Grammar-based SIP parser implementation with performance optimizations

In the paper we present a parser for the Session Initiation Protocol (SIP), a protocol that is a part of the 3GPP´s IP Multimedia System (IMS) framework. The parser is generated by a specially designed parser generator that as an input takes an Augmented Backus Naur Form (ABNF) grammar. This type of grammar is commonly used for formal protocol syntax definitions and is used in the SIP standard. We describe in detail issues and solutions for creating parser generator that can handle ambiguous, nondeterministic grammars as the one of SIP. We show that the generated parser has performance levels comparable to widely available hand-written open-source parsers and is superior when it comes to compliance to formal SIP syntax definitions.