Feat: support IPv4 address in IPv6 format

This change will convert 4in6 IPv6 addresses to IPv4 addresses

lib/lib.go

@@ -167,8 +167,8 @@ func (e *Entry) processPrefix(src any) (*netip.Prefix, IPType, error) {
 		_, network, err := net.ParseCIDR(src)
 		switch err {
 		case nil:
-			prefix, ok := netipx.FromStdIPNet(network)
-			if !ok {
+			prefix, err2 := netip.ParsePrefix(network.String())
+			if err2 != nil {
 				return nil, "", ErrInvalidIPNet
 			}
 			ip := prefix.Addr()
@@ -190,6 +190,16 @@ func (e *Entry) processPrefix(src any) (*netip.Prefix, IPType, error) {
 			case ip.Is4():
 				prefix := netip.PrefixFrom(ip, 32)
 				return &prefix, IPv4, nil
+			case ip.Is4In6():
+				_, network, err2 := net.ParseCIDR(src + "/128")
+				if err2 != nil {
+					return nil, "", ErrInvalidIPNet
+				}
+				prefix, err3 := netip.ParsePrefix(network.String())
+				if err3 != nil {
+					return nil, "", ErrInvalidIPNet
+				}
+				return &prefix, IPv4, nil
 			case ip.Is6():
 				prefix := netip.PrefixFrom(ip, 128)
 				return &prefix, IPv6, nil