Set TLS padding extension value.

Enable TLS padding extension using official value from:

http://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml

CHANGES

@@ -291,23 +291,13 @@
      to be resent. (CVE-2013-6450)
      [Steve Henson]
 
-  *) TLS pad extension: draft-agl-tls-padding-02
+  *) TLS pad extension: draft-agl-tls-padding-03
 
      Workaround for the "TLS hang bug" (see FAQ and PR#2771): if the
      TLS client Hello record length value would otherwise be > 255 and
      less that 512 pad with a dummy extension containing zeroes so it
      is at least 512 bytes long.
 
-     To enable it use an unused extension number (for example chrome uses
-     35655) using:
-
-     e.g. -DTLSEXT_TYPE_padding=35655
-
-     Since the extension is ignored the actual number doesn't matter as long
-     as it doesn't clash with any existing extension.
-
-     This will be updated when the extension gets an official number.
-
      [Adam Langley, Steve Henson]
 
   *) Add functions to allocate and set the fields of an ECDSA_METHOD

ssl/t1_lib.c

@@ -1510,7 +1510,7 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha
 #endif
 #ifdef TLSEXT_TYPE_padding
 	/* Add padding to workaround bugs in F5 terminators.
-	 * See https://tools.ietf.org/html/draft-agl-tls-padding-02
+	 * See https://tools.ietf.org/html/draft-agl-tls-padding-03
 	 *
 	 * NB: because this code works out the length of all existing
 	 * extensions it MUST always appear last.

ssl/tls1.h

@@ -238,6 +238,12 @@ extern "C" {
 /* ExtensionType value from draft-ietf-tls-applayerprotoneg-00 */
 #define TLSEXT_TYPE_application_layer_protocol_negotiation 16
 
+/* ExtensionType value for TLS padding extension.
+ * http://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml
+ * http://tools.ietf.org/html/draft-agl-tls-padding-03
+ */
+#define TLSEXT_TYPE_padding	21
+
 /* ExtensionType value from RFC4507 */
 #define TLSEXT_TYPE_session_ticket		35