Make datagram packing dynamically configurable

This commit adds a public function

   `mbedtls_ssl_conf_datagram_packing()`

that allows to allow / forbid the packing of multiple
records within a single datagram.
This commit is contained in:
Hanno Becker 2018-08-14 13:22:10 +01:00
parent 12405e76b5
commit 04da189225
2 changed files with 50 additions and 3 deletions

View File

@ -1102,6 +1102,11 @@ struct mbedtls_ssl_context
int keep_current_message; /*!< drop or reuse current message
on next call to record layer? */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
uint8_t disable_datagram_packing; /*!< Disable packing multiple records
* within a single datagram. */
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/*
* Record layer (outgoing data)
*/
@ -1763,6 +1768,38 @@ void mbedtls_ssl_conf_dtls_badmac_limit( mbedtls_ssl_config *conf, unsigned limi
#endif /* MBEDTLS_SSL_DTLS_BADMAC_LIMIT */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
/**
* \brief Allow or disallow packing of multiple handshake records
* within a single datagram.
*
* \param ssl The SSL context to configure.
* \param allow_packing This determines whether datagram packing may
* be used or not. A value of \c 0 means that every
* record will be sent in a separate datagram; a
* value of \c 1 means that, if space permits,
* multiple handshake messages (including CCS) belonging to
* a single flight may be packed within a single datagram.
*
* \note This is enabled by default and should only be disabled
* for test purposes, or if datagram packing causes
* interoperability issues with peers that don't support it.
*
* \note Allowing datagram packing reduces the network load since
* there's less overhead if multiple messages share the same
* datagram. Also, it increases the handshake efficiency
* since messages belonging to a single datagram will not
* be reordered in transit, and so future message buffering
* or flight retransmission (if no buffering is used) as
* means to deal with reordering are needed less frequently.
*
* \note Application datagrams are not affected by this option and
* are currently always sent in separate datagrams.
*
*/
void mbedtls_ssl_conf_datagram_packing( mbedtls_ssl_context *ssl,
unsigned allow_packing );
/**
* \brief Set retransmit timeout values for the DTLS handshake.
* (DTLS only, no effect on TLS.)

View File

@ -2923,6 +2923,9 @@ int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
size_t max_frag_len;
const mbedtls_ssl_flight_item * const cur = ssl->handshake->cur_msg;
uint8_t const force_flush = ssl->disable_datagram_packing == 1 ?
SSL_FORCE_FLUSH : SSL_DONT_FORCE_FLUSH;
/* Swap epochs before sending Finished: we can't do it after
* sending ChangeCipherSpec, in case write returns WANT_READ.
* Must be done before copying, may change out_msg pointer */
@ -3030,8 +3033,7 @@ int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
}
/* Actually send the message out */
if( ( ret = mbedtls_ssl_write_record( ssl,
SSL_DONT_FORCE_FLUSH ) ) != 0 )
if( ( ret = mbedtls_ssl_write_record( ssl, force_flush ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
return( ret );
@ -6432,7 +6434,15 @@ void mbedtls_ssl_conf_dtls_badmac_limit( mbedtls_ssl_config *conf, unsigned limi
#endif
#if defined(MBEDTLS_SSL_PROTO_DTLS)
void mbedtls_ssl_conf_handshake_timeout( mbedtls_ssl_config *conf, uint32_t min, uint32_t max )
void mbedtls_ssl_conf_datagram_packing( mbedtls_ssl_context *ssl,
unsigned allow_packing )
{
ssl->disable_datagram_packing = !allow_packing;
}
void mbedtls_ssl_conf_handshake_timeout( mbedtls_ssl_config *conf,
uint32_t min, uint32_t max )
{
conf->hs_timeout_min = min;
conf->hs_timeout_max = max;