command.c

   1 /*
   2  * Copyright (C) 1997-2012 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file command.c Client authentication and server commands. */
   8
   9 #include <regex.h>
  10 #include <signal.h>
  11 #include <sys/time.h>
  12 #include <sys/types.h>
  13 #include <osl.h>
  14
  15 #include "para.h"
  16 #include "error.h"
  17 #include "crypt.h"
  18 #include "sideband.h"
  19 #include "command.h"
  20 #include "server.cmdline.h"
  21 #include "string.h"
  22 #include "afh.h"
  23 #include "afs.h"
  24 #include "server.h"
  25 #include "list.h"
  26 #include "send.h"
  27 #include "sched.h"
  28 #include "vss.h"
  29 #include "net.h"
  30 #include "daemon.h"
  31 #include "fd.h"
  32 #include "ipc.h"
  33 #include "user_list.h"
  34 #include "server_command_list.h"
  35 #include "afs_command_list.h"
  36 #include "signal.h"
  37 #include "version.h"
  38
  39 struct server_command afs_cmds[] = {DEFINE_AFS_CMD_ARRAY};
  40 struct server_command server_cmds[] = {DEFINE_SERVER_CMD_ARRAY};
  41
  42 /** Commands including options must be shorter than this. */
  43 #define MAX_COMMAND_LEN 32768
  44
  45 extern int mmd_mutex;
  46 extern struct misc_meta_data *mmd;
  47 extern struct sender senders[];
  48 int send_afs_status(struct command_context *cc, int parser_friendly);
  49
  50 static void dummy(__a_unused int s)
  51 {
  52 }
  53
  54 static void mmd_dup(struct misc_meta_data *new_mmd)
  55 {
  56         mutex_lock(mmd_mutex);
  57         *new_mmd = *mmd;
  58         mutex_unlock(mmd_mutex);
  59 }
  60
  61 /*
  62  * Compute human readable string containing vss status for given integer value.
  63  *
  64  * We don't want to use vss_playing() and friends here because we take a
  65  * snapshot of the mmd struct and use the copy for computing the state of the
  66  * vss. If the real data were used, we would take the mmd lock for a rather
  67  * long time or risk to get an inconsistent view.
  68  */
  69 static char *vss_status_tohuman(unsigned int flags)
  70 {
  71         if (flags & VSS_PLAYING)
  72                 return para_strdup("playing");
  73         if (flags & VSS_NEXT)
  74                 return para_strdup("stopped");
  75         return para_strdup("paused");
  76 }
  77
  78 /*
  79  * return human readable permission string. Never returns NULL.
  80  */
  81 static char *cmd_perms_itohuman(unsigned int perms)
  82 {
  83         char *msg = para_malloc(5 * sizeof(char));
  84
  85         msg[0] = perms & AFS_READ? 'a' : '-';
  86         msg[1] = perms & AFS_WRITE? 'A' : '-';
  87         msg[2] = perms & VSS_READ? 'v' : '-';
  88         msg[3] = perms & VSS_WRITE? 'V' : '-';
  89         msg[4] = '\0';
  90         return msg;
  91 }
  92
  93 /*
  94  * Never returns NULL.
  95  */
  96 static char *vss_get_status_flags(unsigned int flags)
  97 {
  98         char *msg = para_malloc(5 * sizeof(char));
  99
 100         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
 101         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
 102         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
 103         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
 104         msg[4] = '\0';
 105         return msg;
 106 }
 107
 108 static unsigned get_status(struct misc_meta_data *nmmd, int parser_friendly,
 109                 char **result)
 110 {
 111         char mtime[30] = "";
 112         char *status, *flags; /* vss status info */
 113         /* nobody updates our version of "now" */
 114         char *ut = get_server_uptime_str(NULL);
 115         long offset = (nmmd->offset + 500) / 1000;
 116         struct timeval current_time;
 117         struct tm mtime_tm;
 118         struct para_buffer b = {.flags = parser_friendly? PBF_SIZE_PREFIX : 0};
 119
 120         /* report real status */
 121         status = vss_status_tohuman(nmmd->vss_status_flags);
 122         flags = vss_get_status_flags(nmmd->vss_status_flags);
 123         if (nmmd->size) { /* parent currently has an audio file open */
 124                 localtime_r(&nmmd->mtime, &mtime_tm);
 125                 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
 126         }
 127         gettimeofday(&current_time, NULL);
 128         /*
 129          * The calls to WRITE_STATUS_ITEM() below never fail because
 130          * b->max_size is zero (unlimited), see para_printf(). However, clang
 131          * is not smart enough to prove this and complains nevertheless.
 132          * Casting the return value to void silences clang.
 133          */
 134         (void)WRITE_STATUS_ITEM(&b, SI_FILE_SIZE, "%zu\n", nmmd->size / 1024);
 135         (void)WRITE_STATUS_ITEM(&b, SI_MTIME, "%s\n", mtime);
 136         (void)WRITE_STATUS_ITEM(&b, SI_STATUS, "%s\n", status);
 137         (void)WRITE_STATUS_ITEM(&b, SI_STATUS_FLAGS, "%s\n", flags);
 138         (void)WRITE_STATUS_ITEM(&b, SI_OFFSET, "%li\n", offset);
 139         (void)WRITE_STATUS_ITEM(&b, SI_AFS_MODE, "%s\n", mmd->afs_mode_string);
 140         (void)WRITE_STATUS_ITEM(&b, SI_STREAM_START, "%lu.%lu\n",
 141                 (long unsigned)nmmd->stream_start.tv_sec,
 142                 (long unsigned)nmmd->stream_start.tv_usec);
 143         (void)WRITE_STATUS_ITEM(&b, SI_CURRENT_TIME, "%lu.%lu\n",
 144                 (long unsigned)current_time.tv_sec,
 145                 (long unsigned)current_time.tv_usec);
 146         free(flags);
 147         free(status);
 148         free(ut);
 149         *result = b.buf;
 150         return b.offset;
 151 }
 152
 153 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 154 {
 155         int i;
 156         /* this has to match sender.h */
 157         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 158
 159         scd->sender_num = -1;
 160         if (argc < 2)
 161                 return -E_COMMAND_SYNTAX;
 162         for (i = 0; senders[i].name; i++)
 163                 if (!strcmp(senders[i].name, argv[1]))
 164                         break;
 165         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 166         if (!senders[i].name)
 167                 return -E_COMMAND_SYNTAX;
 168         scd->sender_num = i;
 169         for (i = 0; subcmds[i]; i++)
 170                 if (!strcmp(subcmds[i], argv[2]))
 171                         break;
 172         if (!subcmds[i])
 173                 return -E_COMMAND_SYNTAX;
 174         scd->cmd_num = i;
 175         if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
 176                 return -E_SENDER_CMD;
 177         switch (scd->cmd_num) {
 178         case SENDER_ON:
 179         case SENDER_OFF:
 180                 if (argc != 3)
 181                         return -E_COMMAND_SYNTAX;
 182                 break;
 183         case SENDER_DENY:
 184         case SENDER_ALLOW:
 185                 if (argc != 4 || parse_cidr(argv[3], scd->host,
 186                                 sizeof(scd->host), &scd->netmask) == NULL)
 187                         return -E_COMMAND_SYNTAX;
 188                 break;
 189         case SENDER_ADD:
 190         case SENDER_DELETE:
 191                 if (argc != 4)
 192                         return -E_COMMAND_SYNTAX;
 193                 return parse_fec_url(argv[3], scd);
 194         default:
 195                 return -E_COMMAND_SYNTAX;
 196         }
 197         return 1;
 198 }
 199
 200 /**
 201  * Send a sideband packet through a blocking file descriptor.
 202  *
 203  * \param scc fd and crypto keys.
 204  * \param buf The buffer to send.
 205  * \param numbytes The size of \a buf.
 206  * \param band The sideband designator of this packet.
 207  * \param dont_free If true, never deallocate \a buf.
 208  *
 209  * The nonblock flag must be disabled for the file descriptor given by \a scc.
 210  *
 211  * Stream cipher encryption is automatically activated if neccessary via the
 212  * sideband transformation, depending on the value of \a band.
 213  *
 214  * \return Standard.
 215  *
 216  * \sa \ref send_sb_va().
 217  */
 218 int send_sb(struct stream_cipher_context *scc, void *buf, size_t numbytes,
 219                 int band, bool dont_free)
 220 {
 221         int ret;
 222         struct sb_context *sbc;
 223         struct iovec iov[2];
 224         struct sb_buffer sbb = SBB_INIT(band, buf, numbytes);
 225         sb_transformation trafo = band < SBD_PROCEED? NULL : sc_trafo;
 226
 227         sbc = sb_new_send(&sbb, dont_free, trafo, scc->send);
 228         do {
 229                 ret = sb_get_send_buffers(sbc, iov);
 230                 ret = xwritev(scc->fd, iov, ret);
 231                 if (ret < 0)
 232                         goto fail;
 233         } while (sb_sent(sbc, ret) == false);
 234         return 1;
 235 fail:
 236         sb_free(sbc);
 237         return ret;
 238 }
 239
 240 /**
 241  * Create a variable sized buffer and send it as a sideband packet.
 242  *
 243  * \param scc Passed to \ref send_sb.
 244  * \param band See \ref send_sb.
 245  * \param fmt The format string.
 246  *
 247  * \return The return value of the underlying call to \ref send_sb.
 248  */
 249 __printf_3_4 int send_sb_va(struct stream_cipher_context *scc, int band,
 250                 const char *fmt, ...)
 251 {
 252         va_list ap;
 253         char *msg;
 254         int ret;
 255
 256         va_start(ap, fmt);
 257         ret = xvasprintf(&msg, fmt, ap);
 258         va_end(ap);
 259         return send_sb(scc, msg, ret, band, false);
 260 }
 261
 262 int send_strerror(struct command_context *cc, int err)
 263 {
 264         return cc->use_sideband?
 265                 send_sb_va(&cc->scc, SBD_ERROR_LOG, "%s\n", para_strerror(err))
 266         :
 267                 sc_send_va_buffer(&cc->scc, "%s\n", para_strerror(err));
 268 }
 269
 270 /**
 271  * Send a sideband packet through a blocking file descriptor.
 272  *
 273  * \param scc fd and crypto keys.
 274  * \param expected_band The expected band designator.
 275  * \param max_size Passed to \ref sb_new_recv().
 276  * \param result Body of the sideband packet is returned here.
 277  *
 278  * If \a expected_band is not \p SBD_ANY, the band designator of the received
 279  * sideband packet is compared to \a expected_band and a mismatch is considered
 280  * an error.
 281  *
 282  * \return Standard.
 283  */
 284 int recv_sb(struct stream_cipher_context *scc,
 285                 enum sb_designator expected_band,
 286                 size_t max_size, struct iovec *result)
 287 {
 288         int ret;
 289         struct sb_context *sbc;
 290         struct iovec iov;
 291         struct sb_buffer sbb;
 292         sb_transformation trafo;
 293
 294         trafo = expected_band != SBD_ANY && expected_band < SBD_PROCEED?
 295                 NULL : sc_trafo;
 296         sbc = sb_new_recv(max_size, trafo, scc->recv);
 297         for (;;) {
 298                 sb_get_recv_buffer(sbc, &iov);
 299                 ret = recv_bin_buffer(scc->fd, iov.iov_base, iov.iov_len);
 300                 if (ret == 0)
 301                         ret = -E_EOF;
 302                 if (ret < 0)
 303                         goto fail;
 304                 ret = sb_received(sbc, ret, &sbb);
 305                 if (ret < 0)
 306                         goto fail;
 307                 if (ret > 0)
 308                         break;
 309         }
 310         ret = -E_BAD_BAND;
 311         if (expected_band != SBD_ANY && sbb.band != expected_band)
 312                 goto fail;
 313         *result = sbb.iov;
 314         return 1;
 315 fail:
 316         sb_free(sbc);
 317         return ret;
 318 }
 319
 320 int com_sender(struct command_context *cc)
 321 {
 322         int i, ret = 0;
 323         char *msg = NULL;
 324         struct sender_command_data scd;
 325
 326         if (cc->argc < 2) {
 327                 for (i = 0; senders[i].name; i++) {
 328                         char *tmp;
 329                         ret = xasprintf(&tmp, "%s%s\n", msg? msg : "",
 330                                 senders[i].name);
 331                         free(msg);
 332                         msg = tmp;
 333                 }
 334                 if (cc->use_sideband)
 335                         return send_sb(&cc->scc, msg, ret, SBD_OUTPUT, false);
 336                 ret = sc_send_buffer(&cc->scc, msg);
 337                 free(msg);
 338                 return ret;
 339         }
 340         ret = check_sender_args(cc->argc, cc->argv, &scd);
 341         if (ret < 0) {
 342                 if (scd.sender_num < 0)
 343                         return ret;
 344                 msg = senders[scd.sender_num].help();
 345                 if (cc->use_sideband)
 346                         return send_sb(&cc->scc, msg, strlen(msg), SBD_OUTPUT,
 347                                 false);
 348                 ret = sc_send_buffer(&cc->scc, msg);
 349                 free(msg);
 350                 return ret;
 351         }
 352
 353         switch (scd.cmd_num) {
 354         case SENDER_ADD:
 355         case SENDER_DELETE:
 356                 assert(senders[scd.sender_num].resolve_target);
 357                 ret = senders[scd.sender_num].resolve_target(cc->argv[3], &scd);
 358                 if (ret < 0)
 359                         return ret;
 360         }
 361
 362         for (i = 0; i < 10; i++) {
 363                 mutex_lock(mmd_mutex);
 364                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 365                         mutex_unlock(mmd_mutex);
 366                         usleep(100 * 1000);
 367                         continue;
 368                 }
 369                 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
 370                 mutex_unlock(mmd_mutex);
 371                 break;
 372         }
 373         return (i < 10)? 1 : -E_LOCK;
 374 }
 375
 376 /* server info */
 377 int com_si(struct command_context *cc)
 378 {
 379         int i, ret;
 380         char *msg, *ut, *sender_info = NULL;
 381
 382         if (cc->argc != 1)
 383                 return -E_COMMAND_SYNTAX;
 384         mutex_lock(mmd_mutex);
 385         for (i = 0; senders[i].name; i++) {
 386                 char *info = senders[i].info();
 387                 sender_info = para_strcat(sender_info, info);
 388                 free(info);
 389         }
 390         ut = get_server_uptime_str(now);
 391         ret = xasprintf(&msg, "version: " GIT_VERSION "\n"
 392                 "up: %s\nplayed: %u\n"
 393                 "server_pid: %d\n"
 394                 "afs_pid: %d\n"
 395                 "connections (active/accepted/total): %u/%u/%u\n"
 396                 "current loglevel: %s\n"
 397                 "supported audio formats: %s\n"
 398                 "%s",
 399                 ut, mmd->num_played,
 400                 (int)getppid(),
 401                 (int)mmd->afs_pid,
 402                 mmd->active_connections,
 403                 mmd->num_commands,
 404                 mmd->num_connects,
 405                 conf.loglevel_arg,
 406                 SERVER_AUDIO_FORMATS,
 407                 sender_info
 408         );
 409         mutex_unlock(mmd_mutex);
 410         free(ut);
 411         free(sender_info);
 412         if (cc->use_sideband)
 413                 return send_sb(&cc->scc, msg, ret, SBD_OUTPUT, false);
 414         ret = sc_send_bin_buffer(&cc->scc, msg, ret);
 415         free(msg);
 416         return ret;
 417 }
 418
 419 /* version */
 420 int com_version(struct command_context *cc)
 421 {
 422         char *msg;
 423         size_t len;
 424
 425         if (cc->argc != 1)
 426                 return -E_COMMAND_SYNTAX;
 427         msg = VERSION_TEXT("server") "built: " BUILD_DATE "\n" UNAME_RS
 428                 ", " CC_VERSION "\n";
 429         len = strlen(msg);
 430         if (cc->use_sideband)
 431                 return send_sb(&cc->scc, msg, len, SBD_OUTPUT, true);
 432         return sc_send_bin_buffer(&cc->scc, msg, len);
 433 }
 434
 435 #define EMPTY_STATUS_ITEMS \
 436         ITEM(PATH) \
 437         ITEM(DIRECTORY) \
 438         ITEM(BASENAME) \
 439         ITEM(SCORE) \
 440         ITEM(ATTRIBUTES_BITMAP) \
 441         ITEM(ATTRIBUTES_TXT) \
 442         ITEM(HASH) \
 443         ITEM(IMAGE_ID) \
 444         ITEM(IMAGE_NAME) \
 445         ITEM(LYRICS_ID) \
 446         ITEM(LYRICS_NAME) \
 447         ITEM(BITRATE) \
 448         ITEM(FORMAT) \
 449         ITEM(FREQUENCY) \
 450         ITEM(CHANNELS) \
 451         ITEM(DURATION) \
 452         ITEM(SECONDS_TOTAL) \
 453         ITEM(NUM_PLAYED) \
 454         ITEM(LAST_PLAYED) \
 455         ITEM(TECHINFO) \
 456         ITEM(ARTIST) \
 457         ITEM(TITLE) \
 458         ITEM(YEAR) \
 459         ITEM(ALBUM) \
 460         ITEM(COMMENT) \
 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         static char *esi;
 471         static unsigned len;
 472
 473         if (esi)
 474                 goto out;
 475
 476         if (parser_friendly)
 477                 len = xasprintf(&esi,
 478                         #define ITEM(x) "0004 %02x:\n"
 479                         EMPTY_STATUS_ITEMS
 480                         #undef ITEM
 481                         #define ITEM(x) , SI_ ## x
 482                         EMPTY_STATUS_ITEMS
 483                         #undef ITEM
 484                 );
 485         else
 486                 len = xasprintf(&esi,
 487                         #define ITEM(x) "%s:\n"
 488                         EMPTY_STATUS_ITEMS
 489                         #undef ITEM
 490                         #define ITEM(x) ,status_item_list[SI_ ## x]
 491                         EMPTY_STATUS_ITEMS
 492                         #undef ITEM
 493                 );
 494 out:
 495         *result = esi;
 496         return len;
 497 }
 498 #undef EMPTY_STATUS_ITEMS
 499
 500 /* stat */
 501 int com_stat(struct command_context *cc)
 502 {
 503         int i, ret;
 504         struct misc_meta_data tmp, *nmmd = &tmp;
 505         char *s, *esi = NULL;
 506         int32_t num = 0;
 507         int parser_friendly = 0;
 508
 509         para_sigaction(SIGUSR1, dummy);
 510
 511         for (i = 1; i < cc->argc; i++) {
 512                 const char *arg = cc->argv[i];
 513                 if (arg[0] != '-')
 514                         break;
 515                 if (!strcmp(arg, "--")) {
 516                         i++;
 517                         break;
 518                 }
 519                 if (!strncmp(arg, "-n=", 3)) {
 520                         ret = para_atoi32(arg + 3, &num);
 521                         if (ret < 0)
 522                                 return ret;
 523                         continue;
 524                 }
 525                 if (!strcmp(arg, "-p")) {
 526                         parser_friendly = 1;
 527                         continue;
 528                 }
 529                 return -E_COMMAND_SYNTAX;
 530         }
 531         if (i != cc->argc)
 532                 return -E_COMMAND_SYNTAX;
 533         for (;;) {
 534                 mmd_dup(nmmd);
 535                 ret = get_status(nmmd, parser_friendly, &s);
 536                 if (cc->use_sideband)
 537                         ret = send_sb(&cc->scc, s, ret, SBD_OUTPUT, false);
 538                 else {
 539                         ret = sc_send_bin_buffer(&cc->scc, s, ret);
 540                         free(s);
 541                 }
 542                 if (ret < 0)
 543                         goto out;
 544                 if (nmmd->vss_status_flags & VSS_NEXT) {
 545                         ret = empty_status_items(parser_friendly, &esi);
 546                         if (cc->use_sideband)
 547                                 ret = send_sb(&cc->scc, esi, ret, SBD_OUTPUT,
 548                                         true);
 549                         else
 550                                 ret = sc_send_bin_buffer(&cc->scc, esi, ret);
 551                         if (ret < 0)
 552                                 goto out;
 553                 } else
 554                         send_afs_status(cc, parser_friendly);
 555                 ret = 1;
 556                 if (num > 0 && !--num)
 557                         goto out;
 558                 sleep(50);
 559                 ret = -E_SERVER_CRASH;
 560                 if (getppid() == 1)
 561                         goto out;
 562         }
 563 out:
 564         free(esi);
 565         return ret;
 566 }
 567
 568 static int send_list_of_commands(struct command_context *cc, struct server_command *cmd,
 569                 const char *handler)
 570 {
 571         int ret;
 572         char *msg = NULL;
 573
 574         for (; cmd->name; cmd++) {
 575                 char *tmp, *perms = cmd_perms_itohuman(cmd->perms);
 576                 tmp = make_message("%s\t%s\t%s\t%s\n", cmd->name, handler,
 577                         perms, cmd->description);
 578                 free(perms);
 579                 msg = para_strcat(msg, tmp);
 580                 free(tmp);
 581         }
 582         if (cc->use_sideband)
 583                 return send_sb(&cc->scc, msg, strlen(msg), SBD_OUTPUT, false);
 584         ret = sc_send_buffer(&cc->scc, msg);
 585         free(msg);
 586         return ret;
 587 }
 588
 589 /* returns string that must be freed by the caller */
 590 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 591 {
 592         struct server_command *cmd;
 593
 594         for (cmd = server_cmds; cmd->name; cmd++)
 595                 if (!strcmp(cmd->name, name)) {
 596                         if (handler)
 597                                 *handler = para_strdup("server"); /* server commands */
 598                         return cmd;
 599                 }
 600         /* not found, look for commands supported by afs */
 601         for (cmd = afs_cmds; cmd->name; cmd++)
 602                 if (!strcmp(cmd->name, name)) {
 603                         if (handler)
 604                                 *handler = para_strdup("afs");
 605                         return cmd;
 606                 }
 607         return NULL;
 608 }
 609
 610 /* help */
 611 int com_help(struct command_context *cc)
 612 {
 613         struct server_command *cmd;
 614         char *perms, *handler, *buf;
 615         int ret;
 616
 617         if (cc->argc < 2) {
 618                 /* no argument given, print list of commands */
 619                 if ((ret = send_list_of_commands(cc, server_cmds, "server")) < 0)
 620                         return ret;
 621                 return send_list_of_commands(cc, afs_cmds, "afs");
 622         }
 623         /* argument given for help */
 624         cmd = get_cmd_ptr(cc->argv[1], &handler);
 625         if (!cmd)
 626                 return -E_BAD_CMD;
 627         perms = cmd_perms_itohuman(cmd->perms);
 628         ret = xasprintf(&buf, "%s - %s\n\n"
 629                 "handler: %s\n"
 630                 "permissions: %s\n"
 631                 "usage: %s\n\n"
 632                 "%s\n",
 633                 cc->argv[1],
 634                 cmd->description,
 635                 handler,
 636                 perms,
 637                 cmd->usage,
 638                 cmd->help
 639         );
 640         free(perms);
 641         free(handler);
 642         if (cc->use_sideband)
 643                 return send_sb(&cc->scc, buf, ret, SBD_OUTPUT, false);
 644         ret = sc_send_buffer(&cc->scc, buf);
 645         free(buf);
 646         return ret;
 647 }
 648
 649 /* hup */
 650 int com_hup(struct command_context *cc)
 651 {
 652         if (cc->argc != 1)
 653                 return -E_COMMAND_SYNTAX;
 654         kill(getppid(), SIGHUP);
 655         return 1;
 656 }
 657
 658 /* term */
 659 int com_term(struct command_context *cc)
 660 {
 661         if (cc->argc != 1)
 662                 return -E_COMMAND_SYNTAX;
 663         kill(getppid(), SIGTERM);
 664         return 1;
 665 }
 666
 667 int com_play(struct command_context *cc)
 668 {
 669         if (cc->argc != 1)
 670                 return -E_COMMAND_SYNTAX;
 671         mutex_lock(mmd_mutex);
 672         mmd->new_vss_status_flags |= VSS_PLAYING;
 673         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 674         mutex_unlock(mmd_mutex);
 675         return 1;
 676 }
 677
 678 /* stop */
 679 int com_stop(struct command_context *cc)
 680 {
 681         if (cc->argc != 1)
 682                 return -E_COMMAND_SYNTAX;
 683         mutex_lock(mmd_mutex);
 684         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 685         mmd->new_vss_status_flags &= ~VSS_REPOS;
 686         mmd->new_vss_status_flags |= VSS_NEXT;
 687         mutex_unlock(mmd_mutex);
 688         return 1;
 689 }
 690
 691 /* pause */
 692 int com_pause(struct command_context *cc)
 693 {
 694         if (cc->argc != 1)
 695                 return -E_COMMAND_SYNTAX;
 696         mutex_lock(mmd_mutex);
 697         if (!vss_paused() && !vss_stopped()) {
 698                 mmd->events++;
 699                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 700                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 701         }
 702         mutex_unlock(mmd_mutex);
 703         return 1;
 704 }
 705
 706 /* next */
 707 int com_next(struct command_context *cc)
 708 {
 709         if (cc->argc != 1)
 710                 return -E_COMMAND_SYNTAX;
 711         mutex_lock(mmd_mutex);
 712         mmd->events++;
 713         mmd->new_vss_status_flags |= VSS_NEXT;
 714         mutex_unlock(mmd_mutex);
 715         return 1;
 716 }
 717
 718 /* nomore */
 719 int com_nomore(struct command_context *cc)
 720 {
 721         if (cc->argc != 1)
 722                 return -E_COMMAND_SYNTAX;
 723         mutex_lock(mmd_mutex);
 724         if (vss_playing() || vss_paused())
 725                 mmd->new_vss_status_flags |= VSS_NOMORE;
 726         mutex_unlock(mmd_mutex);
 727         return 1;
 728 }
 729
 730 /* ff */
 731 int com_ff(struct command_context *cc)
 732 {
 733         long promille;
 734         int ret, backwards = 0;
 735         unsigned i;
 736         char c;
 737
 738         if (cc->argc != 2)
 739                 return -E_COMMAND_SYNTAX;
 740         if (!(ret = sscanf(cc->argv[1], "%u%c", &i, &c)))
 741                 return -E_COMMAND_SYNTAX;
 742         if (ret > 1 && c == '-')
 743                 backwards = 1; /* jmp backwards */
 744         mutex_lock(mmd_mutex);
 745         ret = -E_NO_AUDIO_FILE;
 746         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 747                 goto out;
 748         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 749         if (backwards)
 750                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 751         else
 752                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 753         if (promille < 0)
 754                 promille = 0;
 755         if (promille >  1000) {
 756                 mmd->new_vss_status_flags |= VSS_NEXT;
 757                 goto out;
 758         }
 759         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 760         mmd->new_vss_status_flags |= VSS_REPOS;
 761         mmd->new_vss_status_flags &= ~VSS_NEXT;
 762         mmd->events++;
 763         ret = 1;
 764 out:
 765         mutex_unlock(mmd_mutex);
 766         return ret;
 767 }
 768
 769 /* jmp */
 770 int com_jmp(struct command_context *cc)
 771 {
 772         long unsigned int i;
 773         int ret;
 774
 775         if (cc->argc != 2)
 776                 return -E_COMMAND_SYNTAX;
 777         if (sscanf(cc->argv[1], "%lu", &i) <= 0)
 778                 return -E_COMMAND_SYNTAX;
 779         mutex_lock(mmd_mutex);
 780         ret = -E_NO_AUDIO_FILE;
 781         if (!mmd->afd.afhi.chunks_total)
 782                 goto out;
 783         if (i > 100)
 784                 i = 100;
 785         PARA_INFO_LOG("jumping to %lu%%\n", i);
 786         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 787         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 788                 mmd->chunks_sent, mmd->offset);
 789         mmd->new_vss_status_flags |= VSS_REPOS;
 790         mmd->new_vss_status_flags &= ~VSS_NEXT;
 791         ret = 1;
 792         mmd->events++;
 793 out:
 794         mutex_unlock(mmd_mutex);
 795         return ret;
 796 }
 797
 798 /*
 799  * check if perms are sufficient to exec a command having perms cmd_perms.
 800  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 801  */
 802 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 803 {
 804         PARA_DEBUG_LOG("checking permissions\n");
 805         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 806 }
 807
 808 /*
 809  * Parse first string from *cmd and lookup in table of valid commands.
 810  * On error, NULL is returned.
 811  */
 812 static struct server_command *parse_cmd(const char *cmdstr)
 813 {
 814         char buf[255];
 815         int n = 0;
 816
 817         sscanf(cmdstr, "%200s%n", buf, &n);
 818         if (!n)
 819                 return NULL;
 820         buf[n] = '\0';
 821         return get_cmd_ptr(buf, NULL);
 822 }
 823
 824 static int read_command(struct stream_cipher_context *scc, char **result)
 825 {
 826         int ret;
 827         char buf[4096];
 828         char *command = NULL;
 829
 830         for (;;) {
 831                 size_t numbytes;
 832                 char *p;
 833
 834                 ret = sc_recv_buffer(scc, buf, sizeof(buf));
 835                 if (ret < 0)
 836                         goto out;
 837                 if (!ret)
 838                         break;
 839                 numbytes = ret;
 840                 ret = -E_COMMAND_SYNTAX;
 841                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 842                         goto out;
 843                 command = para_strcat(command, buf);
 844                 p = strstr(command, EOC_MSG);
 845                 if (p) {
 846                         *p = '\0';
 847                         break;
 848                 }
 849         }
 850         ret = command? 1 : -E_COMMAND_SYNTAX;
 851 out:
 852         if (ret < 0)
 853                 free(command);
 854         else
 855                 *result = command;
 856         return ret;
 857
 858 }
 859
 860 static void reset_signals(void)
 861 {
 862         para_sigaction(SIGCHLD, SIG_IGN);
 863         para_sigaction(SIGINT, SIG_DFL);
 864         para_sigaction(SIGTERM, SIG_DFL);
 865         para_sigaction(SIGHUP, SIG_DFL);
 866 }
 867
 868 static int parse_auth_request(char *buf, int len, struct user **u,
 869                 bool *use_sideband)
 870 {
 871         int ret;
 872         char *p, *username, **features = NULL;
 873         size_t auth_rq_len = strlen(AUTH_REQUEST_MSG);
 874
 875         *u = NULL;
 876         *use_sideband = false;
 877         if (len < auth_rq_len + 2)
 878                 return -E_AUTH_REQUEST;
 879         if (strncmp(buf, AUTH_REQUEST_MSG, auth_rq_len) != 0)
 880                 return -E_AUTH_REQUEST;
 881         username = buf + auth_rq_len;
 882         p = strchr(username, ' ');
 883         if (p) {
 884                 int i;
 885                 if (p == username)
 886                         return -E_AUTH_REQUEST;
 887                 *p = '\0';
 888                 p++;
 889                 create_argv(p, ",", &features);
 890                 for (i = 0; features[i]; i++) {
 891                         if (strcmp(features[i], "sideband") == 0)
 892                                 *use_sideband = true;
 893                         else {
 894                                 ret = -E_BAD_FEATURE;
 895                                 goto out;
 896                         }
 897                 }
 898         }
 899         PARA_DEBUG_LOG("received auth request for user %s (sideband = %s)\n",
 900                 username, *use_sideband? "true" : "false");
 901         *u = lookup_user(username);
 902         ret = 1;
 903 out:
 904         free_argv(features);
 905         return ret;
 906 }
 907
 908 #define HANDSHAKE_BUFSIZE 4096
 909
 910 static int parse_sb_command(struct command_context *cc, struct iovec *iov)
 911 {
 912         int ret, i;
 913         char *p, *end;
 914
 915         ret = -E_BAD_CMD;
 916         if (iov->iov_base == NULL || iov->iov_len == 0)
 917                 goto out;
 918         p = iov->iov_base;
 919         p[iov->iov_len - 1] = '\0'; /* just to be sure */
 920         cc->cmd = get_cmd_ptr(p, NULL);
 921         if (!cc->cmd)
 922                 goto out;
 923         ret = check_perms(cc->u->perms, cc->cmd);
 924         if (ret < 0)
 925                 goto out;
 926         end = iov->iov_base + iov->iov_len;
 927         for (i = 0, p = iov->iov_base; p < end; i++)
 928                 p += strlen(p) + 1;
 929         cc->argc = i;
 930         cc->argv = para_malloc((cc->argc + 1) * sizeof(char *));
 931         for (i = 0, p = iov->iov_base; p < end; i++) {
 932                 cc->argv[i] = para_strdup(p);
 933                 p += strlen(p) + 1;
 934         }
 935         cc->argv[cc->argc] = NULL;
 936         ret = cc->argc;
 937 out:
 938         free(iov->iov_base);
 939         return ret;
 940 }
 941
 942 /**
 943  * Perform user authentication and execute a command.
 944  *
 945  * \param fd The file descriptor to send output to.
 946  * \param peername Identifies the connecting peer.
 947  *
 948  * Whenever para_server accepts an incoming tcp connection on
 949  * the port it listens on, it forks and the resulting child
 950  * calls this function.
 951  *
 952  * An RSA-based challenge/response is used to authenticate
 953  * the peer. It that authentication succeeds, a random
 954  * session key is generated and sent back to the peer,
 955  * encrypted with its RSA public key.  From this point on,
 956  * all transfers are crypted with this session key.
 957  *
 958  * Next it is checked if the peer supplied  a valid server command or a command
 959  * for the audio file selector.  If yes, and if the user has sufficient
 960  * permissions to execute that command, the function calls the corresponding
 961  * command handler which does argument checking and further processing.
 962  *
 963  * In order to cope with a DOS attacks, a timeout is set up
 964  * which terminates the function if the connection was not
 965  * authenticated when the timeout expires.
 966  *
 967  * \sa alarm(2), crypt.c, crypt.h
 968  */
 969 __noreturn void handle_connect(int fd, const char *peername)
 970 {
 971         int ret;
 972         unsigned char rand_buf[CHALLENGE_SIZE + 2 * SESSION_KEY_LEN];
 973         unsigned char challenge_hash[HASH_SIZE];
 974         char *p, *command = NULL, *buf = para_malloc(HANDSHAKE_BUFSIZE) /* must be on the heap */;
 975         size_t numbytes;
 976         struct command_context cc_struct = {.peer = peername}, *cc = &cc_struct;
 977
 978         cc->scc.fd = fd;
 979         reset_signals();
 980         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 981         ret = mark_fd_blocking(fd);
 982         if (ret < 0)
 983                 goto net_err;
 984         /* send Welcome message */
 985         ret = write_va_buffer(fd, "This is para_server, version "
 986                 PACKAGE_VERSION  ".\n"
 987                 "Features: sideband,foo\n"
 988         );
 989         if (ret < 0)
 990                 goto net_err;
 991         /* recv auth request line */
 992         ret = recv_buffer(fd, buf, HANDSHAKE_BUFSIZE);
 993         if (ret < 0)
 994                 goto net_err;
 995         ret = parse_auth_request(buf, ret, &cc->u, &cc->use_sideband);
 996         if (ret < 0)
 997                 goto net_err;
 998         p = buf + strlen(AUTH_REQUEST_MSG);
 999         PARA_DEBUG_LOG("received auth request for user %s\n", p);
1000         cc->u = lookup_user(p);
1001         if (cc->u) {
1002                 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
1003                 ret = pub_encrypt(cc->u->pubkey, rand_buf, sizeof(rand_buf),
1004                         (unsigned char *)buf);
1005                 if (ret < 0)
1006                         goto net_err;
1007                 numbytes = ret;
1008         } else {
1009                 /*
1010                  * We don't want to reveal our user names, so we send a
1011                  * challenge to the client even if the user does not exist, and
1012                  * fail the authentication later.
1013                  */
1014                 numbytes = 256;
1015                 get_random_bytes_or_die((unsigned char *)buf, numbytes);
1016         }
1017         PARA_DEBUG_LOG("sending %u byte challenge + rc4 keys (%zu bytes)\n",
1018                 CHALLENGE_SIZE, numbytes);
1019         if (cc->use_sideband) {
1020                 struct iovec iov;
1021                 ret = send_sb(&cc->scc, buf, numbytes, SBD_CHALLENGE, false);
1022                 buf = NULL;
1023                 if (ret < 0)
1024                         goto net_err;
1025                 ret = recv_sb(&cc->scc, SBD_CHALLENGE_RESPONSE,
1026                         HANDSHAKE_BUFSIZE, &iov);
1027                 if (ret < 0)
1028                         goto net_err;
1029                 buf = iov.iov_base;
1030                 numbytes = iov.iov_len;
1031         } else {
1032                 ret = write_all(fd, buf, numbytes);
1033                 if (ret < 0)
1034                         goto net_err;
1035                 /* recv challenge response */
1036                 ret = recv_bin_buffer(fd, buf, HASH_SIZE);
1037                 if (ret < 0)
1038                         goto net_err;
1039                 numbytes = ret;
1040         }
1041         PARA_DEBUG_LOG("received %zu bytes challenge response\n", numbytes);
1042         ret = -E_BAD_USER;
1043         if (!cc->u)
1044                 goto net_err;
1045         /*
1046          * The correct response is the hash of the first CHALLENGE_SIZE bytes
1047          * of the random data.
1048          */
1049         ret = -E_BAD_AUTH;
1050         if (numbytes != HASH_SIZE)
1051                 goto net_err;
1052         hash_function((char *)rand_buf, CHALLENGE_SIZE, challenge_hash);
1053         if (memcmp(challenge_hash, buf, HASH_SIZE))
1054                 goto net_err;
1055         /* auth successful */
1056         alarm(0);
1057         PARA_INFO_LOG("good auth for %s\n", cc->u->name);
1058         /* init stream cipher keys with the second part of the random buffer */
1059         cc->scc.recv = sc_new(rand_buf + CHALLENGE_SIZE, SESSION_KEY_LEN);
1060         cc->scc.send = sc_new(rand_buf + CHALLENGE_SIZE + SESSION_KEY_LEN, SESSION_KEY_LEN);
1061         if (cc->use_sideband)
1062                 ret = send_sb(&cc->scc, NULL, 0, SBD_PROCEED, false);
1063         else
1064                 ret = sc_send_buffer(&cc->scc, PROCEED_MSG);
1065         if (ret < 0)
1066                 goto net_err;
1067         if (cc->use_sideband) {
1068                 struct iovec iov;
1069                 ret = recv_sb(&cc->scc, SBD_COMMAND, MAX_COMMAND_LEN, &iov);
1070                 if (ret < 0)
1071                         goto net_err;
1072                 ret = parse_sb_command(cc, &iov);
1073                 if (ret < 0)
1074                         goto err_out;
1075                 cc->argc = ret;
1076         } else {
1077                 ret = read_command(&cc->scc, &command);
1078                 if (ret == -E_COMMAND_SYNTAX)
1079                         goto err_out;
1080                 if (ret < 0)
1081                         goto net_err;
1082                 ret = -E_BAD_CMD;
1083                 cc->cmd = parse_cmd(command);
1084                 if (!cc->cmd)
1085                         goto err_out;
1086                 /* valid command, check permissions */
1087                 ret = check_perms(cc->u->perms, cc->cmd);
1088                 if (ret < 0)
1089                         goto err_out;
1090                 /* valid command and sufficient perms */
1091                 ret = create_argv(command, "\n", &cc->argv);
1092                 if (ret < 0)
1093                         goto err_out;
1094                 cc->argc = ret;
1095         }
1096         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cc->cmd->name,
1097                 cc->u->name, peername);
1098         ret = cc->cmd->handler(cc);
1099         free_argv(cc->argv);
1100         mutex_lock(mmd_mutex);
1101         mmd->num_commands++;
1102         mutex_unlock(mmd_mutex);
1103         if (ret >= 0)
1104                 goto out;
1105 err_out:
1106         if (send_strerror(cc, -ret) >= 0 && cc->use_sideband)
1107                 send_sb(&cc->scc, NULL, 0, SBD_EXIT__FAILURE, true);
1108 net_err:
1109         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
1110 out:
1111         free(buf);
1112         free(command);
1113         mutex_lock(mmd_mutex);
1114         if (cc->cmd && (cc->cmd->perms & AFS_WRITE) && ret >= 0)
1115                 mmd->events++;
1116         mmd->active_connections--;
1117         mutex_unlock(mmd_mutex);
1118         if (ret >= 0 && cc->use_sideband) {
1119                 ret = send_sb(&cc->scc, NULL, 0, SBD_EXIT__SUCCESS, true);
1120                 if (ret < 0)
1121                         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
1122         }
1123         sc_free(cc->scc.recv);
1124         sc_free(cc->scc.send);
1125         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
1126 }