From 2bcb081cb1d788b46d5ce86e085549fe5b1d3b81 Mon Sep 17 00:00:00 2001
From: Roger Dingledine <arma@torproject.org>
Date: Sun, 30 Jul 2006 04:32:58 +0000
Subject: defense in depth

svn:r6939
---
 src/or/circuitbuild.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'src/or/circuitbuild.c')

diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c
index d2973203a..fa5da30c4 100644
--- a/src/or/circuitbuild.c
+++ b/src/or/circuitbuild.c
@@ -625,11 +625,17 @@ circuit_extend(cell_t *cell, circuit_t *circ)
   char *id_digest=NULL;
 
   if (circ->n_conn) {
-    log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,
+    log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
            "n_conn already set. Bug/attack. Closing.");
     return -1;
   }
 
+  if (!server_mode(get_options())) {
+    log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
+           "Got an extend cell, but running as a client. Closing.");
+    return -1;
+  }
+
   relay_header_unpack(&rh, cell->payload);
 
   if (rh.length < 4+2+ONIONSKIN_CHALLENGE_LEN+DIGEST_LEN) {
-- 
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