httpserver-request.lua

-- httpserver-request
-- Part of nodemcu-httpserver, parses incoming client requests.
-- Author: Marcos Kirsch

local function validateMethod(method)
   local httpMethods = {GET=true, HEAD=true, POST=true, PUT=true, DELETE=true, TRACE=true, OPTIONS=true, CONNECT=true, PATCH=true}
   -- default for non-existent attributes returns nil, which evaluates to false
   return httpMethods[method] --
end

local function uriToFilename(uri)
   return "http/" .. string.sub(uri, 2, -1)
end

local function hex_to_char(x)
  return string.char(tonumber(x, 16))
end

local function uri_decode(input)
  return input:gsub("%+", " "):gsub("%%(%x%x)", hex_to_char)
end

local function parseArgs(args)
   local r = {} 
   local i = 1
   if args == nil or args == "" then return r end
   for arg in string.gmatch(args, "([^&]+)") do
      local name, value = string.match(arg, "(.*)=(.*)")
      if name ~= nil then r[name] = uri_decode(value) end
      i = i + 1
   end
   return r
end

local function parseFormData(body)
  local data = {}
  assert(body~=nil, "empty body")
  for kv in body.gmatch(body, "%s*&?([^=]+=[^&]+)") do
    local key, value = string.match(kv, "(.*)=(.*)")
    
--    print("Parsed: " .. key .. " => " .. value)
    data[key] = uri_decode(value)
  end
  return data
end

local function getRequestData(payload)
  local requestData
  return function ()
    if requestData then
      return requestData
    else
      local mimeType = string.match(payload, "Content%-Type: ([%w/-]+)")
      local body_start = payload:find("\r\n\r\n", 1, true)
      local body = payload:sub(body_start, #payload)
      payload = nil
      collectgarbage()
      
      if mimeType == "application/json" then
--        print("JSON: " .. body)
        requestData = cjson.decode(body)
      elseif mimeType == "application/x-www-form-urlencoded" then
        requestData = parseFormData(body)
      else
        requestData = {}
      end
      
      return requestData
    end
  end
end

local function parseUri(uri)
   local r = {}
   local filename
   local ext
   local fullExt = {}

   if uri == nil then return r end
   if uri == "/" then uri = "/index.html" end
   questionMarkPos, b, c, d, e, f = uri:find("?")
   if questionMarkPos == nil then
      r.file = uri:sub(1, questionMarkPos)
      r.args = {}
   else
      r.file = uri:sub(1, questionMarkPos - 1)
      r.args = parseArgs(uri:sub(questionMarkPos+1, #uri))
   end
   filename = r.file
   while filename:match("%.") do
      filename,ext = filename:match("(.+)%.(.+)")
      table.insert(fullExt,1,ext)
   end
   if #fullExt > 1 and fullExt[#fullExt] == 'gz' then
      r.ext = fullExt[#fullExt-1] --
      r.isGzipped = true
   elseif #fullExt >= 1 then
      r.ext = fullExt[#fullExt] --
   end
   r.isScript = r.ext == "lua" or r.ext == "lc"
   r.file = uriToFilename(r.file)
   return r
end

-- Parses the client's request. Returns a dictionary containing pretty much everything
-- the server needs to know about the uri.
return function (request)
    local r = {}
    local e = request:find("\r\n", 1, true)
    if not e then 
        print("httpserver-request.lc: nil e")
        r.methodIsValid = false
        return r
    end
    local line = request:sub(1, e - 1)
    local _ = {}
    local i = {}
    _, i, r.method, r.request = line:find("^([A-Z]+) (.-) HTTP/[1-9]+.[0-9]+$")
    r.methodIsValid = validateMethod(r.method)
    r.uri = parseUri(r.request)
    r.getRequestData = getRequestData(request)
    collectgarbage()
    return r
end