1/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */ 2/* 3 * Copyright (c) 1994, 1995, 1996, 1997, 1998 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by the Computer Systems 17 * Engineering Group at Lawrence Berkeley Laboratory. 18 * 4. Neither the name of the University nor of the Laboratory may be used 19 * to endorse or promote products derived from this software without 20 * specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35#ifndef lint 36static const char rcsid[] _U_ = 37 "@(#) $Header: /tcpdump/master/libpcap/inet.c,v 1.66.2.2 2006/01/21 10:46:13 guy Exp $ (LBL)"; 38#endif 39 40#ifdef HAVE_CONFIG_H 41#include "config.h" 42#endif 43 44#ifdef WIN32 45#include <pcap-stdinc.h> 46#else /* WIN32 */ 47 48#include <sys/param.h> 49#ifndef MSDOS 50//#include <sys/file.h> 51#endif 52#include <sys/ioctl.h> 53#include <sys/socket.h> 54#ifdef HAVE_SYS_SOCKIO_H 55#include <sys/sockio.h> 56#endif 57 58struct mbuf; /* Squelch compiler warnings on some platforms for */ 59struct rtentry; /* declarations in <net/if.h> */ 60#include <net/if.h> 61#include <netinet/in.h> 62#endif /* WIN32 */ 63 64#include <ctype.h> 65#include <errno.h> 66#include <memory.h> 67#include <stdio.h> 68#include <stdlib.h> 69#include <string.h> 70#if !defined(WIN32) && !defined(__BORLANDC__) 71#include <unistd.h> 72#endif /* !WIN32 && !__BORLANDC__ */ 73#ifdef HAVE_LIMITS_H 74#include <limits.h> 75#else 76#define INT_MAX 2147483647 77#endif 78 79#include "pcap-int.h" 80 81#ifdef HAVE_OS_PROTO_H 82#include "os-proto.h" 83#endif 84 85/* Not all systems have IFF_LOOPBACK */ 86#ifdef IFF_LOOPBACK 87#define ISLOOPBACK(name, flags) ((flags) & IFF_LOOPBACK) 88#else 89#define ISLOOPBACK(name, flags) ((name)[0] == 'l' && (name)[1] == 'o' && \ 90 (isdigit((unsigned char)((name)[2])) || (name)[2] == '\0')) 91#endif 92 93struct sockaddr * 94dup_sockaddr(struct sockaddr *sa, size_t sa_length) 95{ 96 struct sockaddr *newsa; 97 98 if ((newsa = malloc(sa_length)) == NULL) 99 return (NULL); 100 return (memcpy(newsa, sa, sa_length)); 101} 102 103static int 104get_instance(const char *name) 105{ 106 const char *cp, *endcp; 107 int n; 108 109 if (strcmp(name, "any") == 0) { 110 /* 111 * Give the "any" device an artificially high instance 112 * number, so it shows up after all other non-loopback 113 * interfaces. 114 */ 115 return INT_MAX; 116 } 117 118 endcp = name + strlen(name); 119 for (cp = name; cp < endcp && !isdigit((unsigned char)*cp); ++cp) 120 continue; 121 122 if (isdigit((unsigned char)*cp)) 123 n = atoi(cp); 124 else 125 n = 0; 126 return (n); 127} 128 129int 130add_or_find_if(pcap_if_t **curdev_ret, pcap_if_t **alldevs, const char *name, 131 u_int flags, const char *description, char *errbuf) 132{ 133 pcap_t *p; 134 pcap_if_t *curdev, *prevdev, *nextdev; 135 int this_instance; 136 137 /* 138 * Can we open this interface for live capture? 139 * 140 * We do this check so that interfaces that ae supplied 141 * by the interface enumeration mechanism we're using 142 * but that don't support packet capture aren't included 143 * in the list. An example of this is loopback interfaces 144 * on Solaris; we don't just omit loopback interfaces 145 * becaue you *can* capture on loopback interfaces on some 146 * OSes. 147 */ 148 p = pcap_open_live(name, 68, 0, 0, errbuf); 149 if (p == NULL) { 150 /* 151 * No. Don't bother including it. 152 * Don't treat this as an error, though. 153 */ 154 *curdev_ret = NULL; 155 return (0); 156 } 157 pcap_close(p); 158 159 /* 160 * Is there already an entry in the list for this interface? 161 */ 162 for (curdev = *alldevs; curdev != NULL; curdev = curdev->next) { 163 if (strcmp(name, curdev->name) == 0) 164 break; /* yes, we found it */ 165 } 166 if (curdev == NULL) { 167 /* 168 * No, we didn't find it. 169 * Allocate a new entry. 170 */ 171 curdev = malloc(sizeof(pcap_if_t)); 172 if (curdev == NULL) { 173 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 174 "malloc: %s", pcap_strerror(errno)); 175 return (-1); 176 } 177 178 /* 179 * Fill in the entry. 180 */ 181 curdev->next = NULL; 182 curdev->name = strdup(name); 183 if (curdev->name == NULL) { 184 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 185 "malloc: %s", pcap_strerror(errno)); 186 free(curdev); 187 return (-1); 188 } 189 if (description != NULL) { 190 /* 191 * We have a description for this interface. 192 */ 193 curdev->description = strdup(description); 194 if (curdev->description == NULL) { 195 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 196 "malloc: %s", pcap_strerror(errno)); 197 free(curdev->name); 198 free(curdev); 199 return (-1); 200 } 201 } else { 202 /* 203 * We don't. 204 */ 205 curdev->description = NULL; 206 } 207 curdev->addresses = NULL; /* list starts out as empty */ 208 curdev->flags = 0; 209 if (ISLOOPBACK(name, flags)) 210 curdev->flags |= PCAP_IF_LOOPBACK; 211 212 /* 213 * Add it to the list, in the appropriate location. 214 * First, get the instance number of this interface. 215 */ 216 this_instance = get_instance(name); 217 218 /* 219 * Now look for the last interface with an instance number 220 * less than or equal to the new interface's instance 221 * number - except that non-loopback interfaces are 222 * arbitrarily treated as having interface numbers less 223 * than those of loopback interfaces, so the loopback 224 * interfaces are put at the end of the list. 225 * 226 * We start with "prevdev" being NULL, meaning we're before 227 * the first element in the list. 228 */ 229 prevdev = NULL; 230 for (;;) { 231 /* 232 * Get the interface after this one. 233 */ 234 if (prevdev == NULL) { 235 /* 236 * The next element is the first element. 237 */ 238 nextdev = *alldevs; 239 } else 240 nextdev = prevdev->next; 241 242 /* 243 * Are we at the end of the list? 244 */ 245 if (nextdev == NULL) { 246 /* 247 * Yes - we have to put the new entry 248 * after "prevdev". 249 */ 250 break; 251 } 252 253 /* 254 * Is the new interface a non-loopback interface 255 * and the next interface a loopback interface? 256 */ 257 if (!(curdev->flags & PCAP_IF_LOOPBACK) && 258 (nextdev->flags & PCAP_IF_LOOPBACK)) { 259 /* 260 * Yes, we should put the new entry 261 * before "nextdev", i.e. after "prevdev". 262 */ 263 break; 264 } 265 266 /* 267 * Is the new interface's instance number less 268 * than the next interface's instance number, 269 * and is it the case that the new interface is a 270 * non-loopback interface or the next interface is 271 * a loopback interface? 272 * 273 * (The goal of both loopback tests is to make 274 * sure that we never put a loopback interface 275 * before any non-loopback interface and that we 276 * always put a non-loopback interface before all 277 * loopback interfaces.) 278 */ 279 if (this_instance < get_instance(nextdev->name) && 280 (!(curdev->flags & PCAP_IF_LOOPBACK) || 281 (nextdev->flags & PCAP_IF_LOOPBACK))) { 282 /* 283 * Yes - we should put the new entry 284 * before "nextdev", i.e. after "prevdev". 285 */ 286 break; 287 } 288 289 prevdev = nextdev; 290 } 291 292 /* 293 * Insert before "nextdev". 294 */ 295 curdev->next = nextdev; 296 297 /* 298 * Insert after "prevdev" - unless "prevdev" is null, 299 * in which case this is the first interface. 300 */ 301 if (prevdev == NULL) { 302 /* 303 * This is the first interface. Pass back a 304 * pointer to it, and put "curdev" before 305 * "nextdev". 306 */ 307 *alldevs = curdev; 308 } else 309 prevdev->next = curdev; 310 } 311 312 *curdev_ret = curdev; 313 return (0); 314} 315 316int 317add_addr_to_iflist(pcap_if_t **alldevs, const char *name, u_int flags, 318 struct sockaddr *addr, size_t addr_size, 319 struct sockaddr *netmask, size_t netmask_size, 320 struct sockaddr *broadaddr, size_t broadaddr_size, 321 struct sockaddr *dstaddr, size_t dstaddr_size, 322 char *errbuf) 323{ 324 pcap_if_t *curdev; 325 pcap_addr_t *curaddr, *prevaddr, *nextaddr; 326 327 if (add_or_find_if(&curdev, alldevs, name, flags, NULL, errbuf) == -1) { 328 /* 329 * Error - give up. 330 */ 331 return (-1); 332 } 333 if (curdev == NULL) { 334 /* 335 * Device wasn't added because it can't be opened. 336 * Not a fatal error. 337 */ 338 return (0); 339 } 340 341 /* 342 * "curdev" is an entry for this interface; add an entry for this 343 * address to its list of addresses. 344 * 345 * Allocate the new entry and fill it in. 346 */ 347 curaddr = malloc(sizeof(pcap_addr_t)); 348 if (curaddr == NULL) { 349 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 350 "malloc: %s", pcap_strerror(errno)); 351 return (-1); 352 } 353 354 curaddr->next = NULL; 355 if (addr != NULL) { 356 curaddr->addr = dup_sockaddr(addr, addr_size); 357 if (curaddr->addr == NULL) { 358 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 359 "malloc: %s", pcap_strerror(errno)); 360 free(curaddr); 361 return (-1); 362 } 363 } else 364 curaddr->addr = NULL; 365 366 if (netmask != NULL) { 367 curaddr->netmask = dup_sockaddr(netmask, netmask_size); 368 if (curaddr->netmask == NULL) { 369 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 370 "malloc: %s", pcap_strerror(errno)); 371 if (curaddr->addr != NULL) 372 free(curaddr->addr); 373 free(curaddr); 374 return (-1); 375 } 376 } else 377 curaddr->netmask = NULL; 378 379 if (broadaddr != NULL) { 380 curaddr->broadaddr = dup_sockaddr(broadaddr, broadaddr_size); 381 if (curaddr->broadaddr == NULL) { 382 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 383 "malloc: %s", pcap_strerror(errno)); 384 if (curaddr->netmask != NULL) 385 free(curaddr->netmask); 386 if (curaddr->addr != NULL) 387 free(curaddr->addr); 388 free(curaddr); 389 return (-1); 390 } 391 } else 392 curaddr->broadaddr = NULL; 393 394 if (dstaddr != NULL) { 395 curaddr->dstaddr = dup_sockaddr(dstaddr, dstaddr_size); 396 if (curaddr->dstaddr == NULL) { 397 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 398 "malloc: %s", pcap_strerror(errno)); 399 if (curaddr->broadaddr != NULL) 400 free(curaddr->broadaddr); 401 if (curaddr->netmask != NULL) 402 free(curaddr->netmask); 403 if (curaddr->addr != NULL) 404 free(curaddr->addr); 405 free(curaddr); 406 return (-1); 407 } 408 } else 409 curaddr->dstaddr = NULL; 410 411 /* 412 * Find the end of the list of addresses. 413 */ 414 for (prevaddr = curdev->addresses; prevaddr != NULL; prevaddr = nextaddr) { 415 nextaddr = prevaddr->next; 416 if (nextaddr == NULL) { 417 /* 418 * This is the end of the list. 419 */ 420 break; 421 } 422 } 423 424 if (prevaddr == NULL) { 425 /* 426 * The list was empty; this is the first member. 427 */ 428 curdev->addresses = curaddr; 429 } else { 430 /* 431 * "prevaddr" is the last member of the list; append 432 * this member to it. 433 */ 434 prevaddr->next = curaddr; 435 } 436 437 return (0); 438} 439 440int 441pcap_add_if(pcap_if_t **devlist, const char *name, u_int flags, 442 const char *description, char *errbuf) 443{ 444 pcap_if_t *curdev; 445 446 return (add_or_find_if(&curdev, devlist, name, flags, description, 447 errbuf)); 448} 449 450 451/* 452 * Free a list of interfaces. 453 */ 454void 455pcap_freealldevs(pcap_if_t *alldevs) 456{ 457 pcap_if_t *curdev, *nextdev; 458 pcap_addr_t *curaddr, *nextaddr; 459 460 for (curdev = alldevs; curdev != NULL; curdev = nextdev) { 461 nextdev = curdev->next; 462 463 /* 464 * Free all addresses. 465 */ 466 for (curaddr = curdev->addresses; curaddr != NULL; curaddr = nextaddr) { 467 nextaddr = curaddr->next; 468 if (curaddr->addr) 469 free(curaddr->addr); 470 if (curaddr->netmask) 471 free(curaddr->netmask); 472 if (curaddr->broadaddr) 473 free(curaddr->broadaddr); 474 if (curaddr->dstaddr) 475 free(curaddr->dstaddr); 476 free(curaddr); 477 } 478 479 /* 480 * Free the name string. 481 */ 482 free(curdev->name); 483 484 /* 485 * Free the description string, if any. 486 */ 487 if (curdev->description != NULL) 488 free(curdev->description); 489 490 /* 491 * Free the interface. 492 */ 493 free(curdev); 494 } 495} 496 497#if !defined(WIN32) && !defined(MSDOS) 498 499/* 500 * Return the name of a network interface attached to the system, or NULL 501 * if none can be found. The interface must be configured up; the 502 * lowest unit number is preferred; loopback is ignored. 503 */ 504char * 505pcap_lookupdev(errbuf) 506 register char *errbuf; 507{ 508 pcap_if_t *alldevs; 509/* for old BSD systems, including bsdi3 */ 510#ifndef IF_NAMESIZE 511#define IF_NAMESIZE IFNAMSIZ 512#endif 513 static char device[IF_NAMESIZE + 1]; 514 char *ret; 515 516 if (pcap_findalldevs(&alldevs, errbuf) == -1) 517 return (NULL); 518 519 if (alldevs == NULL || (alldevs->flags & PCAP_IF_LOOPBACK)) { 520 /* 521 * There are no devices on the list, or the first device 522 * on the list is a loopback device, which means there 523 * are no non-loopback devices on the list. This means 524 * we can't return any device. 525 * 526 * XXX - why not return a loopback device? If we can't 527 * capture on it, it won't be on the list, and if it's 528 * on the list, there aren't any non-loopback devices, 529 * so why not just supply it as the default device? 530 */ 531 (void)strlcpy(errbuf, "no suitable device found", 532 PCAP_ERRBUF_SIZE); 533 ret = NULL; 534 } else { 535 /* 536 * Return the name of the first device on the list. 537 */ 538 (void)strlcpy(device, alldevs->name, sizeof(device)); 539 ret = device; 540 } 541 542 pcap_freealldevs(alldevs); 543 return (ret); 544} 545 546int 547pcap_lookupnet(device, netp, maskp, errbuf) 548 register const char *device; 549 register bpf_u_int32 *netp, *maskp; 550 register char *errbuf; 551{ 552 register int fd; 553 register struct sockaddr_in *sin; 554 struct ifreq ifr; 555 556 /* 557 * The pseudo-device "any" listens on all interfaces and therefore 558 * has the network address and -mask "0.0.0.0" therefore catching 559 * all traffic. Using NULL for the interface is the same as "any". 560 */ 561 if (!device || strcmp(device, "any") == 0 562#ifdef HAVE_DAG_API 563 || strstr(device, "dag") != NULL 564#endif 565#ifdef HAVE_SEPTEL_API 566 || strstr(device, "septel") != NULL 567#endif 568 ) { 569 *netp = *maskp = 0; 570 return 0; 571 } 572 573 fd = socket(AF_INET, SOCK_DGRAM, 0); 574 if (fd < 0) { 575 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s", 576 pcap_strerror(errno)); 577 return (-1); 578 } 579 memset(&ifr, 0, sizeof(ifr)); 580#ifdef linux 581 /* XXX Work around Linux kernel bug */ 582 ifr.ifr_addr.sa_family = AF_INET; 583#endif 584 (void)strlcpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); 585 if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) { 586 if (errno == EADDRNOTAVAIL) { 587 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 588 "%s: no IPv4 address assigned", device); 589 } else { 590 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 591 "SIOCGIFADDR: %s: %s", 592 device, pcap_strerror(errno)); 593 } 594 (void)close(fd); 595 return (-1); 596 } 597 sin = (struct sockaddr_in *)&ifr.ifr_addr; 598 *netp = sin->sin_addr.s_addr; 599 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) { 600 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 601 "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno)); 602 (void)close(fd); 603 return (-1); 604 } 605 (void)close(fd); 606 *maskp = sin->sin_addr.s_addr; 607 if (*maskp == 0) { 608 if (IN_CLASSA(*netp)) 609 *maskp = IN_CLASSA_NET; 610 else if (IN_CLASSB(*netp)) 611 *maskp = IN_CLASSB_NET; 612 else if (IN_CLASSC(*netp)) 613 *maskp = IN_CLASSC_NET; 614 else { 615 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 616 "inet class for 0x%x unknown", *netp); 617 return (-1); 618 } 619 } 620 *netp &= *maskp; 621 return (0); 622} 623 624#elif defined(WIN32) 625 626/* 627 * Return the name of a network interface attached to the system, or NULL 628 * if none can be found. The interface must be configured up; the 629 * lowest unit number is preferred; loopback is ignored. 630 */ 631char * 632pcap_lookupdev(errbuf) 633 register char *errbuf; 634{ 635 DWORD dwVersion; 636 DWORD dwWindowsMajorVersion; 637 dwVersion = GetVersion(); /* get the OS version */ 638 dwWindowsMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion))); 639 640 if (dwVersion >= 0x80000000 && dwWindowsMajorVersion >= 4) { 641 /* 642 * Windows 95, 98, ME. 643 */ 644 ULONG NameLength = 8192; 645 static char AdaptersName[8192]; 646 647 if (PacketGetAdapterNames(AdaptersName,&NameLength) ) 648 return (AdaptersName); 649 else 650 return NULL; 651 } else { 652 /* 653 * Windows NT (NT 4.0, W2K, WXP). Convert the names to UNICODE for backward compatibility 654 */ 655 ULONG NameLength = 8192; 656 static WCHAR AdaptersName[8192]; 657 char *tAstr; 658 WCHAR *tUstr; 659 WCHAR *TAdaptersName = (WCHAR*)malloc(8192 * sizeof(WCHAR)); 660 int NAdapts = 0; 661 662 if(TAdaptersName == NULL) 663 { 664 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "memory allocation failure"); 665 return NULL; 666 } 667 668 if ( !PacketGetAdapterNames((PTSTR)TAdaptersName,&NameLength) ) 669 { 670 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, 671 "PacketGetAdapterNames: %s", 672 pcap_win32strerror()); 673 free(TAdaptersName); 674 return NULL; 675 } 676 677 678 tAstr = (char*)TAdaptersName; 679 tUstr = (WCHAR*)AdaptersName; 680 681 /* 682 * Convert and copy the device names 683 */ 684 while(sscanf(tAstr, "%S", tUstr) > 0) 685 { 686 tAstr += strlen(tAstr) + 1; 687 tUstr += wcslen(tUstr) + 1; 688 NAdapts ++; 689 } 690 691 tAstr++; 692 *tUstr = 0; 693 tUstr++; 694 695 /* 696 * Copy the descriptions 697 */ 698 while(NAdapts--) 699 { 700 strcpy((char*)tUstr, tAstr); 701 (char*)tUstr += strlen(tAstr) + 1;; 702 tAstr += strlen(tAstr) + 1; 703 } 704 705 free(TAdaptersName); 706 return (char *)(AdaptersName); 707 } 708} 709 710 711int 712pcap_lookupnet(device, netp, maskp, errbuf) 713 register const char *device; 714 register bpf_u_int32 *netp, *maskp; 715 register char *errbuf; 716{ 717 /* 718 * We need only the first IPv4 address, so we must scan the array returned by PacketGetNetInfo() 719 * in order to skip non IPv4 (i.e. IPv6 addresses) 720 */ 721 npf_if_addr if_addrs[MAX_NETWORK_ADDRESSES]; 722 LONG if_addr_size = 1; 723 struct sockaddr_in *t_addr; 724 unsigned int i; 725 726 if (!PacketGetNetInfoEx((void *)device, if_addrs, &if_addr_size)) { 727 *netp = *maskp = 0; 728 return (0); 729 } 730 731 for(i=0; i<MAX_NETWORK_ADDRESSES; i++) 732 { 733 if(if_addrs[i].IPAddress.ss_family == AF_INET) 734 { 735 t_addr = (struct sockaddr_in *) &(if_addrs[i].IPAddress); 736 *netp = t_addr->sin_addr.S_un.S_addr; 737 t_addr = (struct sockaddr_in *) &(if_addrs[i].SubnetMask); 738 *maskp = t_addr->sin_addr.S_un.S_addr; 739 740 *netp &= *maskp; 741 return (0); 742 } 743 744 } 745 746 *netp = *maskp = 0; 747 return (0); 748} 749 750#endif /* !WIN32 && !MSDOS */ 751