Hallo,
ich bin ein recht erfahrener Java-Programmierer.
Ich würde gerne TOR umschreiben (habe dazu auch einen Thread im Forum Jobsuche verfasst).
Ich möchte unter anderem die .onion-Domain nicht mehr unterstützten und habe jetzt ein Problem:
Zwar verstehe ich C einigermaßen, kann hiermit aber beim besten Willen nichts anfangen!!!
Den Quelltext gibts im Anhang, hier ein Auszug:
Bitte helft mir ;(
Anhang:Anhang anzeigen src.zip
ich bin ein recht erfahrener Java-Programmierer.
Ich würde gerne TOR umschreiben (habe dazu auch einen Thread im Forum Jobsuche verfasst).
Ich möchte unter anderem die .onion-Domain nicht mehr unterstützten und habe jetzt ein Problem:
Zwar verstehe ich C einigermaßen, kann hiermit aber beim besten Willen nichts anfangen!!!
Den Quelltext gibts im Anhang, hier ein Auszug:
Java:
/* 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 "networkstatus.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"
#include "tor_queue.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.*/
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);
/* 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 oninoskin 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;
#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);
if (onionskin->handshake_type > MAX_ONION_HANDSHAKE_TYPE) {
log_warn(LD_BUG, "Handshake %d out of range! Dropping.",
onionskin->handshake_type);
return -1;
}
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.");
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);
}
/** 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) {
log_warn(LD_BUG, "Handshake %d out of range! Dropping.",
victim->handshake_type);
/* XXX leaks */
return;
}
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;
int i;
for (i=0; i<=MAX_ONION_HANDSHAKE_TYPE; i++) {
while ((victim = TOR_TAILQ_FIRST(&ol_list[i]))) {
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;
}
/** 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)
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