Red Hat Bugzilla – Bug 73852
HOSTALIASES environment variable not used by resolver
Last modified: 2016-11-24 09:55:39 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 Galeon/1.2.5 (X11; Linux i686; U;) Gecko/20020809 Description of problem: The man page for the function gethostbyname() documents that the HOSTALIASES environment variable will be used as an alternate "hosts" file if set. This hasn't worked since release 7.0. I will attach a test case which demonstrates the problem. On my systems (currently 7.3 and (null)), the variable is never used. strace/ltrace never shows the variable looked up. How reproducible: Always Steps to Reproduce: 1. Create a host aliases file: cat > $HOME/hosts <<EOF 127.0.0.1 www.localdomain EOF 2. export HOSTALIASES=$HOME/hosts 3. Compile test case: gcc test-gethostbyname.c -o test-gethostbyname 4. ./test-gethostbyname mail.localdomain Actual Results: Regardless of what name or address you put in the hosts file, it never gets looked up. The environment variable is ignored. Expected Results: The file should be opened by the resolver functions, and hosts listed there should resolve. Additional info:
Created attachment 75884 [details] Test case for gethostbyname()
No, the file pointed to by HOSTALIASES is not the same format as /etc/hosts. See http://unixhelp.ed.ac.uk/CGI/man-cgi?hostname+7 Furthermore, it is used only if looking up name which doesn't contain any dots. Having www www.foobar.com in $HOME/hosts and doing HOSTALIASES=$HOME/hosts ./test-gethostbyname www should give you address of www.foobar.com (also note that HOSTALIASES only works for non-suid/sgid apps).
#HOSTALIASES is not the same format as /etc/hosts No? I swear I'd used it that way in the past. Removing the contents of that file, and rebuilding it according to the man page you link to causes it to work on release 7.3, but it's not working on (null). $ gcc test-gethostbyname.c -o test-gethostbyname $ echo $HOSTALIASES /home/gordon/root/etc/hosts $ export HOSTALIASES $ ls -l $HOSTALIASES -rw-r--r-- 1 gordon gordon 20 Sep 12 09:36 \ /home/gordon/root/etc/hosts $ cat $HOSTALIASES www www.eburg.com $ host www www.dragonsdawn.net is an alias for phantom.dragonsdawn.net. phantom.dragonsdawn.net has address 63.164.112.5 $ host www.eburg.com www.eburg.com is an alias for naneum.eburg.com. naneum.eburg.com has address 63.164.112.2 $ ./test-gethostbyname www gethostbyname returned 63.164.112.5
Don't know where that line break in the HOSTALIASES file came from (in the above text). I think the text widget put it there. The file is only one line long.
Works just fine for me (on glibc-2.2.93-4).
Is that available via up2date or rawhide? I'm running glibc-2.2.93-2