matt335672
3e38d9be80
The start session method is reworked to pass a response back to the client. If the method was successful, a session list entry is created. This is different to the provious behaviour, where we created the session list entry unconditionally. This new arrangement means that we need a different way to avoid a race condition where two users may try to create a session at the same time, and end up with the same display. We do this by keeping track of newly allocated displays as part of the SCP connections. When we allocate a display, the SCP connection displays are also taken into account.
135 lines
3.5 KiB
C
135 lines
3.5 KiB
C
/**
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* xrdp: A Remote Desktop Protocol server.
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*
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* Copyright (C) Jay Sorg 2004-2025
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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*
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* @file display_utils.c
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* @brief Definition of utility calls related to display handling
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* @author Matt Burt
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*/
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#if defined(HAVE_CONFIG_H)
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#include <config_ac.h>
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#endif
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#include <stdio.h>
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#include "arch.h"
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#include "display_utils.h"
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#include "log.h"
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#include "os_calls.h"
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#include "sesman.h"
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#include "sesman_config.h"
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#include "set_int.h"
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#include "xrdp_sockets.h"
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/******************************************************************************/
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/**
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*
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* @brief checks if there's a server running on a display
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* @param display the display to check
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* @return 0 if there isn't a display running, nonzero otherwise
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*
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*/
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static int
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x_server_running_check_ports(int display)
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{
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char text[256];
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int x_running;
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int sck;
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(void)snprintf(text, sizeof(text), X11_UNIX_SOCKET_STR, display);
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x_running = g_file_exist(text);
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if (!x_running)
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{
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LOG(LOG_LEVEL_DEBUG, "Did not find a running X server at %s", text);
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(void)snprintf(text, sizeof(text), "/tmp/.X%d-lock", display);
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x_running = g_file_exist(text);
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}
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if (!x_running) /* check 59xx */
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{
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LOG(LOG_LEVEL_DEBUG, "Did not find a running X server at %s", text);
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if ((sck = g_tcp_socket()) != -1)
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{
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(void)snprintf(text, sizeof(text), "59%2.2d", display);
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x_running = g_tcp_bind(sck, text);
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g_tcp_close(sck);
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}
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}
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if (!x_running) /* check 60xx */
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{
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LOG(LOG_LEVEL_DEBUG, "Did not find a running X server at %s", text);
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if ((sck = g_tcp_socket()) != -1)
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{
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(void)snprintf(text, sizeof(text), "60%2.2d", display);
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x_running = g_tcp_bind(sck, text);
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g_tcp_close(sck);
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}
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}
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if (!x_running) /* check 62xx */
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{
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LOG(LOG_LEVEL_DEBUG, "Did not find a running X server at %s", text);
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if ((sck = g_tcp_socket()) != -1)
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{
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(void)snprintf(text, sizeof(text), "62%2.2d", display);
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x_running = g_tcp_bind(sck, text);
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g_tcp_close(sck);
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}
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}
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if (x_running)
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{
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LOG(LOG_LEVEL_INFO, "Found X server running at %s", text);
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}
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return x_running;
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}
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/******************************************************************************/
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int
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display_utils_get_free_display(const struct set_int *alloc_displays)
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{
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int display;
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for (display = g_cfg->sess.x11_display_offset;
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(unsigned int)display <= g_cfg->sess.max_display_number;
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++display)
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{
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// Have we already allocated this one?
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if (!set_int_contains(alloc_displays, display))
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{
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if (!x_server_running_check_ports(display))
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{
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return display;
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}
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}
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}
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LOG(LOG_LEVEL_ERROR,
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"X server -- no display in range (%d to %d) is available",
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g_cfg->sess.x11_display_offset,
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g_cfg->sess.max_display_number);
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return -1;
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}
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