SSL_get_rpoll_descriptor¶

NAME¶

SSL_get_rpoll_descriptor, SSL_get_wpoll_descriptor, SSL_net_read_desired, SSL_net_write_desired - obtain information which can be used to determine when network I/O can be performed

SYNOPSIS¶

#include <openssl/ssl.h>

int SSL_get_rpoll_descriptor(SSL *s, BIO_POLL_DESCRIPTOR *desc);
int SSL_get_wpoll_descriptor(SSL *s, BIO_POLL_DESCRIPTOR *desc);
int SSL_net_read_desired(SSL *s);
int SSL_net_write_desired(SSL *s);

DESCRIPTION¶

The functions SSL_get_rpoll_descriptor() and SSL_get_wpoll_descriptor() can be used to determine when an SSL object which represents a QUIC connection can perform useful network I/O, so that an application using a QUIC connection SSL object in nonblocking mode can determine when it should call SSL_handle_events().

On success, these functions output poll descriptors. For more information on poll descriptors, see BIO_get_rpoll_descriptor(3).

The functions SSL_net_read_desired() and SSL_net_write_desired() return 1 or 0 depending on whether the SSL object is currently interested in receiving data from the network and/or writing data to the network respectively. If an SSL object is not interested in reading data from the network at the current time, SSL_net_read_desired() will return 0; likewise, if an SSL object is not interested in writing data to the network at the current time, SSL_net_write_desired() will return 0.

The intention is that an application using QUIC in nonblocking mode can use these calls, in conjunction with SSL_get_event_timeout(3) to wait for network I/O conditions which allow the SSL object to perform useful work. When such a condition arises, SSL_handle_events(3) should be called.

In particular, the expected usage is as follows:

SSL_handle_events() should be called whenever the timeout returned by SSL_get_event_timeout(3) (if any) expires
If the last call to SSL_net_read_desired() returned 1, SSL_handle_events() should be called whenever the poll descriptor output by SSL_get_rpoll_descriptor() becomes readable.
If the last call to SSL_net_write_desired() returned 1, SSL_handle_events() should be called whenever the poll descriptor output by SSL_get_wpoll_descriptor() becomes writable.

The return values of the SSL_net_read_desired() and SSL_net_write_desired() functions may change in response to any call to the SSL object other than SSL_net_read_desired(), SSL_net_write_desired(), SSL_get_rpoll_descriptor(), SSL_get_wpoll_descriptor() and SSL_get_event_timeout().

On non-QUIC SSL objects, calls to SSL_get_rpoll_descriptor() and SSL_get_wpoll_descriptor() function the same as calls to BIO_get_rpoll_descriptor() and BIO_get_wpoll_descriptor() on the respective read and write BIOs configured on the SSL object.

On non-QUIC SSL objects, calls to SSL_net_read_desired() and SSL_net_write_desired() function identically to calls to SSL_want_read() and SSL_want_write() respectively.

RETURN VALUES¶

These functions return 1 on success and 0 on failure.

HISTORY¶

The SSL_get_rpoll_descriptor(), SSL_get_wpoll_descriptor(), SSL_net_read_desired() and SSL_net_write_desired() functions were added in OpenSSL 3.2.

COPYRIGHT¶

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 https://www.openssl.org/source/license.html.