diff --git a/zebra-network/src/peer/connection.rs b/zebra-network/src/peer/connection.rs index d834ce877a6..f94090d2998 100644 --- a/zebra-network/src/peer/connection.rs +++ b/zebra-network/src/peer/connection.rs @@ -511,8 +511,32 @@ where .0 .lock() .expect("mutex should be unpoisoned"); - if guard.is_some() { - panic!("called fail_with on already-failed connection state"); + if let Some(original_error) = guard.clone() { + // A failed connection might experience further errors if we: + // 1. concurrently process two different messages + // 2. check for a failed state for the second message + // 3. fail the connection due to the first message + // 4. fail the connection due to the second message + // + // It's not clear: + // * if this is actually a bug, + // * how we can modify Zebra to avoid it. + // + // This warning can also happen due to these bugs: + // * we mark a connection as failed without using fail_with + // * we call fail_with without checking for a failed connection + // state + // + // See the original bug #1510, the initial fix #1531, and the later + // bug #1599. + warn!(?original_error, + new_error = ?e, + connection_state = ?self.state, + client_receiver = ?self.client_rx, + "calling fail_with on already-failed connection state: ignoring new error"); + // we don't need to clean up the connection, the original call to + // fail_with does that + return; } else { *guard = Some(e); }