HILTI and Spicy
HILTI provides an abstract machine model that caters specifically to the networking domain, directly supporting the field's common abstractions and idioms in its instruction set. It comes with compiler toolchain, built on top of LLVM, that turns HILTI programs into optimized, natively executable code just in time.
Spicy is a next-generation parser generator, built on top of HILTI, that makes it easy to build parsers for network protocols, file formats, and more. Spicy is more than just a "yacc for protocols": it's an all-in-one system that enables developers to write attributed grammars defining both syntax and semantics of an input format inside a single comprehensive scripting langauage.
See their home page for more information.