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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 <sys/param.h>
/* Use usleep */
#define _XOPEN_SOURCE 500
#include <errno.h>
#include <unistd.h>
#include "api/s2n.h"
#include "error/s2n_errno.h"
#include "stuffer/s2n_stuffer.h"
#include "tls/s2n_alerts.h"
#include "tls/s2n_connection.h"
#include "tls/s2n_handshake.h"
#include "tls/s2n_post_handshake.h"
#include "tls/s2n_record.h"
#include "tls/s2n_resume.h"
#include "tls/s2n_tls.h"
#include "utils/s2n_blob.h"
#include "utils/s2n_safety.h"
#include "utils/s2n_socket.h"
S2N_RESULT s2n_read_in_bytes(struct s2n_connection *conn, struct s2n_stuffer *output, uint32_t length)
{
while (s2n_stuffer_data_available(output) < length) {
uint32_t remaining = length - s2n_stuffer_data_available(output);
errno = 0;
int r = s2n_connection_recv_stuffer(output, conn, remaining);
if (r == 0) {
conn->closed = 1;
RESULT_BAIL(S2N_ERR_CLOSED);
} else if (r < 0) {
if (errno == EWOULDBLOCK || errno == EAGAIN) {
RESULT_BAIL(S2N_ERR_IO_BLOCKED);
}
RESULT_BAIL(S2N_ERR_IO);
}
conn->wire_bytes_in += r;
}
return S2N_RESULT_OK;
}
int s2n_read_full_record(struct s2n_connection *conn, uint8_t *record_type, int *isSSLv2)
{
*isSSLv2 = 0;
/* If the record has already been decrypted, then leave it alone */
if (conn->in_status == PLAINTEXT) {
/* Only application data packets count as plaintext */
*record_type = TLS_APPLICATION_DATA;
return S2N_SUCCESS;
}
POSIX_GUARD(s2n_stuffer_resize_if_empty(&conn->in, S2N_LARGE_FRAGMENT_LENGTH));
/* Read the record until we at least have a header */
POSIX_GUARD_RESULT(s2n_read_in_bytes(conn, &conn->header_in, S2N_TLS_RECORD_HEADER_LENGTH));
uint16_t fragment_length;
/* If the first bit is set then this is an SSLv2 record */
if (conn->header_in.blob.data[0] & 0x80) {
conn->header_in.blob.data[0] &= 0x7f;
*isSSLv2 = 1;
WITH_ERROR_BLINDING(conn, POSIX_GUARD(s2n_sslv2_record_header_parse(conn, record_type, &conn->client_protocol_version, &fragment_length)));
} else {
WITH_ERROR_BLINDING(conn, POSIX_GUARD(s2n_record_header_parse(conn, record_type, &fragment_length)));
}
/* Read enough to have the whole record */
POSIX_GUARD_RESULT(s2n_read_in_bytes(conn, &conn->in, fragment_length));
if (*isSSLv2) {
return 0;
}
/* Decrypt and parse the record */
if (s2n_early_data_is_trial_decryption_allowed(conn, *record_type)) {
POSIX_ENSURE(s2n_record_parse(conn) >= S2N_SUCCESS, S2N_ERR_EARLY_DATA_TRIAL_DECRYPT);
} else {
WITH_ERROR_BLINDING(conn, POSIX_GUARD(s2n_record_parse(conn)));
}
/* In TLS 1.3, encrypted handshake records would appear to be of record type
* TLS_APPLICATION_DATA. The actual record content type is found after the encrypted
* is decrypted.
*/
if (conn->actual_protocol_version == S2N_TLS13 && *record_type == TLS_APPLICATION_DATA) {
POSIX_GUARD(s2n_tls13_parse_record_type(&conn->in, record_type));
}
return 0;
}
ssize_t s2n_recv_impl(struct s2n_connection *conn, void *buf, ssize_t size, s2n_blocked_status *blocked)
{
ssize_t bytes_read = 0;
struct s2n_blob out = { 0 };
POSIX_GUARD(s2n_blob_init(&out, (uint8_t *) buf, 0));
if (conn->closed) {
return 0;
}
*blocked = S2N_BLOCKED_ON_READ;
POSIX_ENSURE(!s2n_connection_is_quic_enabled(conn), S2N_ERR_UNSUPPORTED_WITH_QUIC);
POSIX_GUARD_RESULT(s2n_early_data_validate_recv(conn));
while (size && !conn->closed) {
int isSSLv2 = 0;
uint8_t record_type;
int r = s2n_read_full_record(conn, &record_type, &isSSLv2);
if (r < 0) {
if (s2n_errno == S2N_ERR_CLOSED) {
*blocked = S2N_NOT_BLOCKED;
if (!bytes_read) {
return 0;
} else {
return bytes_read;
}
}
/* Don't propagate the error if we already read some bytes */
if (s2n_errno == S2N_ERR_IO_BLOCKED && bytes_read) {
s2n_errno = S2N_ERR_OK;
return bytes_read;
}
/* If we get here, it's an error condition */
if (s2n_errno != S2N_ERR_IO_BLOCKED && s2n_allowed_to_cache_connection(conn) && conn->session_id_len) {
conn->config->cache_delete(conn, conn->config->cache_delete_data, conn->session_id, conn->session_id_len);
}
S2N_ERROR_PRESERVE_ERRNO();
}
S2N_ERROR_IF(isSSLv2, S2N_ERR_BAD_MESSAGE);
if (record_type != TLS_HANDSHAKE) {
/*
*= https://tools.ietf.org/rfc/rfc8446#section-5.1
*# - Handshake messages MUST NOT be interleaved with other record
*# types. That is, if a handshake message is split over two or more
*# records, there MUST NOT be any other records between them.
*/
POSIX_ENSURE(s2n_stuffer_is_wiped(&conn->post_handshake.in), S2N_ERR_BAD_MESSAGE);
/* If not handling a handshake message, free the post-handshake memory.
* Post-handshake messages are infrequent enough that we don't want to
* keep a potentially large buffer around unnecessarily.
*/
if (!s2n_stuffer_is_freed(&conn->post_handshake.in)) {
POSIX_GUARD(s2n_stuffer_free(&conn->post_handshake.in));
}
}
if (record_type != TLS_APPLICATION_DATA) {
switch (record_type) {
case TLS_ALERT:
POSIX_GUARD(s2n_process_alert_fragment(conn));
POSIX_GUARD(s2n_flush(conn, blocked));
break;
case TLS_HANDSHAKE: {
s2n_result result = s2n_post_handshake_recv(conn);
/* Ignore any errors due to insufficient input data from io.
* The next iteration of this loop will attempt to read more input data.
*/
if (s2n_result_is_error(result) && s2n_errno != S2N_ERR_IO_BLOCKED) {
WITH_ERROR_BLINDING(conn, POSIX_GUARD_RESULT(result));
}
break;
}
}
POSIX_GUARD(s2n_stuffer_wipe(&conn->header_in));
POSIX_GUARD(s2n_stuffer_wipe(&conn->in));
conn->in_status = ENCRYPTED;
continue;
}
out.size = MIN(size, s2n_stuffer_data_available(&conn->in));
POSIX_GUARD(s2n_stuffer_erase_and_read(&conn->in, &out));
bytes_read += out.size;
out.data += out.size;
size -= out.size;
/* Are we ready for more encrypted data? */
if (s2n_stuffer_data_available(&conn->in) == 0) {
POSIX_GUARD(s2n_stuffer_wipe(&conn->header_in));
POSIX_GUARD(s2n_stuffer_wipe(&conn->in));
conn->in_status = ENCRYPTED;
}
/* If we've read some data, return it in legacy mode */
if (bytes_read && !conn->config->recv_multi_record) {
break;
}
}
if (s2n_stuffer_data_available(&conn->in) == 0) {
*blocked = S2N_NOT_BLOCKED;
}
return bytes_read;
}
ssize_t s2n_recv(struct s2n_connection *conn, void *buf, ssize_t size, s2n_blocked_status *blocked)
{
POSIX_ENSURE(!conn->recv_in_use, S2N_ERR_REENTRANCY);
conn->recv_in_use = true;
ssize_t result = s2n_recv_impl(conn, buf, size, blocked);
POSIX_GUARD_RESULT(s2n_early_data_record_bytes(conn, result));
/* finish the recv call */
POSIX_GUARD_RESULT(s2n_connection_dynamic_free_in_buffer(conn));
conn->recv_in_use = false;
return result;
}
uint32_t s2n_peek(struct s2n_connection *conn)
{
if (conn == NULL) {
return 0;
}
/* If we have partially buffered an encrypted record,
* we should not report those bytes as available to read.
*/
if (conn->in_status != PLAINTEXT) {
return 0;
}
return s2n_stuffer_data_available(&conn->in);
}
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