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