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 <dirent.h>
  14 #include <openssl/rc4.h>
  15 #include <osl.h>
  16 #include <stdbool.h>
  17
  18 #include "para.h"
  19 #include "error.h"
  20 #include "crypt.h"
  21 #include "command.h"
  22 #include "server.cmdline.h"
  23 #include "string.h"
  24 #include "afh.h"
  25 #include "afs.h"
  26 #include "server.h"
  27 #include "list.h"
  28 #include "send.h"
  29 #include "vss.h"
  30 #include "rc4.h"
  31 #include "net.h"
  32 #include "daemon.h"
  33 #include "fd.h"
  34 #include "ipc.h"
  35 #include "user_list.h"
  36 #include "server_command_list.h"
  37 #include "afs_command_list.h"
  38 #include "sched.h"
  39 #include "signal.h"
  40
  41 /** Commands including options must be shorter than this. */
  42 #define MAX_COMMAND_LEN 32768
  43
  44 extern int mmd_mutex;
  45 extern struct misc_meta_data *mmd;
  46 extern struct sender senders[];
  47 int send_afs_status(struct rc4_context *rc4c, int parser_friendly);
  48
  49 const char *status_item_list[] = {STATUS_ITEM_ARRAY};
  50
  51 static void dummy(__a_unused int s)
  52 {
  53 }
  54
  55 static void mmd_dup(struct misc_meta_data *new_mmd)
  56 {
  57         mutex_lock(mmd_mutex);
  58         *new_mmd = *mmd;
  59         mutex_unlock(mmd_mutex);
  60 }
  61
  62 /*
  63  * Compute human readable string containing vss status for given integer value.
  64  *
  65  * We don't want to use vss_playing() and friends here because we take a
  66  * snapshot of the mmd struct and use the copy for computing the state of the
  67  * vss. If the real data were used, we would take the mmd lock for a rather
  68  * long time or risk to get an inconsistent view.
  69  */
  70 static char *vss_status_tohuman(unsigned int flags)
  71 {
  72         if (flags & VSS_PLAYING)
  73                 return para_strdup("playing");
  74         if (flags & VSS_NEXT)
  75                 return para_strdup("stopped");
  76         return para_strdup("paused");
  77 }
  78
  79 /*
  80  * return human readable permission string. Never returns NULL.
  81  */
  82 static char *cmd_perms_itohuman(unsigned int perms)
  83 {
  84         char *msg = para_malloc(5 * sizeof(char));
  85
  86         msg[0] = perms & AFS_READ? 'a' : '-';
  87         msg[1] = perms & AFS_WRITE? 'A' : '-';
  88         msg[2] = perms & VSS_READ? 'v' : '-';
  89         msg[3] = perms & VSS_WRITE? 'V' : '-';
  90         msg[4] = '\0';
  91         return msg;
  92 }
  93
  94 /*
  95  * Never returns NULL.
  96  */
  97 static char *vss_get_status_flags(unsigned int flags)
  98 {
  99         char *msg = para_malloc(5 * sizeof(char));
 100
 101         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
 102         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
 103         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
 104         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
 105         msg[4] = '\0';
 106         return msg;
 107 }
 108
 109 static char *get_status(struct misc_meta_data *nmmd, int parser_friendly)
 110 {
 111         char mtime[30] = "";
 112         char *status, *flags; /* vss status info */
 113         char *ut = uptime_str();
 114         long offset = (nmmd->offset + 500) / 1000;
 115         struct timeval current_time;
 116         struct tm mtime_tm;
 117         struct para_buffer b = {.flags = parser_friendly? PBF_SIZE_PREFIX : 0};
 118
 119         /* report real status */
 120         status = vss_status_tohuman(nmmd->vss_status_flags);
 121         flags = vss_get_status_flags(nmmd->vss_status_flags);
 122         if (nmmd->size) { /* parent currently has an audio file open */
 123                 localtime_r(&nmmd->mtime, &mtime_tm);
 124                 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
 125         }
 126         gettimeofday(&current_time, NULL);
 127         WRITE_STATUS_ITEM(&b, SI_FILE_SIZE, "%zu\n", nmmd->size / 1024);
 128         WRITE_STATUS_ITEM(&b, SI_MTIME, "%s\n", mtime);
 129         WRITE_STATUS_ITEM(&b, SI_STATUS, "%s\n", status);
 130         WRITE_STATUS_ITEM(&b, SI_STATUS_FLAGS, "%s\n", flags);
 131         WRITE_STATUS_ITEM(&b, SI_OFFSET, "%li\n", offset);
 132         WRITE_STATUS_ITEM(&b, SI_AFS_MODE, "%s\n", mmd->afs_mode_string);
 133         WRITE_STATUS_ITEM(&b, SI_STREAM_START, "%lu.%lu\n",
 134                 (long unsigned)nmmd->stream_start.tv_sec,
 135                 (long unsigned)nmmd->stream_start.tv_usec);
 136         WRITE_STATUS_ITEM(&b, SI_CURRENT_TIME, "%lu.%lu\n",
 137                 (long unsigned)current_time.tv_sec,
 138                 (long unsigned)current_time.tv_usec);
 139         free(flags);
 140         free(status);
 141         free(ut);
 142         return b.buf;
 143 }
 144
 145 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 146 {
 147         int i;
 148         /* this has to match sender.h */
 149         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 150
 151         scd->sender_num = -1;
 152         if (argc < 2)
 153                 return -E_COMMAND_SYNTAX;
 154         for (i = 0; senders[i].name; i++)
 155                 if (!strcmp(senders[i].name, argv[1]))
 156                         break;
 157         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 158         if (!senders[i].name)
 159                 return -E_COMMAND_SYNTAX;
 160         scd->sender_num = i;
 161         for (i = 0; subcmds[i]; i++)
 162                 if (!strcmp(subcmds[i], argv[2]))
 163                         break;
 164         if (!subcmds[i])
 165                 return -E_COMMAND_SYNTAX;
 166         scd->cmd_num = i;
 167         if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
 168                 return -E_SENDER_CMD;
 169         switch (scd->cmd_num) {
 170         case SENDER_ON:
 171         case SENDER_OFF:
 172                 if (argc != 3)
 173                         return -E_COMMAND_SYNTAX;
 174                 break;
 175         case SENDER_DENY:
 176         case SENDER_ALLOW:
 177                 if (argc != 4 || parse_cidr(argv[3], scd->host,
 178                                 sizeof(scd->host), &scd->netmask) == NULL)
 179                         return -E_COMMAND_SYNTAX;
 180                 break;
 181         case SENDER_ADD:
 182         case SENDER_DELETE:
 183                 if (argc != 4)
 184                         return -E_COMMAND_SYNTAX;
 185                 return parse_fec_url(argv[3], scd);
 186         default:
 187                 return -E_COMMAND_SYNTAX;
 188         }
 189         return 1;
 190 }
 191
 192 int com_sender(struct rc4_context *rc4c, int argc, char * const * argv)
 193 {
 194         int i, ret;
 195         char *msg = NULL;
 196         struct sender_command_data scd;
 197
 198         if (argc < 2) {
 199                 for (i = 0; senders[i].name; i++) {
 200                         char *tmp = make_message("%s%s\n",
 201                                 msg? msg : "", senders[i].name);
 202                         free(msg);
 203                         msg = tmp;
 204                 }
 205                 ret = rc4_send_buffer(rc4c, msg);
 206                 free(msg);
 207                 return ret;
 208         }
 209         ret = check_sender_args(argc, argv, &scd);
 210         if (ret < 0) {
 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
 219         switch (scd.cmd_num) {
 220         case SENDER_ADD:
 221         case SENDER_DELETE:
 222                 assert(senders[scd.sender_num].resolve_target);
 223                 ret = senders[scd.sender_num].resolve_target(argv[3], &scd);
 224                 if (ret < 0)
 225                         return ret;
 226         }
 227
 228         for (i = 0; i < 10; i++) {
 229                 mutex_lock(mmd_mutex);
 230                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 231                         mutex_unlock(mmd_mutex);
 232                         usleep(100 * 1000);
 233                         continue;
 234                 }
 235                 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
 236                 mutex_unlock(mmd_mutex);
 237                 break;
 238         }
 239         return (i < 10)? 1 : -E_LOCK;
 240 }
 241
 242 /* server info */
 243 int com_si(struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 244 {
 245         int i, ret;
 246         char *ut;
 247         char *sender_info = NULL;
 248
 249         if (argc != 1)
 250                 return -E_COMMAND_SYNTAX;
 251         mutex_lock(mmd_mutex);
 252         for (i = 0; senders[i].name; i++) {
 253                 char *info = senders[i].info();
 254                 sender_info = para_strcat(sender_info, info);
 255                 free(info);
 256         }
 257         ut = uptime_str();
 258         ret = rc4_send_va_buffer(rc4c, "version: " GIT_VERSION "\n"
 259                 "up: %s\nplayed: %u\n"
 260                 "server_pid: %d\n"
 261                 "afs_pid: %d\n"
 262                 "connections (active/accepted/total): %u/%u/%u\n"
 263                 "current loglevel: %s\n"
 264                 "supported audio formats: %s\n"
 265                 "%s",
 266                 ut, mmd->num_played,
 267                 (int)getppid(),
 268                 (int)mmd->afs_pid,
 269                 mmd->active_connections,
 270                 mmd->num_commands,
 271                 mmd->num_connects,
 272                 conf.loglevel_arg,
 273                 SERVER_AUDIO_FORMATS,
 274                 sender_info
 275         );
 276         mutex_unlock(mmd_mutex);
 277         free(ut);
 278         free(sender_info);
 279         return ret;
 280 }
 281
 282 /* version */
 283 int com_version(struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 284 {
 285         if (argc != 1)
 286                 return -E_COMMAND_SYNTAX;
 287         return rc4_send_buffer(rc4c, VERSION_TEXT("server")
 288                 "built: " BUILD_DATE "\n"
 289                 UNAME_RS ", " CC_VERSION "\n"
 290         );
 291 }
 292
 293 #define EMPTY_STATUS_ITEMS \
 294         ITEM(PATH) \
 295         ITEM(DIRECTORY) \
 296         ITEM(BASENAME) \
 297         ITEM(SCORE) \
 298         ITEM(ATTRIBUTES_BITMAP) \
 299         ITEM(ATTRIBUTES_TXT) \
 300         ITEM(HASH) \
 301         ITEM(IMAGE_ID) \
 302         ITEM(IMAGE_NAME) \
 303         ITEM(LYRICS_ID) \
 304         ITEM(LYRICS_NAME) \
 305         ITEM(BITRATE) \
 306         ITEM(FORMAT) \
 307         ITEM(FREQUENCY) \
 308         ITEM(CHANNELS) \
 309         ITEM(DURATION) \
 310         ITEM(SECONDS_TOTAL) \
 311         ITEM(NUM_PLAYED) \
 312         ITEM(LAST_PLAYED) \
 313         ITEM(TECHINFO) \
 314         ITEM(ARTIST) \
 315         ITEM(TITLE) \
 316         ITEM(YEAR) \
 317         ITEM(ALBUM) \
 318         ITEM(COMMENT) \
 319         ITEM(AMPLIFICATION)
 320
 321 /**
 322  * Write a list of audio-file related status items with empty values.
 323  *
 324  * This is used by vss when currently no audio file is open.
 325  */
 326 static char *empty_status_items(int parser_friendly)
 327 {
 328         if (parser_friendly)
 329                 return make_message(
 330                         #define ITEM(x) "0004 %02x:\n"
 331                         EMPTY_STATUS_ITEMS
 332                         #undef ITEM
 333                         #define ITEM(x) , SI_ ## x
 334                         EMPTY_STATUS_ITEMS
 335                         #undef ITEM
 336                 );
 337         return make_message(
 338                 #define ITEM(x) "%s:\n"
 339                 EMPTY_STATUS_ITEMS
 340                 #undef ITEM
 341                 #define ITEM(x) ,status_item_list[SI_ ## x]
 342                 EMPTY_STATUS_ITEMS
 343                 #undef ITEM
 344         );
 345 }
 346 #undef EMPTY_STATUS_ITEMS
 347
 348 /* stat */
 349 int com_stat(struct rc4_context *rc4c, int argc, char * const * argv)
 350 {
 351         int i, ret;
 352         struct misc_meta_data tmp, *nmmd = &tmp;
 353         char *s;
 354         int32_t num = 0;
 355         int parser_friendly = 0;
 356
 357         para_sigaction(SIGUSR1, dummy);
 358
 359         for (i = 1; i < argc; i++) {
 360                 const char *arg = argv[i];
 361                 if (arg[0] != '-')
 362                         break;
 363                 if (!strcmp(arg, "--")) {
 364                         i++;
 365                         break;
 366                 }
 367                 if (!strncmp(arg, "-n=", 3)) {
 368                         ret = para_atoi32(arg + 3, &num);
 369                         if (ret < 0)
 370                                 return ret;
 371                         continue;
 372                 }
 373                 if (!strcmp(arg, "-p")) {
 374                         parser_friendly = 1;
 375                         continue;
 376                 }
 377                 return -E_COMMAND_SYNTAX;
 378         }
 379         if (i != argc)
 380                 return -E_COMMAND_SYNTAX;
 381         for (;;) {
 382                 mmd_dup(nmmd);
 383                 s = get_status(nmmd, parser_friendly);
 384                 ret = rc4_send_buffer(rc4c, s);
 385                 free(s);
 386                 if (ret < 0)
 387                         goto out;
 388                 if (nmmd->vss_status_flags & VSS_NEXT) {
 389                         static char *esi;
 390                         if (!esi)
 391                                 esi = empty_status_items(parser_friendly);
 392                         ret = rc4_send_buffer(rc4c, esi);
 393                         if (ret < 0)
 394                                 goto out;
 395                 } else
 396                         send_afs_status(rc4c, parser_friendly);
 397                 ret = 1;
 398                 if (num > 0 && !--num)
 399                         goto out;
 400                 sleep(50);
 401                 if (getppid() == 1)
 402                         return -E_SERVER_CRASH;
 403         }
 404 out:
 405         return ret;
 406 }
 407
 408 static int send_list_of_commands(struct rc4_context *rc4c, struct server_command *cmd,
 409                 const char *handler)
 410 {
 411         int ret, i;
 412
 413         for (i = 1; cmd->name; cmd++, i++) {
 414                 char *perms = cmd_perms_itohuman(cmd->perms);
 415                 ret = rc4_send_va_buffer(rc4c, "%s\t%s\t%s\t%s\n", cmd->name,
 416                         handler,
 417                         perms,
 418                         cmd->description);
 419                 free(perms);
 420                 if (ret < 0)
 421                         return ret;
 422         }
 423         return 1;
 424 }
 425
 426 /* returns string that must be freed by the caller */
 427 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 428 {
 429         struct server_command *cmd;
 430
 431         for (cmd = server_cmds; cmd->name; cmd++)
 432                 if (!strcmp(cmd->name, name)) {
 433                         if (handler)
 434                                 *handler = para_strdup("server"); /* server commands */
 435                         return cmd;
 436                 }
 437         /* not found, look for commands supported by afs */
 438         for (cmd = afs_cmds; cmd->name; cmd++)
 439                 if (!strcmp(cmd->name, name)) {
 440                         if (handler)
 441                                 *handler = para_strdup("afs");
 442                         return cmd;
 443                 }
 444         return NULL;
 445 }
 446
 447 /* help */
 448 int com_help(struct rc4_context *rc4c, int argc, char * const * argv)
 449 {
 450         struct server_command *cmd;
 451         char *perms, *handler;
 452         int ret;
 453
 454         if (argc < 2) {
 455                 /* no argument given, print list of commands */
 456                 if ((ret = send_list_of_commands(rc4c, server_cmds, "server")) < 0)
 457                         return ret;
 458                 return send_list_of_commands(rc4c, afs_cmds, "afs");
 459         }
 460         /* argument given for help */
 461         cmd = get_cmd_ptr(argv[1], &handler);
 462         if (!cmd)
 463                 return -E_BAD_CMD;
 464         perms = cmd_perms_itohuman(cmd->perms);
 465         ret = rc4_send_va_buffer(rc4c,
 466                 "%s - %s\n\n"
 467                 "handler: %s\n"
 468                 "permissions: %s\n"
 469                 "usage: %s\n\n"
 470                 "%s\n",
 471                 argv[1],
 472                 cmd->description,
 473                 handler,
 474                 perms,
 475                 cmd->usage,
 476                 cmd->help
 477         );
 478         free(perms);
 479         free(handler);
 480         return ret;
 481 }
 482
 483 /* hup */
 484 int com_hup(__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(), SIGHUP);
 489         return 1;
 490 }
 491
 492 /* term */
 493 int com_term(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 494 {
 495         if (argc != 1)
 496                 return -E_COMMAND_SYNTAX;
 497         kill(getppid(), SIGTERM);
 498         return 1;
 499 }
 500
 501 int com_play(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 502 {
 503         if (argc != 1)
 504                 return -E_COMMAND_SYNTAX;
 505         mutex_lock(mmd_mutex);
 506         mmd->new_vss_status_flags |= VSS_PLAYING;
 507         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 508         mutex_unlock(mmd_mutex);
 509         return 1;
 510
 511 }
 512
 513 /* stop */
 514 int com_stop(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 515 {
 516         if (argc != 1)
 517                 return -E_COMMAND_SYNTAX;
 518         mutex_lock(mmd_mutex);
 519         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 520         mmd->new_vss_status_flags &= ~VSS_REPOS;
 521         mmd->new_vss_status_flags |= VSS_NEXT;
 522         mutex_unlock(mmd_mutex);
 523         return 1;
 524 }
 525
 526 /* pause */
 527 int com_pause(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 528 {
 529         if (argc != 1)
 530                 return -E_COMMAND_SYNTAX;
 531         mutex_lock(mmd_mutex);
 532         if (!vss_paused() && !vss_stopped()) {
 533                 mmd->events++;
 534                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 535                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 536         }
 537         mutex_unlock(mmd_mutex);
 538         return 1;
 539 }
 540
 541 /* next */
 542 int com_next(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 543 {
 544         if (argc != 1)
 545                 return -E_COMMAND_SYNTAX;
 546         mutex_lock(mmd_mutex);
 547         mmd->events++;
 548         mmd->new_vss_status_flags |= VSS_NEXT;
 549         mutex_unlock(mmd_mutex);
 550         return 1;
 551 }
 552
 553 /* nomore */
 554 int com_nomore(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 555 {
 556         if (argc != 1)
 557                 return -E_COMMAND_SYNTAX;
 558         mutex_lock(mmd_mutex);
 559         if (vss_playing() || vss_paused())
 560                 mmd->new_vss_status_flags |= VSS_NOMORE;
 561         mutex_unlock(mmd_mutex);
 562         return 1;
 563 }
 564
 565 /* ff */
 566 int com_ff(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 567 {
 568         long promille;
 569         int ret, backwards = 0;
 570         unsigned i;
 571         char c;
 572
 573         if (argc != 2)
 574                 return -E_COMMAND_SYNTAX;
 575         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 576                 return -E_COMMAND_SYNTAX;
 577         if (ret > 1 && c == '-')
 578                 backwards = 1; /* jmp backwards */
 579         mutex_lock(mmd_mutex);
 580         ret = -E_NO_AUDIO_FILE;
 581         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 582                 goto out;
 583         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 584         if (backwards)
 585                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 586         else
 587                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 588         if (promille < 0)
 589                 promille = 0;
 590         if (promille >  1000) {
 591                 mmd->new_vss_status_flags |= VSS_NEXT;
 592                 goto out;
 593         }
 594         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 595         mmd->new_vss_status_flags |= VSS_REPOS;
 596         mmd->new_vss_status_flags &= ~VSS_NEXT;
 597         mmd->events++;
 598         ret = 1;
 599 out:
 600         mutex_unlock(mmd_mutex);
 601         return ret;
 602 }
 603
 604 /* jmp */
 605 int com_jmp(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 606 {
 607         long unsigned int i;
 608         int ret;
 609
 610         if (argc != 2)
 611                 return -E_COMMAND_SYNTAX;
 612         if (sscanf(argv[1], "%lu", &i) <= 0)
 613                 return -E_COMMAND_SYNTAX;
 614         mutex_lock(mmd_mutex);
 615         ret = -E_NO_AUDIO_FILE;
 616         if (!mmd->afd.afhi.chunks_total)
 617                 goto out;
 618         if (i > 100)
 619                 i = 100;
 620         PARA_INFO_LOG("jumping to %lu%%\n", i);
 621         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 622         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 623                 mmd->chunks_sent, mmd->offset);
 624         mmd->new_vss_status_flags |= VSS_REPOS;
 625         mmd->new_vss_status_flags &= ~VSS_NEXT;
 626         ret = 1;
 627         mmd->events++;
 628 out:
 629         mutex_unlock(mmd_mutex);
 630         return ret;
 631 }
 632
 633 /*
 634  * check if perms are sufficient to exec a command having perms cmd_perms.
 635  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 636  */
 637 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 638 {
 639         PARA_DEBUG_LOG("checking permissions\n");
 640         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 641 }
 642
 643 /*
 644  * Parse first string from *cmd and lookup in table of valid commands.
 645  * On error, NULL is returned.
 646  */
 647 static struct server_command *parse_cmd(const char *cmdstr)
 648 {
 649         char buf[255];
 650         int n = 0;
 651
 652         sscanf(cmdstr, "%200s%n", buf, &n);
 653         if (!n)
 654                 return NULL;
 655         buf[n] = '\0';
 656         return get_cmd_ptr(buf, NULL);
 657 }
 658
 659 static int read_command(struct rc4_context *rc4c, char **result)
 660 {
 661         int ret;
 662         char buf[4096];
 663         char *command = NULL;
 664
 665         for (;;) {
 666                 size_t numbytes;
 667                 char *p;
 668
 669                 ret = rc4_recv_buffer(rc4c, buf, sizeof(buf));
 670                 if (ret < 0)
 671                         goto out;
 672                 if (!ret)
 673                         break;
 674                 numbytes = ret;
 675                 ret = -E_COMMAND_SYNTAX;
 676                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 677                         goto out;
 678                 command = para_strcat(command, buf);
 679                 p = strstr(command, EOC_MSG);
 680                 if (p) {
 681                         *p = '\0';
 682                         break;
 683                 }
 684         }
 685         ret = command? 1 : -E_COMMAND_SYNTAX;
 686 out:
 687         if (ret < 0)
 688                 free(command);
 689         else
 690                 *result = command;
 691         return ret;
 692
 693 }
 694
 695 static void reset_signals(void)
 696 {
 697         para_sigaction(SIGCHLD, SIG_IGN);
 698         para_sigaction(SIGINT, SIG_DFL);
 699         para_sigaction(SIGTERM, SIG_DFL);
 700         para_sigaction(SIGHUP, SIG_DFL);
 701 }
 702
 703 /**
 704  * Perform user authentication and execute a command.
 705  *
 706  * \param fd The file descriptor to send output to.
 707  * \param peername Identifies the connecting peer.
 708  *
 709  * Whenever para_server accepts an incoming tcp connection on
 710  * the port it listens on, it forks and the resulting child
 711  * calls this function.
 712  *
 713  * An RSA-based challenge/response is used to authenticate
 714  * the peer. It that authentication succeeds, a random RC4
 715  * session key is generated and sent back to the peer,
 716  * encrypted with its RSA public key.  From this point on,
 717  * all transfers are crypted with this session key.
 718  *
 719  * Next it is checked if the peer supplied  a valid server command or a command
 720  * for the audio file selector.  If yes, and if the user has sufficient
 721  * permissions to execute that command, the function calls the corresponding
 722  * command handler which does argument checking and further processing.
 723  *
 724  * In order to cope with a DOS attacks, a timeout is set up
 725  * which terminates the function if the connection was not
 726  * authenticated when the timeout expires.
 727  *
 728  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 729  */
 730 __noreturn void handle_connect(int fd, const char *peername)
 731 {
 732         int ret, argc;
 733         char buf[4096];
 734         unsigned char rand_buf[CHALLENGE_SIZE + 2 * RC4_KEY_LEN];
 735         unsigned char challenge_sha1[HASH_SIZE];
 736         struct user *u;
 737         struct server_command *cmd = NULL;
 738         char **argv = NULL;
 739         char *p, *command = NULL;
 740         size_t numbytes;
 741         struct rc4_context rc4c = {.fd = fd};
 742
 743         reset_signals();
 744         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 745         ret = mark_fd_blocking(fd);
 746         if (ret < 0)
 747                 goto net_err;
 748         /* send Welcome message */
 749         ret = send_va_buffer(fd, "This is para_server, version "
 750                 PACKAGE_VERSION  ".\n" );
 751         if (ret < 0)
 752                 goto net_err;
 753         /* recv auth request line */
 754         ret = recv_buffer(fd, buf, sizeof(buf));
 755         if (ret < 0)
 756                 goto net_err;
 757         if (ret < 10) {
 758                 ret = -E_AUTH_REQUEST;
 759                 goto net_err;
 760         }
 761         numbytes = ret;
 762         ret = -E_AUTH_REQUEST;
 763         if (strncmp(buf, AUTH_REQUEST_MSG, strlen(AUTH_REQUEST_MSG)))
 764                 goto net_err;
 765         p = buf + strlen(AUTH_REQUEST_MSG);
 766         PARA_DEBUG_LOG("received auth request for user %s\n", p);
 767         ret = -E_BAD_USER;
 768         u = lookup_user(p);
 769         if (u) {
 770                 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
 771                 ret = para_encrypt_buffer(u->rsa, rand_buf, sizeof(rand_buf),
 772                         (unsigned char *)buf);
 773                 if (ret < 0)
 774                         goto net_err;
 775                 numbytes = ret;
 776         } else {
 777                 /*
 778                  * We don't want to reveal our user names, so we send a
 779                  * challenge to the client even if the user does not exist, and
 780                  * fail the authentication later.
 781                  */
 782                 numbytes = 256;
 783                 get_random_bytes_or_die((unsigned char *)buf, numbytes);
 784         }
 785         PARA_DEBUG_LOG("sending %u byte challenge + rc4 keys (%zu bytes)\n",
 786                 CHALLENGE_SIZE, numbytes);
 787         ret = send_bin_buffer(fd, buf, numbytes);
 788         if (ret < 0)
 789                 goto net_err;
 790         /* recv challenge response */
 791         ret = recv_bin_buffer(fd, buf, HASH_SIZE);
 792         if (ret < 0)
 793                 goto net_err;
 794         numbytes = ret;
 795         PARA_DEBUG_LOG("received %d bytes challenge response\n", ret);
 796         ret = -E_BAD_USER;
 797         if (!u)
 798                 goto net_err;
 799         /*
 800          * The correct response is the sha1 of the first CHALLENGE_SIZE bytes
 801          * of the random data.
 802          */
 803         ret = -E_BAD_AUTH;
 804         if (numbytes != HASH_SIZE)
 805                 goto net_err;
 806         sha1_hash((char *)rand_buf, CHALLENGE_SIZE, challenge_sha1);
 807         if (memcmp(challenge_sha1, buf, HASH_SIZE))
 808                 goto net_err;
 809         /* auth successful */
 810         alarm(0);
 811         PARA_INFO_LOG("good auth for %s\n", u->name);
 812         /* init rc4 keys with the second part of the random buffer */
 813         RC4_set_key(&rc4c.recv_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE);
 814         RC4_set_key(&rc4c.send_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE
 815                 + RC4_KEY_LEN);
 816         ret = rc4_send_buffer(&rc4c, PROCEED_MSG);
 817         if (ret < 0)
 818                 goto net_err;
 819         ret = read_command(&rc4c, &command);
 820         if (ret == -E_COMMAND_SYNTAX)
 821                 goto err_out;
 822         if (ret < 0)
 823                 goto net_err;
 824         ret = -E_BAD_CMD;
 825         cmd = parse_cmd(command);
 826         if (!cmd)
 827                 goto err_out;
 828         /* valid command, check permissions */
 829         ret = check_perms(u->perms, cmd);
 830         if (ret < 0)
 831                 goto err_out;
 832         /* valid command and sufficient perms */
 833         ret = create_argv(command, "\n", &argv);
 834         if (ret < 0)
 835                 goto err_out;
 836         argc = ret;
 837         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 838                         peername);
 839         ret = cmd->handler(&rc4c, argc, argv);
 840         free_argv(argv);
 841         mutex_lock(mmd_mutex);
 842         mmd->num_commands++;
 843         mutex_unlock(mmd_mutex);
 844         if (ret >= 0)
 845                 goto out;
 846 err_out:
 847         rc4_send_va_buffer(&rc4c, "%s\n", para_strerror(-ret));
 848 net_err:
 849         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 850 out:
 851         free(command);
 852         mutex_lock(mmd_mutex);
 853         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 854                 mmd->events++;
 855         mmd->active_connections--;
 856         mutex_unlock(mmd_mutex);
 857         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 858 }