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