first commit

geo.go

@@ -0,0 +1,136 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"os"
+	"path/filepath"
+
+	"github.com/oschwald/maxminddb-golang"
+)
+
+type Geo struct {
+	asn  *maxminddb.Reader
+	city *maxminddb.Reader
+}
+
+type ASNResult struct {
+	AutonomousSystemNumber       uint   `maxminddb:"autonomous_system_number"`
+	AutonomousSystemOrganization string `maxminddb:"autonomous_system_organization"`
+}
+
+type CityResult struct {
+	Continent struct {
+		Names map[string]string `maxminddb:"names"`
+	} `maxminddb:"continent"`
+	Country struct {
+		Names map[string]string `maxminddb:"names"`
+	} `maxminddb:"country"`
+	City struct {
+		Names map[string]string `maxminddb:"names"`
+	} `maxminddb:"city"`
+}
+
+func DownloadFile(url, dest string) error {
+	if err := os.MkdirAll(filepath.Dir(dest), 0o755); err != nil {
+		return err
+	}
+
+	fmt.Printf("downloading %s -> %s\n", url, dest)
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("HTTP %d for %s", resp.StatusCode, url)
+	}
+
+	out, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	_, err = io.Copy(out, resp.Body)
+	return err
+}
+
+func ensureMMDB(url, path string) error {
+	if _, err := os.Stat(path); err == nil {
+		return nil
+	}
+	return DownloadFile(url, path)
+}
+
+func InitGeo(cfg *GeoConfig) (*Geo, error) {
+	if err := ensureMMDB(cfg.AsnURL, cfg.AsnPath); err != nil {
+		return nil, fmt.Errorf("ASN DB: %w", err)
+	}
+	if err := ensureMMDB(cfg.CityURL, cfg.CityPath); err != nil {
+		return nil, fmt.Errorf("City DB: %w", err)
+	}
+
+	asn, err := maxminddb.Open(cfg.AsnPath)
+	if err != nil {
+		return nil, fmt.Errorf("open ASN DB: %w", err)
+	}
+	city, err := maxminddb.Open(cfg.CityPath)
+	if err != nil {
+		asn.Close()
+		return nil, fmt.Errorf("open City DB: %w", err)
+	}
+
+	return &Geo{asn: asn, city: city}, nil
+}
+
+func (g *Geo) Close() {
+	g.asn.Close()
+	g.city.Close()
+}
+
+type GeoInfo struct {
+	ASN         string
+	Org         string
+	Continent   string
+	Country     string
+	City        string
+	ReverseDNS  string
+}
+
+func (g *Geo) Lookup(ip net.IP) GeoInfo {
+	info := GeoInfo{ReverseDNS: "Unknown"}
+
+	hosts, err := net.LookupAddr(ip.String())
+	if err == nil && len(hosts) > 0 {
+		info.ReverseDNS = hosts[0]
+	}
+
+	var asn ASNResult
+	if err := g.asn.Lookup(ip, &asn); err == nil {
+		if asn.AutonomousSystemNumber > 0 {
+			info.ASN = fmt.Sprintf("AS%d", asn.AutonomousSystemNumber)
+			info.Org = asn.AutonomousSystemOrganization
+		}
+	}
+
+	var cr CityResult
+	if err := g.city.Lookup(ip, &cr); err == nil {
+		info.Continent = cr.Continent.Names["en"]
+		info.Country = cr.Country.Names["en"]
+		info.City = cr.City.Names["en"]
+	}
+
+	return info
+}
+
+type GeoConfig struct {
+	AsnURL   string
+	CityURL  string
+	AsnPath  string
+	CityPath string
+}