entrynodes.c 125 KB

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  1. /* Copyright (c) 2001 Matej Pfajfar.
  2. * Copyright (c) 2001-2004, Roger Dingledine.
  3. * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
  4. * Copyright (c) 2007-2019, The Tor Project, Inc. */
  5. /* See LICENSE for licensing information */
  6. /**
  7. * \file entrynodes.c
  8. * \brief Code to manage our fixed first nodes for various functions.
  9. *
  10. * Entry nodes can be guards (for general use) or bridges (for censorship
  11. * circumvention).
  12. *
  13. * In general, we use entry guards to prevent traffic-sampling attacks:
  14. * if we chose every circuit independently, an adversary controlling
  15. * some fraction of paths on the network would observe a sample of every
  16. * user's traffic. Using guards gives users a chance of not being
  17. * profiled.
  18. *
  19. * The current entry guard selection code is designed to try to avoid
  20. * _ever_ trying every guard on the network, to try to stick to guards
  21. * that we've used before, to handle hostile/broken networks, and
  22. * to behave sanely when the network goes up and down.
  23. *
  24. * Our algorithm works as follows: First, we maintain a SAMPLE of guards
  25. * we've seen in the networkstatus consensus. We maintain this sample
  26. * over time, and store it persistently; it is chosen without reference
  27. * to our configuration or firewall rules. Guards remain in the sample
  28. * as they enter and leave the consensus. We expand this sample as
  29. * needed, up to a maximum size.
  30. *
  31. * As a subset of the sample, we maintain a FILTERED SET of the guards
  32. * that we would be willing to use if we could connect to them. The
  33. * filter removes all the guards that we're excluding because they're
  34. * bridges (or not bridges), because we have restrictive firewall rules,
  35. * because of ExcludeNodes, because we of path bias restrictions,
  36. * because they're absent from the network at present, and so on.
  37. *
  38. * As a subset of the filtered set, we keep a REACHABLE FILTERED SET
  39. * (also called a "usable filtered set") of those guards that we call
  40. * "reachable" or "maybe reachable". A guard is reachable if we've
  41. * connected to it more recently than we've failed. A guard is "maybe
  42. * reachable" if we have never tried to connect to it, or if we
  43. * failed to connect to it so long ago that we no longer think our
  44. * failure means it's down.
  45. *
  46. * As a persistent ordered list whose elements are taken from the
  47. * sampled set, we track a CONFIRMED GUARDS LIST. A guard becomes
  48. * confirmed when we successfully build a circuit through it, and decide
  49. * to use that circuit. We order the guards on this list by the order
  50. * in which they became confirmed.
  51. *
  52. * And as a final group, we have an ordered list of PRIMARY GUARDS,
  53. * whose elements are taken from the filtered set. We prefer
  54. * confirmed guards to non-confirmed guards for this list, and place
  55. * other restrictions on it. The primary guards are the ones that we
  56. * connect to "when nothing is wrong" -- circuits through them can be used
  57. * immediately.
  58. *
  59. * To build circuits, we take a primary guard if possible -- or a
  60. * reachable filtered confirmed guard if no primary guard is possible --
  61. * or a random reachable filtered guard otherwise. If the guard is
  62. * primary, we can use the circuit immediately on success. Otherwise,
  63. * the guard is now "pending" -- we won't use its circuit unless all
  64. * of the circuits we're trying to build through better guards have
  65. * definitely failed.
  66. *
  67. * While we're building circuits, we track a little "guard state" for
  68. * each circuit. We use this to keep track of whether the circuit is
  69. * one that we can use as soon as it's done, or whether it's one that
  70. * we should keep around to see if we can do better. In the latter case,
  71. * a periodic call to entry_guards_upgrade_waiting_circuits() will
  72. * eventually upgrade it.
  73. **/
  74. /* DOCDOC -- expand this.
  75. *
  76. * Information invariants:
  77. *
  78. * [x] whenever a guard becomes unreachable, clear its usable_filtered flag.
  79. *
  80. * [x] Whenever a guard becomes reachable or maybe-reachable, if its filtered
  81. * flag is set, set its usable_filtered flag.
  82. *
  83. * [x] Whenever we get a new consensus, call update_from_consensus(). (LATER.)
  84. *
  85. * [x] Whenever the configuration changes in a relevant way, update the
  86. * filtered/usable flags. (LATER.)
  87. *
  88. * [x] Whenever we add a guard to the sample, make sure its filtered/usable
  89. * flags are set as possible.
  90. *
  91. * [x] Whenever we remove a guard from the sample, remove it from the primary
  92. * and confirmed lists.
  93. *
  94. * [x] When we make a guard confirmed, update the primary list.
  95. *
  96. * [x] When we make a guard filtered or unfiltered, update the primary list.
  97. *
  98. * [x] When we are about to pick a guard, make sure that the primary list is
  99. * full.
  100. *
  101. * [x] Before calling sample_reachable_filtered_entry_guards(), make sure
  102. * that the filtered, primary, and confirmed flags are up-to-date.
  103. *
  104. * [x] Call entry_guard_consider_retry every time we are about to check
  105. * is_usable_filtered or is_reachable, and every time we set
  106. * is_filtered to 1.
  107. *
  108. * [x] Call entry_guards_changed_for_guard_selection() whenever we update
  109. * a persistent field.
  110. */
  111. #define ENTRYNODES_PRIVATE
  112. #include "core/or/or.h"
  113. #include "app/config/config.h"
  114. #include "app/config/confparse.h"
  115. #include "app/config/statefile.h"
  116. #include "core/mainloop/connection.h"
  117. #include "core/mainloop/mainloop.h"
  118. #include "core/or/channel.h"
  119. #include "core/or/circuitbuild.h"
  120. #include "core/or/circuitlist.h"
  121. #include "core/or/circuitstats.h"
  122. #include "core/or/circuituse.h"
  123. #include "core/or/policies.h"
  124. #include "feature/client/bridges.h"
  125. #include "feature/client/circpathbias.h"
  126. #include "feature/client/entrynodes.h"
  127. #include "feature/client/transports.h"
  128. #include "feature/control/control_events.h"
  129. #include "feature/dircommon/directory.h"
  130. #include "feature/nodelist/describe.h"
  131. #include "feature/nodelist/microdesc.h"
  132. #include "feature/nodelist/networkstatus.h"
  133. #include "feature/nodelist/nickname.h"
  134. #include "feature/nodelist/nodelist.h"
  135. #include "feature/nodelist/node_select.h"
  136. #include "feature/nodelist/routerset.h"
  137. #include "feature/relay/router.h"
  138. #include "lib/crypt_ops/crypto_rand.h"
  139. #include "lib/crypt_ops/digestset.h"
  140. #include "lib/encoding/confline.h"
  141. #include "lib/math/fp.h"
  142. #include "feature/nodelist/node_st.h"
  143. #include "core/or/origin_circuit_st.h"
  144. #include "app/config/or_state_st.h"
  145. /** A list of existing guard selection contexts. */
  146. static smartlist_t *guard_contexts = NULL;
  147. /** The currently enabled guard selection context. */
  148. static guard_selection_t *curr_guard_context = NULL;
  149. /** A value of 1 means that at least one context has changed,
  150. * and those changes need to be flushed to disk. */
  151. static int entry_guards_dirty = 0;
  152. static void entry_guard_set_filtered_flags(const or_options_t *options,
  153. guard_selection_t *gs,
  154. entry_guard_t *guard);
  155. static void pathbias_check_use_success_count(entry_guard_t *guard);
  156. static void pathbias_check_close_success_count(entry_guard_t *guard);
  157. static int node_is_possible_guard(const node_t *node);
  158. static int node_passes_guard_filter(const or_options_t *options,
  159. const node_t *node);
  160. static entry_guard_t *entry_guard_add_to_sample_impl(guard_selection_t *gs,
  161. const uint8_t *rsa_id_digest,
  162. const char *nickname,
  163. const tor_addr_port_t *bridge_addrport);
  164. static entry_guard_t *get_sampled_guard_by_bridge_addr(guard_selection_t *gs,
  165. const tor_addr_port_t *addrport);
  166. static int entry_guard_obeys_restriction(const entry_guard_t *guard,
  167. const entry_guard_restriction_t *rst);
  168. /** Return 0 if we should apply guardfraction information found in the
  169. * consensus. A specific consensus can be specified with the
  170. * <b>ns</b> argument, if NULL the most recent one will be picked.*/
  171. int
  172. should_apply_guardfraction(const networkstatus_t *ns)
  173. {
  174. /* We need to check the corresponding torrc option and the consensus
  175. * parameter if we need to. */
  176. const or_options_t *options = get_options();
  177. /* If UseGuardFraction is 'auto' then check the same-named consensus
  178. * parameter. If the consensus parameter is not present, default to
  179. * "off". */
  180. if (options->UseGuardFraction == -1) {
  181. return networkstatus_get_param(ns, "UseGuardFraction",
  182. 0, /* default to "off" */
  183. 0, 1);
  184. }
  185. return options->UseGuardFraction;
  186. }
  187. /** Return true iff we know a preferred descriptor for <b>guard</b> */
  188. static int
  189. guard_has_descriptor(const entry_guard_t *guard)
  190. {
  191. const node_t *node = node_get_by_id(guard->identity);
  192. if (!node)
  193. return 0;
  194. return node_has_preferred_descriptor(node, 1);
  195. }
  196. /**
  197. * Try to determine the correct type for a selection named "name",
  198. * if <b>type</b> is GS_TYPE_INFER.
  199. */
  200. STATIC guard_selection_type_t
  201. guard_selection_infer_type(guard_selection_type_t type,
  202. const char *name)
  203. {
  204. if (type == GS_TYPE_INFER) {
  205. if (!strcmp(name, "bridges"))
  206. type = GS_TYPE_BRIDGE;
  207. else if (!strcmp(name, "restricted"))
  208. type = GS_TYPE_RESTRICTED;
  209. else
  210. type = GS_TYPE_NORMAL;
  211. }
  212. return type;
  213. }
  214. /**
  215. * Allocate and return a new guard_selection_t, with the name <b>name</b>.
  216. */
  217. STATIC guard_selection_t *
  218. guard_selection_new(const char *name,
  219. guard_selection_type_t type)
  220. {
  221. guard_selection_t *gs;
  222. type = guard_selection_infer_type(type, name);
  223. gs = tor_malloc_zero(sizeof(*gs));
  224. gs->name = tor_strdup(name);
  225. gs->type = type;
  226. gs->sampled_entry_guards = smartlist_new();
  227. gs->confirmed_entry_guards = smartlist_new();
  228. gs->primary_entry_guards = smartlist_new();
  229. return gs;
  230. }
  231. /**
  232. * Return the guard selection called <b>name</b>. If there is none, and
  233. * <b>create_if_absent</b> is true, then create and return it. If there
  234. * is none, and <b>create_if_absent</b> is false, then return NULL.
  235. */
  236. STATIC guard_selection_t *
  237. get_guard_selection_by_name(const char *name,
  238. guard_selection_type_t type,
  239. int create_if_absent)
  240. {
  241. if (!guard_contexts) {
  242. guard_contexts = smartlist_new();
  243. }
  244. SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
  245. if (!strcmp(gs->name, name))
  246. return gs;
  247. } SMARTLIST_FOREACH_END(gs);
  248. if (! create_if_absent)
  249. return NULL;
  250. log_debug(LD_GUARD, "Creating a guard selection called %s", name);
  251. guard_selection_t *new_selection = guard_selection_new(name, type);
  252. smartlist_add(guard_contexts, new_selection);
  253. return new_selection;
  254. }
  255. /**
  256. * Allocate the first guard context that we're planning to use,
  257. * and make it the current context.
  258. */
  259. static void
  260. create_initial_guard_context(void)
  261. {
  262. tor_assert(! curr_guard_context);
  263. if (!guard_contexts) {
  264. guard_contexts = smartlist_new();
  265. }
  266. guard_selection_type_t type = GS_TYPE_INFER;
  267. const char *name = choose_guard_selection(
  268. get_options(),
  269. networkstatus_get_reasonably_live_consensus(
  270. approx_time(),
  271. usable_consensus_flavor()),
  272. NULL,
  273. &type);
  274. tor_assert(name); // "name" can only be NULL if we had an old name.
  275. tor_assert(type != GS_TYPE_INFER);
  276. log_notice(LD_GUARD, "Starting with guard context \"%s\"", name);
  277. curr_guard_context = get_guard_selection_by_name(name, type, 1);
  278. }
  279. /** Get current default guard_selection_t, creating it if necessary */
  280. guard_selection_t *
  281. get_guard_selection_info(void)
  282. {
  283. if (!curr_guard_context) {
  284. create_initial_guard_context();
  285. }
  286. return curr_guard_context;
  287. }
  288. /** Return a statically allocated human-readable description of <b>guard</b>
  289. */
  290. const char *
  291. entry_guard_describe(const entry_guard_t *guard)
  292. {
  293. static char buf[256];
  294. tor_snprintf(buf, sizeof(buf),
  295. "%s ($%s)",
  296. strlen(guard->nickname) ? guard->nickname : "[bridge]",
  297. hex_str(guard->identity, DIGEST_LEN));
  298. return buf;
  299. }
  300. /** Return <b>guard</b>'s 20-byte RSA identity digest */
  301. const char *
  302. entry_guard_get_rsa_id_digest(const entry_guard_t *guard)
  303. {
  304. return guard->identity;
  305. }
  306. /** Return the pathbias state associated with <b>guard</b>. */
  307. guard_pathbias_t *
  308. entry_guard_get_pathbias_state(entry_guard_t *guard)
  309. {
  310. return &guard->pb;
  311. }
  312. HANDLE_IMPL(entry_guard, entry_guard_t, ATTR_UNUSED STATIC)
  313. /** Return an interval betweeen 'now' and 'max_backdate' seconds in the past,
  314. * chosen uniformly at random. We use this before recording persistent
  315. * dates, so that we aren't leaking exactly when we recorded it.
  316. */
  317. MOCK_IMPL(STATIC time_t,
  318. randomize_time,(time_t now, time_t max_backdate))
  319. {
  320. tor_assert(max_backdate > 0);
  321. time_t earliest = now - max_backdate;
  322. time_t latest = now;
  323. if (earliest <= 0)
  324. earliest = 1;
  325. if (latest <= earliest)
  326. latest = earliest + 1;
  327. return crypto_rand_time_range(earliest, latest);
  328. }
  329. /**
  330. * @name parameters for networkstatus algorithm
  331. *
  332. * These parameters are taken from the consensus; some are overrideable in
  333. * the torrc.
  334. */
  335. /**@{*/
  336. /**
  337. * We never let our sampled guard set grow larger than this fraction
  338. * of the guards on the network.
  339. */
  340. STATIC double
  341. get_max_sample_threshold(void)
  342. {
  343. int32_t pct =
  344. networkstatus_get_param(NULL, "guard-max-sample-threshold-percent",
  345. DFLT_MAX_SAMPLE_THRESHOLD_PERCENT,
  346. 1, 100);
  347. return pct / 100.0;
  348. }
  349. /**
  350. * We never let our sampled guard set grow larger than this number.
  351. */
  352. STATIC int
  353. get_max_sample_size_absolute(void)
  354. {
  355. return (int) networkstatus_get_param(NULL, "guard-max-sample-size",
  356. DFLT_MAX_SAMPLE_SIZE,
  357. 1, INT32_MAX);
  358. }
  359. /**
  360. * We always try to make our sample contain at least this many guards.
  361. */
  362. STATIC int
  363. get_min_filtered_sample_size(void)
  364. {
  365. return networkstatus_get_param(NULL, "guard-min-filtered-sample-size",
  366. DFLT_MIN_FILTERED_SAMPLE_SIZE,
  367. 1, INT32_MAX);
  368. }
  369. /**
  370. * If a guard is unlisted for this many days in a row, we remove it.
  371. */
  372. STATIC int
  373. get_remove_unlisted_guards_after_days(void)
  374. {
  375. return networkstatus_get_param(NULL,
  376. "guard-remove-unlisted-guards-after-days",
  377. DFLT_REMOVE_UNLISTED_GUARDS_AFTER_DAYS,
  378. 1, 365*10);
  379. }
  380. /**
  381. * Return number of seconds that will make a guard no longer eligible
  382. * for selection if unlisted for this long.
  383. */
  384. static time_t
  385. get_remove_unlisted_guards_after_seconds(void)
  386. {
  387. return get_remove_unlisted_guards_after_days() * 24 * 60 * 60;
  388. }
  389. /**
  390. * We remove unconfirmed guards from the sample after this many days,
  391. * regardless of whether they are listed or unlisted.
  392. */
  393. STATIC int
  394. get_guard_lifetime(void)
  395. {
  396. if (get_options()->GuardLifetime >= 86400)
  397. return get_options()->GuardLifetime;
  398. int32_t days;
  399. days = networkstatus_get_param(NULL,
  400. "guard-lifetime-days",
  401. DFLT_GUARD_LIFETIME_DAYS, 1, 365*10);
  402. return days * 86400;
  403. }
  404. /**
  405. * We remove confirmed guards from the sample if they were sampled
  406. * GUARD_LIFETIME_DAYS ago and confirmed this many days ago.
  407. */
  408. STATIC int
  409. get_guard_confirmed_min_lifetime(void)
  410. {
  411. if (get_options()->GuardLifetime >= 86400)
  412. return get_options()->GuardLifetime;
  413. int32_t days;
  414. days = networkstatus_get_param(NULL, "guard-confirmed-min-lifetime-days",
  415. DFLT_GUARD_CONFIRMED_MIN_LIFETIME_DAYS,
  416. 1, 365*10);
  417. return days * 86400;
  418. }
  419. /**
  420. * How many guards do we try to keep on our primary guard list?
  421. */
  422. STATIC int
  423. get_n_primary_guards(void)
  424. {
  425. /* If the user has explicitly configured the number of primary guards, do
  426. * what the user wishes to do */
  427. const int configured_primaries = get_options()->NumPrimaryGuards;
  428. if (configured_primaries) {
  429. return configured_primaries;
  430. }
  431. /* otherwise check for consensus parameter and if that's not set either, just
  432. * use the default value. */
  433. return networkstatus_get_param(NULL,
  434. "guard-n-primary-guards",
  435. DFLT_N_PRIMARY_GUARDS, 1, INT32_MAX);
  436. }
  437. /**
  438. * Return the number of the live primary guards we should look at when
  439. * making a circuit.
  440. */
  441. STATIC int
  442. get_n_primary_guards_to_use(guard_usage_t usage)
  443. {
  444. int configured;
  445. const char *param_name;
  446. int param_default;
  447. /* If the user has explicitly configured the amount of guards, use
  448. that. Otherwise, fall back to the default value. */
  449. if (usage == GUARD_USAGE_DIRGUARD) {
  450. configured = get_options()->NumDirectoryGuards;
  451. param_name = "guard-n-primary-dir-guards-to-use";
  452. param_default = DFLT_N_PRIMARY_DIR_GUARDS_TO_USE;
  453. } else {
  454. configured = get_options()->NumEntryGuards;
  455. param_name = "guard-n-primary-guards-to-use";
  456. param_default = DFLT_N_PRIMARY_GUARDS_TO_USE;
  457. }
  458. if (configured >= 1) {
  459. return configured;
  460. }
  461. return networkstatus_get_param(NULL,
  462. param_name, param_default, 1, INT32_MAX);
  463. }
  464. /**
  465. * If we haven't successfully built or used a circuit in this long, then
  466. * consider that the internet is probably down.
  467. */
  468. STATIC int
  469. get_internet_likely_down_interval(void)
  470. {
  471. return networkstatus_get_param(NULL, "guard-internet-likely-down-interval",
  472. DFLT_INTERNET_LIKELY_DOWN_INTERVAL,
  473. 1, INT32_MAX);
  474. }
  475. /**
  476. * If we're trying to connect to a nonprimary guard for at least this
  477. * many seconds, and we haven't gotten the connection to work, we will treat
  478. * lower-priority guards as usable.
  479. */
  480. STATIC int
  481. get_nonprimary_guard_connect_timeout(void)
  482. {
  483. return networkstatus_get_param(NULL,
  484. "guard-nonprimary-guard-connect-timeout",
  485. DFLT_NONPRIMARY_GUARD_CONNECT_TIMEOUT,
  486. 1, INT32_MAX);
  487. }
  488. /**
  489. * If a circuit has been sitting around in 'waiting for better guard' state
  490. * for at least this long, we'll expire it.
  491. */
  492. STATIC int
  493. get_nonprimary_guard_idle_timeout(void)
  494. {
  495. return networkstatus_get_param(NULL,
  496. "guard-nonprimary-guard-idle-timeout",
  497. DFLT_NONPRIMARY_GUARD_IDLE_TIMEOUT,
  498. 1, INT32_MAX);
  499. }
  500. /**
  501. * If our configuration retains fewer than this fraction of guards from the
  502. * torrc, we are in a restricted setting.
  503. */
  504. STATIC double
  505. get_meaningful_restriction_threshold(void)
  506. {
  507. int32_t pct = networkstatus_get_param(NULL,
  508. "guard-meaningful-restriction-percent",
  509. DFLT_MEANINGFUL_RESTRICTION_PERCENT,
  510. 1, INT32_MAX);
  511. return pct / 100.0;
  512. }
  513. /**
  514. * If our configuration retains fewer than this fraction of guards from the
  515. * torrc, we are in an extremely restricted setting, and should warn.
  516. */
  517. STATIC double
  518. get_extreme_restriction_threshold(void)
  519. {
  520. int32_t pct = networkstatus_get_param(NULL,
  521. "guard-extreme-restriction-percent",
  522. DFLT_EXTREME_RESTRICTION_PERCENT,
  523. 1, INT32_MAX);
  524. return pct / 100.0;
  525. }
  526. /* Mark <b>guard</b> as maybe reachable again. */
  527. static void
  528. mark_guard_maybe_reachable(entry_guard_t *guard)
  529. {
  530. if (guard->is_reachable != GUARD_REACHABLE_NO) {
  531. return;
  532. }
  533. /* Note that we do not clear failing_since: this guard is now only
  534. * _maybe-reachable_. */
  535. guard->is_reachable = GUARD_REACHABLE_MAYBE;
  536. if (guard->is_filtered_guard)
  537. guard->is_usable_filtered_guard = 1;
  538. }
  539. /**
  540. * Called when the network comes up after having seemed to be down for
  541. * a while: Mark the primary guards as maybe-reachable so that we'll
  542. * try them again.
  543. */
  544. STATIC void
  545. mark_primary_guards_maybe_reachable(guard_selection_t *gs)
  546. {
  547. tor_assert(gs);
  548. if (!gs->primary_guards_up_to_date)
  549. entry_guards_update_primary(gs);
  550. SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) {
  551. mark_guard_maybe_reachable(guard);
  552. } SMARTLIST_FOREACH_END(guard);
  553. }
  554. /* Called when we exhaust all guards in our sampled set: Marks all guards as
  555. maybe-reachable so that we 'll try them again. */
  556. static void
  557. mark_all_guards_maybe_reachable(guard_selection_t *gs)
  558. {
  559. tor_assert(gs);
  560. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  561. mark_guard_maybe_reachable(guard);
  562. } SMARTLIST_FOREACH_END(guard);
  563. }
  564. /**@}*/
  565. /**
  566. * Given our options and our list of nodes, return the name of the
  567. * guard selection that we should use. Return NULL for "use the
  568. * same selection you were using before.
  569. */
  570. STATIC const char *
  571. choose_guard_selection(const or_options_t *options,
  572. const networkstatus_t *live_ns,
  573. const guard_selection_t *old_selection,
  574. guard_selection_type_t *type_out)
  575. {
  576. tor_assert(options);
  577. tor_assert(type_out);
  578. if (options->UseBridges) {
  579. *type_out = GS_TYPE_BRIDGE;
  580. return "bridges";
  581. }
  582. if (! live_ns) {
  583. /* without a networkstatus, we can't tell any more than that. */
  584. *type_out = GS_TYPE_NORMAL;
  585. return "default";
  586. }
  587. const smartlist_t *nodes = nodelist_get_list();
  588. int n_guards = 0, n_passing_filter = 0;
  589. SMARTLIST_FOREACH_BEGIN(nodes, const node_t *, node) {
  590. if (node_is_possible_guard(node)) {
  591. ++n_guards;
  592. if (node_passes_guard_filter(options, node)) {
  593. ++n_passing_filter;
  594. }
  595. }
  596. } SMARTLIST_FOREACH_END(node);
  597. /* We use separate 'high' and 'low' thresholds here to prevent flapping
  598. * back and forth */
  599. const int meaningful_threshold_high =
  600. (int)(n_guards * get_meaningful_restriction_threshold() * 1.05);
  601. const int meaningful_threshold_mid =
  602. (int)(n_guards * get_meaningful_restriction_threshold());
  603. const int meaningful_threshold_low =
  604. (int)(n_guards * get_meaningful_restriction_threshold() * .95);
  605. const int extreme_threshold =
  606. (int)(n_guards * get_extreme_restriction_threshold());
  607. /*
  608. If we have no previous selection, then we're "restricted" iff we are
  609. below the meaningful restriction threshold. That's easy enough.
  610. But if we _do_ have a previous selection, we make it a little
  611. "sticky": we only move from "restricted" to "default" when we find
  612. that we're above the threshold plus 5%, and we only move from
  613. "default" to "restricted" when we're below the threshold minus 5%.
  614. That should prevent us from flapping back and forth if we happen to
  615. be hovering very close to the default.
  616. The extreme threshold is for warning only.
  617. */
  618. static int have_warned_extreme_threshold = 0;
  619. if (n_guards &&
  620. n_passing_filter < extreme_threshold &&
  621. ! have_warned_extreme_threshold) {
  622. have_warned_extreme_threshold = 1;
  623. const double exclude_frac =
  624. (n_guards - n_passing_filter) / (double)n_guards;
  625. log_warn(LD_GUARD, "Your configuration excludes %d%% of all possible "
  626. "guards. That's likely to make you stand out from the "
  627. "rest of the world.", (int)(exclude_frac * 100));
  628. }
  629. /* Easy case: no previous selection. Just check if we are in restricted or
  630. normal guard selection. */
  631. if (old_selection == NULL) {
  632. if (n_passing_filter >= meaningful_threshold_mid) {
  633. *type_out = GS_TYPE_NORMAL;
  634. return "default";
  635. } else {
  636. *type_out = GS_TYPE_RESTRICTED;
  637. return "restricted";
  638. }
  639. }
  640. /* Trickier case: we do have a previous guard selection context. */
  641. tor_assert(old_selection);
  642. /* Use high and low thresholds to decide guard selection, and if we fall in
  643. the middle then keep the current guard selection context. */
  644. if (n_passing_filter >= meaningful_threshold_high) {
  645. *type_out = GS_TYPE_NORMAL;
  646. return "default";
  647. } else if (n_passing_filter < meaningful_threshold_low) {
  648. *type_out = GS_TYPE_RESTRICTED;
  649. return "restricted";
  650. } else {
  651. /* we are in the middle: maintain previous guard selection */
  652. *type_out = old_selection->type;
  653. return old_selection->name;
  654. }
  655. }
  656. /**
  657. * Check whether we should switch from our current guard selection to a
  658. * different one. If so, switch and return 1. Return 0 otherwise.
  659. *
  660. * On a 1 return, the caller should mark all currently live circuits unusable
  661. * for new streams, by calling circuit_mark_all_unused_circs() and
  662. * circuit_mark_all_dirty_circs_as_unusable().
  663. */
  664. int
  665. update_guard_selection_choice(const or_options_t *options)
  666. {
  667. if (!curr_guard_context) {
  668. create_initial_guard_context();
  669. return 1;
  670. }
  671. guard_selection_type_t type = GS_TYPE_INFER;
  672. const char *new_name = choose_guard_selection(
  673. options,
  674. networkstatus_get_reasonably_live_consensus(
  675. approx_time(),
  676. usable_consensus_flavor()),
  677. curr_guard_context,
  678. &type);
  679. tor_assert(new_name);
  680. tor_assert(type != GS_TYPE_INFER);
  681. const char *cur_name = curr_guard_context->name;
  682. if (! strcmp(cur_name, new_name)) {
  683. log_debug(LD_GUARD,
  684. "Staying with guard context \"%s\" (no change)", new_name);
  685. return 0; // No change
  686. }
  687. log_notice(LD_GUARD, "Switching to guard context \"%s\" (was using \"%s\")",
  688. new_name, cur_name);
  689. guard_selection_t *new_guard_context;
  690. new_guard_context = get_guard_selection_by_name(new_name, type, 1);
  691. tor_assert(new_guard_context);
  692. tor_assert(new_guard_context != curr_guard_context);
  693. curr_guard_context = new_guard_context;
  694. return 1;
  695. }
  696. /**
  697. * Return true iff <b>node</b> has all the flags needed for us to consider it
  698. * a possible guard when sampling guards.
  699. */
  700. static int
  701. node_is_possible_guard(const node_t *node)
  702. {
  703. /* The "GUARDS" set is all nodes in the nodelist for which this predicate
  704. * holds. */
  705. tor_assert(node);
  706. return (node->is_possible_guard &&
  707. node->is_stable &&
  708. node->is_fast &&
  709. node->is_valid &&
  710. node_is_dir(node) &&
  711. !router_digest_is_me(node->identity));
  712. }
  713. /**
  714. * Return the sampled guard with the RSA identity digest <b>rsa_id</b>, or
  715. * NULL if we don't have one. */
  716. STATIC entry_guard_t *
  717. get_sampled_guard_with_id(guard_selection_t *gs,
  718. const uint8_t *rsa_id)
  719. {
  720. tor_assert(gs);
  721. tor_assert(rsa_id);
  722. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  723. if (tor_memeq(guard->identity, rsa_id, DIGEST_LEN))
  724. return guard;
  725. } SMARTLIST_FOREACH_END(guard);
  726. return NULL;
  727. }
  728. /** If <b>gs</b> contains a sampled entry guard matching <b>bridge</b>,
  729. * return that guard. Otherwise return NULL. */
  730. static entry_guard_t *
  731. get_sampled_guard_for_bridge(guard_selection_t *gs,
  732. const bridge_info_t *bridge)
  733. {
  734. const uint8_t *id = bridge_get_rsa_id_digest(bridge);
  735. const tor_addr_port_t *addrport = bridge_get_addr_port(bridge);
  736. entry_guard_t *guard;
  737. if (BUG(!addrport))
  738. return NULL; // LCOV_EXCL_LINE
  739. guard = get_sampled_guard_by_bridge_addr(gs, addrport);
  740. if (! guard || (id && tor_memneq(id, guard->identity, DIGEST_LEN)))
  741. return NULL;
  742. else
  743. return guard;
  744. }
  745. /** If we know a bridge_info_t matching <b>guard</b>, return that
  746. * bridge. Otherwise return NULL. */
  747. static bridge_info_t *
  748. get_bridge_info_for_guard(const entry_guard_t *guard)
  749. {
  750. const uint8_t *identity = NULL;
  751. if (! tor_digest_is_zero(guard->identity)) {
  752. identity = (const uint8_t *)guard->identity;
  753. }
  754. if (BUG(guard->bridge_addr == NULL))
  755. return NULL;
  756. return get_configured_bridge_by_exact_addr_port_digest(
  757. &guard->bridge_addr->addr,
  758. guard->bridge_addr->port,
  759. (const char*)identity);
  760. }
  761. /**
  762. * Return true iff we have a sampled guard with the RSA identity digest
  763. * <b>rsa_id</b>. */
  764. static inline int
  765. have_sampled_guard_with_id(guard_selection_t *gs, const uint8_t *rsa_id)
  766. {
  767. return get_sampled_guard_with_id(gs, rsa_id) != NULL;
  768. }
  769. /**
  770. * Allocate a new entry_guard_t object for <b>node</b>, add it to the
  771. * sampled entry guards in <b>gs</b>, and return it. <b>node</b> must
  772. * not currently be a sampled guard in <b>gs</b>.
  773. */
  774. STATIC entry_guard_t *
  775. entry_guard_add_to_sample(guard_selection_t *gs,
  776. const node_t *node)
  777. {
  778. log_info(LD_GUARD, "Adding %s to the entry guard sample set.",
  779. node_describe(node));
  780. /* make sure that the guard is not already sampled. */
  781. if (BUG(have_sampled_guard_with_id(gs, (const uint8_t*)node->identity)))
  782. return NULL; // LCOV_EXCL_LINE
  783. return entry_guard_add_to_sample_impl(gs,
  784. (const uint8_t*)node->identity,
  785. node_get_nickname(node),
  786. NULL);
  787. }
  788. /**
  789. * Backend: adds a new sampled guard to <b>gs</b>, with given identity,
  790. * nickname, and ORPort. rsa_id_digest and bridge_addrport are optional, but
  791. * we need one of them. nickname is optional. The caller is responsible for
  792. * maintaining the size limit of the SAMPLED_GUARDS set.
  793. */
  794. static entry_guard_t *
  795. entry_guard_add_to_sample_impl(guard_selection_t *gs,
  796. const uint8_t *rsa_id_digest,
  797. const char *nickname,
  798. const tor_addr_port_t *bridge_addrport)
  799. {
  800. const int GUARD_LIFETIME = get_guard_lifetime();
  801. tor_assert(gs);
  802. // XXXX #20827 take ed25519 identity here too.
  803. /* Make sure we can actually identify the guard. */
  804. if (BUG(!rsa_id_digest && !bridge_addrport))
  805. return NULL; // LCOV_EXCL_LINE
  806. entry_guard_t *guard = tor_malloc_zero(sizeof(entry_guard_t));
  807. /* persistent fields */
  808. guard->is_persistent = (rsa_id_digest != NULL);
  809. guard->selection_name = tor_strdup(gs->name);
  810. if (rsa_id_digest)
  811. memcpy(guard->identity, rsa_id_digest, DIGEST_LEN);
  812. if (nickname)
  813. strlcpy(guard->nickname, nickname, sizeof(guard->nickname));
  814. guard->sampled_on_date = randomize_time(approx_time(), GUARD_LIFETIME/10);
  815. tor_free(guard->sampled_by_version);
  816. guard->sampled_by_version = tor_strdup(VERSION);
  817. guard->currently_listed = 1;
  818. guard->confirmed_idx = -1;
  819. /* non-persistent fields */
  820. guard->is_reachable = GUARD_REACHABLE_MAYBE;
  821. if (bridge_addrport)
  822. guard->bridge_addr = tor_memdup(bridge_addrport, sizeof(*bridge_addrport));
  823. smartlist_add(gs->sampled_entry_guards, guard);
  824. guard->in_selection = gs;
  825. entry_guard_set_filtered_flags(get_options(), gs, guard);
  826. entry_guards_changed_for_guard_selection(gs);
  827. return guard;
  828. }
  829. /**
  830. * Add an entry guard to the "bridges" guard selection sample, with
  831. * information taken from <b>bridge</b>. Return that entry guard.
  832. */
  833. static entry_guard_t *
  834. entry_guard_add_bridge_to_sample(guard_selection_t *gs,
  835. const bridge_info_t *bridge)
  836. {
  837. const uint8_t *id_digest = bridge_get_rsa_id_digest(bridge);
  838. const tor_addr_port_t *addrport = bridge_get_addr_port(bridge);
  839. tor_assert(addrport);
  840. /* make sure that the guard is not already sampled. */
  841. if (BUG(get_sampled_guard_for_bridge(gs, bridge)))
  842. return NULL; // LCOV_EXCL_LINE
  843. return entry_guard_add_to_sample_impl(gs, id_digest, NULL, addrport);
  844. }
  845. /**
  846. * Return the entry_guard_t in <b>gs</b> whose address is <b>addrport</b>,
  847. * or NULL if none exists.
  848. */
  849. static entry_guard_t *
  850. get_sampled_guard_by_bridge_addr(guard_selection_t *gs,
  851. const tor_addr_port_t *addrport)
  852. {
  853. if (! gs)
  854. return NULL;
  855. if (BUG(!addrport))
  856. return NULL;
  857. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, g) {
  858. if (g->bridge_addr && tor_addr_port_eq(addrport, g->bridge_addr))
  859. return g;
  860. } SMARTLIST_FOREACH_END(g);
  861. return NULL;
  862. }
  863. /** Update the guard subsystem's knowledge of the identity of the bridge
  864. * at <b>addrport</b>. Idempotent.
  865. */
  866. void
  867. entry_guard_learned_bridge_identity(const tor_addr_port_t *addrport,
  868. const uint8_t *rsa_id_digest)
  869. {
  870. guard_selection_t *gs = get_guard_selection_by_name("bridges",
  871. GS_TYPE_BRIDGE,
  872. 0);
  873. if (!gs)
  874. return;
  875. entry_guard_t *g = get_sampled_guard_by_bridge_addr(gs, addrport);
  876. if (!g)
  877. return;
  878. int make_persistent = 0;
  879. if (tor_digest_is_zero(g->identity)) {
  880. memcpy(g->identity, rsa_id_digest, DIGEST_LEN);
  881. make_persistent = 1;
  882. } else if (tor_memeq(g->identity, rsa_id_digest, DIGEST_LEN)) {
  883. /* Nothing to see here; we learned something we already knew. */
  884. if (BUG(! g->is_persistent))
  885. make_persistent = 1;
  886. } else {
  887. char old_id[HEX_DIGEST_LEN+1];
  888. base16_encode(old_id, sizeof(old_id), g->identity, sizeof(g->identity));
  889. log_warn(LD_BUG, "We 'learned' an identity %s for a bridge at %s:%d, but "
  890. "we already knew a different one (%s). Ignoring the new info as "
  891. "possibly bogus.",
  892. hex_str((const char *)rsa_id_digest, DIGEST_LEN),
  893. fmt_and_decorate_addr(&addrport->addr), addrport->port,
  894. old_id);
  895. return; // redundant, but let's be clear: we're not making this persistent.
  896. }
  897. if (make_persistent) {
  898. g->is_persistent = 1;
  899. entry_guards_changed_for_guard_selection(gs);
  900. }
  901. }
  902. /**
  903. * Return the number of sampled guards in <b>gs</b> that are "filtered"
  904. * (that is, we're willing to connect to them) and that are "usable"
  905. * (that is, either "reachable" or "maybe reachable").
  906. *
  907. * If a restriction is provided in <b>rst</b>, do not count any guards that
  908. * violate it.
  909. */
  910. STATIC int
  911. num_reachable_filtered_guards(const guard_selection_t *gs,
  912. const entry_guard_restriction_t *rst)
  913. {
  914. int n_reachable_filtered_guards = 0;
  915. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  916. entry_guard_consider_retry(guard);
  917. if (! entry_guard_obeys_restriction(guard, rst))
  918. continue;
  919. if (guard->is_usable_filtered_guard)
  920. ++n_reachable_filtered_guards;
  921. } SMARTLIST_FOREACH_END(guard);
  922. return n_reachable_filtered_guards;
  923. }
  924. /** Return the actual maximum size for the sample in <b>gs</b>,
  925. * given that we know about <b>n_guards</b> total. */
  926. static int
  927. get_max_sample_size(guard_selection_t *gs,
  928. int n_guards)
  929. {
  930. const int using_bridges = (gs->type == GS_TYPE_BRIDGE);
  931. const int min_sample = get_min_filtered_sample_size();
  932. /* If we are in bridge mode, expand our sample set as needed without worrying
  933. * about max size. We should respect the user's wishes to use many bridges if
  934. * that's what they have specified in their configuration file. */
  935. if (using_bridges)
  936. return INT_MAX;
  937. const int max_sample_by_pct = (int)(n_guards * get_max_sample_threshold());
  938. const int max_sample_absolute = get_max_sample_size_absolute();
  939. const int max_sample = MIN(max_sample_by_pct, max_sample_absolute);
  940. if (max_sample < min_sample)
  941. return min_sample;
  942. else
  943. return max_sample;
  944. }
  945. /**
  946. * Return a smartlist of the all the guards that are not currently
  947. * members of the sample (GUARDS - SAMPLED_GUARDS). The elements of
  948. * this list are node_t pointers in the non-bridge case, and
  949. * bridge_info_t pointers in the bridge case. Set *<b>n_guards_out/b>
  950. * to the number of guards that we found in GUARDS, including those
  951. * that were already sampled.
  952. */
  953. static smartlist_t *
  954. get_eligible_guards(const or_options_t *options,
  955. guard_selection_t *gs,
  956. int *n_guards_out)
  957. {
  958. /* Construct eligible_guards as GUARDS - SAMPLED_GUARDS */
  959. smartlist_t *eligible_guards = smartlist_new();
  960. int n_guards = 0; // total size of "GUARDS"
  961. if (gs->type == GS_TYPE_BRIDGE) {
  962. const smartlist_t *bridges = bridge_list_get();
  963. SMARTLIST_FOREACH_BEGIN(bridges, bridge_info_t *, bridge) {
  964. ++n_guards;
  965. if (NULL != get_sampled_guard_for_bridge(gs, bridge)) {
  966. continue;
  967. }
  968. smartlist_add(eligible_guards, bridge);
  969. } SMARTLIST_FOREACH_END(bridge);
  970. } else {
  971. const smartlist_t *nodes = nodelist_get_list();
  972. const int n_sampled = smartlist_len(gs->sampled_entry_guards);
  973. /* Build a bloom filter of our current guards: let's keep this O(N). */
  974. digestset_t *sampled_guard_ids = digestset_new(n_sampled);
  975. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, const entry_guard_t *,
  976. guard) {
  977. digestset_add(sampled_guard_ids, guard->identity);
  978. } SMARTLIST_FOREACH_END(guard);
  979. SMARTLIST_FOREACH_BEGIN(nodes, const node_t *, node) {
  980. if (! node_is_possible_guard(node))
  981. continue;
  982. if (gs->type == GS_TYPE_RESTRICTED) {
  983. /* In restricted mode, we apply the filter BEFORE sampling, so
  984. * that we are sampling from the nodes that we might actually
  985. * select. If we sampled first, we might wind up with a sample
  986. * that didn't include any EntryNodes at all. */
  987. if (! node_passes_guard_filter(options, node))
  988. continue;
  989. }
  990. ++n_guards;
  991. if (digestset_probably_contains(sampled_guard_ids, node->identity))
  992. continue;
  993. smartlist_add(eligible_guards, (node_t*)node);
  994. } SMARTLIST_FOREACH_END(node);
  995. /* Now we can free that bloom filter. */
  996. digestset_free(sampled_guard_ids);
  997. }
  998. *n_guards_out = n_guards;
  999. return eligible_guards;
  1000. }
  1001. /** Helper: given a smartlist of either bridge_info_t (if gs->type is
  1002. * GS_TYPE_BRIDGE) or node_t (otherwise), pick one that can be a guard,
  1003. * add it as a guard, remove it from the list, and return a new
  1004. * entry_guard_t. Return NULL on failure. */
  1005. static entry_guard_t *
  1006. select_and_add_guard_item_for_sample(guard_selection_t *gs,
  1007. smartlist_t *eligible_guards)
  1008. {
  1009. entry_guard_t *added_guard;
  1010. if (gs->type == GS_TYPE_BRIDGE) {
  1011. const bridge_info_t *bridge = smartlist_choose(eligible_guards);
  1012. if (BUG(!bridge))
  1013. return NULL; // LCOV_EXCL_LINE
  1014. smartlist_remove(eligible_guards, bridge);
  1015. added_guard = entry_guard_add_bridge_to_sample(gs, bridge);
  1016. } else {
  1017. const node_t *node =
  1018. node_sl_choose_by_bandwidth(eligible_guards, WEIGHT_FOR_GUARD);
  1019. if (BUG(!node))
  1020. return NULL; // LCOV_EXCL_LINE
  1021. smartlist_remove(eligible_guards, node);
  1022. added_guard = entry_guard_add_to_sample(gs, node);
  1023. }
  1024. return added_guard;
  1025. }
  1026. /**
  1027. * Return true iff we need a consensus to update our guards, but we don't
  1028. * have one. (We can return 0 here either if the consensus is _not_ missing,
  1029. * or if we don't need a consensus because we're using bridges.)
  1030. */
  1031. static int
  1032. reasonably_live_consensus_is_missing(const guard_selection_t *gs)
  1033. {
  1034. tor_assert(gs);
  1035. if (gs->type == GS_TYPE_BRIDGE) {
  1036. /* We don't update bridges from the consensus; they aren't there. */
  1037. return 0;
  1038. }
  1039. return networkstatus_get_reasonably_live_consensus(
  1040. approx_time(),
  1041. usable_consensus_flavor()) == NULL;
  1042. }
  1043. /**
  1044. * Add new guards to the sampled guards in <b>gs</b> until there are
  1045. * enough usable filtered guards, but never grow the sample beyond its
  1046. * maximum size. Return the last guard added, or NULL if none were
  1047. * added.
  1048. */
  1049. STATIC entry_guard_t *
  1050. entry_guards_expand_sample(guard_selection_t *gs)
  1051. {
  1052. tor_assert(gs);
  1053. const or_options_t *options = get_options();
  1054. if (reasonably_live_consensus_is_missing(gs)) {
  1055. log_info(LD_GUARD, "Not expanding the sample guard set; we have "
  1056. "no reasonably live consensus.");
  1057. return NULL;
  1058. }
  1059. int n_sampled = smartlist_len(gs->sampled_entry_guards);
  1060. entry_guard_t *added_guard = NULL;
  1061. int n_usable_filtered_guards = num_reachable_filtered_guards(gs, NULL);
  1062. int n_guards = 0;
  1063. smartlist_t *eligible_guards = get_eligible_guards(options, gs, &n_guards);
  1064. const int max_sample = get_max_sample_size(gs, n_guards);
  1065. const int min_filtered_sample = get_min_filtered_sample_size();
  1066. log_info(LD_GUARD, "Expanding the sample guard set. We have %d guards "
  1067. "in the sample, and %d eligible guards to extend it with.",
  1068. n_sampled, smartlist_len(eligible_guards));
  1069. while (n_usable_filtered_guards < min_filtered_sample) {
  1070. /* Has our sample grown too large to expand? */
  1071. if (n_sampled >= max_sample) {
  1072. log_info(LD_GUARD, "Not expanding the guard sample any further; "
  1073. "just hit the maximum sample threshold of %d",
  1074. max_sample);
  1075. goto done;
  1076. }
  1077. /* Did we run out of guards? */
  1078. if (smartlist_len(eligible_guards) == 0) {
  1079. /* LCOV_EXCL_START
  1080. As long as MAX_SAMPLE_THRESHOLD makes can't be adjusted to
  1081. allow all guards to be sampled, this can't be reached.
  1082. */
  1083. log_info(LD_GUARD, "Not expanding the guard sample any further; "
  1084. "just ran out of eligible guards");
  1085. goto done;
  1086. /* LCOV_EXCL_STOP */
  1087. }
  1088. /* Otherwise we can add at least one new guard. */
  1089. added_guard = select_and_add_guard_item_for_sample(gs, eligible_guards);
  1090. if (!added_guard)
  1091. goto done; // LCOV_EXCL_LINE -- only fails on BUG.
  1092. ++n_sampled;
  1093. if (added_guard->is_usable_filtered_guard)
  1094. ++n_usable_filtered_guards;
  1095. }
  1096. done:
  1097. smartlist_free(eligible_guards);
  1098. return added_guard;
  1099. }
  1100. /**
  1101. * Helper: <b>guard</b> has just been removed from the sampled guards:
  1102. * also remove it from primary and confirmed. */
  1103. static void
  1104. remove_guard_from_confirmed_and_primary_lists(guard_selection_t *gs,
  1105. entry_guard_t *guard)
  1106. {
  1107. if (guard->is_primary) {
  1108. guard->is_primary = 0;
  1109. smartlist_remove_keeporder(gs->primary_entry_guards, guard);
  1110. } else {
  1111. if (BUG(smartlist_contains(gs->primary_entry_guards, guard))) {
  1112. smartlist_remove_keeporder(gs->primary_entry_guards, guard);
  1113. }
  1114. }
  1115. if (guard->confirmed_idx >= 0) {
  1116. smartlist_remove_keeporder(gs->confirmed_entry_guards, guard);
  1117. guard->confirmed_idx = -1;
  1118. guard->confirmed_on_date = 0;
  1119. } else {
  1120. if (BUG(smartlist_contains(gs->confirmed_entry_guards, guard))) {
  1121. // LCOV_EXCL_START
  1122. smartlist_remove_keeporder(gs->confirmed_entry_guards, guard);
  1123. // LCOV_EXCL_STOP
  1124. }
  1125. }
  1126. }
  1127. /** Return true iff <b>guard</b> is currently "listed" -- that is, it
  1128. * appears in the consensus, or as a configured bridge (as
  1129. * appropriate) */
  1130. MOCK_IMPL(STATIC int,
  1131. entry_guard_is_listed,(guard_selection_t *gs, const entry_guard_t *guard))
  1132. {
  1133. if (gs->type == GS_TYPE_BRIDGE) {
  1134. return NULL != get_bridge_info_for_guard(guard);
  1135. } else {
  1136. const node_t *node = node_get_by_id(guard->identity);
  1137. return node && node_is_possible_guard(node);
  1138. }
  1139. }
  1140. /**
  1141. * Enumerate <b>sampled_entry_guards</b> smartlist in <b>gs</b>.
  1142. * For each <b>entry_guard_t</b> object in smartlist, do the following:
  1143. * * Update <b>currently_listed</b> field to reflect if guard is listed
  1144. * in guard selection <b>gs</b>.
  1145. * * Set <b>unlisted_since_date</b> to approximate UNIX time of
  1146. * unlisting if guard is unlisted (randomize within 20% of
  1147. * get_remove_unlisted_guards_after_seconds()). Otherwise,
  1148. * set it to 0.
  1149. *
  1150. * Require <b>gs</b> to be non-null pointer.
  1151. * Return a number of entries updated.
  1152. */
  1153. static size_t
  1154. sampled_guards_update_consensus_presence(guard_selection_t *gs)
  1155. {
  1156. size_t n_changes = 0;
  1157. tor_assert(gs);
  1158. const time_t unlisted_since_slop =
  1159. get_remove_unlisted_guards_after_seconds() / 5;
  1160. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  1161. /* XXXX #20827 check ed ID too */
  1162. const int is_listed = entry_guard_is_listed(gs, guard);
  1163. if (is_listed && ! guard->currently_listed) {
  1164. ++n_changes;
  1165. guard->currently_listed = 1;
  1166. guard->unlisted_since_date = 0;
  1167. log_info(LD_GUARD, "Sampled guard %s is now listed again.",
  1168. entry_guard_describe(guard));
  1169. } else if (!is_listed && guard->currently_listed) {
  1170. ++n_changes;
  1171. guard->currently_listed = 0;
  1172. guard->unlisted_since_date = randomize_time(approx_time(),
  1173. unlisted_since_slop);
  1174. log_info(LD_GUARD, "Sampled guard %s is now unlisted.",
  1175. entry_guard_describe(guard));
  1176. } else if (is_listed && guard->currently_listed) {
  1177. log_debug(LD_GUARD, "Sampled guard %s is still listed.",
  1178. entry_guard_describe(guard));
  1179. } else {
  1180. tor_assert(! is_listed && ! guard->currently_listed);
  1181. log_debug(LD_GUARD, "Sampled guard %s is still unlisted.",
  1182. entry_guard_describe(guard));
  1183. }
  1184. /* Clean up unlisted_since_date, just in case. */
  1185. if (guard->currently_listed && guard->unlisted_since_date) {
  1186. ++n_changes;
  1187. guard->unlisted_since_date = 0;
  1188. log_warn(LD_BUG, "Sampled guard %s was listed, but with "
  1189. "unlisted_since_date set. Fixing.",
  1190. entry_guard_describe(guard));
  1191. } else if (!guard->currently_listed && ! guard->unlisted_since_date) {
  1192. ++n_changes;
  1193. guard->unlisted_since_date = randomize_time(approx_time(),
  1194. unlisted_since_slop);
  1195. log_warn(LD_BUG, "Sampled guard %s was unlisted, but with "
  1196. "unlisted_since_date unset. Fixing.",
  1197. entry_guard_describe(guard));
  1198. }
  1199. } SMARTLIST_FOREACH_END(guard);
  1200. return n_changes;
  1201. }
  1202. /**
  1203. * Enumerate <b>sampled_entry_guards</b> smartlist in <b>gs</b>.
  1204. * For each <b>entry_guard_t</b> object in smartlist, do the following:
  1205. * * If <b>currently_listed</b> is false and <b>unlisted_since_date</b>
  1206. * is earlier than <b>remove_if_unlisted_since</b> - remove it.
  1207. * * Otherwise, check if <b>sampled_on_date</b> is earlier than
  1208. * <b>maybe_remove_if_sampled_before</b>.
  1209. * * When above condition is correct, remove the guard if:
  1210. * * It was never confirmed.
  1211. * * It was confirmed before <b>remove_if_confirmed_before</b>.
  1212. *
  1213. * Require <b>gs</b> to be non-null pointer.
  1214. * Return number of entries deleted.
  1215. */
  1216. static size_t
  1217. sampled_guards_prune_obsolete_entries(guard_selection_t *gs,
  1218. const time_t remove_if_unlisted_since,
  1219. const time_t maybe_remove_if_sampled_before,
  1220. const time_t remove_if_confirmed_before)
  1221. {
  1222. size_t n_changes = 0;
  1223. tor_assert(gs);
  1224. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  1225. int rmv = 0;
  1226. if (guard->currently_listed == 0 &&
  1227. guard->unlisted_since_date < remove_if_unlisted_since) {
  1228. /*
  1229. "We have a live consensus, and {IS_LISTED} is false, and
  1230. {FIRST_UNLISTED_AT} is over get_remove_unlisted_guards_after_days()
  1231. days in the past."
  1232. */
  1233. log_info(LD_GUARD, "Removing sampled guard %s: it has been unlisted "
  1234. "for over %d days", entry_guard_describe(guard),
  1235. get_remove_unlisted_guards_after_days());
  1236. rmv = 1;
  1237. } else if (guard->sampled_on_date < maybe_remove_if_sampled_before) {
  1238. /* We have a live consensus, and {ADDED_ON_DATE} is over
  1239. {GUARD_LIFETIME} ago, *and* {CONFIRMED_ON_DATE} is either
  1240. "never", or over {GUARD_CONFIRMED_MIN_LIFETIME} ago.
  1241. */
  1242. if (guard->confirmed_on_date == 0) {
  1243. rmv = 1;
  1244. log_info(LD_GUARD, "Removing sampled guard %s: it was sampled "
  1245. "over %d days ago, but never confirmed.",
  1246. entry_guard_describe(guard),
  1247. get_guard_lifetime() / 86400);
  1248. } else if (guard->confirmed_on_date < remove_if_confirmed_before) {
  1249. rmv = 1;
  1250. log_info(LD_GUARD, "Removing sampled guard %s: it was sampled "
  1251. "over %d days ago, and confirmed over %d days ago.",
  1252. entry_guard_describe(guard),
  1253. get_guard_lifetime() / 86400,
  1254. get_guard_confirmed_min_lifetime() / 86400);
  1255. }
  1256. }
  1257. if (rmv) {
  1258. ++n_changes;
  1259. SMARTLIST_DEL_CURRENT(gs->sampled_entry_guards, guard);
  1260. remove_guard_from_confirmed_and_primary_lists(gs, guard);
  1261. entry_guard_free(guard);
  1262. }
  1263. } SMARTLIST_FOREACH_END(guard);
  1264. return n_changes;
  1265. }
  1266. /**
  1267. * Update the status of all sampled guards based on the arrival of a
  1268. * new consensus networkstatus document. This will include marking
  1269. * some guards as listed or unlisted, and removing expired guards. */
  1270. STATIC void
  1271. sampled_guards_update_from_consensus(guard_selection_t *gs)
  1272. {
  1273. tor_assert(gs);
  1274. // It's important to use a reasonably live consensus here; we want clients
  1275. // to bootstrap even if their clock is skewed by more than 2-3 hours.
  1276. // But we don't want to make changes based on anything that's really old.
  1277. if (reasonably_live_consensus_is_missing(gs)) {
  1278. log_info(LD_GUARD, "Not updating the sample guard set; we have "
  1279. "no reasonably live consensus.");
  1280. return;
  1281. }
  1282. log_info(LD_GUARD, "Updating sampled guard status based on received "
  1283. "consensus.");
  1284. /* First: Update listed/unlisted. */
  1285. size_t n_changes = sampled_guards_update_consensus_presence(gs);
  1286. const time_t remove_if_unlisted_since =
  1287. approx_time() - get_remove_unlisted_guards_after_seconds();
  1288. const time_t maybe_remove_if_sampled_before =
  1289. approx_time() - get_guard_lifetime();
  1290. const time_t remove_if_confirmed_before =
  1291. approx_time() - get_guard_confirmed_min_lifetime();
  1292. /* Then: remove the ones that have been junk for too long */
  1293. n_changes +=
  1294. sampled_guards_prune_obsolete_entries(gs,
  1295. remove_if_unlisted_since,
  1296. maybe_remove_if_sampled_before,
  1297. remove_if_confirmed_before);
  1298. if (n_changes) {
  1299. gs->primary_guards_up_to_date = 0;
  1300. entry_guards_update_filtered_sets(gs);
  1301. /* We don't need to rebuild the confirmed list right here -- we may have
  1302. * removed confirmed guards above, but we can't have added any new
  1303. * confirmed guards.
  1304. */
  1305. entry_guards_changed_for_guard_selection(gs);
  1306. }
  1307. }
  1308. /**
  1309. * Return true iff <b>node</b> is a Tor relay that we are configured to
  1310. * be able to connect to. */
  1311. static int
  1312. node_passes_guard_filter(const or_options_t *options,
  1313. const node_t *node)
  1314. {
  1315. /* NOTE: Make sure that this function stays in sync with
  1316. * options_transition_affects_entry_guards */
  1317. if (routerset_contains_node(options->ExcludeNodes, node))
  1318. return 0;
  1319. if (options->EntryNodes &&
  1320. !routerset_contains_node(options->EntryNodes, node))
  1321. return 0;
  1322. if (!fascist_firewall_allows_node(node, FIREWALL_OR_CONNECTION, 0))
  1323. return 0;
  1324. if (node_is_a_configured_bridge(node))
  1325. return 0;
  1326. return 1;
  1327. }
  1328. /** Helper: Return true iff <b>bridge</b> passes our configuration
  1329. * filter-- if it is a relay that we are configured to be able to
  1330. * connect to. */
  1331. static int
  1332. bridge_passes_guard_filter(const or_options_t *options,
  1333. const bridge_info_t *bridge)
  1334. {
  1335. tor_assert(bridge);
  1336. if (!bridge)
  1337. return 0;
  1338. if (routerset_contains_bridge(options->ExcludeNodes, bridge))
  1339. return 0;
  1340. /* Ignore entrynodes */
  1341. const tor_addr_port_t *addrport = bridge_get_addr_port(bridge);
  1342. if (!fascist_firewall_allows_address_addr(&addrport->addr,
  1343. addrport->port,
  1344. FIREWALL_OR_CONNECTION,
  1345. 0, 0))
  1346. return 0;
  1347. return 1;
  1348. }
  1349. /**
  1350. * Return true iff <b>guard</b> is a Tor relay that we are configured to
  1351. * be able to connect to, and we haven't disabled it for omission from
  1352. * the consensus or path bias issues. */
  1353. static int
  1354. entry_guard_passes_filter(const or_options_t *options, guard_selection_t *gs,
  1355. entry_guard_t *guard)
  1356. {
  1357. if (guard->currently_listed == 0)
  1358. return 0;
  1359. if (guard->pb.path_bias_disabled)
  1360. return 0;
  1361. if (gs->type == GS_TYPE_BRIDGE) {
  1362. const bridge_info_t *bridge = get_bridge_info_for_guard(guard);
  1363. if (bridge == NULL)
  1364. return 0;
  1365. return bridge_passes_guard_filter(options, bridge);
  1366. } else {
  1367. const node_t *node = node_get_by_id(guard->identity);
  1368. if (node == NULL) {
  1369. // This can happen when currently_listed is true, and we're not updating
  1370. // it because we don't have a live consensus.
  1371. return 0;
  1372. }
  1373. return node_passes_guard_filter(options, node);
  1374. }
  1375. }
  1376. /** Return true iff <b>guard</b> is in the same family as <b>node</b>.
  1377. */
  1378. static int
  1379. guard_in_node_family(const entry_guard_t *guard, const node_t *node)
  1380. {
  1381. const node_t *guard_node = node_get_by_id(guard->identity);
  1382. if (guard_node) {
  1383. return nodes_in_same_family(guard_node, node);
  1384. } else {
  1385. /* If we don't have a node_t for the guard node, we might have
  1386. * a bridge_info_t for it. So let's check to see whether the bridge
  1387. * address matches has any family issues.
  1388. *
  1389. * (Strictly speaking, I believe this check is unnecessary, since we only
  1390. * use it to avoid the exit's family when building circuits, and we don't
  1391. * build multihop circuits until we have a routerinfo_t for the
  1392. * bridge... at which point, we'll also have a node_t for the
  1393. * bridge. Nonetheless, it seems wise to include it, in case our
  1394. * assumptions change down the road. -nickm.)
  1395. */
  1396. if (get_options()->EnforceDistinctSubnets && guard->bridge_addr) {
  1397. tor_addr_t node_addr;
  1398. node_get_addr(node, &node_addr);
  1399. if (addrs_in_same_network_family(&node_addr,
  1400. &guard->bridge_addr->addr)) {
  1401. return 1;
  1402. }
  1403. }
  1404. return 0;
  1405. }
  1406. }
  1407. /* Allocate and return a new exit guard restriction (where <b>exit_id</b> is of
  1408. * size DIGEST_LEN) */
  1409. STATIC entry_guard_restriction_t *
  1410. guard_create_exit_restriction(const uint8_t *exit_id)
  1411. {
  1412. entry_guard_restriction_t *rst = NULL;
  1413. rst = tor_malloc_zero(sizeof(entry_guard_restriction_t));
  1414. rst->type = RST_EXIT_NODE;
  1415. memcpy(rst->exclude_id, exit_id, DIGEST_LEN);
  1416. return rst;
  1417. }
  1418. /** If we have fewer than this many possible usable guards, don't set
  1419. * MD-availability-based restrictions: we might blacklist all of them. */
  1420. #define MIN_GUARDS_FOR_MD_RESTRICTION 10
  1421. /** Return true if we should set md dirserver restrictions. We might not want
  1422. * to set those if our guard options are too restricted, since we don't want
  1423. * to blacklist all of them. */
  1424. static int
  1425. should_set_md_dirserver_restriction(void)
  1426. {
  1427. const guard_selection_t *gs = get_guard_selection_info();
  1428. int num_usable_guards = num_reachable_filtered_guards(gs, NULL);
  1429. /* Don't set restriction if too few reachable filtered guards. */
  1430. if (num_usable_guards < MIN_GUARDS_FOR_MD_RESTRICTION) {
  1431. log_info(LD_GUARD, "Not setting md restriction: only %d"
  1432. " usable guards.", num_usable_guards);
  1433. return 0;
  1434. }
  1435. /* We have enough usable guards: set MD restriction */
  1436. return 1;
  1437. }
  1438. /** Allocate and return an outdated md guard restriction. Return NULL if no
  1439. * such restriction is needed. */
  1440. STATIC entry_guard_restriction_t *
  1441. guard_create_dirserver_md_restriction(void)
  1442. {
  1443. entry_guard_restriction_t *rst = NULL;
  1444. if (!should_set_md_dirserver_restriction()) {
  1445. log_debug(LD_GUARD, "Not setting md restriction: too few "
  1446. "filtered guards.");
  1447. return NULL;
  1448. }
  1449. rst = tor_malloc_zero(sizeof(entry_guard_restriction_t));
  1450. rst->type = RST_OUTDATED_MD_DIRSERVER;
  1451. return rst;
  1452. }
  1453. /* Return True if <b>guard</b> obeys the exit restriction <b>rst</b>. */
  1454. static int
  1455. guard_obeys_exit_restriction(const entry_guard_t *guard,
  1456. const entry_guard_restriction_t *rst)
  1457. {
  1458. tor_assert(rst->type == RST_EXIT_NODE);
  1459. // Exclude the exit ID and all of its family.
  1460. const node_t *node = node_get_by_id((const char*)rst->exclude_id);
  1461. if (node && guard_in_node_family(guard, node))
  1462. return 0;
  1463. return tor_memneq(guard->identity, rst->exclude_id, DIGEST_LEN);
  1464. }
  1465. /** Return True if <b>guard</b> should be used as a dirserver for fetching
  1466. * microdescriptors. */
  1467. static int
  1468. guard_obeys_md_dirserver_restriction(const entry_guard_t *guard)
  1469. {
  1470. /* If this guard is an outdated dirserver, don't use it. */
  1471. if (microdesc_relay_is_outdated_dirserver(guard->identity)) {
  1472. log_info(LD_GENERAL, "Skipping %s dirserver: outdated",
  1473. hex_str(guard->identity, DIGEST_LEN));
  1474. return 0;
  1475. }
  1476. log_debug(LD_GENERAL, "%s dirserver obeys md restrictions",
  1477. hex_str(guard->identity, DIGEST_LEN));
  1478. return 1;
  1479. }
  1480. /**
  1481. * Return true iff <b>guard</b> obeys the restrictions defined in <b>rst</b>.
  1482. * (If <b>rst</b> is NULL, there are no restrictions.)
  1483. */
  1484. static int
  1485. entry_guard_obeys_restriction(const entry_guard_t *guard,
  1486. const entry_guard_restriction_t *rst)
  1487. {
  1488. tor_assert(guard);
  1489. if (! rst)
  1490. return 1; // No restriction? No problem.
  1491. if (rst->type == RST_EXIT_NODE) {
  1492. return guard_obeys_exit_restriction(guard, rst);
  1493. } else if (rst->type == RST_OUTDATED_MD_DIRSERVER) {
  1494. return guard_obeys_md_dirserver_restriction(guard);
  1495. }
  1496. tor_assert_nonfatal_unreached();
  1497. return 0;
  1498. }
  1499. /**
  1500. * Update the <b>is_filtered_guard</b> and <b>is_usable_filtered_guard</b>
  1501. * flags on <b>guard</b>. */
  1502. void
  1503. entry_guard_set_filtered_flags(const or_options_t *options,
  1504. guard_selection_t *gs,
  1505. entry_guard_t *guard)
  1506. {
  1507. unsigned was_filtered = guard->is_filtered_guard;
  1508. guard->is_filtered_guard = 0;
  1509. guard->is_usable_filtered_guard = 0;
  1510. if (entry_guard_passes_filter(options, gs, guard)) {
  1511. guard->is_filtered_guard = 1;
  1512. if (guard->is_reachable != GUARD_REACHABLE_NO)
  1513. guard->is_usable_filtered_guard = 1;
  1514. entry_guard_consider_retry(guard);
  1515. }
  1516. log_debug(LD_GUARD, "Updated sampled guard %s: filtered=%d; "
  1517. "reachable_filtered=%d.", entry_guard_describe(guard),
  1518. guard->is_filtered_guard, guard->is_usable_filtered_guard);
  1519. if (!bool_eq(was_filtered, guard->is_filtered_guard)) {
  1520. /* This guard might now be primary or nonprimary. */
  1521. gs->primary_guards_up_to_date = 0;
  1522. }
  1523. }
  1524. /**
  1525. * Update the <b>is_filtered_guard</b> and <b>is_usable_filtered_guard</b>
  1526. * flag on every guard in <b>gs</b>. */
  1527. STATIC void
  1528. entry_guards_update_filtered_sets(guard_selection_t *gs)
  1529. {
  1530. const or_options_t *options = get_options();
  1531. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  1532. entry_guard_set_filtered_flags(options, gs, guard);
  1533. } SMARTLIST_FOREACH_END(guard);
  1534. }
  1535. /**
  1536. * Return a random guard from the reachable filtered sample guards
  1537. * in <b>gs</b>, subject to the exclusion rules listed in <b>flags</b>.
  1538. * Return NULL if no such guard can be found.
  1539. *
  1540. * Make sure that the sample is big enough, and that all the filter flags
  1541. * are set correctly, before calling this function.
  1542. *
  1543. * If a restriction is provided in <b>rst</b>, do not return any guards that
  1544. * violate it.
  1545. **/
  1546. STATIC entry_guard_t *
  1547. sample_reachable_filtered_entry_guards(guard_selection_t *gs,
  1548. const entry_guard_restriction_t *rst,
  1549. unsigned flags)
  1550. {
  1551. tor_assert(gs);
  1552. entry_guard_t *result = NULL;
  1553. const unsigned exclude_confirmed = flags & SAMPLE_EXCLUDE_CONFIRMED;
  1554. const unsigned exclude_primary = flags & SAMPLE_EXCLUDE_PRIMARY;
  1555. const unsigned exclude_pending = flags & SAMPLE_EXCLUDE_PENDING;
  1556. const unsigned no_update_primary = flags & SAMPLE_NO_UPDATE_PRIMARY;
  1557. const unsigned need_descriptor = flags & SAMPLE_EXCLUDE_NO_DESCRIPTOR;
  1558. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  1559. entry_guard_consider_retry(guard);
  1560. } SMARTLIST_FOREACH_END(guard);
  1561. const int n_reachable_filtered = num_reachable_filtered_guards(gs, rst);
  1562. log_info(LD_GUARD, "Trying to sample a reachable guard: We know of %d "
  1563. "in the USABLE_FILTERED set.", n_reachable_filtered);
  1564. const int min_filtered_sample = get_min_filtered_sample_size();
  1565. if (n_reachable_filtered < min_filtered_sample) {
  1566. log_info(LD_GUARD, " (That isn't enough. Trying to expand the sample.)");
  1567. entry_guards_expand_sample(gs);
  1568. }
  1569. if (exclude_primary && !gs->primary_guards_up_to_date && !no_update_primary)
  1570. entry_guards_update_primary(gs);
  1571. /* Build the set of reachable filtered guards. */
  1572. smartlist_t *reachable_filtered_sample = smartlist_new();
  1573. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  1574. entry_guard_consider_retry(guard);// redundant, but cheap.
  1575. if (! entry_guard_obeys_restriction(guard, rst))
  1576. continue;
  1577. if (! guard->is_usable_filtered_guard)
  1578. continue;
  1579. if (exclude_confirmed && guard->confirmed_idx >= 0)
  1580. continue;
  1581. if (exclude_primary && guard->is_primary)
  1582. continue;
  1583. if (exclude_pending && guard->is_pending)
  1584. continue;
  1585. if (need_descriptor && !guard_has_descriptor(guard))
  1586. continue;
  1587. smartlist_add(reachable_filtered_sample, guard);
  1588. } SMARTLIST_FOREACH_END(guard);
  1589. log_info(LD_GUARD, " (After filters [%x], we have %d guards to consider.)",
  1590. flags, smartlist_len(reachable_filtered_sample));
  1591. if (smartlist_len(reachable_filtered_sample)) {
  1592. result = smartlist_choose(reachable_filtered_sample);
  1593. log_info(LD_GUARD, " (Selected %s.)",
  1594. result ? entry_guard_describe(result) : "<null>");
  1595. }
  1596. smartlist_free(reachable_filtered_sample);
  1597. return result;
  1598. }
  1599. /**
  1600. * Helper: compare two entry_guard_t by their confirmed_idx values.
  1601. * Used to sort the confirmed list.
  1602. */
  1603. static int
  1604. compare_guards_by_confirmed_idx(const void **a_, const void **b_)
  1605. {
  1606. const entry_guard_t *a = *a_, *b = *b_;
  1607. if (a->confirmed_idx < b->confirmed_idx)
  1608. return -1;
  1609. else if (a->confirmed_idx > b->confirmed_idx)
  1610. return 1;
  1611. else
  1612. return 0;
  1613. }
  1614. /**
  1615. * Find the confirmed guards from among the sampled guards in <b>gs</b>,
  1616. * and put them in confirmed_entry_guards in the correct
  1617. * order. Recalculate their indices.
  1618. */
  1619. STATIC void
  1620. entry_guards_update_confirmed(guard_selection_t *gs)
  1621. {
  1622. smartlist_clear(gs->confirmed_entry_guards);
  1623. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  1624. if (guard->confirmed_idx >= 0)
  1625. smartlist_add(gs->confirmed_entry_guards, guard);
  1626. } SMARTLIST_FOREACH_END(guard);
  1627. smartlist_sort(gs->confirmed_entry_guards, compare_guards_by_confirmed_idx);
  1628. int any_changed = 0;
  1629. SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) {
  1630. if (guard->confirmed_idx != guard_sl_idx) {
  1631. any_changed = 1;
  1632. guard->confirmed_idx = guard_sl_idx;
  1633. }
  1634. } SMARTLIST_FOREACH_END(guard);
  1635. gs->next_confirmed_idx = smartlist_len(gs->confirmed_entry_guards);
  1636. if (any_changed) {
  1637. entry_guards_changed_for_guard_selection(gs);
  1638. }
  1639. }
  1640. /**
  1641. * Mark <b>guard</b> as a confirmed guard -- that is, one that we have
  1642. * connected to, and intend to use again.
  1643. */
  1644. STATIC void
  1645. make_guard_confirmed(guard_selection_t *gs, entry_guard_t *guard)
  1646. {
  1647. if (BUG(guard->confirmed_on_date && guard->confirmed_idx >= 0))
  1648. return; // LCOV_EXCL_LINE
  1649. if (BUG(smartlist_contains(gs->confirmed_entry_guards, guard)))
  1650. return; // LCOV_EXCL_LINE
  1651. const int GUARD_LIFETIME = get_guard_lifetime();
  1652. guard->confirmed_on_date = randomize_time(approx_time(), GUARD_LIFETIME/10);
  1653. log_info(LD_GUARD, "Marking %s as a confirmed guard (index %d)",
  1654. entry_guard_describe(guard),
  1655. gs->next_confirmed_idx);
  1656. guard->confirmed_idx = gs->next_confirmed_idx++;
  1657. smartlist_add(gs->confirmed_entry_guards, guard);
  1658. // This confirmed guard might kick something else out of the primary
  1659. // guards.
  1660. gs->primary_guards_up_to_date = 0;
  1661. entry_guards_changed_for_guard_selection(gs);
  1662. }
  1663. /**
  1664. * Recalculate the list of primary guards (the ones we'd prefer to use) from
  1665. * the filtered sample and the confirmed list.
  1666. */
  1667. STATIC void
  1668. entry_guards_update_primary(guard_selection_t *gs)
  1669. {
  1670. tor_assert(gs);
  1671. // prevent recursion. Recursion is potentially very bad here.
  1672. static int running = 0;
  1673. tor_assert(!running);
  1674. running = 1;
  1675. const int N_PRIMARY_GUARDS = get_n_primary_guards();
  1676. smartlist_t *new_primary_guards = smartlist_new();
  1677. smartlist_t *old_primary_guards = smartlist_new();
  1678. smartlist_add_all(old_primary_guards, gs->primary_entry_guards);
  1679. /* Set this flag now, to prevent the calls below from recursing. */
  1680. gs->primary_guards_up_to_date = 1;
  1681. /* First, can we fill it up with confirmed guards? */
  1682. SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) {
  1683. if (smartlist_len(new_primary_guards) >= N_PRIMARY_GUARDS)
  1684. break;
  1685. if (! guard->is_filtered_guard)
  1686. continue;
  1687. guard->is_primary = 1;
  1688. smartlist_add(new_primary_guards, guard);
  1689. } SMARTLIST_FOREACH_END(guard);
  1690. SMARTLIST_FOREACH_BEGIN(old_primary_guards, entry_guard_t *, guard) {
  1691. /* Can we keep any older primary guards? First remove all the ones
  1692. * that we already kept. */
  1693. if (smartlist_contains(new_primary_guards, guard)) {
  1694. SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard);
  1695. continue;
  1696. }
  1697. /* Now add any that are still good. */
  1698. if (smartlist_len(new_primary_guards) < N_PRIMARY_GUARDS &&
  1699. guard->is_filtered_guard) {
  1700. guard->is_primary = 1;
  1701. smartlist_add(new_primary_guards, guard);
  1702. SMARTLIST_DEL_CURRENT_KEEPORDER(old_primary_guards, guard);
  1703. } else {
  1704. /* Mark the remaining previous primary guards as non-primary */
  1705. guard->is_primary = 0;
  1706. }
  1707. } SMARTLIST_FOREACH_END(guard);
  1708. /* Finally, fill out the list with sampled guards. */
  1709. while (smartlist_len(new_primary_guards) < N_PRIMARY_GUARDS) {
  1710. entry_guard_t *guard = sample_reachable_filtered_entry_guards(gs, NULL,
  1711. SAMPLE_EXCLUDE_CONFIRMED|
  1712. SAMPLE_EXCLUDE_PRIMARY|
  1713. SAMPLE_NO_UPDATE_PRIMARY);
  1714. if (!guard)
  1715. break;
  1716. guard->is_primary = 1;
  1717. smartlist_add(new_primary_guards, guard);
  1718. }
  1719. #if 1
  1720. /* Debugging. */
  1721. SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, guard, {
  1722. tor_assert_nonfatal(
  1723. bool_eq(guard->is_primary,
  1724. smartlist_contains(new_primary_guards, guard)));
  1725. });
  1726. #endif /* 1 */
  1727. const int any_change = !smartlist_ptrs_eq(gs->primary_entry_guards,
  1728. new_primary_guards);
  1729. if (any_change) {
  1730. log_info(LD_GUARD, "Primary entry guards have changed. "
  1731. "New primary guard list is: ");
  1732. int n = smartlist_len(new_primary_guards);
  1733. SMARTLIST_FOREACH_BEGIN(new_primary_guards, entry_guard_t *, g) {
  1734. log_info(LD_GUARD, " %d/%d: %s%s%s",
  1735. g_sl_idx+1, n, entry_guard_describe(g),
  1736. g->confirmed_idx >= 0 ? " (confirmed)" : "",
  1737. g->is_filtered_guard ? "" : " (excluded by filter)");
  1738. } SMARTLIST_FOREACH_END(g);
  1739. }
  1740. smartlist_free(old_primary_guards);
  1741. smartlist_free(gs->primary_entry_guards);
  1742. gs->primary_entry_guards = new_primary_guards;
  1743. gs->primary_guards_up_to_date = 1;
  1744. running = 0;
  1745. }
  1746. /**
  1747. * Return the number of seconds after the last attempt at which we should
  1748. * retry a guard that has been failing since <b>failing_since</b>.
  1749. */
  1750. static int
  1751. get_retry_schedule(time_t failing_since, time_t now,
  1752. int is_primary)
  1753. {
  1754. const unsigned SIX_HOURS = 6 * 3600;
  1755. const unsigned FOUR_DAYS = 4 * 86400;
  1756. const unsigned SEVEN_DAYS = 7 * 86400;
  1757. time_t tdiff;
  1758. if (now > failing_since) {
  1759. tdiff = now - failing_since;
  1760. } else {
  1761. tdiff = 0;
  1762. }
  1763. const struct {
  1764. time_t maximum; int primary_delay; int nonprimary_delay;
  1765. } delays[] = {
  1766. { SIX_HOURS, 10*60, 1*60*60 },
  1767. { FOUR_DAYS, 90*60, 4*60*60 },
  1768. { SEVEN_DAYS, 4*60*60, 18*60*60 },
  1769. { TIME_MAX, 9*60*60, 36*60*60 }
  1770. };
  1771. unsigned i;
  1772. for (i = 0; i < ARRAY_LENGTH(delays); ++i) {
  1773. if (tdiff <= delays[i].maximum) {
  1774. return is_primary ? delays[i].primary_delay : delays[i].nonprimary_delay;
  1775. }
  1776. }
  1777. /* LCOV_EXCL_START -- can't reach, since delays ends with TIME_MAX. */
  1778. tor_assert_nonfatal_unreached();
  1779. return 36*60*60;
  1780. /* LCOV_EXCL_STOP */
  1781. }
  1782. /**
  1783. * If <b>guard</b> is unreachable, consider whether enough time has passed
  1784. * to consider it maybe-reachable again.
  1785. */
  1786. STATIC void
  1787. entry_guard_consider_retry(entry_guard_t *guard)
  1788. {
  1789. if (guard->is_reachable != GUARD_REACHABLE_NO)
  1790. return; /* No retry needed. */
  1791. const time_t now = approx_time();
  1792. const int delay =
  1793. get_retry_schedule(guard->failing_since, now, guard->is_primary);
  1794. const time_t last_attempt = guard->last_tried_to_connect;
  1795. if (BUG(last_attempt == 0) ||
  1796. now >= last_attempt + delay) {
  1797. /* We should mark this retriable. */
  1798. char tbuf[ISO_TIME_LEN+1];
  1799. format_local_iso_time(tbuf, last_attempt);
  1800. log_info(LD_GUARD, "Marked %s%sguard %s for possible retry, since we "
  1801. "haven't tried to use it since %s.",
  1802. guard->is_primary?"primary ":"",
  1803. guard->confirmed_idx>=0?"confirmed ":"",
  1804. entry_guard_describe(guard),
  1805. tbuf);
  1806. guard->is_reachable = GUARD_REACHABLE_MAYBE;
  1807. if (guard->is_filtered_guard)
  1808. guard->is_usable_filtered_guard = 1;
  1809. }
  1810. }
  1811. /** Tell the entry guards subsystem that we have confirmed that as of
  1812. * just now, we're on the internet. */
  1813. void
  1814. entry_guards_note_internet_connectivity(guard_selection_t *gs)
  1815. {
  1816. gs->last_time_on_internet = approx_time();
  1817. }
  1818. /**
  1819. * Pick a primary guard for use with a circuit, if available. Update the
  1820. * <b>last_tried_to_connect</b> time and the <b>is_pending</b> fields of the
  1821. * guard as appropriate. Set <b>state_out</b> to the new guard-state
  1822. * of the circuit.
  1823. */
  1824. static entry_guard_t *
  1825. select_primary_guard_for_circuit(guard_selection_t *gs,
  1826. guard_usage_t usage,
  1827. const entry_guard_restriction_t *rst,
  1828. unsigned *state_out)
  1829. {
  1830. const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC);
  1831. entry_guard_t *chosen_guard = NULL;
  1832. int num_entry_guards = get_n_primary_guards_to_use(usage);
  1833. smartlist_t *usable_primary_guards = smartlist_new();
  1834. SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) {
  1835. entry_guard_consider_retry(guard);
  1836. if (! entry_guard_obeys_restriction(guard, rst))
  1837. continue;
  1838. if (guard->is_reachable != GUARD_REACHABLE_NO) {
  1839. if (need_descriptor && !guard_has_descriptor(guard)) {
  1840. continue;
  1841. }
  1842. *state_out = GUARD_CIRC_STATE_USABLE_ON_COMPLETION;
  1843. guard->last_tried_to_connect = approx_time();
  1844. smartlist_add(usable_primary_guards, guard);
  1845. if (smartlist_len(usable_primary_guards) >= num_entry_guards)
  1846. break;
  1847. }
  1848. } SMARTLIST_FOREACH_END(guard);
  1849. if (smartlist_len(usable_primary_guards)) {
  1850. chosen_guard = smartlist_choose(usable_primary_guards);
  1851. smartlist_free(usable_primary_guards);
  1852. log_info(LD_GUARD, "Selected primary guard %s for circuit.",
  1853. entry_guard_describe(chosen_guard));
  1854. }
  1855. smartlist_free(usable_primary_guards);
  1856. return chosen_guard;
  1857. }
  1858. /**
  1859. * For use with a circuit, pick a non-pending running filtered confirmed guard,
  1860. * if one is available. Update the <b>last_tried_to_connect</b> time and the
  1861. * <b>is_pending</b> fields of the guard as appropriate. Set <b>state_out</b>
  1862. * to the new guard-state of the circuit.
  1863. */
  1864. static entry_guard_t *
  1865. select_confirmed_guard_for_circuit(guard_selection_t *gs,
  1866. guard_usage_t usage,
  1867. const entry_guard_restriction_t *rst,
  1868. unsigned *state_out)
  1869. {
  1870. const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC);
  1871. SMARTLIST_FOREACH_BEGIN(gs->confirmed_entry_guards, entry_guard_t *, guard) {
  1872. if (guard->is_primary)
  1873. continue; /* we already considered this one. */
  1874. if (! entry_guard_obeys_restriction(guard, rst))
  1875. continue;
  1876. entry_guard_consider_retry(guard);
  1877. if (guard->is_usable_filtered_guard && ! guard->is_pending) {
  1878. if (need_descriptor && !guard_has_descriptor(guard))
  1879. continue; /* not a bug */
  1880. guard->is_pending = 1;
  1881. guard->last_tried_to_connect = approx_time();
  1882. *state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD;
  1883. log_info(LD_GUARD, "No primary guards available. Selected confirmed "
  1884. "guard %s for circuit. Will try other guards before using "
  1885. "this circuit.",
  1886. entry_guard_describe(guard));
  1887. return guard;
  1888. }
  1889. } SMARTLIST_FOREACH_END(guard);
  1890. return NULL;
  1891. }
  1892. /**
  1893. * For use with a circuit, pick a confirmed usable filtered guard
  1894. * at random. Update the <b>last_tried_to_connect</b> time and the
  1895. * <b>is_pending</b> fields of the guard as appropriate. Set <b>state_out</b>
  1896. * to the new guard-state of the circuit.
  1897. */
  1898. static entry_guard_t *
  1899. select_filtered_guard_for_circuit(guard_selection_t *gs,
  1900. guard_usage_t usage,
  1901. const entry_guard_restriction_t *rst,
  1902. unsigned *state_out)
  1903. {
  1904. const int need_descriptor = (usage == GUARD_USAGE_TRAFFIC);
  1905. entry_guard_t *chosen_guard = NULL;
  1906. unsigned flags = 0;
  1907. if (need_descriptor)
  1908. flags |= SAMPLE_EXCLUDE_NO_DESCRIPTOR;
  1909. chosen_guard = sample_reachable_filtered_entry_guards(gs,
  1910. rst,
  1911. SAMPLE_EXCLUDE_CONFIRMED |
  1912. SAMPLE_EXCLUDE_PRIMARY |
  1913. SAMPLE_EXCLUDE_PENDING |
  1914. flags);
  1915. if (!chosen_guard) {
  1916. return NULL;
  1917. }
  1918. chosen_guard->is_pending = 1;
  1919. chosen_guard->last_tried_to_connect = approx_time();
  1920. *state_out = GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD;
  1921. log_info(LD_GUARD, "No primary or confirmed guards available. Selected "
  1922. "random guard %s for circuit. Will try other guards before "
  1923. "using this circuit.",
  1924. entry_guard_describe(chosen_guard));
  1925. return chosen_guard;
  1926. }
  1927. /**
  1928. * Get a guard for use with a circuit. Prefer to pick a running primary
  1929. * guard; then a non-pending running filtered confirmed guard; then a
  1930. * non-pending runnable filtered guard. Update the
  1931. * <b>last_tried_to_connect</b> time and the <b>is_pending</b> fields of the
  1932. * guard as appropriate. Set <b>state_out</b> to the new guard-state
  1933. * of the circuit.
  1934. */
  1935. STATIC entry_guard_t *
  1936. select_entry_guard_for_circuit(guard_selection_t *gs,
  1937. guard_usage_t usage,
  1938. const entry_guard_restriction_t *rst,
  1939. unsigned *state_out)
  1940. {
  1941. entry_guard_t *chosen_guard = NULL;
  1942. tor_assert(gs);
  1943. tor_assert(state_out);
  1944. if (!gs->primary_guards_up_to_date)
  1945. entry_guards_update_primary(gs);
  1946. /* "If any entry in PRIMARY_GUARDS has {is_reachable} status of
  1947. <maybe> or <yes>, return the first such guard." */
  1948. chosen_guard = select_primary_guard_for_circuit(gs, usage, rst, state_out);
  1949. if (chosen_guard)
  1950. return chosen_guard;
  1951. /* "Otherwise, if the ordered intersection of {CONFIRMED_GUARDS}
  1952. and {USABLE_FILTERED_GUARDS} is nonempty, return the first
  1953. entry in that intersection that has {is_pending} set to
  1954. false." */
  1955. chosen_guard = select_confirmed_guard_for_circuit(gs, usage, rst, state_out);
  1956. if (chosen_guard)
  1957. return chosen_guard;
  1958. /* "Otherwise, if there is no such entry, select a member at
  1959. random from {USABLE_FILTERED_GUARDS}." */
  1960. chosen_guard = select_filtered_guard_for_circuit(gs, usage, rst, state_out);
  1961. if (chosen_guard == NULL) {
  1962. log_info(LD_GUARD, "Absolutely no sampled guards were available. "
  1963. "Marking all guards for retry and starting from top again.");
  1964. mark_all_guards_maybe_reachable(gs);
  1965. return NULL;
  1966. }
  1967. return chosen_guard;
  1968. }
  1969. /**
  1970. * Note that we failed to connect to or build circuits through <b>guard</b>.
  1971. * Use with a guard returned by select_entry_guard_for_circuit().
  1972. */
  1973. STATIC void
  1974. entry_guards_note_guard_failure(guard_selection_t *gs,
  1975. entry_guard_t *guard)
  1976. {
  1977. tor_assert(gs);
  1978. guard->is_reachable = GUARD_REACHABLE_NO;
  1979. guard->is_usable_filtered_guard = 0;
  1980. guard->is_pending = 0;
  1981. if (guard->failing_since == 0)
  1982. guard->failing_since = approx_time();
  1983. log_info(LD_GUARD, "Recorded failure for %s%sguard %s",
  1984. guard->is_primary?"primary ":"",
  1985. guard->confirmed_idx>=0?"confirmed ":"",
  1986. entry_guard_describe(guard));
  1987. }
  1988. /**
  1989. * Note that we successfully connected to, and built a circuit through
  1990. * <b>guard</b>. Given the old guard-state of the circuit in <b>old_state</b>,
  1991. * return the new guard-state of the circuit.
  1992. *
  1993. * Be aware: the circuit is only usable when its guard-state becomes
  1994. * GUARD_CIRC_STATE_COMPLETE.
  1995. **/
  1996. STATIC unsigned
  1997. entry_guards_note_guard_success(guard_selection_t *gs,
  1998. entry_guard_t *guard,
  1999. unsigned old_state)
  2000. {
  2001. tor_assert(gs);
  2002. /* Save this, since we're about to overwrite it. */
  2003. const time_t last_time_on_internet = gs->last_time_on_internet;
  2004. gs->last_time_on_internet = approx_time();
  2005. guard->is_reachable = GUARD_REACHABLE_YES;
  2006. guard->failing_since = 0;
  2007. guard->is_pending = 0;
  2008. if (guard->is_filtered_guard)
  2009. guard->is_usable_filtered_guard = 1;
  2010. if (guard->confirmed_idx < 0) {
  2011. make_guard_confirmed(gs, guard);
  2012. if (!gs->primary_guards_up_to_date)
  2013. entry_guards_update_primary(gs);
  2014. }
  2015. unsigned new_state;
  2016. switch (old_state) {
  2017. case GUARD_CIRC_STATE_COMPLETE:
  2018. case GUARD_CIRC_STATE_USABLE_ON_COMPLETION:
  2019. new_state = GUARD_CIRC_STATE_COMPLETE;
  2020. break;
  2021. default:
  2022. tor_assert_nonfatal_unreached();
  2023. /* Fall through. */
  2024. case GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD:
  2025. if (guard->is_primary) {
  2026. /* XXXX #20832 -- I don't actually like this logic. It seems to make
  2027. * us a little more susceptible to evil-ISP attacks. The mitigations
  2028. * I'm thinking of, however, aren't local to this point, so I'll leave
  2029. * it alone. */
  2030. /* This guard may have become primary by virtue of being confirmed.
  2031. * If so, the circuit for it is now complete.
  2032. */
  2033. new_state = GUARD_CIRC_STATE_COMPLETE;
  2034. } else {
  2035. new_state = GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD;
  2036. }
  2037. break;
  2038. }
  2039. if (! guard->is_primary) {
  2040. if (last_time_on_internet + get_internet_likely_down_interval()
  2041. < approx_time()) {
  2042. mark_primary_guards_maybe_reachable(gs);
  2043. }
  2044. }
  2045. log_info(LD_GUARD, "Recorded success for %s%sguard %s",
  2046. guard->is_primary?"primary ":"",
  2047. guard->confirmed_idx>=0?"confirmed ":"",
  2048. entry_guard_describe(guard));
  2049. return new_state;
  2050. }
  2051. /**
  2052. * Helper: Return true iff <b>a</b> has higher priority than <b>b</b>.
  2053. */
  2054. STATIC int
  2055. entry_guard_has_higher_priority(entry_guard_t *a, entry_guard_t *b)
  2056. {
  2057. tor_assert(a && b);
  2058. if (a == b)
  2059. return 0;
  2060. /* Confirmed is always better than unconfirmed; lower index better
  2061. than higher */
  2062. if (a->confirmed_idx < 0) {
  2063. if (b->confirmed_idx >= 0)
  2064. return 0;
  2065. } else {
  2066. if (b->confirmed_idx < 0)
  2067. return 1;
  2068. /* Lower confirmed_idx is better than higher. */
  2069. return (a->confirmed_idx < b->confirmed_idx);
  2070. }
  2071. /* If we reach this point, both are unconfirmed. If one is pending, it
  2072. * has higher priority. */
  2073. if (a->is_pending) {
  2074. if (! b->is_pending)
  2075. return 1;
  2076. /* Both are pending: earlier last_tried_connect wins. */
  2077. return a->last_tried_to_connect < b->last_tried_to_connect;
  2078. } else {
  2079. if (b->is_pending)
  2080. return 0;
  2081. /* Neither is pending: priorities are equal. */
  2082. return 0;
  2083. }
  2084. }
  2085. /** Release all storage held in <b>restriction</b> */
  2086. STATIC void
  2087. entry_guard_restriction_free_(entry_guard_restriction_t *rst)
  2088. {
  2089. tor_free(rst);
  2090. }
  2091. /**
  2092. * Release all storage held in <b>state</b>.
  2093. */
  2094. void
  2095. circuit_guard_state_free_(circuit_guard_state_t *state)
  2096. {
  2097. if (!state)
  2098. return;
  2099. entry_guard_restriction_free(state->restrictions);
  2100. entry_guard_handle_free(state->guard);
  2101. tor_free(state);
  2102. }
  2103. /** Allocate and return a new circuit_guard_state_t to track the result
  2104. * of using <b>guard</b> for a given operation. */
  2105. MOCK_IMPL(STATIC circuit_guard_state_t *,
  2106. circuit_guard_state_new,(entry_guard_t *guard, unsigned state,
  2107. entry_guard_restriction_t *rst))
  2108. {
  2109. circuit_guard_state_t *result;
  2110. result = tor_malloc_zero(sizeof(circuit_guard_state_t));
  2111. result->guard = entry_guard_handle_new(guard);
  2112. result->state = state;
  2113. result->state_set_at = approx_time();
  2114. result->restrictions = rst;
  2115. return result;
  2116. }
  2117. /**
  2118. * Pick a suitable entry guard for a circuit in, and place that guard
  2119. * in *<b>chosen_node_out</b>. Set *<b>guard_state_out</b> to an opaque
  2120. * state object that will record whether the circuit is ready to be used
  2121. * or not. Return 0 on success; on failure, return -1.
  2122. *
  2123. * If a restriction is provided in <b>rst</b>, do not return any guards that
  2124. * violate it, and remember that restriction in <b>guard_state_out</b> for
  2125. * later use. (Takes ownership of the <b>rst</b> object.)
  2126. */
  2127. int
  2128. entry_guard_pick_for_circuit(guard_selection_t *gs,
  2129. guard_usage_t usage,
  2130. entry_guard_restriction_t *rst,
  2131. const node_t **chosen_node_out,
  2132. circuit_guard_state_t **guard_state_out)
  2133. {
  2134. tor_assert(gs);
  2135. tor_assert(chosen_node_out);
  2136. tor_assert(guard_state_out);
  2137. *chosen_node_out = NULL;
  2138. *guard_state_out = NULL;
  2139. unsigned state = 0;
  2140. entry_guard_t *guard =
  2141. select_entry_guard_for_circuit(gs, usage, rst, &state);
  2142. if (! guard)
  2143. goto fail;
  2144. if (BUG(state == 0))
  2145. goto fail;
  2146. const node_t *node = node_get_by_id(guard->identity);
  2147. // XXXX #20827 check Ed ID.
  2148. if (! node)
  2149. goto fail;
  2150. if (BUG(usage != GUARD_USAGE_DIRGUARD &&
  2151. !node_has_preferred_descriptor(node, 1)))
  2152. goto fail;
  2153. *chosen_node_out = node;
  2154. *guard_state_out = circuit_guard_state_new(guard, state, rst);
  2155. return 0;
  2156. fail:
  2157. entry_guard_restriction_free(rst);
  2158. return -1;
  2159. }
  2160. /**
  2161. * Called by the circuit building module when a circuit has succeeded: informs
  2162. * the guards code that the guard in *<b>guard_state_p</b> is working, and
  2163. * advances the state of the guard module. On a GUARD_USABLE_NEVER return
  2164. * value, the circuit is broken and should not be used. On a GUARD_USABLE_NOW
  2165. * return value, the circuit is ready to use. On a GUARD_MAYBE_USABLE_LATER
  2166. * return value, the circuit should not be used until we find out whether
  2167. * preferred guards will work for us.
  2168. */
  2169. guard_usable_t
  2170. entry_guard_succeeded(circuit_guard_state_t **guard_state_p)
  2171. {
  2172. if (BUG(*guard_state_p == NULL))
  2173. return GUARD_USABLE_NEVER;
  2174. entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard);
  2175. if (! guard || BUG(guard->in_selection == NULL))
  2176. return GUARD_USABLE_NEVER;
  2177. unsigned newstate =
  2178. entry_guards_note_guard_success(guard->in_selection, guard,
  2179. (*guard_state_p)->state);
  2180. (*guard_state_p)->state = newstate;
  2181. (*guard_state_p)->state_set_at = approx_time();
  2182. if (newstate == GUARD_CIRC_STATE_COMPLETE) {
  2183. return GUARD_USABLE_NOW;
  2184. } else {
  2185. return GUARD_MAYBE_USABLE_LATER;
  2186. }
  2187. }
  2188. /** Cancel the selection of *<b>guard_state_p</b> without declaring
  2189. * success or failure. It is safe to call this function if success or
  2190. * failure _has_ already been declared. */
  2191. void
  2192. entry_guard_cancel(circuit_guard_state_t **guard_state_p)
  2193. {
  2194. if (BUG(*guard_state_p == NULL))
  2195. return;
  2196. entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard);
  2197. if (! guard)
  2198. return;
  2199. /* XXXX prop271 -- last_tried_to_connect_at will be erroneous here, but this
  2200. * function will only get called in "bug" cases anyway. */
  2201. guard->is_pending = 0;
  2202. circuit_guard_state_free(*guard_state_p);
  2203. *guard_state_p = NULL;
  2204. }
  2205. /**
  2206. * Called by the circuit building module when a circuit has failed:
  2207. * informs the guards code that the guard in *<b>guard_state_p</b> is
  2208. * not working, and advances the state of the guard module.
  2209. */
  2210. void
  2211. entry_guard_failed(circuit_guard_state_t **guard_state_p)
  2212. {
  2213. if (BUG(*guard_state_p == NULL))
  2214. return;
  2215. entry_guard_t *guard = entry_guard_handle_get((*guard_state_p)->guard);
  2216. if (! guard || BUG(guard->in_selection == NULL))
  2217. return;
  2218. entry_guards_note_guard_failure(guard->in_selection, guard);
  2219. (*guard_state_p)->state = GUARD_CIRC_STATE_DEAD;
  2220. (*guard_state_p)->state_set_at = approx_time();
  2221. }
  2222. /**
  2223. * Run the entry_guard_failed() function on every circuit that is
  2224. * pending on <b>chan</b>.
  2225. */
  2226. void
  2227. entry_guard_chan_failed(channel_t *chan)
  2228. {
  2229. if (!chan)
  2230. return;
  2231. smartlist_t *pending = smartlist_new();
  2232. circuit_get_all_pending_on_channel(pending, chan);
  2233. SMARTLIST_FOREACH_BEGIN(pending, circuit_t *, circ) {
  2234. if (!CIRCUIT_IS_ORIGIN(circ))
  2235. continue;
  2236. origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
  2237. if (origin_circ->guard_state) {
  2238. /* We might have no guard state if we didn't use a guard on this
  2239. * circuit (eg it's for a fallback directory). */
  2240. entry_guard_failed(&origin_circ->guard_state);
  2241. }
  2242. } SMARTLIST_FOREACH_END(circ);
  2243. smartlist_free(pending);
  2244. }
  2245. /**
  2246. * Return true iff every primary guard in <b>gs</b> is believed to
  2247. * be unreachable.
  2248. */
  2249. STATIC int
  2250. entry_guards_all_primary_guards_are_down(guard_selection_t *gs)
  2251. {
  2252. tor_assert(gs);
  2253. if (!gs->primary_guards_up_to_date)
  2254. entry_guards_update_primary(gs);
  2255. SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) {
  2256. entry_guard_consider_retry(guard);
  2257. if (guard->is_reachable != GUARD_REACHABLE_NO)
  2258. return 0;
  2259. } SMARTLIST_FOREACH_END(guard);
  2260. return 1;
  2261. }
  2262. /** Wrapper for entry_guard_has_higher_priority that compares the
  2263. * guard-priorities of a pair of circuits. Return 1 if <b>a</b> has higher
  2264. * priority than <b>b</b>.
  2265. *
  2266. * If a restriction is provided in <b>rst</b>, then do not consider
  2267. * <b>a</b> to have higher priority if it violates the restriction.
  2268. */
  2269. static int
  2270. circ_state_has_higher_priority(origin_circuit_t *a,
  2271. const entry_guard_restriction_t *rst,
  2272. origin_circuit_t *b)
  2273. {
  2274. circuit_guard_state_t *state_a = origin_circuit_get_guard_state(a);
  2275. circuit_guard_state_t *state_b = origin_circuit_get_guard_state(b);
  2276. tor_assert(state_a);
  2277. tor_assert(state_b);
  2278. entry_guard_t *guard_a = entry_guard_handle_get(state_a->guard);
  2279. entry_guard_t *guard_b = entry_guard_handle_get(state_b->guard);
  2280. if (! guard_a) {
  2281. /* Unknown guard -- never higher priority. */
  2282. return 0;
  2283. } else if (! guard_b) {
  2284. /* Known guard -- higher priority than any unknown guard. */
  2285. return 1;
  2286. } else if (! entry_guard_obeys_restriction(guard_a, rst)) {
  2287. /* Restriction violated; guard_a cannot have higher priority. */
  2288. return 0;
  2289. } else {
  2290. /* Both known -- compare.*/
  2291. return entry_guard_has_higher_priority(guard_a, guard_b);
  2292. }
  2293. }
  2294. /**
  2295. * Look at all of the origin_circuit_t * objects in <b>all_circuits_in</b>,
  2296. * and see if any of them that were previously not ready to use for
  2297. * guard-related reasons are now ready to use. Place those circuits
  2298. * in <b>newly_complete_out</b>, and mark them COMPLETE.
  2299. *
  2300. * Return 1 if we upgraded any circuits, and 0 otherwise.
  2301. */
  2302. int
  2303. entry_guards_upgrade_waiting_circuits(guard_selection_t *gs,
  2304. const smartlist_t *all_circuits_in,
  2305. smartlist_t *newly_complete_out)
  2306. {
  2307. tor_assert(gs);
  2308. tor_assert(all_circuits_in);
  2309. tor_assert(newly_complete_out);
  2310. if (! entry_guards_all_primary_guards_are_down(gs)) {
  2311. /* We only upgrade a waiting circuit if the primary guards are all
  2312. * down. */
  2313. log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, "
  2314. "but not all primary guards were definitely down.");
  2315. return 0;
  2316. }
  2317. int n_waiting = 0;
  2318. int n_complete = 0;
  2319. int n_complete_blocking = 0;
  2320. origin_circuit_t *best_waiting_circuit = NULL;
  2321. smartlist_t *all_circuits = smartlist_new();
  2322. SMARTLIST_FOREACH_BEGIN(all_circuits_in, origin_circuit_t *, circ) {
  2323. // We filter out circuits that aren't ours, or which we can't
  2324. // reason about.
  2325. circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
  2326. if (state == NULL)
  2327. continue;
  2328. entry_guard_t *guard = entry_guard_handle_get(state->guard);
  2329. if (!guard || guard->in_selection != gs)
  2330. continue;
  2331. if (TO_CIRCUIT(circ)->marked_for_close) {
  2332. /* Don't consider any marked for close circuits. */
  2333. continue;
  2334. }
  2335. smartlist_add(all_circuits, circ);
  2336. } SMARTLIST_FOREACH_END(circ);
  2337. SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
  2338. circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
  2339. if (BUG(state == NULL))
  2340. continue;
  2341. if (state->state == GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD) {
  2342. ++n_waiting;
  2343. if (! best_waiting_circuit ||
  2344. circ_state_has_higher_priority(circ, NULL, best_waiting_circuit)) {
  2345. best_waiting_circuit = circ;
  2346. }
  2347. }
  2348. } SMARTLIST_FOREACH_END(circ);
  2349. if (! best_waiting_circuit) {
  2350. log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits, "
  2351. "but didn't find any.");
  2352. goto no_change;
  2353. }
  2354. /* We'll need to keep track of what restrictions were used when picking this
  2355. * circuit, so that we don't allow any circuit without those restrictions to
  2356. * block it. */
  2357. const entry_guard_restriction_t *rst_on_best_waiting =
  2358. origin_circuit_get_guard_state(best_waiting_circuit)->restrictions;
  2359. /* First look at the complete circuits: Do any block this circuit? */
  2360. SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
  2361. /* "C2 "blocks" C1 if:
  2362. * C2 obeys all the restrictions that C1 had to obey, AND
  2363. * C2 has higher priority than C1, AND
  2364. * Either C2 is <complete>, or C2 is <waiting_for_better_guard>,
  2365. or C2 has been <usable_if_no_better_guard> for no more than
  2366. {NONPRIMARY_GUARD_CONNECT_TIMEOUT} seconds."
  2367. */
  2368. circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
  2369. if BUG((state == NULL))
  2370. continue;
  2371. if (state->state != GUARD_CIRC_STATE_COMPLETE)
  2372. continue;
  2373. ++n_complete;
  2374. if (circ_state_has_higher_priority(circ, rst_on_best_waiting,
  2375. best_waiting_circuit))
  2376. ++n_complete_blocking;
  2377. } SMARTLIST_FOREACH_END(circ);
  2378. if (n_complete_blocking) {
  2379. log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
  2380. "%d complete and %d guard-stalled. At least one complete "
  2381. "circuit had higher priority, so not upgrading.",
  2382. n_complete, n_waiting);
  2383. goto no_change;
  2384. }
  2385. /* " * If any circuit C1 is <waiting_for_better_guard>, AND:
  2386. * All primary guards have reachable status of <no>.
  2387. * There is no circuit C2 that "blocks" C1.
  2388. Then, upgrade C1 to <complete>.""
  2389. */
  2390. int n_blockers_found = 0;
  2391. const time_t state_set_at_cutoff =
  2392. approx_time() - get_nonprimary_guard_connect_timeout();
  2393. SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
  2394. circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
  2395. if (BUG(state == NULL))
  2396. continue;
  2397. if (state->state != GUARD_CIRC_STATE_USABLE_IF_NO_BETTER_GUARD)
  2398. continue;
  2399. if (state->state_set_at <= state_set_at_cutoff)
  2400. continue;
  2401. if (circ_state_has_higher_priority(circ, rst_on_best_waiting,
  2402. best_waiting_circuit))
  2403. ++n_blockers_found;
  2404. } SMARTLIST_FOREACH_END(circ);
  2405. if (n_blockers_found) {
  2406. log_debug(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
  2407. "%d guard-stalled, but %d pending circuit(s) had higher "
  2408. "guard priority, so not upgrading.",
  2409. n_waiting, n_blockers_found);
  2410. goto no_change;
  2411. }
  2412. /* Okay. We have a best waiting circuit, and we aren't waiting for
  2413. anything better. Add all circuits with that priority to the
  2414. list, and call them COMPLETE. */
  2415. int n_succeeded = 0;
  2416. SMARTLIST_FOREACH_BEGIN(all_circuits, origin_circuit_t *, circ) {
  2417. circuit_guard_state_t *state = origin_circuit_get_guard_state(circ);
  2418. if (BUG(state == NULL))
  2419. continue;
  2420. if (circ != best_waiting_circuit && rst_on_best_waiting) {
  2421. /* Can't upgrade other circ with same priority as best; might
  2422. be blocked. */
  2423. continue;
  2424. }
  2425. if (state->state != GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD)
  2426. continue;
  2427. if (circ_state_has_higher_priority(best_waiting_circuit, NULL, circ))
  2428. continue;
  2429. state->state = GUARD_CIRC_STATE_COMPLETE;
  2430. state->state_set_at = approx_time();
  2431. smartlist_add(newly_complete_out, circ);
  2432. ++n_succeeded;
  2433. } SMARTLIST_FOREACH_END(circ);
  2434. log_info(LD_GUARD, "Considered upgrading guard-stalled circuits: found "
  2435. "%d guard-stalled, %d complete. %d of the guard-stalled "
  2436. "circuit(s) had high enough priority to upgrade.",
  2437. n_waiting, n_complete, n_succeeded);
  2438. tor_assert_nonfatal(n_succeeded >= 1);
  2439. smartlist_free(all_circuits);
  2440. return 1;
  2441. no_change:
  2442. smartlist_free(all_circuits);
  2443. return 0;
  2444. }
  2445. /**
  2446. * Return true iff the circuit whose state is <b>guard_state</b> should
  2447. * expire.
  2448. */
  2449. int
  2450. entry_guard_state_should_expire(circuit_guard_state_t *guard_state)
  2451. {
  2452. if (guard_state == NULL)
  2453. return 0;
  2454. const time_t expire_if_waiting_since =
  2455. approx_time() - get_nonprimary_guard_idle_timeout();
  2456. return (guard_state->state == GUARD_CIRC_STATE_WAITING_FOR_BETTER_GUARD
  2457. && guard_state->state_set_at < expire_if_waiting_since);
  2458. }
  2459. /**
  2460. * Update all derived pieces of the guard selection state in <b>gs</b>.
  2461. * Return true iff we should stop using all previously generated circuits.
  2462. */
  2463. int
  2464. entry_guards_update_all(guard_selection_t *gs)
  2465. {
  2466. sampled_guards_update_from_consensus(gs);
  2467. entry_guards_update_filtered_sets(gs);
  2468. entry_guards_update_confirmed(gs);
  2469. entry_guards_update_primary(gs);
  2470. return 0;
  2471. }
  2472. /**
  2473. * Return a newly allocated string for encoding the persistent parts of
  2474. * <b>guard</b> to the state file.
  2475. */
  2476. STATIC char *
  2477. entry_guard_encode_for_state(entry_guard_t *guard)
  2478. {
  2479. /*
  2480. * The meta-format we use is K=V K=V K=V... where K can be any
  2481. * characters excepts space and =, and V can be any characters except
  2482. * space. The order of entries is not allowed to matter.
  2483. * Unrecognized K=V entries are persisted; recognized but erroneous
  2484. * entries are corrected.
  2485. */
  2486. smartlist_t *result = smartlist_new();
  2487. char tbuf[ISO_TIME_LEN+1];
  2488. tor_assert(guard);
  2489. smartlist_add_asprintf(result, "in=%s", guard->selection_name);
  2490. smartlist_add_asprintf(result, "rsa_id=%s",
  2491. hex_str(guard->identity, DIGEST_LEN));
  2492. if (guard->bridge_addr) {
  2493. smartlist_add_asprintf(result, "bridge_addr=%s:%d",
  2494. fmt_and_decorate_addr(&guard->bridge_addr->addr),
  2495. guard->bridge_addr->port);
  2496. }
  2497. if (strlen(guard->nickname) && is_legal_nickname(guard->nickname)) {
  2498. smartlist_add_asprintf(result, "nickname=%s", guard->nickname);
  2499. }
  2500. format_iso_time_nospace(tbuf, guard->sampled_on_date);
  2501. smartlist_add_asprintf(result, "sampled_on=%s", tbuf);
  2502. if (guard->sampled_by_version) {
  2503. smartlist_add_asprintf(result, "sampled_by=%s",
  2504. guard->sampled_by_version);
  2505. }
  2506. if (guard->unlisted_since_date > 0) {
  2507. format_iso_time_nospace(tbuf, guard->unlisted_since_date);
  2508. smartlist_add_asprintf(result, "unlisted_since=%s", tbuf);
  2509. }
  2510. smartlist_add_asprintf(result, "listed=%d",
  2511. (int)guard->currently_listed);
  2512. if (guard->confirmed_idx >= 0) {
  2513. format_iso_time_nospace(tbuf, guard->confirmed_on_date);
  2514. smartlist_add_asprintf(result, "confirmed_on=%s", tbuf);
  2515. smartlist_add_asprintf(result, "confirmed_idx=%d", guard->confirmed_idx);
  2516. }
  2517. const double EPSILON = 1.0e-6;
  2518. /* Make a copy of the pathbias object, since we will want to update
  2519. some of them */
  2520. guard_pathbias_t *pb = tor_memdup(&guard->pb, sizeof(*pb));
  2521. pb->use_successes = pathbias_get_use_success_count(guard);
  2522. pb->successful_circuits_closed = pathbias_get_close_success_count(guard);
  2523. #define PB_FIELD(field) do { \
  2524. if (pb->field >= EPSILON) { \
  2525. smartlist_add_asprintf(result, "pb_" #field "=%f", pb->field); \
  2526. } \
  2527. } while (0)
  2528. PB_FIELD(use_attempts);
  2529. PB_FIELD(use_successes);
  2530. PB_FIELD(circ_attempts);
  2531. PB_FIELD(circ_successes);
  2532. PB_FIELD(successful_circuits_closed);
  2533. PB_FIELD(collapsed_circuits);
  2534. PB_FIELD(unusable_circuits);
  2535. PB_FIELD(timeouts);
  2536. tor_free(pb);
  2537. #undef PB_FIELD
  2538. if (guard->extra_state_fields)
  2539. smartlist_add_strdup(result, guard->extra_state_fields);
  2540. char *joined = smartlist_join_strings(result, " ", 0, NULL);
  2541. SMARTLIST_FOREACH(result, char *, cp, tor_free(cp));
  2542. smartlist_free(result);
  2543. return joined;
  2544. }
  2545. /**
  2546. * Given a string generated by entry_guard_encode_for_state(), parse it
  2547. * (if possible) and return an entry_guard_t object for it. Return NULL
  2548. * on complete failure.
  2549. */
  2550. STATIC entry_guard_t *
  2551. entry_guard_parse_from_state(const char *s)
  2552. {
  2553. /* Unrecognized entries get put in here. */
  2554. smartlist_t *extra = smartlist_new();
  2555. /* These fields get parsed from the string. */
  2556. char *in = NULL;
  2557. char *rsa_id = NULL;
  2558. char *nickname = NULL;
  2559. char *sampled_on = NULL;
  2560. char *sampled_by = NULL;
  2561. char *unlisted_since = NULL;
  2562. char *listed = NULL;
  2563. char *confirmed_on = NULL;
  2564. char *confirmed_idx = NULL;
  2565. char *bridge_addr = NULL;
  2566. // pathbias
  2567. char *pb_use_attempts = NULL;
  2568. char *pb_use_successes = NULL;
  2569. char *pb_circ_attempts = NULL;
  2570. char *pb_circ_successes = NULL;
  2571. char *pb_successful_circuits_closed = NULL;
  2572. char *pb_collapsed_circuits = NULL;
  2573. char *pb_unusable_circuits = NULL;
  2574. char *pb_timeouts = NULL;
  2575. /* Split up the entries. Put the ones we know about in strings and the
  2576. * rest in "extra". */
  2577. {
  2578. smartlist_t *entries = smartlist_new();
  2579. strmap_t *vals = strmap_new(); // Maps keyword to location
  2580. #define FIELD(f) \
  2581. strmap_set(vals, #f, &f);
  2582. FIELD(in);
  2583. FIELD(rsa_id);
  2584. FIELD(nickname);
  2585. FIELD(sampled_on);
  2586. FIELD(sampled_by);
  2587. FIELD(unlisted_since);
  2588. FIELD(listed);
  2589. FIELD(confirmed_on);
  2590. FIELD(confirmed_idx);
  2591. FIELD(bridge_addr);
  2592. FIELD(pb_use_attempts);
  2593. FIELD(pb_use_successes);
  2594. FIELD(pb_circ_attempts);
  2595. FIELD(pb_circ_successes);
  2596. FIELD(pb_successful_circuits_closed);
  2597. FIELD(pb_collapsed_circuits);
  2598. FIELD(pb_unusable_circuits);
  2599. FIELD(pb_timeouts);
  2600. #undef FIELD
  2601. smartlist_split_string(entries, s, " ",
  2602. SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
  2603. SMARTLIST_FOREACH_BEGIN(entries, char *, entry) {
  2604. const char *eq = strchr(entry, '=');
  2605. if (!eq) {
  2606. smartlist_add(extra, entry);
  2607. continue;
  2608. }
  2609. char *key = tor_strndup(entry, eq-entry);
  2610. char **target = strmap_get(vals, key);
  2611. if (target == NULL || *target != NULL) {
  2612. /* unrecognized or already set */
  2613. smartlist_add(extra, entry);
  2614. tor_free(key);
  2615. continue;
  2616. }
  2617. *target = tor_strdup(eq+1);
  2618. tor_free(key);
  2619. tor_free(entry);
  2620. } SMARTLIST_FOREACH_END(entry);
  2621. smartlist_free(entries);
  2622. strmap_free(vals, NULL);
  2623. }
  2624. entry_guard_t *guard = tor_malloc_zero(sizeof(entry_guard_t));
  2625. guard->is_persistent = 1;
  2626. if (in == NULL) {
  2627. log_warn(LD_CIRC, "Guard missing 'in' field");
  2628. goto err;
  2629. }
  2630. guard->selection_name = in;
  2631. in = NULL;
  2632. if (rsa_id == NULL) {
  2633. log_warn(LD_CIRC, "Guard missing RSA ID field");
  2634. goto err;
  2635. }
  2636. /* Process the identity and nickname. */
  2637. if (base16_decode(guard->identity, sizeof(guard->identity),
  2638. rsa_id, strlen(rsa_id)) != DIGEST_LEN) {
  2639. log_warn(LD_CIRC, "Unable to decode guard identity %s", escaped(rsa_id));
  2640. goto err;
  2641. }
  2642. if (nickname) {
  2643. strlcpy(guard->nickname, nickname, sizeof(guard->nickname));
  2644. } else {
  2645. guard->nickname[0]='$';
  2646. base16_encode(guard->nickname+1, sizeof(guard->nickname)-1,
  2647. guard->identity, DIGEST_LEN);
  2648. }
  2649. if (bridge_addr) {
  2650. tor_addr_port_t res;
  2651. memset(&res, 0, sizeof(res));
  2652. int r = tor_addr_port_parse(LOG_WARN, bridge_addr,
  2653. &res.addr, &res.port, -1);
  2654. if (r == 0)
  2655. guard->bridge_addr = tor_memdup(&res, sizeof(res));
  2656. /* On error, we already warned. */
  2657. }
  2658. /* Process the various time fields. */
  2659. #define HANDLE_TIME(field) do { \
  2660. if (field) { \
  2661. int r = parse_iso_time_nospace(field, &field ## _time); \
  2662. if (r < 0) { \
  2663. log_warn(LD_CIRC, "Unable to parse %s %s from guard", \
  2664. #field, escaped(field)); \
  2665. field##_time = -1; \
  2666. } \
  2667. } \
  2668. } while (0)
  2669. time_t sampled_on_time = 0;
  2670. time_t unlisted_since_time = 0;
  2671. time_t confirmed_on_time = 0;
  2672. HANDLE_TIME(sampled_on);
  2673. HANDLE_TIME(unlisted_since);
  2674. HANDLE_TIME(confirmed_on);
  2675. if (sampled_on_time <= 0)
  2676. sampled_on_time = approx_time();
  2677. if (unlisted_since_time < 0)
  2678. unlisted_since_time = 0;
  2679. if (confirmed_on_time < 0)
  2680. confirmed_on_time = 0;
  2681. #undef HANDLE_TIME
  2682. guard->sampled_on_date = sampled_on_time;
  2683. guard->unlisted_since_date = unlisted_since_time;
  2684. guard->confirmed_on_date = confirmed_on_time;
  2685. /* Take sampled_by_version verbatim. */
  2686. guard->sampled_by_version = sampled_by;
  2687. sampled_by = NULL; /* prevent free */
  2688. /* Listed is a boolean */
  2689. if (listed && strcmp(listed, "0"))
  2690. guard->currently_listed = 1;
  2691. /* The index is a nonnegative integer. */
  2692. guard->confirmed_idx = -1;
  2693. if (confirmed_idx) {
  2694. int ok=1;
  2695. long idx = tor_parse_long(confirmed_idx, 10, 0, INT_MAX, &ok, NULL);
  2696. if (! ok) {
  2697. log_warn(LD_GUARD, "Guard has invalid confirmed_idx %s",
  2698. escaped(confirmed_idx));
  2699. } else {
  2700. guard->confirmed_idx = (int)idx;
  2701. }
  2702. }
  2703. /* Anything we didn't recognize gets crammed together */
  2704. if (smartlist_len(extra) > 0) {
  2705. guard->extra_state_fields = smartlist_join_strings(extra, " ", 0, NULL);
  2706. }
  2707. /* initialize non-persistent fields */
  2708. guard->is_reachable = GUARD_REACHABLE_MAYBE;
  2709. #define PB_FIELD(field) \
  2710. do { \
  2711. if (pb_ ## field) { \
  2712. int ok = 1; \
  2713. double r = tor_parse_double(pb_ ## field, 0.0, 1e9, &ok, NULL); \
  2714. if (! ok) { \
  2715. log_warn(LD_CIRC, "Guard has invalid pb_%s %s", \
  2716. #field, pb_ ## field); \
  2717. } else { \
  2718. guard->pb.field = r; \
  2719. } \
  2720. } \
  2721. } while (0)
  2722. PB_FIELD(use_attempts);
  2723. PB_FIELD(use_successes);
  2724. PB_FIELD(circ_attempts);
  2725. PB_FIELD(circ_successes);
  2726. PB_FIELD(successful_circuits_closed);
  2727. PB_FIELD(collapsed_circuits);
  2728. PB_FIELD(unusable_circuits);
  2729. PB_FIELD(timeouts);
  2730. #undef PB_FIELD
  2731. pathbias_check_use_success_count(guard);
  2732. pathbias_check_close_success_count(guard);
  2733. /* We update everything on this guard later, after we've parsed
  2734. * everything. */
  2735. goto done;
  2736. err:
  2737. // only consider it an error if the guard state was totally unparseable.
  2738. entry_guard_free(guard);
  2739. guard = NULL;
  2740. done:
  2741. tor_free(in);
  2742. tor_free(rsa_id);
  2743. tor_free(nickname);
  2744. tor_free(sampled_on);
  2745. tor_free(sampled_by);
  2746. tor_free(unlisted_since);
  2747. tor_free(listed);
  2748. tor_free(confirmed_on);
  2749. tor_free(confirmed_idx);
  2750. tor_free(bridge_addr);
  2751. tor_free(pb_use_attempts);
  2752. tor_free(pb_use_successes);
  2753. tor_free(pb_circ_attempts);
  2754. tor_free(pb_circ_successes);
  2755. tor_free(pb_successful_circuits_closed);
  2756. tor_free(pb_collapsed_circuits);
  2757. tor_free(pb_unusable_circuits);
  2758. tor_free(pb_timeouts);
  2759. SMARTLIST_FOREACH(extra, char *, cp, tor_free(cp));
  2760. smartlist_free(extra);
  2761. return guard;
  2762. }
  2763. /**
  2764. * Replace the Guards entries in <b>state</b> with a list of all our sampled
  2765. * guards.
  2766. */
  2767. static void
  2768. entry_guards_update_guards_in_state(or_state_t *state)
  2769. {
  2770. if (!guard_contexts)
  2771. return;
  2772. config_line_t *lines = NULL;
  2773. config_line_t **nextline = &lines;
  2774. SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
  2775. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  2776. if (guard->is_persistent == 0)
  2777. continue;
  2778. *nextline = tor_malloc_zero(sizeof(config_line_t));
  2779. (*nextline)->key = tor_strdup("Guard");
  2780. (*nextline)->value = entry_guard_encode_for_state(guard);
  2781. nextline = &(*nextline)->next;
  2782. } SMARTLIST_FOREACH_END(guard);
  2783. } SMARTLIST_FOREACH_END(gs);
  2784. config_free_lines(state->Guard);
  2785. state->Guard = lines;
  2786. }
  2787. /**
  2788. * Replace our sampled guards from the Guards entries in <b>state</b>. Return 0
  2789. * on success, -1 on failure. (If <b>set</b> is true, replace nothing -- only
  2790. * check whether replacing would work.)
  2791. */
  2792. static int
  2793. entry_guards_load_guards_from_state(or_state_t *state, int set)
  2794. {
  2795. const config_line_t *line = state->Guard;
  2796. int n_errors = 0;
  2797. if (!guard_contexts)
  2798. guard_contexts = smartlist_new();
  2799. /* Wipe all our existing guard info. (we shouldn't have any, but
  2800. * let's be safe.) */
  2801. if (set) {
  2802. SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
  2803. guard_selection_free(gs);
  2804. if (curr_guard_context == gs)
  2805. curr_guard_context = NULL;
  2806. SMARTLIST_DEL_CURRENT(guard_contexts, gs);
  2807. } SMARTLIST_FOREACH_END(gs);
  2808. }
  2809. for ( ; line != NULL; line = line->next) {
  2810. entry_guard_t *guard = entry_guard_parse_from_state(line->value);
  2811. if (guard == NULL) {
  2812. ++n_errors;
  2813. continue;
  2814. }
  2815. tor_assert(guard->selection_name);
  2816. if (!strcmp(guard->selection_name, "legacy")) {
  2817. ++n_errors;
  2818. entry_guard_free(guard);
  2819. continue;
  2820. }
  2821. if (set) {
  2822. guard_selection_t *gs;
  2823. gs = get_guard_selection_by_name(guard->selection_name,
  2824. GS_TYPE_INFER, 1);
  2825. tor_assert(gs);
  2826. smartlist_add(gs->sampled_entry_guards, guard);
  2827. guard->in_selection = gs;
  2828. } else {
  2829. entry_guard_free(guard);
  2830. }
  2831. }
  2832. if (set) {
  2833. SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
  2834. entry_guards_update_all(gs);
  2835. } SMARTLIST_FOREACH_END(gs);
  2836. }
  2837. return n_errors ? -1 : 0;
  2838. }
  2839. /** If <b>digest</b> matches the identity of any node in the
  2840. * entry_guards list for the provided guard selection state,
  2841. return that node. Else return NULL. */
  2842. entry_guard_t *
  2843. entry_guard_get_by_id_digest_for_guard_selection(guard_selection_t *gs,
  2844. const char *digest)
  2845. {
  2846. return get_sampled_guard_with_id(gs, (const uint8_t*)digest);
  2847. }
  2848. /** Return the node_t associated with a single entry_guard_t. May
  2849. * return NULL if the guard is not currently in the consensus. */
  2850. const node_t *
  2851. entry_guard_find_node(const entry_guard_t *guard)
  2852. {
  2853. tor_assert(guard);
  2854. return node_get_by_id(guard->identity);
  2855. }
  2856. /** If <b>digest</b> matches the identity of any node in the
  2857. * entry_guards list for the default guard selection state,
  2858. return that node. Else return NULL. */
  2859. entry_guard_t *
  2860. entry_guard_get_by_id_digest(const char *digest)
  2861. {
  2862. return entry_guard_get_by_id_digest_for_guard_selection(
  2863. get_guard_selection_info(), digest);
  2864. }
  2865. /** We are about to connect to bridge with identity <b>digest</b> to fetch its
  2866. * descriptor. Create a new guard state for this connection and return it. */
  2867. circuit_guard_state_t *
  2868. get_guard_state_for_bridge_desc_fetch(const char *digest)
  2869. {
  2870. circuit_guard_state_t *guard_state = NULL;
  2871. entry_guard_t *guard = NULL;
  2872. guard = entry_guard_get_by_id_digest_for_guard_selection(
  2873. get_guard_selection_info(), digest);
  2874. if (!guard) {
  2875. return NULL;
  2876. }
  2877. /* Update the guard last_tried_to_connect time since it's checked by the
  2878. * guard susbsystem. */
  2879. guard->last_tried_to_connect = approx_time();
  2880. /* Create the guard state */
  2881. guard_state = circuit_guard_state_new(guard,
  2882. GUARD_CIRC_STATE_USABLE_ON_COMPLETION,
  2883. NULL);
  2884. return guard_state;
  2885. }
  2886. /** Release all storage held by <b>e</b>. */
  2887. STATIC void
  2888. entry_guard_free_(entry_guard_t *e)
  2889. {
  2890. if (!e)
  2891. return;
  2892. entry_guard_handles_clear(e);
  2893. tor_free(e->sampled_by_version);
  2894. tor_free(e->extra_state_fields);
  2895. tor_free(e->selection_name);
  2896. tor_free(e->bridge_addr);
  2897. tor_free(e);
  2898. }
  2899. /** Return 0 if we're fine adding arbitrary routers out of the
  2900. * directory to our entry guard list, or return 1 if we have a
  2901. * list already and we must stick to it.
  2902. */
  2903. int
  2904. entry_list_is_constrained(const or_options_t *options)
  2905. {
  2906. // XXXX #21425 look at the current selection.
  2907. if (options->EntryNodes)
  2908. return 1;
  2909. if (options->UseBridges)
  2910. return 1;
  2911. return 0;
  2912. }
  2913. /** Return the number of bridges that have descriptors that are marked with
  2914. * purpose 'bridge' and are running. If use_maybe_reachable is
  2915. * true, include bridges that might be reachable in the count.
  2916. * Otherwise, if it is false, only include bridges that have recently been
  2917. * found running in the count.
  2918. *
  2919. * We use this function to decide if we're ready to start building
  2920. * circuits through our bridges, or if we need to wait until the
  2921. * directory "server/authority" requests finish. */
  2922. MOCK_IMPL(int,
  2923. num_bridges_usable,(int use_maybe_reachable))
  2924. {
  2925. int n_options = 0;
  2926. if (BUG(!get_options()->UseBridges)) {
  2927. return 0;
  2928. }
  2929. guard_selection_t *gs = get_guard_selection_info();
  2930. if (BUG(gs->type != GS_TYPE_BRIDGE)) {
  2931. return 0;
  2932. }
  2933. SMARTLIST_FOREACH_BEGIN(gs->sampled_entry_guards, entry_guard_t *, guard) {
  2934. /* Not a bridge, or not one we are configured to be able to use. */
  2935. if (! guard->is_filtered_guard)
  2936. continue;
  2937. /* Definitely not usable */
  2938. if (guard->is_reachable == GUARD_REACHABLE_NO)
  2939. continue;
  2940. /* If we want to be really sure the bridges will work, skip maybes */
  2941. if (!use_maybe_reachable && guard->is_reachable == GUARD_REACHABLE_MAYBE)
  2942. continue;
  2943. if (tor_digest_is_zero(guard->identity))
  2944. continue;
  2945. const node_t *node = node_get_by_id(guard->identity);
  2946. if (node && node->ri)
  2947. ++n_options;
  2948. } SMARTLIST_FOREACH_END(guard);
  2949. return n_options;
  2950. }
  2951. /** Check the pathbias use success count of <b>node</b> and disable it if it
  2952. * goes over our thresholds. */
  2953. static void
  2954. pathbias_check_use_success_count(entry_guard_t *node)
  2955. {
  2956. const or_options_t *options = get_options();
  2957. const double EPSILON = 1.0e-9;
  2958. /* Note: We rely on the < comparison here to allow us to set a 0
  2959. * rate and disable the feature entirely. If refactoring, don't
  2960. * change to <= */
  2961. if (node->pb.use_attempts > EPSILON &&
  2962. pathbias_get_use_success_count(node)/node->pb.use_attempts
  2963. < pathbias_get_extreme_use_rate(options) &&
  2964. pathbias_get_dropguards(options)) {
  2965. node->pb.path_bias_disabled = 1;
  2966. log_info(LD_GENERAL,
  2967. "Path use bias is too high (%f/%f); disabling node %s",
  2968. node->pb.circ_successes, node->pb.circ_attempts,
  2969. node->nickname);
  2970. }
  2971. }
  2972. /** Check the pathbias close count of <b>node</b> and disable it if it goes
  2973. * over our thresholds. */
  2974. static void
  2975. pathbias_check_close_success_count(entry_guard_t *node)
  2976. {
  2977. const or_options_t *options = get_options();
  2978. const double EPSILON = 1.0e-9;
  2979. /* Note: We rely on the < comparison here to allow us to set a 0
  2980. * rate and disable the feature entirely. If refactoring, don't
  2981. * change to <= */
  2982. if (node->pb.circ_attempts > EPSILON &&
  2983. pathbias_get_close_success_count(node)/node->pb.circ_attempts
  2984. < pathbias_get_extreme_rate(options) &&
  2985. pathbias_get_dropguards(options)) {
  2986. node->pb.path_bias_disabled = 1;
  2987. log_info(LD_GENERAL,
  2988. "Path bias is too high (%f/%f); disabling node %s",
  2989. node->pb.circ_successes, node->pb.circ_attempts,
  2990. node->nickname);
  2991. }
  2992. }
  2993. /** Parse <b>state</b> and learn about the entry guards it describes.
  2994. * If <b>set</b> is true, and there are no errors, replace the guard
  2995. * list in the default guard selection context with what we find.
  2996. * On success, return 0. On failure, alloc into *<b>msg</b> a string
  2997. * describing the error, and return -1.
  2998. */
  2999. int
  3000. entry_guards_parse_state(or_state_t *state, int set, char **msg)
  3001. {
  3002. entry_guards_dirty = 0;
  3003. int r1 = entry_guards_load_guards_from_state(state, set);
  3004. entry_guards_dirty = 0;
  3005. if (r1 < 0) {
  3006. if (msg && *msg == NULL) {
  3007. *msg = tor_strdup("parsing error");
  3008. }
  3009. return -1;
  3010. }
  3011. return 0;
  3012. }
  3013. /** How long will we let a change in our guard nodes stay un-saved
  3014. * when we are trying to avoid disk writes? */
  3015. #define SLOW_GUARD_STATE_FLUSH_TIME 600
  3016. /** How long will we let a change in our guard nodes stay un-saved
  3017. * when we are not trying to avoid disk writes? */
  3018. #define FAST_GUARD_STATE_FLUSH_TIME 30
  3019. /** Our list of entry guards has changed for a particular guard selection
  3020. * context, or some element of one of our entry guards has changed for one.
  3021. * Write the changes to disk within the next few minutes.
  3022. */
  3023. void
  3024. entry_guards_changed_for_guard_selection(guard_selection_t *gs)
  3025. {
  3026. time_t when;
  3027. tor_assert(gs != NULL);
  3028. entry_guards_dirty = 1;
  3029. if (get_options()->AvoidDiskWrites)
  3030. when = time(NULL) + SLOW_GUARD_STATE_FLUSH_TIME;
  3031. else
  3032. when = time(NULL) + FAST_GUARD_STATE_FLUSH_TIME;
  3033. /* or_state_save() will call entry_guards_update_state() and
  3034. entry_guards_update_guards_in_state()
  3035. */
  3036. or_state_mark_dirty(get_or_state(), when);
  3037. }
  3038. /** Our list of entry guards has changed for the default guard selection
  3039. * context, or some element of one of our entry guards has changed. Write
  3040. * the changes to disk within the next few minutes.
  3041. */
  3042. void
  3043. entry_guards_changed(void)
  3044. {
  3045. entry_guards_changed_for_guard_selection(get_guard_selection_info());
  3046. }
  3047. /** If the entry guard info has not changed, do nothing and return.
  3048. * Otherwise, free the EntryGuards piece of <b>state</b> and create
  3049. * a new one out of the global entry_guards list, and then mark
  3050. * <b>state</b> dirty so it will get saved to disk.
  3051. */
  3052. void
  3053. entry_guards_update_state(or_state_t *state)
  3054. {
  3055. entry_guards_dirty = 0;
  3056. // Handles all guard info.
  3057. entry_guards_update_guards_in_state(state);
  3058. entry_guards_dirty = 0;
  3059. if (!get_options()->AvoidDiskWrites)
  3060. or_state_mark_dirty(get_or_state(), 0);
  3061. entry_guards_dirty = 0;
  3062. }
  3063. /** Return true iff the circuit's guard can succeed that is can be used. */
  3064. int
  3065. entry_guard_could_succeed(const circuit_guard_state_t *guard_state)
  3066. {
  3067. if (!guard_state) {
  3068. return 0;
  3069. }
  3070. entry_guard_t *guard = entry_guard_handle_get(guard_state->guard);
  3071. if (!guard || BUG(guard->in_selection == NULL)) {
  3072. return 0;
  3073. }
  3074. return 1;
  3075. }
  3076. /**
  3077. * Format a single entry guard in the format expected by the controller.
  3078. * Return a newly allocated string.
  3079. */
  3080. STATIC char *
  3081. getinfo_helper_format_single_entry_guard(const entry_guard_t *e)
  3082. {
  3083. const char *status = NULL;
  3084. time_t when = 0;
  3085. const node_t *node;
  3086. char tbuf[ISO_TIME_LEN+1];
  3087. char nbuf[MAX_VERBOSE_NICKNAME_LEN+1];
  3088. /* This is going to be a bit tricky, since the status
  3089. * codes weren't really intended for prop271 guards.
  3090. *
  3091. * XXXX use a more appropriate format for exporting this information
  3092. */
  3093. if (e->confirmed_idx < 0) {
  3094. status = "never-connected";
  3095. } else if (! e->currently_listed) {
  3096. when = e->unlisted_since_date;
  3097. status = "unusable";
  3098. } else if (! e->is_filtered_guard) {
  3099. status = "unusable";
  3100. } else if (e->is_reachable == GUARD_REACHABLE_NO) {
  3101. when = e->failing_since;
  3102. status = "down";
  3103. } else {
  3104. status = "up";
  3105. }
  3106. node = entry_guard_find_node(e);
  3107. if (node) {
  3108. node_get_verbose_nickname(node, nbuf);
  3109. } else {
  3110. nbuf[0] = '$';
  3111. base16_encode(nbuf+1, sizeof(nbuf)-1, e->identity, DIGEST_LEN);
  3112. /* e->nickname field is not very reliable if we don't know about
  3113. * this router any longer; don't include it. */
  3114. }
  3115. char *result = NULL;
  3116. if (when) {
  3117. format_iso_time(tbuf, when);
  3118. tor_asprintf(&result, "%s %s %s\n", nbuf, status, tbuf);
  3119. } else {
  3120. tor_asprintf(&result, "%s %s\n", nbuf, status);
  3121. }
  3122. return result;
  3123. }
  3124. /** If <b>question</b> is the string "entry-guards", then dump
  3125. * to *<b>answer</b> a newly allocated string describing all of
  3126. * the nodes in the global entry_guards list. See control-spec.txt
  3127. * for details.
  3128. * For backward compatibility, we also handle the string "helper-nodes".
  3129. *
  3130. * XXX this should be totally redesigned after prop 271 too, and that's
  3131. * going to take some control spec work.
  3132. * */
  3133. int
  3134. getinfo_helper_entry_guards(control_connection_t *conn,
  3135. const char *question, char **answer,
  3136. const char **errmsg)
  3137. {
  3138. guard_selection_t *gs = get_guard_selection_info();
  3139. tor_assert(gs != NULL);
  3140. (void) conn;
  3141. (void) errmsg;
  3142. if (!strcmp(question,"entry-guards") ||
  3143. !strcmp(question,"helper-nodes")) {
  3144. const smartlist_t *guards;
  3145. guards = gs->sampled_entry_guards;
  3146. smartlist_t *sl = smartlist_new();
  3147. SMARTLIST_FOREACH_BEGIN(guards, const entry_guard_t *, e) {
  3148. char *cp = getinfo_helper_format_single_entry_guard(e);
  3149. smartlist_add(sl, cp);
  3150. } SMARTLIST_FOREACH_END(e);
  3151. *answer = smartlist_join_strings(sl, "", 0, NULL);
  3152. SMARTLIST_FOREACH(sl, char *, c, tor_free(c));
  3153. smartlist_free(sl);
  3154. }
  3155. return 0;
  3156. }
  3157. /* Given the original bandwidth of a guard and its guardfraction,
  3158. * calculate how much bandwidth the guard should have as a guard and
  3159. * as a non-guard.
  3160. *
  3161. * Quoting from proposal236:
  3162. *
  3163. * Let Wpf denote the weight from the 'bandwidth-weights' line a
  3164. * client would apply to N for position p if it had the guard
  3165. * flag, Wpn the weight if it did not have the guard flag, and B the
  3166. * measured bandwidth of N in the consensus. Then instead of choosing
  3167. * N for position p proportionally to Wpf*B or Wpn*B, clients should
  3168. * choose N proportionally to F*Wpf*B + (1-F)*Wpn*B.
  3169. *
  3170. * This function fills the <b>guardfraction_bw</b> structure. It sets
  3171. * <b>guard_bw</b> to F*B and <b>non_guard_bw</b> to (1-F)*B.
  3172. */
  3173. void
  3174. guard_get_guardfraction_bandwidth(guardfraction_bandwidth_t *guardfraction_bw,
  3175. int orig_bandwidth,
  3176. uint32_t guardfraction_percentage)
  3177. {
  3178. double guardfraction_fraction;
  3179. /* Turn the percentage into a fraction. */
  3180. tor_assert(guardfraction_percentage <= 100);
  3181. guardfraction_fraction = guardfraction_percentage / 100.0;
  3182. long guard_bw = tor_lround(guardfraction_fraction * orig_bandwidth);
  3183. tor_assert(guard_bw <= INT_MAX);
  3184. guardfraction_bw->guard_bw = (int) guard_bw;
  3185. guardfraction_bw->non_guard_bw = orig_bandwidth - (int) guard_bw;
  3186. }
  3187. /** Helper: Update the status of all entry guards, in whatever algorithm
  3188. * is used. Return true if we should stop using all previously generated
  3189. * circuits, by calling circuit_mark_all_unused_circs() and
  3190. * circuit_mark_all_dirty_circs_as_unusable().
  3191. */
  3192. int
  3193. guards_update_all(void)
  3194. {
  3195. int mark_circuits = 0;
  3196. if (update_guard_selection_choice(get_options()))
  3197. mark_circuits = 1;
  3198. tor_assert(curr_guard_context);
  3199. if (entry_guards_update_all(curr_guard_context))
  3200. mark_circuits = 1;
  3201. return mark_circuits;
  3202. }
  3203. /** Helper: pick a guard for a circuit, with whatever algorithm is
  3204. used. */
  3205. const node_t *
  3206. guards_choose_guard(cpath_build_state_t *state,
  3207. uint8_t purpose,
  3208. circuit_guard_state_t **guard_state_out)
  3209. {
  3210. const node_t *r = NULL;
  3211. const uint8_t *exit_id = NULL;
  3212. entry_guard_restriction_t *rst = NULL;
  3213. /* Only apply restrictions if we have a specific exit node in mind, and only
  3214. * if we are not doing vanguard circuits: we don't want to apply guard
  3215. * restrictions to vanguard circuits. */
  3216. if (state && !circuit_should_use_vanguards(purpose) &&
  3217. (exit_id = build_state_get_exit_rsa_id(state))) {
  3218. /* We're building to a targeted exit node, so that node can't be
  3219. * chosen as our guard for this circuit. Remember that fact in a
  3220. * restriction. */
  3221. rst = guard_create_exit_restriction(exit_id);
  3222. tor_assert(rst);
  3223. }
  3224. if (entry_guard_pick_for_circuit(get_guard_selection_info(),
  3225. GUARD_USAGE_TRAFFIC,
  3226. rst,
  3227. &r,
  3228. guard_state_out) < 0) {
  3229. tor_assert(r == NULL);
  3230. }
  3231. return r;
  3232. }
  3233. /** Remove all currently listed entry guards for a given guard selection
  3234. * context. This frees and replaces <b>gs</b>, so don't use <b>gs</b>
  3235. * after calling this function. */
  3236. void
  3237. remove_all_entry_guards_for_guard_selection(guard_selection_t *gs)
  3238. {
  3239. // This function shouldn't exist. XXXX
  3240. tor_assert(gs != NULL);
  3241. char *old_name = tor_strdup(gs->name);
  3242. guard_selection_type_t old_type = gs->type;
  3243. SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, entry, {
  3244. control_event_guard(entry->nickname, entry->identity, "DROPPED");
  3245. });
  3246. if (gs == curr_guard_context) {
  3247. curr_guard_context = NULL;
  3248. }
  3249. smartlist_remove(guard_contexts, gs);
  3250. guard_selection_free(gs);
  3251. gs = get_guard_selection_by_name(old_name, old_type, 1);
  3252. entry_guards_changed_for_guard_selection(gs);
  3253. tor_free(old_name);
  3254. }
  3255. /** Remove all currently listed entry guards, so new ones will be chosen.
  3256. *
  3257. * XXXX This function shouldn't exist -- it's meant to support the DROPGUARDS
  3258. * command, which is deprecated.
  3259. */
  3260. void
  3261. remove_all_entry_guards(void)
  3262. {
  3263. remove_all_entry_guards_for_guard_selection(get_guard_selection_info());
  3264. }
  3265. /** Helper: pick a directory guard, with whatever algorithm is used. */
  3266. const node_t *
  3267. guards_choose_dirguard(uint8_t dir_purpose,
  3268. circuit_guard_state_t **guard_state_out)
  3269. {
  3270. const node_t *r = NULL;
  3271. entry_guard_restriction_t *rst = NULL;
  3272. /* If we are fetching microdescs, don't query outdated dirservers. */
  3273. if (dir_purpose == DIR_PURPOSE_FETCH_MICRODESC) {
  3274. rst = guard_create_dirserver_md_restriction();
  3275. }
  3276. if (entry_guard_pick_for_circuit(get_guard_selection_info(),
  3277. GUARD_USAGE_DIRGUARD,
  3278. rst,
  3279. &r,
  3280. guard_state_out) < 0) {
  3281. tor_assert(r == NULL);
  3282. }
  3283. return r;
  3284. }
  3285. /**
  3286. * If we're running with a constrained guard set, then maybe mark our guards
  3287. * usable. Return 1 if we do; 0 if we don't.
  3288. */
  3289. int
  3290. guards_retry_optimistic(const or_options_t *options)
  3291. {
  3292. if (! entry_list_is_constrained(options))
  3293. return 0;
  3294. mark_primary_guards_maybe_reachable(get_guard_selection_info());
  3295. return 1;
  3296. }
  3297. /**
  3298. * Check if we are missing any crucial dirinfo for the guard subsystem to
  3299. * work. Return NULL if everything went well, otherwise return a newly
  3300. * allocated string with an informative error message. In the latter case, use
  3301. * the genreal descriptor information <b>using_mds</b>, <b>num_present</b> and
  3302. * <b>num_usable</b> to improve the error message. */
  3303. char *
  3304. guard_selection_get_err_str_if_dir_info_missing(guard_selection_t *gs,
  3305. int using_mds,
  3306. int num_present, int num_usable)
  3307. {
  3308. if (!gs->primary_guards_up_to_date)
  3309. entry_guards_update_primary(gs);
  3310. char *ret_str = NULL;
  3311. int n_missing_descriptors = 0;
  3312. int n_considered = 0;
  3313. int num_primary_to_check;
  3314. /* We want to check for the descriptor of at least the first two primary
  3315. * guards in our list, since these are the guards that we typically use for
  3316. * circuits. */
  3317. num_primary_to_check = get_n_primary_guards_to_use(GUARD_USAGE_TRAFFIC);
  3318. num_primary_to_check++;
  3319. SMARTLIST_FOREACH_BEGIN(gs->primary_entry_guards, entry_guard_t *, guard) {
  3320. entry_guard_consider_retry(guard);
  3321. if (guard->is_reachable == GUARD_REACHABLE_NO)
  3322. continue;
  3323. n_considered++;
  3324. if (!guard_has_descriptor(guard))
  3325. n_missing_descriptors++;
  3326. if (n_considered >= num_primary_to_check)
  3327. break;
  3328. } SMARTLIST_FOREACH_END(guard);
  3329. /* If we are not missing any descriptors, return NULL. */
  3330. if (!n_missing_descriptors) {
  3331. return NULL;
  3332. }
  3333. /* otherwise return a helpful error string */
  3334. tor_asprintf(&ret_str, "We're missing descriptors for %d/%d of our "
  3335. "primary entry guards (total %sdescriptors: %d/%d).",
  3336. n_missing_descriptors, num_primary_to_check,
  3337. using_mds?"micro":"", num_present, num_usable);
  3338. return ret_str;
  3339. }
  3340. /** As guard_selection_have_enough_dir_info_to_build_circuits, but uses
  3341. * the default guard selection. */
  3342. char *
  3343. entry_guards_get_err_str_if_dir_info_missing(int using_mds,
  3344. int num_present, int num_usable)
  3345. {
  3346. return guard_selection_get_err_str_if_dir_info_missing(
  3347. get_guard_selection_info(),
  3348. using_mds,
  3349. num_present, num_usable);
  3350. }
  3351. /** Free one guard selection context */
  3352. STATIC void
  3353. guard_selection_free_(guard_selection_t *gs)
  3354. {
  3355. if (!gs) return;
  3356. tor_free(gs->name);
  3357. if (gs->sampled_entry_guards) {
  3358. SMARTLIST_FOREACH(gs->sampled_entry_guards, entry_guard_t *, e,
  3359. entry_guard_free(e));
  3360. smartlist_free(gs->sampled_entry_guards);
  3361. gs->sampled_entry_guards = NULL;
  3362. }
  3363. smartlist_free(gs->confirmed_entry_guards);
  3364. smartlist_free(gs->primary_entry_guards);
  3365. tor_free(gs);
  3366. }
  3367. /** Release all storage held by the list of entry guards and related
  3368. * memory structs. */
  3369. void
  3370. entry_guards_free_all(void)
  3371. {
  3372. /* Null out the default */
  3373. curr_guard_context = NULL;
  3374. /* Free all the guard contexts */
  3375. if (guard_contexts != NULL) {
  3376. SMARTLIST_FOREACH_BEGIN(guard_contexts, guard_selection_t *, gs) {
  3377. guard_selection_free(gs);
  3378. } SMARTLIST_FOREACH_END(gs);
  3379. smartlist_free(guard_contexts);
  3380. guard_contexts = NULL;
  3381. }
  3382. circuit_build_times_free_timeouts(get_circuit_build_times_mutable());
  3383. }