added check for required header files

configure.ac

@@ -19,6 +19,23 @@ AC_ARG_ENABLE(pamuserpass, AS_HELP_STRING([--enable-pamuserpass],
               [Build pam userpass support (default: no)]),
               [pamuserpass=true], [pamuserpass=false])
 AM_CONDITIONAL(SESMAN_PAMUSERPASS, [test x$pamuserpass = xtrue])
+
+# checking for openssl
+AC_CHECK_HEADER([openssl/rc4.h], [], [AC_MSG_ERROR([please install libssl-dev or openssl-devel])])
+
+# checking if pam should be autodetected.
+if test -z "$enable_nopam"
+then
+  if test -z "$enable_kerberos"
+  then
+    AC_CHECK_HEADER([security/pam_appl.h], [], [AC_MSG_ERROR([please install libpam0g-dev or pam-devel])])
+  fi
+fi
+
+# checking for Xlib
+AC_CHECK_HEADER([X11/Xlib.h], [], [AC_MSG_ERROR([please install libx11-dev])])
+AC_CHECK_HEADER([X11/extensions/Xfixes.h], [], [AC_MSG_ERROR([please install libxfixes-dev])])
+
 libdir="${libdir}/xrdp";
 if test "x${prefix}" = "xNONE" ; then
 sysconfdir="/etc";