OpenSSL: add support for the TLS padding extension.

openssl/patches/paddingext.patch

+From 61a9671951205d66382556b2502993ffc9201f59 Mon Sep 17 00:00:00 2001
+From: Adam Langley <agl@chromium.org>
+Date: Wed, 11 Dec 2013 16:25:17 -0500
+Subject: [PATCH 57/57] Add padding extension.
+
+This change adds a padding extension, when needed, in order to work
+around bugs in F5 terminators.
+---
+ ssl/t1_lib.c | 20 ++++++++++++++++++++
+ ssl/tls1.h   |  4 ++++
+ 2 files changed, 24 insertions(+)
+
+diff --git a/ssl/s23_clnt.c b/ssl/s23_clnt.c
+index 47673e7..94e9692 100644
+--- a/ssl/s23_clnt.c
++++ b/ssl/s23_clnt.c
+@@ -466,7 +466,10 @@ static int ssl23_client_hello(SSL *s)
+                        {
+                        /* create Client Hello in SSL 3.0/TLS 1.0 format */
+ 
+-                       /* do the record header (5 bytes) and handshake message header (4 bytes) last */
++                       /* do the record header (5 bytes) and handshake message
++                        * header (4 bytes) last. Note: the code to add the
++                        * padding extension in t1_lib.c depends on the size of
++                        * this prefix. */
+                        d = p = &(buf[9]);
+                        
+                        *(p++) = version_major;
+diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
+index a657360..faa8d36 100644
+--- a/ssl/s3_clnt.c
++++ b/ssl/s3_clnt.c
+@@ -752,7 +752,9 @@ int ssl3_client_hello(SSL *s)
+                if (RAND_pseudo_bytes(p,SSL3_RANDOM_SIZE-4) <= 0)
+                        goto err;
+ 
+-               /* Do the message type and length last */
++               /* Do the message type and length last.
++                * Note: the code to add the padding extension in t1_lib.c
++                * depends on the size of this prefix. */
+                d=p= &(buf[4]);
+ 
+                /* version indicates the negotiated version: for example from
+diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
+index 5578056..f9ad9d9 100644
+--- a/ssl/t1_lib.c
++++ b/ssl/t1_lib.c
+@@ -695,6 +695,31 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha
+                 }
+ #endif
+ 
++       /* Add padding to workaround bugs in F5 terminators.
++        * See https://tools.ietf.org/html/draft-agl-tls-padding-02 */
++       {
++       int hlen = ret - (unsigned char *)s->init_buf->data;
++       /* The code in s23_clnt.c to build ClientHello messages includes the
++        * 5-byte record header in the buffer, while the code in s3_clnt.c does
++        * not. */
++       if (s->state == SSL23_ST_CW_CLNT_HELLO_A)
++               hlen -= 5;
++       if (hlen > 0xff && hlen < 0x200)
++               {
++               hlen = 0x200 - hlen;
++               if (hlen >= 4)
++                       hlen -= 4;
++               else
++                       hlen = 0;
++
++               s2n(TLSEXT_TYPE_padding, ret);
++               s2n(hlen, ret);
++               memset(ret, 0, hlen);
++               ret += hlen;
++               }
++       }
++
++
+        if ((extdatalen = ret-p-2)== 0) 
+                return p;
+ 
+diff --git a/ssl/tls1.h b/ssl/tls1.h
+index ecf5da7..df8f482 100644
+--- a/ssl/tls1.h
++++ b/ssl/tls1.h
+@@ -255,6 +255,10 @@ extern "C" {
+ #define TLSEXT_TYPE_channel_id                 30031
+ #define TLSEXT_TYPE_channel_id_new             30032
+ 
++/* See https://tools.ietf.org/html/draft-agl-tls-padding-02
++ * Number not yet IANA assigned. */
++#define TLSEXT_TYPE_padding                    35655
++
+ /* NameType value from RFC 3546 */
+ #define TLSEXT_NAMETYPE_host_name 0
+ /* status request value from RFC 3546 */
+-- 
+1.8.5.1