sys/src/cmd/cpu.c

   1 /*
   2  * cpu.c - Make a connection to a cpu server
   3  *
   4  *         Invoked by listen as 'cpu -R | -N service net netdir'
   5  *                 by users  as 'cpu [-h system] [-c cmd args ...]'
   6  */
   7
   8 #include <u.h>
   9 #include <libc.h>
  10 #include <auth.h>
  11 #include <fcall.h>
  12 #include <libsec.h>
  13
  14 #define Maxfdata 8192
  15 #define MaxStr 128
  16
  17 void    remoteside(int);
  18 void    fatal(char*, ...);
  19 void    lclnoteproc(int);
  20 void    rmtnoteproc(void);
  21 void    catcher(void*, char*);
  22 void    usage(void);
  23 void    writestr(int, char*, char*, int);
  24 int     readstr(int, char*, int);
  25 char    *rexcall(int*, char*, char*);
  26 int     setamalg(char*);
  27 char *keyspec = "";
  28
  29 int     notechan;
  30 int     exportpid;
  31 char    *system;
  32 int     cflag;
  33 int     nflag;
  34 int     dbg;
  35 char    *user;
  36 char    *patternfile;
  37 char    *origargs;
  38
  39 char    *srvname = "ncpu";
  40 char    *exportfs = "/bin/exportfs";
  41 char    *ealgs = "rc4_256 sha1";
  42
  43 /* message size for exportfs; may be larger so we can do big graphics in CPU window */
  44 int     msgsize = Maxfdata+IOHDRSZ;
  45
  46 /* authentication mechanisms */
  47 static int      netkeyauth(int);
  48 static int      netkeysrvauth(int, char*);
  49 static int      p9auth(int);
  50 static int      srvp9auth(int, char*);
  51 static int      noauth(int);
  52 static int      srvnoauth(int, char*);
  53
  54 typedef struct AuthMethod AuthMethod;
  55 struct AuthMethod {
  56         char    *name;                  /* name of method */
  57         int     (*cf)(int);             /* client side authentication */
  58         int     (*sf)(int, char*);      /* server side authentication */
  59 } authmethod[] =
  60 {
  61         { "p9",         p9auth,         srvp9auth,},
  62         { "netkey",     netkeyauth,     netkeysrvauth,},
  63         { "none",       noauth,         srvnoauth,},
  64         { nil,  nil}
  65 };
  66 AuthMethod *am = authmethod;    /* default is p9 */
  67
  68 char *p9authproto = "p9any";
  69
  70 int setam(char*);
  71
  72 char    *aan = "/bin/aan";
  73 char    *anstring = "tcp!*!0";
  74 char    *filterp = nil;
  75
  76 int     filter(int fd, char *host);
  77
  78 void
  79 usage(void)
  80 {
  81         fprint(2, "usage: cpu [-p] [-h system] [-u user] [-a authmethod] "
  82                 "[-e 'crypt hash'] [-k keypattern] [-P patternfile] "
  83                 "[-c cmd arg ...]\n");
  84         exits("usage");
  85 }
  86
  87 /*
  88  * reading /proc/pid/args yields either "name args" or "name [display args]",
  89  * so return only args or display args.
  90  */
  91 static char *
  92 procgetname(void)
  93 {
  94         int fd, n;
  95         char *lp, *rp;
  96         char buf[256];
  97
  98         snprint(buf, sizeof buf, "#p/%d/args", getpid());
  99         if((fd = open(buf, OREAD)) < 0)
 100                 return strdup("");
 101         *buf = '\0';
 102         n = read(fd, buf, sizeof buf-1);
 103         close(fd);
 104         if (n >= 0)
 105                 buf[n] = '\0';
 106         if ((lp = strchr(buf, '[')) == nil || (rp = strrchr(buf, ']')) == nil) {
 107                 lp = strchr(buf, ' ');
 108                 if (lp == nil)
 109                         return strdup("");
 110                 else
 111                         return strdup(lp+1);
 112         }
 113         *rp = '\0';
 114         return strdup(lp+1);
 115 }
 116
 117 /*
 118  * based on libthread's threadsetname, but drags in less library code.
 119  * actually just sets the arguments displayed.
 120  */
 121 void
 122 procsetname(char *fmt, ...)
 123 {
 124         int fd;
 125         char *cmdname;
 126         char buf[128];
 127         va_list arg;
 128
 129         va_start(arg, fmt);
 130         cmdname = vsmprint(fmt, arg);
 131         va_end(arg);
 132         if (cmdname == nil)
 133                 return;
 134         snprint(buf, sizeof buf, "#p/%d/args", getpid());
 135         if((fd = open(buf, OWRITE)) >= 0){
 136                 write(fd, cmdname, strlen(cmdname)+1);
 137                 close(fd);
 138         }
 139         free(cmdname);
 140 }
 141
 142 void
 143 main(int argc, char **argv)
 144 {
 145         char dat[MaxStr], buf[MaxStr], cmd[MaxStr], *p, *s, *err;
 146         int ac, fd, ms, data;
 147         char *av[10];
 148
 149         quotefmtinstall();
 150         origargs = procgetname();
 151         /* see if we should use a larger message size */
 152         fd = open("/dev/draw", OREAD);
 153         if(fd > 0){
 154                 ms = iounit(fd);
 155                 if(msgsize < ms+IOHDRSZ)
 156                         msgsize = ms+IOHDRSZ;
 157                 close(fd);
 158         }
 159
 160         user = getuser();
 161         if(user == nil)
 162                 fatal("can't read user name: %r");
 163         ARGBEGIN{
 164         case 'a':
 165                 p = EARGF(usage());
 166                 if(setam(p) < 0)
 167                         fatal("unknown auth method %s", p);
 168                 break;
 169         case 'e':
 170                 ealgs = EARGF(usage());
 171                 if(*ealgs == 0 || strcmp(ealgs, "clear") == 0)
 172                         ealgs = nil;
 173                 break;
 174         case 'd':
 175                 dbg++;
 176                 break;
 177         case 'f':
 178                 /* ignored but accepted for compatibility */
 179                 break;
 180         case 'n':
 181                 /* must be specified before -R/-O */
 182                 nflag++;
 183                 break;
 184         case 'A':
 185                 anstring = EARGF(usage());
 186                 break;
 187         case 'O':
 188                 p9authproto = "p9sk2";
 189                 remoteside(1);                          /* From listen */
 190                 break;
 191         case 'R':                               /* From listen */
 192                 remoteside(0);
 193                 break;
 194         case 'h':
 195                 system = EARGF(usage());
 196                 break;
 197         case 'c':
 198                 cflag++;
 199                 s = cmd;
 200                 *s++ = '!';
 201                 *s = 0;
 202                 while(p = ARGF())
 203                         s = seprint(s, cmd+sizeof(cmd), " %s", p);
 204                 break;
 205         case 'k':
 206                 keyspec = smprint("%s %s", keyspec, EARGF(usage()));
 207                 break;
 208         case 'P':
 209                 patternfile = EARGF(usage());
 210                 break;
 211         case 'u':
 212                 user = EARGF(usage());
 213                 keyspec = smprint("%s user=%s", keyspec, user);
 214                 break;
 215         case 'p':
 216                 filterp = aan;
 217                 break;
 218         default:
 219                 usage();
 220         }ARGEND;
 221
 222
 223         if(argc != 0)
 224                 usage();
 225
 226         if(system == nil) {
 227                 p = getenv("cpu");
 228                 if(p == 0)
 229                         fatal("set $cpu");
 230                 system = p;
 231         }
 232
 233         if(err = rexcall(&data, system, srvname))
 234                 fatal("%s: %s: %r", err, system);
 235
 236         procsetname("%s", origargs);
 237         /* Tell the remote side the command to execute and where our working directory is */
 238         if(cflag)
 239                 writestr(data, cmd, "command", 0);
 240         if(getwd(dat, sizeof(dat)) == 0)
 241                 writestr(data, "NO", "dir", 0);
 242         else
 243                 writestr(data, dat, "dir", 0);
 244
 245         /* start up a process to pass along notes */
 246         lclnoteproc(data);
 247
 248         /*
 249          *  Wait for the other end to execute and start our file service
 250          *  of /mnt/term
 251          */
 252         if(readstr(data, buf, sizeof(buf)) < 0)
 253                 fatal("waiting for FS: %r");
 254         if(strncmp("FS", buf, 2) != 0) {
 255                 print("remote cpu: %s", buf);
 256                 exits(buf);
 257         }
 258
 259         /* Begin serving the gnot namespace */
 260         close(0);
 261         dup(data, 0);
 262         close(data);
 263
 264         sprint(buf, "%d", msgsize);
 265         ac = 0;
 266         av[ac++] = exportfs;
 267         av[ac++] = "-m";
 268         av[ac++] = buf;
 269         if(dbg)
 270                 av[ac++] = "-d";
 271         if(patternfile != nil){
 272                 av[ac++] = "-P";
 273                 av[ac++] = patternfile;
 274         }
 275         av[ac] = nil;
 276         exec(exportfs, av);
 277         fatal("starting exportfs: %r");
 278 }
 279
 280 void
 281 fatal(char *fmt, ...)
 282 {
 283         char buf[1024];
 284         va_list arg;
 285
 286         va_start(arg, fmt);
 287         vsnprint(buf, sizeof(buf), fmt, arg);
 288         va_end(arg);
 289         fprint(2, "cpu: %s\n", buf);
 290         syslog(0, "cpu", "%s", buf);
 291         exits(buf);
 292 }
 293
 294 char *negstr = "negotiating authentication method";
 295
 296 int
 297 old9p(int fd)
 298 {
 299         int p[2];
 300
 301         if(pipe(p) < 0)
 302                 fatal("pipe: %r");
 303
 304         switch(rfork(RFPROC|RFMEM|RFFDG|RFNAMEG|RFREND)) {
 305         case -1:
 306                 fatal("rfork srvold9p: %r");
 307         case 0:
 308                 if(fd != 1){
 309                         dup(fd, 1);
 310                         close(fd);
 311                 }
 312                 if(p[0] != 0){
 313                         dup(p[0], 0);
 314                         close(p[0]);
 315                 }
 316                 close(p[1]);
 317                 if(0){
 318                         fd = open("/sys/log/cpu", OWRITE);
 319                         if(fd != 2){
 320                                 dup(fd, 2);
 321                                 close(fd);
 322                         }
 323                         execl("/bin/srvold9p", "srvold9p", "-ds", nil);
 324                 } else
 325                         execl("/bin/srvold9p", "srvold9p", "-s", nil);
 326                 fatal("exec srvold9p: %r");
 327         default:
 328                 close(fd);
 329                 close(p[0]);
 330         }
 331         return p[1];
 332 }
 333
 334 /* Invoked with stdin and stdout connected to the network connection */
 335 void
 336 remoteside(int old)
 337 {
 338         char user[MaxStr], buf[MaxStr], xdir[MaxStr], cmd[MaxStr];
 339         int i, n, fd, badchdir, gotcmd;
 340
 341         rfork(RFENVG);
 342         putenv("service", "cpu");
 343         fd = 0;
 344
 345         /* negotiate authentication mechanism */
 346         n = readstr(fd, cmd, sizeof(cmd));
 347         if(n < 0)
 348                 fatal("authenticating: %r");
 349         filterp = nil;
 350         if(!old && strcmp(cmd, "aan") == 0){
 351                 filterp = aan;
 352                 writestr(fd, "", nil, 1);
 353                 n = readstr(fd, cmd, sizeof(cmd));
 354                 if(n < 0)
 355                         fatal("authenticating: %r");
 356         }
 357         if(setamalg(cmd) < 0 || (nflag == 0 && am->sf == srvnoauth)) {
 358                 writestr(fd, "unsupported auth method", nil, 0);
 359                 fatal("bad auth method %s", cmd);
 360         } else
 361                 writestr(fd, "", "", 1);
 362
 363         fd = (*am->sf)(fd, user);
 364         if(fd < 0)
 365                 fatal("srvauth: %r");
 366
 367         /* Now collect invoking cpu's current directory or possibly a command */
 368         gotcmd = 0;
 369         if(readstr(fd, xdir, sizeof(xdir)) < 0)
 370                 fatal("dir/cmd: %r");
 371         if(xdir[0] == '!') {
 372                 strcpy(cmd, &xdir[1]);
 373                 gotcmd = 1;
 374                 if(readstr(fd, xdir, sizeof(xdir)) < 0)
 375                         fatal("dir: %r");
 376         }
 377
 378         /* Establish the new process at the current working directory of the gnot */
 379         badchdir = 0;
 380         if(strcmp(xdir, "NO") != 0)
 381                 if(chdir(xdir) < 0)
 382                         badchdir = 1;
 383
 384         /* Start the gnot serving its namespace */
 385         writestr(fd, "FS", "FS", 0);
 386         writestr(fd, "/", "exportfs dir", 0);
 387
 388         n = read(fd, buf, sizeof(buf));
 389         if(n != 2 || buf[0] != 'O' || buf[1] != 'K')
 390                 exits("remote tree");
 391
 392         if(old)
 393                 fd = old9p(fd);
 394
 395         /* make sure buffers are big by doing fversion explicitly; pick a huge number; other side will trim */
 396         strcpy(buf, VERSION9P);
 397         if(fversion(fd, 64*1024, buf, sizeof buf) < 0)
 398                 exits("fversion failed");
 399         if(mount(fd, -1, "/mnt/term", MCREATE|MREPL, "") < 0)
 400                 exits("mount failed");
 401
 402         close(fd);
 403
 404         /* the remote noteproc uses the mount so it must follow it */
 405         rmtnoteproc();
 406
 407         for(i = 0; i < 3; i++)
 408                 close(i);
 409
 410         if(open("/mnt/term/dev/cons", OREAD) != 0)
 411                 exits("open stdin");
 412         if(open("/mnt/term/dev/cons", OWRITE) != 1)
 413                 exits("open stdout");
 414         dup(1, 2);
 415
 416         if(badchdir)
 417                 print("cpu: failed to chdir to '%s'\n", xdir);
 418
 419         if(gotcmd)
 420                 execl("/bin/rc", "rc", "-lc", cmd, nil);
 421         else
 422                 execl("/bin/rc", "rc", "-li", nil);
 423         fatal("exec shell: %r");
 424 }
 425
 426 char*
 427 rexcall(int *fd, char *host, char *service)
 428 {
 429         char *na;
 430         char err[ERRMAX];
 431         char msg[MaxStr];
 432         int n;
 433
 434         na = netmkaddr(host, 0, service);
 435         procsetname("dialing %s", na);
 436         if((*fd = dial(na, 0, 0, 0)) < 0)
 437                 return "can't dial";
 438
 439         /* negotiate aan filter extension */
 440         if(filterp == aan){
 441                 writestr(*fd, "aan", "negotiating aan", 0);
 442                 n = readstr(*fd, err, sizeof err);
 443                 if(n < 0)
 444                         return "negotiating aan";
 445                 if(*err){
 446                         werrstr(err);
 447                         return negstr;
 448                 }
 449         }
 450
 451         /* negotiate authentication mechanism */
 452         if(ealgs != nil)
 453                 snprint(msg, sizeof(msg), "%s %s", am->name, ealgs);
 454         else
 455                 snprint(msg, sizeof(msg), "%s", am->name);
 456         procsetname("writing %s", msg);
 457         writestr(*fd, msg, negstr, 0);
 458         procsetname("awaiting auth method");
 459         n = readstr(*fd, err, sizeof err);
 460         if(n < 0)
 461                 return negstr;
 462         if(*err){
 463                 werrstr(err);
 464                 return negstr;
 465         }
 466
 467         /* authenticate */
 468         procsetname("%s: auth via %s", origargs, am->name);
 469         *fd = (*am->cf)(*fd);
 470         if(*fd < 0)
 471                 return "can't authenticate";
 472         return 0;
 473 }
 474
 475 void
 476 writestr(int fd, char *str, char *thing, int ignore)
 477 {
 478         int l, n;
 479
 480         l = strlen(str);
 481         n = write(fd, str, l+1);
 482         if(!ignore && n < 0)
 483                 fatal("writing network: %s: %r", thing);
 484 }
 485
 486 int
 487 readstr(int fd, char *str, int len)
 488 {
 489         int n;
 490
 491         while(len) {
 492                 n = read(fd, str, 1);
 493                 if(n < 0)
 494                         return -1;
 495                 if(*str == '\0')
 496                         return 0;
 497                 str++;
 498                 len--;
 499         }
 500         return -1;
 501 }
 502
 503 static int
 504 readln(char *buf, int n)
 505 {
 506         int i;
 507         char *p;
 508
 509         n--;    /* room for \0 */
 510         p = buf;
 511         for(i=0; i<n; i++){
 512                 if(read(0, p, 1) != 1)
 513                         break;
 514                 if(*p == '\n' || *p == '\r')
 515                         break;
 516                 p++;
 517         }
 518         *p = '\0';
 519         return p-buf;
 520 }
 521
 522 /*
 523  *  user level challenge/response
 524  */
 525 static int
 526 netkeyauth(int fd)
 527 {
 528         char chall[32];
 529         char resp[32];
 530
 531         strecpy(chall, chall+sizeof chall, getuser());
 532         print("user[%s]: ", chall);
 533         if(readln(resp, sizeof(resp)) < 0)
 534                 return -1;
 535         if(*resp != 0)
 536                 strcpy(chall, resp);
 537         writestr(fd, chall, "challenge/response", 1);
 538
 539         for(;;){
 540                 if(readstr(fd, chall, sizeof chall) < 0)
 541                         break;
 542                 if(*chall == 0)
 543                         return filter(fd, system);
 544                 print("challenge: %s\nresponse: ", chall);
 545                 if(readln(resp, sizeof(resp)) < 0)
 546                         break;
 547                 writestr(fd, resp, "challenge/response", 1);
 548         }
 549         return -1;
 550 }
 551
 552 static int
 553 netkeysrvauth(int fd, char *user)
 554 {
 555         char response[32];
 556         Chalstate *ch;
 557         int tries;
 558         AuthInfo *ai;
 559
 560         if(readstr(fd, user, MaxStr) < 0)
 561                 return -1;
 562
 563         ai = nil;
 564         ch = nil;
 565         for(tries = 0; tries < 10; tries++){
 566                 if((ch = auth_challenge("proto=p9cr role=server user=%q", user)) == nil)
 567                         return -1;
 568                 writestr(fd, ch->chal, "challenge", 1);
 569                 if(readstr(fd, response, sizeof response) < 0)
 570                         return -1;
 571                 ch->resp = response;
 572                 ch->nresp = strlen(response);
 573                 if((ai = auth_response(ch)) != nil)
 574                         break;
 575         }
 576         auth_freechal(ch);
 577         if(ai == nil)
 578                 return -1;
 579         writestr(fd, "", "challenge", 1);
 580         if(auth_chuid(ai, 0) < 0)
 581                 fatal("newns: %r");
 582         auth_freeAI(ai);
 583         return filter(fd, nil);
 584 }
 585
 586 static void
 587 mksecret(char *t, uchar *f)
 588 {
 589         sprint(t, "%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux",
 590                 f[0], f[1], f[2], f[3], f[4], f[5], f[6], f[7], f[8], f[9]);
 591 }
 592
 593 /*
 594  *  plan9 authentication followed by rc4 encryption
 595  */
 596 static int
 597 p9auth(int fd)
 598 {
 599         uchar key[16], digest[SHA1dlen];
 600         char fromclientsecret[21];
 601         char fromserversecret[21];
 602         AuthInfo *ai;
 603         int i;
 604
 605         procsetname("%s: auth_proxy proto=%q role=client %s",
 606                 origargs, p9authproto, keyspec);
 607         ai = auth_proxy(fd, auth_getkey, "proto=%q role=client %s", p9authproto, keyspec);
 608         if(ai == nil)
 609                 return -1;
 610         if(ealgs == nil){
 611                 auth_freeAI(ai);
 612                 return fd;
 613         }
 614         assert(ai->nsecret <= sizeof(key)-4);
 615         memmove(key+4, ai->secret, ai->nsecret);
 616         auth_freeAI(ai);
 617
 618         /* exchange random numbers */
 619         srand(truerand());
 620         for(i = 0; i < 4; i++)
 621                 key[i] = rand();
 622         procsetname("writing p9 key");
 623         if(write(fd, key, 4) != 4)
 624                 return -1;
 625         procsetname("reading p9 key");
 626         if(readn(fd, key+12, 4) != 4)
 627                 return -1;
 628
 629         /* scramble into two secrets */
 630         sha1(key, sizeof(key), digest, nil);
 631         mksecret(fromclientsecret, digest);
 632         mksecret(fromserversecret, digest+10);
 633
 634         if((fd = filter(fd, system)) < 0)
 635                 return -1;
 636
 637         /* set up encryption */
 638         procsetname("pushssl");
 639         fd = pushssl(fd, ealgs, fromclientsecret, fromserversecret, nil);
 640         if(fd < 0)
 641                 werrstr("can't establish ssl connection: %r");
 642         return fd;
 643 }
 644
 645 static int
 646 noauth(int fd)
 647 {
 648         ealgs = nil;
 649         return fd;
 650 }
 651
 652 static int
 653 srvnoauth(int fd, char *user)
 654 {
 655         strecpy(user, user+MaxStr, getuser());
 656         ealgs = nil;
 657         newns(user, nil);
 658         return fd;
 659 }
 660
 661 void
 662 loghex(uchar *p, int n)
 663 {
 664         char buf[100];
 665         int i;
 666
 667         for(i = 0; i < n; i++)
 668                 sprint(buf+2*i, "%2.2ux", p[i]);
 669         syslog(0, "cpu", "%s", buf);
 670 }
 671
 672 static int
 673 srvp9auth(int fd, char *user)
 674 {
 675         uchar key[16], digest[SHA1dlen];
 676         char fromclientsecret[21];
 677         char fromserversecret[21];
 678         AuthInfo *ai;
 679         int i;
 680
 681         ai = auth_proxy(fd, nil, "proto=%q role=server %s", p9authproto, keyspec);
 682         if(ai == nil)
 683                 return -1;
 684         if(auth_chuid(ai, nil) < 0)
 685                 fatal("newns: %r");
 686         snprint(user, MaxStr, "%s", ai->cuid);
 687         if(ealgs == nil){
 688                 auth_freeAI(ai);
 689                 return fd;
 690         }
 691         assert(ai->nsecret <= sizeof(key)-4);
 692         memmove(key+4, ai->secret, ai->nsecret);
 693         auth_freeAI(ai);
 694
 695         /* exchange random numbers */
 696         srand(truerand());
 697         for(i = 0; i < 4; i++)
 698                 key[i+12] = rand();
 699         if(readn(fd, key, 4) != 4)
 700                 return -1;
 701         if(write(fd, key+12, 4) != 4)
 702                 return -1;
 703
 704         /* scramble into two secrets */
 705         sha1(key, sizeof(key), digest, nil);
 706         mksecret(fromclientsecret, digest);
 707         mksecret(fromserversecret, digest+10);
 708
 709         if((fd = filter(fd, nil)) < 0)
 710                 return -1;
 711
 712         /* set up encryption */
 713         fd = pushssl(fd, ealgs, fromserversecret, fromclientsecret, nil);
 714         if(fd < 0)
 715                 werrstr("can't establish ssl connection: %r");
 716         return fd;
 717 }
 718
 719 /*
 720  *  set authentication mechanism
 721  */
 722 int
 723 setam(char *name)
 724 {
 725         for(am = authmethod; am->name != nil; am++)
 726                 if(strcmp(am->name, name) == 0)
 727                         return 0;
 728         am = authmethod;
 729         return -1;
 730 }
 731
 732 /*
 733  *  set authentication mechanism and encryption/hash algs
 734  */
 735 int
 736 setamalg(char *s)
 737 {
 738         ealgs = strchr(s, ' ');
 739         if(ealgs != nil)
 740                 *ealgs++ = 0;
 741         return setam(s);
 742 }
 743
 744 int
 745 filter(int fd, char *host)
 746 {
 747         char addr[128], buf[256], *s, *file, *argv[16];
 748         int p[2], lfd, flags, len, argc;
 749
 750         if(filterp == nil)
 751                 return fd;
 752         procsetname("filter %s", filterp);
 753         flags = RFNOWAIT|RFPROC|RFMEM|RFFDG|RFREND;
 754         if(host == nil){
 755                 /* remote side */
 756                 if(announce(anstring, addr) < 0)
 757                         fatal("filter: Cannot announce %s: %r", anstring);
 758                 snprint(buf, sizeof(buf), "%s/local", addr);
 759                 if((lfd = open(buf, OREAD)) < 0)
 760                         fatal("filter: Cannot open %s: %r", buf);
 761                 if((len = read(lfd, buf, sizeof buf - 1)) < 0)
 762                         fatal("filter: Cannot read %s: %r", buf);
 763                 close(lfd);
 764                 buf[len] = 0;
 765                 if(s = strchr(buf, '\n'))
 766                         len = s - buf;
 767                 if(write(fd, buf, len) != len)
 768                         fatal("filter: cannot write port; %r");
 769         } else {
 770                 /* client side */
 771                 flags |= RFNOTEG;
 772                 if((len = read(fd, buf, sizeof buf - 1)) < 0)
 773                         fatal("filter: cannot read port; %r");
 774                 buf[len] = '\0';
 775                 if((s = strrchr(buf, '!')) == nil)
 776                         fatal("filter: malformed remote port: %s", buf);
 777                 strecpy(addr, addr+sizeof(addr), netmkaddr(host, "tcp", s+1));
 778                 strecpy(strrchr(addr, '!'), addr+sizeof(addr), s);
 779         }
 780
 781         snprint(buf, sizeof(buf), "%s", filterp);
 782         if((argc = tokenize(buf, argv, nelem(argv)-3)) <= 0)
 783                 fatal("filter: empty command");
 784         if(host)
 785                 argv[argc++] = "-c";
 786         argv[argc++] = addr;
 787         argv[argc] = nil;
 788         file = argv[0];
 789         if(s = strrchr(argv[0], '/'))
 790                 argv[0] = s+1;
 791
 792         if(pipe(p) < 0)
 793                 fatal("filter: pipe; %r");
 794
 795         switch(rfork(flags)) {
 796         case -1:
 797                 fatal("filter: rfork; %r\n");
 798         case 0:
 799                 if (dup(p[0], 1) < 0)
 800                         fatal("filter: Cannot dup to 1; %r");
 801                 if (dup(p[0], 0) < 0)
 802                         fatal("filter: Cannot dup to 0; %r");
 803                 close(p[0]);
 804                 close(p[1]);
 805                 exec(file, argv);
 806                 fatal("filter: exec; %r");
 807         default:
 808                 close(fd);
 809                 close(p[0]);
 810         }
 811         return p[1];
 812 }
 813
 814 char *rmtnotefile = "/mnt/term/dev/cpunote";
 815
 816 /*
 817  *  loop reading /mnt/term/dev/note looking for notes.
 818  *  The child returns to start the shell.
 819  */
 820 void
 821 rmtnoteproc(void)
 822 {
 823         int n, fd, pid, notepid;
 824         char buf[256];
 825
 826         /* new proc returns to start shell */
 827         pid = rfork(RFPROC|RFFDG|RFNOTEG|RFNAMEG|RFMEM);
 828         switch(pid){
 829         case -1:
 830                 syslog(0, "cpu", "cpu -R: can't start noteproc: %r");
 831                 return;
 832         case 0:
 833                 return;
 834         }
 835
 836         /* new proc reads notes from other side and posts them to shell */
 837         switch(notepid = rfork(RFPROC|RFFDG|RFMEM)){
 838         case -1:
 839                 syslog(0, "cpu", "cpu -R: can't start wait proc: %r");
 840                 _exits(0);
 841         case 0:
 842                 fd = open(rmtnotefile, OREAD);
 843                 if(fd < 0){
 844                         syslog(0, "cpu", "cpu -R: can't open %s", rmtnotefile);
 845                         _exits(0);
 846                 }
 847
 848                 for(;;){
 849                         n = read(fd, buf, sizeof(buf)-1);
 850                         if(n <= 0){
 851                                 postnote(PNGROUP, pid, "hangup");
 852                                 _exits(0);
 853                         }
 854                         buf[n] = 0;
 855                         postnote(PNGROUP, pid, buf);
 856                 }
 857         }
 858
 859         /* original proc waits for shell proc to die and kills note proc */
 860         for(;;){
 861                 n = waitpid();
 862                 if(n < 0 || n == pid)
 863                         break;
 864         }
 865         postnote(PNPROC, notepid, "kill");
 866         _exits(0);
 867 }
 868
 869 enum
 870 {
 871         Qdir,
 872         Qcpunote,
 873
 874         Nfid = 32,
 875 };
 876
 877 struct {
 878         char    *name;
 879         Qid     qid;
 880         ulong   perm;
 881 } fstab[] =
 882 {
 883         [Qdir]          { ".",          {Qdir, 0, QTDIR},       DMDIR|0555      },
 884         [Qcpunote]      { "cpunote",    {Qcpunote, 0},          0444            },
 885 };
 886
 887 typedef struct Note Note;
 888 struct Note
 889 {
 890         Note *next;
 891         char msg[ERRMAX];
 892 };
 893
 894 typedef struct Request Request;
 895 struct Request
 896 {
 897         Request *next;
 898         Fcall f;
 899 };
 900
 901 typedef struct Fid Fid;
 902 struct Fid
 903 {
 904         int     fid;
 905         int     file;
 906         int     omode;
 907 };
 908 Fid fids[Nfid];
 909
 910 struct {
 911         Lock;
 912         Note *nfirst, *nlast;
 913         Request *rfirst, *rlast;
 914 } nfs;
 915
 916 int
 917 fsreply(int fd, Fcall *f)
 918 {
 919         uchar buf[IOHDRSZ+Maxfdata];
 920         int n;
 921
 922         if(dbg)
 923                 fprint(2, "notefs: <-%F\n", f);
 924         n = convS2M(f, buf, sizeof buf);
 925         if(n > 0){
 926                 if(write(fd, buf, n) != n){
 927                         close(fd);
 928                         return -1;
 929                 }
 930         }
 931         return 0;
 932 }
 933
 934 /* match a note read request with a note, reply to the request */
 935 int
 936 kick(int fd)
 937 {
 938         Request *rp;
 939         Note *np;
 940         int rv;
 941
 942         for(;;){
 943                 lock(&nfs);
 944                 rp = nfs.rfirst;
 945                 np = nfs.nfirst;
 946                 if(rp == nil || np == nil){
 947                         unlock(&nfs);
 948                         break;
 949                 }
 950                 nfs.rfirst = rp->next;
 951                 nfs.nfirst = np->next;
 952                 unlock(&nfs);
 953
 954                 rp->f.type = Rread;
 955                 rp->f.count = strlen(np->msg);
 956                 rp->f.data = np->msg;
 957                 rv = fsreply(fd, &rp->f);
 958                 free(rp);
 959                 free(np);
 960                 if(rv < 0)
 961                         return -1;
 962         }
 963         return 0;
 964 }
 965
 966 void
 967 flushreq(int tag)
 968 {
 969         Request **l, *rp;
 970
 971         lock(&nfs);
 972         for(l = &nfs.rfirst; *l != nil; l = &(*l)->next){
 973                 rp = *l;
 974                 if(rp->f.tag == tag){
 975                         *l = rp->next;
 976                         unlock(&nfs);
 977                         free(rp);
 978                         return;
 979                 }
 980         }
 981         unlock(&nfs);
 982 }
 983
 984 Fid*
 985 getfid(int fid)
 986 {
 987         int i, freefid;
 988
 989         freefid = -1;
 990         for(i = 0; i < Nfid; i++){
 991                 if(freefid < 0 && fids[i].file < 0)
 992                         freefid = i;
 993                 if(fids[i].fid == fid)
 994                         return &fids[i];
 995         }
 996         if(freefid >= 0){
 997                 fids[freefid].fid = fid;
 998                 return &fids[freefid];
 999         }
1000         return nil;
1001 }
1002
1003 int
1004 fsstat(int fd, Fid *fid, Fcall *f)
1005 {
1006         Dir d;
1007         uchar statbuf[256];
1008
1009         memset(&d, 0, sizeof(d));
1010         d.name = fstab[fid->file].name;
1011         d.uid = user;
1012         d.gid = user;
1013         d.muid = user;
1014         d.qid = fstab[fid->file].qid;
1015         d.mode = fstab[fid->file].perm;
1016         d.atime = d.mtime = time(0);
1017         f->stat = statbuf;
1018         f->nstat = convD2M(&d, statbuf, sizeof statbuf);
1019         return fsreply(fd, f);
1020 }
1021
1022 int
1023 fsread(int fd, Fid *fid, Fcall *f)
1024 {
1025         Dir d;
1026         uchar buf[256];
1027         Request *rp;
1028
1029         switch(fid->file){
1030         default:
1031                 return -1;
1032         case Qdir:
1033                 if(f->offset == 0 && f->count >0){
1034                         memset(&d, 0, sizeof(d));
1035                         d.name = fstab[Qcpunote].name;
1036                         d.uid = user;
1037                         d.gid = user;
1038                         d.muid = user;
1039                         d.qid = fstab[Qcpunote].qid;
1040                         d.mode = fstab[Qcpunote].perm;
1041                         d.atime = d.mtime = time(0);
1042                         f->count = convD2M(&d, buf, sizeof buf);
1043                         f->data = (char*)buf;
1044                 } else
1045                         f->count = 0;
1046                 return fsreply(fd, f);
1047         case Qcpunote:
1048                 rp = mallocz(sizeof(*rp), 1);
1049                 if(rp == nil)
1050                         return -1;
1051                 rp->f = *f;
1052                 lock(&nfs);
1053                 if(nfs.rfirst == nil)
1054                         nfs.rfirst = rp;
1055                 else
1056                         nfs.rlast->next = rp;
1057                 nfs.rlast = rp;
1058                 unlock(&nfs);
1059                 return kick(fd);;
1060         }
1061 }
1062
1063 char Eperm[] = "permission denied";
1064 char Enofile[] = "out of files";
1065 char Enotdir[] = "not a directory";
1066
1067 void
1068 notefs(int fd)
1069 {
1070         uchar buf[IOHDRSZ+Maxfdata];
1071         int i, n, ncpunote;
1072         Fcall f;
1073         Qid wqid[MAXWELEM];
1074         Fid *fid, *nfid;
1075         int doreply;
1076
1077         rfork(RFNOTEG);
1078         fmtinstall('F', fcallfmt);
1079
1080         for(n = 0; n < Nfid; n++){
1081                 fids[n].file = -1;
1082                 fids[n].omode = -1;
1083         }
1084
1085         ncpunote = 0;
1086         for(;;){
1087                 n = read9pmsg(fd, buf, sizeof(buf));
1088                 if(n < 0){
1089                         if(dbg)
1090                                 fprint(2, "read9pmsg(%d) returns %d: %r\n", fd, n);
1091                         break;
1092                 }
1093                 if(n == 0)
1094                         continue;
1095                 if(convM2S(buf, n, &f) <= BIT16SZ)
1096                         break;
1097                 if(dbg)
1098                         fprint(2, "notefs: ->%F\n", &f);
1099                 doreply = 1;
1100                 fid = getfid(f.fid);
1101                 if(fid == nil){
1102 nofids:
1103                         f.type = Rerror;
1104                         f.ename = Enofile;
1105                         fsreply(fd, &f);
1106                         continue;
1107                 }
1108                 switch(f.type++){
1109                 default:
1110                         f.type = Rerror;
1111                         f.ename = "unknown type";
1112                         break;
1113                 case Tflush:
1114                         flushreq(f.oldtag);
1115                         break;
1116                 case Tversion:
1117                         if(f.msize > IOHDRSZ+Maxfdata)
1118                                 f.msize = IOHDRSZ+Maxfdata;
1119                         break;
1120                 case Tauth:
1121                         f.type = Rerror;
1122                         f.ename = "authentication not required";
1123                         break;
1124                 case Tattach:
1125                         f.qid = fstab[Qdir].qid;
1126                         fid->file = Qdir;
1127                         break;
1128                 case Twalk:
1129                         nfid = nil;
1130                         if(f.newfid != f.fid){
1131                                 nfid = getfid(f.newfid);
1132                                 if(nfid == nil)
1133                                         goto nofids;
1134                                 nfid->file = fid->file;
1135                                 fid = nfid;
1136                         }
1137                         for(i=0; i<f.nwname && i<MAXWELEM; i++){
1138                                 if(fid->file != Qdir){
1139                                         f.type = Rerror;
1140                                         f.ename = Enotdir;
1141                                         break;
1142                                 }
1143                                 if(strcmp(f.wname[i], "..") == 0){
1144                                         wqid[i] = fstab[Qdir].qid;
1145                                         continue;
1146                                 }
1147                                 if(strcmp(f.wname[i], "cpunote") != 0){
1148                                         if(i == 0){
1149                                                 f.type = Rerror;
1150                                                 f.ename = "file does not exist";
1151                                         }
1152                                         break;
1153                                 }
1154                                 fid->file = Qcpunote;
1155                                 wqid[i] = fstab[Qcpunote].qid;
1156                         }
1157                         if(nfid != nil && (f.type == Rerror || i < f.nwname))
1158                                 nfid ->file = -1;
1159                         if(f.type != Rerror){
1160                                 f.nwqid = i;
1161                                 for(i=0; i<f.nwqid; i++)
1162                                         f.wqid[i] = wqid[i];
1163                         }
1164                         break;
1165                 case Topen:
1166                         if(f.mode != OREAD){
1167                                 f.type = Rerror;
1168                                 f.ename = Eperm;
1169                                 break;
1170                         }
1171                         fid->omode = f.mode;
1172                         if(fid->file == Qcpunote)
1173                                 ncpunote++;
1174                         f.qid = fstab[fid->file].qid;
1175                         f.iounit = 0;
1176                         break;
1177                 case Tread:
1178                         if(fsread(fd, fid, &f) < 0)
1179                                 goto err;
1180                         doreply = 0;
1181                         break;
1182                 case Tclunk:
1183                         if(fid->omode != -1 && fid->file == Qcpunote){
1184                                 ncpunote--;
1185                                 if(ncpunote == 0)       /* remote side is done */
1186                                         goto err;
1187                         }
1188                         fid->file = -1;
1189                         fid->omode = -1;
1190                         break;
1191                 case Tstat:
1192                         if(fsstat(fd, fid, &f) < 0)
1193                                 goto err;
1194                         doreply = 0;
1195                         break;
1196                 case Tcreate:
1197                 case Twrite:
1198                 case Tremove:
1199                 case Twstat:
1200                         f.type = Rerror;
1201                         f.ename = Eperm;
1202                         break;
1203                 }
1204                 if(doreply)
1205                         if(fsreply(fd, &f) < 0)
1206                                 break;
1207         }
1208 err:
1209         if(dbg)
1210                 fprint(2, "notefs exiting: %r\n");
1211         werrstr("success");
1212         postnote(PNGROUP, exportpid, "kill");
1213         if(dbg)
1214                 fprint(2, "postnote PNGROUP %d: %r\n", exportpid);
1215         close(fd);
1216 }
1217
1218 char    notebuf[ERRMAX];
1219
1220 void
1221 catcher(void*, char *text)
1222 {
1223         int n;
1224
1225         n = strlen(text);
1226         if(n >= sizeof(notebuf))
1227                 n = sizeof(notebuf)-1;
1228         memmove(notebuf, text, n);
1229         notebuf[n] = '\0';
1230         noted(NCONT);
1231 }
1232
1233 /*
1234  *  mount in /dev a note file for the remote side to read.
1235  */
1236 void
1237 lclnoteproc(int netfd)
1238 {
1239         Waitmsg *w;
1240         Note *np;
1241         int pfd[2];
1242         int pid;
1243
1244         if(pipe(pfd) < 0){
1245                 fprint(2, "cpu: can't start note proc: pipe: %r\n");
1246                 return;
1247         }
1248
1249         /* new proc mounts and returns to start exportfs */
1250         switch(pid = rfork(RFPROC|RFNAMEG|RFFDG|RFMEM)){
1251         default:
1252                 exportpid = pid;
1253                 break;
1254         case -1:
1255                 fprint(2, "cpu: can't start note proc: rfork: %r\n");
1256                 return;
1257         case 0:
1258                 close(pfd[0]);
1259                 if(mount(pfd[1], -1, "/dev", MBEFORE, "") < 0)
1260                         fprint(2, "cpu: can't mount note proc: %r\n");
1261                 close(pfd[1]);
1262                 return;
1263         }
1264
1265         close(netfd);
1266         close(pfd[1]);
1267
1268         /* new proc listens for note file system rpc's */
1269         switch(rfork(RFPROC|RFNAMEG|RFMEM)){
1270         case -1:
1271                 fprint(2, "cpu: can't start note proc: rfork1: %r\n");
1272                 _exits(0);
1273         case 0:
1274                 notefs(pfd[0]);
1275                 _exits(0);
1276         }
1277
1278         /* original proc waits for notes */
1279         notify(catcher);
1280         w = nil;
1281         for(;;) {
1282                 *notebuf = 0;
1283                 free(w);
1284                 w = wait();
1285                 if(w == nil) {
1286                         if(*notebuf == 0)
1287                                 break;
1288                         np = mallocz(sizeof(Note), 1);
1289                         if(np != nil){
1290                                 strcpy(np->msg, notebuf);
1291                                 lock(&nfs);
1292                                 if(nfs.nfirst == nil)
1293                                         nfs.nfirst = np;
1294                                 else
1295                                         nfs.nlast->next = np;
1296                                 nfs.nlast = np;
1297                                 unlock(&nfs);
1298                                 kick(pfd[0]);
1299                         }
1300                         unlock(&nfs);
1301                 } else if(w->pid == exportpid)
1302                         break;
1303         }
1304
1305         if(w == nil)
1306                 exits(nil);
1307         exits(0);
1308 /*      exits(w->msg); */
1309 }