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0fd8f5781b
tor/src/or/onion.c
Roger Dingledine 0fd8f5781b fix typos
2013-08-23 21:43:57 -04:00

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/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2013, 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.
**/
#include "or.h"
#include "circuitlist.h"
#include "config.h"
#include "cpuworker.h"
#include "onion.h"
#include "onion_fast.h"
#include "onion_ntor.h"
#include "onion_tap.h"
#include "relay.h"
#include "rephist.h"
#include "router.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;
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
/** Queue of circuits waiting for CPU workers, or NULL if the list is empty.*/
TOR_TAILQ_HEAD(onion_queue_head_t, onion_queue_t) ol_list =
TOR_TAILQ_HEAD_INITIALIZER(ol_list);
/** Number of entries of each type currently in ol_list. */
static int ol_entries[MAX_ONION_HANDSHAKE_TYPE+1];
static void onion_queue_entry_remove(onion_queue_t *victim);
/* XXXX024 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;
/* If we've got fewer than 50 entries, we always have room for one more. */
if (ol_entries[ONION_HANDSHAKE_TYPE_TAP] +
ol_entries[ONION_HANDSHAKE_TYPE_NTOR] < 50)
return 1;
num_cpus = get_num_cpus(options);
/* Compute how many microseconds we'd expect to need to clear all
* onionskins in the current queue. */
tap_usec = estimated_usec_for_onionskins(
ol_entries[ONION_HANDSHAKE_TYPE_TAP],
ONION_HANDSHAKE_TYPE_TAP) / num_cpus;
ntor_usec = estimated_usec_for_onionskins(
ol_entries[ONION_HANDSHAKE_TYPE_NTOR],
ONION_HANDSHAKE_TYPE_NTOR) / num_cpus;
/* See whether that exceeds MaxOnionQueueDelay. If so, we can't queue
* this. */
if ((tap_usec + ntor_usec) / 1000 > (uint64_t)options->MaxOnionQueueDelay)
return 0;
#ifdef CURVE25519_ENABLED
/* 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;
#else
(void) type;
#endif
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);
tmp = tor_malloc_zero(sizeof(onion_queue_t));
tmp->circ = circ;
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 ((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];
circ->onionqueue_entry = tmp;
TOR_TAILQ_INSERT_TAIL(&ol_list, tmp, next);
/* cull elderly requests. */
while (1) {
onion_queue_t *head = TOR_TAILQ_FIRST(&ol_list);
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.");
circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_RESOURCELIMIT);
}
return 0;
}
/** Remove the first item from ol_list and return it, or return
* NULL if the list is empty.
*/
or_circuit_t *
onion_next_task(create_cell_t **onionskin_out)
{
or_circuit_t *circ;
onion_queue_t *head = TOR_TAILQ_FIRST(&ol_list);
if (!head)
return NULL; /* no onions pending, we're done */
tor_assert(head->circ);
tor_assert(head->circ->p_chan); /* make sure it's still valid */
circ = head->circ;
if (head->onionskin &&
head->onionskin->handshake_type <= MAX_ONION_HANDSHAKE_TYPE)
--ol_entries[head->onionskin->handshake_type];
*onionskin_out = head->onionskin;
head->onionskin = NULL; /* prevent free. */
circ->onionqueue_entry = NULL;
onion_queue_entry_remove(head);
return circ;
}
/** 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);
}
/** 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)
{
TOR_TAILQ_REMOVE(&ol_list, victim, next);
if (victim->circ)
victim->circ->onionqueue_entry = NULL;
if (victim->onionskin &&
victim->onionskin->handshake_type <= MAX_ONION_HANDSHAKE_TYPE)
--ol_entries[victim->onionskin->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;
while ((victim = TOR_TAILQ_FIRST(&ol_list))) {
onion_queue_entry_remove(victim);
}
memset(ol_entries, 0, sizeof(ol_entries));
}
/* ============================================================ */
/** Fill in a server_onion_keys_t object at <b>keys</b> 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) */
void
setup_server_onion_keys(server_onion_keys_t *keys)
{
memset(keys, 0, 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);
#ifdef CURVE25519_ENABLED
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);
#endif
}
/** Release all storage held in <b>keys</b>, but do not free <b>keys</b>
* itself (as it's likely to be stack-allocated.) */
void
release_server_onion_keys(server_onion_keys_t *keys)
{
if (! keys)
return;
crypto_pk_free(keys->onion_key);
crypto_pk_free(keys->last_onion_key);
#ifdef CURVE25519_ENABLED
ntor_key_map_free(keys->curve25519_key_map);
tor_free(keys->junk_keypair);
#endif
memset(keys, 0, sizeof(server_onion_keys_t));
}
/** 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;
#ifdef CURVE25519_ENABLED
case ONION_HANDSHAKE_TYPE_NTOR:
ntor_handshake_state_free(state->u.ntor);
state->u.ntor = NULL;
break;
#endif
default:
log_warn(LD_BUG, "called with unknown handshake state type %d",
(int)state->tag);
tor_fragile_assert();
}
}
/** 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:
#ifdef CURVE25519_ENABLED
if (tor_mem_is_zero((const char*)node->curve25519_onion_key.public_key,
CURVE25519_PUBKEY_LEN))
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;
#else
return -1;
#endif
break;
default:
log_warn(LD_BUG, "called with unknown handshake state type %d", type);
tor_fragile_assert();
r = -1;
}
if (r > 0)
state_out->tag = (uint16_t) type;
return r;
}
/** 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+DH_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:
#ifdef CURVE25519_ENABLED
if (onionskin_len < NTOR_ONIONSKIN_LEN)
return -1;
{
size_t keys_tmp_len = keys_out_len + DIGEST_LEN;
uint8_t *keys_tmp = tor_malloc(keys_out_len + DIGEST_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) {
tor_free(keys_tmp);
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, keys_tmp_len);
tor_free(keys_tmp);
r = NTOR_REPLY_LEN;
}
#else
return -1;
#endif
break;
default:
log_warn(LD_BUG, "called with unknown handshake state type %d", type);
tor_fragile_assert();
return -1;
}
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. */
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)
{
if (handshake_state->tag != type)
return -1;
switch (type) {
case ONION_HANDSHAKE_TYPE_TAP:
if (reply_len != TAP_ONIONSKIN_REPLY_LEN)
return -1;
if (onion_skin_TAP_client_handshake(handshake_state->u.tap,
(const char*)reply,
(char *)keys_out, keys_out_len) < 0)
return -1;
memcpy(rend_authenticator_out, reply+DH_KEY_LEN, DIGEST_LEN);
return 0;
case ONION_HANDSHAKE_TYPE_FAST:
if (reply_len != CREATED_FAST_LEN)
return -1;
if (fast_client_handshake(handshake_state->u.fast, reply,
keys_out, keys_out_len) < 0)
return -1;
memcpy(rend_authenticator_out, reply+DIGEST_LEN, DIGEST_LEN);
return 0;
#ifdef CURVE25519_ENABLED
case ONION_HANDSHAKE_TYPE_NTOR:
if (reply_len < NTOR_REPLY_LEN)
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) < 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;
#endif
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;
#ifdef CURVE25519_ENABLED
case ONION_HANDSHAKE_TYPE_NTOR:
if (cell->handshake_len != NTOR_ONIONSKIN_LEN)
return -1;
break;
#endif
default:
if (! unknown_ok)
return -1;
}
return 0;
}
/** 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)
{
if (p_len < 4)
return -1;
cell_out->cell_type = CELL_CREATE2;
cell_out->handshake_type = ntohs(get_uint16(p));
cell_out->handshake_len = ntohs(get_uint16(p+2));
if (cell_out->handshake_len > CELL_PAYLOAD_SIZE - 4 ||
cell_out->handshake_len > p_len - 4)
return -1;
if (cell_out->handshake_type == ONION_HANDSHAKE_TYPE_FAST)
return -1;
memcpy(cell_out->onionskin, p+4, cell_out->handshake_len);
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)
{
memset(cell_out, 0, sizeof(*cell_out));
switch (cell_in->command) {
case CELL_CREATE:
cell_out->cell_type = CELL_CREATE;
if (tor_memeq(cell_in->payload, NTOR_CREATE_MAGIC, 16)) {
cell_out->handshake_type = ONION_HANDSHAKE_TYPE_NTOR;
cell_out->handshake_len = NTOR_ONIONSKIN_LEN;
memcpy(cell_out->onionskin, cell_in->payload+16, NTOR_ONIONSKIN_LEN);
} else {
cell_out->handshake_type = ONION_HANDSHAKE_TYPE_TAP;
cell_out->handshake_len = TAP_ONIONSKIN_CHALLENGE_LEN;
memcpy(cell_out->onionskin, cell_in->payload,
TAP_ONIONSKIN_CHALLENGE_LEN);
}
break;
case CELL_CREATE_FAST:
cell_out->cell_type = CELL_CREATE_FAST;
cell_out->handshake_type = ONION_HANDSHAKE_TYPE_FAST;
cell_out->handshake_len = CREATE_FAST_LEN;
memcpy(cell_out->onionskin, cell_in->payload, CREATE_FAST_LEN);
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);
}
/** Protocol constants for specifier types in EXTEND2
* @{
*/
#define SPECTYPE_IPV4 0
#define SPECTYPE_IPV6 1
#define SPECTYPE_LEGACY_ID 2
/** @} */
/** 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)
{
const uint8_t *eop;
memset(cell_out, 0, sizeof(*cell_out));
if (payload_length > RELAY_PAYLOAD_SIZE)
return -1;
eop = payload + payload_length;
switch (command) {
case RELAY_COMMAND_EXTEND:
{
if (payload_length != 6 + TAP_ONIONSKIN_CHALLENGE_LEN + DIGEST_LEN)
return -1;
cell_out->cell_type = RELAY_COMMAND_EXTEND;
tor_addr_from_ipv4n(&cell_out->orport_ipv4.addr, get_uint32(payload));
cell_out->orport_ipv4.port = ntohs(get_uint16(payload+4));
tor_addr_make_unspec(&cell_out->orport_ipv6.addr);
if (tor_memeq(payload + 6, 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, payload + 22,
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, payload + 6,
TAP_ONIONSKIN_CHALLENGE_LEN);
}
memcpy(cell_out->node_id, payload + 6 + TAP_ONIONSKIN_CHALLENGE_LEN,
DIGEST_LEN);
break;
}
case RELAY_COMMAND_EXTEND2:
{
uint8_t n_specs = *payload, spectype, speclen;
int i;
int found_ipv4 = 0, found_ipv6 = 0, found_id = 0;
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;
++payload;
/* Parse the specifiers. We'll only take the first IPv4 and first IPv6
* address, and the node ID, and ignore everything else */
for (i = 0; i < n_specs; ++i) {
if (eop - payload < 2)
return -1;
spectype = payload[0];
speclen = payload[1];
payload += 2;
if (eop - payload < speclen)
return -1;
switch (spectype) {
case SPECTYPE_IPV4:
if (speclen != 6)
return -1;
if (!found_ipv4) {
tor_addr_from_ipv4n(&cell_out->orport_ipv4.addr,
get_uint32(payload));
cell_out->orport_ipv4.port = ntohs(get_uint16(payload+4));
found_ipv4 = 1;
}
break;
case SPECTYPE_IPV6:
if (speclen != 18)
return -1;
if (!found_ipv6) {
tor_addr_from_ipv6_bytes(&cell_out->orport_ipv6.addr,
(const char*)payload);
cell_out->orport_ipv6.port = ntohs(get_uint16(payload+16));
found_ipv6 = 1;
}
break;
case SPECTYPE_LEGACY_ID:
if (speclen != 20)
return -1;
if (found_id)
return -1;
memcpy(cell_out->node_id, payload, 20);
found_id = 1;
break;
}
payload += speclen;
}
if (!found_id || !found_ipv4)
return -1;
if (parse_create2_payload(&cell_out->create_cell,payload,eop-payload)<0)
return -1;
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)
{
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)
{
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;
}
/** 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, *eop;
if (check_extend_cell(cell_in) < 0)
return -1;
p = payload_out;
eop = payload_out + RELAY_PAYLOAD_SIZE;
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, ntohs(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 = 2;
*command_out = RELAY_COMMAND_EXTEND2;
*p++ = n; /* 2 identifiers */
*p++ = SPECTYPE_IPV4; /* First is IPV4. */
*p++ = 6; /* It's 6 bytes long. */
set_uint32(p, tor_addr_to_ipv4n(&cell_in->orport_ipv4.addr));
set_uint16(p+4, htons(cell_in->orport_ipv4.port));
p += 6;
*p++ = SPECTYPE_LEGACY_ID; /* Next is an identity digest. */
*p++ = 20; /* It's 20 bytes long */
memcpy(p, cell_in->node_id, DIGEST_LEN);
p += 20;
/* Now we can send the handshake */
set_uint16(p, htons(cell_in->create_cell.handshake_type));
set_uint16(p+2, htons(cell_in->create_cell.handshake_len));
p += 4;
if (cell_in->create_cell.handshake_len > eop - p)
return -1;
memcpy(p, cell_in->create_cell.onionskin,
cell_in->create_cell.handshake_len);
p += cell_in->create_cell.handshake_len;
*len_out = p - payload_out;
}
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;
}
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