Commit remaining Burrow platform work

tun/src/tokio/mod.rs

@@ -33,7 +33,7 @@ impl TunInterface {
                 Ok(result) => return result,
                 Err(_would_block) => {
                     tracing::debug!("WouldBlock");
-                    continue
+                    continue;
                 }
             }
         }

tun/src/unix/apple/mod.rs

@@ -114,6 +114,10 @@ impl TunInterface {
         ifname_to_string(buf)
     }
 
+    pub(crate) fn packet_information_size(&self) -> usize {
+        4
+    }
+
     #[throws]
     #[instrument]
     fn ifreq(&self) -> sys::ifreq {

tun/src/unix/linux/mod.rs

@@ -73,6 +73,21 @@ impl TunInterface {
         ifname_to_string(iff.ifr_name)
     }
 
+    pub(crate) fn packet_information_size(&self) -> usize {
+        let mut iff = unsafe { mem::zeroed::<libc::ifreq>() };
+        match unsafe { sys::tun_get_iff(self.socket.as_raw_fd(), &mut iff) } {
+            Ok(_) => {
+                let flags = unsafe { iff.ifr_ifru.ifru_flags };
+                if flags & libc::IFF_NO_PI as i16 != 0 {
+                    0
+                } else {
+                    4
+                }
+            }
+            Err(_) => 4,
+        }
+    }
+
     #[throws]
     #[instrument]
     fn ifreq(&self) -> sys::ifreq {
@@ -283,6 +298,16 @@ impl TunInterface {
     #[throws]
     #[instrument]
     pub fn send(&self, buf: &[u8]) -> usize {
-        self.socket.send(buf)?
+        let len = unsafe {
+            libc::write(
+                self.as_raw_fd(),
+                buf.as_ptr().cast::<libc::c_void>(),
+                buf.len(),
+            )
+        };
+        if len < 0 {
+            Err(Error::last_os_error())?;
+        }
+        len as usize
     }
 }

tun/src/unix/mod.rs

@@ -48,12 +48,26 @@ impl TunInterface {
     #[throws]
     #[instrument]
     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
+        let packet_information_size = self.packet_information_size();
+        let mut tmp_buf = [MaybeUninit::uninit(); 1504];
+        let len = unsafe {
+            libc::read(
+                self.as_raw_fd(),
+                tmp_buf.as_mut_ptr().cast::<libc::c_void>(),
+                tmp_buf.len(),
+            )
+        };
+        if len < 0 {
+            Err(Error::last_os_error())?;
+        }
+        let len = len as usize;
+        if len < packet_information_size {
+            return 0;
+        }
+
+        let result_buf = unsafe { assume_init(&tmp_buf[packet_information_size..len]) };
+        buf[..len - packet_information_size].copy_from_slice(result_buf);
+        len - packet_information_size
     }
 
     #[throws]