feat: use embed geoip database (#396)

* feat: use embed geoip database

* mention ipinfo

* only read once

* comments

comments

* chore: installer version

---------

Co-authored-by: naiba <hi@nai.ba>

pkg/geoip/geoip.db

@@ -0,0 +1 @@
+stub

pkg/geoip/geoip.go

@@ -0,0 +1,54 @@
+package geoip
+
+import (
+	"embed"
+	"fmt"
+	"log"
+	"net"
+	"strings"
+
+	maxminddb "github.com/oschwald/maxminddb-golang"
+)
+
+//go:embed geoip.db
+var geoDBFS embed.FS
+
+var (
+	dbData []byte
+	err    error
+)
+
+type IPInfo struct {
+	Country       string `maxminddb:"country"`
+	CountryName   string `maxminddb:"country_name"`
+	Continent     string `maxminddb:"continent"`
+	ContinentName string `maxminddb:"continent_name"`
+}
+
+func init() {
+	dbData, err = geoDBFS.ReadFile("geoip.db")
+	if err != nil {
+		log.Printf("NEZHA>> Failed to open geoip database: %v", err)
+	}
+}
+
+func Lookup(ip net.IP, record *IPInfo) (string, error) {
+	db, err := maxminddb.FromBytes(dbData)
+	if err != nil {
+		return "", err
+	}
+	defer db.Close()
+
+	err = db.Lookup(ip, record)
+	if err != nil {
+		return "", err
+	}
+
+	if record.Country != "" {
+		return strings.ToLower(record.Country), nil
+	} else if record.Continent != "" {
+		return strings.ToLower(record.Continent), nil
+	}
+
+	return "", fmt.Errorf("IP not found")
+}