guard_context); + + if (entry_guards_update_all(curr_guard_context)) + mark_circuits = 1; + + return mark_circuits; +} + +/** Helper: pick a guard for a circuit, with whatever algorithm is + used. */ +const node_t * +guards_choose_guard(cpath_build_state_t *state, + uint8_t purpose, + circuit_guard_state_t **guard_state_out) +{ + const node_t *r = NULL; + const uint8_t *exit_id = NULL; + entry_guard_restriction_t *rst = NULL; + + /* Only apply restrictions if we have a specific exit node in mind, and only + * if we are not doing vanguard circuits: we don't want to apply guard + * restrictions to vanguard circuits. */ + if (state && !circuit_should_use_vanguards(purpose) && + (exit_id = build_state_get_exit_rsa_id(state))) { + /* We're building to a targeted exit node, so that node can't be + * chosen as our guard for this circuit. Remember that fact in a + * restriction. */ + rst = guard_create_exit_restriction(exit_id); + tor_assert(rst); + } + if (entry_guard_pick_for_circuit(get_guard_selection_info(), + GUARD_USAGE_TRAFFIC, + rst, + &r, + guard_state_out) < 0) { + tor_assert(r == NULL); + } + return r; +} + +/** Remove all currently listed entry guards for a given guard selection + * context. This frees and replaces <b>gs</b>, so don't use <b>gs</b> + * after calling this function. */ +void +remove_all_entry_guards_for_guard_selection(guard_selection_t *gs) +{ + // This function shouldn't exist. XXXX + tor_assert(gs != NULL); + char *old_name = tor_strdup(gs->name); + guard_selection_type_t old_type = gs->type; + + SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, entry, { + control_event_guard(entry->nickname, entry->identity, "DROPPED"); + }); + + if (gs == curr_guard_context) { + curr_guard_context = NULL; + } + + smartlist_remove(guard_contexts, gs); + guard_selection_free(gs); + + gs = get_guard_selection_by_name(old_name, old_type, 1); + entry_guards_changed_for_guard_selection(gs); + tor_free(old_name); +} + +/** Remove all currently listed entry guards, so new ones will be chosen. + * + * XXXX This function shouldn't exist -- it's meant to support the DROPGUARDS + * command, which is deprecated. + */ +void +remove_all_entry_guards(void) +{ + remove_all_entry_guards_for_guard_selection(get_guard_selection_info()); +} + +/** Helper: pick a directory guard, with whatever algorithm is used. */ +const node_t * +guards_choose_dirguard(uint8_t dir_purpose, + circuit_guard_state_t **guard_state_out) +{ + const node_t *r = NULL; + entry_guard_restriction_t *rst = NULL; + + /* If we are fetching microdescs, don't query outdated dirservers. */ + if (dir_purpose == DIR_PURPOSE_FETCH_MICRODESC) { + rst = guard_create_dirserver_md_restriction(); + } + + if (entry_guard_pick_for_circuit(get_guard_selection_info(), + GUARD_USAGE_DIRGUARD, + rst, + &r, + guard_state_out) < 0) { + tor_assert(r == NULL); + } + return r; +} + +/** + * If we're running with a constrained guard set, then maybe mark our guards + * usable. Return 1 if we do; 0 if we don't. + */ +int +guards_retry_optimistic(const or_options_t *options) +{ + if (! entry_list_is_constrained(options)) + return 0; + + mark_primary_guards_maybe_reachable(get_guard_selection_info()); + + return 1; +} + +/** + * Check if we are missing any crucial dirinfo for the guard subsystem to + * work. Return NULL if everything went well, otherwise return a newly + * allocated string with an informative error message. In the latter case, use + * the genreal descriptor information <b>using_mds</b>, <b>num_present</b> and + * <b>num_usable</b> to improve the error message. */ +char * +guard_selection_get_err_str_if_dir_info_missing(guard_selection_t *gs, + int using_mds, + int num_present, int num_usable) +{ + if (!gs->primary_guards_up_to_date) + entry_guards_update_primary(gs); + + char *ret_str = NULL; + int n_missing_descriptors = 0; + int n_considered = 0; + int num_primary_to_check; + + /* We want to check for the descriptor of at least the first two primary + * guards in our list, since these are the guards that we typically use for + * circuits. */ + num_primary_to_check = get_n_primary_guards_to_use(GUARD_USAGE_TRAFFIC); + num_primary_to_check++; + + SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) { + entry_guard_consider_retry(guard); + if (guard->is_reachable == GUARD_REACHABLE_NO) + continue; + n_considered++; + if (!guard_has_descriptor(guard)) + n_missing_descriptors++; + if (n_considered >= num_primary_to_check) + break; + } SMARTLIST_FOREACH_END(guard); + + /* If we are not missing any descriptors, return NULL. */ + if (!n_missing_descriptors) { + return NULL; + } + + /* otherwise return a helpful error string */ + tor_asprintf(&ret_str, "We're missing descriptors for %d/%d of our " + "primary entry guards (total %sdescriptors: %d/%d).", + n_missing_descriptors, num_primary_to_check, + using_mds?"micro":"", num_present, num_usable); + + return ret_str; +} + +/** As guard_selection_have_enough_dir_info_to_build_circuits, but uses + * the default guard selection. */ +char * +entry_guards_get_err_str_if_dir_info_missing(int using_mds, + int num_present, int num_usable) +{ + return guard_selection_get_err_str_if_dir_info_missing( + get_guard_selection_info(), + using_mds, + num_present, num_usable); +} + +/** Free one guard selection context */ +STATIC void +guard_selection_free_(guard_selection_t *gs) +{ + if (!gs) return; + + tor_free(gs->name); + + if (gs->sampled_entry_guards) { + SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, e, + entry_guard_free(e)); + smartlist_free(gs->sampled_entry_guards); + gs->sampled_entry_guards = NULL; + } + + smartlist_free(gs->confirmed_entry_guards); + smartlist_free(gs->primary_entry_guards); + + tor_free(gs); +} + +/** Release all storage held by the list of entry guards and related + * memory structs. */ +void +entry_guards_free_all(void) +{ + /* Null out the default */ + curr_guard_context = NULL; + /* Free all the guard contexts */ + if (guard_contexts != NULL) { + SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) { + guard_selection_free(gs); + } SMARTLIST_FOREACH_END(gs); + smartlist_free(guard_contexts); + guard_contexts = NULL; + } + circuit_build_times_free_timeouts(get_circuit_build_times_mutable()); +} |