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tor/src/or/rendcommon.c

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/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2013, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file rendcommon.c
* \brief Rendezvous implementation: shared code between
* introducers, services, clients, and rendezvous points.
**/
#include "or.h"
#include "circuitbuild.h"
#include "config.h"
#include "rendclient.h"
#include "rendcommon.h"
#include "rendmid.h"
#include "rendservice.h"
#include "rephist.h"
#include "routerlist.h"
#include "routerparse.h"
/** Return 0 if one and two are the same service ids, else -1 or 1 */
int
rend_cmp_service_ids(const char *one, const char *two)
{
return strcasecmp(one,two);
}
/** Free the storage held by the service descriptor <b>desc</b>.
*/
void
rend_service_descriptor_free(rend_service_descriptor_t *desc)
{
if (!desc)
return;
if (desc->pk)
crypto_pk_free(desc->pk);
if (desc->intro_nodes) {
SMARTLIST_FOREACH(desc->intro_nodes, rend_intro_point_t *, intro,
rend_intro_point_free(intro););
smartlist_free(desc->intro_nodes);
}
if (desc->successful_uploads) {
SMARTLIST_FOREACH(desc->successful_uploads, char *, c, tor_free(c););
smartlist_free(desc->successful_uploads);
}
tor_free(desc);
}
/** Length of the descriptor cookie that is used for versioned hidden
* service descriptors. */
#define REND_DESC_COOKIE_LEN 16
/** Length of the replica number that is used to determine the secret ID
* part of versioned hidden service descriptors. */
#define REND_REPLICA_LEN 1
/** Compute the descriptor ID for <b>service_id</b> of length
* <b>REND_SERVICE_ID_LEN</b> and <b>secret_id_part</b> of length
* <b>DIGEST_LEN</b>, and write it to <b>descriptor_id_out</b> of length
* <b>DIGEST_LEN</b>. */
void
rend_get_descriptor_id_bytes(char *descriptor_id_out,
const char *service_id,
const char *secret_id_part)
{
crypto_digest_t *digest = crypto_digest_new();
crypto_digest_add_bytes(digest, service_id, REND_SERVICE_ID_LEN);
crypto_digest_add_bytes(digest, secret_id_part, DIGEST_LEN);
crypto_digest_get_digest(digest, descriptor_id_out, DIGEST_LEN);
crypto_digest_free(digest);
}
/** Compute the secret ID part for time_period,
* a <b>descriptor_cookie</b> of length
* <b>REND_DESC_COOKIE_LEN</b> which may also be <b>NULL</b> if no
* descriptor_cookie shall be used, and <b>replica</b>, and write it to
* <b>secret_id_part</b> of length DIGEST_LEN. */
static void
get_secret_id_part_bytes(char *secret_id_part, uint32_t time_period,
const char *descriptor_cookie, uint8_t replica)
{
crypto_digest_t *digest = crypto_digest_new();
time_period = htonl(time_period);
crypto_digest_add_bytes(digest, (char*)&time_period, sizeof(uint32_t));
if (descriptor_cookie) {
crypto_digest_add_bytes(digest, descriptor_cookie,
REND_DESC_COOKIE_LEN);
}
crypto_digest_add_bytes(digest, (const char *)&replica, REND_REPLICA_LEN);
crypto_digest_get_digest(digest, secret_id_part, DIGEST_LEN);
crypto_digest_free(digest);
}
/** Return the time period for time <b>now</b> plus a potentially
* intended <b>deviation</b> of one or more periods, based on the first byte
* of <b>service_id</b>. */
static uint32_t
get_time_period(time_t now, uint8_t deviation, const char *service_id)
{
/* The time period is the number of REND_TIME_PERIOD_V2_DESC_VALIDITY
* intervals that have passed since the epoch, offset slightly so that
* each service's time periods start and end at a fraction of that
* period based on their first byte. */
return (uint32_t)
(now + ((uint8_t) *service_id) * REND_TIME_PERIOD_V2_DESC_VALIDITY / 256)
/ REND_TIME_PERIOD_V2_DESC_VALIDITY + deviation;
}
/** Compute the time in seconds that a descriptor that is generated
* <b>now</b> for <b>service_id</b> will be valid. */
static uint32_t
get_seconds_valid(time_t now, const char *service_id)
{
uint32_t result = REND_TIME_PERIOD_V2_DESC_VALIDITY -
((uint32_t)
(now + ((uint8_t) *service_id) * REND_TIME_PERIOD_V2_DESC_VALIDITY / 256)
% REND_TIME_PERIOD_V2_DESC_VALIDITY);
return result;
}
/** Compute the binary <b>desc_id_out</b> (DIGEST_LEN bytes long) for a given
* base32-encoded <b>service_id</b> and optional unencoded
* <b>descriptor_cookie</b> of length REND_DESC_COOKIE_LEN,
* at time <b>now</b> for replica number
* <b>replica</b>. <b>desc_id</b> needs to have <b>DIGEST_LEN</b> bytes
* free. Return 0 for success, -1 otherwise. */
int
rend_compute_v2_desc_id(char *desc_id_out, const char *service_id,
const char *descriptor_cookie, time_t now,
uint8_t replica)
{
char service_id_binary[REND_SERVICE_ID_LEN];
char secret_id_part[DIGEST_LEN];
uint32_t time_period;
if (!service_id ||
strlen(service_id) != REND_SERVICE_ID_LEN_BASE32) {
log_warn(LD_REND, "Could not compute v2 descriptor ID: "
"Illegal service ID: %s",
safe_str(service_id));
return -1;
}
if (replica >= REND_NUMBER_OF_NON_CONSECUTIVE_REPLICAS) {
log_warn(LD_REND, "Could not compute v2 descriptor ID: "
"Replica number out of range: %d", replica);
return -1;
}
/* Convert service ID to binary. */
if (base32_decode(service_id_binary, REND_SERVICE_ID_LEN,
service_id, REND_SERVICE_ID_LEN_BASE32) < 0) {
log_warn(LD_REND, "Could not compute v2 descriptor ID: "
"Illegal characters in service ID: %s",
safe_str_client(service_id));
return -1;
}
/* Calculate current time-period. */
time_period = get_time_period(now, 0, service_id_binary);
/* Calculate secret-id-part = h(time-period + replica). */
get_secret_id_part_bytes(secret_id_part, time_period, descriptor_cookie,
replica);
/* Calculate descriptor ID. */
rend_get_descriptor_id_bytes(desc_id_out, service_id_binary, secret_id_part);
return 0;
}
/** Encode the introduction points in <b>desc</b> and write the result to a
* newly allocated string pointed to by <b>encoded</b>. Return 0 for
* success, -1 otherwise. */
static int
rend_encode_v2_intro_points(char **encoded, rend_service_descriptor_t *desc)
{
size_t unenc_len;
char *unenc = NULL;
size_t unenc_written = 0;
int i;
int r = -1;
/* Assemble unencrypted list of introduction points. */
unenc_len = smartlist_len(desc->intro_nodes) * 1000; /* too long, but ok. */
unenc = tor_malloc_zero(unenc_len);
for (i = 0; i < smartlist_len(desc->intro_nodes); i++) {
char id_base32[REND_INTRO_POINT_ID_LEN_BASE32 + 1];
char *onion_key = NULL;
size_t onion_key_len;
crypto_pk_t *intro_key;
char *service_key = NULL;
char *address = NULL;
size_t service_key_len;
int res;
rend_intro_point_t *intro = smartlist_get(desc->intro_nodes, i);
/* Obtain extend info with introduction point details. */
extend_info_t *info = intro->extend_info;
/* Encode introduction point ID. */
base32_encode(id_base32, sizeof(id_base32),
info->identity_digest, DIGEST_LEN);
/* Encode onion key. */
if (crypto_pk_write_public_key_to_string(info->onion_key, &onion_key,
&onion_key_len) < 0) {
log_warn(LD_REND, "Could not write onion key.");
goto done;
}
/* Encode intro key. */
intro_key = intro->intro_key;
if (!intro_key ||
crypto_pk_write_public_key_to_string(intro_key, &service_key,
&service_key_len) < 0) {
log_warn(LD_REND, "Could not write intro key.");
tor_free(onion_key);
goto done;
}
/* Assemble everything for this introduction point. */
address = tor_dup_addr(&info->addr);
res = tor_snprintf(unenc + unenc_written, unenc_len - unenc_written,
"introduction-point %s\n"
"ip-address %s\n"
"onion-port %d\n"
"onion-key\n%s"
"service-key\n%s",
id_base32,
address,
info->port,
onion_key,
service_key);
tor_free(address);
tor_free(onion_key);
tor_free(service_key);
if (res < 0) {
log_warn(LD_REND, "Not enough space for writing introduction point "
"string.");
goto done;
}
/* Update total number of written bytes for unencrypted intro points. */
unenc_written += res;
}
/* Finalize unencrypted introduction points. */
if (unenc_len < unenc_written + 2) {
log_warn(LD_REND, "Not enough space for finalizing introduction point "
"string.");
goto done;
}
unenc[unenc_written++] = '\n';
unenc[unenc_written++] = 0;
*encoded = unenc;
r = 0;
done:
if (r<0)
tor_free(unenc);
return r;
}
/** Encrypt the encoded introduction points in <b>encoded</b> using
* authorization type 'basic' with <b>client_cookies</b> and write the
* result to a newly allocated string pointed to by <b>encrypted_out</b> of
* length <b>encrypted_len_out</b>. Return 0 for success, -1 otherwise. */
static int
rend_encrypt_v2_intro_points_basic(char **encrypted_out,
size_t *encrypted_len_out,
const char *encoded,
smartlist_t *client_cookies)
{
int r = -1, i, pos, enclen, client_blocks;
size_t len, client_entries_len;
char *enc = NULL, iv[CIPHER_IV_LEN], *client_part = NULL,
session_key[CIPHER_KEY_LEN];
smartlist_t *encrypted_session_keys = NULL;
crypto_digest_t *digest;
crypto_cipher_t *cipher;
tor_assert(encoded);
tor_assert(client_cookies && smartlist_len(client_cookies) > 0);
/* Generate session key. */
if (crypto_rand(session_key, CIPHER_KEY_LEN) < 0) {
log_warn(LD_REND, "Unable to generate random session key to encrypt "
"introduction point string.");
goto done;
}
/* Determine length of encrypted introduction points including session
* keys. */
client_blocks = 1 + ((smartlist_len(client_cookies) - 1) /
REND_BASIC_AUTH_CLIENT_MULTIPLE);
client_entries_len = client_blocks * REND_BASIC_AUTH_CLIENT_MULTIPLE *
REND_BASIC_AUTH_CLIENT_ENTRY_LEN;
len = 2 + client_entries_len + CIPHER_IV_LEN + strlen(encoded);
if (client_blocks >= 256) {
log_warn(LD_REND, "Too many clients in introduction point string.");
goto done;
}
enc = tor_malloc_zero(len);
enc[0] = 0x01; /* type of authorization. */
enc[1] = (uint8_t)client_blocks;
/* Encrypt with random session key. */
enclen = crypto_cipher_encrypt_with_iv(session_key,
enc + 2 + client_entries_len,
CIPHER_IV_LEN + strlen(encoded), encoded, strlen(encoded));
if (enclen < 0) {
log_warn(LD_REND, "Could not encrypt introduction point string.");
goto done;
}
memcpy(iv, enc + 2 + client_entries_len, CIPHER_IV_LEN);
/* Encrypt session key for cookies, determine client IDs, and put both
* in a smartlist. */
encrypted_session_keys = smartlist_new();
SMARTLIST_FOREACH_BEGIN(client_cookies, const char *, cookie) {
client_part = tor_malloc_zero(REND_BASIC_AUTH_CLIENT_ENTRY_LEN);
/* Encrypt session key. */
cipher = crypto_cipher_new(cookie);
if (crypto_cipher_encrypt(cipher, client_part +
REND_BASIC_AUTH_CLIENT_ID_LEN,
session_key, CIPHER_KEY_LEN) < 0) {
log_warn(LD_REND, "Could not encrypt session key for client.");
crypto_cipher_free(cipher);
tor_free(client_part);
goto done;
}
crypto_cipher_free(cipher);
/* Determine client ID. */
digest = crypto_digest_new();
crypto_digest_add_bytes(digest, cookie, REND_DESC_COOKIE_LEN);
crypto_digest_add_bytes(digest, iv, CIPHER_IV_LEN);
crypto_digest_get_digest(digest, client_part,
REND_BASIC_AUTH_CLIENT_ID_LEN);
crypto_digest_free(digest);
/* Put both together. */
smartlist_add(encrypted_session_keys, client_part);
} SMARTLIST_FOREACH_END(cookie);
/* Add some fake client IDs and encrypted session keys. */
for (i = (smartlist_len(client_cookies) - 1) %
REND_BASIC_AUTH_CLIENT_MULTIPLE;
i < REND_BASIC_AUTH_CLIENT_MULTIPLE - 1; i++) {
client_part = tor_malloc_zero(REND_BASIC_AUTH_CLIENT_ENTRY_LEN);
if (crypto_rand(client_part, REND_BASIC_AUTH_CLIENT_ENTRY_LEN) < 0) {
log_warn(LD_REND, "Unable to generate fake client entry.");
tor_free(client_part);
goto done;
}
smartlist_add(encrypted_session_keys, client_part);
}
/* Sort smartlist and put elements in result in order. */
smartlist_sort_digests(encrypted_session_keys);
pos = 2;
SMARTLIST_FOREACH(encrypted_session_keys, const char *, entry, {
memcpy(enc + pos, entry, REND_BASIC_AUTH_CLIENT_ENTRY_LEN);
pos += REND_BASIC_AUTH_CLIENT_ENTRY_LEN;
});
*encrypted_out = enc;
*encrypted_len_out = len;
enc = NULL; /* prevent free. */
r = 0;
done:
tor_free(enc);
if (encrypted_session_keys) {
SMARTLIST_FOREACH(encrypted_session_keys, char *, d, tor_free(d););
smartlist_free(encrypted_session_keys);
}
return r;
}
/** Encrypt the encoded introduction points in <b>encoded</b> using
* authorization type 'stealth' with <b>descriptor_cookie</b> of length
* REND_DESC_COOKIE_LEN and write the result to a newly allocated string
* pointed to by <b>encrypted_out</b> of length <b>encrypted_len_out</b>.
* Return 0 for success, -1 otherwise. */
static int
rend_encrypt_v2_intro_points_stealth(char **encrypted_out,
size_t *encrypted_len_out,
const char *encoded,
const char *descriptor_cookie)
{
int r = -1, enclen;
char *enc;
tor_assert(encoded);
tor_assert(descriptor_cookie);
enc = tor_malloc_zero(1 + CIPHER_IV_LEN + strlen(encoded));
enc[0] = 0x02; /* Auth type */
enclen = crypto_cipher_encrypt_with_iv(descriptor_cookie,
enc + 1,
CIPHER_IV_LEN+strlen(encoded),
encoded, strlen(encoded));
if (enclen < 0) {
log_warn(LD_REND, "Could not encrypt introduction point string.");
goto done;
}
*encrypted_out = enc;
*encrypted_len_out = enclen;
enc = NULL; /* prevent free */
r = 0;
done:
tor_free(enc);
return r;
}
/** Attempt to parse the given <b>desc_str</b> and return true if this
* succeeds, false otherwise. */
static int
rend_desc_v2_is_parsable(rend_encoded_v2_service_descriptor_t *desc)
{
rend_service_descriptor_t *test_parsed = NULL;
char test_desc_id[DIGEST_LEN];
char *test_intro_content = NULL;
size_t test_intro_size;
size_t test_encoded_size;
const char *test_next;
int res = rend_parse_v2_service_descriptor(&test_parsed, test_desc_id,
&test_intro_content,
&test_intro_size,
&test_encoded_size,
&test_next, desc->desc_str);
rend_service_descriptor_free(test_parsed);
tor_free(test_intro_content);
return (res >= 0);
}
/** Free the storage held by an encoded v2 service descriptor. */
void
rend_encoded_v2_service_descriptor_free(
rend_encoded_v2_service_descriptor_t *desc)
{
if (!desc)
return;
tor_free(desc->desc_str);
tor_free(desc);
}
/** Free the storage held by an introduction point info. */
void
rend_intro_point_free(rend_intro_point_t *intro)
{
if (!intro)
return;
extend_info_free(intro->extend_info);
crypto_pk_free(intro->intro_key);
if (intro->accepted_intro_rsa_parts != NULL) {
replaycache_free(intro->accepted_intro_rsa_parts);
}
tor_free(intro);
}
/** Encode a set of rend_encoded_v2_service_descriptor_t's for <b>desc</b>
* at time <b>now</b> using <b>service_key</b>, depending on
* <b>auth_type</b> a <b>descriptor_cookie</b> and a list of
* <b>client_cookies</b> (which are both <b>NULL</b> if no client
* authorization is performed), and <b>period</b> (e.g. 0 for the current
* period, 1 for the next period, etc.) and add them to the existing list
* <b>descs_out</b>; return the number of seconds that the descriptors will
* be found by clients, or -1 if the encoding was not successful. */
int
rend_encode_v2_descriptors(smartlist_t *descs_out,
rend_service_descriptor_t *desc, time_t now,
uint8_t period, rend_auth_type_t auth_type,
crypto_pk_t *client_key,
smartlist_t *client_cookies)
{
char service_id[DIGEST_LEN];
uint32_t time_period;
char *ipos_base64 = NULL, *ipos = NULL, *ipos_encrypted = NULL,
*descriptor_cookie = NULL;
size_t ipos_len = 0, ipos_encrypted_len = 0;
int k;
uint32_t seconds_valid;
crypto_pk_t *service_key;
if (!desc) {
log_warn(LD_BUG, "Could not encode v2 descriptor: No desc given.");
return -1;
}
service_key = (auth_type == REND_STEALTH_AUTH) ? client_key : desc->pk;
tor_assert(service_key);
if (auth_type == REND_STEALTH_AUTH) {
descriptor_cookie = smartlist_get(client_cookies, 0);
tor_assert(descriptor_cookie);
}
/* Obtain service_id from public key. */
crypto_pk_get_digest(service_key, service_id);
/* Calculate current time-period. */
time_period = get_time_period(now, period, service_id);
/* Determine how many seconds the descriptor will be valid. */
seconds_valid = period * REND_TIME_PERIOD_V2_DESC_VALIDITY +
get_seconds_valid(now, service_id);
/* Assemble, possibly encrypt, and encode introduction points. */
if (smartlist_len(desc->intro_nodes) > 0) {
if (rend_encode_v2_intro_points(&ipos, desc) < 0) {
log_warn(LD_REND, "Encoding of introduction points did not succeed.");
return -1;
}
switch (auth_type) {
case REND_NO_AUTH:
ipos_len = strlen(ipos);
break;
case REND_BASIC_AUTH:
if (rend_encrypt_v2_intro_points_basic(&ipos_encrypted,
&ipos_encrypted_len, ipos,
client_cookies) < 0) {
log_warn(LD_REND, "Encrypting of introduction points did not "
"succeed.");
tor_free(ipos);
return -1;
}
tor_free(ipos);
ipos = ipos_encrypted;
ipos_len = ipos_encrypted_len;
break;
case REND_STEALTH_AUTH:
if (rend_encrypt_v2_intro_points_stealth(&ipos_encrypted,
&ipos_encrypted_len, ipos,
descriptor_cookie) < 0) {
log_warn(LD_REND, "Encrypting of introduction points did not "
"succeed.");
tor_free(ipos);
return -1;
}
tor_free(ipos);
ipos = ipos_encrypted;
ipos_len = ipos_encrypted_len;
break;
default:
log_warn(LD_REND|LD_BUG, "Unrecognized authorization type %d",
(int)auth_type);
tor_free(ipos);
return -1;
}
/* Base64-encode introduction points. */
ipos_base64 = tor_malloc_zero(ipos_len * 2);
if (base64_encode(ipos_base64, ipos_len * 2, ipos, ipos_len)<0) {
log_warn(LD_REND, "Could not encode introduction point string to "
"base64. length=%d", (int)ipos_len);
tor_free(ipos_base64);
tor_free(ipos);
return -1;
}
tor_free(ipos);
}
/* Encode REND_NUMBER_OF_NON_CONSECUTIVE_REPLICAS descriptors. */
for (k = 0; k < REND_NUMBER_OF_NON_CONSECUTIVE_REPLICAS; k++) {
char secret_id_part[DIGEST_LEN];
char secret_id_part_base32[REND_SECRET_ID_PART_LEN_BASE32 + 1];
char desc_id_base32[REND_DESC_ID_V2_LEN_BASE32 + 1];
char *permanent_key = NULL;
size_t permanent_key_len;
char published[ISO_TIME_LEN+1];
int i;
char protocol_versions_string[16]; /* max len: "0,1,2,3,4,5,6,7\0" */
size_t protocol_versions_written;
size_t desc_len;
char *desc_str = NULL;
int result = 0;
size_t written = 0;
char desc_digest[DIGEST_LEN];
rend_encoded_v2_service_descriptor_t *enc =
tor_malloc_zero(sizeof(rend_encoded_v2_service_descriptor_t));
/* Calculate secret-id-part = h(time-period + cookie + replica). */
get_secret_id_part_bytes(secret_id_part, time_period, descriptor_cookie,
k);
base32_encode(secret_id_part_base32, sizeof(secret_id_part_base32),
secret_id_part, DIGEST_LEN);
/* Calculate descriptor ID. */
rend_get_descriptor_id_bytes(enc->desc_id, service_id, secret_id_part);
base32_encode(desc_id_base32, sizeof(desc_id_base32),
enc->desc_id, DIGEST_LEN);
/* PEM-encode the public key */
if (crypto_pk_write_public_key_to_string(service_key, &permanent_key,
&permanent_key_len) < 0) {
log_warn(LD_BUG, "Could not write public key to string.");
rend_encoded_v2_service_descriptor_free(enc);
goto err;
}
/* Encode timestamp. */
format_iso_time(published, desc->timestamp);
/* Write protocol-versions bitmask to comma-separated value string. */
protocol_versions_written = 0;
for (i = 0; i < 8; i++) {
if (desc->protocols & 1 << i) {
tor_snprintf(protocol_versions_string + protocol_versions_written,
16 - protocol_versions_written, "%d,", i);
protocol_versions_written += 2;
}
}
if (protocol_versions_written)
protocol_versions_string[protocol_versions_written - 1] = '\0';
else
protocol_versions_string[0]= '\0';
/* Assemble complete descriptor. */
desc_len = 2000 + smartlist_len(desc->intro_nodes) * 1000; /* far too long,
but okay.*/
enc->desc_str = desc_str = tor_malloc_zero(desc_len);
result = tor_snprintf(desc_str, desc_len,
"rendezvous-service-descriptor %s\n"
"version 2\n"
"permanent-key\n%s"
"secret-id-part %s\n"
"publication-time %s\n"
"protocol-versions %s\n",
desc_id_base32,
permanent_key,
secret_id_part_base32,
published,
protocol_versions_string);
tor_free(permanent_key);
if (result < 0) {
log_warn(LD_BUG, "Descriptor ran out of room.");
rend_encoded_v2_service_descriptor_free(enc);
goto err;
}
written = result;
/* Add introduction points. */
if (ipos_base64) {
result = tor_snprintf(desc_str + written, desc_len - written,
"introduction-points\n"
"-----BEGIN MESSAGE-----\n%s"
"-----END MESSAGE-----\n",
ipos_base64);
if (result < 0) {
log_warn(LD_BUG, "could not write introduction points.");
rend_encoded_v2_service_descriptor_free(enc);
goto err;
}
written += result;
}
/* Add signature. */
strlcpy(desc_str + written, "signature\n", desc_len - written);
written += strlen(desc_str + written);
if (crypto_digest(desc_digest, desc_str, written) < 0) {
log_warn(LD_BUG, "could not create digest.");
rend_encoded_v2_service_descriptor_free(enc);
goto err;
}
if (router_append_dirobj_signature(desc_str + written,
desc_len - written,
desc_digest, DIGEST_LEN,
service_key) < 0) {
log_warn(LD_BUG, "Couldn't sign desc.");
rend_encoded_v2_service_descriptor_free(enc);
goto err;
}
written += strlen(desc_str+written);
if (written+2 > desc_len) {
log_warn(LD_BUG, "Could not finish desc.");
rend_encoded_v2_service_descriptor_free(enc);
goto err;
}
desc_str[written++] = '\n';
desc_str[written++] = 0;
/* Check if we can parse our own descriptor. */
if (!rend_desc_v2_is_parsable(enc)) {
log_warn(LD_BUG, "Could not parse my own descriptor: %s", desc_str);
rend_encoded_v2_service_descriptor_free(enc);
goto err;
}
smartlist_add(descs_out, enc);
}
log_info(LD_REND, "Successfully encoded a v2 descriptor and "
"confirmed that it is parsable.");
goto done;
err:
SMARTLIST_FOREACH(descs_out, rend_encoded_v2_service_descriptor_t *, d,
rend_encoded_v2_service_descriptor_free(d););
smartlist_clear(descs_out);
seconds_valid = -1;
done:
tor_free(ipos_base64);
return seconds_valid;
}
/** Sets <b>out</b> to the first 10 bytes of the digest of <b>pk</b>,
* base32 encoded. NUL-terminates out. (We use this string to
* identify services in directory requests and .onion URLs.)
*/
int
rend_get_service_id(crypto_pk_t *pk, char *out)
{
char buf[DIGEST_LEN];
tor_assert(pk);
if (crypto_pk_get_digest(pk, buf) < 0)
return -1;
base32_encode(out, REND_SERVICE_ID_LEN_BASE32+1, buf, REND_SERVICE_ID_LEN);
return 0;
}
/* ==== Rendezvous service descriptor cache. */
/** How old do we let hidden service descriptors get before discarding
* them as too old? */
#define REND_CACHE_MAX_AGE (2*24*60*60)
/** How wrong do we assume our clock may be when checking whether hidden
* services are too old or too new? */
#define REND_CACHE_MAX_SKEW (24*60*60)
/** Map from service id (as generated by rend_get_service_id) to
* rend_cache_entry_t. */
static strmap_t *rend_cache = NULL;
/** Map from descriptor id to rend_cache_entry_t; only for hidden service
* directories. */
static digestmap_t *rend_cache_v2_dir = NULL;
/** Initializes the service descriptor cache.
*/
void
rend_cache_init(void)
{
rend_cache = strmap_new();
rend_cache_v2_dir = digestmap_new();
}
/** Helper: free storage held by a single service descriptor cache entry. */
static void
rend_cache_entry_free(rend_cache_entry_t *e)
{
if (!e)
return;
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
tor_free(e);
}
/** Helper: deallocate a rend_cache_entry_t. (Used with strmap_free(), which
* requires a function pointer whose argument is void*). */
static void
rend_cache_entry_free_(void *p)
{
rend_cache_entry_free(p);
}
/** Free all storage held by the service descriptor cache. */
void
rend_cache_free_all(void)
{
strmap_free(rend_cache, rend_cache_entry_free_);
digestmap_free(rend_cache_v2_dir, rend_cache_entry_free_);
rend_cache = NULL;
rend_cache_v2_dir = NULL;
}
/** Removes all old entries from the service descriptor cache.
*/
void
rend_cache_clean(time_t now)
{
strmap_iter_t *iter;
const char *key;
void *val;
rend_cache_entry_t *ent;
time_t cutoff = now - REND_CACHE_MAX_AGE - REND_CACHE_MAX_SKEW;
for (iter = strmap_iter_init(rend_cache); !strmap_iter_done(iter); ) {
strmap_iter_get(iter, &key, &val);
ent = (rend_cache_entry_t*)val;
if (ent->parsed->timestamp < cutoff) {
iter = strmap_iter_next_rmv(rend_cache, iter);
rend_cache_entry_free(ent);
} else {
iter = strmap_iter_next(rend_cache, iter);
}
}
}
/** Remove ALL entries from the rendezvous service descriptor cache.
*/
void
rend_cache_purge(void)
{
if (rend_cache) {
log_info(LD_REND, "Purging HS descriptor cache");
strmap_free(rend_cache, rend_cache_entry_free_);
}
rend_cache = strmap_new();
}
/** Remove all old v2 descriptors and those for which this hidden service
* directory is not responsible for any more. */
void
rend_cache_clean_v2_descs_as_dir(time_t now)
{
digestmap_iter_t *iter;
time_t cutoff = now - REND_CACHE_MAX_AGE - REND_CACHE_MAX_SKEW;
for (iter = digestmap_iter_init(rend_cache_v2_dir);
!digestmap_iter_done(iter); ) {
const char *key;
void *val;
rend_cache_entry_t *ent;
digestmap_iter_get(iter, &key, &val);
ent = val;
if (ent->parsed->timestamp < cutoff ||
!hid_serv_responsible_for_desc_id(key)) {
char key_base32[REND_DESC_ID_V2_LEN_BASE32 + 1];
base32_encode(key_base32, sizeof(key_base32), key, DIGEST_LEN);
log_info(LD_REND, "Removing descriptor with ID '%s' from cache",
safe_str_client(key_base32));
iter = digestmap_iter_next_rmv(rend_cache_v2_dir, iter);
rend_cache_entry_free(ent);
} else {
iter = digestmap_iter_next(rend_cache_v2_dir, iter);
}
}
}
/** Determines whether <b>a</b> is in the interval of <b>b</b> (excluded) and
* <b>c</b> (included) in a circular digest ring; returns 1 if this is the
* case, and 0 otherwise.
*/
int
rend_id_is_in_interval(const char *a, const char *b, const char *c)
{
int a_b, b_c, c_a;
tor_assert(a);
tor_assert(b);
tor_assert(c);
/* There are five cases in which a is outside the interval ]b,c]: */
a_b = tor_memcmp(a,b,DIGEST_LEN);
if (a_b == 0)
return 0; /* 1. a == b (b is excluded) */
b_c = tor_memcmp(b,c,DIGEST_LEN);
if (b_c == 0)
return 0; /* 2. b == c (interval is empty) */
else if (a_b <= 0 && b_c < 0)
return 0; /* 3. a b c */
c_a = tor_memcmp(c,a,DIGEST_LEN);
if (c_a < 0 && a_b <= 0)
return 0; /* 4. c a b */
else if (b_c < 0 && c_a < 0)
return 0; /* 5. b c a */
/* In the other cases (a c b; b a c; c b a), a is inside the interval. */
return 1;
}
/** Return true iff <b>query</b> is a syntactically valid service ID (as
* generated by rend_get_service_id). */
int
rend_valid_service_id(const char *query)
{
if (strlen(query) != REND_SERVICE_ID_LEN_BASE32)
return 0;
if (strspn(query, BASE32_CHARS) != REND_SERVICE_ID_LEN_BASE32)
return 0;
return 1;
}
/** If we have a cached rend_cache_entry_t for the service ID <b>query</b>
* with <b>version</b>, set *<b>e</b> to that entry and return 1.
* Else return 0. If <b>version</b> is nonnegative, only return an entry
* in that descriptor format version. Otherwise (if <b>version</b> is
* negative), return the most recent format we have.
*/
int
rend_cache_lookup_entry(const char *query, int version, rend_cache_entry_t **e)
{
char key[REND_SERVICE_ID_LEN_BASE32+2]; /* <version><query>\0 */
tor_assert(rend_cache);
if (!rend_valid_service_id(query))
return -1;
*e = NULL;
if (version != 0) {
tor_snprintf(key, sizeof(key), "2%s", query);
*e = strmap_get_lc(rend_cache, key);
}
if (!*e && version != 2) {
tor_snprintf(key, sizeof(key), "0%s", query);
*e = strmap_get_lc(rend_cache, key);
}
if (!*e)
return 0;
tor_assert((*e)->parsed && (*e)->parsed->intro_nodes);
/* XXX023 hack for now, to return "not found" if there are no intro
* points remaining. See bug 997. */
if (! rend_client_any_intro_points_usable(*e))
return 0;
return 1;
}
/** Lookup the v2 service descriptor with base32-encoded <b>desc_id</b> and
* copy the pointer to it to *<b>desc</b>. Return 1 on success, 0 on
* well-formed-but-not-found, and -1 on failure.
*/
int
rend_cache_lookup_v2_desc_as_dir(const char *desc_id, const char **desc)
{
rend_cache_entry_t *e;
char desc_id_digest[DIGEST_LEN];
tor_assert(rend_cache_v2_dir);
if (base32_decode(desc_id_digest, DIGEST_LEN,
desc_id, REND_DESC_ID_V2_LEN_BASE32) < 0) {
log_fn(LOG_PROTOCOL_WARN, LD_REND,
"Rejecting v2 rendezvous descriptor request -- descriptor ID "
"contains illegal characters: %s",
safe_str(desc_id));
return -1;
}
/* Lookup descriptor and return. */
e = digestmap_get(rend_cache_v2_dir, desc_id_digest);
if (e) {
*desc = e->desc;
return 1;
}
return 0;
}
/* Do not allow more than this many introduction points in a hidden service
* descriptor */
#define MAX_INTRO_POINTS 10
/** Parse the v2 service descriptor(s) in <b>desc</b> and store it/them to the
* local rend cache. Don't attempt to decrypt the included list of introduction
* points (as we don't have a descriptor cookie for it).
*
* If we have a newer descriptor with the same ID, ignore this one.
* If we have an older descriptor with the same ID, replace it.
*
* Return an appropriate rend_cache_store_status_t.
*/
rend_cache_store_status_t
rend_cache_store_v2_desc_as_dir(const char *desc)
{
rend_service_descriptor_t *parsed;
char desc_id[DIGEST_LEN];
char *intro_content;
size_t intro_size;
size_t encoded_size;
char desc_id_base32[REND_DESC_ID_V2_LEN_BASE32 + 1];
int number_parsed = 0, number_stored = 0;
const char *current_desc = desc;
const char *next_desc;
rend_cache_entry_t *e;
time_t now = time(NULL);
tor_assert(rend_cache_v2_dir);
tor_assert(desc);
if (!hid_serv_acting_as_directory()) {
/* Cannot store descs, because we are (currently) not acting as
* hidden service directory. */
log_info(LD_REND, "Cannot store descs: Not acting as hs dir");
return RCS_NOTDIR;
}
while (rend_parse_v2_service_descriptor(&parsed, desc_id, &intro_content,
&intro_size, &encoded_size,
&next_desc, current_desc) >= 0) {
number_parsed++;
/* We don't care about the introduction points. */
tor_free(intro_content);
/* For pretty log statements. */
base32_encode(desc_id_base32, sizeof(desc_id_base32),
desc_id, DIGEST_LEN);
/* Is desc ID in the range that we are (directly or indirectly) responsible
* for? */
if (!hid_serv_responsible_for_desc_id(desc_id)) {
log_info(LD_REND, "Service descriptor with desc ID %s is not in "
"interval that we are responsible for.",
safe_str_client(desc_id_base32));
goto skip;
}
/* Is descriptor too old? */
if (parsed->timestamp < now - REND_CACHE_MAX_AGE-REND_CACHE_MAX_SKEW) {
log_info(LD_REND, "Service descriptor with desc ID %s is too old.",
safe_str(desc_id_base32));
goto skip;
}
/* Is descriptor too far in the future? */
if (parsed->timestamp > now + REND_CACHE_MAX_SKEW) {
log_info(LD_REND, "Service descriptor with desc ID %s is too far in the "
"future.",
safe_str(desc_id_base32));
goto skip;
}
/* Do we already have a newer descriptor? */
e = digestmap_get(rend_cache_v2_dir, desc_id);
if (e && e->parsed->timestamp > parsed->timestamp) {
log_info(LD_REND, "We already have a newer service descriptor with the "
"same desc ID %s and version.",
safe_str(desc_id_base32));
goto skip;
}
/* Do we already have this descriptor? */
if (e && !strcmp(desc, e->desc)) {
log_info(LD_REND, "We already have this service descriptor with desc "
"ID %s.", safe_str(desc_id_base32));
e->received = time(NULL);
goto skip;
}
/* Store received descriptor. */
if (!e) {
e = tor_malloc_zero(sizeof(rend_cache_entry_t));
digestmap_set(rend_cache_v2_dir, desc_id, e);
} else {
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
}
e->received = time(NULL);
e->parsed = parsed;
e->desc = tor_strndup(current_desc, encoded_size);
e->len = encoded_size;
log_info(LD_REND, "Successfully stored service descriptor with desc ID "
"'%s' and len %d.",
safe_str(desc_id_base32), (int)encoded_size);
number_stored++;
goto advance;
skip:
rend_service_descriptor_free(parsed);
advance:
/* advance to next descriptor, if available. */
current_desc = next_desc;
/* check if there is a next descriptor. */
if (!current_desc ||
strcmpstart(current_desc, "rendezvous-service-descriptor "))
break;
}
if (!number_parsed) {
log_info(LD_REND, "Could not parse any descriptor.");
return RCS_BADDESC;
}
log_info(LD_REND, "Parsed %d and added %d descriptor%s.",
number_parsed, number_stored, number_stored != 1 ? "s" : "");
return RCS_OKAY;
}
/** Parse the v2 service descriptor in <b>desc</b>, decrypt the included list
* of introduction points with <b>descriptor_cookie</b> (which may also be
* <b>NULL</b> if decryption is not necessary), and store the descriptor to
* the local cache under its version and service id.
*
* If we have a newer v2 descriptor with the same ID, ignore this one.
* If we have an older descriptor with the same ID, replace it.
* If the descriptor's service ID does not match
* <b>rend_query</b>-\>onion_address, reject it.
*
* Return an appropriate rend_cache_store_status_t.
*/
rend_cache_store_status_t
rend_cache_store_v2_desc_as_client(const char *desc,
const rend_data_t *rend_query)
{
/*XXXX this seems to have a bit of duplicate code with
* rend_cache_store_v2_desc_as_dir(). Fix that. */
/* Though having similar elements, both functions were separated on
* purpose:
* - dirs don't care about encoded/encrypted introduction points, clients
* do.
* - dirs store descriptors in a separate cache by descriptor ID, whereas
* clients store them by service ID; both caches are different data
* structures and have different access methods.
* - dirs store a descriptor only if they are responsible for its ID,
* clients do so in every way (because they have requested it before).
* - dirs can process multiple concatenated descriptors which is required
* for replication, whereas clients only accept a single descriptor.
* Thus, combining both methods would result in a lot of if statements
* which probably would not improve, but worsen code readability. -KL */
rend_service_descriptor_t *parsed = NULL;
char desc_id[DIGEST_LEN];
char *intro_content = NULL;
size_t intro_size;
size_t encoded_size;
const char *next_desc;
time_t now = time(NULL);
char key[REND_SERVICE_ID_LEN_BASE32+2];
char service_id[REND_SERVICE_ID_LEN_BASE32+1];
rend_cache_entry_t *e;
rend_cache_store_status_t retval = RCS_BADDESC;
tor_assert(rend_cache);
tor_assert(desc);
/* Parse the descriptor. */
if (rend_parse_v2_service_descriptor(&parsed, desc_id, &intro_content,
&intro_size, &encoded_size,
&next_desc, desc) < 0) {
log_warn(LD_REND, "Could not parse descriptor.");
goto err;
}
/* Compute service ID from public key. */
if (rend_get_service_id(parsed->pk, service_id)<0) {
log_warn(LD_REND, "Couldn't compute service ID.");
goto err;
}
if (strcmp(rend_query->onion_address, service_id)) {
log_warn(LD_REND, "Received service descriptor for service ID %s; "
"expected descriptor for service ID %s.",
service_id, safe_str(rend_query->onion_address));
goto err;
}
/* Decode/decrypt introduction points. */
if (intro_content && intro_size > 0) {
int n_intro_points;
if (rend_query->auth_type != REND_NO_AUTH &&
!tor_mem_is_zero(rend_query->descriptor_cookie,
sizeof(rend_query->descriptor_cookie))) {
char *ipos_decrypted = NULL;
size_t ipos_decrypted_size;
if (rend_decrypt_introduction_points(&ipos_decrypted,
&ipos_decrypted_size,
rend_query->descriptor_cookie,
intro_content,
intro_size) < 0) {
log_warn(LD_REND, "Failed to decrypt introduction points. We are "
"probably unable to parse the encoded introduction points.");
} else {
/* Replace encrypted with decrypted introduction points. */
log_info(LD_REND, "Successfully decrypted introduction points.");
tor_free(intro_content);
intro_content = ipos_decrypted;
intro_size = ipos_decrypted_size;
}
}
n_intro_points = rend_parse_introduction_points(parsed, intro_content,
intro_size);
if (n_intro_points <= 0) {
log_warn(LD_REND, "Failed to parse introduction points. Either the "
"service has published a corrupt descriptor, or you have "
"provided invalid authorization data, or (maybe!) the "
"server is deliberately serving broken data in an attempt "
"to crash you with bug 21018.");
goto err;
} else if (n_intro_points > MAX_INTRO_POINTS) {
log_warn(LD_REND, "Found too many introduction points on a hidden "
"service descriptor for %s. This is probably a (misguided) "
"attempt to improve reliability, but it could also be an "
"attempt to do a guard enumeration attack. Rejecting.",
safe_str_client(rend_query->onion_address));
goto err;
}
} else {
log_info(LD_REND, "Descriptor does not contain any introduction points.");
parsed->intro_nodes = smartlist_new();
}
/* We don't need the encoded/encrypted introduction points any longer. */
tor_free(intro_content);
/* Is descriptor too old? */
if (parsed->timestamp < now - REND_CACHE_MAX_AGE-REND_CACHE_MAX_SKEW) {
log_warn(LD_REND, "Service descriptor with service ID %s is too old.",
safe_str_client(service_id));
goto err;
}
/* Is descriptor too far in the future? */
if (parsed->timestamp > now + REND_CACHE_MAX_SKEW) {
log_warn(LD_REND, "Service descriptor with service ID %s is too far in "
"the future.", safe_str_client(service_id));
goto err;
}
/* Do we already have a newer descriptor? */
tor_snprintf(key, sizeof(key), "2%s", service_id);
e = (rend_cache_entry_t*) strmap_get_lc(rend_cache, key);
if (e && e->parsed->timestamp > parsed->timestamp) {
log_info(LD_REND, "We already have a newer service descriptor for "
"service ID %s with the same desc ID and version.",
safe_str_client(service_id));
goto okay;
}
/* Do we already have this descriptor? */
if (e && !strcmp(desc, e->desc)) {
log_info(LD_REND,"We already have this service descriptor %s.",
safe_str_client(service_id));
e->received = time(NULL);
goto okay;
}
if (!e) {
e = tor_malloc_zero(sizeof(rend_cache_entry_t));
strmap_set_lc(rend_cache, key, e);
} else {
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
}
e->received = time(NULL);
e->parsed = parsed;
e->desc = tor_malloc_zero(encoded_size + 1);
strlcpy(e->desc, desc, encoded_size + 1);
e->len = encoded_size;
log_debug(LD_REND,"Successfully stored rend desc '%s', len %d.",
safe_str_client(service_id), (int)encoded_size);
return RCS_OKAY;
okay:
retval = RCS_OKAY;
err:
rend_service_descriptor_free(parsed);
tor_free(intro_content);
return retval;
}
/** Called when we get a rendezvous-related relay cell on circuit
* <b>circ</b>. Dispatch on rendezvous relay command. */
void
rend_process_relay_cell(circuit_t *circ, const crypt_path_t *layer_hint,
int command, size_t length,
const uint8_t *payload)
{
or_circuit_t *or_circ = NULL;
origin_circuit_t *origin_circ = NULL;
int r = -2;
if (CIRCUIT_IS_ORIGIN(circ)) {
origin_circ = TO_ORIGIN_CIRCUIT(circ);
if (!layer_hint || layer_hint != origin_circ->cpath->prev) {
log_fn(LOG_PROTOCOL_WARN, LD_APP,
"Relay cell (rend purpose %d) from wrong hop on origin circ",
command);
origin_circ = NULL;
}
} else {
or_circ = TO_OR_CIRCUIT(circ);
}
switch (command) {
case RELAY_COMMAND_ESTABLISH_INTRO:
if (or_circ)
r = rend_mid_establish_intro(or_circ,payload,length);
break;
case RELAY_COMMAND_ESTABLISH_RENDEZVOUS:
if (or_circ)
r = rend_mid_establish_rendezvous(or_circ,payload,length);
break;
case RELAY_COMMAND_INTRODUCE1:
if (or_circ)
r = rend_mid_introduce(or_circ,payload,length);
break;
case RELAY_COMMAND_INTRODUCE2:
if (origin_circ)
r = rend_service_introduce(origin_circ,payload,length);
break;
case RELAY_COMMAND_INTRODUCE_ACK:
if (origin_circ)
r = rend_client_introduction_acked(origin_circ,payload,length);
break;
case RELAY_COMMAND_RENDEZVOUS1:
if (or_circ)
r = rend_mid_rendezvous(or_circ,payload,length);
break;
case RELAY_COMMAND_RENDEZVOUS2:
if (origin_circ)
r = rend_client_receive_rendezvous(origin_circ,payload,length);
break;
case RELAY_COMMAND_INTRO_ESTABLISHED:
if (origin_circ)
r = rend_service_intro_established(origin_circ,payload,length);
break;
case RELAY_COMMAND_RENDEZVOUS_ESTABLISHED:
if (origin_circ)
r = rend_client_rendezvous_acked(origin_circ,payload,length);
break;
default:
tor_fragile_assert();
}
if (r == -2)
log_info(LD_PROTOCOL, "Dropping cell (type %d) for wrong circuit type.",
command);
}
/** Allocate and return a new rend_data_t with the same
* contents as <b>query</b>. */
rend_data_t *
rend_data_dup(const rend_data_t *data)
{
tor_assert(data);
return tor_memdup(data, sizeof(rend_data_t));
}
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