2db2d9cccabde3f90252e90fdc987fea4444f530
[paraslash.git] / command.c
1 /*
2 * Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>
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 <netinet/in.h>
10 #include <sys/socket.h>
11 #include <regex.h>
12 #include <signal.h>
13 #include <sys/types.h>
14 #include <osl.h>
15 #include <arpa/inet.h>
16 #include <sys/un.h>
17 #include <netdb.h>
18
19 #include "para.h"
20 #include "error.h"
21 #include "crypt.h"
22 #include "sideband.h"
23 #include "command.h"
24 #include "server.cmdline.h"
25 #include "string.h"
26 #include "afh.h"
27 #include "afs.h"
28 #include "server.h"
29 #include "list.h"
30 #include "send.h"
31 #include "sched.h"
32 #include "vss.h"
33 #include "net.h"
34 #include "daemon.h"
35 #include "fd.h"
36 #include "ipc.h"
37 #include "user_list.h"
38 #include "server.command_list.h"
39 #include "afs.command_list.h"
40 #include "signal.h"
41 #include "version.h"
42
43 /* Defines one command of para_server. */
44 struct server_command {
45 /* The name of the command. */
46 const char *name;
47 /* Pointer to the function that handles the command. */
48 int (*handler)(struct command_context *);
49 /* The privileges a user must have to execute this command. */
50 unsigned int perms;
51 /* One-line description of the command. */
52 const char *description;
53 /* Summary of the command line options. */
54 const char *usage;
55 /* The long help text. */
56 const char *help;
57 };
58
59 static struct server_command afs_cmds[] = {DEFINE_AFS_CMD_ARRAY};
60 static struct server_command server_cmds[] = {DEFINE_SERVER_CMD_ARRAY};
61
62 /** Commands including options must be shorter than this. */
63 #define MAX_COMMAND_LEN 32768
64
65 extern int mmd_mutex;
66 extern struct misc_meta_data *mmd;
67 extern struct sender senders[];
68 int send_afs_status(struct command_context *cc, int parser_friendly);
69
70 static void dummy(__a_unused int s)
71 {
72 }
73
74 static void mmd_dup(struct misc_meta_data *new_mmd)
75 {
76 mutex_lock(mmd_mutex);
77 *new_mmd = *mmd;
78 mutex_unlock(mmd_mutex);
79 }
80
81 /*
82 * Compute human readable string containing vss status for given integer value.
83 *
84 * We don't want to use vss_playing() and friends here because we take a
85 * snapshot of the mmd struct and use the copy for computing the state of the
86 * vss. If the real data were used, we would take the mmd lock for a rather
87 * long time or risk to get an inconsistent view.
88 */
89 static char *vss_status_tohuman(unsigned int flags)
90 {
91 if (flags & VSS_PLAYING)
92 return para_strdup("playing");
93 if (flags & VSS_NEXT)
94 return para_strdup("stopped");
95 return para_strdup("paused");
96 }
97
98 /*
99 * return human readable permission string. Never returns NULL.
100 */
101 static char *cmd_perms_itohuman(unsigned int perms)
102 {
103 char *msg = para_malloc(5 * sizeof(char));
104
105 msg[0] = perms & AFS_READ? 'a' : '-';
106 msg[1] = perms & AFS_WRITE? 'A' : '-';
107 msg[2] = perms & VSS_READ? 'v' : '-';
108 msg[3] = perms & VSS_WRITE? 'V' : '-';
109 msg[4] = '\0';
110 return msg;
111 }
112
113 /*
114 * Never returns NULL.
115 */
116 static char *vss_get_status_flags(unsigned int flags)
117 {
118 char *msg = para_malloc(5 * sizeof(char));
119
120 msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
121 msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
122 msg[2] = (flags & VSS_NEXT)? 'N' : '_';
123 msg[3] = (flags & VSS_REPOS)? 'R' : '_';
124 msg[4] = '\0';
125 return msg;
126 }
127
128 static unsigned get_status(struct misc_meta_data *nmmd, int parser_friendly,
129 char **result)
130 {
131 char *status, *flags; /* vss status info */
132 /* nobody updates our version of "now" */
133 long offset = (nmmd->offset + 500) / 1000;
134 struct timeval current_time;
135 struct para_buffer b = {.flags = parser_friendly? PBF_SIZE_PREFIX : 0};
136
137 /* report real status */
138 status = vss_status_tohuman(nmmd->vss_status_flags);
139 flags = vss_get_status_flags(nmmd->vss_status_flags);
140 clock_get_realtime(&current_time);
141 /*
142 * The calls to WRITE_STATUS_ITEM() below never fail because
143 * b->max_size is zero (unlimited), see para_printf(). However, clang
144 * is not smart enough to prove this and complains nevertheless.
145 * Casting the return value to void silences clang.
146 */
147 (void)WRITE_STATUS_ITEM(&b, SI_STATUS, "%s\n", status);
148 (void)WRITE_STATUS_ITEM(&b, SI_STATUS_FLAGS, "%s\n", flags);
149 (void)WRITE_STATUS_ITEM(&b, SI_OFFSET, "%li\n", offset);
150 (void)WRITE_STATUS_ITEM(&b, SI_AFS_MODE, "%s\n", mmd->afs_mode_string);
151 (void)WRITE_STATUS_ITEM(&b, SI_STREAM_START, "%lu.%lu\n",
152 (long unsigned)nmmd->stream_start.tv_sec,
153 (long unsigned)nmmd->stream_start.tv_usec);
154 (void)WRITE_STATUS_ITEM(&b, SI_CURRENT_TIME, "%lu.%lu\n",
155 (long unsigned)current_time.tv_sec,
156 (long unsigned)current_time.tv_usec);
157 free(flags);
158 free(status);
159 *result = b.buf;
160 return b.offset;
161 }
162
163 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
164 {
165 int i;
166 /* this has to match sender.h */
167 const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
168
169 scd->sender_num = -1;
170 if (argc < 2)
171 return -E_COMMAND_SYNTAX;
172 for (i = 0; senders[i].name; i++)
173 if (!strcmp(senders[i].name, argv[1]))
174 break;
175 PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
176 if (!senders[i].name)
177 return -E_COMMAND_SYNTAX;
178 scd->sender_num = i;
179 for (i = 0; subcmds[i]; i++)
180 if (!strcmp(subcmds[i], argv[2]))
181 break;
182 if (!subcmds[i])
183 return -E_COMMAND_SYNTAX;
184 scd->cmd_num = i;
185 if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
186 return -E_SENDER_CMD;
187 switch (scd->cmd_num) {
188 case SENDER_ON:
189 case SENDER_OFF:
190 if (argc != 3)
191 return -E_COMMAND_SYNTAX;
192 break;
193 case SENDER_DENY:
194 case SENDER_ALLOW:
195 if (argc != 4 || parse_cidr(argv[3], scd->host,
196 sizeof(scd->host), &scd->netmask) == NULL)
197 return -E_COMMAND_SYNTAX;
198 break;
199 case SENDER_ADD:
200 case SENDER_DELETE:
201 if (argc != 4)
202 return -E_COMMAND_SYNTAX;
203 return parse_fec_url(argv[3], scd);
204 default:
205 return -E_COMMAND_SYNTAX;
206 }
207 return 1;
208 }
209
210 /**
211 * Send a sideband packet through a blocking file descriptor.
212 *
213 * \param scc fd and crypto keys.
214 * \param buf The buffer to send.
215 * \param numbytes The size of \a buf.
216 * \param band The sideband designator of this packet.
217 * \param dont_free If true, never deallocate \a buf.
218 *
219 * The nonblock flag must be disabled for the file descriptor given by \a scc.
220 *
221 * Stream cipher encryption is automatically activated if necessary via the
222 * sideband transformation, depending on the value of \a band.
223 *
224 * \return Standard.
225 *
226 * \sa \ref send_sb_va().
227 */
228 int send_sb(struct stream_cipher_context *scc, void *buf, size_t numbytes,
229 int band, bool dont_free)
230 {
231 int ret;
232 struct sb_context *sbc;
233 struct iovec iov[2];
234 sb_transformation trafo = band < SBD_PROCEED? NULL : sc_trafo;
235 struct sb_buffer sbb = SBB_INIT(band, buf, numbytes);
236
237 sbc = sb_new_send(&sbb, dont_free, trafo, scc->send);
238 do {
239 ret = sb_get_send_buffers(sbc, iov);
240 ret = xwritev(scc->fd, iov, ret);
241 if (ret < 0)
242 goto fail;
243 } while (sb_sent(sbc, ret) == false);
244 return 1;
245 fail:
246 sb_free(sbc);
247 return ret;
248 }
249
250 /**
251 * Create a variable sized buffer and send it as a sideband packet.
252 *
253 * \param scc Passed to \ref send_sb.
254 * \param band See \ref send_sb.
255 * \param fmt The format string.
256 *
257 * \return The return value of the underlying call to \ref send_sb.
258 */
259 __printf_3_4 int send_sb_va(struct stream_cipher_context *scc, int band,
260 const char *fmt, ...)
261 {
262 va_list ap;
263 char *msg;
264 int ret;
265
266 va_start(ap, fmt);
267 ret = xvasprintf(&msg, fmt, ap);
268 va_end(ap);
269 return send_sb(scc, msg, ret, band, false);
270 }
271
272 /**
273 * Send an error message to a client.
274 *
275 * \param cc Client info.
276 * \param err The (positive) error code.
277 *
278 * \return The return value of the underlying call to send_sb_va().
279 */
280 int send_strerror(struct command_context *cc, int err)
281 {
282 return send_sb_va(&cc->scc, SBD_ERROR_LOG, "%s\n", para_strerror(err));
283 }
284
285 /**
286 * Send a sideband packet through a blocking file descriptor.
287 *
288 * \param scc fd and crypto keys.
289 * \param expected_band The expected band designator.
290 * \param max_size Passed to \ref sb_new_recv().
291 * \param result Body of the sideband packet is returned here.
292 *
293 * If \a expected_band is not \p SBD_ANY, the band designator of the received
294 * sideband packet is compared to \a expected_band and a mismatch is considered
295 * an error.
296 *
297 * \return Standard.
298 */
299 int recv_sb(struct stream_cipher_context *scc,
300 enum sb_designator expected_band,
301 size_t max_size, struct iovec *result)
302 {
303 int ret;
304 struct sb_context *sbc;
305 struct iovec iov;
306 struct sb_buffer sbb;
307 sb_transformation trafo;
308
309 trafo = expected_band != SBD_ANY && expected_band < SBD_PROCEED?
310 NULL : sc_trafo;
311 sbc = sb_new_recv(max_size, trafo, scc->recv);
312 for (;;) {
313 sb_get_recv_buffer(sbc, &iov);
314 ret = recv_bin_buffer(scc->fd, iov.iov_base, iov.iov_len);
315 if (ret == 0)
316 ret = -E_EOF;
317 if (ret < 0)
318 goto fail;
319 ret = sb_received(sbc, ret, &sbb);
320 if (ret < 0)
321 goto fail;
322 if (ret > 0)
323 break;
324 }
325 ret = -E_BAD_BAND;
326 if (expected_band != SBD_ANY && sbb.band != expected_band)
327 goto fail;
328 *result = sbb.iov;
329 return 1;
330 fail:
331 sb_free(sbc);
332 return ret;
333 }
334
335 static int com_sender(struct command_context *cc)
336 {
337 int i, ret = 0;
338 char *msg = NULL;
339 struct sender_command_data scd;
340
341 if (cc->argc < 2) {
342 for (i = 0; senders[i].name; i++) {
343 char *tmp;
344 ret = xasprintf(&tmp, "%s%s\n", msg? msg : "",
345 senders[i].name);
346 free(msg);
347 msg = tmp;
348 }
349 return send_sb(&cc->scc, msg, ret, SBD_OUTPUT, false);
350 }
351 ret = check_sender_args(cc->argc, cc->argv, &scd);
352 if (ret < 0) {
353 if (scd.sender_num < 0)
354 return ret;
355 if (strcmp(cc->argv[2], "status") == 0)
356 msg = senders[scd.sender_num].status();
357 else
358 msg = senders[scd.sender_num].help();
359 return send_sb(&cc->scc, msg, strlen(msg), SBD_OUTPUT, false);
360 }
361
362 switch (scd.cmd_num) {
363 case SENDER_ADD:
364 case SENDER_DELETE:
365 assert(senders[scd.sender_num].resolve_target);
366 ret = senders[scd.sender_num].resolve_target(cc->argv[3], &scd);
367 if (ret < 0)
368 return ret;
369 }
370
371 for (i = 0; i < 10; i++) {
372 mutex_lock(mmd_mutex);
373 if (mmd->sender_cmd_data.cmd_num >= 0) {
374 /* another sender command is active, retry in 100ms */
375 struct timespec ts = {.tv_nsec = 100 * 1000 * 1000};
376 mutex_unlock(mmd_mutex);
377 nanosleep(&ts, NULL);
378 continue;
379 }
380 mmd->sender_cmd_data = scd;
381 mutex_unlock(mmd_mutex);
382 break;
383 }
384 return (i < 10)? 1 : -E_LOCK;
385 }
386
387 /* server info */
388 static int com_si(struct command_context *cc)
389 {
390 int ret;
391 char *msg, *ut;
392
393 if (cc->argc != 1)
394 return -E_COMMAND_SYNTAX;
395 mutex_lock(mmd_mutex);
396 ut = daemon_get_uptime_str(now);
397 ret = xasprintf(&msg,
398 "up: %s\nplayed: %u\n"
399 "server_pid: %d\n"
400 "afs_pid: %d\n"
401 "connections (active/accepted/total): %u/%u/%u\n"
402 "current loglevel: %s\n"
403 "supported audio formats: %s\n",
404 ut, mmd->num_played,
405 (int)getppid(),
406 (int)mmd->afs_pid,
407 mmd->active_connections,
408 mmd->num_commands,
409 mmd->num_connects,
410 conf.loglevel_arg,
411 AUDIO_FORMAT_HANDLERS
412 );
413 mutex_unlock(mmd_mutex);
414 free(ut);
415 return send_sb(&cc->scc, msg, ret, SBD_OUTPUT, false);
416 }
417
418 /* version */
419 static int com_version(struct command_context *cc)
420 {
421 char *msg;
422 size_t len;
423
424 if (cc->argc != 1)
425 return -E_COMMAND_SYNTAX;
426 len = xasprintf(&msg, "%s", version_text("server"));
427 return send_sb(&cc->scc, msg, len, SBD_OUTPUT, false);
428 }
429
430 /** These status items are cleared if no audio file is currently open. */
431 #define EMPTY_STATUS_ITEMS \
432 ITEM(PATH) \
433 ITEM(DIRECTORY) \
434 ITEM(BASENAME) \
435 ITEM(SCORE) \
436 ITEM(ATTRIBUTES_BITMAP) \
437 ITEM(ATTRIBUTES_TXT) \
438 ITEM(HASH) \
439 ITEM(IMAGE_ID) \
440 ITEM(IMAGE_NAME) \
441 ITEM(LYRICS_ID) \
442 ITEM(LYRICS_NAME) \
443 ITEM(BITRATE) \
444 ITEM(FORMAT) \
445 ITEM(FREQUENCY) \
446 ITEM(CHANNELS) \
447 ITEM(DURATION) \
448 ITEM(SECONDS_TOTAL) \
449 ITEM(NUM_PLAYED) \
450 ITEM(LAST_PLAYED) \
451 ITEM(TECHINFO) \
452 ITEM(ARTIST) \
453 ITEM(TITLE) \
454 ITEM(YEAR) \
455 ITEM(ALBUM) \
456 ITEM(COMMENT) \
457 ITEM(MTIME) \
458 ITEM(FILE_SIZE) \
459 ITEM(CHUNK_TIME) \
460 ITEM(NUM_CHUNKS) \
461 ITEM(AMPLIFICATION) \
462
463 /**
464 * Write a list of audio-file related status items with empty values.
465 *
466 * This is used by vss when currently no audio file is open.
467 */
468 static unsigned empty_status_items(int parser_friendly, char **result)
469 {
470 char *esi;
471 unsigned len;
472
473 if (parser_friendly)
474 len = xasprintf(&esi,
475 #define ITEM(x) "0004 %02x:\n"
476 EMPTY_STATUS_ITEMS
477 #undef ITEM
478 #define ITEM(x) , SI_ ## x
479 EMPTY_STATUS_ITEMS
480 #undef ITEM
481 );
482 else
483 len = xasprintf(&esi,
484 #define ITEM(x) "%s:\n"
485 EMPTY_STATUS_ITEMS
486 #undef ITEM
487 #define ITEM(x) ,status_item_list[SI_ ## x]
488 EMPTY_STATUS_ITEMS
489 #undef ITEM
490 );
491 *result = esi;
492 return len;
493 }
494 #undef EMPTY_STATUS_ITEMS
495
496 /* stat */
497 static int com_stat(struct command_context *cc)
498 {
499 int i, ret;
500 struct misc_meta_data tmp, *nmmd = &tmp;
501 char *s;
502 int32_t num = 0;
503 int parser_friendly = 0;
504
505 para_sigaction(SIGUSR1, dummy);
506
507 for (i = 1; i < cc->argc; i++) {
508 const char *arg = cc->argv[i];
509 if (arg[0] != '-')
510 break;
511 if (!strcmp(arg, "--")) {
512 i++;
513 break;
514 }
515 if (!strncmp(arg, "-n=", 3)) {
516 ret = para_atoi32(arg + 3, &num);
517 if (ret < 0)
518 return ret;
519 continue;
520 }
521 if (!strcmp(arg, "-p")) {
522 parser_friendly = 1;
523 continue;
524 }
525 return -E_COMMAND_SYNTAX;
526 }
527 if (i != cc->argc)
528 return -E_COMMAND_SYNTAX;
529 for (;;) {
530 mmd_dup(nmmd);
531 ret = get_status(nmmd, parser_friendly, &s);
532 ret = send_sb(&cc->scc, s, ret, SBD_OUTPUT, false);
533 if (ret < 0)
534 goto out;
535 if (nmmd->vss_status_flags & VSS_NEXT) {
536 char *esi;
537 ret = empty_status_items(parser_friendly, &esi);
538 ret = send_sb(&cc->scc, esi, ret, SBD_OUTPUT, false);
539 if (ret < 0)
540 goto out;
541 } else
542 send_afs_status(cc, parser_friendly);
543 ret = 1;
544 if (num > 0 && !--num)
545 goto out;
546 sleep(50);
547 ret = -E_SERVER_CRASH;
548 if (getppid() == 1)
549 goto out;
550 }
551 out:
552 return ret;
553 }
554
555 static int send_list_of_commands(struct command_context *cc, struct server_command *cmd,
556 const char *handler)
557 {
558 char *msg = NULL;
559
560 for (; cmd->name; cmd++) {
561 char *tmp, *perms = cmd_perms_itohuman(cmd->perms);
562 tmp = make_message("%s\t%s\t%s\t%s\n", cmd->name, handler,
563 perms, cmd->description);
564 free(perms);
565 msg = para_strcat(msg, tmp);
566 free(tmp);
567 }
568 assert(msg);
569 return send_sb(&cc->scc, msg, strlen(msg), SBD_OUTPUT, false);
570 }
571
572 /* returns string that must be freed by the caller */
573 static struct server_command *get_cmd_ptr(const char *name, char **handler)
574 {
575 struct server_command *cmd;
576
577 for (cmd = server_cmds; cmd->name; cmd++)
578 if (!strcmp(cmd->name, name)) {
579 if (handler)
580 *handler = para_strdup("server"); /* server commands */
581 return cmd;
582 }
583 /* not found, look for commands supported by afs */
584 for (cmd = afs_cmds; cmd->name; cmd++)
585 if (!strcmp(cmd->name, name)) {
586 if (handler)
587 *handler = para_strdup("afs");
588 return cmd;
589 }
590 return NULL;
591 }
592
593 /* help */
594 static int com_help(struct command_context *cc)
595 {
596 struct server_command *cmd;
597 char *perms, *handler, *buf;
598 int ret;
599
600 if (cc->argc < 2) {
601 /* no argument given, print list of commands */
602 if ((ret = send_list_of_commands(cc, server_cmds, "server")) < 0)
603 return ret;
604 return send_list_of_commands(cc, afs_cmds, "afs");
605 }
606 /* argument given for help */
607 cmd = get_cmd_ptr(cc->argv[1], &handler);
608 if (!cmd)
609 return -E_BAD_CMD;
610 perms = cmd_perms_itohuman(cmd->perms);
611 ret = xasprintf(&buf, "%s - %s\n\n"
612 "handler: %s\n"
613 "permissions: %s\n"
614 "usage: %s\n\n"
615 "%s\n",
616 cc->argv[1],
617 cmd->description,
618 handler,
619 perms,
620 cmd->usage,
621 cmd->help
622 );
623 free(perms);
624 free(handler);
625 return send_sb(&cc->scc, buf, ret, SBD_OUTPUT, false);
626 }
627
628 /* hup */
629 static int com_hup(struct command_context *cc)
630 {
631 if (cc->argc != 1)
632 return -E_COMMAND_SYNTAX;
633 kill(getppid(), SIGHUP);
634 return 1;
635 }
636
637 /* term */
638 static int com_term(struct command_context *cc)
639 {
640 if (cc->argc != 1)
641 return -E_COMMAND_SYNTAX;
642 kill(getppid(), SIGTERM);
643 return 1;
644 }
645
646 static int com_play(struct command_context *cc)
647 {
648 if (cc->argc != 1)
649 return -E_COMMAND_SYNTAX;
650 mutex_lock(mmd_mutex);
651 mmd->new_vss_status_flags |= VSS_PLAYING;
652 mmd->new_vss_status_flags &= ~VSS_NOMORE;
653 mutex_unlock(mmd_mutex);
654 return 1;
655 }
656
657 /* stop */
658 static int com_stop(struct command_context *cc)
659 {
660 if (cc->argc != 1)
661 return -E_COMMAND_SYNTAX;
662 mutex_lock(mmd_mutex);
663 mmd->new_vss_status_flags &= ~VSS_PLAYING;
664 mmd->new_vss_status_flags &= ~VSS_REPOS;
665 mmd->new_vss_status_flags |= VSS_NEXT;
666 mutex_unlock(mmd_mutex);
667 return 1;
668 }
669
670 /* pause */
671 static int com_pause(struct command_context *cc)
672 {
673 if (cc->argc != 1)
674 return -E_COMMAND_SYNTAX;
675 mutex_lock(mmd_mutex);
676 if (!vss_paused() && !vss_stopped()) {
677 mmd->events++;
678 mmd->new_vss_status_flags &= ~VSS_PLAYING;
679 mmd->new_vss_status_flags &= ~VSS_NEXT;
680 }
681 mutex_unlock(mmd_mutex);
682 return 1;
683 }
684
685 /* next */
686 static int com_next(struct command_context *cc)
687 {
688 if (cc->argc != 1)
689 return -E_COMMAND_SYNTAX;
690 mutex_lock(mmd_mutex);
691 mmd->events++;
692 mmd->new_vss_status_flags |= VSS_NEXT;
693 mutex_unlock(mmd_mutex);
694 return 1;
695 }
696
697 /* nomore */
698 static int com_nomore(struct command_context *cc)
699 {
700 if (cc->argc != 1)
701 return -E_COMMAND_SYNTAX;
702 mutex_lock(mmd_mutex);
703 if (vss_playing() || vss_paused())
704 mmd->new_vss_status_flags |= VSS_NOMORE;
705 mutex_unlock(mmd_mutex);
706 return 1;
707 }
708
709 /* ff */
710 static int com_ff(struct command_context *cc)
711 {
712 long promille;
713 int ret, backwards = 0;
714 unsigned i;
715 char c;
716
717 if (cc->argc != 2)
718 return -E_COMMAND_SYNTAX;
719 if (!(ret = sscanf(cc->argv[1], "%u%c", &i, &c)))
720 return -E_COMMAND_SYNTAX;
721 if (ret > 1 && c == '-')
722 backwards = 1; /* jmp backwards */
723 mutex_lock(mmd_mutex);
724 ret = -E_NO_AUDIO_FILE;
725 if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
726 goto out;
727 promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
728 if (backwards)
729 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
730 else
731 promille += 1000 * i / mmd->afd.afhi.seconds_total;
732 if (promille < 0)
733 promille = 0;
734 if (promille > 1000) {
735 mmd->new_vss_status_flags |= VSS_NEXT;
736 goto out;
737 }
738 mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
739 mmd->new_vss_status_flags |= VSS_REPOS;
740 mmd->new_vss_status_flags &= ~VSS_NEXT;
741 mmd->events++;
742 ret = 1;
743 out:
744 mutex_unlock(mmd_mutex);
745 return ret;
746 }
747
748 /* jmp */
749 static int com_jmp(struct command_context *cc)
750 {
751 long unsigned int i;
752 int ret;
753
754 if (cc->argc != 2)
755 return -E_COMMAND_SYNTAX;
756 if (sscanf(cc->argv[1], "%lu", &i) <= 0)
757 return -E_COMMAND_SYNTAX;
758 mutex_lock(mmd_mutex);
759 ret = -E_NO_AUDIO_FILE;
760 if (!mmd->afd.afhi.chunks_total)
761 goto out;
762 if (i > 100)
763 i = 100;
764 PARA_INFO_LOG("jumping to %lu%%\n", i);
765 mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50) / 100;
766 PARA_INFO_LOG("sent: %lu, offset before jmp: %lu\n",
767 mmd->chunks_sent, mmd->offset);
768 mmd->new_vss_status_flags |= VSS_REPOS;
769 mmd->new_vss_status_flags &= ~VSS_NEXT;
770 ret = 1;
771 mmd->events++;
772 out:
773 mutex_unlock(mmd_mutex);
774 return ret;
775 }
776
777 static int com_tasks(struct command_context *cc)
778 {
779 char *tl = server_get_tasks();
780 int ret = 1;
781
782 if (tl)
783 ret = send_sb(&cc->scc, tl, strlen(tl), SBD_OUTPUT, false);
784 return ret;
785 }
786
787 /*
788 * check if perms are sufficient to exec a command having perms cmd_perms.
789 * Returns 0 if perms are sufficient, -E_PERM otherwise.
790 */
791 static int check_perms(unsigned int perms, const struct server_command *cmd_ptr)
792 {
793 PARA_DEBUG_LOG("checking permissions\n");
794 return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
795 }
796
797 static void reset_signals(void)
798 {
799 para_sigaction(SIGCHLD, SIG_IGN);
800 para_sigaction(SIGINT, SIG_DFL);
801 para_sigaction(SIGTERM, SIG_DFL);
802 para_sigaction(SIGHUP, SIG_DFL);
803 }
804
805 struct connection_features {
806 bool sideband_requested;
807 bool aes_ctr128_requested;
808 };
809
810 static int parse_auth_request(char *buf, int len, struct user **u,
811 struct connection_features *cf)
812 {
813 int ret;
814 char *p, *username, **features = NULL;
815 size_t auth_rq_len = strlen(AUTH_REQUEST_MSG);
816
817 *u = NULL;
818 memset(cf, 0, sizeof(*cf));
819 if (len < auth_rq_len + 2)
820 return -E_AUTH_REQUEST;
821 if (strncmp(buf, AUTH_REQUEST_MSG, auth_rq_len) != 0)
822 return -E_AUTH_REQUEST;
823 username = buf + auth_rq_len;
824 p = strchr(username, ' ');
825 if (p) {
826 int i;
827 if (p == username)
828 return -E_AUTH_REQUEST;
829 *p = '\0';
830 p++;
831 create_argv(p, ",", &features);
832 for (i = 0; features[i]; i++) {
833 if (strcmp(features[i], "sideband") == 0)
834 cf->sideband_requested = true;
835 else if (strcmp(features[i], "aes_ctr128") == 0)
836 cf->aes_ctr128_requested = true;
837 else {
838 ret = -E_BAD_FEATURE;
839 goto out;
840 }
841 }
842 }
843 PARA_DEBUG_LOG("received auth request for user %s\n", username);
844 *u = lookup_user(username);
845 ret = 1;
846 out:
847 free_argv(features);
848 return ret;
849 }
850
851 #define HANDSHAKE_BUFSIZE 4096
852
853 static int parse_sb_command(struct command_context *cc, struct iovec *iov)
854 {
855 int ret, i;
856 char *p, *end;
857
858 ret = -E_BAD_CMD;
859 if (iov->iov_base == NULL || iov->iov_len == 0)
860 goto out;
861 p = iov->iov_base;
862 p[iov->iov_len - 1] = '\0'; /* just to be sure */
863 cc->cmd = get_cmd_ptr(p, NULL);
864 if (!cc->cmd)
865 goto out;
866 ret = check_perms(cc->u->perms, cc->cmd);
867 if (ret < 0)
868 goto out;
869 end = iov->iov_base + iov->iov_len;
870 for (i = 0; p < end; i++)
871 p += strlen(p) + 1;
872 cc->argc = i;
873 cc->argv = para_malloc((cc->argc + 1) * sizeof(char *));
874 for (i = 0, p = iov->iov_base; p < end; i++) {
875 cc->argv[i] = para_strdup(p);
876 p += strlen(p) + 1;
877 }
878 cc->argv[cc->argc] = NULL;
879 ret = cc->argc;
880 out:
881 free(iov->iov_base);
882 return ret;
883 }
884
885 /**
886 * Perform user authentication and execute a command.
887 *
888 * \param fd The file descriptor to send output to.
889 * \param peername Identifies the connecting peer.
890 *
891 * Whenever para_server accepts an incoming tcp connection on the port it
892 * listens on, it forks and the resulting child calls this function.
893 *
894 * An RSA-based challenge/response is used to authenticate the peer. It that
895 * authentication succeeds, a random session key is generated and sent back to
896 * the peer, encrypted with its RSA public key. From this point on, all
897 * transfers are crypted with this session key.
898 *
899 * Next it is checked if the peer supplied a valid server command or a command
900 * for the audio file selector. If yes, and if the user has sufficient
901 * permissions to execute that command, the function calls the corresponding
902 * command handler which does argument checking and further processing.
903 *
904 * In order to cope with a DOS attacks, a timeout is set up which terminates
905 * the function if the connection was not authenticated when the timeout
906 * expires.
907 *
908 * \sa alarm(2), crypt.c, crypt.h
909 */
910 __noreturn void handle_connect(int fd, const char *peername)
911 {
912 int ret;
913 unsigned char rand_buf[CHALLENGE_SIZE + 2 * SESSION_KEY_LEN];
914 unsigned char challenge_hash[HASH_SIZE];
915 char *command = NULL, *buf = para_malloc(HANDSHAKE_BUFSIZE) /* must be on the heap */;
916 size_t numbytes;
917 struct command_context cc_struct = {.peer = peername}, *cc = &cc_struct;
918 struct iovec iov;
919 struct connection_features cf;
920
921 cc->scc.fd = fd;
922 reset_signals();
923 /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
924 ret = mark_fd_blocking(fd);
925 if (ret < 0)
926 goto net_err;
927 /* send Welcome message */
928 ret = write_va_buffer(fd, "This is para_server, version "
929 PACKAGE_VERSION ".\n"
930 "Features: sideband,aes_ctr128\n"
931 );
932 if (ret < 0)
933 goto net_err;
934 /* recv auth request line */
935 ret = recv_buffer(fd, buf, HANDSHAKE_BUFSIZE);
936 if (ret < 0)
937 goto net_err;
938 ret = parse_auth_request(buf, ret, &cc->u, &cf);
939 if (ret < 0)
940 goto net_err;
941 if (!cf.sideband_requested) { /* sideband is mandatory */
942 PARA_ERROR_LOG("client did not request sideband\n");
943 ret = -E_BAD_FEATURE;
944 goto net_err;
945 }
946 if (cc->u) {
947 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
948 ret = pub_encrypt(cc->u->pubkey, rand_buf, sizeof(rand_buf),
949 (unsigned char *)buf);
950 if (ret < 0)
951 goto net_err;
952 numbytes = ret;
953 } else {
954 /*
955 * We don't want to reveal our user names, so we send a
956 * challenge to the client even if the user does not exist, and
957 * fail the authentication later.
958 */
959 numbytes = 256;
960 get_random_bytes_or_die((unsigned char *)buf, numbytes);
961 }
962 PARA_DEBUG_LOG("sending %u byte challenge + session key (%zu bytes)\n",
963 CHALLENGE_SIZE, numbytes);
964 ret = send_sb(&cc->scc, buf, numbytes, SBD_CHALLENGE, false);
965 buf = NULL;
966 if (ret < 0)
967 goto net_err;
968 ret = recv_sb(&cc->scc, SBD_CHALLENGE_RESPONSE,
969 HANDSHAKE_BUFSIZE, &iov);
970 if (ret < 0)
971 goto net_err;
972 buf = iov.iov_base;
973 numbytes = iov.iov_len;
974 PARA_DEBUG_LOG("received %zu bytes challenge response\n", numbytes);
975 ret = -E_BAD_USER;
976 if (!cc->u)
977 goto net_err;
978 /*
979 * The correct response is the hash of the first CHALLENGE_SIZE bytes
980 * of the random data.
981 */
982 ret = -E_BAD_AUTH;
983 if (numbytes != HASH_SIZE)
984 goto net_err;
985 hash_function((char *)rand_buf, CHALLENGE_SIZE, challenge_hash);
986 if (memcmp(challenge_hash, buf, HASH_SIZE))
987 goto net_err;
988 /* auth successful */
989 alarm(0);
990 PARA_INFO_LOG("good auth for %s\n", cc->u->name);
991 /* init stream cipher keys with the second part of the random buffer */
992 cc->scc.recv = sc_new(rand_buf + CHALLENGE_SIZE, SESSION_KEY_LEN,
993 cf.aes_ctr128_requested);
994 cc->scc.send = sc_new(rand_buf + CHALLENGE_SIZE + SESSION_KEY_LEN,
995 SESSION_KEY_LEN, cf.aes_ctr128_requested);
996 ret = send_sb(&cc->scc, NULL, 0, SBD_PROCEED, false);
997 if (ret < 0)
998 goto net_err;
999 ret = recv_sb(&cc->scc, SBD_COMMAND, MAX_COMMAND_LEN, &iov);
1000 if (ret < 0)
1001 goto net_err;
1002 ret = parse_sb_command(cc, &iov);
1003 if (ret < 0)
1004 goto err_out;
1005 cc->argc = ret;
1006 PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cc->cmd->name,
1007 cc->u->name, peername);
1008 ret = cc->cmd->handler(cc);
1009 free_argv(cc->argv);
1010 mutex_lock(mmd_mutex);
1011 mmd->num_commands++;
1012 mutex_unlock(mmd_mutex);
1013 if (ret >= 0)
1014 goto out;
1015 err_out:
1016 if (send_strerror(cc, -ret) >= 0)
1017 send_sb(&cc->scc, NULL, 0, SBD_EXIT__FAILURE, true);
1018 net_err:
1019 PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
1020 out:
1021 free(buf);
1022 free(command);
1023 mutex_lock(mmd_mutex);
1024 if (cc->cmd && (cc->cmd->perms & AFS_WRITE) && ret >= 0)
1025 mmd->events++;
1026 mmd->active_connections--;
1027 mutex_unlock(mmd_mutex);
1028 if (ret >= 0) {
1029 ret = send_sb(&cc->scc, NULL, 0, SBD_EXIT__SUCCESS, true);
1030 if (ret < 0)
1031 PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
1032 }
1033 sc_free(cc->scc.recv);
1034 sc_free(cc->scc.send);
1035 exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
1036 }