Unknown Protocol Operation after reconnect when sending message#2
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basbl wants to merge 2 commits into
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Unknown Protocol Operation after reconnect when sending message#2basbl wants to merge 2 commits into
basbl wants to merge 2 commits into
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When a message is larger than the connection packet size it is written to the socket with several fwrite() calls. If the socket dies *after* the first chunk has been written, Connection::sendMessage() catches the error, reconnects, and resumes the write loop. The byte offset counter $total must be reset to 0 so the *whole* message is resent on the fresh socket. Before the fix $total kept its stale value, so only the tail of the PUB command was sent on the new connection. The NATS server then saw the tail bytes as a fresh protocol command and answered `-ERR 'Unknown Protocol Operation'`.
MattiasAng
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Jun 25, 2026
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Before merging we need to decide whether we want to keep the notes somewhere in a docs folder. |
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I'd say move to docs/changelogs. |
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While investigating a breaching SLO for eConsent caused by Unknown Protocol Operations I ended up here.
The investigation led me to the
Connection::sendMessage-method which after a reconnect does not write the full message to the socket as the running total is not reset.To me this makes sense as it does look like an obvious oversight. Looking for feedback!
Last commit contains the notes on the investigation. We can decide to keep this if we want and give it a place in the repo (docs) or drop it.