![Guy Harris](/assets/img/avatar_default.png)
Otherwise, if you link with both libwiretap and libfiletap, it's anybody's guess which one you get. That means you're wasting memory with two copies of its routines if they're identical, and means surprising behavior if they're not (which showed up when I was debugging a double-free crash - fixing libwiretap's buffer_free() didn't fix the problem, because Wireshark happened to be calling libfiletap' unfixed buffer_free()). There's nothing *tap-specific about Buffers, anyway, so it really belongs in wsutil. Change-Id: I91537e46917e91277981f8f3365a2c0873152870 Reviewed-on: https://code.wireshark.org/review/3066 Reviewed-by: Guy Harris <guy@alum.mit.edu>
188 lines
4.8 KiB
C
188 lines
4.8 KiB
C
/* ber.c
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*
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* Basic Encoding Rules (BER) file reading
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include <errno.h>
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#ifdef HAVE_SYS_STAT_H
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#include <sys/stat.h>
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#endif
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#include "wtap-int.h"
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#include "file_wrappers.h"
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#include <wsutil/buffer.h>
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#include "ber.h"
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#define BER_CLASS_UNI 0
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#define BER_CLASS_APP 1
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#define BER_CLASS_CON 2
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#define BER_UNI_TAG_SEQ 16 /* SEQUENCE, SEQUENCE OF */
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#define BER_UNI_TAG_SET 17 /* SET, SET OF */
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static gboolean ber_read_file(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
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Buffer *buf, int *err, gchar **err_info)
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{
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gint64 file_size;
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int packet_size;
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if ((file_size = wtap_file_size(wth, err)) == -1)
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return FALSE;
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if (file_size > WTAP_MAX_PACKET_SIZE) {
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/*
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* Probably a corrupt capture file; don't blow up trying
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* to allocate space for an immensely-large packet.
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*/
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*err = WTAP_ERR_BAD_FILE;
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*err_info = g_strdup_printf("ber: File has %" G_GINT64_MODIFIER "d-byte packet, bigger than maximum of %u",
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file_size, WTAP_MAX_PACKET_SIZE);
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return FALSE;
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}
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packet_size = (int)file_size;
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phdr->rec_type = REC_TYPE_PACKET;
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phdr->presence_flags = 0; /* yes, we have no bananas^Wtime stamp */
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phdr->caplen = packet_size;
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phdr->len = packet_size;
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phdr->ts.secs = 0;
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phdr->ts.nsecs = 0;
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return wtap_read_packet_bytes(fh, buf, packet_size, err, err_info);
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}
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static gboolean ber_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
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{
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gint64 offset;
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*err = 0;
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offset = file_tell(wth->fh);
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/* there is only ever one packet */
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if (offset != 0)
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return FALSE;
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*data_offset = offset;
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return ber_read_file(wth, wth->fh, &wth->phdr, wth->frame_buffer, err, err_info);
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}
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static gboolean ber_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr _U_,
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Buffer *buf, int *err, gchar **err_info)
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{
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/* there is only one packet */
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if(seek_off > 0) {
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*err = 0;
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return FALSE;
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}
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if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
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return FALSE;
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return ber_read_file(wth, wth->random_fh, phdr, buf, err, err_info);
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}
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int ber_open(wtap *wth, int *err, gchar **err_info)
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{
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#define BER_BYTES_TO_CHECK 8
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guint8 bytes[BER_BYTES_TO_CHECK];
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int bytes_read;
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guint8 ber_id;
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gint8 ber_class;
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gint8 ber_tag;
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gboolean ber_pc;
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guint8 oct, nlb = 0;
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int len = 0;
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gint64 file_size;
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int offset = 0, i;
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bytes_read = file_read(&bytes, BER_BYTES_TO_CHECK, wth->fh);
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if (bytes_read != BER_BYTES_TO_CHECK) {
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*err = file_error(wth->fh, err_info);
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if (*err != 0 && *err != WTAP_ERR_SHORT_READ)
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return -1;
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return 0;
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}
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ber_id = bytes[offset++];
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ber_class = (ber_id>>6) & 0x03;
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ber_pc = (ber_id>>5) & 0x01;
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ber_tag = ber_id & 0x1F;
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/* it must be constructed and either a SET or a SEQUENCE */
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/* or a CONTEXT less than 32 (arbitrary) */
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/* XXX: do we also want to allow APPLICATION */
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if(!(ber_pc &&
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(((ber_class == BER_CLASS_UNI) && ((ber_tag == BER_UNI_TAG_SET) || (ber_tag == BER_UNI_TAG_SEQ))) ||
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((ber_class == BER_CLASS_CON) && (ber_tag < 32)))))
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return 0;
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/* now check the length */
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oct = bytes[offset++];
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if(oct != 0x80) {
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/* not indefinite length encoded */
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if(!(oct & 0x80))
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/* length fits into a single byte */
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len = oct;
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else {
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nlb = oct & 0x7F; /* number of length bytes */
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if((nlb > 0) && (nlb <= (BER_BYTES_TO_CHECK - 2))) {
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/* not indefinite length and we have read enough bytes to compute the length */
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i = nlb;
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while(i--) {
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oct = bytes[offset++];
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len = (len<<8) + oct;
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}
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}
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}
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len += (2 + nlb); /* add back Tag and Length bytes */
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file_size = wtap_file_size(wth, err);
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if(len != file_size) {
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return 0; /* not ASN.1 */
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}
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} else {
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/* Indefinite length encoded - assume it is BER */
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}
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/* seek back to the start of the file */
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if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
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return -1;
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wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_BER;
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wth->file_encap = WTAP_ENCAP_BER;
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wth->snapshot_length = 0;
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wth->subtype_read = ber_read;
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wth->subtype_seek_read = ber_seek_read;
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wth->tsprecision = WTAP_FILE_TSPREC_SEC;
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return 1;
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}
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