Statelessly listen for a new DTLS ClientHello and verify the cookie exchange.
>=1 when the handshake may continue (e.g. via SSL_accept), 0 to retry, or <0 on fatal error.
| Name | Description |
|---|---|
| s | Newly allocated SSL with read/write BIOs set (typically an unconnected datagram BIO). |
| client | Receives the peer address when a verified ClientHello is accepted. |