Parsing Protocol Standards to Parse Standard Protocols

Abstract

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Investigating Automatic Code Generation for Network Packet Parsing

“…In previous work, we have proposed structured specification techniques that do integrate with the standardisation process [2]. Such techniques include specification languages that are structured to be familiar to those developing protocol standards, and tooling that can be used to generate parser code directly from standards documents.…”

“…The expressivity of the protocol data description language determines the set of message formats that can be described, while the code generator determines the architecture, paradigm, and language of the parser code. Accordingly, we consider the code generation functionality of our Network Packet Representation [2], and highlight those features of the representation that assist standards authors in writing clear, unambiguous specifications that generate wellformed code that is easy to reason about. We demonstrate the specification of the TCP packet format, show how its Network Packet Representation is derived and how code can then be generated from this representation.…”

“…Unlocking the benefits of machine-readability and code generation for these languages is best achieved by a common framework that enables the ease-of-use that ad-hoc formats bring, but that enforces the rigour that is required. In prior work, we developed the Network Packet Representation [2], a type system for protocol data, that aims to bridge the gap between the requirements of the standards community, for flexible languages that don't alter the process, with the benefits that come from formal protocol descriptions. As shown in Figure 1, this has been developed to support multiple input protocol description languages, and to generate parser implementations in a range of output programming languages, to give flexibility of input syntax with a rigorous type system and code generation.…”

“…Protocol description languages must be su ciently well defined so that the documents that use them can be parsed, yet must be su ciently flexible and expressive. Further, they must be human readable, usable by those with expertise in protocol design rather than formal methods, and support the consensus-based, discussion heavy, nature of the standardisation process [2]. The design and ...…”

“…Fields in Struct types are associated with optional expressions that constrain their size or value dependent on other fields. The type system is described in more detail in [2]. The Network Packet Representation encodes the protocol data units, and contextual information needed to parse those PDUs, in a strongly typed hierarchical data structure.…”