> For extra fun, openssl itself doesn't fully support renegotiation on duplex connections ...

The necessitated modification to the application protocol on that thread sounds like an OpenSSL cop-out. There is no good reason that OpenSSL shouldn't be able to cache incoming application data during the client-initiated handshake just as it does at other times. It should be able to cache the incoming pre-negotiation records, decoding them. The pending() check would inform the client that they need to reap the incoming data during the handshake too.