From 3125f453cbd3114c5b52f1e4f67529448474d828 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Wed, 7 Sep 2022 10:10:17 +0200
Subject: modernize libcurl test, as in GNUnet

---
 configure.ac        | 66 +++++++++++++++--------------------------------------
 src/lib/Makefile.am |  9 +-------
 2 files changed, 20 insertions(+), 55 deletions(-)

diff --git a/configure.ac b/configure.ac
index 7286e277..5a212c4b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -186,51 +186,25 @@ AS_IF([test "$qrencode" != 1],
 AC_SUBST(QR_CFLAGS)
 AC_SUBST(QR_LIBS)
 
-
-
-# check for libgnurl
-# libgnurl
-LIBGNURL_CHECK_CONFIG(,7.34.0,gnurl=1,gnurl=0)
-AS_IF([test "x$gnurl" = x1],[
-	AM_CONDITIONAL(HAVE_LIBGNURL, true)
-	AC_DEFINE([HAVE_LIBGNURL],[1],[Have libgnurl])
-],[
-	AM_CONDITIONAL(HAVE_LIBGNURL, false)
-])
-
-# libcurl
-LIBCURL_CHECK_CONFIG(,7.34.0,[curl=true],[curl=false])
-AS_IF([test "x$curl" = xtrue],
-      [LDFLAGS="-L$with_libcurl/lib $LDFLAGS"
-       CPPFLAGS="-I$with_libcurl/include $CPPFLAGS"
-       AC_CHECK_HEADERS([curl/curl.h],
-                        [AC_CHECK_DECLS(CURLINFO_TLS_SESSION,
-                         [curl=true],
-                         [curl=false],
-                         [[#include <curl/curl.h>]])],
-                        [curl=false])])
-       # cURL must support CURLINFO_TLS_SESSION, version >= 7.34
-
-# Check for curl/curl.h and gnurl/curl.h so we can use #ifdef
-# HAVE_CURL_CURL_H later (the above LIBCURL_CHECK_CONFIG accepted
-# *either* header set).
-AC_CHECK_HEADERS([curl/curl.h],,
-  curl=false
-  AC_CHECK_HEADERS([gnurl/curl.h],,
-  gnurl=false))
-
-# libgnurl
-AS_IF([test "x$gnurl" = "x0"],
-      [AS_IF([test "x$curl" = "x0"],
-              [AC_MSG_NOTICE([NOTICE: libgnurl not found. taler-bank support will not be compiled.])],
-              [AC_MSG_NOTICE([WARNING: libgnurl not found, trying to use libcurl instead.])])])
-
-AS_IF([test x$curl = xfalse],
-       [AM_CONDITIONAL(HAVE_LIBCURL, false)
-        AS_IF([test "x$gnurl" = "x0"],
-              [AC_MSG_WARN([GNU Taler requires libcurl-gnutls  >= 7.34])])],
-       [AM_CONDITIONAL(HAVE_LIBCURL, true)
-	AC_DEFINE([HAVE_LIBCURL],[1],[Have CURL])])
+# NOTE: If we find libcurl-gnutls here we set LIBCURL to -lcurl-gnutls
+# This affects the LIBCURL_CHECK_CONFIG call below as it takes LIBCURL into
+# account when checking for curl.
+AC_CHECK_LIB([curl-gnutls],
+             [curl_easy_getinfo],
+             [LIBCURL="-lcurl-gnutls"
+              curl_gnutls=1],
+             [curl_gnutls=0])
+
+LIBCURL_CHECK_CONFIG([], [7.34.0], [],
+                     [AC_MSG_ERROR([cURL must have a version >= 7.34.0])])
+
+# Even if curl is found, we check for this constant in order to determine
+# if we can use this feature.
+AC_CHECK_HEADER([curl/curl.h],
+                [AC_CHECK_DECLS([CURLINFO_TLS_SSL_PTR],
+                                [],
+                                [AC_MSG_ERROR([cURL must support CURLINFO_TLS_SSL_PTR])],
+                                [[#include <curl/curl.h>]])])
 
 # Check for Taler's libtalerfakebank
 libtalerfakebank=0
@@ -363,8 +337,6 @@ AM_CONDITIONAL([ENABLE_DOC], [test "x$enable_doc" = "xyes"])
 AM_CONDITIONAL([HAVE_GNUNETPQ], [false])
 AM_CONDITIONAL([HAVE_POSTGRESQL], [false])
 AM_CONDITIONAL([HAVE_TALERFAKEBANK], [false])
-AM_CONDITIONAL([HAVE_LIBCURL], [false])
-AM_CONDITIONAL([HAVE_LIBGNURL], [false])
 AM_CONDITIONAL([HAVE_TSC], [false])
 AM_CONDITIONAL([USE_COVERAGE], [false])
 AM_CONDITIONAL([ENABLE_DOC], [true])
diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
index 95e431e5..dec8712f 100644
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -65,16 +65,9 @@ libtalermerchant_la_LIBADD = \
   -lgnunetjson \
   -lgnunetutil \
   -ljansson \
+  -lcurl \
   $(XLIB)
 
-if HAVE_LIBCURL
-libtalermerchant_la_LIBADD += -lcurl
-else
-if HAVE_LIBGNURL
-libtalermerchant_la_LIBADD += -lgnurl
-endif
-endif
-
 check_PROGRAMS = \
   test_merchant_api_common
 
-- 
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