Rework logic of TDS SSL Pre-login Handshake (babelfish-for-postgresql…

…#1453) (babelfish-for-postgresql#1477)

This commit rewrites the logic of SSL prelogin handshake read. Previously, whatever segments we were reading from the SSL prelogin handshake packet, if the first byte started with TDS_PRELOGIN, then we assumed that the segment is actually the first segment of the SSL handshake packet from the client containing the TDS prelogin header.

This assumption is incorrect. It is possible that the segment being read by the SSL Handshake read method might not contain the TDS prelogin header but still has its first byte as TDS_PRELOGIN. There is no restriction on this for the encrypted handshake message.

We rewrite this logic to check for the TDS prelogin header only if we have fully read the entire previous SSL handshake packet from client or if this is actually the very first SSL packet from client (client hello).

Task: BABEL-4096
Signed-off-by: Sharu Goel [email protected]

Fix crash when calling procedure with more than allowed parameters (b…

…abelfish-for-postgresql#1266) (babelfish-for-postgresql#1270) (babelfish-for-postgresql#1280)

Earlier, Inside is_exec_stmt_on_scalar_func function,  we were accessing the unallocated memory when number of args are greater than FUNC_MAX_ARGS due to which PG crashes with message 'stack smashing detected'  in the PG log. This commit adds a safety check to throw error in case of more than allowed arguments.

Task : BABEL-3984
Signed-off-by: Sumit Jaiswal <[email protected]>