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Document ssl_write_real() behaviour in detail

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Andres Amaya Garcia 2017-09-28 14:41:17 +01:00 committed by Andres Amaya Garcia
parent 7ee25d770d
commit 5b92352374
1 changed files with 21 additions and 2 deletions
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23
library/ssl_tls.c
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@ -7231,8 +7231,16 @@ int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
}
/*
* Send application data to be encrypted by the SSL layer,
* taking care of max fragment length and buffer size
* Send application data to be encrypted by the SSL layer, taking care of max
* fragment length and buffer size.
*
* According to RFC 5246 Section 6.2.1:
*
* Zero-length fragments of Application data MAY be sent as they are
* potentially useful as a traffic analysis countermeasure.
*
* Therefore, it is possible that the input message length is 0 and the
* corresponding return code is 0 on success.
*/
static int ssl_write_real( mbedtls_ssl_context *ssl,
const unsigned char *buf, size_t len )
@ -7260,6 +7268,12 @@ static int ssl_write_real( mbedtls_ssl_context *ssl,
if( ssl->out_left != 0 )
{
/*
* The user has previously tried to send the data and
* MBEDTLS_ERR_SSL_WANT_WRITE or the message was only partially
* written. In this case, we expect the high-level write function
* (e.g. mbedtls_ssl_write()) to be called with the same parameters
*/
if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
@ -7268,6 +7282,11 @@ static int ssl_write_real( mbedtls_ssl_context *ssl,
}
else
{
/*
* The user is trying to send a message the first time, so we need to
* copy the data into the internal buffers and setup the data structure
* to keep track of partial writes
*/
ssl->out_msglen = len;
ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA;
memcpy( ssl->out_msg, buf, len );