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Diffstat (limited to 'src/core/crypto/onion.c')
| -rw-r--r-- | src/core/crypto/onion.c | 1346 |
1 files changed, 1346 insertions, 0 deletions
diff --git a/src/core/crypto/onion.c b/src/core/crypto/onion.c new file mode 100644 index 0000000000..80d8e1a8b1 --- /dev/null +++ b/src/core/crypto/onion.c @@ -0,0 +1,1346 @@ +/* Copyright (c) 2001 Matej Pfajfar. + * Copyright (c) 2001-2004, Roger Dingledine. + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2018, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file onion.c + * \brief Functions to queue create cells, wrap the various onionskin types, + * and parse and create the CREATE cell and its allies. + * + * This module has a few functions, all related to the CREATE/CREATED + * handshake that we use on links in order to create a circuit, and the + * related EXTEND/EXTENDED handshake that we use over circuits in order to + * extend them an additional hop. + * + * In this module, we provide a set of abstractions to create a uniform + * interface over the three circuit extension handshakes that Tor has used + * over the years (TAP, CREATE_FAST, and ntor). These handshakes are + * implemented in onion_tap.c, onion_fast.c, and onion_ntor.c respectively. + * + * All[*] of these handshakes follow a similar pattern: a client, knowing + * some key from the relay it wants to extend through, generates the + * first part of a handshake. A relay receives that handshake, and sends + * a reply. Once the client handles the reply, it knows that it is + * talking to the right relay, and it shares some freshly negotiated key + * material with that relay. + * + * We sometimes call the client's part of the handshake an "onionskin". + * We do this because historically, Onion Routing used a multi-layer + * structure called an "onion" to construct circuits. Each layer of the + * onion contained key material chosen by the client, the identity of + * the next relay in the circuit, and a smaller onion, encrypted with + * the key of the next relay. When we changed Tor to use a telescoping + * circuit extension design, it corresponded to sending each layer of the + * onion separately -- as a series of onionskins. + * + * Clients invoke these functions when creating or extending a circuit, + * from circuitbuild.c. + * + * Relays invoke these functions when they receive a CREATE or EXTEND + * cell in command.c or relay.c, in order to queue the pending request. + * They also invoke them from cpuworker.c, which handles dispatching + * onionskin requests to different worker threads. + * + * <br> + * + * This module also handles: + * <ul> + * <li> Queueing incoming onionskins on the relay side before passing + * them to worker threads. + * <li>Expiring onionskins on the relay side if they have waited for + * too long. + * <li>Packaging private keys on the server side in order to pass + * them to worker threads. + * <li>Encoding and decoding CREATE, CREATED, CREATE2, and CREATED2 cells. + * <li>Encoding and decodign EXTEND, EXTENDED, EXTEND2, and EXTENDED2 + * relay cells. + * </ul> + * + * [*] The CREATE_FAST handshake is weaker than described here; see + * onion_fast.c for more information. + **/ + +#include "or/or.h" +#include "or/circuitbuild.h" +#include "or/circuitlist.h" +#include "or/config.h" +#include "or/cpuworker.h" +#include "lib/crypt_ops/crypto_util.h" +#include "lib/crypt_ops/crypto_dh.h" +#include "or/networkstatus.h" +#include "or/onion.h" +#include "or/onion_fast.h" +#include "or/onion_ntor.h" +#include "or/onion_tap.h" +#include "or/relay.h" +#include "or/rephist.h" +#include "or/router.h" + +#include "or/cell_st.h" +#include "or/extend_info_st.h" +#include "or/or_circuit_st.h" + +// trunnel +#include "trunnel/ed25519_cert.h" + +/** Type for a linked list of circuits that are waiting for a free CPU worker + * to process a waiting onion handshake. */ +typedef struct onion_queue_t { + TOR_TAILQ_ENTRY(onion_queue_t) next; + or_circuit_t *circ; + uint16_t handshake_type; + create_cell_t *onionskin; + time_t when_added; +} onion_queue_t; + +/** 5 seconds on the onion queue til we just send back a destroy */ +#define ONIONQUEUE_WAIT_CUTOFF 5 + +/** Array of queues of circuits waiting for CPU workers. An element is NULL + * if that queue is empty.*/ +static TOR_TAILQ_HEAD(onion_queue_head_t, onion_queue_t) + ol_list[MAX_ONION_HANDSHAKE_TYPE+1] = +{ TOR_TAILQ_HEAD_INITIALIZER(ol_list[0]), /* tap */ + TOR_TAILQ_HEAD_INITIALIZER(ol_list[1]), /* fast */ + TOR_TAILQ_HEAD_INITIALIZER(ol_list[2]), /* ntor */ +}; + +/** Number of entries of each type currently in each element of ol_list[]. */ +static int ol_entries[MAX_ONION_HANDSHAKE_TYPE+1]; + +static int num_ntors_per_tap(void); +static void onion_queue_entry_remove(onion_queue_t *victim); + +/* XXXX Check lengths vs MAX_ONIONSKIN_{CHALLENGE,REPLY}_LEN. + * + * (By which I think I meant, "make sure that no + * X_ONIONSKIN_CHALLENGE/REPLY_LEN is greater than + * MAX_ONIONSKIN_CHALLENGE/REPLY_LEN." Also, make sure that we can pass + * over-large values via EXTEND2/EXTENDED2, for future-compatibility.*/ + +/** Return true iff we have room to queue another onionskin of type + * <b>type</b>. */ +static int +have_room_for_onionskin(uint16_t type) +{ + const or_options_t *options = get_options(); + int num_cpus; + uint64_t tap_usec, ntor_usec; + uint64_t ntor_during_tap_usec, tap_during_ntor_usec; + + /* If we've got fewer than 50 entries, we always have room for one more. */ + if (ol_entries[type] < 50) + return 1; + num_cpus = get_num_cpus(options); + /* Compute how many microseconds we'd expect to need to clear all + * onionskins in various combinations of the queues. */ + + /* How long would it take to process all the TAP cells in the queue? */ + tap_usec = estimated_usec_for_onionskins( + ol_entries[ONION_HANDSHAKE_TYPE_TAP], + ONION_HANDSHAKE_TYPE_TAP) / num_cpus; + + /* How long would it take to process all the NTor cells in the queue? */ + ntor_usec = estimated_usec_for_onionskins( + ol_entries[ONION_HANDSHAKE_TYPE_NTOR], + ONION_HANDSHAKE_TYPE_NTOR) / num_cpus; + + /* How long would it take to process the tap cells that we expect to + * process while draining the ntor queue? */ + tap_during_ntor_usec = estimated_usec_for_onionskins( + MIN(ol_entries[ONION_HANDSHAKE_TYPE_TAP], + ol_entries[ONION_HANDSHAKE_TYPE_NTOR] / num_ntors_per_tap()), + ONION_HANDSHAKE_TYPE_TAP) / num_cpus; + + /* How long would it take to process the ntor cells that we expect to + * process while draining the tap queue? */ + ntor_during_tap_usec = estimated_usec_for_onionskins( + MIN(ol_entries[ONION_HANDSHAKE_TYPE_NTOR], + ol_entries[ONION_HANDSHAKE_TYPE_TAP] * num_ntors_per_tap()), + ONION_HANDSHAKE_TYPE_NTOR) / num_cpus; + + /* See whether that exceeds MaxOnionQueueDelay. If so, we can't queue + * this. */ + if (type == ONION_HANDSHAKE_TYPE_NTOR && + (ntor_usec + tap_during_ntor_usec) / 1000 > + (uint64_t)options->MaxOnionQueueDelay) + return 0; + + if (type == ONION_HANDSHAKE_TYPE_TAP && + (tap_usec + ntor_during_tap_usec) / 1000 > + (uint64_t)options->MaxOnionQueueDelay) + return 0; + + /* If we support the ntor handshake, then don't let TAP handshakes use + * more than 2/3 of the space on the queue. */ + if (type == ONION_HANDSHAKE_TYPE_TAP && + tap_usec / 1000 > (uint64_t)options->MaxOnionQueueDelay * 2 / 3) + return 0; + + return 1; +} + +/** Add <b>circ</b> to the end of ol_list and return 0, except + * if ol_list is too long, in which case do nothing and return -1. + */ +int +onion_pending_add(or_circuit_t *circ, create_cell_t *onionskin) +{ + onion_queue_t *tmp; + time_t now = time(NULL); + + if (onionskin->handshake_type > MAX_ONION_HANDSHAKE_TYPE) { + /* LCOV_EXCL_START + * We should have rejected this far before this point */ + log_warn(LD_BUG, "Handshake %d out of range! Dropping.", + onionskin->handshake_type); + return -1; + /* LCOV_EXCL_STOP */ + } + + tmp = tor_malloc_zero(sizeof(onion_queue_t)); + tmp->circ = circ; + tmp->handshake_type = onionskin->handshake_type; + tmp->onionskin = onionskin; + tmp->when_added = now; + + if (!have_room_for_onionskin(onionskin->handshake_type)) { +#define WARN_TOO_MANY_CIRC_CREATIONS_INTERVAL (60) + static ratelim_t last_warned = + RATELIM_INIT(WARN_TOO_MANY_CIRC_CREATIONS_INTERVAL); + char *m; + if (onionskin->handshake_type == ONION_HANDSHAKE_TYPE_NTOR && + (m = rate_limit_log(&last_warned, approx_time()))) { + log_warn(LD_GENERAL, + "Your computer is too slow to handle this many circuit " + "creation requests! Please consider using the " + "MaxAdvertisedBandwidth config option or choosing a more " + "restricted exit policy.%s",m); + tor_free(m); + } + tor_free(tmp); + return -1; + } + + ++ol_entries[onionskin->handshake_type]; + log_info(LD_OR, "New create (%s). Queues now ntor=%d and tap=%d.", + onionskin->handshake_type == ONION_HANDSHAKE_TYPE_NTOR ? "ntor" : "tap", + ol_entries[ONION_HANDSHAKE_TYPE_NTOR], + ol_entries[ONION_HANDSHAKE_TYPE_TAP]); + + circ->onionqueue_entry = tmp; + TOR_TAILQ_INSERT_TAIL(&ol_list[onionskin->handshake_type], tmp, next); + + /* cull elderly requests. */ + while (1) { + onion_queue_t *head = TOR_TAILQ_FIRST(&ol_list[onionskin->handshake_type]); + if (now - head->when_added < (time_t)ONIONQUEUE_WAIT_CUTOFF) + break; + + circ = head->circ; + circ->onionqueue_entry = NULL; + onion_queue_entry_remove(head); + log_info(LD_CIRC, + "Circuit create request is too old; canceling due to overload."); + if (! TO_CIRCUIT(circ)->marked_for_close) { + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_RESOURCELIMIT); + } + } + return 0; +} + +/** Return a fairness parameter, to prefer processing NTOR style + * handshakes but still slowly drain the TAP queue so we don't starve + * it entirely. */ +static int +num_ntors_per_tap(void) +{ +#define DEFAULT_NUM_NTORS_PER_TAP 10 +#define MIN_NUM_NTORS_PER_TAP 1 +#define MAX_NUM_NTORS_PER_TAP 100000 + + return networkstatus_get_param(NULL, "NumNTorsPerTAP", + DEFAULT_NUM_NTORS_PER_TAP, + MIN_NUM_NTORS_PER_TAP, + MAX_NUM_NTORS_PER_TAP); +} + +/** Choose which onion queue we'll pull from next. If one is empty choose + * the other; if they both have elements, load balance across them but + * favoring NTOR. */ +static uint16_t +decide_next_handshake_type(void) +{ + /* The number of times we've chosen ntor lately when both were available. */ + static int recently_chosen_ntors = 0; + + if (!ol_entries[ONION_HANDSHAKE_TYPE_NTOR]) + return ONION_HANDSHAKE_TYPE_TAP; /* no ntors? try tap */ + + if (!ol_entries[ONION_HANDSHAKE_TYPE_TAP]) { + + /* Nick wants us to prioritize new tap requests when there aren't + * any in the queue and we've processed k ntor cells since the last + * tap cell. This strategy is maybe a good idea, since it starves tap + * less in the case where tap is rare, or maybe a poor idea, since it + * makes the new tap cell unfairly jump in front of ntor cells that + * got here first. In any case this edge case will only become relevant + * once tap is rare. We should reevaluate whether we like this decision + * once tap gets more rare. */ + if (ol_entries[ONION_HANDSHAKE_TYPE_NTOR] && + recently_chosen_ntors <= num_ntors_per_tap()) + ++recently_chosen_ntors; + + return ONION_HANDSHAKE_TYPE_NTOR; /* no taps? try ntor */ + } + + /* They both have something queued. Pick ntor if we haven't done that + * too much lately. */ + if (++recently_chosen_ntors <= num_ntors_per_tap()) { + return ONION_HANDSHAKE_TYPE_NTOR; + } + + /* Else, it's time to let tap have its turn. */ + recently_chosen_ntors = 0; + return ONION_HANDSHAKE_TYPE_TAP; +} + +/** Remove the highest priority item from ol_list[] and return it, or + * return NULL if the lists are empty. + */ +or_circuit_t * +onion_next_task(create_cell_t **onionskin_out) +{ + or_circuit_t *circ; + uint16_t handshake_to_choose = decide_next_handshake_type(); + onion_queue_t *head = TOR_TAILQ_FIRST(&ol_list[handshake_to_choose]); + + if (!head) + return NULL; /* no onions pending, we're done */ + + tor_assert(head->circ); + tor_assert(head->handshake_type <= MAX_ONION_HANDSHAKE_TYPE); +// tor_assert(head->circ->p_chan); /* make sure it's still valid */ +/* XXX I only commented out the above line to make the unit tests + * more manageable. That's probably not good long-term. -RD */ + circ = head->circ; + if (head->onionskin) + --ol_entries[head->handshake_type]; + log_info(LD_OR, "Processing create (%s). Queues now ntor=%d and tap=%d.", + head->handshake_type == ONION_HANDSHAKE_TYPE_NTOR ? "ntor" : "tap", + ol_entries[ONION_HANDSHAKE_TYPE_NTOR], + ol_entries[ONION_HANDSHAKE_TYPE_TAP]); + + *onionskin_out = head->onionskin; + head->onionskin = NULL; /* prevent free. */ + circ->onionqueue_entry = NULL; + onion_queue_entry_remove(head); + return circ; +} + +/** Return the number of <b>handshake_type</b>-style create requests pending. + */ +int +onion_num_pending(uint16_t handshake_type) +{ + return ol_entries[handshake_type]; +} + +/** Go through ol_list, find the onion_queue_t element which points to + * circ, remove and free that element. Leave circ itself alone. + */ +void +onion_pending_remove(or_circuit_t *circ) +{ + onion_queue_t *victim; + + if (!circ) + return; + + victim = circ->onionqueue_entry; + if (victim) + onion_queue_entry_remove(victim); + + cpuworker_cancel_circ_handshake(circ); +} + +/** Remove a queue entry <b>victim</b> from the queue, unlinking it from + * its circuit and freeing it and any structures it owns.*/ +static void +onion_queue_entry_remove(onion_queue_t *victim) +{ + if (victim->handshake_type > MAX_ONION_HANDSHAKE_TYPE) { + /* LCOV_EXCL_START + * We should have rejected this far before this point */ + log_warn(LD_BUG, "Handshake %d out of range! Dropping.", + victim->handshake_type); + /* XXX leaks */ + return; + /* LCOV_EXCL_STOP */ + } + + TOR_TAILQ_REMOVE(&ol_list[victim->handshake_type], victim, next); + + if (victim->circ) + victim->circ->onionqueue_entry = NULL; + + if (victim->onionskin) + --ol_entries[victim->handshake_type]; + + tor_free(victim->onionskin); + tor_free(victim); +} + +/** Remove all circuits from the pending list. Called from tor_free_all. */ +void +clear_pending_onions(void) +{ + onion_queue_t *victim, *next; + int i; + for (i=0; i<=MAX_ONION_HANDSHAKE_TYPE; i++) { + for (victim = TOR_TAILQ_FIRST(&ol_list[i]); victim; victim = next) { + next = TOR_TAILQ_NEXT(victim,next); + onion_queue_entry_remove(victim); + } + tor_assert(TOR_TAILQ_EMPTY(&ol_list[i])); + } + memset(ol_entries, 0, sizeof(ol_entries)); +} + +/* ============================================================ */ + +/** Return a new server_onion_keys_t object with all of the keys + * and other info we might need to do onion handshakes. (We make a copy of + * our keys for each cpuworker to avoid race conditions with the main thread, + * and to avoid locking) */ +server_onion_keys_t * +server_onion_keys_new(void) +{ + server_onion_keys_t *keys = tor_malloc_zero(sizeof(server_onion_keys_t)); + memcpy(keys->my_identity, router_get_my_id_digest(), DIGEST_LEN); + dup_onion_keys(&keys->onion_key, &keys->last_onion_key); + keys->curve25519_key_map = construct_ntor_key_map(); + keys->junk_keypair = tor_malloc_zero(sizeof(curve25519_keypair_t)); + curve25519_keypair_generate(keys->junk_keypair, 0); + return keys; +} + +/** Release all storage held in <b>keys</b>. */ +void +server_onion_keys_free_(server_onion_keys_t *keys) +{ + if (! keys) + return; + + crypto_pk_free(keys->onion_key); + crypto_pk_free(keys->last_onion_key); + ntor_key_map_free(keys->curve25519_key_map); + tor_free(keys->junk_keypair); + memwipe(keys, 0, sizeof(server_onion_keys_t)); + tor_free(keys); +} + +/** Release whatever storage is held in <b>state</b>, depending on its + * type, and clear its pointer. */ +void +onion_handshake_state_release(onion_handshake_state_t *state) +{ + switch (state->tag) { + case ONION_HANDSHAKE_TYPE_TAP: + crypto_dh_free(state->u.tap); + state->u.tap = NULL; + break; + case ONION_HANDSHAKE_TYPE_FAST: + fast_handshake_state_free(state->u.fast); + state->u.fast = NULL; + break; + case ONION_HANDSHAKE_TYPE_NTOR: + ntor_handshake_state_free(state->u.ntor); + state->u.ntor = NULL; + break; + default: + /* LCOV_EXCL_START + * This state should not even exist. */ + log_warn(LD_BUG, "called with unknown handshake state type %d", + (int)state->tag); + tor_fragile_assert(); + /* LCOV_EXCL_STOP */ + } +} + +/** Perform the first step of a circuit-creation handshake of type <b>type</b> + * (one of ONION_HANDSHAKE_TYPE_*): generate the initial "onion skin" in + * <b>onion_skin_out</b>, and store any state information in <b>state_out</b>. + * Return -1 on failure, and the length of the onionskin on acceptance. + */ +int +onion_skin_create(int type, + const extend_info_t *node, + onion_handshake_state_t *state_out, + uint8_t *onion_skin_out) +{ + int r = -1; + + switch (type) { + case ONION_HANDSHAKE_TYPE_TAP: + if (!node->onion_key) + return -1; + + if (onion_skin_TAP_create(node->onion_key, + &state_out->u.tap, + (char*)onion_skin_out) < 0) + return -1; + + r = TAP_ONIONSKIN_CHALLENGE_LEN; + break; + case ONION_HANDSHAKE_TYPE_FAST: + if (fast_onionskin_create(&state_out->u.fast, onion_skin_out) < 0) + return -1; + + r = CREATE_FAST_LEN; + break; + case ONION_HANDSHAKE_TYPE_NTOR: + if (!extend_info_supports_ntor(node)) + return -1; + if (onion_skin_ntor_create((const uint8_t*)node->identity_digest, + &node->curve25519_onion_key, + &state_out->u.ntor, + onion_skin_out) < 0) + return -1; + + r = NTOR_ONIONSKIN_LEN; + break; + default: + /* LCOV_EXCL_START + * We should never try to create an impossible handshake type. */ + log_warn(LD_BUG, "called with unknown handshake state type %d", type); + tor_fragile_assert(); + r = -1; + /* LCOV_EXCL_STOP */ + } + + if (r > 0) + state_out->tag = (uint16_t) type; + + return r; +} + +/* This is the maximum value for keys_out_len passed to + * onion_skin_server_handshake, plus 16. We can make it bigger if needed: + * It just defines how many bytes to stack-allocate. */ +#define MAX_KEYS_TMP_LEN 128 + +/** Perform the second (server-side) step of a circuit-creation handshake of + * type <b>type</b>, responding to the client request in <b>onion_skin</b> + * using the keys in <b>keys</b>. On success, write our response into + * <b>reply_out</b>, generate <b>keys_out_len</b> bytes worth of key material + * in <b>keys_out_len</b>, a hidden service nonce to <b>rend_nonce_out</b>, + * and return the length of the reply. On failure, return -1. + */ +int +onion_skin_server_handshake(int type, + const uint8_t *onion_skin, size_t onionskin_len, + const server_onion_keys_t *keys, + uint8_t *reply_out, + uint8_t *keys_out, size_t keys_out_len, + uint8_t *rend_nonce_out) +{ + int r = -1; + + switch (type) { + case ONION_HANDSHAKE_TYPE_TAP: + if (onionskin_len != TAP_ONIONSKIN_CHALLENGE_LEN) + return -1; + if (onion_skin_TAP_server_handshake((const char*)onion_skin, + keys->onion_key, keys->last_onion_key, + (char*)reply_out, + (char*)keys_out, keys_out_len)<0) + return -1; + r = TAP_ONIONSKIN_REPLY_LEN; + memcpy(rend_nonce_out, reply_out+DH1024_KEY_LEN, DIGEST_LEN); + break; + case ONION_HANDSHAKE_TYPE_FAST: + if (onionskin_len != CREATE_FAST_LEN) + return -1; + if (fast_server_handshake(onion_skin, reply_out, keys_out, keys_out_len)<0) + return -1; + r = CREATED_FAST_LEN; + memcpy(rend_nonce_out, reply_out+DIGEST_LEN, DIGEST_LEN); + break; + case ONION_HANDSHAKE_TYPE_NTOR: + if (onionskin_len < NTOR_ONIONSKIN_LEN) + return -1; + { + size_t keys_tmp_len = keys_out_len + DIGEST_LEN; + tor_assert(keys_tmp_len <= MAX_KEYS_TMP_LEN); + uint8_t keys_tmp[MAX_KEYS_TMP_LEN]; + + if (onion_skin_ntor_server_handshake( + onion_skin, keys->curve25519_key_map, + keys->junk_keypair, + keys->my_identity, + reply_out, keys_tmp, keys_tmp_len)<0) { + /* no need to memwipe here, since the output will never be used */ + return -1; + } + + memcpy(keys_out, keys_tmp, keys_out_len); + memcpy(rend_nonce_out, keys_tmp+keys_out_len, DIGEST_LEN); + memwipe(keys_tmp, 0, sizeof(keys_tmp)); + r = NTOR_REPLY_LEN; + } + break; + default: + /* LCOV_EXCL_START + * We should have rejected this far before this point */ + log_warn(LD_BUG, "called with unknown handshake state type %d", type); + tor_fragile_assert(); + return -1; + /* LCOV_EXCL_STOP */ + } + + return r; +} + +/** Perform the final (client-side) step of a circuit-creation handshake of + * type <b>type</b>, using our state in <b>handshake_state</b> and the + * server's response in <b>reply</b>. On success, generate <b>keys_out_len</b> + * bytes worth of key material in <b>keys_out_len</b>, set + * <b>rend_authenticator_out</b> to the "KH" field that can be used to + * establish introduction points at this hop, and return 0. On failure, + * return -1, and set *msg_out to an error message if this is worth + * complaining to the user about. */ +int +onion_skin_client_handshake(int type, + const onion_handshake_state_t *handshake_state, + const uint8_t *reply, size_t reply_len, + uint8_t *keys_out, size_t keys_out_len, + uint8_t *rend_authenticator_out, + const char **msg_out) +{ + if (handshake_state->tag != type) + return -1; + + switch (type) { + case ONION_HANDSHAKE_TYPE_TAP: + if (reply_len != TAP_ONIONSKIN_REPLY_LEN) { + if (msg_out) + *msg_out = "TAP reply was not of the correct length."; + return -1; + } + if (onion_skin_TAP_client_handshake(handshake_state->u.tap, + (const char*)reply, + (char *)keys_out, keys_out_len, + msg_out) < 0) + return -1; + + memcpy(rend_authenticator_out, reply+DH1024_KEY_LEN, DIGEST_LEN); + + return 0; + case ONION_HANDSHAKE_TYPE_FAST: + if (reply_len != CREATED_FAST_LEN) { + if (msg_out) + *msg_out = "TAP reply was not of the correct length."; + return -1; + } + if (fast_client_handshake(handshake_state->u.fast, reply, + keys_out, keys_out_len, msg_out) < 0) + return -1; + + memcpy(rend_authenticator_out, reply+DIGEST_LEN, DIGEST_LEN); + return 0; + case ONION_HANDSHAKE_TYPE_NTOR: + if (reply_len < NTOR_REPLY_LEN) { + if (msg_out) + *msg_out = "ntor reply was not of the correct length."; + return -1; + } + { + size_t keys_tmp_len = keys_out_len + DIGEST_LEN; + uint8_t *keys_tmp = tor_malloc(keys_tmp_len); + if (onion_skin_ntor_client_handshake(handshake_state->u.ntor, + reply, + keys_tmp, keys_tmp_len, msg_out) < 0) { + tor_free(keys_tmp); + return -1; + } + memcpy(keys_out, keys_tmp, keys_out_len); + memcpy(rend_authenticator_out, keys_tmp + keys_out_len, DIGEST_LEN); + memwipe(keys_tmp, 0, keys_tmp_len); + tor_free(keys_tmp); + } + return 0; + default: + log_warn(LD_BUG, "called with unknown handshake state type %d", type); + tor_fragile_assert(); + return -1; + } +} + +/** Helper: return 0 if <b>cell</b> appears valid, -1 otherwise. If + * <b>unknown_ok</b> is true, allow cells with handshake types we don't + * recognize. */ +static int +check_create_cell(const create_cell_t *cell, int unknown_ok) +{ + switch (cell->cell_type) { + case CELL_CREATE: + if (cell->handshake_type != ONION_HANDSHAKE_TYPE_TAP && + cell->handshake_type != ONION_HANDSHAKE_TYPE_NTOR) + return -1; + break; + case CELL_CREATE_FAST: + if (cell->handshake_type != ONION_HANDSHAKE_TYPE_FAST) + return -1; + break; + case CELL_CREATE2: + break; + default: + return -1; + } + + switch (cell->handshake_type) { + case ONION_HANDSHAKE_TYPE_TAP: + if (cell->handshake_len != TAP_ONIONSKIN_CHALLENGE_LEN) + return -1; + break; + case ONION_HANDSHAKE_TYPE_FAST: + if (cell->handshake_len != CREATE_FAST_LEN) + return -1; + break; + case ONION_HANDSHAKE_TYPE_NTOR: + if (cell->handshake_len != NTOR_ONIONSKIN_LEN) + return -1; + break; + default: + if (! unknown_ok) + return -1; + } + + return 0; +} + +/** Write the various parameters into the create cell. Separate from + * create_cell_parse() to make unit testing easier. + */ +void +create_cell_init(create_cell_t *cell_out, uint8_t cell_type, + uint16_t handshake_type, uint16_t handshake_len, + const uint8_t *onionskin) +{ + memset(cell_out, 0, sizeof(*cell_out)); + + cell_out->cell_type = cell_type; + cell_out->handshake_type = handshake_type; + cell_out->handshake_len = handshake_len; + memcpy(cell_out->onionskin, onionskin, handshake_len); +} + +/** Helper: parse the CREATE2 payload at <b>p</b>, which could be up to + * <b>p_len</b> bytes long, and use it to fill the fields of + * <b>cell_out</b>. Return 0 on success and -1 on failure. + * + * Note that part of the body of an EXTEND2 cell is a CREATE2 payload, so + * this function is also used for parsing those. + */ +static int +parse_create2_payload(create_cell_t *cell_out, const uint8_t *p, size_t p_len) +{ + uint16_t handshake_type, handshake_len; + + if (p_len < 4) + return -1; + + handshake_type = ntohs(get_uint16(p)); + handshake_len = ntohs(get_uint16(p+2)); + + if (handshake_len > CELL_PAYLOAD_SIZE - 4 || handshake_len > p_len - 4) + return -1; + if (handshake_type == ONION_HANDSHAKE_TYPE_FAST) + return -1; + + create_cell_init(cell_out, CELL_CREATE2, handshake_type, handshake_len, + p+4); + return 0; +} + +/** Magic string which, in a CREATE or EXTEND cell, indicates that a seeming + * TAP payload is really an ntor payload. We'd do away with this if every + * relay supported EXTEND2, but we want to be able to extend from A to B with + * ntor even when A doesn't understand EXTEND2 and so can't generate a + * CREATE2 cell. + **/ +#define NTOR_CREATE_MAGIC "ntorNTORntorNTOR" + +/** Parse a CREATE, CREATE_FAST, or CREATE2 cell from <b>cell_in</b> into + * <b>cell_out</b>. Return 0 on success, -1 on failure. (We reject some + * syntactically valid CREATE2 cells that we can't generate or react to.) */ +int +create_cell_parse(create_cell_t *cell_out, const cell_t *cell_in) +{ + switch (cell_in->command) { + case CELL_CREATE: + if (tor_memeq(cell_in->payload, NTOR_CREATE_MAGIC, 16)) { + create_cell_init(cell_out, CELL_CREATE, ONION_HANDSHAKE_TYPE_NTOR, + NTOR_ONIONSKIN_LEN, cell_in->payload+16); + } else { + create_cell_init(cell_out, CELL_CREATE, ONION_HANDSHAKE_TYPE_TAP, + TAP_ONIONSKIN_CHALLENGE_LEN, cell_in->payload); + } + break; + case CELL_CREATE_FAST: + create_cell_init(cell_out, CELL_CREATE_FAST, ONION_HANDSHAKE_TYPE_FAST, + CREATE_FAST_LEN, cell_in->payload); + break; + case CELL_CREATE2: + if (parse_create2_payload(cell_out, cell_in->payload, + CELL_PAYLOAD_SIZE) < 0) + return -1; + break; + default: + return -1; + } + + return check_create_cell(cell_out, 0); +} + +/** Helper: return 0 if <b>cell</b> appears valid, -1 otherwise. */ +static int +check_created_cell(const created_cell_t *cell) +{ + switch (cell->cell_type) { + case CELL_CREATED: + if (cell->handshake_len != TAP_ONIONSKIN_REPLY_LEN && + cell->handshake_len != NTOR_REPLY_LEN) + return -1; + break; + case CELL_CREATED_FAST: + if (cell->handshake_len != CREATED_FAST_LEN) + return -1; + break; + case CELL_CREATED2: + if (cell->handshake_len > RELAY_PAYLOAD_SIZE-2) + return -1; + break; + } + + return 0; +} + +/** Parse a CREATED, CREATED_FAST, or CREATED2 cell from <b>cell_in</b> into + * <b>cell_out</b>. Return 0 on success, -1 on failure. */ +int +created_cell_parse(created_cell_t *cell_out, const cell_t *cell_in) +{ + memset(cell_out, 0, sizeof(*cell_out)); + + switch (cell_in->command) { + case CELL_CREATED: + cell_out->cell_type = CELL_CREATED; + cell_out->handshake_len = TAP_ONIONSKIN_REPLY_LEN; + memcpy(cell_out->reply, cell_in->payload, TAP_ONIONSKIN_REPLY_LEN); + break; + case CELL_CREATED_FAST: + cell_out->cell_type = CELL_CREATED_FAST; + cell_out->handshake_len = CREATED_FAST_LEN; + memcpy(cell_out->reply, cell_in->payload, CREATED_FAST_LEN); + break; + case CELL_CREATED2: + { + const uint8_t *p = cell_in->payload; + cell_out->cell_type = CELL_CREATED2; + cell_out->handshake_len = ntohs(get_uint16(p)); + if (cell_out->handshake_len > CELL_PAYLOAD_SIZE - 2) + return -1; + memcpy(cell_out->reply, p+2, cell_out->handshake_len); + break; + } + } + + return check_created_cell(cell_out); +} + +/** Helper: return 0 if <b>cell</b> appears valid, -1 otherwise. */ +static int +check_extend_cell(const extend_cell_t *cell) +{ + if (tor_digest_is_zero((const char*)cell->node_id)) + return -1; + /* We don't currently allow EXTEND2 cells without an IPv4 address */ + if (tor_addr_family(&cell->orport_ipv4.addr) == AF_UNSPEC) + return -1; + if (cell->create_cell.cell_type == CELL_CREATE) { + if (cell->cell_type != RELAY_COMMAND_EXTEND) + return -1; + } else if (cell->create_cell.cell_type == CELL_CREATE2) { + if (cell->cell_type != RELAY_COMMAND_EXTEND2 && + cell->cell_type != RELAY_COMMAND_EXTEND) + return -1; + } else { + /* In particular, no CREATE_FAST cells are allowed */ + return -1; + } + if (cell->create_cell.handshake_type == ONION_HANDSHAKE_TYPE_FAST) + return -1; + + return check_create_cell(&cell->create_cell, 1); +} + +static int +extend_cell_from_extend1_cell_body(extend_cell_t *cell_out, + const extend1_cell_body_t *cell) +{ + tor_assert(cell_out); + tor_assert(cell); + memset(cell_out, 0, sizeof(*cell_out)); + tor_addr_make_unspec(&cell_out->orport_ipv4.addr); + tor_addr_make_unspec(&cell_out->orport_ipv6.addr); + + cell_out->cell_type = RELAY_COMMAND_EXTEND; + tor_addr_from_ipv4h(&cell_out->orport_ipv4.addr, cell->ipv4addr); + cell_out->orport_ipv4.port = cell->port; + if (tor_memeq(cell->onionskin, NTOR_CREATE_MAGIC, 16)) { + cell_out->create_cell.cell_type = CELL_CREATE2; + cell_out->create_cell.handshake_type = ONION_HANDSHAKE_TYPE_NTOR; + cell_out->create_cell.handshake_len = NTOR_ONIONSKIN_LEN; + memcpy(cell_out->create_cell.onionskin, cell->onionskin + 16, + NTOR_ONIONSKIN_LEN); + } else { + cell_out->create_cell.cell_type = CELL_CREATE; + cell_out->create_cell.handshake_type = ONION_HANDSHAKE_TYPE_TAP; + cell_out->create_cell.handshake_len = TAP_ONIONSKIN_CHALLENGE_LEN; + memcpy(cell_out->create_cell.onionskin, cell->onionskin, + TAP_ONIONSKIN_CHALLENGE_LEN); + } + memcpy(cell_out->node_id, cell->identity, DIGEST_LEN); + return 0; +} + +static int +create_cell_from_create2_cell_body(create_cell_t *cell_out, + const create2_cell_body_t *cell) +{ + tor_assert(cell_out); + tor_assert(cell); + memset(cell_out, 0, sizeof(create_cell_t)); + if (BUG(cell->handshake_len > sizeof(cell_out->onionskin))) { + /* This should be impossible because there just isn't enough room in the + * input cell to make the handshake_len this large and provide a + * handshake_data to match. */ + return -1; + } + + cell_out->cell_type = CELL_CREATE2; + cell_out->handshake_type = cell->handshake_type; + cell_out->handshake_len = cell->handshake_len; + memcpy(cell_out->onionskin, + create2_cell_body_getconstarray_handshake_data(cell), + cell->handshake_len); + return 0; +} + +static int +extend_cell_from_extend2_cell_body(extend_cell_t *cell_out, + const extend2_cell_body_t *cell) +{ + tor_assert(cell_out); + tor_assert(cell); + int found_ipv4 = 0, found_ipv6 = 0, found_rsa_id = 0, found_ed_id = 0; + memset(cell_out, 0, sizeof(*cell_out)); + tor_addr_make_unspec(&cell_out->orport_ipv4.addr); + tor_addr_make_unspec(&cell_out->orport_ipv6.addr); + cell_out->cell_type = RELAY_COMMAND_EXTEND2; + + unsigned i; + for (i = 0; i < cell->n_spec; ++i) { + const link_specifier_t *ls = extend2_cell_body_getconst_ls(cell, i); + switch (ls->ls_type) { + case LS_IPV4: + if (found_ipv4) + continue; + found_ipv4 = 1; + tor_addr_from_ipv4h(&cell_out->orport_ipv4.addr, ls->un_ipv4_addr); + cell_out->orport_ipv4.port = ls->un_ipv4_port; + break; + case LS_IPV6: + if (found_ipv6) + continue; + found_ipv6 = 1; + tor_addr_from_ipv6_bytes(&cell_out->orport_ipv6.addr, + (const char *)ls->un_ipv6_addr); + cell_out->orport_ipv6.port = ls->un_ipv6_port; + break; + case LS_LEGACY_ID: + if (found_rsa_id) + return -1; + found_rsa_id = 1; + memcpy(cell_out->node_id, ls->un_legacy_id, 20); + break; + case LS_ED25519_ID: + if (found_ed_id) + return -1; + found_ed_id = 1; + memcpy(cell_out->ed_pubkey.pubkey, ls->un_ed25519_id, 32); + break; + default: + /* Ignore this, whatever it is. */ + break; + } + } + + if (!found_rsa_id || !found_ipv4) /* These are mandatory */ + return -1; + + return create_cell_from_create2_cell_body(&cell_out->create_cell, + cell->create2); +} + +/** Parse an EXTEND or EXTEND2 cell (according to <b>command</b>) from the + * <b>payload_length</b> bytes of <b>payload</b> into <b>cell_out</b>. Return + * 0 on success, -1 on failure. */ +int +extend_cell_parse(extend_cell_t *cell_out, const uint8_t command, + const uint8_t *payload, size_t payload_length) +{ + + tor_assert(cell_out); + tor_assert(payload); + + if (payload_length > RELAY_PAYLOAD_SIZE) + return -1; + + switch (command) { + case RELAY_COMMAND_EXTEND: + { + extend1_cell_body_t *cell = NULL; + if (extend1_cell_body_parse(&cell, payload, payload_length)<0 || + cell == NULL) { + if (cell) + extend1_cell_body_free(cell); + return -1; + } + int r = extend_cell_from_extend1_cell_body(cell_out, cell); + extend1_cell_body_free(cell); + if (r < 0) + return r; + } + break; + case RELAY_COMMAND_EXTEND2: + { + extend2_cell_body_t *cell = NULL; + if (extend2_cell_body_parse(&cell, payload, payload_length) < 0 || + cell == NULL) { + if (cell) + extend2_cell_body_free(cell); + return -1; + } + int r = extend_cell_from_extend2_cell_body(cell_out, cell); + extend2_cell_body_free(cell); + if (r < 0) + return r; + } + break; + default: + return -1; + } + + return check_extend_cell(cell_out); +} + +/** Helper: return 0 if <b>cell</b> appears valid, -1 otherwise. */ +static int +check_extended_cell(const extended_cell_t *cell) +{ + tor_assert(cell); + if (cell->created_cell.cell_type == CELL_CREATED) { + if (cell->cell_type != RELAY_COMMAND_EXTENDED) + return -1; + } else if (cell->created_cell.cell_type == CELL_CREATED2) { + if (cell->cell_type != RELAY_COMMAND_EXTENDED2) + return -1; + } else { + return -1; + } + + return check_created_cell(&cell->created_cell); +} + +/** Parse an EXTENDED or EXTENDED2 cell (according to <b>command</b>) from the + * <b>payload_length</b> bytes of <b>payload</b> into <b>cell_out</b>. Return + * 0 on success, -1 on failure. */ +int +extended_cell_parse(extended_cell_t *cell_out, + const uint8_t command, const uint8_t *payload, + size_t payload_len) +{ + tor_assert(cell_out); + tor_assert(payload); + + memset(cell_out, 0, sizeof(*cell_out)); + if (payload_len > RELAY_PAYLOAD_SIZE) + return -1; + + switch (command) { + case RELAY_COMMAND_EXTENDED: + if (payload_len != TAP_ONIONSKIN_REPLY_LEN) + return -1; + cell_out->cell_type = RELAY_COMMAND_EXTENDED; + cell_out->created_cell.cell_type = CELL_CREATED; + cell_out->created_cell.handshake_len = TAP_ONIONSKIN_REPLY_LEN; + memcpy(cell_out->created_cell.reply, payload, TAP_ONIONSKIN_REPLY_LEN); + break; + case RELAY_COMMAND_EXTENDED2: + { + cell_out->cell_type = RELAY_COMMAND_EXTENDED2; + cell_out->created_cell.cell_type = CELL_CREATED2; + cell_out->created_cell.handshake_len = ntohs(get_uint16(payload)); + if (cell_out->created_cell.handshake_len > RELAY_PAYLOAD_SIZE - 2 || + cell_out->created_cell.handshake_len > payload_len - 2) + return -1; + memcpy(cell_out->created_cell.reply, payload+2, + cell_out->created_cell.handshake_len); + } + break; + default: + return -1; + } + + return check_extended_cell(cell_out); +} + +/** Fill <b>cell_out</b> with a correctly formatted version of the + * CREATE{,_FAST,2} cell in <b>cell_in</b>. Return 0 on success, -1 on + * failure. This is a cell we didn't originate if <b>relayed</b> is true. */ +static int +create_cell_format_impl(cell_t *cell_out, const create_cell_t *cell_in, + int relayed) +{ + uint8_t *p; + size_t space; + if (check_create_cell(cell_in, relayed) < 0) + return -1; + + memset(cell_out->payload, 0, sizeof(cell_out->payload)); + cell_out->command = cell_in->cell_type; + + p = cell_out->payload; + space = sizeof(cell_out->payload); + + switch (cell_in->cell_type) { + case CELL_CREATE: + if (cell_in->handshake_type == ONION_HANDSHAKE_TYPE_NTOR) { + memcpy(p, NTOR_CREATE_MAGIC, 16); + p += 16; + space -= 16; + } + /* Fall through */ + case CELL_CREATE_FAST: + tor_assert(cell_in->handshake_len <= space); + memcpy(p, cell_in->onionskin, cell_in->handshake_len); + break; + case CELL_CREATE2: + tor_assert(cell_in->handshake_len <= sizeof(cell_out->payload)-4); + set_uint16(cell_out->payload, htons(cell_in->handshake_type)); + set_uint16(cell_out->payload+2, htons(cell_in->handshake_len)); + memcpy(cell_out->payload + 4, cell_in->onionskin, cell_in->handshake_len); + break; + default: + return -1; + } + + return 0; +} + +int +create_cell_format(cell_t *cell_out, const create_cell_t *cell_in) +{ + return create_cell_format_impl(cell_out, cell_in, 0); +} + +int +create_cell_format_relayed(cell_t *cell_out, const create_cell_t *cell_in) +{ + return create_cell_format_impl(cell_out, cell_in, 1); +} + +/** Fill <b>cell_out</b> with a correctly formatted version of the + * CREATED{,_FAST,2} cell in <b>cell_in</b>. Return 0 on success, -1 on + * failure. */ +int +created_cell_format(cell_t *cell_out, const created_cell_t *cell_in) +{ + if (check_created_cell(cell_in) < 0) + return -1; + + memset(cell_out->payload, 0, sizeof(cell_out->payload)); + cell_out->command = cell_in->cell_type; + + switch (cell_in->cell_type) { + case CELL_CREATED: + case CELL_CREATED_FAST: + tor_assert(cell_in->handshake_len <= sizeof(cell_out->payload)); + memcpy(cell_out->payload, cell_in->reply, cell_in->handshake_len); + break; + case CELL_CREATED2: + tor_assert(cell_in->handshake_len <= sizeof(cell_out->payload)-2); + set_uint16(cell_out->payload, htons(cell_in->handshake_len)); + memcpy(cell_out->payload + 2, cell_in->reply, cell_in->handshake_len); + break; + default: + return -1; + } + return 0; +} + +/** Return true iff we are configured (by torrc or by the networkstatus + * parameters) to use Ed25519 identities in our Extend2 cells. */ +static int +should_include_ed25519_id_extend_cells(const networkstatus_t *ns, + const or_options_t *options) +{ + if (options->ExtendByEd25519ID != -1) + return options->ExtendByEd25519ID; /* The user has an opinion. */ + + return (int) networkstatus_get_param(ns, "ExtendByEd25519ID", + 0 /* default */, + 0 /* min */, + 1 /*max*/); +} + +/** Format the EXTEND{,2} cell in <b>cell_in</b>, storing its relay payload in + * <b>payload_out</b>, the number of bytes used in *<b>len_out</b>, and the + * relay command in *<b>command_out</b>. The <b>payload_out</b> must have + * RELAY_PAYLOAD_SIZE bytes available. Return 0 on success, -1 on failure. */ +int +extend_cell_format(uint8_t *command_out, uint16_t *len_out, + uint8_t *payload_out, const extend_cell_t *cell_in) +{ + uint8_t *p; + if (check_extend_cell(cell_in) < 0) + return -1; + + p = payload_out; + + memset(p, 0, RELAY_PAYLOAD_SIZE); + + switch (cell_in->cell_type) { + case RELAY_COMMAND_EXTEND: + { + *command_out = RELAY_COMMAND_EXTEND; + *len_out = 6 + TAP_ONIONSKIN_CHALLENGE_LEN + DIGEST_LEN; + set_uint32(p, tor_addr_to_ipv4n(&cell_in->orport_ipv4.addr)); + set_uint16(p+4, htons(cell_in->orport_ipv4.port)); + if (cell_in->create_cell.handshake_type == ONION_HANDSHAKE_TYPE_NTOR) { + memcpy(p+6, NTOR_CREATE_MAGIC, 16); + memcpy(p+22, cell_in->create_cell.onionskin, NTOR_ONIONSKIN_LEN); + } else { + memcpy(p+6, cell_in->create_cell.onionskin, + TAP_ONIONSKIN_CHALLENGE_LEN); + } + memcpy(p+6+TAP_ONIONSKIN_CHALLENGE_LEN, cell_in->node_id, DIGEST_LEN); + } + break; + case RELAY_COMMAND_EXTEND2: + { + uint8_t n_specifiers = 2; + *command_out = RELAY_COMMAND_EXTEND2; + extend2_cell_body_t *cell = extend2_cell_body_new(); + link_specifier_t *ls; + { + /* IPv4 specifier first. */ + ls = link_specifier_new(); + extend2_cell_body_add_ls(cell, ls); + ls->ls_type = LS_IPV4; + ls->ls_len = 6; + ls->un_ipv4_addr = tor_addr_to_ipv4h(&cell_in->orport_ipv4.addr); + ls->un_ipv4_port = cell_in->orport_ipv4.port; + } + { + /* Then RSA id */ + ls = link_specifier_new(); + extend2_cell_body_add_ls(cell, ls); + ls->ls_type = LS_LEGACY_ID; + ls->ls_len = DIGEST_LEN; + memcpy(ls->un_legacy_id, cell_in->node_id, DIGEST_LEN); + } + if (should_include_ed25519_id_extend_cells(NULL, get_options()) && + !ed25519_public_key_is_zero(&cell_in->ed_pubkey)) { + /* Then, maybe, the ed25519 id! */ + ++n_specifiers; + ls = link_specifier_new(); + extend2_cell_body_add_ls(cell, ls); + ls->ls_type = LS_ED25519_ID; + ls->ls_len = 32; + memcpy(ls->un_ed25519_id, cell_in->ed_pubkey.pubkey, 32); + } + cell->n_spec = n_specifiers; + + /* Now, the handshake */ + cell->create2 = create2_cell_body_new(); + cell->create2->handshake_type = cell_in->create_cell.handshake_type; + cell->create2->handshake_len = cell_in->create_cell.handshake_len; + create2_cell_body_setlen_handshake_data(cell->create2, + cell_in->create_cell.handshake_len); + memcpy(create2_cell_body_getarray_handshake_data(cell->create2), + cell_in->create_cell.onionskin, + cell_in->create_cell.handshake_len); + + ssize_t len_encoded = extend2_cell_body_encode( + payload_out, RELAY_PAYLOAD_SIZE, + cell); + extend2_cell_body_free(cell); + if (len_encoded < 0 || len_encoded > UINT16_MAX) + return -1; + *len_out = (uint16_t) len_encoded; + } + break; + default: + return -1; + } + + return 0; +} + +/** Format the EXTENDED{,2} cell in <b>cell_in</b>, storing its relay payload + * in <b>payload_out</b>, the number of bytes used in *<b>len_out</b>, and the + * relay command in *<b>command_out</b>. The <b>payload_out</b> must have + * RELAY_PAYLOAD_SIZE bytes available. Return 0 on success, -1 on failure. */ +int +extended_cell_format(uint8_t *command_out, uint16_t *len_out, + uint8_t *payload_out, const extended_cell_t *cell_in) +{ + uint8_t *p; + if (check_extended_cell(cell_in) < 0) + return -1; + + p = payload_out; + memset(p, 0, RELAY_PAYLOAD_SIZE); + + switch (cell_in->cell_type) { + case RELAY_COMMAND_EXTENDED: + { + *command_out = RELAY_COMMAND_EXTENDED; + *len_out = TAP_ONIONSKIN_REPLY_LEN; + memcpy(payload_out, cell_in->created_cell.reply, + TAP_ONIONSKIN_REPLY_LEN); + } + break; + case RELAY_COMMAND_EXTENDED2: + { + *command_out = RELAY_COMMAND_EXTENDED2; + *len_out = 2 + cell_in->created_cell.handshake_len; + set_uint16(payload_out, htons(cell_in->created_cell.handshake_len)); + if (2+cell_in->created_cell.handshake_len > RELAY_PAYLOAD_SIZE) + return -1; + memcpy(payload_out+2, cell_in->created_cell.reply, + cell_in->created_cell.handshake_len); + } + break; + default: + return -1; + } + + return 0; +} |