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/* ber.c
*
* Basic Encoding Rules (BER) file reading
*
* $Id$
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <errno.h>
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include "wtap-int.h"
#include "file_wrappers.h"
#include "buffer.h"
#include "ber.h"
#define BER_CLASS_UNI 0
#define BER_CLASS_APP 1
#define BER_CLASS_CON 2
#define BER_UNI_TAG_SEQ 16 /* SEQUENCE, SEQUENCE OF */
#define BER_UNI_TAG_SET 17 /* SET, SET OF */
static gboolean ber_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
{
gint64 offset;
guint8 *buf;
gint64 file_size;
int packet_size;
*err = 0;
offset = file_tell(wth->fh);
/* there is only ever one packet */
if (offset != 0)
return FALSE;
*data_offset = offset;
if ((file_size = wtap_file_size(wth, err)) == -1)
return FALSE;
if (file_size > WTAP_MAX_PACKET_SIZE) {
/*
* Probably a corrupt capture file; don't blow up trying
* to allocate space for an immensely-large packet.
*/
*err = WTAP_ERR_BAD_FILE;
*err_info = g_strdup_printf("ber: File has %" G_GINT64_MODIFIER "d-byte packet, bigger than maximum of %u",
file_size, WTAP_MAX_PACKET_SIZE);
return FALSE;
}
packet_size = (int)file_size;
buffer_assure_space(wth->frame_buffer, packet_size);
buf = buffer_start_ptr(wth->frame_buffer);
wtap_file_read_expected_bytes(buf, packet_size, wth->fh, err, err_info);
wth->phdr.presence_flags = 0; /* yes, we have no bananas^Wtime stamp */
wth->phdr.caplen = packet_size;
wth->phdr.len = packet_size;
wth->phdr.ts.secs = 0;
wth->phdr.ts.nsecs = 0;
return TRUE;
}
static gboolean ber_seek_read(wtap *wth, gint64 seek_off, union wtap_pseudo_header *pseudo_header _U_,
guint8 *pd, int length, int *err, gchar **err_info)
{
int packet_size = length;
/* there is only one packet */
if(seek_off > 0) {
*err = 0;
return FALSE;
}
if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
return FALSE;
wtap_file_read_expected_bytes(pd, packet_size, wth->random_fh, err, err_info);
return TRUE;
}
int ber_open(wtap *wth, int *err, gchar **err_info)
{
#define BER_BYTES_TO_CHECK 8
guint8 bytes[BER_BYTES_TO_CHECK];
int bytes_read;
guint8 ber_id;
gint8 ber_class;
gint8 ber_tag;
gboolean ber_pc;
guint8 oct, nlb = 0;
int len = 0;
gint64 file_size;
int offset = 0, i;
bytes_read = file_read(&bytes, BER_BYTES_TO_CHECK, wth->fh);
if (bytes_read != BER_BYTES_TO_CHECK) {
*err = file_error(wth->fh, err_info);
return (*err != 0) ? -1 : 0;
}
ber_id = bytes[offset++];
ber_class = (ber_id>>6) & 0x03;
ber_pc = (ber_id>>5) & 0x01;
ber_tag = ber_id & 0x1F;
/* it must be constructed and either a SET or a SEQUENCE */
/* or a CONTEXT less than 32 (arbitrary) */
/* XXX: do we also want to allow APPLICATION */
if(!(ber_pc &&
(((ber_class == BER_CLASS_UNI) && ((ber_tag == BER_UNI_TAG_SET) || (ber_tag == BER_UNI_TAG_SEQ))) ||
((ber_class == BER_CLASS_CON) && (ber_tag < 32)))))
return 0;
/* now check the length */
oct = bytes[offset++];
if(oct != 0x80) {
/* not indefinite length encoded */
if(!(oct & 0x80))
/* length fits into a single byte */
len = oct;
else {
nlb = oct & 0x7F; /* number of length bytes */
if((nlb > 0) && (nlb <= (BER_BYTES_TO_CHECK - 2))) {
/* not indefinite length and we have read enough bytes to compute the length */
i = nlb;
while(i--) {
oct = bytes[offset++];
len = (len<<8) + oct;
}
}
}
len += (2 + nlb); /* add back Tag and Length bytes */
file_size = wtap_file_size(wth, err);
if(len != file_size) {
return 0; /* not ASN.1 */
}
} else {
/* Indefinite length encoded - assume it is BER */
}
/* seek back to the start of the file */
if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
return -1;
wth->file_type = WTAP_FILE_BER;
wth->file_encap = WTAP_ENCAP_BER;
wth->snapshot_length = 0;
wth->subtype_read = ber_read;
wth->subtype_seek_read = ber_seek_read;
wth->tsprecision = WTAP_FILE_TSPREC_SEC;
return 1;
}
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