The Tcpdump Group git mirrors - libpcap/blob - savefile.c

   1 /*
   2  * Copyright (c) 1993, 1994, 1995, 1996, 1997
   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: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  *
  21  * savefile.c - supports offline use of tcpdump
  22  *      Extraction/creation by Jeffrey Mogul, DECWRL
  23  *      Modified by Steve McCanne, LBL.
  24  *
  25  * Used to save the received packet headers, after filtering, to
  26  * a file, and then read them later.
  27  * The first record in the file contains saved values for the machine
  28  * dependent values so we can print the dump file on any architecture.
  29  */
  30
  31 #ifndef lint
  32 static const char rcsid[] =
  33     "@(#) $Header: /tcpdump/master/libpcap/savefile.c,v 1.64 2002-07-11 09:06:46 guy Exp $ (LBL)";
  34 #endif
  35
  36 #ifdef HAVE_CONFIG_H
  37 #include "config.h"
  38 #endif
  39
  40 #include <errno.h>
  41 #include <memory.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45
  46 #include "pcap-int.h"
  47
  48 #ifdef HAVE_OS_PROTO_H
  49 #include "os-proto.h"
  50 #endif
  51
  52 #define TCPDUMP_MAGIC 0xa1b2c3d4
  53 #define PATCHED_TCPDUMP_MAGIC 0xa1b2cd34
  54
  55 /*
  56  * We use the "receiver-makes-right" approach to byte order,
  57  * because time is at a premium when we are writing the file.
  58  * In other words, the pcap_file_header and pcap_pkthdr,
  59  * records are written in host byte order.
  60  * Note that the packets are always written in network byte order.
  61  *
  62  * ntoh[ls] aren't sufficient because we might need to swap on a big-endian
  63  * machine (if the file was written in little-end order).
  64  */
  65 #define SWAPLONG(y) \
  66 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
  67 #define SWAPSHORT(y) \
  68         ( (((y)&0xff)<<8) | ((u_short)((y)&0xff00)>>8) )
  69
  70 #define SFERR_TRUNC             1
  71 #define SFERR_BADVERSION        2
  72 #define SFERR_BADF              3
  73 #define SFERR_EOF               4 /* not really an error, just a status */
  74
  75 /*
  76  * We don't write DLT_* values to the capture file header, because
  77  * they're not the same on all platforms.
  78  *
  79  * Unfortunately, the various flavors of BSD have not always used the same
  80  * numerical values for the same data types, and various patches to
  81  * libpcap for non-BSD OSes have added their own DLT_* codes for link
  82  * layer encapsulation types seen on those OSes, and those codes have had,
  83  * in some cases, values that were also used, on other platforms, for other
  84  * link layer encapsulation types.
  85  *
  86  * This means that capture files of a type whose numerical DLT_* code
  87  * means different things on different BSDs, or with different versions
  88  * of libpcap, can't always be read on systems other than those like
  89  * the one running on the machine on which the capture was made.
  90  *
  91  * Instead, we define here a set of LINKTYPE_* codes, and map DLT_* codes
  92  * to LINKTYPE_* codes when writing a savefile header, and map LINKTYPE_*
  93  * codes to DLT_* codes when reading a savefile header.
  94  *
  95  * For those DLT_* codes that have, as far as we know, the same values on
  96  * all platforms (DLT_NULL through DLT_FDDI), we define LINKTYPE_xxx as
  97  * DLT_xxx; that way, captures of those types can still be read by
  98  * versions of libpcap that map LINKTYPE_* values to DLT_* values, and
  99  * captures of those types written by versions of libpcap that map DLT_
 100  * values to LINKTYPE_ values can still be read by older versions
 101  * of libpcap.
 102  *
 103  * The other LINKTYPE_* codes are given values starting at 100, in the
 104  * hopes that no DLT_* code will be given one of those values.
 105  *
 106  * In order to ensure that a given LINKTYPE_* code's value will refer to
 107  * the same encapsulation type on all platforms, you should not allocate
 108  * a new LINKTYPE_* value without consulting "tcpdump-workers@tcpdump.org".
 109  * The tcpdump developers will allocate a value for you, and will not
 110  * subsequently allocate it to anybody else; that value will be added to
 111  * the "pcap.h" in the tcpdump.org CVS repository, so that a future
 112  * libpcap release will include it.
 113  *
 114  * You should, if possible, also contribute patches to libpcap and tcpdump
 115  * to handle the new encapsulation type, so that they can also be checked
 116  * into the tcpdump.org CVS repository and so that they will appear in
 117  * future libpcap and tcpdump releases.
 118  */
 119 #define LINKTYPE_NULL           DLT_NULL
 120 #define LINKTYPE_ETHERNET       DLT_EN10MB      /* also for 100Mb and up */
 121 #define LINKTYPE_EXP_ETHERNET   DLT_EN3MB       /* 3Mb experimental Ethernet */
 122 #define LINKTYPE_AX25           DLT_AX25
 123 #define LINKTYPE_PRONET         DLT_PRONET
 124 #define LINKTYPE_CHAOS          DLT_CHAOS
 125 #define LINKTYPE_TOKEN_RING     DLT_IEEE802     /* DLT_IEEE802 is used for Token Ring */
 126 #define LINKTYPE_ARCNET         DLT_ARCNET
 127 #define LINKTYPE_SLIP           DLT_SLIP
 128 #define LINKTYPE_PPP            DLT_PPP
 129 #define LINKTYPE_FDDI           DLT_FDDI
 130
 131 /*
 132  * LINKTYPE_PPP is for use when there might, or might not, be an RFC 1662
 133  * PPP in HDLC-like framing header (with 0xff 0x03 before the PPP protocol
 134  * field) at the beginning of the packet.
 135  *
 136  * This is for use when there is always such a header; the address field
 137  * might be 0xff, for regular PPP, or it might be an address field for Cisco
 138  * point-to-point with HDLC framing as per section 4.3.1 of RFC 1547 ("Cisco
 139  * HDLC").  This is, for example, what you get with NetBSD's DLT_PPP_SERIAL.
 140  *
 141  * We give it the same value as NetBSD's DLT_PPP_SERIAL, in the hopes that
 142  * nobody else will choose a DLT_ value of 50, and so that DLT_PPP_SERIAL
 143  * captures will be written out with a link type that NetBSD's tcpdump
 144  * can read.
 145  */
 146 #define LINKTYPE_PPP_HDLC       50              /* PPP in HDLC-like framing */
 147
 148 #define LINKTYPE_PPP_ETHER      51              /* NetBSD PPP-over-Ethernet */
 149
 150 #define LINKTYPE_ATM_RFC1483    100             /* LLC/SNAP-encapsulated ATM */
 151 #define LINKTYPE_RAW            101             /* raw IP */
 152 #define LINKTYPE_SLIP_BSDOS     102             /* BSD/OS SLIP BPF header */
 153 #define LINKTYPE_PPP_BSDOS      103             /* BSD/OS PPP BPF header */
 154 #define LINKTYPE_C_HDLC         104             /* Cisco HDLC */
 155 #define LINKTYPE_IEEE802_11     105             /* IEEE 802.11 (wireless) */
 156 #define LINKTYPE_ATM_CLIP       106             /* Linux Classical IP over ATM */
 157 #define LINKTYPE_LOOP           108             /* OpenBSD loopback */
 158
 159 #define LINKTYPE_LINUX_SLL      113             /* Linux cooked socket capture */
 160 #define LINKTYPE_LTALK          114             /* Apple LocalTalk hardware */
 161 #define LINKTYPE_ECONET         115             /* Acorn Econet */
 162
 163 #define LINKTYPE_CISCO_IOS      118             /* For Cisco-internal use */
 164 #define LINKTYPE_PRISM_HEADER   119             /* 802.11+Prism II monitor mode */
 165 #define LINKTYPE_AIRONET_HEADER 120             /* FreeBSD Aironet driver stuff */
 166 #define LINKTYPE_SUNATM         123             /* Solaris+SunATM */
 167
 168 /*
 169  * These types are reserved for future use.
 170  */
 171 #define LINKTYPE_FRELAY         107             /* Frame Relay */
 172 #define LINKTYPE_ENC            109             /* OpenBSD IPSEC enc */
 173 #define LINKTYPE_LANE8023       110             /* ATM LANE + 802.3 */
 174 #define LINKTYPE_HIPPI          111             /* NetBSD HIPPI */
 175 #define LINKTYPE_HDLC           112             /* NetBSD HDLC framing */
 176 #define LINKTYPE_IPFILTER       116             /* IP Filter capture files */
 177 #define LINKTYPE_PFLOG          117             /* OpenBSD DLT_PFLOG */
 178 #define LINKTYPE_HHDLC          121             /* Siemens HiPath HDLC */
 179 #define LINKTYPE_IP_OVER_FC     122             /* RFC 2625 IP-over-Fibre Channel */
 180 #define LINKTYPE_SUNATM         123             /* Solaris+SunATM */
 181
 182 static struct linktype_map {
 183         int     dlt;
 184         int     linktype;
 185 } map[] = {
 186         /*
 187          * These DLT_* codes have LINKTYPE_* codes with values identical
 188          * to the values of the corresponding DLT_* code.
 189          */
 190         { DLT_NULL,             LINKTYPE_NULL },
 191         { DLT_EN10MB,           LINKTYPE_ETHERNET },
 192         { DLT_EN3MB,            LINKTYPE_EXP_ETHERNET },
 193         { DLT_AX25,             LINKTYPE_AX25 },
 194         { DLT_PRONET,           LINKTYPE_PRONET },
 195         { DLT_CHAOS,            LINKTYPE_CHAOS },
 196         { DLT_IEEE802,          LINKTYPE_TOKEN_RING },
 197         { DLT_ARCNET,           LINKTYPE_ARCNET },
 198         { DLT_SLIP,             LINKTYPE_SLIP },
 199         { DLT_PPP,              LINKTYPE_PPP },
 200         { DLT_FDDI,             LINKTYPE_FDDI },
 201
 202         /*
 203          * These DLT_* codes have different values on different
 204          * platforms; we map them to LINKTYPE_* codes that
 205          * have values that should never be equal to any DLT_*
 206          * code.
 207          */
 208 #ifdef DLT_FR
 209         /* BSD/OS Frame Relay */
 210         { DLT_FR,               LINKTYPE_FRELAY },
 211 #endif
 212         { DLT_ATM_RFC1483,      LINKTYPE_ATM_RFC1483 },
 213         { DLT_RAW,              LINKTYPE_RAW },
 214         { DLT_SLIP_BSDOS,       LINKTYPE_SLIP_BSDOS },
 215         { DLT_PPP_BSDOS,        LINKTYPE_PPP_BSDOS },
 216
 217         /* BSD/OS Cisco HDLC */
 218         { DLT_C_HDLC,           LINKTYPE_C_HDLC },
 219
 220         /*
 221          * These DLT_* codes are not on all platforms, but, so far,
 222          * there don't appear to be any platforms that define
 223          * other codes with those values; we map them to
 224          * different LINKTYPE_* values anyway, just in case.
 225          */
 226
 227         /* Linux ATM Classical IP */
 228         { DLT_ATM_CLIP,         LINKTYPE_ATM_CLIP },
 229
 230         /* NetBSD sync/async serial PPP (or Cisco HDLC) */
 231         { DLT_PPP_SERIAL,       LINKTYPE_PPP_HDLC },
 232
 233         /* NetBSD PPP over Ethernet */
 234         { DLT_PPP_ETHER,        LINKTYPE_PPP_ETHER },
 235
 236         /* IEEE 802.11 wireless */
 237         { DLT_IEEE802_11,       LINKTYPE_IEEE802_11 },
 238
 239         /* Frame Relay */
 240         { DLT_FRELAY,           LINKTYPE_FRELAY },
 241
 242         /* OpenBSD loopback */
 243         { DLT_LOOP,             LINKTYPE_LOOP },
 244
 245         /* Linux cooked socket capture */
 246         { DLT_LINUX_SLL,        LINKTYPE_LINUX_SLL },
 247
 248         /* Apple LocalTalk hardware */
 249         { DLT_LTALK,            LINKTYPE_LTALK },
 250
 251         /* Acorn Econet */
 252         { DLT_ECONET,           LINKTYPE_ECONET },
 253
 254         /* For Cisco-internal use */
 255         { DLT_CISCO_IOS,        LINKTYPE_CISCO_IOS },
 256
 257         /* Prism II monitor-mode header plus 802.11 header */
 258         { DLT_PRISM_HEADER,     LINKTYPE_PRISM_HEADER },
 259
 260         /* FreeBSD Aironet driver stuff */
 261         { DLT_AIRONET_HEADER,   LINKTYPE_AIRONET_HEADER },
 262
 263         /* Siemens HiPath HDLC */
 264         { DLT_HHDLC,            LINKTYPE_HHDLC },
 265
 266         /* RFC 2625 IP-over-Fibre Channel */
 267         { DLT_IP_OVER_FC,       LINKTYPE_IP_OVER_FC },
 268
 269         /* Solaris+SunATM */
 270         { DLT_SUNATM,           LINKTYPE_SUNATM },
 271
 272         /*
 273          * Any platform that defines additional DLT_* codes should:
 274          *
 275          *      request a LINKTYPE_* code and value from tcpdump.org,
 276          *      as per the above;
 277          *
 278          *      add, in their version of libpcap, an entry to map
 279          *      those DLT_* codes to the corresponding LINKTYPE_*
 280          *      code;
 281          *
 282          *      redefine, in their "net/bpf.h", any DLT_* values
 283          *      that collide with the values used by their additional
 284          *      DLT_* codes, to remove those collisions (but without
 285          *      making them collide with any of the LINKTYPE_*
 286          *      values equal to 50 or above; they should also avoid
 287          *      defining DLT_* values that collide with those
 288          *      LINKTYPE_* values, either).
 289          */
 290         { -1,                   -1 }
 291 };
 292
 293 static int
 294 dlt_to_linktype(int dlt)
 295 {
 296         int i;
 297
 298         for (i = 0; map[i].dlt != -1; i++) {
 299                 if (map[i].dlt == dlt)
 300                         return (map[i].linktype);
 301         }
 302
 303         /*
 304          * If we don't have a mapping for this DLT_ code, return an
 305          * error; that means that the table above needs to have an
 306          * entry added.
 307          */
 308         return (-1);
 309 }
 310
 311 static int
 312 linktype_to_dlt(int linktype)
 313 {
 314         int i;
 315
 316         for (i = 0; map[i].linktype != -1; i++) {
 317                 if (map[i].linktype == linktype)
 318                         return (map[i].dlt);
 319         }
 320
 321         /*
 322          * If we don't have an entry for this link type, return
 323          * the link type value; it may be a DLT_ value from an
 324          * older version of libpcap.
 325          */
 326         return linktype;
 327 }
 328
 329 static int
 330 sf_write_header(FILE *fp, int linktype, int thiszone, int snaplen)
 331 {
 332         struct pcap_file_header hdr;
 333
 334         hdr.magic = TCPDUMP_MAGIC;
 335         hdr.version_major = PCAP_VERSION_MAJOR;
 336         hdr.version_minor = PCAP_VERSION_MINOR;
 337
 338         hdr.thiszone = thiszone;
 339         hdr.snaplen = snaplen;
 340         hdr.sigfigs = 0;
 341         hdr.linktype = linktype;
 342
 343         if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
 344                 return (-1);
 345
 346         return (0);
 347 }
 348
 349 static void
 350 swap_hdr(struct pcap_file_header *hp)
 351 {
 352         hp->version_major = SWAPSHORT(hp->version_major);
 353         hp->version_minor = SWAPSHORT(hp->version_minor);
 354         hp->thiszone = SWAPLONG(hp->thiszone);
 355         hp->sigfigs = SWAPLONG(hp->sigfigs);
 356         hp->snaplen = SWAPLONG(hp->snaplen);
 357         hp->linktype = SWAPLONG(hp->linktype);
 358 }
 359
 360 pcap_t *
 361 pcap_open_offline(const char *fname, char *errbuf)
 362 {
 363         register pcap_t *p;
 364         register FILE *fp;
 365         struct pcap_file_header hdr;
 366         bpf_u_int32 magic;
 367         int linklen;
 368
 369         p = (pcap_t *)malloc(sizeof(*p));
 370         if (p == NULL) {
 371                 strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE);
 372                 return (NULL);
 373         }
 374
 375         memset((char *)p, 0, sizeof(*p));
 376         /*
 377          * Set this field so we don't close stdin in pcap_close!
 378          */
 379         p->fd = -1;
 380
 381         if (fname[0] == '-' && fname[1] == '\0')
 382                 fp = stdin;
 383         else {
 384                 fp = fopen(fname, "r");
 385                 if (fp == NULL) {
 386                         snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s", fname,
 387                             pcap_strerror(errno));
 388                         goto bad;
 389                 }
 390         }
 391         if (fread((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
 392                 snprintf(errbuf, PCAP_ERRBUF_SIZE, "fread: %s",
 393                     pcap_strerror(errno));
 394                 goto bad;
 395         }
 396         magic = hdr.magic;
 397         if (magic != TCPDUMP_MAGIC && magic != PATCHED_TCPDUMP_MAGIC) {
 398                 magic = SWAPLONG(magic);
 399                 if (magic != TCPDUMP_MAGIC && magic != PATCHED_TCPDUMP_MAGIC) {
 400                         snprintf(errbuf, PCAP_ERRBUF_SIZE,
 401                             "bad dump file format");
 402                         goto bad;
 403                 }
 404                 p->sf.swapped = 1;
 405                 swap_hdr(&hdr);
 406         }
 407         if (magic == PATCHED_TCPDUMP_MAGIC) {
 408                 /*
 409                  * XXX - the patch that's in some versions of libpcap
 410                  * changes the packet header but not the magic number;
 411                  * we'd have to use some hacks^H^H^H^H^Hheuristics to
 412                  * detect that.
 413                  */
 414                 p->sf.hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
 415         } else
 416                 p->sf.hdrsize = sizeof(struct pcap_sf_pkthdr);
 417         if (hdr.version_major < PCAP_VERSION_MAJOR) {
 418                 snprintf(errbuf, PCAP_ERRBUF_SIZE, "archaic file format");
 419                 goto bad;
 420         }
 421         p->tzoff = hdr.thiszone;
 422         p->snapshot = hdr.snaplen;
 423         p->linktype = linktype_to_dlt(hdr.linktype);
 424         p->sf.rfile = fp;
 425         p->bufsize = hdr.snaplen;
 426
 427         /* Align link header as required for proper data alignment */
 428         /* XXX should handle all types */
 429         switch (p->linktype) {
 430
 431         case DLT_EN10MB:
 432                 linklen = 14;
 433                 break;
 434
 435         case DLT_FDDI:
 436                 linklen = 13 + 8;       /* fddi_header + llc */
 437                 break;
 438
 439         case DLT_NULL:
 440         default:
 441                 linklen = 0;
 442                 break;
 443         }
 444
 445         if (p->bufsize < 0)
 446                 p->bufsize = BPF_MAXBUFSIZE;
 447         p->sf.base = (u_char *)malloc(p->bufsize + BPF_ALIGNMENT);
 448         if (p->sf.base == NULL) {
 449                 strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE);
 450                 goto bad;
 451         }
 452         p->buffer = p->sf.base + BPF_ALIGNMENT - (linklen % BPF_ALIGNMENT);
 453         p->sf.version_major = hdr.version_major;
 454         p->sf.version_minor = hdr.version_minor;
 455 #ifdef PCAP_FDDIPAD
 456         /* XXX padding only needed for kernel fcode */
 457         pcap_fddipad = 0;
 458 #endif
 459
 460         return (p);
 461  bad:
 462         free(p);
 463         return (NULL);
 464 }
 465
 466 /*
 467  * Read sf_readfile and return the next packet.  Return the header in hdr
 468  * and the contents in buf.  Return 0 on success, SFERR_EOF if there were
 469  * no more packets, and SFERR_TRUNC if a partial packet was encountered.
 470  */
 471 static int
 472 sf_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char *buf, int buflen)
 473 {
 474         struct pcap_sf_patched_pkthdr sf_hdr;
 475         FILE *fp = p->sf.rfile;
 476
 477         /*
 478          * Read the packet header; the structure we use as a buffer
 479          * is the longer structure for files generated by the patched
 480          * libpcap, but if the file has the magic number for an
 481          * unpatched libpcap we only read as many bytes as the regular
 482          * header has.
 483          */
 484         if (fread(&sf_hdr, p->sf.hdrsize, 1, fp) != 1) {
 485                 /* probably an EOF, though could be a truncated packet */
 486                 return (1);
 487         }
 488
 489         if (p->sf.swapped) {
 490                 /* these were written in opposite byte order */
 491                 hdr->caplen = SWAPLONG(sf_hdr.caplen);
 492                 hdr->len = SWAPLONG(sf_hdr.len);
 493                 hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
 494                 hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
 495         } else {
 496                 hdr->caplen = sf_hdr.caplen;
 497                 hdr->len = sf_hdr.len;
 498                 hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
 499                 hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
 500         }
 501         /*
 502          * We interchanged the caplen and len fields at version 2.3,
 503          * in order to match the bpf header layout.  But unfortunately
 504          * some files were written with version 2.3 in their headers
 505          * but without the interchanged fields.
 506          */
 507         if (p->sf.version_minor < 3 ||
 508             (p->sf.version_minor == 3 && hdr->caplen > hdr->len)) {
 509                 int t = hdr->caplen;
 510                 hdr->caplen = hdr->len;
 511                 hdr->len = t;
 512         }
 513
 514         if (hdr->caplen > buflen) {
 515                 /*
 516                  * This can happen due to Solaris 2.3 systems tripping
 517                  * over the BUFMOD problem and not setting the snapshot
 518                  * correctly in the savefile header.  If the caplen isn't
 519                  * grossly wrong, try to salvage.
 520                  */
 521                 static u_char *tp = NULL;
 522                 static int tsize = 0;
 523
 524                 if (hdr->caplen > 65535) {
 525                         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 526                             "bogus savefile header");
 527                         return (-1);
 528                 }
 529
 530                 if (tsize < hdr->caplen) {
 531                         tsize = ((hdr->caplen + 1023) / 1024) * 1024;
 532                         if (tp != NULL)
 533                                 free((u_char *)tp);
 534                         tp = (u_char *)malloc(tsize);
 535                         if (tp == NULL) {
 536                                 tsize = 0;
 537                                 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 538                                     "BUFMOD hack malloc");
 539                                 return (-1);
 540                         }
 541                 }
 542                 if (fread((char *)tp, hdr->caplen, 1, fp) != 1) {
 543                         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 544                             "truncated dump file");
 545                         return (-1);
 546                 }
 547                 /*
 548                  * We can only keep up to buflen bytes.  Since caplen > buflen
 549                  * is exactly how we got here, we know we can only keep the
 550                  * first buflen bytes and must drop the remainder.  Adjust
 551                  * caplen accordingly, so we don't get confused later as
 552                  * to how many bytes we have to play with.
 553                  */
 554                 hdr->caplen = buflen;
 555                 memcpy((char *)buf, (char *)tp, buflen);
 556
 557         } else {
 558                 /* read the packet itself */
 559
 560                 if (fread((char *)buf, hdr->caplen, 1, fp) != 1) {
 561                         snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 562                             "truncated dump file");
 563                         return (-1);
 564                 }
 565         }
 566         return (0);
 567 }
 568
 569 /*
 570  * Print out packets stored in the file initialized by sf_read_init().
 571  * If cnt > 0, return after 'cnt' packets, otherwise continue until eof.
 572  */
 573 int
 574 pcap_offline_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
 575 {
 576         struct bpf_insn *fcode = p->fcode.bf_insns;
 577         int status = 0;
 578         int n = 0;
 579
 580         while (status == 0) {
 581                 struct pcap_pkthdr h;
 582
 583                 status = sf_next_packet(p, &h, p->buffer, p->bufsize);
 584                 if (status) {
 585                         if (status == 1)
 586                                 return (0);
 587                         return (status);
 588                 }
 589
 590                 if (fcode == NULL ||
 591                     bpf_filter(fcode, p->buffer, h.len, h.caplen)) {
 592                         (*callback)(user, &h, p->buffer);
 593                         if (++n >= cnt && cnt > 0)
 594                                 break;
 595                 }
 596         }
 597         /*XXX this breaks semantics tcpslice expects */
 598         return (n);
 599 }
 600
 601 /*
 602  * Output a packet to the initialized dump file.
 603  */
 604 void
 605 pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
 606 {
 607         register FILE *f;
 608         struct pcap_sf_pkthdr sf_hdr;
 609
 610         f = (FILE *)user;
 611         sf_hdr.ts.tv_sec  = h->ts.tv_sec;
 612         sf_hdr.ts.tv_usec = h->ts.tv_usec;
 613         sf_hdr.caplen     = h->caplen;
 614         sf_hdr.len        = h->len;
 615         /* XXX we should check the return status */
 616         (void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
 617         (void)fwrite((char *)sp, h->caplen, 1, f);
 618 }
 619
 620 /*
 621  * Initialize so that sf_write() will output to the file named 'fname'.
 622  */
 623 pcap_dumper_t *
 624 pcap_dump_open(pcap_t *p, const char *fname)
 625 {
 626         FILE *f;
 627         int linktype;
 628
 629         linktype = dlt_to_linktype(p->linktype);
 630         if (linktype == -1) {
 631                 snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
 632                     "%s: link-layer type %d isn't supported in savefiles",
 633                     fname, linktype);
 634                 return (NULL);
 635         }
 636
 637         if (fname[0] == '-' && fname[1] == '\0')
 638                 f = stdout;
 639         else {
 640                 f = fopen(fname, "w");
 641                 if (f == NULL) {
 642                         snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s: %s",
 643                             fname, pcap_strerror(errno));
 644                         return (NULL);
 645                 }
 646         }
 647         (void)sf_write_header(f, linktype, p->tzoff, p->snapshot);
 648         return ((pcap_dumper_t *)f);
 649 }
 650
 651 void
 652 pcap_dump_close(pcap_dumper_t *p)
 653 {
 654
 655 #ifdef notyet
 656         if (ferror((FILE *)p))
 657                 return-an-error;
 658         /* XXX should check return from fclose() too */
 659 #endif
 660         (void)fclose((FILE *)p);
 661 }