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| author | Nikos Mavrogiannopoulos <nmav@gnutls.org> | 2015-05-03 19:51:28 +0200 |
|---|---|---|
| committer | Nikos Mavrogiannopoulos <nmav@gnutls.org> | 2015-05-03 19:51:28 +0200 |
| commit | 05c7bed3ff47dea3e964e7bcb89e615b3cb40342 (patch) | |
| tree | c60da5e67dad3c93f4316414e7a3b1f19b6f7b3a /manual/html_node/Asynchronous-operation.html | |
| parent | e9bf4cc7f5608188e2b9a63f29785e7ce4b388a7 (diff) | |
| download | gnutls-05c7bed3ff47dea3e964e7bcb89e615b3cb40342.tar.gz | |
updated manual for 3.4.1
Diffstat (limited to 'manual/html_node/Asynchronous-operation.html')
| -rw-r--r-- | manual/html_node/Asynchronous-operation.html | 55 |
1 files changed, 36 insertions, 19 deletions
diff --git a/manual/html_node/Asynchronous-operation.html b/manual/html_node/Asynchronous-operation.html index c6ce719aec..a2db501783 100644 --- a/manual/html_node/Asynchronous-operation.html +++ b/manual/html_node/Asynchronous-operation.html @@ -1,7 +1,7 @@ <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <!-- This manual is last updated 4 March 2015 for version -3.4.0 of GnuTLS. +3.4.1 of GnuTLS. Copyright (C) 2001-2015 Free Software Foundation, Inc.\\ Copyright (C) 2001-2015 Nikos Mavrogiannopoulos @@ -14,10 +14,10 @@ copy of the license is included in the section entitled "GNU Free Documentation License". --> <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> <head> -<title>GnuTLS 3.4.0: Asynchronous operation</title> +<title>GnuTLS 3.4.1: Asynchronous operation</title> -<meta name="description" content="GnuTLS 3.4.0: Asynchronous operation"> -<meta name="keywords" content="GnuTLS 3.4.0: Asynchronous operation"> +<meta name="description" content="GnuTLS 3.4.1: Asynchronous operation"> +<meta name="keywords" content="GnuTLS 3.4.1: Asynchronous operation"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="makeinfo"> @@ -164,6 +164,7 @@ Next: <a href="DTLS-sessions.html#DTLS-sessions" accesskey="n" rel="next">DTLS s <hr> <a name="Asynchronous-operation-1"></a> <h4 class="subsection">6.5.1 Asynchronous operation</h4> + <p><acronym>GnuTLS</acronym> can be used with asynchronous socket or event-driven programming. The approach is similar to using Berkeley sockets under such an environment. The blocking, due to network interaction, calls such as @@ -180,18 +181,36 @@ The only exception is <a href="Core-TLS-API.html#gnutls_005frecord_005fsend">gnu which if interrupted subsequent calls need not to include the data to be sent (can be called with NULL argument). </p> -<p>The <code>select</code> system call can also be used in combination with the -<acronym>GnuTLS</acronym> functions. <code>select</code> allows monitoring of sockets -and notifies on them being ready for reading or writing data. Note however -that this system call cannot notify on data present in <acronym>GnuTLS</acronym> -read buffers, it is only applicable to the kernel sockets API. Thus if -you are using it for reading from a <acronym>GnuTLS</acronym> session, make sure -that any cached data are read completely. That can be achieved by checking there -are no data waiting to be read (using <a href="Core-TLS-API.html#gnutls_005frecord_005fcheck_005fpending">gnutls_record_check_pending</a>), +<p>When using the <code>select</code> system call though, one should remember +that it is only applicable to the kernel sockets API. To check for any +available buffers in a <acronym>GnuTLS</acronym> session, +utilize <a href="Core-TLS-API.html#gnutls_005frecord_005fcheck_005fpending">gnutls_record_check_pending</a>, either before the <code>select</code> system call, or after a call to <a href="Core-TLS-API.html#gnutls_005frecord_005frecv">gnutls_record_recv</a>. <acronym>GnuTLS</acronym> does not keep a write buffer, thus when writing no additional actions are required. </p> +<p>The following paragraphs describe the detailed requirements for non-blocking +operation when using the TLS or DTLS protocols. +</p> +<a name="TLS-protocol"></a> +<h4 class="subsubsection">6.5.1.1 TLS protocol</h4> +<p>There are no special requirements for the TLS protocol operation in non-blocking +mode if a non-blocking socket is used. +</p> +<p>It is recommended, however, for future compatibility, when in non-blocking mode, to +call the <a href="Core-TLS-API.html#gnutls_005finit">gnutls_init</a> function with the +<code>GNUTLS_NONBLOCK</code> flag set (see <a href="Session-initialization.html#Session-initialization">Session initialization</a>). +</p> +<a name="Datagram-TLS-protocol"></a> +<h4 class="subsubsection">6.5.1.2 Datagram TLS protocol</h4> +<p>When in non-blocking mode the function, the <a href="Core-TLS-API.html#gnutls_005finit">gnutls_init</a> function +must be called with the <code>GNUTLS_NONBLOCK</code> flag set (see <a href="Session-initialization.html#Session-initialization">Session initialization</a>). +</p> +<p>In constrast with the TLS protocol, the pull timeout function is required, +but will only be called with a timeout of zero. In that case it should indicate +whether there are data to be received or not. When not using the default pull function, +then <a href="Core-TLS-API.html#gnutls_005ftransport_005fset_005fpull_005ftimeout_005ffunction">gnutls_transport_set_pull_timeout_function</a> should be called. +</p> <p>Although in the TLS protocol implementation each call to receive or send function implies to restoring the same function that was interrupted, in the DTLS protocol this requirement isn’t true. @@ -223,14 +242,12 @@ trying to write data. <p><strong>Returns:</strong> 0 if trying to read data, 1 if trying to write data. </p></dd></dl> -<p>Moreover, to prevent blocking from DTLS’ retransmission timers to block a -handshake, the <a href="Core-TLS-API.html#gnutls_005finit">gnutls_init</a> function should be called with the -<code>GNUTLS_NONBLOCK</code> flag set (see <a href="Session-initialization.html#Session-initialization">Session initialization</a>). In that -case, in order to be able to use the DTLS handshake timers, the function -<a href="Datagram-TLS-API.html#gnutls_005fdtls_005fget_005ftimeout">gnutls_dtls_get_timeout</a> should be used to estimate when to call -<a href="Core-TLS-API.html#gnutls_005fhandshake">gnutls_handshake</a> if no packets have been received. +<p>When calling <a href="Core-TLS-API.html#gnutls_005fhandshake">gnutls_handshake</a> through a multi-plexer, +to be able to handle properly the DTLS handshake retransmission timers, +the function <a href="Datagram-TLS-API.html#gnutls_005fdtls_005fget_005ftimeout">gnutls_dtls_get_timeout</a> +should be used to estimate when to call <a href="Core-TLS-API.html#gnutls_005fhandshake">gnutls_handshake</a> if +no data have been received. </p> - <hr> <div class="header"> <p> |