command.c

   1 /*
   2  * Copyright (C) 1997-2011 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 <osl.h>
  14 #include <stdbool.h>
  15
  16 #include "para.h"
  17 #include "error.h"
  18 #include "crypt.h"
  19 #include "command.h"
  20 #include "server.cmdline.h"
  21 #include "string.h"
  22 #include "afh.h"
  23 #include "afs.h"
  24 #include "server.h"
  25 #include "list.h"
  26 #include "send.h"
  27 #include "vss.h"
  28 #include "net.h"
  29 #include "daemon.h"
  30 #include "fd.h"
  31 #include "ipc.h"
  32 #include "user_list.h"
  33 #include "server_command_list.h"
  34 #include "afs_command_list.h"
  35 #include "sched.h"
  36 #include "signal.h"
  37 #include "version.h"
  38
  39 /** Commands including options must be shorter than this. */
  40 #define MAX_COMMAND_LEN 32768
  41
  42 extern int mmd_mutex;
  43 extern struct misc_meta_data *mmd;
  44 extern struct sender senders[];
  45 int send_afs_status(struct stream_cipher_context *scc, int parser_friendly);
  46
  47 const char *status_item_list[] = {STATUS_ITEM_ARRAY};
  48
  49 static void dummy(__a_unused int s)
  50 {
  51 }
  52
  53 static void mmd_dup(struct misc_meta_data *new_mmd)
  54 {
  55         mutex_lock(mmd_mutex);
  56         *new_mmd = *mmd;
  57         mutex_unlock(mmd_mutex);
  58 }
  59
  60 /*
  61  * Compute human readable string containing vss status for given integer value.
  62  *
  63  * We don't want to use vss_playing() and friends here because we take a
  64  * snapshot of the mmd struct and use the copy for computing the state of the
  65  * vss. If the real data were used, we would take the mmd lock for a rather
  66  * long time or risk to get an inconsistent view.
  67  */
  68 static char *vss_status_tohuman(unsigned int flags)
  69 {
  70         if (flags & VSS_PLAYING)
  71                 return para_strdup("playing");
  72         if (flags & VSS_NEXT)
  73                 return para_strdup("stopped");
  74         return para_strdup("paused");
  75 }
  76
  77 /*
  78  * return human readable permission string. Never returns NULL.
  79  */
  80 static char *cmd_perms_itohuman(unsigned int perms)
  81 {
  82         char *msg = para_malloc(5 * sizeof(char));
  83
  84         msg[0] = perms & AFS_READ? 'a' : '-';
  85         msg[1] = perms & AFS_WRITE? 'A' : '-';
  86         msg[2] = perms & VSS_READ? 'v' : '-';
  87         msg[3] = perms & VSS_WRITE? 'V' : '-';
  88         msg[4] = '\0';
  89         return msg;
  90 }
  91
  92 /*
  93  * Never returns NULL.
  94  */
  95 static char *vss_get_status_flags(unsigned int flags)
  96 {
  97         char *msg = para_malloc(5 * sizeof(char));
  98
  99         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
 100         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
 101         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
 102         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
 103         msg[4] = '\0';
 104         return msg;
 105 }
 106
 107 static char *get_status(struct misc_meta_data *nmmd, int parser_friendly)
 108 {
 109         char mtime[30] = "";
 110         char *status, *flags; /* vss status info */
 111         char *ut = uptime_str();
 112         long offset = (nmmd->offset + 500) / 1000;
 113         struct timeval current_time;
 114         struct tm mtime_tm;
 115         struct para_buffer b = {.flags = parser_friendly? PBF_SIZE_PREFIX : 0};
 116
 117         /* report real status */
 118         status = vss_status_tohuman(nmmd->vss_status_flags);
 119         flags = vss_get_status_flags(nmmd->vss_status_flags);
 120         if (nmmd->size) { /* parent currently has an audio file open */
 121                 localtime_r(&nmmd->mtime, &mtime_tm);
 122                 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
 123         }
 124         gettimeofday(&current_time, NULL);
 125         WRITE_STATUS_ITEM(&b, SI_FILE_SIZE, "%zu\n", nmmd->size / 1024);
 126         WRITE_STATUS_ITEM(&b, SI_MTIME, "%s\n", mtime);
 127         WRITE_STATUS_ITEM(&b, SI_STATUS, "%s\n", status);
 128         WRITE_STATUS_ITEM(&b, SI_STATUS_FLAGS, "%s\n", flags);
 129         WRITE_STATUS_ITEM(&b, SI_OFFSET, "%li\n", offset);
 130         WRITE_STATUS_ITEM(&b, SI_AFS_MODE, "%s\n", mmd->afs_mode_string);
 131         WRITE_STATUS_ITEM(&b, SI_STREAM_START, "%lu.%lu\n",
 132                 (long unsigned)nmmd->stream_start.tv_sec,
 133                 (long unsigned)nmmd->stream_start.tv_usec);
 134         WRITE_STATUS_ITEM(&b, SI_CURRENT_TIME, "%lu.%lu\n",
 135                 (long unsigned)current_time.tv_sec,
 136                 (long unsigned)current_time.tv_usec);
 137         free(flags);
 138         free(status);
 139         free(ut);
 140         return b.buf;
 141 }
 142
 143 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 144 {
 145         int i;
 146         /* this has to match sender.h */
 147         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 148
 149         scd->sender_num = -1;
 150         if (argc < 2)
 151                 return -E_COMMAND_SYNTAX;
 152         for (i = 0; senders[i].name; i++)
 153                 if (!strcmp(senders[i].name, argv[1]))
 154                         break;
 155         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 156         if (!senders[i].name)
 157                 return -E_COMMAND_SYNTAX;
 158         scd->sender_num = i;
 159         for (i = 0; subcmds[i]; i++)
 160                 if (!strcmp(subcmds[i], argv[2]))
 161                         break;
 162         if (!subcmds[i])
 163                 return -E_COMMAND_SYNTAX;
 164         scd->cmd_num = i;
 165         if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
 166                 return -E_SENDER_CMD;
 167         switch (scd->cmd_num) {
 168         case SENDER_ON:
 169         case SENDER_OFF:
 170                 if (argc != 3)
 171                         return -E_COMMAND_SYNTAX;
 172                 break;
 173         case SENDER_DENY:
 174         case SENDER_ALLOW:
 175                 if (argc != 4 || parse_cidr(argv[3], scd->host,
 176                                 sizeof(scd->host), &scd->netmask) == NULL)
 177                         return -E_COMMAND_SYNTAX;
 178                 break;
 179         case SENDER_ADD:
 180         case SENDER_DELETE:
 181                 if (argc != 4)
 182                         return -E_COMMAND_SYNTAX;
 183                 return parse_fec_url(argv[3], scd);
 184         default:
 185                 return -E_COMMAND_SYNTAX;
 186         }
 187         return 1;
 188 }
 189
 190 int com_sender(struct stream_cipher_context *scc, int argc, char * const * argv)
 191 {
 192         int i, ret;
 193         char *msg = NULL;
 194         struct sender_command_data scd;
 195
 196         if (argc < 2) {
 197                 for (i = 0; senders[i].name; i++) {
 198                         char *tmp = make_message("%s%s\n",
 199                                 msg? msg : "", senders[i].name);
 200                         free(msg);
 201                         msg = tmp;
 202                 }
 203                 ret = sc_send_buffer(scc, msg);
 204                 free(msg);
 205                 return ret;
 206         }
 207         ret = check_sender_args(argc, argv, &scd);
 208         if (ret < 0) {
 209                 if (scd.sender_num < 0)
 210                         return ret;
 211                 msg = senders[scd.sender_num].help();
 212                 ret = sc_send_buffer(scc, msg);
 213                 free(msg);
 214                 return ret;
 215         }
 216
 217         switch (scd.cmd_num) {
 218         case SENDER_ADD:
 219         case SENDER_DELETE:
 220                 assert(senders[scd.sender_num].resolve_target);
 221                 ret = senders[scd.sender_num].resolve_target(argv[3], &scd);
 222                 if (ret < 0)
 223                         return ret;
 224         }
 225
 226         for (i = 0; i < 10; i++) {
 227                 mutex_lock(mmd_mutex);
 228                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 229                         mutex_unlock(mmd_mutex);
 230                         usleep(100 * 1000);
 231                         continue;
 232                 }
 233                 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
 234                 mutex_unlock(mmd_mutex);
 235                 break;
 236         }
 237         return (i < 10)? 1 : -E_LOCK;
 238 }
 239
 240 /* server info */
 241 int com_si(struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 242 {
 243         int i, ret;
 244         char *ut;
 245         char *sender_info = NULL;
 246
 247         if (argc != 1)
 248                 return -E_COMMAND_SYNTAX;
 249         mutex_lock(mmd_mutex);
 250         for (i = 0; senders[i].name; i++) {
 251                 char *info = senders[i].info();
 252                 sender_info = para_strcat(sender_info, info);
 253                 free(info);
 254         }
 255         ut = uptime_str();
 256         ret = sc_send_va_buffer(scc, "version: " GIT_VERSION "\n"
 257                 "up: %s\nplayed: %u\n"
 258                 "server_pid: %d\n"
 259                 "afs_pid: %d\n"
 260                 "connections (active/accepted/total): %u/%u/%u\n"
 261                 "current loglevel: %s\n"
 262                 "supported audio formats: %s\n"
 263                 "%s",
 264                 ut, mmd->num_played,
 265                 (int)getppid(),
 266                 (int)mmd->afs_pid,
 267                 mmd->active_connections,
 268                 mmd->num_commands,
 269                 mmd->num_connects,
 270                 conf.loglevel_arg,
 271                 SERVER_AUDIO_FORMATS,
 272                 sender_info
 273         );
 274         mutex_unlock(mmd_mutex);
 275         free(ut);
 276         free(sender_info);
 277         return ret;
 278 }
 279
 280 /* version */
 281 int com_version(struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 282 {
 283         if (argc != 1)
 284                 return -E_COMMAND_SYNTAX;
 285         return sc_send_buffer(scc, VERSION_TEXT("server")
 286                 "built: " BUILD_DATE "\n"
 287                 UNAME_RS ", " CC_VERSION "\n"
 288         );
 289 }
 290
 291 #define EMPTY_STATUS_ITEMS \
 292         ITEM(PATH) \
 293         ITEM(DIRECTORY) \
 294         ITEM(BASENAME) \
 295         ITEM(SCORE) \
 296         ITEM(ATTRIBUTES_BITMAP) \
 297         ITEM(ATTRIBUTES_TXT) \
 298         ITEM(HASH) \
 299         ITEM(IMAGE_ID) \
 300         ITEM(IMAGE_NAME) \
 301         ITEM(LYRICS_ID) \
 302         ITEM(LYRICS_NAME) \
 303         ITEM(BITRATE) \
 304         ITEM(FORMAT) \
 305         ITEM(FREQUENCY) \
 306         ITEM(CHANNELS) \
 307         ITEM(DURATION) \
 308         ITEM(SECONDS_TOTAL) \
 309         ITEM(NUM_PLAYED) \
 310         ITEM(LAST_PLAYED) \
 311         ITEM(TECHINFO) \
 312         ITEM(ARTIST) \
 313         ITEM(TITLE) \
 314         ITEM(YEAR) \
 315         ITEM(ALBUM) \
 316         ITEM(COMMENT) \
 317         ITEM(AMPLIFICATION)
 318
 319 /**
 320  * Write a list of audio-file related status items with empty values.
 321  *
 322  * This is used by vss when currently no audio file is open.
 323  */
 324 static char *empty_status_items(int parser_friendly)
 325 {
 326         if (parser_friendly)
 327                 return make_message(
 328                         #define ITEM(x) "0004 %02x:\n"
 329                         EMPTY_STATUS_ITEMS
 330                         #undef ITEM
 331                         #define ITEM(x) , SI_ ## x
 332                         EMPTY_STATUS_ITEMS
 333                         #undef ITEM
 334                 );
 335         return make_message(
 336                 #define ITEM(x) "%s:\n"
 337                 EMPTY_STATUS_ITEMS
 338                 #undef ITEM
 339                 #define ITEM(x) ,status_item_list[SI_ ## x]
 340                 EMPTY_STATUS_ITEMS
 341                 #undef ITEM
 342         );
 343 }
 344 #undef EMPTY_STATUS_ITEMS
 345
 346 /* stat */
 347 int com_stat(struct stream_cipher_context *scc, int argc, char * const * argv)
 348 {
 349         int i, ret;
 350         struct misc_meta_data tmp, *nmmd = &tmp;
 351         char *s;
 352         int32_t num = 0;
 353         int parser_friendly = 0;
 354
 355         para_sigaction(SIGUSR1, dummy);
 356
 357         for (i = 1; i < argc; i++) {
 358                 const char *arg = argv[i];
 359                 if (arg[0] != '-')
 360                         break;
 361                 if (!strcmp(arg, "--")) {
 362                         i++;
 363                         break;
 364                 }
 365                 if (!strncmp(arg, "-n=", 3)) {
 366                         ret = para_atoi32(arg + 3, &num);
 367                         if (ret < 0)
 368                                 return ret;
 369                         continue;
 370                 }
 371                 if (!strcmp(arg, "-p")) {
 372                         parser_friendly = 1;
 373                         continue;
 374                 }
 375                 return -E_COMMAND_SYNTAX;
 376         }
 377         if (i != argc)
 378                 return -E_COMMAND_SYNTAX;
 379         for (;;) {
 380                 mmd_dup(nmmd);
 381                 s = get_status(nmmd, parser_friendly);
 382                 ret = sc_send_buffer(scc, s);
 383                 free(s);
 384                 if (ret < 0)
 385                         goto out;
 386                 if (nmmd->vss_status_flags & VSS_NEXT) {
 387                         static char *esi;
 388                         if (!esi)
 389                                 esi = empty_status_items(parser_friendly);
 390                         ret = sc_send_buffer(scc, esi);
 391                         if (ret < 0)
 392                                 goto out;
 393                 } else
 394                         send_afs_status(scc, parser_friendly);
 395                 ret = 1;
 396                 if (num > 0 && !--num)
 397                         goto out;
 398                 sleep(50);
 399                 if (getppid() == 1)
 400                         return -E_SERVER_CRASH;
 401         }
 402 out:
 403         return ret;
 404 }
 405
 406 static int send_list_of_commands(struct stream_cipher_context *scc, struct server_command *cmd,
 407                 const char *handler)
 408 {
 409         int ret, i;
 410
 411         for (i = 1; cmd->name; cmd++, i++) {
 412                 char *perms = cmd_perms_itohuman(cmd->perms);
 413                 ret = sc_send_va_buffer(scc, "%s\t%s\t%s\t%s\n", cmd->name,
 414                         handler,
 415                         perms,
 416                         cmd->description);
 417                 free(perms);
 418                 if (ret < 0)
 419                         return ret;
 420         }
 421         return 1;
 422 }
 423
 424 /* returns string that must be freed by the caller */
 425 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 426 {
 427         struct server_command *cmd;
 428
 429         for (cmd = server_cmds; cmd->name; cmd++)
 430                 if (!strcmp(cmd->name, name)) {
 431                         if (handler)
 432                                 *handler = para_strdup("server"); /* server commands */
 433                         return cmd;
 434                 }
 435         /* not found, look for commands supported by afs */
 436         for (cmd = afs_cmds; cmd->name; cmd++)
 437                 if (!strcmp(cmd->name, name)) {
 438                         if (handler)
 439                                 *handler = para_strdup("afs");
 440                         return cmd;
 441                 }
 442         return NULL;
 443 }
 444
 445 /* help */
 446 int com_help(struct stream_cipher_context *scc, int argc, char * const * argv)
 447 {
 448         struct server_command *cmd;
 449         char *perms, *handler;
 450         int ret;
 451
 452         if (argc < 2) {
 453                 /* no argument given, print list of commands */
 454                 if ((ret = send_list_of_commands(scc, server_cmds, "server")) < 0)
 455                         return ret;
 456                 return send_list_of_commands(scc, afs_cmds, "afs");
 457         }
 458         /* argument given for help */
 459         cmd = get_cmd_ptr(argv[1], &handler);
 460         if (!cmd)
 461                 return -E_BAD_CMD;
 462         perms = cmd_perms_itohuman(cmd->perms);
 463         ret = sc_send_va_buffer(scc,
 464                 "%s - %s\n\n"
 465                 "handler: %s\n"
 466                 "permissions: %s\n"
 467                 "usage: %s\n\n"
 468                 "%s\n",
 469                 argv[1],
 470                 cmd->description,
 471                 handler,
 472                 perms,
 473                 cmd->usage,
 474                 cmd->help
 475         );
 476         free(perms);
 477         free(handler);
 478         return ret;
 479 }
 480
 481 /* hup */
 482 int com_hup(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 483 {
 484         if (argc != 1)
 485                 return -E_COMMAND_SYNTAX;
 486         kill(getppid(), SIGHUP);
 487         return 1;
 488 }
 489
 490 /* term */
 491 int com_term(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 492 {
 493         if (argc != 1)
 494                 return -E_COMMAND_SYNTAX;
 495         kill(getppid(), SIGTERM);
 496         return 1;
 497 }
 498
 499 int com_play(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 500 {
 501         if (argc != 1)
 502                 return -E_COMMAND_SYNTAX;
 503         mutex_lock(mmd_mutex);
 504         mmd->new_vss_status_flags |= VSS_PLAYING;
 505         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 506         mutex_unlock(mmd_mutex);
 507         return 1;
 508
 509 }
 510
 511 /* stop */
 512 int com_stop(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 513 {
 514         if (argc != 1)
 515                 return -E_COMMAND_SYNTAX;
 516         mutex_lock(mmd_mutex);
 517         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 518         mmd->new_vss_status_flags &= ~VSS_REPOS;
 519         mmd->new_vss_status_flags |= VSS_NEXT;
 520         mutex_unlock(mmd_mutex);
 521         return 1;
 522 }
 523
 524 /* pause */
 525 int com_pause(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 526 {
 527         if (argc != 1)
 528                 return -E_COMMAND_SYNTAX;
 529         mutex_lock(mmd_mutex);
 530         if (!vss_paused() && !vss_stopped()) {
 531                 mmd->events++;
 532                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 533                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 534         }
 535         mutex_unlock(mmd_mutex);
 536         return 1;
 537 }
 538
 539 /* next */
 540 int com_next(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 541 {
 542         if (argc != 1)
 543                 return -E_COMMAND_SYNTAX;
 544         mutex_lock(mmd_mutex);
 545         mmd->events++;
 546         mmd->new_vss_status_flags |= VSS_NEXT;
 547         mutex_unlock(mmd_mutex);
 548         return 1;
 549 }
 550
 551 /* nomore */
 552 int com_nomore(__a_unused struct stream_cipher_context *scc, int argc, __a_unused char * const * argv)
 553 {
 554         if (argc != 1)
 555                 return -E_COMMAND_SYNTAX;
 556         mutex_lock(mmd_mutex);
 557         if (vss_playing() || vss_paused())
 558                 mmd->new_vss_status_flags |= VSS_NOMORE;
 559         mutex_unlock(mmd_mutex);
 560         return 1;
 561 }
 562
 563 /* ff */
 564 int com_ff(__a_unused struct stream_cipher_context *scc, int argc, char * const * argv)
 565 {
 566         long promille;
 567         int ret, backwards = 0;
 568         unsigned i;
 569         char c;
 570
 571         if (argc != 2)
 572                 return -E_COMMAND_SYNTAX;
 573         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 574                 return -E_COMMAND_SYNTAX;
 575         if (ret > 1 && c == '-')
 576                 backwards = 1; /* jmp backwards */
 577         mutex_lock(mmd_mutex);
 578         ret = -E_NO_AUDIO_FILE;
 579         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 580                 goto out;
 581         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 582         if (backwards)
 583                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 584         else
 585                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 586         if (promille < 0)
 587                 promille = 0;
 588         if (promille >  1000) {
 589                 mmd->new_vss_status_flags |= VSS_NEXT;
 590                 goto out;
 591         }
 592         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 593         mmd->new_vss_status_flags |= VSS_REPOS;
 594         mmd->new_vss_status_flags &= ~VSS_NEXT;
 595         mmd->events++;
 596         ret = 1;
 597 out:
 598         mutex_unlock(mmd_mutex);
 599         return ret;
 600 }
 601
 602 /* jmp */
 603 int com_jmp(__a_unused struct stream_cipher_context *scc, int argc, char * const * argv)
 604 {
 605         long unsigned int i;
 606         int ret;
 607
 608         if (argc != 2)
 609                 return -E_COMMAND_SYNTAX;
 610         if (sscanf(argv[1], "%lu", &i) <= 0)
 611                 return -E_COMMAND_SYNTAX;
 612         mutex_lock(mmd_mutex);
 613         ret = -E_NO_AUDIO_FILE;
 614         if (!mmd->afd.afhi.chunks_total)
 615                 goto out;
 616         if (i > 100)
 617                 i = 100;
 618         PARA_INFO_LOG("jumping to %lu%%\n", i);
 619         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 620         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 621                 mmd->chunks_sent, mmd->offset);
 622         mmd->new_vss_status_flags |= VSS_REPOS;
 623         mmd->new_vss_status_flags &= ~VSS_NEXT;
 624         ret = 1;
 625         mmd->events++;
 626 out:
 627         mutex_unlock(mmd_mutex);
 628         return ret;
 629 }
 630
 631 /*
 632  * check if perms are sufficient to exec a command having perms cmd_perms.
 633  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 634  */
 635 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 636 {
 637         PARA_DEBUG_LOG("checking permissions\n");
 638         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 639 }
 640
 641 /*
 642  * Parse first string from *cmd and lookup in table of valid commands.
 643  * On error, NULL is returned.
 644  */
 645 static struct server_command *parse_cmd(const char *cmdstr)
 646 {
 647         char buf[255];
 648         int n = 0;
 649
 650         sscanf(cmdstr, "%200s%n", buf, &n);
 651         if (!n)
 652                 return NULL;
 653         buf[n] = '\0';
 654         return get_cmd_ptr(buf, NULL);
 655 }
 656
 657 static int read_command(struct stream_cipher_context *scc, char **result)
 658 {
 659         int ret;
 660         char buf[4096];
 661         char *command = NULL;
 662
 663         for (;;) {
 664                 size_t numbytes;
 665                 char *p;
 666
 667                 ret = sc_recv_buffer(scc, buf, sizeof(buf));
 668                 if (ret < 0)
 669                         goto out;
 670                 if (!ret)
 671                         break;
 672                 numbytes = ret;
 673                 ret = -E_COMMAND_SYNTAX;
 674                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 675                         goto out;
 676                 command = para_strcat(command, buf);
 677                 p = strstr(command, EOC_MSG);
 678                 if (p) {
 679                         *p = '\0';
 680                         break;
 681                 }
 682         }
 683         ret = command? 1 : -E_COMMAND_SYNTAX;
 684 out:
 685         if (ret < 0)
 686                 free(command);
 687         else
 688                 *result = command;
 689         return ret;
 690
 691 }
 692
 693 static void reset_signals(void)
 694 {
 695         para_sigaction(SIGCHLD, SIG_IGN);
 696         para_sigaction(SIGINT, SIG_DFL);
 697         para_sigaction(SIGTERM, SIG_DFL);
 698         para_sigaction(SIGHUP, SIG_DFL);
 699 }
 700
 701 /**
 702  * Perform user authentication and execute a command.
 703  *
 704  * \param fd The file descriptor to send output to.
 705  * \param peername Identifies the connecting peer.
 706  *
 707  * Whenever para_server accepts an incoming tcp connection on
 708  * the port it listens on, it forks and the resulting child
 709  * calls this function.
 710  *
 711  * An RSA-based challenge/response is used to authenticate
 712  * the peer. It that authentication succeeds, a random
 713  * session key is generated and sent back to the peer,
 714  * encrypted with its RSA public key.  From this point on,
 715  * all transfers are crypted with this session key.
 716  *
 717  * Next it is checked if the peer supplied  a valid server command or a command
 718  * for the audio file selector.  If yes, and if the user has sufficient
 719  * permissions to execute that command, the function calls the corresponding
 720  * command handler which does argument checking and further processing.
 721  *
 722  * In order to cope with a DOS attacks, a timeout is set up
 723  * which terminates the function if the connection was not
 724  * authenticated when the timeout expires.
 725  *
 726  * \sa alarm(2), crypt.c, crypt.h
 727  */
 728 __noreturn void handle_connect(int fd, const char *peername)
 729 {
 730         int ret, argc;
 731         char buf[4096];
 732         unsigned char rand_buf[CHALLENGE_SIZE + 2 * SESSION_KEY_LEN];
 733         unsigned char challenge_hash[HASH_SIZE];
 734         struct user *u;
 735         struct server_command *cmd = NULL;
 736         char **argv = NULL;
 737         char *p, *command = NULL;
 738         size_t numbytes;
 739         struct stream_cipher_context scc = {.fd = fd};
 740
 741         reset_signals();
 742         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 743         ret = mark_fd_blocking(fd);
 744         if (ret < 0)
 745                 goto net_err;
 746         /* send Welcome message */
 747         ret = send_va_buffer(fd, "This is para_server, version "
 748                 PACKAGE_VERSION  ".\n" );
 749         if (ret < 0)
 750                 goto net_err;
 751         /* recv auth request line */
 752         ret = recv_buffer(fd, buf, sizeof(buf));
 753         if (ret < 0)
 754                 goto net_err;
 755         if (ret < 10) {
 756                 ret = -E_AUTH_REQUEST;
 757                 goto net_err;
 758         }
 759         numbytes = ret;
 760         ret = -E_AUTH_REQUEST;
 761         if (strncmp(buf, AUTH_REQUEST_MSG, strlen(AUTH_REQUEST_MSG)))
 762                 goto net_err;
 763         p = buf + strlen(AUTH_REQUEST_MSG);
 764         PARA_DEBUG_LOG("received auth request for user %s\n", p);
 765         ret = -E_BAD_USER;
 766         u = lookup_user(p);
 767         if (u) {
 768                 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
 769                 ret = pub_encrypt(u->pubkey, rand_buf, sizeof(rand_buf),
 770                         (unsigned char *)buf);
 771                 if (ret < 0)
 772                         goto net_err;
 773                 numbytes = ret;
 774         } else {
 775                 /*
 776                  * We don't want to reveal our user names, so we send a
 777                  * challenge to the client even if the user does not exist, and
 778                  * fail the authentication later.
 779                  */
 780                 numbytes = 256;
 781                 get_random_bytes_or_die((unsigned char *)buf, numbytes);
 782         }
 783         PARA_DEBUG_LOG("sending %u byte challenge + rc4 keys (%zu bytes)\n",
 784                 CHALLENGE_SIZE, numbytes);
 785         ret = send_bin_buffer(fd, buf, numbytes);
 786         if (ret < 0)
 787                 goto net_err;
 788         /* recv challenge response */
 789         ret = recv_bin_buffer(fd, buf, HASH_SIZE);
 790         if (ret < 0)
 791                 goto net_err;
 792         numbytes = ret;
 793         PARA_DEBUG_LOG("received %d bytes challenge response\n", ret);
 794         ret = -E_BAD_USER;
 795         if (!u)
 796                 goto net_err;
 797         /*
 798          * The correct response is the hash of the first CHALLENGE_SIZE bytes
 799          * of the random data.
 800          */
 801         ret = -E_BAD_AUTH;
 802         if (numbytes != HASH_SIZE)
 803                 goto net_err;
 804         hash_function((char *)rand_buf, CHALLENGE_SIZE, challenge_hash);
 805         if (memcmp(challenge_hash, buf, HASH_SIZE))
 806                 goto net_err;
 807         /* auth successful */
 808         alarm(0);
 809         PARA_INFO_LOG("good auth for %s\n", u->name);
 810         /* init stream cipher keys with the second part of the random buffer */
 811         scc.recv = sc_new(rand_buf + CHALLENGE_SIZE, SESSION_KEY_LEN);
 812         scc.send = sc_new(rand_buf + CHALLENGE_SIZE + SESSION_KEY_LEN, SESSION_KEY_LEN);
 813         ret = sc_send_buffer(&scc, PROCEED_MSG);
 814         if (ret < 0)
 815                 goto net_err;
 816         ret = read_command(&scc, &command);
 817         if (ret == -E_COMMAND_SYNTAX)
 818                 goto err_out;
 819         if (ret < 0)
 820                 goto net_err;
 821         ret = -E_BAD_CMD;
 822         cmd = parse_cmd(command);
 823         if (!cmd)
 824                 goto err_out;
 825         /* valid command, check permissions */
 826         ret = check_perms(u->perms, cmd);
 827         if (ret < 0)
 828                 goto err_out;
 829         /* valid command and sufficient perms */
 830         ret = create_argv(command, "\n", &argv);
 831         if (ret < 0)
 832                 goto err_out;
 833         argc = ret;
 834         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 835                         peername);
 836         ret = cmd->handler(&scc, argc, argv);
 837         free_argv(argv);
 838         mutex_lock(mmd_mutex);
 839         mmd->num_commands++;
 840         mutex_unlock(mmd_mutex);
 841         if (ret >= 0)
 842                 goto out;
 843 err_out:
 844         sc_send_va_buffer(&scc, "%s\n", para_strerror(-ret));
 845 net_err:
 846         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 847 out:
 848         free(command);
 849         sc_free(scc.recv);
 850         sc_free(scc.send);
 851         mutex_lock(mmd_mutex);
 852         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 853                 mmd->events++;
 854         mmd->active_connections--;
 855         mutex_unlock(mmd_mutex);
 856         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 857 }