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/* 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 {
guint32 af;
guint32 spi;
guint32 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 = -1;
static int hf_enc_af = -1;
static int hf_enc_spi = -1;
static int hf_enc_flags = -1;
static int hf_enc_flags_payload_enc = -1;
static int hf_enc_flags_payload_auth = -1;
static int hf_enc_flags_payload_compress = -1;
static int hf_enc_flags_header_auth = -1;
static int hf_enc_flags_reserved = -1;
static gint ett_enc = -1;
static gint ett_enc_flag = -1;
static gboolean
capture_enc(const guchar *pd, int offset _U_, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header)
{
guint32 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;
guint 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_guint32(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 gint *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:
*/
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