/*
 * Copyright (C) 2011-2017 Intel Corporation. All rights reserved.
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 * modification, are permitted provided that the following conditions
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 *
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 *     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
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#include "sgx_trts.h"
#include "sgx_utils.h"
#include "EnclaveMessageExchange.h"
#include "sgx_eid.h"
#include "error_codes.h"
#include "sgx_ecp_types.h"
#include "sgx_thread.h"
#include <map>
#include "dh_session_protocol.h"
#include "sgx_dh.h"
#include "sgx_tcrypto.h"
#include "LocalAttestationCode_t.h"
#include "sgx_tseal.h"

#ifdef __cplusplus
extern "C" {
#endif

uint32_t verify_peer_enclave_trust(sgx_dh_session_enclave_identity_t* peer_enclave_identity, sgx_measurement_t* measurement);
#ifdef __cplusplus
}
#endif
uint32_t create_ecdsa_key_pair(sgx_ec256_public_t* pub_key, sgx_ec256_private_t* priv_key);
void serialize_key_pair_to_string( sgx_ec256_public_t* pub_key, sgx_ec256_private_t* signing_priv_key, uint8_t* private_public_key_string);
void deserialize_string_to_key_pair(uint8_t* private_public_key_string, sgx_ec256_public_t* pub_key, sgx_ec256_private_t* priv_key); 



 
#define MAX_SESSION_COUNT  16

//number of open sessions
// uint32_t g_session_count = 0;

ATTESTATION_STATUS generate_session_id(uint32_t *session_id);
ATTESTATION_STATUS end_session();
sgx_ec256_private_t signing_priv_key;
sgx_ec256_private_t short_term_priv_key;
sgx_ec256_public_t short_term_pub_key; // for testing only: to test verification of signature
uint32_t one_la_done; 
sgx_measurement_t verifier_mr_enclave;
sgx_measurement_t apache_mr_signer; 
sgx_ecc_state_handle_t ecc_state;


uint32_t session_ids[MAX_SESSION_COUNT];

// Our enclave will not be doing LA with more than 1 decryptor enclave at a time.
// We should not need this.
//std::map<int, dh_session_t>g_dest_session_info_map;
dh_session_t global_session_info;
// TODO: May be we need to store all previously assigned session IDs instead of just the counter; to prevent replay attacks -
uint32_t global_session_id=0;


//Handle the request from Source Enclave for a session
ATTESTATION_STATUS session_request(sgx_dh_msg1_t *dh_msg1,
                          uint32_t *session_id )
{
 //   dh_session_t session_info;
    sgx_dh_session_t sgx_dh_session;
    sgx_status_t status = SGX_SUCCESS;

    if(!session_id || !dh_msg1)
    {
        return INVALID_PARAMETER_ERROR;
    }

    //Intialize the session as a session responder
    status = sgx_dh_init_session(SGX_DH_SESSION_RESPONDER, &sgx_dh_session);
    if(SGX_SUCCESS != status)
    {
        return status;
    }

    *session_id=1;

    global_session_info.status = IN_PROGRESS;

    //Generate Message1 that will be returned to Source Enclave
    status = sgx_dh_responder_gen_msg1((sgx_dh_msg1_t*)dh_msg1, &sgx_dh_session);
    if(SGX_SUCCESS != status)
    {
        global_session_id--;
        // SAFE_FREE(g_session_id_tracker[*session_id]);
        return status;
    }
    memcpy(&global_session_info.in_progress.dh_session, &sgx_dh_session, sizeof(sgx_dh_session_t));
    //return sgx_seal_data(0, NULL, 0, NULL, 0, NULL); 
    //Store the session information under the correspoding source enlave id key
    //    g_dest_session_info_map.insert(std::pair<sgx_enclave_id_t, dh_session_t>(src_enclave_id, session_info));

    return status;
}

//Verify Message 2, generate Message3 and exchange Message 3 with Source Enclave
ATTESTATION_STATUS exchange_report(
                          sgx_dh_msg2_t *dh_msg2,
                          sgx_dh_msg3_t *dh_msg3,
                          uint32_t* session_id)
{

    sgx_key_128bit_t dh_aek;   // Session key
//    dh_session_t session_info;
    ATTESTATION_STATUS status = SUCCESS;
    sgx_dh_session_t sgx_dh_session;
    sgx_dh_session_enclave_identity_t initiator_identity;

    if(!dh_msg2 || !dh_msg3)
    {
        return INVALID_PARAMETER_ERROR;
    }

    memset(&dh_aek,0, sizeof(sgx_key_128bit_t));
// Why is there a do-while loop anyway? It seems like there is no successful exit ... 
//    do
//    {
      // TODO: Make sure that this works - pointers
//        session_info = global_session_info;

        if(global_session_info.status != IN_PROGRESS)
        {
            status = INVALID_SESSION;
            end_session(); 
        }

        memcpy(&sgx_dh_session, &global_session_info.in_progress.dh_session, sizeof(sgx_dh_session_t));

        dh_msg3->msg3_body.additional_prop_length = 0;
        //Process message 2 from source enclave and obtain message 3
        sgx_status_t se_ret = sgx_dh_responder_proc_msg2(dh_msg2,
                                                       dh_msg3,
                                                       &sgx_dh_session,
                                                       &dh_aek,
                                                       &initiator_identity);
        if(SGX_SUCCESS != se_ret)
        {
            status = se_ret;
            end_session();
        }
	uint32_t hash_count; 
        // THIS IS WHERE THE DECRYPTOR VERIFIES THE APACHE'S MRSIGNER IS THE PUBLIC KEY GIVEN AFTER THE LOCAL ATTESTATION WITH THE VERIFIER.
        //Verify source enclave's trust
	if(one_la_done == 0) 
	{
		one_la_done = 1;
	        uint32_t ret = verify_peer_enclave_trust(&initiator_identity, NULL);
	        if(ret != SUCCESS)
        	{
            		return ret; //INVALID_SESSION;
       		}
		for(hash_count=0; hash_count<32; hash_count++)
			verifier_mr_enclave.m[hash_count] = initiator_identity.mr_signer.m[hash_count];
	} 
	else 
	{
		return 0xFFFFFFFF;
		/*
		uint32_t ret = verify_peer_enclave_trust(&initiator_identity, &apache_mrsigner);
                if(ret != SUCCESS)
                {
                        return ret; //INVALID_SESSION;
                }
		*/
	}

	// TODO: Verify that these changes will be lost on update. 
        //save the session ID, status and initialize the session nonce
        global_session_info.session_id = *session_id;
        global_session_info.status = ACTIVE;
        global_session_info.active.counter = 0;
        memcpy(&global_session_info.active.AEK, &dh_aek, sizeof(sgx_key_128bit_t));
        memset(&dh_aek,0, sizeof(sgx_key_128bit_t));
        //g_session_count++;*/
//    }while(0);

    return status;
}

uint32_t create_ecdsa_key_pair(sgx_ec256_public_t* pub_key, sgx_ec256_private_t* priv_key)
{
  sgx_status_t se_ret; sgx_status_t se_ret2;
  //create ECC context
  ecc_state = NULL;
  se_ret = sgx_ecc256_open_context(&ecc_state);
  if(SGX_SUCCESS != se_ret)
    return se_ret;

  // generate private key and public key
  se_ret = sgx_ecc256_create_key_pair(priv_key, pub_key, ecc_state);
  se_ret2 = sgx_ecc256_close_context(ecc_state);

  if(SGX_SUCCESS != se_ret || se_ret2!= SGX_SUCCESS) // something weird has happened - couldn't shut it down.
    return 0xFFFFFFFF;
  return SGX_SUCCESS;
}

// todo: set to private
// todo: assumes that the length of the keystring is at least 3*SGX_ECP256_KEY_SIZE
void serialize_key_pair_to_string(sgx_ec256_public_t* pub_key, sgx_ec256_private_t* signing_priv_key, uint8_t* private_public_key_string)
{
  if(private_public_key_string != NULL)  // nowhere to serialize to
  {
     uint32_t counter;
     if(pub_key != NULL)  // public key to serialize
     {
        for(counter=0;counter<SGX_ECP256_KEY_SIZE; counter++)
          *(private_public_key_string+counter)=pub_key->gx[counter];

        for(counter=SGX_ECP256_KEY_SIZE;counter<2*SGX_ECP256_KEY_SIZE; counter++)
           *(private_public_key_string+counter)=pub_key->gy[counter-SGX_ECP256_KEY_SIZE];
     }

     if(signing_priv_key != NULL) // private key to serialize
     {
       for(counter=2*SGX_ECP256_KEY_SIZE;counter<3*SGX_ECP256_KEY_SIZE; counter++)
          *(private_public_key_string+counter)=signing_priv_key->r[counter - 2*SGX_ECP256_KEY_SIZE];
     }
/*
     if(pub_key != NULL)  // public key to serialize
     {
        for(counter=SGX_ECP256_KEY_SIZE;counter<2*SGX_ECP256_KEY_SIZE; counter++)
          *(private_public_key_string+counter)=pub_key->gx[counter-SGX_ECP256_KEY_SIZE];

        for(counter=2*SGX_ECP256_KEY_SIZE;counter<3*SGX_ECP256_KEY_SIZE; counter++)
           *(private_public_key_string+counter)=pub_key->gy[counter-2*SGX_ECP256_KEY_SIZE];
     }*/
  }
}


// todo: set to private
void deserialize_string_to_key_pair(uint8_t* private_public_key_string, sgx_ec256_public_t* pub_key, sgx_ec256_private_t* signing_priv_key)
{
  if(private_public_key_string != NULL) // nowhere to deserialize from 
  {
    uint32_t counter;
    if(signing_priv_key != NULL) 
    {

     for(counter=2*SGX_ECP256_KEY_SIZE;counter<3*SGX_ECP256_KEY_SIZE; counter++)
       signing_priv_key->r[counter-2*SGX_ECP256_KEY_SIZE]=*(private_public_key_string+counter);
    }

    if(pub_key != NULL)
    {
      for(counter=0;counter<SGX_ECP256_KEY_SIZE; counter++)
        	pub_key->gx[counter]=*(private_public_key_string+counter);

      for(counter=SGX_ECP256_KEY_SIZE;counter<2*SGX_ECP256_KEY_SIZE; counter++)
  	pub_key->gy[counter-SGX_ECP256_KEY_SIZE]=*(private_public_key_string+counter);
    }
  }
}


uint32_t create_and_seal_ecdsa_signing_key_pair(__attribute__((unused))   sgx_ec256_public_t* pub_key, __attribute__((unused))  uint32_t* sealed_data_length, __attribute__((unused)) uint8_t* sealed_data)
{
    uint32_t ret_status; sgx_ec256_private_t private_key;  uint32_t counter;
    ret_status=create_ecdsa_key_pair(pub_key, &private_key);
    if(ret_status!=SGX_SUCCESS)
       return ret_status;
    for(counter=0;counter<SGX_ECP256_KEY_SIZE; counter++)
	signing_priv_key.r[counter]=private_key.r[counter]; 
    // generating the entire string as there is no SGX function to generate the public key from the private one.
    uint8_t* private_public_key_string = (uint8_t*) malloc(3*SGX_ECP256_KEY_SIZE);
    uint8_t* sealed_data2 = (uint8_t*) malloc(*sealed_data_length);
    // serializing keypair to string
    serialize_key_pair_to_string(pub_key, &private_key, private_public_key_string);
    uint8_t* private_key_string = (uint8_t*) malloc(SGX_ECP256_KEY_SIZE); 
    for(counter=0;counter<SGX_ECP256_KEY_SIZE;counter++)
	*(private_key_string+counter)=private_key.r[counter];
//    return *sealed_data_length;
    ret_status = sgx_seal_data(0, NULL, 3*SGX_ECP256_KEY_SIZE, private_public_key_string, *sealed_data_length, (sgx_sealed_data_t*) sealed_data2); 
    for(counter=0;counter<*sealed_data_length;counter++)
	*(sealed_data+counter)=*(sealed_data2+counter); 
    free(sealed_data2);
    free(private_key_string);  //free(private_key);  
    free(private_public_key_string);

    return ret_status; // SGX_SUCCESS; 
}

/*
uint32_t unseal_and_restore_sealed_signing_key_pair(__attribute__((unused)) sgx_ec256_public_t* pub_key, __attribute__((unused))  uint8_t* sealed_data, __attribute__((unused))   uint32_t* sgx_sealed_data_length)
{
	return SGX_SUCCESS; 

}*/

uint32_t unseal_and_restore_sealed_signing_key_pair(__attribute__((unused)) sgx_ec256_public_t* pub_key, uint8_t* sealed_data, size_t* sgx_sealed_data_length)
{
  uint32_t expected_plaintext_msg_length; uint8_t* temp_plaintext; uint32_t counter; uint32_t ret_status;
  expected_plaintext_msg_length = sgx_get_encrypt_txt_len((sgx_sealed_data_t*)sealed_data);
  if(expected_plaintext_msg_length == 0xffffffff)
    return 0xFFFFFFFF;

//  uint32_t return_status; 
  uint8_t* sealed_data2 = (uint8_t*) malloc(*sgx_sealed_data_length); 
  for(counter=0;counter<*sgx_sealed_data_length;counter++)
  {
	*(sealed_data2+counter)=*(sealed_data+counter); 
  }

  temp_plaintext = (uint8_t*)malloc( expected_plaintext_msg_length );
  ret_status = sgx_unseal_data((sgx_sealed_data_t*)sealed_data2, NULL, 0, temp_plaintext, &expected_plaintext_msg_length);
  if(ret_status != SGX_SUCCESS)
  {
    free(temp_plaintext);free(sealed_data2);
    switch(ret_status)
    {
      case SGX_ERROR_MAC_MISMATCH:
          // MAC of the sealed data is incorrect.          The sealed data has been tampered.
          break;
      case SGX_ERROR_INVALID_ATTRIBUTE:
          // Indicates attribute field of the sealed data is incorrect.
          break;
      case SGX_ERROR_INVALID_ISVSVN:
          // Indicates isv_svn field of the sealed data is greater than            the enclave�s ISVSVN. This is a downgraded enclave.
          break;
      case SGX_ERROR_INVALID_CPUSVN:
          // Indicates cpu_svn field of the sealed data is greater than            the platform�s cpu_svn. enclave is  on a downgraded platform.
          break;
      case SGX_ERROR_INVALID_KEYNAME:
          // Indicates key_name field of the sealed data is incorrect.
          break;
      default:
          // other errors
          break;
    }
    return ret_status;
  }
   
  deserialize_string_to_key_pair(temp_plaintext, pub_key, &signing_priv_key);
  free(temp_plaintext); free(sealed_data2);  
  return SGX_SUCCESS;
}

uint32_t create_and_sign_client_side_pub_key(sgx_measurement_t* mr_enclave,  sgx_ec256_public_t* generated_pub_key, sgx_ec256_signature_t* generated_signature)
{
	// create key pair
	uint32_t ret_status = create_ecdsa_key_pair(&short_term_pub_key, &short_term_priv_key);  uint32_t counter;
	uint32_t ret_status2;
       if(ret_status!=SGX_SUCCESS)
           return ret_status;
	// serialize public key, append mr_enclave 
	uint8_t* public_key_string = (uint8_t*) malloc(3*SGX_ECP256_KEY_SIZE); // for .edl file - size parameter for serialize is 96 and this fits coz we need to append the mr_enclave to the pub key 
	serialize_key_pair_to_string(&short_term_pub_key, NULL, public_key_string);
	for(counter=32*2; counter<32*3; counter++) // appending mr_enclave
		*(public_key_string+counter)=mr_enclave->m[counter]; 
	// retrieve long-term private key from global variable - apparently, need to create a local copy or it crashes
	sgx_ec256_private_t long_term_priv_key;
	for(counter=0; counter<SGX_ECP256_KEY_SIZE; counter++) 
		long_term_priv_key.r[counter] = signing_priv_key.r[counter];  
	// sign public key with long-term private key 
	sgx_ec256_signature_t local_signature; sgx_ecc_state_handle_t ecc_handle; 
	//// opening context for signature
	ret_status = sgx_ecc256_open_context(&ecc_handle); 
	if(ret_status != SGX_SUCCESS) 
		return ret_status; 
	ret_status = sgx_ecdsa_sign(public_key_string,2*SGX_ECP256_KEY_SIZE, &long_term_priv_key, &local_signature, ecc_handle);
	ret_status2 = sgx_ecc256_close_context(ecc_handle); 
	free(public_key_string); 
	if(ret_status == SGX_SUCCESS) 
	{
		for(counter=0; counter<SGX_ECP256_KEY_SIZE; counter++) 
			generated_pub_key->gx[counter] = short_term_pub_key.gx[counter]; 
		for(counter=0;counter<SGX_NISTP_ECP256_KEY_SIZE	; counter++)
		{
			generated_signature->x[counter] = local_signature.x[counter]; 
                        generated_signature->y[counter] = local_signature.y[counter]; 
		}
	}
	if(ret_status != SGX_SUCCESS || ret_status2 != SGX_SUCCESS)
		return 0xFFFFFFFF;
	return 0; 
}



uint32_t calculate_sealed_data_size( uint32_t input_size) 
{
//	*op_size=sgx_calc_sealed_data_size(0, input_size); 
	return sgx_calc_sealed_data_size(0, input_size);

}









// TODO: Fix this.
//Respond to the request from the Source Enclave to close the session
ATTESTATION_STATUS end_session(/**/)
{
  return SUCCESS;
}
/*
// Session_id is set to the first index of the pointer array that is non-null.(Not sure how it is ensured that all of them point to NULL at the start)
// Why can't it just keep a counter that is incremented? What are the values of g_session_id_tracker array?
//Returns a new sessionID for the source destination session
ATTESTATION_STATUS generate_session_id(uint32_t *session_id)
{
    ATTESTATION_STATUS status = SUCCESS;

    if(!session_id)
    {
        return INVALID_PARAMETER_ERROR;
    }
    //if the session structure is untintialized, set that as the next session ID
    for (int i = 0; i < MAX_SESSION_COUNT; i++)
    {
        if (g_session_id_tracker[i] == NULL)
        {
            *session_id = i;
            return status;
        }
    }

    status = NO_AVAILABLE_SESSION_ERROR;

    return status;
*/
  // *session_id=++global_session_id;
//}