113d40330Schristos=pod 213d40330Schristos 313d40330Schristos=head1 NAME 413d40330Schristos 513d40330SchristosSSL_pending, SSL_has_pending - check for readable bytes buffered in an 613d40330SchristosSSL object 713d40330Schristos 813d40330Schristos=head1 SYNOPSIS 913d40330Schristos 1013d40330Schristos #include <openssl/ssl.h> 1113d40330Schristos 1213d40330Schristos int SSL_pending(const SSL *ssl); 1313d40330Schristos int SSL_has_pending(const SSL *s); 1413d40330Schristos 1513d40330Schristos=head1 DESCRIPTION 1613d40330Schristos 1713d40330SchristosData is received in whole blocks known as records from the peer. A whole record 1813d40330Schristosis processed (e.g. decrypted) in one go and is buffered by OpenSSL until it is 1913d40330Schristosread by the application via a call to L<SSL_read_ex(3)> or L<SSL_read(3)>. 2013d40330Schristos 2113d40330SchristosSSL_pending() returns the number of bytes which have been processed, buffered 2213d40330Schristosand are available inside B<ssl> for immediate read. 2313d40330Schristos 2413d40330SchristosIf the B<SSL> object's I<read_ahead> flag is set (see 2513d40330SchristosL<SSL_CTX_set_read_ahead(3)>), additional protocol bytes (beyond the current 2613d40330Schristosrecord) may have been read containing more TLS/SSL records. This also applies to 2713d40330SchristosDTLS and pipelining (see L<SSL_CTX_set_split_send_fragment(3)>). These 2813d40330Schristosadditional bytes will be buffered by OpenSSL but will remain unprocessed until 2913d40330Schristosthey are needed. As these bytes are still in an unprocessed state SSL_pending() 30f30e0929Schristoswill ignore them. Therefore, it is possible for no more bytes to be readable from 3113d40330Schristosthe underlying BIO (because OpenSSL has already read them) and for SSL_pending() 3213d40330Schristosto return 0, even though readable application data bytes are available (because 3313d40330Schristosthe data is in unprocessed buffered records). 3413d40330Schristos 3513d40330SchristosSSL_has_pending() returns 1 if B<s> has buffered data (whether processed or 3613d40330Schristosunprocessed) and 0 otherwise. Note that it is possible for SSL_has_pending() to 3713d40330Schristosreturn 1, and then a subsequent call to SSL_read_ex() or SSL_read() to return no 3813d40330Schristosdata because the unprocessed buffered data when processed yielded no application 3913d40330Schristosdata (for example this can happen during renegotiation). It is also possible in 4013d40330Schristosthis scenario for SSL_has_pending() to continue to return 1 even after an 4113d40330SchristosSSL_read_ex() or SSL_read() call because the buffered and unprocessed data is 4213d40330Schristosnot yet processable (e.g. because OpenSSL has only received a partial record so 4313d40330Schristosfar). 4413d40330Schristos 4513d40330Schristos=head1 RETURN VALUES 4613d40330Schristos 4713d40330SchristosSSL_pending() returns the number of buffered and processed application data 4813d40330Schristosbytes that are pending and are available for immediate read. SSL_has_pending() 4913d40330Schristosreturns 1 if there is buffered record data in the SSL object and 0 otherwise. 5013d40330Schristos 5113d40330Schristos=head1 SEE ALSO 5213d40330Schristos 5313d40330SchristosL<SSL_read_ex(3)>, L<SSL_read(3)>, L<SSL_CTX_set_read_ahead(3)>, 5413d40330SchristosL<SSL_CTX_set_split_send_fragment(3)>, L<ssl(7)> 5513d40330Schristos 5613d40330Schristos=head1 HISTORY 5713d40330Schristos 5813d40330SchristosThe SSL_has_pending() function was added in OpenSSL 1.1.0. 5913d40330Schristos 6013d40330Schristos=head1 COPYRIGHT 6113d40330Schristos 62f30e0929SchristosCopyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. 6313d40330Schristos 64*b0d17251SchristosLicensed under the Apache License 2.0 (the "License"). You may not use 6513d40330Schristosthis file except in compliance with the License. You can obtain a copy 6613d40330Schristosin the file LICENSE in the source distribution or at 6713d40330SchristosL<https://www.openssl.org/source/license.html>. 6813d40330Schristos 6913d40330Schristos=cut 70