Commit 2dc6019e authored by Nick Mathewson's avatar Nick Mathewson 🥄
Browse files

r12688@Kushana: nickm | 2007-04-09 17:29:12 -0400

 Simplify dns_resolve: use a helper function so that we handle the error/answer/pending cases uniformly in dns_resolve, and everything else in dns_resolve_impl.


svn:r9932
parent 9c3df07b
......@@ -97,6 +97,8 @@ static int launch_resolve(edge_connection_t *exitconn);
static void add_wildcarded_test_address(const char *address);
static int configure_nameservers(int force);
static int answer_is_wildcarded(const char *ip);
static int dns_resolve_impl(edge_connection_t *exitconn, int is_resolve,
or_circuit_t *oncirc, char **resolved_to_hostname);
#ifdef DEBUG_DNS_CACHE
static void _assert_cache_ok(void);
#define assert_cache_ok() _assert_cache_ok()
......@@ -523,48 +525,85 @@ parse_inaddr_arpa_address(const char *address, struct in_addr *in)
* On "pending", link the connection to resolving streams. Otherwise,
* clear its on_circuit field.
*/
/* XXXX020 Split this into a helper that checks whether there is an answer,
* and a caller that takes appropriate action based on what happened. */
int
dns_resolve(edge_connection_t *exitconn)
{
or_circuit_t *oncirc = TO_OR_CIRCUIT(exitconn->on_circuit);
int is_resolve, r;
char *hostname = NULL;
is_resolve = exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE;
r = dns_resolve_impl(exitconn, is_resolve, oncirc, &hostname);
switch (r) {
case 1:
if (is_resolve) {
if (hostname)
send_resolved_hostname_cell(exitconn, hostname);
else
send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
} else {
exitconn->next_stream = oncirc->n_streams;
oncirc->n_streams = exitconn;
}
break;
case 0:
exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
exitconn->next_stream = oncirc->resolving_streams;
oncirc->resolving_streams = exitconn;
break;
case -2:
case -1:
if (is_resolve) {
send_resolved_cell(exitconn,
(r == -1) ? RESOLVED_TYPE_ERROR : RESOLVED_TYPE_ERROR_TRANSIENT);
}
//circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
exitconn->on_circuit = NULL;
if (!exitconn->_base.marked_for_close)
connection_free(TO_CONN(exitconn));
break;
default:
tor_assert(0);
}
tor_free(hostname);
return r;
}
/** Helper function for dns_resolve: same functionality, but does not handle:
* - marking connections on error and clearing their on_circuit
* - linking connections to n_streams/resolving_streams,
* - sending resolved cells if we have an answer/error right away,
*
* Returns -2 on a transient error. Sets *<b>hostname_out</b> to a newly
* allocated string holding a cached reverse DNS value, if any.
*/
static int
dns_resolve_impl(edge_connection_t *exitconn, int is_resolve,
or_circuit_t *oncirc, char **hostname_out)
{
cached_resolve_t *resolve;
cached_resolve_t search;
pending_connection_t *pending_connection;
struct in_addr in;
time_t now = time(NULL);
int is_reverse = 0, is_resolve, r;
or_circuit_t *oncirc = TO_OR_CIRCUIT(exitconn->on_circuit);
int is_reverse = 0, r;
assert_connection_ok(TO_CONN(exitconn), 0);
tor_assert(exitconn->_base.s == -1);
assert_cache_ok();
tor_assert(oncirc);
is_resolve = exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE;
/* first check if exitconn->_base.address is an IP. If so, we already
* know the answer. */
if (tor_inet_aton(exitconn->_base.address, &in) != 0) {
exitconn->_base.addr = ntohl(in.s_addr);
exitconn->address_ttl = DEFAULT_DNS_TTL;
if (is_resolve) {
send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
} else {
exitconn->next_stream = oncirc->n_streams;
oncirc->n_streams = exitconn;
}
return 1;
}
if (address_is_invalid_destination(exitconn->_base.address, 0)) {
log(LOG_PROTOCOL_WARN, LD_EXIT,
"Rejecting invalid destination address %s",
escaped_safe_str(exitconn->_base.address));
if (is_resolve)
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
//circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
exitconn->on_circuit = NULL;
if (!exitconn->_base.marked_for_close)
connection_free(TO_CONN(exitconn));
return -1;
}
......@@ -593,12 +632,6 @@ dns_resolve(edge_connection_t *exitconn)
"sending error.",
escaped_safe_str(exitconn->_base.address));
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
//circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
exitconn->on_circuit = NULL;
if (!exitconn->_base.marked_for_close)
connection_free(TO_CONN(exitconn));
return -1;
}
//log_notice(LD_EXIT, "Looks like an address %s",
......@@ -620,10 +653,6 @@ dns_resolve(edge_connection_t *exitconn)
log_debug(LD_EXIT,"Connection (fd %d) waiting for pending DNS "
"resolve of %s", exitconn->_base.s,
escaped_safe_str(exitconn->_base.address));
exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
exitconn->next_stream = oncirc->resolving_streams;
oncirc->resolving_streams = exitconn;
return 0;
case CACHE_STATE_CACHED_VALID:
log_debug(LD_EXIT,"Connection (fd %d) found cached answer for %s",
......@@ -632,30 +661,15 @@ dns_resolve(edge_connection_t *exitconn)
exitconn->address_ttl = resolve->ttl;
if (resolve->is_reverse) {
tor_assert(is_resolve);
send_resolved_hostname_cell(exitconn,
resolve->result.hostname);
*hostname_out = tor_strdup(resolve->result.hostname);
} else {
exitconn->_base.addr = resolve->result.addr;
if (is_resolve)
send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
}
if (!is_resolve) {
/* It's a connect; add it into the linked list of n_streams on this
circuit */
exitconn->next_stream = oncirc->n_streams;
oncirc->n_streams = exitconn;
}
return 1;
case CACHE_STATE_CACHED_FAILED:
log_debug(LD_EXIT,"Connection (fd %d) found cached error for %s",
exitconn->_base.s,
escaped_safe_str(exitconn->_base.address));
if (is_resolve)
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
// circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
exitconn->on_circuit = NULL;
if (!exitconn->_base.marked_for_close)
connection_free(TO_CONN(exitconn));
return -1;
case CACHE_STATE_DONE:
log_err(LD_BUG, "Found a 'DONE' dns resolve still in the cache.");
......@@ -674,7 +688,6 @@ dns_resolve(edge_connection_t *exitconn)
pending_connection = tor_malloc_zero(sizeof(pending_connection_t));
pending_connection->conn = exitconn;
resolve->pending_connections = pending_connection;
exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
/* Add this resolve to the cache and priority queue. */
HT_INSERT(cache_map, &cache_root, resolve);
......@@ -684,17 +697,7 @@ dns_resolve(edge_connection_t *exitconn)
escaped_safe_str(exitconn->_base.address));
assert_cache_ok();
r = launch_resolve(exitconn);
if (r == 0) {
exitconn->next_stream = oncirc->resolving_streams;
oncirc->resolving_streams = exitconn;
} else {
tor_assert(r<0);
exitconn->on_circuit = NULL;
if (!exitconn->_base.marked_for_close)
connection_free(TO_CONN(exitconn));
}
return r;
return launch_resolve(exitconn);
}
/** Log an error and abort if conn is waiting for a DNS resolve.
......@@ -1196,7 +1199,8 @@ evdns_callback(int result, char type, int count, int ttl, void *addresses,
}
/** For eventdns: start resolving as necessary to find the target for
* <b>exitconn</b>. Returns -1 on error, 0 on "resolve launched." */
* <b>exitconn</b>. Returns -1 on error, -2 on transient errror,
* 0 on "resolve launched." */
static int
launch_resolve(edge_connection_t *exitconn)
{
......@@ -1231,18 +1235,11 @@ launch_resolve(edge_connection_t *exitconn)
if (r) {
log_warn(LD_EXIT, "eventdns rejected address %s: error %d.",
escaped_safe_str(addr), r);
if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE) {
if (evdns_err_is_transient(r))
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT);
else {
exitconn->address_ttl = DEFAULT_DNS_TTL;
send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
}
}
r = evdns_err_is_transient(r) ? -2 : -1;
dns_cancel_pending_resolve(addr); /* also sends end and frees */
tor_free(addr);
}
return r ? -1 : 0;
return r;
}
/** How many requests for bogus addresses have we launched so far? */
......
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