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SSL_pending(3)                      OpenSSL                     SSL_pending(3)



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

LIBRARY
       libcrypto, -lcrypto

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 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>.



3.0.12                            2023-05-07                    SSL_pending(3)