/* packet-fortinet-sso.c

 * Routines for Fortinet Single Sign-On

 * Copyright 2020, Alexis La Goutte <alexis.lagoutte at gmail dot com>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 *

 * No spec/doc is available based on reverse/analysis of protocol...

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/addr_resolv.h>

#define UDP_FSSO        8002

void proto_register_fortinet_sso(void);

void proto_reg_handoff_fortinet_sso(void);

static int proto_fortinet_sso;

static int ett_fortinet_sso;

static int hf_fsso_length;

static int hf_fsso_timestamp;

static int hf_fsso_client_ip;

static int hf_fsso_payload_length;

static int hf_fsso_string;

static int hf_fsso_domain;

static int hf_fsso_user;

static int hf_fsso_host;

static int hf_fsso_version;

static int hf_fsso_tsagent_number_port_range;

static int hf_fsso_tsagent_port_range_min;

static int hf_fsso_tsagent_port_range_max;

static int hf_fsso_unknown;

static int hf_fsso_unknown_ipv4;

static dissector_handle_t fortinet_sso_handle;

/* Add the '/' delimited field at offset (limited to *remaining bytes) and

 * advance past it. If there is no delimiter the field takes all that is left. */

static void

fsso_add_field(proto_tree *tree, int hf, tvbuff_t *tvb, unsigned *offset, unsigned *remaining)

{

    unsigned found_offset;

    unsigned len;

    bool found = false;

    if (*remaining > 0)

        found = tvb_find_uint8_length(tvb, *offset, *remaining, '/', &found_offset);

    if (found) {

        len = found_offset - *offset;

        proto_tree_add_item(tree, hf, tvb, *offset, len, ENC_ASCII);

        *offset += len + 1;

        *remaining -= len + 1;

    } else {

        proto_tree_add_item(tree, hf, tvb, *offset, *remaining, ENC_ASCII);

        *offset += *remaining;

        *remaining = 0;

    }

}

static int

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

{

    proto_tree *ti;

    proto_tree *fsso_tree;

    uint32_t payload_length, client_ip;

    unsigned string_length;

    const char *string;

    unsigned offset = 0;

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

    col_set_str(pinfo->cinfo, COL_INFO, "Fortinet Single Sign-On");

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

    fsso_tree = proto_item_add_subtree(ti, ett_fortinet_sso);

    proto_tree_add_item(fsso_tree, hf_fsso_length, tvb, offset, 2, ENC_BIG_ENDIAN);

    offset += 2;

    proto_tree_add_item(fsso_tree, hf_fsso_timestamp, tvb, offset, 4, ENC_BIG_ENDIAN);

    offset += 4;

    proto_tree_add_item(fsso_tree, hf_fsso_client_ip, tvb, offset, 4, ENC_BIG_ENDIAN);

    client_ip = tvb_get_ipv4(tvb, offset);

    offset += 4;

    proto_tree_add_item_ret_uint(fsso_tree, hf_fsso_payload_length, tvb, offset, 2, ENC_BIG_ENDIAN, &payload_length);

    offset += 2;

    proto_tree_add_item_ret_string_and_length(fsso_tree, hf_fsso_string, tvb, offset, -1, ENC_ASCII, pinfo->pool, (const uint8_t**)&string, &string_length);

    col_add_str(pinfo->cinfo, COL_INFO, string);

    if(client_ip == 0xFFFFFFFF) { //if client_ip equal 255.255.255.255 (0xFFFFFFFF) is KeepAlive packet

        /* Domain / KeepAlive (User) / Version */

        fsso_add_field(fsso_tree, hf_fsso_domain, tvb, &offset, &string_length);

        fsso_add_field(fsso_tree, hf_fsso_user, tvb, &offset, &string_length);

        fsso_add_field(fsso_tree, hf_fsso_version, tvb, &offset, &string_length);

    } else {

        /* Host / Domain / User */

        fsso_add_field(fsso_tree, hf_fsso_host, tvb, &offset, &string_length);

        fsso_add_field(fsso_tree, hf_fsso_domain, tvb, &offset, &string_length);

        fsso_add_field(fsso_tree, hf_fsso_user, tvb, &offset, &string_length);

    }

    if(tvb_reported_length_remaining(tvb, offset) == 4) {

        /* There is some packet with extra IPv4 address... */

        proto_tree_add_item(fsso_tree, hf_fsso_unknown_ipv4, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

    } else {

        if(tvb_reported_length_remaining(tvb, offset)) {

            uint16_t value;

            uint32_t number_port_range;

            value = tvb_get_ntohs(tvb, offset);

            if(value == 0x2002) { /* Not a TS Agent additional Data */

                proto_tree_add_item(fsso_tree, hf_fsso_unknown, tvb, offset, 2, ENC_NA);

                offset += 2;

                proto_tree_add_item(fsso_tree, hf_fsso_unknown_ipv4, tvb, offset, 4, ENC_BIG_ENDIAN);

                offset += 4;

                proto_tree_add_item(fsso_tree, hf_fsso_unknown, tvb, offset, 6, ENC_NA);

                offset += 6;

                proto_tree_add_item(fsso_tree, hf_fsso_unknown_ipv4, tvb, offset, 4, ENC_BIG_ENDIAN);

                offset += 4;

                proto_tree_add_item(fsso_tree, hf_fsso_unknown, tvb, offset, 1, ENC_NA);

                offset += 1;

            } else {

                proto_tree_add_item(fsso_tree, hf_fsso_unknown, tvb, offset, 15, ENC_NA);

                offset += 15;

                proto_tree_add_item(fsso_tree, hf_fsso_unknown, tvb, offset, 5, ENC_NA);

                offset += 5;

                proto_tree_add_item(fsso_tree, hf_fsso_unknown, tvb, offset, 6, ENC_NA);

                offset += 6;

                /* Port Range assigned to user for TS Agent (RDP/Citrix) */

                proto_tree_add_item_ret_uint(fsso_tree, hf_fsso_tsagent_number_port_range, tvb, offset, 2, ENC_BIG_ENDIAN, &number_port_range);

                offset += 2;

                while (number_port_range) {

                    proto_tree_add_item(fsso_tree, hf_fsso_tsagent_port_range_min, tvb, offset, 2, ENC_BIG_ENDIAN);

                    offset += 2;

                    proto_tree_add_item(fsso_tree, hf_fsso_tsagent_port_range_max, tvb, offset, 2, ENC_BIG_ENDIAN);

                    offset += 2;

                    number_port_range --;

                }

            }

        }

    }

    return offset;

}

static bool

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

{

    uint32_t length_remaining, length;

    if (tvb_captured_length(tvb) < 2) {

        return false;

    }

    length_remaining = tvb_reported_length_remaining(tvb, 0);

    //first bytes is the length of payload

    length = tvb_get_ntohs(tvb, 0);

    if(length_remaining != length)

    {

        return false;

    }

    //always send with UDP Destination Port 80002

    if(pinfo->destport != UDP_FSSO)

    {

        return false;

    }

    dissect_fortinet_sso(tvb, pinfo, tree, data);

    return true;

}

void

proto_register_fortinet_sso(void)

{

    static hf_register_info hf[] = {

        { &hf_fsso_length,

        { "Length", "fortinet_sso.length", FT_UINT16, BASE_DEC, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_timestamp,

        { "Timestamp", "fortinet_sso.timestamp", FT_ABSOLUTE_TIME, ABSOLUTE_TIME_LOCAL, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_client_ip,

        { "Client IP", "fortinet_sso.client_ip", FT_IPv4, BASE_NONE, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_payload_length,

        { "Payload Length", "fortinet_sso.payload_length", FT_UINT16, BASE_DEC, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_string,

        { "String", "fortinet_sso.string", FT_STRINGZ, BASE_NONE, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_user,

        { "User", "fortinet_sso.user", FT_STRING, BASE_NONE, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_domain,

        { "Domain", "fortinet_sso.domain", FT_STRING, BASE_NONE, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_host,

        { "Host", "fortinet_sso.host", FT_STRING, BASE_NONE, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_version,

        { "Version", "fortinet_sso.version", FT_STRING, BASE_NONE, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_tsagent_number_port_range,

        { "Number of Port Range", "fortinet_sso.tsagent.port_range.number", FT_UINT16, BASE_DEC, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_tsagent_port_range_min,

        { "Port Range (Min)", "fortinet_sso.tsagent.port_range.min", FT_UINT16, BASE_DEC, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_tsagent_port_range_max,

        { "Port Range (Max)", "fortinet_sso.tsagent.port_range.max", FT_UINT16, BASE_DEC, NULL, 0x0,

        NULL, HFILL}},

        { &hf_fsso_unknown,

        { "Unknown", "fortinet_sso.unknown", FT_BYTES, BASE_NONE, NULL, 0x0,

        "Unknown Data...", HFILL}},

        { &hf_fsso_unknown_ipv4,

        { "Unknown IPv4", "fortinet_sso.unknown.ipv4", FT_IPv4, BASE_NONE, NULL, 0x0,

        "Unknown Data...", HFILL}},

    };

    static int *ett[] = {

        &ett_fortinet_sso,

    };

    proto_fortinet_sso = proto_register_protocol("Fortinet Single Sign On", "fortinet_sso", "fortinet_sso");

    fortinet_sso_handle = register_dissector("fortinet_sso", dissect_fortinet_sso, proto_fortinet_sso);

    proto_register_field_array(proto_fortinet_sso, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

}

void

proto_reg_handoff_fortinet_sso(void)

{

    dissector_add_uint_with_preference("udp.port", 0, fortinet_sso_handle);

    heur_dissector_add("udp", dissect_fortinet_fsso_heur, "Fortinet SSO over UDP", "fortinet_sso", proto_fortinet_sso, HEURISTIC_ENABLE);

}

/*

 * 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:

 */