command.c

   1 /*
   2  * Copyright (C) 1997-2007 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
  15 #include "para.h"
  16 #include "error.h"
  17 #include "server.cmdline.h"
  18 #include "string.h"
  19 #include "afh.h"
  20 #include "afs.h"
  21 #include "server.h"
  22 #include "vss.h"
  23 #include "send.h"
  24 #include "rc4.h"
  25 #include "net.h"
  26 #include "daemon.h"
  27 #include "fd.h"
  28 #include "list.h"
  29 #include "user_list.h"
  30 #include "server_command_list.h"
  31 #include "afs_command_list.h"
  32
  33 /** Commands including options must be shorter than this. */
  34 #define MAX_COMMAND_LEN 32768
  35
  36 static RC4_KEY rc4_recv_key;
  37 static RC4_KEY rc4_send_key;
  38 static unsigned char rc4_buf[2 * RC4_KEY_LEN];
  39
  40 extern const char *status_item_list[NUM_STAT_ITEMS];
  41 extern struct misc_meta_data *mmd;
  42 extern struct sender senders[];
  43
  44 static void dummy(__a_unused int s)
  45 {}
  46
  47 static void mmd_dup(struct misc_meta_data *new_mmd)
  48 {
  49         mmd_lock();
  50         *new_mmd = *mmd;
  51         mmd_unlock();
  52 }
  53
  54 /*
  55  * compute human readable string containing
  56  * vss status for given integer value
  57  */
  58 static char *vss_status_tohuman(unsigned int flags)
  59 {
  60         if (flags & VSS_PLAYING)
  61                 return para_strdup("playing");
  62         else if (flags & VSS_NEXT)
  63                 return para_strdup("stopped");
  64         else
  65                 return para_strdup("paused");
  66 }
  67
  68 /*
  69  * return human readable permission string. Never returns NULL.
  70  */
  71 static char *cmd_perms_itohuman(unsigned int perms)
  72 {
  73         char *msg = para_malloc(5 * sizeof(char));
  74
  75         msg[0] = perms & AFS_READ? 'a' : '-';
  76         msg[1] = perms & AFS_WRITE? 'A' : '-';
  77         msg[2] = perms & VSS_READ? 'v' : '-';
  78         msg[3] = perms & VSS_WRITE? 'V' : '-';
  79         msg[4] = '\0';
  80         return msg;
  81 }
  82
  83 /*
  84  * Never returns NULL.
  85  */
  86 static char *vss_get_status_flags(unsigned int flags)
  87 {
  88         char *msg = para_malloc(5 * sizeof(char));
  89
  90         msg[0] = (flags & VSS_PLAYING)? 'P' : '_';
  91         msg[1] = (flags & VSS_NOMORE)? 'O' : '_';
  92         msg[2] = (flags & VSS_NEXT)? 'N' : '_';
  93         msg[3] = (flags & VSS_REPOS)? 'R' : '_';
  94         msg[4] = '\0';
  95         return msg;
  96 }
  97
  98 static char *get_status(struct misc_meta_data *nmmd)
  99 {
 100         char *basename, *dirname, *ret, mtime[30] = "";
 101         char *status, *flags; /* vss status info */
 102         char *ut = uptime_str();
 103         long offset = (nmmd->offset + 500) / 1000;
 104         struct timeval now;
 105         struct tm mtime_tm;
 106
 107         /* report real status */
 108         status = vss_status_tohuman(nmmd->vss_status_flags);
 109         flags = vss_get_status_flags(nmmd->vss_status_flags);
 110         basename = para_basename(nmmd->afd.path);
 111         dirname = para_dirname(nmmd->afd.path);
 112         if (basename) {
 113                 localtime_r(&nmmd->mtime, &mtime_tm);
 114                 strftime(mtime, 29, "%a %b %d %Y", &mtime_tm);
 115         }
 116         gettimeofday(&now, NULL);
 117         ret = make_message(
 118                 "%s:%zu\n"      "%s:%s\n"               "%s:%lu\n"
 119                 "%s:%s\n"       "%s:%s\n"       "%s:%s\n"
 120                 "%s:%li\n"      "%s:%s\n"
 121                 "%s:%s\n"       "%s:%lu.%lu\n"  "%s:%lu.%lu\n"
 122                 "%s:%s\n"       "%s\n",
 123                 status_item_list[SI_FILE_SIZE], nmmd->size / 1024,
 124                 status_item_list[SI_MTIME], mtime,
 125                 status_item_list[SI_LENGTH], nmmd->afd.afhi.seconds_total,
 126
 127                 status_item_list[SI_BASENAME], basename ? basename : "(none)",
 128                 status_item_list[SI_STATUS], status,
 129                 status_item_list[SI_STATUS_FLAGS], flags,
 130
 131                 status_item_list[SI_OFFSET], offset,
 132                 status_item_list[SI_AFS_MODE], mmd->afs_mode_string,
 133
 134                 status_item_list[SI_UPTIME], ut,
 135                 status_item_list[SI_STREAM_START],
 136                         (long unsigned)nmmd->stream_start.tv_sec,
 137                         (long unsigned)nmmd->stream_start.tv_usec,
 138                 status_item_list[SI_CURRENT_TIME],
 139                         (long unsigned)now.tv_sec,
 140                         (long unsigned)now.tv_usec,
 141
 142                 status_item_list[SI_DIRECTORY], dirname? dirname : "(none)",
 143                 nmmd->afd.afs_status_info
 144
 145         );
 146         free(basename);
 147         free(dirname);
 148         free(flags);
 149         free(status);
 150         free(ut);
 151         return ret;
 152 }
 153
 154 static int check_sender_args(int argc, char * const * argv, struct sender_command_data *scd)
 155 {
 156         int i;
 157         /* this has to match sender.h */
 158         const char *subcmds[] = {"add", "delete", "allow", "deny", "on", "off", NULL};
 159
 160         scd->sender_num = -1;
 161         if (argc < 2)
 162                 return -E_COMMAND_SYNTAX;
 163         for (i = 0; senders[i].name; i++)
 164                 if (!strcmp(senders[i].name, argv[1]))
 165                         break;
 166         PARA_DEBUG_LOG("%d:%s\n", argc, argv[1]);
 167         if (!senders[i].name)
 168                 return -E_COMMAND_SYNTAX;
 169         scd->sender_num = i;
 170         for (i = 0; subcmds[i]; i++)
 171                 if (!strcmp(subcmds[i], argv[2]))
 172                         break;
 173         if (!subcmds[i])
 174                 return -E_COMMAND_SYNTAX;
 175         scd->cmd_num = i;
 176         mmd_lock();
 177         if (!senders[scd->sender_num].client_cmds[scd->cmd_num]) {
 178                 mmd_unlock();
 179                 return -E_SENDER_CMD;
 180         }
 181         mmd_unlock();
 182         switch (scd->cmd_num) {
 183         case SENDER_ON:
 184         case SENDER_OFF:
 185                 if (argc != 3)
 186                         return -E_COMMAND_SYNTAX;
 187                 break;
 188         case SENDER_DENY:
 189         case SENDER_ALLOW:
 190                 if (argc != 4 && argc != 5)
 191                         return -E_COMMAND_SYNTAX;
 192                 if (!inet_pton(AF_INET, argv[3], &scd->addr))
 193                         return -E_COMMAND_SYNTAX;
 194                 scd->netmask = 32;
 195                 if (argc == 5) {
 196                         scd->netmask = atoi(argv[4]);
 197                         if (scd->netmask < 0 || scd->netmask > 32)
 198                                 return -E_COMMAND_SYNTAX;
 199                 }
 200                 break;
 201         case SENDER_ADD:
 202         case SENDER_DELETE:
 203                 if (argc != 4 && argc != 5)
 204                         return -E_COMMAND_SYNTAX;
 205                 if (!inet_pton(AF_INET, argv[3], &scd->addr))
 206                         return -E_COMMAND_SYNTAX;
 207                 scd->port = -1;
 208                 if (argc == 5) {
 209                         scd->port = atoi(argv[4]);
 210                         if (scd->port < 0 || scd->port > 65535)
 211                                 return -E_COMMAND_SYNTAX;
 212                 }
 213                 break;
 214         default:
 215                 return -E_COMMAND_SYNTAX;
 216         }
 217         return 1;
 218 }
 219
 220 int com_sender(int fd, int argc, char * const * argv)
 221 {
 222         int i, ret;
 223         struct sender_command_data scd;
 224
 225         if (argc < 2) {
 226                 char *msg = NULL;
 227                 for (i = 0; senders[i].name; i++) {
 228                         char *tmp = make_message("%s%s\n",
 229                                 msg? msg : "", senders[i].name);
 230                         free(msg);
 231                         msg = tmp;
 232                 }
 233                 ret = send_buffer(fd, msg);
 234                 free(msg);
 235                 return ret;
 236         }
 237         ret = check_sender_args(argc, argv, &scd);
 238         if (ret < 0) {
 239                 char *msg;
 240                 if (scd.sender_num < 0)
 241                         return ret;
 242                 msg = senders[scd.sender_num].help();
 243                 send_buffer(fd, msg);
 244                 free(msg);
 245                 return 1;
 246         }
 247         for (i = 0; i < 10; i++) {
 248                 mmd_lock();
 249                 if (mmd->sender_cmd_data.cmd_num >= 0) {
 250                         mmd_unlock();
 251                         usleep(100 * 1000);
 252                         continue;
 253                 }
 254                 mmd->sender_cmd_data = scd;
 255                 mmd_unlock();
 256                 break;
 257         }
 258         return (i < 10)? 1 : -E_LOCK;
 259 }
 260
 261 /* server info */
 262 int com_si(int fd, int argc, __a_unused char * const * argv)
 263 {
 264         int i, ret;
 265         char *ut;
 266         char *sender_info = NULL, *sender_list = NULL;
 267
 268         if (argc != 1)
 269                 return -E_COMMAND_SYNTAX;
 270         mmd_lock();
 271         for (i = 0; senders[i].name; i++) {
 272                 char *info = senders[i].info();
 273                 sender_info = para_strcat(sender_info, info);
 274                 free(info);
 275                 sender_list = para_strcat(sender_list, senders[i].name);
 276                 sender_list = para_strcat(sender_list, " ");
 277         }
 278         ut = uptime_str();
 279         ret = send_va_buffer(fd, "up: %s\nplayed: %u\n"
 280                 "pid: %d\n"
 281                 "connections (active/accepted/total): %u/%u/%u\n"
 282                 "current loglevel: %i\n"
 283                 "supported audio formats: %s\n"
 284                 "supported senders: %s\n"
 285                 "%s",
 286                 ut, mmd->num_played,
 287                 getppid(),
 288                 mmd->active_connections,
 289                 mmd->num_commands,
 290                 mmd->num_connects,
 291                 conf.loglevel_arg,
 292                 supported_audio_formats(),
 293                 sender_list,
 294                 sender_info
 295         );
 296         mmd_unlock();
 297         free(ut);
 298         free(sender_list);
 299         free(sender_info);
 300         return ret;
 301 }
 302
 303 /* version */
 304 int com_version(int fd, int argc, __a_unused char * const * argv)
 305 {
 306         if (argc != 1)
 307                 return -E_COMMAND_SYNTAX;
 308         return send_buffer(fd, VERSION_TEXT("server")
 309                 "built: " BUILD_DATE "\n"
 310                 SYSTEM ", " CC_VERSION "\n"
 311         );
 312 }
 313
 314 /* stat */
 315 int com_stat(int fd, int argc, char * const * argv)
 316 {
 317         int ret, num = 0;/* status will be printed that many
 318                           * times. num <= 0 means: print forever
 319                           */
 320         struct misc_meta_data tmp, *nmmd = &tmp;
 321         char *s;
 322
 323         signal(SIGUSR1, dummy);
 324
 325         if (argc > 1)
 326                 num = atoi(argv[1]);
 327         for (;;) {
 328
 329                 mmd_dup(nmmd);
 330                 s = get_status(nmmd);
 331                 ret = send_buffer(fd, s);
 332                 free(s);
 333                 if (ret < 0)
 334                         goto out;
 335                 ret = 1;
 336                 if (num == 1)
 337                         goto out;
 338                 sleep(50);
 339                 if (getppid() == 1)
 340                         return -E_SERVER_CRASH;
 341         }
 342 out:
 343         return ret;
 344 }
 345
 346 static int send_list_of_commands(int fd, struct server_command *cmd,
 347                 const char *handler)
 348 {
 349         int ret, i;
 350
 351         for (i = 1; cmd->name; cmd++, i++) {
 352                 char *perms = cmd_perms_itohuman(cmd->perms);
 353                 ret = send_va_buffer(fd, "%s\t%s\t%s\t%s\n", cmd->name,
 354                         handler,
 355                         perms,
 356                         cmd->description);
 357                 free(perms);
 358                 if (ret < 0)
 359                         return ret;
 360         }
 361         return 1;
 362 }
 363
 364 /* returns string that must be freed by the caller */
 365 static struct server_command *get_cmd_ptr(const char *name, char **handler)
 366 {
 367         struct server_command *cmd;
 368
 369         for (cmd = server_cmds; cmd->name; cmd++)
 370                 if (!strcmp(cmd->name, name)) {
 371                         if (handler)
 372                                 *handler = para_strdup("server"); /* server commands */
 373                         return cmd;
 374                 }
 375         /* not found, look for commands supported by afs */
 376         for (cmd = afs_cmds; cmd->name; cmd++)
 377                 if (!strcmp(cmd->name, name)) {
 378                         if (handler)
 379                                 *handler = para_strdup("afs");
 380                         return cmd;
 381                 }
 382         return NULL;
 383 }
 384
 385 /* help */
 386 int com_help(int fd, int argc, char * const * argv)
 387 {
 388         struct server_command *cmd;
 389         char *perms, *handler;
 390         int ret;
 391
 392         if (argc < 2) {
 393                 /* no argument given, print list of commands */
 394                 if ((ret = send_list_of_commands(fd, server_cmds, "server")) < 0)
 395                         return ret;
 396                 return send_list_of_commands(fd, afs_cmds, "afs");
 397         }
 398         /* argument given for help */
 399         cmd = get_cmd_ptr(argv[1], &handler);
 400         if (!cmd) {
 401                 free(handler);
 402                 return -E_BAD_CMD;
 403         }
 404         perms = cmd_perms_itohuman(cmd->perms);
 405         ret = send_va_buffer(fd,
 406                 "%s - %s\n\n"
 407                 "handler: %s\n"
 408                 "permissions: %s\n"
 409                 "usage: %s\n\n"
 410                 "%s\n",
 411                 argv[1],
 412                 cmd->description,
 413                 handler,
 414                 perms,
 415                 cmd->usage,
 416                 cmd->help
 417         );
 418         free(perms);
 419         free(handler);
 420         return ret;
 421 }
 422
 423 /* hup */
 424 int com_hup(__a_unused int fd, int argc, __a_unused char * const * argv)
 425 {
 426         if (argc != 1)
 427                 return -E_COMMAND_SYNTAX;
 428         kill(getppid(), SIGHUP);
 429         return 1;
 430 }
 431
 432 /* term */
 433 int com_term(__a_unused int fd, int argc, __a_unused char * const * argv)
 434 {
 435         if (argc != 1)
 436                 return -E_COMMAND_SYNTAX;
 437         kill(getppid(), SIGTERM);
 438         return 1;
 439 }
 440
 441 int com_play(__a_unused int fd, int argc, __a_unused char * const * argv)
 442 {
 443         if (argc != 1)
 444                 return -E_COMMAND_SYNTAX;
 445         mmd_lock();
 446         mmd->new_vss_status_flags |= VSS_PLAYING;
 447         mmd->new_vss_status_flags &= ~VSS_NOMORE;
 448         mmd_unlock();
 449         return 1;
 450
 451 }
 452
 453 /* stop */
 454 int com_stop(__a_unused int fd, int argc, __a_unused char * const * argv)
 455 {
 456         if (argc != 1)
 457                 return -E_COMMAND_SYNTAX;
 458         mmd_lock();
 459         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 460         mmd->new_vss_status_flags &= ~VSS_REPOS;
 461         mmd->new_vss_status_flags |= VSS_NEXT;
 462         mmd_unlock();
 463         return 1;
 464 }
 465
 466 /* pause */
 467 int com_pause(__a_unused int fd, int argc, __a_unused char * const * argv)
 468 {
 469         if (argc != 1)
 470                 return -E_COMMAND_SYNTAX;
 471         mmd_lock();
 472         if (!vss_paused())
 473                 mmd->events++;
 474         mmd->new_vss_status_flags &= ~VSS_PLAYING;
 475         mmd->new_vss_status_flags &= ~VSS_NEXT;
 476         mmd_unlock();
 477         return 1;
 478 }
 479
 480 /* next */
 481 int com_next(__a_unused int fd, int argc, __a_unused char * const * argv)
 482 {
 483         if (argc != 1)
 484                 return -E_COMMAND_SYNTAX;
 485         mmd_lock();
 486         mmd->events++;
 487         mmd->new_vss_status_flags |= VSS_NEXT;
 488         mmd_unlock();
 489         return 1;
 490 }
 491
 492 /* nomore */
 493 int com_nomore(__a_unused int fd, int argc, __a_unused char * const * argv)
 494 {
 495         if (argc != 1)
 496                 return -E_COMMAND_SYNTAX;
 497         mmd_lock();
 498         if (vss_playing() || vss_paused())
 499                 mmd->new_vss_status_flags |= VSS_NOMORE;
 500         mmd_unlock();
 501         return 1;
 502 }
 503
 504 /* ff */
 505 int com_ff(__a_unused int fd, int argc, char * const * argv)
 506 {
 507         long promille;
 508         int ret, backwards = 0;
 509         unsigned i;
 510         char c;
 511
 512         if (argc != 2)
 513                 return -E_COMMAND_SYNTAX;
 514         if (!(ret = sscanf(argv[1], "%u%c", &i, &c)))
 515                 return -E_COMMAND_SYNTAX;
 516         if (ret > 1 && c == '-')
 517                 backwards = 1; /* jmp backwards */
 518         mmd_lock();
 519         ret = -E_NO_AUDIO_FILE;
 520         if (!mmd->afd.afhi.chunks_total || !mmd->afd.afhi.seconds_total)
 521                 goto out;
 522         promille = (1000 * mmd->current_chunk) / mmd->afd.afhi.chunks_total;
 523         if (backwards)
 524                 promille -= 1000 * i / mmd->afd.afhi.seconds_total;
 525         else
 526                 promille += 1000 * i / mmd->afd.afhi.seconds_total;
 527         if (promille < 0)
 528                 promille = 0;
 529         if (promille >  1000) {
 530                 mmd->new_vss_status_flags |= VSS_NEXT;
 531                 goto out;
 532         }
 533         mmd->repos_request = (mmd->afd.afhi.chunks_total * promille) / 1000;
 534         mmd->new_vss_status_flags |= VSS_REPOS;
 535         mmd->new_vss_status_flags &= ~VSS_NEXT;
 536         mmd->events++;
 537         ret = 1;
 538 out:
 539         mmd_unlock();
 540         return ret;
 541 }
 542
 543 /* jmp */
 544 int com_jmp(__a_unused int fd, int argc, char * const * argv)
 545 {
 546         long unsigned int i;
 547         int ret;
 548
 549         if (argc != 2)
 550                 return -E_COMMAND_SYNTAX;
 551         if (sscanf(argv[1], "%lu", &i) <= 0)
 552                 return -E_COMMAND_SYNTAX;
 553         mmd_lock();
 554         ret = -E_NO_AUDIO_FILE;
 555         if (!mmd->afd.afhi.chunks_total)
 556                 goto out;
 557         if (i > 100)
 558                 i = 100;
 559         PARA_INFO_LOG("jumping to %lu%%\n", i);
 560         mmd->repos_request = (mmd->afd.afhi.chunks_total * i + 50)/ 100;
 561         PARA_INFO_LOG("sent: %lu,  offset before jmp: %lu\n",
 562                 mmd->chunks_sent, mmd->offset);
 563         mmd->new_vss_status_flags |= VSS_REPOS;
 564         mmd->new_vss_status_flags &= ~VSS_NEXT;
 565         ret = 1;
 566         mmd->events++;
 567 out:
 568         mmd_unlock();
 569         return ret;
 570 }
 571
 572 /*
 573  * check if perms are sufficient to exec a command having perms cmd_perms.
 574  * Returns 0 if perms are sufficient, -E_PERM otherwise.
 575  */
 576 static int check_perms(unsigned int perms, struct server_command *cmd_ptr)
 577 {
 578         PARA_DEBUG_LOG("%s", "checking permissions\n");
 579         return (cmd_ptr->perms & perms) < cmd_ptr->perms ? -E_PERM : 0;
 580 }
 581
 582 /*
 583  * Parse first string from *cmd and lookup in table of valid commands.
 584  * On error, NULL is returned.
 585  */
 586 static struct server_command *parse_cmd(const char *cmdstr)
 587 {
 588         char buf[255];
 589         int n = 0;
 590
 591         sscanf(cmdstr, "%200s%n", buf, &n);
 592         if (!n)
 593                 return NULL;
 594         buf[n] = '\0';
 595         return get_cmd_ptr(buf, NULL);
 596 }
 597
 598 static void init_rc4_keys(void)
 599 {
 600         int i;
 601
 602         for (i = 0; i < 2 * RC4_KEY_LEN; i++)
 603                 rc4_buf[i] = para_random(256);
 604         PARA_DEBUG_LOG("rc4 keys initialized (%u:%u)\n",
 605                 (unsigned char) rc4_buf[0],
 606                 (unsigned char) rc4_buf[RC4_KEY_LEN]);
 607         RC4_set_key(&rc4_recv_key, RC4_KEY_LEN, rc4_buf);
 608         RC4_set_key(&rc4_send_key, RC4_KEY_LEN, rc4_buf + RC4_KEY_LEN);
 609 }
 610
 611 static void rc4_recv(unsigned long len, const unsigned char *indata,
 612                 unsigned char *outdata, __a_unused void *private_data)
 613 {
 614         RC4(&rc4_recv_key, len, indata, outdata);
 615 }
 616
 617 static void rc4_send(unsigned long len, const unsigned char *indata,
 618                 unsigned char *outdata, __a_unused void *private_data)
 619 {
 620         RC4(&rc4_send_key, len, indata, outdata);
 621 }
 622
 623 static int read_command(int fd, char **result)
 624 {
 625         int ret;
 626         char buf[4096];
 627         char *command = NULL;
 628
 629         for (;;) {
 630                 size_t numbytes;
 631                 char *p;
 632
 633                 ret = recv_buffer(fd, buf, sizeof(buf));
 634                 if (ret < 0)
 635                         goto out;
 636                 if (!ret)
 637                         break;
 638                 numbytes = ret;
 639                 ret = -E_COMMAND_SYNTAX;
 640                 if (command && numbytes + strlen(command) > MAX_COMMAND_LEN) /* DOS */
 641                         goto out;
 642                 command = para_strcat(command, buf);
 643                 p = strstr(command, EOC_MSG);
 644                 if (p) {
 645                         *p = '\0';
 646                         break;
 647                 }
 648         }
 649         ret = command? 1 : -E_COMMAND_SYNTAX;
 650 out:
 651         if (ret < 0)
 652                 free(command);
 653         else
 654                 *result = command;
 655         return ret;
 656
 657 }
 658
 659 /**
 660  * perform user authentication and execute a command
 661  *
 662  * \param fd the file descriptor to send output to
 663  * \param addr socket address info of peer
 664  *
 665  * \return EXIT_SUCCESS or EXIT_FAILURE
 666  *
 667  * Whenever para_server accepts an incoming tcp connection on
 668  * the port it listens on, it forks and the resulting child
 669  * calls this function.
 670  *
 671  * An RSA-based challenge/response is used to authenticate
 672  * the peer. It that authentication succeeds, a random RC4
 673  * session key is generated and sent back to the peer,
 674  * encrypted with its RSA public key.  From this point on,
 675  * all transfers are crypted with this session key.
 676  *
 677  * Next it is checked if the peer supplied  a valid server command or a command
 678  * for the audio file selector.  If yes, and if the user has sufficient
 679  * permissions to execute that command, the function calls the corresponding
 680  * command handler which does argument checking and further processing.
 681  *
 682  * In order to cope with a DOS attacks, a timeout is set up
 683  * which terminates the function if the connection was not
 684  * authenticated when the timeout expires.
 685  *
 686  * \sa alarm(2), rc4(3), crypt.c, crypt.h
 687  */
 688 int handle_connect(int fd, struct sockaddr_in *addr)
 689 {
 690         int ret, argc, use_rc4 = 0;
 691         char buf[4096];
 692         unsigned char crypt_buf[MAXLINE];
 693         struct user *u;
 694         struct server_command *cmd = NULL;
 695         long unsigned challenge_nr, chall_response;
 696         char **argv = NULL;
 697         char *p, *command = NULL;
 698         size_t numbytes;
 699
 700         signal(SIGCHLD, SIG_IGN);
 701         signal(SIGINT, SIG_DFL);
 702         signal(SIGTERM, SIG_DFL);
 703         signal(SIGHUP, SIG_DFL);
 704         signal(SIGUSR1, SIG_IGN);
 705
 706         challenge_nr = random();
 707         /* send Welcome message */
 708         ret = send_va_buffer(fd, "This is para_server, version "
 709                 PACKAGE_VERSION  ".\n" );
 710         if (ret < 0)
 711                 goto err_out;
 712         /* recv auth request line */
 713         ret = recv_buffer(fd, buf, sizeof(buf));
 714         if (ret < 0)
 715                 goto err_out;
 716         if (ret <= 6) {
 717                 ret = -E_AUTH;
 718                 goto err_out;
 719         }
 720         numbytes = ret;
 721         ret = -E_AUTH;
 722         if (strncmp(buf, "auth ", 5))
 723                 goto err_out;
 724
 725         if (numbytes < 9 || strncmp(buf, "auth rc4 ", 9))
 726                 p = buf + 5; /* client version < 0.2.6 */
 727         else {
 728                 p = buf + 9; /* client version >= 0.2.6 */
 729                 use_rc4 = 1;
 730         }
 731         PARA_DEBUG_LOG("received %s request for user %s\n",
 732                 use_rc4? "rc4" : "auth", p);
 733         ret = -E_BAD_USER;
 734         u = lookup_user(p);
 735         if (!u)
 736                 goto err_out;
 737         ret = para_encrypt_challenge(u->rsa, challenge_nr, crypt_buf);
 738         if (ret <= 0)
 739                 goto err_out;
 740         numbytes = ret;
 741         PARA_DEBUG_LOG("sending %zu byte challenge\n", numbytes);
 742         /* We can't use send_buffer here since buf may contain null bytes */
 743         ret = send_bin_buffer(fd,(char *) crypt_buf, numbytes);
 744         if (ret < 0)
 745                 goto err_out;
 746         /* recv decrypted number */
 747         ret = recv_buffer(fd, buf, sizeof(buf));
 748         if (ret < 0)
 749                 goto err_out;
 750         numbytes = ret;
 751         ret = -E_AUTH;
 752         if (!numbytes)
 753                 goto err_out;
 754         if (sscanf(buf, CHALLENGE_RESPONSE_MSG "%lu", &chall_response) < 1
 755                         || chall_response != challenge_nr)
 756                 goto err_out;
 757         /* auth successful, send 'Proceed' message */
 758         PARA_INFO_LOG("good auth for %s (%lu)\n", u->name, challenge_nr);
 759         sprintf(buf, "%s", PROCEED_MSG);
 760         if (use_rc4) {
 761                 init_rc4_keys();
 762                 ret = para_encrypt_buffer(u->rsa, rc4_buf, 2 * RC4_KEY_LEN,
 763                         (unsigned char *)buf + PROCEED_MSG_LEN + 1);
 764                 if (ret <= 0)
 765                         goto err_out;
 766                 numbytes = ret + strlen(PROCEED_MSG) + 1;
 767         } else
 768                 numbytes = strlen(buf);
 769         ret = send_bin_buffer(fd, buf, numbytes);
 770         if (ret < 0)
 771                 goto err_out;
 772         if (use_rc4)
 773                 enable_crypt(fd, rc4_recv, rc4_send, NULL);
 774         ret = read_command(fd, &command);
 775         if (ret < 0)
 776                 goto err_out;
 777         ret = -E_BAD_CMD;
 778         cmd = parse_cmd(command);
 779         if (!cmd)
 780                 goto err_out;
 781         /* valid command, check permissions */
 782         ret = check_perms(u->perms, cmd);
 783         if (ret < 0)
 784                 goto err_out;
 785         /* valid command and sufficient perms */
 786         alarm(0);
 787         argc = split_args(command, &argv, "\n");
 788         mmd_lock();
 789         mmd->num_commands++;
 790         mmd_unlock();
 791         PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cmd->name, u->name,
 792                 inet_ntoa(addr->sin_addr));
 793         ret = cmd->handler(fd, argc, argv);
 794         if (ret >= 0) {
 795                 ret = EXIT_SUCCESS;
 796                 goto out;
 797         }
 798 err_out:
 799         PARA_NOTICE_LOG("%s\n", PARA_STRERROR(-ret));
 800         if (ret != -E_SEND && ret != -E_RECV)
 801                 send_va_buffer(fd, "%s\n", PARA_STRERROR(-ret));
 802         ret = EXIT_FAILURE;
 803 out:
 804         free(command);
 805         free(argv);
 806         mmd_lock();
 807         if (cmd && (cmd->perms & AFS_WRITE) && ret >= 0)
 808                 mmd->events++;
 809         mmd->active_connections--;
 810         mmd_unlock();
 811         return ret;
 812 }