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/* csids.c
*
* Copyright (c) 2000 by Mike Hall <mlh@io.com>
* Copyright (c) 2000 by Cisco Systems
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "wtap-int.h"
#include "csids.h"
#include "file_wrappers.h"
#include <stdlib.h>
#include <string.h>
/*
* This module reads the output from the Cisco Secure Intrusion Detection
* System iplogging facility. The term iplogging is misleading since this
* logger will only output TCP. There is no link layer information.
* Packet format is 4 byte timestamp (seconds since epoch), and a 4 byte size
* of data following for that packet.
*
* For a time there was an error in iplogging and the ip length, flags, and id
* were byteswapped. We will check for this and handle it before handing to
* wireshark.
*/
typedef struct {
gboolean byteswapped;
} csids_t;
static gboolean csids_read(wtap *wth, int *err, gchar **err_info,
gint64 *data_offset);
static gboolean csids_seek_read(wtap *wth, gint64 seek_off,
struct wtap_pkthdr *phdr, Buffer *buf, int *err, gchar **err_info);
static gboolean csids_read_packet(FILE_T fh, csids_t *csids,
struct wtap_pkthdr *phdr, Buffer *buf, int *err, gchar **err_info);
struct csids_header {
guint32 seconds; /* seconds since epoch */
guint16 zeropad; /* 2 byte zero'ed pads */
guint16 caplen; /* the capture length */
};
wtap_open_return_val csids_open(wtap *wth, int *err, gchar **err_info)
{
/* There is no file header. There is only a header for each packet
* so we read a packet header and compare the caplen with iplen. They
* should always be equal except with the weird byteswap version.
*
* THIS IS BROKEN-- anytime the caplen is 0x0101 or 0x0202 up to 0x0505
* this will byteswap it. I need to fix this. XXX --mlh
*/
int tmp,iplen;
gboolean byteswap = FALSE;
struct csids_header hdr;
csids_t *csids;
/* check the file to make sure it is a csids file. */
if( !wtap_read_bytes( wth->fh, &hdr, sizeof( struct csids_header), err, err_info ) ) {
if( *err != WTAP_ERR_SHORT_READ ) {
return WTAP_OPEN_ERROR;
}
return WTAP_OPEN_NOT_MINE;
}
if( hdr.zeropad != 0 || hdr.caplen == 0 ) {
return WTAP_OPEN_NOT_MINE;
}
hdr.seconds = pntoh32( &hdr.seconds );
hdr.caplen = pntoh16( &hdr.caplen );
if( !wtap_read_bytes( wth->fh, &tmp, 2, err, err_info ) ) {
if( *err != WTAP_ERR_SHORT_READ ) {
return WTAP_OPEN_ERROR;
}
return WTAP_OPEN_NOT_MINE;
}
if( !wtap_read_bytes(wth->fh, &iplen, 2, err, err_info ) ) {
if( *err != WTAP_ERR_SHORT_READ ) {
return WTAP_OPEN_ERROR;
}
return WTAP_OPEN_NOT_MINE;
}
iplen = pntoh16(&iplen);
if ( iplen == 0 )
return WTAP_OPEN_NOT_MINE;
/* if iplen and hdr.caplen are equal, default to no byteswap. */
if( iplen > hdr.caplen ) {
/* maybe this is just a byteswapped version. the iplen ipflags */
/* and ipid are swapped. We cannot use the normal swaps because */
/* we don't know the host */
iplen = GUINT16_SWAP_LE_BE(iplen);
if( iplen <= hdr.caplen ) {
/* we know this format */
byteswap = TRUE;
} else {
/* don't know this one */
return WTAP_OPEN_NOT_MINE;
}
} else {
byteswap = FALSE;
}
/* no file header. So reset the fh to 0 so we can read the first packet */
if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
return WTAP_OPEN_ERROR;
csids = (csids_t *)g_malloc(sizeof(csids_t));
wth->priv = (void *)csids;
csids->byteswapped = byteswap;
wth->file_encap = WTAP_ENCAP_RAW_IP;
wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_CSIDS;
wth->snapshot_length = 0; /* not known */
wth->subtype_read = csids_read;
wth->subtype_seek_read = csids_seek_read;
wth->file_tsprec = WTAP_TSPREC_SEC;
return WTAP_OPEN_MINE;
}
/* Find the next packet and parse it; called from wtap_read(). */
static gboolean csids_read(wtap *wth, int *err, gchar **err_info,
gint64 *data_offset)
{
csids_t *csids = (csids_t *)wth->priv;
*data_offset = file_tell(wth->fh);
return csids_read_packet( wth->fh, csids, &wth->phdr, wth->frame_buffer,
err, err_info );
}
/* Used to read packets in random-access fashion */
static gboolean
csids_seek_read(wtap *wth,
gint64 seek_off,
struct wtap_pkthdr *phdr,
Buffer *buf,
int *err,
gchar **err_info)
{
csids_t *csids = (csids_t *)wth->priv;
if( file_seek( wth->random_fh, seek_off, SEEK_SET, err ) == -1 )
return FALSE;
if( !csids_read_packet( wth->random_fh, csids, phdr, buf, err, err_info ) ) {
if( *err == 0 )
*err = WTAP_ERR_SHORT_READ;
return FALSE;
}
return TRUE;
}
static gboolean
csids_read_packet(FILE_T fh, csids_t *csids, struct wtap_pkthdr *phdr,
Buffer *buf, int *err, gchar **err_info)
{
struct csids_header hdr;
guint8 *pd;
if( !wtap_read_bytes_or_eof( fh, &hdr, sizeof( struct csids_header), err, err_info ) )
return FALSE;
hdr.seconds = pntoh32(&hdr.seconds);
hdr.caplen = pntoh16(&hdr.caplen);
phdr->rec_type = REC_TYPE_PACKET;
phdr->presence_flags = WTAP_HAS_TS;
phdr->len = hdr.caplen;
phdr->caplen = hdr.caplen;
phdr->ts.secs = hdr.seconds;
phdr->ts.nsecs = 0;
if( !wtap_read_packet_bytes( fh, buf, phdr->caplen, err, err_info ) )
return FALSE;
pd = ws_buffer_start_ptr( buf );
if( csids->byteswapped ) {
if( phdr->caplen >= 2 ) {
PBSWAP16(pd); /* the ip len */
if( phdr->caplen >= 4 ) {
PBSWAP16(pd+2); /* ip id */
if( phdr->caplen >= 6 )
PBSWAP16(pd+4); /* ip flags and fragoff */
}
}
}
return TRUE;
}
/*
* Editor modelines - http://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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