/* packet-kpasswd.c

 * Routines for kpasswd packet dissection

 *    Ronnie Sahlberg 2003

 *

 * See RFC 3244

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/asn1.h>

#include "packet-tcp.h"

#include "packet-kerberos.h"

#include <epan/prefs.h>

void proto_register_kpasswd(void);

void proto_reg_handoff_kpasswd(void);

static dissector_handle_t kpasswd_handle_udp;

static dissector_handle_t kpasswd_handle_tcp;

/* Desegment Kerberos over TCP messages */

static bool kpasswd_desegment = true;

static int proto_kpasswd;

static int hf_kpasswd_message_len;

static int hf_kpasswd_version;

static int hf_kpasswd_result;

static int hf_kpasswd_result_string;

static int hf_kpasswd_ap_req_len;

static int hf_kpasswd_ap_req_data;

static int hf_kpasswd_krb_priv_message;

static int hf_kpasswd_ChangePasswdData;

static int ett_kpasswd;

static int ett_ap_req_data;

static int ett_krb_priv_message;

#define UDP_PORT_KPASSWD        464

#define TCP_PORT_KPASSWD        464

static const value_string vers_vals[] = {

    { 0x0001, "Reply" },

    { 0xff80, "Request" },

    { 0,      NULL },

};

/** Dissects AP-REQ or AP-REP part of password change. */

static void

dissect_kpasswd_ap_req_data(packet_info *pinfo _U_, tvbuff_t *tvb, proto_tree *parent_tree)

{

    proto_item *it;

    proto_tree *tree;

    it=proto_tree_add_item(parent_tree, hf_kpasswd_ap_req_data, tvb, 0, -1, ENC_NA);

    tree=proto_item_add_subtree(it, ett_ap_req_data);

    dissect_kerberos_main(tvb, pinfo, tree, false, NULL);

}

static int

dissect_kpasswd_user_data_request(packet_info *pinfo, tvbuff_t *tvb, proto_tree *tree)

{

    int offset=0;

    asn1_ctx_t asn1_ctx;

    asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, true, pinfo);

    offset=dissect_kerberos_ChangePasswdData (false, tvb, offset, &asn1_ctx, tree, hf_kpasswd_ChangePasswdData);

    return offset;

}

static kerberos_callbacks cb_req[] = {

    { KRB_CBTAG_PRIV_USER_DATA, dissect_kpasswd_user_data_request },

    { 0, NULL }

};

#define KRB5_KPASSWD_SUCCESS             0

#define KRB5_KPASSWD_MALFORMED           1

#define KRB5_KPASSWD_HARDERROR           2

#define KRB5_KPASSWD_AUTHERROR           3

#define KRB5_KPASSWD_SOFTERROR           4

#define KRB5_KPASSWD_ACCESSDENIED        5

#define KRB5_KPASSWD_BAD_VERSION         6

#define KRB5_KPASSWD_INITIAL_FLAG_NEEDED 7

static const value_string kpasswd_result_types[] = {

    { KRB5_KPASSWD_SUCCESS, "Success" },

    { KRB5_KPASSWD_MALFORMED, "Malformed" },

    { KRB5_KPASSWD_HARDERROR, "HardError" },

    { KRB5_KPASSWD_AUTHERROR, "AuthError" },

    { KRB5_KPASSWD_SOFTERROR, "SoftError" },

    { KRB5_KPASSWD_ACCESSDENIED, "AccessDenied" },

    { KRB5_KPASSWD_BAD_VERSION, "BadVersion" },

    { KRB5_KPASSWD_INITIAL_FLAG_NEEDED, "InitialFlagNeeded" },

    { 0, NULL }

};

static int

dissect_kpasswd_user_data_reply(packet_info *pinfo, tvbuff_t *tvb, proto_tree *tree)

{

    int offset=0;

    uint16_t result;

    /* result */

    result = tvb_get_ntohs(tvb, offset);

    proto_tree_add_uint(tree, hf_kpasswd_result, tvb, offset, 2, result);

    offset+=2;

    col_add_str(pinfo->cinfo, COL_INFO,

        val_to_str(result, kpasswd_result_types, "Result: %u"));

    /* optional result string */

    if(tvb_reported_length_remaining(tvb, offset) > 0){

        proto_tree_add_item(tree, hf_kpasswd_result_string, tvb, offset, tvb_reported_length_remaining(tvb, offset), ENC_ASCII);

        offset = tvb_reported_length(tvb);

    }

    return offset;

}

static kerberos_callbacks cb_rep[] = {

    { KRB_CBTAG_PRIV_USER_DATA, dissect_kpasswd_user_data_reply },

    { 0, NULL }

};

static int

dissect_kpasswd_krb_priv_message(packet_info *pinfo _U_, tvbuff_t *tvb, proto_tree *parent_tree, bool isrequest)

{

    proto_item *it;

    proto_tree *tree=NULL;

    int offset;

    if(parent_tree){

        it=proto_tree_add_item(parent_tree, hf_kpasswd_krb_priv_message, tvb, 0, -1, ENC_NA);

        tree=proto_item_add_subtree(it, ett_krb_priv_message);

    }

    if(isrequest){

        offset = dissect_kerberos_main(tvb, pinfo, tree, false, cb_req);

    } else {

        offset = dissect_kerberos_main(tvb, pinfo, tree, false, cb_rep);

    }

    /* offset is bytes consumed in child tvb given to us */

    return offset;

}

static int

dissect_kpasswd_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, bool have_rm)

{

    proto_item *kpasswd_item=NULL;

    proto_tree *kpasswd_tree=NULL;

    int offset = 0;

    uint16_t message_len, version, ap_req_len;

    tvbuff_t *next_tvb;

    /* TCP record mark and length */

    uint32_t krb_rm = 0;

    int krb_reclen = 0;

    int krb_rm_size = 0;    /* bytes consumed by record mark: 0 or 4 */

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

    col_clear(pinfo->cinfo, COL_INFO);

    /* can't pass have_rm to dissect_kerberos_main, so strip rm first */

    if (have_rm) {

        krb_rm = tvb_get_ntohl(tvb, offset);

        krb_reclen = kerberos_rm_to_reclen(krb_rm);

        krb_rm_size = 4;

        /*

         * What is a reasonable size limit?

         */

        if (krb_reclen > 10 * 1024 * 1024) {

            return (-1);

        }

        offset += krb_rm_size;

    }

    /* it might be a KERBEROS ERROR */

    if(tvb_get_uint8(tvb, offset)==0x7e){

        /* TCP record mark, if any, not displayed.  But hopefully

         * KRB-ERROR dissection will proceed correctly. */

        next_tvb=tvb_new_subset_remaining(tvb, offset);

        return dissect_kerberos_main(next_tvb, pinfo, tree, false, NULL);

    }

    message_len=tvb_get_ntohs(tvb, offset);

    version=tvb_get_ntohs(tvb, offset+2);

    ap_req_len=tvb_get_ntohs(tvb, offset+4);

    if(tree){

        kpasswd_item=proto_tree_add_item(tree, proto_kpasswd, tvb, offset-krb_rm_size, message_len+krb_rm_size, ENC_NA);

        kpasswd_tree=proto_item_add_subtree(kpasswd_item, ett_kpasswd);

        if (have_rm) {

            show_krb_recordmark(kpasswd_tree, tvb, offset-krb_rm_size, krb_rm);

        }

    }

    proto_tree_add_uint(kpasswd_tree, hf_kpasswd_message_len, tvb, offset, 2, message_len);

    proto_tree_add_uint(kpasswd_tree, hf_kpasswd_version, tvb, offset+2, 2, version);

    col_set_str(pinfo->cinfo, COL_INFO, val_to_str_const(version, vers_vals, "Unknown command"));

    proto_tree_add_uint(kpasswd_tree, hf_kpasswd_ap_req_len, tvb, offset+4, 2, ap_req_len);

    offset+=6;

    /* AP-REQ / AP-REP data */

    next_tvb=tvb_new_subset_length(tvb, offset, ap_req_len);

    dissect_kpasswd_ap_req_data(pinfo, next_tvb, kpasswd_tree);

    offset+=ap_req_len;

    /* KRB-PRIV message */

    next_tvb=tvb_new_subset_remaining(tvb, offset);

    offset += dissect_kpasswd_krb_priv_message(pinfo, next_tvb, kpasswd_tree, (version==0xff80));

    proto_item_set_len(kpasswd_item, offset);

    return offset;

}

static int

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

{

    dissect_kpasswd_common(tvb, pinfo, tree, false);

    return tvb_captured_length(tvb);

}

static int

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

{

    pinfo->fragmented = true;

    if (dissect_kpasswd_common(tvb, pinfo, tree, true) < 0) {

        /*

         * The dissector failed to recognize this as a valid

         * Kerberos message.  Mark it as a continuation packet.

         */

        col_set_str(pinfo->cinfo, COL_INFO, "Continuation");

    }

    return tvb_captured_length(tvb);

}

static int

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

{

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

    col_clear(pinfo->cinfo, COL_INFO);

    tcp_dissect_pdus(tvb, pinfo, tree, kpasswd_desegment, 4, get_krb_pdu_len, dissect_kpasswd_tcp_pdu, data);

    return tvb_captured_length(tvb);

}

void

proto_register_kpasswd(void)

{

    static hf_register_info hf[] = {

    { &hf_kpasswd_message_len,

        { "Message Length", "kpasswd.message_len", FT_UINT16, BASE_DEC,

        NULL, 0, NULL, HFILL }},

    { &hf_kpasswd_ap_req_len,

        { "AP_REQ Length", "kpasswd.ap_req_len", FT_UINT16, BASE_DEC,

        NULL, 0, "Length of AP_REQ data", HFILL }},

    { &hf_kpasswd_version,

        { "Version", "kpasswd.version", FT_UINT16, BASE_HEX,

        VALS(vers_vals), 0, NULL, HFILL }},

    { &hf_kpasswd_result,

        { "Result", "kpasswd.result", FT_UINT16, BASE_DEC,

        VALS(kpasswd_result_types), 0, NULL, HFILL }},

    { &hf_kpasswd_result_string,

        { "Result String", "kpasswd.result_string", FT_STRING, BASE_NONE,

        NULL, 0, NULL, HFILL }},

    { &hf_kpasswd_ap_req_data,

        { "AP_REQ", "kpasswd.ap_req", FT_NONE, BASE_NONE,

        NULL, 0, "AP_REQ structure", HFILL }},

    { &hf_kpasswd_krb_priv_message,

        { "KRB-PRIV", "kpasswd.krb_priv", FT_NONE, BASE_NONE,

        NULL, 0, "KRB-PRIV message", HFILL }},

    { &hf_kpasswd_ChangePasswdData, {

        "ChangePasswdData", "kpasswd.ChangePasswdData", FT_NONE, BASE_NONE,

        NULL, 0, "Change Password Data structure", HFILL }},

    };

    static int *ett[] = {

        &ett_kpasswd,

        &ett_ap_req_data,

        &ett_krb_priv_message,

    };

        module_t *kpasswd_module;

    proto_kpasswd = proto_register_protocol("MS Kpasswd", "Kpasswd", "kpasswd");

    proto_register_field_array(proto_kpasswd, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    /* Register preferences */

    kpasswd_module = prefs_register_protocol(proto_kpasswd, NULL);

    prefs_register_bool_preference(kpasswd_module, "desegment",

        "Reassemble Kpasswd over TCP messages spanning multiple TCP segments",

        "Whether the Kpasswd 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.",

        &kpasswd_desegment);

    /* Register dissectors */

    kpasswd_handle_udp = register_dissector("kpasswd.udp", dissect_kpasswd_udp, proto_kpasswd);

    kpasswd_handle_tcp = register_dissector("kpasswd.tcp", dissect_kpasswd_tcp, proto_kpasswd);

}

void

proto_reg_handoff_kpasswd(void)

{

    dissector_add_uint_with_preference("udp.port", UDP_PORT_KPASSWD, kpasswd_handle_udp);

    dissector_add_uint_with_preference("tcp.port", TCP_PORT_KPASSWD, kpasswd_handle_tcp);

}

/*

 * 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:

 */