epan/dissectors/packet-ms-nns.c

   1 /* packet-ms-nns.c
   2  * Routines for .NET NegotiateStream Protocol (MS-NNS) dissection
   3  * Copyright 2020, Uli Heilmeier <uh@heilmeier.eu>
   4  *
   5  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wieshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 /*
  13  * Basic dissector for .NET NegotiateStream Protocol based on protocol reference found at
  14  * https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-NNS/%5bMS-NNS%5d.pdf
  15  */
  16
  17 #include <config.h>
  18
  19 #include <epan/packet.h>
  20 #include <epan/conversation.h>
  21
  22 /* Prototypes */
  23 void proto_reg_handoff_nns(void);
  24 void proto_register_nns(void);
  25
  26 static dissector_handle_t gssapi_handle;
  27
  28
  29 #define MS_NNS_MESSAGE_HANDSHAKE_DONE      20
  30 #define MS_NNS_MESSAGE_HANDSHAKE_ERROR     21
  31 #define MS_NNS_MESSAGE_HANDSHAKE_PROGRESS  22
  32
  33 static const value_string nns_message_id_vals[] = {
  34     { MS_NNS_MESSAGE_HANDSHAKE_DONE, "Handshake Done" },
  35     { MS_NNS_MESSAGE_HANDSHAKE_ERROR, "Handshake Error" },
  36     { MS_NNS_MESSAGE_HANDSHAKE_PROGRESS, "Handshake In Progress" },
  37     { 0, NULL}
  38 };
  39
  40 struct nns_session_state {
  41     uint32_t  handshake_done;
  42     bool      first_handshake_done;
  43 };
  44
  45 static int proto_nns;
  46 static int hf_nns_message_id;
  47 static int hf_nns_major_version;
  48 static int hf_nns_minor_version;
  49 static int hf_nns_auth_payload_size;
  50 static int hf_nns_auth_payload;
  51 static int hf_nns_payload_size;
  52 static int hf_nns_payload;
  53
  54 static int ett_nns;
  55 static int ett_nns_payload;
  56
  57 #define MS_NNS_MIN_LENGTH 4
  58
  59 static int
  60 dissect_nns(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
  61 {
  62     proto_item      *ti, *pti;
  63     proto_tree      *nns_tree, *payload_tree;
  64     unsigned        offset = 0;
  65     uint32_t        message_id;
  66     uint32_t        payload_size;
  67     conversation_t  *conversation;
  68     tvbuff_t        *nt_tvb;
  69     int             remaining;
  70     struct nns_session_state *session_state;
  71
  72     if (tvb_reported_length(tvb) < MS_NNS_MIN_LENGTH)
  73         return 0;
  74
  75     conversation = find_or_create_conversation(pinfo);
  76
  77     session_state = (struct nns_session_state *)conversation_get_proto_data(conversation, proto_nns);
  78     if (!session_state) {
  79         session_state = wmem_new0(wmem_file_scope(), struct nns_session_state);
  80         conversation_add_proto_data(conversation, proto_nns, session_state);
  81     }
  82
  83     col_set_str(pinfo->cinfo, COL_PROTOCOL, "MS-NNS");
  84     col_clear(pinfo->cinfo, COL_INFO);
  85
  86     ti = proto_tree_add_item(tree, proto_nns, tvb, 0, -1, ENC_NA);
  87
  88     nns_tree = proto_item_add_subtree(ti, ett_nns);
  89
  90     /* As it is unknown if there is a one-way Handshake Done or a two-way Handshake Done we check the first frame
  91      * after the first Handshake Done if it looks like a Handshake Done message (0x140100). */
  92
  93     if ( session_state->handshake_done && session_state->handshake_done < pinfo->num &&
  94             !(session_state->first_handshake_done && tvb_get_ntoh24(tvb, offset) == 0x140100)) {
  95         proto_tree_add_item_ret_uint(nns_tree, hf_nns_payload_size, tvb, offset, 4, ENC_LITTLE_ENDIAN, &payload_size);
  96         offset += 4;
  97         col_append_str(pinfo->cinfo, COL_INFO, "Data");
  98         if ( payload_size > 0) {
  99             remaining = tvb_reported_length_remaining(tvb, offset);
 100             if ((uint32_t) remaining < payload_size) {
 101                 pinfo->desegment_offset = offset - 4;
 102                 pinfo->desegment_len = payload_size - remaining;
 103                 return (offset - 4);
 104             }
 105             proto_tree_add_item(nns_tree, hf_nns_payload, tvb, offset, payload_size, ENC_NA);
 106             offset += payload_size;
 107             session_state->first_handshake_done = false;
 108         }
 109     }
 110     else {
 111         proto_tree_add_item_ret_uint(nns_tree, hf_nns_message_id, tvb, offset, 1, ENC_NA, &message_id);
 112         offset += 1;
 113         col_append_sep_fstr(pinfo->cinfo, COL_INFO, ", ", "%s", val_to_str_const(message_id, nns_message_id_vals, "Unknown Record"));
 114         proto_tree_add_item(nns_tree, hf_nns_major_version, tvb, offset, 1, ENC_NA);
 115         offset += 1;
 116         proto_tree_add_item(nns_tree, hf_nns_minor_version, tvb, offset, 1, ENC_NA);
 117         offset += 1;
 118         proto_tree_add_item_ret_uint(nns_tree, hf_nns_auth_payload_size, tvb, offset, 2, ENC_BIG_ENDIAN, &payload_size);
 119         offset += 2;
 120         if ( payload_size > 0) {
 121             if ((uint32_t) tvb_reported_length_remaining(tvb, offset) < payload_size) {
 122                 pinfo->desegment_offset = offset - 5;
 123                 pinfo->desegment_len = payload_size;
 124                 return (offset - 5);
 125             }
 126             pti = proto_tree_add_item(nns_tree, hf_nns_auth_payload, tvb, offset, payload_size, ENC_NA);
 127             if (message_id == MS_NNS_MESSAGE_HANDSHAKE_DONE || message_id == MS_NNS_MESSAGE_HANDSHAKE_PROGRESS) {
 128                 nt_tvb = tvb_new_subset_length(tvb, offset, payload_size);
 129                 payload_tree = proto_item_add_subtree(pti, ett_nns_payload);
 130                 call_dissector(gssapi_handle, nt_tvb, pinfo, payload_tree);
 131             }
 132             offset += payload_size;
 133         }
 134         if ( message_id == MS_NNS_MESSAGE_HANDSHAKE_DONE) {
 135             session_state->handshake_done = pinfo->num;
 136             session_state->first_handshake_done = (session_state->first_handshake_done ? false : true);
 137         }
 138     }
 139     return offset;
 140 }
 141
 142 void proto_register_nns(void)
 143 {
 144     static hf_register_info hf[] = {
 145         { &hf_nns_message_id,
 146           { "MessageID", "ms-nns.message_id",
 147             FT_UINT8, BASE_DEC, VALS(nns_message_id_vals), 0x0,
 148             NULL, HFILL }
 149         },
 150         { &hf_nns_major_version,
 151           { "Major Version", "ms-nns.major_version",
 152             FT_UINT8, BASE_DEC, NULL, 0x0,
 153             NULL, HFILL }
 154         },
 155         { &hf_nns_minor_version,
 156           { "Minor Version", "ms-nns.minor_version",
 157             FT_UINT8, BASE_DEC, NULL, 0x0,
 158             NULL, HFILL }
 159         },
 160         { &hf_nns_auth_payload_size,
 161           { "Auth Payload Size", "ms-nns.auth_payload_size",
 162             FT_UINT16, BASE_DEC, NULL, 0x0,
 163             NULL, HFILL }
 164         },
 165         { &hf_nns_auth_payload,
 166           { "Auth Payload", "ms-nns.known_encoding",
 167             FT_BYTES, BASE_NONE, NULL, 0x0,
 168             NULL, HFILL }
 169         },
 170         { &hf_nns_payload_size,
 171           { "Payload Size", "ms-nns.payload_size",
 172             FT_UINT32, BASE_DEC, NULL, 0x0,
 173             NULL, HFILL }
 174         },
 175         { &hf_nns_payload,
 176           { "Payload", "ms-nns.payload",
 177             FT_BYTES, BASE_NONE, NULL, 0x0,
 178             NULL, HFILL }
 179         }
 180     };
 181
 182     static int *ett[] = {
 183         &ett_nns,
 184         &ett_nns_payload
 185     };
 186
 187     proto_nns = proto_register_protocol(".NET NegotiateStream Protocol", "MS-NNS", "ms-nns");
 188     proto_register_field_array(proto_nns, hf, array_length(hf));
 189     proto_register_subtree_array(ett, array_length(ett));
 190     register_dissector("ms-nns", dissect_nns, proto_nns);
 191 }
 192
 193 void proto_reg_handoff_nns(void)
 194 {
 195     gssapi_handle = find_dissector("gssapi");
 196 }
 197
 198 /*
 199  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 200  *
 201  * Local variables:
 202  * c-basic-offset: 4
 203  * tab-width: 8
 204  * indent-tabs-mode: nil
 205  * End:
 206  *
 207  * vi: set shiftwidth=4 tabstop=8 expandtab:
 208  * :indentSize=4:tabSize=8:noTabs=true:
 209  */