forked from osmocom/wireshark
116 lines
2.8 KiB
C
116 lines
2.8 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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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "config.h"
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#include <errno.h>
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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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wtap_open_return_val 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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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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if (!wtap_read_bytes(wth->fh, &bytes, BER_BYTES_TO_CHECK, err, err_info)) {
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if (*err != WTAP_ERR_SHORT_READ)
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return WTAP_OPEN_ERROR;
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return WTAP_OPEN_NOT_MINE;
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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/APPLICATION less than 32 (arbitrary) */
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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_class == BER_CLASS_APP)) && (ber_tag < 32)))))
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return WTAP_OPEN_NOT_MINE;
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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 WTAP_OPEN_NOT_MINE; /* 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 WTAP_OPEN_ERROR;
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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 = wtap_full_file_read;
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wth->subtype_seek_read = wtap_full_file_seek_read;
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wth->file_tsprec = WTAP_TSPREC_SEC;
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return WTAP_OPEN_MINE;
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local Variables:
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* c-basic-offset: 2
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=2 tabstop=8 expandtab:
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* :indentSize=2:tabSize=8:noTabs=true:
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*/
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