diff options
Diffstat (limited to 'src/or/rendcache.c')
| -rw-r--r-- | src/or/rendcache.c | 302 |
1 files changed, 299 insertions, 3 deletions
diff --git a/src/or/rendcache.c b/src/or/rendcache.c index be94ef4445..9a33046fb6 100644 --- a/src/or/rendcache.c +++ b/src/or/rendcache.c @@ -9,7 +9,6 @@ #include "rendcache.h" #include "config.h" -#include "rendcommon.h" #include "rephist.h" #include "routerlist.h" #include "routerparse.h" @@ -22,6 +21,33 @@ static strmap_t *rend_cache = NULL; * 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 unsuable. + * + * 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 realy 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; @@ -32,6 +58,7 @@ rend_cache_init(void) { rend_cache = strmap_new(); rend_cache_v2_dir = digestmap_new(); + rend_cache_failure = strmap_new(); } /** Return the approximate number of bytes needed to hold <b>e</b>. */ @@ -85,6 +112,83 @@ rend_cache_increment_allocation(size_t n) } } +/** 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); +} + +/** 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_FOREACH_MODIFY(entry->intro_failures, key, + rend_cache_failure_intro_t *, e) { + rend_cache_failure_intro_entry_free(e); + MAP_DEL_CURRENT(key); + } DIGESTMAP_FOREACH_END; + 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 *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) @@ -92,6 +196,9 @@ 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); @@ -111,11 +218,42 @@ rend_cache_free_all(void) { strmap_free(rend_cache, rend_cache_entry_free_); digestmap_free(rend_cache_v2_dir, rend_cache_entry_free_); + strmap_free(rend_cache_failure, rend_cache_failure_entry_free_); rend_cache = NULL; rend_cache_v2_dir = 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 service descriptor cache. */ void @@ -150,6 +288,140 @@ rend_cache_purge(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 failure cache"); + strmap_free(rend_cache_failure, rend_cache_failure_entry_free_); + } + rend_cache_failure = strmap_new(); +} + +/** Lookup the rend failure cache using a relay identity digest in + * <b>identity</b> and service ID <b>service_id</b>. 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; +} + +/** 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; + + /* 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); + digestmap_set(fail_entry->intro_failures, (char *) identity, 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) { + /* 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); + rend_intro_point_free(intro); + /* Keep it for our new entry. */ + digestmap_set(new_entry->intro_failures, (char *) identity, entry); + 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. * @@ -537,20 +809,44 @@ rend_cache_store_v2_desc_as_client(const char *desc, "the future.", safe_str_client(service_id)); goto err; } - /* Do we already have a newer descriptor? */ + /* 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 && e->parsed->timestamp >= parsed->timestamp) { + 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 tells 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 unsuable. */ + validate_intro_point_failure(parsed, service_id); + /* It's now possible that our intro point list is empty, this 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, every " + "intro points are unusable. Discarding it.", + safe_str_client(service_id)); + goto err; + } + /* Now either purge the current one and replace it's 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); } |