weissi/httpparser

HTTP request/response parser for Swift 3

HTTP Parser - Swift 3

This is a parser for HTTP messages written in Swift 3. It parses both requests and responses. The parser is designed to be used in performance HTTP applications. It does not make any allocations, it does not buffer data and it can be interrupted at anytime.

This project was forked and ported from the 'C' http-parser project.

Features:

• No dependencies
• Handles persistent streams (keep-alive)
• Decodes chunked encoding
• Upgrade support
• Defends against buffer overflow attacks

The parser extracts the following information from HTTP messages:

• Header fields and values
• Content-Length
• Request method
• Response status code
• Transfer-Encoding
• HTTP version
• Request URL
• Message body

Swift Objectives

• Leverage the existing 'C' logic from http-parser
• Allow for http-parser.c changes to be easily ported in the future. As such:
  • Intentionally not adopting Swift naming guidelines
  • Keep all variable and function names the same
    • Only change public API's to be object oriented
  • Leave unnecessary markup in place such as:
    • End of case 'break'
    • Parenthesis in if statements

Performance

The Swift version is currently 1.4 times slower than the 'C' version. However the library is processing over 500,000 requests per second which should meet the requirements of most performance Swift applications.

Tests run with Release mode on a MacBook Air (MacBookAir6,2):

• http-parser - 'C' - 782K req/sec
• HTTPParser - Swift - 566K req/sec

Although all memory allocations have been optimized out there still are several retain/release calls which could be optimized. It would be ideal for an expert in the Xcode Instruments Time Profiler to review the library.

API Changes

http-parser	HTTPParser
struct http_parser	class http_parser
struct http_parser_settings	protocol http_parser_delegate
http_parser_version()	version()
http_parser_init()	reset()
http_parser_settings_init()	Use protocol above
http_parser_execute()	execute()
http_should_keep_alive()	should_keep_alive()
http_method_str()	method_str()
http_errno_name()	errno_name()
http_errno_description()	errno_description()
http_parser_pause()	pause()
http_body_is_final()	body_is_final()
http_parser_url_init()	Not ported - see below
http_parser_parse_url()	Not ported - see below

Testing

macOS

• Install Xcode 8.1
• run 'swift build --clean'
• run 'swift build'
• run 'swift test'

Linux

• Install Docker for Mac v1.12
• run 'docker-compose up'

To Do

• Finish porting unit tests (test.swift)
• Further Xcode Instruments Time Profiler review

URL Parsing

The URL parsing code from http-parser was not ported since Swift 3 applications can rely on the native URL class in Foundation.