commit a70366317d898e800a3d8e2a59be4fa91cd8b4b3
author Paul Bakker <p.j.bakker@polarssl.org> Wed Apr 30 10:15:38 2014 +0200
committer Paul Bakker <p.j.bakker@polarssl.org> Wed Apr 30 10:16:16 2014 +0200
tree a806153cdc9b876aab77417d4ad27b049f5f75be
parent c73079a78cd0a028375b5d0da4a0d471394278c3

Improve interop by not writing ext_len in ClientHello / ServerHello when 0

The RFC also indicates that without any extensions, we should write a
struct {} (empty) not an array of length zero.

library/ssl_cli.c

diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 0a69f4d..cd0d8c2 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -651,9 +651,12 @@
     SSL_DEBUG_MSG( 3, ( "client hello, total extension length: %d",
                    ext_len ) );
 
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
-    p += ext_len;
+    if( ext_len > 0 )
+    {
+        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
+        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+        p += ext_len;
+    }
 
     ssl->out_msglen  = p - buf;
     ssl->out_msgtype = SSL_MSG_HANDSHAKE;