tokio-quiche: drain coalesced QUIC packets on recv

[babasha]

quiche::Connection::recv only processes one QUIC packet per call, but a single UDP datagram can contain several coalesced packets (a server commonly coalesces Initial + Handshake, and loopback MTU=65536 makes this common in local tests). The existing call sites in ClientConnector and IoWorker invoked recv once per buffer, so any packet coalesced after the first was silently discarded -- handshakes stall waiting for a Handshake-level frame that was already delivered.

Introduce a recv_coalesced helper at each call site that loops over conn.recv until it returns Done, advancing the buffer by the number of bytes quiche consumed.

[LPardue]

quiche's recv() handles coalesced packets, as noted in https://github.com/cloudflare/quiche/blob/master/quiche/src/lib.rs#L2819. Therefore, I don't understand what problem is being addressed

[antoniovicente]

quiche's recv() handles coalesced packets, as noted in https://github.com/cloudflare/quiche/blob/master/quiche/src/lib.rs#L2819. Therefore, I don't understand what problem is being addressed

Some evidence of it being handled correctly: If you look at the recv() implementation, you'll notice that the 2 cases that return Ok() should return a number of bytes equal to buf.len() since done should equal len when left == 0