[client] Eliminate UDP proxy in user-space mode (#2712)

In the case of user space WireGuard mode, use in-memory proxy between the TURN/Relay connection and the WireGuard Bind. We keep the UDP proxy and eBPF proxy for kernel mode.

The key change is the new wgproxy/bind and the iface/bind/ice_bind changes. Everything else is just to fulfill the dependencies.

client/iface/wgproxy/ebpf/proxy_test.go

@@ -0,0 +1,56 @@
+//go:build linux && !android
+
+package ebpf
+
+import (
+	"testing"
+)
+
+func TestWGEBPFProxy_connStore(t *testing.T) {
+	wgProxy := NewWGEBPFProxy(1)
+
+	p, _ := wgProxy.storeTurnConn(nil)
+	if p != 1 {
+		t.Errorf("invalid initial port: %d", wgProxy.lastUsedPort)
+	}
+
+	numOfConns := 10
+	for i := 0; i < numOfConns; i++ {
+		p, _ = wgProxy.storeTurnConn(nil)
+	}
+	if p != uint16(numOfConns)+1 {
+		t.Errorf("invalid last used port: %d, expected: %d", p, numOfConns+1)
+	}
+	if len(wgProxy.turnConnStore) != numOfConns+1 {
+		t.Errorf("invalid store size: %d, expected: %d", len(wgProxy.turnConnStore), numOfConns+1)
+	}
+}
+
+func TestWGEBPFProxy_portCalculation_overflow(t *testing.T) {
+	wgProxy := NewWGEBPFProxy(1)
+
+	_, _ = wgProxy.storeTurnConn(nil)
+	wgProxy.lastUsedPort = 65535
+	p, _ := wgProxy.storeTurnConn(nil)
+
+	if len(wgProxy.turnConnStore) != 2 {
+		t.Errorf("invalid store size: %d, expected: %d", len(wgProxy.turnConnStore), 2)
+	}
+
+	if p != 2 {
+		t.Errorf("invalid last used port: %d, expected: %d", p, 2)
+	}
+}
+
+func TestWGEBPFProxy_portCalculation_maxConn(t *testing.T) {
+	wgProxy := NewWGEBPFProxy(1)
+
+	for i := 0; i < 65535; i++ {
+		_, _ = wgProxy.storeTurnConn(nil)
+	}
+
+	_, err := wgProxy.storeTurnConn(nil)
+	if err == nil {
+		t.Errorf("invalid turn conn store calculation")
+	}
+}