drop_privileges_or_die(): Check return value of setuid().
[paraslash.git] / command.c
1 /*
2 * Copyright (C) 1997-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file command.c Client authentication and server commands. */
8
9 #include <signal.h>
10 #include <sys/time.h>
11 #include <sys/types.h>
12 #include <dirent.h>
13 #include <openssl/rc4.h>
14
15 #include "para.h"
16 #include "error.h"
17 #include "server.cmdline.h"
18 #include "string.h"
19 #include "afh.h"
20 #include "afs.h"
21 #include "server.h"
22 #include "vss.h"
23 #include "list.h"
24 #include "send.h"
25 #include "rc4.h"
26 #include "net.h"
27 #include "daemon.h"
28 #include "fd.h"
29 #include "ipc.h"
30 #include "user_list.h"
31 #include "server_command_list.h"
32 #include "afs_command_list.h"
33 #include "sched.h"
34 #include "signal.h"
35
36 /** Commands including options must be shorter than this. */
37 #define MAX_COMMAND_LEN 32768
38
39 static RC4_KEY rc4_recv_key;
40 static RC4_KEY rc4_send_key;
41 static unsigned char rc4_buf[2 * RC4_KEY_LEN];
42
43 extern int mmd_mutex;
44 extern struct misc_meta_data *mmd;
45 extern struct sender senders[];
46
47 static void dummy(__a_unused int s)
48 {
49 }
50
51 static void mmd_dup(struct misc_meta_data *new_mmd)
52 {
53 mutex_lock(mmd_mutex);
54 *new_mmd = *mmd;
55 mutex_unlock(mmd_mutex);
56 }
57
58 /*
59 * Compute human readable string containing vss status for given integer value.
60 *
61 * We don't want to use vss_playing() and friends here because we take a
62 * snapshot of the mmd struct and use the copy for computing the state of the
63 * vss. If the real data were used, we would take the mmd lock for a rather
64 * long time or risk to get an inconsistent view.
65 */
66 static char *vss_status_tohuman(unsigned int flags)
67 {
68 if (flags & VSS_PLAYING)
69 return para_strdup("playing");
70 if (flags & VSS_NEXT)
71 return para_strdup("stopped");
72 return para_strdup("paused");
73 }
74
75 /*
76 * return human readable permission string. Never returns NULL.
77 */
78 static char *cmd_perms_itohuman(unsigned int perms)
79 {
80 char *msg = para_malloc(5 * sizeof(char));
81
82 msg[0] = perms & AFS_READ? 'a' : '-';
83 msg[1] = perms & AFS_WRITE? 'A' : '-';
84 msg[2] = perms & VSS_READ? 'v' : '-';
85 msg[3] = perms & VSS_WRITE? 'V' : '-';
86 msg[4] = '\0';
87 return msg;
88 }
89
90 /*
91 * Never returns NULL.
92 */
93 static char *vss_get_status_flags(unsigned int flags)
94 {
95 char *msg = para_malloc(5 * sizeof(char));
96
97 msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
98 msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
99 msg[2] = (flags & VSS_NEXT)? 'N' : '_';
100 msg[3] = (flags & VSS_REPOS)? 'R' : '_';
101 msg[4] = '\0';
102 return msg;
103 }
104
105 static char *get_status(struct misc_meta_data *nmmd)
106 {
107 char *ret, mtime[30] = "";
108 char *status, *flags; /* vss status info */
109 char *ut = uptime_str();
110 long offset = (nmmd->offset + 500) / 1000;
111 struct timeval current_time;
112 struct tm mtime_tm;
113
114 /* report real status */
115 status = vss_status_tohuman(nmmd->vss_status_flags);
116 flags = vss_get_status_flags(nmmd->vss_status_flags);
117 if (nmmd->size) { /* parent currently has an audio file open */
118 localtime_r(&nmmd->mtime, &mtime_tm);
119 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
120 }
121 gettimeofday(&current_time, NULL);
122 ret = make_message(
123 "%s: %zu\n" /* file size */
124 "%s: %s\n" /* mtime */
125 "%s: %s\n" /* status */
126 "%s: %s\n" /* status flags */
127 "%s: %li\n" /* offset */
128 "%s: %s\n" /* afs mode */
129 "%s: %lu.%lu\n" /* stream start */
130 "%s: %lu.%lu\n" /* current server time */
131 "%s", /* afs status info */
132 status_item_list[SI_FILE_SIZE], nmmd->size / 1024,
133 status_item_list[SI_MTIME], mtime,
134 status_item_list[SI_STATUS], status,
135 status_item_list[SI_STATUS_FLAGS], flags,
136
137 status_item_list[SI_OFFSET], offset,
138 status_item_list[SI_AFS_MODE], mmd->afs_mode_string,
139
140 status_item_list[SI_STREAM_START],
141 (long unsigned)nmmd->stream_start.tv_sec,
142 (long unsigned)nmmd->stream_start.tv_usec,
143 status_item_list[SI_CURRENT_TIME],
144 (long unsigned)current_time.tv_sec,
145 (long unsigned)current_time.tv_usec,
146
147 nmmd->afd.verbose_ls_output
148
149 );
150 free(flags);
151 free(status);
152 free(ut);
153 return ret;
154 }
155
156 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
157 {
158 int i;
159 /* this has to match sender.h */
160 const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
161
162 scd->sender_num = -1;
163 if (argc < 2)
164 return -E_COMMAND_SYNTAX;
165 for (i = 0; senders[i].name; i++)
166 if (!strcmp(senders[i].name, argv[1]))
167 break;
168 PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
169 if (!senders[i].name)
170 return -E_COMMAND_SYNTAX;
171 scd->sender_num = i;
172 for (i = 0; subcmds[i]; i++)
173 if (!strcmp(subcmds[i], argv[2]))
174 break;
175 if (!subcmds[i])
176 return -E_COMMAND_SYNTAX;
177 scd->cmd_num = i;
178 if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
179 return -E_SENDER_CMD;
180 switch (scd->cmd_num) {
181 case SENDER_ON:
182 case SENDER_OFF:
183 if (argc != 3)
184 return -E_COMMAND_SYNTAX;
185 break;
186 case SENDER_DENY:
187 case SENDER_ALLOW:
188 if (argc != 4 || parse_cidr(argv[3], scd->host,
189 sizeof(scd->host), &scd->netmask) == NULL)
190 return -E_COMMAND_SYNTAX;
191 break;
192 case SENDER_ADD:
193 case SENDER_DELETE:
194 if (argc != 4)
195 return -E_COMMAND_SYNTAX;
196 return parse_fec_url(argv[3], scd);
197 default:
198 return -E_COMMAND_SYNTAX;
199 }
200 return 1;
201 }
202
203 int com_sender(int fd, int argc, char * const * argv)
204 {
205 int i, ret;
206 struct sender_command_data scd;
207
208 if (argc < 2) {
209 char *msg = NULL;
210 for (i = 0; senders[i].name; i++) {
211 char *tmp = make_message("%s%s\n",
212 msg? msg : "", senders[i].name);
213 free(msg);
214 msg = tmp;
215 }
216 ret = send_buffer(fd, msg);
217 free(msg);
218 return ret;
219 }
220 ret = check_sender_args(argc, argv, &scd);
221 if (ret < 0) {
222 char *msg;
223 if (scd.sender_num < 0)
224 return ret;
225 msg = senders[scd.sender_num].help();
226 ret = send_buffer(fd, msg);
227 free(msg);
228 return ret;
229 }
230 for (i = 0; i < 10; i++) {
231 mutex_lock(mmd_mutex);
232 if (mmd->sender_cmd_data.cmd_num >= 0) {
233 mutex_unlock(mmd_mutex);
234 usleep(100 * 1000);
235 continue;
236 }
237 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
238 mutex_unlock(mmd_mutex);
239 break;
240 }
241 return (i < 10)? 1 : -E_LOCK;
242 }
243
244 /* server info */
245 int com_si(int fd, int argc, __a_unused char * const * argv)
246 {
247 int i, ret;
248 char *ut;
249 char *sender_info = NULL, *sender_list = NULL;
250
251 if (argc != 1)
252 return -E_COMMAND_SYNTAX;
253 mutex_lock(mmd_mutex);
254 for (i = 0; senders[i].name; i++) {
255 char *info = senders[i].info();
256 sender_info = para_strcat(sender_info, info);
257 free(info);
258 sender_list = para_strcat(sender_list, senders[i].name);
259 sender_list = para_strcat(sender_list, " ");
260 }
261 ut = uptime_str();
262 ret = send_va_buffer(fd, "up: %s\nplayed: %u\n"
263 "server_pid: %d\n"
264 "afs_pid: %d\n"
265 "connections (active/accepted/total): %u/%u/%u\n"
266 "current loglevel: %s\n"
267 "supported audio formats: %s\n"
268 "supported senders: %s\n"
269 "%s",
270 ut, mmd->num_played,
271 (int)getppid(),
272 (int)mmd->afs_pid,
273 mmd->active_connections,
274 mmd->num_commands,
275 mmd->num_connects,
276 conf.loglevel_arg,
277 supported_audio_formats(),
278 sender_list,
279 sender_info
280 );
281 mutex_unlock(mmd_mutex);
282 free(ut);
283 free(sender_list);
284 free(sender_info);
285 return ret;
286 }
287
288 /* version */
289 int com_version(int fd, int argc, __a_unused char * const * argv)
290 {
291 if (argc != 1)
292 return -E_COMMAND_SYNTAX;
293 return send_buffer(fd, VERSION_TEXT("server")
294 "built: " BUILD_DATE "\n"
295 UNAME_RS ", " CC_VERSION "\n"
296 );
297 }
298
299 /* stat */
300 int com_stat(int fd, int argc, char * const * argv)
301 {
302 int ret, num = 0;/* status will be printed that many
303 * times. num <= 0 means: print forever
304 */
305 struct misc_meta_data tmp, *nmmd = &tmp;
306 char *s;
307
308 para_sigaction(SIGUSR1, dummy);
309
310 if (argc > 2)
311 return -E_COMMAND_SYNTAX;
312 if (argc > 1) {
313 ret = para_atoi32(argv[1], &num);
314 if (ret < 0)
315 goto out;
316 }
317 for (;;) {
318
319 mmd_dup(nmmd);
320 s = get_status(nmmd);
321 ret = send_buffer(fd, s);
322 free(s);
323 if (ret < 0)
324 goto out;
325 ret = 1;
326 if (num > 0 && !--num)
327 goto out;
328 sleep(50);
329 if (getppid() == 1)
330 return -E_SERVER_CRASH;
331 }
332 out:
333 return ret;
334 }
335
336 static int send_list_of_commands(int fd, struct server_command *cmd,
337 const char *handler)
338 {
339 int ret, i;
340
341 for (i = 1; cmd->name; cmd++, i++) {
342 char *perms = cmd_perms_itohuman(cmd->perms);
343 ret = send_va_buffer(fd, "%s\t%s\t%s\t%s\n", cmd->name,
344 handler,
345 perms,
346 cmd->description);
347 free(perms);
348 if (ret < 0)
349 return ret;
350 }
351 return 1;
352 }
353
354 /* returns string that must be freed by the caller */
355 static struct server_command *get_cmd_ptr(const char *name, char **handler)
356 {
357 struct server_command *cmd;
358
359 for (cmd = server_cmds; cmd->name; cmd++)
360 if (!strcmp(cmd->name, name)) {
361 if (handler)
362 *handler = para_strdup("server"); /* server commands */
363 return cmd;
364 }
365 /* not found, look for commands supported by afs */
366 for (cmd = afs_cmds; cmd->name; cmd++)
367 if (!strcmp(cmd->name, name)) {
368 if (handler)
369 *handler = para_strdup("afs");
370 return cmd;
371 }
372 return NULL;
373 }
374
375 /* help */
376 int com_help(int fd, int argc, char * const * argv)
377 {
378 struct server_command *cmd;
379 char *perms, *handler;
380 int ret;
381
382 if (argc < 2) {
383 /* no argument given, print list of commands */
384 if ((ret = send_list_of_commands(fd, server_cmds, "server")) < 0)
385 return ret;
386 return send_list_of_commands(fd, afs_cmds, "afs");
387 }
388 /* argument given for help */
389 cmd = get_cmd_ptr(argv[1], &handler);
390 if (!cmd) {
391 free(handler);
392 return -E_BAD_CMD;
393 }
394 perms = cmd_perms_itohuman(cmd->perms);
395 ret = send_va_buffer(fd,
396 "%s - %s\n\n"
397 "handler: %s\n"
398 "permissions: %s\n"
399 "usage: %s\n\n"
400 "%s\n",
401 argv[1],
402 cmd->description,
403 handler,
404 perms,
405 cmd->usage,
406 cmd->help
407 );
408 free(perms);
409 free(handler);
410 return ret;
411 }
412
413 /* hup */
414 int com_hup(__a_unused int fd, int argc, __a_unused char * const * argv)
415 {
416 if (argc != 1)
417 return -E_COMMAND_SYNTAX;
418 kill(getppid(), SIGHUP);
419 return 1;
420 }
421
422 /* term */
423 int com_term(__a_unused int fd, int argc, __a_unused char * const * argv)
424 {
425 if (argc != 1)
426 return -E_COMMAND_SYNTAX;
427 kill(getppid(), SIGTERM);
428 return 1;
429 }
430
431 int com_play(__a_unused int fd, int argc, __a_unused char * const * argv)
432 {
433 if (argc != 1)
434 return -E_COMMAND_SYNTAX;
435 mutex_lock(mmd_mutex);
436 mmd->new_vss_status_flags |= VSS_PLAYING;
437 mmd->new_vss_status_flags &= ~VSS_NOMORE;
438 mutex_unlock(mmd_mutex);
439 return 1;
440
441 }
442
443 /* stop */
444 int com_stop(__a_unused int fd, int argc, __a_unused char * const * argv)
445 {
446 if (argc != 1)
447 return -E_COMMAND_SYNTAX;
448 mutex_lock(mmd_mutex);
449 mmd->new_vss_status_flags &= ~VSS_PLAYING;
450 mmd->new_vss_status_flags &= ~VSS_REPOS;
451 mmd->new_vss_status_flags |= VSS_NEXT;
452 mutex_unlock(mmd_mutex);
453 return 1;
454 }
455
456 /* pause */
457 int com_pause(__a_unused int fd, int argc, __a_unused char * const * argv)
458 {
459 if (argc != 1)
460 return -E_COMMAND_SYNTAX;
461 mutex_lock(mmd_mutex);
462 if (!vss_paused() && !vss_stopped()) {
463 mmd->events++;
464 mmd->new_vss_status_flags &= ~VSS_PLAYING;
465 mmd->new_vss_status_flags &= ~VSS_NEXT;
466 }
467 mutex_unlock(mmd_mutex);
468 return 1;
469 }
470
471 /* next */
472 int com_next(__a_unused int fd, int argc, __a_unused char * const * argv)
473 {
474 if (argc != 1)
475 return -E_COMMAND_SYNTAX;
476 mutex_lock(mmd_mutex);
477 mmd->events++;
478 mmd->new_vss_status_flags |= VSS_NEXT;
479 mutex_unlock(mmd_mutex);
480 return 1;
481 }
482
483 /* nomore */
484 int com_nomore(__a_unused int fd, int argc, __a_unused char * const * argv)
485 {
486 if (argc != 1)
487 return -E_COMMAND_SYNTAX;
488 mutex_lock(mmd_mutex);
489 if (vss_playing() || vss_paused())
490 mmd->new_vss_status_flags |= VSS_NOMORE;
491 mutex_unlock(mmd_mutex);
492 return 1;
493 }
494
495 /* ff */
496 int com_ff(__a_unused int fd, int argc, char * const * argv)
497 {
498 long promille;
499 int ret, backwards = 0;
500 unsigned i;
501 char c;
502
503 if (argc != 2)
504 return -E_COMMAND_SYNTAX;
505 if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
506 return -E_COMMAND_SYNTAX;
507 if (ret > 1 && c == '-')
508 backwards = 1; /* jmp backwards */
509 mutex_lock(mmd_mutex);
510 ret = -E_NO_AUDIO_FILE;
511 if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
512 goto out;
513 promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
514 if (backwards)
515 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
516 else
517 promille += 1000 * i / mmd->afd.afhi.seconds_total;
518 if (promille < 0)
519 promille = 0;
520 if (promille > 1000) {
521 mmd->new_vss_status_flags |= VSS_NEXT;
522 goto out;
523 }
524 mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
525 mmd->new_vss_status_flags |= VSS_REPOS;
526 mmd->new_vss_status_flags &= ~VSS_NEXT;
527 mmd->events++;
528 ret = 1;
529 out:
530 mutex_unlock(mmd_mutex);
531 return ret;
532 }
533
534 /* jmp */
535 int com_jmp(__a_unused int fd, int argc, char * const * argv)
536 {
537 long unsigned int i;
538 int ret;
539
540 if (argc != 2)
541 return -E_COMMAND_SYNTAX;
542 if (sscanf(argv[1], "%lu", &i) <= 0)
543 return -E_COMMAND_SYNTAX;
544 mutex_lock(mmd_mutex);
545 ret = -E_NO_AUDIO_FILE;
546 if (!mmd->afd.afhi.chunks_total)
547 goto out;
548 if (i > 100)
549 i = 100;
550 PARA_INFO_LOG("jumping to %lu%%\n", i);
551 mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
552 PARA_INFO_LOG("sent: %lu, offset before jmp: %lu\n",
553 mmd->chunks_sent, mmd->offset);
554 mmd->new_vss_status_flags |= VSS_REPOS;
555 mmd->new_vss_status_flags &= ~VSS_NEXT;
556 ret = 1;
557 mmd->events++;
558 out:
559 mutex_unlock(mmd_mutex);
560 return ret;
561 }
562
563 /*
564 * check if perms are sufficient to exec a command having perms cmd_perms.
565 * Returns 0 if perms are sufficient, -E_PERM otherwise.
566 */
567 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
568 {
569 PARA_DEBUG_LOG("checking permissions\n");
570 return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
571 }
572
573 /*
574 * Parse first string from *cmd and lookup in table of valid commands.
575 * On error, NULL is returned.
576 */
577 static struct server_command *parse_cmd(const char *cmdstr)
578 {
579 char buf[255];
580 int n = 0;
581
582 sscanf(cmdstr, "%200s%n", buf, &n);
583 if (!n)
584 return NULL;
585 buf[n] = '\0';
586 return get_cmd_ptr(buf, NULL);
587 }
588
589 static void init_rc4_keys(void)
590 {
591 int i;
592
593 for (i = 0; i < 2 * RC4_KEY_LEN; i++)
594 rc4_buf[i] = para_random(256);
595 PARA_DEBUG_LOG("rc4 keys initialized (%u:%u)\n",
596 (unsigned char) rc4_buf[0],
597 (unsigned char) rc4_buf[RC4_KEY_LEN]);
598 RC4_set_key(&rc4_recv_key, RC4_KEY_LEN, rc4_buf);
599 RC4_set_key(&rc4_send_key, RC4_KEY_LEN, rc4_buf + RC4_KEY_LEN);
600 }
601
602 static void rc4_recv(unsigned long len, const unsigned char *indata,
603 unsigned char *outdata, __a_unused void *private_data)
604 {
605 RC4(&rc4_recv_key, len, indata, outdata);
606 }
607
608 static void rc4_send(unsigned long len, const unsigned char *indata,
609 unsigned char *outdata, __a_unused void *private_data)
610 {
611 RC4(&rc4_send_key, len, indata, outdata);
612 }
613
614 static int read_command(int fd, char **result)
615 {
616 int ret;
617 char buf[4096];
618 char *command = NULL;
619
620 for (;;) {
621 size_t numbytes;
622 char *p;
623
624 ret = recv_buffer(fd, buf, sizeof(buf));
625 if (ret < 0)
626 goto out;
627 if (!ret)
628 break;
629 numbytes = ret;
630 ret = -E_COMMAND_SYNTAX;
631 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
632 goto out;
633 command = para_strcat(command, buf);
634 p = strstr(command, EOC_MSG);
635 if (p) {
636 *p = '\0';
637 break;
638 }
639 }
640 ret = command? 1 : -E_COMMAND_SYNTAX;
641 out:
642 if (ret < 0)
643 free(command);
644 else
645 *result = command;
646 return ret;
647
648 }
649
650 static void reset_signals(void)
651 {
652 para_sigaction(SIGCHLD, SIG_IGN);
653 para_sigaction(SIGINT, SIG_DFL);
654 para_sigaction(SIGTERM, SIG_DFL);
655 para_sigaction(SIGHUP, SIG_DFL);
656 }
657
658 /**
659 * Perform user authentication and execute a command.
660 *
661 * \param fd The file descriptor to send output to.
662 * \param peername Identifies the connecting peer.
663 *
664 * Whenever para_server accepts an incoming tcp connection on
665 * the port it listens on, it forks and the resulting child
666 * calls this function.
667 *
668 * An RSA-based challenge/response is used to authenticate
669 * the peer. It that authentication succeeds, a random RC4
670 * session key is generated and sent back to the peer,
671 * encrypted with its RSA public key. From this point on,
672 * all transfers are crypted with this session key.
673 *
674 * Next it is checked if the peer supplied a valid server command or a command
675 * for the audio file selector. If yes, and if the user has sufficient
676 * permissions to execute that command, the function calls the corresponding
677 * command handler which does argument checking and further processing.
678 *
679 * In order to cope with a DOS attacks, a timeout is set up
680 * which terminates the function if the connection was not
681 * authenticated when the timeout expires.
682 *
683 * \sa alarm(2), rc4(3), crypt.c, crypt.h
684 */
685 __noreturn void handle_connect(int fd, const char *peername)
686 {
687 int ret, argc, use_rc4 = 0;
688 char buf[4096];
689 unsigned char crypt_buf[MAXLINE];
690 struct user *u;
691 struct server_command *cmd = NULL;
692 long unsigned challenge_nr, chall_response;
693 char **argv = NULL;
694 char *p, *command = NULL;
695 size_t numbytes;
696
697 reset_signals();
698 /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
699 ret = mark_fd_blocking(fd);
700 if (ret < 0)
701 goto err_out;
702 challenge_nr = random();
703 /* send Welcome message */
704 ret = send_va_buffer(fd, "This is para_server, version "
705 PACKAGE_VERSION ".\n" );
706 if (ret < 0)
707 goto err_out;
708 /* recv auth request line */
709 ret = recv_buffer(fd, buf, sizeof(buf));
710 if (ret < 0)
711 goto err_out;
712 if (ret <= 6) {
713 ret = -E_AUTH;
714 goto err_out;
715 }
716 numbytes = ret;
717 ret = -E_AUTH;
718 if (strncmp(buf, "auth ", 5))
719 goto err_out;
720
721 if (numbytes < 9 || strncmp(buf, "auth rc4 ", 9))
722 p = buf + 5; /* client version < 0.2.6 */
723 else {
724 p = buf + 9; /* client version >= 0.2.6 */
725 use_rc4 = 1;
726 }
727 PARA_DEBUG_LOG("received %s request for user %s\n",
728 use_rc4? "rc4" : "auth", p);
729 ret = -E_BAD_USER;
730 u = lookup_user(p);
731 if (!u)
732 goto err_out;
733 ret = para_encrypt_challenge(u->rsa, challenge_nr, crypt_buf);
734 if (ret <= 0)
735 goto err_out;
736 numbytes = ret;
737 PARA_DEBUG_LOG("sending %zu byte challenge\n", numbytes);
738 /* We can't use send_buffer here since buf may contain null bytes */
739 ret = send_bin_buffer(fd,(char *) crypt_buf, numbytes);
740 if (ret < 0)
741 goto net_err;
742 /* recv decrypted number */
743 ret = recv_buffer(fd, buf, sizeof(buf));
744 if (ret < 0)
745 goto net_err;
746 numbytes = ret;
747 ret = -E_AUTH;
748 if (!numbytes)
749 goto net_err;
750 if (sscanf(buf, CHALLENGE_RESPONSE_MSG "%lu", &chall_response) < 1
751 || chall_response != challenge_nr)
752 goto err_out;
753 /* auth successful, send 'Proceed' message */
754 PARA_INFO_LOG("good auth for %s (%lu)\n", u->name, challenge_nr);
755 sprintf(buf, "%s", PROCEED_MSG);
756 if (use_rc4) {
757 init_rc4_keys();
758 ret = para_encrypt_buffer(u->rsa, rc4_buf, 2 * RC4_KEY_LEN,
759 (unsigned char *)buf + PROCEED_MSG_LEN + 1);
760 if (ret <= 0)
761 goto err_out;
762 numbytes = ret + strlen(PROCEED_MSG) + 1;
763 } else
764 numbytes = strlen(buf);
765 ret = send_bin_buffer(fd, buf, numbytes);
766 if (ret < 0)
767 goto net_err;
768 if (use_rc4)
769 enable_crypt(fd, rc4_recv, rc4_send, NULL);
770 ret = read_command(fd, &command);
771 if (ret == -E_COMMAND_SYNTAX)
772 goto err_out;
773 if (ret < 0)
774 goto net_err;
775 ret = -E_BAD_CMD;
776 cmd = parse_cmd(command);
777 if (!cmd)
778 goto err_out;
779 /* valid command, check permissions */
780 ret = check_perms(u->perms, cmd);
781 if (ret < 0)
782 goto err_out;
783 /* valid command and sufficient perms */
784 alarm(0);
785 argc = split_args(command, &argv, "\n");
786 PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
787 peername);
788 ret = cmd->handler(fd, argc, argv);
789 mutex_lock(mmd_mutex);
790 mmd->num_commands++;
791 mutex_unlock(mmd_mutex);
792 if (ret >= 0)
793 goto out;
794 err_out:
795 send_va_buffer(fd, "%s\n", para_strerror(-ret));
796 net_err:
797 PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
798 out:
799 free(command);
800 free(argv);
801 mutex_lock(mmd_mutex);
802 if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
803 mmd->events++;
804 mmd->active_connections--;
805 mutex_unlock(mmd_mutex);
806 exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
807 }