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package iploc
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import (
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_ "embed"
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"encoding/binary"
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"net"
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"github.com/yinheli/mahonia"
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)
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// Note: This file is a modified version of https://github.com/yinheli/qqwry.
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//go:embed qqwry.dat
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var qqwry []byte
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const (
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cIndexLen = 7
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cRedirectMode1 = 0x01
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cRedirectMode2 = 0x02
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)
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// Find get country and city base ip
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func Find(ip string) (string, string) {
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// If ip is "::1", To4 returns nil.
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to4 := net.ParseIP(ip).To4()
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if to4 == nil {
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to4 = net.ParseIP("127.0.0.1").To4()
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}
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offset := searchIndex(binary.BigEndian.Uint32(to4))
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if offset <= 0 {
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return "", ""
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}
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var country, area []byte
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mode := readMode(offset + 4)
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if mode == cRedirectMode1 {
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countryOffset := readUInt24(offset + 5)
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mode = readMode(countryOffset)
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if mode == cRedirectMode2 {
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c := readUInt24(countryOffset + 1)
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country = readString(c)
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countryOffset += 4
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} else {
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country = readString(countryOffset)
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countryOffset += uint32(len(country) + 1)
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}
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area = readArea(countryOffset)
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} else if mode == cRedirectMode2 {
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countryOffset := readUInt24(offset + 5)
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country = readString(countryOffset)
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area = readArea(offset + 8)
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} else {
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country = readString(offset + 4)
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area = readArea(offset + uint32(5+len(country)))
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}
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enc := mahonia.NewDecoder("gbk")
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Country := enc.ConvertString(string(country))
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City := enc.ConvertString(string(area))
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return Country, City
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}
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func readMode(offset uint32) byte {
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return qqwry[offset]
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}
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func readArea(offset uint32) []byte {
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mode := readMode(offset)
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if mode == cRedirectMode1 || mode == cRedirectMode2 {
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areaOffset := readUInt24(offset + 1)
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if areaOffset == 0 {
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return []byte("")
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} else {
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return readString(areaOffset)
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}
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} else {
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return readString(offset)
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}
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}
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func readString(offset uint32) []byte {
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data := make([]byte, 0, 30)
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for {
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if qqwry[offset] == 0 {
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break
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}
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data = append(data, qqwry[offset])
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offset++
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}
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return data
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}
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func searchIndex(ip uint32) uint32 {
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header := qqwry[:8]
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start := binary.LittleEndian.Uint32(header[:4])
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end := binary.LittleEndian.Uint32(header[4:])
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for {
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mid := getMiddleOffset(start, end)
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buf := qqwry[mid : mid+cIndexLen]
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ipaddr := binary.LittleEndian.Uint32(buf[:4])
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if end-start == cIndexLen {
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offset := byte3ToUInt32(buf[4:])
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// TODO: 这里可能有bug，需要优化
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if ip < binary.LittleEndian.Uint32(qqwry[end:end+4]) {
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return offset
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} else {
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return 0
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}
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}
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// 找到的比较大，向前移
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if ipaddr > ip {
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end = mid
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} else if ipaddr < ip { // 找到的比较小，向后移
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start = mid
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} else {
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return byte3ToUInt32(buf[4:])
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}
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}
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}
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func readUInt24(offset uint32) uint32 {
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return byte3ToUInt32(qqwry[offset : offset+3])
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}
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func getMiddleOffset(start uint32, end uint32) uint32 {
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records := ((end - start) / cIndexLen) >> 1
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return start + records*cIndexLen
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}
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func byte3ToUInt32(data []byte) uint32 {
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i := uint32(data[0]) & 0xff
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i |= (uint32(data[1]) << 8) & 0xff00
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i |= (uint32(data[2]) << 16) & 0xff0000
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return i
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}
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