Mail Box Parsing

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Parsing Mail box files

Say you save the source code in the current directory (or elsewhere in your PackagePath) as mboxparser.lua. In your code, put:

parse = require "mboxparser" 

The main function, parse.mbox, receives the mailbox file contents as a string and returns a table with one entry per message. Each entry has the following structure:

message = {

    headers = {

        [["name_1"]] = "value_1",

        [["name_2"]] = "value_2",

        ...           ...

        [["name_n"]] = "value_n",

    },

    body = "message body"

}

	

Therefore, if a mailbox has the following contents:

From  whoever@tecgraf.puc-rio.br  Thu Nov 22 13:59:05 2001

Date: Thu, 22 Nov 2001 13:59:04 -0200 (EDT)

From: Whoever Smith <whoever@tecgraf.puc-rio.br>

To: Other Smith <other@tecgraf.puc-rio.br>

Subject: This is a test message

Content-Type: TEXT/PLAIN; charset=US-ASCII



Hi, This is the message body.  Regards, Diego.

	

Calling parse.mbox on it would return the following table:

messages = {

  { 

    headers = {

      from = "Whoever Smith <whoever@tecgraf.puc-rio.br>", 

      subject = "This is a test message", 

      to = "Other Smith <other@tecgraf.puc-rio.br>", 

      date = "Thu, 22 Nov 2001 13:59:04 -0200 (EDT)", 

      ["content-type"] = "TEXT/PLAIN; charset=US-ASCII", 

    }, 

    body = "Hi, This is the message body.  Regards, Diego.",

  }

}

	

Source Code

local Public = {}

local strfind, strlower, gsub = string.find, string.lower, string.gsub

local strsub, tinsert = string.sub, table.insert



function Public.headers(headers_s)

    local headers = {}

    headers_s = "\n" .. headers_s .. "$$$:\n"

    local i, j = 1, 1

    local name, value, _

    while 1 do

        j = strfind(headers_s, "\n%S-:", i+1)

        if not j then break end

        _, _, name, value = strfind(strsub(headers_s, i+1, j-1), "(%S-):(.*)")

        value = gsub(value or "", "\r\n", "\n")

        value = gsub(value, "\n%s*", " ")

        name = strlower(name)

        if headers[name] then headers[name] = headers[name] .. ", " ..  value

        else headers[name] = value end

        i, j = j, i

    end

    headers["$$$"] = nil

    return headers

end



function Public.message(message_s)

    message_s = gsub(message_s, "^.-\n", "")

    local _, headers_s, body

    _, _, headers_s, body = strfind(message_s, "^(.-\n)\n(.*)")

    headers_s = headers_s or ""

    body = body or ""

    return { headers = Public.headers(headers_s), body = body }

end



function Public.mbox(mbox_s)

    local mbox = {}

    mbox_s = "\n" .. mbox_s .. "\nFrom "

    local i, j = 1, 1

    while 1 do

        j = strfind(mbox_s, "\nFrom ", i + 1)

        if not j then break end

        tinsert(mbox, Public.message(strsub(mbox_s, i + 1, j - 1)))

        i, j = j, i

    end

    return mbox

end



return Public

	

Credits

The original Lua 4 code was created by DiegoNehab, and is used to test the LuaSocket[1] 1.4 SMTP code. The Lua 5 version was made by DirkLaurie.