Recover better from TCP connections to Tor servers that are broken but

don't tell you (it happens!); and rotate TLS connections once a week.

1) If an OR conn becomes more than a week old, make it obsolete.
2) If it's obsolete and empty, kill it.
3) When an OR makes a second connection to you, allow it.
4) If we want to send a new create cell, but the best conn we've
   got is obsolete, and the router is 0.1.1.9-alpha-cvs or later, ask
   for a new conn instead.
5) When we time out on circuit building on the first hop, make that
   connection obsolete.


svn:r5429

1 files changed, 29 insertions, 9 deletions

diff --git a/src/or/connection.c b/src/or/connection.c
index b38f0daff7..88cbd9a676 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -1547,8 +1547,8 @@ connection_or_exact_get_by_addr_port(uint32_t addr, uint16_t port)
   return best;
 }
 
-/** Return a connection with give type, address, port, and purpose or NULL if
- * no such connection exists. */
+/** Return a connection with given type, address, port, and purpose;
+ * or NULL if no such connection exists. */
 connection_t *
 connection_get_by_type_addr_port_purpose(int type, uint32_t addr, uint16_t port,
                                          int purpose)
@@ -1570,22 +1570,42 @@ connection_get_by_type_addr_port_purpose(int type, uint32_t addr, uint16_t port,
   return NULL;
 }
 
+/** Return the best connection of type OR with the
+ * digest <b>digest</b> that we have, or NULL if we have none.
+ *
+ * 1) Don't return it if it's marked for close.
+ * 2) If there are any open conns, ignore non-open conns.
+ * 3) If there are any non-obsolete conns, ignore obsolete conns.
+ * 4) Then if there are any non-empty conns, ignore empty conns.
+ * 5) Of the remaining conns, prefer newer conns.
+ */
 connection_t *
-connection_get_by_identity_digest(const char *digest, int type)
+connection_get_by_identity_digest(const char *digest)
 {
-  int i, n;
+  int i, n, newer;
   connection_t *conn, *best=NULL;
   connection_t **carray;
 
   get_connection_array(&carray,&n);
   for (i=0;i<n;i++) {
     conn = carray[i];
-    if (conn->type != type)
+    if (conn->marked_for_close ||
+        memcmp(conn->identity_digest, digest, DIGEST_LEN))
       continue;
-    if (!memcmp(conn->identity_digest, digest, DIGEST_LEN) &&
-        !conn->marked_for_close &&
-        (!best || best->timestamp_created < conn->timestamp_created))
-      best = conn;
+    if (!best) {
+      best = conn; /* whatever it is, it's better than nothing. */
+      continue;
+    }
+    if (best->state == OR_CONN_STATE_OPEN &&
+        conn->state != OR_CONN_STATE_OPEN)
+      continue; /* avoid non-open conns if we can */
+    newer = best->timestamp_created < conn->timestamp_created;
+    if (conn->is_obsolete && (!best->is_obsolete || !newer))
+      continue; /* we have something, and it's better than this. */
+    if (circuit_get_by_conn(best) && !circuit_get_by_conn(conn))
+      continue; /* prefer conns with circuits on them */
+    if (newer)
+      best = conn; /* lastly, prefer newer conns */
   }
   return best;
 }