1 files changed, 43 insertions, 0 deletions
diff --git a/src/types/tun.rs b/src/types/tun.rs
new file mode 100644
index 0000000..72caa71
--- /dev/null
+++ b/src/types/tun.rs
@@ -0,0 +1,43 @@
+use std::error;
+
+pub trait Tun: Send + Sync {
+    type Error: error::Error;
+
+    /// Returns the MTU of the device
+    ///
+    /// This function needs to be efficient (called for every read).
+    /// The goto implementation stragtegy is to .load an atomic variable,
+    /// then use e.g. netlink to update the variable in a seperate thread.
+    ///
+    /// # Returns
+    ///
+    /// The MTU of the interface in bytes
+    fn mtu(&self) -> usize;
+
+    /// Reads an IP packet into dst[offset:] from the tunnel device
+    ///
+    /// The reason for providing space for a prefix
+    /// is to efficiently accommodate platforms on which the packet is prefaced by a header.
+    /// This space is later used to construct the transport message inplace.
+    ///
+    /// # Arguments
+    ///
+    /// - dst: Destination buffer (enough space for MTU bytes + header)
+    /// - offset: Offset for the beginning of the IP packet
+    ///
+    /// # Returns
+    ///
+    /// The size of the IP packet (ignoring the header) or an std::error::Error instance:
+    fn read(&self, dst: &mut [u8], offset: usize) -> Result<usize, Self::Error>;
+
+    /// Writes an IP packet to the tunnel device
+    ///
+    /// # Arguments
+    ///
+    /// - src: Buffer containing the IP packet to be written
+    ///
+    /// # Returns
+    ///
+    /// Unit type or an error
+    fn write(&self, src: &[u8]) -> Result<(), Self::Error>;
+}