node: Make sure to only read packet-line header

If there is an unexpected error, eg. `BrokenPipe` in the upload process
process of the worker, we may have more than four bytes to read from the
remote socket. This change ensures that we don't attempt to read more
into a buffer of size `4`.

radicle-node/src/worker.rs

@@ -174,7 +174,7 @@ impl<G: Signer + Ecdh + 'static> Worker<G> {
                         log::debug!(target: "worker", "Waiting for `done` packet from remote..");
 
                         let mut header = [0; pktline::HEADER_LEN];
-                        if let Ok(pktline::Packetline::Done) = pktline_r.read_pktline(&mut header) {
+                        if let Ok(()) = pktline_r.read_done_pktline(&mut header) {
                             (WireSession::from_split_io(stream_r, stream_w), Err(err))
                         } else {
                             log::error!(
@@ -460,6 +460,16 @@ pub mod pktline {
             Ok((cmd, Vec::from(&pktline[..length])))
         }
 
+        /// Parse a `done` packet-line.
+        pub fn read_done_pktline(&mut self, buf: &mut [u8]) -> io::Result<()> {
+            self.read_exact(&mut buf[..HEADER_LEN])?;
+
+            if &buf[..HEADER_LEN] == DONE_PKT {
+                return Ok(());
+            }
+            Err(io::ErrorKind::InvalidInput.into())
+        }
+
         /// Parse a Git packet-line.
         pub fn read_pktline(&mut self, buf: &mut [u8]) -> io::Result<Packetline> {
             self.read_exact(&mut buf[..HEADER_LEN])?;