wiretap/candump.c

   1 /* candump.c
   2  *
   3  * Wiretap Library
   4  * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
   5  *
   6  * Support for candump log file format
   7  * Copyright (c) 2019 by Maksim Salau <maksim.salau@gmail.com>
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 #include <config.h>
  13 #include "candump.h"
  14
  15 #include <wtap-int.h>
  16 #include <file_wrappers.h>
  17 #include <wsutil/exported_pdu_tlvs.h>
  18 #include <string.h>
  19 #include <inttypes.h>
  20 #include <errno.h>
  21 #include "candump_priv.h"
  22
  23 static bool candump_read(wtap *wth, wtap_rec *rec, Buffer *buf,
  24                              int *err, char **err_info,
  25                              int64_t *data_offset);
  26 static bool candump_seek_read(wtap *wth, int64_t seek_off,
  27                                   wtap_rec *rec, Buffer *buf,
  28                                   int *err, char **err_info);
  29
  30 static int candump_file_type_subtype = -1;
  31
  32 void register_candump(void);
  33
  34 /*
  35  * This is written by the candump utility on Linux.
  36  */
  37
  38 static bool
  39 candump_gen_packet(wtap_rec *rec, Buffer *buf, const msg_t *msg, int *err,
  40                      char **err_info)
  41 {
  42     /* Generate Exported PDU tags for the packet info */
  43     ws_buffer_clean(buf);
  44
  45     if (msg->is_fd)
  46     {
  47         canfd_frame_t canfd_frame = {0};
  48
  49         /*
  50          * There's a maximum of CANFD_MAX_DLEN bytes in a CAN-FD frame.
  51          */
  52         if (msg->data.length > CANFD_MAX_DLEN) {
  53             *err = WTAP_ERR_BAD_FILE;
  54             if (err_info != NULL) {
  55                 *err_info = ws_strdup_printf("candump: File has %u-byte CAN FD packet, bigger than maximum of %u",
  56                                              msg->data.length, CANFD_MAX_DLEN);
  57             }
  58             return false;
  59         }
  60
  61         canfd_frame.can_id = g_htonl(msg->id);
  62         canfd_frame.flags  = msg->flags | CANFD_FDF;
  63         canfd_frame.len    = msg->data.length;
  64         memcpy(canfd_frame.data, msg->data.data, msg->data.length);
  65
  66         ws_buffer_append(buf, (uint8_t *)&canfd_frame, sizeof(canfd_frame));
  67     }
  68     else
  69     {
  70         can_frame_t can_frame = {0};
  71
  72         /*
  73          * There's a maximum of CAN_MAX_DLEN bytes in a CAN frame.
  74          */
  75         if (msg->data.length > CAN_MAX_DLEN) {
  76             *err = WTAP_ERR_BAD_FILE;
  77             if (err_info != NULL) {
  78                 *err_info = ws_strdup_printf("candump: File has %u-byte CAN packet, bigger than maximum of %u",
  79                                              msg->data.length, CAN_MAX_DLEN);
  80             }
  81             return false;
  82         }
  83
  84         can_frame.can_id  = g_htonl(msg->id);
  85         can_frame.can_dlc = msg->data.length;
  86         memcpy(can_frame.data, msg->data.data, msg->data.length);
  87
  88         ws_buffer_append(buf, (uint8_t *)&can_frame, sizeof(can_frame));
  89     }
  90
  91     rec->rec_type       = REC_TYPE_PACKET;
  92     rec->block          = wtap_block_create(WTAP_BLOCK_PACKET);
  93     rec->presence_flags = WTAP_HAS_TS;
  94     rec->ts             = msg->ts;
  95     rec->tsprec         = WTAP_TSPREC_USEC;
  96
  97     rec->rec_header.packet_header.caplen = (uint32_t)ws_buffer_length(buf);
  98     rec->rec_header.packet_header.len    = (uint32_t)ws_buffer_length(buf);
  99
 100     return true;
 101 }
 102
 103 static bool
 104 candump_parse(FILE_T fh, msg_t *msg, int64_t *offset, int *err, char **err_info)
 105 {
 106     candump_state_t state = {0};
 107     bool            ok;
 108     int64_t         seek_off;
 109
 110 #ifdef CANDUMP_DEBUG
 111     candump_debug_printf("%s: Trying candump file decoder\n", G_STRFUNC);
 112 #endif
 113
 114     state.fh = fh;
 115
 116     do
 117     {
 118         if (file_eof(fh))
 119             return false;
 120
 121         seek_off = file_tell(fh);
 122 #ifdef CANDUMP_DEBUG
 123         candump_debug_printf("%s: Starting parser at offset %" PRIi64 "\n", G_STRFUNC, seek_off);
 124 #endif
 125         state.file_bytes_read = 0;
 126         ok = run_candump_parser(&state, err, err_info);
 127
 128         /* Rewind the file to the offset we have finished parsing */
 129         if (file_seek(fh, seek_off + state.file_bytes_read, SEEK_SET, err) == -1)
 130         {
 131             g_free(*err_info);
 132             *err      = errno;
 133             *err_info = g_strdup(g_strerror(errno));
 134             return false;
 135         }
 136     }
 137     while (ok && !state.is_msg_valid);
 138
 139     if (!ok)
 140         return false;
 141
 142 #ifdef CANDUMP_DEBUG
 143     candump_debug_printf("%s: Success\n", G_STRFUNC);
 144 #endif
 145
 146     if (offset)
 147         *offset = seek_off;
 148
 149     if (msg)
 150         *msg = state.msg;
 151
 152     return true;
 153 }
 154
 155 wtap_open_return_val
 156 candump_open(wtap *wth, int *err, char **err_info)
 157 {
 158     if (!candump_parse(wth->fh, NULL, NULL, err, err_info))
 159     {
 160         g_free(*err_info);
 161
 162         *err      = 0;
 163         *err_info = NULL;
 164
 165         return WTAP_OPEN_NOT_MINE;
 166     }
 167
 168 #ifdef CANDUMP_DEBUG
 169     candump_debug_printf("%s: This is our file\n", G_STRFUNC);
 170 #endif
 171
 172     if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
 173     {
 174         *err      = errno;
 175         *err_info = g_strdup(g_strerror(errno));
 176
 177         return WTAP_OPEN_ERROR;
 178     }
 179
 180     wth->priv              = NULL;
 181     wth->file_type_subtype = candump_file_type_subtype;
 182     wth->file_encap        = WTAP_ENCAP_SOCKETCAN;
 183     wth->file_tsprec       = WTAP_TSPREC_USEC;
 184     wth->subtype_read      = candump_read;
 185     wth->subtype_seek_read = candump_seek_read;
 186
 187     return WTAP_OPEN_MINE;
 188 }
 189
 190 static bool
 191 candump_read(wtap *wth, wtap_rec *rec, Buffer *buf, int *err, char **err_info,
 192              int64_t *data_offset)
 193 {
 194     msg_t msg;
 195
 196 #ifdef CANDUMP_DEBUG
 197     candump_debug_printf("%s: Try reading at offset %" PRIi64 "\n", G_STRFUNC, file_tell(wth->fh));
 198 #endif
 199
 200     if (!candump_parse(wth->fh, &msg, data_offset, err, err_info))
 201         return false;
 202
 203 #ifdef CANDUMP_DEBUG
 204     candump_debug_printf("%s: Stopped at offset %" PRIi64 "\n", G_STRFUNC, file_tell(wth->fh));
 205 #endif
 206
 207     return candump_gen_packet(rec, buf, &msg, err, err_info);
 208 }
 209
 210 static bool
 211 candump_seek_read(wtap *wth , int64_t seek_off, wtap_rec *rec,
 212                   Buffer *buf, int *err, char **err_info)
 213 {
 214     msg_t msg;
 215
 216 #ifdef CANDUMP_DEBUG
 217     candump_debug_printf("%s: Read at offset %" PRIi64 "\n", G_STRFUNC, seek_off);
 218 #endif
 219
 220     if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
 221     {
 222         *err      = errno;
 223         *err_info = g_strdup(g_strerror(errno));
 224
 225         return false;
 226     }
 227
 228     if (!candump_parse(wth->random_fh, &msg, NULL, err, err_info))
 229         return false;
 230
 231     return candump_gen_packet(rec, buf, &msg, err, err_info);
 232 }
 233
 234 static const struct supported_block_type candump_blocks_supported[] = {
 235     /*
 236      * We support packet blocks, with no comments or other options.
 237      */
 238     { WTAP_BLOCK_PACKET, MULTIPLE_BLOCKS_SUPPORTED, NO_OPTIONS_SUPPORTED }
 239 };
 240
 241 static const struct file_type_subtype_info candump_info = {
 242     "Linux candump file", "candump", NULL, NULL,
 243     false, BLOCKS_SUPPORTED(candump_blocks_supported),
 244     NULL, NULL, NULL
 245 };
 246
 247 void register_candump(void)
 248 {
 249     candump_file_type_subtype = wtap_register_file_type_subtype(&candump_info);
 250 }
 251
 252 /*
 253  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 254  *
 255  * Local variables:
 256  * c-basic-offset: 4
 257  * tab-width: 8
 258  * indent-tabs-mode: nil
 259  * End:
 260  *
 261  * vi: set shiftwidth=4 tabstop=8 expandtab:
 262  * :indentSize=4:tabSize=8:noTabs=true:
 263  */