command.c

   1 /*
   2  * Copyright (C) 1997-2009 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file command.c Client authentication and server commands. */
   8
   9 #include <signal.h>
  10 #include <sys/time.h>
  11 #include <sys/types.h>
  12 #include <dirent.h>
  13 #include <openssl/rc4.h>
  14 #include <osl.h>
  15
  16 #include "para.h"
  17 #include "error.h"
  18 #include "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 "vss.h"
  26 #include "list.h"
  27 #include "send.h"
  28 #include "rc4.h"
  29 #include "net.h"
  30 #include "daemon.h"
  31 #include "fd.h"
  32 #include "ipc.h"
  33 #include "user_list.h"
  34 #include "server_command_list.h"
  35 #include "afs_command_list.h"
  36 #include "sched.h"
  37 #include "signal.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 rc4_context *rc4c, int parser_friendly);
  46
  47
  48 static void dummy(__a_unused int s)
  49 {
  50 }
  51
  52 static void mmd_dup(struct misc_meta_data *new_mmd)
  53 {
  54         mutex_lock(mmd_mutex);
  55         *new_mmd = *mmd;
  56         mutex_unlock(mmd_mutex);
  57 }
  58
  59 /*
  60  * Compute human readable string containing vss status for given integer value.
  61  *
  62  * We don't want to use vss_playing() and friends here because we take a
  63  * snapshot of the mmd struct and use the copy for computing the state of the
  64  * vss. If the real data were used, we would take the mmd lock for a rather
  65  * long time or risk to get an inconsistent view.
  66  */
  67 static char *vss_status_tohuman(unsigned int flags)
  68 {
  69         if (flags & VSS_PLAYING)
  70                 return para_strdup("playing");
  71         if (flags & VSS_NEXT)
  72                 return para_strdup("stopped");
  73         return para_strdup("paused");
  74 }
  75
  76 /*
  77  * return human readable permission string. Never returns NULL.
  78  */
  79 static char *cmd_perms_itohuman(unsigned int perms)
  80 {
  81         char *msg = para_malloc(5 * sizeof(char));
  82
  83         msg[0] = perms & AFS_READ? 'a' : '-';
  84         msg[1] = perms & AFS_WRITE? 'A' : '-';
  85         msg[2] = perms & VSS_READ? 'v' : '-';
  86         msg[3] = perms & VSS_WRITE? 'V' : '-';
  87         msg[4] = '\0';
  88         return msg;
  89 }
  90
  91 /*
  92  * Never returns NULL.
  93  */
  94 static char *vss_get_status_flags(unsigned int flags)
  95 {
  96         char *msg = para_malloc(5 * sizeof(char));
  97
  98         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
  99         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
 100         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
 101         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
 102         msg[4] = '\0';
 103         return msg;
 104 }
 105
 106 static char *get_status(struct misc_meta_data *nmmd, int parser_friendly)
 107 {
 108         char mtime[30] = "";
 109         char *status, *flags; /* vss status info */
 110         char *ut = uptime_str();
 111         long offset = (nmmd->offset + 500) / 1000;
 112         struct timeval current_time;
 113         struct tm mtime_tm;
 114         struct para_buffer b = {.flags = parser_friendly? PBF_SIZE_PREFIX : 0};
 115
 116         /* report real status */
 117         status = vss_status_tohuman(nmmd->vss_status_flags);
 118         flags = vss_get_status_flags(nmmd->vss_status_flags);
 119         if (nmmd->size) { /* parent currently has an audio file open */
 120                 localtime_r(&nmmd->mtime, &mtime_tm);
 121                 strftime(mtime, 29, "%b %d %Y", &mtime_tm);
 122         }
 123         gettimeofday(&current_time, NULL);
 124         WRITE_STATUS_ITEM(&b, SI_FILE_SIZE, "%zu\n", nmmd->size / 1024);
 125         WRITE_STATUS_ITEM(&b, SI_MTIME, "%s\n", mtime);
 126         WRITE_STATUS_ITEM(&b, SI_STATUS, "%s\n", status);
 127         WRITE_STATUS_ITEM(&b, SI_STATUS_FLAGS, "%s\n", flags);
 128         WRITE_STATUS_ITEM(&b, SI_OFFSET, "%li\n", offset);
 129         WRITE_STATUS_ITEM(&b, SI_AFS_MODE, "%s\n", mmd->afs_mode_string);
 130         WRITE_STATUS_ITEM(&b, SI_STREAM_START, "%lu.%lu\n",
 131                 (long unsigned)nmmd->stream_start.tv_sec,
 132                 (long unsigned)nmmd->stream_start.tv_usec);
 133         WRITE_STATUS_ITEM(&b, SI_CURRENT_TIME, "%lu.%lu\n",
 134                 (long unsigned)current_time.tv_sec,
 135                 (long unsigned)current_time.tv_usec);
 136         free(flags);
 137         free(status);
 138         free(ut);
 139         return b.buf;
 140 }
 141
 142 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 143 {
 144         int i;
 145         /* this has to match sender.h */
 146         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 147
 148         scd->sender_num = -1;
 149         if (argc < 2)
 150                 return -E_COMMAND_SYNTAX;
 151         for (i = 0; senders[i].name; i++)
 152                 if (!strcmp(senders[i].name, argv[1]))
 153                         break;
 154         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 155         if (!senders[i].name)
 156                 return -E_COMMAND_SYNTAX;
 157         scd->sender_num = i;
 158         for (i = 0; subcmds[i]; i++)
 159                 if (!strcmp(subcmds[i], argv[2]))
 160                         break;
 161         if (!subcmds[i])
 162                 return -E_COMMAND_SYNTAX;
 163         scd->cmd_num = i;
 164         if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
 165                 return -E_SENDER_CMD;
 166         switch (scd->cmd_num) {
 167         case SENDER_ON:
 168         case SENDER_OFF:
 169                 if (argc != 3)
 170                         return -E_COMMAND_SYNTAX;
 171                 break;
 172         case SENDER_DENY:
 173         case SENDER_ALLOW:
 174                 if (argc != 4 || parse_cidr(argv[3], scd->host,
 175                                 sizeof(scd->host), &scd->netmask) == NULL)
 176                         return -E_COMMAND_SYNTAX;
 177                 break;
 178         case SENDER_ADD:
 179         case SENDER_DELETE:
 180                 if (argc != 4)
 181                         return -E_COMMAND_SYNTAX;
 182                 return parse_fec_url(argv[3], scd);
 183         default:
 184                 return -E_COMMAND_SYNTAX;
 185         }
 186         return 1;
 187 }
 188
 189 int com_sender(struct rc4_context *rc4c, int argc, char * const * argv)
 190 {
 191         int i, ret;
 192         struct sender_command_data scd;
 193
 194         if (argc < 2) {
 195                 char *msg = NULL;
 196                 for (i = 0; senders[i].name; i++) {
 197                         char *tmp = make_message("%s%s\n",
 198                                 msg? msg : "", senders[i].name);
 199                         free(msg);
 200                         msg = tmp;
 201                 }
 202                 ret = rc4_send_buffer(rc4c, msg);
 203                 free(msg);
 204                 return ret;
 205         }
 206         ret = check_sender_args(argc, argv, &scd);
 207         if (ret < 0) {
 208                 char *msg;
 209                 if (scd.sender_num < 0)
 210                         return ret;
 211                 msg = senders[scd.sender_num].help();
 212                 ret = rc4_send_buffer(rc4c, msg);
 213                 free(msg);
 214                 return ret;
 215         }
 216         for (i = 0; i < 10; i++) {
 217                 mutex_lock(mmd_mutex);
 218                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 219                         mutex_unlock(mmd_mutex);
 220                         usleep(100 * 1000);
 221                         continue;
 222                 }
 223                 memcpy(&mmd->sender_cmd_data, &scd, sizeof(scd));
 224                 mutex_unlock(mmd_mutex);
 225                 break;
 226         }
 227         return (i < 10)? 1 : -E_LOCK;
 228 }
 229
 230 /* server info */
 231 int com_si(struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 232 {
 233         int i, ret;
 234         char *ut;
 235         char *sender_info = NULL, *sender_list = NULL;
 236
 237         if (argc != 1)
 238                 return -E_COMMAND_SYNTAX;
 239         mutex_lock(mmd_mutex);
 240         for (i = 0; senders[i].name; i++) {
 241                 char *info = senders[i].info();
 242                 sender_info = para_strcat(sender_info, info);
 243                 free(info);
 244                 sender_list = para_strcat(sender_list, senders[i].name);
 245                 sender_list = para_strcat(sender_list, " ");
 246         }
 247         ut = uptime_str();
 248         ret = rc4_send_va_buffer(rc4c, "up: %s\nplayed: %u\n"
 249                 "server_pid: %d\n"
 250                 "afs_pid: %d\n"
 251                 "connections (active/accepted/total): %u/%u/%u\n"
 252                 "current loglevel: %s\n"
 253                 "supported audio formats: %s\n"
 254                 "supported senders: %s\n"
 255                 "%s",
 256                 ut, mmd->num_played,
 257                 (int)getppid(),
 258                 (int)mmd->afs_pid,
 259                 mmd->active_connections,
 260                 mmd->num_commands,
 261                 mmd->num_connects,
 262                 conf.loglevel_arg,
 263                 supported_audio_formats(),
 264                 sender_list,
 265                 sender_info
 266         );
 267         mutex_unlock(mmd_mutex);
 268         free(ut);
 269         free(sender_list);
 270         free(sender_info);
 271         return ret;
 272 }
 273
 274 /* version */
 275 int com_version(struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 276 {
 277         if (argc != 1)
 278                 return -E_COMMAND_SYNTAX;
 279         return rc4_send_buffer(rc4c, VERSION_TEXT("server")
 280                 "built: " BUILD_DATE "\n"
 281                 UNAME_RS ", " CC_VERSION "\n"
 282         );
 283 }
 284
 285 #define EMPTY_STATUS_ITEMS \
 286         ITEM(PATH) \
 287         ITEM(DIRECTORY) \
 288         ITEM(BASENAME) \
 289         ITEM(SCORE) \
 290         ITEM(ATTRIBUTES_BITMAP) \
 291         ITEM(ATTRIBUTES_TXT) \
 292         ITEM(HASH) \
 293         ITEM(IMAGE_ID) \
 294         ITEM(IMAGE_NAME) \
 295         ITEM(LYRICS_ID) \
 296         ITEM(LYRICS_NAME) \
 297         ITEM(BITRATE) \
 298         ITEM(FORMAT) \
 299         ITEM(FREQUENCY) \
 300         ITEM(CHANNELS) \
 301         ITEM(DURATION) \
 302         ITEM(SECONDS_TOTAL) \
 303         ITEM(NUM_PLAYED) \
 304         ITEM(LAST_PLAYED) \
 305         ITEM(TECHINFO) \
 306         ITEM(ARTIST) \
 307         ITEM(TITLE) \
 308         ITEM(YEAR) \
 309         ITEM(ALBUM) \
 310         ITEM(COMMENT) \
 311         ITEM(AMPLIFICATION)
 312
 313 /**
 314  * Write a list of audio-file related status items with empty values.
 315  *
 316  * This is used by vss when currently no audio file is open.
 317  */
 318 static char *empty_status_items(int parser_friendly)
 319 {
 320         if (parser_friendly)
 321                 return make_message(
 322                         #define ITEM(x) "0004 %02x:\n"
 323                         EMPTY_STATUS_ITEMS
 324                         #undef ITEM
 325                         #define ITEM(x) , SI_ ## x
 326                         EMPTY_STATUS_ITEMS
 327                         #undef ITEM
 328                 );
 329         return make_message(
 330                 #define ITEM(x) "%s:\n"
 331                 EMPTY_STATUS_ITEMS
 332                 #undef ITEM
 333                 #define ITEM(x) ,status_item_list[SI_ ## x]
 334                 EMPTY_STATUS_ITEMS
 335                 #undef ITEM
 336         );
 337 }
 338 #undef EMPTY_STATUS_ITEMS
 339
 340 /* stat */
 341 int com_stat(struct rc4_context *rc4c, int argc, char * const * argv)
 342 {
 343         int i, ret;
 344         struct misc_meta_data tmp, *nmmd = &tmp;
 345         char *s;
 346         int32_t num = 0;
 347         int parser_friendly = 0;
 348
 349         para_sigaction(SIGUSR1, dummy);
 350
 351         for (i = 1; i < argc; i++) {
 352                 const char *arg = argv[i];
 353                 if (arg[0] != '-')
 354                         break;
 355                 if (!strcmp(arg, "--")) {
 356                         i++;
 357                         break;
 358                 }
 359                 if (!strncmp(arg, "-n=", 3)) {
 360                         ret = para_atoi32(arg + 3, &num);
 361                         if (ret < 0)
 362                                 return ret;
 363                         continue;
 364                 }
 365                 if (!strcmp(arg, "-p")) {
 366                         parser_friendly = 1;
 367                         continue;
 368                 }
 369         }
 370         if (i != argc)
 371                 return -E_COMMAND_SYNTAX;
 372         for (;;) {
 373                 mmd_dup(nmmd);
 374                 s = get_status(nmmd, parser_friendly);
 375                 ret = rc4_send_buffer(rc4c, s);
 376                 free(s);
 377                 if (ret < 0)
 378                         goto out;
 379                 if (nmmd->vss_status_flags & VSS_NEXT) {
 380                         static char *esi;
 381                         if (!esi)
 382                                 esi = empty_status_items(parser_friendly);
 383                         ret = rc4_send_buffer(rc4c, esi);
 384                         if (ret < 0)
 385                                 goto out;
 386                 } else
 387                         send_afs_status(rc4c, parser_friendly);
 388                 ret = 1;
 389                 if (num > 0 && !--num)
 390                         goto out;
 391                 sleep(50);
 392                 if (getppid() == 1)
 393                         return -E_SERVER_CRASH;
 394         }
 395 out:
 396         return ret;
 397 }
 398
 399 static int send_list_of_commands(struct rc4_context *rc4c, struct server_command *cmd,
 400                 const char *handler)
 401 {
 402         int ret, i;
 403
 404         for (i = 1; cmd->name; cmd++, i++) {
 405                 char *perms = cmd_perms_itohuman(cmd->perms);
 406                 ret = rc4_send_va_buffer(rc4c, "%s\t%s\t%s\t%s\n", cmd->name,
 407                         handler,
 408                         perms,
 409                         cmd->description);
 410                 free(perms);
 411                 if (ret < 0)
 412                         return ret;
 413         }
 414         return 1;
 415 }
 416
 417 /* returns string that must be freed by the caller */
 418 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 419 {
 420         struct server_command *cmd;
 421
 422         for (cmd = server_cmds; cmd->name; cmd++)
 423                 if (!strcmp(cmd->name, name)) {
 424                         if (handler)
 425                                 *handler = para_strdup("server"); /* server commands */
 426                         return cmd;
 427                 }
 428         /* not found, look for commands supported by afs */
 429         for (cmd = afs_cmds; cmd->name; cmd++)
 430                 if (!strcmp(cmd->name, name)) {
 431                         if (handler)
 432                                 *handler = para_strdup("afs");
 433                         return cmd;
 434                 }
 435         return NULL;
 436 }
 437
 438 /* help */
 439 int com_help(struct rc4_context *rc4c, int argc, char * const * argv)
 440 {
 441         struct server_command *cmd;
 442         char *perms, *handler;
 443         int ret;
 444
 445         if (argc < 2) {
 446                 /* no argument given, print list of commands */
 447                 if ((ret = send_list_of_commands(rc4c, server_cmds, "server")) < 0)
 448                         return ret;
 449                 return send_list_of_commands(rc4c, afs_cmds, "afs");
 450         }
 451         /* argument given for help */
 452         cmd = get_cmd_ptr(argv[1], &handler);
 453         if (!cmd) {
 454                 free(handler);
 455                 return -E_BAD_CMD;
 456         }
 457         perms = cmd_perms_itohuman(cmd->perms);
 458         ret = rc4_send_va_buffer(rc4c,
 459                 "%s - %s\n\n"
 460                 "handler: %s\n"
 461                 "permissions: %s\n"
 462                 "usage: %s\n\n"
 463                 "%s\n",
 464                 argv[1],
 465                 cmd->description,
 466                 handler,
 467                 perms,
 468                 cmd->usage,
 469                 cmd->help
 470         );
 471         free(perms);
 472         free(handler);
 473         return ret;
 474 }
 475
 476 /* hup */
 477 int com_hup(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 478 {
 479         if (argc != 1)
 480                 return -E_COMMAND_SYNTAX;
 481         kill(getppid(), SIGHUP);
 482         return 1;
 483 }
 484
 485 /* term */
 486 int com_term(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 487 {
 488         if (argc != 1)
 489                 return -E_COMMAND_SYNTAX;
 490         kill(getppid(), SIGTERM);
 491         return 1;
 492 }
 493
 494 int com_play(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 495 {
 496         if (argc != 1)
 497                 return -E_COMMAND_SYNTAX;
 498         mutex_lock(mmd_mutex);
 499         mmd->new_vss_status_flags |= VSS_PLAYING;
 500         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 501         mutex_unlock(mmd_mutex);
 502         return 1;
 503
 504 }
 505
 506 /* stop */
 507 int com_stop(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 508 {
 509         if (argc != 1)
 510                 return -E_COMMAND_SYNTAX;
 511         mutex_lock(mmd_mutex);
 512         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 513         mmd->new_vss_status_flags &= ~VSS_REPOS;
 514         mmd->new_vss_status_flags |= VSS_NEXT;
 515         mutex_unlock(mmd_mutex);
 516         return 1;
 517 }
 518
 519 /* pause */
 520 int com_pause(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 521 {
 522         if (argc != 1)
 523                 return -E_COMMAND_SYNTAX;
 524         mutex_lock(mmd_mutex);
 525         if (!vss_paused() && !vss_stopped()) {
 526                 mmd->events++;
 527                 mmd->new_vss_status_flags &= ~VSS_PLAYING;
 528                 mmd->new_vss_status_flags &= ~VSS_NEXT;
 529         }
 530         mutex_unlock(mmd_mutex);
 531         return 1;
 532 }
 533
 534 /* next */
 535 int com_next(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 536 {
 537         if (argc != 1)
 538                 return -E_COMMAND_SYNTAX;
 539         mutex_lock(mmd_mutex);
 540         mmd->events++;
 541         mmd->new_vss_status_flags |= VSS_NEXT;
 542         mutex_unlock(mmd_mutex);
 543         return 1;
 544 }
 545
 546 /* nomore */
 547 int com_nomore(__a_unused struct rc4_context *rc4c, int argc, __a_unused char * const * argv)
 548 {
 549         if (argc != 1)
 550                 return -E_COMMAND_SYNTAX;
 551         mutex_lock(mmd_mutex);
 552         if (vss_playing() || vss_paused())
 553                 mmd->new_vss_status_flags |= VSS_NOMORE;
 554         mutex_unlock(mmd_mutex);
 555         return 1;
 556 }
 557
 558 /* ff */
 559 int com_ff(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 560 {
 561         long promille;
 562         int ret, backwards = 0;
 563         unsigned i;
 564         char c;
 565
 566         if (argc != 2)
 567                 return -E_COMMAND_SYNTAX;
 568         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 569                 return -E_COMMAND_SYNTAX;
 570         if (ret > 1 && c == '-')
 571                 backwards = 1; /* jmp backwards */
 572         mutex_lock(mmd_mutex);
 573         ret = -E_NO_AUDIO_FILE;
 574         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 575                 goto out;
 576         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 577         if (backwards)
 578                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 579         else
 580                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 581         if (promille < 0)
 582                 promille = 0;
 583         if (promille >  1000) {
 584                 mmd->new_vss_status_flags |= VSS_NEXT;
 585                 goto out;
 586         }
 587         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 588         mmd->new_vss_status_flags |= VSS_REPOS;
 589         mmd->new_vss_status_flags &= ~VSS_NEXT;
 590         mmd->events++;
 591         ret = 1;
 592 out:
 593         mutex_unlock(mmd_mutex);
 594         return ret;
 595 }
 596
 597 /* jmp */
 598 int com_jmp(__a_unused struct rc4_context *rc4c, int argc, char * const * argv)
 599 {
 600         long unsigned int i;
 601         int ret;
 602
 603         if (argc != 2)
 604                 return -E_COMMAND_SYNTAX;
 605         if (sscanf(argv[1], "%lu", &i) <= 0)
 606                 return -E_COMMAND_SYNTAX;
 607         mutex_lock(mmd_mutex);
 608         ret = -E_NO_AUDIO_FILE;
 609         if (!mmd->afd.afhi.chunks_total)
 610                 goto out;
 611         if (i > 100)
 612                 i = 100;
 613         PARA_INFO_LOG("jumping to %lu%%\n", i);
 614         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 615         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 616                 mmd->chunks_sent, mmd->offset);
 617         mmd->new_vss_status_flags |= VSS_REPOS;
 618         mmd->new_vss_status_flags &= ~VSS_NEXT;
 619         ret = 1;
 620         mmd->events++;
 621 out:
 622         mutex_unlock(mmd_mutex);
 623         return ret;
 624 }
 625
 626 /*
 627  * check if perms are sufficient to exec a command having perms cmd_perms.
 628  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 629  */
 630 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 631 {
 632         PARA_DEBUG_LOG("checking permissions\n");
 633         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 634 }
 635
 636 /*
 637  * Parse first string from *cmd and lookup in table of valid commands.
 638  * On error, NULL is returned.
 639  */
 640 static struct server_command *parse_cmd(const char *cmdstr)
 641 {
 642         char buf[255];
 643         int n = 0;
 644
 645         sscanf(cmdstr, "%200s%n", buf, &n);
 646         if (!n)
 647                 return NULL;
 648         buf[n] = '\0';
 649         return get_cmd_ptr(buf, NULL);
 650 }
 651
 652 static int read_command(struct rc4_context *rc4c, char **result)
 653 {
 654         int ret;
 655         char buf[4096];
 656         char *command = NULL;
 657
 658         for (;;) {
 659                 size_t numbytes;
 660                 char *p;
 661
 662                 ret = rc4_recv_buffer(rc4c, buf, sizeof(buf));
 663                 if (ret < 0)
 664                         goto out;
 665                 if (!ret)
 666                         break;
 667                 numbytes = ret;
 668                 ret = -E_COMMAND_SYNTAX;
 669                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 670                         goto out;
 671                 command = para_strcat(command, buf);
 672                 p = strstr(command, EOC_MSG);
 673                 if (p) {
 674                         *p = '\0';
 675                         break;
 676                 }
 677         }
 678         ret = command? 1 : -E_COMMAND_SYNTAX;
 679 out:
 680         if (ret < 0)
 681                 free(command);
 682         else
 683                 *result = command;
 684         return ret;
 685
 686 }
 687
 688 static void reset_signals(void)
 689 {
 690         para_sigaction(SIGCHLD, SIG_IGN);
 691         para_sigaction(SIGINT, SIG_DFL);
 692         para_sigaction(SIGTERM, SIG_DFL);
 693         para_sigaction(SIGHUP, SIG_DFL);
 694 }
 695
 696 /**
 697  * Perform user authentication and execute a command.
 698  *
 699  * \param fd The file descriptor to send output to.
 700  * \param peername Identifies the connecting peer.
 701  *
 702  * Whenever para_server accepts an incoming tcp connection on
 703  * the port it listens on, it forks and the resulting child
 704  * calls this function.
 705  *
 706  * An RSA-based challenge/response is used to authenticate
 707  * the peer. It that authentication succeeds, a random RC4
 708  * session key is generated and sent back to the peer,
 709  * encrypted with its RSA public key.  From this point on,
 710  * all transfers are crypted with this session key.
 711  *
 712  * Next it is checked if the peer supplied  a valid server command or a command
 713  * for the audio file selector.  If yes, and if the user has sufficient
 714  * permissions to execute that command, the function calls the corresponding
 715  * command handler which does argument checking and further processing.
 716  *
 717  * In order to cope with a DOS attacks, a timeout is set up
 718  * which terminates the function if the connection was not
 719  * authenticated when the timeout expires.
 720  *
 721  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 722  */
 723 __noreturn void handle_connect(int fd, const char *peername)
 724 {
 725         int ret, argc;
 726         char buf[4096];
 727         unsigned char rand_buf[CHALLENGE_SIZE + 2 * RC4_KEY_LEN];
 728         unsigned char challenge_sha1[HASH_SIZE];
 729         struct user *u;
 730         struct server_command *cmd = NULL;
 731         char **argv = NULL;
 732         char *p, *command = NULL;
 733         size_t numbytes;
 734         struct rc4_context rc4c = {.fd = fd};
 735
 736         reset_signals();
 737         /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
 738         ret = mark_fd_blocking(fd);
 739         if (ret < 0)
 740                 goto err_out;
 741         /* send Welcome message */
 742         ret = send_va_buffer(fd, "This is para_server, version "
 743                 PACKAGE_VERSION  ".\n" );
 744         if (ret < 0)
 745                 goto err_out;
 746         /* recv auth request line */
 747         ret = recv_buffer(fd, buf, sizeof(buf));
 748         if (ret < 0)
 749                 goto err_out;
 750         if (ret < 10) {
 751                 ret = -E_AUTH_REQUEST;
 752                 goto err_out;
 753         }
 754         numbytes = ret;
 755         ret = -E_AUTH_REQUEST;
 756         if (strncmp(buf, AUTH_REQUEST_MSG, strlen(AUTH_REQUEST_MSG)))
 757                 goto err_out;
 758         p = buf + strlen(AUTH_REQUEST_MSG);
 759         PARA_DEBUG_LOG("received auth request for user %s\n", p);
 760         ret = -E_BAD_USER;
 761         u = lookup_user(p);
 762         if (u) {
 763                 get_random_bytes_or_die(rand_buf, sizeof(rand_buf));
 764                 ret = para_encrypt_buffer(u->rsa, rand_buf, sizeof(rand_buf),
 765                         (unsigned char *)buf);
 766                 if (ret < 0)
 767                         goto err_out;
 768                 numbytes = ret;
 769         } else {
 770                 /*
 771                  * We don't want to reveal our user names, so we send a
 772                  * challenge to the client even if the user does not exist, and
 773                  * fail the authentication later.
 774                  */
 775                 numbytes = 256;
 776                 get_random_bytes_or_die((unsigned char *)buf, numbytes);
 777         }
 778         PARA_DEBUG_LOG("sending %zu byte challenge + rc4 keys (%u bytes)\n",
 779                 CHALLENGE_SIZE, numbytes);
 780         ret = send_bin_buffer(fd, buf, numbytes);
 781         if (ret < 0)
 782                 goto net_err;
 783         /* recv challenge response */
 784         ret = recv_bin_buffer(fd, buf, HASH_SIZE);
 785         if (ret < 0)
 786                 goto net_err;
 787         numbytes = ret;
 788         PARA_DEBUG_LOG("received %zu bytes challenge response\n", ret);
 789         ret = -E_BAD_USER;
 790         if (!u)
 791                 goto net_err;
 792         /*
 793          * The correct response is the sha1 of the first CHALLENGE_SIZE bytes
 794          * of the random data.
 795          */
 796         ret = -E_BAD_AUTH;
 797         if (numbytes != HASH_SIZE)
 798                 goto net_err;
 799         sha1_hash((char *)rand_buf, CHALLENGE_SIZE, challenge_sha1);
 800         if (memcmp(challenge_sha1, buf, HASH_SIZE))
 801                 goto net_err;
 802         /* auth successful */
 803         alarm(0);
 804         PARA_INFO_LOG("good auth for %s\n", u->name);
 805         /* init rc4 keys with the second part of the random buffer */
 806         RC4_set_key(&rc4c.recv_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE);
 807         RC4_set_key(&rc4c.send_key, RC4_KEY_LEN, rand_buf + CHALLENGE_SIZE
 808                 + RC4_KEY_LEN);
 809         ret = rc4_send_buffer(&rc4c, PROCEED_MSG);
 810         if (ret < 0)
 811                 goto net_err;
 812         ret = read_command(&rc4c, &command);
 813         if (ret == -E_COMMAND_SYNTAX)
 814                 goto err_out;
 815         if (ret < 0)
 816                 goto net_err;
 817         ret = -E_BAD_CMD;
 818         cmd = parse_cmd(command);
 819         if (!cmd)
 820                 goto err_out;
 821         /* valid command, check permissions */
 822         ret = check_perms(u->perms, cmd);
 823         if (ret < 0)
 824                 goto err_out;
 825         /* valid command and sufficient perms */
 826         argc = split_args(command, &argv, "\n");
 827         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 828                         peername);
 829         ret = cmd->handler(&rc4c, argc, argv);
 830         mutex_lock(mmd_mutex);
 831         mmd->num_commands++;
 832         mutex_unlock(mmd_mutex);
 833         if (ret >= 0)
 834                 goto out;
 835 err_out:
 836         rc4_send_va_buffer(&rc4c, "%s\n", para_strerror(-ret));
 837 net_err:
 838         PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
 839 out:
 840         free(command);
 841         free(argv);
 842         mutex_lock(mmd_mutex);
 843         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 844                 mmd->events++;
 845         mmd->active_connections--;
 846         mutex_unlock(mmd_mutex);
 847         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 848 }