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.\" ========================================================================
.\"
.IX Title "SSL_PENDING 3"
.TH SSL_PENDING 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
SSL_pending, SSL_has_pending \- check for readable bytes buffered in an SSL object
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/ssl.h>
\&
\& int SSL_pending(const SSL *ssl);
\& int SSL_has_pending(const SSL *s);
.Ve
.SH "DESCRIPTION"
.IX Header "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 \fBSSL_read_ex\fR\|(3) or \fBSSL_read\fR\|(3).
.PP
\&\fBSSL_pending()\fR returns the number of bytes which have been processed, buffered
and are available inside \fBssl\fR for immediate read.
.PP
If the \fB\s-1SSL\s0\fR object's \fIread_ahead\fR flag is set (see
\&\fBSSL_CTX_set_read_ahead\fR\|(3)), additional protocol bytes (beyond the current
record) may have been read containing more \s-1TLS/SSL\s0 records. This also applies to
\&\s-1DTLS\s0 and pipelining (see \fBSSL_CTX_set_split_send_fragment\fR\|(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 \fBSSL_pending()\fR
will ignore them. Therefore, it is possible for no more bytes to be readable from
the underlying \s-1BIO\s0 (because OpenSSL has already read them) and for \fBSSL_pending()\fR
to return 0, even though readable application data bytes are available (because
the data is in unprocessed buffered records).
.PP
\&\fBSSL_has_pending()\fR returns 1 if \fBs\fR has buffered data (whether processed or
unprocessed) and 0 otherwise. Note that it is possible for \fBSSL_has_pending()\fR to
return 1, and then a subsequent call to \fBSSL_read_ex()\fR or \fBSSL_read()\fR 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 \fBSSL_has_pending()\fR to continue to return 1 even after an
\&\fBSSL_read_ex()\fR or \fBSSL_read()\fR call because the buffered and unprocessed data is
not yet processable (e.g. because OpenSSL has only received a partial record so
far).
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBSSL_pending()\fR returns the number of buffered and processed application data
bytes that are pending and are available for immediate read. \fBSSL_has_pending()\fR
returns 1 if there is buffered record data in the \s-1SSL\s0 object and 0 otherwise.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBSSL_read_ex\fR\|(3), \fBSSL_read\fR\|(3), \fBSSL_CTX_set_read_ahead\fR\|(3),
\&\fBSSL_CTX_set_split_send_fragment\fR\|(3), \fBssl\fR\|(7)
.SH "HISTORY"
.IX Header "HISTORY"
The \fBSSL_has_pending()\fR function was added in OpenSSL 1.1.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2000\-2020 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.