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/*
* Copyright 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 <stdint.h>
#include "error/s2n_errno.h"
#include "tls/s2n_connection.h"
#include "tls/s2n_resume.h"
#include "tls/s2n_tls.h"
#include "tls/s2n_tls13_handshake.h"
#include "stuffer/s2n_stuffer.h"
#include "utils/s2n_safety.h"
int s2n_server_finished_recv(struct s2n_connection *conn)
{
uint8_t *our_version;
int length = S2N_TLS_FINISHED_LEN;
our_version = conn->handshake.server_finished;
if (conn->actual_protocol_version == S2N_SSLv3) {
length = S2N_SSL_FINISHED_LEN;
}
uint8_t *their_version = s2n_stuffer_raw_read(&conn->handshake.io, length);
POSIX_ENSURE_REF(their_version);
S2N_ERROR_IF(!s2n_constant_time_equals(our_version, their_version, length), S2N_ERR_BAD_MESSAGE);
return 0;
}
int s2n_server_finished_send(struct s2n_connection *conn)
{
uint8_t *our_version;
int length = S2N_TLS_FINISHED_LEN;
/* Compute the finished message */
POSIX_GUARD(s2n_prf_server_finished(conn));
our_version = conn->handshake.server_finished;
if (conn->actual_protocol_version == S2N_SSLv3) {
length = S2N_SSL_FINISHED_LEN;
}
POSIX_GUARD(s2n_stuffer_write_bytes(&conn->handshake.io, our_version, length));
/* Zero the sequence number */
struct s2n_blob seq = {.data = conn->secure.server_sequence_number,.size = S2N_TLS_SEQUENCE_NUM_LEN };
POSIX_GUARD(s2n_blob_zero(&seq));
/* Update the secure state to active, and point the client at the active state */
conn->server = &conn->secure;
if (s2n_connection_is_session_resumed(conn)) {
POSIX_GUARD(s2n_prf_key_expansion(conn));
}
return 0;
}
int s2n_tls13_server_finished_recv(struct s2n_connection *conn) {
POSIX_ENSURE_EQ(conn->actual_protocol_version, S2N_TLS13);
uint8_t length = s2n_stuffer_data_available(&conn->handshake.io);
S2N_ERROR_IF(length == 0, S2N_ERR_BAD_MESSAGE);
/* read finished mac from handshake */
struct s2n_blob wire_finished_mac = {0};
s2n_blob_init(&wire_finished_mac, s2n_stuffer_raw_read(&conn->handshake.io, length), length);
/* get tls13 keys */
s2n_tls13_connection_keys(keys, conn);
/* get transcript hash */
POSIX_ENSURE_REF(conn->handshake.hashes);
struct s2n_hash_state *hash_state = &conn->handshake.hashes->hash_workspace;
POSIX_GUARD_RESULT(s2n_handshake_copy_hash_state(conn, keys.hash_algorithm, hash_state));
/* look up finished secret key */
struct s2n_blob finished_key = {0};
POSIX_GUARD(s2n_blob_init(&finished_key, conn->handshake.server_finished, keys.size));
/* generate the hashed message authenticated code */
s2n_tls13_key_blob(server_finished_mac, keys.size);
POSIX_GUARD(s2n_tls13_calculate_finished_mac(&keys, &finished_key, hash_state, &server_finished_mac));
/* compare mac with received message */
POSIX_GUARD(s2n_tls13_mac_verify(&keys, &server_finished_mac, &wire_finished_mac));
return 0;
}
int s2n_tls13_server_finished_send(struct s2n_connection *conn) {
POSIX_ENSURE_EQ(conn->actual_protocol_version, S2N_TLS13);
/* get tls13 keys */
s2n_tls13_connection_keys(keys, conn);
/* get transcript hash */
POSIX_ENSURE_REF(conn->handshake.hashes);
struct s2n_hash_state *hash_state = &conn->handshake.hashes->hash_workspace;
POSIX_GUARD_RESULT(s2n_handshake_copy_hash_state(conn, keys.hash_algorithm, hash_state));
/* look up finished secret key */
struct s2n_blob finished_key = {0};
POSIX_GUARD(s2n_blob_init(&finished_key, conn->handshake.server_finished, keys.size));
/* generate the hashed message authenticated code */
s2n_tls13_key_blob(server_finished_mac, keys.size);
POSIX_GUARD(s2n_tls13_calculate_finished_mac(&keys, &finished_key, hash_state, &server_finished_mac));
/* write to handshake io */
POSIX_GUARD(s2n_stuffer_write(&conn->handshake.io, &server_finished_mac));
return 0;
}
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