Server Initial packets should not carry tokens

[josephnoir]

RFC 9000 says in Section 17.2.2 regarding token length:

"Initial packets sent by the server MUST set the Token Length field to 0; clients that receive an Initial packet with a non-zero Token Length field MUST either discard the packet or generate a connection error of type PROTOCOL_VIOLATION."

If I read the code correctly, the server might falsely include the issued retry token in the packet.

[rpaulo]

Isn't initialToken only set when we receive a retry? Don't we drop a RETRY from the client?

[agnosticdev]

Yeah, I think the issue here is that once the server receives the new initial packet and validates it in retryTokenPresent then it continues to hold onto it and so its send in the Packet.build function. You could destroy the token at that point because the packet and the token have been validated. This would probably make more sense. We will also need to change the unit tests in SwiftNetworkQUICRetryTokenTests to only validate the client token.