From a89852636cec9c2037b6dde8f0dffea61f2cda5c Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Wed, 17 Dec 2008 13:14:54 +0000
Subject: [PATCH] Backport r17139: Fix another case of refusing to use a chosen
 exit node because we think it will reject _mostly_ everything.  Based on
 patch from rovv.  See bug 752.

svn:r17640
---
 ChangeLog           |  3 +++
 doc/TODO.020        |  2 +-
 src/or/circuituse.c | 43 ++++++++++++++++++++++++++++++++-----------
 3 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 37c68561d..3d8e10434 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -34,6 +34,9 @@ Changes in version 0.2.0.33 - 200?-??-??
     - 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.)
+    - Fix another case of assuming, when a specific exit is requested,
+      that we know more than the user about what hosts it allows.
+      Fixes one case of bug 752.  Patch from rovv.
 
   o Minor features:
     - Report the case where all signatures in a detached set are rejected
diff --git a/doc/TODO.020 b/doc/TODO.020
index fcbd39a20..f532f9161 100644
--- a/doc/TODO.020
+++ b/doc/TODO.020
@@ -18,7 +18,7 @@ Backport for 0.2.0 once better tested:
     o ... 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.
+  o r17139: Fix another case of overriding .exit choices.
   - r17162 and r17164: fix another case of not checking cpath_layer.
   - r17208,r17209,r7211,r17212,r17214: Avoid gotterdammerung when an
     authority has an expired certificate.
diff --git a/src/or/circuituse.c b/src/or/circuituse.c
index 96a7e21ef..ea8224140 100644
--- a/src/or/circuituse.c
+++ b/src/or/circuituse.c
@@ -1015,17 +1015,38 @@ circuit_get_open_circ_or_launch(edge_connection_t *conn,
 
   /* Do we need to check exit policy? */
   if (check_exit_policy) {
-    struct in_addr in;
-    uint32_t addr = 0;
-    if (tor_inet_aton(conn->socks_request->address, &in))
-      addr = ntohl(in.s_addr);
-    if (router_exit_policy_all_routers_reject(addr, conn->socks_request->port,
-                                              need_uptime)) {
-      log_notice(LD_APP,
-                 "No Tor server exists that allows exit to %s:%d. Rejecting.",
-                 safe_str(conn->socks_request->address),
-                 conn->socks_request->port);
-      return -1;
+    if (!conn->chosen_exit_name) {
+      struct in_addr in;
+      uint32_t addr = 0;
+      if (tor_inet_aton(conn->socks_request->address, &in))
+        addr = ntohl(in.s_addr);
+      if (router_exit_policy_all_routers_reject(addr, conn->socks_request->port,
+                                                need_uptime)) {
+        log_notice(LD_APP,
+                   "No Tor server exists that allows exit to %s:%d. Rejecting.",
+                   safe_str(conn->socks_request->address),
+                   conn->socks_request->port);
+        return -1;
+      }
+    } else {
+      /* XXXX021 Duplicates checks in connection_ap_handshake_attach_circuit
+       * XXXX021 Fix this, then backport it? */
+      routerinfo_t *router = router_get_by_nickname(conn->chosen_exit_name, 1);
+      int opt = conn->_base.chosen_exit_optional;
+      if (router && !connection_ap_can_use_exit(conn, router)) {
+        log_fn(opt ? LOG_INFO : LOG_WARN, LD_APP,
+               "Requested exit point '%s' would refuse request. %s.",
+               conn->chosen_exit_name, opt ? "Trying others" : "Closing");
+        if (opt) {
+          conn->_base.chosen_exit_optional = 0;
+          tor_free(conn->chosen_exit_name);
+          /* Try again. */
+          return circuit_get_open_circ_or_launch(conn,
+                                                 desired_circuit_purpose,
+                                                 circp);
+        }
+        return -1;
+      }
     }
   }