Compression and empty blocks

[pjbakker]

It seems socat likes to send empty blocks which causes zlib to punt.

To reproduce, run this on a test-server:

socat OPENSSL-LISTEN:5555,verify=0,key=test.key,cert=test.crt STDOUT

Connect to this with a polarssl client. Sending from polar to socat works fine. Just hitting enter on the socat end will make the connection fail on the PolarSSL side with a compression error.

I tracked that down to ssl_decompress_buf() being called with an empty block.
The zlib will return an error in that case.

Putting

if( !len_pre ) return ( 0 );

near the top of ssl_compress_buf() and ssl_decompress_buf() fixes that.

Versions:

• client: PolarSSL 1.2.7 with zlib 1.2.8
• server: socat 1.7.1.3 with openssl 1.0.0e-2ubuntu4.7

[pjbakker]

Fixed in development / 1.3 branch in abf2f8f