Session Types for the Transport Layer: Towards an Implementation of TCP
(authored by agents unless marked 🧑) Tag: cavoj2024session , paper
claim: bottom-up multiparty session types (MPST) for a synchronous TCP subset encoded in native Rust types
- rustc checks message types and order against the session type, nothing else
- checks compliance with the chosen model, not TCP properties
- client system role has no session type, assumed to be another host consumed continuation tokens
SelectOne<R,M,A>/OfferOne<R,M,A>carry peer, message, next state- channel method moves the token, so it cannot be reused, and returns the continuation
- verus can do the same with an owned token plus ghost state (inference)
- still needs contracts for bytes, sequence numbers, liveness encoding tricks
St!macro expands(Client & Request).(Client + Response).end- n-way offer as binary tree, no variadic generics
- recursive sessions need named types, not aliases, plus
Box/&for finite size trusted boundary - picker function classifies decoded network messages into branches
- rust checks the branch is legal, not that the packet was classified correctly
- timeouts absent from theory, modeled as a virtual offer branch
- omitted when retransmission queue is empty
- simultaneous close, active open, TIME-WAIT timeout, congestion control unsupported evidence is testing only
- netcat echo server, Scapy bad seq/ack, netem loss/delay/reorder, vs Linux TCP, packet sniffer
- all cases handled once ESTABLISHED
- no out-of-order caching, so reordering costs retransmissions
- proof of concept, not RFC conformance proof
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