[or-cvs] r10399: Fix handling of resolves with very long or otherwise malform (in tor/trunk: . src/or)

[nickm@xxxxxxxx]

Author: nickm
Date: 2007-05-29 15:54:51 -0400 (Tue, 29 May 2007)
New Revision: 10399

Modified:
   tor/trunk/
   tor/trunk/src/or/circuituse.c
   tor/trunk/src/or/dns.c
   tor/trunk/src/or/eventdns.c
Log:
 r13070@catbus:  nickm | 2007-05-29 15:53:21 -0400
 Fix handling of resolves with very long or otherwise malformed addresses, and comment dns_resolve better, and stop making what should be a BUG warning into an assert(0).  This fixes bug 427, which was introduced around 9900/9931/9932.  Not a backport candidate: 0.1.2.x never had this bug.



Property changes on: tor/trunk
___________________________________________________________________
 svk:merge ticket from /tor/trunk [r13070] on 8246c3cf-6607-4228-993b-4d95d33730f1

Modified: tor/trunk/src/or/circuituse.c
===================================================================
--- tor/trunk/src/or/circuituse.c	2007-05-29 18:58:16 UTC (rev 10398)
+++ tor/trunk/src/or/circuituse.c	2007-05-29 19:54:51 UTC (rev 10399)
@@ -536,8 +536,9 @@
     }
   }
 
-  log_err(LD_BUG,"edge conn not in circuit's list?");
-  tor_assert(0); /* should never get here */
+  log_warn(LD_BUG,"Edge connection not in circuit's list.");
+  /* Don't give an error here; it's harmless. */
+  // tor_fragile_assert();
 }
 
 /** Find each circuit that has been unused for too long, or dirty

Modified: tor/trunk/src/or/dns.c
===================================================================
--- tor/trunk/src/or/dns.c	2007-05-29 18:58:16 UTC (rev 10398)
+++ tor/trunk/src/or/dns.c	2007-05-29 19:54:51 UTC (rev 10399)
@@ -536,30 +536,42 @@
   r = dns_resolve_impl(exitconn, is_resolve, oncirc, &hostname);
   switch (r) {
     case 1:
+      /* We got an answer without a lookup.  (Either the answer was
+       * cached, or it was obvious (like an IP address).)*/
       if (is_resolve) {
+        /* Send the answer back right now, and detach. */
         if (hostname)
           send_resolved_hostname_cell(exitconn, hostname);
         else
           send_resolved_cell(exitconn, RESOLVED_TYPE_IPV4);
         exitconn->on_circuit = NULL;
       } else {
+        /* Add to the n_streams list; the calling function will send back a
+         * connected cell. */
         exitconn->next_stream = oncirc->n_streams;
         oncirc->n_streams = exitconn;
       }
       break;
     case 0:
-      /* add it into the linked list of resolving_streams on this circuit */
+      /* The request is pending: add the connection into the linked list of
+       * resolving_streams on this circuit. */
       exitconn->_base.state = EXIT_CONN_STATE_RESOLVING;
       exitconn->next_stream = oncirc->resolving_streams;
       oncirc->resolving_streams = exitconn;
       break;
     case -2:
     case -1:
+      /* The request failed before it could start: cancel this connection,
+       * and stop everybody waiting forthe same connection. */
       if (is_resolve) {
         send_resolved_cell(exitconn,
              (r == -1) ? RESOLVED_TYPE_ERROR : RESOLVED_TYPE_ERROR_TRANSIENT);
       }
+
       exitconn->on_circuit = NULL;
+
+      dns_cancel_pending_resolve(exitconn->_base.address);
+
       if (!exitconn->_base.marked_for_close) {
         connection_free(TO_CONN(exitconn));
         //XXX020 ... and we just leak exitconn otherwise? -RD
@@ -838,6 +850,7 @@
     assert_connection_ok(TO_CONN(pendconn), 0);
     tor_assert(pendconn->_base.s == -1);
     if (!pendconn->_base.marked_for_close) {
+      /* XXXX020 RESOURCELIMIT?  Not RESOLVEFAILED??? */
       connection_edge_end(pendconn, END_STREAM_REASON_RESOURCELIMIT);
     }
     circ = circuit_get_by_edge_conn(pendconn);
@@ -1247,8 +1260,8 @@
     log_warn(LD_EXIT, "eventdns rejected address %s: error %d.",
              escaped_safe_str(addr), r);
     r = evdns_err_is_transient(r) ? -2 : -1;
-    dns_cancel_pending_resolve(addr); /* also sends end and frees */
-    tor_free(addr);
+    tor_free(addr); /* There is no evdns request in progress; stop
+                     * addr from getting leaked. */
   }
   return r;
 }

Modified: tor/trunk/src/or/eventdns.c
===================================================================
--- tor/trunk/src/or/eventdns.c	2007-05-29 18:58:16 UTC (rev 10398)
+++ tor/trunk/src/or/eventdns.c	2007-05-29 19:54:51 UTC (rev 10399)
@@ -2658,14 +2658,23 @@
 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
 
 	char *const first_token = strtok_r(start, delims, &strtok_state);
-	if (!first_token) return;
+	if (!first_token) {
+		log(EVDNS_LOG_WARN,"No token.");
+		return;
+	}
 
+
+	log(EVDNS_LOG_WARN,"Token is %s; flags is %d", first_token, flags);
+
 	if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
 		const char *const nameserver = NEXT_TOKEN;
 		struct in_addr ina;
 
+		log(EVDNS_LOG_WARN,"Parsed nameserver %s", nameserver);
+
 		if (inet_aton(nameserver, &ina)) {
 			// address is valid
+			log(EVDNS_LOG_WARN,"Liked it.");
 			evdns_nameserver_add(ina.s_addr);
 		}
 	} else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {