Fix a race condition when a client closes the connection #34
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cure
reviewed
Jun 8, 2021
cure
reviewed
Jun 8, 2021
| now := time.Now().UTC() | ||
| m.LastSeen = &now | ||
| db.Save(&m) | ||
| h.pollMu.Lock() |
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don't we want to keep this call to Lock() ?
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I moved it a few lines up, to cover also the DB access... Not really needed though...
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If it's not needed, let's keep it where it was to keep the lock as short as possible? LGTM otherwise!
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Fully agreed. Sent another commit and proceeding with merge :)
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The issue occurs when a client closes the connection. We receive cancellation of the gin context here https://github.com/juanfont/headscale/blob/main/api.go#L322. Because of the
defer close(update)in PollNetMapHandler we were closing the channel outside the mutex so it can happen that a new client arrives and tries to notify its peers - including the one that just closed the connection https://github.com/juanfont/headscale/blob/main/api.go#L288Fixes #32.