commit 4446a885f3aeb3a33b95c72bae1f115bed77f0cb

Author: Florian Weimer <fweimer@redhat.com>

Date:   Tue Jul 4 14:47:29 2017 +0200

    resolv: Fix resolv_conf _res matching

    A dot-less host name without an /etc/resolv.conf file caused an

    assertion failure in update_from_conf because the function would not

    deal correctly with the empty search list case.

    Thanks to Andreas Schwab for debugging assistence.

diff --git a/resolv/resolv_conf.c b/resolv/resolv_conf.c

index 0ed36cde02608f2d..f391d30c277bb348 100644

--- a/resolv/resolv_conf.c

+++ b/resolv/resolv_conf.c

@@ -272,7 +272,7 @@ resolv_conf_matches (const struct __res_state *resp,

       nserv = MAXNS;

     /* _ext.nscount is 0 until initialized by res_send.c.  */

     if (resp->nscount != nserv

-        && (resp->_u._ext.nscount != 0 && resp->_u._ext.nscount != nserv))

+        || (resp->_u._ext.nscount != 0 && resp->_u._ext.nscount != nserv))

       return false;

     for (size_t i = 0; i < nserv; ++i)

       {

@@ -295,9 +295,25 @@ resolv_conf_matches (const struct __res_state *resp,

   /* Check that the search list in *RESP has not been modified by the

      application.  */

   {

-    if (!(resp->dnsrch[0] == resp->defdname

-          && resp->dnsrch[MAXDNSRCH] == NULL))

+    if (resp->dnsrch[0] == NULL)

+      {

+        /* Empty search list.  No default domain name.  */

+        return conf->search_list_size == 0 && resp->defdname[0] == '\0';

+      }

+

+    if (resp->dnsrch[0] != resp->defdname)

+      /* If the search list is not empty, it must start with the

+         default domain name.  */

+      return false;

+

+    size_t nsearch;

+    for (nsearch = 0; nsearch < MAXDNSRCH; ++nsearch)

+      if (resp->dnsrch[nsearch] == NULL)

+        break;

+    if (nsearch > MAXDNSRCH)

+      /* Search list is not null-terminated.  */

       return false;

+

     size_t search_list_size = 0;

     for (size_t i = 0; i < conf->search_list_size; ++i)

       {

@@ -326,6 +342,8 @@ resolv_conf_matches (const struct __res_state *resp,

     size_t nsort = conf->sort_list_size;

     if (nsort > MAXRESOLVSORT)

       nsort = MAXRESOLVSORT;

+    if (resp->nsort != nsort)

+      return false;

     for (size_t i = 0; i < nsort; ++i)

       if (resp->sort_list[i].addr.s_addr != conf->sort_list[i].addr.s_addr

           || resp->sort_list[i].mask != conf->sort_list[i].mask)

diff --git a/resolv/tst-resolv-res_init-skeleton.c b/resolv/tst-resolv-res_init-skeleton.c

index 9e496a3212b0f2ab..8f395d8ce92773a9 100644

--- a/resolv/tst-resolv-res_init-skeleton.c

+++ b/resolv/tst-resolv-res_init-skeleton.c

@@ -307,6 +307,10 @@ struct test_case

   /* Setting for the RES_OPTIONS environment variable.  NULL if the

      variable is not to be set.  */

   const char *res_options;

+

+  /* Override the system host name.  NULL means that no change is made

+     and the default is used (test_hostname).  */

+  const char *hostname;

 };

 enum test_init

@@ -358,6 +362,14 @@ run_res_init (void *closure)

     setenv ("LOCALDOMAIN", ctx->t->localdomain, 1);

   if (ctx->t->res_options != NULL)

     setenv ("RES_OPTIONS", ctx->t->res_options, 1);

+  if (ctx->t->hostname != NULL)

+    {

+      /* This test needs its own namespace, to avoid changing the host

+         name for the parent, too.  */

+      TEST_VERIFY_EXIT (unshare (CLONE_NEWUTS) == 0);

+      if (sethostname (ctx->t->hostname, strlen (ctx->t->hostname)) != 0)

+        FAIL_EXIT1 ("sethostname (\"%s\"): %m", ctx->t->hostname);

+    }

   switch (ctx->init)

     {

@@ -434,6 +446,12 @@ struct test_case test_cases[] =

      "nameserver 127.0.0.1\n"

      "; nameserver[0]: [127.0.0.1]:53\n"

     },

+    {.name = "empty file, no-dot hostname",

+     .conf = "",

+     .expected = "nameserver 127.0.0.1\n"

+     "; nameserver[0]: [127.0.0.1]:53\n",

+     .hostname = "example",

+    },

     {.name = "empty file with LOCALDOMAIN",

      .conf = "",

      .expected = "search example.net\n"

@@ -462,8 +480,7 @@ struct test_case test_cases[] =

      .res_options = "edns0 attempts:5",

     },

     {.name = "basic",

-     .conf = "domain example.net\n"

-     "search corp.example.com example.com\n"

+     .conf =  "search corp.example.com example.com\n"

      "nameserver 192.0.2.1\n",

      .expected = "search corp.example.com example.com\n"

      "; search[0]: corp.example.com\n"

@@ -471,6 +488,16 @@ struct test_case test_cases[] =

      "nameserver 192.0.2.1\n"

      "; nameserver[0]: [192.0.2.1]:53\n"

     },

+    {.name = "basic with no-dot hostname",

+     .conf = "search corp.example.com example.com\n"

+     "nameserver 192.0.2.1\n",

+     .expected = "search corp.example.com example.com\n"

+     "; search[0]: corp.example.com\n"

+     "; search[1]: example.com\n"

+     "nameserver 192.0.2.1\n"

+     "; nameserver[0]: [192.0.2.1]:53\n",

+     .hostname = "example",

+    },

     {.name = "basic no-reload",

      .conf = "options no-reload\n"

      "search corp.example.com example.com\n"