/*
    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    0MQ 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef __ZMQ_CURVE_SERVER_HPP_INCLUDED__
#define __ZMQ_CURVE_SERVER_HPP_INCLUDED__

#include "platform.hpp"

#ifdef HAVE_LIBSODIUM
#include <sodium.h>

#if crypto_box_NONCEBYTES != 24 \
||  crypto_box_PUBLICKEYBYTES != 32 \
||  crypto_box_SECRETKEYBYTES != 32 \
||  crypto_box_ZEROBYTES != 32 \
||  crypto_box_BOXZEROBYTES != 16 \
||  crypto_secretbox_NONCEBYTES != 24 \
||  crypto_secretbox_ZEROBYTES != 32 \
||  crypto_secretbox_BOXZEROBYTES != 16
#error "libsodium not built properly"
#endif

#include "mechanism.hpp"
#include "options.hpp"

namespace zmq
{

    class msg_t;
    class session_base_t;

    class curve_server_t : public mechanism_t
    {
    public:

        curve_server_t (session_base_t *session_,
                        const std::string &peer_address_,
                        const options_t &options_);
        virtual ~curve_server_t ();

        // mechanism implementation
        virtual int next_handshake_command (msg_t *msg_);
        virtual int process_handshake_command (msg_t *msg_);
        virtual int encode (msg_t *msg_);
        virtual int decode (msg_t *msg_);
        virtual int zap_msg_available ();
        virtual bool is_handshake_complete () const;

    private:

        enum state_t {
            expect_hello,
            send_welcome,
            expect_initiate,
            expect_zap_reply,
            send_ready,
            connected
        };

        session_base_t * const session;

        const std::string peer_address;

        //  Current FSM state
        state_t state;

        //  True iff we are awaiting reply from ZAP handler.
        bool expecting_zap_reply;

        uint64_t nonce;

        //  Our permanent secret key (s)
        uint8_t our_perma_sec_key [crypto_box_SECRETKEYBYTES];

        //  Our transient public key (S')
        uint8_t our_trans_pub_key [crypto_box_PUBLICKEYBYTES];

        //  Our transient secret key (s')
        uint8_t our_trans_sec_key [crypto_box_SECRETKEYBYTES];

        //  Client's transient public key (C')
        uint8_t peer_trans_pub_key [crypto_box_PUBLICKEYBYTES];

        //  Key used to produce cookie
        uint8_t cookie_key [crypto_secretbox_KEYBYTES];

        //  Intermediary buffer used to speed up boxing and unboxing.
        uint8_t precomputed [crypto_box_BEFORENMBYTES];

        int process_hello (msg_t *msg_);
        int produce_welcome (msg_t *msg_);
        int process_initiate (msg_t *msg_);
        int produce_ready (msg_t *msg_);

        void send_zap_request (const uint8_t *key);
        int receive_and_process_zap_reply ();
    };

}

#endif

#endif