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/* packet-ms-nns.c
* Routines for .NET NegotiateStream Protocol (MS-NNS) dissection
* Copyright 2020, Uli Heilmeier <uh@heilmeier.eu>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wieshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* Basic dissector for .NET NegotiateStream Protocol based on protocol reference found at
* https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-NNS/%5bMS-NNS%5d.pdf
*/
#include <config.h>
#include <epan/packet.h>
#include <epan/conversation.h>
/* Prototypes */
void proto_reg_handoff_nns(void);
void proto_register_nns(void);
static dissector_handle_t gssapi_handle;
#define MS_NNS_MESSAGE_HANDSHAKE_DONE 20
#define MS_NNS_MESSAGE_HANDSHAKE_ERROR 21
#define MS_NNS_MESSAGE_HANDSHAKE_PROGRESS 22
static const value_string nns_message_id_vals[] = {
{ MS_NNS_MESSAGE_HANDSHAKE_DONE, "Handshake Done" },
{ MS_NNS_MESSAGE_HANDSHAKE_ERROR, "Handshake Error" },
{ MS_NNS_MESSAGE_HANDSHAKE_PROGRESS, "Handshake In Progress" },
{ 0, NULL}
};
struct nns_session_state {
uint32_t handshake_done;
bool first_handshake_done;
};
static int proto_nns;
static int hf_nns_message_id;
static int hf_nns_major_version;
static int hf_nns_minor_version;
static int hf_nns_auth_payload_size;
static int hf_nns_auth_payload;
static int hf_nns_payload_size;
static int hf_nns_payload;
static int ett_nns;
static int ett_nns_payload;
#define MS_NNS_MIN_LENGTH 4
static int
dissect_nns(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_item *ti, *pti;
proto_tree *nns_tree, *payload_tree;
unsigned offset = 0;
uint32_t message_id;
uint32_t payload_size;
conversation_t *conversation;
tvbuff_t *nt_tvb;
int remaining;
struct nns_session_state *session_state;
if (tvb_reported_length(tvb) < MS_NNS_MIN_LENGTH)
return 0;
conversation = find_or_create_conversation(pinfo);
session_state = (struct nns_session_state *)conversation_get_proto_data(conversation, proto_nns);
if (!session_state) {
session_state = wmem_new0(wmem_file_scope(), struct nns_session_state);
conversation_add_proto_data(conversation, proto_nns, session_state);
}
col_set_str(pinfo->cinfo, COL_PROTOCOL, "MS-NNS");
col_clear(pinfo->cinfo, COL_INFO);
ti = proto_tree_add_item(tree, proto_nns, tvb, 0, -1, ENC_NA);
nns_tree = proto_item_add_subtree(ti, ett_nns);
/* As it is unknown if there is a one-way Handshake Done or a two-way Handshake Done we check the first frame
* after the first Handshake Done if it looks like a Handshake Done message (0x140100). */
if ( session_state->handshake_done && session_state->handshake_done < pinfo->num &&
!(session_state->first_handshake_done && tvb_get_ntoh24(tvb, offset) == 0x140100)) {
proto_tree_add_item_ret_uint(nns_tree, hf_nns_payload_size, tvb, offset, 4, ENC_LITTLE_ENDIAN, &payload_size);
offset += 4;
col_append_str(pinfo->cinfo, COL_INFO, "Data");
if ( payload_size > 0) {
remaining = tvb_reported_length_remaining(tvb, offset);
if ((uint32_t) remaining < payload_size) {
pinfo->desegment_offset = offset - 4;
pinfo->desegment_len = payload_size - remaining;
return (offset - 4);
}
proto_tree_add_item(nns_tree, hf_nns_payload, tvb, offset, payload_size, ENC_NA);
offset += payload_size;
session_state->first_handshake_done = false;
}
}
else {
proto_tree_add_item_ret_uint(nns_tree, hf_nns_message_id, tvb, offset, 1, ENC_NA, &message_id);
offset += 1;
col_append_sep_fstr(pinfo->cinfo, COL_INFO, ", ", "%s", val_to_str_const(message_id, nns_message_id_vals, "Unknown Record"));
proto_tree_add_item(nns_tree, hf_nns_major_version, tvb, offset, 1, ENC_NA);
offset += 1;
proto_tree_add_item(nns_tree, hf_nns_minor_version, tvb, offset, 1, ENC_NA);
offset += 1;
proto_tree_add_item_ret_uint(nns_tree, hf_nns_auth_payload_size, tvb, offset, 2, ENC_BIG_ENDIAN, &payload_size);
offset += 2;
if ( payload_size > 0) {
if ((uint32_t) tvb_reported_length_remaining(tvb, offset) < payload_size) {
pinfo->desegment_offset = offset - 5;
pinfo->desegment_len = payload_size;
return (offset - 5);
}
pti = proto_tree_add_item(nns_tree, hf_nns_auth_payload, tvb, offset, payload_size, ENC_NA);
if (message_id == MS_NNS_MESSAGE_HANDSHAKE_DONE || message_id == MS_NNS_MESSAGE_HANDSHAKE_PROGRESS) {
nt_tvb = tvb_new_subset_length(tvb, offset, payload_size);
payload_tree = proto_item_add_subtree(pti, ett_nns_payload);
call_dissector(gssapi_handle, nt_tvb, pinfo, payload_tree);
}
offset += payload_size;
}
if ( message_id == MS_NNS_MESSAGE_HANDSHAKE_DONE) {
session_state->handshake_done = pinfo->num;
session_state->first_handshake_done = (session_state->first_handshake_done ? false : true);
}
}
return offset;
}
void proto_register_nns(void)
{
static hf_register_info hf[] = {
{ &hf_nns_message_id,
{ "MessageID", "ms-nns.message_id",
FT_UINT8, BASE_DEC, VALS(nns_message_id_vals), 0x0,
NULL, HFILL }
},
{ &hf_nns_major_version,
{ "Major Version", "ms-nns.major_version",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_nns_minor_version,
{ "Minor Version", "ms-nns.minor_version",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_nns_auth_payload_size,
{ "Auth Payload Size", "ms-nns.auth_payload_size",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_nns_auth_payload,
{ "Auth Payload", "ms-nns.known_encoding",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_nns_payload_size,
{ "Payload Size", "ms-nns.payload_size",
FT_UINT32, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_nns_payload,
{ "Payload", "ms-nns.payload",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
}
};
static int *ett[] = {
&ett_nns,
&ett_nns_payload
};
proto_nns = proto_register_protocol(".NET NegotiateStream Protocol", "MS-NNS", "ms-nns");
proto_register_field_array(proto_nns, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_dissector("ms-nns", dissect_nns, proto_nns);
}
void proto_reg_handoff_nns(void)
{
gssapi_handle = find_dissector("gssapi");
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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