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, *sender_list = 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                 sender_list = para_strcat(sender_list, senders[i].name);
 247                 sender_list = para_strcat(sender_list, " ");
 248         }
 249         ut = uptime_str();
 250         ret = rc4_send_va_buffer(rc4c, "up: %s\nplayed: %u\n"
 251                 "server_pid: %d\n"
 252                 "afs_pid: %d\n"
 253                 "connections (active/accepted/total): %u/%u/%u\n"
 254                 "current loglevel: %s\n"
 255                 "supported audio formats: %s\n"
 256                 "supported senders: %s\n"
 257                 "%s",
 258                 ut, mmd->num_played,
 259                 (int)getppid(),
 260                 (int)mmd->afs_pid,
 261                 mmd->active_connections,
 262                 mmd->num_commands,
 263                 mmd->num_connects,
 264                 conf.loglevel_arg,
 265                 supported_audio_formats(),
 266                 sender_list,
 267                 sender_info
 268         );
 269         mutex_unlock(mmd_mutex);
 270         free(ut);
 271         free(sender_list);
 272         free(sender_info);
 273         return ret;
 274 }
 275
 276 /* version */
 277 int com_version(struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 278 {
 279         if (argc != 1)
 280                 return -E_COMMAND_SYNTAX;
 281         return rc4_send_buffer(rc4c, VERSION_TEXT("server")
 282                 "built: " BUILD_DATE "\n"
 283                 UNAME_RS ", " CC_VERSION "\n"
 284         );
 285 }
 286
 287 #define EMPTY_STATUS_ITEMS \
 288         ITEM(PATH) \
 289         ITEM(DIRECTORY) \
 290         ITEM(BASENAME) \
 291         ITEM(SCORE) \
 292         ITEM(ATTRIBUTES_BITMAP) \
 293         ITEM(ATTRIBUTES_TXT) \
 294         ITEM(HASH) \
 295         ITEM(IMAGE_ID) \
 296         ITEM(IMAGE_NAME) \
 297         ITEM(LYRICS_ID) \
 298         ITEM(LYRICS_NAME) \
 299         ITEM(BITRATE) \
 300         ITEM(FORMAT) \
 301         ITEM(FREQUENCY) \
 302         ITEM(CHANNELS) \
 303         ITEM(DURATION) \
 304         ITEM(SECONDS_TOTAL) \
 305         ITEM(NUM_PLAYED) \
 306         ITEM(LAST_PLAYED) \
 307         ITEM(TECHINFO) \
 308         ITEM(ARTIST) \
 309         ITEM(TITLE) \
 310         ITEM(YEAR) \
 311         ITEM(ALBUM) \
 312         ITEM(COMMENT) \
 313         ITEM(AMPLIFICATION)
 314
 315 /**
 316  * Write a list of audio-file related status items with empty values.
 317  *
 318  * This is used by vss when currently no audio file is open.
 319  */
 320 static char *empty_status_items(int parser_friendly)
 321 {
 322         if (parser_friendly)
 323                 return make_message(
 324                         #define ITEM(x) "0004 %02x:\n"
 325                         EMPTY_STATUS_ITEMS
 326                         #undef ITEM
 327                         #define ITEM(x) , SI_ ## x
 328                         EMPTY_STATUS_ITEMS
 329                         #undef ITEM
 330                 );
 331         return make_message(
 332                 #define ITEM(x) "%s:\n"
 333                 EMPTY_STATUS_ITEMS
 334                 #undef ITEM
 335                 #define ITEM(x) ,status_item_list[SI_ ## x]
 336                 EMPTY_STATUS_ITEMS
 337                 #undef ITEM
 338         );
 339 }
 340 #undef EMPTY_STATUS_ITEMS
 341
 342 /* stat */
 343 int com_stat(struct rc4_context *rc4c, int argc, char * const * argv)
 344 {
 345         int i, ret;
 346         struct misc_meta_data tmp, *nmmd = &tmp;
 347         char *s;
 348         int32_t num = 0;
 349         int parser_friendly = 0;
 350
 351         para_sigaction(SIGUSR1, dummy);
 352
 353         for (i = 1; i < argc; i++) {
 354                 const char *arg = argv[i];
 355                 if (arg[0] != '-')
 356                         break;
 357                 if (!strcmp(arg, "--")) {
 358                         i++;
 359                         break;
 360                 }
 361                 if (!strncmp(arg, "-n=", 3)) {
 362                         ret = para_atoi32(arg + 3, &num);
 363                         if (ret < 0)
 364                                 return ret;
 365                         continue;
 366                 }
 367                 if (!strcmp(arg, "-p")) {
 368                         parser_friendly = 1;
 369                         continue;
 370                 }
 371                 return -E_COMMAND_SYNTAX;
 372         }
 373         if (i != argc)
 374                 return -E_COMMAND_SYNTAX;
 375         for (;;) {
 376                 mmd_dup(nmmd);
 377                 s = get_status(nmmd, parser_friendly);
 378                 ret = rc4_send_buffer(rc4c, s);
 379                 free(s);
 380                 if (ret < 0)
 381                         goto out;
 382                 if (nmmd->vss_status_flags & VSS_NEXT) {
 383                         static char *esi;
 384                         if (!esi)
 385                                 esi = empty_status_items(parser_friendly);
 386                         ret = rc4_send_buffer(rc4c, esi);
 387                         if (ret < 0)
 388                                 goto out;
 389                 } else
 390                         send_afs_status(rc4c, parser_friendly);
 391                 ret = 1;
 392                 if (num > 0 && !--num)
 393                         goto out;
 394                 sleep(50);
 395                 if (getppid() == 1)
 396                         return -E_SERVER_CRASH;
 397         }
 398 out:
 399         return ret;
 400 }
 401
 402 static int send_list_of_commands(struct rc4_context *rc4c, struct server_command *cmd,
 403                 const char *handler)
 404 {
 405         int ret, i;
 406
 407         for (i = 1; cmd->name; cmd++, i++) {
 408                 char *perms = cmd_perms_itohuman(cmd->perms);
 409                 ret = rc4_send_va_buffer(rc4c, "%s\t%s\t%s\t%s\n", cmd->name,
 410                         handler,
 411                         perms,
 412                         cmd->description);
 413                 free(perms);
 414                 if (ret < 0)
 415                         return ret;
 416         }
 417         return 1;
 418 }
 419
 420 /* returns string that must be freed by the caller */
 421 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 422 {
 423         struct server_command *cmd;
 424
 425         for (cmd = server_cmds; cmd->name; cmd++)
 426                 if (!strcmp(cmd->name, name)) {
 427                         if (handler)
 428                                 *handler = para_strdup("server"); /* server commands */
 429                         return cmd;
 430                 }
 431         /* not found, look for commands supported by afs */
 432         for (cmd = afs_cmds; cmd->name; cmd++)
 433                 if (!strcmp(cmd->name, name)) {
 434                         if (handler)
 435                                 *handler = para_strdup("afs");
 436                         return cmd;
 437                 }
 438         return NULL;
 439 }
 440
 441 /* help */
 442 int com_help(struct rc4_context *rc4c, int argc, char * const * argv)
 443 {
 444         struct server_command *cmd;
 445         char *perms, *handler;
 446         int ret;
 447
 448         if (argc < 2) {
 449                 /* no argument given, print list of commands */
 450                 if ((ret = send_list_of_commands(rc4c, server_cmds, "server")) < 0)
 451                         return ret;
 452                 return send_list_of_commands(rc4c, afs_cmds, "afs");
 453         }
 454         /* argument given for help */
 455         cmd = get_cmd_ptr(argv[1], &handler);
 456         if (!cmd) {
 457                 free(handler);
 458                 return -E_BAD_CMD;
 459         }
 460         perms = cmd_perms_itohuman(cmd->perms);
 461         ret = rc4_send_va_buffer(rc4c,
 462                 "%s - %s\n\n"
 463                 "handler: %s\n"
 464                 "permissions: %s\n"
 465                 "usage: %s\n\n"
 466                 "%s\n",
 467                 argv[1],
 468                 cmd->description,
 469                 handler,
 470                 perms,
 471                 cmd->usage,
 472                 cmd->help
 473         );
 474         free(perms);
 475         free(handler);
 476         return ret;
 477 }
 478
 479 /* hup */
 480 int com_hup(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 481 {
 482         if (argc != 1)
 483                 return -E_COMMAND_SYNTAX;
 484         kill(getppid(), SIGHUP);
 485         return 1;
 486 }
 487
 488 /* term */
 489 int com_term(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 490 {
 491         if (argc != 1)
 492                 return -E_COMMAND_SYNTAX;
 493         kill(getppid(), SIGTERM);
 494         return 1;
 495 }
 496
 497 int com_play(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 498 {
 499         if (argc != 1)
 500                 return -E_COMMAND_SYNTAX;
 501         mutex_lock(mmd_mutex);
 502         mmd->new_vss_status_flags |= VSS_PLAYING;
 503         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 504         mutex_unlock(mmd_mutex);
 505         return 1;
 506
 507 }
 508
 509 /* stop */
 510 int com_stop(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 511 {
 512         if (argc != 1)
 513                 return -E_COMMAND_SYNTAX;
 514         mutex_lock(mmd_mutex);
 515         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 516         mmd->new_vss_status_flags &= ~VSS_REPOS;
 517         mmd->new_vss_status_flags |= VSS_NEXT;
 518         mutex_unlock(mmd_mutex);
 519         return 1;
 520 }
 521
 522 /* pause */
 523 int com_pause(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 524 {
 525         if (argc != 1)
 526                 return -E_COMMAND_SYNTAX;
 527         mutex_lock(mmd_mutex);
 528         if (!vss_paused() && !vss_stopped()) {
 529                 mmd->events++;
 530                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 531                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 532         }
 533         mutex_unlock(mmd_mutex);
 534         return 1;
 535 }
 536
 537 /* next */
 538 int com_next(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 539 {
 540         if (argc != 1)
 541                 return -E_COMMAND_SYNTAX;
 542         mutex_lock(mmd_mutex);
 543         mmd->events++;
 544         mmd->new_vss_status_flags |= VSS_NEXT;
 545         mutex_unlock(mmd_mutex);
 546         return 1;
 547 }
 548
 549 /* nomore */
 550 int com_nomore(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 551 {
 552         if (argc != 1)
 553                 return -E_COMMAND_SYNTAX;
 554         mutex_lock(mmd_mutex);
 555         if (vss_playing() || vss_paused())
 556                 mmd->new_vss_status_flags |= VSS_NOMORE;
 557         mutex_unlock(mmd_mutex);
 558         return 1;
 559 }
 560
 561 /* ff */
 562 int com_ff(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 563 {
 564         long promille;
 565         int ret, backwards = 0;
 566         unsigned i;
 567         char c;
 568
 569         if (argc != 2)
 570                 return -E_COMMAND_SYNTAX;
 571         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 572                 return -E_COMMAND_SYNTAX;
 573         if (ret > 1 && c == '-')
 574                 backwards = 1; /* jmp backwards */
 575         mutex_lock(mmd_mutex);
 576         ret = -E_NO_AUDIO_FILE;
 577         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 578                 goto out;
 579         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 580         if (backwards)
 581                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 582         else
 583                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 584         if (promille < 0)
 585                 promille = 0;
 586         if (promille >  1000) {
 587                 mmd->new_vss_status_flags |= VSS_NEXT;
 588                 goto out;
 589         }
 590         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 591         mmd->new_vss_status_flags |= VSS_REPOS;
 592         mmd->new_vss_status_flags &= ~VSS_NEXT;
 593         mmd->events++;
 594         ret = 1;
 595 out:
 596         mutex_unlock(mmd_mutex);
 597         return ret;
 598 }
 599
 600 /* jmp */
 601 int com_jmp(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 602 {
 603         long unsigned int i;
 604         int ret;
 605
 606         if (argc != 2)
 607                 return -E_COMMAND_SYNTAX;
 608         if (sscanf(argv[1], "%lu", &i) <= 0)
 609                 return -E_COMMAND_SYNTAX;
 610         mutex_lock(mmd_mutex);
 611         ret = -E_NO_AUDIO_FILE;
 612         if (!mmd->afd.afhi.chunks_total)
 613                 goto out;
 614         if (i > 100)
 615                 i = 100;
 616         PARA_INFO_LOG("jumping to %lu%%\n", i);
 617         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 618         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 619                 mmd->chunks_sent, mmd->offset);
 620         mmd->new_vss_status_flags |= VSS_REPOS;
 621         mmd->new_vss_status_flags &= ~VSS_NEXT;
 622         ret = 1;
 623         mmd->events++;
 624 out:
 625         mutex_unlock(mmd_mutex);
 626         return ret;
 627 }
 628
 629 /*
 630  * check if perms are sufficient to exec a command having perms cmd_perms.
 631  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 632  */
 633 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 634 {
 635         PARA_DEBUG_LOG("checking permissions\n");
 636         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 637 }
 638
 639 /*
 640  * Parse first string from *cmd and lookup in table of valid commands.
 641  * On error, NULL is returned.
 642  */
 643 static struct server_command *parse_cmd(const char *cmdstr)
 644 {
 645         char buf[255];
 646         int n = 0;
 647
 648         sscanf(cmdstr, "%200s%n", buf, &n);
 649         if (!n)
 650                 return NULL;
 651         buf[n] = '\0';
 652         return get_cmd_ptr(buf, NULL);
 653 }
 654
 655 static int read_command(struct rc4_context *rc4c, char **result)
 656 {
 657         int ret;
 658         char buf[4096];
 659         char *command = NULL;
 660
 661         for (;;) {
 662                 size_t numbytes;
 663                 char *p;
 664
 665                 ret = rc4_recv_buffer(rc4c, buf, sizeof(buf));
 666                 if (ret < 0)
 667                         goto out;
 668                 if (!ret)
 669                         break;
 670                 numbytes = ret;
 671                 ret = -E_COMMAND_SYNTAX;
 672                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 673                         goto out;
 674                 command = para_strcat(command, buf);
 675                 p = strstr(command, EOC_MSG);
 676                 if (p) {
 677                         *p = '\0';
 678                         break;
 679                 }
 680         }
 681         ret = command? 1 : -E_COMMAND_SYNTAX;
 682 out:
 683         if (ret < 0)
 684                 free(command);
 685         else
 686                 *result = command;
 687         return ret;
 688
 689 }
 690
 691 static void reset_signals(void)
 692 {
 693         para_sigaction(SIGCHLD, SIG_IGN);
 694         para_sigaction(SIGINT, SIG_DFL);
 695         para_sigaction(SIGTERM, SIG_DFL);
 696         para_sigaction(SIGHUP, SIG_DFL);
 697 }
 698
 699 /**
 700  * Perform user authentication and execute a command.
 701  *
 702  * \param fd The file descriptor to send output to.
 703  * \param peername Identifies the connecting peer.
 704  *
 705  * Whenever para_server accepts an incoming tcp connection on
 706  * the port it listens on, it forks and the resulting child
 707  * calls this function.
 708  *
 709  * An RSA-based challenge/response is used to authenticate
 710  * the peer. It that authentication succeeds, a random RC4
 711  * session key is generated and sent back to the peer,
 712  * encrypted with its RSA public key.  From this point on,
 713  * all transfers are crypted with this session key.
 714  *
 715  * Next it is checked if the peer supplied  a valid server command or a command
 716  * for the audio file selector.  If yes, and if the user has sufficient
 717  * permissions to execute that command, the function calls the corresponding
 718  * command handler which does argument checking and further processing.
 719  *
 720  * In order to cope with a DOS attacks, a timeout is set up
 721  * which terminates the function if the connection was not
 722  * authenticated when the timeout expires.
 723  *
 724  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 725  */
 726 __noreturn void handle_connect(int fd, const char *peername)
 727 {
 728         int ret, argc;
 729         char buf[4096];
 730         unsigned char rand_buf[CHALLENGE_SIZE + 2 * RC4_KEY_LEN];
 731         unsigned char challenge_sha1[HASH_SIZE];
 732         struct user *u;
 733         struct server_command *cmd = NULL;
 734         char **argv = NULL;
 735         char *p, *command = NULL;
 736         size_t numbytes;
 737         struct rc4_context rc4c = {.fd = fd};
 738
 739         reset_signals();
 740         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 741         ret = mark_fd_blocking(fd);
 742         if (ret < 0)
 743                 goto err_out;
 744         /* send Welcome message */
 745         ret = send_va_buffer(fd, "This is para_server, version "
 746                 PACKAGE_VERSION  ".\n" );
 747         if (ret < 0)
 748                 goto err_out;
 749         /* recv auth request line */
 750         ret = recv_buffer(fd, buf, sizeof(buf));
 751         if (ret < 0)
 752                 goto err_out;
 753         if (ret < 10) {
 754                 ret = -E_AUTH_REQUEST;
 755                 goto err_out;
 756         }
 757         numbytes = ret;
 758         ret = -E_AUTH_REQUEST;
 759         if (strncmp(buf, AUTH_REQUEST_MSG, strlen(AUTH_REQUEST_MSG)))
 760                 goto err_out;
 761         p = buf + strlen(AUTH_REQUEST_MSG);
 762         PARA_DEBUG_LOG("received auth request for user %s\n", p);
 763         ret = -E_BAD_USER;
 764         u = lookup_user(p);
 765         if (u) {
 766                 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
 767                 ret = para_encrypt_buffer(u->rsa, rand_buf, sizeof(rand_buf),
 768                         (unsigned char *)buf);
 769                 if (ret < 0)
 770                         goto err_out;
 771                 numbytes = ret;
 772         } else {
 773                 /*
 774                  * We don't want to reveal our user names, so we send a
 775                  * challenge to the client even if the user does not exist, and
 776                  * fail the authentication later.
 777                  */
 778                 numbytes = 256;
 779                 get_random_bytes_or_die((unsigned char *)buf, numbytes);
 780         }
 781         PARA_DEBUG_LOG("sending %u byte challenge + rc4 keys (%zu bytes)\n",
 782                 CHALLENGE_SIZE, numbytes);
 783         ret = send_bin_buffer(fd, buf, numbytes);
 784         if (ret < 0)
 785                 goto net_err;
 786         /* recv challenge response */
 787         ret = recv_bin_buffer(fd, buf, HASH_SIZE);
 788         if (ret < 0)
 789                 goto net_err;
 790         numbytes = ret;
 791         PARA_DEBUG_LOG("received %d bytes challenge response\n", ret);
 792         ret = -E_BAD_USER;
 793         if (!u)
 794                 goto net_err;
 795         /*
 796          * The correct response is the sha1 of the first CHALLENGE_SIZE bytes
 797          * of the random data.
 798          */
 799         ret = -E_BAD_AUTH;
 800         if (numbytes != HASH_SIZE)
 801                 goto net_err;
 802         sha1_hash((char *)rand_buf, CHALLENGE_SIZE, challenge_sha1);
 803         if (memcmp(challenge_sha1, buf, HASH_SIZE))
 804                 goto net_err;
 805         /* auth successful */
 806         alarm(0);
 807         PARA_INFO_LOG("good auth for %s\n", u->name);
 808         /* init rc4 keys with the second part of the random buffer */
 809         RC4_set_key(&rc4c.recv_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE);
 810         RC4_set_key(&rc4c.send_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE
 811                 + RC4_KEY_LEN);
 812         ret = rc4_send_buffer(&rc4c, PROCEED_MSG);
 813         if (ret < 0)
 814                 goto net_err;
 815         ret = read_command(&rc4c, &command);
 816         if (ret == -E_COMMAND_SYNTAX)
 817                 goto err_out;
 818         if (ret < 0)
 819                 goto net_err;
 820         ret = -E_BAD_CMD;
 821         cmd = parse_cmd(command);
 822         if (!cmd)
 823                 goto err_out;
 824         /* valid command, check permissions */
 825         ret = check_perms(u->perms, cmd);
 826         if (ret < 0)
 827                 goto err_out;
 828         /* valid command and sufficient perms */
 829         ret = create_argv(command, "\n", &argv);
 830         if (ret < 0)
 831                 goto err_out;
 832         argc = ret;
 833         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 834                         peername);
 835         ret = cmd->handler(&rc4c, argc, argv);
 836         free_argv(argv);
 837         mutex_lock(mmd_mutex);
 838         mmd->num_commands++;
 839         mutex_unlock(mmd_mutex);
 840         if (ret >= 0)
 841                 goto out;
 842 err_out:
 843         rc4_send_va_buffer(&rc4c, "%s\n", para_strerror(-ret));
 844 net_err:
 845         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 846 out:
 847         free(command);
 848         mutex_lock(mmd_mutex);
 849         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 850                 mmd->events++;
 851         mmd->active_connections--;
 852         mutex_unlock(mmd_mutex);
 853         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 854 }