prefer Network over string

app/router/rules/condition.go

@@ -165,5 +165,5 @@ func NewNetworkMatcher(network *v2net.NetworkList) *NetworkMatcher {
 }
 
 func (this *NetworkMatcher) Apply(dest v2net.Destination) bool {
-	return this.network.HasNetwork(v2net.Network(dest.Network()))
+	return this.network.HasNetwork(dest.Network())
 }

common/net/destination.go

@@ -2,7 +2,7 @@ package net
 
 // Destination represents a network destination including address and protocol (tcp / udp).
 type Destination interface {
-	Network() string  // Protocol of communication (tcp / udp)
+	Network() Network // Protocol of communication (tcp / udp)
 	Address() Address // Address of destination
 	Port() Port
 	String() string // String representation of the destination
@@ -28,8 +28,8 @@ type tcpDestination struct {
 	port    Port
 }
 
-func (dest *tcpDestination) Network() string {
+func (dest *tcpDestination) Network() Network {
-	return "tcp"
+	return TCPNetwork
 }
 
 func (dest *tcpDestination) Address() Address {
@@ -74,8 +74,8 @@ type udpDestination struct {
 	port    Port
 }
 
-func (dest *udpDestination) Network() string {
+func (dest *udpDestination) Network() Network {
-	return "udp"
+	return UDPNetwork
 }
 
 func (dest *udpDestination) Address() Address {