3 * Basic Encoding Rules (BER) file reading
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13 * GNU General Public License for more details.
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24 #ifdef HAVE_SYS_STAT_H
29 #include "file_wrappers.h"
34 #define BER_CLASS_UNI 0
35 #define BER_CLASS_APP 1
36 #define BER_CLASS_CON 2
38 #define BER_UNI_TAG_SEQ 16 /* SEQUENCE, SEQUENCE OF */
39 #define BER_UNI_TAG_SET 17 /* SET, SET OF */
41 static int ber_read_file(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
42 Buffer *buf, int *err, gchar **err_info)
47 if ((file_size = wtap_file_size(wth, err)) == -1)
50 if (file_size > WTAP_MAX_PACKET_SIZE) {
52 * Probably a corrupt capture file; don't blow up trying
53 * to allocate space for an immensely-large packet.
55 *err = WTAP_ERR_BAD_FILE;
56 *err_info = g_strdup_printf("ber: File has %" G_GINT64_MODIFIER "d-byte packet, bigger than maximum of %u",
57 file_size, WTAP_MAX_PACKET_SIZE);
60 packet_size = (int)file_size;
62 phdr->presence_flags = 0; /* yes, we have no bananas^Wtime stamp */
64 phdr->caplen = packet_size;
65 phdr->len = packet_size;
70 if (!wtap_read_packet_bytes(fh, buf, packet_size, err, err_info))
72 return REC_TYPE_PACKET;
75 static int ber_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
81 offset = file_tell(wth->fh);
83 /* there is only ever one packet */
87 *data_offset = offset;
89 return ber_read_file(wth, wth->fh, &wth->phdr, wth->frame_buffer, err, err_info);
92 static int ber_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr _U_,
93 Buffer *buf, int *err, gchar **err_info)
95 /* there is only one packet */
101 if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
104 return ber_read_file(wth, wth->random_fh, phdr, buf, err, err_info);
107 int ber_open(wtap *wth, int *err, gchar **err_info)
109 #define BER_BYTES_TO_CHECK 8
110 guint8 bytes[BER_BYTES_TO_CHECK];
121 bytes_read = file_read(&bytes, BER_BYTES_TO_CHECK, wth->fh);
122 if (bytes_read != BER_BYTES_TO_CHECK) {
123 *err = file_error(wth->fh, err_info);
124 if (*err != 0 && *err != WTAP_ERR_SHORT_READ)
129 ber_id = bytes[offset++];
131 ber_class = (ber_id>>6) & 0x03;
132 ber_pc = (ber_id>>5) & 0x01;
133 ber_tag = ber_id & 0x1F;
135 /* it must be constructed and either a SET or a SEQUENCE */
136 /* or a CONTEXT less than 32 (arbitrary) */
137 /* XXX: do we also want to allow APPLICATION */
139 (((ber_class == BER_CLASS_UNI) && ((ber_tag == BER_UNI_TAG_SET) || (ber_tag == BER_UNI_TAG_SEQ))) ||
140 ((ber_class == BER_CLASS_CON) && (ber_tag < 32)))))
143 /* now check the length */
144 oct = bytes[offset++];
147 /* not indefinite length encoded */
150 /* length fits into a single byte */
153 nlb = oct & 0x7F; /* number of length bytes */
155 if((nlb > 0) && (nlb <= (BER_BYTES_TO_CHECK - 2))) {
156 /* not indefinite length and we have read enough bytes to compute the length */
159 oct = bytes[offset++];
160 len = (len<<8) + oct;
165 len += (2 + nlb); /* add back Tag and Length bytes */
166 file_size = wtap_file_size(wth, err);
168 if(len != file_size) {
169 return 0; /* not ASN.1 */
172 /* Indefinite length encoded - assume it is BER */
175 /* seek back to the start of the file */
176 if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
179 wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_BER;
180 wth->file_encap = WTAP_ENCAP_BER;
181 wth->snapshot_length = 0;
183 wth->subtype_read = ber_read;
184 wth->subtype_seek_read = ber_seek_read;
185 wth->tsprecision = WTAP_FILE_TSPREC_SEC;