feat: add IP-ASN rule

constant/path.go

@@ -15,6 +15,7 @@ const Name = "mihomo"
 var (
 	GeositeName = "GeoSite.dat"
 	GeoipName   = "GeoIP.dat"
+	ASNName     = "ASN.mmdb"
 )
 
 // Path is used to get the configuration path
@@ -112,6 +113,25 @@ func (p *path) MMDB() string {
 	return P.Join(p.homeDir, "geoip.metadb")
 }
 
+func (p *path) ASN() string {
+	files, err := os.ReadDir(p.homeDir)
+	if err != nil {
+		return ""
+	}
+	for _, fi := range files {
+		if fi.IsDir() {
+			// 目录则直接跳过
+			continue
+		} else {
+			if strings.EqualFold(fi.Name(), "ASN.mmdb") {
+				ASNName = fi.Name()
+				return P.Join(p.homeDir, fi.Name())
+			}
+		}
+	}
+	return P.Join(p.homeDir, ASNName)
+}
+
 func (p *path) OldCache() string {
 	return P.Join(p.homeDir, ".cache")
 }