First changes for future use of NTBTLS.

* configure.ac (NEED_NTBTLS_ABI, NEED_NTBTLS_VERSION): New.
(HTTP_USE_NTBTLS): New.  Prefer over GNUTLS.
* m4/ntbtls.m4: New.
* m4/Makefile.am (EXTRA_DIST): Add new file.
* common/http.c: Add conditionals to eventually use NTBTLS.
--

This is only the configure stuff.  If you have NTBTLS installed GNUTLS
will not be used but there won't be any https support either :-(.
This patch is used to have a real world test bench for the forthcoming
library.

m4/Makefile.am

@@ -4,7 +4,7 @@ EXTRA_DIST += ldap.m4 libcurl.m4 libusb.m4 tar-ustar.m4 readline.m4
 
 EXTRA_DIST += gnupg-pth.m4
 
-EXTRA_DIST += gpg-error.m4 libgcrypt.m4 libassuan.m4 ksba.m4
+EXTRA_DIST += gpg-error.m4 libgcrypt.m4 libassuan.m4 ksba.m4 ntbtls.m4
 
 EXTRA_DIST += autobuild.m4
 

m4/ntbtls.m4

@@ -0,0 +1,137 @@
+dnl Autoconf macros for NTBTLS
+dnl Copyright (C) 2002, 2004, 2011 Free Software Foundation, Inc.
+dnl
+dnl This file is free software; as a special exception the author gives
+dnl unlimited permission to copy and/or distribute it, with or without
+dnl modifications, as long as this notice is preserved.
+dnl
+dnl This file is distributed in the hope that it will be useful, but
+dnl WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+dnl implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+
+dnl AM_PATH_NTBTLS([MINIMUM-VERSION,
+dnl                   [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND ]]])
+dnl
+dnl Test for NTBTLS and define NTBTLS_CFLAGS and NTBTLS_LIBS.
+dnl MINIMUN-VERSION is a string with the version number optionalliy prefixed
+dnl with the API version to also check the API compatibility. Example:
+dnl a MINIMUN-VERSION of 1:1.2.5 won't pass the test unless the installed
+dnl version of libgcrypt is at least 1.2.5 *and* the API number is 1.  Using
+dnl this features allows to prevent build against newer versions of libgcrypt
+dnl with a changed API.
+dnl
+AC_DEFUN([AM_PATH_NTBTLS],
+[ AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_ARG_WITH(ntbtls-prefix,
+            AC_HELP_STRING([--with-ntbtls-prefix=PFX],
+                           [prefix where NTBTLS is installed (optional)]),
+     ntbtls_config_prefix="$withval", ntbtls_config_prefix="")
+  if test x"${NTBTLS_CONFIG}" = x ; then
+     if test x"${ntbtls_config_prefix}" != x ; then
+        NTBTLS_CONFIG="${ntbtls_config_prefix}/bin/ntbtls-config"
+     else
+       case "${SYSROOT}" in
+         /*)
+           if test -x "${SYSROOT}/bin/ntbtls-config" ; then
+             NTBTLS_CONFIG="${SYSROOT}/bin/ntbtls-config"
+           fi
+           ;;
+         '')
+           ;;
+          *)
+           AC_MSG_WARN([Ignoring \$SYSROOT as it is not an absolute path.])
+           ;;
+       esac
+     fi
+  fi
+
+  AC_PATH_PROG(NTBTLS_CONFIG, ntbtls-config, no)
+  tmp=ifelse([$1], ,1:1.0.0,$1)
+  if echo "$tmp" | grep ':' >/dev/null 2>/dev/null ; then
+     req_ntbtls_api=`echo "$tmp"     | sed 's/\(.*\):\(.*\)/\1/'`
+     min_ntbtls_version=`echo "$tmp" | sed 's/\(.*\):\(.*\)/\2/'`
+  else
+     req_ntbtls_api=0
+     min_ntbtls_version="$tmp"
+  fi
+
+  AC_MSG_CHECKING(for NTBTLS - version >= $min_ntbtls_version)
+  ok=no
+  if test "$NTBTLS_CONFIG" != "no" ; then
+    req_major=`echo $min_ntbtls_version | \
+               sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\)/\1/'`
+    req_minor=`echo $min_ntbtls_version | \
+               sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\)/\2/'`
+    req_micro=`echo $min_ntbtls_version | \
+               sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\)/\3/'`
+    ntbtls_config_version=`$NTBTLS_CONFIG --version`
+    major=`echo $ntbtls_config_version | \
+               sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\).*/\1/'`
+    minor=`echo $ntbtls_config_version | \
+               sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\).*/\2/'`
+    micro=`echo $ntbtls_config_version | \
+               sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\).*/\3/'`
+    if test "$major" -gt "$req_major"; then
+        ok=yes
+    else
+        if test "$major" -eq "$req_major"; then
+            if test "$minor" -gt "$req_minor"; then
+               ok=yes
+            else
+               if test "$minor" -eq "$req_minor"; then
+                   if test "$micro" -ge "$req_micro"; then
+                     ok=yes
+                   fi
+               fi
+            fi
+        fi
+    fi
+  fi
+  if test $ok = yes; then
+    AC_MSG_RESULT([yes ($ntbtls_config_version)])
+  else
+    AC_MSG_RESULT(no)
+  fi
+  if test $ok = yes; then
+     # If we have a recent ntbtls, we should also check that the
+     # API is compatible
+     if test "$req_ntbtls_api" -gt 0 ; then
+        tmp=`$NTBTLS_CONFIG --api-version 2>/dev/null || echo 0`
+        if test "$tmp" -gt 0 ; then
+           AC_MSG_CHECKING([NTBTLS API version])
+           if test "$req_ntbtls_api" -eq "$tmp" ; then
+             AC_MSG_RESULT([okay])
+           else
+             ok=no
+             AC_MSG_RESULT([does not match. want=$req_ntbtls_api got=$tmp])
+           fi
+        fi
+     fi
+  fi
+  if test $ok = yes; then
+    NTBTLS_CFLAGS=`$NTBTLS_CONFIG --cflags`
+    NTBTLS_LIBS=`$NTBTLS_CONFIG --libs`
+    ifelse([$2], , :, [$2])
+    ntbtls_config_host=`$NTBTLS_CONFIG --host 2>/dev/null || echo none`
+    if test x"$ntbtls_config_host" != xnone ; then
+      if test x"$ntbtls_config_host" != x"$host" ; then
+  AC_MSG_WARN([[
+***
+*** The config script $NTBTLS_CONFIG was
+*** built for $ntbtls_config_host and thus may not match the
+*** used host $host.
+*** You may want to use the configure option --with-ntbtls-prefix
+*** to specify a matching config script or use \$SYSROOT.
+***]])
+        gpg_config_script_warn="$gpg_config_script_warn ntbtls"
+      fi
+    fi
+  else
+    NTBTLS_CFLAGS=""
+    NTBTLS_LIBS=""
+    ifelse([$3], , :, [$3])
+  fi
+  AC_SUBST(NTBTLS_CFLAGS)
+  AC_SUBST(NTBTLS_LIBS)
+])