1 /* 2 * bootpgw.c - BOOTP GateWay 3 * This program forwards BOOTP Request packets to a BOOTP server. 4 */ 5 6 /************************************************************************ 7 Copyright 1988, 1991 by Carnegie Mellon University 8 9 All Rights Reserved 10 11 Permission to use, copy, modify, and distribute this software and its 12 documentation for any purpose and without fee is hereby granted, provided 13 that the above copyright notice appear in all copies and that both that 14 copyright notice and this permission notice appear in supporting 15 documentation, and that the name of Carnegie Mellon University not be used 16 in advertising or publicity pertaining to distribution of the software 17 without specific, written prior permission. 18 19 CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS 20 SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. 21 IN NO EVENT SHALL CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL 22 DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 23 PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 24 ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 25 SOFTWARE. 26 ************************************************************************/ 27 28 /* $FreeBSD: src/libexec/bootpd/bootpgw/bootpgw.c,v 1.6 2003/02/05 13:45:25 charnier Exp $ */ 29 /* $DragonFly: src/libexec/bootpd/bootpgw/bootpgw.c,v 1.2 2003/06/17 04:27:07 dillon Exp $ */ 30 31 /* 32 * BOOTPGW is typically used to forward BOOTP client requests from 33 * one subnet to a BOOTP server on a different subnet. 34 */ 35 36 #include <sys/types.h> 37 #include <sys/param.h> 38 #include <sys/socket.h> 39 #include <sys/ioctl.h> 40 #include <sys/file.h> 41 #include <sys/time.h> 42 #include <sys/stat.h> 43 #include <sys/utsname.h> 44 45 #include <net/if.h> 46 #include <netinet/in.h> 47 #include <arpa/inet.h> /* inet_ntoa */ 48 49 #ifndef NO_UNISTD 50 #include <unistd.h> 51 #endif 52 53 #include <err.h> 54 #include <stdlib.h> 55 #include <signal.h> 56 #include <stdio.h> 57 #include <string.h> 58 #include <errno.h> 59 #include <ctype.h> 60 #include <netdb.h> 61 #include <paths.h> 62 #include <syslog.h> 63 #include <assert.h> 64 65 #ifdef NO_SETSID 66 # include <fcntl.h> /* for O_RDONLY, etc */ 67 #endif 68 69 #ifndef USE_BFUNCS 70 # include <memory.h> 71 /* Yes, memcpy is OK here (no overlapped copies). */ 72 # define bcopy(a,b,c) memcpy(b,a,c) 73 # define bzero(p,l) memset(p,0,l) 74 # define bcmp(a,b,c) memcmp(a,b,c) 75 #endif 76 77 #include "bootp.h" 78 #include "getif.h" 79 #include "hwaddr.h" 80 #include "report.h" 81 #include "patchlevel.h" 82 83 /* Local definitions: */ 84 #define MAX_MSG_SIZE (3*512) /* Maximum packet size */ 85 #define TRUE 1 86 #define FALSE 0 87 #define get_network_errmsg get_errmsg 88 89 90 91 /* 92 * Externals, forward declarations, and global variables 93 */ 94 95 static void usage(void); 96 static void handle_reply(void); 97 static void handle_request(void); 98 99 /* 100 * IP port numbers for client and server obtained from /etc/services 101 */ 102 103 u_short bootps_port, bootpc_port; 104 105 106 /* 107 * Internet socket and interface config structures 108 */ 109 110 struct sockaddr_in bind_addr; /* Listening */ 111 struct sockaddr_in recv_addr; /* Packet source */ 112 struct sockaddr_in send_addr; /* destination */ 113 114 115 /* 116 * option defaults 117 */ 118 int debug = 0; /* Debugging flag (level) */ 119 struct timeval actualtimeout = 120 { /* fifteen minutes */ 121 15 * 60L, /* tv_sec */ 122 0 /* tv_usec */ 123 }; 124 u_char maxhops = 4; /* Number of hops allowed for requests. */ 125 u_int minwait = 3; /* Number of seconds client must wait before 126 its bootrequest packets are forwarded. */ 127 128 /* 129 * General 130 */ 131 132 int s; /* Socket file descriptor */ 133 char *pktbuf; /* Receive packet buffer */ 134 int pktlen; 135 char *progname; 136 char *servername; 137 int32 server_ipa; /* Real server IP address, network order. */ 138 139 struct in_addr my_ip_addr; 140 141 struct utsname my_uname; 142 char *hostname; 143 144 145 146 147 148 /* 149 * Initialization such as command-line processing is done and then the 150 * main server loop is started. 151 */ 152 153 int 154 main(int argc, char **argv) 155 { 156 struct timeval *timeout; 157 struct bootp *bp; 158 struct servent *servp; 159 struct hostent *hep; 160 char *stmp; 161 int n, ba_len, ra_len; 162 int nfound, readfds; 163 int standalone; 164 165 progname = strrchr(argv[0], '/'); 166 if (progname) progname++; 167 else progname = argv[0]; 168 169 /* 170 * Initialize logging. 171 */ 172 report_init(0); /* uses progname */ 173 174 /* 175 * Log startup 176 */ 177 report(LOG_INFO, "version %s.%d", VERSION, PATCHLEVEL); 178 179 /* Debugging for compilers with struct padding. */ 180 assert(sizeof(struct bootp) == BP_MINPKTSZ); 181 182 /* Get space for receiving packets and composing replies. */ 183 pktbuf = malloc(MAX_MSG_SIZE); 184 if (!pktbuf) { 185 report(LOG_ERR, "malloc failed"); 186 exit(1); 187 } 188 bp = (struct bootp *) pktbuf; 189 190 /* 191 * Check to see if a socket was passed to us from inetd. 192 * 193 * Use getsockname() to determine if descriptor 0 is indeed a socket 194 * (and thus we are probably a child of inetd) or if it is instead 195 * something else and we are running standalone. 196 */ 197 s = 0; 198 ba_len = sizeof(bind_addr); 199 bzero((char *) &bind_addr, ba_len); 200 errno = 0; 201 standalone = TRUE; 202 if (getsockname(s, (struct sockaddr *) &bind_addr, &ba_len) == 0) { 203 /* 204 * Descriptor 0 is a socket. Assume we are a child of inetd. 205 */ 206 if (bind_addr.sin_family == AF_INET) { 207 standalone = FALSE; 208 bootps_port = ntohs(bind_addr.sin_port); 209 } else { 210 /* Some other type of socket? */ 211 report(LOG_INFO, "getsockname: not an INET socket"); 212 } 213 } 214 /* 215 * Set defaults that might be changed by option switches. 216 */ 217 stmp = NULL; 218 timeout = &actualtimeout; 219 220 if (uname(&my_uname) < 0) 221 errx(1, "can't get hostname"); 222 hostname = my_uname.nodename; 223 224 hep = gethostbyname(hostname); 225 if (!hep) { 226 printf("Can not get my IP address\n"); 227 exit(1); 228 } 229 bcopy(hep->h_addr, (char *)&my_ip_addr, sizeof(my_ip_addr)); 230 231 /* 232 * Read switches. 233 */ 234 for (argc--, argv++; argc > 0; argc--, argv++) { 235 if (argv[0][0] != '-') 236 break; 237 switch (argv[0][1]) { 238 239 case 'd': /* debug level */ 240 if (argv[0][2]) { 241 stmp = &(argv[0][2]); 242 } else if (argv[1] && argv[1][0] == '-') { 243 /* 244 * Backwards-compatible behavior: 245 * no parameter, so just increment the debug flag. 246 */ 247 debug++; 248 break; 249 } else { 250 argc--; 251 argv++; 252 stmp = argv[0]; 253 } 254 if (!stmp || (sscanf(stmp, "%d", &n) != 1) || (n < 0)) { 255 warnx("invalid debug level"); 256 break; 257 } 258 debug = n; 259 break; 260 261 case 'h': /* hop count limit */ 262 if (argv[0][2]) { 263 stmp = &(argv[0][2]); 264 } else { 265 argc--; 266 argv++; 267 stmp = argv[0]; 268 } 269 if (!stmp || (sscanf(stmp, "%d", &n) != 1) || 270 (n < 0) || (n > 16)) 271 { 272 warnx("invalid hop count limit"); 273 break; 274 } 275 maxhops = (u_char)n; 276 break; 277 278 case 'i': /* inetd mode */ 279 standalone = FALSE; 280 break; 281 282 case 's': /* standalone mode */ 283 standalone = TRUE; 284 break; 285 286 case 't': /* timeout */ 287 if (argv[0][2]) { 288 stmp = &(argv[0][2]); 289 } else { 290 argc--; 291 argv++; 292 stmp = argv[0]; 293 } 294 if (!stmp || (sscanf(stmp, "%d", &n) != 1) || (n < 0)) { 295 warnx("invalid timeout specification"); 296 break; 297 } 298 actualtimeout.tv_sec = (int32) (60 * n); 299 /* 300 * If the actual timeout is zero, pass a NULL pointer 301 * to select so it blocks indefinitely, otherwise, 302 * point to the actual timeout value. 303 */ 304 timeout = (n > 0) ? &actualtimeout : NULL; 305 break; 306 307 case 'w': /* wait time */ 308 if (argv[0][2]) { 309 stmp = &(argv[0][2]); 310 } else { 311 argc--; 312 argv++; 313 stmp = argv[0]; 314 } 315 if (!stmp || (sscanf(stmp, "%d", &n) != 1) || 316 (n < 0) || (n > 60)) 317 { 318 warnx("invalid wait time"); 319 break; 320 } 321 minwait = (u_int)n; 322 break; 323 324 default: 325 warnx("unknown switch: -%c", argv[0][1]); 326 usage(); 327 break; 328 329 } /* switch */ 330 } /* for args */ 331 332 /* Make sure server name argument is suplied. */ 333 servername = argv[0]; 334 if (!servername) { 335 warnx("missing server name"); 336 usage(); 337 } 338 /* 339 * Get address of real bootp server. 340 */ 341 if (isdigit(servername[0])) 342 server_ipa = inet_addr(servername); 343 else { 344 hep = gethostbyname(servername); 345 if (!hep) 346 errx(1, "can't get addr for %s", servername); 347 bcopy(hep->h_addr, (char *)&server_ipa, sizeof(server_ipa)); 348 } 349 350 if (standalone) { 351 /* 352 * Go into background and disassociate from controlling terminal. 353 * XXX - This is not the POSIX way (Should use setsid). -gwr 354 */ 355 if (debug < 3) { 356 if (fork()) 357 exit(0); 358 #ifdef NO_SETSID 359 setpgrp(0,0); 360 #ifdef TIOCNOTTY 361 n = open(_PATH_TTY, O_RDWR); 362 if (n >= 0) { 363 ioctl(n, TIOCNOTTY, NULL); 364 (void) close(n); 365 } 366 #endif /* TIOCNOTTY */ 367 #else /* SETSID */ 368 if (setsid() < 0) 369 perror("setsid"); 370 #endif /* SETSID */ 371 } /* if debug < 3 */ 372 /* 373 * Nuke any timeout value 374 */ 375 timeout = NULL; 376 377 /* 378 * Here, bootpd would do: 379 * chdir 380 * tzone_init 381 * rdtab_init 382 * readtab 383 */ 384 385 /* 386 * Create a socket. 387 */ 388 if ((s = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 389 report(LOG_ERR, "socket: %s", get_network_errmsg()); 390 exit(1); 391 } 392 /* 393 * Get server's listening port number 394 */ 395 servp = getservbyname("bootps", "udp"); 396 if (servp) { 397 bootps_port = ntohs((u_short) servp->s_port); 398 } else { 399 bootps_port = (u_short) IPPORT_BOOTPS; 400 report(LOG_ERR, 401 "bootps/udp: unknown service -- using port %d", 402 bootps_port); 403 } 404 405 /* 406 * Bind socket to BOOTPS port. 407 */ 408 bind_addr.sin_family = AF_INET; 409 bind_addr.sin_port = htons(bootps_port); 410 bind_addr.sin_addr.s_addr = INADDR_ANY; 411 if (bind(s, (struct sockaddr *) &bind_addr, 412 sizeof(bind_addr)) < 0) 413 { 414 report(LOG_ERR, "bind: %s", get_network_errmsg()); 415 exit(1); 416 } 417 } /* if standalone */ 418 /* 419 * Get destination port number so we can reply to client 420 */ 421 servp = getservbyname("bootpc", "udp"); 422 if (servp) { 423 bootpc_port = ntohs(servp->s_port); 424 } else { 425 report(LOG_ERR, 426 "bootpc/udp: unknown service -- using port %d", 427 IPPORT_BOOTPC); 428 bootpc_port = (u_short) IPPORT_BOOTPC; 429 } 430 431 /* no signal catchers */ 432 433 /* 434 * Process incoming requests. 435 */ 436 for (;;) { 437 struct timeval tv; 438 439 readfds = 1 << s; 440 if (timeout) 441 tv = *timeout; 442 443 nfound = select(s + 1, (fd_set *)&readfds, NULL, NULL, 444 (timeout) ? &tv : NULL); 445 if (nfound < 0) { 446 if (errno != EINTR) { 447 report(LOG_ERR, "select: %s", get_errmsg()); 448 } 449 continue; 450 } 451 if (!(readfds & (1 << s))) { 452 report(LOG_INFO, "exiting after %ld minutes of inactivity", 453 actualtimeout.tv_sec / 60); 454 exit(0); 455 } 456 ra_len = sizeof(recv_addr); 457 n = recvfrom(s, pktbuf, MAX_MSG_SIZE, 0, 458 (struct sockaddr *) &recv_addr, &ra_len); 459 if (n <= 0) { 460 continue; 461 } 462 if (debug > 3) { 463 report(LOG_INFO, "recvd pkt from IP addr %s", 464 inet_ntoa(recv_addr.sin_addr)); 465 } 466 if (n < sizeof(struct bootp)) { 467 if (debug) { 468 report(LOG_INFO, "received short packet"); 469 } 470 continue; 471 } 472 pktlen = n; 473 474 switch (bp->bp_op) { 475 case BOOTREQUEST: 476 handle_request(); 477 break; 478 case BOOTREPLY: 479 handle_reply(); 480 break; 481 } 482 } 483 return 0; 484 } 485 486 487 488 489 /* 490 * Print "usage" message and exit 491 */ 492 493 static void 494 usage(void) 495 { 496 fprintf(stderr, 497 "usage: bootpgw [-d level] [-i] [-s] [-t timeout] server\n"); 498 fprintf(stderr, "\t -d n\tset debug level\n"); 499 fprintf(stderr, "\t -h n\tset max hop count\n"); 500 fprintf(stderr, "\t -i\tforce inetd mode (run as child of inetd)\n"); 501 fprintf(stderr, "\t -s\tforce standalone mode (run without inetd)\n"); 502 fprintf(stderr, "\t -t n\tset inetd exit timeout to n minutes\n"); 503 fprintf(stderr, "\t -w n\tset min wait time (secs)\n"); 504 exit(1); 505 } 506 507 508 509 /* 510 * Process BOOTREQUEST packet. 511 * 512 * Note, this just forwards the request to a real server. 513 */ 514 static void 515 handle_request(void) 516 { 517 struct bootp *bp = (struct bootp *) pktbuf; 518 u_short secs; 519 u_char hops; 520 521 /* XXX - SLIP init: Set bp_ciaddr = recv_addr here? */ 522 523 if (debug) { 524 report(LOG_INFO, "request from %s", 525 inet_ntoa(recv_addr.sin_addr)); 526 } 527 /* Has the client been waiting long enough? */ 528 secs = ntohs(bp->bp_secs); 529 if (secs < minwait) 530 return; 531 532 /* Has this packet hopped too many times? */ 533 hops = bp->bp_hops; 534 if (++hops > maxhops) { 535 report(LOG_NOTICE, "reqest from %s reached hop limit", 536 inet_ntoa(recv_addr.sin_addr)); 537 return; 538 } 539 bp->bp_hops = hops; 540 541 /* 542 * Here one might discard a request from the same subnet as the 543 * real server, but we can assume that the real server will send 544 * a reply to the client before it waits for minwait seconds. 545 */ 546 547 /* If gateway address is not set, put in local interface addr. */ 548 if (bp->bp_giaddr.s_addr == 0) { 549 #if 0 /* BUG */ 550 struct sockaddr_in *sip; 551 struct ifreq *ifr; 552 /* 553 * XXX - This picks the wrong interface when the receive addr 554 * is the broadcast address. There is no portable way to 555 * find out which interface a broadcast was received on. -gwr 556 * (Thanks to <walker@zk3.dec.com> for finding this bug!) 557 */ 558 ifr = getif(s, &recv_addr.sin_addr); 559 if (!ifr) { 560 report(LOG_NOTICE, "no interface for request from %s", 561 inet_ntoa(recv_addr.sin_addr)); 562 return; 563 } 564 sip = (struct sockaddr_in *) &(ifr->ifr_addr); 565 bp->bp_giaddr = sip->sin_addr; 566 #else /* BUG */ 567 /* 568 * XXX - Just set "giaddr" to our "official" IP address. 569 * RFC 1532 says giaddr MUST be set to the address of the 570 * interface on which the request was received. Setting 571 * it to our "default" IP address is not strictly correct, 572 * but is good enough to allow the real BOOTP server to 573 * get the reply back here. Then, before we forward the 574 * reply to the client, the giaddr field is corrected. 575 * (In case the client uses giaddr, which it should not.) 576 * See handle_reply() 577 */ 578 bp->bp_giaddr = my_ip_addr; 579 #endif /* BUG */ 580 581 /* 582 * XXX - DHCP says to insert a subnet mask option into the 583 * options area of the request (if vendor magic == std). 584 */ 585 } 586 /* Set up socket address for send. */ 587 send_addr.sin_family = AF_INET; 588 send_addr.sin_port = htons(bootps_port); 589 send_addr.sin_addr.s_addr = server_ipa; 590 591 /* Send reply with same size packet as request used. */ 592 if (sendto(s, pktbuf, pktlen, 0, 593 (struct sockaddr *) &send_addr, 594 sizeof(send_addr)) < 0) 595 { 596 report(LOG_ERR, "sendto: %s", get_network_errmsg()); 597 } 598 } 599 600 601 602 /* 603 * Process BOOTREPLY packet. 604 */ 605 static void 606 handle_reply(void) 607 { 608 struct bootp *bp = (struct bootp *) pktbuf; 609 struct ifreq *ifr; 610 struct sockaddr_in *sip; 611 unsigned char *ha; 612 int len, haf; 613 614 if (debug) { 615 report(LOG_INFO, " reply for %s", 616 inet_ntoa(bp->bp_yiaddr)); 617 } 618 /* Make sure client is directly accessible. */ 619 ifr = getif(s, &(bp->bp_yiaddr)); 620 if (!ifr) { 621 report(LOG_NOTICE, "no interface for reply to %s", 622 inet_ntoa(bp->bp_yiaddr)); 623 return; 624 } 625 #if 1 /* Experimental (see BUG above) */ 626 /* #ifdef CATER_TO_OLD_CLIENTS ? */ 627 /* 628 * The giaddr field has been set to our "default" IP address 629 * which might not be on the same interface as the client. 630 * In case the client looks at giaddr, (which it should not) 631 * giaddr is now set to the address of the correct interface. 632 */ 633 sip = (struct sockaddr_in *) &(ifr->ifr_addr); 634 bp->bp_giaddr = sip->sin_addr; 635 #endif 636 637 /* Set up socket address for send to client. */ 638 send_addr.sin_family = AF_INET; 639 send_addr.sin_addr = bp->bp_yiaddr; 640 send_addr.sin_port = htons(bootpc_port); 641 642 /* Create an ARP cache entry for the client. */ 643 ha = bp->bp_chaddr; 644 len = bp->bp_hlen; 645 if (len > MAXHADDRLEN) 646 len = MAXHADDRLEN; 647 haf = (int) bp->bp_htype; 648 if (haf == 0) 649 haf = HTYPE_ETHERNET; 650 651 if (debug > 1) 652 report(LOG_INFO, "setarp %s - %s", 653 inet_ntoa(bp->bp_yiaddr), haddrtoa(ha, len)); 654 setarp(s, &bp->bp_yiaddr, haf, ha, len); 655 656 /* Send reply with same size packet as request used. */ 657 if (sendto(s, pktbuf, pktlen, 0, 658 (struct sockaddr *) &send_addr, 659 sizeof(send_addr)) < 0) 660 { 661 report(LOG_ERR, "sendto: %s", get_network_errmsg()); 662 } 663 } 664 665 /* 666 * Local Variables: 667 * tab-width: 4 668 * c-indent-level: 4 669 * c-argdecl-indent: 4 670 * c-continued-statement-offset: 4 671 * c-continued-brace-offset: -4 672 * c-label-offset: -4 673 * c-brace-offset: 0 674 * End: 675 */ 676