Go语言：整形数字字符串转换为IPv6地址字符串

IPv6对应的整形数字为16个字节，只能用big.Int来存储。而类似于“53174336847441874194254142093255507967”这种长度的数字可以由字符串来表示，如下代码用于将数字字符串转换为对应的IPv6地址字符串。

package mainimport ("encoding/hex""errors""fmt""math/big""strings"
)//NumToIPv6 converts a big integer represented by a string into an IPv6 address string
func NumToIPv6(numasstr string) (string, error) {bi, ok := new(big.Int).SetString(numasstr, 10)if !ok {return "", errors.New("fail to convert string to big.Int")}b255 := new(big.Int).SetBytes([]byte{255})var buf = make([]byte, 2)p := make([]string, 8)j := 0var i uinttmpint := new(big.Int)for i = 0; i < 16; i += 2 {tmpint.Rsh(bi, 120-i*8).And(tmpint, b255)bytes := tmpint.Bytes()if len(bytes) > 0 {buf[0] = bytes[0]} else {buf[0] = 0}tmpint.Rsh(bi, 120-(i+1)*8).And(tmpint, b255)bytes = tmpint.Bytes()if len(bytes) > 0 {buf[1] = bytes[0]} else {buf[1] = 0}p[j] = hex.EncodeToString(buf)j++}return strings.Join(p, ":"), nil
}func convertAndPrint(numasstr string) {ipstr, _ := NumToIPv6(numasstr)fmt.Printf("%s %v\n", ipstr, numasstr)
}func main() {convertAndPrint("53174336847441874194254142093255507967")convertAndPrint("53174336768213711679990085974688268287")convertAndPrint("0")convertAndPrint("53174312128255169743780812907543003136")convertAndPrint("65535")convertAndPrint("167904045")convertAndPrint("4294967295")convertAndPrint("281470681743360")convertAndPrint("281474976710655")convertAndPrint("281470849647405")
}

输出：

2801:0137:ffff:ffff:ffff:ffff:ffff:ffff 53174336847441874194254142093255507967
2801:0137:0000:0000:0000:ffff:ffff:ffff 53174336768213711679990085974688268287
0000:0000:0000:0000:0000:0000:0000:0000 0
2801:0000:0000:0000:0000:0000:0000:0000 53174312128255169743780812907543003136
0000:0000:0000:0000:0000:0000:0000:ffff 65535
0000:0000:0000:0000:0000:0000:0a02:032d 167904045
0000:0000:0000:0000:0000:0000:ffff:ffff 4294967295
0000:0000:0000:0000:0000:ffff:0000:0000 281470681743360
0000:0000:0000:0000:0000:ffff:ffff:ffff 281474976710655
0000:0000:0000:0000:0000:ffff:0a02:032d 281470849647405