From: James Morris <jmorris@namei.org>
Date: Mon, 2 Jun 2008 09:40:15 +1000 (EST)

On Sat, 31 May 2008, Adam Langley wrote:

quoted

When MD5 signatures are turned on we can end up with syntactically invalid
packets with a header length < 20 bytes. This is because tcp_header_size
overflows with 12 bytes of timestamp, 20 bytes of signature and > 8 bytes of
SACK option.

Since we can't fit any SACK blocks in the final 8 bytes of options space, and
the MD5 signature is more important, we disable including SACK, or even
advertising it, when MD5 is enabled.

Signed-off-by: Adam Langley <redacted>

Reviewed-by: James Morris <jmorris@namei.org>

After making some minor coding style fixups, I applied this
fix, thanks everyone.