Commit 8c6d8c2a authored by Dr. Stephen Henson's avatar Dr. Stephen Henson
Browse files

Backport TLS padding extension from master.

parent 53a8f8c2

CHANGES

+19 −0
Original line number Diff line number Diff line
@@ -4,6 +4,25 @@ 


 Changes between 1.0.1e and 1.0.2 [xx XXX xxxx]



  *) TLS pad extension: draft-agl-tls-padding-02



     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]



  *) Extended RSA OAEP support via EVP_PKEY API. Options to specify digest,

     MGF1 digest and OAEP label.

     [Steve Henson]

ssl/t1_lib.c

+30 −0
Original line number Diff line number Diff line
@@ -1502,6 +1502,36 @@ unsigned char *ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned cha 
			}

		}



#ifdef TLSEXT_TYPE_padding

	/* Add padding to workaround bugs in F5 terminators.

	 * See https://tools.ietf.org/html/draft-agl-tls-padding-02

	 *

	 * NB: because this code works out the length of all existing

	 * extensions it MUST always appear last.

	 */

	{

	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;

		}

	}

#endif



	if ((extdatalen = ret-p-2) == 0)

		return p;