command.c

   1 /*
   2  * Copyright (C) 1997-2009 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 <signal.h>
  10 #include <sys/time.h>
  11 #include <sys/types.h>
  12 #include <dirent.h>
  13 #include <openssl/rc4.h>
  14 #include <osl.h>
  15
  16 #include "para.h"
  17 #include "error.h"
  18 #include "server.cmdline.h"
  19 #include "string.h"
  20 #include "afh.h"
  21 #include "afs.h"
  22 #include "server.h"
  23 #include "vss.h"
  24 #include "list.h"
  25 #include "send.h"
  26 #include "rc4.h"
  27 #include "net.h"
  28 #include "daemon.h"
  29 #include "fd.h"
  30 #include "ipc.h"
  31 #include "user_list.h"
  32 #include "server_command_list.h"
  33 #include "afs_command_list.h"
  34 #include "sched.h"
  35 #include "signal.h"
  36
  37 /** Commands including options must be shorter than this. */
  38 #define MAX_COMMAND_LEN 32768
  39
  40 static RC4_KEY rc4_recv_key;
  41 static RC4_KEY rc4_send_key;
  42 static unsigned char rc4_buf[2 * RC4_KEY_LEN];
  43
  44 extern int mmd_mutex;
  45 extern struct misc_meta_data *mmd;
  46 extern struct sender senders[];
  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)
 107 {
 108         char *ret, 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
 115         /* report real status */
 116         status = vss_status_tohuman(nmmd->vss_status_flags);
 117         flags = vss_get_status_flags(nmmd->vss_status_flags);
 118         if (nmmd->size) { /* parent currently has an audio file open */
 119                 localtime_r(&nmmd->mtime, &mtime_tm);
 120                 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
 121         }
 122         gettimeofday(&current_time, NULL);
 123         ret = make_message(
 124                 "%s: %zu\n" /* file size */
 125                 "%s: %s\n" /* mtime */
 126                 "%s: %s\n" /* status */
 127                 "%s: %s\n" /* status flags */
 128                 "%s: %li\n" /* offset */
 129                 "%s: %s\n" /* afs mode */
 130                 "%s: %lu.%lu\n" /* stream start */
 131                 "%s: %lu.%lu\n", /* current server time */
 132                 status_item_list[SI_FILE_SIZE], nmmd->size / 1024,
 133                 status_item_list[SI_MTIME], mtime,
 134                 status_item_list[SI_STATUS], status,
 135                 status_item_list[SI_STATUS_FLAGS], flags,
 136
 137                 status_item_list[SI_OFFSET], offset,
 138                 status_item_list[SI_AFS_MODE], mmd->afs_mode_string,
 139
 140                 status_item_list[SI_STREAM_START],
 141                         (long unsigned)nmmd->stream_start.tv_sec,
 142                         (long unsigned)nmmd->stream_start.tv_usec,
 143                 status_item_list[SI_CURRENT_TIME],
 144                         (long unsigned)current_time.tv_sec,
 145                         (long unsigned)current_time.tv_usec
 146         );
 147         free(flags);
 148         free(status);
 149         free(ut);
 150         return ret;
 151 }
 152
 153 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 154 {
 155         int i;
 156         /* this has to match sender.h */
 157         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 158
 159         scd->sender_num = -1;
 160         if (argc < 2)
 161                 return -E_COMMAND_SYNTAX;
 162         for (i = 0; senders[i].name; i++)
 163                 if (!strcmp(senders[i].name, argv[1]))
 164                         break;
 165         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 166         if (!senders[i].name)
 167                 return -E_COMMAND_SYNTAX;
 168         scd->sender_num = i;
 169         for (i = 0; subcmds[i]; i++)
 170                 if (!strcmp(subcmds[i], argv[2]))
 171                         break;
 172         if (!subcmds[i])
 173                 return -E_COMMAND_SYNTAX;
 174         scd->cmd_num = i;
 175         if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
 176                 return -E_SENDER_CMD;
 177         switch (scd->cmd_num) {
 178         case SENDER_ON:
 179         case SENDER_OFF:
 180                 if (argc != 3)
 181                         return -E_COMMAND_SYNTAX;
 182                 break;
 183         case SENDER_DENY:
 184         case SENDER_ALLOW:
 185                 if (argc != 4 && argc != 5)
 186                         return -E_COMMAND_SYNTAX;
 187                 if (!is_valid_ipv4_address(argv[3]))
 188                         return -E_COMMAND_SYNTAX;
 189                 scd->netmask = 32;
 190                 if (argc == 5) {
 191                         scd->netmask = atoi(argv[4]);
 192                         if (scd->netmask < 0 || scd->netmask > 32)
 193                                 return -E_COMMAND_SYNTAX;
 194                 }
 195                 strncpy(scd->host, argv[3], sizeof(scd->host));
 196                 break;
 197         case SENDER_ADD:
 198         case SENDER_DELETE:
 199                 if (argc != 4)
 200                         return -E_COMMAND_SYNTAX;
 201                 return parse_fec_url(argv[3], scd);
 202         default:
 203                 return -E_COMMAND_SYNTAX;
 204         }
 205         return 1;
 206 }
 207
 208 int com_sender(int fd, int argc, char * const * argv)
 209 {
 210         int i, ret;
 211         struct sender_command_data scd;
 212
 213         if (argc < 2) {
 214                 char *msg = NULL;
 215                 for (i = 0; senders[i].name; i++) {
 216                         char *tmp = make_message("%s%s\n",
 217                                 msg? msg : "", senders[i].name);
 218                         free(msg);
 219                         msg = tmp;
 220                 }
 221                 ret = send_buffer(fd, msg);
 222                 free(msg);
 223                 return ret;
 224         }
 225         ret = check_sender_args(argc, argv, &scd);
 226         if (ret < 0) {
 227                 char *msg;
 228                 if (scd.sender_num < 0)
 229                         return ret;
 230                 msg = senders[scd.sender_num].help();
 231                 ret = send_buffer(fd, msg);
 232                 free(msg);
 233                 return ret;
 234         }
 235         for (i = 0; i < 10; i++) {
 236                 mutex_lock(mmd_mutex);
 237                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 238                         mutex_unlock(mmd_mutex);
 239                         usleep(100 * 1000);
 240                         continue;
 241                 }
 242                 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
 243                 mutex_unlock(mmd_mutex);
 244                 break;
 245         }
 246         return (i < 10)? 1 : -E_LOCK;
 247 }
 248
 249 /* server info */
 250 int com_si(int fd, int argc, __a_unused char * const * argv)
 251 {
 252         int i, ret;
 253         char *ut;
 254         char *sender_info = NULL, *sender_list = NULL;
 255
 256         if (argc != 1)
 257                 return -E_COMMAND_SYNTAX;
 258         mutex_lock(mmd_mutex);
 259         for (i = 0; senders[i].name; i++) {
 260                 char *info = senders[i].info();
 261                 sender_info = para_strcat(sender_info, info);
 262                 free(info);
 263                 sender_list = para_strcat(sender_list, senders[i].name);
 264                 sender_list = para_strcat(sender_list, " ");
 265         }
 266         ut = uptime_str();
 267         ret = send_va_buffer(fd, "up: %s\nplayed: %u\n"
 268                 "server_pid: %d\n"
 269                 "afs_pid: %d\n"
 270                 "connections (active/accepted/total): %u/%u/%u\n"
 271                 "current loglevel: %s\n"
 272                 "supported audio formats: %s\n"
 273                 "supported senders: %s\n"
 274                 "%s",
 275                 ut, mmd->num_played,
 276                 (int)getppid(),
 277                 (int)mmd->afs_pid,
 278                 mmd->active_connections,
 279                 mmd->num_commands,
 280                 mmd->num_connects,
 281                 conf.loglevel_arg,
 282                 supported_audio_formats(),
 283                 sender_list,
 284                 sender_info
 285         );
 286         mutex_unlock(mmd_mutex);
 287         free(ut);
 288         free(sender_list);
 289         free(sender_info);
 290         return ret;
 291 }
 292
 293 /* version */
 294 int com_version(int fd, int argc, __a_unused char * const * argv)
 295 {
 296         if (argc != 1)
 297                 return -E_COMMAND_SYNTAX;
 298         return send_buffer(fd, VERSION_TEXT("server")
 299                 "built: " BUILD_DATE "\n"
 300                 UNAME_RS ", " CC_VERSION "\n"
 301         );
 302 }
 303
 304 /**
 305  * Write a list of audio-file related status items with empty values.
 306  *
 307  * This is used by vss when currently no audio file is open.
 308  */
 309 static char *empty_status_items(void)
 310 {
 311         return make_message(
 312                 "%s: \n" /* path */
 313                 "%s: \n" /* dirname */
 314                 "%s: \n" /* basename */
 315                 "%s: \n" /* score */
 316                 "%s: \n" /* attributes bitmap */
 317                 "%s: \n" /* attributes txt */
 318                 "%s: \n" /* hash */
 319                 "%s: \n" /* image id */
 320                 "%s: \n" /* image name */
 321                 "%s: \n" /* lyrics id */
 322                 "%s: \n" /* lyrics name */
 323                 "%s: \n" /* bitrate */
 324                 "%s: \n" /* format */
 325                 "%s: \n" /* frequency */
 326                 "%s: \n" /* channels */
 327                 "%s: \n" /* duration */
 328                 "%s: \n" /* seconds total */
 329                 "%s: \n" /* num played */
 330                 "%s: \n" /* last played */
 331                 "%s: \n" /* techinfo */
 332                 "%s: \n" /* artist */
 333                 "%s: \n" /* title */
 334                 "%s: \n" /* year */
 335                 "%s: \n" /* album */
 336                 "%s: \n" /* comment */
 337                 "%s: \n" /* amplification */
 338                 ,
 339                 status_item_list[SI_PATH],
 340                 status_item_list[SI_DIRECTORY],
 341                 status_item_list[SI_BASENAME],
 342                 status_item_list[SI_SCORE],
 343                 status_item_list[SI_ATTRIBUTES_BITMAP],
 344                 status_item_list[SI_ATTRIBUTES_TXT],
 345                 status_item_list[SI_HASH],
 346                 status_item_list[SI_IMAGE_ID],
 347                 status_item_list[SI_IMAGE_NAME],
 348                 status_item_list[SI_LYRICS_ID],
 349                 status_item_list[SI_LYRICS_NAME],
 350                 status_item_list[SI_BITRATE],
 351                 status_item_list[SI_FORMAT],
 352                 status_item_list[SI_FREQUENCY],
 353                 status_item_list[SI_CHANNELS],
 354                 status_item_list[SI_DURATION],
 355                 status_item_list[SI_SECONDS_TOTAL],
 356                 status_item_list[SI_NUM_PLAYED],
 357                 status_item_list[SI_LAST_PLAYED],
 358                 status_item_list[SI_TECHINFO],
 359                 status_item_list[SI_ARTIST],
 360                 status_item_list[SI_TITLE],
 361                 status_item_list[SI_YEAR],
 362                 status_item_list[SI_ALBUM],
 363                 status_item_list[SI_COMMENT],
 364                 status_item_list[SI_AMPLIFICATION]
 365         );
 366 }
 367
 368 /* stat */
 369 int com_stat(int fd, int argc, char * const * argv)
 370 {
 371         int ret, num = 0;/* status will be printed that many
 372                           * times. num <= 0 means: print forever
 373                           */
 374         struct misc_meta_data tmp, *nmmd = &tmp;
 375         char *s;
 376
 377         para_sigaction(SIGUSR1, dummy);
 378
 379         if (argc > 1)
 380                 num = atoi(argv[1]);
 381         for (;;) {
 382
 383                 mmd_dup(nmmd);
 384                 s = get_status(nmmd);
 385                 ret = send_buffer(fd, s);
 386                 free(s);
 387                 if (ret < 0)
 388                         goto out;
 389                 if (nmmd->vss_status_flags & VSS_NEXT) {
 390                         static char *esi;
 391                         if (!esi)
 392                                 esi = empty_status_items();
 393                         ret = send_buffer(fd, esi);
 394                         if (ret < 0)
 395                                 goto out;
 396                 } else
 397                         send_afs_status(fd);
 398                 ret = 1;
 399                 if (num > 0 && !--num)
 400                         goto out;
 401                 sleep(50);
 402                 if (getppid() == 1)
 403                         return -E_SERVER_CRASH;
 404         }
 405 out:
 406         return ret;
 407 }
 408
 409 static int send_list_of_commands(int fd, struct server_command *cmd,
 410                 const char *handler)
 411 {
 412         int ret, i;
 413
 414         for (i = 1; cmd->name; cmd++, i++) {
 415                 char *perms = cmd_perms_itohuman(cmd->perms);
 416                 ret = send_va_buffer(fd, "%s\t%s\t%s\t%s\n", cmd->name,
 417                         handler,
 418                         perms,
 419                         cmd->description);
 420                 free(perms);
 421                 if (ret < 0)
 422                         return ret;
 423         }
 424         return 1;
 425 }
 426
 427 /* returns string that must be freed by the caller */
 428 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 429 {
 430         struct server_command *cmd;
 431
 432         for (cmd = server_cmds; cmd->name; cmd++)
 433                 if (!strcmp(cmd->name, name)) {
 434                         if (handler)
 435                                 *handler = para_strdup("server"); /* server commands */
 436                         return cmd;
 437                 }
 438         /* not found, look for commands supported by afs */
 439         for (cmd = afs_cmds; cmd->name; cmd++)
 440                 if (!strcmp(cmd->name, name)) {
 441                         if (handler)
 442                                 *handler = para_strdup("afs");
 443                         return cmd;
 444                 }
 445         return NULL;
 446 }
 447
 448 /* help */
 449 int com_help(int fd, int argc, char * const * argv)
 450 {
 451         struct server_command *cmd;
 452         char *perms, *handler;
 453         int ret;
 454
 455         if (argc < 2) {
 456                 /* no argument given, print list of commands */
 457                 if ((ret = send_list_of_commands(fd, server_cmds, "server")) < 0)
 458                         return ret;
 459                 return send_list_of_commands(fd, afs_cmds, "afs");
 460         }
 461         /* argument given for help */
 462         cmd = get_cmd_ptr(argv[1], &handler);
 463         if (!cmd) {
 464                 free(handler);
 465                 return -E_BAD_CMD;
 466         }
 467         perms = cmd_perms_itohuman(cmd->perms);
 468         ret = send_va_buffer(fd,
 469                 "%s - %s\n\n"
 470                 "handler: %s\n"
 471                 "permissions: %s\n"
 472                 "usage: %s\n\n"
 473                 "%s\n",
 474                 argv[1],
 475                 cmd->description,
 476                 handler,
 477                 perms,
 478                 cmd->usage,
 479                 cmd->help
 480         );
 481         free(perms);
 482         free(handler);
 483         return ret;
 484 }
 485
 486 /* hup */
 487 int com_hup(__a_unused int fd, int argc, __a_unused char * const * argv)
 488 {
 489         if (argc != 1)
 490                 return -E_COMMAND_SYNTAX;
 491         kill(getppid(), SIGHUP);
 492         return 1;
 493 }
 494
 495 /* term */
 496 int com_term(__a_unused int fd, int argc, __a_unused char * const * argv)
 497 {
 498         if (argc != 1)
 499                 return -E_COMMAND_SYNTAX;
 500         kill(getppid(), SIGTERM);
 501         return 1;
 502 }
 503
 504 int com_play(__a_unused int fd, int argc, __a_unused char * const * argv)
 505 {
 506         if (argc != 1)
 507                 return -E_COMMAND_SYNTAX;
 508         mutex_lock(mmd_mutex);
 509         mmd->new_vss_status_flags |= VSS_PLAYING;
 510         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 511         mutex_unlock(mmd_mutex);
 512         return 1;
 513
 514 }
 515
 516 /* stop */
 517 int com_stop(__a_unused int fd, int argc, __a_unused char * const * argv)
 518 {
 519         if (argc != 1)
 520                 return -E_COMMAND_SYNTAX;
 521         mutex_lock(mmd_mutex);
 522         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 523         mmd->new_vss_status_flags &= ~VSS_REPOS;
 524         mmd->new_vss_status_flags |= VSS_NEXT;
 525         mutex_unlock(mmd_mutex);
 526         return 1;
 527 }
 528
 529 /* pause */
 530 int com_pause(__a_unused int fd, int argc, __a_unused char * const * argv)
 531 {
 532         if (argc != 1)
 533                 return -E_COMMAND_SYNTAX;
 534         mutex_lock(mmd_mutex);
 535         if (!vss_paused() && !vss_stopped()) {
 536                 mmd->events++;
 537                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 538                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 539         }
 540         mutex_unlock(mmd_mutex);
 541         return 1;
 542 }
 543
 544 /* next */
 545 int com_next(__a_unused int fd, int argc, __a_unused char * const * argv)
 546 {
 547         if (argc != 1)
 548                 return -E_COMMAND_SYNTAX;
 549         mutex_lock(mmd_mutex);
 550         mmd->events++;
 551         mmd->new_vss_status_flags |= VSS_NEXT;
 552         mutex_unlock(mmd_mutex);
 553         return 1;
 554 }
 555
 556 /* nomore */
 557 int com_nomore(__a_unused int fd, int argc, __a_unused char * const * argv)
 558 {
 559         if (argc != 1)
 560                 return -E_COMMAND_SYNTAX;
 561         mutex_lock(mmd_mutex);
 562         if (vss_playing() || vss_paused())
 563                 mmd->new_vss_status_flags |= VSS_NOMORE;
 564         mutex_unlock(mmd_mutex);
 565         return 1;
 566 }
 567
 568 /* ff */
 569 int com_ff(__a_unused int fd, int argc, char * const * argv)
 570 {
 571         long promille;
 572         int ret, backwards = 0;
 573         unsigned i;
 574         char c;
 575
 576         if (argc != 2)
 577                 return -E_COMMAND_SYNTAX;
 578         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 579                 return -E_COMMAND_SYNTAX;
 580         if (ret > 1 && c == '-')
 581                 backwards = 1; /* jmp backwards */
 582         mutex_lock(mmd_mutex);
 583         ret = -E_NO_AUDIO_FILE;
 584         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 585                 goto out;
 586         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 587         if (backwards)
 588                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 589         else
 590                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 591         if (promille < 0)
 592                 promille = 0;
 593         if (promille >  1000) {
 594                 mmd->new_vss_status_flags |= VSS_NEXT;
 595                 goto out;
 596         }
 597         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 598         mmd->new_vss_status_flags |= VSS_REPOS;
 599         mmd->new_vss_status_flags &= ~VSS_NEXT;
 600         mmd->events++;
 601         ret = 1;
 602 out:
 603         mutex_unlock(mmd_mutex);
 604         return ret;
 605 }
 606
 607 /* jmp */
 608 int com_jmp(__a_unused int fd, int argc, char * const * argv)
 609 {
 610         long unsigned int i;
 611         int ret;
 612
 613         if (argc != 2)
 614                 return -E_COMMAND_SYNTAX;
 615         if (sscanf(argv[1], "%lu", &i) <= 0)
 616                 return -E_COMMAND_SYNTAX;
 617         mutex_lock(mmd_mutex);
 618         ret = -E_NO_AUDIO_FILE;
 619         if (!mmd->afd.afhi.chunks_total)
 620                 goto out;
 621         if (i > 100)
 622                 i = 100;
 623         PARA_INFO_LOG("jumping to %lu%%\n", i);
 624         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 625         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 626                 mmd->chunks_sent, mmd->offset);
 627         mmd->new_vss_status_flags |= VSS_REPOS;
 628         mmd->new_vss_status_flags &= ~VSS_NEXT;
 629         ret = 1;
 630         mmd->events++;
 631 out:
 632         mutex_unlock(mmd_mutex);
 633         return ret;
 634 }
 635
 636 /*
 637  * check if perms are sufficient to exec a command having perms cmd_perms.
 638  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 639  */
 640 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 641 {
 642         PARA_DEBUG_LOG("checking permissions\n");
 643         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 644 }
 645
 646 /*
 647  * Parse first string from *cmd and lookup in table of valid commands.
 648  * On error, NULL is returned.
 649  */
 650 static struct server_command *parse_cmd(const char *cmdstr)
 651 {
 652         char buf[255];
 653         int n = 0;
 654
 655         sscanf(cmdstr, "%200s%n", buf, &n);
 656         if (!n)
 657                 return NULL;
 658         buf[n] = '\0';
 659         return get_cmd_ptr(buf, NULL);
 660 }
 661
 662 static void init_rc4_keys(void)
 663 {
 664         int i;
 665
 666         for (i = 0; i < 2 * RC4_KEY_LEN; i++)
 667                 rc4_buf[i] = para_random(256);
 668         PARA_DEBUG_LOG("rc4 keys initialized (%u:%u)\n",
 669                 (unsigned char) rc4_buf[0],
 670                 (unsigned char) rc4_buf[RC4_KEY_LEN]);
 671         RC4_set_key(&rc4_recv_key, RC4_KEY_LEN, rc4_buf);
 672         RC4_set_key(&rc4_send_key, RC4_KEY_LEN, rc4_buf + RC4_KEY_LEN);
 673 }
 674
 675 static void rc4_recv(unsigned long len, const unsigned char *indata,
 676                 unsigned char *outdata, __a_unused void *private_data)
 677 {
 678         RC4(&rc4_recv_key, len, indata, outdata);
 679 }
 680
 681 static void rc4_send(unsigned long len, const unsigned char *indata,
 682                 unsigned char *outdata, __a_unused void *private_data)
 683 {
 684         RC4(&rc4_send_key, len, indata, outdata);
 685 }
 686
 687 static int read_command(int fd, char **result)
 688 {
 689         int ret;
 690         char buf[4096];
 691         char *command = NULL;
 692
 693         for (;;) {
 694                 size_t numbytes;
 695                 char *p;
 696
 697                 ret = recv_buffer(fd, buf, sizeof(buf));
 698                 if (ret < 0)
 699                         goto out;
 700                 if (!ret)
 701                         break;
 702                 numbytes = ret;
 703                 ret = -E_COMMAND_SYNTAX;
 704                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 705                         goto out;
 706                 command = para_strcat(command, buf);
 707                 p = strstr(command, EOC_MSG);
 708                 if (p) {
 709                         *p = '\0';
 710                         break;
 711                 }
 712         }
 713         ret = command? 1 : -E_COMMAND_SYNTAX;
 714 out:
 715         if (ret < 0)
 716                 free(command);
 717         else
 718                 *result = command;
 719         return ret;
 720
 721 }
 722
 723 static void reset_signals(void)
 724 {
 725         para_sigaction(SIGCHLD, SIG_IGN);
 726         para_sigaction(SIGINT, SIG_DFL);
 727         para_sigaction(SIGTERM, SIG_DFL);
 728         para_sigaction(SIGHUP, SIG_DFL);
 729 }
 730
 731 /**
 732  * Perform user authentication and execute a command.
 733  *
 734  * \param fd The file descriptor to send output to.
 735  * \param peername Identifies the connecting peer.
 736  *
 737  * Whenever para_server accepts an incoming tcp connection on
 738  * the port it listens on, it forks and the resulting child
 739  * calls this function.
 740  *
 741  * An RSA-based challenge/response is used to authenticate
 742  * the peer. It that authentication succeeds, a random RC4
 743  * session key is generated and sent back to the peer,
 744  * encrypted with its RSA public key.  From this point on,
 745  * all transfers are crypted with this session key.
 746  *
 747  * Next it is checked if the peer supplied  a valid server command or a command
 748  * for the audio file selector.  If yes, and if the user has sufficient
 749  * permissions to execute that command, the function calls the corresponding
 750  * command handler which does argument checking and further processing.
 751  *
 752  * In order to cope with a DOS attacks, a timeout is set up
 753  * which terminates the function if the connection was not
 754  * authenticated when the timeout expires.
 755  *
 756  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 757  */
 758 __noreturn void handle_connect(int fd, const char *peername)
 759 {
 760         int ret, argc, use_rc4 = 0;
 761         char buf[4096];
 762         unsigned char crypt_buf[MAXLINE];
 763         struct user *u;
 764         struct server_command *cmd = NULL;
 765         long unsigned challenge_nr, chall_response;
 766         char **argv = NULL;
 767         char *p, *command = NULL;
 768         size_t numbytes;
 769
 770         reset_signals();
 771         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 772         ret = mark_fd_blocking(fd);
 773         if (ret < 0)
 774                 goto err_out;
 775         challenge_nr = random();
 776         /* send Welcome message */
 777         ret = send_va_buffer(fd, "This is para_server, version "
 778                 PACKAGE_VERSION  ".\n" );
 779         if (ret < 0)
 780                 goto err_out;
 781         /* recv auth request line */
 782         ret = recv_buffer(fd, buf, sizeof(buf));
 783         if (ret < 0)
 784                 goto err_out;
 785         if (ret <= 6) {
 786                 ret = -E_AUTH;
 787                 goto err_out;
 788         }
 789         numbytes = ret;
 790         ret = -E_AUTH;
 791         if (strncmp(buf, "auth ", 5))
 792                 goto err_out;
 793
 794         if (numbytes < 9 || strncmp(buf, "auth rc4 ", 9))
 795                 p = buf + 5; /* client version < 0.2.6 */
 796         else {
 797                 p = buf + 9; /* client version >= 0.2.6 */
 798                 use_rc4 = 1;
 799         }
 800         PARA_DEBUG_LOG("received %s request for user %s\n",
 801                 use_rc4? "rc4" : "auth", p);
 802         ret = -E_BAD_USER;
 803         u = lookup_user(p);
 804         if (!u)
 805                 goto err_out;
 806         ret = para_encrypt_challenge(u->rsa, challenge_nr, crypt_buf);
 807         if (ret <= 0)
 808                 goto err_out;
 809         numbytes = ret;
 810         PARA_DEBUG_LOG("sending %zu byte challenge\n", numbytes);
 811         /* We can't use send_buffer here since buf may contain null bytes */
 812         ret = send_bin_buffer(fd,(char *) crypt_buf, numbytes);
 813         if (ret < 0)
 814                 goto net_err;
 815         /* recv decrypted number */
 816         ret = recv_buffer(fd, buf, sizeof(buf));
 817         if (ret < 0)
 818                 goto net_err;
 819         numbytes = ret;
 820         ret = -E_AUTH;
 821         if (!numbytes)
 822                 goto net_err;
 823         if (sscanf(buf, CHALLENGE_RESPONSE_MSG "%lu", &chall_response) < 1
 824                         || chall_response != challenge_nr)
 825                 goto err_out;
 826         /* auth successful, send 'Proceed' message */
 827         PARA_INFO_LOG("good auth for %s (%lu)\n", u->name, challenge_nr);
 828         sprintf(buf, "%s", PROCEED_MSG);
 829         if (use_rc4) {
 830                 init_rc4_keys();
 831                 ret = para_encrypt_buffer(u->rsa, rc4_buf, 2 * RC4_KEY_LEN,
 832                         (unsigned char *)buf + PROCEED_MSG_LEN + 1);
 833                 if (ret <= 0)
 834                         goto err_out;
 835                 numbytes = ret + strlen(PROCEED_MSG) + 1;
 836         } else
 837                 numbytes = strlen(buf);
 838         ret = send_bin_buffer(fd, buf, numbytes);
 839         if (ret < 0)
 840                 goto net_err;
 841         if (use_rc4)
 842                 enable_crypt(fd, rc4_recv, rc4_send, NULL);
 843         ret = read_command(fd, &command);
 844         if (ret == -E_COMMAND_SYNTAX)
 845                 goto err_out;
 846         if (ret < 0)
 847                 goto net_err;
 848         ret = -E_BAD_CMD;
 849         cmd = parse_cmd(command);
 850         if (!cmd)
 851                 goto err_out;
 852         /* valid command, check permissions */
 853         ret = check_perms(u->perms, cmd);
 854         if (ret < 0)
 855                 goto err_out;
 856         /* valid command and sufficient perms */
 857         alarm(0);
 858         argc = split_args(command, &argv, "\n");
 859         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 860                         peername);
 861         ret = cmd->handler(fd, argc, argv);
 862         mutex_lock(mmd_mutex);
 863         mmd->num_commands++;
 864         mutex_unlock(mmd_mutex);
 865         if (ret >= 0)
 866                 goto out;
 867 err_out:
 868         send_va_buffer(fd, "%s\n", para_strerror(-ret));
 869 net_err:
 870         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 871 out:
 872         free(command);
 873         free(argv);
 874         mutex_lock(mmd_mutex);
 875         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 876                 mmd->events++;
 877         mmd->active_connections--;
 878         mutex_unlock(mmd_mutex);
 879         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 880 }