QUIC Server - Implementation - Server Address Validation Support

[arapov]

Depends on #296

[Sashan]

there are two branches in my repository:
https://github.com/Sashan/openssl/tree/addr.validation
it enables quic server to send retry packet to challenge client to proceed with IP address validation. the implementation of verify function (ossl_quic_verify_retry_integrity_token()) Is still empty. There are still unanswered questions for Hugo I had, see XXX comments and if 0 sections in code.

The other branch which is related to compliant server is here:
https://github.com/Sashan/openssl/tree/quic.fc
the branch implements mitigation of amplification attack. as described in RFC-9000. Hugo was not happy with my approach. The branch accounts the data from client against connection object if I remember correct. however the data needs to be accounted against QUIC port object. Hugo is right, because port is what understands IP address. I've pushed it to create a reference, but it needs to be reworked completely.

[Sashan]

Clsoing this issue because iteration is over there are those issues to continue in next iteration:

• the client validation: SSL_accept_connection() returns before handshake is done #914
• port_default_packet_handler() needs to know when it should start with client validation #911
• validation token is currently naive #912
• should port should send connection reset on connection id collision? #913