resolv: Move __res_get_nsaddr to its own file and into libc

Eliminate the use of the EXT macro from it because it does not
add clarity.  The function was added to res_send.c in 2015, and
the copyright year reflects that.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/resolv/res_get_nsaddr.c b/resolv/res_get_nsaddr.c
new file mode 100644
index 0000000000..593597bdd7
--- /dev/null
+++ b/resolv/res_get_nsaddr.c
@@ -0,0 +1,39 @@
+/* Name server address at specified index in res_state.
+   Copyright (C) 2015-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <assert.h>
+#include <resolv.h>
+#include <resolv-internal.h>
+
+struct sockaddr *
+__res_get_nsaddr (res_state statp, unsigned int n)
+{
+  assert (n < statp->nscount);
+
+  if (statp->nsaddr_list[n].sin_family == 0
+      && statp->_u._ext.nsaddrs[n] != NULL)
+    /* statp->_u._ext.nsaddrs[n] holds an address that is larger than
+       struct sockaddr, and user code did not update
+       statp->nsaddr_list[n].  */
+    return (struct sockaddr *) statp->_u._ext.nsaddrs[n];
+  else
+    /* User code updated statp->nsaddr_list[n], or statp->nsaddr_list[n]
+       has the same content as statp->_u._ext.nsaddrs[n].  */
+    return (struct sockaddr *) (void *) &statp->nsaddr_list[n];
+}
+libc_hidden_def (__res_get_nsaddr)