Add the ability to make GDM spawn XDMCP sessions on a local X proxy

2005-04-22  Mark McLoughlin  <mark@skynet.ie>

	Add the ability to make GDM spawn XDMCP sessions on a local
	X proxy server. Experimental support for disconnect/reconnect
	or "session migration" is also implemented using DMX.
	More details in bug #301602.

	* configure.in: require glib 2.6.0 and check for DMX.

	* config/gdm.conf.in: add xdmpc/EnableProxy, xdmcp/ProxyXServer
	and xdmcp/ProxyReconnect config keys.

	* docs/C/gdm.xml: document new config keys.

	* daemon/gdm.h: add TYPE_XDMCP_PROXY server type, add #defines
	for the new config keys, re-name various xnest related GdmDisplay
	members to be applicable for all proxy servers, add xdmcp_dispnum
	GdmDisplay member, modify the format of GDM_SOP_QUERYLOGIN and
	add GDM_SOP_AUTHFILE and GDM_SOP_MIGRATE.

	* daemon/gdm.c: read the new config keys, change format of what
	GDM_SOP_QUERYLOGIN returns, implement GDM_SOP_AUTHFILE and
	GDM_SOP_MIGRATE.

	* daemon/xdmcp.h: add gdm_xdmcp_migrate.

	* daemon/xdmcp.c: when xdmpc/EnableProxy and xdmcp/ProxyXServer,
	set things up such that a proxy sever (which displays on the
	requesting X server) is run locally by the slave.
	Also implement migrating the proxy server from one parent display
	to another using the xdmcp/ProxyReconnect command.

	* daemon/server.c: if we're running a proxy server (e.g. Xnest
	or Xdmx), hold a connection open to the parent display so that
	it doesn't reset.
	Run proxy servers with -display rather than setting $DISPLAY.

	* daemon/slave.c:
	Once we've successfully logged the user in, send SOP_QUERYLOGIN
	to the slave - if the result from that indicates that the user
	is already logged in and that session is migratable (e.g. by
	reconnecting a proxy server or changing the VT), then migrate
	to the existing session using SOP_MIGRATE.
	In the case of an Xdmcp proxy, hold open the connection to the
	parent display so that it doesn't reset. Exit the slave as
	soon as that connection closes.

	* utils/Makefile.am, utils/gdm-dmx-reconnect-proxy.c: implementation
	of xdmcp/ProxyReconnect for use with Xdmx.

3 files changed, 150 insertions, 0 deletions

diff --git a/utils/.cvsignore b/utils/.cvsignore
index 80868fe5..9f61016a 100644
--- a/utils/.cvsignore
+++ b/utils/.cvsignore
@@ -6,3 +6,4 @@ gdmaskpass
 gdmopen
 gdmmktemp
 gdmtranslate
+gdm-dmx-reconnect-proxy
diff --git a/utils/Makefile.am b/utils/Makefile.am
index f22e4363..7ec28603 100644
--- a/utils/Makefile.am
+++ b/utils/Makefile.am
@@ -20,6 +20,10 @@ libexec_PROGRAMS = \
 # bin_PROGRAMS = \
 #	gdmmktemp
 
+if DMX_SUPPORT
+bin_PROGRAMS = gdm-dmx-reconnect-proxy
+endif
+
 EXTRA_PROGRAMS = gdmaskpass gdmopen
 
 gdmaskpass_SOURCES = \
@@ -47,3 +51,15 @@ gdmtranslate_LDADD = \
 
 #gdmmktemp_LDADD = \
 #	$(INTLLIBS)
+
+if DMX_SUPPORT
+gdm_dmx_reconnect_proxy_SOURCES = \
+	gdm-dmx-reconnect-proxy.c
+
+gdm_dmx_reconnect_proxy_LDADD = \
+	$(GLIB_LIBS) \
+	$(X_EXTRA_LIBS) \
+	$(X_LIBS) \
+	-lX11 \
+	$(DMX_LIBS)
+endif
diff --git a/utils/gdm-dmx-reconnect-proxy.c b/utils/gdm-dmx-reconnect-proxy.c
new file mode 100644
index 00000000..352db3f7
--- /dev/null
+++ b/utils/gdm-dmx-reconnect-proxy.c
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2005 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <config.h>
+
+#include <stdlib.h>
+#include <glib.h>
+#include <glib/gi18n.h>
+
+#include <X11/Xlib.h>
+#include <X11/extensions/dmxext.h>
+
+#include <ve-misc.h>
+
+static char *to_display = NULL;
+static char *backend_display = NULL;
+static char *to_authfile = NULL;
+static char *backend_authfile = NULL;
+
+static GOptionEntry options[] = {
+	{
+		"to", 0, 0, G_OPTION_ARG_STRING, &to_display,
+		N_("DMX display to migrate to"),
+		N_("DISPLAY")
+	},
+	{
+		"display", 0, 0, G_OPTION_ARG_STRING, &backend_display,
+		N_("Backend display name"),
+		N_("DISPLAY")
+	},
+	{
+		"to-authfile", 0, 0, G_OPTION_ARG_STRING, &to_authfile,
+		N_("Xauthority file for destination display"),
+		N_("AUTHFILE")
+	},
+	{
+		"display-authfile", 0, 0, G_OPTION_ARG_STRING, &backend_authfile,
+		N_("Xauthority file for backend display"),
+		N_("AUTHFILE")
+	},
+	{ NULL }
+};
+
+static Display *
+get_dmx_display (const char *display_name,
+		 const char *authfile)
+{
+	Display *display;
+	int event_base, error_base;
+	const char *old_authfile;
+
+	old_authfile = getenv ("XAUTHORITY");
+	ve_setenv ("XAUTHORITY", authfile, TRUE);
+
+	if ((display = XOpenDisplay (display_name)) == NULL)
+		g_printerr (_("Failed to open display \"%s\"\n"), display_name);
+
+	if (display != NULL &&
+	    !DMXQueryExtension (display, &event_base, &error_base)) {
+		g_printerr (_("DMX extension not present on \"%s\"\n"), display_name);
+		XCloseDisplay (display);
+		display = NULL;
+	}
+
+	ve_setenv ("XAUTHORITY", old_authfile, TRUE);
+
+	return display;
+}
+
+int
+main (int argc, char **argv)
+{
+	GOptionContext *options_context;
+	Display *display;
+	DMXScreenAttributes attr;
+	guint mask;
+	int screen;
+
+	setlocale (LC_ALL, "");
+	bindtextdomain (GETTEXT_PACKAGE, GNOMELOCALEDIR);
+	textdomain (GETTEXT_PACKAGE);
+
+	options_context = g_option_context_new (_("- migrate a backend display from one DMX display to another"));
+	g_option_context_add_main_entries (options_context, options, GETTEXT_PACKAGE);
+	g_option_context_parse (options_context, &argc, &argv, NULL);
+
+	if (to_display == NULL) {
+		g_printerr (_("You must specify a destination DMX display using %s\n"), "--to");
+		return 1;
+	}
+
+	if (backend_display == NULL) {
+		g_printerr (_("You must specify a backend display which using %s\n"), "--display");
+		return 1;
+	}
+
+	if ((display = get_dmx_display (to_display, to_authfile)) == NULL)
+		return 1;
+
+	/* Note, we have no way yet of using backend_authfile to ensure
+	 * that the DMX server can authenticate against the backend Xserver.
+	 * For now, we must disable access control on the backend server.
+	 */
+
+	mask = 0;
+	screen = 0;
+	if (!DMXAddScreen (display, backend_display, mask, &attr, &screen)) {
+		g_printerr (_("DMXAddScreen \"%s\" failed on \"%s\"\n"),
+			    backend_display, to_display);
+		XCloseDisplay (display);
+		return 1;
+	}
+
+	XCloseDisplay (display);
+
+	return 0;
+}