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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
This commit is contained in:
Nick Mathewson
parent
9c3df07b56
commit
2dc6019edb
129
src/or/dns.c
129
src/or/dns.c
@ -97,6 +97,8 @@ static int launch_resolve(edge_connection_t *exitconn);
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static void add_wildcarded_test_address(const char *address);
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static int configure_nameservers(int force);
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static int answer_is_wildcarded(const char *ip);
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static int dns_resolve_impl(edge_connection_t *exitconn, int is_resolve,
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or_circuit_t *oncirc, char **resolved_to_hostname);
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#ifdef DEBUG_DNS_CACHE
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static void _assert_cache_ok(void);
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#define assert_cache_ok() _assert_cache_ok()
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@ -523,48 +525,85 @@ parse_inaddr_arpa_address(const char *address, struct in_addr *in)
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* On "pending", link the connection to resolving streams. Otherwise,
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* clear its on_circuit field.
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*/
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/* XXXX020 Split this into a helper that checks whether there is an answer,
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* and a caller that takes appropriate action based on what happened. */
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int
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dns_resolve(edge_connection_t *exitconn)
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{
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or_circuit_t *oncirc = TO_OR_CIRCUIT(exitconn->on_circuit);
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int is_resolve, r;
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char *hostname = NULL;
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is_resolve = exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE;
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r = dns_resolve_impl(exitconn, is_resolve, oncirc, &hostname);
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switch (r) {
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case 1:
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if (is_resolve) {
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if (hostname)
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send_resolved_hostname_cell(exitconn, hostname);
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else
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send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
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} else {
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exitconn->next_stream = oncirc->n_streams;
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oncirc->n_streams = exitconn;
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}
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break;
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case 0:
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exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
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exitconn->next_stream = oncirc->resolving_streams;
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oncirc->resolving_streams = exitconn;
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break;
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case -2:
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case -1:
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if (is_resolve) {
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send_resolved_cell(exitconn,
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(r == -1) ? RESOLVED_TYPE_ERROR : RESOLVED_TYPE_ERROR_TRANSIENT);
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}
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//circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
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exitconn->on_circuit = NULL;
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if (!exitconn->_base.marked_for_close)
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connection_free(TO_CONN(exitconn));
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break;
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default:
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tor_assert(0);
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}
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tor_free(hostname);
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return r;
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}
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/** Helper function for dns_resolve: same functionality, but does not handle:
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* - marking connections on error and clearing their on_circuit
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* - linking connections to n_streams/resolving_streams,
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* - sending resolved cells if we have an answer/error right away,
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*
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* Returns -2 on a transient error. Sets *<b>hostname_out</b> to a newly
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* allocated string holding a cached reverse DNS value, if any.
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*/
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static int
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dns_resolve_impl(edge_connection_t *exitconn, int is_resolve,
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or_circuit_t *oncirc, char **hostname_out)
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{
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cached_resolve_t *resolve;
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cached_resolve_t search;
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pending_connection_t *pending_connection;
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struct in_addr in;
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time_t now = time(NULL);
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int is_reverse = 0, is_resolve, r;
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or_circuit_t *oncirc = TO_OR_CIRCUIT(exitconn->on_circuit);
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int is_reverse = 0, r;
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assert_connection_ok(TO_CONN(exitconn), 0);
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tor_assert(exitconn->_base.s == -1);
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assert_cache_ok();
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tor_assert(oncirc);
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is_resolve = exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE;
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/* first check if exitconn->_base.address is an IP. If so, we already
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* know the answer. */
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if (tor_inet_aton(exitconn->_base.address, &in) != 0) {
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exitconn->_base.addr = ntohl(in.s_addr);
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exitconn->address_ttl = DEFAULT_DNS_TTL;
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if (is_resolve) {
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send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
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} else {
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exitconn->next_stream = oncirc->n_streams;
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oncirc->n_streams = exitconn;
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}
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return 1;
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}
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if (address_is_invalid_destination(exitconn->_base.address, 0)) {
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log(LOG_PROTOCOL_WARN, LD_EXIT,
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"Rejecting invalid destination address %s",
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escaped_safe_str(exitconn->_base.address));
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if (is_resolve)
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send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
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//circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
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exitconn->on_circuit = NULL;
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if (!exitconn->_base.marked_for_close)
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connection_free(TO_CONN(exitconn));
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return -1;
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}
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@ -593,12 +632,6 @@ dns_resolve(edge_connection_t *exitconn)
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"sending error.",
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escaped_safe_str(exitconn->_base.address));
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if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE)
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send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
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//circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
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exitconn->on_circuit = NULL;
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if (!exitconn->_base.marked_for_close)
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connection_free(TO_CONN(exitconn));
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return -1;
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}
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//log_notice(LD_EXIT, "Looks like an address %s",
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@ -620,10 +653,6 @@ dns_resolve(edge_connection_t *exitconn)
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log_debug(LD_EXIT,"Connection (fd %d) waiting for pending DNS "
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"resolve of %s", exitconn->_base.s,
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escaped_safe_str(exitconn->_base.address));
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exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
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exitconn->next_stream = oncirc->resolving_streams;
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oncirc->resolving_streams = exitconn;
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return 0;
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case CACHE_STATE_CACHED_VALID:
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log_debug(LD_EXIT,"Connection (fd %d) found cached answer for %s",
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@ -632,30 +661,15 @@ dns_resolve(edge_connection_t *exitconn)
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exitconn->address_ttl = resolve->ttl;
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if (resolve->is_reverse) {
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tor_assert(is_resolve);
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send_resolved_hostname_cell(exitconn,
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resolve->result.hostname);
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*hostname_out = tor_strdup(resolve->result.hostname);
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} else {
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exitconn->_base.addr = resolve->result.addr;
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if (is_resolve)
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send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
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}
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if (!is_resolve) {
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/* It's a connect; add it into the linked list of n_streams on this
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circuit */
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exitconn->next_stream = oncirc->n_streams;
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oncirc->n_streams = exitconn;
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}
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return 1;
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case CACHE_STATE_CACHED_FAILED:
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log_debug(LD_EXIT,"Connection (fd %d) found cached error for %s",
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exitconn->_base.s,
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escaped_safe_str(exitconn->_base.address));
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if (is_resolve)
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send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
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// circuit_detach_stream(TO_CIRCUIT(oncirc), exitconn);
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exitconn->on_circuit = NULL;
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if (!exitconn->_base.marked_for_close)
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connection_free(TO_CONN(exitconn));
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return -1;
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case CACHE_STATE_DONE:
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log_err(LD_BUG, "Found a 'DONE' dns resolve still in the cache.");
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@ -674,7 +688,6 @@ dns_resolve(edge_connection_t *exitconn)
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pending_connection = tor_malloc_zero(sizeof(pending_connection_t));
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pending_connection->conn = exitconn;
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resolve->pending_connections = pending_connection;
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exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
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/* Add this resolve to the cache and priority queue. */
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HT_INSERT(cache_map, &cache_root, resolve);
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@ -684,17 +697,7 @@ dns_resolve(edge_connection_t *exitconn)
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escaped_safe_str(exitconn->_base.address));
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assert_cache_ok();
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r = launch_resolve(exitconn);
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if (r == 0) {
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exitconn->next_stream = oncirc->resolving_streams;
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oncirc->resolving_streams = exitconn;
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} else {
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tor_assert(r<0);
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exitconn->on_circuit = NULL;
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if (!exitconn->_base.marked_for_close)
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connection_free(TO_CONN(exitconn));
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}
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return r;
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return launch_resolve(exitconn);
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}
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/** Log an error and abort if conn is waiting for a DNS resolve.
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@ -1196,7 +1199,8 @@ evdns_callback(int result, char type, int count, int ttl, void *addresses,
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}
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/** For eventdns: start resolving as necessary to find the target for
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* <b>exitconn</b>. Returns -1 on error, 0 on "resolve launched." */
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* <b>exitconn</b>. Returns -1 on error, -2 on transient errror,
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* 0 on "resolve launched." */
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static int
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launch_resolve(edge_connection_t *exitconn)
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{
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@ -1231,18 +1235,11 @@ launch_resolve(edge_connection_t *exitconn)
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if (r) {
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log_warn(LD_EXIT, "eventdns rejected address %s: error %d.",
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escaped_safe_str(addr), r);
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if (exitconn->_base.purpose == EXIT_PURPOSE_RESOLVE) {
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if (evdns_err_is_transient(r))
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send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR_TRANSIENT);
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else {
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exitconn->address_ttl = DEFAULT_DNS_TTL;
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send_resolved_cell(exitconn, RESOLVED_TYPE_ERROR);
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}
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}
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r = evdns_err_is_transient(r) ? -2 : -1;
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dns_cancel_pending_resolve(addr); /* also sends end and frees */
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tor_free(addr);
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}
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return r ? -1 : 0;
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return r;
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}
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/** How many requests for bogus addresses have we launched so far? */
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