bridges.c 31 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) 2007-2017, The Tor Project, Inc. */
  5. /* See LICENSE for licensing information */
  6. /**
  7. * \file bridges.c
  8. * \brief Code to manage bridges and bridge selection.
  9. *
  10. * Bridges are fixed entry nodes, used for censorship circumvention.
  11. **/
  12. #include "or.h"
  13. #include "bridges.h"
  14. #include "circuitbuild.h"
  15. #include "config.h"
  16. #include "connection.h"
  17. #include "directory.h"
  18. #include "entrynodes.h"
  19. #include "nodelist.h"
  20. #include "policies.h"
  21. #include "router.h"
  22. #include "routerlist.h"
  23. #include "routerset.h"
  24. #include "transports.h"
  25. /** Information about a configured bridge. Currently this just matches the
  26. * ones in the torrc file, but one day we may be able to learn about new
  27. * bridges on our own, and remember them in the state file. */
  28. struct bridge_info_t {
  29. /** Address and port of the bridge, as configured by the user.*/
  30. tor_addr_port_t addrport_configured;
  31. /** Address of the bridge. */
  32. tor_addr_t addr;
  33. /** TLS port for the bridge. */
  34. uint16_t port;
  35. /** Boolean: We are re-parsing our bridge list, and we are going to remove
  36. * this one if we don't find it in the list of configured bridges. */
  37. unsigned marked_for_removal : 1;
  38. /** Expected identity digest, or all zero bytes if we don't know what the
  39. * digest should be. */
  40. char identity[DIGEST_LEN];
  41. /** Name of pluggable transport protocol taken from its config line. */
  42. char *transport_name;
  43. /** When should we next try to fetch a descriptor for this bridge? */
  44. download_status_t fetch_status;
  45. /** A smartlist of k=v values to be passed to the SOCKS proxy, if
  46. transports are used for this bridge. */
  47. smartlist_t *socks_args;
  48. };
  49. static void bridge_free(bridge_info_t *bridge);
  50. /** A list of configured bridges. Whenever we actually get a descriptor
  51. * for one, we add it as an entry guard. Note that the order of bridges
  52. * in this list does not necessarily correspond to the order of bridges
  53. * in the torrc. */
  54. static smartlist_t *bridge_list = NULL;
  55. /** Mark every entry of the bridge list to be removed on our next call to
  56. * sweep_bridge_list unless it has first been un-marked. */
  57. void
  58. mark_bridge_list(void)
  59. {
  60. if (!bridge_list)
  61. bridge_list = smartlist_new();
  62. SMARTLIST_FOREACH(bridge_list, bridge_info_t *, b,
  63. b->marked_for_removal = 1);
  64. }
  65. /** Remove every entry of the bridge list that was marked with
  66. * mark_bridge_list if it has not subsequently been un-marked. */
  67. void
  68. sweep_bridge_list(void)
  69. {
  70. if (!bridge_list)
  71. bridge_list = smartlist_new();
  72. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, b) {
  73. if (b->marked_for_removal) {
  74. SMARTLIST_DEL_CURRENT(bridge_list, b);
  75. bridge_free(b);
  76. }
  77. } SMARTLIST_FOREACH_END(b);
  78. }
  79. /** Initialize the bridge list to empty, creating it if needed. */
  80. static void
  81. clear_bridge_list(void)
  82. {
  83. if (!bridge_list)
  84. bridge_list = smartlist_new();
  85. SMARTLIST_FOREACH(bridge_list, bridge_info_t *, b, bridge_free(b));
  86. smartlist_clear(bridge_list);
  87. }
  88. /** Free the bridge <b>bridge</b>. */
  89. static void
  90. bridge_free(bridge_info_t *bridge)
  91. {
  92. if (!bridge)
  93. return;
  94. tor_free(bridge->transport_name);
  95. if (bridge->socks_args) {
  96. SMARTLIST_FOREACH(bridge->socks_args, char*, s, tor_free(s));
  97. smartlist_free(bridge->socks_args);
  98. }
  99. tor_free(bridge);
  100. }
  101. /** Return a list of all the configured bridges, as bridge_info_t pointers. */
  102. const smartlist_t *
  103. bridge_list_get(void)
  104. {
  105. if (!bridge_list)
  106. bridge_list = smartlist_new();
  107. return bridge_list;
  108. }
  109. /**
  110. * Given a <b>bridge</b>, return a pointer to its RSA identity digest, or
  111. * NULL if we don't know one for it.
  112. */
  113. const uint8_t *
  114. bridge_get_rsa_id_digest(const bridge_info_t *bridge)
  115. {
  116. tor_assert(bridge);
  117. if (tor_digest_is_zero(bridge->identity))
  118. return NULL;
  119. else
  120. return (const uint8_t *) bridge->identity;
  121. }
  122. /**
  123. * Given a <b>bridge</b>, return a pointer to its configured addr:port
  124. * combination.
  125. */
  126. const tor_addr_port_t *
  127. bridge_get_addr_port(const bridge_info_t *bridge)
  128. {
  129. tor_assert(bridge);
  130. return &bridge->addrport_configured;
  131. }
  132. /** If we have a bridge configured whose digest matches <b>digest</b>, or a
  133. * bridge with no known digest whose address matches any of the
  134. * tor_addr_port_t's in <b>orports</b>, return that bridge. Else return
  135. * NULL. */
  136. static bridge_info_t *
  137. get_configured_bridge_by_orports_digest(const char *digest,
  138. const smartlist_t *orports)
  139. {
  140. if (!bridge_list)
  141. return NULL;
  142. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge)
  143. {
  144. if (tor_digest_is_zero(bridge->identity)) {
  145. SMARTLIST_FOREACH_BEGIN(orports, tor_addr_port_t *, ap)
  146. {
  147. if (tor_addr_compare(&bridge->addr, &ap->addr, CMP_EXACT) == 0 &&
  148. bridge->port == ap->port)
  149. return bridge;
  150. }
  151. SMARTLIST_FOREACH_END(ap);
  152. }
  153. if (digest && tor_memeq(bridge->identity, digest, DIGEST_LEN))
  154. return bridge;
  155. }
  156. SMARTLIST_FOREACH_END(bridge);
  157. return NULL;
  158. }
  159. /** If we have a bridge configured whose digest matches <b>digest</b>, or a
  160. * bridge with no known digest whose address matches <b>addr</b>:<b>port</b>,
  161. * return that bridge. Else return NULL. If <b>digest</b> is NULL, check for
  162. * address/port matches only. */
  163. bridge_info_t *
  164. get_configured_bridge_by_addr_port_digest(const tor_addr_t *addr,
  165. uint16_t port,
  166. const char *digest)
  167. {
  168. if (!bridge_list)
  169. return NULL;
  170. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge)
  171. {
  172. if ((tor_digest_is_zero(bridge->identity) || digest == NULL) &&
  173. !tor_addr_compare(&bridge->addr, addr, CMP_EXACT) &&
  174. bridge->port == port)
  175. return bridge;
  176. if (digest && tor_memeq(bridge->identity, digest, DIGEST_LEN))
  177. return bridge;
  178. }
  179. SMARTLIST_FOREACH_END(bridge);
  180. return NULL;
  181. }
  182. /**
  183. * As get_configured_bridge_by_addr_port, but require that the
  184. * address match <b>addr</b>:<b>port</b>, and that the ID digest match
  185. * <b>digest</b>. (The other function will ignore the address if the
  186. * digest matches.)
  187. */
  188. bridge_info_t *
  189. get_configured_bridge_by_exact_addr_port_digest(const tor_addr_t *addr,
  190. uint16_t port,
  191. const char *digest)
  192. {
  193. if (!bridge_list)
  194. return NULL;
  195. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge) {
  196. if (!tor_addr_compare(&bridge->addr, addr, CMP_EXACT) &&
  197. bridge->port == port) {
  198. if (digest && tor_memeq(bridge->identity, digest, DIGEST_LEN))
  199. return bridge;
  200. else if (!digest || tor_digest_is_zero(bridge->identity))
  201. return bridge;
  202. }
  203. } SMARTLIST_FOREACH_END(bridge);
  204. return NULL;
  205. }
  206. /** If we have a bridge configured whose digest matches <b>digest</b>, or a
  207. * bridge with no known digest whose address matches <b>addr</b>:<b>port</b>,
  208. * return 1. Else return 0. If <b>digest</b> is NULL, check for
  209. * address/port matches only. */
  210. int
  211. addr_is_a_configured_bridge(const tor_addr_t *addr,
  212. uint16_t port,
  213. const char *digest)
  214. {
  215. tor_assert(addr);
  216. return get_configured_bridge_by_addr_port_digest(addr, port, digest) ? 1 : 0;
  217. }
  218. /** If we have a bridge configured whose digest matches
  219. * <b>ei->identity_digest</b>, or a bridge with no known digest whose address
  220. * matches <b>ei->addr</b>:<b>ei->port</b>, return 1. Else return 0.
  221. * If <b>ei->onion_key</b> is NULL, check for address/port matches only. */
  222. int
  223. extend_info_is_a_configured_bridge(const extend_info_t *ei)
  224. {
  225. const char *digest = ei->onion_key ? ei->identity_digest : NULL;
  226. return addr_is_a_configured_bridge(&ei->addr, ei->port, digest);
  227. }
  228. /** Wrapper around get_configured_bridge_by_addr_port_digest() to look
  229. * it up via router descriptor <b>ri</b>. */
  230. static bridge_info_t *
  231. get_configured_bridge_by_routerinfo(const routerinfo_t *ri)
  232. {
  233. bridge_info_t *bi = NULL;
  234. smartlist_t *orports = router_get_all_orports(ri);
  235. bi = get_configured_bridge_by_orports_digest(ri->cache_info.identity_digest,
  236. orports);
  237. SMARTLIST_FOREACH(orports, tor_addr_port_t *, p, tor_free(p));
  238. smartlist_free(orports);
  239. return bi;
  240. }
  241. /** Return 1 if <b>ri</b> is one of our known bridges, else 0. */
  242. int
  243. routerinfo_is_a_configured_bridge(const routerinfo_t *ri)
  244. {
  245. return get_configured_bridge_by_routerinfo(ri) ? 1 : 0;
  246. }
  247. /** Return 1 if <b>node</b> is one of our configured bridges, else 0. */
  248. int
  249. node_is_a_configured_bridge(const node_t *node)
  250. {
  251. int retval = 0;
  252. smartlist_t *orports = node_get_all_orports(node);
  253. retval = get_configured_bridge_by_orports_digest(node->identity,
  254. orports) != NULL;
  255. SMARTLIST_FOREACH(orports, tor_addr_port_t *, p, tor_free(p));
  256. smartlist_free(orports);
  257. return retval;
  258. }
  259. /** We made a connection to a router at <b>addr</b>:<b>port</b>
  260. * without knowing its digest. Its digest turned out to be <b>digest</b>.
  261. * If it was a bridge, and we still don't know its digest, record it.
  262. */
  263. void
  264. learned_router_identity(const tor_addr_t *addr, uint16_t port,
  265. const char *digest,
  266. const ed25519_public_key_t *ed_id)
  267. {
  268. // XXXX prop220 use ed_id here, once there is some way to specify
  269. (void)ed_id;
  270. int learned = 0;
  271. bridge_info_t *bridge =
  272. get_configured_bridge_by_exact_addr_port_digest(addr, port, digest);
  273. if (bridge && tor_digest_is_zero(bridge->identity)) {
  274. memcpy(bridge->identity, digest, DIGEST_LEN);
  275. learned = 1;
  276. }
  277. /* XXXX prop220 remember bridge ed25519 identities -- add a field */
  278. #if 0
  279. if (bridge && ed_id &&
  280. ed25519_public_key_is_zero(&bridge->ed25519_identity) &&
  281. !ed25519_public_key_is_zero(ed_id)) {
  282. memcpy(&bridge->ed25519_identity, ed_id, sizeof(*ed_id));
  283. learned = 1;
  284. }
  285. #endif
  286. if (learned) {
  287. char *transport_info = NULL;
  288. const char *transport_name =
  289. find_transport_name_by_bridge_addrport(addr, port);
  290. if (transport_name)
  291. tor_asprintf(&transport_info, " (with transport '%s')", transport_name);
  292. // XXXX prop220 log both fingerprints.
  293. log_notice(LD_DIR, "Learned fingerprint %s for bridge %s%s.",
  294. hex_str(digest, DIGEST_LEN), fmt_addrport(addr, port),
  295. transport_info ? transport_info : "");
  296. tor_free(transport_info);
  297. entry_guard_learned_bridge_identity(&bridge->addrport_configured,
  298. (const uint8_t *)digest);
  299. }
  300. }
  301. /** Return true if <b>bridge</b> has the same identity digest as
  302. * <b>digest</b>. If <b>digest</b> is NULL, it matches
  303. * bridges with unspecified identity digests. */
  304. static int
  305. bridge_has_digest(const bridge_info_t *bridge, const char *digest)
  306. {
  307. if (digest)
  308. return tor_memeq(digest, bridge->identity, DIGEST_LEN);
  309. else
  310. return tor_digest_is_zero(bridge->identity);
  311. }
  312. /** We are about to add a new bridge at <b>addr</b>:<b>port</b>, with optional
  313. * <b>digest</b> and <b>transport_name</b>. Mark for removal any previously
  314. * existing bridge with the same address and port, and warn the user as
  315. * appropriate.
  316. */
  317. static void
  318. bridge_resolve_conflicts(const tor_addr_t *addr, uint16_t port,
  319. const char *digest, const char *transport_name)
  320. {
  321. /* Iterate the already-registered bridge list:
  322. If you find a bridge with the same adress and port, mark it for
  323. removal. It doesn't make sense to have two active bridges with
  324. the same IP:PORT. If the bridge in question has a different
  325. digest or transport than <b>digest</b>/<b>transport_name</b>,
  326. it's probably a misconfiguration and we should warn the user.
  327. */
  328. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge) {
  329. if (bridge->marked_for_removal)
  330. continue;
  331. if (tor_addr_eq(&bridge->addr, addr) && (bridge->port == port)) {
  332. bridge->marked_for_removal = 1;
  333. if (!bridge_has_digest(bridge, digest) ||
  334. strcmp_opt(bridge->transport_name, transport_name)) {
  335. /* warn the user */
  336. char *bridge_description_new, *bridge_description_old;
  337. tor_asprintf(&bridge_description_new, "%s:%s:%s",
  338. fmt_addrport(addr, port),
  339. digest ? hex_str(digest, DIGEST_LEN) : "",
  340. transport_name ? transport_name : "");
  341. tor_asprintf(&bridge_description_old, "%s:%s:%s",
  342. fmt_addrport(&bridge->addr, bridge->port),
  343. tor_digest_is_zero(bridge->identity) ?
  344. "" : hex_str(bridge->identity,DIGEST_LEN),
  345. bridge->transport_name ? bridge->transport_name : "");
  346. log_warn(LD_GENERAL,"Tried to add bridge '%s', but we found a conflict"
  347. " with the already registered bridge '%s'. We will discard"
  348. " the old bridge and keep '%s'. If this is not what you"
  349. " wanted, please change your configuration file accordingly.",
  350. bridge_description_new, bridge_description_old,
  351. bridge_description_new);
  352. tor_free(bridge_description_new);
  353. tor_free(bridge_description_old);
  354. }
  355. }
  356. } SMARTLIST_FOREACH_END(bridge);
  357. }
  358. /** Return True if we have a bridge that uses a transport with name
  359. * <b>transport_name</b>. */
  360. MOCK_IMPL(int,
  361. transport_is_needed, (const char *transport_name))
  362. {
  363. if (!bridge_list)
  364. return 0;
  365. SMARTLIST_FOREACH_BEGIN(bridge_list, const bridge_info_t *, bridge) {
  366. if (bridge->transport_name &&
  367. !strcmp(bridge->transport_name, transport_name))
  368. return 1;
  369. } SMARTLIST_FOREACH_END(bridge);
  370. return 0;
  371. }
  372. /** Register the bridge information in <b>bridge_line</b> to the
  373. * bridge subsystem. Steals reference of <b>bridge_line</b>. */
  374. void
  375. bridge_add_from_config(bridge_line_t *bridge_line)
  376. {
  377. bridge_info_t *b;
  378. // XXXX prop220 add a way to specify ed25519 ID to bridge_line_t.
  379. { /* Log the bridge we are about to register: */
  380. log_debug(LD_GENERAL, "Registering bridge at %s (transport: %s) (%s)",
  381. fmt_addrport(&bridge_line->addr, bridge_line->port),
  382. bridge_line->transport_name ?
  383. bridge_line->transport_name : "no transport",
  384. tor_digest_is_zero(bridge_line->digest) ?
  385. "no key listed" : hex_str(bridge_line->digest, DIGEST_LEN));
  386. if (bridge_line->socks_args) { /* print socks arguments */
  387. int i = 0;
  388. tor_assert(smartlist_len(bridge_line->socks_args) > 0);
  389. log_debug(LD_GENERAL, "Bridge uses %d SOCKS arguments:",
  390. smartlist_len(bridge_line->socks_args));
  391. SMARTLIST_FOREACH(bridge_line->socks_args, const char *, arg,
  392. log_debug(LD_CONFIG, "%d: %s", ++i, arg));
  393. }
  394. }
  395. bridge_resolve_conflicts(&bridge_line->addr,
  396. bridge_line->port,
  397. bridge_line->digest,
  398. bridge_line->transport_name);
  399. b = tor_malloc_zero(sizeof(bridge_info_t));
  400. tor_addr_copy(&b->addrport_configured.addr, &bridge_line->addr);
  401. b->addrport_configured.port = bridge_line->port;
  402. tor_addr_copy(&b->addr, &bridge_line->addr);
  403. b->port = bridge_line->port;
  404. memcpy(b->identity, bridge_line->digest, DIGEST_LEN);
  405. if (bridge_line->transport_name)
  406. b->transport_name = bridge_line->transport_name;
  407. b->fetch_status.schedule = DL_SCHED_BRIDGE;
  408. b->fetch_status.backoff = DL_SCHED_RANDOM_EXPONENTIAL;
  409. b->socks_args = bridge_line->socks_args;
  410. if (!bridge_list)
  411. bridge_list = smartlist_new();
  412. tor_free(bridge_line); /* Deallocate bridge_line now. */
  413. smartlist_add(bridge_list, b);
  414. }
  415. /** If <b>digest</b> is one of our known bridges, return it. */
  416. bridge_info_t *
  417. find_bridge_by_digest(const char *digest)
  418. {
  419. if (! bridge_list)
  420. return NULL;
  421. SMARTLIST_FOREACH(bridge_list, bridge_info_t *, bridge,
  422. {
  423. if (tor_memeq(bridge->identity, digest, DIGEST_LEN))
  424. return bridge;
  425. });
  426. return NULL;
  427. }
  428. /** Given the <b>addr</b> and <b>port</b> of a bridge, if that bridge
  429. * supports a pluggable transport, return its name. Otherwise, return
  430. * NULL. */
  431. const char *
  432. find_transport_name_by_bridge_addrport(const tor_addr_t *addr, uint16_t port)
  433. {
  434. if (!bridge_list)
  435. return NULL;
  436. SMARTLIST_FOREACH_BEGIN(bridge_list, const bridge_info_t *, bridge) {
  437. if (tor_addr_eq(&bridge->addr, addr) &&
  438. (bridge->port == port))
  439. return bridge->transport_name;
  440. } SMARTLIST_FOREACH_END(bridge);
  441. return NULL;
  442. }
  443. /** If <b>addr</b> and <b>port</b> match the address and port of a
  444. * bridge of ours that uses pluggable transports, place its transport
  445. * in <b>transport</b>.
  446. *
  447. * Return 0 on success (found a transport, or found a bridge with no
  448. * transport, or found no bridge); return -1 if we should be using a
  449. * transport, but the transport could not be found.
  450. */
  451. int
  452. get_transport_by_bridge_addrport(const tor_addr_t *addr, uint16_t port,
  453. const transport_t **transport)
  454. {
  455. *transport = NULL;
  456. if (!bridge_list)
  457. return 0;
  458. SMARTLIST_FOREACH_BEGIN(bridge_list, const bridge_info_t *, bridge) {
  459. if (tor_addr_eq(&bridge->addr, addr) &&
  460. (bridge->port == port)) { /* bridge matched */
  461. if (bridge->transport_name) { /* it also uses pluggable transports */
  462. *transport = transport_get_by_name(bridge->transport_name);
  463. if (*transport == NULL) { /* it uses pluggable transports, but
  464. the transport could not be found! */
  465. return -1;
  466. }
  467. return 0;
  468. } else { /* bridge matched, but it doesn't use transports. */
  469. break;
  470. }
  471. }
  472. } SMARTLIST_FOREACH_END(bridge);
  473. *transport = NULL;
  474. return 0;
  475. }
  476. /** Return a smartlist containing all the SOCKS arguments that we
  477. * should pass to the SOCKS proxy. */
  478. const smartlist_t *
  479. get_socks_args_by_bridge_addrport(const tor_addr_t *addr, uint16_t port)
  480. {
  481. bridge_info_t *bridge = get_configured_bridge_by_addr_port_digest(addr,
  482. port,
  483. NULL);
  484. return bridge ? bridge->socks_args : NULL;
  485. }
  486. /** We need to ask <b>bridge</b> for its server descriptor. */
  487. static void
  488. launch_direct_bridge_descriptor_fetch(bridge_info_t *bridge)
  489. {
  490. const or_options_t *options = get_options();
  491. circuit_guard_state_t *guard_state = NULL;
  492. if (connection_get_by_type_addr_port_purpose(
  493. CONN_TYPE_DIR, &bridge->addr, bridge->port,
  494. DIR_PURPOSE_FETCH_SERVERDESC))
  495. return; /* it's already on the way */
  496. if (routerset_contains_bridge(options->ExcludeNodes, bridge)) {
  497. download_status_mark_impossible(&bridge->fetch_status);
  498. log_warn(LD_APP, "Not using bridge at %s: it is in ExcludeNodes.",
  499. safe_str_client(fmt_and_decorate_addr(&bridge->addr)));
  500. return;
  501. }
  502. /* Until we get a descriptor for the bridge, we only know one address for
  503. * it. */
  504. if (!fascist_firewall_allows_address_addr(&bridge->addr, bridge->port,
  505. FIREWALL_OR_CONNECTION, 0, 0)) {
  506. log_notice(LD_CONFIG, "Tried to fetch a descriptor directly from a "
  507. "bridge, but that bridge is not reachable through our "
  508. "firewall.");
  509. return;
  510. }
  511. tor_addr_port_t bridge_addrport;
  512. memcpy(&bridge_addrport.addr, &bridge->addr, sizeof(tor_addr_t));
  513. bridge_addrport.port = bridge->port;
  514. guard_state = get_guard_state_for_bridge_desc_fetch(bridge->identity);
  515. directory_request_t *req =
  516. directory_request_new(DIR_PURPOSE_FETCH_SERVERDESC);
  517. directory_request_set_or_addr_port(req, &bridge_addrport);
  518. directory_request_set_directory_id_digest(req, bridge->identity);
  519. directory_request_set_router_purpose(req, ROUTER_PURPOSE_BRIDGE);
  520. directory_request_set_resource(req, "authority.z");
  521. if (guard_state) {
  522. directory_request_set_guard_state(req, guard_state);
  523. }
  524. directory_initiate_request(req);
  525. directory_request_free(req);
  526. }
  527. /** Fetching the bridge descriptor from the bridge authority returned a
  528. * "not found". Fall back to trying a direct fetch. */
  529. void
  530. retry_bridge_descriptor_fetch_directly(const char *digest)
  531. {
  532. bridge_info_t *bridge = find_bridge_by_digest(digest);
  533. if (!bridge)
  534. return; /* not found? oh well. */
  535. launch_direct_bridge_descriptor_fetch(bridge);
  536. }
  537. /** For each bridge in our list for which we don't currently have a
  538. * descriptor, fetch a new copy of its descriptor -- either directly
  539. * from the bridge or via a bridge authority. */
  540. void
  541. fetch_bridge_descriptors(const or_options_t *options, time_t now)
  542. {
  543. int num_bridge_auths = get_n_authorities(BRIDGE_DIRINFO);
  544. int ask_bridge_directly;
  545. int can_use_bridge_authority;
  546. if (!bridge_list)
  547. return;
  548. /* If we still have unconfigured managed proxies, don't go and
  549. connect to a bridge. */
  550. if (pt_proxies_configuration_pending())
  551. return;
  552. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge)
  553. {
  554. if (!download_status_is_ready(&bridge->fetch_status, now,
  555. IMPOSSIBLE_TO_DOWNLOAD))
  556. continue; /* don't bother, no need to retry yet */
  557. if (routerset_contains_bridge(options->ExcludeNodes, bridge)) {
  558. download_status_mark_impossible(&bridge->fetch_status);
  559. log_warn(LD_APP, "Not using bridge at %s: it is in ExcludeNodes.",
  560. safe_str_client(fmt_and_decorate_addr(&bridge->addr)));
  561. continue;
  562. }
  563. /* schedule another fetch as if this one will fail, in case it does */
  564. download_status_failed(&bridge->fetch_status, 0);
  565. can_use_bridge_authority = !tor_digest_is_zero(bridge->identity) &&
  566. num_bridge_auths;
  567. ask_bridge_directly = !can_use_bridge_authority ||
  568. !options->UpdateBridgesFromAuthority;
  569. log_debug(LD_DIR, "ask_bridge_directly=%d (%d, %d, %d)",
  570. ask_bridge_directly, tor_digest_is_zero(bridge->identity),
  571. !options->UpdateBridgesFromAuthority, !num_bridge_auths);
  572. if (ask_bridge_directly &&
  573. !fascist_firewall_allows_address_addr(&bridge->addr, bridge->port,
  574. FIREWALL_OR_CONNECTION, 0,
  575. 0)) {
  576. log_notice(LD_DIR, "Bridge at '%s' isn't reachable by our "
  577. "firewall policy. %s.",
  578. fmt_addrport(&bridge->addr, bridge->port),
  579. can_use_bridge_authority ?
  580. "Asking bridge authority instead" : "Skipping");
  581. if (can_use_bridge_authority)
  582. ask_bridge_directly = 0;
  583. else
  584. continue;
  585. }
  586. if (ask_bridge_directly) {
  587. /* we need to ask the bridge itself for its descriptor. */
  588. launch_direct_bridge_descriptor_fetch(bridge);
  589. } else {
  590. /* We have a digest and we want to ask an authority. We could
  591. * combine all the requests into one, but that may give more
  592. * hints to the bridge authority than we want to give. */
  593. char resource[10 + HEX_DIGEST_LEN];
  594. memcpy(resource, "fp/", 3);
  595. base16_encode(resource+3, HEX_DIGEST_LEN+1,
  596. bridge->identity, DIGEST_LEN);
  597. memcpy(resource+3+HEX_DIGEST_LEN, ".z", 3);
  598. log_info(LD_DIR, "Fetching bridge info '%s' from bridge authority.",
  599. resource);
  600. directory_get_from_dirserver(DIR_PURPOSE_FETCH_SERVERDESC,
  601. ROUTER_PURPOSE_BRIDGE, resource, 0, DL_WANT_AUTHORITY);
  602. }
  603. }
  604. SMARTLIST_FOREACH_END(bridge);
  605. }
  606. /** If our <b>bridge</b> is configured to be a different address than
  607. * the bridge gives in <b>node</b>, rewrite the routerinfo
  608. * we received to use the address we meant to use. Now we handle
  609. * multihomed bridges better.
  610. */
  611. static void
  612. rewrite_node_address_for_bridge(const bridge_info_t *bridge, node_t *node)
  613. {
  614. /* XXXX move this function. */
  615. /* XXXX overridden addresses should really live in the node_t, so that the
  616. * routerinfo_t and the microdesc_t can be immutable. But we can only
  617. * do that safely if we know that no function that connects to an OR
  618. * does so through an address from any source other than node_get_addr().
  619. */
  620. tor_addr_t addr;
  621. const or_options_t *options = get_options();
  622. if (node->ri) {
  623. routerinfo_t *ri = node->ri;
  624. tor_addr_from_ipv4h(&addr, ri->addr);
  625. if ((!tor_addr_compare(&bridge->addr, &addr, CMP_EXACT) &&
  626. bridge->port == ri->or_port) ||
  627. (!tor_addr_compare(&bridge->addr, &ri->ipv6_addr, CMP_EXACT) &&
  628. bridge->port == ri->ipv6_orport)) {
  629. /* they match, so no need to do anything */
  630. } else {
  631. if (tor_addr_family(&bridge->addr) == AF_INET) {
  632. ri->addr = tor_addr_to_ipv4h(&bridge->addr);
  633. ri->or_port = bridge->port;
  634. log_info(LD_DIR,
  635. "Adjusted bridge routerinfo for '%s' to match configured "
  636. "address %s:%d.",
  637. ri->nickname, fmt_addr32(ri->addr), ri->or_port);
  638. } else if (tor_addr_family(&bridge->addr) == AF_INET6) {
  639. tor_addr_copy(&ri->ipv6_addr, &bridge->addr);
  640. ri->ipv6_orport = bridge->port;
  641. log_info(LD_DIR,
  642. "Adjusted bridge routerinfo for '%s' to match configured "
  643. "address %s.",
  644. ri->nickname, fmt_addrport(&ri->ipv6_addr, ri->ipv6_orport));
  645. } else {
  646. log_err(LD_BUG, "Address family not supported: %d.",
  647. tor_addr_family(&bridge->addr));
  648. return;
  649. }
  650. }
  651. if (options->ClientPreferIPv6ORPort == -1) {
  652. /* Mark which address to use based on which bridge_t we got. */
  653. node->ipv6_preferred = (tor_addr_family(&bridge->addr) == AF_INET6 &&
  654. !tor_addr_is_null(&node->ri->ipv6_addr));
  655. } else {
  656. /* Mark which address to use based on user preference */
  657. node->ipv6_preferred = (fascist_firewall_prefer_ipv6_orport(options) &&
  658. !tor_addr_is_null(&node->ri->ipv6_addr));
  659. }
  660. /* XXXipv6 we lack support for falling back to another address for
  661. the same relay, warn the user */
  662. if (!tor_addr_is_null(&ri->ipv6_addr)) {
  663. tor_addr_port_t ap;
  664. node_get_pref_orport(node, &ap);
  665. log_notice(LD_CONFIG,
  666. "Bridge '%s' has both an IPv4 and an IPv6 address. "
  667. "Will prefer using its %s address (%s) based on %s.",
  668. ri->nickname,
  669. node->ipv6_preferred ? "IPv6" : "IPv4",
  670. fmt_addrport(&ap.addr, ap.port),
  671. options->ClientPreferIPv6ORPort == -1 ?
  672. "the configured Bridge address" :
  673. "ClientPreferIPv6ORPort");
  674. }
  675. }
  676. if (node->rs) {
  677. routerstatus_t *rs = node->rs;
  678. tor_addr_from_ipv4h(&addr, rs->addr);
  679. if (!tor_addr_compare(&bridge->addr, &addr, CMP_EXACT) &&
  680. bridge->port == rs->or_port) {
  681. /* they match, so no need to do anything */
  682. } else {
  683. rs->addr = tor_addr_to_ipv4h(&bridge->addr);
  684. rs->or_port = bridge->port;
  685. log_info(LD_DIR,
  686. "Adjusted bridge routerstatus for '%s' to match "
  687. "configured address %s.",
  688. rs->nickname, fmt_addrport(&bridge->addr, rs->or_port));
  689. }
  690. }
  691. }
  692. /** We just learned a descriptor for a bridge. See if that
  693. * digest is in our entry guard list, and add it if not. */
  694. void
  695. learned_bridge_descriptor(routerinfo_t *ri, int from_cache)
  696. {
  697. tor_assert(ri);
  698. tor_assert(ri->purpose == ROUTER_PURPOSE_BRIDGE);
  699. if (get_options()->UseBridges) {
  700. int first = num_bridges_usable() <= 1;
  701. bridge_info_t *bridge = get_configured_bridge_by_routerinfo(ri);
  702. time_t now = time(NULL);
  703. router_set_status(ri->cache_info.identity_digest, 1);
  704. if (bridge) { /* if we actually want to use this one */
  705. node_t *node;
  706. /* it's here; schedule its re-fetch for a long time from now. */
  707. if (!from_cache)
  708. download_status_reset(&bridge->fetch_status);
  709. node = node_get_mutable_by_id(ri->cache_info.identity_digest);
  710. tor_assert(node);
  711. rewrite_node_address_for_bridge(bridge, node);
  712. if (tor_digest_is_zero(bridge->identity)) {
  713. memcpy(bridge->identity,ri->cache_info.identity_digest, DIGEST_LEN);
  714. log_notice(LD_DIR, "Learned identity %s for bridge at %s:%d",
  715. hex_str(bridge->identity, DIGEST_LEN),
  716. fmt_and_decorate_addr(&bridge->addr),
  717. (int) bridge->port);
  718. }
  719. entry_guard_learned_bridge_identity(&bridge->addrport_configured,
  720. (const uint8_t*)ri->cache_info.identity_digest);
  721. log_notice(LD_DIR, "new bridge descriptor '%s' (%s): %s", ri->nickname,
  722. from_cache ? "cached" : "fresh", router_describe(ri));
  723. /* set entry->made_contact so if it goes down we don't drop it from
  724. * our entry node list */
  725. if (first) {
  726. routerlist_retry_directory_downloads(now);
  727. }
  728. }
  729. }
  730. }
  731. /** Return the number of bridges that have descriptors that
  732. * are marked with purpose 'bridge' and are running.
  733. *
  734. * We use this function to decide if we're ready to start building
  735. * circuits through our bridges, or if we need to wait until the
  736. * directory "server/authority" requests finish. */
  737. int
  738. any_bridge_descriptors_known(void)
  739. {
  740. tor_assert(get_options()->UseBridges);
  741. if (!bridge_list)
  742. return 0;
  743. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge) {
  744. const node_t *node;
  745. if (!tor_digest_is_zero(bridge->identity) &&
  746. (node = node_get_by_id(bridge->identity)) != NULL &&
  747. node->ri) {
  748. return 1;
  749. }
  750. } SMARTLIST_FOREACH_END(bridge);
  751. return 0;
  752. }
  753. /** Return a smartlist containing all bridge identity digests */
  754. MOCK_IMPL(smartlist_t *,
  755. list_bridge_identities, (void))
  756. {
  757. smartlist_t *result = NULL;
  758. char *digest_tmp;
  759. if (get_options()->UseBridges && bridge_list) {
  760. result = smartlist_new();
  761. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, b) {
  762. digest_tmp = tor_malloc(DIGEST_LEN);
  763. memcpy(digest_tmp, b->identity, DIGEST_LEN);
  764. smartlist_add(result, digest_tmp);
  765. } SMARTLIST_FOREACH_END(b);
  766. }
  767. return result;
  768. }
  769. /** Get the download status for a bridge descriptor given its identity */
  770. MOCK_IMPL(download_status_t *,
  771. get_bridge_dl_status_by_id, (const char *digest))
  772. {
  773. download_status_t *dl = NULL;
  774. if (digest && get_options()->UseBridges && bridge_list) {
  775. SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, b) {
  776. if (tor_memeq(digest, b->identity, DIGEST_LEN)) {
  777. dl = &(b->fetch_status);
  778. break;
  779. }
  780. } SMARTLIST_FOREACH_END(b);
  781. }
  782. return dl;
  783. }
  784. /** Release all storage held in bridges.c */
  785. void
  786. bridges_free_all(void)
  787. {
  788. clear_bridge_list();
  789. smartlist_free(bridge_list);
  790. bridge_list = NULL;
  791. }