Android_verify/third_party/android-libs/share/man/man3/SSL_handle_events.3ossl

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.\" ========================================================================
.\"
.IX Title "SSL_HANDLE_EVENTS 3ossl"
.TH SSL_HANDLE_EVENTS 3ossl "2024-09-03" "3.3.2" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
SSL_handle_events \- advance asynchronous state machine and perform network I/O
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ssl.h>
\&
\& int SSL_handle_events(SSL *ssl);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBSSL_handle_events()\fR performs any internal processing which is due on a \s-1SSL\s0 object. The
exact operations performed by \fBSSL_handle_events()\fR vary depending on what kind of protocol
is being used with the given \s-1SSL\s0 object. For example, \fBSSL_handle_events()\fR may handle
timeout events which have become due, or may attempt, to the extent currently
possible, to perform network I/O operations on one of the BIOs underlying the
\&\s-1SSL\s0 object.
.PP
The primary use case for \fBSSL_handle_events()\fR is to allow an application which uses
OpenSSL in nonblocking mode to give OpenSSL an opportunity to handle timer
events, or to respond to the availability of new data to be read from an
underlying \s-1BIO,\s0 or to respond to the opportunity to write pending data to an
underlying \s-1BIO.\s0
.PP
\&\fBSSL_handle_events()\fR can be used only with the following types of \s-1SSL\s0 object:
.IP "\s-1DTLS SSL\s0 objects" 4
.IX Item "DTLS SSL objects"
Using \fBSSL_handle_events()\fR on an \s-1SSL\s0 object being used with a \s-1DTLS\s0 method allows timeout
events to be handled properly. This is equivalent to a call to
\&\fBDTLSv1_handle_timeout\fR\|(3). Since \fBSSL_handle_events()\fR handles a superset of the use
cases of \fBDTLSv1_handle_timeout\fR\|(3), it should be preferred for new
applications which do not require support for OpenSSL 3.1 or older.
.Sp
When using \s-1DTLS,\s0 an application must call \fBSSL_handle_events()\fR as indicated by
calls to \fBSSL_get_event_timeout\fR\|(3); event handling is not performed
automatically by calls to other \s-1SSL\s0 functions such as \fBSSL_read\fR\|(3) or
\&\fBSSL_write\fR\|(3). Note that this is different to \s-1QUIC\s0 which also performs event
handling implicitly; see below.
.IP "\s-1QUIC\s0 connection \s-1SSL\s0 objects" 4
.IX Item "QUIC connection SSL objects"
Using \fBSSL_handle_events()\fR on an \s-1SSL\s0 object which represents a \s-1QUIC\s0 connection allows
timeout events to be handled properly, as well as incoming network data to be
processed, and queued outgoing network data to be written, if the underlying \s-1BIO\s0
has the capacity to accept it.
.Sp
Ordinarily, when an application uses an \s-1SSL\s0 object in blocking mode, it does not
need to call \fBSSL_handle_events()\fR because OpenSSL performs ticking internally on an
automatic basis. However, if an application uses a \s-1QUIC\s0 connection in
nonblocking mode, it must at a minimum ensure that \fBSSL_handle_events()\fR is called
periodically to allow timeout events to be handled. An application can find out
when it next needs to call \fBSSL_handle_events()\fR for this purpose (if at all) by calling
\&\fBSSL_get_event_timeout\fR\|(3).
.Sp
Calling \fBSSL_handle_events()\fR on a \s-1QUIC\s0 connection \s-1SSL\s0 object being used in blocking mode
is not necessary unless no I/O calls (such as \fBSSL_read\fR\|(3) or \fBSSL_write\fR\|(3))
will be made to the object for a substantial period of time. So long as at least
one call to the \s-1SSL\s0 object is blocking, no such call is needed. However,
\&\fBSSL_handle_events()\fR may optionally be used on a \s-1QUIC\s0 connection object if desired.
.Sp
With the thread-assisted mode of operation \fBOSSL_QUIC_client_thread_method\fR\|(3)
it is unnecessary to call \fBSSL_handle_events()\fR as the assist thread handles the \s-1QUIC\s0
connection events.
.PP
Calling \fBSSL_handle_events()\fR on any other kind of \s-1SSL\s0 object is a no-op. This is
considered a success case.
.PP
Note that \fBSSL_handle_events()\fR supersedes the older \fBDTLSv1_handle_timeout\fR\|(3) function
for all use cases.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
Returns 1 on success and 0 on failure.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBSSL_get_event_timeout\fR\|(3), \fBDTLSv1_handle_timeout\fR\|(3), \fBssl\fR\|(7)
.SH "HISTORY"
.IX Header "HISTORY"
The \fBSSL_handle_events()\fR function was added in OpenSSL 3.2.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.