usr.sbin/inetd/builtins.c

   1 /*-
   2  * Copyright (c) 1983, 1991, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/usr.sbin/inetd/builtins.c,v 1.19.2.7 2002/07/22 14:05:56 fanf Exp $
  27  *
  28  */
  29
  30 #include <sys/filio.h>
  31 #include <sys/param.h>
  32 #include <sys/stat.h>
  33 #include <sys/socket.h>
  34 #include <sys/sysctl.h>
  35 #include <sys/ucred.h>
  36 #include <sys/uio.h>
  37 #include <sys/utsname.h>
  38
  39 #include <ctype.h>
  40 #include <err.h>
  41 #include <errno.h>
  42 #include <fcntl.h>
  43 #include <limits.h>
  44 #include <pwd.h>
  45 #include <signal.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <sysexits.h>
  49 #include <syslog.h>
  50 #include <unistd.h>
  51
  52 #include "inetd.h"
  53
  54 void            chargen_dg(int, struct servtab *);
  55 void            chargen_stream(int, struct servtab *) __dead2;
  56 void            daytime_dg(int, struct servtab *);
  57 void            daytime_stream(int, struct servtab *);
  58 void            discard_dg(int, struct servtab *);
  59 void            discard_stream(int, struct servtab *) __dead2;
  60 void            echo_dg(int, struct servtab *);
  61 void            echo_stream(int, struct servtab *) __dead2;
  62 static int      get_line(int, char *, int);
  63 void            iderror(int, int, int, const char *) __dead2;
  64 void            ident_stream(int, struct servtab *) __dead2;
  65 void            initring(void);
  66 unsigned long   machtime(void);
  67 void            machtime_dg(int, struct servtab *);
  68 void            machtime_stream(int, struct servtab *);
  69
  70 char ring[128];
  71 char *endring;
  72
  73
  74 struct biltin biltins[] = {
  75         /* Echo received data */
  76         { "echo",       SOCK_STREAM,    1, -1,  echo_stream },
  77         { "echo",       SOCK_DGRAM,     0, 1,   echo_dg },
  78
  79         /* Internet /dev/null */
  80         { "discard",    SOCK_STREAM,    1, -1,  discard_stream },
  81         { "discard",    SOCK_DGRAM,     0, 1,   discard_dg },
  82
  83         /* Return 32 bit time since 1900 */
  84         { "time",       SOCK_STREAM,    0, -1,  machtime_stream },
  85         { "time",       SOCK_DGRAM,     0, 1,   machtime_dg },
  86
  87         /* Return human-readable time */
  88         { "daytime",    SOCK_STREAM,    0, -1,  daytime_stream },
  89         { "daytime",    SOCK_DGRAM,     0, 1,   daytime_dg },
  90
  91         /* Familiar character generator */
  92         { "chargen",    SOCK_STREAM,    1, -1,  chargen_stream },
  93         { "chargen",    SOCK_DGRAM,     0, 1,   chargen_dg },
  94
  95         { "tcpmux",     SOCK_STREAM,    1, -1,  (bi_fn_t *)tcpmux },
  96
  97         { "auth",       SOCK_STREAM,    1, -1,  ident_stream },
  98
  99         { NULL,         0,              0, 0,   NULL }
 100 };
 101
 102 /*
 103  * RFC864 Character Generator Protocol. Generates character data without
 104  * any regard for input.
 105  */
 106
 107 void
 108 initring(void)
 109 {
 110         int i;
 111
 112         endring = ring;
 113
 114         for (i = 0; i <= 128; ++i)
 115                 if (isprint(i))
 116                         *endring++ = i;
 117 }
 118
 119 /* ARGSUSED */
 120 void
 121 chargen_dg(int s, struct servtab *sep)          /* Character generator */
 122 {
 123         struct sockaddr_storage ss;
 124         static char *rs;
 125         int len;
 126         socklen_t size;
 127         char text[LINESIZ+2];
 128
 129         if (endring == NULL) {
 130                 initring();
 131                 rs = ring;
 132         }
 133
 134         size = sizeof(ss);
 135         if (recvfrom(s, text, sizeof(text), 0,
 136                      (struct sockaddr *)&ss, &size) < 0)
 137                 return;
 138
 139         if (check_loop((struct sockaddr *)&ss, sep))
 140                 return;
 141
 142         if ((len = endring - rs) >= LINESIZ)
 143                 memmove(text, rs, LINESIZ);
 144         else {
 145                 memmove(text, rs, len);
 146                 memmove(text + len, ring, LINESIZ - len);
 147         }
 148         if (++rs == endring)
 149                 rs = ring;
 150         text[LINESIZ] = '\r';
 151         text[LINESIZ + 1] = '\n';
 152         sendto(s, text, sizeof(text), 0, (struct sockaddr *)&ss, size);
 153 }
 154
 155 /* ARGSUSED */
 156 void
 157 chargen_stream(int s, struct servtab *sep)              /* Character generator */
 158 {
 159         int len;
 160         char *rs, text[LINESIZ+2];
 161
 162         inetd_setproctitle(sep->se_service, s);
 163
 164         if (!endring) {
 165                 initring();
 166                 rs = ring;
 167         }
 168
 169         text[LINESIZ] = '\r';
 170         text[LINESIZ + 1] = '\n';
 171         for (rs = ring;;) {
 172                 if ((len = endring - rs) >= LINESIZ)
 173                         memmove(text, rs, LINESIZ);
 174                 else {
 175                         memmove(text, rs, len);
 176                         memmove(text + len, ring, LINESIZ - len);
 177                 }
 178                 if (++rs == endring)
 179                         rs = ring;
 180                 if (write(s, text, sizeof(text)) != sizeof(text))
 181                         break;
 182         }
 183         exit(0);
 184 }
 185
 186 /*
 187  * RFC867 Daytime Protocol. Sends the current date and time as an ascii
 188  * character string without any regard for input.
 189  */
 190
 191 /* ARGSUSED */
 192 void
 193 daytime_dg(int s, struct servtab *sep)          /* Return human-readable time of day */
 194 {
 195         char buffer[256];
 196         time_t now;
 197         struct sockaddr_storage ss;
 198         socklen_t size;
 199
 200         now = time(NULL);
 201
 202         size = sizeof(ss);
 203         if (recvfrom(s, buffer, sizeof(buffer), 0,
 204                      (struct sockaddr *)&ss, &size) < 0)
 205                 return;
 206
 207         if (check_loop((struct sockaddr *)&ss, sep))
 208                 return;
 209
 210         sprintf(buffer, "%.24s\r\n", ctime(&now));
 211         sendto(s, buffer, strlen(buffer), 0, (struct sockaddr *)&ss, size);
 212 }
 213
 214 /* ARGSUSED */
 215 void
 216 daytime_stream(int s, struct servtab *sep __unused) /* Return human-readable time of day */
 217 {
 218         char buffer[256];
 219         time_t now;
 220
 221         now = time(NULL);
 222
 223         sprintf(buffer, "%.24s\r\n", ctime(&now));
 224         send(s, buffer, strlen(buffer), MSG_EOF);
 225 }
 226
 227 /*
 228  * RFC863 Discard Protocol. Any data received is thrown away and no response
 229  * is sent.
 230  */
 231
 232 /* ARGSUSED */
 233 void
 234 discard_dg(int s, struct servtab *sep __unused) /* Discard service -- ignore data */
 235 {
 236         char buffer[BUFSIZE];
 237
 238         read(s, buffer, sizeof(buffer));
 239 }
 240
 241 /* ARGSUSED */
 242 void
 243 discard_stream(int s, struct servtab *sep) /* Discard service -- ignore data */
 244 {
 245         int ret;
 246         char buffer[BUFSIZE];
 247
 248         inetd_setproctitle(sep->se_service, s);
 249         while (1) {
 250                 while ((ret = read(s, buffer, sizeof(buffer))) > 0)
 251                         ;
 252                 if (ret == 0 || errno != EINTR)
 253                         break;
 254         }
 255         exit(0);
 256 }
 257
 258 /*
 259  * RFC862 Echo Protocol. Any data received is sent back to the sender as
 260  * received.
 261  */
 262
 263 /* ARGSUSED */
 264 void
 265 echo_dg(int s, struct servtab *sep) /* Echo service -- echo data back */
 266 {
 267         char buffer[65536]; /* Should be sizeof(max datagram). */
 268         int i;
 269         socklen_t size;
 270         struct sockaddr_storage ss;
 271
 272         size = sizeof(ss);
 273         if ((i = recvfrom(s, buffer, sizeof(buffer), 0,
 274                           (struct sockaddr *)&ss, &size)) < 0)
 275                 return;
 276
 277         if (check_loop((struct sockaddr *)&ss, sep))
 278                 return;
 279
 280         sendto(s, buffer, i, 0, (struct sockaddr *)&ss, size);
 281 }
 282
 283 /* ARGSUSED */
 284 void
 285 echo_stream(int s, struct servtab *sep)         /* Echo service -- echo data back */
 286 {
 287         char buffer[BUFSIZE];
 288         int i;
 289
 290         inetd_setproctitle(sep->se_service, s);
 291         while ((i = read(s, buffer, sizeof(buffer))) > 0 &&
 292             write(s, buffer, i) > 0)
 293                 ;
 294         exit(0);
 295 }
 296
 297 /*
 298  * RFC1413 Identification Protocol. Given a TCP port number pair, return a
 299  * character string which identifies the owner of that connection on the
 300  * server's system. Extended to allow for ~/.fakeid support and ~/.noident
 301  * support.
 302  */
 303
 304 /* RFC 1413 says the following are the only errors you can return. */
 305 #define ID_INVALID      "INVALID-PORT"  /* Port number improperly specified. */
 306 #define ID_NOUSER       "NO-USER"       /* Port not in use/not identifable. */
 307 #define ID_HIDDEN       "HIDDEN-USER"   /* Hiden at user's request. */
 308 #define ID_UNKNOWN      "UNKNOWN-ERROR" /* Everything else. */
 309
 310 /* ARGSUSED */
 311 void
 312 iderror(int lport, int fport, int s, const char *er)    /* Generic ident_stream error-sending func */
 313 {
 314         char *p;
 315
 316         asprintf(&p, "%d , %d : ERROR : %s\r\n", lport, fport, er);
 317         if (p == NULL) {
 318                 syslog(LOG_ERR, "asprintf: %m");
 319                 exit(EX_OSERR);
 320         }
 321         send(s, p, strlen(p), MSG_EOF);
 322         free(p);
 323
 324         exit(0);
 325 }
 326
 327 /* ARGSUSED */
 328 void
 329 ident_stream(int s, struct servtab *sep)                /* Ident service (AKA "auth") */
 330 {
 331         struct utsname un;
 332         struct stat sb;
 333         struct sockaddr_in sin4[2];
 334 #ifdef INET6
 335         struct sockaddr_in6 sin6[2];
 336 #endif
 337         struct sockaddr_storage ss[2];
 338         struct ucred uc;
 339         struct timeval tv = {
 340                 10,
 341                 0
 342         }, to;
 343         struct passwd *pw = NULL;
 344         fd_set fdset;
 345         char buf[BUFSIZE], *p, **av, *osname = NULL, e;
 346         char idbuf[MAXLOGNAME] = ""; /* Big enough to hold uid in decimal. */
 347         socklen_t socklen;
 348         ssize_t ssize;
 349         size_t size, bufsiz;
 350         int c, fflag = 0, nflag = 0, rflag = 0, argc = 0;
 351         int gflag = 0, iflag = 0, Fflag = 0, getcredfail = 0, onreadlen;
 352         u_short lport, fport;
 353
 354         inetd_setproctitle(sep->se_service, s);
 355         /*
 356          * Reset getopt() since we are a fork() but not an exec() from
 357          * a parent which used getopt() already.
 358          */
 359         optind = 1;
 360         optreset = 1;
 361         /*
 362          * Take the internal argument vector and count it out to make an
 363          * argument count for getopt. This can be used for any internal
 364          * service to read arguments and use getopt() easily.
 365          */
 366         for (av = sep->se_argv; *av; av++)
 367                 argc++;
 368         if (argc) {
 369                 int sec, usec;
 370                 size_t i;
 371                 u_int32_t rnd32;
 372
 373                 while ((c = getopt(argc, sep->se_argv, "d:fFgino:rt:")) != -1)
 374                         switch (c) {
 375                         case 'd':
 376                                 if (!gflag)
 377                                         strlcpy(idbuf, optarg, sizeof(idbuf));
 378                                 break;
 379                         case 'f':
 380                                 fflag = 1;
 381                                 break;
 382                         case 'F':
 383                                 fflag = 1;
 384                                 Fflag=1;
 385                                 break;
 386                         case 'g':
 387                                 gflag = 1;
 388                                 rnd32 = 0;      /* Shush, compiler. */
 389                                 /*
 390                                  * The number of bits in "rnd32" divided
 391                                  * by the number of bits needed per iteration
 392                                  * gives a more optimal way to reload the
 393                                  * random number only when necessary.
 394                                  *
 395                                  * 32 bits from arc4random corresponds to
 396                                  * about 6 base-36 digits, so we reseed evey 6.
 397                                  */
 398                                 for (i = 0; i < sizeof(idbuf) - 1; i++) {
 399                                         static const char *const base36 =
 400                                             "0123456789"
 401                                             "abcdefghijklmnopqrstuvwxyz";
 402                                         if (i % 6 == 0)
 403                                                 rnd32 = arc4random();
 404                                         idbuf[i] = base36[rnd32 % 36];
 405                                         rnd32 /= 36;
 406                                 }
 407                                 idbuf[i] = '\0';
 408                                 break;
 409                         case 'i':
 410                                 iflag = 1;
 411                                 break;
 412                         case 'n':
 413                                 nflag = 1;
 414                                 break;
 415                         case 'o':
 416                                 osname = optarg;
 417                                 break;
 418                         case 'r':
 419                                 rflag = 1;
 420                                 break;
 421                         case 't':
 422                                 switch (sscanf(optarg, "%d.%d", &sec, &usec)) {
 423                                 case 2:
 424                                         tv.tv_usec = usec;
 425                                         /* FALLTHROUGH */
 426                                 case 1:
 427                                         tv.tv_sec = sec;
 428                                         break;
 429                                 default:
 430                                         if (debug)
 431                                                 warnx("bad -t argument");
 432                                         break;
 433                                 }
 434                                 break;
 435                         default:
 436                                 break;
 437                         }
 438         }
 439         if (osname == NULL) {
 440                 if (uname(&un) == -1)
 441                         iderror(0, 0, s, ID_UNKNOWN);
 442                 osname = un.sysname;
 443         }
 444
 445         /*
 446          * We're going to prepare for and execute reception of a
 447          * packet of data from the user. The data is in the format
 448          * "local_port , foreign_port\r\n" (with local being the
 449          * server's port and foreign being the client's.)
 450          */
 451         gettimeofday(&to, NULL);
 452         to.tv_sec += tv.tv_sec;
 453         to.tv_usec += tv.tv_usec;
 454         if (to.tv_usec >= 1000000) {
 455                 to.tv_usec -= 1000000;
 456                 to.tv_sec++;
 457         }
 458
 459         size = 0;
 460         bufsiz = sizeof(buf) - 1;
 461         FD_ZERO(&fdset);
 462         while (bufsiz > 0) {
 463                 gettimeofday(&tv, NULL);
 464                 tv.tv_sec = to.tv_sec - tv.tv_sec;
 465                 tv.tv_usec = to.tv_usec - tv.tv_usec;
 466                 if (tv.tv_usec < 0) {
 467                         tv.tv_usec += 1000000;
 468                         tv.tv_sec--;
 469                 }
 470                 if (tv.tv_sec < 0)
 471                         break;
 472                 FD_SET(s, &fdset);
 473                 if (select(s + 1, &fdset, NULL, NULL, &tv) == -1)
 474                         iderror(0, 0, s, ID_UNKNOWN);
 475                 if (ioctl(s, FIONREAD, &onreadlen) == -1)
 476                         iderror(0, 0, s, ID_UNKNOWN);
 477                 if ((size_t)onreadlen > bufsiz)
 478                         onreadlen = bufsiz;
 479                 ssize = read(s, &buf[size], (size_t)onreadlen);
 480                 if (ssize == -1)
 481                         iderror(0, 0, s, ID_UNKNOWN);
 482                 else if (ssize == 0)
 483                         break;
 484                 bufsiz -= ssize;
 485                 size += ssize;
 486                 if (memchr(&buf[size - ssize], '\n', ssize) != NULL)
 487                         break;
 488         }
 489         buf[size] = '\0';
 490         /* Read two characters, and check for a delimiting character */
 491         if (sscanf(buf, "%hu , %hu%c", &lport, &fport, &e) != 3 || isdigit(e))
 492                 iderror(0, 0, s, ID_INVALID);
 493
 494         /* Send garbage? */
 495         if (gflag)
 496                 goto printit;
 497
 498         /*
 499          * If not "real" (-r), send a HIDDEN-USER error for everything.
 500          * If -d is used to set a fallback username, this is used to
 501          * override it, and the fallback is returned instead.
 502          */
 503         if (!rflag) {
 504                 if (*idbuf == '\0')
 505                         iderror(lport, fport, s, ID_HIDDEN);
 506                 goto printit;
 507         }
 508
 509         /*
 510          * We take the input and construct an array of two sockaddr_ins
 511          * which contain the local address information and foreign
 512          * address information, respectively, used to look up the
 513          * credentials for the socket (which are returned by the
 514          * sysctl "net.inet.tcp.getcred" when we call it.)
 515          */
 516         socklen = sizeof(ss[0]);
 517         if (getsockname(s, (struct sockaddr *)&ss[0], &socklen) == -1)
 518                 iderror(lport, fport, s, ID_UNKNOWN);
 519         socklen = sizeof(ss[1]);
 520         if (getpeername(s, (struct sockaddr *)&ss[1], &socklen) == -1)
 521                 iderror(lport, fport, s, ID_UNKNOWN);
 522         if (ss[0].ss_family != ss[1].ss_family)
 523                 iderror(lport, fport, s, ID_UNKNOWN);
 524         size = sizeof(uc);
 525         switch (ss[0].ss_family) {
 526         case AF_INET:
 527                 sin4[0] = *(struct sockaddr_in *)&ss[0];
 528                 sin4[0].sin_port = htons(lport);
 529                 sin4[1] = *(struct sockaddr_in *)&ss[1];
 530                 sin4[1].sin_port = htons(fport);
 531                 if (sysctlbyname("net.inet.tcp.getcred", &uc, &size, sin4,
 532                                  sizeof(sin4)) == -1)
 533                         getcredfail = errno;
 534                 break;
 535 #ifdef INET6
 536         case AF_INET6:
 537                 sin6[0] = *(struct sockaddr_in6 *)&ss[0];
 538                 sin6[0].sin6_port = htons(lport);
 539                 sin6[1] = *(struct sockaddr_in6 *)&ss[1];
 540                 sin6[1].sin6_port = htons(fport);
 541                 if (sysctlbyname("net.inet6.tcp6.getcred", &uc, &size, sin6,
 542                                  sizeof(sin6)) == -1)
 543                         getcredfail = errno;
 544                 break;
 545 #endif
 546         default: /* should not reach here */
 547                 getcredfail = EAFNOSUPPORT;
 548                 break;
 549         }
 550         if (getcredfail != 0) {
 551                 if (*idbuf == '\0')
 552                         iderror(lport, fport, s,
 553                             getcredfail == ENOENT ? ID_NOUSER : ID_UNKNOWN);
 554                 goto printit;
 555         }
 556
 557         /* Look up the pw to get the username and home directory*/
 558         errno = 0;
 559         pw = getpwuid(uc.cr_uid);
 560         if (pw == NULL)
 561                 iderror(lport, fport, s, errno == 0 ? ID_NOUSER : ID_UNKNOWN);
 562
 563         if (iflag)
 564                 snprintf(idbuf, sizeof(idbuf), "%u", (unsigned)pw->pw_uid);
 565         else
 566                 strlcpy(idbuf, pw->pw_name, sizeof(idbuf));
 567
 568         /*
 569          * If enabled, we check for a file named ".noident" in the user's
 570          * home directory. If found, we return HIDDEN-USER.
 571          */
 572         if (nflag) {
 573                 if (asprintf(&p, "%s/.noident", pw->pw_dir) == -1)
 574                         iderror(lport, fport, s, ID_UNKNOWN);
 575                 if (lstat(p, &sb) == 0) {
 576                         free(p);
 577                         iderror(lport, fport, s, ID_HIDDEN);
 578                 }
 579                 free(p);
 580         }
 581
 582         /*
 583          * Here, if enabled, we read a user's ".fakeid" file in their
 584          * home directory. It consists of a line containing the name
 585          * they want.
 586          */
 587         if (fflag) {
 588                 int fakeid_fd;
 589
 590                 /*
 591                  * Here we set ourself to effectively be the user, so we don't
 592                  * open any files we have no permission to open, especially
 593                  * symbolic links to sensitive root-owned files or devices.
 594                  */
 595                 if (initgroups(pw->pw_name, pw->pw_gid) == -1)
 596                         iderror(lport, fport, s, ID_UNKNOWN);
 597                 if (seteuid(pw->pw_uid) == -1)
 598                         iderror(lport, fport, s, ID_UNKNOWN);
 599                 /*
 600                  * We can't stat() here since that would be a race
 601                  * condition.
 602                  * Therefore, we open the file we have permissions to open
 603                  * and if it's not a regular file, we close it and end up
 604                  * returning the user's real username.
 605                  */
 606                 if (asprintf(&p, "%s/.fakeid", pw->pw_dir) == -1)
 607                         iderror(lport, fport, s, ID_UNKNOWN);
 608                 fakeid_fd = open(p, O_RDONLY | O_NONBLOCK);
 609                 free(p);
 610                 if (fakeid_fd == -1 || fstat(fakeid_fd, &sb) == -1 ||
 611                     !S_ISREG(sb.st_mode))
 612                         goto fakeid_fail;
 613
 614                 if ((ssize = read(fakeid_fd, buf, sizeof(buf) - 1)) < 0)
 615                         goto fakeid_fail;
 616                 buf[ssize] = '\0';
 617
 618                 /*
 619                  * Usually, the file will have the desired identity
 620                  * in the form "identity\n". Allow for leading white
 621                  * space and trailing white space/end of line.
 622                  */
 623                 p = buf;
 624                 p += strspn(p, " \t");
 625                 p[strcspn(p, " \t\r\n")] = '\0';
 626                 if (strlen(p) > MAXLOGNAME - 1) /* Too long (including nul)? */
 627                         p[MAXLOGNAME - 1] = '\0';
 628
 629                 /*
 630                  * If the name is a zero-length string or matches it
 631                  * the id or name of another user (unless permitted by -F)
 632                  * then it is invalid.
 633                  */
 634                 if (*p == '\0')
 635                         goto fakeid_fail;
 636                 if (!Fflag) {
 637                         if (iflag) {
 638                                 if (p[strspn(p, "0123456789")] == '\0' &&
 639                                     getpwuid(atoi(p)) != NULL)
 640                                         goto fakeid_fail;
 641                         } else {
 642                                 if (getpwnam(p) != NULL)
 643                                         goto fakeid_fail;
 644                         }
 645                 }
 646
 647                 strlcpy(idbuf, p, sizeof(idbuf));
 648
 649 fakeid_fail:
 650                 if (fakeid_fd != -1)
 651                         close(fakeid_fd);
 652         }
 653
 654 printit:
 655         /* Finally, we make and send the reply. */
 656         if (asprintf(&p, "%d , %d : USERID : %s : %s\r\n", lport, fport, osname,
 657             idbuf) == -1) {
 658                 syslog(LOG_ERR, "asprintf: %m");
 659                 exit(EX_OSERR);
 660         }
 661         send(s, p, strlen(p), MSG_EOF);
 662         free(p);
 663
 664         exit(0);
 665 }
 666
 667 /*
 668  * RFC738 Time Server.
 669  * Return a machine readable date and time, in the form of the
 670  * number of seconds since midnight, Jan 1, 1900.  Since gettimeofday
 671  * returns the number of seconds since midnight, Jan 1, 1970,
 672  * we must add 2208988800 seconds to this figure to make up for
 673  * some seventy years Bell Labs was asleep.
 674  */
 675
 676 unsigned long
 677 machtime(void)
 678 {
 679         struct timeval tv;
 680
 681         if (gettimeofday(&tv, NULL) < 0) {
 682                 if (debug)
 683                         warnx("unable to get time of day");
 684                 return (0L);
 685         }
 686 #define OFFSET ((u_long)25567 * 24*60*60)
 687         return (htonl((long)(tv.tv_sec + OFFSET)));
 688 #undef OFFSET
 689 }
 690
 691 /* ARGSUSED */
 692 void
 693 machtime_dg(int s, struct servtab *sep)
 694 {
 695         unsigned long result;
 696         struct sockaddr_storage ss;
 697         socklen_t size;
 698
 699         size = sizeof(ss);
 700         if (recvfrom(s, (char *)&result, sizeof(result), 0,
 701                      (struct sockaddr *)&ss, &size) < 0)
 702                 return;
 703
 704         if (check_loop((struct sockaddr *)&ss, sep))
 705                 return;
 706
 707         result = machtime();
 708         sendto(s, (char *) &result, sizeof(result), 0,
 709                       (struct sockaddr *)&ss, size);
 710 }
 711
 712 /* ARGSUSED */
 713 void
 714 machtime_stream(int s, struct servtab *sep __unused)
 715 {
 716         unsigned long result;
 717
 718         result = machtime();
 719         send(s, (char *) &result, sizeof(result), MSG_EOF);
 720 }
 721
 722 /*
 723  * RFC1078 TCP Port Service Multiplexer (TCPMUX). Service connections to
 724  * services based on the service name sent.
 725  *
 726  *  Based on TCPMUX.C by Mark K. Lottor November 1988
 727  *  sri-nic::ps:<mkl>tcpmux.c
 728  */
 729
 730 #define MAX_SERV_LEN    (256+2)         /* 2 bytes for \r\n */
 731 #define strwrite(fd, buf)       write(fd, buf, sizeof(buf)-1)
 732
 733 static int              /* # of characters upto \r,\n or \0 */
 734 get_line(int fd, char *buf, int len)
 735 {
 736         int count = 0, n;
 737         struct sigaction sa;
 738
 739         sa.sa_flags = 0;
 740         sigemptyset(&sa.sa_mask);
 741         sa.sa_handler = SIG_DFL;
 742         sigaction(SIGALRM, &sa, NULL);
 743         do {
 744                 alarm(10);
 745                 n = read(fd, buf, len-count);
 746                 alarm(0);
 747                 if (n == 0)
 748                         return (count);
 749                 if (n < 0)
 750                         return (-1);
 751                 while (--n >= 0) {
 752                         if (*buf == '\r' || *buf == '\n' || *buf == '\0')
 753                                 return (count);
 754                         count++;
 755                         buf++;
 756                 }
 757         } while (count < len);
 758         return (count);
 759 }
 760
 761 struct servtab *
 762 tcpmux(int s)
 763 {
 764         struct servtab *sep;
 765         char service[MAX_SERV_LEN+1];
 766         int len;
 767
 768         /* Get requested service name */
 769         if ((len = get_line(s, service, MAX_SERV_LEN)) < 0) {
 770                 strwrite(s, "-Error reading service name\r\n");
 771                 return (NULL);
 772         }
 773         service[len] = '\0';
 774
 775         if (debug)
 776                 warnx("tcpmux: someone wants %s", service);
 777
 778         /*
 779          * Help is a required command, and lists available services,
 780          * one per line.
 781          */
 782         if (!strcasecmp(service, "help")) {
 783                 for (sep = servtab; sep; sep = sep->se_next) {
 784                         if (!ISMUX(sep))
 785                                 continue;
 786                         write(s,sep->se_service,strlen(sep->se_service));
 787                         strwrite(s, "\r\n");
 788                 }
 789                 return (NULL);
 790         }
 791
 792         /* Try matching a service in inetd.conf with the request */
 793         for (sep = servtab; sep; sep = sep->se_next) {
 794                 if (!ISMUX(sep))
 795                         continue;
 796                 if (!strcasecmp(service, sep->se_service)) {
 797                         if (ISMUXPLUS(sep)) {
 798                                 strwrite(s, "+Go\r\n");
 799                         }
 800                         return (sep);
 801                 }
 802         }
 803         strwrite(s, "-Service not available\r\n");
 804         return (NULL);
 805 }