QUIC "Message too long"
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- Dominant language
- Rust
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Description
Summary
With switch to QUIC I sometimes getting messages like this:
2023-10-14T07:49:21.668469Z sendmsg error: Os { code: 90, kind: Uncategorized, message: "Message too long" }, Transmit: { destination: 65.108.232.15:30533, src_ip: None, enc: Some(Ect0), len: 1420, segment_size: None }
Expected behavior
Should not exceed MTU
Actual behavior
Fails, likely due to exceeding MTU
Relevant log output
No response
Possible Solution
This likely happens because I have MTU set to 1420 (Wireguard is the reason) rather than more common 1500. If there is MTU expectation hardcoded somewhere it probably needs to change to MTU discovery instead. If MTU discovery is already present, it should not print warnings/errors.
Changing MTU back to 1500 resolves the issue.
Version
libp2p 0.52.3
libp2p-quic 0.9.2
Would you like to work on fixing this bug ?
Maybe
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the QUIC sendmsg failure with a WireGuard MTU of 1420 and compare it with MTU 1500. Trace where the reported packet length is selected and determine whether MTU discovery is involved; done means packets no longer fail with "Message too long" under the lower MTU.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- networking
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100