identd.c revision 1.5
1 /* 2 ** $Id: identd.c,v 1.5 1995/06/07 17:14:21 cgd Exp $ 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 <stdio.h> 26 #include <string.h> 27 #include <ctype.h> 28 #include <errno.h> 29 #include <netdb.h> 30 #include <signal.h> 31 #include <fcntl.h> 32 33 #include <sys/types.h> 34 #include <sys/param.h> 35 #include <sys/ioctl.h> 36 #include <sys/socket.h> 37 #ifndef _AUX_SOURCE 38 # include <sys/file.h> 39 #endif 40 #include <sys/time.h> 41 #include <sys/wait.h> 42 43 #include <pwd.h> 44 #include <grp.h> 45 46 #include <netinet/in.h> 47 48 #ifndef HPUX7 49 # include <arpa/inet.h> 50 #endif 51 52 #if defined(MIPS) || defined(BSD43) 53 extern int errno; 54 #endif 55 56 #include "identd.h" 57 #include "error.h" 58 59 /* Antique unixes do not have these things defined... */ 60 #ifndef FD_SETSIZE 61 # define FD_SETSIZE 256 62 #endif 63 64 #ifndef FD_SET 65 # ifndef NFDBITS 66 # define NFDBITS (sizeof(int) * NBBY) /* bits per mask */ 67 # endif 68 # define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS))) 69 #endif 70 71 #ifndef FD_ZERO 72 # define FD_ZERO(p) bzero((char *)(p), sizeof(*(p))) 73 #endif 74 75 extern char *version; 76 77 extern void *calloc(); 78 extern void *malloc(); 79 80 81 char *path_unix = NULL; 82 char *path_kmem = NULL; 83 84 int verbose_flag = 0; 85 int debug_flag = 0; 86 int syslog_flag = 0; 87 int multi_flag = 0; 88 int other_flag = 0; 89 int unknown_flag = 0; 90 int number_flag = 0; 91 int noident_flag = 0; 92 93 int lport = 0; 94 int fport = 0; 95 96 char *charset_name = NULL; 97 char *indirect_host = NULL; 98 char *indirect_password = NULL; 99 100 static int child_pid; 101 102 #ifdef LOG_DAEMON 103 static int syslog_facility = LOG_DAEMON; 104 #endif 105 106 /* 107 ** The structure passing convention for GCC is incompatible with 108 ** Suns own C compiler, so we define our own inet_ntoa() function. 109 ** (This should only affect GCC version 1 I think, a well, this works 110 ** for version 2 also so why bother.. :-) 111 */ 112 #if defined(__GNUC__) && defined(__sparc__) 113 114 #ifdef inet_ntoa 115 #undef inet_ntoa 116 #endif 117 118 char *inet_ntoa(ad) 119 struct in_addr ad; 120 { 121 unsigned long int s_ad; 122 int a, b, c, d; 123 static char addr[20]; 124 125 s_ad = ad.s_addr; 126 d = s_ad % 256; 127 s_ad /= 256; 128 c = s_ad % 256; 129 s_ad /= 256; 130 b = s_ad % 256; 131 a = s_ad / 256; 132 sprintf(addr, "%d.%d.%d.%d", a, b, c, d); 133 134 return addr; 135 } 136 #endif 137 138 139 /* 140 ** Return the name of the connecting host, or the IP number as a string. 141 */ 142 char *gethost(addr) 143 struct in_addr *addr; 144 { 145 struct hostent *hp; 146 147 148 hp = gethostbyaddr((char *) addr, sizeof(struct in_addr), AF_INET); 149 if (hp) 150 return hp->h_name; 151 else 152 return inet_ntoa(*addr); 153 } 154 155 /* 156 ** Exit cleanly after our time's up. 157 */ 158 static SIGRETURN_TYPE 159 alarm_handler() 160 { 161 if (syslog_flag) 162 syslog(LOG_DEBUG, "SIGALRM triggered, exiting"); 163 164 exit(0); 165 } 166 167 #if !defined(hpux) && !defined(__hpux) && !defined(SVR4) || defined(_CRAY) 168 /* 169 ** This is used to clean up zombie child processes 170 ** if the -w or -b options are used. 171 */ 172 static SIGRETURN_TYPE 173 child_handler() 174 { 175 #if defined(IRIX) || defined(NeXT) 176 union wait status; 177 #else 178 int status; 179 #endif 180 181 while (wait3(&status, WNOHANG, NULL) > 0) 182 ; 183 184 #ifndef SIGRETURN_TYPE_IS_VOID 185 return 0; 186 #endif 187 } 188 #endif 189 190 191 char *clearmem(bp, len) 192 char *bp; 193 int len; 194 { 195 char *cp; 196 197 cp = bp; 198 while (len-- > 0) 199 *cp++ = 0; 200 201 return bp; 202 } 203 204 205 /* 206 ** Main entry point into this daemon 207 */ 208 int main(argc,argv) 209 int argc; 210 char *argv[]; 211 { 212 int i, len; 213 struct sockaddr_in sin; 214 struct in_addr laddr, faddr; 215 struct timeval tv; 216 217 int background_flag = 0; 218 int timeout = 0; 219 char *portno = "113"; 220 char *bind_address = NULL; 221 int set_uid = 0; 222 int set_gid = 0; 223 int inhibit_default_config = 0; 224 int opt_count = 0; /* Count of option flags */ 225 226 #ifdef __convex__ 227 argc--; /* get rid of extra argument passed by inetd */ 228 #endif 229 230 /* 231 ** Prescan the arguments for "-f<config-file>" switches 232 */ 233 inhibit_default_config = 0; 234 for (i = 1; i < argc && argv[i][0] == '-'; i++) 235 if (argv[i][1] == 'f') 236 inhibit_default_config = 1; 237 238 /* 239 ** Parse the default config file - if it exists 240 */ 241 if (!inhibit_default_config) 242 parse_config(NULL, 1); 243 244 /* 245 ** Parse the command line arguments 246 */ 247 for (i = 1; i < argc && argv[i][0] == '-'; i++) { 248 opt_count++; 249 switch (argv[i][1]) 250 { 251 case 'b': /* Start as standalone daemon */ 252 background_flag = 1; 253 break; 254 255 case 'w': /* Start from Inetd, wait mode */ 256 background_flag = 2; 257 break; 258 259 case 'i': /* Start from Inetd, nowait mode */ 260 background_flag = 0; 261 break; 262 263 case 't': 264 timeout = atoi(argv[i]+2); 265 break; 266 267 case 'p': 268 portno = argv[i]+2; 269 break; 270 271 case 'a': 272 bind_address = argv[i]+2; 273 break; 274 275 case 'u': 276 if (isdigit(argv[i][2])) 277 set_uid = atoi(argv[i]+2); 278 else 279 { 280 struct passwd *pwd; 281 282 pwd = getpwnam(argv[i]+2); 283 if (!pwd) 284 ERROR1("no such user (%s) for -u option", argv[i]+2); 285 else 286 { 287 set_uid = pwd->pw_uid; 288 set_gid = pwd->pw_gid; 289 } 290 } 291 break; 292 293 case 'g': 294 if (isdigit(argv[i][2])) 295 set_gid = atoi(argv[i]+2); 296 else 297 { 298 struct group *grp; 299 300 grp = getgrnam(argv[i]+2); 301 if (!grp) 302 ERROR1("no such group (%s) for -g option", argv[i]+2); 303 else 304 set_gid = grp->gr_gid; 305 } 306 break; 307 308 case 'c': 309 charset_name = argv[i]+2; 310 break; 311 312 case 'r': 313 indirect_host = argv[i]+2; 314 break; 315 316 case 'l': /* Use the Syslog daemon for logging */ 317 syslog_flag++; 318 break; 319 320 case 'o': 321 other_flag = 1; 322 break; 323 324 case 'e': 325 unknown_flag = 1; 326 break; 327 328 case 'n': 329 number_flag = 1; 330 break; 331 332 case 'V': /* Give version of this daemon */ 333 printf("[in.identd, version %s]\r\n", version); 334 exit(0); 335 break; 336 337 case 'v': /* Be verbose */ 338 verbose_flag++; 339 break; 340 341 case 'd': /* Enable debugging */ 342 debug_flag++; 343 break; 344 345 case 'm': /* Enable multiline queries */ 346 multi_flag++; 347 break; 348 349 case 'N': /* Enable users ".noident" files */ 350 noident_flag++; 351 break; 352 } 353 } 354 355 #if defined(_AUX_SOURCE) || defined (SUNOS35) 356 /* A/UX 2.0* & SunOS 3.5 calls us with an argument XXXXXXXX.YYYY 357 ** where XXXXXXXXX is the hexadecimal version of the callers 358 ** IP number, and YYYY is the port/socket or something. 359 ** It seems to be impossible to pass arguments to a daemon started 360 ** by inetd. 361 ** 362 ** Just in case it is started from something else, then we only 363 ** skip the argument if no option flags have been seen. 364 */ 365 if (opt_count == 0) 366 argc--; 367 #endif 368 369 /* 370 ** Path to kernel namelist file specified on command line 371 */ 372 if (i < argc) 373 path_unix = argv[i++]; 374 375 /* 376 ** Path to kernel memory device specified on command line 377 */ 378 if (i < argc) 379 path_kmem = argv[i++]; 380 381 382 /* 383 ** Open the kernel memory device and read the nlist table 384 */ 385 if (k_open() < 0) 386 ERROR("main: k_open"); 387 388 /* 389 ** Do the special handling needed for the "-b" flag 390 */ 391 if (background_flag == 1) 392 { 393 struct sockaddr_in addr; 394 struct servent *sp; 395 int fd; 396 397 398 if (fork()) 399 exit(0); 400 401 close(0); 402 close(1); 403 close(2); 404 405 if (fork()) 406 exit(0); 407 408 fd = socket(AF_INET, SOCK_STREAM, 0); 409 if (fd == -1) 410 ERROR("main: socket"); 411 412 if (fd != 0) 413 dup2(fd, 0); 414 415 clearmem(&addr, sizeof(addr)); 416 417 addr.sin_len = sizeof(struct sockaddr_in); 418 addr.sin_family = AF_INET; 419 if (bind_address == NULL) 420 addr.sin_addr.s_addr = htonl(INADDR_ANY); 421 else 422 { 423 if (inet_aton(bind_address, &addr.sin_addr) == 0) 424 { 425 struct hostent *hp; 426 427 hp = gethostbyname(bind_address); 428 if (!hp) 429 ERROR1("no such address (%s) for -a switch", bind_address); 430 431 memcpy(&addr.sin_addr, hp->h_addr, sizeof(addr.sin_addr)); 432 } 433 } 434 435 if (isdigit(portno[0])) 436 addr.sin_port = htons(atoi(portno)); 437 else 438 { 439 sp = getservbyname(portno, "tcp"); 440 if (sp == NULL) 441 ERROR1("main: getservbyname: %s", portno); 442 addr.sin_port = sp->s_port; 443 } 444 445 if (bind(0, (struct sockaddr *) &addr, sizeof(addr)) < 0) 446 ERROR("main: bind"); 447 448 if (listen(0, 3) < 0) 449 ERROR("main: listen"); 450 } 451 452 if (set_gid) 453 if (setgid(set_gid) == -1) 454 ERROR("main: setgid"); 455 456 if (set_uid) 457 if (setuid(set_uid) == -1) 458 ERROR("main: setuid"); 459 460 /* 461 ** Do some special handling if the "-b" or "-w" flags are used 462 */ 463 if (background_flag) 464 { 465 int nfds, fd; 466 fd_set read_set; 467 468 469 /* 470 ** Set up the SIGCHLD signal child termination handler so 471 ** that we can avoid zombie processes hanging around and 472 ** handle childs terminating before being able to complete the 473 ** handshake. 474 */ 475 #if (defined(SVR4) || defined(hpux) || defined(__hpux) || \ 476 defined(_CRAY) || defined(_AUX_SOURCE)) 477 signal(SIGCHLD, SIG_IGN); 478 #else 479 signal(SIGCHLD, (SIGRETURN_TYPE (*)()) child_handler); 480 #endif 481 482 /* 483 ** Loop and dispatch client handling processes 484 */ 485 do 486 { 487 /* 488 ** Terminate if we've been idle for 'timeout' seconds 489 */ 490 if (background_flag == 2 && timeout) 491 { 492 signal(SIGALRM, alarm_handler); 493 alarm(timeout); 494 } 495 496 /* 497 ** Wait for a connection request to occur. 498 ** Ignore EINTR (Interrupted System Call). 499 */ 500 do 501 { 502 FD_ZERO(&read_set); 503 FD_SET(0, &read_set); 504 505 if (timeout) 506 { 507 tv.tv_sec = timeout; 508 tv.tv_usec = 0; 509 nfds = select(FD_SETSIZE, &read_set, NULL, NULL, &tv); 510 } 511 else 512 513 nfds = select(FD_SETSIZE, &read_set, NULL, NULL, NULL); 514 } while (nfds < 0 && errno == EINTR); 515 516 /* 517 ** An error occured in select? Just die 518 */ 519 if (nfds < 0) 520 ERROR("main: select"); 521 522 /* 523 ** Timeout limit reached. Exit nicely 524 */ 525 if (nfds == 0) 526 exit(0); 527 528 /* 529 ** Disable the alarm timeout 530 */ 531 alarm(0); 532 533 /* 534 ** Accept the new client 535 */ 536 fd = accept(0, NULL, NULL); 537 if (fd == -1) 538 ERROR1("main: accept. errno = %d", errno); 539 540 /* 541 ** And fork, then close the fd if we are the parent. 542 */ 543 child_pid = fork(); 544 } while (child_pid && (close(fd), 1)); 545 546 /* 547 ** We are now in child, the parent has returned to "do" above. 548 */ 549 if (dup2(fd, 0) == -1) 550 ERROR("main: dup2: failed fd 0"); 551 552 if (dup2(fd, 1) == -1) 553 ERROR("main: dup2: failed fd 1"); 554 555 if (dup2(fd, 2) == -1) 556 ERROR("main: dup2: failed fd 2"); 557 } 558 559 /* 560 ** Get foreign internet address 561 */ 562 len = sizeof(sin); 563 if (getpeername(0, (struct sockaddr *) &sin, &len) == -1) 564 { 565 /* 566 ** A user has tried to start us from the command line or 567 ** the network link died, in which case this message won't 568 ** reach to other end anyway, so lets give the poor user some 569 ** errors. 570 */ 571 perror("in.identd: getpeername()"); 572 exit(1); 573 } 574 575 faddr = sin.sin_addr; 576 577 578 /* 579 ** Open the connection to the Syslog daemon if requested 580 */ 581 if (syslog_flag) 582 { 583 #ifdef LOG_DAEMON 584 openlog("identd", LOG_PID, syslog_facility); 585 #else 586 openlog("identd", LOG_PID); 587 #endif 588 589 syslog(LOG_INFO, "Connection from %s", gethost(&faddr)); 590 } 591 592 593 /* 594 ** Get local internet address 595 */ 596 len = sizeof(sin); 597 #ifdef ATTSVR4 598 if (t_getsockname(0, (struct sockaddr *) &sin, &len) == -1) 599 #else 600 if (getsockname(0, (struct sockaddr *) &sin, &len) == -1) 601 #endif 602 { 603 /* 604 ** We can just die here, because if this fails then the 605 ** network has died and we haven't got anyone to return 606 ** errors to. 607 */ 608 exit(1); 609 } 610 laddr = sin.sin_addr; 611 612 613 /* 614 ** Get the local/foreign port pair from the luser 615 */ 616 parse(stdin, &laddr, &faddr); 617 618 exit(0); 619 } 620
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