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/* Copyright (c) 2015-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file rendcache.c
* \brief Hidden service descriptor cache.
**/
#define RENDCACHE_PRIVATE
#include "rendcache.h"
#include "config.h"
#include "rephist.h"
#include "routerlist.h"
#include "routerparse.h"
#include "rendcommon.h"
/** Map from service id (as generated by rend_get_service_id) to
* rend_cache_entry_t. */
STATIC strmap_t *rend_cache = NULL;
/** Map from service id to rend_cache_entry_t; only for hidden services. */
static strmap_t *rend_cache_local_service = NULL;
/** Map from descriptor id to rend_cache_entry_t; only for hidden service
* directories. */
STATIC digestmap_t *rend_cache_v2_dir = NULL;
/** (Client side only) Map from service id to rend_cache_failure_t. This
* cache is used to track intro point(IP) failures so we know when to keep
* or discard a new descriptor we just fetched. Here is a description of the
* cache behavior.
*
* Everytime tor discards an IP (ex: receives a NACK), we add an entry to
* this cache noting the identity digest of the IP and it's failure type for
* the service ID. The reason we indexed this cache by service ID is to
* differentiate errors that can occur only for a specific service like a
* NACK for instance. It applies for one but maybe not for the others.
*
* Once a service descriptor is fetched and considered valid, each IP is
* looked up in this cache and if present, it is discarded from the fetched
* descriptor. At the end, all IP(s) in the cache, for a specific service
* ID, that were NOT present in the descriptor are removed from this cache.
* Which means that if at least one IP was not in this cache, thus usuable,
* it's considered a new descriptor so we keep it. Else, if all IPs were in
* this cache, we discard the descriptor as it's considered unusable.
*
* Once a descriptor is removed from the rend cache or expires, the entry
* in this cache is also removed for the service ID.
*
* This scheme allows us to not rely on the descriptor's timestamp (which
* is rounded down to the hour) to know if we have a newer descriptor. We
* only rely on the usability of intro points from an internal state. */
STATIC strmap_t *rend_cache_failure = NULL;
/* DOCDOC */
STATIC size_t rend_cache_total_allocation = 0;
/** Initializes the service descriptor cache.
*/
void
rend_cache_init(void)
{
rend_cache = strmap_new();
rend_cache_v2_dir = digestmap_new();
rend_cache_local_service = strmap_new();
rend_cache_failure = strmap_new();
}
/** Return the approximate number of bytes needed to hold <b>e</b>. */
STATIC size_t
rend_cache_entry_allocation(const rend_cache_entry_t *e)
{
if (!e)
return 0;
/* This doesn't count intro_nodes or key size */
return sizeof(*e) + e->len + sizeof(*e->parsed);
}
/* DOCDOC */
size_t
rend_cache_get_total_allocation(void)
{
return rend_cache_total_allocation;
}
/** Decrement the total bytes attributed to the rendezvous cache by n. */
void
rend_cache_decrement_allocation(size_t n)
{
static int have_underflowed = 0;
if (rend_cache_total_allocation >= n) {
rend_cache_total_allocation -= n;
} else {
rend_cache_total_allocation = 0;
if (! have_underflowed) {
have_underflowed = 1;
log_warn(LD_BUG, "Underflow in rend_cache_decrement_allocation");
}
}
}
/** Increase the total bytes attributed to the rendezvous cache by n. */
void
rend_cache_increment_allocation(size_t n)
{
static int have_overflowed = 0;
if (rend_cache_total_allocation <= SIZE_MAX - n) {
rend_cache_total_allocation += n;
} else {
rend_cache_total_allocation = SIZE_MAX;
if (! have_overflowed) {
have_overflowed = 1;
log_warn(LD_BUG, "Overflow in rend_cache_increment_allocation");
}
}
}
/** Helper: free a rend cache failure intro object. */
STATIC void
rend_cache_failure_intro_entry_free_(rend_cache_failure_intro_t *entry)
{
if (entry == NULL) {
return;
}
tor_free(entry);
}
static void
rend_cache_failure_intro_entry_free_void(void *entry)
{
rend_cache_failure_intro_entry_free_(entry);
}
/** Allocate a rend cache failure intro object and return it. <b>failure</b>
* is set into the object. This function can not fail. */
STATIC rend_cache_failure_intro_t *
rend_cache_failure_intro_entry_new(rend_intro_point_failure_t failure)
{
rend_cache_failure_intro_t *entry = tor_malloc(sizeof(*entry));
entry->failure_type = failure;
entry->created_ts = time(NULL);
return entry;
}
/** Helper: free a rend cache failure object. */
STATIC void
rend_cache_failure_entry_free_(rend_cache_failure_t *entry)
{
if (entry == NULL) {
return;
}
/* Free and remove every intro failure object. */
digestmap_free(entry->intro_failures,
rend_cache_failure_intro_entry_free_void);
tor_free(entry);
}
/** Helper: deallocate a rend_cache_failure_t. (Used with strmap_free(),
* which requires a function pointer whose argument is void*). */
STATIC void
rend_cache_failure_entry_free_void(void *entry)
{
rend_cache_failure_entry_free_(entry);
}
/** Allocate a rend cache failure object and return it. This function can
* not fail. */
STATIC rend_cache_failure_t *
rend_cache_failure_entry_new(void)
{
rend_cache_failure_t *entry = tor_malloc(sizeof(*entry));
entry->intro_failures = digestmap_new();
return entry;
}
/** Remove failure cache entry for the service ID in the given descriptor
* <b>desc</b>. */
STATIC void
rend_cache_failure_remove(rend_service_descriptor_t *desc)
{
char service_id[REND_SERVICE_ID_LEN_BASE32 + 1];
rend_cache_failure_t *entry;
if (desc == NULL) {
return;
}
if (rend_get_service_id(desc->pk, service_id) < 0) {
return;
}
entry = strmap_get_lc(rend_cache_failure, service_id);
if (entry != NULL) {
strmap_remove_lc(rend_cache_failure, service_id);
rend_cache_failure_entry_free(entry);
}
}
/** 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_cache_decrement_allocation(rend_cache_entry_allocation(e));
/* We are about to remove a descriptor from the cache so remove the entry
* in the failure cache. */
rend_cache_failure_remove(e->parsed);
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(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_void);
digestmap_free(rend_cache_v2_dir, rend_cache_entry_free_void);
strmap_free(rend_cache_local_service, rend_cache_entry_free_void);
strmap_free(rend_cache_failure, rend_cache_failure_entry_free_void);
rend_cache = NULL;
rend_cache_v2_dir = NULL;
rend_cache_local_service = NULL;
rend_cache_failure = NULL;
rend_cache_total_allocation = 0;
}
/** Remove all entries that re REND_CACHE_FAILURE_MAX_AGE old. This is
* called every second.
*
* We have to clean these regurlarly else if for whatever reasons an hidden
* service goes offline and a client tries to connect to it during that
* time, a failure entry is created and the client will be unable to connect
* for a while even though the service has return online. */
void
rend_cache_failure_clean(time_t now)
{
time_t cutoff = now - REND_CACHE_FAILURE_MAX_AGE;
STRMAP_FOREACH_MODIFY(rend_cache_failure, key,
rend_cache_failure_t *, ent) {
/* Free and remove every intro failure object that match the cutoff. */
DIGESTMAP_FOREACH_MODIFY(ent->intro_failures, ip_key,
rend_cache_failure_intro_t *, ip_ent) {
if (ip_ent->created_ts < cutoff) {
rend_cache_failure_intro_entry_free(ip_ent);
MAP_DEL_CURRENT(ip_key);
}
} DIGESTMAP_FOREACH_END;
/* If the entry is now empty of intro point failures, remove it. */
if (digestmap_isempty(ent->intro_failures)) {
rend_cache_failure_entry_free(ent);
MAP_DEL_CURRENT(key);
}
} STRMAP_FOREACH_END;
}
/** Removes all old entries from the client or service descriptor cache.
*/
void
rend_cache_clean(time_t now, rend_cache_type_t cache_type)
{
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;
strmap_t *cache = NULL;
if (cache_type == REND_CACHE_TYPE_CLIENT) {
cache = rend_cache;
} else if (cache_type == REND_CACHE_TYPE_SERVICE) {
cache = rend_cache_local_service;
}
tor_assert(cache);
for (iter = strmap_iter_init(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(cache, iter);
rend_cache_entry_free(ent);
} else {
iter = strmap_iter_next(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 v2 descriptor cache");
strmap_free(rend_cache, rend_cache_entry_free_void);
}
rend_cache = strmap_new();
}
/** Remove ALL entries from the failure cache. This is also called when a
* NEWNYM signal is received. */
void
rend_cache_failure_purge(void)
{
if (rend_cache_failure) {
log_info(LD_REND, "Purging HS v2 failure cache");
strmap_free(rend_cache_failure, rend_cache_failure_entry_free_void);
}
rend_cache_failure = strmap_new();
}
/** Lookup the rend failure cache using a relay identity digest in
* <b>identity</b> which has DIGEST_LEN bytes and service ID <b>service_id</b>
* which is a null-terminated string. If found, the intro failure is set in
* <b>intro_entry</b> else it stays untouched. Return 1 iff found else 0. */
STATIC int
cache_failure_intro_lookup(const uint8_t *identity, const char *service_id,
rend_cache_failure_intro_t **intro_entry)
{
rend_cache_failure_t *elem;
rend_cache_failure_intro_t *intro_elem;
tor_assert(rend_cache_failure);
if (intro_entry) {
*intro_entry = NULL;
}
/* Lookup descriptor and return it. */
elem = strmap_get_lc(rend_cache_failure, service_id);
if (elem == NULL) {
goto not_found;
}
intro_elem = digestmap_get(elem->intro_failures, (char *) identity);
if (intro_elem == NULL) {
goto not_found;
}
if (intro_entry) {
*intro_entry = intro_elem;
}
return 1;
not_found:
return 0;
}
/** Allocate a new cache failure intro object and copy the content from
* <b>entry</b> to this newly allocated object. Return it. */
static rend_cache_failure_intro_t *
cache_failure_intro_dup(const rend_cache_failure_intro_t *entry)
{
rend_cache_failure_intro_t *ent_dup =
rend_cache_failure_intro_entry_new(entry->failure_type);
ent_dup->created_ts = entry->created_ts;
return ent_dup;
}
/** Add an intro point failure to the failure cache using the relay
* <b>identity</b> and service ID <b>service_id</b>. Record the
* <b>failure</b> in that object. */
STATIC void
cache_failure_intro_add(const uint8_t *identity, const char *service_id,
rend_intro_point_failure_t failure)
{
rend_cache_failure_t *fail_entry;
rend_cache_failure_intro_t *entry, *old_entry;
/* Make sure we have a failure object for this service ID and if not,
* create it with this new intro failure entry. */
fail_entry = strmap_get_lc(rend_cache_failure, service_id);
if (fail_entry == NULL) {
fail_entry = rend_cache_failure_entry_new();
/* Add failure entry to global rend failure cache. */
strmap_set_lc(rend_cache_failure, service_id, fail_entry);
}
entry = rend_cache_failure_intro_entry_new(failure);
old_entry = digestmap_set(fail_entry->intro_failures,
(char *) identity, entry);
/* This _should_ be NULL, but in case it isn't, free it. */
rend_cache_failure_intro_entry_free(old_entry);
}
/** Using a parsed descriptor <b>desc</b>, check if the introduction points
* are present in the failure cache and if so they are removed from the
* descriptor and kept into the failure cache. Then, each intro points that
* are NOT in the descriptor but in the failure cache for the given
* <b>service_id</b> are removed from the failure cache. */
STATIC void
validate_intro_point_failure(const rend_service_descriptor_t *desc,
const char *service_id)
{
rend_cache_failure_t *new_entry, *cur_entry;
/* New entry for the service ID that will be replacing the one in the
* failure cache since we have a new descriptor. In the case where all
* intro points are removed, we are assured that the new entry is the same
* as the current one. */
new_entry = tor_malloc(sizeof(*new_entry));
new_entry->intro_failures = digestmap_new();
tor_assert(desc);
SMARTLIST_FOREACH_BEGIN(desc->intro_nodes, rend_intro_point_t *, intro) {
int found;
rend_cache_failure_intro_t *entry;
const uint8_t *identity =
(uint8_t *) intro->extend_info->identity_digest;
found = cache_failure_intro_lookup(identity, service_id, &entry);
if (found) {
/* Dup here since it will be freed at the end when removing the
* original entry in the cache. */
rend_cache_failure_intro_t *ent_dup = cache_failure_intro_dup(entry);
/* This intro point is in our cache, discard it from the descriptor
* because chances are that it's unusable. */
SMARTLIST_DEL_CURRENT(desc->intro_nodes, intro);
/* Keep it for our new entry. */
digestmap_set(new_entry->intro_failures, (char *) identity, ent_dup);
/* Only free it when we're done looking at it. */
rend_intro_point_free(intro);
continue;
}
} SMARTLIST_FOREACH_END(intro);
/* Swap the failure entry in the cache and free the current one. */
cur_entry = strmap_get_lc(rend_cache_failure, service_id);
if (cur_entry != NULL) {
rend_cache_failure_entry_free(cur_entry);
}
strmap_set_lc(rend_cache_failure, service_id, new_entry);
}
/** Note down an intro failure in the rend failure cache using the type of
* failure in <b>failure</b> for the relay identity digest in
* <b>identity</b> and service ID <b>service_id</b>. If an entry already
* exists in the cache, the failure type is changed with <b>failure</b>. */
void
rend_cache_intro_failure_note(rend_intro_point_failure_t failure,
const uint8_t *identity,
const char *service_id)
{
int found;
rend_cache_failure_intro_t *entry;
found = cache_failure_intro_lookup(identity, service_id, &entry);
if (!found) {
cache_failure_intro_add(identity, service_id, failure);
} else {
/* Replace introduction point failure with this one. */
entry->failure_type = failure;
}
}
/** Remove all old v2 descriptors and those for which this hidden service
* directory is not responsible for any more. The cutoff is the time limit for
* which we want to keep the cache entry. In other words, any entry created
* before will be removed. */
size_t
rend_cache_clean_v2_descs_as_dir(time_t cutoff)
{
digestmap_iter_t *iter;
size_t bytes_removed = 0;
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) {
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));
bytes_removed += rend_cache_entry_allocation(ent);
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);
}
}
return bytes_removed;
}
/** Lookup in the client cache the given service ID <b>query</b> for
* <b>version</b>.
*
* Return 0 if found and if <b>e</b> is non NULL, set it with the entry
* found. Else, a negative value is returned and <b>e</b> is untouched.
* -EINVAL means that <b>query</b> is not a valid service id.
* -ENOENT means that no entry in the cache was found. */
int
rend_cache_lookup_entry(const char *query, int version, rend_cache_entry_t **e)
{
int ret = 0;
char key[REND_SERVICE_ID_LEN_BASE32 + 2]; /* <version><query>\0 */
rend_cache_entry_t *entry = NULL;
static const int default_version = 2;
tor_assert(rend_cache);
tor_assert(query);
if (!rend_valid_v2_service_id(query)) {
ret = -EINVAL;
goto end;
}
switch (version) {
case 0:
log_warn(LD_REND, "Cache lookup of a v0 renddesc is deprecated.");
break;
case 2:
/* Default is version 2. */
default:
tor_snprintf(key, sizeof(key), "%d%s", default_version, query);
entry = strmap_get_lc(rend_cache, key);
break;
}
if (!entry) {
ret = -ENOENT;
goto end;
}
tor_assert(entry->parsed && entry->parsed->intro_nodes);
if (e) {
*e = entry;
}
end:
return ret;
}
/*
* Lookup the v2 service descriptor with the service ID <b>query</b> in the
* local service descriptor cache. Return 0 if found and if <b>e</b> is
* non NULL, set it with the entry found. Else, a negative value is returned
* and <b>e</b> is untouched.
* -EINVAL means that <b>query</b> is not a valid service id.
* -ENOENT means that no entry in the cache was found. */
int
rend_cache_lookup_v2_desc_as_service(const char *query, rend_cache_entry_t **e)
{
int ret = 0;
rend_cache_entry_t *entry = NULL;
tor_assert(rend_cache_local_service);
tor_assert(query);
if (!rend_valid_v2_service_id(query)) {
ret = -EINVAL;
goto end;
}
/* Lookup descriptor and return. */
entry = strmap_get_lc(rend_cache_local_service, query);
if (!entry) {
ret = -ENOENT;
goto end;
}
if (e) {
*e = entry;
}
end:
return ret;
}
/** 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;
e->last_served = approx_time();
return 1;
}
return 0;
}
/** 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 0 on success, or -1 if we couldn't parse any of them.
*
* We should only call this function for public (e.g. non bridge) relays.
*/
int
rend_cache_store_v2_desc_as_dir(const char *desc)
{
const or_options_t *options = get_options();
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);
while (rend_parse_v2_service_descriptor(&parsed, desc_id, &intro_content,
&intro_size, &encoded_size,
&next_desc, current_desc, 1) >= 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 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));
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);
/* Treat something just uploaded as having been served a little
* while ago, so that flooding with new descriptors doesn't help
* too much.
*/
e->last_served = approx_time() - 3600;
} else {
rend_cache_decrement_allocation(rend_cache_entry_allocation(e));
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
}
e->parsed = parsed;
e->desc = tor_strndup(current_desc, encoded_size);
e->len = encoded_size;
rend_cache_increment_allocation(rend_cache_entry_allocation(e));
log_info(LD_REND, "Successfully stored service descriptor with desc ID "
"'%s' and len %d.",
safe_str(desc_id_base32), (int)encoded_size);
/* Statistics: Note down this potentially new HS. */
if (options->HiddenServiceStatistics) {
rep_hist_stored_maybe_new_hs(e->parsed->pk);
}
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 -1;
}
log_info(LD_REND, "Parsed %d and added %d descriptor%s.",
number_parsed, number_stored, number_stored != 1 ? "s" : "");
return 0;
}
/** Parse the v2 service descriptor in <b>desc</b> and store it to the
* local service rend cache. Don't attempt to decrypt the included list of
* introduction points.
*
* 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 0 on success, or -1 if we couldn't understand the descriptor.
*/
int
rend_cache_store_v2_desc_as_service(const char *desc)
{
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;
char service_id[REND_SERVICE_ID_LEN_BASE32+1];
rend_cache_entry_t *e;
int retval = -1;
tor_assert(rend_cache_local_service);
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) < 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;
}
/* Do we already have a newer descriptor? Allow new descriptors with a
rounded timestamp equal to or newer than the current descriptor */
e = (rend_cache_entry_t*) strmap_get_lc(rend_cache_local_service,
service_id);
if (e && e->parsed->timestamp > parsed->timestamp) {
log_info(LD_REND, "We already have a newer service descriptor for "
"service ID %s.", safe_str_client(service_id));
goto okay;
}
/* We don't care about the introduction points. */
tor_free(intro_content);
if (!e) {
e = tor_malloc_zero(sizeof(rend_cache_entry_t));
strmap_set_lc(rend_cache_local_service, service_id, e);
} else {
rend_cache_decrement_allocation(rend_cache_entry_allocation(e));
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
}
e->parsed = parsed;
e->desc = tor_malloc_zero(encoded_size + 1);
strlcpy(e->desc, desc, encoded_size + 1);
e->len = encoded_size;
rend_cache_increment_allocation(rend_cache_entry_allocation(e));
log_debug(LD_REND,"Successfully stored rend desc '%s', len %d.",
safe_str_client(service_id), (int)encoded_size);
return 0;
okay:
retval = 0;
err:
rend_service_descriptor_free(parsed);
tor_free(intro_content);
return retval;
}
/** 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.
*
* If the descriptor's descriptor ID doesn't match <b>desc_id_base32</b>,
* reject it.
*
* Return 0 on success, or -1 if we rejected the descriptor.
* If entry is not NULL, set it with the cache entry pointer of the descriptor.
*/
int
rend_cache_store_v2_desc_as_client(const char *desc,
const char *desc_id_base32,
const rend_data_t *rend_query,
rend_cache_entry_t **entry)
{
/*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];
char want_desc_id[DIGEST_LEN];
rend_cache_entry_t *e;
int retval = -1;
rend_data_v2_t *rend_data = TO_REND_DATA_V2(rend_query);
tor_assert(rend_cache);
tor_assert(desc);
tor_assert(desc_id_base32);
memset(want_desc_id, 0, sizeof(want_desc_id));
if (entry) {
*entry = NULL;
}
if (base32_decode(want_desc_id, sizeof(want_desc_id),
desc_id_base32, strlen(desc_id_base32)) != 0) {
log_warn(LD_BUG, "Couldn't decode base32 %s for descriptor id.",
escaped_safe_str_client(desc_id_base32));
goto err;
}
/* Parse the descriptor. */
if (rend_parse_v2_service_descriptor(&parsed, desc_id, &intro_content,
&intro_size, &encoded_size,
&next_desc, desc, 0) < 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 (rend_data->onion_address[0] != '\0' &&
strcmp(rend_data->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_data->onion_address));
goto err;
}
if (tor_memneq(desc_id, want_desc_id, DIGEST_LEN)) {
log_warn(LD_REND, "Received service descriptor for %s with incorrect "
"descriptor ID.", service_id);
goto err;
}
/* Decode/decrypt introduction points. */
if (intro_content && intro_size > 0) {
int n_intro_points;
if (rend_data->auth_type != REND_NO_AUTH &&
!tor_mem_is_zero(rend_data->descriptor_cookie,
sizeof(rend_data->descriptor_cookie))) {
char *ipos_decrypted = NULL;
size_t ipos_decrypted_size;
if (rend_decrypt_introduction_points(&ipos_decrypted,
&ipos_decrypted_size,
rend_data->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(service_id));
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 have the same exact copy already in our cache? */
tor_snprintf(key, sizeof(key), "2%s", service_id);
e = (rend_cache_entry_t*) strmap_get_lc(rend_cache, key);
if (e && !strcmp(desc, e->desc)) {
log_info(LD_REND,"We already have this service descriptor %s.",
safe_str_client(service_id));
goto okay;
}
/* Verify that we are not replacing an older descriptor. It's important to
* avoid an evil HSDir serving old descriptor. We validate if the
* timestamp is greater than and not equal because it's a rounded down
* timestamp to the hour so if the descriptor changed in the same hour,
* the rend cache failure will tell us if we have a new descriptor. */
if (e && e->parsed->timestamp > parsed->timestamp) {
log_info(LD_REND, "We already have a new enough service descriptor for "
"service ID %s with the same desc ID and version.",
safe_str_client(service_id));
goto okay;
}
/* Lookup our failure cache for intro point that might be unusable. */
validate_intro_point_failure(parsed, service_id);
/* It's now possible that our intro point list is empty, which means that
* this descriptor is useless to us because intro points have all failed
* somehow before. Discard the descriptor. */
if (smartlist_len(parsed->intro_nodes) == 0) {
log_info(LD_REND, "Service descriptor with service ID %s has no "
"usable intro points. Discarding it.",
safe_str_client(service_id));
goto err;
}
/* Now either purge the current one and replace its content or create a
* new one and add it to the rend cache. */
if (!e) {
e = tor_malloc_zero(sizeof(rend_cache_entry_t));
strmap_set_lc(rend_cache, key, e);
} else {
rend_cache_decrement_allocation(rend_cache_entry_allocation(e));
rend_cache_failure_remove(e->parsed);
rend_service_descriptor_free(e->parsed);
tor_free(e->desc);
}
e->parsed = parsed;
e->desc = tor_malloc_zero(encoded_size + 1);
strlcpy(e->desc, desc, encoded_size + 1);
e->len = encoded_size;
rend_cache_increment_allocation(rend_cache_entry_allocation(e));
log_debug(LD_REND,"Successfully stored rend desc '%s', len %d.",
safe_str_client(service_id), (int)encoded_size);
if (entry) {
*entry = e;
}
return 0;
okay:
if (entry) {
*entry = e;
}
retval = 0;
err:
rend_service_descriptor_free(parsed);
tor_free(intro_content);
return retval;
}
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