Lua_Script

-- ----------------------------------------------------------------------
-- ---------------------------------------------------------------------
--  Lua Script to convert Basic Auth header to JWT authrization header.
-- ----------------------------------------------------------------------
-- ----------------------------------------------------------------------


-- ------------------------------
--  Function to split the String
-- ------------------------------

function mysplit(inputstr, sep)
        if sep == nil then
                sep = "%s"
        end
        local t={} ; i=1
        for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
                t[i] = str
                i = i + 1
        end
        return t
end

-- -------------------------------------------
--  Function to extract header from request
-- -------------------------------------------

function extract_params()
  local params = {}
  local header_params = ngx.req.get_headers()

  params.authorization = {}

  if header_params['Authorization'] then
    local authorizationParams_temp = header_params['Authorization']
    local authorizationParams = mysplit(authorizationParams_temp," ")
    if authorizationParams[1] == "Basic" then
     params.authorization = mysplit(ngx.decode_base64(authorizationParams[2]),":")
           params.client_id = params.authorization[1]
     params.client_secret = params.authorization[2]
    end
   end
  return params
end

-- --------------------------------------
-- Get the token from the OAuth Server
-- -------------------------------------
function get_token(params,logger)
  local res = {}
  local json = require('cjson')

  res = request_token(params)
  local jsonValueOfResponse = json.decode(res.body)
  local tokenValue=''
  for k,v in pairs(jsonValueOfResponse) do
     if k == "access_token" then
        tokenValue = v
     end
  end
  if res.status ~= 200 then
    ngx.status = res.status
    ngx.header.content_type = "application/json; charset=utf-8"
    ngx.print(res.body)
    ngx.exit(ngx.HTTP_FORBIDDEN)
  else
   set_token(tokenValue)
  end
end


-- --------------------------------------------
-- Calls the token endpoint to request a token
-- --------------------------------------------
function request_token(params)

 local http = require ('resty.http')
      local httpc = http.new()
      local res, err = httpc:request_uri("http://authServer.in/connect/token", {
        method = "POST",
        body = "client_id=" .. params.client_id .. "&client_secret=" .. params.client_secret .."&scope=internal_services&grant_type=client_credentials"
      })
      if not res then
        ngx.say("failed to request: ", err)
        return
      end
  return { ["status"] = res.status, ["body"] = res.body }
end

-- -----------------------------------
-- Rset token in the Header
-- -----------------------------------
function set_token(token)
       ngx.req.set_header("Authorization", "Bearer " .. token);
end

-- ------------------------
-- ------------------------
-- Entry Point Started
-- -------------------------
-- ------------------------

local headerParams = extract_params()

if headerParams.client_id and headerParams.client_secret then
   get_token(headerParams,logger)
end