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 "afs_common.h"
  19 #include "string.h"
  20 #include "afh.h"
  21 #include "afs.h"
  22 #include "server.h"
  23 #include "vss.h"
  24 #include "send.h"
  25 #include "rc4.h"
  26 #include "net.h"
  27 #include "daemon.h"
  28 #include "fd.h"
  29 #include "list.h"
  30 #include "user_list.h"
  31 #include "server_command_list.h"
  32 #include "afs_command_list.h"
  33
  34 /** commands including options must be shorter than this */
  35 #define MAX_COMMAND_LEN 32768
  36
  37 static RC4_KEY rc4_recv_key;
  38 static RC4_KEY rc4_send_key;
  39 static unsigned char rc4_buf[2 * RC4_KEY_LEN];
  40
  41 extern const char *status_item_list[NUM_STAT_ITEMS];
  42 extern struct misc_meta_data *mmd;
  43 extern struct sender senders[];
  44
  45 static void dummy(__a_unused int s)
  46 {}
  47
  48 static void mmd_dup(struct misc_meta_data *new_mmd)
  49 {
  50         mmd_lock();
  51         *new_mmd = *mmd;
  52         mmd_unlock();
  53 }
  54
  55 /*
  56  * compute human readable string containing
  57  * vss status for given integer value
  58  */
  59 static char *vss_status_tohuman(unsigned int flags)
  60 {
  61         if (flags & VSS_PLAYING)
  62                 return para_strdup("playing");
  63         else if (flags & VSS_NEXT)
  64                 return para_strdup("stopped");
  65         else
  66                 return para_strdup("paused");
  67 }
  68
  69 /*
  70  * return human readable permission string. Never returns NULL.
  71  */
  72 static char *cmd_perms_itohuman(unsigned int perms)
  73 {
  74         char *msg = para_malloc(5 * sizeof(char));
  75
  76         msg[0] = perms & AFS_READ? 'a' : '-';
  77         msg[1] = perms & AFS_WRITE? 'A' : '-';
  78         msg[2] = perms & VSS_READ? 'v' : '-';
  79         msg[3] = perms & VSS_WRITE? 'V' : '-';
  80         msg[4] = '\0';
  81         return msg;
  82 }
  83
  84 /*
  85  * Never returns NULL.
  86  */
  87 static char *vss_get_status_flags(unsigned int flags)
  88 {
  89         char *msg = para_malloc(5 * sizeof(char));
  90
  91         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
  92         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
  93         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
  94         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
  95         msg[4] = '\0';
  96         return msg;
  97 }
  98
  99 /*
 100  * compute status bar string. Never returns NULL
 101  */
 102 static char *get_sb_string(struct misc_meta_data *nmmd)
 103 {
 104         char *base, *ret;
 105         long long unsigned secs = 0, rsecs = 0, percent = 0;
 106
 107         base = para_basename(nmmd->filename);
 108         if (!base)
 109                 return para_strdup("");
 110         if (!base[0])
 111                 return base;
 112         if (nmmd->afi.chunks_total) {
 113                 secs = (long long) nmmd->afi.seconds_total * nmmd->chunks_sent
 114                         / nmmd->afi.chunks_total;
 115                 rsecs = (long long) nmmd->afi.seconds_total *
 116                         (nmmd->afi.chunks_total - nmmd->chunks_sent)
 117                         / nmmd->afi.chunks_total;
 118                 percent = 100 * ((nmmd->chunks_sent + 5) / 10)
 119                         / ((nmmd->afi.chunks_total + 5) / 10);
 120         }
 121         ret = make_message("%llu:%02llu [%llu:%02llu] (%llu%%) %s",
 122                 secs / 60, secs % 60,
 123                 rsecs / 60, rsecs % 60,
 124                 percent,
 125                 base
 126         );
 127         free(base);
 128         return ret;
 129 }
 130
 131 static char *get_status(struct misc_meta_data *nmmd)
 132 {
 133         char *bar, *ret, mtime[30] = "";
 134         char *status, *flags; /* vss status info */
 135         char *ut = uptime_str();
 136         long offset = (nmmd->offset + 500) / 1000;
 137         struct timeval now;
 138         struct tm mtime_tm;
 139
 140         if (nmmd->audio_format >= 0) {
 141                 localtime_r(&nmmd->mtime, &mtime_tm);
 142                 strftime(mtime, 29, "%a %b %d %Y", &mtime_tm);
 143         }
 144         /* report real status */
 145         status = vss_status_tohuman(nmmd->vss_status_flags);
 146         flags = vss_get_status_flags(nmmd->vss_status_flags);
 147         bar = para_basename(nmmd->filename);
 148         gettimeofday(&now, NULL);
 149         ret = make_message(
 150                 "%s:%zu\n"      "%s:%s\n"               "%s:%lu\n"      "%s:%u\n"
 151                 "%s:%s\n"       "%s:%s\n"       "%s:%s\n"       "%s:%s\n"
 152                 "%s:%li\n"      "%s:%s\n"       "%s"
 153                 "%s:%s\n"       "%s:%lu.%lu\n"  "%s:%lu.%lu\n",
 154                 status_item_list[SI_FILE_SIZE], nmmd->size / 1024,
 155                 status_item_list[SI_MTIME], mtime,
 156                 status_item_list[SI_LENGTH], nmmd->afi.seconds_total,
 157                 status_item_list[SI_NUM_PLAYED], nmmd->num_played,
 158
 159                 status_item_list[SI_STATUS_BAR], bar ? bar : "(none)",
 160                 status_item_list[SI_STATUS], status,
 161                 status_item_list[SI_STATUS_FLAGS], flags,
 162                 status_item_list[SI_SELECTOR], "FIXME",
 163
 164                 status_item_list[SI_OFFSET], offset,
 165                 status_item_list[SI_FORMAT], audio_format_name(nmmd->audio_format),
 166                 nmmd->afi.info_string,
 167
 168                 status_item_list[SI_UPTIME], ut,
 169                 status_item_list[SI_STREAM_START],
 170                         (long unsigned)nmmd->stream_start.tv_sec,
 171                         (long unsigned)nmmd->stream_start.tv_usec,
 172                 status_item_list[SI_CURRENT_TIME],
 173                         (long unsigned)now.tv_sec,
 174                         (long unsigned)now.tv_usec
 175
 176         );
 177         free(bar);
 178         free(flags);
 179         free(status);
 180         free(ut);
 181         return ret;
 182 }
 183
 184 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 185 {
 186         int i;
 187         /* this has to match sender.h */
 188         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 189
 190         scd->sender_num = -1;
 191         if (argc < 2)
 192                 return -E_COMMAND_SYNTAX;
 193         for (i = 0; senders[i].name; i++)
 194                 if (!strcmp(senders[i].name, argv[1]))
 195                         break;
 196         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 197         if (!senders[i].name)
 198                 return -E_COMMAND_SYNTAX;
 199         scd->sender_num = i;
 200         for (i = 0; subcmds[i]; i++)
 201                 if (!strcmp(subcmds[i], argv[2]))
 202                         break;
 203         if (!subcmds[i])
 204                 return -E_COMMAND_SYNTAX;
 205         scd->cmd_num = i;
 206         mmd_lock();
 207         if (!senders[scd->sender_num].client_cmds[scd->cmd_num]) {
 208                 mmd_unlock();
 209                 return -E_SENDER_CMD;
 210         }
 211         mmd_unlock();
 212         switch (scd->cmd_num) {
 213         case SENDER_ON:
 214         case SENDER_OFF:
 215                 if (argc != 3)
 216                         return -E_COMMAND_SYNTAX;
 217                 break;
 218         case SENDER_DENY:
 219         case SENDER_ALLOW:
 220                 if (argc != 4 && argc != 5)
 221                         return -E_COMMAND_SYNTAX;
 222                 if (!inet_pton(AF_INET, argv[3], &scd->addr))
 223                         return -E_COMMAND_SYNTAX;
 224                 scd->netmask = 32;
 225                 if (argc == 5) {
 226                         scd->netmask = atoi(argv[4]);
 227                         if (scd->netmask < 0 || scd->netmask > 32)
 228                                 return -E_COMMAND_SYNTAX;
 229                 }
 230                 break;
 231         case SENDER_ADD:
 232         case SENDER_DELETE:
 233                 if (argc != 4 && argc != 5)
 234                         return -E_COMMAND_SYNTAX;
 235                 if (!inet_pton(AF_INET, argv[3], &scd->addr))
 236                         return -E_COMMAND_SYNTAX;
 237                 scd->port = -1;
 238                 if (argc == 5) {
 239                         scd->port = atoi(argv[4]);
 240                         if (scd->port < 0 || scd->port > 65535)
 241                                 return -E_COMMAND_SYNTAX;
 242                 }
 243                 break;
 244         default:
 245                 return -E_COMMAND_SYNTAX;
 246         }
 247         return 1;
 248 }
 249
 250 int com_sender(int fd, int argc, char * const * argv)
 251 {
 252         int i, ret;
 253         struct sender_command_data scd;
 254
 255         if (argc < 2) {
 256                 char *msg = NULL;
 257                 for (i = 0; senders[i].name; i++) {
 258                         char *tmp = make_message("%s%s\n",
 259                                 msg? msg : "", senders[i].name);
 260                         free(msg);
 261                         msg = tmp;
 262                 }
 263                 ret = send_buffer(fd, msg);
 264                 free(msg);
 265                 return ret;
 266         }
 267         ret = check_sender_args(argc, argv, &scd);
 268         if (ret < 0) {
 269                 char *msg;
 270                 if (scd.sender_num < 0)
 271                         return ret;
 272                 msg = senders[scd.sender_num].help();
 273                 send_buffer(fd, msg);
 274                 free(msg);
 275                 return 1;
 276         }
 277         for (i = 0; i < 10; i++) {
 278                 mmd_lock();
 279                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 280                         mmd_unlock();
 281                         usleep(100 * 1000);
 282                         continue;
 283                 }
 284                 mmd->sender_cmd_data = scd;
 285                 mmd_unlock();
 286                 break;
 287         }
 288         return (i < 10)? 1 : -E_LOCK;
 289 }
 290
 291 /* server info */
 292 int com_si(int fd, int argc, __a_unused char * const * argv)
 293 {
 294         int i, ret;
 295         char *ut;
 296         char *sender_info = NULL, *sender_list = NULL;
 297
 298         if (argc != 1)
 299                 return -E_COMMAND_SYNTAX;
 300         mmd_lock();
 301         for (i = 0; senders[i].name; i++) {
 302                 char *info = senders[i].info();
 303                 sender_info = para_strcat(sender_info, info);
 304                 free(info);
 305                 sender_list = para_strcat(sender_list, senders[i].name);
 306                 sender_list = para_strcat(sender_list, " ");
 307         }
 308         ut = uptime_str();
 309         ret = send_va_buffer(fd, "up: %s\nplayed: %u\n"
 310                 "pid: %d\n"
 311                 "connections (active/accepted/total): %u/%u/%u\n"
 312                 "current loglevel: %i\n"
 313                 "supported audio formats: %s\n"
 314                 "supported senders: %s\n"
 315                 "%s",
 316                 ut, mmd->num_played,
 317                 getppid(),
 318                 mmd->active_connections,
 319                 mmd->num_commands,
 320                 mmd->num_connects,
 321                 conf.loglevel_arg,
 322                 supported_audio_formats(),
 323                 sender_list,
 324                 sender_info
 325         );
 326         mmd_unlock();
 327         free(ut);
 328         free(sender_list);
 329         free(sender_info);
 330         return ret;
 331 }
 332
 333 /* version */
 334 int com_version(int fd, int argc, __a_unused char * const * argv)
 335 {
 336         if (argc != 1)
 337                 return -E_COMMAND_SYNTAX;
 338         return send_buffer(fd, VERSION_TEXT("server")
 339                 "built: " BUILD_DATE "\n"
 340                 SYSTEM ", " CC_VERSION "\n"
 341         );
 342 }
 343
 344 /* sc */
 345 int com_sc(int fd, int argc, char * const * argv)
 346 {
 347         char *name = NULL;
 348         int ret, old = 0, count = -1; /* print af change forever */
 349
 350         if (argc > 1)
 351                 count = atoi(argv[1]);
 352 repeat:
 353         mmd_lock();
 354         if (old != mmd->num_played) {
 355                 old = mmd->num_played;
 356                 name = para_strdup(mmd->filename);
 357         }
 358         mmd_unlock();
 359         if (name) {
 360                 ret = send_va_buffer(fd, "%s\n", name);
 361                 free(name);
 362                 name = NULL;
 363                 if (ret < 0)
 364                         return ret;
 365                 if (argc > 1 && !--count)
 366                         return 1;
 367         }
 368         usleep(500000);
 369         goto repeat;
 370 }
 371
 372 /* sb */
 373 int com_sb(int fd, int argc, char * const * argv)
 374 {
 375         char *sb;
 376         int ret, nr = -1;       /* status bar will be printed that many
 377                                  * times. Negative value means: print
 378                                  * forever
 379                                  */
 380         if (argc > 1)
 381                 nr = atoi(argv[1]);
 382         while (nr) {
 383                 mmd_lock();
 384                 sb = get_sb_string(mmd);
 385                 mmd_unlock();
 386                 ret = send_va_buffer(fd, "%s\n", sb);
 387                 free(sb);
 388                 if (ret < 0)
 389                         return ret;
 390                 if (nr == 1)
 391                         return 1;
 392                 usleep(500000);
 393                 if (nr > 0)
 394                         nr--;
 395         }
 396         return 1;
 397 }
 398
 399 /* stat */
 400 int com_stat(int fd, int argc, char * const * argv)
 401 {
 402         int ret, num = 0;/* status will be printed that many
 403                           * times. num <= 0 means: print forever
 404                           */
 405         struct misc_meta_data tmp, *nmmd = &tmp;
 406         char *s;
 407
 408         signal(SIGUSR1, dummy);
 409
 410         if (argc > 1)
 411                 num = atoi(argv[1]);
 412         for (;;) {
 413
 414                 mmd_dup(nmmd);
 415                 s = get_status(nmmd);
 416                 ret = send_buffer(fd, s);
 417                 free(s);
 418                 if (ret < 0)
 419                         goto out;
 420                 ret = 1;
 421                 if (num == 1)
 422                         goto out;
 423                 sleep(50);
 424                 if (getppid() == 1)
 425                         return -E_SERVER_CRASH;
 426         }
 427 out:
 428         return ret;
 429 }
 430
 431 static int send_list_of_commands(int fd, struct server_command *cmd,
 432                 const char *handler)
 433 {
 434         int ret, i;
 435
 436         for (i = 1; cmd->name; cmd++, i++) {
 437                 char *perms = cmd_perms_itohuman(cmd->perms);
 438                 ret = send_va_buffer(fd, "%s\t%s\t%s\t%s\n", cmd->name,
 439                         handler,
 440                         perms,
 441                         cmd->description);
 442                 free(perms);
 443                 if (ret < 0)
 444                         return ret;
 445         }
 446         return 1;
 447 }
 448
 449 /* always returns string that must be freed by the caller in handler */
 450 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 451 {
 452         struct server_command *cmd;
 453
 454         for (cmd = server_cmds; cmd->name; cmd++)
 455                 if (!strcmp(cmd->name, name)) {
 456                         if (handler)
 457                                 *handler = para_strdup("para_server"); /* server commands */
 458                         return cmd;
 459                 }
 460         /* not found, look for commands supported by afs */
 461         for (cmd = afs_cmds; cmd->name; cmd++)
 462                 if (!strcmp(cmd->name, name))
 463                         return cmd;
 464         return NULL;
 465 }
 466
 467 /* help */
 468 int com_help(int fd, int argc, char * const * argv)
 469 {
 470         struct server_command *cmd;
 471         char *perms, *handler;
 472         int ret;
 473
 474         if (argc < 2) {
 475                 /* no argument given, print list of commands */
 476                 if ((ret = send_list_of_commands(fd, server_cmds, "server")) < 0)
 477                         return ret;
 478                 return send_list_of_commands(fd, afs_cmds, "afs");
 479         }
 480         /* argument given for help */
 481         cmd = get_cmd_ptr(argv[1], &handler);
 482         if (!cmd) {
 483                 free(handler);
 484                 return -E_BAD_CMD;
 485         }
 486         perms = cmd_perms_itohuman(cmd->perms);
 487         ret = send_va_buffer(fd,
 488                 "%s - %s\n\n"
 489                 "handler: %s\n"
 490                 "permissions: %s\n"
 491                 "usage: %s\n\n"
 492                 "%s\n",
 493                 argv[1],
 494                 cmd->description,
 495                 handler,
 496                 perms,
 497                 cmd->usage,
 498                 cmd->help
 499         );
 500         free(perms);
 501         free(handler);
 502         return ret;
 503 }
 504
 505 /* hup */
 506 int com_hup(__a_unused int fd, int argc, __a_unused char * const * argv)
 507 {
 508         if (argc != 1)
 509                 return -E_COMMAND_SYNTAX;
 510         kill(getppid(), SIGHUP);
 511         return 1;
 512 }
 513
 514 /* term */
 515 int com_term(__a_unused int fd, int argc, __a_unused char * const * argv)
 516 {
 517         if (argc != 1)
 518                 return -E_COMMAND_SYNTAX;
 519         kill(getppid(), SIGTERM);
 520         return 1;
 521 }
 522
 523 int com_play(__a_unused int fd, int argc, __a_unused char * const * argv)
 524 {
 525         if (argc != 1)
 526                 return -E_COMMAND_SYNTAX;
 527         mmd_lock();
 528         mmd->new_vss_status_flags |= VSS_PLAYING;
 529         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 530         mmd_unlock();
 531         return 1;
 532
 533 }
 534
 535 /* stop */
 536 int com_stop(__a_unused int fd, int argc, __a_unused char * const * argv)
 537 {
 538         if (argc != 1)
 539                 return -E_COMMAND_SYNTAX;
 540         mmd_lock();
 541         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 542         mmd->new_vss_status_flags &= ~VSS_REPOS;
 543         mmd->new_vss_status_flags |= VSS_NEXT;
 544         mmd_unlock();
 545         return 1;
 546 }
 547
 548 /* pause */
 549 int com_pause(__a_unused int fd, int argc, __a_unused char * const * argv)
 550 {
 551         if (argc != 1)
 552                 return -E_COMMAND_SYNTAX;
 553         mmd_lock();
 554         if (!vss_paused())
 555                 mmd->events++;
 556         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 557         mmd->new_vss_status_flags &= ~VSS_NEXT;
 558         mmd_unlock();
 559         return 1;
 560 }
 561
 562 /* next */
 563 int com_next(__a_unused int fd, int argc, __a_unused char * const * argv)
 564 {
 565         if (argc != 1)
 566                 return -E_COMMAND_SYNTAX;
 567         mmd_lock();
 568         mmd->events++;
 569         mmd->new_vss_status_flags |= VSS_NEXT;
 570         mmd_unlock();
 571         return 1;
 572 }
 573
 574 /* nomore */
 575 int com_nomore(__a_unused int fd, int argc, __a_unused char * const * argv)
 576 {
 577         if (argc != 1)
 578                 return -E_COMMAND_SYNTAX;
 579         mmd_lock();
 580         if (vss_playing() || vss_paused())
 581                 mmd->new_vss_status_flags |= VSS_NOMORE;
 582         mmd_unlock();
 583         return 1;
 584 }
 585
 586 /* ff */
 587 int com_ff(__a_unused int fd, int argc, char * const * argv)
 588 {
 589         long promille;
 590         int ret, backwards = 0;
 591         unsigned i;
 592         char c;
 593
 594         if (argc != 2)
 595                 return -E_COMMAND_SYNTAX;
 596         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 597                 return -E_COMMAND_SYNTAX;
 598         if (ret > 1 && c == '-')
 599                 backwards = 1; /* jmp backwards */
 600         mmd_lock();
 601         ret = -E_NO_AUDIO_FILE;
 602         if (!mmd->afi.chunks_total || !mmd->afi.seconds_total)
 603                 goto out;
 604         promille = (1000 * mmd->current_chunk) / mmd->afi.chunks_total;
 605         if (backwards)
 606                 promille -= 1000 * i / mmd->afi.seconds_total;
 607         else
 608                 promille += 1000 * i / mmd->afi.seconds_total;
 609         if (promille < 0)
 610                 promille = 0;
 611         if (promille >  1000) {
 612                 mmd->new_vss_status_flags |= VSS_NEXT;
 613                 goto out;
 614         }
 615         mmd->repos_request = (mmd->afi.chunks_total * promille) / 1000;
 616         mmd->new_vss_status_flags |= VSS_REPOS;
 617         mmd->new_vss_status_flags &= ~VSS_NEXT;
 618         mmd->events++;
 619         ret = 1;
 620 out:
 621         mmd_unlock();
 622         return ret;
 623 }
 624
 625 /* jmp */
 626 int com_jmp(__a_unused int fd, int argc, char * const * argv)
 627 {
 628         long unsigned int i;
 629         int ret;
 630
 631         if (argc != 2)
 632                 return -E_COMMAND_SYNTAX;
 633         if (sscanf(argv[1], "%lu", &i) <= 0)
 634                 return -E_COMMAND_SYNTAX;
 635         mmd_lock();
 636         ret = -E_NO_AUDIO_FILE;
 637         if (!mmd->afi.chunks_total)
 638                 goto out;
 639         if (i > 100)
 640                 i = 100;
 641         PARA_INFO_LOG("jumping to %lu%%\n", i);
 642         mmd->repos_request = (mmd->afi.chunks_total * i + 50)/ 100;
 643         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 644                 mmd->chunks_sent, mmd->offset);
 645         mmd->new_vss_status_flags |= VSS_REPOS;
 646         mmd->new_vss_status_flags &= ~VSS_NEXT;
 647         ret = 1;
 648         mmd->events++;
 649 out:
 650         mmd_unlock();
 651         return ret;
 652 }
 653
 654 /*
 655  * check if perms are sufficient to exec a command having perms cmd_perms.
 656  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 657  */
 658 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 659 {
 660         PARA_DEBUG_LOG("%s", "checking permissions\n");
 661         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 662 }
 663
 664 /*
 665  * Parse first string from *cmd and lookup in table of valid commands.
 666  * On error, NULL is returned.
 667  */
 668 static struct server_command *parse_cmd(const char *cmdstr)
 669 {
 670         char buf[255];
 671         int n = 0;
 672
 673         sscanf(cmdstr, "%200s%n", buf, &n);
 674         if (!n)
 675                 return NULL;
 676         buf[n] = '\0';
 677         return get_cmd_ptr(buf, NULL);
 678 }
 679
 680 static long int para_rand(long unsigned max)
 681 {
 682         return (long int) ((max + 0.0) * (random() / (RAND_MAX + 1.0)));
 683 }
 684
 685 static void init_rc4_keys(void)
 686 {
 687         int i;
 688
 689         for (i = 0; i < 2 * RC4_KEY_LEN; i++)
 690                 rc4_buf[i] = para_rand(256);
 691         PARA_DEBUG_LOG("rc4 keys initialized (%u:%u)\n",
 692                 (unsigned char) rc4_buf[0],
 693                 (unsigned char) rc4_buf[RC4_KEY_LEN]);
 694         RC4_set_key(&rc4_recv_key, RC4_KEY_LEN, rc4_buf);
 695         RC4_set_key(&rc4_send_key, RC4_KEY_LEN, rc4_buf + RC4_KEY_LEN);
 696 }
 697
 698 static void rc4_recv(unsigned long len, const unsigned char *indata,
 699                 unsigned char *outdata, __a_unused void *private_data)
 700 {
 701         RC4(&rc4_recv_key, len, indata, outdata);
 702 }
 703
 704 static void rc4_send(unsigned long len, const unsigned char *indata,
 705                 unsigned char *outdata, __a_unused void *private_data)
 706 {
 707         RC4(&rc4_send_key, len, indata, outdata);
 708 }
 709
 710 static int read_command(int fd, char **result)
 711 {
 712         int ret;
 713         char buf[4096];
 714         char *command = NULL;
 715
 716         for (;;) {
 717                 size_t numbytes;
 718                 char *p;
 719
 720                 ret = recv_buffer(fd, buf, sizeof(buf));
 721                 if (ret < 0)
 722                         goto out;
 723                 if (!ret)
 724                         break;
 725                 numbytes = ret;
 726                 ret = -E_COMMAND_SYNTAX;
 727                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 728                         goto out;
 729                 command = para_strcat(command, buf);
 730                 p = strstr(command, EOC_MSG);
 731                 if (p) {
 732                         *p = '\0';
 733                         break;
 734                 }
 735         }
 736         ret = command? 1 : -E_COMMAND_SYNTAX;
 737 out:
 738         if (ret < 0)
 739                 free(command);
 740         else
 741                 *result = command;
 742         return ret;
 743
 744 }
 745
 746 /**
 747  * perform user authentication and execute a command
 748  *
 749  * \param fd the file descriptor to send output to
 750  * \param addr socket address info of peer
 751  *
 752  * \return EXIT_SUCCESS or EXIT_FAILURE
 753  *
 754  * Whenever para_server accepts an incoming tcp connection on
 755  * the port it listens on, it forks and the resulting child
 756  * calls this function.
 757  *
 758  * An RSA-based challenge/response is used to authenticate
 759  * the peer. It that authentication succeeds, a random RC4
 760  * session key is generated and sent back to the peer,
 761  * encrypted with its RSA public key.  From this point on,
 762  * all transfers are crypted with this session key.
 763  *
 764  * Next it is checked if the peer supplied  a valid server command or a command
 765  * for the audio file selector.  If yes, and if the user has sufficient
 766  * permissions to execute that command, the function calls the corresponding
 767  * command handler which does argument checking and further processing.
 768  *
 769  * In order to cope with a DOS attacks, a timeout is set up
 770  * which terminates the function if the connection was not
 771  * authenticated when the timeout expires.
 772  *
 773  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 774  */
 775 int handle_connect(int fd, struct sockaddr_in *addr)
 776 {
 777         int ret, argc, use_rc4 = 0;
 778         char buf[4096];
 779         unsigned char crypt_buf[MAXLINE];
 780         struct user *u;
 781         struct server_command *cmd = NULL;
 782         long unsigned challenge_nr, chall_response;
 783         char **argv = NULL;
 784         char *p, *command = NULL;
 785         size_t numbytes;
 786
 787         signal(SIGCHLD, SIG_IGN);
 788         signal(SIGINT, SIG_DFL);
 789         signal(SIGTERM, SIG_DFL);
 790         signal(SIGHUP, SIG_DFL);
 791         signal(SIGUSR1, SIG_IGN);
 792
 793         challenge_nr = random();
 794         /* send Welcome message */
 795         ret = send_va_buffer(fd, "This is para_server, version "
 796                 PACKAGE_VERSION  ".\n" );
 797         if (ret < 0)
 798                 goto err_out;
 799         /* recv auth request line */
 800         ret = recv_buffer(fd, buf, sizeof(buf));
 801         if (ret < 0)
 802                 goto err_out;
 803         if (ret <= 6) {
 804                 ret = -E_AUTH;
 805                 goto err_out;
 806         }
 807         numbytes = ret;
 808         ret = -E_AUTH;
 809         if (strncmp(buf, "auth ", 5))
 810                 goto err_out;
 811
 812         if (numbytes < 9 || strncmp(buf, "auth rc4 ", 9))
 813                 p = buf + 5; /* client version < 0.2.6 */
 814         else {
 815                 p = buf + 9; /* client version >= 0.2.6 */
 816                 use_rc4 = 1;
 817         }
 818         PARA_DEBUG_LOG("received %s request for user %s\n",
 819                 use_rc4? "rc4" : "auth", p);
 820         ret = -E_BAD_USER;
 821         u = lookup_user(p);
 822         if (!u)
 823                 goto err_out;
 824         ret = para_encrypt_challenge(u->rsa, challenge_nr, crypt_buf);
 825         if (ret <= 0)
 826                 goto err_out;
 827         numbytes = ret;
 828         PARA_DEBUG_LOG("sending %zu byte challenge\n", numbytes);
 829         /* We can't use send_buffer here since buf may contain null bytes */
 830         ret = send_bin_buffer(fd,(char *) crypt_buf, numbytes);
 831         if (ret < 0)
 832                 goto err_out;
 833         /* recv decrypted number */
 834         ret = recv_buffer(fd, buf, sizeof(buf));
 835         if (ret < 0)
 836                 goto err_out;
 837         numbytes = ret;
 838         ret = -E_AUTH;
 839         if (!numbytes)
 840                 goto err_out;
 841         if (sscanf(buf, CHALLENGE_RESPONSE_MSG "%lu", &chall_response) < 1
 842                         || chall_response != challenge_nr)
 843                 goto err_out;
 844         /* auth successful, send 'Proceed' message */
 845         PARA_INFO_LOG("good auth for %s (%lu)\n", u->name, challenge_nr);
 846         sprintf(buf, "%s", PROCEED_MSG);
 847         if (use_rc4) {
 848                 init_rc4_keys();
 849                 ret = para_encrypt_buffer(u->rsa, rc4_buf, 2 * RC4_KEY_LEN,
 850                         (unsigned char *)buf + PROCEED_MSG_LEN + 1);
 851                 if (ret <= 0)
 852                         goto err_out;
 853                 numbytes = ret + strlen(PROCEED_MSG) + 1;
 854         } else
 855                 numbytes = strlen(buf);
 856         ret = send_bin_buffer(fd, buf, numbytes);
 857         if (ret < 0)
 858                 goto err_out;
 859         if (use_rc4)
 860                 enable_crypt(fd, rc4_recv, rc4_send, NULL);
 861         ret = read_command(fd, &command);
 862         if (ret < 0)
 863                 goto err_out;
 864         ret = -E_BAD_CMD;
 865         cmd = parse_cmd(command);
 866         if (!cmd)
 867                 goto err_out;
 868         /* valid command, check permissions */
 869         ret = check_perms(u->perms, cmd);
 870         if (ret < 0)
 871                 goto err_out;
 872         /* valid command and sufficient perms */
 873         alarm(0);
 874         argc = split_args(command, &argv, "\n");
 875         mmd_lock();
 876         mmd->num_commands++;
 877         mmd_unlock();
 878         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 879                 inet_ntoa(addr->sin_addr));
 880         ret = cmd->handler(fd, argc, argv);
 881         if (ret >= 0) {
 882                 ret = EXIT_SUCCESS;
 883                 goto out;
 884         }
 885 err_out:
 886         PARA_NOTICE_LOG("%s\n", PARA_STRERROR(-ret));
 887         if (ret != -E_SEND && ret != -E_RECV)
 888                 send_va_buffer(fd, "%s\n", PARA_STRERROR(-ret));
 889         ret = EXIT_FAILURE;
 890 out:
 891         free(command);
 892         free(argv);
 893         mmd_lock();
 894         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 895                 mmd->events++;
 896         mmd->active_connections--;
 897         mmd_unlock();
 898         return ret;
 899 }