wiretap/mplog.c

   1 /* mplog.c
   2  *
   3  * File format support for Micropross mplog files
   4  * Copyright (c) 2016 by Martin Kaiser <martin@kaiser.cx>
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13
  14 /*
  15    The mplog file format logs the communication between a contactless
  16    smartcard and a card reader. Such files contain information about the
  17    physical layer as well as the bytes exchanged between devices.
  18    Some commercial logging and testing tools by the French company Micropross
  19    use this format.
  20
  21    The information used for implementing this wiretap module were
  22    obtained from reverse-engineering. There is no publicly available
  23    documentation of the mplog file format.
  24
  25    Mplog files start with the string "MPCSII". This string is part of
  26    the header which is in total 0x80 bytes long.
  27
  28    Following the header, the file is a sequence of 8 byte-blocks.
  29         data       (one byte)
  30         block type (one byte)
  31         timestamp  (six bytes)
  32
  33    The timestamp is a counter in little-endian format. The counter is in
  34    units of 10ns.
  35 */
  36
  37 #include "config.h"
  38 #include "mplog.h"
  39
  40 #include <string.h>
  41 #include <wtap-int.h>
  42 #include <file_wrappers.h>
  43
  44 /* the block types */
  45 #define TYPE_PCD_PICC_A  0x70
  46 #define TYPE_PICC_PCD_A  0x71
  47 #define TYPE_PCD_PICC_B  0x72
  48 #define TYPE_PICC_PCD_B  0x73
  49 #define TYPE_UNKNOWN     0xFF
  50
  51 #define KNOWN_TYPE(x) \
  52 ( \
  53   ((x) == TYPE_PCD_PICC_A) || \
  54   ((x) == TYPE_PICC_PCD_A) || \
  55   ((x) == TYPE_PCD_PICC_B) || \
  56   ((x) == TYPE_PICC_PCD_B) \
  57 )
  58
  59 #define MPLOG_BLOCK_SIZE 8
  60
  61 /* ISO14443 pseudo-header, see https://www.kaiser.cx/pcap-iso14443.html */
  62 #define ISO14443_PSEUDO_HDR_VER  0
  63 #define ISO14443_PSEUDO_HDR_LEN  4
  64 /*  the two transfer events are the types that include a trailing CRC
  65     the CRC is always present in mplog files */
  66 #define ISO14443_PSEUDO_HDR_PICC_TO_PCD  0xFF
  67 #define ISO14443_PSEUDO_HDR_PCD_TO_PICC  0xFE
  68
  69
  70 #define ISO14443_MAX_PKT_LEN    4096
  71
  72 #define PKT_BUF_LEN   (ISO14443_PSEUDO_HDR_LEN + ISO14443_MAX_PKT_LEN)
  73
  74
  75 static int mplog_file_type_subtype = -1;
  76
  77 void register_mplog(void);
  78
  79 /* read the next packet, starting at the current position of fh
  80    as we know very little about the file format, our approach is rather simple:
  81    - we read block-by-block until a known block-type is found
  82         - this block's type is the type of the next packet
  83         - this block's timestamp will become the packet's timestamp
  84         - the data byte will be our packet's first byte
  85    - we carry on reading blocks and add the data bytes
  86      of all blocks of "our" type
  87    - if a different well-known block type is found, this is the end of
  88      our packet, we go back one block so that this block can be picked
  89      up as the start of the next packet
  90    - if two blocks of our packet's block type are more than 200us apart,
  91      we treat this as a packet boundary as described above
  92    */
  93 static bool mplog_read_packet(FILE_T fh, wtap_rec *rec,
  94         Buffer *buf, int *err, char **err_info)
  95 {
  96     uint8_t *p, *start_p;
  97     /* --- the last block of a known type --- */
  98     uint64_t last_ctr = 0;
  99     /* --- the current block --- */
 100     uint8_t block[MPLOG_BLOCK_SIZE]; /* the entire block */
 101     uint8_t data, type; /* its data and block type bytes */
 102     uint64_t ctr; /* its timestamp counter */
 103     /* --- the packet we're assembling --- */
 104     int pkt_bytes = 0;
 105     uint8_t pkt_type = TYPE_UNKNOWN;
 106     /* the timestamp of the packet's first block,
 107        this will become the packet's timestamp */
 108     uint64_t pkt_ctr = 0;
 109
 110
 111     ws_buffer_assure_space(buf, PKT_BUF_LEN);
 112     p = ws_buffer_start_ptr(buf);
 113     start_p = p;
 114
 115     /* leave space for the iso14443 pseudo header
 116        we can't create it until we've seen the entire packet */
 117     p += ISO14443_PSEUDO_HDR_LEN;
 118
 119     do {
 120         if (!wtap_read_bytes_or_eof(fh, block, sizeof(block), err, err_info)) {
 121             /* If we've already read some data, if this failed with an EOF,
 122                so that *err is 0, it's a short read. */
 123             if (pkt_bytes != 0) {
 124                 if (*err == 0)
 125                     *err = WTAP_ERR_SHORT_READ;
 126             }
 127             break;
 128         }
 129         data = block[0];
 130         type = block[1];
 131         ctr = pletoh48(&block[2]);
 132
 133         if (pkt_type == TYPE_UNKNOWN) {
 134             if (KNOWN_TYPE(type)) {
 135                 pkt_type = type;
 136                 pkt_ctr = ctr;
 137             }
 138         }
 139
 140         if (type == pkt_type) {
 141             if (last_ctr != 0) {
 142                 /* if the distance to the last byte of the
 143                    same type is larger than 200us, this is very likely the
 144                    first byte of a new packet -> go back one block and exit
 145                    ctr and last_ctr are in units of 10ns
 146                    at 106kbit/s, it takes approx 75us to send one byte */
 147                 if (ctr - last_ctr > 200*100) {
 148                     file_seek(fh, -MPLOG_BLOCK_SIZE, SEEK_CUR, err);
 149                     break;
 150                 }
 151             }
 152
 153             *p++ = data;
 154             pkt_bytes++;
 155             last_ctr = ctr;
 156         }
 157         else if (KNOWN_TYPE(type)) {
 158             file_seek(fh, -MPLOG_BLOCK_SIZE, SEEK_CUR, err);
 159             break;
 160         }
 161     } while (pkt_bytes < ISO14443_MAX_PKT_LEN);
 162
 163     if (pkt_type == TYPE_UNKNOWN)
 164         return false;
 165
 166     start_p[0] = ISO14443_PSEUDO_HDR_VER;
 167
 168     if (pkt_type==TYPE_PCD_PICC_A || pkt_type==TYPE_PCD_PICC_B)
 169         start_p[1] = ISO14443_PSEUDO_HDR_PCD_TO_PICC;
 170     else
 171         start_p[1] = ISO14443_PSEUDO_HDR_PICC_TO_PCD;
 172
 173     start_p[2] = pkt_bytes >> 8;
 174     start_p[3] = pkt_bytes & 0xFF;
 175
 176     rec->rec_type = REC_TYPE_PACKET;
 177     rec->block = wtap_block_create(WTAP_BLOCK_PACKET);
 178     rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_ISO14443;
 179     rec->presence_flags = WTAP_HAS_TS | WTAP_HAS_CAP_LEN;
 180     rec->ts.secs = (time_t)((pkt_ctr*10)/(1000*1000*1000));
 181     rec->ts.nsecs = (int)((pkt_ctr*10)%(1000*1000*1000));
 182     rec->rec_header.packet_header.caplen = ISO14443_PSEUDO_HDR_LEN + pkt_bytes;
 183     rec->rec_header.packet_header.len = rec->rec_header.packet_header.caplen;
 184
 185     return true;
 186 }
 187
 188
 189 static bool
 190 mplog_read(wtap *wth, wtap_rec *rec, Buffer *buf, int *err,
 191         char **err_info, int64_t *data_offset)
 192 {
 193     *data_offset = file_tell(wth->fh);
 194
 195     return mplog_read_packet(wth->fh, rec, buf, err, err_info);
 196 }
 197
 198
 199 static bool
 200 mplog_seek_read(wtap *wth, int64_t seek_off, wtap_rec *rec, Buffer *buf,
 201                 int *err, char **err_info)
 202 {
 203     if (-1 == file_seek(wth->random_fh, seek_off, SEEK_SET, err))
 204         return false;
 205
 206     if (!mplog_read_packet(wth->random_fh, rec, buf, err, err_info)) {
 207         /* Even if we got an immediate EOF, that's an error. */
 208         if (*err == 0)
 209             *err = WTAP_ERR_SHORT_READ;
 210         return false;
 211     }
 212     return true;
 213 }
 214
 215
 216 wtap_open_return_val mplog_open(wtap *wth, int *err, char **err_info)
 217 {
 218     bool ok;
 219     uint8_t magic[6];
 220
 221     ok = wtap_read_bytes(wth->fh, magic, 6, err, err_info);
 222     if (!ok) {
 223         if (*err != WTAP_ERR_SHORT_READ)
 224             return WTAP_OPEN_ERROR;
 225         return WTAP_OPEN_NOT_MINE;
 226     }
 227     if (memcmp(magic, "MPCSII", 6) != 0)
 228         return WTAP_OPEN_NOT_MINE;
 229
 230     wth->file_encap = WTAP_ENCAP_ISO14443;
 231     wth->snapshot_length = 0;
 232     wth->file_tsprec = WTAP_TSPREC_NSEC;
 233
 234     wth->priv = NULL;
 235
 236     wth->subtype_read = mplog_read;
 237     wth->subtype_seek_read = mplog_seek_read;
 238     wth->file_type_subtype = mplog_file_type_subtype;
 239
 240     /* skip the file header */
 241     if (-1 == file_seek(wth->fh, 0x80, SEEK_SET, err))
 242         return WTAP_OPEN_ERROR;
 243
 244     *err = 0;
 245
 246     /*
 247      * Add an IDB; we don't know how many interfaces were
 248      * involved, so we just say one interface, about which
 249      * we only know the link-layer type, snapshot length,
 250      * and time stamp resolution.
 251      */
 252     wtap_add_generated_idb(wth);
 253
 254     return WTAP_OPEN_MINE;
 255 }
 256
 257 static const struct supported_block_type mplog_blocks_supported[] = {
 258     /*
 259      * We support packet blocks, with no comments or other options.
 260      */
 261     { WTAP_BLOCK_PACKET, MULTIPLE_BLOCKS_SUPPORTED, NO_OPTIONS_SUPPORTED }
 262 };
 263
 264 static const struct file_type_subtype_info mplog_info = {
 265     "Micropross mplog", "mplog", "mplog", NULL,
 266     false, BLOCKS_SUPPORTED(mplog_blocks_supported),
 267     NULL, NULL, NULL
 268 };
 269
 270 void register_mplog(void)
 271 {
 272     mplog_file_type_subtype = wtap_register_file_type_subtype(&mplog_info);
 273
 274     /*
 275      * Register name for backwards compatibility with the
 276      * wtap_filetypes table in Lua.
 277      */
 278     wtap_register_backwards_compatibility_lua_name("MPLOG",
 279                                                    mplog_file_type_subtype);
 280 }
 281
 282 /*
 283  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 284  *
 285  * Local variables:
 286  * c-basic-offset: 4
 287  * tab-width: 8
 288  * indent-tabs-mode: nil
 289  * End:
 290  *
 291  * vi: set shiftwidth=4 tabstop=8 expandtab:
 292  * :indentSize=4:tabSize=8:noTabs=true:
 293  */