Fix counterparty channel id unwrap (#220)

* add failing test

* bug fix

* changelog

.changelog/unreleased/bug-fixes/219-counterparty-unwrap.md

@@ -0,0 +1,2 @@
+- Don't panic on user input in channel proof verification
+  ([#219](https://github.com/cosmos/ibc-rs/issues/219))

crates/ibc/src/core/ics04_channel/error.rs

@@ -251,7 +251,6 @@ define_error! {
             },
 
         InvalidCounterpartyChannelId
-            [ ValidationError ]
             | _ | { "Invalid channel id in counterparty" },
 
         InvalidChannelState

crates/ibc/src/core/ics04_channel/handler/chan_open_try.rs

@@ -283,4 +283,46 @@ mod tests {
             }
         }
     }
+
+    /// Addresses [issue 219](https://github.com/cosmos/ibc-rs/issues/219)
+    #[test]
+    fn chan_open_try_invalid_counterparty_channel_id() {
+        let proof_height = 10;
+        let conn_id = ConnectionId::new(2);
+        let client_id = ClientId::new(mock_client_type(), 45).unwrap();
+
+        // This is the connection underlying the channel we're trying to open.
+        let conn_end = ConnectionEnd::new(
+            ConnectionState::Open,
+            client_id.clone(),
+            ConnectionCounterparty::try_from(get_dummy_raw_counterparty()).unwrap(),
+            get_compatible_versions(),
+            ZERO_DURATION,
+        );
+
+        // We're going to test message processing against this message.
+        // Note: we make the counterparty's channel_id `None`.
+        let mut msg =
+            MsgChannelOpenTry::try_from(get_dummy_raw_msg_chan_open_try(proof_height)).unwrap();
+        msg.channel.remote.channel_id = None;
+
+        let chan_id = ChannelId::new(24);
+        let hops = vec![conn_id.clone()];
+        msg.channel.connection_hops = hops;
+
+        let chan_end = ChannelEnd::new(
+            State::Init,
+            *msg.channel.ordering(),
+            msg.channel.counterparty().clone(),
+            msg.channel.connection_hops().clone(),
+            msg.channel.version().clone(),
+        );
+        let context = MockContext::default()
+            .with_client(&client_id, Height::new(0, proof_height).unwrap())
+            .with_connection(conn_id, conn_end)
+            .with_channel(msg.port_id.clone(), chan_id, chan_end);
+
+        // Makes sure we don't crash
+        let _ = chan_open_try::process(&context, &msg);
+    }
 }

crates/ibc/src/core/ics04_channel/handler/verify.rs

@@ -38,7 +38,10 @@ pub fn verify_channel_proofs<Ctx: ChannelReader>(
             proofs.object_proof(),
             consensus_state.root(),
             channel_end.counterparty().port_id(),
-            channel_end.counterparty().channel_id().unwrap(),
+            channel_end
+                .counterparty()
+                .channel_id()
+                .ok_or_else(Error::invalid_counterparty_channel_id)?,
             expected_chan,
         )
         .map_err(Error::verify_channel_failed)

crates/ibc/src/core/ics04_channel/msgs/chan_open_try.rs

@@ -102,7 +102,7 @@ impl TryFrom<RawMsgChannelOpenTry> for MsgChannelOpenTry {
         };
 
         msg.validate_basic()
-            .map_err(ChannelError::invalid_counterparty_channel_id)?;
+            .map_err(|_| ChannelError::invalid_counterparty_channel_id())?;
 
         Ok(msg)
     }