Update locking to be interior to PeerPcb

tun/src/unix/mod.rs

@@ -1,5 +1,6 @@
 use std::{
     io::{Error, Read},
+    mem::MaybeUninit,
     os::fd::{AsRawFd, FromRawFd, IntoRawFd, RawFd},
 };
 
@@ -38,14 +39,19 @@ impl IntoRawFd for TunInterface {
     }
 }
 
+unsafe fn assume_init(buf: &[MaybeUninit<u8>]) -> &[u8] {
+    &*(buf as *const [MaybeUninit<u8>] as *const [u8])
+}
+
 impl TunInterface {
     #[throws]
     #[instrument]
-    pub fn recv(&mut self, buf: &mut [u8]) -> usize {
-        // there might be a more efficient way to implement this
-        let tmp_buf = &mut [0u8; 1500];
-        let len = self.socket.read(tmp_buf)?;
-        buf[..len - 4].copy_from_slice(&tmp_buf[4..len]);
+    pub fn recv(&self, buf: &mut [u8]) -> usize {
+        // Use IoVec to read directly into target buffer
+        let mut tmp_buf = [MaybeUninit::uninit(); 1500];
+        let len = self.socket.recv(&mut tmp_buf)?;
+        let result_buf = unsafe { assume_init(&tmp_buf[4..len]) };
+        buf[..len - 4].copy_from_slice(&result_buf);
         len - 4
     }