/* packet-enc.c

 *

 * Copyright (c) 2003 Markus Friedl.  All rights reserved.

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/capture_dissectors.h>

#include <epan/aftypes.h>

#include <wsutil/pint.h>

void proto_register_enc(void);

void proto_reg_handoff_enc(void);

static dissector_handle_t enc_handle;

static capture_dissector_handle_t enc_cap_handle;

/* The header in OpenBSD Encapsulating Interface files. */

struct enchdr {

  uint32_t af;

  uint32_t spi;

  uint32_t flags;

};

#define BSD_ENC_HDRLEN    12

#define BSD_ENC_M_CONF          0x00000400  /* payload encrypted */

#define BSD_ENC_M_AUTH          0x00000800  /* payload authenticated */

#define BSD_ENC_M_COMP          0x00001000  /* payload compressed */

#define BSD_ENC_M_AUTH_AH       0x00002000  /* header authenticated */

#define BSD_ENC_M_RESERVED      0xFFFFC3FF  /* Reserved/unused flags */

static dissector_table_t enc_dissector_table;

/* header fields */

static int proto_enc;

static int hf_enc_af;

static int hf_enc_spi;

static int hf_enc_flags;

static int hf_enc_flags_payload_enc;

static int hf_enc_flags_payload_auth;

static int hf_enc_flags_payload_compress;

static int hf_enc_flags_header_auth;

static int hf_enc_flags_reserved;

static int ett_enc;

static int ett_enc_flag;

static bool

capture_enc(const unsigned char *pd, int offset _U_, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header)

{

  uint32_t af;

  if (!BYTES_ARE_IN_FRAME(0, len, BSD_ENC_HDRLEN))

    return false;

  memcpy((char *)&af, (const char *)&pd[0], sizeof(af));

  if ((af & 0xFFFF0000) != 0) {

    /*

     * BSD AF_ types will always have the upper 16 bits as 0, so if any

     * of them are non-zero, the af field must be byte-swapped, and

     * will, at least in DLT_ENC headers, always have at least one of

     * the lower 16 bits not being 0 (it won't be AF_UNSPEC, which is

     * 0), so if the af field is byte-swapped, at least one of the

     * upper 16 bits will be 0.

     */

    af = GUINT32_SWAP_LE_BE(af);

  }

  return try_capture_dissector("enc", af, pd, BSD_ENC_HDRLEN, len, cpinfo, pseudo_header);

}

static const value_string af_vals[] = {

  { BSD_AF_INET,  "IPv4" },

  { BSD_AF_INET6_BSD, "IPv6" },

  { 0, NULL }

};

static int

dissect_enc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

  struct enchdr  ench;

  unsigned       writer_encoding;

  tvbuff_t      *next_tvb;

  proto_tree    *enc_tree;

  proto_item    *ti;

  static int * const flags[] = {

    &hf_enc_flags_payload_enc,

    &hf_enc_flags_payload_auth,

    &hf_enc_flags_payload_compress,

    &hf_enc_flags_header_auth,

    &hf_enc_flags_reserved,

    NULL

  };

  col_set_str(pinfo->cinfo, COL_PROTOCOL, "ENC");

  /*

   * Initially assume the file was written by a host with our byte order.

   */

  writer_encoding = ENC_HOST_ENDIAN;

  ench.af = tvb_get_h_uint32(tvb, 0);

  if ((ench.af & 0xFFFF0000) != 0) {

    /*

     * BSD AF_ types will always have the upper 16 bits as 0, so if any

     * of them are non-zero, the af field must be byte-swapped, and

     * will, at least in DLT_ENC headers, always have at least one of

     * the lower 16 bits not being 0 (it won't be AF_UNSPEC, which is

     * 0), so if the af field is byte-swapped, at least one of the

     * upper 16 bits will be 0.

     */

    ench.af = GUINT32_SWAP_LE_BE(ench.af);

    /*

     * It was written by a host with the *opposite* byte order.

     */

    writer_encoding = ENC_ANTI_HOST_ENDIAN;

  }

  ench.spi = tvb_get_ntohl(tvb, 4);

  if (tree) {

    ti = proto_tree_add_protocol_format(tree, proto_enc, tvb, 0,

                                        BSD_ENC_HDRLEN,

                                        "Enc %s, SPI 0x%8.8x",

                                        val_to_str(ench.af, af_vals, "unknown (%u)"),

                                        ench.spi);

    enc_tree = proto_item_add_subtree(ti, ett_enc);

    proto_tree_add_item(enc_tree, hf_enc_af, tvb, 0, 4, writer_encoding);

    proto_tree_add_item(enc_tree, hf_enc_spi, tvb, 4, 4, ENC_BIG_ENDIAN);

    proto_tree_add_bitmask(enc_tree, tvb, 8, hf_enc_flags, ett_enc_flag, flags, writer_encoding);

  }

  /* Set the tvbuff for the payload after the header */

  next_tvb = tvb_new_subset_remaining(tvb, BSD_ENC_HDRLEN);

  if (!dissector_try_uint(enc_dissector_table, ench.af, next_tvb, pinfo, tree))

    call_data_dissector(next_tvb, pinfo, tree);

  return tvb_captured_length(tvb);

}

void

proto_register_enc(void)

{

  static hf_register_info hf[] = {

    { &hf_enc_af,

      { "Address Family", "enc.af", FT_UINT32, BASE_DEC, VALS(af_vals), 0x0,

        "Protocol (IPv4 vs IPv6)", HFILL }},

    { &hf_enc_spi,

      { "SPI", "enc.spi", FT_UINT32, BASE_HEX, NULL, 0x0,

        "Security Parameter Index", HFILL }},

    { &hf_enc_flags,

      { "Flags", "enc.flags", FT_UINT32, BASE_HEX, NULL, 0x0,

        "ENC flags", HFILL }},

    { &hf_enc_flags_payload_enc,

      { "Payload encrypted", "enc.flags.payload_enc", FT_BOOLEAN, 32, NULL, BSD_ENC_M_CONF,

        NULL, HFILL }},

    { &hf_enc_flags_payload_auth,

      { "Payload authenticated", "enc.flags.payload_auth", FT_BOOLEAN, 32, NULL, BSD_ENC_M_AUTH,

        NULL, HFILL }},

    { &hf_enc_flags_payload_compress,

      { "Payload compressed", "enc.flags.payload_compress", FT_BOOLEAN, 32, NULL, BSD_ENC_M_COMP,

        NULL, HFILL }},

    { &hf_enc_flags_header_auth,

      { "Header authenticated", "enc.flags.header_auth", FT_BOOLEAN, 32, NULL, BSD_ENC_M_AUTH_AH,

        NULL, HFILL }},

    { &hf_enc_flags_reserved,

      { "Reserved", "enc.flags.reserved", FT_UINT32, BASE_HEX, NULL, BSD_ENC_M_RESERVED,

        NULL, HFILL }},

  };

  static int *ett[] =

  {

      &ett_enc,

      &ett_enc_flag

  };

  proto_enc = proto_register_protocol("OpenBSD Encapsulating device",

                                      "ENC", "enc");

  proto_register_field_array(proto_enc, hf, array_length(hf));

  proto_register_subtree_array(ett, array_length(ett));

  enc_dissector_table = register_dissector_table("enc", "OpenBSD Encapsulating device", proto_enc, FT_UINT32, BASE_DEC);

  register_capture_dissector_table("enc", "ENC");

  enc_handle  = register_dissector("enc", dissect_enc, proto_enc);

  enc_cap_handle = register_capture_dissector("enc", capture_enc, proto_enc);

}

void

proto_reg_handoff_enc(void)

{

  dissector_add_uint("wtap_encap", WTAP_ENCAP_ENC, enc_handle);

  capture_dissector_add_uint("wtap_encap", WTAP_ENCAP_ENC, enc_cap_handle);

}

/*

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

 *

 * Local Variables:

 * c-basic-offset: 2

 * tab-width: 8

 * indent-tabs-mode: nil

 * End:

 *

 * ex: set shiftwidth=2 tabstop=8 expandtab:

 * :indentSize=2:tabSize=8:noTabs=true:

 */