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/*
* Copyright (C) 2010-2011 Robert Ancell.
* Author: Robert Ancell <robert.ancell@canonical.com>
*
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version. See http://www.gnu.org/copyleft/gpl.html the full text of the
* license.
*/
#include <stdlib.h>
#include <string.h>
#include <X11/X.h>
#define HASXDMAUTH
#include <X11/Xdmcp.h>
#include <gio/gio.h>
#include "xdmcp-server.h"
#include "xdmcp-protocol.h"
#include "xdmcp-session-private.h"
#include "x-authority.h"
enum {
NEW_SESSION,
LAST_SIGNAL
};
static guint signals[LAST_SIGNAL] = { 0 };
struct XDMCPServerPrivate
{
/* Port to listen on */
guint port;
/* Listening sockets */
GSocket *socket, *socket6;
/* Hostname to report to client */
gchar *hostname;
/* Status to report to clients */
gchar *status;
/* XDM-AUTHENTICATION-1 key */
gchar *key;
/* Active XDMCP sessions */
GHashTable *sessions;
};
G_DEFINE_TYPE (XDMCPServer, xdmcp_server, G_TYPE_OBJECT);
/* Maximum number of milliseconds client will resend manage requests before giving up */
#define MANAGE_TIMEOUT 126000
XDMCPServer *
xdmcp_server_new (void)
{
return g_object_new (XDMCP_SERVER_TYPE, NULL);
}
void
xdmcp_server_set_port (XDMCPServer *server, guint port)
{
g_return_if_fail (server != NULL);
server->priv->port = port;
}
guint
xdmcp_server_get_port (XDMCPServer *server)
{
g_return_val_if_fail (server != NULL, 0);
return server->priv->port;
}
void
xdmcp_server_set_hostname (XDMCPServer *server, const gchar *hostname)
{
g_return_if_fail (server != NULL);
g_free (server->priv->hostname);
server->priv->hostname = g_strdup (hostname);
}
const gchar *
xdmcp_server_get_hostname (XDMCPServer *server)
{
g_return_val_if_fail (server != NULL, NULL);
return server->priv->hostname;
}
void
xdmcp_server_set_status (XDMCPServer *server, const gchar *status)
{
g_return_if_fail (server != NULL);
g_free (server->priv->status);
server->priv->status = g_strdup (status);
}
const gchar *
xdmcp_server_get_status (XDMCPServer *server)
{
g_return_val_if_fail (server != NULL, NULL);
return server->priv->status;
}
void
xdmcp_server_set_key (XDMCPServer *server, const gchar *key)
{
g_return_if_fail (server != NULL);
g_free (server->priv->key);
server->priv->key = g_strdup (key);
}
static gboolean
session_timeout_cb (XDMCPSession *session)
{
session->priv->inactive_timeout = 0;
g_debug ("Timing out unmanaged session %d", session->priv->id);
g_hash_table_remove (session->priv->server->priv->sessions, GINT_TO_POINTER ((gint) session->priv->id));
return FALSE;
}
static XDMCPSession *
add_session (XDMCPServer *server)
{
XDMCPSession *session;
guint16 id;
do
{
id = g_random_int () & 0xFFFFFFFF;
} while (g_hash_table_lookup (server->priv->sessions, GINT_TO_POINTER ((gint) id)));
session = xdmcp_session_new (id);
session->priv->server = server;
g_hash_table_insert (server->priv->sessions, GINT_TO_POINTER ((gint) id), g_object_ref (session));
session->priv->inactive_timeout = g_timeout_add (MANAGE_TIMEOUT, (GSourceFunc) session_timeout_cb, session);
return session;
}
static XDMCPSession *
get_session (XDMCPServer *server, guint16 id)
{
return g_hash_table_lookup (server->priv->sessions, GINT_TO_POINTER ((gint) id));
}
static void
send_packet (GSocket *socket, GSocketAddress *address, XDMCPPacket *packet)
{
guint8 data[1024];
gssize n_written;
g_debug ("Send %s", xdmcp_packet_tostring (packet));
n_written = xdmcp_packet_encode (packet, data, 1024);
if (n_written < 0)
g_critical ("Failed to encode XDMCP packet");
else
{
GError *error = NULL;
g_socket_send_to (socket, address, (gchar *) data, n_written, NULL, &error);
if (error)
g_warning ("Error sending packet: %s", error->message);
g_clear_error (&error);
}
}
static const gchar *
get_authentication_name (XDMCPServer *server)
{
if (server->priv->key)
return "XDM-AUTHENTICATION-1";
else
return "";
}
static void
handle_query (XDMCPServer *server, GSocket *socket, GSocketAddress *address, XDMCPPacket *packet)
{
XDMCPPacket *response;
gchar **i;
gchar *authentication_name = NULL;
/* If no authentication requested and we are configured for none then allow */
if (packet->Query.authentication_names[0] == NULL && server->priv->key == NULL)
authentication_name = "";
for (i = packet->Query.authentication_names; *i; i++)
{
if (strcmp (*i, get_authentication_name (server)) == 0 && server->priv->key != NULL)
{
authentication_name = *i;
break;
}
}
if (authentication_name)
{
response = xdmcp_packet_alloc (XDMCP_Willing);
response->Willing.authentication_name = g_strdup (authentication_name);
response->Willing.hostname = g_strdup (server->priv->hostname);
response->Willing.status = g_strdup (server->priv->status);
}
else
{
response = xdmcp_packet_alloc (XDMCP_Unwilling);
response->Unwilling.hostname = g_strdup (server->priv->hostname);
if (server->priv->key)
response->Unwilling.status = g_strdup_printf ("No matching authentication, server requires %s", get_authentication_name (server));
else
response->Unwilling.status = g_strdup ("Server does not support authentication");
}
send_packet (socket, address, response);
xdmcp_packet_free (response);
}
static guint8
atox (char c)
{
if (c >= '0' && c <= '9')
return c - '0';
if (c >= 'a' && c <= 'f')
return c - 'a' + 10;
if (c >= 'A' && c <= 'F')
return c - 'A' + 10;
return 0;
}
static void
decode_key (const gchar *key, guint8 *data)
{
gint i;
memset (data, 0, 8);
if (strncmp (key, "0x", 2) == 0 || strncmp (key, "0X", 2) == 0)
{
for (i = 0; i < 8; i++)
{
if (key[i*2] == '\0')
break;
data[i] |= atox (key[i*2]) << 8;
if (key[i*2+1] == '\0')
break;
data[i] |= atox (key[i*2+1]);
}
}
else
{
for (i = 1; i < 8 && key[i-1]; i++)
data[i] = key[i-1];
}
}
static void
handle_request (XDMCPServer *server, GSocket *socket, GSocketAddress *address, XDMCPPacket *packet)
{
int i;
XDMCPPacket *response;
XDMCPSession *session;
guint8 *authentication_data = NULL;
gsize authentication_data_length = 0;
gboolean match_authorization = FALSE;
gchar *authorization_name;
guint8 *authorization_data = NULL;
gsize authorization_data_length = 0;
guint8 *session_authorization_data = NULL;
gsize session_authorization_data_length = 0;
gchar **j;
guint16 family;
GInetAddress *x_server_address = NULL;
gchar *display_number;
XdmAuthKeyRec rho;
/* Try and find an IPv6 address */
for (i = 0; i < packet->Request.n_connections; i++)
{
XDMCPConnection *connection = &packet->Request.connections[i];
if (connection->type == XAUTH_FAMILY_INTERNET6 && connection->address.length == 16)
{
family = connection->type;
x_server_address = g_inet_address_new_from_bytes (connection->address.data, G_SOCKET_FAMILY_IPV6);
/* We can't use link-local addresses, as we need to know what interface it is on */
if (g_inet_address_get_is_link_local (x_server_address))
{
g_object_unref (x_server_address);
x_server_address = NULL;
}
else
break;
}
}
/* If no IPv6 address, then try and find an IPv4 one */
if (!x_server_address)
{
for (i = 0; i < packet->Request.n_connections; i++)
{
XDMCPConnection *connection = &packet->Request.connections[i];
if (connection->type == XAUTH_FAMILY_INTERNET && connection->address.length == 4)
{
family = connection->type;
x_server_address = g_inet_address_new_from_bytes (connection->address.data, G_SOCKET_FAMILY_IPV4);
break;
}
}
}
/* Decline if haven't got an address we can connect on */
if (!x_server_address)
{
response = xdmcp_packet_alloc (XDMCP_Decline);
response->Decline.status = g_strdup ("No valid address found");
response->Decline.authentication_name = g_strdup (packet->Request.authentication_name);
response->Decline.authentication_data.data = authentication_data;
response->Decline.authentication_data.length = authentication_data_length;
send_packet (socket, address, response);
xdmcp_packet_free (response);
return;
}
/* Must be using our authentication scheme */
if (strcmp (packet->Request.authentication_name, get_authentication_name (server)) != 0)
{
response = xdmcp_packet_alloc (XDMCP_Decline);
if (server->priv->key)
response->Decline.status = g_strdup_printf ("Server only supports %s authentication", get_authentication_name (server));
else
response->Decline.status = g_strdup ("Server does not support authentication");
response->Decline.authentication_name = g_strdup ("");
send_packet (socket, address, response);
xdmcp_packet_free (response);
return;
}
/* Perform requested authentication */
if (server->priv->key)
{
guint8 input[8], key[8];
memset (input, 0, 8);
memcpy (input, packet->Request.authentication_data.data, packet->Request.authentication_data.length > 8 ? 8 : packet->Request.authentication_data.length);
/* Setup key */
decode_key (server->priv->key, key);
/* Decode message from server */
authentication_data = g_malloc (sizeof (guint8) * 8);
authentication_data_length = 8;
XdmcpUnwrap (input, key, rho.data, authentication_data_length);
XdmcpIncrementKey (&rho);
XdmcpWrap (rho.data, key, authentication_data, authentication_data_length);
authorization_name = g_strdup ("XDM-AUTHORIZATION-1");
}
else
authorization_name = g_strdup ("MIT-MAGIC-COOKIE-1");
/* Check if they support our authorization */
for (j = packet->Request.authorization_names; *j; j++)
{
if (strcmp (*j, authorization_name) == 0)
{
match_authorization = TRUE;
break;
}
}
/* Decline if don't support out authorization */
if (!match_authorization)
{
response = xdmcp_packet_alloc (XDMCP_Decline);
response->Decline.status = g_strdup_printf ("Server requires %s authorization", authorization_name);
g_free (authorization_name);
response->Decline.authentication_name = g_strdup (packet->Request.authentication_name);
response->Decline.authentication_data.data = authentication_data;
response->Decline.authentication_data.length = authentication_data_length;
send_packet (socket, address, response);
xdmcp_packet_free (response);
return;
}
/* Perform requested authorization */
if (server->priv->key)
{
gint i;
guint8 key[8], session_key[8];
/* Setup key */
decode_key (server->priv->key, key);
/* Generate a private session key */
// FIXME: Pick a good DES key?
session_key[0] = 0;
for (i = 1; i < 8; i++)
session_key[i] = g_random_int () & 0xFF;
/* Encrypt the session key and send it to the server */
authorization_data = g_malloc (8);
authorization_data_length = 8;
XdmcpWrap (session_key, key, authorization_data, authorization_data_length);
/* Authorization data is the number received from the client followed by the private session key */
session_authorization_data = g_malloc (16);
session_authorization_data_length = 16;
XdmcpDecrementKey (&rho);
memcpy (session_authorization_data, rho.data, 8);
memcpy (session_authorization_data + 8, session_key, 8);
}
else
{
XAuthority *auth;
/* Data is the cookie */
auth = x_authority_new_cookie (XAUTH_FAMILY_WILD, NULL, 0, "");
authorization_data = x_authority_copy_authorization_data (auth);
authorization_data_length = x_authority_get_authorization_data_length (auth);
session_authorization_data = x_authority_copy_authorization_data (auth);
session_authorization_data_length = x_authority_get_authorization_data_length (auth);
g_object_unref (auth);
}
session = add_session (server);
session->priv->address = x_server_address;
session->priv->display_number = packet->Request.display_number;
display_number = g_strdup_printf ("%d", packet->Request.display_number);
/* We need to check if this is the loopback address and set the authority
* for a local connection if this is so as XCB treats "127.0.0.1" as local
* always */
if (g_inet_address_get_is_loopback (x_server_address))
{
gchar hostname[1024];
gethostname (hostname, 1024);
session->priv->authority = x_authority_new (XAUTH_FAMILY_LOCAL,
(guint8 *) hostname,
strlen (hostname),
display_number,
authorization_name,
session_authorization_data,
session_authorization_data_length);
}
else
session->priv->authority = x_authority_new (family,
g_inet_address_to_bytes (G_INET_ADDRESS (x_server_address)),
g_inet_address_get_native_size (G_INET_ADDRESS (x_server_address)),
display_number,
authorization_name,
session_authorization_data,
session_authorization_data_length);
g_free (display_number);
response = xdmcp_packet_alloc (XDMCP_Accept);
response->Accept.session_id = xdmcp_session_get_id (session);
response->Accept.authentication_name = g_strdup (packet->Request.authentication_name);
response->Accept.authentication_data.data = authentication_data;
response->Accept.authentication_data.length = authentication_data_length;
response->Accept.authorization_name = authorization_name;
response->Accept.authorization_data.data = authorization_data;
response->Accept.authorization_data.length = authorization_data_length;
send_packet (socket, address, response);
xdmcp_packet_free (response);
}
static void
handle_manage (XDMCPServer *server, GSocket *socket, GSocketAddress *address, XDMCPPacket *packet)
{
XDMCPSession *session;
gboolean result;
session = get_session (server, packet->Manage.session_id);
if (!session)
{
XDMCPPacket *response;
response = xdmcp_packet_alloc (XDMCP_Refuse);
response->Refuse.session_id = packet->Manage.session_id;
send_packet (socket, address, response);
xdmcp_packet_free (response);
return;
}
/* Ignore duplicate requests */
if (session->priv->started)
{
if (session->priv->display_number != packet->Manage.display_number ||
strcmp (session->priv->display_class, packet->Manage.display_class) != 0)
g_debug ("Ignoring duplicate Manage with different data");
return;
}
/* Reject if has changed display number */
if (packet->Manage.display_number != session->priv->display_number)
{
XDMCPPacket *response;
g_debug ("Received Manage for display number %d, but Request was %d", packet->Manage.display_number, session->priv->display_number);
response = xdmcp_packet_alloc (XDMCP_Refuse);
response->Refuse.session_id = packet->Manage.session_id;
send_packet (socket, address, response);
xdmcp_packet_free (response);
}
session->priv->display_class = g_strdup (packet->Manage.display_class);
g_signal_emit (server, signals[NEW_SESSION], 0, session, &result);
if (result)
{
/* Cancel the inactive timer */
if (session->priv->inactive_timeout)
g_source_remove (session->priv->inactive_timeout);
session->priv->started = TRUE;
}
else
{
XDMCPPacket *response;
response = xdmcp_packet_alloc (XDMCP_Failed);
response->Failed.session_id = packet->Manage.session_id;
response->Failed.status = g_strdup_printf ("Failed to connect to display :%d", packet->Manage.display_number);
send_packet (socket, address, response);
xdmcp_packet_free (response);
}
}
static void
handle_keep_alive (XDMCPServer *server, GSocket *socket, GSocketAddress *address, XDMCPPacket *packet)
{
XDMCPPacket *response;
XDMCPSession *session;
gboolean alive = FALSE;
session = get_session (server, packet->KeepAlive.session_id);
if (session)
alive = TRUE; // FIXME: xdmcp_session_get_alive (session);
response = xdmcp_packet_alloc (XDMCP_Alive);
response->Alive.session_running = alive;
response->Alive.session_id = alive ? packet->KeepAlive.session_id : 0;
send_packet (socket, address, response);
xdmcp_packet_free (response);
}
static gboolean
read_cb (GSocket *socket, GIOCondition condition, XDMCPServer *server)
{
GSocketAddress *address;
gchar data[1024];
GError *error = NULL;
gssize n_read;
n_read = g_socket_receive_from (socket, &address, data, 1024, NULL, &error);
if (error)
g_warning ("Failed to read from XDMCP socket: %s", error->message);
g_clear_error (&error);
if (n_read > 0)
{
XDMCPPacket *packet;
packet = xdmcp_packet_decode ((guint8 *)data, n_read);
if (packet)
{
g_debug ("Got %s", xdmcp_packet_tostring (packet));
switch (packet->opcode)
{
case XDMCP_BroadcastQuery:
case XDMCP_Query:
case XDMCP_IndirectQuery:
handle_query (server, socket, address, packet);
break;
case XDMCP_Request:
handle_request (server, socket, address, packet);
break;
case XDMCP_Manage:
handle_manage (server, socket, address, packet);
break;
case XDMCP_KeepAlive:
handle_keep_alive (server, socket, address, packet);
break;
default:
g_warning ("Got unexpected XDMCP packet %d", packet->opcode);
break;
}
xdmcp_packet_free (packet);
}
}
return TRUE;
}
static GSocket *
open_udp_socket (GSocketFamily family, guint port, GError **error)
{
GSocket *socket;
GSocketAddress *address;
gboolean result;
socket = g_socket_new (family, G_SOCKET_TYPE_DATAGRAM, G_SOCKET_PROTOCOL_UDP, error);
if (!socket)
return NULL;
address = g_inet_socket_address_new (g_inet_address_new_any (family), port);
result = g_socket_bind (socket, address, TRUE, error);
if (!result)
{
g_object_unref (socket);
return NULL;
}
return socket;
}
gboolean
xdmcp_server_start (XDMCPServer *server)
{
GSource *source;
GError *error = NULL;
g_return_val_if_fail (server != NULL, FALSE);
server->priv->socket = open_udp_socket (G_SOCKET_FAMILY_IPV4, server->priv->port, &error);
if (error)
g_warning ("Failed to create IPv4 XDMCP socket: %s", error->message);
g_clear_error (&error);
if (server->priv->socket)
{
source = g_socket_create_source (server->priv->socket, G_IO_IN, NULL);
g_source_set_callback (source, (GSourceFunc) read_cb, server, NULL);
g_source_attach (source, NULL);
}
server->priv->socket6 = open_udp_socket (G_SOCKET_FAMILY_IPV6, server->priv->port, &error);
if (error)
g_warning ("Failed to create IPv6 XDMCP socket: %s", error->message);
g_clear_error (&error);
if (server->priv->socket6)
{
source = g_socket_create_source (server->priv->socket6, G_IO_IN, NULL);
g_source_set_callback (source, (GSourceFunc) read_cb, server, NULL);
g_source_attach (source, NULL);
}
if (!server->priv->socket && !server->priv->socket6)
return FALSE;
return TRUE;
}
static void
xdmcp_server_init (XDMCPServer *server)
{
server->priv = G_TYPE_INSTANCE_GET_PRIVATE (server, XDMCP_SERVER_TYPE, XDMCPServerPrivate);
server->priv->port = XDM_UDP_PORT;
server->priv->hostname = g_strdup ("");
server->priv->status = g_strdup ("");
server->priv->sessions = g_hash_table_new_full (g_direct_hash, g_direct_equal, NULL, g_object_unref);
}
static void
xdmcp_server_finalize (GObject *object)
{
XDMCPServer *self;
self = XDMCP_SERVER (object);
if (self->priv->socket)
g_object_unref (self->priv->socket);
if (self->priv->socket6)
g_object_unref (self->priv->socket6);
g_free (self->priv->hostname);
g_free (self->priv->status);
g_free (self->priv->key);
g_hash_table_unref (self->priv->sessions);
G_OBJECT_CLASS (xdmcp_server_parent_class)->finalize (object);
}
static void
xdmcp_server_class_init (XDMCPServerClass *klass)
{
GObjectClass *object_class = G_OBJECT_CLASS (klass);
object_class->finalize = xdmcp_server_finalize;
g_type_class_add_private (klass, sizeof (XDMCPServerPrivate));
signals[NEW_SESSION] =
g_signal_new ("new-session",
G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (XDMCPServerClass, new_session),
g_signal_accumulator_true_handled,
NULL,
NULL,
G_TYPE_BOOLEAN, 1, XDMCP_SESSION_TYPE);
}
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