whoami.fangpeishi.com (whoami.akamai.com) based on openresty

nginx.conf

worker_processes  1;
daemon on;
master_process on;


error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  debug;

#pid        logs/nginx.pid;


events {
    accept_mutex off;
    worker_connections  1024;
}


stream {
    lua_package_path '$prefix/lualib/?.lua;;';

    init_by_lua_block {
            jit.opt.start("minstitch=2")
            }

    server {
            listen 53 udp;

            content_by_lua_block {
                 require "whoami".go()
            }
       }
}

whoami.lua

local bit = require "bit"
local byte = string.byte
local lshift = bit.lshift
local rshift = bit.rshift
local char = string.char
local sub = string.sub
local gmatch = string.gmatch

local _M = {}
local resp_tb = {}



function _M.go()
   local sock, err = ngx.req.udp_socket()
   if not sock then
      ngx.log(ngx.ERR, "failed to get the request socket:", err)
      return ngx.exit(ngx.ERROR)
   end

   local req, err = sock:receive()
   if not req then
      ngx.log(ngx.ERR, "failed to receive:", err)
      return ngx.exit(ngx.ERROR)
   end

   local id
   local n = #req
   if n < 12 then
      ngx.log(ngx.ERR, "request truncated")
      return
   end


   -- Transaction ID
   resp_tb[1] = char(byte(req, 1))
   resp_tb[2] = char(byte(req, 2))

   -- Flags
   resp_tb[3] = "\x84\xa0"

   -- Questions, Answer RRS, Authority RRs,Additional RRs
   resp_tb[4] = "\x00\x01\x00\x01\x00\x00\x00\x00"

   -- Queries
   -- for "whoami.fangpeishi.com"
   resp_tb[5] = char(byte(req, 13,39))


   -- Answers
   -- Name
   resp_tb[6] = "\xc0\x0c"

   -- TTL 180s
   resp_tb[7] = "\x00\x01\x00\x01\x00\x00\x00\x02"

   -- RDLength
   resp_tb[8] = "\x00\x04"

   -- RDdata
   local i = 9
   for code in gmatch(ngx.var.remote_addr, '([0-9]+)') do
      resp_tb[i] = char(code)
      i = i+1
   end


   local ok, err = sock:send{resp_tb}
   if not ok then
      ngx.log(ngx.ERR, "failed to send:", err)
      return
   end

end

return _M