introducing the RDT protocol

README.md

@@ -8,6 +8,7 @@ Another p2p network library in Go
 - Full support for IPv4/IPv6 dual stack
 - Easy-to-use library (net.PacketConn) 
 - **Transport layer security (curve25519 & chacha20poly1305 for end-to-end encryption)**
+- [RDT](https://github.com/rkonfj/peerguard/tree/main/rdt) protocol for reliable data transfer  
 - Cross-platform compatibility (linux/windows/macOS/iOS/android)
 
 ## Get Started

rdt/README.md

@@ -0,0 +1,44 @@
+# RDT
+
+a Reliable Data Transfer protocol.
+
+### Example
+**Server**
+```go
+packetConn, err := net.ListenPacket("udp", "192.168.3.99:22334")
+if err != nil {
+    panic(err)
+}
+listener, err := rdt.Listen(packetConn)
+if err != nil {
+    panic(err)
+}
+
+for {
+    conn, err := listener.Accept()
+    if err != nil {
+        panic(err)
+    }
+    handle(conn)
+}
+```
+**Client**
+```go
+packetConn, err := net.ListenPacket("udp", "192.168.3.98:22335")
+if err != nil {
+    panic(err)
+}
+listener, err := rdt.Listen(packetConn)
+if err != nil {
+    panic(err)
+}
+
+conn, err := listener.OpenStream(&net.UDPAddr{
+    IP:   net.ParseIP("192.168.3.99"),
+    Port: 22334,
+})
+if err != nil {
+    panic(err)
+}
+...
+```