OpenBSD-4.6/lib/libpcap/savefile.c
/* $OpenBSD: savefile.c,v 1.9 2006/03/26 20:58:51 djm Exp $ */
/*
* 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.
*
* savefile.c - supports offline use of tcpdump
* 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.
*/
#include <sys/types.h>
#include <sys/time.h>
#include <errno.h>
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#include "pcap-int.h"
#define TCPDUMP_MAGIC 0xa1b2c3d4
/*
* We use the "receiver-makes-right" approach to byte order,
* because time is at a premium when we are writing the file.
* In other words, the pcap_file_header and pcap_pkthdr,
* records are written in host byte order.
* Note that the packets are always written in network byte order.
*
* ntoh[ls] aren't sufficient because we might need to swap on a big-endian
* machine (if the file was written in little-end order).
*/
#define SWAPLONG(y) \
((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
#define SWAPSHORT(y) \
( (((y)&0xff)<<8) | ((u_short)((y)&0xff00)>>8) )
#define SFERR_TRUNC 1
#define SFERR_BADVERSION 2
#define SFERR_BADF 3
#define SFERR_EOF 4 /* not really an error, just a status */
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);
}
static void
swap_hdr(struct pcap_file_header *hp)
{
hp->version_major = SWAPSHORT(hp->version_major);
hp->version_minor = SWAPSHORT(hp->version_minor);
hp->thiszone = SWAPLONG(hp->thiszone);
hp->sigfigs = SWAPLONG(hp->sigfigs);
hp->snaplen = SWAPLONG(hp->snaplen);
hp->linktype = SWAPLONG(hp->linktype);
}
pcap_t *
pcap_open_offline(const char *fname, char *errbuf)
{
pcap_t *p;
FILE *fp;
if (fname[0] == '-' && fname[1] == '\0')
fp = stdin;
else {
fp = fopen(fname, "r");
if (fp == NULL) {
snprintf(errbuf, PCAP_ERRBUF_SIZE, "%s: %s", fname,
pcap_strerror(errno));
return (NULL);
}
}
p = pcap_fopen_offline(fp, errbuf);
if (p == NULL) {
if (fp != stdin)
fclose(fp);
}
return (p);
}
pcap_t *
pcap_fopen_offline(FILE *fp, char *errbuf)
{
pcap_t *p;
struct pcap_file_header hdr;
int linklen;
p = (pcap_t *)malloc(sizeof(*p));
if (p == NULL) {
strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE);
return (NULL);
}
memset((char *)p, 0, sizeof(*p));
/*
* Set this field so we don't double-close in pcap_close!
*/
p->fd = -1;
if (fread((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
snprintf(errbuf, PCAP_ERRBUF_SIZE, "fread: %s",
pcap_strerror(errno));
goto bad;
}
if (hdr.magic != TCPDUMP_MAGIC) {
if (SWAPLONG(hdr.magic) != TCPDUMP_MAGIC) {
snprintf(errbuf, PCAP_ERRBUF_SIZE,
"bad dump file format");
goto bad;
}
p->sf.swapped = 1;
swap_hdr(&hdr);
}
if (hdr.version_major < PCAP_VERSION_MAJOR) {
snprintf(errbuf, PCAP_ERRBUF_SIZE, "archaic file format");
goto bad;
}
p->tzoff = hdr.thiszone;
p->snapshot = hdr.snaplen;
p->linktype = hdr.linktype;
p->sf.rfile = fp;
p->bufsize = hdr.snaplen;
/* Align link header as required for proper data alignment */
/* XXX should handle all types */
switch (p->linktype) {
case DLT_EN10MB:
linklen = 14;
break;
case DLT_FDDI:
linklen = 13 + 8; /* fddi_header + llc */
break;
case DLT_NULL:
default:
linklen = 0;
break;
}
if (p->bufsize < 0)
p->bufsize = BPF_MAXBUFSIZE;
p->sf.base = (u_char *)malloc(p->bufsize + BPF_ALIGNMENT);
if (p->sf.base == NULL) {
strlcpy(errbuf, "out of swap", PCAP_ERRBUF_SIZE);
goto bad;
}
p->buffer = p->sf.base + BPF_ALIGNMENT - (linklen % BPF_ALIGNMENT);
p->sf.version_major = hdr.version_major;
p->sf.version_minor = hdr.version_minor;
#ifdef PCAP_FDDIPAD
/* XXX padding only needed for kernel fcode */
pcap_fddipad = 0;
#endif
return (p);
bad:
free(p);
return (NULL);
}
/*
* Read sf_readfile and return the next packet. Return the header in hdr
* and the contents in buf. Return 0 on success, SFERR_EOF if there were
* no more packets, and SFERR_TRUNC if a partial packet was encountered.
*/
static int
sf_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char *buf, int buflen)
{
FILE *fp = p->sf.rfile;
/* read the stamp */
if (fread((char *)hdr, sizeof(struct pcap_pkthdr), 1, fp) != 1) {
/* probably an EOF, though could be a truncated packet */
return (1);
}
if (p->sf.swapped) {
/* these were written in opposite byte order */
hdr->caplen = SWAPLONG(hdr->caplen);
hdr->len = SWAPLONG(hdr->len);
hdr->ts.tv_sec = SWAPLONG(hdr->ts.tv_sec);
hdr->ts.tv_usec = SWAPLONG(hdr->ts.tv_usec);
}
/*
* 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.
*/
if (p->sf.version_minor < 3 ||
(p->sf.version_minor == 3 && hdr->caplen > hdr->len)) {
int t = hdr->caplen;
hdr->caplen = hdr->len;
hdr->len = t;
}
if (hdr->caplen > buflen) {
/*
* 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 int 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);
}
}
if (fread((char *)tp, hdr->caplen, 1, fp) != 1) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file");
return (-1);
}
/*
* We can only keep up to buflen bytes. Since caplen > buflen
* is exactly how we got here, we know we can only keep the
* first buflen 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 = buflen;
memcpy((char *)buf, (char *)tp, buflen);
} else {
/* read the packet itself */
if (fread((char *)buf, hdr->caplen, 1, fp) != 1) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"truncated dump file");
return (-1);
}
}
return (0);
}
/*
* Print out packets stored in the file initialized by sf_read_init().
* If cnt > 0, return after 'cnt' packets, otherwise continue until eof.
*/
int
pcap_offline_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
{
struct bpf_insn *fcode = p->fcode.bf_insns;
int status = 0;
int n = 0;
while (status == 0) {
struct pcap_pkthdr h;
status = sf_next_packet(p, &h, p->buffer, p->bufsize);
if (status) {
if (status == 1)
return (0);
return (status);
}
if (fcode == NULL ||
bpf_filter(fcode, p->buffer, h.len, h.caplen)) {
(*callback)(user, &h, p->buffer);
if (++n >= cnt && cnt > 0)
break;
}
}
/*XXX this breaks semantics tcpslice expects */
return (n);
}
/*
* 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;
f = (FILE *)user;
/* XXX we should check the return status */
(void)fwrite((char *)h, sizeof(*h), 1, f);
(void)fwrite((char *)sp, h->caplen, 1, f);
}
static pcap_dumper_t *
pcap_setup_dump(pcap_t *p, FILE *f, const char *fname)
{
if (sf_write_header(f, p->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;
if (fname[0] == '-' && fname[1] == '\0')
f = stdout;
else {
f = fopen(fname, "w");
if (f == NULL) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "%s: %s",
fname, pcap_strerror(errno));
return (NULL);
}
}
return (pcap_setup_dump(p, f, fname));
}
/*
* Initialize so that sf_write() will output to the given stream.
*/
pcap_dumper_t *
pcap_dump_fopen(pcap_t *p, FILE *f)
{
return (pcap_setup_dump(p, 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));
}
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);
}