diff options
Diffstat (limited to 'doc/cha-gtls-app.texi')
| -rw-r--r-- | doc/cha-gtls-app.texi | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/doc/cha-gtls-app.texi b/doc/cha-gtls-app.texi index d787d0f44c..37b00514da 100644 --- a/doc/cha-gtls-app.texi +++ b/doc/cha-gtls-app.texi @@ -792,6 +792,7 @@ remaining until the next retransmission, or better the time until @menu * Asynchronous operation:: +* Reducing round-trips:: * DTLS sessions:: @end menu @@ -859,6 +860,31 @@ the function @funcref{gnutls_dtls_get_timeout} should be used to estimate when to call @funcref{gnutls_handshake} if no data have been received. +@node Reducing round-trips +@subsection Reducing round-trips + +The full TLS 1.2 handshake requires 2 round-trips to complete, and when +combined with TCP's SYN and SYN-ACK negotiation it extends to 3 full +round-trips. While, the abbreviated (resumed) TLS handshake drops that to 2.5 +round-trips, it still adds considerable latency, reducing its applicability +to certain applications. + +In client side, it is possible to take advantage of the TCP fast open +@xcite{RFC7413} mechanism on operating +systems that support it. That can be done either by manually crafting the push and pull +callbacks, or by utilizing @funcref{gnutls_transport_set_fastopen}. In that +case the initial TCP handshake is eliminated, reducing the TLS handshake round-trip to 2. +Note, that in that case any connection failures will be reported during the +@funcref{gnutls_handshake} function call with error code +@code{GNUTLS_E_PUSH_ERROR}. + +@showfuncdesc{gnutls_transport_set_fastopen} + +In non-resumed sessions it is possible to further reduce the round-trips to +a single one by taking advantage of the @ref{False Start} TLS extension. +This can be enabled by setting the @acronym{GNUTLS_ENABLE_FALSE_START} flag +on @funcref{gnutls_init}. + @node DTLS sessions @subsection DTLS sessions |