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- /* Copyright (c) 2015, The Tor Project, Inc. */
- /* See LICENSE for licensing information */
- /**
- * \file rendcache.c
- * \brief Hidden service desriptor cache.
- **/
- #include "rendcache.h"
- #include "config.h"
- #include "rendcommon.h"
- #include "rephist.h"
- #include "routerlist.h"
- #include "routerparse.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 descriptor id to rend_cache_entry_t; only for hidden service
- * directories. */
- static digestmap_t *rend_cache_v2_dir = 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();
- }
- /** 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. */
- static 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. */
- static 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 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));
- 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;
- rend_cache_total_allocation = 0;
- }
- /** 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.
- *
- * If at all possible, remove at least <b>force_remove</b> bytes of data.
- */
- void
- rend_cache_clean_v2_descs_as_dir(time_t now, size_t force_remove)
- {
- digestmap_iter_t *iter;
- time_t cutoff = now - REND_CACHE_MAX_AGE - REND_CACHE_MAX_SKEW;
- const int LAST_SERVED_CUTOFF_STEP = 1800;
- time_t last_served_cutoff = cutoff;
- size_t bytes_removed = 0;
- do {
- 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 ||
- ent->last_served < last_served_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));
- 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);
- }
- }
- /* In case we didn't remove enough bytes, advance the cutoff a little. */
- last_served_cutoff += LAST_SERVED_CUTOFF_STEP;
- if (last_served_cutoff > now)
- break;
- } while (bytes_removed < force_remove);
- }
- /** 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_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 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 an appropriate rend_cache_store_status_t.
- */
- rend_cache_store_status_t
- 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);
- 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, 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 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));
- 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 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.
- *
- * If the descriptor's descriptor ID doesn't match <b>desc_id_base32</b>,
- * reject it.
- *
- * Return an appropriate rend_cache_store_status_t. If entry is not NULL,
- * set it with the cache entry pointer of the descriptor.
- */
- rend_cache_store_status_t
- 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;
- rend_cache_store_status_t retval = RCS_BADDESC;
- 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_query->onion_address[0] != '\0' &&
- 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;
- }
- 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_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.");
- 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 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 new enough service descriptor for "
- "service ID %s with the same desc ID and version.",
- safe_str_client(service_id));
- goto okay;
- }
- 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_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 RCS_OKAY;
- okay:
- if (entry) {
- *entry = e;
- }
- retval = RCS_OKAY;
- err:
- rend_service_descriptor_free(parsed);
- tor_free(intro_content);
- return retval;
- }
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