ssl_set_hostname was mostly useless, because it allowed setting host name of an existing SSL object. However SNI was sent as part of client_hello, which was done in ssl_client_new. So it wasn't possible to actually set host name before connection would start.
X509 context contains certificate fingerprint and various names which may be used to verify the certificate.
Previously we would free it right after the handshake completion, which prevented the client from actually using any information from X509 context.
Postponing this to the first ssl_read/ssl_write call after the handshake, we give the client a chance to verify the certificate.
Also added logging to ssl_match_fingerprint function in case fingerprint doesn't match expected value.
