wireshark/epan/dissectors/packet-hpfeeds.c

/* packet-hpfeeds.c
 * Routines for Honeypot Protocol Feeds packet disassembly
 * Copyright 2013, Sebastiano DI PAOLA - <sebastiano.dipaola@gmail.com>
 *
 * $Id$
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */


/*
 * 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 "packet-tcp.h"

#define HPFEEDS_PORT 10000

static gboolean hpfeeds_desegment = TRUE;

static int proto_hpfeeds = -1;

static int hf_hpfeeds_opcode = -1;
static int hf_hpfeeds_msg_length = -1;
static int hf_hpfeeds_nonce = -1;
static int hf_hpfeeds_secret = -1;
static int hf_hpfeeds_payload = -1; 
static int hf_hpfeeds_server_len = -1; 
static int hf_hpfeeds_server = -1; 
static int hf_hpfeeds_ident_len = -1;
static int hf_hpfeeds_ident = -1;
static int hf_hpfeeds_channel = -1;
static int hf_hpfeeds_chan_len = -1;
static int hf_hpfeeds_errmsg = -1;

static gint ett_hpfeeds = -1;

/* 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_OPCODE_OFFSET   4
#define HPFEEDS_HDR_LEN  5


/* This value is equal to the number of elements inside the following structure
* and should be updated in case new types of messages are added to the protocol
*/
#define HPFEEDS_IMPLEMENTED_OPCODE 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, guint offset)
{
    proto_tree_add_item(tree, hf_hpfeeds_errmsg, tvb, offset, -1, ENC_BIG_ENDIAN);
} 

static void
dissect_hpfeeds_info_pdu(tvbuff_t *tvb, proto_tree *tree, guint offset)
{
    guint8 len = 0;
    proto_item *ti = NULL;
    proto_tree *data_subtree = NULL;
    guint8 *strptr = NULL;

    len = tvb_get_guint8(tvb, offset);
    /* don't move the offset yet as we need to get data after this operation */
    strptr = tvb_get_ephemeral_string(tvb, offset + 1, len);
    ti = proto_tree_add_text(tree, tvb, offset, -1, "Broker: %s", strptr);
    data_subtree = proto_item_add_subtree(ti, ett_hpfeeds); 

    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_BIG_ENDIAN);
    offset += len;   
 
    proto_tree_add_item(data_subtree, hf_hpfeeds_nonce, tvb, offset, -1,
        ENC_BIG_ENDIAN);
}

static void
dissect_hpfeeds_auth_pdu(tvbuff_t *tvb, proto_tree *tree, guint offset)
{
    guint8 len = 0;
    
    len = tvb_get_guint8(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_BIG_ENDIAN);
    offset += len;   
 
    proto_tree_add_item(tree, hf_hpfeeds_secret, tvb,
                    offset, -1, ENC_BIG_ENDIAN);
}

static void
dissect_hpfeeds_publish_pdu(tvbuff_t *tvb, proto_tree *tree, guint offset)
{
    guint8 len = 0;

    len = tvb_get_guint8(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_BIG_ENDIAN);
    offset += len;   
    len = tvb_get_guint8(tvb, offset);
    proto_tree_add_item(tree, hf_hpfeeds_chan_len, tvb, offset, 1,
        ENC_BIG_ENDIAN);
    offset += 1;

    proto_tree_add_item(tree, hf_hpfeeds_channel, tvb, offset, len,
        ENC_BIG_ENDIAN);
    offset += len;

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

static void
dissect_hpfeeds_subscribe_pdu(tvbuff_t *tvb, proto_tree *tree, guint offset)
{
    guint8 len = 0;
    /* get length of ident field */    
    len = tvb_get_guint8(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_BIG_ENDIAN);
    /* move forward inside data */
    offset += len;
    proto_tree_add_item(tree, hf_hpfeeds_channel, tvb, offset, -1,
        ENC_BIG_ENDIAN);
}

/*
 * 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 guint
get_hpfeeds_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset)
{
    return tvb_get_ntohl(tvb, offset);
}

static void
dissect_hpfeeds_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
    /* We have already parsed msg length we need to skip to opcode offset */
    guint offset = HPFEEDS_OPCODE_OFFSET;

    guint8 opcode;
    proto_item *ti;
    proto_tree *data_subtree;
   
    /* Get opcode and write it */
    opcode = tvb_get_guint8(tvb, offset);

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "HPFEEDS");
    /* Clear out stuff in the info column */
    col_clear(pinfo->cinfo,COL_INFO);
    col_add_fstr(pinfo->cinfo, COL_INFO, "Type %s",
        val_to_str(opcode, opcode_vals, "Unknown (0x%02x)"));

    ti = proto_tree_add_item(tree, hf_hpfeeds_opcode, tvb, offset, 
            1, ENC_BIG_ENDIAN);
    data_subtree = proto_item_add_subtree(ti, ett_hpfeeds);
    offset += 1;

    if (opcode >= HPFEEDS_IMPLEMENTED_OPCODE) {
        expert_add_info_format(pinfo, ti, PI_PROTOCOL, PI_WARN, 
                "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, data_subtree, offset);
            break;
            case OP_AUTH:
                dissect_hpfeeds_auth_pdu(tvb, data_subtree, offset);
            break;
            case OP_PUBLISH:
                dissect_hpfeeds_publish_pdu(tvb, 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 */
        }
    }
}

static void 
dissect_hpfeeds(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
    guint msglen = 0;
    guint8 offset = 0;
    proto_item *ti = NULL;
    proto_tree *hpfeeds_tree = NULL;

    /* At lease header is needed */
    if (tvb_reported_length(tvb) < HPFEEDS_HDR_LEN)
        return;

    /* get message length in order to decide if we need to reassemble packet */
    msglen = tvb_get_guint8(tvb, offset);
    
    /* Retrieve header data */    
    if (tree) {
        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);
    } 
   
    if (tvb_reported_length(tvb) < msglen) {
        /* we need to reassemble */
        tcp_dissect_pdus(tvb, pinfo, hpfeeds_tree, hpfeeds_desegment, 5,
            get_hpfeeds_pdu_len, dissect_hpfeeds_pdu);
    } else
        dissect_hpfeeds_pdu(tvb, pinfo, hpfeeds_tree);
}

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 gint *ett[] = {
        &ett_hpfeeds
    };

    module_t *hpfeeds_module;

    proto_hpfeeds = proto_register_protocol (
        "HPFEEDS HoneyPot Feeds Protocol", /* name */
        "HPFEEDS",      /* short name */
        "hpfeeds"       /* abbrev     */
        );

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

    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);
}

void
proto_reg_handoff_hpfeeds(void)
{
    static dissector_handle_t hpfeeds_handle;

    hpfeeds_handle = create_dissector_handle(dissect_hpfeeds, proto_hpfeeds);
    dissector_add_handle("tcp.port", hpfeeds_handle);
}