command.c 23 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 command.c
  8. * \brief Functions for processing incoming cells.
  9. *
  10. * When we receive a cell from a client or a relay, it arrives on some
  11. * channel, and tells us what to do with it. In this module, we dispatch based
  12. * on the cell type using the functions command_process_cell() and
  13. * command_process_var_cell(), and deal with the cell accordingly. (These
  14. * handlers are installed on a channel with the command_setup_channel()
  15. * function.)
  16. *
  17. * Channels have a chance to handle some cell types on their own before they
  18. * are ever passed here --- typically, they do this for cells that are
  19. * specific to a given channel type. For example, in channeltls.c, the cells
  20. * for the initial connection handshake are handled before we get here. (Of
  21. * course, the fact that there _is_ only one channel type for now means that
  22. * we may have gotten the factoring wrong here.)
  23. *
  24. * Handling other cell types is mainly farmed off to other modules, after
  25. * initial sanity-checking. CREATE* cells are handled ultimately in onion.c,
  26. * CREATED* cells trigger circuit creation in circuitbuild.c, DESTROY cells
  27. * are handled here (since they're simple), and RELAY cells, in all their
  28. * complexity, are passed off to relay.c.
  29. **/
  30. /* In-points to command.c:
  31. *
  32. * - command_process_cell(), called from
  33. * incoming cell handlers of channel_t instances;
  34. * callbacks registered in command_setup_channel(),
  35. * called when channels are created in circuitbuild.c
  36. */
  37. #include "or.h"
  38. #include "channel.h"
  39. #include "circuitbuild.h"
  40. #include "circuitlist.h"
  41. #include "command.h"
  42. #include "connection.h"
  43. #include "connection_or.h"
  44. #include "config.h"
  45. #include "control.h"
  46. #include "cpuworker.h"
  47. #include "dos.h"
  48. #include "hibernate.h"
  49. #include "nodelist.h"
  50. #include "onion.h"
  51. #include "rephist.h"
  52. #include "relay.h"
  53. #include "router.h"
  54. #include "routerlist.h"
  55. /** How many CELL_CREATE cells have we received, ever? */
  56. uint64_t stats_n_create_cells_processed = 0;
  57. /** How many CELL_CREATED cells have we received, ever? */
  58. uint64_t stats_n_created_cells_processed = 0;
  59. /** How many CELL_RELAY cells have we received, ever? */
  60. uint64_t stats_n_relay_cells_processed = 0;
  61. /** How many CELL_DESTROY cells have we received, ever? */
  62. uint64_t stats_n_destroy_cells_processed = 0;
  63. /* Handle an incoming channel */
  64. static void command_handle_incoming_channel(channel_listener_t *listener,
  65. channel_t *chan);
  66. /* These are the main functions for processing cells */
  67. static void command_process_create_cell(cell_t *cell, channel_t *chan);
  68. static void command_process_created_cell(cell_t *cell, channel_t *chan);
  69. static void command_process_relay_cell(cell_t *cell, channel_t *chan);
  70. static void command_process_destroy_cell(cell_t *cell, channel_t *chan);
  71. /** Convert the cell <b>command</b> into a lower-case, human-readable
  72. * string. */
  73. const char *
  74. cell_command_to_string(uint8_t command)
  75. {
  76. switch (command) {
  77. case CELL_PADDING: return "padding";
  78. case CELL_CREATE: return "create";
  79. case CELL_CREATED: return "created";
  80. case CELL_RELAY: return "relay";
  81. case CELL_DESTROY: return "destroy";
  82. case CELL_CREATE_FAST: return "create_fast";
  83. case CELL_CREATED_FAST: return "created_fast";
  84. case CELL_VERSIONS: return "versions";
  85. case CELL_NETINFO: return "netinfo";
  86. case CELL_RELAY_EARLY: return "relay_early";
  87. case CELL_CREATE2: return "create2";
  88. case CELL_CREATED2: return "created2";
  89. case CELL_VPADDING: return "vpadding";
  90. case CELL_CERTS: return "certs";
  91. case CELL_AUTH_CHALLENGE: return "auth_challenge";
  92. case CELL_AUTHENTICATE: return "authenticate";
  93. case CELL_AUTHORIZE: return "authorize";
  94. default: return "unrecognized";
  95. }
  96. }
  97. #ifdef KEEP_TIMING_STATS
  98. /** This is a wrapper function around the actual function that processes the
  99. * <b>cell</b> that just arrived on <b>conn</b>. Increment <b>*time</b>
  100. * by the number of microseconds used by the call to <b>*func(cell, conn)</b>.
  101. */
  102. static void
  103. command_time_process_cell(cell_t *cell, channel_t *chan, int *time,
  104. void (*func)(cell_t *, channel_t *))
  105. {
  106. struct timeval start, end;
  107. long time_passed;
  108. tor_gettimeofday(&start);
  109. (*func)(cell, chan);
  110. tor_gettimeofday(&end);
  111. time_passed = tv_udiff(&start, &end) ;
  112. if (time_passed > 10000) { /* more than 10ms */
  113. log_debug(LD_OR,"That call just took %ld ms.",time_passed/1000);
  114. }
  115. if (time_passed < 0) {
  116. log_info(LD_GENERAL,"That call took us back in time!");
  117. time_passed = 0;
  118. }
  119. *time += time_passed;
  120. }
  121. #endif /* defined(KEEP_TIMING_STATS) */
  122. /** Process a <b>cell</b> that was just received on <b>chan</b>. Keep internal
  123. * statistics about how many of each cell we've processed so far
  124. * this second, and the total number of microseconds it took to
  125. * process each type of cell.
  126. */
  127. void
  128. command_process_cell(channel_t *chan, cell_t *cell)
  129. {
  130. #ifdef KEEP_TIMING_STATS
  131. /* how many of each cell have we seen so far this second? needs better
  132. * name. */
  133. static int num_create=0, num_created=0, num_relay=0, num_destroy=0;
  134. /* how long has it taken to process each type of cell? */
  135. static int create_time=0, created_time=0, relay_time=0, destroy_time=0;
  136. static time_t current_second = 0; /* from previous calls to time */
  137. time_t now = time(NULL);
  138. if (now > current_second) { /* the second has rolled over */
  139. /* print stats */
  140. log_info(LD_OR,
  141. "At end of second: %d creates (%d ms), %d createds (%d ms), "
  142. "%d relays (%d ms), %d destroys (%d ms)",
  143. num_create, create_time/1000,
  144. num_created, created_time/1000,
  145. num_relay, relay_time/1000,
  146. num_destroy, destroy_time/1000);
  147. /* zero out stats */
  148. num_create = num_created = num_relay = num_destroy = 0;
  149. create_time = created_time = relay_time = destroy_time = 0;
  150. /* remember which second it is, for next time */
  151. current_second = now;
  152. }
  153. #endif /* defined(KEEP_TIMING_STATS) */
  154. #ifdef KEEP_TIMING_STATS
  155. #define PROCESS_CELL(tp, cl, cn) STMT_BEGIN { \
  156. ++num ## tp; \
  157. command_time_process_cell(cl, cn, & tp ## time , \
  158. command_process_ ## tp ## _cell); \
  159. } STMT_END
  160. #else /* !(defined(KEEP_TIMING_STATS)) */
  161. #define PROCESS_CELL(tp, cl, cn) command_process_ ## tp ## _cell(cl, cn)
  162. #endif /* defined(KEEP_TIMING_STATS) */
  163. switch (cell->command) {
  164. case CELL_CREATE:
  165. case CELL_CREATE_FAST:
  166. case CELL_CREATE2:
  167. ++stats_n_create_cells_processed;
  168. PROCESS_CELL(create, cell, chan);
  169. break;
  170. case CELL_CREATED:
  171. case CELL_CREATED_FAST:
  172. case CELL_CREATED2:
  173. ++stats_n_created_cells_processed;
  174. PROCESS_CELL(created, cell, chan);
  175. break;
  176. case CELL_RELAY:
  177. case CELL_RELAY_EARLY:
  178. ++stats_n_relay_cells_processed;
  179. PROCESS_CELL(relay, cell, chan);
  180. break;
  181. case CELL_DESTROY:
  182. ++stats_n_destroy_cells_processed;
  183. PROCESS_CELL(destroy, cell, chan);
  184. break;
  185. default:
  186. log_fn(LOG_INFO, LD_PROTOCOL,
  187. "Cell of unknown or unexpected type (%d) received. "
  188. "Dropping.",
  189. cell->command);
  190. break;
  191. }
  192. }
  193. /** Process an incoming var_cell from a channel; in the current protocol all
  194. * the var_cells are handshake-related and handled below the channel layer,
  195. * so this just logs a warning and drops the cell.
  196. */
  197. void
  198. command_process_var_cell(channel_t *chan, var_cell_t *var_cell)
  199. {
  200. tor_assert(chan);
  201. tor_assert(var_cell);
  202. log_info(LD_PROTOCOL,
  203. "Received unexpected var_cell above the channel layer of type %d"
  204. "; dropping it.",
  205. var_cell->command);
  206. }
  207. /** Process a 'create' <b>cell</b> that just arrived from <b>chan</b>. Make a
  208. * new circuit with the p_circ_id specified in cell. Put the circuit in state
  209. * onionskin_pending, and pass the onionskin to the cpuworker. Circ will get
  210. * picked up again when the cpuworker finishes decrypting it.
  211. */
  212. static void
  213. command_process_create_cell(cell_t *cell, channel_t *chan)
  214. {
  215. or_circuit_t *circ;
  216. const or_options_t *options = get_options();
  217. int id_is_high;
  218. create_cell_t *create_cell;
  219. tor_assert(cell);
  220. tor_assert(chan);
  221. log_debug(LD_OR,
  222. "Got a CREATE cell for circ_id %u on channel " U64_FORMAT
  223. " (%p)",
  224. (unsigned)cell->circ_id,
  225. U64_PRINTF_ARG(chan->global_identifier), chan);
  226. /* First thing we do, even though the cell might be invalid, is inform the
  227. * DoS mitigation subsystem layer of this event. Validation is done by this
  228. * function. */
  229. dos_cc_new_create_cell(chan);
  230. /* We check for the conditions that would make us drop the cell before
  231. * we check for the conditions that would make us send a DESTROY back,
  232. * since those conditions would make a DESTROY nonsensical. */
  233. if (cell->circ_id == 0) {
  234. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  235. "Received a create cell (type %d) from %s with zero circID; "
  236. " ignoring.", (int)cell->command,
  237. channel_get_actual_remote_descr(chan));
  238. return;
  239. }
  240. if (circuit_id_in_use_on_channel(cell->circ_id, chan)) {
  241. const node_t *node = node_get_by_id(chan->identity_digest);
  242. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  243. "Received CREATE cell (circID %u) for known circ. "
  244. "Dropping (age %d).",
  245. (unsigned)cell->circ_id,
  246. (int)(time(NULL) - channel_when_created(chan)));
  247. if (node) {
  248. char *p = esc_for_log(node_get_platform(node));
  249. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  250. "Details: router %s, platform %s.",
  251. node_describe(node), p);
  252. tor_free(p);
  253. }
  254. return;
  255. }
  256. if (we_are_hibernating()) {
  257. log_info(LD_OR,
  258. "Received create cell but we're shutting down. Sending back "
  259. "destroy.");
  260. channel_send_destroy(cell->circ_id, chan,
  261. END_CIRC_REASON_HIBERNATING);
  262. return;
  263. }
  264. /* Check if we should apply a defense for this channel. */
  265. if (dos_cc_get_defense_type(chan) == DOS_CC_DEFENSE_REFUSE_CELL) {
  266. channel_send_destroy(cell->circ_id, chan,
  267. END_CIRC_REASON_RESOURCELIMIT);
  268. return;
  269. }
  270. if (!server_mode(options) ||
  271. (!public_server_mode(options) && channel_is_outgoing(chan))) {
  272. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  273. "Received create cell (type %d) from %s, but we're connected "
  274. "to it as a client. "
  275. "Sending back a destroy.",
  276. (int)cell->command, channel_get_canonical_remote_descr(chan));
  277. channel_send_destroy(cell->circ_id, chan,
  278. END_CIRC_REASON_TORPROTOCOL);
  279. return;
  280. }
  281. /* If the high bit of the circuit ID is not as expected, close the
  282. * circ. */
  283. if (chan->wide_circ_ids)
  284. id_is_high = cell->circ_id & (1u<<31);
  285. else
  286. id_is_high = cell->circ_id & (1u<<15);
  287. if ((id_is_high &&
  288. chan->circ_id_type == CIRC_ID_TYPE_HIGHER) ||
  289. (!id_is_high &&
  290. chan->circ_id_type == CIRC_ID_TYPE_LOWER)) {
  291. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  292. "Received create cell with unexpected circ_id %u. Closing.",
  293. (unsigned)cell->circ_id);
  294. channel_send_destroy(cell->circ_id, chan,
  295. END_CIRC_REASON_TORPROTOCOL);
  296. return;
  297. }
  298. circ = or_circuit_new(cell->circ_id, chan);
  299. circ->base_.purpose = CIRCUIT_PURPOSE_OR;
  300. circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_ONIONSKIN_PENDING);
  301. create_cell = tor_malloc_zero(sizeof(create_cell_t));
  302. if (create_cell_parse(create_cell, cell) < 0) {
  303. tor_free(create_cell);
  304. log_fn(LOG_PROTOCOL_WARN, LD_OR,
  305. "Bogus/unrecognized create cell; closing.");
  306. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
  307. return;
  308. }
  309. if (connection_or_digest_is_known_relay(chan->identity_digest)) {
  310. rep_hist_note_circuit_handshake_requested(create_cell->handshake_type);
  311. }
  312. if (create_cell->handshake_type != ONION_HANDSHAKE_TYPE_FAST) {
  313. /* hand it off to the cpuworkers, and then return. */
  314. if (assign_onionskin_to_cpuworker(circ, create_cell) < 0) {
  315. log_debug(LD_GENERAL,"Failed to hand off onionskin. Closing.");
  316. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_RESOURCELIMIT);
  317. return;
  318. }
  319. log_debug(LD_OR,"success: handed off onionskin.");
  320. } else {
  321. /* This is a CREATE_FAST cell; we can handle it immediately without using
  322. * a CPU worker. */
  323. uint8_t keys[CPATH_KEY_MATERIAL_LEN];
  324. uint8_t rend_circ_nonce[DIGEST_LEN];
  325. int len;
  326. created_cell_t created_cell;
  327. memset(&created_cell, 0, sizeof(created_cell));
  328. len = onion_skin_server_handshake(ONION_HANDSHAKE_TYPE_FAST,
  329. create_cell->onionskin,
  330. create_cell->handshake_len,
  331. NULL,
  332. created_cell.reply,
  333. keys, CPATH_KEY_MATERIAL_LEN,
  334. rend_circ_nonce);
  335. tor_free(create_cell);
  336. if (len < 0) {
  337. log_warn(LD_OR,"Failed to generate key material. Closing.");
  338. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
  339. return;
  340. }
  341. created_cell.cell_type = CELL_CREATED_FAST;
  342. created_cell.handshake_len = len;
  343. if (onionskin_answer(circ, &created_cell,
  344. (const char *)keys, sizeof(keys),
  345. rend_circ_nonce)<0) {
  346. log_warn(LD_OR,"Failed to reply to CREATE_FAST cell. Closing.");
  347. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
  348. return;
  349. }
  350. memwipe(keys, 0, sizeof(keys));
  351. }
  352. }
  353. /** Process a 'created' <b>cell</b> that just arrived from <b>chan</b>.
  354. * Find the circuit
  355. * that it's intended for. If we're not the origin of the circuit, package
  356. * the 'created' cell in an 'extended' relay cell and pass it back. If we
  357. * are the origin of the circuit, send it to circuit_finish_handshake() to
  358. * finish processing keys, and then call circuit_send_next_onion_skin() to
  359. * extend to the next hop in the circuit if necessary.
  360. */
  361. static void
  362. command_process_created_cell(cell_t *cell, channel_t *chan)
  363. {
  364. circuit_t *circ;
  365. extended_cell_t extended_cell;
  366. circ = circuit_get_by_circid_channel(cell->circ_id, chan);
  367. if (!circ) {
  368. log_info(LD_OR,
  369. "(circID %u) unknown circ (probably got a destroy earlier). "
  370. "Dropping.", (unsigned)cell->circ_id);
  371. return;
  372. }
  373. if (circ->n_circ_id != cell->circ_id || circ->n_chan != chan) {
  374. log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,
  375. "got created cell from Tor client? Closing.");
  376. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  377. return;
  378. }
  379. if (created_cell_parse(&extended_cell.created_cell, cell) < 0) {
  380. log_fn(LOG_PROTOCOL_WARN, LD_OR, "Unparseable created cell.");
  381. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  382. return;
  383. }
  384. if (CIRCUIT_IS_ORIGIN(circ)) { /* we're the OP. Handshake this. */
  385. origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
  386. int err_reason = 0;
  387. log_debug(LD_OR,"at OP. Finishing handshake.");
  388. if ((err_reason = circuit_finish_handshake(origin_circ,
  389. &extended_cell.created_cell)) < 0) {
  390. circuit_mark_for_close(circ, -err_reason);
  391. return;
  392. }
  393. log_debug(LD_OR,"Moving to next skin.");
  394. if ((err_reason = circuit_send_next_onion_skin(origin_circ)) < 0) {
  395. log_info(LD_OR,"circuit_send_next_onion_skin failed.");
  396. /* XXX push this circuit_close lower */
  397. circuit_mark_for_close(circ, -err_reason);
  398. return;
  399. }
  400. } else { /* pack it into an extended relay cell, and send it. */
  401. uint8_t command=0;
  402. uint16_t len=0;
  403. uint8_t payload[RELAY_PAYLOAD_SIZE];
  404. log_debug(LD_OR,
  405. "Converting created cell to extended relay cell, sending.");
  406. memset(payload, 0, sizeof(payload));
  407. if (extended_cell.created_cell.cell_type == CELL_CREATED2)
  408. extended_cell.cell_type = RELAY_COMMAND_EXTENDED2;
  409. else
  410. extended_cell.cell_type = RELAY_COMMAND_EXTENDED;
  411. if (extended_cell_format(&command, &len, payload, &extended_cell) < 0) {
  412. log_fn(LOG_PROTOCOL_WARN, LD_OR, "Can't format extended cell.");
  413. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  414. return;
  415. }
  416. relay_send_command_from_edge(0, circ, command,
  417. (const char*)payload, len, NULL);
  418. }
  419. }
  420. /** Process a 'relay' or 'relay_early' <b>cell</b> that just arrived from
  421. * <b>conn</b>. Make sure it came in with a recognized circ_id. Pass it on to
  422. * circuit_receive_relay_cell() for actual processing.
  423. */
  424. static void
  425. command_process_relay_cell(cell_t *cell, channel_t *chan)
  426. {
  427. const or_options_t *options = get_options();
  428. circuit_t *circ;
  429. int reason, direction;
  430. circ = circuit_get_by_circid_channel(cell->circ_id, chan);
  431. if (!circ) {
  432. log_debug(LD_OR,
  433. "unknown circuit %u on connection from %s. Dropping.",
  434. (unsigned)cell->circ_id,
  435. channel_get_canonical_remote_descr(chan));
  436. return;
  437. }
  438. if (circ->state == CIRCUIT_STATE_ONIONSKIN_PENDING) {
  439. log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,"circuit in create_wait. Closing.");
  440. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  441. return;
  442. }
  443. if (CIRCUIT_IS_ORIGIN(circ)) {
  444. /* if we're a relay and treating connections with recent local
  445. * traffic better, then this is one of them. */
  446. channel_timestamp_client(chan);
  447. }
  448. if (!CIRCUIT_IS_ORIGIN(circ) &&
  449. chan == TO_OR_CIRCUIT(circ)->p_chan &&
  450. cell->circ_id == TO_OR_CIRCUIT(circ)->p_circ_id)
  451. direction = CELL_DIRECTION_OUT;
  452. else
  453. direction = CELL_DIRECTION_IN;
  454. /* If we have a relay_early cell, make sure that it's outbound, and we've
  455. * gotten no more than MAX_RELAY_EARLY_CELLS_PER_CIRCUIT of them. */
  456. if (cell->command == CELL_RELAY_EARLY) {
  457. if (direction == CELL_DIRECTION_IN) {
  458. /* Inbound early cells could once be encountered as a result of
  459. * bug 1038; but relays running versions before 0.2.1.19 are long
  460. * gone from the network, so any such cells now are surprising. */
  461. log_warn(LD_OR,
  462. "Received an inbound RELAY_EARLY cell on circuit %u."
  463. " Closing circuit. Please report this event,"
  464. " along with the following message.",
  465. (unsigned)cell->circ_id);
  466. if (CIRCUIT_IS_ORIGIN(circ)) {
  467. circuit_log_path(LOG_WARN, LD_OR, TO_ORIGIN_CIRCUIT(circ));
  468. } else if (circ->n_chan) {
  469. log_warn(LD_OR, " upstream=%s",
  470. channel_get_actual_remote_descr(circ->n_chan));
  471. }
  472. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  473. return;
  474. } else {
  475. or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
  476. if (or_circ->remaining_relay_early_cells == 0) {
  477. log_fn(LOG_PROTOCOL_WARN, LD_OR,
  478. "Received too many RELAY_EARLY cells on circ %u from %s."
  479. " Closing circuit.",
  480. (unsigned)cell->circ_id,
  481. safe_str(channel_get_canonical_remote_descr(chan)));
  482. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  483. return;
  484. }
  485. --or_circ->remaining_relay_early_cells;
  486. }
  487. }
  488. if ((reason = circuit_receive_relay_cell(cell, circ, direction)) < 0) {
  489. log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,"circuit_receive_relay_cell "
  490. "(%s) failed. Closing.",
  491. direction==CELL_DIRECTION_OUT?"forward":"backward");
  492. circuit_mark_for_close(circ, -reason);
  493. }
  494. /* If this is a cell in an RP circuit, count it as part of the
  495. hidden service stats */
  496. if (options->HiddenServiceStatistics &&
  497. !CIRCUIT_IS_ORIGIN(circ) &&
  498. TO_OR_CIRCUIT(circ)->circuit_carries_hs_traffic_stats) {
  499. rep_hist_seen_new_rp_cell();
  500. }
  501. }
  502. /** Process a 'destroy' <b>cell</b> that just arrived from
  503. * <b>chan</b>. Find the circ that it refers to (if any).
  504. *
  505. * If the circ is in state
  506. * onionskin_pending, then call onion_pending_remove() to remove it
  507. * from the pending onion list (note that if it's already being
  508. * processed by the cpuworker, it won't be in the list anymore; but
  509. * when the cpuworker returns it, the circuit will be gone, and the
  510. * cpuworker response will be dropped).
  511. *
  512. * Then mark the circuit for close (which marks all edges for close,
  513. * and passes the destroy cell onward if necessary).
  514. */
  515. static void
  516. command_process_destroy_cell(cell_t *cell, channel_t *chan)
  517. {
  518. circuit_t *circ;
  519. int reason;
  520. circ = circuit_get_by_circid_channel(cell->circ_id, chan);
  521. if (!circ) {
  522. log_info(LD_OR,"unknown circuit %u on connection from %s. Dropping.",
  523. (unsigned)cell->circ_id,
  524. channel_get_canonical_remote_descr(chan));
  525. return;
  526. }
  527. log_debug(LD_OR,"Received for circID %u.",(unsigned)cell->circ_id);
  528. reason = (uint8_t)cell->payload[0];
  529. circ->received_destroy = 1;
  530. if (!CIRCUIT_IS_ORIGIN(circ) &&
  531. chan == TO_OR_CIRCUIT(circ)->p_chan &&
  532. cell->circ_id == TO_OR_CIRCUIT(circ)->p_circ_id) {
  533. /* the destroy came from behind */
  534. circuit_set_p_circid_chan(TO_OR_CIRCUIT(circ), 0, NULL);
  535. circuit_mark_for_close(circ, reason|END_CIRC_REASON_FLAG_REMOTE);
  536. } else { /* the destroy came from ahead */
  537. circuit_set_n_circid_chan(circ, 0, NULL);
  538. if (CIRCUIT_IS_ORIGIN(circ)) {
  539. circuit_mark_for_close(circ, reason|END_CIRC_REASON_FLAG_REMOTE);
  540. } else {
  541. char payload[1];
  542. log_debug(LD_OR, "Delivering 'truncated' back.");
  543. payload[0] = (char)reason;
  544. relay_send_command_from_edge(0, circ, RELAY_COMMAND_TRUNCATED,
  545. payload, sizeof(payload), NULL);
  546. }
  547. }
  548. }
  549. /** Callback to handle a new channel; call command_setup_channel() to give
  550. * it the right cell handlers.
  551. */
  552. static void
  553. command_handle_incoming_channel(channel_listener_t *listener, channel_t *chan)
  554. {
  555. tor_assert(listener);
  556. tor_assert(chan);
  557. command_setup_channel(chan);
  558. }
  559. /** Given a channel, install the right handlers to process incoming
  560. * cells on it.
  561. */
  562. void
  563. command_setup_channel(channel_t *chan)
  564. {
  565. tor_assert(chan);
  566. channel_set_cell_handlers(chan,
  567. command_process_cell,
  568. command_process_var_cell);
  569. }
  570. /** Given a listener, install the right handler to process incoming
  571. * channels on it.
  572. */
  573. void
  574. command_setup_listener(channel_listener_t *listener)
  575. {
  576. tor_assert(listener);
  577. tor_assert(listener->state == CHANNEL_LISTENER_STATE_LISTENING);
  578. channel_listener_set_listener_fn(listener, command_handle_incoming_channel);
  579. }