ping.lua

local ffi = require 'ffi'
local uv = require 'uv'
local os = require('os')

local AF_INET = 2
local AF_INET6 = jit.os == "OSX" and 30 or
                 jit.os == "Linux" and 10 or error("Unknown OS")
local SOCK_RAW = 3
local IPPROTO_ICMP = 1
local IPPROTO_ICMP6 = 58
ffi.cdef[[
  int socket(int socket_family, int socket_type, int protocol);
]]

local band = bit.band
local bor = bit.bor
local bnot = bit.bnot
local lshift = bit.lshift
local rshift = bit.rshift
local byte = string.byte
local char = string.char
local time = os.time

-- Calculate 16-bit one's complement of the one's complement sum
local function checksum(buffer)
  local sum = 0
  for i = 1, #buffer, 2 do
    local word = bor(lshift(byte(buffer, i), 8), byte(buffer, i + 1))
    sum = sum + word
    if sum > 0xffff then
      sum = sum - 0xffff -- remove carry bit and add 1
    end
  end

  -- Take complement
  sum = band(bnot(sum), 0xffff)

  -- Return as 2-byte string in network byte order
  return char(rshift(sum, 8), band(sum, 0xff))
end


local function sock4(ip)
  local sockfd = ffi.C.socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)
  assert(sockfd >= 0, "Failed to create socket")
  local raw = uv.new_udp()
  assert(raw:open(sockfd))
  return raw
end

local function sock6(ip)
  local sockfd = ffi.C.socket(AF_INET6, SOCK_RAW, IPPROTO_ICMP6)
  assert(sockfd >= 0, "Failed to create socket")
  local raw = uv.new_udp()
  assert(raw:open(sockfd))
  return raw
end


local id = math.random(0x10000) % 0x10000
local seq = 0

local function ping(ip, payload)
  local now = time()
  local top, sock
  if ip:match("^%d+%.%d+%.%d+%.%d+$") then
    top = "\x08\x00"
    sock = sock4(ip)
  else
    top = "\x80\x00"
    sock = sock6(ip)
  end
  local bottom = char(
    band(rshift(id, 8), 0xff), band(id, 0xff), -- id
    band(rshift(seq, 8), 0xff), band(seq, 0xff), -- seq
    -- timestamp
    band(rshift(now, 24), 0xff), band(rshift(now, 16), 0xff),
    band(rshift(now, 8), 0xff), band(now, 0xff)
  ) .. payload
  seq = (seq + 1) % 256
  sock:send(top .. checksum(top .. "\x00\x00" .. bottom) .. bottom, ip, 0)
  sock:recv_start(function (err, message, address)
    assert(not err, err)
    p { message = message, address = address }
    sock:recv_stop()
  end)
end

local e4payload = "\x00\x02\x7b\x14\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f" ..
  "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f" ..
  "\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f" ..
  "\x30\x31\x32\x33\x34\x35\x36\x37"
local e6payload = "\x56\x03\x01\xc9\x00\x01\xa3\x7d"

uv.new_timer():start(0, 1000, function ()
  ping("127.0.0.1", e4payload)
  ping("::1", e6payload)
  ping("23.253.227.83", e4payload)
  ping("2001:4800:7817:103:be76:4eff:fe05:3fa8", e6payload)
end)