command.c

   1 /*
   2  * Copyright (C) 1997-2011 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 #include <stdbool.h>
  15
  16 #include "para.h"
  17 #include "error.h"
  18 #include "crypt.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 "vss.h"
  28 #include "net.h"
  29 #include "daemon.h"
  30 #include "fd.h"
  31 #include "ipc.h"
  32 #include "user_list.h"
  33 #include "server_command_list.h"
  34 #include "afs_command_list.h"
  35 #include "sched.h"
  36 #include "signal.h"
  37
  38 /** Commands including options must be shorter than this. */
  39 #define MAX_COMMAND_LEN 32768
  40
  41 extern int mmd_mutex;
  42 extern struct misc_meta_data *mmd;
  43 extern struct sender senders[];
  44 int send_afs_status(struct stream_cipher_context *scc, int parser_friendly);
  45
  46 const char *status_item_list[] = {STATUS_ITEM_ARRAY};
  47
  48 static void dummy(__a_unused int s)
  49 {
  50 }
  51
  52 static void mmd_dup(struct misc_meta_data *new_mmd)
  53 {
  54         mutex_lock(mmd_mutex);
  55         *new_mmd = *mmd;
  56         mutex_unlock(mmd_mutex);
  57 }
  58
  59 /*
  60  * Compute human readable string containing vss status for given integer value.
  61  *
  62  * We don't want to use vss_playing() and friends here because we take a
  63  * snapshot of the mmd struct and use the copy for computing the state of the
  64  * vss. If the real data were used, we would take the mmd lock for a rather
  65  * long time or risk to get an inconsistent view.
  66  */
  67 static char *vss_status_tohuman(unsigned int flags)
  68 {
  69         if (flags & VSS_PLAYING)
  70                 return para_strdup("playing");
  71         if (flags & VSS_NEXT)
  72                 return para_strdup("stopped");
  73         return para_strdup("paused");
  74 }
  75
  76 /*
  77  * return human readable permission string. Never returns NULL.
  78  */
  79 static char *cmd_perms_itohuman(unsigned int perms)
  80 {
  81         char *msg = para_malloc(5 * sizeof(char));
  82
  83         msg[0] = perms & AFS_READ? 'a' : '-';
  84         msg[1] = perms & AFS_WRITE? 'A' : '-';
  85         msg[2] = perms & VSS_READ? 'v' : '-';
  86         msg[3] = perms & VSS_WRITE? 'V' : '-';
  87         msg[4] = '\0';
  88         return msg;
  89 }
  90
  91 /*
  92  * Never returns NULL.
  93  */
  94 static char *vss_get_status_flags(unsigned int flags)
  95 {
  96         char *msg = para_malloc(5 * sizeof(char));
  97
  98         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
  99         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
 100         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
 101         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
 102         msg[4] = '\0';
 103         return msg;
 104 }
 105
 106 static char *get_status(struct misc_meta_data *nmmd, int parser_friendly)
 107 {
 108         char mtime[30] = "";
 109         char *status, *flags; /* vss status info */
 110         char *ut = uptime_str();
 111         long offset = (nmmd->offset + 500) / 1000;
 112         struct timeval current_time;
 113         struct tm mtime_tm;
 114         struct para_buffer b = {.flags = parser_friendly? PBF_SIZE_PREFIX : 0};
 115
 116         /* report real status */
 117         status = vss_status_tohuman(nmmd->vss_status_flags);
 118         flags = vss_get_status_flags(nmmd->vss_status_flags);
 119         if (nmmd->size) { /* parent currently has an audio file open */
 120                 localtime_r(&nmmd->mtime, &mtime_tm);
 121                 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
 122         }
 123         gettimeofday(&current_time, NULL);
 124         WRITE_STATUS_ITEM(&b, SI_FILE_SIZE, "%zu\n", nmmd->size / 1024);
 125         WRITE_STATUS_ITEM(&b, SI_MTIME, "%s\n", mtime);
 126         WRITE_STATUS_ITEM(&b, SI_STATUS, "%s\n", status);
 127         WRITE_STATUS_ITEM(&b, SI_STATUS_FLAGS, "%s\n", flags);
 128         WRITE_STATUS_ITEM(&b, SI_OFFSET, "%li\n", offset);
 129         WRITE_STATUS_ITEM(&b, SI_AFS_MODE, "%s\n", mmd->afs_mode_string);
 130         WRITE_STATUS_ITEM(&b, SI_STREAM_START, "%lu.%lu\n",
 131                 (long unsigned)nmmd->stream_start.tv_sec,
 132                 (long unsigned)nmmd->stream_start.tv_usec);
 133         WRITE_STATUS_ITEM(&b, SI_CURRENT_TIME, "%lu.%lu\n",
 134                 (long unsigned)current_time.tv_sec,
 135                 (long unsigned)current_time.tv_usec);
 136         free(flags);
 137         free(status);
 138         free(ut);
 139         return b.buf;
 140 }
 141
 142 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 143 {
 144         int i;
 145         /* this has to match sender.h */
 146         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 147
 148         scd->sender_num = -1;
 149         if (argc < 2)
 150                 return -E_COMMAND_SYNTAX;
 151         for (i = 0; senders[i].name; i++)
 152                 if (!strcmp(senders[i].name, argv[1]))
 153                         break;
 154         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 155         if (!senders[i].name)
 156                 return -E_COMMAND_SYNTAX;
 157         scd->sender_num = i;
 158         for (i = 0; subcmds[i]; i++)
 159                 if (!strcmp(subcmds[i], argv[2]))
 160                         break;
 161         if (!subcmds[i])
 162                 return -E_COMMAND_SYNTAX;
 163         scd->cmd_num = i;
 164         if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
 165                 return -E_SENDER_CMD;
 166         switch (scd->cmd_num) {
 167         case SENDER_ON:
 168         case SENDER_OFF:
 169                 if (argc != 3)
 170                         return -E_COMMAND_SYNTAX;
 171                 break;
 172         case SENDER_DENY:
 173         case SENDER_ALLOW:
 174                 if (argc != 4 || parse_cidr(argv[3], scd->host,
 175                                 sizeof(scd->host), &scd->netmask) == NULL)
 176                         return -E_COMMAND_SYNTAX;
 177                 break;
 178         case SENDER_ADD:
 179         case SENDER_DELETE:
 180                 if (argc != 4)
 181                         return -E_COMMAND_SYNTAX;
 182                 return parse_fec_url(argv[3], scd);
 183         default:
 184                 return -E_COMMAND_SYNTAX;
 185         }
 186         return 1;
 187 }
 188
 189 int com_sender(struct stream_cipher_context *scc, int argc, char * const * argv)
 190 {
 191         int i, ret;
 192         char *msg = NULL;
 193         struct sender_command_data scd;
 194
 195         if (argc < 2) {
 196                 for (i = 0; senders[i].name; i++) {
 197                         char *tmp = make_message("%s%s\n",
 198                                 msg? msg : "", senders[i].name);
 199                         free(msg);
 200                         msg = tmp;
 201                 }
 202                 ret = sc_send_buffer(scc, msg);
 203                 free(msg);
 204                 return ret;
 205         }
 206         ret = check_sender_args(argc, argv, &scd);
 207         if (ret < 0) {
 208                 if (scd.sender_num < 0)
 209                         return ret;
 210                 msg = senders[scd.sender_num].help();
 211                 ret = sc_send_buffer(scc, msg);
 212                 free(msg);
 213                 return ret;
 214         }
 215
 216         switch (scd.cmd_num) {
 217         case SENDER_ADD:
 218         case SENDER_DELETE:
 219                 assert(senders[scd.sender_num].resolve_target);
 220                 ret = senders[scd.sender_num].resolve_target(argv[3], &scd);
 221                 if (ret < 0)
 222                         return ret;
 223         }
 224
 225         for (i = 0; i < 10; i++) {
 226                 mutex_lock(mmd_mutex);
 227                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 228                         mutex_unlock(mmd_mutex);
 229                         usleep(100 * 1000);
 230                         continue;
 231                 }
 232                 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
 233                 mutex_unlock(mmd_mutex);
 234                 break;
 235         }
 236         return (i < 10)? 1 : -E_LOCK;
 237 }
 238
 239 /* server info */
 240 int com_si(struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 241 {
 242         int i, ret;
 243         char *ut;
 244         char *sender_info = NULL;
 245
 246         if (argc != 1)
 247                 return -E_COMMAND_SYNTAX;
 248         mutex_lock(mmd_mutex);
 249         for (i = 0; senders[i].name; i++) {
 250                 char *info = senders[i].info();
 251                 sender_info = para_strcat(sender_info, info);
 252                 free(info);
 253         }
 254         ut = uptime_str();
 255         ret = sc_send_va_buffer(scc, "version: " GIT_VERSION "\n"
 256                 "up: %s\nplayed: %u\n"
 257                 "server_pid: %d\n"
 258                 "afs_pid: %d\n"
 259                 "connections (active/accepted/total): %u/%u/%u\n"
 260                 "current loglevel: %s\n"
 261                 "supported audio formats: %s\n"
 262                 "%s",
 263                 ut, mmd->num_played,
 264                 (int)getppid(),
 265                 (int)mmd->afs_pid,
 266                 mmd->active_connections,
 267                 mmd->num_commands,
 268                 mmd->num_connects,
 269                 conf.loglevel_arg,
 270                 SERVER_AUDIO_FORMATS,
 271                 sender_info
 272         );
 273         mutex_unlock(mmd_mutex);
 274         free(ut);
 275         free(sender_info);
 276         return ret;
 277 }
 278
 279 /* version */
 280 int com_version(struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 281 {
 282         if (argc != 1)
 283                 return -E_COMMAND_SYNTAX;
 284         return sc_send_buffer(scc, VERSION_TEXT("server")
 285                 "built: " BUILD_DATE "\n"
 286                 UNAME_RS ", " CC_VERSION "\n"
 287         );
 288 }
 289
 290 #define EMPTY_STATUS_ITEMS \
 291         ITEM(PATH) \
 292         ITEM(DIRECTORY) \
 293         ITEM(BASENAME) \
 294         ITEM(SCORE) \
 295         ITEM(ATTRIBUTES_BITMAP) \
 296         ITEM(ATTRIBUTES_TXT) \
 297         ITEM(HASH) \
 298         ITEM(IMAGE_ID) \
 299         ITEM(IMAGE_NAME) \
 300         ITEM(LYRICS_ID) \
 301         ITEM(LYRICS_NAME) \
 302         ITEM(BITRATE) \
 303         ITEM(FORMAT) \
 304         ITEM(FREQUENCY) \
 305         ITEM(CHANNELS) \
 306         ITEM(DURATION) \
 307         ITEM(SECONDS_TOTAL) \
 308         ITEM(NUM_PLAYED) \
 309         ITEM(LAST_PLAYED) \
 310         ITEM(TECHINFO) \
 311         ITEM(ARTIST) \
 312         ITEM(TITLE) \
 313         ITEM(YEAR) \
 314         ITEM(ALBUM) \
 315         ITEM(COMMENT) \
 316         ITEM(AMPLIFICATION)
 317
 318 /**
 319  * Write a list of audio-file related status items with empty values.
 320  *
 321  * This is used by vss when currently no audio file is open.
 322  */
 323 static char *empty_status_items(int parser_friendly)
 324 {
 325         if (parser_friendly)
 326                 return make_message(
 327                         #define ITEM(x) "0004 %02x:\n"
 328                         EMPTY_STATUS_ITEMS
 329                         #undef ITEM
 330                         #define ITEM(x) , SI_ ## x
 331                         EMPTY_STATUS_ITEMS
 332                         #undef ITEM
 333                 );
 334         return make_message(
 335                 #define ITEM(x) "%s:\n"
 336                 EMPTY_STATUS_ITEMS
 337                 #undef ITEM
 338                 #define ITEM(x) ,status_item_list[SI_ ## x]
 339                 EMPTY_STATUS_ITEMS
 340                 #undef ITEM
 341         );
 342 }
 343 #undef EMPTY_STATUS_ITEMS
 344
 345 /* stat */
 346 int com_stat(struct stream_cipher_context *scc, int argc, char * const * argv)
 347 {
 348         int i, ret;
 349         struct misc_meta_data tmp, *nmmd = &tmp;
 350         char *s;
 351         int32_t num = 0;
 352         int parser_friendly = 0;
 353
 354         para_sigaction(SIGUSR1, dummy);
 355
 356         for (i = 1; i < argc; i++) {
 357                 const char *arg = argv[i];
 358                 if (arg[0] != '-')
 359                         break;
 360                 if (!strcmp(arg, "--")) {
 361                         i++;
 362                         break;
 363                 }
 364                 if (!strncmp(arg, "-n=", 3)) {
 365                         ret = para_atoi32(arg + 3, &num);
 366                         if (ret < 0)
 367                                 return ret;
 368                         continue;
 369                 }
 370                 if (!strcmp(arg, "-p")) {
 371                         parser_friendly = 1;
 372                         continue;
 373                 }
 374                 return -E_COMMAND_SYNTAX;
 375         }
 376         if (i != argc)
 377                 return -E_COMMAND_SYNTAX;
 378         for (;;) {
 379                 mmd_dup(nmmd);
 380                 s = get_status(nmmd, parser_friendly);
 381                 ret = sc_send_buffer(scc, s);
 382                 free(s);
 383                 if (ret < 0)
 384                         goto out;
 385                 if (nmmd->vss_status_flags & VSS_NEXT) {
 386                         static char *esi;
 387                         if (!esi)
 388                                 esi = empty_status_items(parser_friendly);
 389                         ret = sc_send_buffer(scc, esi);
 390                         if (ret < 0)
 391                                 goto out;
 392                 } else
 393                         send_afs_status(scc, parser_friendly);
 394                 ret = 1;
 395                 if (num > 0 && !--num)
 396                         goto out;
 397                 sleep(50);
 398                 if (getppid() == 1)
 399                         return -E_SERVER_CRASH;
 400         }
 401 out:
 402         return ret;
 403 }
 404
 405 static int send_list_of_commands(struct stream_cipher_context *scc, struct server_command *cmd,
 406                 const char *handler)
 407 {
 408         int ret, i;
 409
 410         for (i = 1; cmd->name; cmd++, i++) {
 411                 char *perms = cmd_perms_itohuman(cmd->perms);
 412                 ret = sc_send_va_buffer(scc, "%s\t%s\t%s\t%s\n", cmd->name,
 413                         handler,
 414                         perms,
 415                         cmd->description);
 416                 free(perms);
 417                 if (ret < 0)
 418                         return ret;
 419         }
 420         return 1;
 421 }
 422
 423 /* returns string that must be freed by the caller */
 424 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 425 {
 426         struct server_command *cmd;
 427
 428         for (cmd = server_cmds; cmd->name; cmd++)
 429                 if (!strcmp(cmd->name, name)) {
 430                         if (handler)
 431                                 *handler = para_strdup("server"); /* server commands */
 432                         return cmd;
 433                 }
 434         /* not found, look for commands supported by afs */
 435         for (cmd = afs_cmds; cmd->name; cmd++)
 436                 if (!strcmp(cmd->name, name)) {
 437                         if (handler)
 438                                 *handler = para_strdup("afs");
 439                         return cmd;
 440                 }
 441         return NULL;
 442 }
 443
 444 /* help */
 445 int com_help(struct stream_cipher_context *scc, int argc, char * const * argv)
 446 {
 447         struct server_command *cmd;
 448         char *perms, *handler;
 449         int ret;
 450
 451         if (argc < 2) {
 452                 /* no argument given, print list of commands */
 453                 if ((ret = send_list_of_commands(scc, server_cmds, "server")) < 0)
 454                         return ret;
 455                 return send_list_of_commands(scc, afs_cmds, "afs");
 456         }
 457         /* argument given for help */
 458         cmd = get_cmd_ptr(argv[1], &handler);
 459         if (!cmd)
 460                 return -E_BAD_CMD;
 461         perms = cmd_perms_itohuman(cmd->perms);
 462         ret = sc_send_va_buffer(scc,
 463                 "%s - %s\n\n"
 464                 "handler: %s\n"
 465                 "permissions: %s\n"
 466                 "usage: %s\n\n"
 467                 "%s\n",
 468                 argv[1],
 469                 cmd->description,
 470                 handler,
 471                 perms,
 472                 cmd->usage,
 473                 cmd->help
 474         );
 475         free(perms);
 476         free(handler);
 477         return ret;
 478 }
 479
 480 /* hup */
 481 int com_hup(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 482 {
 483         if (argc != 1)
 484                 return -E_COMMAND_SYNTAX;
 485         kill(getppid(), SIGHUP);
 486         return 1;
 487 }
 488
 489 /* term */
 490 int com_term(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 491 {
 492         if (argc != 1)
 493                 return -E_COMMAND_SYNTAX;
 494         kill(getppid(), SIGTERM);
 495         return 1;
 496 }
 497
 498 int com_play(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 499 {
 500         if (argc != 1)
 501                 return -E_COMMAND_SYNTAX;
 502         mutex_lock(mmd_mutex);
 503         mmd->new_vss_status_flags |= VSS_PLAYING;
 504         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 505         mutex_unlock(mmd_mutex);
 506         return 1;
 507
 508 }
 509
 510 /* stop */
 511 int com_stop(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 512 {
 513         if (argc != 1)
 514                 return -E_COMMAND_SYNTAX;
 515         mutex_lock(mmd_mutex);
 516         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 517         mmd->new_vss_status_flags &= ~VSS_REPOS;
 518         mmd->new_vss_status_flags |= VSS_NEXT;
 519         mutex_unlock(mmd_mutex);
 520         return 1;
 521 }
 522
 523 /* pause */
 524 int com_pause(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 525 {
 526         if (argc != 1)
 527                 return -E_COMMAND_SYNTAX;
 528         mutex_lock(mmd_mutex);
 529         if (!vss_paused() && !vss_stopped()) {
 530                 mmd->events++;
 531                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 532                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 533         }
 534         mutex_unlock(mmd_mutex);
 535         return 1;
 536 }
 537
 538 /* next */
 539 int com_next(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 540 {
 541         if (argc != 1)
 542                 return -E_COMMAND_SYNTAX;
 543         mutex_lock(mmd_mutex);
 544         mmd->events++;
 545         mmd->new_vss_status_flags |= VSS_NEXT;
 546         mutex_unlock(mmd_mutex);
 547         return 1;
 548 }
 549
 550 /* nomore */
 551 int com_nomore(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 552 {
 553         if (argc != 1)
 554                 return -E_COMMAND_SYNTAX;
 555         mutex_lock(mmd_mutex);
 556         if (vss_playing() || vss_paused())
 557                 mmd->new_vss_status_flags |= VSS_NOMORE;
 558         mutex_unlock(mmd_mutex);
 559         return 1;
 560 }
 561
 562 /* ff */
 563 int com_ff(__a_unused struct stream_cipher_context *scc, int argc, char * const * argv)
 564 {
 565         long promille;
 566         int ret, backwards = 0;
 567         unsigned i;
 568         char c;
 569
 570         if (argc != 2)
 571                 return -E_COMMAND_SYNTAX;
 572         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 573                 return -E_COMMAND_SYNTAX;
 574         if (ret > 1 && c == '-')
 575                 backwards = 1; /* jmp backwards */
 576         mutex_lock(mmd_mutex);
 577         ret = -E_NO_AUDIO_FILE;
 578         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 579                 goto out;
 580         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 581         if (backwards)
 582                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 583         else
 584                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 585         if (promille < 0)
 586                 promille = 0;
 587         if (promille >  1000) {
 588                 mmd->new_vss_status_flags |= VSS_NEXT;
 589                 goto out;
 590         }
 591         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 592         mmd->new_vss_status_flags |= VSS_REPOS;
 593         mmd->new_vss_status_flags &= ~VSS_NEXT;
 594         mmd->events++;
 595         ret = 1;
 596 out:
 597         mutex_unlock(mmd_mutex);
 598         return ret;
 599 }
 600
 601 /* jmp */
 602 int com_jmp(__a_unused struct stream_cipher_context *scc, int argc, char * const * argv)
 603 {
 604         long unsigned int i;
 605         int ret;
 606
 607         if (argc != 2)
 608                 return -E_COMMAND_SYNTAX;
 609         if (sscanf(argv[1], "%lu", &i) <= 0)
 610                 return -E_COMMAND_SYNTAX;
 611         mutex_lock(mmd_mutex);
 612         ret = -E_NO_AUDIO_FILE;
 613         if (!mmd->afd.afhi.chunks_total)
 614                 goto out;
 615         if (i > 100)
 616                 i = 100;
 617         PARA_INFO_LOG("jumping to %lu%%\n", i);
 618         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 619         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 620                 mmd->chunks_sent, mmd->offset);
 621         mmd->new_vss_status_flags |= VSS_REPOS;
 622         mmd->new_vss_status_flags &= ~VSS_NEXT;
 623         ret = 1;
 624         mmd->events++;
 625 out:
 626         mutex_unlock(mmd_mutex);
 627         return ret;
 628 }
 629
 630 /*
 631  * check if perms are sufficient to exec a command having perms cmd_perms.
 632  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 633  */
 634 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 635 {
 636         PARA_DEBUG_LOG("checking permissions\n");
 637         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 638 }
 639
 640 /*
 641  * Parse first string from *cmd and lookup in table of valid commands.
 642  * On error, NULL is returned.
 643  */
 644 static struct server_command *parse_cmd(const char *cmdstr)
 645 {
 646         char buf[255];
 647         int n = 0;
 648
 649         sscanf(cmdstr, "%200s%n", buf, &n);
 650         if (!n)
 651                 return NULL;
 652         buf[n] = '\0';
 653         return get_cmd_ptr(buf, NULL);
 654 }
 655
 656 static int read_command(struct stream_cipher_context *scc, char **result)
 657 {
 658         int ret;
 659         char buf[4096];
 660         char *command = NULL;
 661
 662         for (;;) {
 663                 size_t numbytes;
 664                 char *p;
 665
 666                 ret = sc_recv_buffer(scc, buf, sizeof(buf));
 667                 if (ret < 0)
 668                         goto out;
 669                 if (!ret)
 670                         break;
 671                 numbytes = ret;
 672                 ret = -E_COMMAND_SYNTAX;
 673                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 674                         goto out;
 675                 command = para_strcat(command, buf);
 676                 p = strstr(command, EOC_MSG);
 677                 if (p) {
 678                         *p = '\0';
 679                         break;
 680                 }
 681         }
 682         ret = command? 1 : -E_COMMAND_SYNTAX;
 683 out:
 684         if (ret < 0)
 685                 free(command);
 686         else
 687                 *result = command;
 688         return ret;
 689
 690 }
 691
 692 static void reset_signals(void)
 693 {
 694         para_sigaction(SIGCHLD, SIG_IGN);
 695         para_sigaction(SIGINT, SIG_DFL);
 696         para_sigaction(SIGTERM, SIG_DFL);
 697         para_sigaction(SIGHUP, SIG_DFL);
 698 }
 699
 700 /**
 701  * Perform user authentication and execute a command.
 702  *
 703  * \param fd The file descriptor to send output to.
 704  * \param peername Identifies the connecting peer.
 705  *
 706  * Whenever para_server accepts an incoming tcp connection on
 707  * the port it listens on, it forks and the resulting child
 708  * calls this function.
 709  *
 710  * An RSA-based challenge/response is used to authenticate
 711  * the peer. It that authentication succeeds, a random
 712  * session key is generated and sent back to the peer,
 713  * encrypted with its RSA public key.  From this point on,
 714  * all transfers are crypted with this session key.
 715  *
 716  * Next it is checked if the peer supplied  a valid server command or a command
 717  * for the audio file selector.  If yes, and if the user has sufficient
 718  * permissions to execute that command, the function calls the corresponding
 719  * command handler which does argument checking and further processing.
 720  *
 721  * In order to cope with a DOS attacks, a timeout is set up
 722  * which terminates the function if the connection was not
 723  * authenticated when the timeout expires.
 724  *
 725  * \sa alarm(2), crypt.c, crypt.h
 726  */
 727 __noreturn void handle_connect(int fd, const char *peername)
 728 {
 729         int ret, argc;
 730         char buf[4096];
 731         unsigned char rand_buf[CHALLENGE_SIZE + 2 * SESSION_KEY_LEN];
 732         unsigned char challenge_hash[HASH_SIZE];
 733         struct user *u;
 734         struct server_command *cmd = NULL;
 735         char **argv = NULL;
 736         char *p, *command = NULL;
 737         size_t numbytes;
 738         struct stream_cipher_context scc = {.fd = fd};
 739
 740         reset_signals();
 741         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 742         ret = mark_fd_blocking(fd);
 743         if (ret < 0)
 744                 goto net_err;
 745         /* send Welcome message */
 746         ret = send_va_buffer(fd, "This is para_server, version "
 747                 PACKAGE_VERSION  ".\n" );
 748         if (ret < 0)
 749                 goto net_err;
 750         /* recv auth request line */
 751         ret = recv_buffer(fd, buf, sizeof(buf));
 752         if (ret < 0)
 753                 goto net_err;
 754         if (ret < 10) {
 755                 ret = -E_AUTH_REQUEST;
 756                 goto net_err;
 757         }
 758         numbytes = ret;
 759         ret = -E_AUTH_REQUEST;
 760         if (strncmp(buf, AUTH_REQUEST_MSG, strlen(AUTH_REQUEST_MSG)))
 761                 goto net_err;
 762         p = buf + strlen(AUTH_REQUEST_MSG);
 763         PARA_DEBUG_LOG("received auth request for user %s\n", p);
 764         ret = -E_BAD_USER;
 765         u = lookup_user(p);
 766         if (u) {
 767                 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
 768                 ret = pub_encrypt(u->pubkey, rand_buf, sizeof(rand_buf),
 769                         (unsigned char *)buf);
 770                 if (ret < 0)
 771                         goto net_err;
 772                 numbytes = ret;
 773         } else {
 774                 /*
 775                  * We don't want to reveal our user names, so we send a
 776                  * challenge to the client even if the user does not exist, and
 777                  * fail the authentication later.
 778                  */
 779                 numbytes = 256;
 780                 get_random_bytes_or_die((unsigned char *)buf, numbytes);
 781         }
 782         PARA_DEBUG_LOG("sending %u byte challenge + rc4 keys (%zu bytes)\n",
 783                 CHALLENGE_SIZE, numbytes);
 784         ret = send_bin_buffer(fd, buf, numbytes);
 785         if (ret < 0)
 786                 goto net_err;
 787         /* recv challenge response */
 788         ret = recv_bin_buffer(fd, buf, HASH_SIZE);
 789         if (ret < 0)
 790                 goto net_err;
 791         numbytes = ret;
 792         PARA_DEBUG_LOG("received %d bytes challenge response\n", ret);
 793         ret = -E_BAD_USER;
 794         if (!u)
 795                 goto net_err;
 796         /*
 797          * The correct response is the hash of the first CHALLENGE_SIZE bytes
 798          * of the random data.
 799          */
 800         ret = -E_BAD_AUTH;
 801         if (numbytes != HASH_SIZE)
 802                 goto net_err;
 803         hash_function((char *)rand_buf, CHALLENGE_SIZE, challenge_hash);
 804         if (memcmp(challenge_hash, buf, HASH_SIZE))
 805                 goto net_err;
 806         /* auth successful */
 807         alarm(0);
 808         PARA_INFO_LOG("good auth for %s\n", u->name);
 809         /* init stream cipher keys with the second part of the random buffer */
 810         scc.recv = sc_new(rand_buf + CHALLENGE_SIZE, SESSION_KEY_LEN);
 811         scc.send = sc_new(rand_buf + CHALLENGE_SIZE + SESSION_KEY_LEN, SESSION_KEY_LEN);
 812         ret = sc_send_buffer(&scc, PROCEED_MSG);
 813         if (ret < 0)
 814                 goto net_err;
 815         ret = read_command(&scc, &command);
 816         if (ret == -E_COMMAND_SYNTAX)
 817                 goto err_out;
 818         if (ret < 0)
 819                 goto net_err;
 820         ret = -E_BAD_CMD;
 821         cmd = parse_cmd(command);
 822         if (!cmd)
 823                 goto err_out;
 824         /* valid command, check permissions */
 825         ret = check_perms(u->perms, cmd);
 826         if (ret < 0)
 827                 goto err_out;
 828         /* valid command and sufficient perms */
 829         ret = create_argv(command, "\n", &argv);
 830         if (ret < 0)
 831                 goto err_out;
 832         argc = ret;
 833         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 834                         peername);
 835         ret = cmd->handler(&scc, argc, argv);
 836         free_argv(argv);
 837         mutex_lock(mmd_mutex);
 838         mmd->num_commands++;
 839         mutex_unlock(mmd_mutex);
 840         if (ret >= 0)
 841                 goto out;
 842 err_out:
 843         sc_send_va_buffer(&scc, "%s\n", para_strerror(-ret));
 844 net_err:
 845         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 846 out:
 847         free(command);
 848         sc_free(scc.recv);
 849         sc_free(scc.send);
 850         mutex_lock(mmd_mutex);
 851         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 852                 mmd->events++;
 853         mmd->active_connections--;
 854         mutex_unlock(mmd_mutex);
 855         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 856 }