Reinstate ChanCell as a meaningful type.

tor-proto/src/chancell.rs

@@ -11,7 +11,6 @@
 
 pub mod codec;
 pub mod msg;
-use bytes;
 use caret::caret_int;
 
 /// The amount of data sent in a fixed-length cell.
@@ -137,27 +136,26 @@ impl ChanCmd {
             _ => true,
         }
     }
+    pub fn accepts_circid_val(self, id: CircID) -> bool {
+        if self.is_recognized() {
+            self.allows_circid() == (id == 0.into())
+        } else {
+            true
+        }
+    }
 }
 
-/// A single cell extracted from, or encodeable onto, a channel.
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct ChanCell {
-    circ: CircID,
-    cmd: ChanCmd,
-    body: bytes::Bytes,
+    circid: CircID,
+    msg: msg::ChannelMessage,
 }
 
 impl ChanCell {
-    /// Return the cell's circuit ID.
     pub fn get_circid(&self) -> CircID {
-        self.circ
+        self.circid
     }
-    /// Return the cell's channel ID
-    pub fn get_cmd(&self) -> ChanCmd {
-        self.cmd
-    }
-    /// Return the body of this cell.
-    pub fn get_body(&self) -> &bytes::Bytes {
-        &self.body
+    pub fn get_msg(&self) -> &msg::ChannelMessage {
+        &self.msg
     }
 }

tor-proto/src/chancell/codec.rs

@@ -1,7 +1,4 @@
-use crate::chancell::{
-    msg::{ChanMsg, ChannelMessage},
-    ChanCmd, CircID,
-};
+use crate::chancell::{msg::ChanMsg, ChanCell, ChanCmd, CircID};
 use crate::crypto::cell::CELL_BODY_LEN;
 use arrayref::{array_mut_ref, array_ref};
 use bytes;
@@ -34,11 +31,12 @@ pub struct ChannelCodec {
 }
 
 impl futures_codec::Encoder for ChannelCodec {
-    type Item = (CircID, ChannelMessage);
+    type Item = ChanCell;
     type Error = Error;
 
     fn encode(&mut self, item: Self::Item, dst: &mut bytes::BytesMut) -> Result<(), Self::Error> {
-        let (circid, msg) = item;
+        let circid = item.get_circid();
+        let msg = item.get_msg();
         let cmd = msg.get_cmd();
         dst.write_u32(circid.into());
         dst.write_u8(cmd.into());
@@ -69,7 +67,7 @@ impl futures_codec::Encoder for ChannelCodec {
 }
 
 impl futures_codec::Decoder for ChannelCodec {
-    type Item = (CircID, ChannelMessage);
+    type Item = ChanCell;
     type Error = Error;
 
     fn decode(&mut self, src: &mut bytes::BytesMut) -> Result<Option<Self::Item>, Self::Error> {
@@ -91,9 +89,13 @@ impl futures_codec::Decoder for ChannelCodec {
 
         let cell = src.split_to(cell_len).freeze();
         let mut r = Reader::from_bytes(&cell);
-        let circid = r.take_u32()?.into();
+        let circid: CircID = r.take_u32()?.into();
         r.advance(if varcell { 1 } else { 3 })?;
         let msg = r.extract()?;
-        Ok(Some((circid, msg)))
+
+        if !cmd.accepts_circid_val(circid) {
+            return Err(Error::Misc());
+        }
+        Ok(Some(ChanCell { circid, msg }))
     }
 }