freebsd-dev/contrib/libpcap/sf-pcap.c
2012-05-14 05:12:56 +00:00

619 lines
16 KiB
C

/*
* Copyright (c) 1993, 1994, 1995, 1996, 1997
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* sf-pcap.c - libpcap-file-format-specific code from savefile.c
* Extraction/creation by Jeffrey Mogul, DECWRL
* Modified by Steve McCanne, LBL.
*
* Used to save the received packet headers, after filtering, to
* a file, and then read them later.
* The first record in the file contains saved values for the machine
* dependent values so we can print the dump file on any architecture.
*/
#ifndef lint
static const char rcsid[] _U_ =
"@(#) $Header$ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef WIN32
#include <pcap-stdinc.h>
#else /* WIN32 */
#if HAVE_INTTYPES_H
#include <inttypes.h>
#elif HAVE_STDINT_H
#include <stdint.h>
#endif
#ifdef HAVE_SYS_BITYPES_H
#include <sys/bitypes.h>
#endif
#include <sys/types.h>
#endif /* WIN32 */
#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pcap-int.h"
#include "pcap-common.h"
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#include "sf-pcap.h"
/*
* Setting O_BINARY on DOS/Windows is a bit tricky
*/
#if defined(WIN32)
#define SET_BINMODE(f) _setmode(_fileno(f), _O_BINARY)
#elif defined(MSDOS)
#if defined(__HIGHC__)
#define SET_BINMODE(f) setmode(f, O_BINARY)
#else
#define SET_BINMODE(f) setmode(fileno(f), O_BINARY)
#endif
#endif
/*
* Standard libpcap format.
*/
#define TCPDUMP_MAGIC 0xa1b2c3d4
/*
* Alexey Kuznetzov's modified libpcap format.
*/
#define KUZNETZOV_TCPDUMP_MAGIC 0xa1b2cd34
/*
* Reserved for Francisco Mesquita <francisco.mesquita@radiomovel.pt>
* for another modified format.
*/
#define FMESQUITA_TCPDUMP_MAGIC 0xa1b234cd
/*
* Navtel Communcations' format, with nanosecond timestamps,
* as per a request from Dumas Hwang <dumas.hwang@navtelcom.com>.
*/
#define NAVTEL_TCPDUMP_MAGIC 0xa12b3c4d
/*
* Normal libpcap format, except for seconds/nanoseconds timestamps,
* as per a request by Ulf Lamping <ulf.lamping@web.de>
*/
#define NSEC_TCPDUMP_MAGIC 0xa1b23c4d
/*
* Mechanism for storing information about a capture in the upper
* 6 bits of a linktype value in a capture file.
*
* LT_LINKTYPE_EXT(x) extracts the additional information.
*
* The rest of the bits are for a value describing the link-layer
* value. LT_LINKTYPE(x) extracts that value.
*/
#define LT_LINKTYPE(x) ((x) & 0x03FFFFFF)
#define LT_LINKTYPE_EXT(x) ((x) & 0xFC000000)
static int pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **datap);
/*
* Check whether this is a pcap savefile and, if it is, extract the
* relevant information from the header.
*/
int
pcap_check_header(pcap_t *p, bpf_u_int32 magic, FILE *fp, char *errbuf)
{
struct pcap_file_header hdr;
size_t amt_read;
/*
* Check whether the first 4 bytes of the file are the magic
* number for a pcap savefile, or for a byte-swapped pcap
* savefile.
*/
if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC) {
magic = SWAPLONG(magic);
if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC)
return (0); /* nope */
p->sf.swapped = 1;
}
/*
* They are. Put the magic number in the header, and read
* the rest of the header.
*/
hdr.magic = magic;
amt_read = fread(((char *)&hdr) + sizeof hdr.magic, 1,
sizeof(hdr) - sizeof(hdr.magic), fp);
if (amt_read != sizeof(hdr) - sizeof(hdr.magic)) {
if (ferror(fp)) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"error reading dump file: %s",
pcap_strerror(errno));
} else {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %lu file header bytes, only got %lu",
(unsigned long)sizeof(hdr),
(unsigned long)amt_read);
}
return (-1);
}
/*
* If it's a byte-swapped capture file, byte-swap the header.
*/
if (p->sf.swapped) {
hdr.version_major = SWAPSHORT(hdr.version_major);
hdr.version_minor = SWAPSHORT(hdr.version_minor);
hdr.thiszone = SWAPLONG(hdr.thiszone);
hdr.sigfigs = SWAPLONG(hdr.sigfigs);
hdr.snaplen = SWAPLONG(hdr.snaplen);
hdr.linktype = SWAPLONG(hdr.linktype);
}
if (hdr.version_major < PCAP_VERSION_MAJOR) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"archaic pcap savefile format");
return (-1);
}
p->sf.version_major = hdr.version_major;
p->sf.version_minor = hdr.version_minor;
p->tzoff = hdr.thiszone;
p->snapshot = hdr.snaplen;
p->linktype = linktype_to_dlt(LT_LINKTYPE(hdr.linktype));
p->linktype_ext = LT_LINKTYPE_EXT(hdr.linktype);
p->sf.next_packet_op = pcap_next_packet;
/*
* We interchanged the caplen and len fields at version 2.3,
* in order to match the bpf header layout. But unfortunately
* some files were written with version 2.3 in their headers
* but without the interchanged fields.
*
* In addition, DG/UX tcpdump writes out files with a version
* number of 543.0, and with the caplen and len fields in the
* pre-2.3 order.
*/
switch (hdr.version_major) {
case 2:
if (hdr.version_minor < 3)
p->sf.lengths_swapped = SWAPPED;
else if (hdr.version_minor == 3)
p->sf.lengths_swapped = MAYBE_SWAPPED;
else
p->sf.lengths_swapped = NOT_SWAPPED;
break;
case 543:
p->sf.lengths_swapped = SWAPPED;
break;
default:
p->sf.lengths_swapped = NOT_SWAPPED;
break;
}
if (magic == KUZNETZOV_TCPDUMP_MAGIC) {
/*
* XXX - the patch that's in some versions of libpcap
* changes the packet header but not the magic number,
* and some other versions with this magic number have
* some extra debugging information in the packet header;
* we'd have to use some hacks^H^H^H^H^Hheuristics to
* detect those variants.
*
* Ethereal does that, but it does so by trying to read
* the first two packets of the file with each of the
* record header formats. That currently means it seeks
* backwards and retries the reads, which doesn't work
* on pipes. We want to be able to read from a pipe, so
* that strategy won't work; we'd have to buffer some
* data ourselves and read from that buffer in order to
* make that work.
*/
p->sf.hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
if (p->linktype == DLT_EN10MB) {
/*
* This capture might have been done in raw mode
* or cooked mode.
*
* If it was done in cooked mode, p->snapshot was
* passed to recvfrom() as the buffer size, meaning
* that the most packet data that would be copied
* would be p->snapshot. However, a faked Ethernet
* header would then have been added to it, so the
* most data that would be in a packet in the file
* would be p->snapshot + 14.
*
* We can't easily tell whether the capture was done
* in raw mode or cooked mode, so we'll assume it was
* cooked mode, and add 14 to the snapshot length.
* That means that, for a raw capture, the snapshot
* length will be misleading if you use it to figure
* out why a capture doesn't have all the packet data,
* but there's not much we can do to avoid that.
*/
p->snapshot += 14;
}
} else
p->sf.hdrsize = sizeof(struct pcap_sf_pkthdr);
/*
* Allocate a buffer for the packet data.
*/
p->bufsize = p->snapshot;
if (p->bufsize <= 0) {
/*
* Bogus snapshot length; use 64KiB as a fallback.
*/
p->bufsize = 65536;
}
p->buffer = malloc(p->bufsize);
if (p->buffer == NULL) {
snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
return (-1);
}
return (1);
}
/*
* Read and return the next packet from the savefile. Return the header
* in hdr and a pointer to the contents in data. Return 0 on success, 1
* if there were no more packets, and -1 on an error.
*/
static int
pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
{
struct pcap_sf_patched_pkthdr sf_hdr;
FILE *fp = p->sf.rfile;
size_t amt_read;
bpf_u_int32 t;
/*
* Read the packet header; the structure we use as a buffer
* is the longer structure for files generated by the patched
* libpcap, but if the file has the magic number for an
* unpatched libpcap we only read as many bytes as the regular
* header has.
*/
amt_read = fread(&sf_hdr, 1, p->sf.hdrsize, fp);
if (amt_read != p->sf.hdrsize) {
if (ferror(fp)) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"error reading dump file: %s",
pcap_strerror(errno));
return (-1);
} else {
if (amt_read != 0) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %lu header bytes, only got %lu",
(unsigned long)p->sf.hdrsize,
(unsigned long)amt_read);
return (-1);
}
/* EOF */
return (1);
}
}
if (p->sf.swapped) {
/* these were written in opposite byte order */
hdr->caplen = SWAPLONG(sf_hdr.caplen);
hdr->len = SWAPLONG(sf_hdr.len);
hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
} else {
hdr->caplen = sf_hdr.caplen;
hdr->len = sf_hdr.len;
hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
}
/* Swap the caplen and len fields, if necessary. */
switch (p->sf.lengths_swapped) {
case NOT_SWAPPED:
break;
case MAYBE_SWAPPED:
if (hdr->caplen <= hdr->len) {
/*
* The captured length is <= the actual length,
* so presumably they weren't swapped.
*/
break;
}
/* FALLTHROUGH */
case SWAPPED:
t = hdr->caplen;
hdr->caplen = hdr->len;
hdr->len = t;
break;
}
if (hdr->caplen > p->bufsize) {
/*
* This can happen due to Solaris 2.3 systems tripping
* over the BUFMOD problem and not setting the snapshot
* correctly in the savefile header. If the caplen isn't
* grossly wrong, try to salvage.
*/
static u_char *tp = NULL;
static size_t tsize = 0;
if (hdr->caplen > 65535) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"bogus savefile header");
return (-1);
}
if (tsize < hdr->caplen) {
tsize = ((hdr->caplen + 1023) / 1024) * 1024;
if (tp != NULL)
free((u_char *)tp);
tp = (u_char *)malloc(tsize);
if (tp == NULL) {
tsize = 0;
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"BUFMOD hack malloc");
return (-1);
}
}
amt_read = fread((char *)tp, 1, hdr->caplen, fp);
if (amt_read != hdr->caplen) {
if (ferror(fp)) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"error reading dump file: %s",
pcap_strerror(errno));
} else {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %u captured bytes, only got %lu",
hdr->caplen, (unsigned long)amt_read);
}
return (-1);
}
/*
* We can only keep up to p->bufsize bytes. Since
* caplen > p->bufsize is exactly how we got here,
* we know we can only keep the first p->bufsize bytes
* and must drop the remainder. Adjust caplen accordingly,
* so we don't get confused later as to how many bytes we
* have to play with.
*/
hdr->caplen = p->bufsize;
memcpy(p->buffer, (char *)tp, p->bufsize);
} else {
/* read the packet itself */
amt_read = fread(p->buffer, 1, hdr->caplen, fp);
if (amt_read != hdr->caplen) {
if (ferror(fp)) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"error reading dump file: %s",
pcap_strerror(errno));
} else {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file; tried to read %u captured bytes, only got %lu",
hdr->caplen, (unsigned long)amt_read);
}
return (-1);
}
}
*data = p->buffer;
if (p->sf.swapped) {
/*
* Convert pseudo-headers from the byte order of
* the host on which the file was saved to our
* byte order, as necessary.
*/
switch (p->linktype) {
case DLT_USB_LINUX:
swap_linux_usb_header(hdr, *data, 0);
break;
case DLT_USB_LINUX_MMAPPED:
swap_linux_usb_header(hdr, *data, 1);
break;
}
}
return (0);
}
static int
sf_write_header(FILE *fp, int linktype, int thiszone, int snaplen)
{
struct pcap_file_header hdr;
hdr.magic = TCPDUMP_MAGIC;
hdr.version_major = PCAP_VERSION_MAJOR;
hdr.version_minor = PCAP_VERSION_MINOR;
hdr.thiszone = thiszone;
hdr.snaplen = snaplen;
hdr.sigfigs = 0;
hdr.linktype = linktype;
if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
return (-1);
return (0);
}
/*
* Output a packet to the initialized dump file.
*/
void
pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
register FILE *f;
struct pcap_sf_pkthdr sf_hdr;
f = (FILE *)user;
sf_hdr.ts.tv_sec = h->ts.tv_sec;
sf_hdr.ts.tv_usec = h->ts.tv_usec;
sf_hdr.caplen = h->caplen;
sf_hdr.len = h->len;
/* XXX we should check the return status */
(void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
(void)fwrite(sp, h->caplen, 1, f);
}
static pcap_dumper_t *
pcap_setup_dump(pcap_t *p, int linktype, FILE *f, const char *fname)
{
#if defined(WIN32) || defined(MSDOS)
/*
* If we're writing to the standard output, put it in binary
* mode, as savefiles are binary files.
*
* Otherwise, we turn off buffering.
* XXX - why? And why not on the standard output?
*/
if (f == stdout)
SET_BINMODE(f);
else
setbuf(f, NULL);
#endif
if (sf_write_header(f, linktype, p->tzoff, p->snapshot) == -1) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "Can't write to %s: %s",
fname, pcap_strerror(errno));
if (f != stdout)
(void)fclose(f);
return (NULL);
}
return ((pcap_dumper_t *)f);
}
/*
* Initialize so that sf_write() will output to the file named 'fname'.
*/
pcap_dumper_t *
pcap_dump_open(pcap_t *p, const char *fname)
{
FILE *f;
int linktype;
/*
* If this pcap_t hasn't been activated, it doesn't have a
* link-layer type, so we can't use it.
*/
if (!p->activated) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: not-yet-activated pcap_t passed to pcap_dump_open",
fname);
return (NULL);
}
linktype = dlt_to_linktype(p->linktype);
if (linktype == -1) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"%s: link-layer type %d isn't supported in savefiles",
fname, p->linktype);
return (NULL);
}
linktype |= p->linktype_ext;
if (fname[0] == '-' && fname[1] == '\0') {
f = stdout;
fname = "standard output";
} else {
#if !defined(WIN32) && !defined(MSDOS)
f = fopen(fname, "w");
#else
f = fopen(fname, "wb");
#endif
if (f == NULL) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s: %s",
fname, pcap_strerror(errno));
return (NULL);
}
}
return (pcap_setup_dump(p, linktype, f, fname));
}
/*
* Initialize so that sf_write() will output to the given stream.
*/
pcap_dumper_t *
pcap_dump_fopen(pcap_t *p, FILE *f)
{
int linktype;
linktype = dlt_to_linktype(p->linktype);
if (linktype == -1) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"stream: link-layer type %d isn't supported in savefiles",
p->linktype);
return (NULL);
}
linktype |= p->linktype_ext;
return (pcap_setup_dump(p, linktype, f, "stream"));
}
FILE *
pcap_dump_file(pcap_dumper_t *p)
{
return ((FILE *)p);
}
long
pcap_dump_ftell(pcap_dumper_t *p)
{
return (ftell((FILE *)p));
}
int
pcap_dump_flush(pcap_dumper_t *p)
{
if (fflush((FILE *)p) == EOF)
return (-1);
else
return (0);
}
void
pcap_dump_close(pcap_dumper_t *p)
{
#ifdef notyet
if (ferror((FILE *)p))
return-an-error;
/* XXX should check return from fclose() too */
#endif
(void)fclose((FILE *)p);
}