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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>
#include <errno.h>
#include <s2n.h>
#include "error/s2n_errno.h"
#include "tls/s2n_cipher_suites.h"
#include "tls/s2n_connection.h"
#include "tls/s2n_handshake.h"
#include "tls/s2n_post_handshake.h"
#include "tls/s2n_record.h"
#include "stuffer/s2n_stuffer.h"
#include "crypto/s2n_cipher.h"
#include "utils/s2n_safety.h"
#include "utils/s2n_blob.h"
int s2n_flush(struct s2n_connection *conn, s2n_blocked_status * blocked)
{
int w;
*blocked = S2N_BLOCKED_ON_WRITE;
/* Write any data that's already pending */
WRITE:
while (s2n_stuffer_data_available(&conn->out)) {
errno = 0;
w = s2n_connection_send_stuffer(&conn->out, conn, s2n_stuffer_data_available(&conn->out));
if (w < 0) {
if (errno == EWOULDBLOCK || errno == EAGAIN) {
S2N_ERROR(S2N_ERR_IO_BLOCKED);
}
S2N_ERROR(S2N_ERR_IO);
}
conn->wire_bytes_out += w;
}
if (conn->closing) {
conn->closed = 1;
}
GUARD(s2n_stuffer_rewrite(&conn->out));
/* If there's an alert pending out, send that */
if (s2n_stuffer_data_available(&conn->reader_alert_out) == 2) {
struct s2n_blob alert = {0};
alert.data = conn->reader_alert_out.blob.data;
alert.size = 2;
GUARD(s2n_record_write(conn, TLS_ALERT, &alert));
GUARD(s2n_stuffer_rewrite(&conn->reader_alert_out));
conn->closing = 1;
/* Actually write it ... */
goto WRITE;
}
/* Do the same for writer driven alerts */
if (s2n_stuffer_data_available(&conn->writer_alert_out) == 2) {
struct s2n_blob alert = {0};
alert.data = conn->writer_alert_out.blob.data;
alert.size = 2;
GUARD(s2n_record_write(conn, TLS_ALERT, &alert));
GUARD(s2n_stuffer_rewrite(&conn->writer_alert_out));
conn->closing = 1;
/* Actually write it ... */
goto WRITE;
}
*blocked = S2N_NOT_BLOCKED;
return 0;
}
ssize_t s2n_sendv_with_offset(struct s2n_connection *conn, const struct iovec *bufs, ssize_t count, ssize_t offs, s2n_blocked_status *blocked)
{
ssize_t user_data_sent, total_size = 0;
S2N_ERROR_IF(conn->closed, S2N_ERR_CLOSED);
S2N_ERROR_IF(conn->config->quic_enabled, S2N_ERR_UNSUPPORTED_WITH_QUIC);
/* Flush any pending I/O */
GUARD(s2n_flush(conn, blocked));
/* Acknowledge consumed and flushed user data as sent */
user_data_sent = conn->current_user_data_consumed;
*blocked = S2N_BLOCKED_ON_WRITE;
uint16_t max_payload_size = 0;
GUARD_AS_POSIX(s2n_record_max_write_payload_size(conn, &max_payload_size));
/* TLS 1.0 and SSLv3 are vulnerable to the so-called Beast attack. Work
* around this by splitting messages into one byte records, and then
* the remainder can follow as usual.
*/
int cbcHackUsed = 0;
struct s2n_crypto_parameters *writer = conn->server;
if (conn->mode == S2N_CLIENT) {
writer = conn->client;
}
/* Defensive check against an invalid retry */
if (offs) {
const struct iovec* _bufs = bufs;
ssize_t _count = count;
while (offs >= _bufs->iov_len && _count > 0) {
offs -= _bufs->iov_len;
_bufs++;
_count--;
}
bufs = _bufs;
count = _count;
}
for (int i = 0; i < count; i++) {
total_size += bufs[i].iov_len;
}
total_size -= offs;
S2N_ERROR_IF(conn->current_user_data_consumed > total_size, S2N_ERR_SEND_SIZE);
if (conn->dynamic_record_timeout_threshold > 0) {
uint64_t elapsed;
GUARD_AS_POSIX(s2n_timer_elapsed(conn->config, &conn->write_timer, &elapsed));
/* Reset record size back to a single segment after threshold seconds of inactivity */
if (elapsed - conn->last_write_elapsed > (uint64_t) conn->dynamic_record_timeout_threshold * 1000000000) {
conn->active_application_bytes_consumed = 0;
}
conn->last_write_elapsed = elapsed;
}
/* Now write the data we were asked to send this round */
while (total_size - conn->current_user_data_consumed) {
ssize_t to_write = MIN(total_size - conn->current_user_data_consumed, max_payload_size);
/* If dynamic record size is enabled,
* use small TLS records that fit into a single TCP segment for the threshold bytes of data
*/
if (conn->active_application_bytes_consumed < (uint64_t) conn->dynamic_record_resize_threshold) {
uint16_t min_payload_size = 0;
GUARD_AS_POSIX(s2n_record_min_write_payload_size(conn, &min_payload_size));
to_write = MIN(min_payload_size, to_write);
}
/* Don't split messages in server mode for interoperability with naive clients.
* Some clients may have expectations based on the amount of content in the first record.
*/
if (conn->actual_protocol_version < S2N_TLS11 && writer->cipher_suite->record_alg->cipher->type == S2N_CBC && conn->mode != S2N_SERVER) {
if (to_write > 1 && cbcHackUsed == 0) {
to_write = 1;
cbcHackUsed = 1;
}
}
GUARD(s2n_stuffer_rewrite(&conn->out));
GUARD(s2n_post_handshake_send(conn, blocked));
/* Write and encrypt the record */
GUARD(s2n_record_writev(conn, TLS_APPLICATION_DATA, bufs, count,
conn->current_user_data_consumed + offs, to_write));
conn->current_user_data_consumed += to_write;
conn->active_application_bytes_consumed += to_write;
/* Send it */
if (s2n_flush(conn, blocked) < 0) {
if (s2n_errno == S2N_ERR_IO_BLOCKED && user_data_sent > 0) {
/* We successfully sent >0 user bytes on the wire, but not the full requested payload
* because we became blocked on I/O. Acknowledge the data sent. */
conn->current_user_data_consumed -= user_data_sent;
return user_data_sent;
} else {
S2N_ERROR_PRESERVE_ERRNO();
}
}
/* Acknowledge consumed and flushed user data as sent */
user_data_sent = conn->current_user_data_consumed;
}
/* If everything has been written, then there's no user data pending */
conn->current_user_data_consumed = 0;
*blocked = S2N_NOT_BLOCKED;
return total_size;
}
ssize_t s2n_sendv(struct s2n_connection *conn, const struct iovec *bufs, ssize_t count, s2n_blocked_status *blocked)
{
return s2n_sendv_with_offset(conn, bufs, count, 0, blocked);
}
ssize_t s2n_send(struct s2n_connection *conn, const void *buf, ssize_t size, s2n_blocked_status *blocked)
{
struct iovec iov;
iov.iov_base = (void*)(uintptr_t)buf;
iov.iov_len = size;
return s2n_sendv_with_offset(conn, &iov, 1, 0, blocked);
}
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