Object RE2

A precompiled Google RE2 regex from C++ land that can be used from your Lua scripts.

TIP if you are just working with simple regexes then it is better to use the built in LuaJIT functions. The performance gains may not be enough to justify crossing the Lua-C boundary. This works best with complex or large numbers of regexes that are called at a low frequency.

Functions

A summary of the functions available in this object.

Creation

You need to use the T.re2 method to create a precompiled regex object. After the creation, you can invoke the following function to run the matches.

Functions

Name	In	Out	Description
partial_match	string	bool	Does the regex match anywhere in the input string
full_match	string	bool	Full input string must match the regex
partial_match_c1	string	bool, string	Match input string with 1 capture. If matched, return true + captured string Example (Host.*)\\s*: will pull the match in paranthesis into a string. If not matched, return false, nil.
partial_match_c2	string	bool, string, string	Same as partial_match_c1 but extract TWO captures rather than one.
partial_match_n	string	bool, string1..stringN	Partial match returns variable number of strings, you are expected to know how many captures are there
full_match_n	string	bool, string1..stringN	Full input string must match the regex. Returns N-capture strings

More will be added as required.

Example

Here is an example usage of RE2 parsing HTTP headers. You create a precompiled RE2 once in onload(..) then use it in your code.

onload = function()

    T.re2_http_request = T.re2("(GET|POST|HEAD|OPTIONS|CONNECT)\\s(\\S+)\\sHTTP/\\d\\.\\d")
    T.re2_connect=T.re2("CONNECT\\s(\\S+):(\\d+)")

  end,

  -- reassembly_handler block
  -- 
  reassembly_handler   = {


    onpayload = function(engine, timestamp, flowkey, direction, seekpos, buffer) 

        -- Using RE2 
        local match,c1,c2 = T.re2_http_request:partial_match_n(buffstr:tostring())

        print("Method="..c1)
        print("URL="..c2)