/* eyesdn.c

 *

 * Wiretap Library

 * Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 */

#include "config.h"

#include "eyesdn.h"

#include "wtap_module.h"

#include "file_wrappers.h"

#include <stdlib.h>

#include <string.h>

#include <wsutil/pint.h>

static int eyesdn_file_type_subtype = -1;

void register_eyesdn(void);

/* This module reads the output of the EyeSDN USB S0/E1 ISDN probes

 * They store HDLC frames of D and B channels in a binary format

 * The fileformat is

 *

 * 1-6 Byte: EyeSDN - Magic

 * 7-n Byte: Frames

 *

 * Each Frame starts with the 0xff Flag byte

 * - Bytes 0-2: timestamp (usec in network byte order)

 * - Bytes 3-7: timestamp (40bits sec since 1970 in network byte order)

 * - Byte 8: channel (0 for D channel, 1-30 for B1-B30)

 * - Byte 9: Sender Bit 0(0 NT, 1 TE), Protocol in Bits 7:1, see enum

 * - Byte 10-11: frame size in bytes

 * - Byte 12-n: Frame Payload

 *

 * All multibyte values are represented in network byte order

 * The frame is terminated with a flag character (0xff)

 * bytes 0xff within a frame are escaped using the 0xfe escape character

 * the byte following the escape character is decremented by two:

 * so 0xfe 0xfd is actually a 0xff

 * Characters that need to be escaped are 0xff and 0xfe

 */

static bool esc_read(FILE_T fh, uint8_t *buf, int len, int *err, char **err_info)

{

  int i;

  int value;

  for(i=0; i<len; i++) {

    value=file_getc(fh);

    if(value==-1) {

      /* EOF or error */

      *err=file_error(fh, err_info);

      if(*err==0)

        *err=WTAP_ERR_SHORT_READ;

      return false;

    }

    if(value==0xff) {

      /* error !!, read into next frame */

      *err=WTAP_ERR_BAD_FILE;

      *err_info=g_strdup("eyesdn: No flag character seen in frame");

      return false;

    }

    if(value==0xfe) {

      /* we need to escape */

      value=file_getc(fh);

      if(value==-1) {

        /* EOF or error */

        *err=file_error(fh, err_info);

        if(*err==0)

          *err=WTAP_ERR_SHORT_READ;

        return false;

      }

      value+=2;

    }

    buf[i]=value;

  }

  return true;

}

static bool esc_read_append_buffer(FILE_T fh, Buffer *buf, int len, int *err, char **err_info)

{

  /* Make sure we have enough room for the data */

  ws_buffer_assure_space(buf, len);

  if (!esc_read(fh, ws_buffer_end_ptr(buf), len, err, err_info))

    return false;

  ws_buffer_increase_length(buf, len);

  return true;

}

/* Magic text to check for eyesdn-ness of file */

static const unsigned char eyesdn_hdr_magic[]  =

{ 'E', 'y', 'e', 'S', 'D', 'N'};

#define EYESDN_HDR_MAGIC_SIZE  sizeof(eyesdn_hdr_magic)

/* Size of a record header */

#define EYESDN_HDR_LENGTH   12

static bool eyesdn_read(wtap *wth, wtap_rec *rec,

  int *err, char **err_info, int64_t *data_offset);

static bool eyesdn_seek_read(wtap *wth, int64_t seek_off,

  wtap_rec *rec, int *err, char **err_info);

static bool read_eyesdn_rec(FILE_T fh, wtap_rec *rec,

  int *err, char **err_info);

/* Seeks to the beginning of the next packet, and returns the

   byte offset.  Returns -1 on failure, and sets "*err" to the error

   and "*err_info" to null or an additional error string. */

static int64_t eyesdn_seek_next_packet(wtap *wth, int *err, char **err_info)

{

  int byte;

  int64_t cur_off;

  while ((byte = file_getc(wth->fh)) != EOF) {

    if (byte == 0xff) {

      cur_off = file_tell(wth->fh);

      if (cur_off == -1) {

        /* Error. */

        *err = file_error(wth->fh, err_info);

        return -1;

      }

      return cur_off;

    }

  }

  /* EOF or error. */

  *err = file_error(wth->fh, err_info);

  return -1;

}

wtap_open_return_val eyesdn_open(wtap *wth, int *err, char **err_info)

{

  char  magic[EYESDN_HDR_MAGIC_SIZE];

  /* Look for eyesdn header */

  if (!wtap_read_bytes(wth->fh, &magic, sizeof magic, err, err_info)) {

    if (*err != WTAP_ERR_SHORT_READ)

      return WTAP_OPEN_ERROR;

    return WTAP_OPEN_NOT_MINE;

  }

  if (memcmp(magic, eyesdn_hdr_magic, EYESDN_HDR_MAGIC_SIZE) != 0)

    return WTAP_OPEN_NOT_MINE;

  wth->file_encap = WTAP_ENCAP_PER_PACKET;

  wth->file_type_subtype = eyesdn_file_type_subtype;

  wth->snapshot_length = 0; /* not known */

  wth->subtype_read = eyesdn_read;

  wth->subtype_seek_read = eyesdn_seek_read;

  wth->file_tsprec = WTAP_TSPREC_USEC;

  return WTAP_OPEN_MINE;

}

/* Find the next record and parse it; called from wtap_read(). */

static bool eyesdn_read(wtap *wth, wtap_rec *rec,

    int *err, char **err_info, int64_t *data_offset)

{

  int64_t offset;

  /* Find the next record */

  offset = eyesdn_seek_next_packet(wth, err, err_info);

  if (offset < 1)

    return false;

  *data_offset = offset;

  /* Parse the record */

  return read_eyesdn_rec(wth->fh, rec, err, err_info);

}

/* Used to read packets in random-access fashion */

static bool

eyesdn_seek_read(wtap *wth, int64_t seek_off, wtap_rec *rec,

  int *err, char **err_info)

{

  if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)

    return false;

  return read_eyesdn_rec(wth->random_fh, rec, err, err_info);

}

/* Parses a record. */

static bool

read_eyesdn_rec(FILE_T fh, wtap_rec *rec, int *err, char **err_info)

{

  union wtap_pseudo_header *pseudo_header = &rec->rec_header.packet_header.pseudo_header;

  uint8_t   hdr[EYESDN_HDR_LENGTH];

  time_t    secs;

  int   usecs;

  unsigned  pkt_len;

  uint8_t   channel, direction;

  /* Our file pointer should be at the summary information header

   * for a packet. Read in that header and extract the useful

   * information.

   */

  if (!esc_read(fh, hdr, EYESDN_HDR_LENGTH, err, err_info))

    return false;

  wtap_setup_packet_rec(rec, WTAP_ENCAP_UNKNOWN);

  rec->block = wtap_block_create(WTAP_BLOCK_PACKET);

  /* extract information from header */

  usecs = pntohu24(&hdr[0]);

  secs = pntohu40(&hdr[3]);

  channel = hdr[8];

  direction = hdr[9];

  pkt_len = pntohu16(&hdr[10]);

  switch(direction >> 1) {

  default:

  case EYESDN_ENCAP_ISDN: /* ISDN */

    pseudo_header->isdn.uton = direction & 1;

    pseudo_header->isdn.channel = channel;

    if(channel) { /* bearer channels */

      rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_ISDN; /* recognises PPP */

      pseudo_header->isdn.uton=!pseudo_header->isdn.uton; /* bug */

    } else { /* D channel */

      rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_ISDN;

    }

    break;

  case EYESDN_ENCAP_MSG: /* Layer 1 message */

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_LAYER1_EVENT;

    pseudo_header->l1event.uton = (direction & 1);

    break;

  case EYESDN_ENCAP_LAPB: /* X.25 via LAPB */

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_LAPB;

    pseudo_header->dte_dce.flags = (direction & 1) ? 0 : 0x80;

    break;

  case EYESDN_ENCAP_ATM: { /* ATM cells */

#define CELL_LEN 53

    unsigned char cell[CELL_LEN];

    int64_t cur_off;

    if(pkt_len != CELL_LEN) {

      *err = WTAP_ERR_BAD_FILE;

      *err_info = ws_strdup_printf(

          "eyesdn: ATM cell has a length != 53 (%u)",

          pkt_len);

      return false;

    }

    cur_off = file_tell(fh);

    if (!esc_read(fh, cell, CELL_LEN, err, err_info))

      return false;

    if (file_seek(fh, cur_off, SEEK_SET, err) == -1)

      return false;

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_ATM_PDUS_UNTRUNCATED;

    pseudo_header->atm.flags=ATM_RAW_CELL;

    pseudo_header->atm.aal=AAL_UNKNOWN;

    pseudo_header->atm.type=TRAF_UMTS_FP;

    pseudo_header->atm.subtype=TRAF_ST_UNKNOWN;

    pseudo_header->atm.vpi=((cell[0]&0xf)<<4) + (cell[0]&0xf);

    pseudo_header->atm.vci=((cell[0]&0xf)<<4) + cell[0]; /* from cell */

    pseudo_header->atm.channel=direction & 1;

    }

    break;

  case EYESDN_ENCAP_MTP2: /* SS7 frames */

    pseudo_header->mtp2.sent = direction & 1;

    pseudo_header->mtp2.annex_a_used = MTP2_ANNEX_A_USED_UNKNOWN;

    pseudo_header->mtp2.link_number = channel;

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_MTP2_WITH_PHDR;

    break;

  case EYESDN_ENCAP_DPNSS: /* DPNSS */

    pseudo_header->isdn.uton = direction & 1;

    pseudo_header->isdn.channel = channel;

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_DPNSS;

    break;

  case EYESDN_ENCAP_DASS2: /* DASS2 frames */

    pseudo_header->isdn.uton = direction & 1;

    pseudo_header->isdn.channel = channel;

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_DPNSS;

    break;

  case EYESDN_ENCAP_BACNET: /* BACNET async over HDLC frames */

          pseudo_header->isdn.uton = direction & 1;

    pseudo_header->isdn.channel = channel;

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_BACNET_MS_TP_WITH_PHDR;

    break;

  case EYESDN_ENCAP_V5_EF: /* V5EF */

    pseudo_header->isdn.uton = direction & 1;

    pseudo_header->isdn.channel = channel;

    rec->rec_header.packet_header.pkt_encap = WTAP_ENCAP_V5_EF;

    break;

  }

  if(pkt_len > WTAP_MAX_PACKET_SIZE_STANDARD) {

    *err = WTAP_ERR_BAD_FILE;

    *err_info = ws_strdup_printf("eyesdn: File has %u-byte packet, bigger than maximum of %u",

        pkt_len, WTAP_MAX_PACKET_SIZE_STANDARD);

    return false;

  }

  rec->presence_flags = WTAP_HAS_TS;

  rec->ts.secs = secs;

  rec->ts.nsecs = usecs * 1000;

  rec->rec_header.packet_header.caplen = pkt_len;

  rec->rec_header.packet_header.len = pkt_len;

  return esc_read_append_buffer(fh, &rec->data, pkt_len, err, err_info);

}

static bool

esc_write(wtap_dumper *wdh, const uint8_t *buf, int len, int *err)

{

  int i;

  uint8_t byte;

  static const uint8_t esc = 0xfe;

  for(i=0; i<len; i++) {

    byte=buf[i];

    if(byte == 0xff || byte == 0xfe) {

      /*

       * Escape the frame delimiter and escape byte.

       */

      if (!wtap_dump_file_write(wdh, &esc, sizeof esc, err))

        return false;

      byte-=2;

    }

    if (!wtap_dump_file_write(wdh, &byte, sizeof byte, err))

      return false;

  }

  return true;

}

static bool eyesdn_dump(wtap_dumper *wdh, const wtap_rec *rec,

      int *err, char **err_info);

static bool eyesdn_dump_open(wtap_dumper *wdh, int *err, char **err_info _U_)

{

  wdh->subtype_write=eyesdn_dump;

  if (!wtap_dump_file_write(wdh, eyesdn_hdr_magic,

      EYESDN_HDR_MAGIC_SIZE, err))

    return false;

  *err=0;

  return true;

}

static int eyesdn_dump_can_write_encap(int encap)

{

  switch (encap) {

  case WTAP_ENCAP_ISDN:

  case WTAP_ENCAP_LAYER1_EVENT:

  case WTAP_ENCAP_DPNSS:

  case WTAP_ENCAP_ATM_PDUS_UNTRUNCATED:

  case WTAP_ENCAP_LAPB:

  case WTAP_ENCAP_MTP2_WITH_PHDR:

  case WTAP_ENCAP_BACNET_MS_TP_WITH_PHDR:

  case WTAP_ENCAP_PER_PACKET:

    return 0;

  default:

    return WTAP_ERR_UNWRITABLE_ENCAP;

  }

}

/* Write a record for a packet to a dump file.

 *    Returns true on success, false on failure. */

static bool eyesdn_dump(wtap_dumper *wdh, const wtap_rec *rec,

      int *err, char **err_info _U_)

{

  static const uint8_t start_flag = 0xff;

  const union wtap_pseudo_header *pseudo_header = &rec->rec_header.packet_header.pseudo_header;

  uint8_t buf[EYESDN_HDR_LENGTH];

  int usecs;

  time_t secs;

  int channel;

  int origin;

  int protocol;

  int size;

  /* We can only write packet records. */

  if (rec->rec_type != REC_TYPE_PACKET) {

    *err = WTAP_ERR_UNWRITABLE_REC_TYPE;

    *err_info = wtap_unwritable_rec_type_err_string(rec);

    return false;

  }

  /* Don't write out anything bigger than we can read.

   * (The length field in packet headers is 16 bits, which

   * imposes a hard limit.) */

  if (rec->rec_header.packet_header.caplen > 65535) {

    *err = WTAP_ERR_PACKET_TOO_LARGE;

    return false;

  }

  usecs=rec->ts.nsecs/1000;

  secs=rec->ts.secs;

  size=rec->rec_header.packet_header.caplen;

  origin = pseudo_header->isdn.uton;

  channel = pseudo_header->isdn.channel;

  switch(rec->rec_header.packet_header.pkt_encap) {

  case WTAP_ENCAP_ISDN:

    protocol=EYESDN_ENCAP_ISDN; /* set depending on decoder format and mode */

    break;

  case WTAP_ENCAP_LAYER1_EVENT:

    protocol=EYESDN_ENCAP_MSG;

    break;

  case WTAP_ENCAP_DPNSS:

    protocol=EYESDN_ENCAP_DPNSS;

    break;

#if 0

  case WTAP_ENCAP_DASS2:

    protocol=EYESDN_ENCAP_DASS2;

    break;

#endif

  case WTAP_ENCAP_ATM_PDUS_UNTRUNCATED:

    protocol=EYESDN_ENCAP_ATM;

    channel=0x80;

    break;

  case WTAP_ENCAP_LAPB:

    protocol=EYESDN_ENCAP_LAPB;

    break;

  case WTAP_ENCAP_MTP2_WITH_PHDR:

    protocol=EYESDN_ENCAP_MTP2;

    break;

  case WTAP_ENCAP_BACNET_MS_TP_WITH_PHDR:

    protocol=EYESDN_ENCAP_BACNET;

    break;

  case WTAP_ENCAP_V5_EF:

    protocol=EYESDN_ENCAP_V5_EF;

    break;

  default:

    *err=WTAP_ERR_UNWRITABLE_ENCAP;

    return false;

  }

  phtonu24(&buf[0], usecs);       /* 0-2 */

  phtonu40(&buf[3], secs);          /* 3-7 */

  phtonu8(&buf[8], channel);        /* 8 */

  phtonu8(&buf[9], (origin?1:0) + (protocol << 1)); /* 9 */

  phtonu16(&buf[10], size);       /* 10-11 */

  /* start flag */

  if (!wtap_dump_file_write(wdh, &start_flag, sizeof start_flag, err))

    return false;

  if (!esc_write(wdh, buf, 12, err))

    return false;

  if (!esc_write(wdh, ws_buffer_start_ptr(&rec->data), size, err))

    return false;

  return true;

}

static const struct supported_block_type eyesdn_blocks_supported[] = {

  /*

   * We support packet blocks, with no comments or other options.

   */

  { WTAP_BLOCK_PACKET, MULTIPLE_BLOCKS_SUPPORTED, NO_OPTIONS_SUPPORTED }

};

static const struct file_type_subtype_info eyesdn_info = {

  "EyeSDN USB S0/E1 ISDN trace format", "eyesdn", "trc", NULL,

  false, BLOCKS_SUPPORTED(eyesdn_blocks_supported),

  eyesdn_dump_can_write_encap, eyesdn_dump_open, NULL

};

void register_eyesdn(void)

{

  eyesdn_file_type_subtype = wtap_register_file_type_subtype(&eyesdn_info);

  /*

   * Register name for backwards compatibility with the

   * wtap_filetypes table in Lua.

   */

  wtap_register_backwards_compatibility_lua_name("EYESDN",

      eyesdn_file_type_subtype);

}

/*

 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html

 *

 * Local variables:

 * c-basic-offset: 8

 * tab-width: 8

 * indent-tabs-mode: t

 * End:

 *

 * vi: set shiftwidth=8 tabstop=8 noexpandtab:

 * :indentSize=8:tabSize=8:noTabs=false:

 */