fix validateAddressFormat

I2PAddr.go

@@ -3,6 +3,7 @@ package i2pkeys
 import (
 	"crypto/sha256"
 	"fmt"
+	"net"
 	"strings"
 )
 
@@ -60,15 +61,21 @@ func sanitizeAddress(addr string) string {
 }
 
 func validateAddressFormat(addr string) error {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		// If SplitHostPort fails, it means addr is not in host:port format
+		host = addr
+	}
+	if host != "" {
+		addr = host
+	}
 	if len(addr) > MaxAddressLength || len(addr) < MinAddressLength {
 		return fmt.Errorf("invalid address length: got %d, want between %d and %d",
 			len(addr), MinAddressLength, MaxAddressLength)
 	}
-
 	if strings.HasSuffix(addr, B32Suffix) {
 		return fmt.Errorf("cannot convert %s to full destination", B32Suffix)
 	}
-
 	return nil
 }