Avoid segfault for anonymous clients with macaroons

[jthiltges]

Don't dereference a null sentryPtr Closes #38

[djw8605]

If the username is "", would it always hit this line:

https://github.com/opensciencegrid/xrootd-multiuser/blob/642a8f2843b27e5c76d7d872cf75801e68be72a1/src/UserSentry.hh#L125-L131

[jthiltges]

Thanks for pointing out that mistake. I reworked things a little. I do like having anonymous access logged differently from lookup failures (and avoiding the overhead).

Note that I still need to compile and test this (the reason for marking it draft).

[djw8605]

Let me know when you have had a chance to compile and test.

[jthiltges]

@djw8605 I've built xrootd-multiuser with this patch, and it's running on red-xfer13.unl.edu. Initial testing looks OK. Anonymous and authenticated requests seem OK.

[matyasselmeci]

Is this still an issue?

[jthiltges]

It's still reproducible with the example in #38

[root@red-xfer13 ~]# rpm -q xrootd xrootd-multiuser
xrootd-5.6.2-2.3.osg36.el8.x86_64
xrootd-multiuser-2.1.3-1.3.osg36.el8.x86_64

[root@red-xfer13 ~]# tail -0f /var/log/messages
Nov 13 17:19:36 red-xfer13.unl.edu kernel: xrootd[1622077]: segfault at 4 ip 00007f83cc9f0585 sp 00007f83d34e3fc0 error 4 in libXrdMultiuser-5.so[7f83cc9e3000+1a000]
Nov 13 17:19:36 red-xfer13.unl.edu kernel: Code: ff 0f 85 59 ff ff ff e9 59 ff ff ff f3 0f 1e fa eb 92 f3 0f 1e fa 49 89 c4 e9 d4 fe ff ff 48 c7 84 24 90 00 00 00 00 00 00 00 <8b> 04 25 04 00 00 00 0f 0b f3 0f 1e fa 49 89 c4 e9 bb fe ff ff 66
Nov 13 17:19:36 red-xfer13.unl.edu systemd[1]: xrootd-privileged@clustered.service: Main process exited, code=killed, status=11/SEGV
Nov 13 17:19:36 red-xfer13.unl.edu systemd[1]: xrootd-privileged@clustered.service: Failed with result 'signal'.

[matyasselmeci]

Derek, do you think you can take a look in the next few days? I was about to cut a release so we can make #53 available, but I can hold off on tagging until this is merged...

[bbockelm]

@djw8605 - ping on this item.

[bbockelm]

@djw8605 - Ping on the above!