Golang : Convert IPv4 address to packed 32-bit binary format
There are times when we need to deal with low-level network functions such as dealing with C program and the IP version 4 string address format is not really suitable. The IP version 4 address needs to be converted to packed 32-bit binary format first.
For example,
IP address 127.0.0.1 packed to 7f000001
Below is an example on how to convert the IPv4 address to packed 32-bits with encoding/binary
package.
Here you go!
package main
import (
"bytes"
"encoding/binary"
"fmt"
"math/big"
"net"
)
func IP4toInt(IPv4Address net.IP) int64 {
IPv4Int := big.NewInt(0)
IPv4Int.SetBytes(IPv4Address.To4())
return IPv4Int.Int64()
}
//similar to Python's socket.inet_aton() function
//https://docs.python.org/3/library/socket.html#socket.inet_aton
func Pack32BinaryIP4(ip4Address string) string {
ipv4Decimal := IP4toInt(net.ParseIP(ip4Address))
buf := new(bytes.Buffer)
err := binary.Write(buf, binary.BigEndian, uint32(ipv4Decimal))
if err != nil {
fmt.Println("Unable to write to buffer:", err)
}
// present in hexadecimal format
result := fmt.Sprintf("%x", buf.Bytes())
return result
}
func main() {
fmt.Println("IP address 127.0.0.1 packed to ", Pack32BinaryIP4("127.0.0.1"))
fmt.Println("IP address 192.168.0.1 packed to ", Pack32BinaryIP4("192.168.0.1"))
}
Output:
IP address 127.0.0.1 packed to 7f000001
IP address 192.168.0.1 packed to c0a80001
Happy coding!
References:
https://www.socketloop.com/tutorials/golang-convert-decimal-number-integer-to-ipv4-address
https://golang.org/pkg/encoding/binary/#Write
https://www.socketloop.com/tutorials/golang-how-to-convert-cast-string-to-ip-address
See also : Golang : Convert decimal number(integer) to IPv4 address
By Adam Ng
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