lbbs/src/fork.c

/***************************************************************************
                                                  fork.c  -  description
                                                         -------------------
        Copyright            : (C) 2004-2025 by Leaflet
        Email                : leaflet@leafok.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.                                   *
 *                                                                         *
 ***************************************************************************/

#include "common.h"
#include "bbs_main.h"
#include "bbs.h"
#include "log.h"
#include "io.h"
#include "fork.h"
#include "menu.h"
#include "database.h"
#include "login.h"
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <libssh/libssh.h>
#include <libssh/server.h>
#include <libssh/callbacks.h>

#define SSH_AUTH_MAX_DURATION 60 // seconds

struct ssl_server_cb_data_t
{
        int tries;
        int error;
};

static int auth_password(ssh_session session, const char *user,
                                                 const char *password, void *userdata)
{
        MYSQL *db;
        struct ssl_server_cb_data_t *p_data = userdata;
        int ret;

        if ((db = db_open()) == NULL)
        {
                return SSH_AUTH_ERROR;
        }

        if (strcmp(user, "guest") == 0)
        {
                ret = load_guest_info(db);
        }
        else
        {
                ret = check_user(db, user, password);
        }

        mysql_close(db);

        if (ret == 0)
        {
                return SSH_AUTH_SUCCESS;
        }

        if ((++(p_data->tries)) >= BBS_login_retry_times)
        {
                p_data->error = 1;
        }

        return SSH_AUTH_DENIED;
}

static int pty_request(ssh_session session, ssh_channel channel, const char *term,
                                           int x, int y, int px, int py, void *userdata)
{
        return 0;
}

static int shell_request(ssh_session session, ssh_channel channel, void *userdata)
{
        return 0;
}

static struct ssh_channel_callbacks_struct channel_cb = {
        .channel_pty_request_function = pty_request,
        .channel_shell_request_function = shell_request};

static ssh_channel new_session_channel(ssh_session session, void *userdata)
{
        if (SSH_channel != NULL)
        {
                return NULL;
        }

        SSH_channel = ssh_channel_new(session);
        ssh_callbacks_init(&channel_cb);
        ssh_set_channel_callbacks(SSH_channel, &channel_cb);

        return SSH_channel;
}

int fork_server(void)
{
        ssh_event event;
        int pid;
        int i;
        int ret;

        struct ssl_server_cb_data_t cb_data = {
                .tries = 0,
                .error = 0,
        };

        struct ssh_server_callbacks_struct cb = {
                .userdata = &cb_data,
                .auth_password_function = auth_password,
                .channel_open_request_session_function = new_session_channel,
        };

        pid = fork();

        if (pid > 0) // Parent process
        {
                SYS_child_process_count++;
                log_common("Child process (%d) start\n", pid);
                return pid;
        }
        else if (pid < 0) // Error
        {
                log_error("fork() error (%d)\n", errno);
                return -1;
        }

        // Child process

        if (close(socket_server[0]) == -1 || close(socket_server[1]) == -1)
        {
                log_error("Close server socket failed\n");
        }

        SSH_session = ssh_new();

        if (SSH_v2)
        {
                if (ssh_bind_accept_fd(sshbind, SSH_session, socket_client) != SSH_OK)
                {
                        log_error("ssh_bind_accept_fd() error: %s\n", ssh_get_error(SSH_session));
                        goto cleanup;
                }

                ssh_bind_free(sshbind);

                ssh_callbacks_init(&cb);
                ssh_set_server_callbacks(SSH_session, &cb);

                if (ssh_handle_key_exchange(SSH_session))
                {
                        log_error("ssh_handle_key_exchange() error: %s\n", ssh_get_error(SSH_session));
                        goto cleanup;
                }
                ssh_set_auth_methods(SSH_session, SSH_AUTH_METHOD_PASSWORD);

                event = ssh_event_new();
                ssh_event_add_session(event, SSH_session);

                for (i = 0; i < SSH_AUTH_MAX_DURATION && !SYS_server_exit && !cb_data.error && SSH_channel == NULL; i++)
                {
                        ret = ssh_event_dopoll(event, 1000); // 1 second
                        if (ret == SSH_ERROR)
                        {
                                log_error("ssh_event_dopoll() error: %s\n", ssh_get_error(SSH_session));
                                goto cleanup;
                        }
                }

                if (cb_data.error)
                {
                        log_error("SSH auth error, tried %d times\n", cb_data.tries);
                        goto cleanup;
                }
        }

        // Redirect Input
        close(STDIN_FILENO);
        if (dup2(socket_client, STDIN_FILENO) == -1)
        {
                log_error("Redirect stdin to client socket failed\n");
                goto cleanup;
        }

        // Redirect Output
        close(STDOUT_FILENO);
        if (dup2(socket_client, STDOUT_FILENO) == -1)
        {
                log_error("Redirect stdout to client socket failed\n");
                goto cleanup;
        }

        SYS_child_process_count = 0;

        bbs_main();

cleanup:
        // Child process exit
        SYS_server_exit = 1;

        if (SSH_v2)
        {
                ssh_channel_free(SSH_channel);
                ssh_disconnect(SSH_session);
        }
        else if (close(socket_client) == -1)
        {
                log_error("Close client socket failed\n");
        }

        ssh_free(SSH_session);
        ssh_finalize();

        // Close Input and Output for client
        close(STDIN_FILENO);
        close(STDOUT_FILENO);

        log_common("Process exit normally\n");
        log_end();

        _exit(0);

        return 0;
}
1	sysadm	1.1	/***************************************************************************
2	sysadm	1.12	fork.c - description
3			-------------------
4	sysadm	1.15	Copyright : (C) 2004-2025 by Leaflet
5			Email : leaflet@leafok.com
6	sysadm	1.1	***************************************************************************/
7
8			/***************************************************************************
9			* *
10			* This program is free software; you can redistribute it and/or modify *
11			* it under the terms of the GNU General Public License as published by *
12	sysadm	1.15	* the Free Software Foundation; either version 3 of the License, or *
13	sysadm	1.1	* (at your option) any later version. *
14			* *
15			***************************************************************************/
16
17	sysadm	1.2	#include "common.h"
18	sysadm	1.13	#include "bbs_main.h"
19	sysadm	1.25	#include "bbs.h"
20	sysadm	1.13	#include "log.h"
21	sysadm	1.7	#include "io.h"
22	sysadm	1.13	#include "fork.h"
23	sysadm	1.19	#include "menu.h"
24	sysadm	1.25	#include "database.h"
25			#include "login.h"
26	sysadm	1.14	#include <stdio.h>
27	sysadm	1.7	#include <string.h>
28	sysadm	1.18	#include <signal.h>
29	sysadm	1.13	#include <unistd.h>
30			#include <stdlib.h>
31	sysadm	1.16	#include <errno.h>
32	sysadm	1.25	#include <libssh/libssh.h>
33			#include <libssh/server.h>
34			#include <libssh/callbacks.h>
35	sysadm	1.3
36	sysadm	1.25	#define SSH_AUTH_MAX_DURATION 60 // seconds
37
38			struct ssl_server_cb_data_t
39			{
40			int tries;
41			int error;
42			};
43
44			static int auth_password(ssh_session session, const char *user,
45			const char password, void userdata)
46			{
47			MYSQL *db;
48			struct ssl_server_cb_data_t *p_data = userdata;
49			int ret;
50
51			if ((db = db_open()) == NULL)
52			{
53			return SSH_AUTH_ERROR;
54			}
55
56			if (strcmp(user, "guest") == 0)
57			{
58			ret = load_guest_info(db);
59			}
60			else
61			{
62			ret = check_user(db, user, password);
63			}
64
65			mysql_close(db);
66
67			if (ret == 0)
68			{
69			return SSH_AUTH_SUCCESS;
70			}
71
72			if ((++(p_data->tries)) >= BBS_login_retry_times)
73			{
74			p_data->error = 1;
75			}
76
77			return SSH_AUTH_DENIED;
78			}
79
80			static int pty_request(ssh_session session, ssh_channel channel, const char *term,
81			int x, int y, int px, int py, void *userdata)
82			{
83			return 0;
84			}
85
86			static int shell_request(ssh_session session, ssh_channel channel, void *userdata)
87			{
88			return 0;
89			}
90
91			static struct ssh_channel_callbacks_struct channel_cb = {
92			.channel_pty_request_function = pty_request,
93			.channel_shell_request_function = shell_request};
94
95			static ssh_channel new_session_channel(ssh_session session, void *userdata)
96	sysadm	1.3	{
97	sysadm	1.25	if (SSH_channel != NULL)
98			{
99			return NULL;
100			}
101
102			SSH_channel = ssh_channel_new(session);
103			ssh_callbacks_init(&channel_cb);
104			ssh_set_channel_callbacks(SSH_channel, &channel_cb);
105
106			return SSH_channel;
107			}
108
109	sysadm	1.26	int fork_server(void)
110	sysadm	1.25	{
111			ssh_event event;
112	sysadm	1.12	int pid;
113	sysadm	1.25	int i;
114			int ret;
115
116			struct ssl_server_cb_data_t cb_data = {
117			.tries = 0,
118			.error = 0,
119			};
120
121			struct ssh_server_callbacks_struct cb = {
122			.userdata = &cb_data,
123			.auth_password_function = auth_password,
124			.channel_open_request_session_function = new_session_channel,
125			};
126	sysadm	1.10
127	sysadm	1.14	pid = fork();
128
129			if (pid > 0) // Parent process
130	sysadm	1.12	{
131			SYS_child_process_count++;
132	sysadm	1.24	log_common("Child process (%d) start\n", pid);
133	sysadm	1.22	return pid;
134	sysadm	1.12	}
135	sysadm	1.14	else if (pid < 0) // Error
136			{
137	sysadm	1.16	log_error("fork() error (%d)\n", errno);
138	sysadm	1.12	return -1;
139	sysadm	1.14	}
140	sysadm	1.12
141	sysadm	1.14	// Child process
142	sysadm	1.26
143			if (close(socket_server[0]) == -1 \|\| close(socket_server[1]) == -1)
144	sysadm	1.12	{
145			log_error("Close server socket failed\n");
146			}
147
148	sysadm	1.25	SSH_session = ssh_new();
149
150			if (SSH_v2)
151			{
152			if (ssh_bind_accept_fd(sshbind, SSH_session, socket_client) != SSH_OK)
153			{
154			log_error("ssh_bind_accept_fd() error: %s\n", ssh_get_error(SSH_session));
155			goto cleanup;
156			}
157
158			ssh_bind_free(sshbind);
159
160			ssh_callbacks_init(&cb);
161			ssh_set_server_callbacks(SSH_session, &cb);
162
163			if (ssh_handle_key_exchange(SSH_session))
164			{
165			log_error("ssh_handle_key_exchange() error: %s\n", ssh_get_error(SSH_session));
166			goto cleanup;
167			}
168			ssh_set_auth_methods(SSH_session, SSH_AUTH_METHOD_PASSWORD);
169
170			event = ssh_event_new();
171			ssh_event_add_session(event, SSH_session);
172
173			for (i = 0; i < SSH_AUTH_MAX_DURATION && !SYS_server_exit && !cb_data.error && SSH_channel == NULL; i++)
174			{
175			ret = ssh_event_dopoll(event, 1000); // 1 second
176			if (ret == SSH_ERROR)
177			{
178			log_error("ssh_event_dopoll() error: %s\n", ssh_get_error(SSH_session));
179			goto cleanup;
180			}
181			}
182
183			if (cb_data.error)
184			{
185			log_error("SSH auth error, tried %d times\n", cb_data.tries);
186			goto cleanup;
187			}
188			}
189
190	sysadm	1.12	// Redirect Input
191	sysadm	1.14	close(STDIN_FILENO);
192			if (dup2(socket_client, STDIN_FILENO) == -1)
193	sysadm	1.12	{
194			log_error("Redirect stdin to client socket failed\n");
195	sysadm	1.23	goto cleanup;
196	sysadm	1.12	}
197
198			// Redirect Output
199	sysadm	1.14	close(STDOUT_FILENO);
200			if (dup2(socket_client, STDOUT_FILENO) == -1)
201	sysadm	1.12	{
202			log_error("Redirect stdout to client socket failed\n");
203	sysadm	1.23	goto cleanup;
204	sysadm	1.12	}
205
206	sysadm	1.18	SYS_child_process_count = 0;
207
208	sysadm	1.12	bbs_main();
209
210	sysadm	1.23	cleanup:
211	sysadm	1.17	// Child process exit
212			SYS_server_exit = 1;
213
214	sysadm	1.25	if (SSH_v2)
215			{
216			ssh_channel_free(SSH_channel);
217			ssh_disconnect(SSH_session);
218			}
219			else if (close(socket_client) == -1)
220	sysadm	1.12	{
221			log_error("Close client socket failed\n");
222			}
223
224	sysadm	1.25	ssh_free(SSH_session);
225			ssh_finalize();
226
227	sysadm	1.12	// Close Input and Output for client
228	sysadm	1.14	close(STDIN_FILENO);
229			close(STDOUT_FILENO);
230	sysadm	1.9
231	sysadm	1.24	log_common("Process exit normally\n");
232	sysadm	1.12	log_end();
233	sysadm	1.3
234	sysadm	1.19	_exit(0);
235	sysadm	1.23
236	sysadm	1.12	return 0;
237	sysadm	1.3	}
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