We present a foundationally verified implementation of a reliable communication library for asynchronous client-server communication, and a stack of formally verified components on top thereof. Our library is implemented in an OCaml-like language on top of UDP and features characteristic traits of existing protocols, such as a simple handshaking protocol, bidirectional channels, and retransmission/acknowledgement mechanisms. We verify the library in the Aneris distributed separation logic using a novel proof pattern---dubbed the session escrow pattern---based on the existing escrow proof pattern and the so-called dependent separation protocols, which hitherto have only been used in a non-distributed concurrent setting. We demonstrate how our specification of the reliable communication library simplifies formal reasoning about applications, such as a remote procedure call library, which we in turn use to verify a lazily replicated key-value store with leader-followers and clients thereof. Our development is highly modular---each component is verified relative to specifications of the components it uses (not the implementation). All our results are formalized in the Coq proof assistant.

@article{paperbot1924,
  title = {Verifying Reliable Network Components in a Distributed Separation Logic with Dependent Separation Protocols},
  author = {Léon Gondelman and Jonas Kastberg Hinrichsen and Mário Pereira and Amin Timany and Lars Birkedal},
  journal = {Proceedings of the ACM on Programming Languages},
  volume = {7},
  number = {ICFP},
  year = {2023},
  doi = {10.1145/3607859}
}