Countermeasure that fixes #1038

informalsystems · Jun 8, 2021 · 1098ac0 · 1098ac0
1 parent 2b84667
commit 1098ac0
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Showing 2 changed files with 52 additions and 3 deletions.
diff --git a/relayer/src/channel.rs b/relayer/src/channel.rs
@@ -420,12 +420,24 @@ impl Channel {
         let a_channel = self
             .src_chain()
             .query_channel(&self.src_port_id(), src_channel_id, Height::zero())
-            .map_err(|_| ChannelError::Failed("Failed to query source chain".into()))?;
+            .map_err(|_| {
+                ChannelError::Failed(
+                    format!("failed to query source chain {}", self.src_chain().id()).into(),
+                )
+            })?;
 
         let b_channel = self
             .dst_chain()
             .query_channel(&self.dst_port_id(), dst_channel_id, Height::zero())
-            .map_err(|_| ChannelError::Failed("Failed to query destination chain".into()))?;
+            .map_err(|_| {
+                ChannelError::Failed(
+                    format!(
+                        "failed to query destination chain {}",
+                        self.dst_chain().id()
+                    )
+                    .into(),
+                )
+            })?;
 
         match (a_channel.state(), b_channel.state()) {
             (State::Init, State::TryOpen) | (State::TryOpen, State::TryOpen) => {
@@ -457,7 +469,7 @@ impl Channel {
                 info!("done {} => {:#?}\n", self.src_chain().id(), event)
             }
             (State::Open, State::Open) => {
-                info!("Channel handshake finished for {:#?}\n", self);
+                info!("channel handshake finished for {:#?}\n", self);
             }
             _ => { /* TODO channel close */ }
         }

diff --git a/relayer/src/link.rs b/relayer/src/link.rs
@@ -1634,6 +1634,43 @@ impl Link {
             )));
         }
 
+        // Check that the counterparty details on the destination chain matches the source chain
+        let b_channel = b_chain
+            .query_channel(
+                &a_channel.counterparty().port_id,
+                &b_channel_id,
+                Height::default(),
+            )
+            .map_err(|e| {
+                LinkError::Failed(format!(
+                    "channel/port {}/{} does not exist on destination chain {}; context={}",
+                    b_channel_id,
+                    a_channel.counterparty().port_id,
+                    b_chain.id(),
+                    e
+                ))
+            })?;
+        match b_channel.counterparty().channel_id.clone() {
+            Some(actual_a_channel_id) => {
+                if actual_a_channel_id.ne(a_channel_id)
+                    || b_channel.counterparty().port_id != opts.src_port_id
+                {
+                    return Err(LinkError::Failed(format!("conflicting link configuration: channel/port {}/{} on destination chain {} does not point back to the source chain {}:{}/{} (but points to {}/{})",
+                                                         b_channel_id, a_channel.counterparty().port_id, b_chain.id(), a_chain.id(),
+                                                         a_channel_id, opts.src_port_id, actual_a_channel_id, b_channel.counterparty().port_id)));
+                }
+            }
+            None => {
+                return Err(LinkError::Failed(format!(
+                    "the channel/port {}/{} on destination chain {} has no counterparty channel set",
+                    b_channel_id,
+                    a_channel.counterparty().port_id,
+                    b_chain.id()
+                )));
+            }
+        }
+
+        // Check the underlying connection
         let a_connection_id = a_channel.connection_hops()[0].clone();
         let a_connection = a_chain.query_connection(&a_connection_id, Height::zero())?;