Backport r17091: when we have no pending streams, choose exits with choose_good_exit_server_general rather than with circuit_get_unhandled_ports().

svn:r17637

ChangeLog

@@ -31,6 +31,9 @@ Changes in version 0.2.0.33 - 200?-??-??
       until one succeeds.  Fixes bug 691.
     - Use 64 bits instead of 32 bits for connection identifiers used with
       the controller protocol, to greatly reduce risk of identifier reuse.
+    - When we're choosing an exit node for a circuit, and we have no pending
+      streams, choose a good general exit rather than one that supports "all
+      the pending streams".  Bugfix on 0.1.1.x. (Fix by rovv.)
 
   o Minor features:
     - Report the case where all signatures in a detached set are rejected

doc/TODO.020

@@ -12,8 +12,10 @@ Backport for 0.2.0 once better tested:
             approach). (Also maybe r16674)
     [Partially backported.  Instead of the basic name checking, I backported
      r17171 instead, to be even more resistant to poisoning.]
-  - r17091: distinguish "no routers support pending circuits" from
-            "no circuits are pending." See also r17181 and r17184.
+  o r17091: distinguish "no routers support pending circuits" from
+            "no circuits are pending."
+    - See also r17181...
+    - ... and r17184.
   - r17137: send END cell in response to connect to nonexistent hidserv port.
   - r17138: reject *:* servers should never do DNS lookups.
   - r17139: Fix another case of overriding .exit choices.

src/or/circuitbuild.c

@@ -1255,6 +1255,11 @@ choose_good_exit_server_general(routerlist_t *dir, int need_uptime,
 //               router->nickname, i);
       }
     }); /* End looping over connections. */
+    if (n_pending_connections > 0 && n_supported[i] == 0) {
+      /* Leave best_support at -1 if that's where it is, so we can
+       * distinguish it later. */
+      continue;
+    }
     if (n_supported[i] > best_support) {
       /* If this router is better than previous ones, remember its index
        * and goodness, and start counting how many routers are this good. */