First draft of the libosl patch series.
[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 && argc != 5)
189 return -E_COMMAND_SYNTAX;
190 if (!is_valid_ipv4_address(argv[3]))
191 return -E_COMMAND_SYNTAX;
192 scd->netmask = 32;
193 if (argc == 5) {
194 scd->netmask = atoi(argv[4]);
195 if (scd->netmask < 0 || scd->netmask > 32)
196 return -E_COMMAND_SYNTAX;
197 }
198 strncpy(scd->host, argv[3], sizeof(scd->host));
199 break;
200 case SENDER_ADD:
201 case SENDER_DELETE:
202 if (argc != 4)
203 return -E_COMMAND_SYNTAX;
204 return parse_fec_url(argv[3], scd);
205 default:
206 return -E_COMMAND_SYNTAX;
207 }
208 return 1;
209 }
210
211 int com_sender(int fd, int argc, char * const * argv)
212 {
213 int i, ret;
214 struct sender_command_data scd;
215
216 if (argc < 2) {
217 char *msg = NULL;
218 for (i = 0; senders[i].name; i++) {
219 char *tmp = make_message("%s%s\n",
220 msg? msg : "", senders[i].name);
221 free(msg);
222 msg = tmp;
223 }
224 ret = send_buffer(fd, msg);
225 free(msg);
226 return ret;
227 }
228 ret = check_sender_args(argc, argv, &scd);
229 if (ret < 0) {
230 char *msg;
231 if (scd.sender_num < 0)
232 return ret;
233 msg = senders[scd.sender_num].help();
234 ret = send_buffer(fd, msg);
235 free(msg);
236 return ret;
237 }
238 for (i = 0; i < 10; i++) {
239 mutex_lock(mmd_mutex);
240 if (mmd->sender_cmd_data.cmd_num >= 0) {
241 mutex_unlock(mmd_mutex);
242 usleep(100 * 1000);
243 continue;
244 }
245 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
246 mutex_unlock(mmd_mutex);
247 break;
248 }
249 return (i < 10)? 1 : -E_LOCK;
250 }
251
252 /* server info */
253 int com_si(int fd, int argc, __a_unused char * const * argv)
254 {
255 int i, ret;
256 char *ut;
257 char *sender_info = NULL, *sender_list = NULL;
258
259 if (argc != 1)
260 return -E_COMMAND_SYNTAX;
261 mutex_lock(mmd_mutex);
262 for (i = 0; senders[i].name; i++) {
263 char *info = senders[i].info();
264 sender_info = para_strcat(sender_info, info);
265 free(info);
266 sender_list = para_strcat(sender_list, senders[i].name);
267 sender_list = para_strcat(sender_list, " ");
268 }
269 ut = uptime_str();
270 ret = send_va_buffer(fd, "up: %s\nplayed: %u\n"
271 "server_pid: %d\n"
272 "afs_pid: %d\n"
273 "connections (active/accepted/total): %u/%u/%u\n"
274 "current loglevel: %s\n"
275 "supported audio formats: %s\n"
276 "supported senders: %s\n"
277 "%s",
278 ut, mmd->num_played,
279 (int)getppid(),
280 (int)mmd->afs_pid,
281 mmd->active_connections,
282 mmd->num_commands,
283 mmd->num_connects,
284 conf.loglevel_arg,
285 supported_audio_formats(),
286 sender_list,
287 sender_info
288 );
289 mutex_unlock(mmd_mutex);
290 free(ut);
291 free(sender_list);
292 free(sender_info);
293 return ret;
294 }
295
296 /* version */
297 int com_version(int fd, int argc, __a_unused char * const * argv)
298 {
299 if (argc != 1)
300 return -E_COMMAND_SYNTAX;
301 return send_buffer(fd, VERSION_TEXT("server")
302 "built: " BUILD_DATE "\n"
303 UNAME_RS ", " CC_VERSION "\n"
304 );
305 }
306
307 /* stat */
308 int com_stat(int fd, int argc, char * const * argv)
309 {
310 int ret, num = 0;/* status will be printed that many
311 * times. num <= 0 means: print forever
312 */
313 struct misc_meta_data tmp, *nmmd = &tmp;
314 char *s;
315
316 para_sigaction(SIGUSR1, dummy);
317
318 if (argc > 1)
319 num = atoi(argv[1]);
320 for (;;) {
321
322 mmd_dup(nmmd);
323 s = get_status(nmmd);
324 ret = send_buffer(fd, s);
325 free(s);
326 if (ret < 0)
327 goto out;
328 ret = 1;
329 if (num > 0 && !--num)
330 goto out;
331 sleep(50);
332 if (getppid() == 1)
333 return -E_SERVER_CRASH;
334 }
335 out:
336 return ret;
337 }
338
339 static int send_list_of_commands(int fd, struct server_command *cmd,
340 const char *handler)
341 {
342 int ret, i;
343
344 for (i = 1; cmd->name; cmd++, i++) {
345 char *perms = cmd_perms_itohuman(cmd->perms);
346 ret = send_va_buffer(fd, "%s\t%s\t%s\t%s\n", cmd->name,
347 handler,
348 perms,
349 cmd->description);
350 free(perms);
351 if (ret < 0)
352 return ret;
353 }
354 return 1;
355 }
356
357 /* returns string that must be freed by the caller */
358 static struct server_command *get_cmd_ptr(const char *name, char **handler)
359 {
360 struct server_command *cmd;
361
362 for (cmd = server_cmds; cmd->name; cmd++)
363 if (!strcmp(cmd->name, name)) {
364 if (handler)
365 *handler = para_strdup("server"); /* server commands */
366 return cmd;
367 }
368 /* not found, look for commands supported by afs */
369 for (cmd = afs_cmds; cmd->name; cmd++)
370 if (!strcmp(cmd->name, name)) {
371 if (handler)
372 *handler = para_strdup("afs");
373 return cmd;
374 }
375 return NULL;
376 }
377
378 /* help */
379 int com_help(int fd, int argc, char * const * argv)
380 {
381 struct server_command *cmd;
382 char *perms, *handler;
383 int ret;
384
385 if (argc < 2) {
386 /* no argument given, print list of commands */
387 if ((ret = send_list_of_commands(fd, server_cmds, "server")) < 0)
388 return ret;
389 return send_list_of_commands(fd, afs_cmds, "afs");
390 }
391 /* argument given for help */
392 cmd = get_cmd_ptr(argv[1], &handler);
393 if (!cmd) {
394 free(handler);
395 return -E_BAD_CMD;
396 }
397 perms = cmd_perms_itohuman(cmd->perms);
398 ret = send_va_buffer(fd,
399 "%s - %s\n\n"
400 "handler: %s\n"
401 "permissions: %s\n"
402 "usage: %s\n\n"
403 "%s\n",
404 argv[1],
405 cmd->description,
406 handler,
407 perms,
408 cmd->usage,
409 cmd->help
410 );
411 free(perms);
412 free(handler);
413 return ret;
414 }
415
416 /* hup */
417 int com_hup(__a_unused int fd, int argc, __a_unused char * const * argv)
418 {
419 if (argc != 1)
420 return -E_COMMAND_SYNTAX;
421 kill(getppid(), SIGHUP);
422 return 1;
423 }
424
425 /* term */
426 int com_term(__a_unused int fd, int argc, __a_unused char * const * argv)
427 {
428 if (argc != 1)
429 return -E_COMMAND_SYNTAX;
430 kill(getppid(), SIGTERM);
431 return 1;
432 }
433
434 int com_play(__a_unused int fd, int argc, __a_unused char * const * argv)
435 {
436 if (argc != 1)
437 return -E_COMMAND_SYNTAX;
438 mutex_lock(mmd_mutex);
439 mmd->new_vss_status_flags |= VSS_PLAYING;
440 mmd->new_vss_status_flags &= ~VSS_NOMORE;
441 mutex_unlock(mmd_mutex);
442 return 1;
443
444 }
445
446 /* stop */
447 int com_stop(__a_unused int fd, int argc, __a_unused char * const * argv)
448 {
449 if (argc != 1)
450 return -E_COMMAND_SYNTAX;
451 mutex_lock(mmd_mutex);
452 mmd->new_vss_status_flags &= ~VSS_PLAYING;
453 mmd->new_vss_status_flags &= ~VSS_REPOS;
454 mmd->new_vss_status_flags |= VSS_NEXT;
455 mutex_unlock(mmd_mutex);
456 return 1;
457 }
458
459 /* pause */
460 int com_pause(__a_unused int fd, int argc, __a_unused char * const * argv)
461 {
462 if (argc != 1)
463 return -E_COMMAND_SYNTAX;
464 mutex_lock(mmd_mutex);
465 if (!vss_paused() && !vss_stopped()) {
466 mmd->events++;
467 mmd->new_vss_status_flags &= ~VSS_PLAYING;
468 mmd->new_vss_status_flags &= ~VSS_NEXT;
469 }
470 mutex_unlock(mmd_mutex);
471 return 1;
472 }
473
474 /* next */
475 int com_next(__a_unused int fd, int argc, __a_unused char * const * argv)
476 {
477 if (argc != 1)
478 return -E_COMMAND_SYNTAX;
479 mutex_lock(mmd_mutex);
480 mmd->events++;
481 mmd->new_vss_status_flags |= VSS_NEXT;
482 mutex_unlock(mmd_mutex);
483 return 1;
484 }
485
486 /* nomore */
487 int com_nomore(__a_unused int fd, int argc, __a_unused char * const * argv)
488 {
489 if (argc != 1)
490 return -E_COMMAND_SYNTAX;
491 mutex_lock(mmd_mutex);
492 if (vss_playing() || vss_paused())
493 mmd->new_vss_status_flags |= VSS_NOMORE;
494 mutex_unlock(mmd_mutex);
495 return 1;
496 }
497
498 /* ff */
499 int com_ff(__a_unused int fd, int argc, char * const * argv)
500 {
501 long promille;
502 int ret, backwards = 0;
503 unsigned i;
504 char c;
505
506 if (argc != 2)
507 return -E_COMMAND_SYNTAX;
508 if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
509 return -E_COMMAND_SYNTAX;
510 if (ret > 1 && c == '-')
511 backwards = 1; /* jmp backwards */
512 mutex_lock(mmd_mutex);
513 ret = -E_NO_AUDIO_FILE;
514 if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
515 goto out;
516 promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
517 if (backwards)
518 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
519 else
520 promille += 1000 * i / mmd->afd.afhi.seconds_total;
521 if (promille < 0)
522 promille = 0;
523 if (promille > 1000) {
524 mmd->new_vss_status_flags |= VSS_NEXT;
525 goto out;
526 }
527 mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
528 mmd->new_vss_status_flags |= VSS_REPOS;
529 mmd->new_vss_status_flags &= ~VSS_NEXT;
530 mmd->events++;
531 ret = 1;
532 out:
533 mutex_unlock(mmd_mutex);
534 return ret;
535 }
536
537 /* jmp */
538 int com_jmp(__a_unused int fd, int argc, char * const * argv)
539 {
540 long unsigned int i;
541 int ret;
542
543 if (argc != 2)
544 return -E_COMMAND_SYNTAX;
545 if (sscanf(argv[1], "%lu", &i) <= 0)
546 return -E_COMMAND_SYNTAX;
547 mutex_lock(mmd_mutex);
548 ret = -E_NO_AUDIO_FILE;
549 if (!mmd->afd.afhi.chunks_total)
550 goto out;
551 if (i > 100)
552 i = 100;
553 PARA_INFO_LOG("jumping to %lu%%\n", i);
554 mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
555 PARA_INFO_LOG("sent: %lu, offset before jmp: %lu\n",
556 mmd->chunks_sent, mmd->offset);
557 mmd->new_vss_status_flags |= VSS_REPOS;
558 mmd->new_vss_status_flags &= ~VSS_NEXT;
559 ret = 1;
560 mmd->events++;
561 out:
562 mutex_unlock(mmd_mutex);
563 return ret;
564 }
565
566 /*
567 * check if perms are sufficient to exec a command having perms cmd_perms.
568 * Returns 0 if perms are sufficient, -E_PERM otherwise.
569 */
570 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
571 {
572 PARA_DEBUG_LOG("checking permissions\n");
573 return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
574 }
575
576 /*
577 * Parse first string from *cmd and lookup in table of valid commands.
578 * On error, NULL is returned.
579 */
580 static struct server_command *parse_cmd(const char *cmdstr)
581 {
582 char buf[255];
583 int n = 0;
584
585 sscanf(cmdstr, "%200s%n", buf, &n);
586 if (!n)
587 return NULL;
588 buf[n] = '\0';
589 return get_cmd_ptr(buf, NULL);
590 }
591
592 static void init_rc4_keys(void)
593 {
594 int i;
595
596 for (i = 0; i < 2 * RC4_KEY_LEN; i++)
597 rc4_buf[i] = para_random(256);
598 PARA_DEBUG_LOG("rc4 keys initialized (%u:%u)\n",
599 (unsigned char) rc4_buf[0],
600 (unsigned char) rc4_buf[RC4_KEY_LEN]);
601 RC4_set_key(&rc4_recv_key, RC4_KEY_LEN, rc4_buf);
602 RC4_set_key(&rc4_send_key, RC4_KEY_LEN, rc4_buf + RC4_KEY_LEN);
603 }
604
605 static void rc4_recv(unsigned long len, const unsigned char *indata,
606 unsigned char *outdata, __a_unused void *private_data)
607 {
608 RC4(&rc4_recv_key, len, indata, outdata);
609 }
610
611 static void rc4_send(unsigned long len, const unsigned char *indata,
612 unsigned char *outdata, __a_unused void *private_data)
613 {
614 RC4(&rc4_send_key, len, indata, outdata);
615 }
616
617 static int read_command(int fd, char **result)
618 {
619 int ret;
620 char buf[4096];
621 char *command = NULL;
622
623 for (;;) {
624 size_t numbytes;
625 char *p;
626
627 ret = recv_buffer(fd, buf, sizeof(buf));
628 if (ret < 0)
629 goto out;
630 if (!ret)
631 break;
632 numbytes = ret;
633 ret = -E_COMMAND_SYNTAX;
634 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
635 goto out;
636 command = para_strcat(command, buf);
637 p = strstr(command, EOC_MSG);
638 if (p) {
639 *p = '\0';
640 break;
641 }
642 }
643 ret = command? 1 : -E_COMMAND_SYNTAX;
644 out:
645 if (ret < 0)
646 free(command);
647 else
648 *result = command;
649 return ret;
650
651 }
652
653 static void reset_signals(void)
654 {
655 para_sigaction(SIGCHLD, SIG_IGN);
656 para_sigaction(SIGINT, SIG_DFL);
657 para_sigaction(SIGTERM, SIG_DFL);
658 para_sigaction(SIGHUP, SIG_DFL);
659 }
660
661 /**
662 * Perform user authentication and execute a command.
663 *
664 * \param fd The file descriptor to send output to.
665 * \param peername Identifies the connecting peer.
666 *
667 * Whenever para_server accepts an incoming tcp connection on
668 * the port it listens on, it forks and the resulting child
669 * calls this function.
670 *
671 * An RSA-based challenge/response is used to authenticate
672 * the peer. It that authentication succeeds, a random RC4
673 * session key is generated and sent back to the peer,
674 * encrypted with its RSA public key. From this point on,
675 * all transfers are crypted with this session key.
676 *
677 * Next it is checked if the peer supplied a valid server command or a command
678 * for the audio file selector. If yes, and if the user has sufficient
679 * permissions to execute that command, the function calls the corresponding
680 * command handler which does argument checking and further processing.
681 *
682 * In order to cope with a DOS attacks, a timeout is set up
683 * which terminates the function if the connection was not
684 * authenticated when the timeout expires.
685 *
686 * \sa alarm(2), rc4(3), crypt.c, crypt.h
687 */
688 __noreturn void handle_connect(int fd, const char *peername)
689 {
690 int ret, argc, use_rc4 = 0;
691 char buf[4096];
692 unsigned char crypt_buf[MAXLINE];
693 struct user *u;
694 struct server_command *cmd = NULL;
695 long unsigned challenge_nr, chall_response;
696 char **argv = NULL;
697 char *p, *command = NULL;
698 size_t numbytes;
699
700 reset_signals();
701 /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
702 ret = mark_fd_blocking(fd);
703 if (ret < 0)
704 goto err_out;
705 challenge_nr = random();
706 /* send Welcome message */
707 ret = send_va_buffer(fd, "This is para_server, version "
708 PACKAGE_VERSION ".\n" );
709 if (ret < 0)
710 goto err_out;
711 /* recv auth request line */
712 ret = recv_buffer(fd, buf, sizeof(buf));
713 if (ret < 0)
714 goto err_out;
715 if (ret <= 6) {
716 ret = -E_AUTH;
717 goto err_out;
718 }
719 numbytes = ret;
720 ret = -E_AUTH;
721 if (strncmp(buf, "auth ", 5))
722 goto err_out;
723
724 if (numbytes < 9 || strncmp(buf, "auth rc4 ", 9))
725 p = buf + 5; /* client version < 0.2.6 */
726 else {
727 p = buf + 9; /* client version >= 0.2.6 */
728 use_rc4 = 1;
729 }
730 PARA_DEBUG_LOG("received %s request for user %s\n",
731 use_rc4? "rc4" : "auth", p);
732 ret = -E_BAD_USER;
733 u = lookup_user(p);
734 if (!u)
735 goto err_out;
736 ret = para_encrypt_challenge(u->rsa, challenge_nr, crypt_buf);
737 if (ret <= 0)
738 goto err_out;
739 numbytes = ret;
740 PARA_DEBUG_LOG("sending %zu byte challenge\n", numbytes);
741 /* We can't use send_buffer here since buf may contain null bytes */
742 ret = send_bin_buffer(fd,(char *) crypt_buf, numbytes);
743 if (ret < 0)
744 goto net_err;
745 /* recv decrypted number */
746 ret = recv_buffer(fd, buf, sizeof(buf));
747 if (ret < 0)
748 goto net_err;
749 numbytes = ret;
750 ret = -E_AUTH;
751 if (!numbytes)
752 goto net_err;
753 if (sscanf(buf, CHALLENGE_RESPONSE_MSG "%lu", &chall_response) < 1
754 || chall_response != challenge_nr)
755 goto err_out;
756 /* auth successful, send 'Proceed' message */
757 PARA_INFO_LOG("good auth for %s (%lu)\n", u->name, challenge_nr);
758 sprintf(buf, "%s", PROCEED_MSG);
759 if (use_rc4) {
760 init_rc4_keys();
761 ret = para_encrypt_buffer(u->rsa, rc4_buf, 2 * RC4_KEY_LEN,
762 (unsigned char *)buf + PROCEED_MSG_LEN + 1);
763 if (ret <= 0)
764 goto err_out;
765 numbytes = ret + strlen(PROCEED_MSG) + 1;
766 } else
767 numbytes = strlen(buf);
768 ret = send_bin_buffer(fd, buf, numbytes);
769 if (ret < 0)
770 goto net_err;
771 if (use_rc4)
772 enable_crypt(fd, rc4_recv, rc4_send, NULL);
773 ret = read_command(fd, &command);
774 if (ret == -E_COMMAND_SYNTAX)
775 goto err_out;
776 if (ret < 0)
777 goto net_err;
778 ret = -E_BAD_CMD;
779 cmd = parse_cmd(command);
780 if (!cmd)
781 goto err_out;
782 /* valid command, check permissions */
783 ret = check_perms(u->perms, cmd);
784 if (ret < 0)
785 goto err_out;
786 /* valid command and sufficient perms */
787 alarm(0);
788 argc = split_args(command, &argv, "\n");
789 PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
790 peername);
791 ret = cmd->handler(fd, argc, argv);
792 mutex_lock(mmd_mutex);
793 mmd->num_commands++;
794 mutex_unlock(mmd_mutex);
795 if (ret >= 0)
796 goto out;
797 err_out:
798 send_va_buffer(fd, "%s\n", para_strerror(-ret));
799 net_err:
800 PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
801 out:
802 free(command);
803 free(argv);
804 mutex_lock(mmd_mutex);
805 if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
806 mmd->events++;
807 mmd->active_connections--;
808 mutex_unlock(mmd_mutex);
809 exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
810 }