Clarify use of mbedtls_ssl_check_pending

This commit is contained in:
Hanno Becker 2017-10-31 13:00:14 +00:00
parent 197a91cd82
commit 9b19a1253f

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@ -2243,15 +2243,6 @@ void mbedtls_ssl_conf_renegotiation_period( mbedtls_ssl_config *conf,
*
* \return 0 if nothing's pending, 1 otherwise.
*
* \note This function is essential when using the library
* with event-driven I/O. You should not idle
* (waiting for events from the underlying transport
* or from timers) before this function's check passes.
* Otherwise, it's possible to run into a deadlock
* (if processing the pending data involves essential
* communication with the peer) or to accumulate and
* potentially lose data.
*
* \note This is different in purpose and behaviour from
* \c mbedtls_ssl_get_bytes_avail in that it considers
* any kind of unprocessed data, not only unread
@ -2262,11 +2253,25 @@ void mbedtls_ssl_conf_renegotiation_period( mbedtls_ssl_config *conf,
* further records waiting to be processed from
* the current underlying transport's datagram.
*
* \note If this function returns 0 (data pending), this
* \note If this function returns 1 (data pending), this
* does not imply that a subsequent call to
* \c mbedtls_ssl_read will provide any data;
* e.g., the unprocessed data might turn out
* to be an alert or a handshake message.
*
* \note This function is useful in the following situation:
* If the SSL/TLS module successfully returns from an
* operation - e.g. a handshake or an application record
* read - and you're awaiting incoming data next, you
* must not immediately idle on the underlying transport
* to have data ready, but you need to check the value
* of this function first. The reason is that the desired
* data might already be read but not yet processed.
* If, in contrast, a previous call to the SSL/TLS module
* returned MBEDTLS_ERR_SSL_WANT_READ, it is not necessary
* to call this function, as the latter error code entails
* that all internal data has been processed.
*
*/
int mbedtls_ssl_check_pending( const mbedtls_ssl_context *ssl );