Your message dated Fri, 10 Jan 2025 20:06:37 +0100 with message-id <[email protected]> and subject line Re: Bug#626472: libc6: gethostbyname fails if label ends with dash has caused the Debian Bug report #626472, regarding libc6: gethostbyname fails if label ends with dash to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact [email protected] immediately.) -- 626472: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=626472 Debian Bug Tracking System Contact [email protected] with problems
--- Begin Message ---Package: libc6 Version: 2.11.2-10 Severity: normal Compare: $ host foo-.tumblr.com foo-.tumblr.com is an alias for proxy-tumblelogs.d1.tumblr.com. proxy-tumblelogs.d1.tumblr.com has address 174.121.98.168 $ and $ getent hosts foo-.tumblr.com $ echo $? 2 $ By contrast: $ getent hosts foo.tumblr.com 174.121.98.168 proxy-tumblelogs.d1.tumblr.com foo.tumblr.com tcpdump/wireshark shows that the DNS query for foo-.tumblr.com does go out, and is answered with the CNAME and A (for proxy-tumblelogs.d1.tumblr.com), but gethostbyname just returns failure with errno set to EBADMSG. Here's a test program that shows that: #include <stdio.h> #include <error.h> #include <netdb.h> #include <sys/socket.h> #include <errno.h> int main (int argc, char *argv[]) { char *hostname = "foo-.tumblr.com"; struct hostent *r=gethostbyname2(hostname, AF_INET); perror("ghbn2 returned error"); return 0; } As a consequence, any program that uses gethostbyname (and possibly other glibc name resolution interfaces) cannot resolve any domain name that contain a label that ends with a dash, or possibly this is limited to the ones that resolve to a CNAME. Labels that end with a dash ("-") in in a domain name are not 100% RFC-conformant, but they are used in the wild, e.g. in http://barefeetdreams-.tumblr.com/ I presume that the DNS stub resolver of "other OS" accepts to resolve such a name, else the author of the above page would have noticed her blog is not reachable. On a Debian GNU/Linux machine, trying to load this URL won't work, obviously, because of this bug. You can work around that and check for yourself there is an active website behind that address by adding 174.121.98.168 barefeetdreams-.tumblr.com to /etc/hosts For interoperability purposes, I think it would be best to accept such "technically invalid" domains. -- System Information: Debian Release: squeeze/sid APT prefers oldstable APT policy: (500, 'oldstable'), (500, 'stable'), (400, 'testing'), (300, 'unstable') Architecture: amd64 (x86_64) Kernel: Linux 2.6.32-5-amd64 (SMP w/2 CPU cores) Locale: LANG=fr_LU.UTF-8, LC_CTYPE=fr_LU.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/bash Versions of packages libc6 depends on: ii libc-bin 2.11.2-10 Embedded GNU C Library: Binaries ii libgcc1 1:4.4.5-8 GCC support library libc6 recommends no packages. Versions of packages libc6 suggests: ii debconf [debconf-2.0] 1.5.24 Debian configuration management sy ii glibc-doc 2.11.2-6+squeeze1 Embedded GNU C Library: Documentat ii locales 2.11.2-6+squeeze1 Embedded GNU C Library: National L -- debconf information: * glibc/upgrade: true * glibc/disable-screensaver: glibc/restart-failed: * glibc/restart-services: gdm openbsd-inetd exim4 cups cron
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--- Begin Message ---Version: 2.27-1 On 2011-05-12 10:34, Lionel Elie Mamane wrote: > Package: libc6 > Version: 2.11.2-10 > Severity: normal > > Compare: > > $ host foo-.tumblr.com > foo-.tumblr.com is an alias for proxy-tumblelogs.d1.tumblr.com. > proxy-tumblelogs.d1.tumblr.com has address 174.121.98.168 > $ > > and > > $ getent hosts foo-.tumblr.com > $ echo $? > 2 > $ > > By contrast: > > $ getent hosts foo.tumblr.com > 174.121.98.168 proxy-tumblelogs.d1.tumblr.com foo.tumblr.com This bug got fixed in glibc 2.27. Closing the bug accordingly. Regards Aurelien -- Aurelien Jarno GPG: 4096R/1DDD8C9B [email protected] http://aurel32.net
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