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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .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>.