From 22b08ab1a45eb3773b3c90dc37a31a7574520daa Mon Sep 17 00:00:00 2001
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Date: Sat, 4 Mar 2017 14:56:53 +0100
Subject: [PATCH 2/2] configure.ac: switch to pkg-config to find openssl

Using AC_CHECK_LIB() doesn't work properly for static linking, because
it doesn't return information on transitive dependencies of
libraries. For example, if library A internally uses library B, then
with dynamic linking, doing -lA is sufficient. However, with static
linking, one must do -lA -lB, and AC_CHECK_LIB() will only give the -lA
information. This for example causes a build failure when building
sngrep statically with openssl enabled:

checking for SSL_new in -lssl... no
configure: error:  You need to have libssl installed to compile sngrep

due to undefined symbols in the OpenSSL library.

The proper solution for this is to discover the library using
pkg-config, because pkg-config properly returns the list of necessary
libraries, as it understands the concept of "list of libraries needed
when dynamic linking" and "list of libraries needed for static linking".

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Upstream-status: https://github.com/irontec/sngrep/pull/176
---
 configure.ac    | 9 +--------
 src/Makefile.am | 4 ++++
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/configure.ac b/configure.ac
index 42e00e9..9f8e6d2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -129,14 +129,7 @@ AS_IF([test "x$WITH_OPENSSL" == "xyes"], [
 	AS_IF([test "x$WITH_GNUTLS" == "xyes"], [
 	    AC_MSG_ERROR([ GnuTLS and OpenSSL can not be enabled at the same time ])
 	], [])
-
-	AC_CHECK_LIB([ssl], [SSL_new], [], [
-	    AC_MSG_ERROR([ You need to have libssl installed to compile sngrep])
-	])
-
-	AC_CHECK_LIB([crypto], [EVP_get_cipherbyname], [], [
-	    AC_MSG_ERROR([ You need to have libcrypto installed to compile sngrep])
-	])
+	PKG_CHECK_MODULES([SSL], [libssl libcrypto])
 	AC_DEFINE([WITH_OPENSSL],[],[Compile With Openssl compatibility])
 ], [])
 
diff --git a/src/Makefile.am b/src/Makefile.am
index 961f4a0..3a471b7 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,6 +1,8 @@
 AUTOMAKE_OPTIONS=subdir-objects
 bin_PROGRAMS=sngrep
 sngrep_SOURCES=capture.c
+sngrep_CFLAGS=
+sngrep_LDADD=
 if USE_EEP
 sngrep_SOURCES+=capture_eep.c
 endif
@@ -9,6 +11,8 @@ sngrep_SOURCES+=capture_gnutls.c
 endif
 if WITH_OPENSSL
 sngrep_SOURCES+=capture_openssl.c
+sngrep_CFLAGS+=$(SSL_CFLAGS)
+sngrep_LDADD+=$(SSL_LIBS)
 endif
 sngrep_SOURCES+=address.c packet.c sip.c sip_call.c sip_msg.c sip_attr.c main.c
 sngrep_SOURCES+=option.c group.c filter.c keybinding.c media.c setting.c rtp.c
-- 
2.7.4