identd.c revision 1.8
1 /* $NetBSD: identd.c,v 1.8 1997/10/08 07:07:49 mrg Exp $ */ 2 3 /* 4 ** identd.c A TCP/IP link identification protocol server 5 ** 6 ** This program is in the public domain and may be used freely by anyone 7 ** who wants to. 8 ** 9 ** Last update: 22 April 1993 10 ** 11 ** Please send bug fixes/bug reports to: Peter Eriksson <pen (at) lysator.liu.se> 12 */ 13 14 #if defined(IRIX) || defined(SVR4) || defined(NeXT) || defined(__NetBSD__) 15 # define SIGRETURN_TYPE void 16 # define SIGRETURN_TYPE_IS_VOID 17 #else 18 # define SIGRETURN_TYPE int 19 #endif 20 21 #ifdef SVR4 22 # define STRNET 23 #endif 24 25 #include <sys/types.h> 26 #include <sys/param.h> 27 #include <sys/ioctl.h> 28 #include <sys/socket.h> 29 #ifndef _AUX_SOURCE 30 # include <sys/file.h> 31 #endif 32 #include <sys/time.h> 33 #include <sys/wait.h> 34 35 #include <stdio.h> 36 #include <string.h> 37 #include <ctype.h> 38 #include <errno.h> 39 #include <netdb.h> 40 #include <signal.h> 41 #include <fcntl.h> 42 #include <stdlib.h> 43 #include <unistd.h> 44 45 #include <pwd.h> 46 #include <grp.h> 47 48 #include <netinet/in.h> 49 50 #ifndef HPUX7 51 # include <arpa/inet.h> 52 #endif 53 54 #if defined(MIPS) || defined(BSD43) 55 extern int errno; 56 #endif 57 58 #include "identd.h" 59 #include "error.h" 60 61 /* Antique unixes do not have these things defined... */ 62 #ifndef FD_SETSIZE 63 # define FD_SETSIZE 256 64 #endif 65 66 #ifndef FD_SET 67 # ifndef NFDBITS 68 # define NFDBITS (sizeof(int) * NBBY) /* bits per mask */ 69 # endif 70 # define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) 71 #endif 72 73 #ifndef FD_ZERO 74 # define FD_ZERO(p) bzero((char *)(p), sizeof(*(p))) 75 #endif 76 77 extern char *version; 78 79 char *path_unix = NULL; 80 char *path_kmem = NULL; 81 82 int verbose_flag = 0; 83 int debug_flag = 0; 84 int syslog_flag = 0; 85 int multi_flag = 0; 86 int other_flag = 0; 87 int unknown_flag = 0; 88 int number_flag = 0; 89 int noident_flag = 0; 90 91 int lport = 0; 92 int fport = 0; 93 94 char *charset_name = NULL; 95 char *indirect_host = NULL; 96 char *indirect_password = NULL; 97 98 static int child_pid; 99 100 #ifdef LOG_DAEMON 101 static int syslog_facility = LOG_DAEMON; 102 #endif 103 104 char *clearmem __P((char *, int)); 105 static SIGRETURN_TYPE alarm_handler __P((int)); 106 int main __P((int, char *[])); 107 108 /* 109 ** The structure passing convention for GCC is incompatible with 110 ** Suns own C compiler, so we define our own inet_ntoa() function. 111 ** (This should only affect GCC version 1 I think, a well, this works 112 ** for version 2 also so why bother.. :-) 113 */ 114 #if defined(__GNUC__) && defined(__sparc__) 115 116 #ifdef inet_ntoa 117 #undef inet_ntoa 118 #endif 119 120 char *inet_ntoa(ad) 121 struct in_addr ad; 122 { 123 unsigned long int s_ad; 124 int a, b, c, d; 125 static char addr[20]; 126 127 s_ad = ad.s_addr; 128 d = s_ad % 256; 129 s_ad /= 256; 130 c = s_ad % 256; 131 s_ad /= 256; 132 b = s_ad % 256; 133 a = s_ad / 256; 134 sprintf(addr, "%d.%d.%d.%d", a, b, c, d); 135 136 return addr; 137 } 138 #endif 139 140 141 /* 142 ** Return the name of the connecting host, or the IP number as a string. 143 */ 144 char *gethost(addr) 145 struct in_addr *addr; 146 { 147 struct hostent *hp; 148 149 150 hp = gethostbyaddr((char *) addr, sizeof(struct in_addr), AF_INET); 151 if (hp) 152 return hp->h_name; 153 else 154 return inet_ntoa(*addr); 155 } 156 157 /* 158 ** Exit cleanly after our time's up. 159 */ 160 static SIGRETURN_TYPE 161 alarm_handler(dummy) 162 int dummy; 163 { 164 if (syslog_flag) 165 syslog(LOG_DEBUG, "SIGALRM triggered, exiting"); 166 167 exit(0); 168 } 169 170 #if !defined(hpux) && !defined(__hpux) && !defined(SVR4) && !defined(__NetBSD__) || defined(_CRAY) 171 /* 172 ** This is used to clean up zombie child processes 173 ** if the -w or -b options are used. 174 */ 175 static SIGRETURN_TYPE 176 child_handler() 177 { 178 #if defined(IRIX) || defined(NeXT) 179 union wait status; 180 #else 181 int status; 182 #endif 183 184 while (wait3(&status, WNOHANG, NULL) > 0) 185 ; 186 187 #ifndef SIGRETURN_TYPE_IS_VOID 188 return 0; 189 #endif 190 } 191 #endif 192 193 char *clearmem(bp, len) 194 char *bp; 195 int len; 196 { 197 char *cp; 198 199 cp = bp; 200 while (len-- > 0) 201 *cp++ = 0; 202 203 return bp; 204 } 205 206 207 /* 208 ** Main entry point into this daemon 209 */ 210 int main(argc,argv) 211 int argc; 212 char *argv[]; 213 { 214 int i, len; 215 struct sockaddr_in sin; 216 struct in_addr laddr, faddr; 217 struct timeval tv; 218 219 int background_flag = 0; 220 int timeout = 0; 221 char *portno = "113"; 222 char *bind_address = NULL; 223 int set_uid = 0; 224 int set_gid = 0; 225 int inhibit_default_config = 0; 226 int opt_count = 0; /* Count of option flags */ 227 228 #ifdef __convex__ 229 argc--; /* get rid of extra argument passed by inetd */ 230 #endif 231 232 /* 233 ** Prescan the arguments for "-f<config-file>" switches 234 */ 235 inhibit_default_config = 0; 236 for (i = 1; i < argc && argv[i][0] == '-'; i++) 237 if (argv[i][1] == 'f') 238 inhibit_default_config = 1; 239 240 /* 241 ** Parse the default config file - if it exists 242 */ 243 if (!inhibit_default_config) 244 parse_config(NULL, 1); 245 246 /* 247 ** Parse the command line arguments 248 */ 249 for (i = 1; i < argc && argv[i][0] == '-'; i++) { 250 opt_count++; 251 switch (argv[i][1]) 252 { 253 case 'b': /* Start as standalone daemon */ 254 background_flag = 1; 255 break; 256 257 case 'w': /* Start from Inetd, wait mode */ 258 background_flag = 2; 259 break; 260 261 case 'i': /* Start from Inetd, nowait mode */ 262 background_flag = 0; 263 break; 264 265 case 't': 266 timeout = atoi(argv[i]+2); 267 break; 268 269 case 'p': 270 portno = argv[i]+2; 271 break; 272 273 case 'a': 274 bind_address = argv[i]+2; 275 break; 276 277 case 'u': 278 if (isdigit(argv[i][2])) 279 set_uid = atoi(argv[i]+2); 280 else 281 { 282 struct passwd *pwd; 283 284 pwd = getpwnam(argv[i]+2); 285 if (!pwd) 286 ERROR1("no such user (%s) for -u option", argv[i]+2); 287 else 288 { 289 set_uid = pwd->pw_uid; 290 set_gid = pwd->pw_gid; 291 } 292 } 293 break; 294 295 case 'g': 296 if (isdigit(argv[i][2])) 297 set_gid = atoi(argv[i]+2); 298 else 299 { 300 struct group *grp; 301 302 grp = getgrnam(argv[i]+2); 303 if (!grp) 304 ERROR1("no such group (%s) for -g option", argv[i]+2); 305 else 306 set_gid = grp->gr_gid; 307 } 308 break; 309 310 case 'c': 311 charset_name = argv[i]+2; 312 break; 313 314 case 'r': 315 indirect_host = argv[i]+2; 316 break; 317 318 case 'l': /* Use the Syslog daemon for logging */ 319 syslog_flag++; 320 break; 321 322 case 'o': 323 other_flag = 1; 324 break; 325 326 case 'e': 327 unknown_flag = 1; 328 break; 329 330 case 'n': 331 number_flag = 1; 332 break; 333 334 case 'V': /* Give version of this daemon */ 335 printf("[in.identd, version %s]\r\n", version); 336 exit(0); 337 break; 338 339 case 'v': /* Be verbose */ 340 verbose_flag++; 341 break; 342 343 case 'd': /* Enable debugging */ 344 debug_flag++; 345 break; 346 347 case 'm': /* Enable multiline queries */ 348 multi_flag++; 349 break; 350 351 case 'N': /* Enable users ".noident" files */ 352 noident_flag++; 353 break; 354 } 355 } 356 357 #if defined(_AUX_SOURCE) || defined (SUNOS35) 358 /* A/UX 2.0* & SunOS 3.5 calls us with an argument XXXXXXXX.YYYY 359 ** where XXXXXXXXX is the hexadecimal version of the callers 360 ** IP number, and YYYY is the port/socket or something. 361 ** It seems to be impossible to pass arguments to a daemon started 362 ** by inetd. 363 ** 364 ** Just in case it is started from something else, then we only 365 ** skip the argument if no option flags have been seen. 366 */ 367 if (opt_count == 0) 368 argc--; 369 #endif 370 371 /* 372 ** Path to kernel namelist file specified on command line 373 */ 374 if (i < argc) 375 path_unix = argv[i++]; 376 377 /* 378 ** Path to kernel memory device specified on command line 379 */ 380 if (i < argc) 381 path_kmem = argv[i++]; 382 383 384 /* 385 ** Open the kernel memory device and read the nlist table 386 */ 387 if (k_open() < 0) 388 ERROR("main: k_open"); 389 390 /* 391 ** Do the special handling needed for the "-b" flag 392 */ 393 if (background_flag == 1) 394 { 395 struct sockaddr_in addr; 396 struct servent *sp; 397 int fd; 398 399 400 if (fork()) 401 exit(0); 402 403 close(0); 404 close(1); 405 close(2); 406 407 if (fork()) 408 exit(0); 409 410 fd = socket(AF_INET, SOCK_STREAM, 0); 411 if (fd == -1) 412 ERROR("main: socket"); 413 414 if (fd != 0) 415 dup2(fd, 0); 416 417 clearmem((char *)&addr, sizeof(addr)); 418 419 addr.sin_len = sizeof(struct sockaddr_in); 420 addr.sin_family = AF_INET; 421 if (bind_address == NULL) 422 addr.sin_addr.s_addr = htonl(INADDR_ANY); 423 else 424 { 425 if (inet_aton(bind_address, &addr.sin_addr) == 0) 426 { 427 struct hostent *hp; 428 429 hp = gethostbyname(bind_address); 430 if (!hp) 431 ERROR1("no such address (%s) for -a switch", bind_address); 432 433 memcpy(&addr.sin_addr, hp->h_addr, sizeof(addr.sin_addr)); 434 } 435 } 436 437 if (isdigit(portno[0])) 438 addr.sin_port = htons(atoi(portno)); 439 else 440 { 441 sp = getservbyname(portno, "tcp"); 442 if (sp == NULL) 443 ERROR1("main: getservbyname: %s", portno); 444 addr.sin_port = sp->s_port; 445 } 446 447 if (bind(0, (struct sockaddr *) &addr, sizeof(addr)) < 0) 448 ERROR("main: bind"); 449 450 if (listen(0, 3) < 0) 451 ERROR("main: listen"); 452 } 453 454 if (set_gid) 455 if (setgid(set_gid) == -1) 456 ERROR("main: setgid"); 457 458 if (set_uid) 459 if (setuid(set_uid) == -1) 460 ERROR("main: setuid"); 461 462 /* 463 ** Do some special handling if the "-b" or "-w" flags are used 464 */ 465 if (background_flag) 466 { 467 int nfds, fd; 468 fd_set read_set; 469 470 471 /* 472 ** Set up the SIGCHLD signal child termination handler so 473 ** that we can avoid zombie processes hanging around and 474 ** handle childs terminating before being able to complete the 475 ** handshake. 476 */ 477 #if (defined(SVR4) || defined(hpux) || defined(__hpux) || \ 478 defined(__NetBSD__) || defined(_CRAY) || defined(_AUX_SOURCE)) 479 signal(SIGCHLD, SIG_IGN); 480 #else 481 signal(SIGCHLD, (SIGRETURN_TYPE (*)()) child_handler); 482 #endif 483 484 /* 485 ** Loop and dispatch client handling processes 486 */ 487 do 488 { 489 /* 490 ** Terminate if we've been idle for 'timeout' seconds 491 */ 492 if (background_flag == 2 && timeout) 493 { 494 signal(SIGALRM, alarm_handler); 495 alarm(timeout); 496 } 497 498 /* 499 ** Wait for a connection request to occur. 500 ** Ignore EINTR (Interrupted System Call). 501 */ 502 do 503 { 504 FD_ZERO(&read_set); 505 FD_SET(0, &read_set); 506 507 if (timeout) 508 { 509 tv.tv_sec = timeout; 510 tv.tv_usec = 0; 511 nfds = select(FD_SETSIZE, &read_set, NULL, NULL, &tv); 512 } 513 else 514 515 nfds = select(FD_SETSIZE, &read_set, NULL, NULL, NULL); 516 } while (nfds < 0 && errno == EINTR); 517 518 /* 519 ** An error occured in select? Just die 520 */ 521 if (nfds < 0) 522 ERROR("main: select"); 523 524 /* 525 ** Timeout limit reached. Exit nicely 526 */ 527 if (nfds == 0) 528 exit(0); 529 530 /* 531 ** Disable the alarm timeout 532 */ 533 alarm(0); 534 535 /* 536 ** Accept the new client 537 */ 538 fd = accept(0, NULL, NULL); 539 if (fd == -1) 540 ERROR1("main: accept. errno = %d", errno); 541 542 /* 543 ** And fork, then close the fd if we are the parent. 544 */ 545 child_pid = fork(); 546 } while (child_pid && (close(fd), 1)); 547 548 /* 549 ** We are now in child, the parent has returned to "do" above. 550 */ 551 if (dup2(fd, 0) == -1) 552 ERROR("main: dup2: failed fd 0"); 553 554 if (dup2(fd, 1) == -1) 555 ERROR("main: dup2: failed fd 1"); 556 557 if (dup2(fd, 2) == -1) 558 ERROR("main: dup2: failed fd 2"); 559 } 560 561 /* 562 ** Get foreign internet address 563 */ 564 len = sizeof(sin); 565 if (getpeername(0, (struct sockaddr *) &sin, &len) == -1) 566 { 567 /* 568 ** A user has tried to start us from the command line or 569 ** the network link died, in which case this message won't 570 ** reach to other end anyway, so lets give the poor user some 571 ** errors. 572 */ 573 perror("in.identd: getpeername()"); 574 exit(1); 575 } 576 577 faddr = sin.sin_addr; 578 579 580 /* 581 ** Open the connection to the Syslog daemon if requested 582 */ 583 if (syslog_flag) 584 { 585 #ifdef LOG_DAEMON 586 openlog("identd", LOG_PID, syslog_facility); 587 #else 588 openlog("identd", LOG_PID); 589 #endif 590 591 syslog(LOG_INFO, "Connection from %s", gethost(&faddr)); 592 } 593 594 595 /* 596 ** Get local internet address 597 */ 598 len = sizeof(sin); 599 #ifdef ATTSVR4 600 if (t_getsockname(0, (struct sockaddr *) &sin, &len) == -1) 601 #else 602 if (getsockname(0, (struct sockaddr *) &sin, &len) == -1) 603 #endif 604 { 605 /* 606 ** We can just die here, because if this fails then the 607 ** network has died and we haven't got anyone to return 608 ** errors to. 609 */ 610 exit(1); 611 } 612 laddr = sin.sin_addr; 613 614 615 /* 616 ** Get the local/foreign port pair from the luser 617 */ 618 parse(stdin, &laddr, &faddr); 619 620 exit(0); 621 } 622
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