BZ#16469: resolv: skip leading dot in domain to search

This should only happen if the domain to search is the root,
represented as "." rather than by an empty string.  Skipping it here
prevents libc_res_nquerydomain from duplicating the trailing dot,
which would cause the domain name compression to fail.

for  ChangeLog

	[BZ #16469]
	* resolv/res_query.c (__libc_res_nsearch): Skip leading dot in
	search domain names.

diff --git a/ChangeLog b/ChangeLog
index 650d11892d578c19fbc82c1c139203a06b0d93f4..76fda28818b863cbffb39221894f84e82b342f4e 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2014-11-21  Alexandre Oliva <aoliva@redhat.com>
+
+       [BZ #16469]
+       * resolv/res_query.c (__libc_res_nsearch): Skip leading dot in
+       search domain names.
+
 2014-11-21  Alexandre Oliva <aoliva@redhat.com>
 
        [BZ #16469]

diff --git a/resolv/res_query.c b/resolv/res_query.c
index 33eeeb70da6511134342f4d50db1b80fe9032ac4..4a9b3b3f27288f1c6926082ba5aadcd0427b142e 100644 (file)
--- a/resolv/res_query.c
+++ b/resolv/res_query.c
@@ -413,13 +413,24 @@ __libc_res_nsearch(res_state statp,
                for (domain = (const char * const *)statp->dnsrch;
                     *domain && !done;
                     domain++) {
+                       const char *dname = domain[0];
                        searched = 1;
 
-                       if (domain[0][0] == '\0' ||
-                           (domain[0][0] == '.' && domain[0][1] == '\0'))
+                       /* __libc_res_nquerydoman concatenates name
+                          with dname with a "." in between.  If we
+                          pass it in dname the "." we got from the
+                          configured default search path, we'll end
+                          up with "name..", which won't resolve.
+                          OTOH, passing it "" will result in "name.",
+                          which has the intended effect for both
+                          possible representations of the root
+                          domain.  */
+                       if (dname[0] == '.')
+                               dname++;
+                       if (dname[0] == '\0')
                                root_on_list++;
 
-                       ret = __libc_res_nquerydomain(statp, name, *domain,
+                       ret = __libc_res_nquerydomain(statp, name, dname,
                                                      class, type,
                                                      answer, anslen, answerp,
                                                      answerp2, nanswerp2,