Current design of the peer protocol handshake limits alternative implementations in languages other than C/C++ as described in this article. Indeed, src/ripple/overlay/README.md refers to the current implementation rather than describing the protocol:

* `Session-Signature`

    This field must be present. It contains a cryptographic token formed
    from the SHA512 hash of the shared data exchanged during SSL handshaking.
    For more details see the corresponding source code.

apparently referring to lines 31-93 in src/ripple/overlay/impl/TMHello.cpp.

OpenSSL routines SSL_get_finished and SSL_get_peer_finished are being used to access Finished messages sent over the socket which violates TLS socket transparency. These low-lever routines are only available in C/C++ for a reason.

Requesting protocol upgrade to RTXP/1.3 with Session-Signature (HTTP header) and nodeproof (the corresponding field of the Hello message in protobuf protocol) replaced by a more portable mechanism which would not be language-specific and could be implemented in other programming languages, for example using Node.js.