=pod

=head1 NAME

SSL_accept_stream, SSL_get_accept_stream_queue_len, SSL_ACCEPT_STREAM_NO_BLOCK -
accept an incoming QUIC stream from a QUIC peer

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 #define SSL_ACCEPT_STREAM_NO_BLOCK

 SSL *SSL_accept_stream(SSL *ssl, uint64_t flags);

 size_t SSL_get_accept_stream_queue_len(SSL *ssl);

=head1 DESCRIPTION

The SSL_accept_stream() function attempts to dequeue an incoming stream from the
given QUIC connection SSL object and returns the newly allocated QUIC stream SSL
object.

If the queue of incoming streams is empty, this function returns NULL (in
nonblocking mode) or waits for an incoming stream (in blocking mode). This
function may still return NULL in blocking mode, for example if the underlying
connection is terminated.

The caller is responsible for managing the lifetime of the returned QUIC stream
SSL object. The lifespan of the parent QUIC connection SSL object must exceed
that of the QUIC stream SSL object; that is, the stream object must be freed
first, using L<SSL_free(3)>.

This function will block if the QUIC connection SSL object is configured in
blocking mode (see L<SSL_set_blocking_mode(3)>), but this may be bypassed by
passing the flag B<SSL_ACCEPT_STREAM_NO_BLOCK> in B<flags>. If this flag is set,
this function never blocks.

SSL_get_accept_stream_queue_len() returns the number of incoming streams
currently waiting in the accept queue.

=begin comment

TODO(QUIC): Revise in MSMT PR to mention threading considerations.

=end comment

Depending on whether default stream functionality is being used, it may be
necessary to explicitly configure the incoming stream rejection policy before
streams can be accepted; see L<SSL_set_incoming_stream_reject_policy(3)>.

=begin comment

TODO(QUIC): Update the above to refer to default stream man(7) page once
man(7) pages are merged

=end comment

=head1 RETURN VALUES

SSL_accept_stream() returns a newly allocated QUIC stream SSL object, or NULL if
no new incoming streams are available, or if the connection has been terminated,
or if called on a SSL object other than a QUIC connection SSL object.

SSL_get_accept_stream_queue_len() returns the number of incoming streams
currently waiting in the accept queue, or 0 if called on a SSL object other than
a QUIC connection SSL object.

=head1 SEE ALSO

L<SSL_new_stream(3)>, L<SSL_set_blocking_mode(3)>, L<SSL_free(3)>

=head1 HISTORY

SSL_accept_stream() and SSL_get_accept_stream_queue_len() were added in OpenSSL
3.2.

=head1 COPYRIGHT

Copyright 2002-2023 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.

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