command.c 22 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) 2007-2016, 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 "hibernate.h"
  48. #include "nodelist.h"
  49. #include "onion.h"
  50. #include "rephist.h"
  51. #include "relay.h"
  52. #include "router.h"
  53. #include "routerlist.h"
  54. /** How many CELL_CREATE cells have we received, ever? */
  55. uint64_t stats_n_create_cells_processed = 0;
  56. /** How many CELL_CREATED cells have we received, ever? */
  57. uint64_t stats_n_created_cells_processed = 0;
  58. /** How many CELL_RELAY cells have we received, ever? */
  59. uint64_t stats_n_relay_cells_processed = 0;
  60. /** How many CELL_DESTROY cells have we received, ever? */
  61. uint64_t stats_n_destroy_cells_processed = 0;
  62. /* Handle an incoming channel */
  63. static void command_handle_incoming_channel(channel_listener_t *listener,
  64. channel_t *chan);
  65. /* These are the main functions for processing cells */
  66. static void command_process_create_cell(cell_t *cell, channel_t *chan);
  67. static void command_process_created_cell(cell_t *cell, channel_t *chan);
  68. static void command_process_relay_cell(cell_t *cell, channel_t *chan);
  69. static void command_process_destroy_cell(cell_t *cell, channel_t *chan);
  70. /** Convert the cell <b>command</b> into a lower-case, human-readable
  71. * string. */
  72. const char *
  73. cell_command_to_string(uint8_t command)
  74. {
  75. switch (command) {
  76. case CELL_PADDING: return "padding";
  77. case CELL_CREATE: return "create";
  78. case CELL_CREATED: return "created";
  79. case CELL_RELAY: return "relay";
  80. case CELL_DESTROY: return "destroy";
  81. case CELL_CREATE_FAST: return "create_fast";
  82. case CELL_CREATED_FAST: return "created_fast";
  83. case CELL_VERSIONS: return "versions";
  84. case CELL_NETINFO: return "netinfo";
  85. case CELL_RELAY_EARLY: return "relay_early";
  86. case CELL_CREATE2: return "create2";
  87. case CELL_CREATED2: return "created2";
  88. case CELL_VPADDING: return "vpadding";
  89. case CELL_CERTS: return "certs";
  90. case CELL_AUTH_CHALLENGE: return "auth_challenge";
  91. case CELL_AUTHENTICATE: return "authenticate";
  92. case CELL_AUTHORIZE: return "authorize";
  93. default: return "unrecognized";
  94. }
  95. }
  96. #ifdef KEEP_TIMING_STATS
  97. /** This is a wrapper function around the actual function that processes the
  98. * <b>cell</b> that just arrived on <b>conn</b>. Increment <b>*time</b>
  99. * by the number of microseconds used by the call to <b>*func(cell, conn)</b>.
  100. */
  101. static void
  102. command_time_process_cell(cell_t *cell, channel_t *chan, int *time,
  103. void (*func)(cell_t *, channel_t *))
  104. {
  105. struct timeval start, end;
  106. long time_passed;
  107. tor_gettimeofday(&start);
  108. (*func)(cell, chan);
  109. tor_gettimeofday(&end);
  110. time_passed = tv_udiff(&start, &end) ;
  111. if (time_passed > 10000) { /* more than 10ms */
  112. log_debug(LD_OR,"That call just took %ld ms.",time_passed/1000);
  113. }
  114. if (time_passed < 0) {
  115. log_info(LD_GENERAL,"That call took us back in time!");
  116. time_passed = 0;
  117. }
  118. *time += time_passed;
  119. }
  120. #endif
  121. /** Process a <b>cell</b> that was just received on <b>chan</b>. Keep internal
  122. * statistics about how many of each cell we've processed so far
  123. * this second, and the total number of microseconds it took to
  124. * process each type of cell.
  125. */
  126. void
  127. command_process_cell(channel_t *chan, cell_t *cell)
  128. {
  129. #ifdef KEEP_TIMING_STATS
  130. /* how many of each cell have we seen so far this second? needs better
  131. * name. */
  132. static int num_create=0, num_created=0, num_relay=0, num_destroy=0;
  133. /* how long has it taken to process each type of cell? */
  134. static int create_time=0, created_time=0, relay_time=0, destroy_time=0;
  135. static time_t current_second = 0; /* from previous calls to time */
  136. time_t now = time(NULL);
  137. if (now > current_second) { /* the second has rolled over */
  138. /* print stats */
  139. log_info(LD_OR,
  140. "At end of second: %d creates (%d ms), %d createds (%d ms), "
  141. "%d relays (%d ms), %d destroys (%d ms)",
  142. num_create, create_time/1000,
  143. num_created, created_time/1000,
  144. num_relay, relay_time/1000,
  145. num_destroy, destroy_time/1000);
  146. /* zero out stats */
  147. num_create = num_created = num_relay = num_destroy = 0;
  148. create_time = created_time = relay_time = destroy_time = 0;
  149. /* remember which second it is, for next time */
  150. current_second = now;
  151. }
  152. #endif
  153. #ifdef KEEP_TIMING_STATS
  154. #define PROCESS_CELL(tp, cl, cn) STMT_BEGIN { \
  155. ++num ## tp; \
  156. command_time_process_cell(cl, cn, & tp ## time , \
  157. command_process_ ## tp ## _cell); \
  158. } STMT_END
  159. #else
  160. #define PROCESS_CELL(tp, cl, cn) command_process_ ## tp ## _cell(cl, cn)
  161. #endif
  162. switch (cell->command) {
  163. case CELL_CREATE:
  164. case CELL_CREATE_FAST:
  165. case CELL_CREATE2:
  166. ++stats_n_create_cells_processed;
  167. PROCESS_CELL(create, cell, chan);
  168. break;
  169. case CELL_CREATED:
  170. case CELL_CREATED_FAST:
  171. case CELL_CREATED2:
  172. ++stats_n_created_cells_processed;
  173. PROCESS_CELL(created, cell, chan);
  174. break;
  175. case CELL_RELAY:
  176. case CELL_RELAY_EARLY:
  177. ++stats_n_relay_cells_processed;
  178. PROCESS_CELL(relay, cell, chan);
  179. break;
  180. case CELL_DESTROY:
  181. ++stats_n_destroy_cells_processed;
  182. PROCESS_CELL(destroy, cell, chan);
  183. break;
  184. default:
  185. log_fn(LOG_INFO, LD_PROTOCOL,
  186. "Cell of unknown or unexpected type (%d) received. "
  187. "Dropping.",
  188. cell->command);
  189. break;
  190. }
  191. }
  192. /** Process an incoming var_cell from a channel; in the current protocol all
  193. * the var_cells are handshake-related and handled below the channel layer,
  194. * so this just logs a warning and drops the cell.
  195. */
  196. void
  197. command_process_var_cell(channel_t *chan, var_cell_t *var_cell)
  198. {
  199. tor_assert(chan);
  200. tor_assert(var_cell);
  201. log_info(LD_PROTOCOL,
  202. "Received unexpected var_cell above the channel layer of type %d"
  203. "; dropping it.",
  204. var_cell->command);
  205. }
  206. /** Process a 'create' <b>cell</b> that just arrived from <b>chan</b>. Make a
  207. * new circuit with the p_circ_id specified in cell. Put the circuit in state
  208. * onionskin_pending, and pass the onionskin to the cpuworker. Circ will get
  209. * picked up again when the cpuworker finishes decrypting it.
  210. */
  211. static void
  212. command_process_create_cell(cell_t *cell, channel_t *chan)
  213. {
  214. or_circuit_t *circ;
  215. const or_options_t *options = get_options();
  216. int id_is_high;
  217. create_cell_t *create_cell;
  218. tor_assert(cell);
  219. tor_assert(chan);
  220. log_debug(LD_OR,
  221. "Got a CREATE cell for circ_id %u on channel " U64_FORMAT
  222. " (%p)",
  223. (unsigned)cell->circ_id,
  224. U64_PRINTF_ARG(chan->global_identifier), chan);
  225. /* We check for the conditions that would make us drop the cell before
  226. * we check for the conditions that would make us send a DESTROY back,
  227. * since those conditions would make a DESTROY nonsensical. */
  228. if (cell->circ_id == 0) {
  229. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  230. "Received a create cell (type %d) from %s with zero circID; "
  231. " ignoring.", (int)cell->command,
  232. channel_get_actual_remote_descr(chan));
  233. return;
  234. }
  235. if (circuit_id_in_use_on_channel(cell->circ_id, chan)) {
  236. const node_t *node = node_get_by_id(chan->identity_digest);
  237. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  238. "Received CREATE cell (circID %u) for known circ. "
  239. "Dropping (age %d).",
  240. (unsigned)cell->circ_id,
  241. (int)(time(NULL) - channel_when_created(chan)));
  242. if (node) {
  243. char *p = esc_for_log(node_get_platform(node));
  244. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  245. "Details: router %s, platform %s.",
  246. node_describe(node), p);
  247. tor_free(p);
  248. }
  249. return;
  250. }
  251. if (we_are_hibernating()) {
  252. log_info(LD_OR,
  253. "Received create cell but we're shutting down. Sending back "
  254. "destroy.");
  255. channel_send_destroy(cell->circ_id, chan,
  256. END_CIRC_REASON_HIBERNATING);
  257. return;
  258. }
  259. if (!server_mode(options) ||
  260. (!public_server_mode(options) && channel_is_outgoing(chan))) {
  261. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  262. "Received create cell (type %d) from %s, but we're connected "
  263. "to it as a client. "
  264. "Sending back a destroy.",
  265. (int)cell->command, channel_get_canonical_remote_descr(chan));
  266. channel_send_destroy(cell->circ_id, chan,
  267. END_CIRC_REASON_TORPROTOCOL);
  268. return;
  269. }
  270. /* If the high bit of the circuit ID is not as expected, close the
  271. * circ. */
  272. if (chan->wide_circ_ids)
  273. id_is_high = cell->circ_id & (1u<<31);
  274. else
  275. id_is_high = cell->circ_id & (1u<<15);
  276. if ((id_is_high &&
  277. chan->circ_id_type == CIRC_ID_TYPE_HIGHER) ||
  278. (!id_is_high &&
  279. chan->circ_id_type == CIRC_ID_TYPE_LOWER)) {
  280. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
  281. "Received create cell with unexpected circ_id %u. Closing.",
  282. (unsigned)cell->circ_id);
  283. channel_send_destroy(cell->circ_id, chan,
  284. END_CIRC_REASON_TORPROTOCOL);
  285. return;
  286. }
  287. circ = or_circuit_new(cell->circ_id, chan);
  288. circ->base_.purpose = CIRCUIT_PURPOSE_OR;
  289. circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_ONIONSKIN_PENDING);
  290. create_cell = tor_malloc_zero(sizeof(create_cell_t));
  291. if (create_cell_parse(create_cell, cell) < 0) {
  292. tor_free(create_cell);
  293. log_fn(LOG_PROTOCOL_WARN, LD_OR,
  294. "Bogus/unrecognized create cell; closing.");
  295. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL);
  296. return;
  297. }
  298. if (create_cell->handshake_type != ONION_HANDSHAKE_TYPE_FAST) {
  299. /* hand it off to the cpuworkers, and then return. */
  300. if (connection_or_digest_is_known_relay(chan->identity_digest))
  301. rep_hist_note_circuit_handshake_requested(create_cell->handshake_type);
  302. if (assign_onionskin_to_cpuworker(circ, create_cell) < 0) {
  303. log_debug(LD_GENERAL,"Failed to hand off onionskin. Closing.");
  304. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_RESOURCELIMIT);
  305. return;
  306. }
  307. log_debug(LD_OR,"success: handed off onionskin.");
  308. } else {
  309. /* This is a CREATE_FAST cell; we can handle it immediately without using
  310. * a CPU worker. */
  311. uint8_t keys[CPATH_KEY_MATERIAL_LEN];
  312. uint8_t rend_circ_nonce[DIGEST_LEN];
  313. int len;
  314. created_cell_t created_cell;
  315. /* Make sure we never try to use the OR connection on which we
  316. * received this cell to satisfy an EXTEND request, */
  317. channel_mark_client(chan);
  318. memset(&created_cell, 0, sizeof(created_cell));
  319. len = onion_skin_server_handshake(ONION_HANDSHAKE_TYPE_FAST,
  320. create_cell->onionskin,
  321. create_cell->handshake_len,
  322. NULL,
  323. created_cell.reply,
  324. keys, CPATH_KEY_MATERIAL_LEN,
  325. rend_circ_nonce);
  326. tor_free(create_cell);
  327. if (len < 0) {
  328. log_warn(LD_OR,"Failed to generate key material. Closing.");
  329. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
  330. return;
  331. }
  332. created_cell.cell_type = CELL_CREATED_FAST;
  333. created_cell.handshake_len = len;
  334. if (onionskin_answer(circ, &created_cell,
  335. (const char *)keys, rend_circ_nonce)<0) {
  336. log_warn(LD_OR,"Failed to reply to CREATE_FAST cell. Closing.");
  337. circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_INTERNAL);
  338. return;
  339. }
  340. memwipe(keys, 0, sizeof(keys));
  341. }
  342. }
  343. /** Process a 'created' <b>cell</b> that just arrived from <b>chan</b>.
  344. * Find the circuit
  345. * that it's intended for. If we're not the origin of the circuit, package
  346. * the 'created' cell in an 'extended' relay cell and pass it back. If we
  347. * are the origin of the circuit, send it to circuit_finish_handshake() to
  348. * finish processing keys, and then call circuit_send_next_onion_skin() to
  349. * extend to the next hop in the circuit if necessary.
  350. */
  351. static void
  352. command_process_created_cell(cell_t *cell, channel_t *chan)
  353. {
  354. circuit_t *circ;
  355. extended_cell_t extended_cell;
  356. circ = circuit_get_by_circid_channel(cell->circ_id, chan);
  357. if (!circ) {
  358. log_info(LD_OR,
  359. "(circID %u) unknown circ (probably got a destroy earlier). "
  360. "Dropping.", (unsigned)cell->circ_id);
  361. return;
  362. }
  363. if (circ->n_circ_id != cell->circ_id || circ->n_chan != chan) {
  364. log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,
  365. "got created cell from Tor client? Closing.");
  366. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  367. return;
  368. }
  369. if (created_cell_parse(&extended_cell.created_cell, cell) < 0) {
  370. log_fn(LOG_PROTOCOL_WARN, LD_OR, "Unparseable created cell.");
  371. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  372. return;
  373. }
  374. if (CIRCUIT_IS_ORIGIN(circ)) { /* we're the OP. Handshake this. */
  375. origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
  376. int err_reason = 0;
  377. log_debug(LD_OR,"at OP. Finishing handshake.");
  378. if ((err_reason = circuit_finish_handshake(origin_circ,
  379. &extended_cell.created_cell)) < 0) {
  380. circuit_mark_for_close(circ, -err_reason);
  381. return;
  382. }
  383. log_debug(LD_OR,"Moving to next skin.");
  384. if ((err_reason = circuit_send_next_onion_skin(origin_circ)) < 0) {
  385. log_info(LD_OR,"circuit_send_next_onion_skin failed.");
  386. /* XXX push this circuit_close lower */
  387. circuit_mark_for_close(circ, -err_reason);
  388. return;
  389. }
  390. } else { /* pack it into an extended relay cell, and send it. */
  391. uint8_t command=0;
  392. uint16_t len=0;
  393. uint8_t payload[RELAY_PAYLOAD_SIZE];
  394. log_debug(LD_OR,
  395. "Converting created cell to extended relay cell, sending.");
  396. memset(payload, 0, sizeof(payload));
  397. if (extended_cell.created_cell.cell_type == CELL_CREATED2)
  398. extended_cell.cell_type = RELAY_COMMAND_EXTENDED2;
  399. else
  400. extended_cell.cell_type = RELAY_COMMAND_EXTENDED;
  401. if (extended_cell_format(&command, &len, payload, &extended_cell) < 0) {
  402. log_fn(LOG_PROTOCOL_WARN, LD_OR, "Can't format extended cell.");
  403. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  404. return;
  405. }
  406. relay_send_command_from_edge(0, circ, command,
  407. (const char*)payload, len, NULL);
  408. }
  409. }
  410. /** Process a 'relay' or 'relay_early' <b>cell</b> that just arrived from
  411. * <b>conn</b>. Make sure it came in with a recognized circ_id. Pass it on to
  412. * circuit_receive_relay_cell() for actual processing.
  413. */
  414. static void
  415. command_process_relay_cell(cell_t *cell, channel_t *chan)
  416. {
  417. const or_options_t *options = get_options();
  418. circuit_t *circ;
  419. int reason, direction;
  420. circ = circuit_get_by_circid_channel(cell->circ_id, chan);
  421. if (!circ) {
  422. log_debug(LD_OR,
  423. "unknown circuit %u on connection from %s. Dropping.",
  424. (unsigned)cell->circ_id,
  425. channel_get_canonical_remote_descr(chan));
  426. return;
  427. }
  428. if (circ->state == CIRCUIT_STATE_ONIONSKIN_PENDING) {
  429. log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,"circuit in create_wait. Closing.");
  430. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  431. return;
  432. }
  433. if (CIRCUIT_IS_ORIGIN(circ)) {
  434. /* if we're a relay and treating connections with recent local
  435. * traffic better, then this is one of them. */
  436. channel_timestamp_client(chan);
  437. }
  438. if (!CIRCUIT_IS_ORIGIN(circ) &&
  439. chan == TO_OR_CIRCUIT(circ)->p_chan &&
  440. cell->circ_id == TO_OR_CIRCUIT(circ)->p_circ_id)
  441. direction = CELL_DIRECTION_OUT;
  442. else
  443. direction = CELL_DIRECTION_IN;
  444. /* If we have a relay_early cell, make sure that it's outbound, and we've
  445. * gotten no more than MAX_RELAY_EARLY_CELLS_PER_CIRCUIT of them. */
  446. if (cell->command == CELL_RELAY_EARLY) {
  447. if (direction == CELL_DIRECTION_IN) {
  448. /* Inbound early cells could once be encountered as a result of
  449. * bug 1038; but relays running versions before 0.2.1.19 are long
  450. * gone from the network, so any such cells now are surprising. */
  451. log_warn(LD_OR,
  452. "Received an inbound RELAY_EARLY cell on circuit %u."
  453. " Closing circuit. Please report this event,"
  454. " along with the following message.",
  455. (unsigned)cell->circ_id);
  456. if (CIRCUIT_IS_ORIGIN(circ)) {
  457. circuit_log_path(LOG_WARN, LD_OR, TO_ORIGIN_CIRCUIT(circ));
  458. } else if (circ->n_chan) {
  459. log_warn(LD_OR, " upstream=%s",
  460. channel_get_actual_remote_descr(circ->n_chan));
  461. }
  462. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  463. return;
  464. } else {
  465. or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
  466. if (or_circ->remaining_relay_early_cells == 0) {
  467. log_fn(LOG_PROTOCOL_WARN, LD_OR,
  468. "Received too many RELAY_EARLY cells on circ %u from %s."
  469. " Closing circuit.",
  470. (unsigned)cell->circ_id,
  471. safe_str(channel_get_canonical_remote_descr(chan)));
  472. circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
  473. return;
  474. }
  475. --or_circ->remaining_relay_early_cells;
  476. }
  477. }
  478. if ((reason = circuit_receive_relay_cell(cell, circ, direction)) < 0) {
  479. log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,"circuit_receive_relay_cell "
  480. "(%s) failed. Closing.",
  481. direction==CELL_DIRECTION_OUT?"forward":"backward");
  482. circuit_mark_for_close(circ, -reason);
  483. }
  484. /* If this is a cell in an RP circuit, count it as part of the
  485. hidden service stats */
  486. if (options->HiddenServiceStatistics &&
  487. !CIRCUIT_IS_ORIGIN(circ) &&
  488. TO_OR_CIRCUIT(circ)->circuit_carries_hs_traffic_stats) {
  489. rep_hist_seen_new_rp_cell();
  490. }
  491. }
  492. /** Process a 'destroy' <b>cell</b> that just arrived from
  493. * <b>chan</b>. Find the circ that it refers to (if any).
  494. *
  495. * If the circ is in state
  496. * onionskin_pending, then call onion_pending_remove() to remove it
  497. * from the pending onion list (note that if it's already being
  498. * processed by the cpuworker, it won't be in the list anymore; but
  499. * when the cpuworker returns it, the circuit will be gone, and the
  500. * cpuworker response will be dropped).
  501. *
  502. * Then mark the circuit for close (which marks all edges for close,
  503. * and passes the destroy cell onward if necessary).
  504. */
  505. static void
  506. command_process_destroy_cell(cell_t *cell, channel_t *chan)
  507. {
  508. circuit_t *circ;
  509. int reason;
  510. circ = circuit_get_by_circid_channel(cell->circ_id, chan);
  511. if (!circ) {
  512. log_info(LD_OR,"unknown circuit %u on connection from %s. Dropping.",
  513. (unsigned)cell->circ_id,
  514. channel_get_canonical_remote_descr(chan));
  515. return;
  516. }
  517. log_debug(LD_OR,"Received for circID %u.",(unsigned)cell->circ_id);
  518. reason = (uint8_t)cell->payload[0];
  519. circ->received_destroy = 1;
  520. if (!CIRCUIT_IS_ORIGIN(circ) &&
  521. chan == TO_OR_CIRCUIT(circ)->p_chan &&
  522. cell->circ_id == TO_OR_CIRCUIT(circ)->p_circ_id) {
  523. /* the destroy came from behind */
  524. circuit_set_p_circid_chan(TO_OR_CIRCUIT(circ), 0, NULL);
  525. circuit_mark_for_close(circ, reason|END_CIRC_REASON_FLAG_REMOTE);
  526. } else { /* the destroy came from ahead */
  527. circuit_set_n_circid_chan(circ, 0, NULL);
  528. if (CIRCUIT_IS_ORIGIN(circ)) {
  529. circuit_mark_for_close(circ, reason|END_CIRC_REASON_FLAG_REMOTE);
  530. } else {
  531. char payload[1];
  532. log_debug(LD_OR, "Delivering 'truncated' back.");
  533. payload[0] = (char)reason;
  534. relay_send_command_from_edge(0, circ, RELAY_COMMAND_TRUNCATED,
  535. payload, sizeof(payload), NULL);
  536. }
  537. }
  538. }
  539. /** Callback to handle a new channel; call command_setup_channel() to give
  540. * it the right cell handlers.
  541. */
  542. static void
  543. command_handle_incoming_channel(channel_listener_t *listener, channel_t *chan)
  544. {
  545. tor_assert(listener);
  546. tor_assert(chan);
  547. command_setup_channel(chan);
  548. }
  549. /** Given a channel, install the right handlers to process incoming
  550. * cells on it.
  551. */
  552. void
  553. command_setup_channel(channel_t *chan)
  554. {
  555. tor_assert(chan);
  556. channel_set_cell_handlers(chan,
  557. command_process_cell,
  558. command_process_var_cell);
  559. }
  560. /** Given a listener, install the right handler to process incoming
  561. * channels on it.
  562. */
  563. void
  564. command_setup_listener(channel_listener_t *listener)
  565. {
  566. tor_assert(listener);
  567. tor_assert(listener->state == CHANNEL_LISTENER_STATE_LISTENING);
  568. channel_listener_set_listener_fn(listener, command_handle_incoming_channel);
  569. }