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 <regex.h>
  10 #include <signal.h>
  11 #include <sys/time.h>
  12 #include <sys/types.h>
  13 #include <dirent.h>
  14 #include <openssl/rc4.h>
  15 #include <osl.h>
  16
  17 #include "para.h"
  18 #include "error.h"
  19 #include "crypt.h"
  20 #include "command.h"
  21 #include "server.cmdline.h"
  22 #include "string.h"
  23 #include "afh.h"
  24 #include "afs.h"
  25 #include "server.h"
  26 #include "vss.h"
  27 #include "list.h"
  28 #include "send.h"
  29 #include "rc4.h"
  30 #include "net.h"
  31 #include "daemon.h"
  32 #include "fd.h"
  33 #include "ipc.h"
  34 #include "user_list.h"
  35 #include "server_command_list.h"
  36 #include "afs_command_list.h"
  37 #include "sched.h"
  38 #include "signal.h"
  39
  40 /** Commands including options must be shorter than this. */
  41 #define MAX_COMMAND_LEN 32768
  42
  43 extern int mmd_mutex;
  44 extern struct misc_meta_data *mmd;
  45 extern struct sender senders[];
  46 int send_afs_status(struct rc4_context *rc4c, int parser_friendly);
  47
  48 const char *status_item_list[] = {STATUS_ITEM_ARRAY};
  49
  50 static void dummy(__a_unused int s)
  51 {
  52 }
  53
  54 static void mmd_dup(struct misc_meta_data *new_mmd)
  55 {
  56         mutex_lock(mmd_mutex);
  57         *new_mmd = *mmd;
  58         mutex_unlock(mmd_mutex);
  59 }
  60
  61 /*
  62  * Compute human readable string containing vss status for given integer value.
  63  *
  64  * We don't want to use vss_playing() and friends here because we take a
  65  * snapshot of the mmd struct and use the copy for computing the state of the
  66  * vss. If the real data were used, we would take the mmd lock for a rather
  67  * long time or risk to get an inconsistent view.
  68  */
  69 static char *vss_status_tohuman(unsigned int flags)
  70 {
  71         if (flags & VSS_PLAYING)
  72                 return para_strdup("playing");
  73         if (flags & VSS_NEXT)
  74                 return para_strdup("stopped");
  75         return para_strdup("paused");
  76 }
  77
  78 /*
  79  * return human readable permission string. Never returns NULL.
  80  */
  81 static char *cmd_perms_itohuman(unsigned int perms)
  82 {
  83         char *msg = para_malloc(5 * sizeof(char));
  84
  85         msg[0] = perms & AFS_READ? 'a' : '-';
  86         msg[1] = perms & AFS_WRITE? 'A' : '-';
  87         msg[2] = perms & VSS_READ? 'v' : '-';
  88         msg[3] = perms & VSS_WRITE? 'V' : '-';
  89         msg[4] = '\0';
  90         return msg;
  91 }
  92
  93 /*
  94  * Never returns NULL.
  95  */
  96 static char *vss_get_status_flags(unsigned int flags)
  97 {
  98         char *msg = para_malloc(5 * sizeof(char));
  99
 100         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
 101         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
 102         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
 103         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
 104         msg[4] = '\0';
 105         return msg;
 106 }
 107
 108 static char *get_status(struct misc_meta_data *nmmd, int parser_friendly)
 109 {
 110         char mtime[30] = "";
 111         char *status, *flags; /* vss status info */
 112         char *ut = uptime_str();
 113         long offset = (nmmd->offset + 500) / 1000;
 114         struct timeval current_time;
 115         struct tm mtime_tm;
 116         struct para_buffer b = {.flags = parser_friendly? PBF_SIZE_PREFIX : 0};
 117
 118         /* report real status */
 119         status = vss_status_tohuman(nmmd->vss_status_flags);
 120         flags = vss_get_status_flags(nmmd->vss_status_flags);
 121         if (nmmd->size) { /* parent currently has an audio file open */
 122                 localtime_r(&nmmd->mtime, &mtime_tm);
 123                 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
 124         }
 125         gettimeofday(&current_time, NULL);
 126         WRITE_STATUS_ITEM(&b, SI_FILE_SIZE, "%zu\n", nmmd->size / 1024);
 127         WRITE_STATUS_ITEM(&b, SI_MTIME, "%s\n", mtime);
 128         WRITE_STATUS_ITEM(&b, SI_STATUS, "%s\n", status);
 129         WRITE_STATUS_ITEM(&b, SI_STATUS_FLAGS, "%s\n", flags);
 130         WRITE_STATUS_ITEM(&b, SI_OFFSET, "%li\n", offset);
 131         WRITE_STATUS_ITEM(&b, SI_AFS_MODE, "%s\n", mmd->afs_mode_string);
 132         WRITE_STATUS_ITEM(&b, SI_STREAM_START, "%lu.%lu\n",
 133                 (long unsigned)nmmd->stream_start.tv_sec,
 134                 (long unsigned)nmmd->stream_start.tv_usec);
 135         WRITE_STATUS_ITEM(&b, SI_CURRENT_TIME, "%lu.%lu\n",
 136                 (long unsigned)current_time.tv_sec,
 137                 (long unsigned)current_time.tv_usec);
 138         free(flags);
 139         free(status);
 140         free(ut);
 141         return b.buf;
 142 }
 143
 144 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 145 {
 146         int i;
 147         /* this has to match sender.h */
 148         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 149
 150         scd->sender_num = -1;
 151         if (argc < 2)
 152                 return -E_COMMAND_SYNTAX;
 153         for (i = 0; senders[i].name; i++)
 154                 if (!strcmp(senders[i].name, argv[1]))
 155                         break;
 156         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 157         if (!senders[i].name)
 158                 return -E_COMMAND_SYNTAX;
 159         scd->sender_num = i;
 160         for (i = 0; subcmds[i]; i++)
 161                 if (!strcmp(subcmds[i], argv[2]))
 162                         break;
 163         if (!subcmds[i])
 164                 return -E_COMMAND_SYNTAX;
 165         scd->cmd_num = i;
 166         if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
 167                 return -E_SENDER_CMD;
 168         switch (scd->cmd_num) {
 169         case SENDER_ON:
 170         case SENDER_OFF:
 171                 if (argc != 3)
 172                         return -E_COMMAND_SYNTAX;
 173                 break;
 174         case SENDER_DENY:
 175         case SENDER_ALLOW:
 176                 if (argc != 4 || parse_cidr(argv[3], scd->host,
 177                                 sizeof(scd->host), &scd->netmask) == NULL)
 178                         return -E_COMMAND_SYNTAX;
 179                 break;
 180         case SENDER_ADD:
 181         case SENDER_DELETE:
 182                 if (argc != 4)
 183                         return -E_COMMAND_SYNTAX;
 184                 return parse_fec_url(argv[3], scd);
 185         default:
 186                 return -E_COMMAND_SYNTAX;
 187         }
 188         return 1;
 189 }
 190
 191 int com_sender(struct rc4_context *rc4c, int argc, char * const * argv)
 192 {
 193         int i, ret;
 194         struct sender_command_data scd;
 195
 196         if (argc < 2) {
 197                 char *msg = NULL;
 198                 for (i = 0; senders[i].name; i++) {
 199                         char *tmp = make_message("%s%s\n",
 200                                 msg? msg : "", senders[i].name);
 201                         free(msg);
 202                         msg = tmp;
 203                 }
 204                 ret = rc4_send_buffer(rc4c, msg);
 205                 free(msg);
 206                 return ret;
 207         }
 208         ret = check_sender_args(argc, argv, &scd);
 209         if (ret < 0) {
 210                 char *msg;
 211                 if (scd.sender_num < 0)
 212                         return ret;
 213                 msg = senders[scd.sender_num].help();
 214                 ret = rc4_send_buffer(rc4c, msg);
 215                 free(msg);
 216                 return ret;
 217         }
 218         for (i = 0; i < 10; i++) {
 219                 mutex_lock(mmd_mutex);
 220                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 221                         mutex_unlock(mmd_mutex);
 222                         usleep(100 * 1000);
 223                         continue;
 224                 }
 225                 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
 226                 mutex_unlock(mmd_mutex);
 227                 break;
 228         }
 229         return (i < 10)? 1 : -E_LOCK;
 230 }
 231
 232 /* server info */
 233 int com_si(struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 234 {
 235         int i, ret;
 236         char *ut;
 237         char *sender_info = NULL;
 238
 239         if (argc != 1)
 240                 return -E_COMMAND_SYNTAX;
 241         mutex_lock(mmd_mutex);
 242         for (i = 0; senders[i].name; i++) {
 243                 char *info = senders[i].info();
 244                 sender_info = para_strcat(sender_info, info);
 245                 free(info);
 246         }
 247         ut = uptime_str();
 248         ret = rc4_send_va_buffer(rc4c, "up: %s\nplayed: %u\n"
 249                 "server_pid: %d\n"
 250                 "afs_pid: %d\n"
 251                 "connections (active/accepted/total): %u/%u/%u\n"
 252                 "current loglevel: %s\n"
 253                 "supported audio formats: %s\n"
 254                 "%s",
 255                 ut, mmd->num_played,
 256                 (int)getppid(),
 257                 (int)mmd->afs_pid,
 258                 mmd->active_connections,
 259                 mmd->num_commands,
 260                 mmd->num_connects,
 261                 conf.loglevel_arg,
 262                 supported_audio_formats(),
 263                 sender_info
 264         );
 265         mutex_unlock(mmd_mutex);
 266         free(ut);
 267         free(sender_info);
 268         return ret;
 269 }
 270
 271 /* version */
 272 int com_version(struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 273 {
 274         if (argc != 1)
 275                 return -E_COMMAND_SYNTAX;
 276         return rc4_send_buffer(rc4c, VERSION_TEXT("server")
 277                 "built: " BUILD_DATE "\n"
 278                 UNAME_RS ", " CC_VERSION "\n"
 279         );
 280 }
 281
 282 #define EMPTY_STATUS_ITEMS \
 283         ITEM(PATH) \
 284         ITEM(DIRECTORY) \
 285         ITEM(BASENAME) \
 286         ITEM(SCORE) \
 287         ITEM(ATTRIBUTES_BITMAP) \
 288         ITEM(ATTRIBUTES_TXT) \
 289         ITEM(HASH) \
 290         ITEM(IMAGE_ID) \
 291         ITEM(IMAGE_NAME) \
 292         ITEM(LYRICS_ID) \
 293         ITEM(LYRICS_NAME) \
 294         ITEM(BITRATE) \
 295         ITEM(FORMAT) \
 296         ITEM(FREQUENCY) \
 297         ITEM(CHANNELS) \
 298         ITEM(DURATION) \
 299         ITEM(SECONDS_TOTAL) \
 300         ITEM(NUM_PLAYED) \
 301         ITEM(LAST_PLAYED) \
 302         ITEM(TECHINFO) \
 303         ITEM(ARTIST) \
 304         ITEM(TITLE) \
 305         ITEM(YEAR) \
 306         ITEM(ALBUM) \
 307         ITEM(COMMENT) \
 308         ITEM(AMPLIFICATION)
 309
 310 /**
 311  * Write a list of audio-file related status items with empty values.
 312  *
 313  * This is used by vss when currently no audio file is open.
 314  */
 315 static char *empty_status_items(int parser_friendly)
 316 {
 317         if (parser_friendly)
 318                 return make_message(
 319                         #define ITEM(x) "0004 %02x:\n"
 320                         EMPTY_STATUS_ITEMS
 321                         #undef ITEM
 322                         #define ITEM(x) , SI_ ## x
 323                         EMPTY_STATUS_ITEMS
 324                         #undef ITEM
 325                 );
 326         return make_message(
 327                 #define ITEM(x) "%s:\n"
 328                 EMPTY_STATUS_ITEMS
 329                 #undef ITEM
 330                 #define ITEM(x) ,status_item_list[SI_ ## x]
 331                 EMPTY_STATUS_ITEMS
 332                 #undef ITEM
 333         );
 334 }
 335 #undef EMPTY_STATUS_ITEMS
 336
 337 /* stat */
 338 int com_stat(struct rc4_context *rc4c, int argc, char * const * argv)
 339 {
 340         int i, ret;
 341         struct misc_meta_data tmp, *nmmd = &tmp;
 342         char *s;
 343         int32_t num = 0;
 344         int parser_friendly = 0;
 345
 346         para_sigaction(SIGUSR1, dummy);
 347
 348         for (i = 1; i < argc; i++) {
 349                 const char *arg = argv[i];
 350                 if (arg[0] != '-')
 351                         break;
 352                 if (!strcmp(arg, "--")) {
 353                         i++;
 354                         break;
 355                 }
 356                 if (!strncmp(arg, "-n=", 3)) {
 357                         ret = para_atoi32(arg + 3, &num);
 358                         if (ret < 0)
 359                                 return ret;
 360                         continue;
 361                 }
 362                 if (!strcmp(arg, "-p")) {
 363                         parser_friendly = 1;
 364                         continue;
 365                 }
 366                 return -E_COMMAND_SYNTAX;
 367         }
 368         if (i != argc)
 369                 return -E_COMMAND_SYNTAX;
 370         for (;;) {
 371                 mmd_dup(nmmd);
 372                 s = get_status(nmmd, parser_friendly);
 373                 ret = rc4_send_buffer(rc4c, s);
 374                 free(s);
 375                 if (ret < 0)
 376                         goto out;
 377                 if (nmmd->vss_status_flags & VSS_NEXT) {
 378                         static char *esi;
 379                         if (!esi)
 380                                 esi = empty_status_items(parser_friendly);
 381                         ret = rc4_send_buffer(rc4c, esi);
 382                         if (ret < 0)
 383                                 goto out;
 384                 } else
 385                         send_afs_status(rc4c, parser_friendly);
 386                 ret = 1;
 387                 if (num > 0 && !--num)
 388                         goto out;
 389                 sleep(50);
 390                 if (getppid() == 1)
 391                         return -E_SERVER_CRASH;
 392         }
 393 out:
 394         return ret;
 395 }
 396
 397 static int send_list_of_commands(struct rc4_context *rc4c, struct server_command *cmd,
 398                 const char *handler)
 399 {
 400         int ret, i;
 401
 402         for (i = 1; cmd->name; cmd++, i++) {
 403                 char *perms = cmd_perms_itohuman(cmd->perms);
 404                 ret = rc4_send_va_buffer(rc4c, "%s\t%s\t%s\t%s\n", cmd->name,
 405                         handler,
 406                         perms,
 407                         cmd->description);
 408                 free(perms);
 409                 if (ret < 0)
 410                         return ret;
 411         }
 412         return 1;
 413 }
 414
 415 /* returns string that must be freed by the caller */
 416 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 417 {
 418         struct server_command *cmd;
 419
 420         for (cmd = server_cmds; cmd->name; cmd++)
 421                 if (!strcmp(cmd->name, name)) {
 422                         if (handler)
 423                                 *handler = para_strdup("server"); /* server commands */
 424                         return cmd;
 425                 }
 426         /* not found, look for commands supported by afs */
 427         for (cmd = afs_cmds; cmd->name; cmd++)
 428                 if (!strcmp(cmd->name, name)) {
 429                         if (handler)
 430                                 *handler = para_strdup("afs");
 431                         return cmd;
 432                 }
 433         return NULL;
 434 }
 435
 436 /* help */
 437 int com_help(struct rc4_context *rc4c, int argc, char * const * argv)
 438 {
 439         struct server_command *cmd;
 440         char *perms, *handler;
 441         int ret;
 442
 443         if (argc < 2) {
 444                 /* no argument given, print list of commands */
 445                 if ((ret = send_list_of_commands(rc4c, server_cmds, "server")) < 0)
 446                         return ret;
 447                 return send_list_of_commands(rc4c, afs_cmds, "afs");
 448         }
 449         /* argument given for help */
 450         cmd = get_cmd_ptr(argv[1], &handler);
 451         if (!cmd) {
 452                 free(handler);
 453                 return -E_BAD_CMD;
 454         }
 455         perms = cmd_perms_itohuman(cmd->perms);
 456         ret = rc4_send_va_buffer(rc4c,
 457                 "%s - %s\n\n"
 458                 "handler: %s\n"
 459                 "permissions: %s\n"
 460                 "usage: %s\n\n"
 461                 "%s\n",
 462                 argv[1],
 463                 cmd->description,
 464                 handler,
 465                 perms,
 466                 cmd->usage,
 467                 cmd->help
 468         );
 469         free(perms);
 470         free(handler);
 471         return ret;
 472 }
 473
 474 /* hup */
 475 int com_hup(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 476 {
 477         if (argc != 1)
 478                 return -E_COMMAND_SYNTAX;
 479         kill(getppid(), SIGHUP);
 480         return 1;
 481 }
 482
 483 /* term */
 484 int com_term(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 485 {
 486         if (argc != 1)
 487                 return -E_COMMAND_SYNTAX;
 488         kill(getppid(), SIGTERM);
 489         return 1;
 490 }
 491
 492 int com_play(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 493 {
 494         if (argc != 1)
 495                 return -E_COMMAND_SYNTAX;
 496         mutex_lock(mmd_mutex);
 497         mmd->new_vss_status_flags |= VSS_PLAYING;
 498         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 499         mutex_unlock(mmd_mutex);
 500         return 1;
 501
 502 }
 503
 504 /* stop */
 505 int com_stop(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 506 {
 507         if (argc != 1)
 508                 return -E_COMMAND_SYNTAX;
 509         mutex_lock(mmd_mutex);
 510         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 511         mmd->new_vss_status_flags &= ~VSS_REPOS;
 512         mmd->new_vss_status_flags |= VSS_NEXT;
 513         mutex_unlock(mmd_mutex);
 514         return 1;
 515 }
 516
 517 /* pause */
 518 int com_pause(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 519 {
 520         if (argc != 1)
 521                 return -E_COMMAND_SYNTAX;
 522         mutex_lock(mmd_mutex);
 523         if (!vss_paused() && !vss_stopped()) {
 524                 mmd->events++;
 525                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 526                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 527         }
 528         mutex_unlock(mmd_mutex);
 529         return 1;
 530 }
 531
 532 /* next */
 533 int com_next(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 534 {
 535         if (argc != 1)
 536                 return -E_COMMAND_SYNTAX;
 537         mutex_lock(mmd_mutex);
 538         mmd->events++;
 539         mmd->new_vss_status_flags |= VSS_NEXT;
 540         mutex_unlock(mmd_mutex);
 541         return 1;
 542 }
 543
 544 /* nomore */
 545 int com_nomore(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 546 {
 547         if (argc != 1)
 548                 return -E_COMMAND_SYNTAX;
 549         mutex_lock(mmd_mutex);
 550         if (vss_playing() || vss_paused())
 551                 mmd->new_vss_status_flags |= VSS_NOMORE;
 552         mutex_unlock(mmd_mutex);
 553         return 1;
 554 }
 555
 556 /* ff */
 557 int com_ff(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 558 {
 559         long promille;
 560         int ret, backwards = 0;
 561         unsigned i;
 562         char c;
 563
 564         if (argc != 2)
 565                 return -E_COMMAND_SYNTAX;
 566         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 567                 return -E_COMMAND_SYNTAX;
 568         if (ret > 1 && c == '-')
 569                 backwards = 1; /* jmp backwards */
 570         mutex_lock(mmd_mutex);
 571         ret = -E_NO_AUDIO_FILE;
 572         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 573                 goto out;
 574         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 575         if (backwards)
 576                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 577         else
 578                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 579         if (promille < 0)
 580                 promille = 0;
 581         if (promille >  1000) {
 582                 mmd->new_vss_status_flags |= VSS_NEXT;
 583                 goto out;
 584         }
 585         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 586         mmd->new_vss_status_flags |= VSS_REPOS;
 587         mmd->new_vss_status_flags &= ~VSS_NEXT;
 588         mmd->events++;
 589         ret = 1;
 590 out:
 591         mutex_unlock(mmd_mutex);
 592         return ret;
 593 }
 594
 595 /* jmp */
 596 int com_jmp(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 597 {
 598         long unsigned int i;
 599         int ret;
 600
 601         if (argc != 2)
 602                 return -E_COMMAND_SYNTAX;
 603         if (sscanf(argv[1], "%lu", &i) <= 0)
 604                 return -E_COMMAND_SYNTAX;
 605         mutex_lock(mmd_mutex);
 606         ret = -E_NO_AUDIO_FILE;
 607         if (!mmd->afd.afhi.chunks_total)
 608                 goto out;
 609         if (i > 100)
 610                 i = 100;
 611         PARA_INFO_LOG("jumping to %lu%%\n", i);
 612         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 613         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 614                 mmd->chunks_sent, mmd->offset);
 615         mmd->new_vss_status_flags |= VSS_REPOS;
 616         mmd->new_vss_status_flags &= ~VSS_NEXT;
 617         ret = 1;
 618         mmd->events++;
 619 out:
 620         mutex_unlock(mmd_mutex);
 621         return ret;
 622 }
 623
 624 /*
 625  * check if perms are sufficient to exec a command having perms cmd_perms.
 626  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 627  */
 628 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 629 {
 630         PARA_DEBUG_LOG("checking permissions\n");
 631         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 632 }
 633
 634 /*
 635  * Parse first string from *cmd and lookup in table of valid commands.
 636  * On error, NULL is returned.
 637  */
 638 static struct server_command *parse_cmd(const char *cmdstr)
 639 {
 640         char buf[255];
 641         int n = 0;
 642
 643         sscanf(cmdstr, "%200s%n", buf, &n);
 644         if (!n)
 645                 return NULL;
 646         buf[n] = '\0';
 647         return get_cmd_ptr(buf, NULL);
 648 }
 649
 650 static int read_command(struct rc4_context *rc4c, char **result)
 651 {
 652         int ret;
 653         char buf[4096];
 654         char *command = NULL;
 655
 656         for (;;) {
 657                 size_t numbytes;
 658                 char *p;
 659
 660                 ret = rc4_recv_buffer(rc4c, buf, sizeof(buf));
 661                 if (ret < 0)
 662                         goto out;
 663                 if (!ret)
 664                         break;
 665                 numbytes = ret;
 666                 ret = -E_COMMAND_SYNTAX;
 667                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 668                         goto out;
 669                 command = para_strcat(command, buf);
 670                 p = strstr(command, EOC_MSG);
 671                 if (p) {
 672                         *p = '\0';
 673                         break;
 674                 }
 675         }
 676         ret = command? 1 : -E_COMMAND_SYNTAX;
 677 out:
 678         if (ret < 0)
 679                 free(command);
 680         else
 681                 *result = command;
 682         return ret;
 683
 684 }
 685
 686 static void reset_signals(void)
 687 {
 688         para_sigaction(SIGCHLD, SIG_IGN);
 689         para_sigaction(SIGINT, SIG_DFL);
 690         para_sigaction(SIGTERM, SIG_DFL);
 691         para_sigaction(SIGHUP, SIG_DFL);
 692 }
 693
 694 /**
 695  * Perform user authentication and execute a command.
 696  *
 697  * \param fd The file descriptor to send output to.
 698  * \param peername Identifies the connecting peer.
 699  *
 700  * Whenever para_server accepts an incoming tcp connection on
 701  * the port it listens on, it forks and the resulting child
 702  * calls this function.
 703  *
 704  * An RSA-based challenge/response is used to authenticate
 705  * the peer. It that authentication succeeds, a random RC4
 706  * session key is generated and sent back to the peer,
 707  * encrypted with its RSA public key.  From this point on,
 708  * all transfers are crypted with this session key.
 709  *
 710  * Next it is checked if the peer supplied  a valid server command or a command
 711  * for the audio file selector.  If yes, and if the user has sufficient
 712  * permissions to execute that command, the function calls the corresponding
 713  * command handler which does argument checking and further processing.
 714  *
 715  * In order to cope with a DOS attacks, a timeout is set up
 716  * which terminates the function if the connection was not
 717  * authenticated when the timeout expires.
 718  *
 719  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 720  */
 721 __noreturn void handle_connect(int fd, const char *peername)
 722 {
 723         int ret, argc;
 724         char buf[4096];
 725         unsigned char rand_buf[CHALLENGE_SIZE + 2 * RC4_KEY_LEN];
 726         unsigned char challenge_sha1[HASH_SIZE];
 727         struct user *u;
 728         struct server_command *cmd = NULL;
 729         char **argv = NULL;
 730         char *p, *command = NULL;
 731         size_t numbytes;
 732         struct rc4_context rc4c = {.fd = fd};
 733
 734         reset_signals();
 735         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 736         ret = mark_fd_blocking(fd);
 737         if (ret < 0)
 738                 goto err_out;
 739         /* send Welcome message */
 740         ret = send_va_buffer(fd, "This is para_server, version "
 741                 PACKAGE_VERSION  ".\n" );
 742         if (ret < 0)
 743                 goto err_out;
 744         /* recv auth request line */
 745         ret = recv_buffer(fd, buf, sizeof(buf));
 746         if (ret < 0)
 747                 goto err_out;
 748         if (ret < 10) {
 749                 ret = -E_AUTH_REQUEST;
 750                 goto err_out;
 751         }
 752         numbytes = ret;
 753         ret = -E_AUTH_REQUEST;
 754         if (strncmp(buf, AUTH_REQUEST_MSG, strlen(AUTH_REQUEST_MSG)))
 755                 goto err_out;
 756         p = buf + strlen(AUTH_REQUEST_MSG);
 757         PARA_DEBUG_LOG("received auth request for user %s\n", p);
 758         ret = -E_BAD_USER;
 759         u = lookup_user(p);
 760         if (u) {
 761                 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
 762                 ret = para_encrypt_buffer(u->rsa, rand_buf, sizeof(rand_buf),
 763                         (unsigned char *)buf);
 764                 if (ret < 0)
 765                         goto err_out;
 766                 numbytes = ret;
 767         } else {
 768                 /*
 769                  * We don't want to reveal our user names, so we send a
 770                  * challenge to the client even if the user does not exist, and
 771                  * fail the authentication later.
 772                  */
 773                 numbytes = 256;
 774                 get_random_bytes_or_die((unsigned char *)buf, numbytes);
 775         }
 776         PARA_DEBUG_LOG("sending %u byte challenge + rc4 keys (%zu bytes)\n",
 777                 CHALLENGE_SIZE, numbytes);
 778         ret = send_bin_buffer(fd, buf, numbytes);
 779         if (ret < 0)
 780                 goto net_err;
 781         /* recv challenge response */
 782         ret = recv_bin_buffer(fd, buf, HASH_SIZE);
 783         if (ret < 0)
 784                 goto net_err;
 785         numbytes = ret;
 786         PARA_DEBUG_LOG("received %d bytes challenge response\n", ret);
 787         ret = -E_BAD_USER;
 788         if (!u)
 789                 goto net_err;
 790         /*
 791          * The correct response is the sha1 of the first CHALLENGE_SIZE bytes
 792          * of the random data.
 793          */
 794         ret = -E_BAD_AUTH;
 795         if (numbytes != HASH_SIZE)
 796                 goto net_err;
 797         sha1_hash((char *)rand_buf, CHALLENGE_SIZE, challenge_sha1);
 798         if (memcmp(challenge_sha1, buf, HASH_SIZE))
 799                 goto net_err;
 800         /* auth successful */
 801         alarm(0);
 802         PARA_INFO_LOG("good auth for %s\n", u->name);
 803         /* init rc4 keys with the second part of the random buffer */
 804         RC4_set_key(&rc4c.recv_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE);
 805         RC4_set_key(&rc4c.send_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE
 806                 + RC4_KEY_LEN);
 807         ret = rc4_send_buffer(&rc4c, PROCEED_MSG);
 808         if (ret < 0)
 809                 goto net_err;
 810         ret = read_command(&rc4c, &command);
 811         if (ret == -E_COMMAND_SYNTAX)
 812                 goto err_out;
 813         if (ret < 0)
 814                 goto net_err;
 815         ret = -E_BAD_CMD;
 816         cmd = parse_cmd(command);
 817         if (!cmd)
 818                 goto err_out;
 819         /* valid command, check permissions */
 820         ret = check_perms(u->perms, cmd);
 821         if (ret < 0)
 822                 goto err_out;
 823         /* valid command and sufficient perms */
 824         ret = create_argv(command, "\n", &argv);
 825         if (ret < 0)
 826                 goto err_out;
 827         argc = ret;
 828         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 829                         peername);
 830         ret = cmd->handler(&rc4c, argc, argv);
 831         free_argv(argv);
 832         mutex_lock(mmd_mutex);
 833         mmd->num_commands++;
 834         mutex_unlock(mmd_mutex);
 835         if (ret >= 0)
 836                 goto out;
 837 err_out:
 838         rc4_send_va_buffer(&rc4c, "%s\n", para_strerror(-ret));
 839 net_err:
 840         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 841 out:
 842         free(command);
 843         mutex_lock(mmd_mutex);
 844         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 845                 mmd->events++;
 846         mmd->active_connections--;
 847         mutex_unlock(mmd_mutex);
 848         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 849 }