rspamd/lualib/lua_mime.lua

--[[
Copyright (c) 2019, Vsevolod Stakhov <vsevolod@highsecure.ru>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
]]--

--[[[
-- @module lua_mime
-- This module contains helper functions to modify mime parts
--]]

local rspamd_util = require "rspamd_util"

local exports = {}

local function newline(task)
  local t = task:get_newlines_type()

  if t == 'cr' then
    return '\r'
  elseif t == 'lf' then
    return '\n'
  end

  return '\r\n'
end


--[[[
-- @function lua_mime.add_text_footer(task, html_footer, text_footer)
-- Adds a footer to all text parts in a message. It returns a table with the following
-- fields:
-- * out: new content (body only)
-- * need_rewrite_ct: boolean field that means if we must rewrite content type
-- * new_ct: new content type (type => string, subtype => string)
--]]
exports.add_text_footer = function(task, html_footer, text_footer)
  local newline_s = newline(task)
  local res = {}
  local out = {}
  local text_parts = task:get_text_parts()

  if not (html_footer or text_footer) or not (text_parts and #text_parts > 0) then
    return false
  end

  local function do_append_footer(part, footer, is_multipart)
    local tp = part:get_text()
    local ct = 'text/plain'
    local cte = 'quoted-printable'

    if tp:is_html() then
      ct = 'text/html'
    end

    if part:get_cte() == '7bit' then
      cte = '7bit'
    end

    if is_multipart then
      out[#out + 1] = string.format('Content-Type: %s; charset=utf-8%s'..
          'Content-Transfer-Encoding: %s',
          ct, newline_s, cte)
      out[#out + 1] = ''
    end

    local content = tostring(tp:get_content('raw_utf') or '')
    local double_nline = newline_s .. newline_s
    local nlen = #double_nline
    -- Hack, if part ends with 2 newline, then we append it after footer
    if content:sub(-(nlen), nlen + 1) == double_nline then
      content = string.format('%s%s',
          content:sub(-(#newline_s), #newline_s + 1), -- content without last newline
          footer)
      out[#out + 1] = {rspamd_util.encode_qp(content,
          80, task:get_newlines_type()), true}
      out[#out + 1] = ''
    else
      content = content .. footer
      out[#out + 1] = {rspamd_util.encode_qp(content,
          80, task:get_newlines_type()), true}
      out[#out + 1] = ''
    end

  end

  if html_footer or text_footer then
    -- We need to take extra care about content-type and cte
    local ct = task:get_header('Content-Type')
    if ct then
      ct = rspamd_util.parse_content_type(ct, task:get_mempool())
    end

    if ct then
      if ct.type and ct.type == 'text' then
        if ct.subtype then
          if html_footer and (ct.subtype == 'html' or ct.subtype == 'htm') then
            res.need_rewrite_ct = true
          elseif text_footer and ct.subtype == 'plain' then
            res.need_rewrite_ct = true
          end
        else
          if text_footer then
            res.need_rewrite_ct = true
          end
        end

        res.new_ct = ct
      end
    else

      if text_parts then

        if #text_parts == 1 then
          res.need_rewrite_ct = true
          res.new_ct = {
            type = 'text',
            subtype = 'plain'
          }
        elseif #text_parts > 1 then
          -- XXX: in fact, it cannot be
          res.new_ct = {
            type = 'multipart',
            subtype = 'mixed'
          }
        end
      end
    end
  end

  local boundaries = {}
  local cur_boundary

  for _,part in ipairs(task:get_parts()) do
    local boundary = part:get_boundary()
    if part:is_multipart() then
      if cur_boundary then
        out[#out + 1] = string.format('--%s',
            boundaries[#boundaries])
      end

      boundaries[#boundaries + 1] = boundary or '--XXX'
      cur_boundary = boundary

      local rh = part:get_raw_headers()
      if #rh > 0 then
        out[#out + 1] = {rh, true}
      end
    elseif part:is_message() then
      if boundary then
        if cur_boundary and boundary ~= cur_boundary then
          -- Need to close boundary
          out[#out + 1] = string.format('--%s--%s',
              boundaries[#boundaries], newline_s)
          table.remove(boundaries)
          cur_boundary = nil
        end
        out[#out + 1] = string.format('--%s',
            boundary)
      end

      out[#out + 1] = {part:get_raw_headers(), true}
    else
      local append_footer = false
      local skip_footer = part:is_attachment()

      local parent = part:get_parent()
      if parent then
        local t,st = parent:get_type()

        if t == 'multipart' and st == 'signed' then
          -- Do not modify signed parts
          skip_footer = true
        end
      end
      if text_footer and part:is_text() then
        local tp = part:get_text()

        if not tp:is_html() then
          append_footer = text_footer
        end
      end

      if html_footer and part:is_text() then
        local tp = part:get_text()

        if tp:is_html() then
          append_footer = html_footer
        end
      end

      if boundary then
        if cur_boundary and boundary ~= cur_boundary then
          -- Need to close boundary
          out[#out + 1] = string.format('--%s--%s',
              boundaries[#boundaries], newline_s)
          table.remove(boundaries)
          cur_boundary = boundary
        end
        out[#out + 1] = string.format('--%s',
            boundary)
      end

      if append_footer and not skip_footer then
        do_append_footer(part, append_footer,
            parent and parent:is_multipart())
      else
        out[#out + 1] = {part:get_raw_headers(), true}
        out[#out + 1] = {part:get_raw_content(), false}
      end
    end
  end

  -- Close remaining
  local b = table.remove(boundaries)
  while b do
    out[#out + 1] = string.format('--%s--', b)
    if #boundaries > 0 then
      out[#out + 1] = ''
    end
    b = table.remove(boundaries)
  end

  res.out = out

  return res
end

-- All mime extensions with corresponding content types
exports.full_extensions_map = {
  {"323", "text/h323"},
  {"3g2", "video/3gpp2"},
  {"3gp", "video/3gpp"},
  {"3gp2", "video/3gpp2"},
  {"3gpp", "video/3gpp"},
  {"7z", "application/x-7z-compressed"},
  {"aa", "audio/audible"},
  {"AAC", "audio/aac"},
  {"aaf", "application/octet-stream"},
  {"aax", "audio/vnd.audible.aax"},
  {"ac3", "audio/ac3"},
  {"aca", "application/octet-stream"},
  {"accda", "application/msaccess.addin"},
  {"accdb", "application/msaccess"},
  {"accdc", "application/msaccess.cab"},
  {"accde", "application/msaccess"},
  {"accdr", "application/msaccess.runtime"},
  {"accdt", "application/msaccess"},
  {"accdw", "application/msaccess.webapplication"},
  {"accft", "application/msaccess.ftemplate"},
  {"acx", "application/internet-property-stream"},
  {"AddIn", "text/xml"},
  {"ade", "application/msaccess"},
  {"adobebridge", "application/x-bridge-url"},
  {"adp", "application/msaccess"},
  {"ADT", "audio/vnd.dlna.adts"},
  {"ADTS", "audio/aac"},
  {"afm", "application/octet-stream"},
  {"ai", "application/postscript"},
  {"aif", "audio/aiff"},
  {"aifc", "audio/aiff"},
  {"aiff", "audio/aiff"},
  {"air", "application/vnd.adobe.air-application-installer-package+zip"},
  {"amc", "application/mpeg"},
  {"anx", "application/annodex"},
  {"apk", "application/vnd.android.package-archive" },
  {"application", "application/x-ms-application"},
  {"art", "image/x-jg"},
  {"asa", "application/xml"},
  {"asax", "application/xml"},
  {"ascx", "application/xml"},
  {"asd", "application/octet-stream"},
  {"asf", "video/x-ms-asf"},
  {"ashx", "application/xml"},
  {"asi", "application/octet-stream"},
  {"asm", "text/plain"},
  {"asmx", "application/xml"},
  {"aspx", "application/xml"},
  {"asr", "video/x-ms-asf"},
  {"asx", "video/x-ms-asf"},
  {"atom", "application/atom+xml"},
  {"au", "audio/basic"},
  {"avi", "video/x-msvideo"},
  {"axa", "audio/annodex"},
  {"axs", "application/olescript"},
  {"axv", "video/annodex"},
  {"bas", "text/plain"},
  {"bcpio", "application/x-bcpio"},
  {"bin", "application/octet-stream"},
  {"bmp", "image/bmp"},
  {"c", "text/plain"},
  {"cab", "application/octet-stream"},
  {"caf", "audio/x-caf"},
  {"calx", "application/vnd.ms-office.calx"},
  {"cat", "application/vnd.ms-pki.seccat"},
  {"cc", "text/plain"},
  {"cd", "text/plain"},
  {"cdda", "audio/aiff"},
  {"cdf", "application/x-cdf"},
  {"cer", "application/x-x509-ca-cert"},
  {"cfg", "text/plain"},
  {"chm", "application/octet-stream"},
  {"class", "application/x-java-applet"},
  {"clp", "application/x-msclip"},
  {"cmd", "text/plain"},
  {"cmx", "image/x-cmx"},
  {"cnf", "text/plain"},
  {"cod", "image/cis-cod"},
  {"config", "application/xml"},
  {"contact", "text/x-ms-contact"},
  {"coverage", "application/xml"},
  {"cpio", "application/x-cpio"},
  {"cpp", "text/plain"},
  {"crd", "application/x-mscardfile"},
  {"crl", "application/pkix-crl"},
  {"crt", "application/x-x509-ca-cert"},
  {"cs", "text/plain"},
  {"csdproj", "text/plain"},
  {"csh", "application/x-csh"},
  {"csproj", "text/plain"},
  {"css", "text/css"},
  {"csv", {"application/vnd.ms-excel", "text/csv", "text/plain"}},
  {"cur", "application/octet-stream"},
  {"cxx", "text/plain"},
  {"dat", {"application/octet-stream", "application/ms-tnef"}},
  {"datasource", "application/xml"},
  {"dbproj", "text/plain"},
  {"dcr", "application/x-director"},
  {"def", "text/plain"},
  {"deploy", "application/octet-stream"},
  {"der", "application/x-x509-ca-cert"},
  {"dgml", "application/xml"},
  {"dib", "image/bmp"},
  {"dif", "video/x-dv"},
  {"dir", "application/x-director"},
  {"disco", "text/xml"},
  {"divx", "video/divx"},
  {"dll", "application/x-msdownload"},
  {"dll.config", "text/xml"},
  {"dlm", "text/dlm"},
  {"doc", "application/msword"},
  {"docm", "application/vnd.ms-word.document.macroEnabled.12"},
  {"docx", {
    "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
    "application/msword",
    "application/vnd.ms-word.document.12",
    "application/octet-stream",
  }},
  {"dot", "application/msword"},
  {"dotm", "application/vnd.ms-word.template.macroEnabled.12"},
  {"dotx", "application/vnd.openxmlformats-officedocument.wordprocessingml.template"},
  {"dsp", "application/octet-stream"},
  {"dsw", "text/plain"},
  {"dtd", "text/xml"},
  {"dtsConfig", "text/xml"},
  {"dv", "video/x-dv"},
  {"dvi", "application/x-dvi"},
  {"dwf", "drawing/x-dwf"},
  {"dwg", {"application/acad", "image/vnd.dwg"}},
  {"dwp", "application/octet-stream"},
  {"dxf", "application/x-dxf" },
  {"dxr", "application/x-director"},
  {"eml", "message/rfc822"},
  {"emz", "application/octet-stream"},
  {"eot", "application/vnd.ms-fontobject"},
  {"eps", "application/postscript"},
  {"etl", "application/etl"},
  {"etx", "text/x-setext"},
  {"evy", "application/envoy"},
  {"exe", {
    "application/x-dosexec",
    "application/x-msdownload",
    "application/x-executable",
  }},
  {"exe.config", "text/xml"},
  {"fdf", "application/vnd.fdf"},
  {"fif", "application/fractals"},
  {"filters", "application/xml"},
  {"fla", "application/octet-stream"},
  {"flac", "audio/flac"},
  {"flr", "x-world/x-vrml"},
  {"flv", "video/x-flv"},
  {"fsscript", "application/fsharp-script"},
  {"fsx", "application/fsharp-script"},
  {"generictest", "application/xml"},
  {"gif", "image/gif"},
  {"gpx", "application/gpx+xml"},
  {"group", "text/x-ms-group"},
  {"gsm", "audio/x-gsm"},
  {"gtar", "application/x-gtar"},
  {"gz", {"application/gzip", "application/x-gzip"}},
  {"h", "text/plain"},
  {"hdf", "application/x-hdf"},
  {"hdml", "text/x-hdml"},
  {"hhc", "application/x-oleobject"},
  {"hhk", "application/octet-stream"},
  {"hhp", "application/octet-stream"},
  {"hlp", "application/winhlp"},
  {"hpp", "text/plain"},
  {"hqx", "application/mac-binhex40"},
  {"hta", "application/hta"},
  {"htc", "text/x-component"},
  {"htm", "text/html"},
  {"html", "text/html"},
  {"htt", "text/webviewhtml"},
  {"hxa", "application/xml"},
  {"hxc", "application/xml"},
  {"hxd", "application/octet-stream"},
  {"hxe", "application/xml"},
  {"hxf", "application/xml"},
  {"hxh", "application/octet-stream"},
  {"hxi", "application/octet-stream"},
  {"hxk", "application/xml"},
  {"hxq", "application/octet-stream"},
  {"hxr", "application/octet-stream"},
  {"hxs", "application/octet-stream"},
  {"hxt", "text/html"},
  {"hxv", "application/xml"},
  {"hxw", "application/octet-stream"},
  {"hxx", "text/plain"},
  {"i", "text/plain"},
  {"ico", "image/x-icon"},
  {"ics", {"text/calendar", "application/octet-stream"}},
  {"idl", "text/plain"},
  {"ief", "image/ief"},
  {"iii", "application/x-iphone"},
  {"inc", "text/plain"},
  {"inf", "application/octet-stream"},
  {"ini", "text/plain"},
  {"inl", "text/plain"},
  {"ins", "application/x-internet-signup"},
  {"ipa", "application/x-itunes-ipa"},
  {"ipg", "application/x-itunes-ipg"},
  {"ipproj", "text/plain"},
  {"ipsw", "application/x-itunes-ipsw"},
  {"iqy", "text/x-ms-iqy"},
  {"isp", "application/x-internet-signup"},
  {"ite", "application/x-itunes-ite"},
  {"itlp", "application/x-itunes-itlp"},
  {"itms", "application/x-itunes-itms"},
  {"itpc", "application/x-itunes-itpc"},
  {"IVF", "video/x-ivf"},
  {"jar", "application/java-archive"},
  {"java", "application/octet-stream"},
  {"jck", "application/liquidmotion"},
  {"jcz", "application/liquidmotion"},
  {"jfif", "image/pjpeg"},
  {"jnlp", "application/x-java-jnlp-file"},
  {"jpb", "application/octet-stream"},
  {"jpe", {"image/jpeg", "image/pjpeg"}},
  {"jpeg", {"image/jpeg", "image/pjpeg"}},
  {"jpg", {"image/jpeg", "image/pjpeg"}},
  {"js", "application/javascript"},
  {"json", "application/json"},
  {"jsx", "text/jscript"},
  {"jsxbin", "text/plain"},
  {"latex", "application/x-latex"},
  {"library-ms", "application/windows-library+xml"},
  {"lit", "application/x-ms-reader"},
  {"loadtest", "application/xml"},
  {"lpk", "application/octet-stream"},
  {"lsf", "video/x-la-asf"},
  {"lst", "text/plain"},
  {"lsx", "video/x-la-asf"},
  {"lzh", "application/octet-stream"},
  {"m13", "application/x-msmediaview"},
  {"m14", "application/x-msmediaview"},
  {"m1v", "video/mpeg"},
  {"m2t", "video/vnd.dlna.mpeg-tts"},
  {"m2ts", "video/vnd.dlna.mpeg-tts"},
  {"m2v", "video/mpeg"},
  {"m3u", "audio/x-mpegurl"},
  {"m3u8", "audio/x-mpegurl"},
  {"m4a", {"audio/m4a", "audio/x-m4a"}},
  {"m4b", "audio/m4b"},
  {"m4p", "audio/m4p"},
  {"m4r", "audio/x-m4r"},
  {"m4v", "video/x-m4v"},
  {"mac", "image/x-macpaint"},
  {"mak", "text/plain"},
  {"man", "application/x-troff-man"},
  {"manifest", "application/x-ms-manifest"},
  {"map", "text/plain"},
  {"master", "application/xml"},
  {"mbox", "application/mbox"},
  {"mda", "application/msaccess"},
  {"mdb", "application/x-msaccess"},
  {"mde", "application/msaccess"},
  {"mdp", "application/octet-stream"},
  {"me", "application/x-troff-me"},
  {"mfp", "application/x-shockwave-flash"},
  {"mht", "message/rfc822"},
  {"mhtml", "message/rfc822"},
  {"mid", "audio/mid"},
  {"midi", "audio/mid"},
  {"mix", "application/octet-stream"},
  {"mk", "text/plain"},
  {"mmf", "application/x-smaf"},
  {"mno", "text/xml"},
  {"mny", "application/x-msmoney"},
  {"mod", "video/mpeg"},
  {"mov", "video/quicktime"},
  {"movie", "video/x-sgi-movie"},
  {"mp2", "video/mpeg"},
  {"mp2v", "video/mpeg"},
  {"mp3", "audio/mpeg"},
  {"mp4", "video/mp4"},
  {"mp4v", "video/mp4"},
  {"mpa", "video/mpeg"},
  {"mpe", "video/mpeg"},
  {"mpeg", "video/mpeg"},
  {"mpf", "application/vnd.ms-mediapackage"},
  {"mpg", "video/mpeg"},
  {"mpp", "application/vnd.ms-project"},
  {"mpv2", "video/mpeg"},
  {"mqv", "video/quicktime"},
  {"ms", "application/x-troff-ms"},
  {"msg", "application/vnd.ms-outlook"},
  {"msi", {"application/x-msi", "application/octet-stream"}},
  {"mso", "application/octet-stream"},
  {"mts", "video/vnd.dlna.mpeg-tts"},
  {"mtx", "application/xml"},
  {"mvb", "application/x-msmediaview"},
  {"mvc", "application/x-miva-compiled"},
  {"mxp", "application/x-mmxp"},
  {"nc", "application/x-netcdf"},
  {"nsc", "video/x-ms-asf"},
  {"nws", "message/rfc822"},
  {"ocx", "application/octet-stream"},
  {"oda", "application/oda"},
  {"odb", "application/vnd.oasis.opendocument.database"},
  {"odc", "application/vnd.oasis.opendocument.chart"},
  {"odf", "application/vnd.oasis.opendocument.formula"},
  {"odg", "application/vnd.oasis.opendocument.graphics"},
  {"odh", "text/plain"},
  {"odi", "application/vnd.oasis.opendocument.image"},
  {"odl", "text/plain"},
  {"odm", "application/vnd.oasis.opendocument.text-master"},
  {"odp", "application/vnd.oasis.opendocument.presentation"},
  {"ods", "application/vnd.oasis.opendocument.spreadsheet"},
  {"odt", "application/vnd.oasis.opendocument.text"},
  {"oga", "audio/ogg"},
  {"ogg", "audio/ogg"},
  {"ogv", "video/ogg"},
  {"ogx", "application/ogg"},
  {"one", "application/onenote"},
  {"onea", "application/onenote"},
  {"onepkg", "application/onenote"},
  {"onetmp", "application/onenote"},
  {"onetoc", "application/onenote"},
  {"onetoc2", "application/onenote"},
  {"opus", "audio/ogg"},
  {"orderedtest", "application/xml"},
  {"osdx", "application/opensearchdescription+xml"},
  {"otf", "application/font-sfnt"},
  {"otg", "application/vnd.oasis.opendocument.graphics-template"},
  {"oth", "application/vnd.oasis.opendocument.text-web"},
  {"otp", "application/vnd.oasis.opendocument.presentation-template"},
  {"ots", "application/vnd.oasis.opendocument.spreadsheet-template"},
  {"ott", "application/vnd.oasis.opendocument.text-template"},
  {"oxt", "application/vnd.openofficeorg.extension"},
  {"p10", "application/pkcs10"},
  {"p12", "application/x-pkcs12"},
  {"p7b", "application/x-pkcs7-certificates"},
  {"p7c", "application/pkcs7-mime"},
  {"p7m", "application/pkcs7-mime"},
  {"p7r", "application/x-pkcs7-certreqresp"},
  {"p7s", {"application/pkcs7-signature", "text/plain"}},
  {"pbm", "image/x-portable-bitmap"},
  {"pcast", "application/x-podcast"},
  {"pct", "image/pict"},
  {"pcx", "application/octet-stream"},
  {"pcz", "application/octet-stream"},
  {"pdf", "application/pdf"},
  {"pfb", "application/octet-stream"},
  {"pfm", "application/octet-stream"},
  {"pfx", "application/x-pkcs12"},
  {"pgm", "image/x-portable-graymap"},
  {"pic", "image/pict"},
  {"pict", "image/pict"},
  {"pkgdef", "text/plain"},
  {"pkgundef", "text/plain"},
  {"pko", "application/vnd.ms-pki.pko"},
  {"pls", "audio/scpls"},
  {"pma", "application/x-perfmon"},
  {"pmc", "application/x-perfmon"},
  {"pml", "application/x-perfmon"},
  {"pmr", "application/x-perfmon"},
  {"pmw", "application/x-perfmon"},
  {"png", "image/png"},
  {"pnm", "image/x-portable-anymap"},
  {"pnt", "image/x-macpaint"},
  {"pntg", "image/x-macpaint"},
  {"pnz", "image/png"},
  {"pot", "application/vnd.ms-powerpoint"},
  {"potm", "application/vnd.ms-powerpoint.template.macroEnabled.12"},
  {"potx", "application/vnd.openxmlformats-officedocument.presentationml.template"},
  {"ppa", "application/vnd.ms-powerpoint"},
  {"ppam", "application/vnd.ms-powerpoint.addin.macroEnabled.12"},
  {"ppm", "image/x-portable-pixmap"},
  {"pps", "application/vnd.ms-powerpoint"},
  {"ppsm", "application/vnd.ms-powerpoint.slideshow.macroEnabled.12"},
  {"ppsx", "application/vnd.openxmlformats-officedocument.presentationml.slideshow"},
  {"ppt", "application/vnd.ms-powerpoint"},
  {"pptm", "application/vnd.ms-powerpoint.presentation.macroEnabled.12"},
  {"pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation"},
  {"prf", "application/pics-rules"},
  {"prm", "application/octet-stream"},
  {"prx", "application/octet-stream"},
  {"ps", "application/postscript"},
  {"psc1", "application/PowerShell"},
  {"psd", "application/octet-stream"},
  {"psess", "application/xml"},
  {"psm", "application/octet-stream"},
  {"psp", "application/octet-stream"},
  {"pst", "application/vnd.ms-outlook"},
  {"pub", "application/x-mspublisher"},
  {"pwz", "application/vnd.ms-powerpoint"},
  {"qht", "text/x-html-insertion"},
  {"qhtm", "text/x-html-insertion"},
  {"qt", "video/quicktime"},
  {"qti", "image/x-quicktime"},
  {"qtif", "image/x-quicktime"},
  {"qtl", "application/x-quicktimeplayer"},
  {"qxd", "application/octet-stream"},
  {"ra", "audio/x-pn-realaudio"},
  {"ram", "audio/x-pn-realaudio"},
  {"rar", {"application/x-rar-compressed", "application/x-rar", "application/octet-stream"}},
  {"ras", "image/x-cmu-raster"},
  {"rat", "application/rat-file"},
  {"rc", "text/plain"},
  {"rc2", "text/plain"},
  {"rct", "text/plain"},
  {"rdlc", "application/xml"},
  {"reg", "text/plain"},
  {"resx", "application/xml"},
  {"rf", "image/vnd.rn-realflash"},
  {"rgb", "image/x-rgb"},
  {"rgs", "text/plain"},
  {"rm", "application/vnd.rn-realmedia"},
  {"rmi", "audio/mid"},
  {"rmp", "application/vnd.rn-rn_music_package"},
  {"roff", "application/x-troff"},
  {"rpm", "audio/x-pn-realaudio-plugin"},
  {"rqy", "text/x-ms-rqy"},
  {"rtf", {"application/rtf","application/msword", "text/richtext", "text/rtf"}},
  {"rtx", "text/richtext"},
  {"rvt", "application/octet-stream" },
  {"ruleset", "application/xml"},
  {"s", "text/plain"},
  {"safariextz", "application/x-safari-safariextz"},
  {"scd", "application/x-msschedule"},
  {"scr", "text/plain"},
  {"sct", "text/scriptlet"},
  {"sd2", "audio/x-sd2"},
  {"sdp", "application/sdp"},
  {"sea", "application/octet-stream"},
  {"searchConnector-ms", "application/windows-search-connector+xml"},
  {"setpay", "application/set-payment-initiation"},
  {"setreg", "application/set-registration-initiation"},
  {"settings", "application/xml"},
  {"sgimb", "application/x-sgimb"},
  {"sgml", "text/sgml"},
  {"sh", "application/x-sh"},
  {"shar", "application/x-shar"},
  {"shtml", "text/html"},
  {"sit", "application/x-stuffit"},
  {"sitemap", "application/xml"},
  {"skin", "application/xml"},
  {"skp", "application/x-koan" },
  {"sldm", "application/vnd.ms-powerpoint.slide.macroEnabled.12"},
  {"sldx", "application/vnd.openxmlformats-officedocument.presentationml.slide"},
  {"slk", "application/vnd.ms-excel"},
  {"sln", "text/plain"},
  {"slupkg-ms", "application/x-ms-license"},
  {"smd", "audio/x-smd"},
  {"smi", "application/octet-stream"},
  {"smx", "audio/x-smd"},
  {"smz", "audio/x-smd"},
  {"snd", "audio/basic"},
  {"snippet", "application/xml"},
  {"snp", "application/octet-stream"},
  {"sol", "text/plain"},
  {"sor", "text/plain"},
  {"spc", "application/x-pkcs7-certificates"},
  {"spl", "application/futuresplash"},
  {"spx", "audio/ogg"},
  {"src", "application/x-wais-source"},
  {"srf", "text/plain"},
  {"SSISDeploymentManifest", "text/xml"},
  {"ssm", "application/streamingmedia"},
  {"sst", "application/vnd.ms-pki.certstore"},
  {"stl", "application/vnd.ms-pki.stl"},
  {"sv4cpio", "application/x-sv4cpio"},
  {"sv4crc", "application/x-sv4crc"},
  {"svc", "application/xml"},
  {"svg", "image/svg+xml"},
  {"swf", "application/x-shockwave-flash"},
  {"step", "application/step"},
  {"stp", "application/step"},
  {"t", "application/x-troff"},
  {"tar", "application/x-tar"},
  {"tcl", "application/x-tcl"},
  {"testrunconfig", "application/xml"},
  {"testsettings", "application/xml"},
  {"tex", "application/x-tex"},
  {"texi", "application/x-texinfo"},
  {"texinfo", "application/x-texinfo"},
  {"tgz", "application/x-compressed"},
  {"thmx", "application/vnd.ms-officetheme"},
  {"thn", "application/octet-stream"},
  {"tif", {"image/tiff", "application/octet-stream"}},
  {"tiff", "image/tiff"},
  {"tlh", "text/plain"},
  {"tli", "text/plain"},
  {"toc", "application/octet-stream"},
  {"tr", "application/x-troff"},
  {"trm", "application/x-msterminal"},
  {"trx", "application/xml"},
  {"ts", "video/vnd.dlna.mpeg-tts"},
  {"tsv", "text/tab-separated-values"},
  {"ttf", "application/font-sfnt"},
  {"tts", "video/vnd.dlna.mpeg-tts"},
  {"txt", "text/plain"},
  {"u32", "application/octet-stream"},
  {"uls", "text/iuls"},
  {"user", "text/plain"},
  {"ustar", "application/x-ustar"},
  {"vb", "text/plain"},
  {"vbdproj", "text/plain"},
  {"vbk", "video/mpeg"},
  {"vbproj", "text/plain"},
  {"vbs", "text/vbscript"},
  {"vcf", {"text/x-vcard", "text/vcard"}},
  {"vcproj", "application/xml"},
  {"vcs", "text/plain"},
  {"vcxproj", "application/xml"},
  {"vddproj", "text/plain"},
  {"vdp", "text/plain"},
  {"vdproj", "text/plain"},
  {"vdx", "application/vnd.ms-visio.viewer"},
  {"vml", "text/xml"},
  {"vscontent", "application/xml"},
  {"vsct", "text/xml"},
  {"vsd", "application/vnd.visio"},
  {"vsi", "application/ms-vsi"},
  {"vsix", "application/vsix"},
  {"vsixlangpack", "text/xml"},
  {"vsixmanifest", "text/xml"},
  {"vsmdi", "application/xml"},
  {"vspscc", "text/plain"},
  {"vss", "application/vnd.visio"},
  {"vsscc", "text/plain"},
  {"vssettings", "text/xml"},
  {"vssscc", "text/plain"},
  {"vst", "application/vnd.visio"},
  {"vstemplate", "text/xml"},
  {"vsto", "application/x-ms-vsto"},
  {"vsw", "application/vnd.visio"},
  {"vsx", "application/vnd.visio"},
  {"vtx", "application/vnd.visio"},
  {"wav", "audio/wav"},
  {"wave", "audio/wav"},
  {"wax", "audio/x-ms-wax"},
  {"wbk", "application/msword"},
  {"wbmp", "image/vnd.wap.wbmp"},
  {"wcm", "application/vnd.ms-works"},
  {"wdb", "application/vnd.ms-works"},
  {"wdp", "image/vnd.ms-photo"},
  {"webarchive", "application/x-safari-webarchive"},
  {"webm", "video/webm"},
  {"webp", "image/webp"},
  {"webtest", "application/xml"},
  {"wiq", "application/xml"},
  {"wiz", "application/msword"},
  {"wks", "application/vnd.ms-works"},
  {"WLMP", "application/wlmoviemaker"},
  {"wlpginstall", "application/x-wlpg-detect"},
  {"wlpginstall3", "application/x-wlpg3-detect"},
  {"wm", "video/x-ms-wm"},
  {"wma", "audio/x-ms-wma"},
  {"wmd", "application/x-ms-wmd"},
  {"wmf", "application/x-msmetafile"},
  {"wml", "text/vnd.wap.wml"},
  {"wmlc", "application/vnd.wap.wmlc"},
  {"wmls", "text/vnd.wap.wmlscript"},
  {"wmlsc", "application/vnd.wap.wmlscriptc"},
  {"wmp", "video/x-ms-wmp"},
  {"wmv", "video/x-ms-wmv"},
  {"wmx", "video/x-ms-wmx"},
  {"wmz", "application/x-ms-wmz"},
  {"woff", "application/font-woff"},
  {"wpl", "application/vnd.ms-wpl"},
  {"wps", "application/vnd.ms-works"},
  {"wri", "application/x-mswrite"},
  {"wrl", "x-world/x-vrml"},
  {"wrz", "x-world/x-vrml"},
  {"wsc", "text/scriptlet"},
  {"wsdl", "text/xml"},
  {"wvx", "video/x-ms-wvx"},
  {"x", "application/directx"},
  {"xaf", "x-world/x-vrml"},
  {"xaml", "application/xaml+xml"},
  {"xap", "application/x-silverlight-app"},
  {"xbap", "application/x-ms-xbap"},
  {"xbm", "image/x-xbitmap"},
  {"xdr", "text/plain"},
  {"xht", "application/xhtml+xml"},
  {"xhtml", "application/xhtml+xml"},
  {"xla", "application/vnd.ms-excel"},
  {"xlam", "application/vnd.ms-excel.addin.macroEnabled.12"},
  {"xlc", "application/vnd.ms-excel"},
  {"xld", "application/vnd.ms-excel"},
  {"xlk", "application/vnd.ms-excel"},
  {"xll", "application/vnd.ms-excel"},
  {"xlm", "application/vnd.ms-excel"},
  {"xls", {
    "application/excel",
    "application/vnd.ms-excel",
    "application/vnd.ms-office",
    "application/x-excel",
    "application/octet-stream"
  }},
  {"xlsb", "application/vnd.ms-excel.sheet.binary.macroEnabled.12"},
  {"xlsm", "application/vnd.ms-excel.sheet.macroEnabled.12"},
  {"xlsx", {
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    "application/vnd.ms-excel.12",
    "application/octet-stream"
  }},
  {"xlt", "application/vnd.ms-excel"},
  {"xltm", "application/vnd.ms-excel.template.macroEnabled.12"},
  {"xltx", "application/vnd.openxmlformats-officedocument.spreadsheetml.template"},
  {"xlw", "application/vnd.ms-excel"},
  {"xml", {"application/xml", "text/xml", "application/octet-stream"}},
  {"xmp", "application/octet-stream" },
  {"xmta", "application/xml"},
  {"xof", "x-world/x-vrml"},
  {"XOML", "text/plain"},
  {"xpm", "image/x-xpixmap"},
  {"xps", "application/vnd.ms-xpsdocument"},
  {"xrm-ms", "text/xml"},
  {"xsc", "application/xml"},
  {"xsd", "text/xml"},
  {"xsf", "text/xml"},
  {"xsl", "text/xml"},
  {"xslt", "text/xml"},
  {"xsn", "application/octet-stream"},
  {"xss", "application/xml"},
  {"xspf", "application/xspf+xml"},
  {"xtp", "application/octet-stream"},
  {"xwd", "image/x-xwindowdump"},
  {"z", "application/x-compress"},
  {"zip", {
    "application/zip",
    "application/x-zip-compressed",
    "application/octet-stream"
  }},
  {"zlib", "application/zlib"},
}

-- Used to match extension by content type
exports.reversed_extensions_map = {
  ["text/html"] = "html",
  ["text/css"] = "css",
  ["text/xml"] = "xml",
  ["image/gif"] = "gif",
  ["image/jpeg"] = "jpeg",
  ["application/javascript"] = "js",
  ["application/atom+xml"] = "atom",
  ["application/rss+xml"] = "rss",
  ["application/csv"] = "csv",
  ["text/mathml"] = "mml",
  ["text/plain"] = "txt",
  ["text/vnd.sun.j2me.app-descriptor"] = "jad",
  ["text/vnd.wap.wml"] = "wml",
  ["text/x-component"] = "htc",
  ["image/png"] = "png",
  ["image/svg+xml"] = "svg",
  ["image/tiff"] = "tiff",
  ["image/vnd.wap.wbmp"] = "wbmp",
  ["image/webp"] = "webp",
  ["image/x-icon"] = "ico",
  ["image/x-jng"] = "jng",
  ["image/x-ms-bmp"] = "bmp",
  ["font/woff"] = "woff",
  ["font/woff2"] = "woff2",
  ["application/java-archive"] = "jar",
  ["application/json"] = "json",
  ["application/mac-binhex40"] = "hqx",
  ["application/msword"] = "doc",
  ["application/pdf"] = "pdf",
  ["application/postscript"] = "ps",
  ["application/rtf"] = "rtf",
  ["application/vnd.apple.mpegurl"] = "m3u8",
  ["application/vnd.google-earth.kml+xml"] = "kml",
  ["application/vnd.google-earth.kmz"] = "kmz",
  ["application/vnd.ms-excel"] = "xls",
  ["application/vnd.ms-fontobject"] = "eot",
  ["application/vnd.ms-powerpoint"] = "ppt",
  ["application/vnd.oasis.opendocument.graphics"] = "odg",
  ["application/vnd.oasis.opendocument.presentation"] = "odp",
  ["application/vnd.oasis.opendocument.spreadsheet"] = "ods",
  ["application/vnd.oasis.opendocument.text"] = "odt",
  ["application/vnd.openxmlformats-officedocument.presentationml.presentation"] = "pptx",
  ["application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"] = "xlsx",
  ["application/vnd.openxmlformats-officedocument.wordprocessingml.document"] = "docx",
  ["application/x-7z-compressed"] = "7z",
  ["application/x-cocoa"] = "cco",
  ["application/x-java-archive-diff"] = "jardiff",
  ["application/x-java-jnlp-file"] = "jnlp",
  ["application/x-makeself"] = "run",
  ["application/x-perl"] = "pl",
  ["application/x-pilot"] = "pdb",
  ["application/x-rar-compressed"] = "rar",
  ["application/x-redhat-package-manager"] = "rpm",
  ["application/x-sea"] = "sea",
  ["application/x-shockwave-flash"] = "swf",
  ["application/x-stuffit"] = "sit",
  ["application/x-tcl"] = "tcl",
  ["application/x-x509-ca-cert"] = "crt",
  ["application/x-xpinstall"] = "xpi",
  ["application/xhtml+xml"] = "xhtml",
  ["application/xspf+xml"] = "xspf",
  ["application/zip"] = "zip",
  ["application/x-dosexec"] = "exe",
  ["application/x-msdownload"] = "exe",
  ["application/x-executable"] = "exe",
  ["text/x-msdos-batch"] = "bat",

  ["audio/midi"] = "mid",
  ["audio/mpeg"] = "mp3",
  ["audio/ogg"] = "ogg",
  ["audio/x-m4a"] = "m4a",
  ["audio/x-realaudio"] = "ra",
  ["video/3gpp"] = "3gpp",
  ["video/mp2t"] = "ts",
  ["video/mp4"] = "mp4",
  ["video/mpeg"] = "mpeg",
  ["video/quicktime"] = "mov",
  ["video/webm"] = "webm",
  ["video/x-flv"] = "flv",
  ["video/x-m4v"] = "m4v",
  ["video/x-mng"] = "mng",
  ["video/x-ms-asf"] = "asx",
  ["video/x-ms-wmv"] = "wmv",
  ["video/x-msvideo"] = "avi",
}

return exports