Convert maxmind mmdb file into map for Rspamd

mmdb2map.go

package main

import (
	"fmt"
	"log"

	"github.com/oschwald/maxminddb-golang"
)

func main() {
	db, err := maxminddb.Open("/usr/share/GeoIP/GeoLite2-Country.mmdb")
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	record := struct {
		Country struct {
			ISOCode string `maxminddb:"iso_code"`
		} `maxminddb:"country"`
	}{}

	networks := db.Networks(maxminddb.SkipAliasedNetworks)
	for networks.Next() {
		subnet, err := networks.Network(&record)
		if err != nil {
			log.Panic(err)
		}
		if record.Country.ISOCode != "" {
			fmt.Printf("%s %s\n", subnet.String(), record.Country.ISOCode)
		}
	}
	if networks.Err() != nil {
		log.Panic(networks.Err())
	}
}