mirror of
https://github.com/openssl/openssl.git
synced 2024-11-27 05:21:51 +08:00
60 lines
2.3 KiB
Plaintext
60 lines
2.3 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
SSL_pending, SSL_has_pending - check for readable bytes buffered in an
|
|
SSL object
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/ssl.h>
|
|
|
|
int SSL_pending(const SSL *ssl);
|
|
int SSL_has_pending(const SSL *s);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
Data is received in whole blocks known as records from the peer. A whole record
|
|
is processed (e.g. decrypted) in one go and is buffered by OpenSSL until it is
|
|
read by the application via a call to L<SSL_read(3)>.
|
|
|
|
SSL_pending() returns the number of bytes which have been processed, buffered
|
|
and are available inside B<ssl> for immediate read.
|
|
|
|
If the B<SSL> object's I<read_ahead> flag is set (see
|
|
L<SSL_CTX_set_read_ahead(3)>), additional protocol bytes (beyond the current
|
|
record) may have been read containing more TLS/SSL records. This also applies to
|
|
DTLS and pipelining (see L<SSL_CTX_set_split_send_fragment(3)>). These
|
|
additional bytes will be buffered by OpenSSL but will remain unprocessed until
|
|
they are needed. As these bytes are still in an unprocessed state SSL_pending()
|
|
will ignore them. Therefore it is possible for no more bytes to be readable from
|
|
the underlying BIO (because OpenSSL has already read them) and for SSL_pending()
|
|
to return 0, even though readable application data bytes are available (because
|
|
the data is in unprocessed buffered records).
|
|
|
|
SSL_has_pending() returns 1 if B<s> has buffered data (whether processed or
|
|
unprocessed) and 0 otherwise. Note that it is possible for SSL_has_pending() to
|
|
return 1, and then a subsequent call to SSL_read() to return no data because the
|
|
unprocessed buffered data when processed yielded no application data (for
|
|
example this can happen during renegotiation). It is also possible in this
|
|
scenario for SSL_has_pending() to continue to return 1 even after an SSL_read()
|
|
call because the buffered and unprocessed data is not yet processable (e.g.
|
|
because OpenSSL has only received a partial record so far).
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
SSL_pending() returns the number of buffered and processed application data
|
|
bytes that are pending and are available for immediate read. SSL_has_pending()
|
|
returns 1 if there is buffered record data in the SSL object and 0 otherwise.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<SSL_read(3)>, L<SSL_CTX_set_read_ahead(3)>,
|
|
L<SSL_CTX_set_split_send_fragment(3)>, L<ssl(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
The SSL_has_pending() function was added in OpenSSL 1.1.0.
|
|
|
|
=cut
|