NFD » ndn-cxx

Can you upload a Wireshark capture of the machine when the problematic unit test is running?
The capture should show port 53 traffic on both IPv4 and IPv6.

Strangely, I'm not getting this issue anymore. I was only getting it on the University network and not on my home network. However, now when I run the tests from within the University network (on Vagrant), the tests pass.

http://jenkins.named-data.net/job/NFD/5409/ failed due to DNS issue. Can you keep a tcpdump continuously running on 17.04 slaves, capturing DNS traffic only, so that we have a log whenever the problem appears again?

Eric Newberry wrote:

It appears that the DNS lookup issues happen when doing reverse lookups (IP address to hostname) during FaceUri canonization

AFAIK we don't do any reverse lookups during FaceUri canonization.

Is it a problem with the host node, or a problem with Ubuntu 17.04 OS?

I also notice that all slaves on that host node is down at the moment.
I'd suggest to ensure each OS version has slaves on at least two host nodes. This can expose any host-node specific issue, and also prevents single point of failure.

UPDATE: Arizona UITS is upgrading firewall, causing remote nodes to appear offline. But it's still a good idea to shift slaves onto two or more sites.

Junxiao Shi wrote:

Surprisingly, there is no DNS packet seen in tcpdump.

Yes, I noticed this when I did tcpdumps on these nodes yesterday. I believe the DNS queries are being resolved using alternative means, perhaps systemd-resolved. However, systemd-resolved should also use port 53 for its traffic.

Davide Pesavento wrote:

Eric Newberry wrote:

It appears that the DNS lookup issues happen when doing reverse lookups (IP address to hostname) during FaceUri canonization

AFAIK we don't do any reverse lookups during FaceUri canonization.

Here's some output from the tools unit tests run on Ubuntu 17.04:

../tests/tools/nfdc/face-module.t.cpp(395): error: in "Nfdc/TestFaceModule/CreateCommand/ErrorConflict": check exitCode == 1 has failed [4 != 1]
../tests/tools/nfdc/face-module.t.cpp(397): error: in "Nfdc/TestFaceModule/CreateCommand/ErrorConflict": check err.is_equal("Error 409 when creating face: conflict-409\n") has failed. Output content: "Error when canonizing 'udp://20.53.73.45': Hostname resolution timed out
"

I don't have an explanation for that output, but there's no code in ndn-cxx, NFD, or nfdc to perform reverse resolutions, so something else must be going on.

As a side note, IpHostCanonizeProvider could avoid calling dns::asyncResolve() if the host portion of the URI already contains a valid IP address.

Junxiao Shi wrote:

Is it a problem with the host node, or a problem with Ubuntu 17.04 OS?

Seems to be the former.

Job 5172 on a UA slave passed successfully, while Job 5173 failed on a CSU slave. Therefore this issue seems related to the host or network environment at CSU.

I've launched a second 17.04 node at UA and disconnected both 17.04 nodes at CSU. Hopefully, this will resolve the issues as this issue seems specific to the CSU environment.

Davide Pesavento wrote:

Seems to be working for now. Should we close (or reject) this issue?

Probably not reject since there were changes merged for this issue.