geo-ip.go

package main

import (
	"fmt"
	"github.com/oschwald/geoip2-golang"
	"log"
	"net"
	"os"
)

// geolocate returns the geographical location of the IP address.
func geolocate(ipaddr string) (string, error) {
	// Download from https://dev.maxmind.com/geoip/geoip2/geolite2/
	MaxMindDB := "GeoLite2-City.mmdb"

	db, err := geoip2.Open(MaxMindDB)
	if err != nil {
		return "", err
	}
	defer db.Close()

	ip := net.ParseIP(ipaddr)
	record, err := db.City(ip)
	if err != nil {
		return "", err
	}

	return record.Country.Names["en"], nil
}

func main() {
	if len(os.Args) != 2 {
		fmt.Fprintf(os.Stderr, "You need to supply an IP address\n")
		os.Exit(1)
	}
	ipaddr := os.Args[1]

	loc, err := geolocate(ipaddr)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(loc)
}