ip.lua

#!/usr/bin/env luajit

local bit = require("bit")

function byteToUint32(a,b,c,d)
        local _int = 0
	if a then
		_int = _int +  bit.lshift(a, 24)
	end
	_int = _int + bit.lshift(b, 16)
	_int = _int + bit.lshift(c, 8)
	_int = _int + d
	if _int >= 0 then
        return _int
    else
        return _int + math.pow(2, 32)
    end
end

local ipBinaryFilePath = "../../../../17monipdb.dat"

function IpLocation(ipstr)
    local ip1,ip2,ip3,ip4 = string.match(ipstr, "(%d+).(%d+).(%d+).(%d+)")
    local ip_uint32 = byteToUint32(ip1, ip2, ip3, ip4)
	local file = io.open(ipBinaryFilePath)
	if file == nil then
		return nil
	end

	local str = file:read(4)
	local offset_len = byteToUint32(string.byte(str, 1), string.byte(str, 2),string.byte(str, 3),string.byte(str, 4))

	local indexBuffer = file:read(offset_len - 4)

	local tmp_offset = ip1 * 4 
	local start_len = byteToUint32(string.byte(indexBuffer, tmp_offset + 4), string.byte(indexBuffer, tmp_offset + 3), string.byte(indexBuffer, tmp_offset + 2), string.byte(indexBuffer, tmp_offset + 1))

	local max_comp_len = offset_len - 1028
	start = start_len * 8 + 1024 + 1
    local find_uint32 = 0
	local index_offset = -1
	local index_length = -1
	while start < max_comp_len do
        find_uint32 = byteToUint32(string.byte(indexBuffer, start), string.byte(indexBuffer, start+1),string.byte(indexBuffer, start+2),string.byte(indexBuffer, start+3))
        if ip_uint32 <= find_uint32  then
			index_offset = byteToUint32(0, string.byte(indexBuffer, start+6),string.byte(indexBuffer, start+5),string.byte(indexBuffer, start+4))
			index_length = string.byte(indexBuffer, start+7)
			break
		end
		start = start + 8
	end

	if index_offset == -1 or index_length == -1 then
		return nil
	end

	local offset = offset_len + index_offset - 1024

	file:seek("set", offset)

	return file:read(index_length)
end

print(IpLocation("128.0.0.0"))