/[LeafOK_CVS]/lbbs/src/net_server.c
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Revision 1.71 - (show annotations)
Mon Sep 22 05:07:22 2025 UTC (5 months, 3 weeks ago) by sysadm
Branch: MAIN
Changes since 1.70: +15 -0 lines
Content type: text/x-csrc
Add timeout control for SSH handshake and authentication

1 /***************************************************************************
2 net_server.c - description
3 -------------------
4 Copyright : (C) 2004-2025 by Leaflet
5 Email : leaflet@leafok.com
6 ***************************************************************************/
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 * the Free Software Foundation; either version 3 of the License, or *
13 * (at your option) any later version. *
14 * *
15 ***************************************************************************/
16
17 #include "bbs.h"
18 #include "bbs_main.h"
19 #include "common.h"
20 #include "database.h"
21 #include "file_loader.h"
22 #include "io.h"
23 #include "init.h"
24 #include "log.h"
25 #include "login.h"
26 #include "menu.h"
27 #include "net_server.h"
28 #include "section_list.h"
29 #include "section_list_loader.h"
30 #include <errno.h>
31 #include <fcntl.h>
32 #include <signal.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36 #include <arpa/inet.h>
37 #include <libssh/callbacks.h>
38 #include <libssh/libssh.h>
39 #include <libssh/server.h>
40 #include <netinet/in.h>
41 #include <sys/epoll.h>
42 #include <sys/socket.h>
43 #include <sys/syscall.h>
44 #include <sys/types.h>
45 #include <sys/wait.h>
46 #include <systemd/sd-daemon.h>
47
48 #define WAIT_CHILD_PROCESS_EXIT_TIMEOUT 5 // second
49 #define WAIT_CHILD_PROCESS_KILL_TIMEOUT 1 // second
50
51 struct process_sockaddr_t
52 {
53 pid_t pid;
54 in_addr_t s_addr;
55 };
56 typedef struct process_sockaddr_t PROCESS_SOCKADDR;
57
58 static PROCESS_SOCKADDR process_sockaddr_pool[MAX_CLIENT_LIMIT];
59
60 #define SSH_AUTH_MAX_DURATION (60 * 1000) // milliseconds
61
62 struct ssl_server_cb_data_t
63 {
64 int tries;
65 int error;
66 };
67
68 static int auth_password(ssh_session session, const char *user,
69 const char *password, void *userdata)
70 {
71 struct ssl_server_cb_data_t *p_data = userdata;
72 int ret;
73
74 if (strcmp(user, "guest") == 0)
75 {
76 ret = load_guest_info();
77 }
78 else
79 {
80 ret = check_user(user, password);
81 }
82
83 if (ret == 0)
84 {
85 return SSH_AUTH_SUCCESS;
86 }
87
88 if ((++(p_data->tries)) >= BBS_login_retry_times)
89 {
90 p_data->error = 1;
91 }
92
93 return SSH_AUTH_DENIED;
94 }
95
96 static int pty_request(ssh_session session, ssh_channel channel, const char *term,
97 int x, int y, int px, int py, void *userdata)
98 {
99 return 0;
100 }
101
102 static int shell_request(ssh_session session, ssh_channel channel, void *userdata)
103 {
104 return 0;
105 }
106
107 static struct ssh_channel_callbacks_struct channel_cb = {
108 .channel_pty_request_function = pty_request,
109 .channel_shell_request_function = shell_request};
110
111 static ssh_channel new_session_channel(ssh_session session, void *userdata)
112 {
113 if (SSH_channel != NULL)
114 {
115 return NULL;
116 }
117
118 SSH_channel = ssh_channel_new(session);
119 ssh_callbacks_init(&channel_cb);
120 ssh_set_channel_callbacks(SSH_channel, &channel_cb);
121
122 return SSH_channel;
123 }
124
125 static int fork_server(void)
126 {
127 ssh_event event;
128 long int ssh_timeout = 0;
129 int pid;
130 int i;
131 int ret;
132
133 struct ssl_server_cb_data_t cb_data = {
134 .tries = 0,
135 .error = 0,
136 };
137
138 struct ssh_server_callbacks_struct cb = {
139 .userdata = &cb_data,
140 .auth_password_function = auth_password,
141 .channel_open_request_session_function = new_session_channel,
142 };
143
144 pid = fork();
145
146 if (pid > 0) // Parent process
147 {
148 SYS_child_process_count++;
149 log_common("Child process (%d) start\n", pid);
150 return pid;
151 }
152 else if (pid < 0) // Error
153 {
154 log_error("fork() error (%d)\n", errno);
155 return -1;
156 }
157
158 // Child process
159
160 if (close(socket_server[0]) == -1 || close(socket_server[1]) == -1)
161 {
162 log_error("Close server socket failed\n");
163 }
164
165 SSH_session = ssh_new();
166
167 if (SSH_v2)
168 {
169 if (ssh_bind_accept_fd(sshbind, SSH_session, socket_client) != SSH_OK)
170 {
171 log_error("ssh_bind_accept_fd() error: %s\n", ssh_get_error(SSH_session));
172 goto cleanup;
173 }
174
175 ssh_bind_free(sshbind);
176
177 ssh_callbacks_init(&cb);
178 ssh_set_server_callbacks(SSH_session, &cb);
179
180 ssh_timeout = 60; // second
181 if (ssh_options_set(SSH_session, SSH_OPTIONS_TIMEOUT, &ssh_timeout) < 0)
182 {
183 log_error("Error setting SSH options: %s\n", ssh_get_error(SSH_session));
184 goto cleanup;
185 }
186
187 if (ssh_handle_key_exchange(SSH_session))
188 {
189 log_error("ssh_handle_key_exchange() error: %s\n", ssh_get_error(SSH_session));
190 goto cleanup;
191 }
192 ssh_set_auth_methods(SSH_session, SSH_AUTH_METHOD_PASSWORD);
193
194 event = ssh_event_new();
195 ssh_event_add_session(event, SSH_session);
196
197 for (i = 0; i < SSH_AUTH_MAX_DURATION && !SYS_server_exit && !cb_data.error && SSH_channel == NULL; i += 100)
198 {
199 ret = ssh_event_dopoll(event, 100); // 0.1 second
200 if (ret == SSH_ERROR)
201 {
202 log_error("ssh_event_dopoll() error: %s\n", ssh_get_error(SSH_session));
203 goto cleanup;
204 }
205 }
206
207 if (cb_data.error)
208 {
209 log_error("SSH auth error, tried %d times\n", cb_data.tries);
210 goto cleanup;
211 }
212
213 ssh_timeout = 0;
214 if (ssh_options_set(SSH_session, SSH_OPTIONS_TIMEOUT, &ssh_timeout) < 0)
215 {
216 log_error("Error setting SSH options: %s\n", ssh_get_error(SSH_session));
217 goto cleanup;
218 }
219 }
220
221 // Redirect Input
222 close(STDIN_FILENO);
223 if (dup2(socket_client, STDIN_FILENO) == -1)
224 {
225 log_error("Redirect stdin to client socket failed\n");
226 goto cleanup;
227 }
228
229 // Redirect Output
230 close(STDOUT_FILENO);
231 if (dup2(socket_client, STDOUT_FILENO) == -1)
232 {
233 log_error("Redirect stdout to client socket failed\n");
234 goto cleanup;
235 }
236
237 SYS_child_process_count = 0;
238
239 bbs_main();
240
241 cleanup:
242 // Child process exit
243 SYS_server_exit = 1;
244
245 if (SSH_v2)
246 {
247 ssh_channel_free(SSH_channel);
248 ssh_disconnect(SSH_session);
249 }
250 else if (close(socket_client) == -1)
251 {
252 log_error("Close client socket failed\n");
253 }
254
255 ssh_free(SSH_session);
256 ssh_finalize();
257
258 // Close Input and Output for client
259 close(STDIN_FILENO);
260 close(STDOUT_FILENO);
261
262 log_common("Process exit normally\n");
263 log_end();
264
265 _exit(0);
266
267 return 0;
268 }
269
270 int net_server(const char *hostaddr, in_port_t port[])
271 {
272 unsigned int addrlen;
273 int ret;
274 int flags[2];
275 struct sockaddr_in sin;
276 struct epoll_event ev, events[MAX_EVENTS];
277 int nfds, epollfd;
278 siginfo_t siginfo;
279 int notify_child_exit = 0;
280 time_t tm_notify_child_exit = time(NULL);
281 int sd_notify_stopping = 0;
282 MENU_SET bbs_menu_new;
283 int i, j;
284 pid_t pid;
285 int ssh_log_level = SSH_LOG_NOLOG;
286
287 ssh_init();
288
289 sshbind = ssh_bind_new();
290
291 if (ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDADDR, hostaddr) < 0 ||
292 ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDPORT, &port) < 0 ||
293 ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_HOSTKEY, SSH_HOST_KEYFILE) < 0 ||
294 ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_HOSTKEY_ALGORITHMS, "ssh-rsa,rsa-sha2-512,rsa-sha2-256") < 0 ||
295 ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_LOG_VERBOSITY, &ssh_log_level) < 0)
296 {
297 log_error("Error setting SSH bind options: %s\n", ssh_get_error(sshbind));
298 ssh_bind_free(sshbind);
299 return -1;
300 }
301
302 epollfd = epoll_create1(0);
303 if (epollfd < 0)
304 {
305 log_error("epoll_create1() error (%d)\n", errno);
306 return -1;
307 }
308
309 // Server socket
310 for (i = 0; i < 2; i++)
311 {
312 socket_server[i] = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
313
314 if (socket_server[i] < 0)
315 {
316 log_error("Create socket_server error (%d)\n", errno);
317 return -1;
318 }
319
320 sin.sin_family = AF_INET;
321 sin.sin_addr.s_addr = (hostaddr[0] != '\0' ? inet_addr(hostaddr) : INADDR_ANY);
322 sin.sin_port = htons(port[i]);
323
324 // Reuse address and port
325 flags[i] = 1;
326 if (setsockopt(socket_server[i], SOL_SOCKET, SO_REUSEADDR, &flags[i], sizeof(flags[i])) < 0)
327 {
328 log_error("setsockopt SO_REUSEADDR error (%d)\n", errno);
329 }
330 if (setsockopt(socket_server[i], SOL_SOCKET, SO_REUSEPORT, &flags[i], sizeof(flags[i])) < 0)
331 {
332 log_error("setsockopt SO_REUSEPORT error (%d)\n", errno);
333 }
334
335 if (bind(socket_server[i], (struct sockaddr *)&sin, sizeof(sin)) < 0)
336 {
337 log_error("Bind address %s:%u error (%d)\n",
338 inet_ntoa(sin.sin_addr), ntohs(sin.sin_port), errno);
339 return -1;
340 }
341
342 if (listen(socket_server[i], 10) < 0)
343 {
344 log_error("Telnet socket listen error (%d)\n", errno);
345 return -1;
346 }
347
348 log_common("Listening at %s:%u\n", inet_ntoa(sin.sin_addr), ntohs(sin.sin_port));
349
350 ev.events = EPOLLIN;
351 ev.data.fd = socket_server[i];
352 if (epoll_ctl(epollfd, EPOLL_CTL_ADD, socket_server[i], &ev) == -1)
353 {
354 log_error("epoll_ctl(socket_server[%d]) error (%d)\n", i, errno);
355 if (close(epollfd) < 0)
356 {
357 log_error("close(epoll) error (%d)\n");
358 }
359 return -1;
360 }
361
362 flags[i] = fcntl(socket_server[i], F_GETFL, 0);
363 fcntl(socket_server[i], F_SETFL, flags[i] | O_NONBLOCK);
364 }
365
366 // Startup complete
367 sd_notifyf(0, "READY=1\n"
368 "STATUS=Listening at %s:%d (Telnet) and %s:%d (SSH2)\n"
369 "MAINPID=%d",
370 hostaddr, port[0], hostaddr, port[1], getpid());
371
372 while (!SYS_server_exit || SYS_child_process_count > 0)
373 {
374 if (SYS_server_exit && !sd_notify_stopping)
375 {
376 sd_notify(0, "STOPPING=1");
377 sd_notify_stopping = 1;
378 }
379
380 while ((SYS_child_exit || SYS_server_exit) && SYS_child_process_count > 0)
381 {
382 SYS_child_exit = 0;
383
384 siginfo.si_pid = 0;
385 ret = waitid(P_ALL, 0, &siginfo, WEXITED | WNOHANG);
386 if (ret == 0 && siginfo.si_pid > 0)
387 {
388 SYS_child_exit = 1; // Retry waitid
389
390 SYS_child_process_count--;
391 log_common("Child process (%d) exited\n", siginfo.si_pid);
392
393 if (siginfo.si_pid != section_list_loader_pid)
394 {
395 i = 0;
396 for (; i < BBS_max_client; i++)
397 {
398 if (process_sockaddr_pool[i].pid == siginfo.si_pid)
399 {
400 process_sockaddr_pool[i].pid = 0;
401 break;
402 }
403 }
404 if (i >= BBS_max_client)
405 {
406 log_error("Child process (%d) not found in process sockaddr pool\n", siginfo.si_pid);
407 }
408 }
409 }
410 else if (ret == 0)
411 {
412 break;
413 }
414 else if (ret < 0)
415 {
416 log_error("Error in waitid: %d\n", errno);
417 break;
418 }
419 }
420
421 if (SYS_server_exit && !SYS_child_exit && SYS_child_process_count > 0)
422 {
423 if (notify_child_exit == 0)
424 {
425 sd_notifyf(0, "STATUS=Notify %d child process to exit", SYS_child_process_count);
426 log_common("Notify %d child process to exit\n", SYS_child_process_count);
427
428 if (kill(0, SIGTERM) < 0)
429 {
430 log_error("Send SIGTERM signal failed (%d)\n", errno);
431 }
432
433 notify_child_exit = 1;
434 tm_notify_child_exit = time(NULL);
435 }
436 else if (notify_child_exit == 1 && time(NULL) - tm_notify_child_exit >= WAIT_CHILD_PROCESS_EXIT_TIMEOUT)
437 {
438 sd_notifyf(0, "STATUS=Kill %d child process", SYS_child_process_count);
439
440 for (i = 0; i < BBS_max_client; i++)
441 {
442 if (process_sockaddr_pool[i].pid != 0)
443 {
444 log_error("Kill child process (pid=%d)\n", process_sockaddr_pool[i].pid);
445 if (kill(process_sockaddr_pool[i].pid, SIGKILL) < 0)
446 {
447 log_error("Send SIGKILL signal failed (%d)\n", errno);
448 }
449 }
450 }
451
452 notify_child_exit = 2;
453 tm_notify_child_exit = time(NULL);
454 }
455 else if (notify_child_exit == 2 && time(NULL) - tm_notify_child_exit >= WAIT_CHILD_PROCESS_KILL_TIMEOUT)
456 {
457 log_error("Main process prepare to exit without waiting for %d child process any longer\n", SYS_child_process_count);
458 SYS_child_process_count = 0;
459 }
460 }
461
462 if (SYS_conf_reload && !SYS_server_exit)
463 {
464 SYS_conf_reload = 0;
465 sd_notify(0, "RELOADING=1");
466
467 // Reload configuration
468 if (load_conf(CONF_BBSD) < 0)
469 {
470 log_error("Reload conf failed\n");
471 }
472
473 if (load_menu(&bbs_menu_new, CONF_MENU) < 0)
474 {
475 unload_menu(&bbs_menu_new);
476 log_error("Reload menu failed\n");
477 }
478 else
479 {
480 unload_menu(&bbs_menu);
481 memcpy(&bbs_menu, &bbs_menu_new, sizeof(bbs_menu_new));
482 log_common("Reload menu successfully\n");
483 }
484
485 for (int i = 0; i < data_files_load_startup_count; i++)
486 {
487 if (load_file(data_files_load_startup[i]) < 0)
488 {
489 log_error("load_file_mmap(%s) error\n", data_files_load_startup[i]);
490 }
491 }
492 log_common("Reload data files successfully\n");
493
494 // Load section config and gen_ex
495 if (load_section_config_from_db(1) < 0)
496 {
497 log_error("load_section_config_from_db(1) error\n");
498 }
499 else
500 {
501 log_common("Reload section config and gen_ex successfully\n");
502 }
503
504 sd_notify(0, "READY=1");
505 }
506
507 nfds = epoll_wait(epollfd, events, MAX_EVENTS, 100); // 0.1 second
508
509 if (nfds < 0)
510 {
511 if (errno != EINTR)
512 {
513 log_error("epoll_wait() error (%d)\n", errno);
514 break;
515 }
516 continue;
517 }
518
519 // Stop accept new connection on exit
520 if (SYS_server_exit)
521 {
522 continue;
523 }
524
525 for (int i = 0; i < nfds; i++)
526 {
527 if (events[i].data.fd == socket_server[0] || events[i].data.fd == socket_server[1])
528 {
529 SSH_v2 = (events[i].data.fd == socket_server[1] ? 1 : 0);
530
531 while (!SYS_server_exit) // Accept all incoming connections until error
532 {
533 addrlen = sizeof(sin);
534 socket_client = accept(socket_server[SSH_v2], (struct sockaddr *)&sin, &addrlen);
535 if (socket_client < 0)
536 {
537 if (errno == EAGAIN || errno == EWOULDBLOCK)
538 {
539 break;
540 }
541 else if (errno == EINTR)
542 {
543 continue;
544 }
545 else
546 {
547 log_error("accept(socket_server) error (%d)\n", errno);
548 break;
549 }
550 }
551
552 strncpy(hostaddr_client, inet_ntoa(sin.sin_addr), sizeof(hostaddr_client) - 1);
553 hostaddr_client[sizeof(hostaddr_client) - 1] = '\0';
554
555 port_client = ntohs(sin.sin_port);
556
557 log_common("Accept %s connection from %s:%d\n", (SSH_v2 ? "SSH" : "telnet"), hostaddr_client, port_client);
558
559 if (SYS_child_process_count - 1 < BBS_max_client)
560 {
561 j = 0;
562 for (i = 0; i < BBS_max_client; i++)
563 {
564 if (process_sockaddr_pool[i].pid != 0 && process_sockaddr_pool[i].s_addr == sin.sin_addr.s_addr)
565 {
566 j++;
567 if (j >= BBS_max_client_per_ip)
568 {
569 log_common("Too many client connections (%d) from %s\n", j, hostaddr_client);
570 break;
571 }
572 }
573 }
574
575 if (j < BBS_max_client_per_ip)
576 {
577 if ((pid = fork_server()) < 0)
578 {
579 log_error("fork_server() error\n");
580 }
581 else if (pid > 0)
582 {
583 i = 0;
584 for (; i < BBS_max_client; i++)
585 {
586 if (process_sockaddr_pool[i].pid == 0)
587 {
588 break;
589 }
590 }
591
592 if (i >= BBS_max_client)
593 {
594 log_error("Process sockaddr pool depleted\n");
595 }
596 else
597 {
598 process_sockaddr_pool[i].pid = pid;
599 process_sockaddr_pool[i].s_addr = sin.sin_addr.s_addr;
600 }
601 }
602 }
603 }
604 else
605 {
606 log_error("Rejected client connection over limit (%d)\n", SYS_child_process_count - 1);
607 }
608
609 if (close(socket_client) == -1)
610 {
611 log_error("close(socket_lient) error (%d)\n", errno);
612 }
613 }
614 }
615 }
616 }
617
618 if (close(epollfd) < 0)
619 {
620 log_error("close(epoll) error (%d)\n");
621 }
622
623 for (i = 0; i < 2; i++)
624 {
625 fcntl(socket_server[i], F_SETFL, flags[i]);
626
627 if (close(socket_server[i]) == -1)
628 {
629 log_error("Close server socket failed\n");
630 }
631 }
632
633 ssh_bind_free(sshbind);
634 ssh_finalize();
635
636 return 0;
637 }

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