From: Gert Doering <gert@greenie.muc.de>
Date: Mon, 27 Apr 2015 19:27:21 +0000 (+0200)
Subject: assume res_init() is always there.
X-Git-Tag: v2.3.7~16
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ae9aff25c5a74e770a29a3a675f5b8f8dd8c5bf8;p=thirdparty%2Fopenvpn.git

assume res_init() is always there.

Previously, the code tried to find res_init(), and on some systems
got it wrong in configure, silently not-using res_init(), leading
to unexpected failures to re-init the resolver.

We know that all supported OSes (except Windows) have res_init(), so
change the call to "#ifndef WIN32", and adjust configure.ac to just
find the library to link (if any).  With that, failures to find
res_init() are no longer "hidden" but clearly visible at link time.

AC_SEARCH_LIBS() bits inspired by CUPS' cups_network.m4 (GPLv2)

Fix (part of) trac #523

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Lazy-ACK-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1430162841-5840-1-git-send-email-gert@greenie.muc.de>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9614
(cherry picked from commit 403dc434d245e5df5ae262935aa2e7364547e260)
---

diff --git a/configure.ac b/configure.ac
index 9b8c380ce..ab700cf54 100644
--- a/configure.ac
+++ b/configure.ac
@@ -603,12 +603,6 @@ AC_SUBST([SOCKETS_LIBS])
 old_LIBS="${LIBS}"
 LIBS="${LIBS} ${SOCKETS_LIBS}"
 AC_CHECK_FUNCS([sendmsg recvmsg inet_ntop inet_pton])
-AC_CHECK_FUNCS(
-	[res_init],
-	,
-	,
-	[[#include <resolv.h>]]
-)
 # Windows use stdcall for winsock so we cannot auto detect these
 m4_define(
 	[SOCKET_FUNCS],
@@ -636,6 +630,11 @@ else
 fi
 LIBS="${old_LIBS}"
 
+# we assume res_init() always exist, but need to find out *where*...
+AC_SEARCH_LIBS(__res_init, resolv bind, ,
+    AC_SEARCH_LIBS(res_9_init, resolv bind, ,
+	AC_SEARCH_LIBS(res_init, resolv bind, , )))
+
 AC_ARG_VAR([TAP_CFLAGS], [C compiler flags for tap])
 old_CFLAGS="${CFLAGS}"
 CFLAGS="${CFLAGS} ${TAP_CFLAGS}"
diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
index 6e68c18aa..af13e3620 100644
--- a/src/openvpn/socket.c
+++ b/src/openvpn/socket.c
@@ -137,7 +137,7 @@ openvpn_getaddrinfo (unsigned int flags,
 
   ASSERT(res);
 
-#if defined(HAVE_RES_INIT)
+#ifndef WIN32
   res_init ();
 #endif