User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7a) Gecko/20040114 Firebird/0.8.0+ Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7a) Gecko/20040114 Firebird/0.8.0+ My /etc/resolv.conf contains exactly one DNS server: fec0:0:0:ffff::1 (that is an IPv6 anycast address that is served on the same machine). My Firebird started giving me intermittent DNS errors ("Address Not Found Error", "wireservice.wired.com could not be found. Please check the name and try again.") This happens with all names, not just this one. tcpdump on loopback reveals that my dnscache works fine and answer all queries, but firebird sends about every third to fifth query to 127.0.0.1 instead of the correct address. There is no dnscache on 127.0.0.1, so the result is an ICMP port unreachable message. I can see that Firebird then resends the query three times, every time with the same result obviously, and then gives up and gives me the error message. Retrying the same page helps most of the time, but sometimes I have to reload several times. This is particularly unnerving since Firebird apparently does not have it's own DNS cache, so if I go to a web page with many inline images, most of the time none of them will show up, even if I get the web page itself. Reproducible: Sometimes Steps to Reproduce: 1. just click around on the net, for example to slashdot.org, and try to follow some links (it does not matter whether the links are internal to slashdot or external) 2. run tcpdump port 53 to watch the DNS packets 3. watch in amazement as Mozilla queries the wrong server every now and then Actual Results: Mozilla sometimes asks 127.0.0.1 instead of fec0:0:0:ffff::1 Expected Results: ask fec0:0:0:ffff::1
can you attach a Networking log, see instructions here: http://www.mozilla.org/projects/netlib/http/http-debugging.html (you may want to reduce the log to show the relevant part if the issue doesn't occur in the first pages as the log tends to grow rapidly)
Can you put the resolv.conf file and the tcpdump in the bug?
Summary: Intermittent DNS errors, tcpdump shows that firebird asks wrong server → DNS: IPv6: Intermittent errors, tcpdump shows query to 127.0.0.1
Here is partial tcpdump output ("tcpdump -n -i lo -s 0 port 53"): 01:33:43.101374 IP 127.0.0.1.32809 > 127.0.0.1.53: 10005+ AAAA? www.heise.de. (30) 01:33:43.101734 IP 127.0.0.1.32809 > 127.0.0.1.53: 10005+ AAAA? www.heise.de. (30) 01:33:43.101779 IP 127.0.0.1.32809 > 127.0.0.1.53: 10006+ AAAA? www.heise.de. (30) 01:33:43.101811 IP 127.0.0.1.32809 > 127.0.0.1.53: 10006+ AAAA? www.heise.de. (30) 01:33:43.101852 IP 127.0.0.1.32809 > 127.0.0.1.53: 10007+ A? www.heise.de. (30) 01:33:43.101884 IP 127.0.0.1.32809 > 127.0.0.1.53: 10007+ A? www.heise.de. (30) 01:33:43.101918 IP 127.0.0.1.32809 > 127.0.0.1.53: 10008+ A? www.heise.de. (30) 01:33:43.101963 IP 127.0.0.1.32809 > 127.0.0.1.53: 10008+ A? www.heise.de. (30) I said "port 53", so we don't get the icmp port unreachable here. And this is what my /etc/resolv.conf looks like: nameserver fec0:0:0:ffff::1 #nameserver 10.0.0.1
firebird is just calling glibc functions. in this case, firebird is likely calling getaddrinfo. maybe this is a glibc bug. do any other applications misbehave in a similar fashion? i'll attach a little test program that can be used to simulate getaddrinfo being called by an application. try testing this program to see how it behaves.
felix: if you can run the test program and report back on how it behaves that would be very helpful. thanks!!
No other glibc program behaves like this. In fact, I'm currently using Konqueror to browse the web because of these problems, and it is of course linked to the same glibc. Also, MozillaFirebird 0.7 does not have the problem, only the CVS version. I'm using Gentoo, so the 0.7 version was also compiled on my box with the same glibc and the same gcc, it's not a binary from someone else.
felix: ok, that's helpful info... can you still please run the test program? i'm not certain that konqueror is using getaddrinfo on your OS.
I just kept clicking around with the firebird 0.7 release, and it turns out that it also produces the 127.0.0.1 DNS queries, it just took a lot longer. Mhh. It may be a glibc bug after all. I will open a Gentoo bug on this, maybe they have an idea. BTW: your test program is broken, it prints IPv6 addresses incorrectly ;-) The test program does not exhibit the problem. I think it only happens if the same application does a lot of getaddrinfo calls. I just added a loop to the test program that runs the same getaddrinfo for 100 times, but it still does not reproduce the bug. Maybe firebird overwrites some glibc memory here? Konqueror, by the way, also supports IPv6, so I am quite sure that it also uses getaddrinfo for DNS resolution.
hmm.. firebird 0.7 did not use getaddrinfo, so that is a very interesting data point. during the mozilla 1.6 development cycle, the mozilla host resolver was rewritten to use getaddrinfo for ipv6 support. otherwise, it still calls gethostbyname_r on linux. konqueror could be calling gethostbyname2 instead to deal with ipv6. though, from past experience with that codebase, i think it is probably calling getaddrinfo as well. i really don't know for sure. memory corruption is a slim possibility here. it is very odd though that the same problem can be seen before and after the mozilla host resolver rewrite :-/ do you know if anyone else has seen this problem? have you tried creating a new mozilla user profile? can you reproduce this using a mozilla nightly build?
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Status: UNCONFIRMED → RESOLVED
Last Resolved: 13 years ago
Resolution: --- → EXPIRED
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Status: RESOLVED → VERIFIED
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