usr.sbin/ppp/main.c

   1 /*-
   2  * Copyright (c) 1996 - 2001 Brian Somers <brian@Awfulhak.org>
   3  *          based on work by Toshiharu OHNO <tony-o@iij.ad.jp>
   4  *                           Internet Initiative Japan, Inc (IIJ)
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  * $FreeBSD: src/usr.sbin/ppp/main.c,v 1.167.2.8 2002/09/01 02:12:28 brian Exp $
  29  * $DragonFly: src/usr.sbin/ppp/main.c,v 1.2 2003/06/17 04:30:00 dillon Exp $
  30  */
  31
  32 #include <sys/param.h>
  33 #include <netinet/in.h>
  34 #include <netinet/in_systm.h>
  35 #include <netinet/ip.h>
  36 #include <sys/un.h>
  37 #include <sys/socket.h>
  38 #include <net/route.h>
  39
  40 #include <errno.h>
  41 #include <fcntl.h>
  42 #include <paths.h>
  43 #include <signal.h>
  44 #include <stdarg.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <sys/time.h>
  49 #include <termios.h>
  50 #include <unistd.h>
  51 #include <sys/stat.h>
  52
  53 #ifndef NONAT
  54 #ifdef LOCALNAT
  55 #include "alias.h"
  56 #else
  57 #include <alias.h>
  58 #endif
  59 #endif
  60
  61 #include "layer.h"
  62 #include "probe.h"
  63 #include "mbuf.h"
  64 #include "log.h"
  65 #include "defs.h"
  66 #include "id.h"
  67 #include "timer.h"
  68 #include "fsm.h"
  69 #include "lqr.h"
  70 #include "hdlc.h"
  71 #include "lcp.h"
  72 #include "ccp.h"
  73 #include "iplist.h"
  74 #include "throughput.h"
  75 #include "slcompress.h"
  76 #include "ncpaddr.h"
  77 #include "ipcp.h"
  78 #include "filter.h"
  79 #include "descriptor.h"
  80 #include "link.h"
  81 #include "mp.h"
  82 #ifndef NORADIUS
  83 #include "radius.h"
  84 #endif
  85 #include "ipv6cp.h"
  86 #include "ncp.h"
  87 #include "bundle.h"
  88 #include "auth.h"
  89 #include "systems.h"
  90 #include "sig.h"
  91 #include "main.h"
  92 #include "server.h"
  93 #include "prompt.h"
  94 #include "chat.h"
  95 #include "chap.h"
  96 #include "cbcp.h"
  97 #include "datalink.h"
  98 #include "iface.h"
  99
 100 #ifndef O_NONBLOCK
 101 #ifdef O_NDELAY
 102 #define O_NONBLOCK O_NDELAY
 103 #endif
 104 #endif
 105
 106 static void DoLoop(struct bundle *);
 107 static void TerminalStop(int);
 108
 109 static struct bundle *SignalBundle;
 110 static struct prompt *SignalPrompt;
 111
 112 void
 113 Cleanup(void)
 114 {
 115   SignalBundle->CleaningUp = 1;
 116   bundle_Close(SignalBundle, NULL, CLOSE_STAYDOWN);
 117 }
 118
 119 void
 120 AbortProgram(int excode)
 121 {
 122   if (SignalBundle)
 123     server_Close(SignalBundle);
 124   log_Printf(LogPHASE, "PPP Terminated (%s).\n", ex_desc(excode));
 125   if (SignalBundle) {
 126     bundle_Close(SignalBundle, NULL, CLOSE_STAYDOWN);
 127     bundle_Destroy(SignalBundle);
 128   }
 129   log_Close();
 130   exit(excode);
 131 }
 132
 133 static void
 134 CloseConnection(int signo)
 135 {
 136   /* NOTE, these are manual, we've done a setsid() */
 137   sig_signal(SIGINT, SIG_IGN);
 138   log_Printf(LogPHASE, "Caught signal %d, abort connection(s)\n", signo);
 139   bundle_Down(SignalBundle, CLOSE_STAYDOWN);
 140   sig_signal(SIGINT, CloseConnection);
 141 }
 142
 143 static void
 144 CloseSession(int signo)
 145 {
 146   log_Printf(LogPHASE, "Signal %d, terminate.\n", signo);
 147   Cleanup();
 148 }
 149
 150 static pid_t BGPid = 0;
 151
 152 static void
 153 KillChild(int signo)
 154 {
 155   signal(signo, SIG_IGN);
 156   log_Printf(LogPHASE, "Parent: Signal %d\n", signo);
 157   kill(BGPid, SIGINT);
 158 }
 159
 160 static void
 161 TerminalCont(int signo __unused)
 162 {
 163   signal(SIGCONT, SIG_DFL);
 164   prompt_Continue(SignalPrompt);
 165 }
 166
 167 static void
 168 TerminalStop(int signo __unused)
 169 {
 170   prompt_Suspend(SignalPrompt);
 171   signal(SIGCONT, TerminalCont);
 172   raise(SIGSTOP);
 173 }
 174
 175 static void
 176 BringDownServer(int signo __unused)
 177 {
 178   /* Drops all child prompts too ! */
 179   if (server_Close(SignalBundle))
 180     log_Printf(LogPHASE, "Closed server socket\n");
 181 }
 182
 183 static void
 184 RestartServer(int signo __unused)
 185 {
 186   /* Drops all child prompts and re-opens the socket */
 187   server_Reopen(SignalBundle);
 188 }
 189
 190 static void
 191 Usage(void)
 192 {
 193   fprintf(stderr, "usage: ppp [-auto | -foreground | -background | -direct |"
 194           " -dedicated | -ddial | -interactive]"
 195 #ifndef NOALIAS
 196           " [-nat]"
 197 #endif
 198           " [-quiet] [-unit N] [system ...]\n");
 199   exit(EX_START);
 200 }
 201
 202 struct switches {
 203   unsigned nat : 1;
 204   unsigned fg : 1;
 205   unsigned quiet : 1;
 206   int mode;
 207   int unit;
 208 };
 209
 210 static int
 211 ProcessArgs(int argc, char **argv, struct switches *sw)
 212 {
 213   int optc, newmode, arg;
 214   char *cp;
 215
 216   optc = 0;
 217   memset(sw, '\0', sizeof *sw);
 218   sw->mode = PHYS_INTERACTIVE;
 219   sw->unit = -1;
 220
 221   for (arg = 1; arg < argc && *argv[arg] == '-'; arg++, optc++) {
 222     cp = argv[arg] + 1;
 223     newmode = Nam2mode(cp);
 224     switch (newmode) {
 225       case PHYS_NONE:
 226         if (strcmp(cp, "nat") == 0) {
 227 #ifdef NONAT
 228           log_Printf(LogWARN, "%s ignored: NAT is compiled out\n", argv[arg]);
 229 #else
 230           sw->nat = 1;
 231 #endif
 232           optc--;                       /* this option isn't exclusive */
 233         } else if (strcmp(cp, "alias") == 0) {
 234 #ifdef NONAT
 235           log_Printf(LogWARN, "%s ignored: NAT is compiled out\n", argv[arg]);
 236           fprintf(stderr, "%s ignored: NAT is compiled out\n", argv[arg]);
 237 #else
 238           log_Printf(LogWARN, "%s is deprecated\n", argv[arg]);
 239           fprintf(stderr, "%s is deprecated\n", argv[arg]);
 240           sw->nat = 1;
 241 #endif
 242           optc--;                       /* this option isn't exclusive */
 243         } else if (strncmp(cp, "unit", 4) == 0) {
 244           optc--;                       /* this option isn't exclusive */
 245           if (cp[4] == '\0') {
 246             optc--;                     /* nor is the argument */
 247             if (++arg == argc) {
 248               fprintf(stderr, "-unit: Expected unit number\n");
 249               Usage();
 250             } else
 251               sw->unit = atoi(argv[arg]);
 252           } else
 253             sw->unit = atoi(cp + 4);
 254         } else if (strcmp(cp, "quiet") == 0) {
 255           sw->quiet = 1;
 256           optc--;                       /* this option isn't exclusive */
 257         } else
 258           Usage();
 259         break;
 260
 261       case PHYS_ALL:
 262         Usage();
 263         break;
 264
 265       default:
 266         sw->mode = newmode;
 267         if (newmode == PHYS_FOREGROUND)
 268           sw->fg = 1;
 269     }
 270   }
 271
 272   if (optc > 1) {
 273     fprintf(stderr, "You may specify only one mode.\n");
 274     exit(EX_START);
 275   }
 276
 277   if (sw->mode == PHYS_AUTO && arg == argc) {
 278     fprintf(stderr, "A system must be specified in auto mode.\n");
 279     exit(EX_START);
 280   }
 281
 282   return arg;           /* Don't SetLabel yet ! */
 283 }
 284
 285 static void
 286 CheckLabel(const char *label, struct prompt *prompt, int mode)
 287 {
 288   const char *err;
 289
 290   if ((err = system_IsValid(label, prompt, mode)) != NULL) {
 291     fprintf(stderr, "%s: %s\n", label, err);
 292     if (mode == PHYS_DIRECT)
 293       log_Printf(LogWARN, "Label %s rejected -direct connection: %s\n",
 294                  label, err);
 295     log_Close();
 296     exit(1);
 297   }
 298 }
 299
 300
 301 int
 302 main(int argc, char **argv)
 303 {
 304   char *name;
 305   const char *lastlabel;
 306   int arg, holdfd[3], label;
 307   unsigned f;
 308   struct bundle *bundle;
 309   struct prompt *prompt;
 310   struct switches sw;
 311
 312   probe_Init();
 313
 314   /*
 315    * We open 3 descriptors to ensure that STDIN_FILENO, STDOUT_FILENO and
 316    * STDERR_FILENO are always open.  These are closed before DoLoop(),
 317    * but *after* we've avoided the possibility of erroneously closing
 318    * an important descriptor with close(STD{IN,OUT,ERR}_FILENO).
 319    */
 320   if ((holdfd[0] = open(_PATH_DEVNULL, O_RDWR)) == -1) {
 321     fprintf(stderr, "Cannot open %s !\n", _PATH_DEVNULL);
 322     return 2;
 323   }
 324   for (f = 1; f < sizeof holdfd / sizeof *holdfd; f++)
 325     holdfd[f] = dup(holdfd[0]);
 326
 327   name = strrchr(argv[0], '/');
 328   log_Open(name ? name + 1 : argv[0]);
 329
 330 #ifndef NONAT
 331   PacketAliasInit();
 332 #endif
 333   label = ProcessArgs(argc, argv, &sw);
 334
 335   /*
 336    * A FreeBSD & OpenBSD hack to dodge a bug in the tty driver that drops
 337    * output occasionally.... I must find the real reason some time.  To
 338    * display the dodgy behaviour, comment out this bit, make yourself a large
 339    * routing table and then run ppp in interactive mode.  The `show route'
 340    * command will drop chunks of data !!!
 341    */
 342   if (sw.mode == PHYS_INTERACTIVE) {
 343     close(STDIN_FILENO);
 344     if (open(_PATH_TTY, O_RDONLY) != STDIN_FILENO) {
 345       fprintf(stderr, "Cannot open %s for input !\n", _PATH_TTY);
 346       return 2;
 347     }
 348   }
 349
 350   /* Allow output for the moment (except in direct mode) */
 351   if (sw.mode == PHYS_DIRECT)
 352     prompt = NULL;
 353   else
 354     SignalPrompt = prompt = prompt_Create(NULL, NULL, PROMPT_STD);
 355
 356   ID0init();
 357   if (ID0realuid() != 0) {
 358     char conf[200], *ptr;
 359
 360     snprintf(conf, sizeof conf, "%s/%s", PPP_CONFDIR, CONFFILE);
 361     do {
 362       struct stat sb;
 363
 364       if (stat(conf, &sb) == 0 && sb.st_mode & S_IWOTH) {
 365         log_Printf(LogALERT, "ppp: Access violation: Please protect %s\n",
 366                    conf);
 367         return -1;
 368       }
 369       ptr = conf + strlen(conf)-2;
 370       while (ptr > conf && *ptr != '/')
 371         *ptr-- = '\0';
 372     } while (ptr >= conf);
 373   }
 374
 375   if (label < argc)
 376     for (arg = label; arg < argc; arg++)
 377       CheckLabel(argv[arg], prompt, sw.mode);
 378   else
 379     CheckLabel("default", prompt, sw.mode);
 380
 381   if (!sw.quiet)
 382     prompt_Printf(prompt, "Working in %s mode\n", mode2Nam(sw.mode));
 383
 384   if ((bundle = bundle_Create(TUN_PREFIX, sw.mode, sw.unit)) == NULL)
 385     return EX_START;
 386
 387   /* NOTE:  We may now have changed argv[1] via a ``set proctitle'' */
 388
 389   if (prompt) {
 390     prompt->bundle = bundle;    /* couldn't do it earlier */
 391     if (!sw.quiet)
 392       prompt_Printf(prompt, "Using interface: %s\n", bundle->iface->name);
 393   }
 394   SignalBundle = bundle;
 395   bundle->NatEnabled = sw.nat;
 396   if (sw.nat)
 397     bundle->cfg.opt |= OPT_IFACEALIAS;
 398
 399   if (system_Select(bundle, "default", CONFFILE, prompt, NULL) < 0)
 400     prompt_Printf(prompt, "Warning: No default entry found in config file.\n");
 401
 402   sig_signal(SIGHUP, CloseSession);
 403   sig_signal(SIGTERM, CloseSession);
 404   sig_signal(SIGINT, CloseConnection);
 405   sig_signal(SIGQUIT, CloseSession);
 406   sig_signal(SIGALRM, SIG_IGN);
 407   signal(SIGPIPE, SIG_IGN);
 408
 409   if (sw.mode == PHYS_INTERACTIVE)
 410     sig_signal(SIGTSTP, TerminalStop);
 411
 412   sig_signal(SIGUSR1, RestartServer);
 413   sig_signal(SIGUSR2, BringDownServer);
 414
 415   lastlabel = argv[argc - 1];
 416   for (arg = label; arg < argc; arg++) {
 417     /* In case we use LABEL or ``set enddisc label'' */
 418     bundle_SetLabel(bundle, lastlabel);
 419     system_Select(bundle, argv[arg], CONFFILE, prompt, NULL);
 420   }
 421
 422   if (label < argc)
 423     /* In case the last label did a ``load'' */
 424     bundle_SetLabel(bundle, lastlabel);
 425
 426   if (sw.mode == PHYS_AUTO &&
 427       ncprange_family(&bundle->ncp.ipcp.cfg.peer_range) == AF_UNSPEC) {
 428     prompt_Printf(prompt, "You must ``set ifaddr'' with a peer address "
 429                   "in auto mode.\n");
 430     AbortProgram(EX_START);
 431   }
 432
 433   if (sw.mode != PHYS_INTERACTIVE) {
 434     if (sw.mode != PHYS_DIRECT) {
 435       if (!sw.fg) {
 436         int bgpipe[2];
 437         pid_t bgpid;
 438
 439         if (sw.mode == PHYS_BACKGROUND && pipe(bgpipe)) {
 440           log_Printf(LogERROR, "pipe: %s\n", strerror(errno));
 441           AbortProgram(EX_SOCK);
 442         }
 443
 444         bgpid = fork();
 445         if (bgpid == -1) {
 446           log_Printf(LogERROR, "fork: %s\n", strerror(errno));
 447           AbortProgram(EX_SOCK);
 448         }
 449
 450         if (bgpid) {
 451           char c = EX_NORMAL;
 452           int ret;
 453
 454           if (sw.mode == PHYS_BACKGROUND) {
 455             close(bgpipe[1]);
 456             BGPid = bgpid;
 457             /* If we get a signal, kill the child */
 458             signal(SIGHUP, KillChild);
 459             signal(SIGTERM, KillChild);
 460             signal(SIGINT, KillChild);
 461             signal(SIGQUIT, KillChild);
 462
 463             /* Wait for our child to close its pipe before we exit */
 464             while ((ret = read(bgpipe[0], &c, 1)) == 1) {
 465               switch (c) {
 466                 case EX_NORMAL:
 467                   if (!sw.quiet) {
 468                     prompt_Printf(prompt, "PPP enabled\n");
 469                     log_Printf(LogPHASE, "Parent: PPP enabled\n");
 470                   }
 471                   break;
 472                 case EX_REDIAL:
 473                   if (!sw.quiet)
 474                     prompt_Printf(prompt, "Attempting redial\n");
 475                   continue;
 476                 case EX_RECONNECT:
 477                   if (!sw.quiet)
 478                     prompt_Printf(prompt, "Attempting reconnect\n");
 479                   continue;
 480                 default:
 481                   prompt_Printf(prompt, "Child failed (%s)\n",
 482                                 ex_desc((int)c));
 483                   log_Printf(LogPHASE, "Parent: Child failed (%s)\n",
 484                              ex_desc((int) c));
 485               }
 486               break;
 487             }
 488             if (ret != 1) {
 489               prompt_Printf(prompt, "Child exit, no status.\n");
 490               log_Printf(LogPHASE, "Parent: Child exit, no status.\n");
 491             }
 492             close(bgpipe[0]);
 493           }
 494           return c;
 495         } else if (sw.mode == PHYS_BACKGROUND) {
 496           close(bgpipe[0]);
 497           bundle->notify.fd = bgpipe[1];
 498         }
 499
 500         bundle_ChangedPID(bundle);
 501         bundle_LockTun(bundle); /* we have a new pid */
 502       }
 503
 504       /* -auto, -dedicated, -ddial, -foreground & -background */
 505       prompt_Destroy(prompt, 0);
 506       close(STDOUT_FILENO);
 507       close(STDERR_FILENO);
 508       close(STDIN_FILENO);
 509       if (!sw.fg)
 510         setsid();
 511     } else {
 512       /* -direct - STDIN_FILENO gets used by physical_Open */
 513       prompt_TtyInit(NULL);
 514       close(STDOUT_FILENO);
 515       close(STDERR_FILENO);
 516     }
 517   } else {
 518     /* -interactive */
 519     close(STDERR_FILENO);
 520     prompt_TtyInit(prompt);
 521     prompt_TtyCommandMode(prompt);
 522     prompt_Required(prompt);
 523   }
 524
 525   /* We can get rid of these now */
 526   for (f = 0; f < sizeof holdfd / sizeof *holdfd; f++)
 527     close(holdfd[f]);
 528
 529   log_Printf(LogPHASE, "PPP Started (%s mode).\n", mode2Nam(sw.mode));
 530   DoLoop(bundle);
 531   AbortProgram(EX_NORMAL);
 532
 533   return EX_NORMAL;
 534 }
 535
 536 static void
 537 DoLoop(struct bundle *bundle)
 538 {
 539   fd_set *rfds, *wfds, *efds;
 540   int i, nfds, nothing_done;
 541
 542   if ((rfds = mkfdset()) == NULL) {
 543     log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");
 544     return;
 545   }
 546
 547   if ((wfds = mkfdset()) == NULL) {
 548     log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");
 549     free(rfds);
 550     return;
 551   }
 552
 553   if ((efds = mkfdset()) == NULL) {
 554     log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");
 555     free(rfds);
 556     free(wfds);
 557     return;
 558   }
 559
 560   for (; !bundle_IsDead(bundle); bundle_CleanDatalinks(bundle)) {
 561     nfds = 0;
 562     zerofdset(rfds);
 563     zerofdset(wfds);
 564     zerofdset(efds);
 565
 566     /* All our datalinks, the tun device and the MP socket */
 567     descriptor_UpdateSet(&bundle->desc, rfds, wfds, efds, &nfds);
 568
 569     /* All our prompts and the diagnostic socket */
 570     descriptor_UpdateSet(&server.desc, rfds, NULL, NULL, &nfds);
 571
 572     bundle_CleanDatalinks(bundle);
 573     if (bundle_IsDead(bundle))
 574       /* Don't select - we'll be here forever */
 575       break;
 576
 577     /*
 578      * It's possible that we've had a signal since we last checked.  If
 579      * we don't check again before calling select(), we may end up stuck
 580      * after having missed the event.... sig_Handle() tries to be as
 581      * quick as possible if nothing is likely to have happened.
 582      * This is only really likely if we block in open(... O_NONBLOCK)
 583      * which will happen with a misconfigured device.
 584      */
 585     if (sig_Handle())
 586       continue;
 587
 588     i = select(nfds, rfds, wfds, efds, NULL);
 589
 590     if (i < 0 && errno != EINTR) {
 591       log_Printf(LogERROR, "DoLoop: select(): %s\n", strerror(errno));
 592       if (log_IsKept(LogTIMER)) {
 593         struct timeval t;
 594
 595         for (i = 0; i <= nfds; i++) {
 596           if (FD_ISSET(i, rfds)) {
 597             log_Printf(LogTIMER, "Read set contains %d\n", i);
 598             FD_CLR(i, rfds);
 599             t.tv_sec = t.tv_usec = 0;
 600             if (select(nfds, rfds, wfds, efds, &t) != -1) {
 601               log_Printf(LogTIMER, "The culprit !\n");
 602               break;
 603             }
 604           }
 605           if (FD_ISSET(i, wfds)) {
 606             log_Printf(LogTIMER, "Write set contains %d\n", i);
 607             FD_CLR(i, wfds);
 608             t.tv_sec = t.tv_usec = 0;
 609             if (select(nfds, rfds, wfds, efds, &t) != -1) {
 610               log_Printf(LogTIMER, "The culprit !\n");
 611               break;
 612             }
 613           }
 614           if (FD_ISSET(i, efds)) {
 615             log_Printf(LogTIMER, "Error set contains %d\n", i);
 616             FD_CLR(i, efds);
 617             t.tv_sec = t.tv_usec = 0;
 618             if (select(nfds, rfds, wfds, efds, &t) != -1) {
 619               log_Printf(LogTIMER, "The culprit !\n");
 620               break;
 621             }
 622           }
 623         }
 624       }
 625       break;
 626     }
 627
 628     log_Printf(LogTIMER, "Select returns %d\n", i);
 629
 630     sig_Handle();
 631
 632     if (i <= 0)
 633       continue;
 634
 635     for (i = 0; i <= nfds; i++)
 636       if (FD_ISSET(i, efds)) {
 637         log_Printf(LogPHASE, "Exception detected on descriptor %d\n", i);
 638         /* We deal gracefully with link descriptor exceptions */
 639         if (!bundle_Exception(bundle, i)) {
 640           log_Printf(LogERROR, "Exception cannot be handled !\n");
 641           break;
 642         }
 643       }
 644
 645     if (i <= nfds)
 646       break;
 647
 648     nothing_done = 1;
 649
 650     if (descriptor_IsSet(&server.desc, rfds)) {
 651       descriptor_Read(&server.desc, bundle, rfds);
 652       nothing_done = 0;
 653     }
 654
 655     if (descriptor_IsSet(&bundle->desc, rfds)) {
 656       descriptor_Read(&bundle->desc, bundle, rfds);
 657       nothing_done = 0;
 658     }
 659
 660     if (descriptor_IsSet(&bundle->desc, wfds))
 661       if (descriptor_Write(&bundle->desc, bundle, wfds) <= 0 && nothing_done) {
 662         /*
 663          * This is disastrous.  The OS has told us that something is
 664          * writable, and all our write()s have failed.  Rather than
 665          * going back immediately to do our UpdateSet()s and select(),
 666          * we sleep for a bit to avoid gobbling up all cpu time.
 667          */
 668         struct timeval t;
 669
 670         t.tv_sec = 0;
 671         t.tv_usec = 100000;
 672         select(0, NULL, NULL, NULL, &t);
 673       }
 674   }
 675
 676   log_Printf(LogDEBUG, "DoLoop done.\n");
 677 }