command.c

   1 /*
   2  * Copyright (C) 1997-2007 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file command.c does client authentication and executes server commands */
   8
   9 #include <signal.h>
  10 #include <sys/time.h>
  11 #include <sys/types.h>
  12 #include <dirent.h>
  13 #include <openssl/rc4.h>
  14
  15 #include "para.h"
  16 #include "error.h"
  17 #include "server.cmdline.h"
  18 #include "string.h"
  19 #include "afh.h"
  20 #include "afs.h"
  21 #include "server.h"
  22 #include "vss.h"
  23 #include "send.h"
  24 #include "rc4.h"
  25 #include "net.h"
  26 #include "daemon.h"
  27 #include "fd.h"
  28 #include "list.h"
  29 #include "user_list.h"
  30 #include "server_command_list.h"
  31 #include "afs_command_list.h"
  32
  33 /** commands including options must be shorter than this */
  34 #define MAX_COMMAND_LEN 32768
  35
  36 static RC4_KEY rc4_recv_key;
  37 static RC4_KEY rc4_send_key;
  38 static unsigned char rc4_buf[2 * RC4_KEY_LEN];
  39
  40 extern const char *status_item_list[NUM_STAT_ITEMS];
  41 extern struct misc_meta_data *mmd;
  42 extern struct sender senders[];
  43
  44 static void dummy(__a_unused int s)
  45 {}
  46
  47 static void mmd_dup(struct misc_meta_data *new_mmd)
  48 {
  49         mmd_lock();
  50         *new_mmd = *mmd;
  51         mmd_unlock();
  52 }
  53
  54 /*
  55  * compute human readable string containing
  56  * vss status for given integer value
  57  */
  58 static char *vss_status_tohuman(unsigned int flags)
  59 {
  60         if (flags & VSS_PLAYING)
  61                 return para_strdup("playing");
  62         else if (flags & VSS_NEXT)
  63                 return para_strdup("stopped");
  64         else
  65                 return para_strdup("paused");
  66 }
  67
  68 /*
  69  * return human readable permission string. Never returns NULL.
  70  */
  71 static char *cmd_perms_itohuman(unsigned int perms)
  72 {
  73         char *msg = para_malloc(5 * sizeof(char));
  74
  75         msg[0] = perms & AFS_READ? 'a' : '-';
  76         msg[1] = perms & AFS_WRITE? 'A' : '-';
  77         msg[2] = perms & VSS_READ? 'v' : '-';
  78         msg[3] = perms & VSS_WRITE? 'V' : '-';
  79         msg[4] = '\0';
  80         return msg;
  81 }
  82
  83 /*
  84  * Never returns NULL.
  85  */
  86 static char *vss_get_status_flags(unsigned int flags)
  87 {
  88         char *msg = para_malloc(5 * sizeof(char));
  89
  90         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
  91         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
  92         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
  93         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
  94         msg[4] = '\0';
  95         return msg;
  96 }
  97
  98 /*
  99  * compute status bar string. Never returns NULL
 100  */
 101 static char *get_sb_string(struct misc_meta_data *nmmd)
 102 {
 103         char *base, *ret;
 104         long long unsigned secs = 0, rsecs = 0, percent = 0;
 105
 106         base = para_basename(nmmd->filename);
 107         if (!base)
 108                 return para_strdup("");
 109         if (!base[0])
 110                 return base;
 111         if (nmmd->afi.chunks_total) {
 112                 secs = (long long) nmmd->afi.seconds_total * nmmd->chunks_sent
 113                         / nmmd->afi.chunks_total;
 114                 rsecs = (long long) nmmd->afi.seconds_total *
 115                         (nmmd->afi.chunks_total - nmmd->chunks_sent)
 116                         / nmmd->afi.chunks_total;
 117                 percent = 100 * ((nmmd->chunks_sent + 5) / 10)
 118                         / ((nmmd->afi.chunks_total + 5) / 10);
 119         }
 120         ret = make_message("%llu:%02llu [%llu:%02llu] (%llu%%) %s",
 121                 secs / 60, secs % 60,
 122                 rsecs / 60, rsecs % 60,
 123                 percent,
 124                 base
 125         );
 126         free(base);
 127         return ret;
 128 }
 129
 130 static char *get_status(struct misc_meta_data *nmmd)
 131 {
 132         char *bar, *ret, mtime[30] = "";
 133         char *status, *flags; /* vss status info */
 134         char *ut = uptime_str();
 135         long offset = (nmmd->offset + 500) / 1000;
 136         struct timeval now;
 137         struct tm mtime_tm;
 138
 139         if (nmmd->audio_format >= 0) {
 140                 localtime_r(&nmmd->mtime, &mtime_tm);
 141                 strftime(mtime, 29, "%a %b %d %Y", &mtime_tm);
 142         }
 143         /* report real status */
 144         status = vss_status_tohuman(nmmd->vss_status_flags);
 145         flags = vss_get_status_flags(nmmd->vss_status_flags);
 146         bar = para_basename(nmmd->filename);
 147         gettimeofday(&now, NULL);
 148         ret = make_message(
 149                 "%s:%zu\n"      "%s:%s\n"               "%s:%lu\n"      "%s:%u\n"
 150                 "%s:%s\n"       "%s:%s\n"       "%s:%s\n"       "%s:%s\n"
 151                 "%s:%li\n"      "%s:%s\n"       "%s"
 152                 "%s:%s\n"       "%s:%lu.%lu\n"  "%s:%lu.%lu\n",
 153                 status_item_list[SI_FILE_SIZE], nmmd->size / 1024,
 154                 status_item_list[SI_MTIME], mtime,
 155                 status_item_list[SI_LENGTH], nmmd->afi.seconds_total,
 156                 status_item_list[SI_NUM_PLAYED], nmmd->num_played,
 157
 158                 status_item_list[SI_STATUS_BAR], bar ? bar : "(none)",
 159                 status_item_list[SI_STATUS], status,
 160                 status_item_list[SI_STATUS_FLAGS], flags,
 161                 status_item_list[SI_SELECTOR], "FIXME",
 162
 163                 status_item_list[SI_OFFSET], offset,
 164                 status_item_list[SI_FORMAT], audio_format_name(nmmd->audio_format),
 165                 nmmd->afi.info_string,
 166
 167                 status_item_list[SI_UPTIME], ut,
 168                 status_item_list[SI_STREAM_START],
 169                         (long unsigned)nmmd->stream_start.tv_sec,
 170                         (long unsigned)nmmd->stream_start.tv_usec,
 171                 status_item_list[SI_CURRENT_TIME],
 172                         (long unsigned)now.tv_sec,
 173                         (long unsigned)now.tv_usec
 174
 175         );
 176         free(bar);
 177         free(flags);
 178         free(status);
 179         free(ut);
 180         return ret;
 181 }
 182
 183 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 184 {
 185         int i;
 186         /* this has to match sender.h */
 187         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 188
 189         scd->sender_num = -1;
 190         if (argc < 2)
 191                 return -E_COMMAND_SYNTAX;
 192         for (i = 0; senders[i].name; i++)
 193                 if (!strcmp(senders[i].name, argv[1]))
 194                         break;
 195         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 196         if (!senders[i].name)
 197                 return -E_COMMAND_SYNTAX;
 198         scd->sender_num = i;
 199         for (i = 0; subcmds[i]; i++)
 200                 if (!strcmp(subcmds[i], argv[2]))
 201                         break;
 202         if (!subcmds[i])
 203                 return -E_COMMAND_SYNTAX;
 204         scd->cmd_num = i;
 205         mmd_lock();
 206         if (!senders[scd->sender_num].client_cmds[scd->cmd_num]) {
 207                 mmd_unlock();
 208                 return -E_SENDER_CMD;
 209         }
 210         mmd_unlock();
 211         switch (scd->cmd_num) {
 212         case SENDER_ON:
 213         case SENDER_OFF:
 214                 if (argc != 3)
 215                         return -E_COMMAND_SYNTAX;
 216                 break;
 217         case SENDER_DENY:
 218         case SENDER_ALLOW:
 219                 if (argc != 4 && argc != 5)
 220                         return -E_COMMAND_SYNTAX;
 221                 if (!inet_pton(AF_INET, argv[3], &scd->addr))
 222                         return -E_COMMAND_SYNTAX;
 223                 scd->netmask = 32;
 224                 if (argc == 5) {
 225                         scd->netmask = atoi(argv[4]);
 226                         if (scd->netmask < 0 || scd->netmask > 32)
 227                                 return -E_COMMAND_SYNTAX;
 228                 }
 229                 break;
 230         case SENDER_ADD:
 231         case SENDER_DELETE:
 232                 if (argc != 4 && argc != 5)
 233                         return -E_COMMAND_SYNTAX;
 234                 if (!inet_pton(AF_INET, argv[3], &scd->addr))
 235                         return -E_COMMAND_SYNTAX;
 236                 scd->port = -1;
 237                 if (argc == 5) {
 238                         scd->port = atoi(argv[4]);
 239                         if (scd->port < 0 || scd->port > 65535)
 240                                 return -E_COMMAND_SYNTAX;
 241                 }
 242                 break;
 243         default:
 244                 return -E_COMMAND_SYNTAX;
 245         }
 246         return 1;
 247 }
 248
 249 int com_sender(int fd, int argc, char * const * argv)
 250 {
 251         int i, ret;
 252         struct sender_command_data scd;
 253
 254         if (argc < 2) {
 255                 char *msg = NULL;
 256                 for (i = 0; senders[i].name; i++) {
 257                         char *tmp = make_message("%s%s\n",
 258                                 msg? msg : "", senders[i].name);
 259                         free(msg);
 260                         msg = tmp;
 261                 }
 262                 ret = send_buffer(fd, msg);
 263                 free(msg);
 264                 return ret;
 265         }
 266         ret = check_sender_args(argc, argv, &scd);
 267         if (ret < 0) {
 268                 char *msg;
 269                 if (scd.sender_num < 0)
 270                         return ret;
 271                 msg = senders[scd.sender_num].help();
 272                 send_buffer(fd, msg);
 273                 free(msg);
 274                 return 1;
 275         }
 276         for (i = 0; i < 10; i++) {
 277                 mmd_lock();
 278                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 279                         mmd_unlock();
 280                         usleep(100 * 1000);
 281                         continue;
 282                 }
 283                 mmd->sender_cmd_data = scd;
 284                 mmd_unlock();
 285                 break;
 286         }
 287         return (i < 10)? 1 : -E_LOCK;
 288 }
 289
 290 /* server info */
 291 int com_si(int fd, int argc, __a_unused char * const * argv)
 292 {
 293         int i, ret;
 294         char *ut;
 295         char *sender_info = NULL, *sender_list = NULL;
 296
 297         if (argc != 1)
 298                 return -E_COMMAND_SYNTAX;
 299         mmd_lock();
 300         for (i = 0; senders[i].name; i++) {
 301                 char *info = senders[i].info();
 302                 sender_info = para_strcat(sender_info, info);
 303                 free(info);
 304                 sender_list = para_strcat(sender_list, senders[i].name);
 305                 sender_list = para_strcat(sender_list, " ");
 306         }
 307         ut = uptime_str();
 308         ret = send_va_buffer(fd, "up: %s\nplayed: %u\n"
 309                 "pid: %d\n"
 310                 "connections (active/accepted/total): %u/%u/%u\n"
 311                 "current loglevel: %i\n"
 312                 "supported audio formats: %s\n"
 313                 "supported senders: %s\n"
 314                 "%s",
 315                 ut, mmd->num_played,
 316                 getppid(),
 317                 mmd->active_connections,
 318                 mmd->num_commands,
 319                 mmd->num_connects,
 320                 conf.loglevel_arg,
 321                 supported_audio_formats(),
 322                 sender_list,
 323                 sender_info
 324         );
 325         mmd_unlock();
 326         free(ut);
 327         free(sender_list);
 328         free(sender_info);
 329         return ret;
 330 }
 331
 332 /* version */
 333 int com_version(int fd, int argc, __a_unused char * const * argv)
 334 {
 335         if (argc != 1)
 336                 return -E_COMMAND_SYNTAX;
 337         return send_buffer(fd, VERSION_TEXT("server")
 338                 "built: " BUILD_DATE "\n"
 339                 SYSTEM ", " CC_VERSION "\n"
 340         );
 341 }
 342
 343 /* sc */
 344 int com_sc(int fd, int argc, char * const * argv)
 345 {
 346         char *name = NULL;
 347         int ret, old = 0, count = -1; /* print af change forever */
 348
 349         if (argc > 1)
 350                 count = atoi(argv[1]);
 351 repeat:
 352         mmd_lock();
 353         if (old != mmd->num_played) {
 354                 old = mmd->num_played;
 355                 name = para_strdup(mmd->filename);
 356         }
 357         mmd_unlock();
 358         if (name) {
 359                 ret = send_va_buffer(fd, "%s\n", name);
 360                 free(name);
 361                 name = NULL;
 362                 if (ret < 0)
 363                         return ret;
 364                 if (argc > 1 && !--count)
 365                         return 1;
 366         }
 367         usleep(500000);
 368         goto repeat;
 369 }
 370
 371 /* sb */
 372 int com_sb(int fd, int argc, char * const * argv)
 373 {
 374         char *sb;
 375         int ret, nr = -1;       /* status bar will be printed that many
 376                                  * times. Negative value means: print
 377                                  * forever
 378                                  */
 379         if (argc > 1)
 380                 nr = atoi(argv[1]);
 381         while (nr) {
 382                 mmd_lock();
 383                 sb = get_sb_string(mmd);
 384                 mmd_unlock();
 385                 ret = send_va_buffer(fd, "%s\n", sb);
 386                 free(sb);
 387                 if (ret < 0)
 388                         return ret;
 389                 if (nr == 1)
 390                         return 1;
 391                 usleep(500000);
 392                 if (nr > 0)
 393                         nr--;
 394         }
 395         return 1;
 396 }
 397
 398 /* stat */
 399 int com_stat(int fd, int argc, char * const * argv)
 400 {
 401         int ret, num = 0;/* status will be printed that many
 402                           * times. num <= 0 means: print forever
 403                           */
 404         struct misc_meta_data tmp, *nmmd = &tmp;
 405         char *s;
 406
 407         signal(SIGUSR1, dummy);
 408
 409         if (argc > 1)
 410                 num = atoi(argv[1]);
 411         for (;;) {
 412
 413                 mmd_dup(nmmd);
 414                 s = get_status(nmmd);
 415                 ret = send_buffer(fd, s);
 416                 free(s);
 417                 if (ret < 0)
 418                         goto out;
 419                 ret = 1;
 420                 if (num == 1)
 421                         goto out;
 422                 sleep(50);
 423                 if (getppid() == 1)
 424                         return -E_SERVER_CRASH;
 425         }
 426 out:
 427         return ret;
 428 }
 429
 430 static int send_list_of_commands(int fd, struct server_command *cmd,
 431                 const char *handler)
 432 {
 433         int ret, i;
 434
 435         for (i = 1; cmd->name; cmd++, i++) {
 436                 char *perms = cmd_perms_itohuman(cmd->perms);
 437                 ret = send_va_buffer(fd, "%s\t%s\t%s\t%s\n", cmd->name,
 438                         handler,
 439                         perms,
 440                         cmd->description);
 441                 free(perms);
 442                 if (ret < 0)
 443                         return ret;
 444         }
 445         return 1;
 446 }
 447
 448 /* always returns string that must be freed by the caller in handler */
 449 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 450 {
 451         struct server_command *cmd;
 452
 453         for (cmd = server_cmds; cmd->name; cmd++)
 454                 if (!strcmp(cmd->name, name)) {
 455                         if (handler)
 456                                 *handler = para_strdup("para_server"); /* server commands */
 457                         return cmd;
 458                 }
 459         /* not found, look for commands supported by afs */
 460         for (cmd = afs_cmds; cmd->name; cmd++)
 461                 if (!strcmp(cmd->name, name))
 462                         return cmd;
 463         return NULL;
 464 }
 465
 466 /* help */
 467 int com_help(int fd, int argc, char * const * argv)
 468 {
 469         struct server_command *cmd;
 470         char *perms, *handler;
 471         int ret;
 472
 473         if (argc < 2) {
 474                 /* no argument given, print list of commands */
 475                 if ((ret = send_list_of_commands(fd, server_cmds, "server")) < 0)
 476                         return ret;
 477                 return send_list_of_commands(fd, afs_cmds, "afs");
 478         }
 479         /* argument given for help */
 480         cmd = get_cmd_ptr(argv[1], &handler);
 481         if (!cmd) {
 482                 free(handler);
 483                 return -E_BAD_CMD;
 484         }
 485         perms = cmd_perms_itohuman(cmd->perms);
 486         ret = send_va_buffer(fd,
 487                 "%s - %s\n\n"
 488                 "handler: %s\n"
 489                 "permissions: %s\n"
 490                 "usage: %s\n\n"
 491                 "%s\n",
 492                 argv[1],
 493                 cmd->description,
 494                 handler,
 495                 perms,
 496                 cmd->usage,
 497                 cmd->help
 498         );
 499         free(perms);
 500         free(handler);
 501         return ret;
 502 }
 503
 504 /* hup */
 505 int com_hup(__a_unused int fd, int argc, __a_unused char * const * argv)
 506 {
 507         if (argc != 1)
 508                 return -E_COMMAND_SYNTAX;
 509         kill(getppid(), SIGHUP);
 510         return 1;
 511 }
 512
 513 /* term */
 514 int com_term(__a_unused int fd, int argc, __a_unused char * const * argv)
 515 {
 516         if (argc != 1)
 517                 return -E_COMMAND_SYNTAX;
 518         kill(getppid(), SIGTERM);
 519         return 1;
 520 }
 521
 522 int com_play(__a_unused int fd, int argc, __a_unused char * const * argv)
 523 {
 524         if (argc != 1)
 525                 return -E_COMMAND_SYNTAX;
 526         mmd_lock();
 527         mmd->new_vss_status_flags |= VSS_PLAYING;
 528         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 529         mmd_unlock();
 530         return 1;
 531
 532 }
 533
 534 /* stop */
 535 int com_stop(__a_unused int fd, int argc, __a_unused char * const * argv)
 536 {
 537         if (argc != 1)
 538                 return -E_COMMAND_SYNTAX;
 539         mmd_lock();
 540         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 541         mmd->new_vss_status_flags &= ~VSS_REPOS;
 542         mmd->new_vss_status_flags |= VSS_NEXT;
 543         mmd_unlock();
 544         return 1;
 545 }
 546
 547 /* pause */
 548 int com_pause(__a_unused int fd, int argc, __a_unused char * const * argv)
 549 {
 550         if (argc != 1)
 551                 return -E_COMMAND_SYNTAX;
 552         mmd_lock();
 553         if (!vss_paused())
 554                 mmd->events++;
 555         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 556         mmd->new_vss_status_flags &= ~VSS_NEXT;
 557         mmd_unlock();
 558         return 1;
 559 }
 560
 561 /* next */
 562 int com_next(__a_unused int fd, int argc, __a_unused char * const * argv)
 563 {
 564         if (argc != 1)
 565                 return -E_COMMAND_SYNTAX;
 566         mmd_lock();
 567         mmd->events++;
 568         mmd->new_vss_status_flags |= VSS_NEXT;
 569         mmd_unlock();
 570         return 1;
 571 }
 572
 573 /* nomore */
 574 int com_nomore(__a_unused int fd, int argc, __a_unused char * const * argv)
 575 {
 576         if (argc != 1)
 577                 return -E_COMMAND_SYNTAX;
 578         mmd_lock();
 579         if (vss_playing() || vss_paused())
 580                 mmd->new_vss_status_flags |= VSS_NOMORE;
 581         mmd_unlock();
 582         return 1;
 583 }
 584
 585 /* ff */
 586 int com_ff(__a_unused int fd, int argc, char * const * argv)
 587 {
 588         long promille;
 589         int ret, backwards = 0;
 590         unsigned i;
 591         char c;
 592
 593         if (argc != 2)
 594                 return -E_COMMAND_SYNTAX;
 595         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 596                 return -E_COMMAND_SYNTAX;
 597         if (ret > 1 && c == '-')
 598                 backwards = 1; /* jmp backwards */
 599         mmd_lock();
 600         ret = -E_NO_AUDIO_FILE;
 601         if (!mmd->afi.chunks_total || !mmd->afi.seconds_total)
 602                 goto out;
 603         promille = (1000 * mmd->current_chunk) / mmd->afi.chunks_total;
 604         if (backwards)
 605                 promille -= 1000 * i / mmd->afi.seconds_total;
 606         else
 607                 promille += 1000 * i / mmd->afi.seconds_total;
 608         if (promille < 0)
 609                 promille = 0;
 610         if (promille >  1000) {
 611                 mmd->new_vss_status_flags |= VSS_NEXT;
 612                 goto out;
 613         }
 614         mmd->repos_request = (mmd->afi.chunks_total * promille) / 1000;
 615         mmd->new_vss_status_flags |= VSS_REPOS;
 616         mmd->new_vss_status_flags &= ~VSS_NEXT;
 617         mmd->events++;
 618         ret = 1;
 619 out:
 620         mmd_unlock();
 621         return ret;
 622 }
 623
 624 /* jmp */
 625 int com_jmp(__a_unused int fd, int argc, char * const * argv)
 626 {
 627         long unsigned int i;
 628         int ret;
 629
 630         if (argc != 2)
 631                 return -E_COMMAND_SYNTAX;
 632         if (sscanf(argv[1], "%lu", &i) <= 0)
 633                 return -E_COMMAND_SYNTAX;
 634         mmd_lock();
 635         ret = -E_NO_AUDIO_FILE;
 636         if (!mmd->afi.chunks_total)
 637                 goto out;
 638         if (i > 100)
 639                 i = 100;
 640         PARA_INFO_LOG("jumping to %lu%%\n", i);
 641         mmd->repos_request = (mmd->afi.chunks_total * i + 50)/ 100;
 642         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 643                 mmd->chunks_sent, mmd->offset);
 644         mmd->new_vss_status_flags |= VSS_REPOS;
 645         mmd->new_vss_status_flags &= ~VSS_NEXT;
 646         ret = 1;
 647         mmd->events++;
 648 out:
 649         mmd_unlock();
 650         return ret;
 651 }
 652
 653 /*
 654  * check if perms are sufficient to exec a command having perms cmd_perms.
 655  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 656  */
 657 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 658 {
 659         PARA_DEBUG_LOG("%s", "checking permissions\n");
 660         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 661 }
 662
 663 /*
 664  * Parse first string from *cmd and lookup in table of valid commands.
 665  * On error, NULL is returned.
 666  */
 667 static struct server_command *parse_cmd(const char *cmdstr)
 668 {
 669         char buf[255];
 670         int n = 0;
 671
 672         sscanf(cmdstr, "%200s%n", buf, &n);
 673         if (!n)
 674                 return NULL;
 675         buf[n] = '\0';
 676         return get_cmd_ptr(buf, NULL);
 677 }
 678
 679 static long int para_rand(long unsigned max)
 680 {
 681         return (long int) ((max + 0.0) * (random() / (RAND_MAX + 1.0)));
 682 }
 683
 684 static void init_rc4_keys(void)
 685 {
 686         int i;
 687
 688         for (i = 0; i < 2 * RC4_KEY_LEN; i++)
 689                 rc4_buf[i] = para_rand(256);
 690         PARA_DEBUG_LOG("rc4 keys initialized (%u:%u)\n",
 691                 (unsigned char) rc4_buf[0],
 692                 (unsigned char) rc4_buf[RC4_KEY_LEN]);
 693         RC4_set_key(&rc4_recv_key, RC4_KEY_LEN, rc4_buf);
 694         RC4_set_key(&rc4_send_key, RC4_KEY_LEN, rc4_buf + RC4_KEY_LEN);
 695 }
 696
 697 static void rc4_recv(unsigned long len, const unsigned char *indata,
 698                 unsigned char *outdata, __a_unused void *private_data)
 699 {
 700         RC4(&rc4_recv_key, len, indata, outdata);
 701 }
 702
 703 static void rc4_send(unsigned long len, const unsigned char *indata,
 704                 unsigned char *outdata, __a_unused void *private_data)
 705 {
 706         RC4(&rc4_send_key, len, indata, outdata);
 707 }
 708
 709 static int read_command(int fd, char **result)
 710 {
 711         int ret;
 712         char buf[4096];
 713         char *command = NULL;
 714
 715         for (;;) {
 716                 size_t numbytes;
 717                 char *p;
 718
 719                 ret = recv_buffer(fd, buf, sizeof(buf));
 720                 if (ret < 0)
 721                         goto out;
 722                 if (!ret)
 723                         break;
 724                 numbytes = ret;
 725                 ret = -E_COMMAND_SYNTAX;
 726                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 727                         goto out;
 728                 command = para_strcat(command, buf);
 729                 p = strstr(command, EOC_MSG);
 730                 if (p) {
 731                         *p = '\0';
 732                         break;
 733                 }
 734         }
 735         ret = command? 1 : -E_COMMAND_SYNTAX;
 736 out:
 737         if (ret < 0)
 738                 free(command);
 739         else
 740                 *result = command;
 741         return ret;
 742
 743 }
 744
 745 /**
 746  * perform user authentication and execute a command
 747  *
 748  * \param fd the file descriptor to send output to
 749  * \param addr socket address info of peer
 750  *
 751  * \return EXIT_SUCCESS or EXIT_FAILURE
 752  *
 753  * Whenever para_server accepts an incoming tcp connection on
 754  * the port it listens on, it forks and the resulting child
 755  * calls this function.
 756  *
 757  * An RSA-based challenge/response is used to authenticate
 758  * the peer. It that authentication succeeds, a random RC4
 759  * session key is generated and sent back to the peer,
 760  * encrypted with its RSA public key.  From this point on,
 761  * all transfers are crypted with this session key.
 762  *
 763  * Next it is checked if the peer supplied  a valid server command or a command
 764  * for the audio file selector.  If yes, and if the user has sufficient
 765  * permissions to execute that command, the function calls the corresponding
 766  * command handler which does argument checking and further processing.
 767  *
 768  * In order to cope with a DOS attacks, a timeout is set up
 769  * which terminates the function if the connection was not
 770  * authenticated when the timeout expires.
 771  *
 772  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 773  */
 774 int handle_connect(int fd, struct sockaddr_in *addr)
 775 {
 776         int ret, argc, use_rc4 = 0;
 777         char buf[4096];
 778         unsigned char crypt_buf[MAXLINE];
 779         struct user *u;
 780         struct server_command *cmd = NULL;
 781         long unsigned challenge_nr, chall_response;
 782         char **argv = NULL;
 783         char *p, *command = NULL;
 784         size_t numbytes;
 785
 786         signal(SIGCHLD, SIG_IGN);
 787         signal(SIGINT, SIG_DFL);
 788         signal(SIGTERM, SIG_DFL);
 789         signal(SIGHUP, SIG_DFL);
 790         signal(SIGUSR1, SIG_IGN);
 791
 792         challenge_nr = random();
 793         /* send Welcome message */
 794         ret = send_va_buffer(fd, "This is para_server, version "
 795                 PACKAGE_VERSION  ".\n" );
 796         if (ret < 0)
 797                 goto err_out;
 798         /* recv auth request line */
 799         ret = recv_buffer(fd, buf, sizeof(buf));
 800         if (ret < 0)
 801                 goto err_out;
 802         if (ret <= 6) {
 803                 ret = -E_AUTH;
 804                 goto err_out;
 805         }
 806         numbytes = ret;
 807         ret = -E_AUTH;
 808         if (strncmp(buf, "auth ", 5))
 809                 goto err_out;
 810
 811         if (numbytes < 9 || strncmp(buf, "auth rc4 ", 9))
 812                 p = buf + 5; /* client version < 0.2.6 */
 813         else {
 814                 p = buf + 9; /* client version >= 0.2.6 */
 815                 use_rc4 = 1;
 816         }
 817         PARA_DEBUG_LOG("received %s request for user %s\n",
 818                 use_rc4? "rc4" : "auth", p);
 819         ret = -E_BAD_USER;
 820         u = lookup_user(p);
 821         if (!u)
 822                 goto err_out;
 823         ret = para_encrypt_challenge(u->rsa, challenge_nr, crypt_buf);
 824         if (ret <= 0)
 825                 goto err_out;
 826         numbytes = ret;
 827         PARA_DEBUG_LOG("sending %zu byte challenge\n", numbytes);
 828         /* We can't use send_buffer here since buf may contain null bytes */
 829         ret = send_bin_buffer(fd,(char *) crypt_buf, numbytes);
 830         if (ret < 0)
 831                 goto err_out;
 832         /* recv decrypted number */
 833         ret = recv_buffer(fd, buf, sizeof(buf));
 834         if (ret < 0)
 835                 goto err_out;
 836         numbytes = ret;
 837         ret = -E_AUTH;
 838         if (!numbytes)
 839                 goto err_out;
 840         if (sscanf(buf, CHALLENGE_RESPONSE_MSG "%lu", &chall_response) < 1
 841                         || chall_response != challenge_nr)
 842                 goto err_out;
 843         /* auth successful, send 'Proceed' message */
 844         PARA_INFO_LOG("good auth for %s (%lu)\n", u->name, challenge_nr);
 845         sprintf(buf, "%s", PROCEED_MSG);
 846         if (use_rc4) {
 847                 init_rc4_keys();
 848                 ret = para_encrypt_buffer(u->rsa, rc4_buf, 2 * RC4_KEY_LEN,
 849                         (unsigned char *)buf + PROCEED_MSG_LEN + 1);
 850                 if (ret <= 0)
 851                         goto err_out;
 852                 numbytes = ret + strlen(PROCEED_MSG) + 1;
 853         } else
 854                 numbytes = strlen(buf);
 855         ret = send_bin_buffer(fd, buf, numbytes);
 856         if (ret < 0)
 857                 goto err_out;
 858         if (use_rc4)
 859                 enable_crypt(fd, rc4_recv, rc4_send, NULL);
 860         ret = read_command(fd, &command);
 861         if (ret < 0)
 862                 goto err_out;
 863         ret = -E_BAD_CMD;
 864         cmd = parse_cmd(command);
 865         if (!cmd)
 866                 goto err_out;
 867         /* valid command, check permissions */
 868         ret = check_perms(u->perms, cmd);
 869         if (ret < 0)
 870                 goto err_out;
 871         /* valid command and sufficient perms */
 872         alarm(0);
 873         argc = split_args(command, &argv, "\n");
 874         mmd_lock();
 875         mmd->num_commands++;
 876         mmd_unlock();
 877         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 878                 inet_ntoa(addr->sin_addr));
 879         ret = cmd->handler(fd, argc, argv);
 880         if (ret >= 0) {
 881                 ret = EXIT_SUCCESS;
 882                 goto out;
 883         }
 884 err_out:
 885         PARA_NOTICE_LOG("%s\n", PARA_STRERROR(-ret));
 886         if (ret != -E_SEND && ret != -E_RECV)
 887                 send_va_buffer(fd, "%s\n", PARA_STRERROR(-ret));
 888         ret = EXIT_FAILURE;
 889 out:
 890         free(command);
 891         free(argv);
 892         mmd_lock();
 893         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 894                 mmd->events++;
 895         mmd->active_connections--;
 896         mmd_unlock();
 897         return ret;
 898 }