SSL_pending

SSL_PENDING(3)                       OpenSSL                      SSL_PENDING(3)



NAME
       SSL_pending, SSL_has_pending - check for readable bytes buffered in an
       SSL object

SYNOPSIS
        #include <openssl/ssl.h>

        int SSL_pending(const SSL *ssl);
        int SSL_has_pending(const SSL *s);

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 SSL_read_ex(3) or
       SSL_read(3).

       SSL_pending() returns the number of bytes which have been processed,
       buffered and are available inside ssl for immediate read.

       If the SSL object's read_ahead flag is set (see
       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 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 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_ex() or 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_ex() or 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).

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.

SEE ALSO
       SSL_read_ex(3), SSL_read(3), SSL_CTX_set_read_ahead(3),
       SSL_CTX_set_split_send_fragment(3), ssl(7)

HISTORY
       The SSL_has_pending() function was added in OpenSSL 1.1.0.

COPYRIGHT
       Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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>.



1.1.1l                             2021-08-24                     SSL_PENDING(3)