Add some debugging asserts to dns.c; these are too expensive to leave in permanently. (a0cf95e1) · Commits · The Tor Project / Core / Tor

src/or/dns.c

+41 −2

Original line number	Diff line number	Diff line
		@@ -57,12 +57,15 @@ typedef struct pending_connection_t {
		struct pending_connection_t *next;
		} pending_connection_t;

		#define CACHED_RESOLVE_MAGIC 0x1234F00D

		/** A DNS request: possibly completed, possibly pending; cached_resolve
		* structs are stored at the OR side in a hash table, and as a linked
		* list from oldest to newest.
		*/
		typedef struct cached_resolve_t {
		HT_ENTRY(cached_resolve_t) node;
		uint32_t magic;
		char address[MAX_ADDRESSLEN]; /*< The hostname to be resolved. /
		uint32_t addr; /*< IPv4 addr for <b>address</b>. /
		char state; /**< 0 is pending; 1 means answer is valid; 2 means resolve
		@@ -87,6 +90,8 @@ static int dnsworker_main(void *data);
		static int spawn_dnsworker(void);
		static int spawn_enough_dnsworkers(void);
		#endif
		static void assert_cache_ok(void);
		static void assert_resolve_ok(cached_resolve_t *resolve);

		/** Hash table of cached_resolve objects. */
		static HT_HEAD(cache_map, cached_resolve_t) cache_root;
		@@ -97,6 +102,7 @@ static INLINE int
		cached_resolves_eq(cached_resolve_t a, cached_resolve_t b)
		{
		/* make this smarter one day? */
		assert_resolve_ok(a); // Not b; b may be just a search.
		return !strncmp(a->address, b->address, MAX_ADDRESSLEN);
		}

		@@ -192,6 +198,7 @@ _free_cached_resolve(cached_resolve_t *r)
		r->pending_connections = victim->next;
		tor_free(victim);
		}
		r->magic = 0xFF00FF00;
		tor_free(r);
		}

		@@ -258,6 +265,7 @@ purge_expired_resolves(uint32_t now)
		newest_cached_resolve = NULL; /* then make sure the list's tail knows
		* that too */
		HT_REMOVE(cache_map, &cache_root, resolve);
		resolve->magic = 0xF0BBF0BB;
		tor_free(resolve);
		}
		}
		@@ -340,6 +348,8 @@ dns_resolve(connection_t *exitconn)
		assert_connection_ok(exitconn, 0);
		tor_assert(exitconn->s == -1);

		assert_cache_ok();

		/* first check if exitconn->address is an IP. If so, we already
		* know the answer. */
		if (tor_inet_aton(exitconn->address, &in) != 0) {
		@@ -398,6 +408,7 @@ dns_resolve(connection_t *exitconn)
		}
		/* not there, need to add it */
		resolve = tor_malloc_zero(sizeof(cached_resolve_t));
		resolve->magic = CACHED_RESOLVE_MAGIC;
		resolve->state = CACHE_STATE_PENDING;
		resolve->expire = now + DEFAULT_DNS_TTL; /* this will get replaced. */
		strlcpy(resolve->address, exitconn->address, sizeof(resolve->address));
		@@ -411,6 +422,7 @@ dns_resolve(connection_t *exitconn)
		insert_resolve(resolve);
		log_debug(LD_EXIT,"Assigning question %s to dnsworker.",
		escaped_safe_str(exitconn->address));
		assert_cache_ok();
		return assign_to_dnsworker(exitconn);
		}

		@@ -581,7 +593,7 @@ dns_purge_resolve(cached_resolve_t *resolve)

		/* remove resolve from the map */
		HT_REMOVE(cache_map, &cache_root, resolve);

		resolve->magic = 0xAAAAAAAA;
		tor_free(resolve);
		}

		@@ -593,7 +605,8 @@ dns_purge_resolve(cached_resolve_t *resolve)
		* DNS_RESOLVE_{FAILED_TRANSIENT\|FAILED_PERMANENT\|SUCCEEDED}.
		*/
		static void
		dns_found_answer(const char *address, uint32_t addr, char outcome, uint32_t ttl)
		dns_found_answer(const char *address, uint32_t addr, char outcome,
		uint32_t ttl)
		{
		pending_connection_t *pend;
		cached_resolve_t search;
		@@ -601,6 +614,8 @@ dns_found_answer(const char *address, uint32_t addr, char outcome, uint32_t ttl)
		connection_t *pendconn;
		circuit_t *circ;

		assert_cache_ok();

		strlcpy(search.address, address, sizeof(search.address));

		resolve = HT_FIND(cache_map, &cache_root, &search);
		@@ -608,6 +623,7 @@ dns_found_answer(const char *address, uint32_t addr, char outcome, uint32_t ttl)
		log_info(LD_EXIT,"Resolved unasked address %s; caching anyway.",
		escaped_safe_str(address));
		resolve = tor_malloc_zero(sizeof(cached_resolve_t));
		resolve->magic = CACHED_RESOLVE_MAGIC;
		resolve->state = (outcome == DNS_RESOLVE_SUCCEEDED) ?
		CACHE_STATE_VALID : CACHE_STATE_FAILED;
		strlcpy(resolve->address, address, sizeof(resolve->address));
		@@ -695,6 +711,8 @@ dns_found_answer(const char *address, uint32_t addr, char outcome, uint32_t ttl)
		if (outcome == DNS_RESOLVE_FAILED_TRANSIENT) { /* remove from cache */
		dns_purge_resolve(resolve);
		}

		assert_cache_ok();
		}

		#ifndef USE_EVENTDNS
		@@ -1175,3 +1193,24 @@ assign_to_dnsworker(connection_t *exitconn)
		}
		#endif /* USE_EVENTDNS */

		static void
		assert_resolve_ok(cached_resolve_t *resolve)
		{
		tor_assert(resolve);
		tor_assert(resolve->magic == CACHED_RESOLVE_MAGIC);
		tor_assert(strlen(resolve->address) < MAX_ADDRESSLEN);
		tor_assert(! resolve->next \|\| resolve->next->magic == CACHED_RESOLVE_MAGIC);

		}

		static void
		assert_cache_ok(void)
		{
		cached_resolve_t **resolve;
		tor_assert(_cache_map_HT_REP_OK(&cache_root));

		HT_FOREACH(resolve, cache_map, &cache_root) {
		assert_resolve_ok(*resolve);
		}
		}