支持tap网卡,优化tun网卡配置

switch/win-tun-tap/src/tun/packet.rs

@@ -0,0 +1,64 @@
+
+use crate::TunDevice;
+
+pub(crate) enum Kind {
+    SendPacketPending,
+    //Send packet type, but not sent yet
+    SendPacketSent,
+    //Send packet type - sent
+    ReceivePacket,
+}
+
+/// Represents a wintun packet
+pub struct TunPacket<'a> {
+    pub(crate) kind: Kind,
+    pub(crate) size:usize,
+    pub(crate) bytes_ptr: *const u8,
+
+    //Share ownership of session to prevent the session from being dropped before packets that
+    //belong to it
+    pub(crate) tun_device: Option<&'a TunDevice>,
+}
+
+impl <'a>TunPacket<'a> {
+    /// Returns the bytes this packet holds as &mut.
+    /// The lifetime of the bytes is tied to the lifetime of this packet.
+    pub fn bytes_mut(&mut self) -> &mut [u8] {
+        unsafe { std::slice::from_raw_parts_mut(self.bytes_ptr as *mut u8, self.size) }
+    }
+
+    /// Returns an immutable reference to the bytes this packet holds.
+    /// The lifetime of the bytes is tied to the lifetime of this packet.
+    pub fn bytes(&self) -> &[u8] {
+        unsafe { std::slice::from_raw_parts(self.bytes_ptr,self.size) }
+    }
+}
+
+impl <'a>Drop for TunPacket<'a> {
+    fn drop(&mut self) {
+        match self.kind {
+            Kind::ReceivePacket => {
+                unsafe {
+                    //SAFETY:
+                    //
+                    //  1. We share ownership of the session therefore it hasn't been dropped yet
+                    //  2. Bytes is valid because each packet holds exclusive access to a region of the
+                    //     ring buffer that the wintun session owns. We return that region of
+                    //     memory back to wintun here
+                    let tun_device = self.tun_device.unwrap();
+                    tun_device.win_tun
+                        .WintunReleaseReceivePacket(tun_device.session, self.bytes_ptr)
+                };
+            }
+            Kind::SendPacketPending => {
+                //If someone allocates a packet with session.allocate_send_packet() and then it is
+                //dropped without being sent, this will hold up the send queue because wintun expects
+                //that every allocated packet is sent
+                panic!("Packet was never sent!");
+            }
+            Kind::SendPacketSent => {
+                //Nop
+            }
+        }
+    }
+}