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Refactor record size limit extension handling

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Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
This commit is contained in:
Waleed Elmelegy
2023-12-20 17:28:31 +00:00
parent 26e3698357
commit 049cd302ed
6 changed files with 65 additions and 40 deletions
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45
library/ssl_tls.c
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@ -2492,7 +2492,7 @@ static int ssl_tls13_session_save(const mbedtls_ssl_session *session,
needed += 4; /* max_early_data_size */
#endif
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
needed += 2; /* record_size_limit */
needed += 2; /* record_size_limit */
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
#if defined(MBEDTLS_HAVE_TIME)
@ -3420,6 +3420,31 @@ size_t mbedtls_ssl_get_input_max_frag_len(const mbedtls_ssl_context *ssl)
return max_len;
}
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
size_t mbedtls_ssl_get_output_record_size_limit(const mbedtls_ssl_context *ssl)
{
const size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
size_t record_size_limit = max_len;
if (ssl->session != NULL &&
ssl->session->record_size_limit >= MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN &&
ssl->session->record_size_limit < max_len) {
record_size_limit = ssl->session->record_size_limit;
}
// TODO: this is currently untested
/* During a handshake, use the value being negotiated */
if (ssl->session_negotiate != NULL &&
ssl->session_negotiate->record_size_limit >= MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN &&
ssl->session_negotiate->record_size_limit < max_len) {
record_size_limit = ssl->session_negotiate->record_size_limit;
}
return record_size_limit;
}
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
size_t mbedtls_ssl_get_output_max_frag_len(const mbedtls_ssl_context *ssl)
{
size_t max_len;
@ -3491,6 +3516,21 @@ int mbedtls_ssl_get_max_out_record_payload(const mbedtls_ssl_context *ssl)
if (max_len > record_size_limit) {
max_len = record_size_limit;
if (ssl->transform_out != NULL &&
ssl->transform_out->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
/* RFC 8449, section 4:
*
* This value [record_size_limit] is the length of the plaintext
* of a protected record.
* The value includes the content type and padding added in TLS 1.3
* (that is, the complete length of TLSInnerPlaintext).
*
* Thus, round down to a multiple of MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY
* and subtract 1 (for the content type that will be added later)
*/
max_len = ((max_len / MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY) *
MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY) - 1;
}
}
#endif
@ -3516,7 +3556,8 @@ int mbedtls_ssl_get_max_out_record_payload(const mbedtls_ssl_context *ssl)
#endif /* MBEDTLS_SSL_PROTO_DTLS */
#if !defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) && \
!defined(MBEDTLS_SSL_PROTO_DTLS)
!defined(MBEDTLS_SSL_PROTO_DTLS) && \
!defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
((void) ssl);
#endif