diff options
Diffstat (limited to 'src/or/dns.c')
| -rw-r--r-- | src/or/dns.c | 84 |
1 files changed, 60 insertions, 24 deletions
diff --git a/src/or/dns.c b/src/or/dns.c index b7b5e0e64..6090c459f 100644 --- a/src/or/dns.c +++ b/src/or/dns.c @@ -127,10 +127,16 @@ typedef struct pending_connection_t { * connections, and should appear in the hash table. */ #define CACHE_STATE_CACHED 2 -/* DOCDOC */ +/** @name status values for a single DNS request. + * + * @{ */ +/** The DNS request is in progress. */ #define RES_STATUS_INFLIGHT 1 +/** The DNS request finished and gave an answer */ #define RES_STATUS_DONE_OK 2 +/** The DNS request finished and gave an error */ #define RES_STATUS_DONE_ERR 3 +/**@}*/ /** A DNS request: possibly completed, possibly pending; cached_resolve * structs are stored at the OR side in a hash table, and as a linked @@ -138,27 +144,34 @@ typedef struct pending_connection_t { */ typedef struct cached_resolve_t { HT_ENTRY(cached_resolve_t) node; - uint32_t magic; + uint32_t magic; /**< Must be CACHED_RESOLVE_MAGIC */ char address[MAX_ADDRESSLEN]; /**< The hostname to be resolved. */ union { - uint32_t addr_ipv4; /**< IPv4 addr for <b>address</b>. */ - int err_ipv4; - } result_ipv4; + uint32_t addr_ipv4; /**< IPv4 addr for <b>address</b>, if successful */ + int err_ipv4; /**< One of DNS_ERR_*, if IPv4 lookup failed. */ + } result_ipv4; /**< Outcome of IPv4 lookup */ union { - struct in6_addr addr_ipv6; - int err_ipv6; - } result_ipv6; + struct in6_addr addr_ipv6; /**< IPv6 addr for <b>address</b>, if + * successful */ + int err_ipv6; /**< One of DNS_ERR_*, if IPv6 lookup failed. */ + } result_ipv6; /**< Outcome of IPv6 lookup, if any */ union { - char *hostname; - int err_hostname; + char *hostname; /** A hostname, if PTR lookup happened successfully*/ + int err_hostname; /** One of DNS_ERR_*, if PTR lookup failed. */ } result_ptr; + /** @name Status fields + * + * These take one of the RES_STATUS_* values, depending on the state + * of the corresponding lookup. + * + * @{ */ unsigned int res_status_ipv4 : 2; unsigned int res_status_ipv6 : 2; unsigned int res_status_hostname : 2; - + /**@}*/ uint8_t state; /**< Is this cached entry pending/done/informative? */ - //uint8_t is_reverse; /**< Is this a reverse (addr-to-hostname) lookup? */ + time_t expire; /**< Remove items from cache after this time. */ uint32_t ttl_ipv4; /**< What TTL did the nameserver tell us? */ uint32_t ttl_ipv6; /**< What TTL did the nameserver tell us? */ @@ -201,9 +214,11 @@ 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; -/*DOCDOC*/ +/** Global: how many IPv6 requests have we made in all? */ static uint64_t n_ipv6_requests_made = 0; +/** Global: how many IPv6 requests have timed out? */ static uint64_t n_ipv6_timeouts = 0; +/** Global: Do we think that IPv6 DNS is broken? */ static int dns_is_broken_for_ipv6 = 0; /** Function to compare hashed resolves on their addresses; used to @@ -445,7 +460,7 @@ cached_resolve_add_answer(cached_resolve_t *resolve, } } -/*DOCDOC*/ +/** Return true iff there are no in-flight requests for <b>resolve</b>. */ static int cached_resolve_have_all_answers(const cached_resolve_t *resolve) { @@ -911,7 +926,16 @@ dns_resolve_impl(edge_connection_t *exitconn, int is_resolve, return launch_resolve(resolve); } -/* DOCDOC must set address_ttl, addr, etc.*/ +/** Given an exit connection <b>exitconn</b>, and a cached_resolve_t + * <b>resolve</b> whose DNS lookups have all succeeded or failed, update the + * appropriate fields (address_ttl and addr) of <b>exitconn</b>. + * + * If this is a reverse lookup, set *<b>hostname_out</b> to a newly allocated + * copy of the name resulting hostname. + * + * Return -2 on a transient error, -1 on a permenent error, and 1 on + * a successful lookup. + */ static int set_exitconn_info_from_resolve(edge_connection_t *exitconn, const cached_resolve_t *resolve, @@ -1178,11 +1202,14 @@ is_test_address(const char *address) smartlist_string_isin_case(options->ServerDNSTestAddresses, address); } -/** Called on the OR side when a DNS worker or the eventdns library tells us - * the outcome of a DNS resolve: tell all pending connections about the result - * of the lookup, and cache the value. (<b>address</b> is a NUL-terminated - * string containing the address to look up; <b>addr</b> is an IPv4 address in - * host order; DOCDOC +/** Called on the OR side when the eventdns library tells us the outcome of a + * single DNS resolve: remember the answer, and tell all pending connections + * about the result of the lookup if the lookup is now done. (<b>address</b> + * is a NUL-terminated string containing the address to look up; + * <b>query_type</b> is one of DNS_{IPv4_A,IPv6_AAAA,PTR}; <b>dns_answer</b> + * is DNS_OK or one of DNS_ERR_*, <b>addr</b> is an IPv4 or IPv6 address if we + * got one; <b>hostname</b> is a hostname fora PTR request if we got one, and + * <b>ttl</b> is the time-to-live of this answer, in seconds.) */ static void dns_found_answer(const char *address, uint8_t query_type, @@ -1229,7 +1256,9 @@ dns_found_answer(const char *address, uint8_t query_type, } } -/*DOCDOC*/ +/** Given a pending cached_resolve_t that we just finished resolving, + * inform every connection that was waiting for the outcome of that + * resolution. */ static void inform_pending_connections(cached_resolve_t *resolve) { @@ -1306,7 +1335,12 @@ inform_pending_connections(cached_resolve_t *resolve) } } -/*DOCDOC*/ +/** Remove a pending cached_resolve_t from the hashtable, and add a + * corresponding cached cached_resolve_t. + * + * This function is only necessary because of the perversity of our + * cache timeout code; see inline comment for ideas on eliminating it. + **/ static void make_pending_resolve_cached(cached_resolve_t *resolve) { @@ -1627,7 +1661,9 @@ evdns_callback(int result, char type, int count, int ttl, void *addresses, tor_free(arg_); } -/**DOCDOC*/ +/** Start a single DNS resolve for <b>address</b> (if <b>query_type</b> is + * DNS_IPv4_A or DNS_IPv6_AAAA) <b>ptr_address</b> (if <b>query_type</b> is + * DNS_PTR). Return 0 if we launched the request, -1 otherwise. */ static int launch_one_resolve(const char *address, uint8_t query_type, const tor_addr_t *ptr_address) @@ -2011,7 +2047,7 @@ dns_seems_to_be_broken(void) return dns_is_completely_invalid; } -/** DOCDOC */ +/** Return true iff we think that IPv6 hostname lookup is broken */ int dns_seems_to_be_broken_for_ipv6(void) { |