lasi.cgi.lua

#! /home/stuserbot/bin/lua
local rt = {}

local getenv = os.getenv
local strupper = string.upper
local strlower = string.lower
local format = string.format
local gsub = string.gsub
local setmetatable = setmetatable
local write = io.write
local pcall = pcall

do --server------------------------------------------------------------
  local servars = {"software", "name", "port",
  "protocol"} --todo: replace url_scheme in the spec with this
  rt.server = {}
  for i=1, #servars do
    local var = servars[i]
    rt.server[var] = getenv("SERVER_"..strupper(var))
  end

  local cgiver = getenv "GATEWAY_INTERFACE" or ""
  rt.server.connector = format("lasi.cgi/0.3.0 (%s)",cgiver)
end

do --headers-----------------------------------------------------------
  local http_headers = {
    "Accept",
    "User-Agent",
    "Connection",
    "Referer",
    "Cookie",
    "Host"
  }
  local function normalize(name)
    name = gsub(name,"%-","%_")
    return strlower(name)
  end


  local function get_header_var(header)
    return getenv("HTTP_"..strupper(header))
  end

  rt.headers = {}
  rt.headers.content_length = getenv "CONTENT_LENGTH"
  rt.headers.content_type = getenv "CONTENT_TYPE"
  for i=1, #http_headers do
    local header = normalize(http_headers[i])

    rt.headers[header] = get_header_var(header)
  end

  --add index metamethod to catch any other headers
  local metamethods = {}
  function metamethods:__index(header)
    local header = normalize(header)
    if not self[header] then
      self[header]= get_header_var(header)
    end
    return self[header]
  end

  setmetatable(rt.headers,metamethods)
end

do --others------------------------------------------------------------
  rt.method = getenv "REQUEST_METHOD"
  rt.query = getenv "QUERY_STRING"
  rt.prefix = getenv "SCRIPT_NAME"
  rt.path = getenv "PATH_INFO"
end

--run------------------------------------------------------------------
local function respond(code, headers,msg)
  local function normalize(name)
    --todo: non-alphanumeric/hyphen characters?
    return gsub(name,"%_","%-")
  end

  write('Status: ',code,'\n')

  for k,v in pairs(headers) do
    --todo: sanitize values
    write(normalize(k),': ',v,'\n')
  end

  write'\n'

  if rt.method ~= "HEAD" then
    --todo: support for non-string messages
    write(msg)
  end
end

local function resperr(msg)
  respond(500,{["Content-Type"]="text/plain"},msg)
end

local script = getenv "PATH_TRANSLATED"
if not script then
  print "PATH_TRANSLATED environment variable not defined."
  print "(Is this being called as a CGI handler?)"
else
  local scr, err = io.open(script)
  if scr then
    success, coderr, headers, msg =
      pcall(scr)
    if success then
      respond(coderr, headers, msg)
    else
      resperr(coderr)
    end
  else
    resperr(coderr)
  end
end