/*
 * Copyright (C) 2011-2019 Intel Corporation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
 *   * Neither the name of Intel Corporation nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <string>
#include "sgx_eid.h"
#include "EnclaveInitiator_t.h"
#include "EnclaveMessageExchange.h"
#include "error_codes.h"
#include "Utility_EnclaveInitiator.h"
#include "sgx_dh.h"

#define UNUSED(val) (void)(val)

#define RESPONDER_PRODID 1

dh_session_t g_session;

/* Function Description:
 *   This is ECALL routine to create ECDH session.
 *   When it succeeds to create ECDH session, the session context is saved in g_session.
 * */
extern "C" uint32_t test_create_session()
{
    return create_session(&g_session);
}

/* Function Description:
 *   This is ECALL routine to transfer message with ECDH peer
 * */
uint32_t test_message_exchange()
{
    ATTESTATION_STATUS ke_status = SUCCESS;
    uint32_t target_fn_id, msg_type;
    char* marshalled_inp_buff;
    size_t marshalled_inp_buff_len;
    char* out_buff;
    size_t out_buff_len;
    size_t max_out_buff_size;
    char* secret_response;
    uint32_t secret_data;

    target_fn_id = 0;
    msg_type = MESSAGE_EXCHANGE;
    max_out_buff_size = 50; // it's assumed the maximum payload size in response message is 50 bytes, it's for demontration purpose
    secret_data = 0x12345678; //Secret Data here is shown only for purpose of demonstration.

    //Marshals the secret data into a buffer
    ke_status = marshal_message_exchange_request(target_fn_id, msg_type, secret_data, &marshalled_inp_buff, &marshalled_inp_buff_len);
    if(ke_status != SUCCESS)
    {
        return ke_status;
    }

    //Core Reference Code function
    ke_status = send_request_receive_response(&g_session, marshalled_inp_buff,
                marshalled_inp_buff_len, max_out_buff_size, &out_buff, &out_buff_len);
    if(ke_status != SUCCESS)
    {
        SAFE_FREE(marshalled_inp_buff);
        SAFE_FREE(out_buff);
        return ke_status;
    }

    //Un-marshal the secret response data
    ke_status = umarshal_message_exchange_response(out_buff, &secret_response);
    if(ke_status != SUCCESS)
    {
        SAFE_FREE(marshalled_inp_buff);
        SAFE_FREE(out_buff);
        return ke_status;
    }

    SAFE_FREE(marshalled_inp_buff);
    SAFE_FREE(out_buff);
    SAFE_FREE(secret_response);
    return SUCCESS;
}

/* Function Descriptin:
 *   This is ECALL interface to close secure session*/
uint32_t test_close_session()
{
    ATTESTATION_STATUS ke_status;

    ke_status = close_session(&g_session);

    //Erase the session context
    memset(&g_session, 0, sizeof(dh_session_t));
    return ke_status;
}

/* Function Description:
 *   This is to verify peer enclave's identity.
 * For demonstration purpose, we verify below points:
 *   1. peer enclave's MRSIGNER is as expected
 *   2. peer enclave's PROD_ID is as expected
 *   3. peer enclave's attribute is reasonable: it's INITIALIZED'ed enclave; in non-debug build configuration, the enlave isn't loaded with enclave debug mode.
 **/
extern "C" uint32_t verify_peer_enclave_trust(sgx_dh_session_enclave_identity_t* peer_enclave_identity)
{
    if (!peer_enclave_identity)
        return INVALID_PARAMETER_ERROR;
    // check peer enclave's MRSIGNER

    // check peer enclave's product ID and enclave attribute (should be INITIALIZED'ed)
    if ( !(peer_enclave_identity->attributes.flags & SGX_FLAGS_INITTED))
    {
        return ENCLAVE_TRUST_ERROR;
    }

    // check the enclave isn't loaded in enclave debug mode, except that the project is built for debug purpose

    return SUCCESS;
}

/* Function Description: Operates on the input secret and generate the output secret
 * */
uint32_t get_message_exchange_response(uint32_t inp_secret_data)
{
    uint32_t secret_response;

    //User should use more complex encryption method to protect their secret, below is just a simple example
    secret_response = inp_secret_data & 0x11111111;

    return secret_response;

}

//Generates the response from the request message
/* Function Description:
 *   process request message and generate response
 * Parameter Descriptin:
 *   [input] decrypted_data: this is pointer to decrypted message
 *   [output] resp_buffer: this is pointer to response message, the buffer is allocated inside this function
 *   [output] resp_length: this points to response length
 * */
extern "C" uint32_t message_exchange_response_generator(char* decrypted_data,
        char** resp_buffer,
        size_t* resp_length)
{
    ms_in_msg_exchange_t *ms;
    uint32_t inp_secret_data;
    uint32_t out_secret_data;
    if(!decrypted_data || !resp_length)
    {
        return INVALID_PARAMETER_ERROR;
    }
    ms = (ms_in_msg_exchange_t *)decrypted_data;

    if(umarshal_message_exchange_request(&inp_secret_data,ms) != SUCCESS)
        return ATTESTATION_ERROR;

    out_secret_data = get_message_exchange_response(inp_secret_data);

    if(marshal_message_exchange_response(resp_buffer, resp_length, out_secret_data) != SUCCESS)
        return MALLOC_ERROR;

    return SUCCESS;
}
