[stack] skeleton for ENTRY_UDP

quicktap/src/stack/entry_udp.rs

@@ -3,6 +3,7 @@
 use std::error::Error;
 use std::net::SocketAddr;
 use crate::device::QTInterface;
+use crate::drivers::error::DriverError;
 use crate::stack::{PacketProcessingStage};
 
 /// The ENTRY stage of the packet processing stack for UDP packets
@@ -10,6 +11,29 @@ pub struct UDPPacketEntryStage {}
 
 impl PacketProcessingStage for UDPPacketEntryStage {
     fn process_packet(pkt: Vec<u8>, from: &SocketAddr, interface: &QTInterface) -> Result<(), Box<dyn Error>> {
+        // packet types are determined by the first byte of the packet
+        // if it is not a known packet type, return an error and drop the packet
+        match pkt.first().ok_or(DriverError::InvalidPacketTypeRecvOnInterface)? {
+            1 => Self::handle_new_handshake(pkt, from, interface),
+            2 => Self::handle_handshake_response(pkt, from, interface),
+            3 => Self::handle_handshake_cookie_reply(pkt, from, interface),
+            4 => Self::handle_data_packet(pkt, from, interface),
+            _ => Err(DriverError::InvalidPacketTypeRecvOnInterface.into())
+        }
+    }
+}
+
+impl UDPPacketEntryStage {
+    fn handle_new_handshake(pkt: Vec<u8>, from: &SocketAddr, interface: &QTInterface) -> Result<(), Box<dyn Error>> {
+        unimplemented!();
+    }
+    fn handle_handshake_response(pkt: Vec<u8>, from: &SocketAddr, interface: &QTInterface) -> Result<(), Box<dyn Error>> {
+        unimplemented!();
+    }
+    fn handle_handshake_cookie_reply(pkt: Vec<u8>, from: &SocketAddr, interface: &QTInterface) -> Result<(), Box<dyn Error>> {
+        unimplemented!();
+    }
+    fn handle_data_packet(pkt: Vec<u8>, from: &SocketAddr, interface: &QTInterface) -> Result<(), Box<dyn Error>> {
         unimplemented!();
     }
 }