mdw@git.distorted.org.uk Git - tripe/blob - proxy/tripe-mitm.c

   1 /* -*-c-*-
   2  *
   3  * An evil proxy for TrIPE
   4  *
   5  * (c) 2001 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software: you can redistribute it and/or modify it under
  13  * the terms of the GNU General Public License as published by the Free
  14  * Software Foundation; either version 3 of the License, or (at your
  15  * option) any later version.
  16  *
  17  * TrIPE is distributed in the hope that it will be useful, but WITHOUT
  18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  20  * for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE.  If not, see <https://www.gnu.org/licenses/>.
  24  */
  25
  26 /*----- Header files ------------------------------------------------------*/
  27
  28 #include "config.h"
  29
  30 #include <assert.h>
  31 #include <errno.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <time.h>
  36
  37 #include <sys/types.h>
  38 #include <sys/time.h>
  39 #include <unistd.h>
  40 #include <fcntl.h>
  41
  42 #include <sys/socket.h>
  43 #include <netinet/in.h>
  44 #include <arpa/inet.h>
  45 #include <netdb.h>
  46
  47 #include <mLib/alloc.h>
  48 #include <mLib/dstr.h>
  49 #include <mLib/fdflags.h>
  50 #include <mLib/mdwopt.h>
  51 #include <mLib/quis.h>
  52 #include <mLib/report.h>
  53 #include <mLib/sel.h>
  54 #include <mLib/sub.h>
  55 #include <mLib/tv.h>
  56
  57 #include <catacomb/buf.h>
  58
  59 #include <catacomb/key.h>
  60
  61 #include <catacomb/mp.h>
  62 #include <catacomb/mprand.h>
  63 #include <catacomb/dh.h>
  64
  65 #include <catacomb/noise.h>
  66 #include <catacomb/rand.h>
  67 #include <catacomb/rc4.h>
  68
  69 #include "util.h"
  70
  71 /*----- Data structures ---------------------------------------------------*/
  72
  73 typedef struct peer {
  74   sel_file sf;
  75   dh_pub kpub;
  76   const char *name;
  77   struct filter *f;
  78 } peer;
  79
  80 typedef struct filter {
  81   struct filter *next;
  82   peer *p_from, *p_to;
  83   void (*func)(struct filter */*f*/, const octet */*buf*/, size_t /*sz*/);
  84   void *state;
  85 } filter;
  86
  87 typedef struct qnode {
  88   octet *buf;
  89   size_t sz;
  90 } qnode;
  91
  92 /*----- Static variables --------------------------------------------------*/
  93
  94 #define PKBUFSZ 65536
  95
  96 static sel_state sel;
  97 static peer peers[2];
  98 static unsigned npeer = 0;
  99 static key_file keys;
 100 static grand *rng;
 101
 102 #define PASS(f, buf, sz) ((f) ? (f)->func((f), (buf), (sz)) : (void)0)
 103 #define RND(i) (rng->ops->range(rng, (i)))
 104
 105 /*----- Peer management ---------------------------------------------------*/
 106
 107 static void dopacket(int fd, unsigned mode, void *vv)
 108 {
 109   octet buf[PKBUFSZ];
 110   peer *p = vv;
 111   int r = read(fd, buf, sizeof(buf));
 112   if (r >= 0) {
 113     printf("recv from `%s'\n", p->name);
 114     PASS(p->f, buf, r);
 115   }
 116 }
 117
 118 static void addpeer(unsigned ac, char **av)
 119 {
 120   key_packstruct kps[DH_PUBFETCHSZ];
 121   key_packdef *kp;
 122   struct hostent *h;
 123   struct sockaddr_in sin;
 124   int len = PKBUFSZ;
 125   peer *p;
 126   int fd;
 127   int e;
 128
 129   if (ac != 4)
 130     die(1, "syntax: peer:NAME:PORT:ADDR:PORT");
 131   if (npeer >= 2)
 132     die(1, "enough peers already");
 133   p = &peers[npeer++];
 134   p->name = xstrdup(av[0]);
 135   kp = key_fetchinit(dh_pubfetch, kps, &p->kpub);
 136   e = key_fetchbyname(kp, &keys, av[0]);
 137   key_fetchdone(kp);
 138   if (e)
 139     die(1, "key_fetch `%s': %s", av[0], key_strerror(e));
 140   if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
 141     die(1, "socket: %s", strerror(errno));
 142   fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
 143   memset(&sin, 0, sizeof(sin));
 144   sin.sin_family = AF_INET;
 145   sin.sin_addr.s_addr = INADDR_ANY;
 146   sin.sin_port = htons(atoi(av[1]));
 147   if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
 148     die(1, "bind: %s", strerror(errno));
 149   memset(&sin, 0, sizeof(sin));
 150   sin.sin_family = AF_INET;
 151   if ((h = gethostbyname(av[2])) == 0)
 152     die(1, "gethostbyname `%s'", av[2]);
 153   if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 154       setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)))
 155     die(1, "setsockopt: %s", strerror(errno));
 156   memcpy(&sin.sin_addr, h->h_addr, sizeof(sin.sin_addr));
 157   sin.sin_port = htons(atoi(av[3]));
 158   if (connect(fd, (struct sockaddr *)&sin, sizeof(sin)))
 159     die(1, "connect: %s", strerror(errno));
 160   sel_initfile(&sel, &p->sf, fd, SEL_READ, dopacket, p);
 161   sel_addfile(&p->sf);
 162 }
 163
 164 /*----- Fork filter -------------------------------------------------------*/
 165
 166 typedef struct forknode {
 167   struct forknode *next;
 168   filter *f;
 169 } forknode;
 170
 171 typedef struct forkfilt {
 172   const char *name;
 173   forknode *fn;
 174 } forkfilt;
 175
 176 static void dofork(filter *f, const octet *buf, size_t sz)
 177 {
 178   forkfilt *ff = f->state;
 179   forknode *fn;
 180   unsigned i = 0;
 181
 182   ff = f->state;
 183   for (fn = ff->fn; fn; fn = fn->next) {
 184     printf("fork branch %u of fork `%s'\n", i++, ff->name);
 185     PASS(fn->f, buf, sz);
 186   }
 187   printf("fork branch %u of fork `%s'\n", i++, ff->name);
 188   PASS(f->next, buf, sz);
 189 }
 190
 191 static void addfork(filter *f, unsigned ac, char **av)
 192 {
 193   forkfilt *ff;
 194   if (ac != 1)
 195     die(1, "syntax: filt:fork:NAME");
 196   ff = CREATE(forkfilt);
 197   ff->name = xstrdup(av[0]);
 198   ff->fn = 0;
 199   f->func = dofork;
 200   f->state = ff;
 201 }
 202
 203 static void nextfork(unsigned ac, char **av)
 204 {
 205   unsigned i, j;
 206   filter *f;
 207   forkfilt *ff;
 208   forknode *fn, **ffn;
 209   peer *p;
 210
 211   if (ac < 1)
 212     die(1, "syntax: next:NAME:...");
 213   for (i = 0; i < 2; i++) {
 214     p = &peers[i];
 215     for (f = p->f; f; f = f->next) {
 216       if (f->func != dofork)
 217         continue;
 218       ff = f->state;
 219       for (j = 0; j < ac; j++) {
 220         if (strcmp(av[j], ff->name) == 0)
 221           goto match;
 222       }
 223       continue;
 224     match:
 225       fn = CREATE(forknode);
 226       for (ffn = &ff->fn; *ffn; ffn = &(*ffn)->next)
 227         ;
 228       fn->f = f->next;
 229       f->next = 0;
 230       fn->next = 0;
 231       *ffn = fn;
 232     }
 233   }
 234 }
 235
 236 /*----- Corrupt filter ----------------------------------------------------*/
 237
 238 typedef struct corrupt {
 239   unsigned p_corrupt;
 240 } corrupt;
 241
 242 static void docorrupt(filter *f, const octet *buf, size_t sz)
 243 {
 244   corrupt *c = f->state;
 245   octet b[PKBUFSZ];
 246   memcpy(b, buf, sz);
 247
 248   while (!RND(c->p_corrupt)) {
 249     puts("corrupt packet");
 250     b[RND(sz)] ^= RND(256);
 251   }
 252   PASS(f->next, b, sz);
 253 }
 254
 255 static void addcorrupt(filter *f, unsigned ac, char **av)
 256 {
 257   corrupt *c;
 258   if (ac > 1)
 259     die(1, "syntax: filt:corrupt[:P-CORRUPT]");
 260   c = CREATE(corrupt);
 261   if (ac > 0)
 262     c->p_corrupt = atoi(av[0]);
 263   else
 264     c->p_corrupt = 5;
 265   f->state = c;
 266   f->func = docorrupt;
 267 }
 268
 269 /*----- Drop filter -------------------------------------------------------*/
 270
 271 typedef struct drop {
 272   unsigned p_drop;
 273 } drop;
 274
 275 static void dodrop(filter *f, const octet *buf, size_t sz)
 276 {
 277   drop *d = f->state;
 278
 279   if (!RND(d->p_drop))
 280     puts("drop packet");
 281   else
 282     PASS(f->next, buf, sz);
 283 }
 284
 285 static void adddrop(filter *f, unsigned ac, char **av)
 286 {
 287   drop *d;
 288   if (ac > 1)
 289     die(1, "syntax: filt:drop[:P-DROP]");
 290   d = CREATE(drop);
 291   if (ac > 0)
 292     d->p_drop = atoi(av[0]);
 293   else
 294     d->p_drop = 5;
 295   f->state = d;
 296   f->func = dodrop;
 297 }
 298
 299 /*----- Delay filter ------------------------------------------------------*/
 300
 301 typedef struct delaynode {
 302   unsigned flag;
 303   sel_timer tm;
 304   unsigned i;
 305   struct delay *d;
 306   octet *buf;
 307   size_t sz;
 308   unsigned seq;
 309 } delaynode;
 310
 311 typedef struct delay {
 312   unsigned max, n;
 313   unsigned long t;
 314   unsigned p_replay;
 315   filter *f;
 316   delaynode *q;
 317 } delay;
 318
 319 static void dtimer(struct timeval *tv, void *vv);
 320
 321 static void dinsert(delaynode *dn)
 322 {
 323   struct timeval tv;
 324   sel_timer *ta, *tb;
 325   unsigned long tdelta = RND(dn->d->t);
 326   gettimeofday(&tv, 0);
 327   TV_ADDL(&tv, &tv, 0, tdelta);
 328   assert(!dn->flag);
 329   sel_addtimer(&sel, &dn->tm, &tv, dtimer, dn);
 330   dn->flag = 1;
 331   for (ta = tb = sel.timers; ta; ta = ta->next) {
 332     ta = ta->next; if (!ta) break; assert(ta != tb);
 333     ta = ta->next; if (!ta) break; assert(ta != tb);
 334     tb = tb->next;
 335   }
 336   printf(" delay %lu usecs", tdelta);
 337 }
 338
 339 static void dsend(delaynode *dn, unsigned force)
 340 {
 341   delay *d = dn->d;
 342   delaynode *ddn;
 343   fputs(" send...\n", stdout);
 344   assert(dn->buf);
 345   PASS(d->f->next, dn->buf, dn->sz);
 346   fputs("delay ...", stdout);
 347   if (!force)
 348     dinsert(dn);
 349   else {
 350     xfree(dn->buf);
 351     dn->buf = 0;
 352     d->n--;
 353     if (dn->i < d->n) {
 354       ddn = &d->q[d->n];
 355       sel_rmtimer(&ddn->tm);
 356       sel_addtimer(&sel, &dn->tm, &ddn->tm.tv, dtimer, dn);
 357       dn->flag = 1;
 358       dn->buf = ddn->buf;
 359       dn->sz = ddn->sz;
 360       dn->seq = ddn->seq;
 361       ddn->buf = 0;
 362       ddn->flag = 0;
 363       printf(" move id %u from slot %u to slot %u", ddn->seq, ddn->i, dn->i);
 364     }
 365     { unsigned i; for (i = 0; i < d->n; i++) assert(d->q[i].buf); }
 366     fputs(" remove", stdout);
 367   }
 368 }
 369
 370 static void dtimer(struct timeval *tv, void *vv)
 371 {
 372   delaynode *dn = vv;
 373   printf("delay timer peer `%s' id %u slot %u",
 374          dn->d->f->p_from->name, dn->seq, dn->i);
 375   dn->flag = 0;
 376   dsend(dn, RND(dn->d->p_replay));
 377   fputc('\n', stdout);
 378 }
 379
 380 static void dodelay(filter *f, const octet *buf, size_t sz)
 381 {
 382   delay *d = f->state;
 383   delaynode *dn;
 384   static unsigned seq = 0;
 385
 386   fputs("delay", stdout);
 387   if (d->n == d->max) {
 388     dn = &d->q[RND(d->n)];
 389     printf(" force uid %u", dn->seq);
 390     sel_rmtimer(&dn->tm);
 391     dn->flag = 0;
 392     dsend(dn, 1);
 393     fputc(';', stdout);
 394   }
 395   dn = &d->q[d->n++];
 396   dn->seq = seq++;
 397   printf(" new id %u in slot %u", dn->seq, dn->i);
 398   dn->buf = xmalloc(sz);
 399   dn->sz = sz;
 400   memcpy(dn->buf, buf, sz);
 401   dinsert(dn);
 402   fputc('\n', stdout);
 403 }
 404
 405 static void adddelay(filter *f, unsigned ac, char **av)
 406 {
 407   delay *d;
 408   unsigned i;
 409
 410   if (ac < 1 || ac > 3)
 411     die(1, "syntax: filt:delay:QLEN[:MILLIS:P-REPLAY]");
 412   d = CREATE(delay);
 413   d->max = atoi(av[0]);
 414   if (ac > 1)
 415     d->t = strtoul(av[1], 0, 10);
 416   else
 417     d->t = 100;
 418   d->t *= 1000;
 419   if (ac > 2)
 420     d->p_replay = atoi(av[2]);
 421   else
 422     d->p_replay = 20;
 423   d->n = 0;
 424   d->q = xmalloc(d->max * sizeof(delaynode));
 425   d->f = f;
 426   f->state = d;
 427   f->func = dodelay;
 428   for (i = 0; i < d->max; i++) {
 429     d->q[i].d = d;
 430     d->q[i].i = i;
 431     d->q[i].buf = 0;
 432     d->q[i].flag = 0;
 433   }
 434 }
 435
 436 /*----- Filters -----------------------------------------------------------*/
 437
 438 static void dosend(filter *f, const octet *buf, size_t sz)
 439 {
 440   printf("send to `%s'\n", f->p_to->name);
 441   DISCARD(write(f->p_to->sf.fd, buf, sz));
 442 }
 443
 444 static void addsend(filter *f, unsigned ac, char **av)
 445 {
 446   if (ac)
 447     die(1, "syntax: filt:send");
 448   f->func = dosend;
 449 }
 450
 451 const struct filtab {
 452   const char *name;
 453   void (*func)(filter */*f*/, unsigned /*ac*/, char **/*av*/);
 454 } filtab[] = {
 455   { "send",     addsend },
 456   { "fork",     addfork },
 457   { "delay",    adddelay },
 458   { "drop",     adddrop },
 459   { "corrupt",  addcorrupt },
 460   { 0,          0 }
 461 };
 462
 463 static void dofilter(peer *from, peer *to, unsigned ac, char **av)
 464 {
 465   filter **ff, *f = CREATE(filter);
 466   const struct filtab *ft;
 467   if (ac < 1)
 468     die(1, "syntax: {l,r,}filt:NAME:...");
 469   f->next = 0;
 470   f->p_from = from;
 471   f->p_to = to;
 472   f->state = 0;
 473   for (ff = &from->f; *ff; ff = &(*ff)->next)
 474     ;
 475   *ff = f;
 476   for (ft = filtab; ft->name; ft++) {
 477     if (strcmp(av[0], ft->name) == 0) {
 478       ft->func(f, ac - 1, av + 1);
 479       return;
 480     }
 481   }
 482   die(1, "unknown filter `%s'", av[0]);
 483 }
 484
 485 /*----- Flooding ----------------------------------------------------------*/
 486
 487 typedef struct flood {
 488   peer *p;
 489   unsigned type;
 490   size_t sz;
 491   unsigned long t;
 492   sel_timer tm;
 493 } flood;
 494
 495 static void setflood(flood *f);
 496
 497 static void floodtimer(struct timeval *tv, void *vv)
 498 {
 499   flood *f = vv;
 500   octet buf[PKBUFSZ];
 501   size_t sz;
 502
 503   sz = RND(f->sz);
 504   sz += RND(f->sz);
 505   sz += RND(f->sz);
 506   sz += RND(f->sz);
 507   sz /= 2;
 508
 509   rng->ops->fill(rng, buf, sz);
 510   if (f->type < 0x100)
 511     buf[0] = f->type;
 512   puts("flood packet");
 513   PASS(f->p->f, buf, sz);
 514   setflood(f);
 515 }
 516
 517 static void setflood(flood *f)
 518 {
 519   struct timeval tv;
 520   gettimeofday(&tv, 0);
 521   TV_ADDL(&tv, &tv, 0, RND(f->t));
 522   sel_addtimer(&sel, &f->tm, &tv, floodtimer, f);
 523 }
 524
 525 static void doflood(peer *p, unsigned ac, char **av)
 526 {
 527   flood *f;
 528   if (ac > 3)
 529     die(1, "syntax: flood[:TYPE:MILLIS:SIZE]");
 530   f = CREATE(flood);
 531   f->p = p;
 532   if (ac > 0)
 533     f->type = strtoul(av[0], 0, 16);
 534   else
 535     f->type = 0x100;
 536   if (ac > 1)
 537     f->t = atoi(av[1]);
 538   else
 539     f->t = 10;
 540   if (ac > 2)
 541     f->sz = atoi(av[2]);
 542   else
 543     f->sz = 128;
 544   f->t *= 1000;
 545   setflood(f);
 546 }
 547
 548 /*----- Configuration commands --------------------------------------------*/
 549
 550 static void parse(char *p);
 551
 552 static void addflood(unsigned ac, char **av) {
 553   doflood(&peers[0], ac, av);
 554   doflood(&peers[1], ac, av);
 555 }
 556 static void addlflood(unsigned ac, char **av) {
 557   doflood(&peers[0], ac, av);
 558 }
 559 static void addrflood(unsigned ac, char **av) {
 560   doflood(&peers[1], ac, av);
 561 }
 562
 563 static void addfilter(unsigned ac, char **av) {
 564   dofilter(&peers[0], &peers[1], ac, av);
 565   dofilter(&peers[1], &peers[0], ac, av);
 566 }
 567 static void addlfilter(unsigned ac, char **av) {
 568   dofilter(&peers[0], &peers[1], ac, av);
 569 }
 570 static void addrfilter(unsigned ac, char **av) {
 571   dofilter(&peers[1], &peers[0], ac, av);
 572 }
 573
 574 static void include(unsigned ac, char **av)
 575 {
 576   FILE *fp;
 577   dstr d = DSTR_INIT;
 578   if (!ac)
 579     die(1, "syntax: include:FILE:...");
 580   while (*av) {
 581     if ((fp = fopen(*av, "r")) == 0)
 582       die(1, "fopen `%s': %s", *av, strerror(errno));
 583     while (dstr_putline(&d, fp) != EOF) {
 584       parse(d.buf);
 585       DRESET(&d);
 586     }
 587     fclose(fp);
 588     av++;
 589   }
 590 }
 591
 592 const struct cmdtab {
 593   const char *name;
 594   void (*func)(unsigned /*ac*/, char **/*av*/);
 595 } cmdtab[] = {
 596   { "peer",     addpeer },
 597   { "include",  include },
 598   { "filt",     addfilter },
 599   { "lfilt",    addlfilter },
 600   { "rfilt",    addrfilter },
 601   { "next",     nextfork },
 602   { "flood",    addflood },
 603   { "lflood",   addlflood },
 604   { "rflood",   addrflood },
 605   { 0,          0 }
 606 };
 607
 608 #define AVMAX 16
 609
 610 static void parse(char *p)
 611 {
 612   char *v[AVMAX];
 613   unsigned c = 0;
 614   const struct cmdtab *ct;
 615
 616   p = strtok(p, ":");
 617   if (!p || *p == '#')
 618     return;
 619   do {
 620     v[c++] = p;
 621     p = strtok(0, ":");
 622   } while (p && c < AVMAX - 1);
 623   v[c] = 0;
 624   for (ct = cmdtab; ct->name; ct++) {
 625     if (strcmp(ct->name, v[0]) == 0) {
 626       ct->func(c - 1, v + 1);
 627       return;
 628     }
 629   }
 630   die(1, "unknown command `%s'", v[0]);
 631 }
 632
 633 /*----- Main driver -------------------------------------------------------*/
 634
 635 static void version(FILE *fp)
 636   { pquis(fp, "$, TrIPE version " VERSION "\n"); }
 637
 638 static void usage(FILE *fp)
 639   { pquis(fp, "Usage: $ [-k KEYRING] DIRECTIVE...\n"); }
 640
 641 static void help(FILE *fp)
 642 {
 643   version(fp);
 644   putc('\n', fp);
 645   usage(fp);
 646   fputs("\n\
 647 Options:\n\
 648 \n\
 649 -h, --help              Show this help text.\n\
 650 -v, --version           Show the version number.\n\
 651 -u, --usage             Show terse usage summary.\n\
 652 \n\
 653 -k, --keyring=FILE      Fetch keys from FILE.\n\
 654 \n\
 655 Directives:\n\
 656   peer:NAME:LOCAL-PORT:REMOTE-ADDR:REMOTE-PORT\n\
 657   include:FILE\n\
 658   {,l,r}filt:FILTER:ARGS:...\n\
 659   next:TAG\n\
 660   {,l,r}flood:TYPE:MILLIS:SIZE\n\
 661 \n\
 662 Filters:\n\
 663   send\n\
 664   fork:TAG\n\
 665   delay:QLEN[:MILLIS:P-REPLAY]\n\
 666   drop[:P-DROP]\n\
 667   corrupt[:P-CORRUPT]\n",
 668         fp);
 669 }
 670
 671 int main(int argc, char *argv[])
 672 {
 673   const char *kfname = "keyring.pub";
 674   int i;
 675   unsigned f = 0;
 676   char buf[16];
 677
 678 #define f_bogus 1u
 679
 680   ego(argv[0]);
 681   for (;;) {
 682     static const struct option opt[] = {
 683       { "help",         0,              0,      'h' },
 684       { "version",      0,              0,      'v' },
 685       { "usage",        0,              0,      'u' },
 686       { "keyring",      OPTF_ARGREQ,    0,      'k' },
 687       { 0,              0,              0,      0 }
 688     };
 689     if ((i = mdwopt(argc, argv, "hvuk:", opt, 0, 0, 0)) < 0)
 690       break;
 691     switch (i) {
 692       case 'h':
 693         help(stdout);
 694         exit(0);
 695       case 'v':
 696         version(stdout);
 697         exit(0);
 698       case 'u':
 699         usage(stdout);
 700         exit(0);
 701       case 'k':
 702         kfname = optarg;
 703         break;
 704       default:
 705         f |= f_bogus;
 706         break;
 707     }
 708   }
 709   if (f & f_bogus) {
 710     usage(stderr);
 711     exit(1);
 712   }
 713   rand_noisesrc(RAND_GLOBAL, &noise_source);
 714   rand_seed(RAND_GLOBAL, 160);
 715   rand_get(RAND_GLOBAL, buf, sizeof(buf));
 716   rng = rc4_rand(buf, sizeof(buf));
 717   sel_init(&sel);
 718   if (key_open(&keys, kfname, KOPEN_READ, key_moan, 0))
 719     die(1, "couldn't open `%s': %s", kfname, strerror(errno));
 720   for (i = optind; i < argc; i++)
 721     parse(argv[i]);
 722   if (npeer != 2)
 723     die(1, "need two peers");
 724   for (;;)
 725     sel_select(&sel);
 726
 727 #undef f_bogus
 728 }
 729
 730 /*----- That's all, folks -------------------------------------------------*/