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/tcpprox.go

@@ -0,0 +1,146 @@
+package streamproxy
+
+import (
+	"errors"
+	"io"
+	"log"
+	"net"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+func isValidIP(ip string) bool {
+	parsedIP := net.ParseIP(ip)
+	return parsedIP != nil
+}
+
+func isValidPort(port string) bool {
+	portInt, err := strconv.Atoi(port)
+	if err != nil {
+		return false
+	}
+
+	if portInt < 1 || portInt > 65535 {
+		return false
+	}
+
+	return true
+}
+
+func connCopy(conn1 net.Conn, conn2 net.Conn, wg *sync.WaitGroup, accumulator *atomic.Int64) {
+	n, err := io.Copy(conn1, conn2)
+	if err != nil {
+		return
+	}
+	accumulator.Add(n) //Add to accumulator
+	conn1.Close()
+	log.Println("[←]", "close the connect at local:["+conn1.LocalAddr().String()+"] and remote:["+conn1.RemoteAddr().String()+"]")
+	//conn2.Close()
+	//log.Println("[←]", "close the connect at local:["+conn2.LocalAddr().String()+"] and remote:["+conn2.RemoteAddr().String()+"]")
+	wg.Done()
+}
+
+func forward(conn1 net.Conn, conn2 net.Conn, aTob *atomic.Int64, bToa *atomic.Int64) {
+	log.Printf("[+] start transmit. [%s],[%s] <-> [%s],[%s] \n", conn1.LocalAddr().String(), conn1.RemoteAddr().String(), conn2.LocalAddr().String(), conn2.RemoteAddr().String())
+	var wg sync.WaitGroup
+	// wait tow goroutines
+	wg.Add(2)
+	go connCopy(conn1, conn2, &wg, aTob)
+	go connCopy(conn2, conn1, &wg, bToa)
+	//blocking when the wg is locked
+	wg.Wait()
+}
+
+func (c *ProxyRelayConfig) accept(listener net.Listener) (net.Conn, error) {
+	conn, err := listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+
+	//Check if connection in blacklist or whitelist
+	if addr, ok := conn.RemoteAddr().(*net.TCPAddr); ok {
+		if !c.parent.Options.AccessControlHandler(conn) {
+			time.Sleep(300 * time.Millisecond)
+			conn.Close()
+			log.Println("[x]", "Connection from "+addr.IP.String()+" rejected by access control policy")
+			return nil, errors.New("Connection from " + addr.IP.String() + " rejected by access control policy")
+		}
+	}
+
+	log.Println("[√]", "accept a new client. remote address:["+conn.RemoteAddr().String()+"], local address:["+conn.LocalAddr().String()+"]")
+	return conn, err
+}
+
+func startListener(address string) (net.Listener, error) {
+	log.Println("[+]", "try to start server on:["+address+"]")
+	server, err := net.Listen("tcp", address)
+	if err != nil {
+		return nil, errors.New("listen address [" + address + "] faild")
+	}
+	log.Println("[√]", "start listen at address:["+address+"]")
+	return server, nil
+}
+
+/*
+	Forwarder Functions
+*/
+
+/*
+portA -> server
+server -> portB
+*/
+func (c *ProxyRelayConfig) Port2host(allowPort string, targetAddress string, stopChan chan bool) error {
+	listenerStartingAddr := allowPort
+	if isValidPort(allowPort) {
+		//number only, e.g. 8080
+		listenerStartingAddr = "0.0.0.0:" + allowPort
+	} else if strings.HasPrefix(allowPort, ":") && isValidPort(allowPort[1:]) {
+		//port number starting with :, e.g. :8080
+		listenerStartingAddr = "0.0.0.0" + allowPort
+	}
+
+	server, err := startListener(listenerStartingAddr)
+	if err != nil {
+		return err
+	}
+
+	targetAddress = strings.TrimSpace(targetAddress)
+
+	//Start stop handler
+	go func() {
+		<-stopChan
+		log.Println("[x]", "Received stop signal. Exiting Port to Host forwarder")
+		server.Close()
+	}()
+
+	//Start blocking loop for accepting connections
+	for {
+		conn, err := c.accept(server)
+		if err != nil {
+			if errors.Is(err, net.ErrClosed) {
+				//Terminate by stop chan. Exit listener loop
+				return nil
+			}
+			//Connection error. Retry
+			continue
+		}
+
+		go func(targetAddress string) {
+			log.Println("[+]", "start connect host:["+targetAddress+"]")
+			target, err := net.Dial("tcp", targetAddress)
+			if err != nil {
+				// temporarily unavailable, don't use fatal.
+				log.Println("[x]", "connect target address ["+targetAddress+"] faild. retry in ", c.Timeout, "seconds. ")
+				conn.Close()
+				log.Println("[←]", "close the connect at local:["+conn.LocalAddr().String()+"] and remote:["+conn.RemoteAddr().String()+"]")
+				time.Sleep(time.Duration(c.Timeout) * time.Second)
+				return
+			}
+			log.Println("[→]", "connect target address ["+targetAddress+"] success.")
+			forward(target, conn, &c.aTobAccumulatedByteTransfer, &c.bToaAccumulatedByteTransfer)
+		}(targetAddress)
+	}
+}