/* packet-hpfeeds.c

 * Routines for Honeypot Protocol Feeds packet disassembly

 * Copyright 2013, Sebastiano DI PAOLA - <sebastiano.dipaola@gmail.com>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

/*

 * Additional information regarding hpfeeds protocol can be found here

 * https://redmine.honeynet.org/projects/hpfeeds/wiki

*/

#include "config.h"

#include <epan/packet.h>

#include <epan/prefs.h>

#include <epan/expert.h>

#include <epan/tap.h>

#include <epan/stats_tree.h>

#include <epan/wmem_scopes.h>

#include "packet-tcp.h"

struct HpfeedsTap {

    unsigned payload_size;

    uint8_t* channel;

    uint8_t opcode;

};

static int hpfeeds_tap;

static const char* st_str_channels_payload = "Payload size per channel";

static const char* st_str_opcodes = "Opcodes";

static int st_node_channels_payload = -1;

static int st_node_opcodes = -1;

static wmem_list_t* channels_list;

struct channel_node {

    uint8_t* channel;

    unsigned st_node_channel_payload;

};

void proto_register_hpfeeds(void);

void proto_reg_handoff_hpfeeds(void);

static dissector_handle_t hpfeeds_handle;

static heur_dissector_list_t heur_subdissector_list;

/* Preferences */

static bool hpfeeds_desegment = true;

static bool try_heuristic = true;

static int proto_hpfeeds;

static int hf_hpfeeds_opcode;

static int hf_hpfeeds_msg_length;

static int hf_hpfeeds_nonce;

static int hf_hpfeeds_secret;

static int hf_hpfeeds_payload;

static int hf_hpfeeds_server_len;

static int hf_hpfeeds_server;

static int hf_hpfeeds_ident_len;

static int hf_hpfeeds_ident;

static int hf_hpfeeds_channel;

static int hf_hpfeeds_chan_len;

static int hf_hpfeeds_errmsg;

static int ett_hpfeeds;

static expert_field ei_hpfeeds_opcode_unknown;

/* OPCODE */

#define OP_ERROR       0         /* error message*/

#define OP_INFO        1         /* server name, nonce */

#define OP_AUTH        2         /* client id, sha1(nonce+authkey) */

#define OP_PUBLISH     3         /* client id, channelname, payload */

#define OP_SUBSCRIBE   4         /* client id, channelname*/

/* OFFSET FOR HEADER */

#define HPFEEDS_HDR_LEN  5

static const value_string opcode_vals[] = {

    { OP_ERROR,      "Error" },

    { OP_INFO,       "Info" },

    { OP_AUTH,       "Auth" },

    { OP_PUBLISH,    "Publish" },

    { OP_SUBSCRIBE,  "Subscribe" },

    { 0,              NULL },

};

static void

dissect_hpfeeds_error_pdu(tvbuff_t *tvb, proto_tree *tree, unsigned offset)

{

    proto_tree_add_item(tree, hf_hpfeeds_errmsg, tvb, offset, -1, ENC_ASCII);

}

static void

dissect_hpfeeds_info_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset)

{

    uint8_t len = 0;

    proto_tree *data_subtree;

    uint8_t *strptr = NULL;

    len = tvb_get_uint8(tvb, offset);

    /* don't move the offset yet as we need to get data after this operation */

    strptr = tvb_get_string_enc(pinfo->pool, tvb, offset + 1, len, ENC_ASCII);

    data_subtree = proto_tree_add_subtree_format(tree, tvb, offset, -1, ett_hpfeeds, NULL, "Broker: %s", strptr);

    proto_tree_add_item(data_subtree, hf_hpfeeds_server_len, tvb, offset, 1,

        ENC_BIG_ENDIAN);

    offset += 1;

    proto_tree_add_item(data_subtree, hf_hpfeeds_server, tvb, offset, len,

        ENC_ASCII);

    offset += len;

    proto_tree_add_item(data_subtree, hf_hpfeeds_nonce, tvb, offset, -1,

        ENC_NA);

}

static void

dissect_hpfeeds_auth_pdu(tvbuff_t *tvb, proto_tree *tree, unsigned offset)

{

    uint8_t len = 0;

    len = tvb_get_uint8(tvb, offset);

    proto_tree_add_item(tree, hf_hpfeeds_ident_len, tvb,

                    offset, 1, ENC_BIG_ENDIAN);

    offset += 1;

    proto_tree_add_item(tree, hf_hpfeeds_ident, tvb,

                    offset, len, ENC_ASCII);

    offset += len;

    proto_tree_add_item(tree, hf_hpfeeds_secret, tvb,

                    offset, -1, ENC_NA);

}

static uint8_t*

hpfeeds_get_channel_name(tvbuff_t* tvb, unsigned offset)

{

    uint8_t len = tvb_get_uint8(tvb, offset);

    offset += len + 1;

    len = tvb_get_uint8(tvb, offset);

    offset += 1;

    return tvb_get_string_enc(wmem_file_scope(), tvb, offset, len, ENC_ASCII);

}

static unsigned

hpfeeds_get_payload_size(tvbuff_t* tvb, unsigned offset)

{

    unsigned message_len = tvb_get_ntohl(tvb, offset);

    unsigned ident_len = tvb_get_uint8(tvb, offset + 5);

    unsigned channel_len = tvb_get_uint8(tvb, offset + 6 + ident_len);

    return (message_len - 2 - ident_len - 1 - channel_len);

}

static void

dissect_hpfeeds_publish_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,

    unsigned offset)

{

    uint8_t len = 0;

    heur_dtbl_entry_t *hdtbl_entry;

    tvbuff_t *next_tvb;

    const uint8_t *channelname = NULL;

    const char* save_match_string = NULL;

    len = tvb_get_uint8(tvb, offset);

    proto_tree_add_item(tree, hf_hpfeeds_ident_len, tvb, offset, 1, ENC_BIG_ENDIAN);

    offset += 1;

    proto_tree_add_item(tree, hf_hpfeeds_ident, tvb, offset, len, ENC_ASCII);

    offset += len;

    len = tvb_get_uint8(tvb, offset);

    proto_tree_add_item(tree, hf_hpfeeds_chan_len, tvb, offset, 1, ENC_BIG_ENDIAN);

    offset += 1;

    /* get the channel name as ephemeral string to pass it to the heuristic decoders */

    proto_tree_add_item_ret_string(tree, hf_hpfeeds_channel, tvb, offset, len, ENC_ASCII|ENC_NA,

        pinfo->pool, &channelname);

    offset += len;

    /* try the heuristic dissectors */

    if (try_heuristic) {

        /* save the current match_string before calling the subdissectors */

        if (pinfo->match_string)

            save_match_string = pinfo->match_string;

        pinfo->match_string = (const char*)channelname;

        next_tvb = tvb_new_subset_remaining(tvb, offset);

        if (dissector_try_heuristic(heur_subdissector_list, next_tvb, pinfo, tree, &hdtbl_entry, NULL)) {

            return;

        }

        pinfo->match_string = save_match_string;

    }

    /* heuristic failed. Print remaining bytes as flat payload */

    proto_tree_add_item(tree, hf_hpfeeds_payload, tvb, offset, -1, ENC_NA);

}

static void hpfeeds_stats_tree_init(stats_tree* st)

{

    st_node_channels_payload = stats_tree_create_node(st, st_str_channels_payload, 0, STAT_DT_INT, true);

    st_node_opcodes = stats_tree_create_pivot(st, st_str_opcodes, 0);

    channels_list = wmem_list_new(wmem_epan_scope());

}

static tap_packet_status hpfeeds_stats_tree_packet(stats_tree* st _U_, packet_info* pinfo _U_, epan_dissect_t* edt _U_, const void* p, tap_flags_t flags _U_)

{

    const struct HpfeedsTap *pi = (const struct HpfeedsTap *)p;

    wmem_list_frame_t* head = wmem_list_head(channels_list);

    wmem_list_frame_t* cur = head;

    struct channel_node* ch_node;

    if (pi->opcode == OP_PUBLISH) {

        /* search an existing channel node and create it if it does not */

        while(cur != NULL) {

            ch_node = (struct channel_node*)wmem_list_frame_data(cur);

            if (strncmp((char*)ch_node->channel, (char*)pi->channel, strlen((char*)pi->channel)) == 0) {

                break;

            }

            cur = wmem_list_frame_next(cur);

        }

        if (cur == NULL) {

            ch_node = wmem_new0(wmem_file_scope(), struct channel_node);

            ch_node->channel = (unsigned char*)wmem_strdup(wmem_file_scope(), (char*)pi->channel);

            ch_node->st_node_channel_payload = stats_tree_create_node(st, (char*)ch_node->channel,

                st_node_channels_payload, STAT_DT_INT, false);

            wmem_list_append(channels_list, ch_node);

        }

        avg_stat_node_add_value_int(st, st_str_channels_payload, 0, false, pi->payload_size);

        avg_stat_node_add_value_int(st, (char*)ch_node->channel, 0, false, pi->payload_size);

    }

    stats_tree_tick_pivot(st, st_node_opcodes,

            val_to_str(pinfo->pool, pi->opcode, opcode_vals, "Unknown opcode (%d)"));

    return TAP_PACKET_REDRAW;

}

static void

dissect_hpfeeds_subscribe_pdu(tvbuff_t *tvb, proto_tree *tree, unsigned offset)

{

    uint8_t len = 0;

    /* get length of ident field */

    len = tvb_get_uint8(tvb, offset);

    proto_tree_add_item(tree, hf_hpfeeds_ident_len, tvb, offset, 1,

        ENC_BIG_ENDIAN);

    offset += 1;

    proto_tree_add_item(tree, hf_hpfeeds_ident, tvb, offset, len,

        ENC_ASCII);

    /* move forward inside data */

    offset += len;

    proto_tree_add_item(tree, hf_hpfeeds_channel, tvb, offset, -1,

        ENC_ASCII);

}

/*

 * Get the length of the HPFEED message, including header

 * This is a trivial function, but it's mandatory as it is used as a callback

 * by the routine to re-assemble the protocol spread on multiple TCP packets

 */

static unsigned

get_hpfeeds_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_)

{

    return tvb_get_ntohl(tvb, offset + 0);

}

static int

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

{

    struct HpfeedsTap *hpfeeds_stats;

    /* We have already parsed msg length we need to skip to opcode offset */

    unsigned offset = 0;

    uint8_t opcode;

    proto_item *ti;

    proto_tree *hpfeeds_tree, *data_subtree;

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

    ti = proto_tree_add_item(tree, proto_hpfeeds, tvb, 0, -1, ENC_NA);

    hpfeeds_tree = proto_item_add_subtree(ti, ett_hpfeeds);

    proto_tree_add_item(hpfeeds_tree, hf_hpfeeds_msg_length, tvb, offset,

        4, ENC_BIG_ENDIAN);

    offset += 4;

    /* Get opcode and write it */

    opcode = tvb_get_uint8(tvb, offset);

    /* Clear out stuff in the info column */

    col_add_fstr(pinfo->cinfo, COL_INFO, "Type %s",

        val_to_str(pinfo->pool, opcode, opcode_vals, "Unknown (0x%02x)"));

    ti = proto_tree_add_item(hpfeeds_tree, hf_hpfeeds_opcode, tvb, offset,

            1, ENC_BIG_ENDIAN);

    data_subtree = proto_item_add_subtree(ti, ett_hpfeeds);

    offset += 1;

    if (opcode >= array_length(opcode_vals) - 1) {

        expert_add_info_format(pinfo, ti, &ei_hpfeeds_opcode_unknown,

                "Unknown value %02x for opcode field", opcode);

    }

    if (tree) { /* we are being asked for details */

        switch (opcode) {

            case OP_ERROR:

                dissect_hpfeeds_error_pdu(tvb, data_subtree, offset);

            break;

            case OP_INFO:

                dissect_hpfeeds_info_pdu(tvb, pinfo, data_subtree, offset);

            break;

            case OP_AUTH:

                dissect_hpfeeds_auth_pdu(tvb, data_subtree, offset);

            break;

            case OP_PUBLISH:

                dissect_hpfeeds_publish_pdu(tvb, pinfo, data_subtree, offset);

            break;

            case OP_SUBSCRIBE:

                dissect_hpfeeds_subscribe_pdu(tvb, data_subtree, offset);

            break;

            /* No need for a default, we check that outside the if(tree)

             * block earlier */

        }

    }

    /* In publish, generate stats every packet, even not in tree */

    hpfeeds_stats = wmem_new0(wmem_file_scope(), struct HpfeedsTap);

    if (opcode == OP_PUBLISH) {

        hpfeeds_stats->channel = hpfeeds_get_channel_name(tvb, offset);

        hpfeeds_stats->payload_size = hpfeeds_get_payload_size(tvb, 0);

    }

    hpfeeds_stats->opcode = opcode;

    tap_queue_packet(hpfeeds_tap, pinfo, hpfeeds_stats);

    return tvb_captured_length(tvb);

}

static int

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

{

    tcp_dissect_pdus(tvb, pinfo, tree, hpfeeds_desegment, HPFEEDS_HDR_LEN,

        get_hpfeeds_pdu_len, dissect_hpfeeds_pdu, data);

    return tvb_captured_length(tvb);

}

void

proto_register_hpfeeds(void)

{

    static hf_register_info hf[] = {

        { &hf_hpfeeds_opcode,

            { "Opcode", "hpfeeds.opcode",

            FT_UINT8, BASE_DEC_HEX,

            VALS(opcode_vals), 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_msg_length,

            { "Message Length", "hpfeeds.msglen",

            FT_UINT32, BASE_DEC_HEX,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_nonce,

            { "Nonce", "hpfeeds.nonce",

            FT_BYTES, BASE_NONE,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_secret,

            { "Secret", "hpfeeds.secret",

            FT_BYTES, BASE_NONE,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_payload,

            { "Payload", "hpfeeds.payload",

            FT_BYTES, BASE_NONE,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_server,

            { "Server", "hpfeeds.server",

            FT_STRING, BASE_NONE,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_ident,

            { "Ident", "hpfeeds.ident",

            FT_STRING, BASE_NONE,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_channel,

            { "Channel", "hpfeeds.channel",

            FT_STRING, BASE_NONE,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_chan_len,

            { "Channel length", "hpfeeds.channel_len",

            FT_UINT8, BASE_DEC,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_ident_len,

            { "Ident length", "hpfeeds.ident_len",

            FT_UINT8, BASE_DEC,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_errmsg,

            { "Error message", "hpfeeds.errmsg",

            FT_STRING, BASE_NONE,

            NULL, 0x0,

            NULL, HFILL }

        },

        { &hf_hpfeeds_server_len,

            { "Server length", "hpfeeds.server_len",

            FT_UINT8, BASE_DEC,

            NULL, 0x0,

            NULL, HFILL }

        },

    };

    /* Setup protocol subtree array */

    static int *ett[] = {

        &ett_hpfeeds

    };

    static ei_register_info ei[] = {

        { &ei_hpfeeds_opcode_unknown, { "hpfeeds.opcode.unknown", PI_PROTOCOL, PI_WARN, "Unknown value for opcode field", EXPFILL }},

    };

    module_t *hpfeeds_module;

    expert_module_t* expert_hpfeeds;

    proto_hpfeeds = proto_register_protocol (

        "HPFEEDS HoneyPot Feeds Protocol", /* name */

        "HPFEEDS",      /* short name */

        "hpfeeds"       /* abbrev     */

        );

    heur_subdissector_list = register_heur_dissector_list_with_description("hpfeeds", "HPFEEDS Publish payload", proto_hpfeeds);

    proto_register_field_array(proto_hpfeeds, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    expert_hpfeeds = expert_register_protocol(proto_hpfeeds);

    expert_register_field_array(expert_hpfeeds, ei, array_length(ei));

    hpfeeds_handle = register_dissector("hpfeeds", dissect_hpfeeds, proto_hpfeeds);

    hpfeeds_module = prefs_register_protocol(proto_hpfeeds, NULL);

    prefs_register_bool_preference(hpfeeds_module, "desegment_hpfeeds_messages",

        "Reassemble HPFEEDS messages spanning multiple TCP segments",

        "Whether the HPFEEDS dissector should reassemble messages spanning "

        "multiple TCP segments. "

        "To use this option, you must also enable \"Allow subdissectors to "

        "reassemble TCP streams\" in the TCP protocol settings.",

        &hpfeeds_desegment);

    prefs_register_bool_preference(hpfeeds_module, "try_heuristic",

        "Try heuristic sub-dissectors",

        "Try to decode the payload using an heuristic sub-dissector",

        &try_heuristic);

    hpfeeds_tap = register_tap("hpfeeds");

}

void

proto_reg_handoff_hpfeeds(void)

{

    stats_tree_register("hpfeeds", "hpfeeds", "HPFEEDS", 0, hpfeeds_stats_tree_packet, hpfeeds_stats_tree_init, NULL);

    dissector_add_for_decode_as_with_preference("tcp.port", hpfeeds_handle);

}

/*

 * 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:

 */