What is the difference between Openssl's BIO wrappers and SSL calls?

Question

I have long been confused if using the BIO_* way would have obvious advantage over the raw SSL_* calls.

I always use the non-bio as I thought I have more control.

Answer 1

BIO drives me up the wall but it allows you to transparently put in compression and other filters. You do want compression since it 1) makes cryptanalysis harder, 2) uses less bandwidth and 3) takes less CPU to compress + encrypt than to encrypt the raw data stream.