814645f42f
As revealed by some traces provided by @gabrieltz in GH #1903 issue, there are clients (chrome I guess) which acknowledge only one packet among others in the same datagram. This is the case for the first datagram sent by a QUIC haproxy listener made an Initial packet followed by an Handshake one. In this identified case, this is the Handshake packet only which is acknowledged. But if the client is able to respond with an Handshake packet (ACK frame) this is because it has successfully parsed the Initial packet. So, why not also acknowledging it? AFAIK, this is mandatory. On our side, when restransmitting this datagram, the Handshake packet was accessed from the Initial packet after having being released. Anyway. There is an issue on our side. Obviously, we must not expect an implementation to respect the RFC especially when it want to build an attack ;) With this simple patch for each TX packet we send, we also set the previous one in addition to the next one. When a packet is acknowledged, we detach the next one and the next one in the same datagram from this packet, so that it cannot be resent when resending these packets (the previous one, in our case). Thank you to @gabrieltz for having reported this issue. Must be backported to 2.6.