Support no-proxy mode connection mode (#245)

When one of the peers has a static public host IP
or both peers are in the same local network
we establish a direct Wireguard connection
bypassing proxy usage.
This helps reduce FD usage and improves
performance.

client/internal/proxy/dummy.go

@@ -66,3 +66,7 @@ func (p *DummyProxy) Start(remoteConn net.Conn) error {
 
 	return nil
 }
+
+func (p *DummyProxy) Type() Type {
+	return TypeDummy
+}

client/internal/proxy/noproxy.go

@@ -0,0 +1,49 @@
+package proxy
+
+import (
+	log "github.com/sirupsen/logrus"
+	"github.com/wiretrustee/wiretrustee/iface"
+	"net"
+)
+
+// NoProxy is used when there is no need for a proxy between ICE and Wireguard.
+// This is possible in either of these cases:
+// - peers are in the same local network
+// - one of the peers has a public static IP (host)
+// NoProxy will just update remote peer with a remote host and fixed Wireguard port (r.g. 51820).
+// In order NoProxy to work, Wireguard port has to be fixed for the time being.
+type NoProxy struct {
+	config Config
+}
+
+func NewNoProxy(config Config) *NoProxy {
+	return &NoProxy{config: config}
+}
+
+func (p *NoProxy) Close() error {
+	// noop
+	return nil
+}
+
+// Start just updates Wireguard peer with the remote IP and default Wireguard port
+func (p *NoProxy) Start(remoteConn net.Conn) error {
+
+	log.Debugf("using NoProxy while connecting to peer %s", p.config.RemoteKey)
+	addr, err := net.ResolveUDPAddr("udp", remoteConn.RemoteAddr().String())
+	if err != nil {
+		return err
+	}
+	addr.Port = iface.DefaultWgPort
+	err = p.config.WgInterface.UpdatePeer(p.config.RemoteKey, p.config.AllowedIps, DefaultWgKeepAlive,
+		addr, p.config.PreSharedKey)
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (p *NoProxy) Type() Type {
+	return TypeNoProxy
+}

client/internal/proxy/proxy.go

@@ -10,6 +10,14 @@ import (
 
 const DefaultWgKeepAlive = 25 * time.Second
 
+type Type string
+
+const (
+	TypeNoProxy   Type = "NoProxy"
+	TypeWireguard Type = "Wireguard"
+	TypeDummy     Type = "Dummy"
+)
+
 type Config struct {
 	WgListenAddr string
 	RemoteKey    string
@@ -22,4 +30,5 @@ type Proxy interface {
 	io.Closer
 	// Start creates a local remoteConn and starts proxying data from/to remoteConn
 	Start(remoteConn net.Conn) error
+	Type() Type
 }

client/internal/proxy/wireguard.go

@@ -122,3 +122,7 @@ func (p *WireguardProxy) proxyToLocal() {
 		}
 	}
 }
+
+func (p *WireguardProxy) Type() Type {
+	return TypeWireguard
+}