web: validate the flag configuration in Serve and ServeMultiple - #439
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ListenAndServe validates its FlagConfig before using it, but Serve and ServeMultiple went straight to dereferencing flags.WebConfigFile. Both are exported for callers that create their own listeners, and such a caller builds a FlagConfig by hand rather than getting one from kingpinflag, so passing one without WebConfigFile set is an easy mistake. It crashed the process with a nil pointer dereference instead of returning ErrMissingFlag. Check the flags in both, using a narrower check than checkFlags. The listener fields are deliberately not required here: the caller supplies the listener, so demanding a listen address or the systemd socket flag would reject a legitimate configuration. checkFlags keeps requiring them for ListenAndServe, which does create the listeners itself, and now shares the web config half of the validation. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Signed-off-by: Manuel Rüger <manuel@rueg.eu>
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ListenAndServevalidates itsFlagConfigbefore using it, butServeandServeMultiplego straight to dereferencingflags.WebConfigFile.Both are exported for callers that create their own listeners, and such a caller builds a
FlagConfigby hand rather than getting one fromkingpinflag, so passing one withoutWebConfigFileset is an easy mistake. It crashes the process instead of returningErrMissingFlag:Change
Check the flags in both, using a narrower check than
checkFlags. The listener fields are deliberately not required here: the caller supplies the listener, so demanding a listen address or the systemd socket flag would reject a legitimate configuration.checkFlagskeeps requiring them forListenAndServe, which does create the listeners, and now shares the web-config half of the validation.🤖 Generated with Claude Code