/*
 * Copyright 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

#include <s2n.h>

#include "error/s2n_errno.h"

#include "tls/s2n_connection.h"
#include "tls/s2n_config.h"
#include "tls/s2n_signature_algorithms.h"
#include "tls/s2n_tls.h"

#include "stuffer/s2n_stuffer.h"

#include "utils/s2n_safety.h"


int s2n_client_cert_verify_recv(struct s2n_connection *conn)
{
    struct s2n_stuffer *in = &conn->handshake.io;

    s2n_hash_algorithm chosen_hash_alg = S2N_HASH_MD5_SHA1;
    s2n_signature_algorithm chosen_signature_alg = S2N_SIGNATURE_RSA;

    if(conn->actual_protocol_version == S2N_TLS12){
        /* Make sure the client is actually using one of the {sig,hash} pairs that we sent in the ClientCertificateRequest */
        GUARD(s2n_get_signature_hash_pair_if_supported(in, &chosen_hash_alg, &chosen_signature_alg));
    }
    uint16_t signature_size;
    struct s2n_blob signature = {0};
    GUARD(s2n_stuffer_read_uint16(in, &signature_size));
    signature.size = signature_size;
    signature.data = s2n_stuffer_raw_read(in, signature.size);
    notnull_check(signature.data);

    /* Use a copy of the hash state since the verify digest computation may modify the running hash state we need later. */
    struct s2n_hash_state hash_state = {0};
    GUARD(s2n_handshake_get_hash_state(conn, chosen_hash_alg, &hash_state));
    GUARD(s2n_hash_copy(&conn->handshake.ccv_hash_copy, &hash_state));

    switch (chosen_signature_alg) {
    case S2N_SIGNATURE_RSA:
    case S2N_SIGNATURE_ECDSA:
        GUARD(s2n_pkey_verify(&conn->secure.client_public_key, &conn->handshake.ccv_hash_copy, &signature));
        break;
    default:
        S2N_ERROR(S2N_ERR_INVALID_SIGNATURE_ALGORITHM);
    }

    /* Client certificate has been verified. Minimize required handshake hash algs */
    GUARD(s2n_conn_update_required_handshake_hashes(conn));

    return 0;
}


int s2n_client_cert_verify_send(struct s2n_connection *conn)
{
    struct s2n_stuffer *out = &conn->handshake.io;

    s2n_hash_algorithm chosen_hash_alg = S2N_HASH_MD5_SHA1;
    s2n_signature_algorithm chosen_signature_alg = S2N_SIGNATURE_RSA;

    if(conn->actual_protocol_version == S2N_TLS12){
        chosen_hash_alg = conn->secure.client_cert_hash_algorithm;
        chosen_signature_alg = conn->secure.client_cert_sig_alg;

        GUARD(s2n_stuffer_write_uint8(out, (uint8_t) chosen_hash_alg));
        GUARD(s2n_stuffer_write_uint8(out, (uint8_t) chosen_signature_alg));
    }

    /* Use a copy of the hash state since the verify digest computation may modify the running hash state we need later. */
    struct s2n_hash_state hash_state = {0};
    GUARD(s2n_handshake_get_hash_state(conn, chosen_hash_alg, &hash_state));
    GUARD(s2n_hash_copy(&conn->handshake.ccv_hash_copy, &hash_state));

    struct s2n_blob signature = {0};

    struct s2n_cert_chain_and_key *cert_chain_and_key = conn->handshake_params.our_chain_and_key;
    switch (chosen_signature_alg) {
    /* s2n currently only supports RSA Signatures */
    case S2N_SIGNATURE_RSA:
        signature.size = s2n_pkey_size(cert_chain_and_key->private_key);
        GUARD(s2n_stuffer_write_uint16(out, signature.size));
        signature.data = s2n_stuffer_raw_write(out, signature.size);
        notnull_check(signature.data);
        GUARD(s2n_pkey_sign(cert_chain_and_key->private_key, &conn->handshake.ccv_hash_copy, &signature));
        break;
    default:
        S2N_ERROR(S2N_ERR_INVALID_SIGNATURE_ALGORITHM);
    }

    /* Client certificate has been verified. Minimize required handshake hash algs */
    GUARD(s2n_conn_update_required_handshake_hashes(conn));

    return 0;
}