Added stream proxy UDP support

+ Added UDP support #147 (wip)
+ Updated structure for proxy storage
+ Renamed TCPprox module to streamproxy
+ Added multi selection for white / blacklist #176

src/mod/streamproxy/udpprox.go

@@ -0,0 +1,157 @@
+package streamproxy
+
+import (
+	"errors"
+	"log"
+	"net"
+	"strings"
+	"time"
+)
+
+/*
+	UDP Proxy Module
+*/
+
+// Information maintained for each client/server connection
+type udpClientServerConn struct {
+	ClientAddr *net.UDPAddr // Address of the client
+	ServerConn *net.UDPConn // UDP connection to server
+}
+
+// Generate a new connection by opening a UDP connection to the server
+func createNewUDPConn(srvAddr, cliAddr *net.UDPAddr) *udpClientServerConn {
+	conn := new(udpClientServerConn)
+	conn.ClientAddr = cliAddr
+	srvudp, err := net.DialUDP("udp", nil, srvAddr)
+	if err != nil {
+		return nil
+	}
+	conn.ServerConn = srvudp
+	return conn
+}
+
+// Start listener, return inbound lisener and proxy target UDP address
+func initUDPConnections(listenAddr string, targetAddress string) (*net.UDPConn, *net.UDPAddr, error) {
+	// Set up Proxy
+	saddr, err := net.ResolveUDPAddr("udp", listenAddr)
+	if err != nil {
+		return nil, nil, err
+	}
+	inboundConn, err := net.ListenUDP("udp", saddr)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	log.Println("[UDP] Proxy listening on " + listenAddr)
+
+	outboundConn, err := net.ResolveUDPAddr("udp", targetAddress)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return inboundConn, outboundConn, nil
+}
+
+// Go routine which manages connection from server to single client
+func (c *ProxyRelayConfig) RunUDPConnectionRelay(conn *udpClientServerConn, lisenter *net.UDPConn) {
+	var buffer [1500]byte
+	for {
+		// Read from server
+		n, err := conn.ServerConn.Read(buffer[0:])
+		if err != nil {
+			if errors.Is(err, net.ErrClosed) {
+				return
+			}
+			continue
+		}
+		// Relay it to client
+		_, err = lisenter.WriteToUDP(buffer[0:n], conn.ClientAddr)
+		if err != nil {
+			continue
+		}
+
+	}
+}
+
+// Close all connections that waiting for read from server
+func (c *ProxyRelayConfig) CloseAllUDPConnections() {
+	c.udpClientMap.Range(func(clientAddr, clientServerConn interface{}) bool {
+		conn := clientServerConn.(*udpClientServerConn)
+		conn.ServerConn.Close()
+		return true
+	})
+}
+
+func (c *ProxyRelayConfig) ForwardUDP(address1, address2 string, stopChan chan bool) error {
+	//By default the incoming listen Address is int
+	//We need to add the loopback address into it
+	if isValidPort(address1) {
+		//Port number only. Missing the : in front
+		address1 = ":" + address1
+	}
+	if strings.HasPrefix(address1, ":") {
+		//Prepend 127.0.0.1 to the address
+		address1 = "127.0.0.1" + address1
+	}
+
+	lisener, targetAddr, err := initUDPConnections(address1, address2)
+	if err != nil {
+		return err
+	}
+
+	go func() {
+		//Stop channel receiver
+		for {
+			select {
+			case <-stopChan:
+				//Stop signal received
+				//Stop server -> client forwarder
+				c.CloseAllUDPConnections()
+				//Stop client -> server forwarder
+				//Force close, will terminate ReadFromUDP for inbound listener
+				lisener.Close()
+				return
+			default:
+				time.Sleep(100 * time.Millisecond)
+			}
+		}
+
+	}()
+
+	var buffer [1500]byte
+	for {
+		n, cliaddr, err := lisener.ReadFromUDP(buffer[0:])
+		if err != nil {
+			if errors.Is(err, net.ErrClosed) {
+				//Proxy stopped
+				return nil
+			}
+			continue
+		}
+		c.aTobAccumulatedByteTransfer.Add(int64(n))
+		saddr := cliaddr.String()
+		rawConn, found := c.udpClientMap.Load(saddr)
+		var conn *udpClientServerConn
+		if !found {
+			conn = createNewUDPConn(targetAddr, cliaddr)
+			if conn == nil {
+				continue
+			}
+			c.udpClientMap.Store(saddr, conn)
+			log.Println("[UDP] Created new connection for client " + saddr)
+			// Fire up routine to manage new connection
+			go c.RunUDPConnectionRelay(conn, lisener)
+
+		} else {
+			log.Println("[UDP] Found connection for client " + saddr)
+			conn = rawConn.(*udpClientServerConn)
+		}
+
+		// Relay to server
+		_, err = conn.ServerConn.Write(buffer[0:n])
+		if err != nil {
+			continue
+		}
+
+	}
+}