mdw@git.distorted.org.uk Git - userv-utils/blob - ipif/service.c

   1 /*
   2  * userv service (or standalone program)
   3  * for per-user IP subranges.
   4  *
   5  * This is invoked as root, directly from userv.
   6  * Its arguments are supposed to be, in order:
   7  *  <config>
   8  *      Specifies address ranges and gids which own them.
   9  *  --  Indicates that the remaining arguments are user-supplied
  10  *      and therefore untrusted.
  11  *  <local-addr>,<peer-addr>,<mtu>,<proto>
  12  *      As for slattach.  Supported protocols are slip, cslip, and
  13  *      adaptive.  Alternatively, set to `debug' to print debugging
  14  *      info.  <local-addr> is address of the interface on chiark;
  15  *      <peer-addr> is the address of the point-to-point peer.
  16  *  <prefix>/<mask>,<prefix>/<mask>,...
  17  *      List of additional routes to add for this interface.
  18  *      May be the empty argument.
  19  *
  20  * <config> is either
  21  *    <gid>,<prefix>/<len>[,<junk>]
  22  *      indicating that that gid may allocate addresses in
  23  *      the relevant subspace (<junk> is ignored)
  24  * or #...
  25  *      which is a comment
  26  * or /<config-file-name> or ./<config-file-name> or ../<config-file-name>
  27  *      which refers to a file which contains lines which
  28  *      are each <config>
  29  * or *
  30  *      which means that anything is permitted
  31  *
  32  * Should be run from userv with no-disconnect-hup.
  33  */
  34
  35 #include <stdio.h>
  36 #include <string.h>
  37 #include <stdlib.h>
  38 #include <assert.h>
  39 #include <errno.h>
  40 #include <stdarg.h>
  41 #include <ctype.h>
  42 #include <limits.h>
  43 #include <signal.h>
  44 #include <unistd.h>
  45
  46 #include <sys/types.h>
  47 #include <sys/wait.h>
  48 #include <sys/stat.h>
  49
  50 #define NARGS 4
  51 #define MAXEXROUTES 5
  52 #define ATXTLEN 12
  53
  54 static const unsigned long gidmaxval= (unsigned long)((gid_t)-2);
  55 static const char *const protos_ok[]= { "slip", "cslip", "adaptive", 0 };
  56 static const int signals[]= { SIGHUP, SIGINT, SIGTERM, 0 };
  57
  58 static const char *configstr, *proto;
  59 static unsigned long localaddr, peeraddr, mtu;
  60 static int localallow, peerallow, allallow;
  61 static int nexroutes;
  62 static struct exroute {
  63   unsigned long prefix, mask;
  64   int allow;
  65   char prefixtxt[ATXTLEN], masktxt[ATXTLEN];
  66 } exroutes[MAXEXROUTES];
  67
  68 static char localtxt[ATXTLEN];
  69 static char peertxt[ATXTLEN];
  70
  71 static struct pplace {
  72   struct pplace *parent;
  73   const char *filename;
  74   int lineno;
  75 } *cpplace;
  76
  77
  78 static int slpipe[2], ptmaster;
  79 static const char *ifname;
  80 static const char *ptyname;
  81
  82 #define NPIDS 4
  83
  84 static union {
  85   struct { pid_t sl, cout, cin, task; } byname;
  86   pid_t bynumber[NPIDS];
  87 } pids;
  88 sigset_t emptyset, fullset;
  89
  90
  91 static void terminate(int estatus) {
  92   int i, status;
  93   pid_t pid;
  94
  95   for (i=0; i<NPIDS; i++)
  96     if (pids.bynumber[i]) kill(pids.bynumber[i], SIGTERM);
  97
  98   for (;;) {
  99     pid= waitpid(-1,&status,0);
 100     if (pid == (pid_t)-1) break;
 101   }
 102   exit(estatus);
 103 }
 104
 105
 106 static void fatal(const char *fmt, ...)
 107      __attribute__((format(printf,1,2)));
 108 static void fatal(const char *fmt, ...) {
 109   va_list al;
 110   va_start(al,fmt);
 111
 112   fputs("userv-ipif service: fatal error: ",stderr);
 113   vfprintf(stderr, fmt, al);
 114   putc('\n',stderr);
 115   terminate(8);
 116 }
 117
 118 static void sysfatal(const char *fmt, ...)
 119      __attribute__((format(printf,1,2)));
 120 static void sysfatal(const char *fmt, ...) {
 121   va_list al;
 122   int e;
 123
 124   e= errno;
 125   va_start(al,fmt);
 126
 127   fputs("userv-ipif service: fatal system error",stderr);
 128   vfprintf(stderr, fmt, al);
 129   fprintf(stderr,"%s\n", strerror(e));
 130   terminate(12);
 131 }
 132
 133
 134 static void badusage(const char *fmt, ...)
 135      __attribute__((format(printf,1,2)));
 136 static void badusage(const char *fmt, ...) {
 137   va_list al;
 138   struct pplace *cpp;
 139
 140   if (cpplace) {
 141     fprintf(stderr,
 142             "userv-ipif service: %s:%d: ",
 143             cpplace->filename, cpplace->lineno);
 144   } else {
 145     fputs("userv-ipif service: invalid usage: ",stderr);
 146   }
 147   va_start(al,fmt);
 148   vfprintf(stderr, fmt, al);
 149   putc('\n',stderr);
 150
 151   if (cpplace) {
 152     for (cpp=cpplace->parent; cpp; cpp=cpp->parent) {
 153       fprintf(stderr,
 154               "userv-ipif service: %s:%d: ... in file included from here\n",
 155               cpp->filename, cpp->lineno);
 156     }
 157   }
 158   terminate(16);
 159 }
 160
 161 static char *ip2txt(unsigned long addr, char *buf) {
 162   sprintf(buf, "%lu.%lu.%lu.%lu",
 163           (addr>>24) & 0x0ff,
 164           (addr>>16) & 0x0ff,
 165           (addr>>8) & 0x0ff,
 166           (addr) & 0x0ff);
 167   return buf;
 168 }
 169
 170 static unsigned long eat_number(const char **argp, const char *what,
 171                                 unsigned long min, unsigned long max,
 172                                 const char *endchars, int *endchar_r) {
 173   /* If !endchars then the endchar must be a nul, otherwise it may be
 174    * a nul (resulting in *argp set to 0) or something else (*argp set
 175    * to point to after delim, *endchar_r set to delim).
 176    * *endchar_r may be 0.
 177    */
 178   unsigned long rv;
 179   char *ep;
 180   int endchar;
 181
 182   if (!*argp) { badusage("missing number %s\n",what); }
 183   rv= strtoul(*argp,&ep,0);
 184   if ((endchar= *ep)) {
 185     if (!endchars) badusage("junk after number %s\n",what);
 186     if (!strchr(endchars,endchar))
 187       badusage("invalid character or delimiter `%c' in or after number, %s:"
 188                " expected %s (or none?)\n", endchar,what,endchars);
 189     *argp= ep+1;
 190   } else {
 191     *argp= 0;
 192   }
 193   if (endchar_r) *endchar_r= endchar;
 194   if (rv < min || rv > max) badusage("number %s value %lu out of range %lu..%lu",
 195                                      what, rv, min, max);
 196   return rv;
 197 }
 198
 199 static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1,
 200                                const char *w2, unsigned long p2, unsigned long m2) {
 201   unsigned long mask;
 202
 203   mask= m1&m2;
 204   if ((p1 & mask) != (p2 & mask)) return;
 205   badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx",
 206            w1,p1,m1, w2,p2,m2);
 207 }
 208
 209 static unsigned long eat_addr(const char **argp, const char *what,
 210                               const char *endchars, int *endchar_r) {
 211   char whatbuf[100];
 212   unsigned long rv;
 213   int i;
 214
 215   for (rv=0, i=0;
 216        i<4;
 217        i++) {
 218     rv <<= 8;
 219     sprintf(whatbuf,"%s byte #%d",what,i);
 220     rv |= eat_number(argp,whatbuf, 0,255, i<3 ? "." : endchars, endchar_r);
 221   }
 222
 223   return rv;
 224 }
 225
 226 static void eat_prefixmask(const char **argp, const char *what,
 227                            const char *endchars, int *endchar_r,
 228                            unsigned long *prefix_r, unsigned long *mask_r, int *len_r) {
 229   /* mask_r and len_r may be 0 */
 230   char whatbuf[100];
 231   int len;
 232   unsigned long prefix, mask;
 233
 234   prefix= eat_addr(argp,what, "/",0);
 235   sprintf(whatbuf,"%s length",what);
 236   len= eat_number(argp,whatbuf, 0,32, endchars,endchar_r);
 237
 238   mask= (~0UL << (32-len));
 239   if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx\n",
 240                                what,prefix,mask);
 241   *prefix_r= prefix;
 242   if (mask_r) *mask_r= mask;
 243   if (len_r) *len_r= len;
 244 }
 245
 246 static int addrnet_isin(unsigned long prefix, unsigned long mask,
 247                         unsigned long mprefix, unsigned long mmask) {
 248   return  !(~mask & mmask)  &&  (prefix & mmask) == mprefix;
 249 }
 250
 251
 252 static void permit(unsigned long pprefix, unsigned long pmask) {
 253   int i, any;
 254
 255   assert(!(pprefix & ~pmask));
 256
 257   if (!proto) fputs("permits",stdout);
 258   if (addrnet_isin(localaddr,~0UL, pprefix,pmask)) {
 259     if (!proto) fputs(" local-addr",stdout);
 260     any= localallow= 1;
 261   }
 262   if (addrnet_isin(peeraddr,~0UL, pprefix,pmask)) {
 263     if (!proto) fputs(" peer-addr",stdout);
 264     any= peerallow= 1;
 265   }
 266   for (i=0; i<nexroutes; i++) {
 267     if (addrnet_isin(exroutes[i].prefix,exroutes[i].mask, pprefix,pmask)) {
 268       if (!proto) printf(" route#%d",i);
 269       any= exroutes[i].allow= 1;
 270     }
 271   }
 272   if (!proto) {
 273     if (!any) fputs(" nothing!",stderr);
 274     putchar('\n');
 275   }
 276 }
 277
 278 static void pconfig(const char *configstr, int truncated);
 279
 280 static void pfile(const char *filename) {
 281   FILE *file;
 282   char buf[PATH_MAX];
 283   int l, truncated, c;
 284   struct pplace npp, *cpp;
 285
 286   for (cpp=cpplace; cpp; cpp=cpp->parent) {
 287     if (!strcmp(cpp->filename,filename))
 288       badusage("recursive configuration file `%s'",filename);
 289   }
 290
 291   file= fopen(filename,"r");
 292   if (!file)
 293     badusage("cannot open configuration file `%s': %s", filename, strerror(errno));
 294
 295   if (!proto) printf("config file `%s':\n",filename);
 296
 297   npp.parent= cpplace;
 298   npp.filename= filename;
 299   npp.lineno= 0;
 300   cpplace= &npp;
 301
 302   while (fgets(buf, sizeof(buf), file)) {
 303     npp.lineno++;
 304     l= strlen(buf);
 305     if (!l) continue;
 306
 307     truncated= (buf[l-1] != '\n');
 308     while (l>0 && isspace((unsigned char) buf[l-1])) l--;
 309     if (!l) continue;
 310     buf[l]= 0;
 311
 312     if (truncated) {
 313       while ((c= getc(file)) != EOF && c != '\n');
 314       if (c == EOF) break;
 315     }
 316
 317     pconfig(buf,truncated);
 318   }
 319   if (ferror(file))
 320     badusage("failed while reading configuration file: %s", strerror(errno));
 321
 322   cpplace= npp.parent;
 323 }
 324
 325 static void pconfig(const char *configstr, int truncated) {
 326   unsigned long fgid, tgid, pprefix, pmask;
 327   int plen;
 328   char ptxt[ATXTLEN];
 329   const char *gidlist;
 330
 331   switch (configstr[0]) {
 332   case '*':
 333     if (strcmp(configstr,"*")) badusage("`*' directive must be only thing on line");
 334     permit(0UL,0UL);
 335     return;
 336
 337   case '#':
 338     return;
 339
 340   case '/': case '.':
 341     if (truncated) badusage("filename too long (`%.100s...')",configstr);
 342     pfile(configstr);
 343     return;
 344
 345   default:
 346     if (!isdigit((unsigned char)configstr[0]))
 347       badusage("unknown configuration directive");
 348
 349     fgid= eat_number(&configstr,"gid", 0,gidmaxval, ",",0);
 350     eat_prefixmask(&configstr,"permitted-prefix", ",",0, &pprefix,&pmask,&plen);
 351     if (!configstr && truncated) badusage("gid,prefix/len,... spec too long");
 352
 353     if (!proto) printf(" %5lu,%s/%d: ", fgid, ip2txt(pprefix,ptxt), plen);
 354
 355     gidlist= getenv("USERV_GID");
 356     if (!gidlist) fatal("USERV_GID not set");
 357     for (;;) {
 358       if (!gidlist) {
 359         if (!proto) printf("no matching gid\n");
 360         return;
 361       }
 362       tgid= eat_number(&gidlist,"userv-gid", 0,gidmaxval, " ",0);
 363       if (tgid == fgid) break;
 364     }
 365     permit(pprefix,pmask);
 366     return;
 367   }
 368 }
 369
 370 static void checkallow(int allow, const char *what,
 371                        const char *prefixtxt, const char *masktxt) {
 372   if (allow) return;
 373   fprintf(stderr,"userv-ipif service: access denied for %s, %s/%s\n",
 374           what, prefixtxt, masktxt);
 375   allallow= 0;
 376 }
 377
 378 static void parseargs(int argc, const char *const *argv) {
 379   unsigned long routeaddr, routemask;
 380   const char *carg;
 381   const char *const *cprotop;
 382   int i;
 383   char erwhatbuf[100], erwhatbuf2[100];
 384
 385   if (argc < NARGS+1) { badusage("too few arguments"); }
 386   if (argc > NARGS+1) { badusage("too many arguments"); }
 387
 388   configstr= *++argv;
 389
 390   carg= *++argv;
 391   if (strcmp(carg,"--")) badusage("separator argument `--' not found, got `%s'",carg);
 392
 393   carg= *++argv;
 394   localaddr= eat_addr(&carg,"local-addr", ",",0);
 395   peeraddr= eat_addr(&carg,"peer-addr", ",",0);
 396   mtu= eat_number(&carg,"mtu", 576,65536, ",",0);
 397   localallow= peerallow= 0;
 398
 399   if (!strcmp(carg,"debug")) {
 400     proto= 0;
 401   } else {
 402     for (cprotop= protos_ok;
 403          (proto= *cprotop) && strcmp(proto,carg);
 404          cprotop++);
 405     if (!proto) fatal("invalid protocol");
 406   }
 407
 408   addrnet_mustdiffer("local-addr",localaddr,~0UL, "peer-addr",peeraddr,~0UL);
 409
 410   carg= *++argv;
 411   for (nexroutes=0;
 412        carg;
 413        nexroutes++) {
 414     if (nexroutes == MAXEXROUTES)
 415       fatal("too many extra routes (only %d allowed)",MAXEXROUTES);
 416     sprintf(erwhatbuf,"route#%d",nexroutes);
 417
 418     eat_prefixmask(&carg,erwhatbuf, ",",0, &routeaddr,&routemask,0);
 419     if (routemask == ~0UL) {
 420       addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "local-addr",localaddr,~0UL);
 421       addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "peer-addr",peeraddr,~0UL);
 422     }
 423     for (i=0; i<nexroutes; i++) {
 424       sprintf(erwhatbuf2,"route#%d",i);
 425       addrnet_mustdiffer(erwhatbuf,routeaddr,routemask,
 426                          erwhatbuf2,exroutes[i].prefix,exroutes[i].mask);
 427     }
 428     exroutes[nexroutes].prefix= routeaddr;
 429     exroutes[nexroutes].mask= routemask;
 430     exroutes[nexroutes].allow= 0;
 431     ip2txt(routeaddr,exroutes[nexroutes].prefixtxt);
 432     ip2txt(routemask,exroutes[nexroutes].masktxt);
 433   }
 434   ip2txt(localaddr,localtxt);
 435   ip2txt(peeraddr,peertxt);
 436 }
 437
 438 static void checkpermit(void) {
 439   int i;
 440   char erwhatbuf[100];
 441
 442   allallow= 1;
 443   checkallow(localallow,"local-addr", localtxt,"32");
 444   checkallow(peerallow,"peer-addr", peertxt,"32");
 445   for (i=0; i<nexroutes; i++) {
 446     sprintf(erwhatbuf, "route#%d", i);
 447     checkallow(exroutes[i].allow, erwhatbuf, exroutes[i].prefixtxt, exroutes[i].masktxt);
 448   }
 449   if (!allallow) fatal("access denied");
 450 }
 451
 452 static void dumpdebug(void) __attribute__((noreturn));
 453 static void dumpdebug(void) {
 454   int i;
 455   char erwhatbuf[100];
 456
 457   printf("protocol: debug\n"
 458          "local:    %08lx == %s\n"
 459          "peer:     %08lx == %s\n"
 460          "mtu:      %ld\n"
 461          "routes:   %d\n",
 462          localaddr, localtxt,
 463          peeraddr, peertxt,
 464          mtu,
 465          nexroutes);
 466   for (i=0; i<nexroutes; i++) {
 467     sprintf(erwhatbuf, "route#%d:", i);
 468     printf("%-9s %08lx/%08lx == %s/%s\n",
 469            erwhatbuf,
 470            exroutes[i].prefix, exroutes[i].mask,
 471            exroutes[i].prefixtxt, exroutes[i].masktxt);
 472   }
 473   if (ferror(stdout) || fclose(stdout)) sysfatal("flush stdout");
 474   exit(0);
 475 }
 476
 477 static void setsignals(void (*handler)(int), struct sigaction *sa, int chldflags) {
 478   const int *signalp;
 479   int r, sig;
 480
 481   sa->sa_handler= handler;
 482   sa->sa_flags= 0;
 483   for (signalp=signals; (sig=*signalp); signalp++) {
 484     r= sigaction(sig, sa, 0);  if (r) sysfatal("uncatch signal");
 485   }
 486   sa->sa_flags= chldflags;
 487   r= sigaction(SIGCHLD, sa, 0);  if (r) sysfatal("uncatch children");
 488 }
 489
 490 static void setsigmask(const sigset_t *ss) {
 491   int r;
 492
 493   r= sigprocmask(SIG_SETMASK, ss, 0);
 494   if (r) sysfatal("[un]block signals");
 495 }
 496
 497 static void infork(void) {
 498   struct sigaction sa;
 499
 500   memset(&pids,0,sizeof(pids));
 501   sigemptyset(&sa.sa_mask);
 502   setsignals(SIG_DFL,&sa,0);
 503   setsigmask(&emptyset);
 504 }
 505
 506 static pid_t makesubproc(void (*entry)(void)) {
 507   pid_t pid;
 508
 509   pid= fork();  if (pid == (pid_t)-1) sysfatal("fork for subprocess");
 510   if (pid) return pid;
 511
 512   infork();
 513   entry();
 514   abort();
 515 }
 516
 517 static int task(void) {
 518   pid_t pid;
 519
 520   pid= fork();
 521   if (pids.byname.task == (pid_t)-1) sysfatal("fork for task");
 522   if (!pids.byname.task) { infork(); return 1; }
 523
 524   pids.byname.task= pid;
 525   while (pids.byname.task) sigsuspend(&emptyset);
 526   return 0;
 527 }
 528
 529 static void sl_entry(void) {
 530   if (dup2(slpipe[1],1) != 1) sysfatal("dup2 stdout in slattach child");
 531   execlp("slattach", "slattach", "-v", "-L", "-p",proto, ptyname, (char*)0);
 532   sysfatal("cannot exec slattach");
 533 }
 534
 535 static void cin_entry(void) {
 536   if (dup2(ptmaster,1) != 1) sysfatal("dup2 stdout in cat input child");
 537   execlp("cat", "cat", (char*)0);
 538   sysfatal("cannot exec cat input");
 539 }
 540
 541 static void cout_entry(void) {
 542   if (dup2(ptmaster,0) != 1) sysfatal("dup2 stdin in cat output child");
 543   execlp("cat", "cat", (char*)0);
 544   sysfatal("cannot exec cat output");
 545 }
 546
 547 static void sighandler(int signum) {
 548   pid_t pid;
 549   int estatus, status;
 550   const char *taskfail;
 551
 552   estatus= 4;
 553
 554   if (signum == SIGCHLD) {
 555     for (;;) {
 556       pid= waitpid(-1,&status,WNOHANG);
 557       if (!pid || pid == (pid_t)-1) return;
 558
 559       if (pid == pids.byname.task) {
 560         pids.byname.task= 0;
 561         if (!status) return;
 562         taskfail= "task";
 563       } else if (pid == pids.byname.cin) {
 564         pids.byname.cin= 0;
 565         if (status) {
 566           taskfail= "input cat";
 567         } else {
 568           taskfail= 0;
 569           estatus= 0;
 570         }
 571       } else if (pid == pids.byname.cout) {
 572         pids.byname.cout= 0;
 573         taskfail= "output cat";
 574       } else if (pid == pids.byname.sl) {
 575         pids.byname.sl= 0;
 576         taskfail= "slattach";
 577       } else {
 578         continue;
 579       }
 580     }
 581     if (taskfail) {
 582       fprintf(stderr,
 583               "userv-ipif service: %s unexpected terminated with status code %d\n",
 584               taskfail, status);
 585     }
 586   } else {
 587     fprintf(stderr,
 588             "userv-ipif service: received signal %d, terminating\n",
 589             signum);
 590   }
 591
 592   terminate(estatus);
 593 }
 594
 595 static void startup(void) {
 596   int r;
 597   struct sigaction sa;
 598
 599   sigfillset(&fullset);
 600   sigemptyset(&emptyset);
 601
 602   ptmaster= getpt();  if (ptmaster==-1) sysfatal("allocate pty master");
 603   r= grantpt(ptmaster);  if (r) sysfatal("grab/grant pty slave");
 604   ptyname= ptsname(ptmaster);  if (!ptyname) sysfatal("get pty slave name");
 605   r= chmod(ptyname,0600);  if (r) sysfatal("chmod pty slave");
 606
 607   sigfillset(&sa.sa_mask);
 608   setsignals(sighandler,&sa,SA_NOCLDSTOP);
 609   setsigmask(&fullset);
 610 }
 611
 612 static void startslattach(void) {
 613   FILE *piper;
 614   char ifnbuf[200];
 615   int r, l, k;
 616
 617   r= pipe(slpipe);  if (r) sysfatal("create pipe");
 618   piper= fdopen(slpipe[0],"r");  if (!piper) sysfatal("fdopen pipe");
 619
 620   pids.byname.sl= makesubproc(sl_entry);
 621
 622   close(slpipe[1]);
 623   setsigmask(&emptyset);
 624   if (!fgets(ifnbuf,sizeof(ifnbuf),piper)) {
 625     if (ferror(piper)) sysfatal("cannot read ifname from slattach");
 626     else fatal("cannot read ifname from slattach");
 627   }
 628   setsigmask(&fullset);
 629   l= strlen(ifnbuf);
 630   if (l<0 || ifnbuf[l-1] != '\n') fatal("slattach gave strange output `%s'",ifnbuf);
 631   ifnbuf[l-1]= 0;
 632   for (k=l; k>0 && ifnbuf[k-1]!=' '; k--);
 633   ifname= ifnbuf+k;
 634 }
 635
 636 static void netconfigure(void) {
 637   char mtutxt[100];
 638   int i;
 639
 640   if (task()) {
 641     sprintf(mtutxt,"%lu",mtu);
 642
 643     execlp("ifconfig", "ifconfig", ifname, localtxt,
 644            "netmask","255.255.255.255", "-broadcast", "pointopoint",peertxt,
 645            "mtu",mtutxt, "up", (char*)0);
 646     sysfatal("cannot exec ifconfig");
 647   }
 648
 649   if (task()) {
 650     execlp("route","route", "-host",localtxt, "netmask","255.255.255.255",
 651            "dev",ifname, (char*)0);
 652     sysfatal("cannot exec route (for local)");
 653   }
 654
 655   if (task()) {
 656     execlp("route","route", "-host",peertxt, "netmask","255.255.255.255",
 657            "dev",ifname, (char*)0);
 658     sysfatal("cannot exec route (for peer)");
 659   }
 660
 661   for (i=0; i<nexroutes; i++) {
 662     if (task()) {
 663       execlp("route","route", "-net",exroutes[i].prefixtxt,
 664              "netmask",exroutes[i].masktxt,
 665              "gw",peertxt, "dev",ifname, (char*)0);
 666       sysfatal("cannot exec route (for route)");
 667     }
 668   }
 669 }
 670
 671 static void copydata(void) __attribute__((noreturn));
 672 static void copydata(void) {
 673   pids.byname.cin= makesubproc(cin_entry);
 674   pids.byname.cout= makesubproc(cout_entry);
 675
 676   for (;;) sigsuspend(&emptyset);
 677 }
 678
 679 int main(int argc, const char *const *argv) {
 680   parseargs(argc,argv);
 681   pconfig(configstr,0);
 682   checkpermit();
 683   if (!proto) dumpdebug();
 684
 685   startup();
 686   startslattach();
 687   netconfigure();
 688   copydata();
 689 }