Allow 0 as a valid ret value for mbedtls_ssl_write
This patch modifies the documentation for mbedtls_ssl_write() to allow
0 as a valid return value as this is the correct number of bytes that
should be returned when an empty TLS Application record is sent.
@@ -2907,17 +2907,19 @@ int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
* or MBEDTLS_ERR_SSL_WANT_WRITE or MBEDTLS_ERR_SSL_WANT_READ,
* or another negative error code.
*
- * \note If this function returns something other than a positive value
- * or MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop using
- * the SSL context for reading or writing, and either free it or
- * call \c mbedtls_ssl_session_reset() on it before re-using it
- * for a new connection; the current connection must be closed.
+ * \note If this function returns something other than 0, a positive
+ * value or MBEDTLS_ERR_SSL_WANT_READ/WRITE, you must stop
+ * using the SSL context for reading or writing, and either
+ * free it or call \c mbedtls_ssl_session_reset() on it before
+ * re-using it for a new connection; the current connection
+ * must be closed.
*
* \note When this function returns MBEDTLS_ERR_SSL_WANT_WRITE/READ,
* it must be called later with the *same* arguments,
- * until it returns a positive value. When the function returns
- * MBEDTLS_ERR_SSL_WANT_WRITE there may be some partial
- * data in the output buffer, however this is not yet sent.
+ * until it returns a value greater that or equal to 0. When
+ * the function returns MBEDTLS_ERR_SSL_WANT_WRITE there may be
+ * some partial data in the output buffer, however this is not
+ * yet sent.
*
* \note If the requested length is greater than the maximum
* fragment length (either the built-in limit or the one set
@@ -2926,6 +2928,9 @@ int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
* - with DTLS, MBEDTLS_ERR_SSL_BAD_INPUT_DATA is returned.
* \c mbedtls_ssl_get_max_frag_len() may be used to query the
* active maximum fragment length.
+ *
+ * \note Attempting to write 0 bytes will result in an empty TLS
+ * application record being sent.
*/
int mbedtls_ssl_write( mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len );
