IPv4 to Mongo ObjectID

main.go

package main

import (
	"encoding/hex"
	"fmt"
	"strings"

	"gopkg.in/mgo.v2/bson"
)

func main() {

	fmt.Print(IPv4ToObjectID("127.0.0.1"))
	fmt.Print(IPv4ToObjectID("255.255.255.255"))
}

func IPv4ToObjectID(IP string) bson.ObjectId {

	ip := strings.Replace(IP, ".", "", -1)
	ipLen := len(ip)
	if ipLen < 12 {
		ip = ip + strings.Repeat("0", 12-ipLen)
	} else if len(ip) > 12 {
		ip = ip[:12]
	}
	encodedIP := hex.EncodeToString([]byte(ip))

	return bson.ObjectIdHex(encodedIP)
}