1=pod 2 3=head1 NAME 4 5SSL_pending, SSL_has_pending - check for readable bytes buffered in an 6SSL object 7 8=head1 SYNOPSIS 9 10 #include <openssl/ssl.h> 11 12 int SSL_pending(const SSL *ssl); 13 int SSL_has_pending(const SSL *s); 14 15=head1 DESCRIPTION 16 17Data is received in whole blocks known as records from the peer. A whole record 18is processed (e.g. decrypted) in one go and is buffered by OpenSSL until it is 19read by the application via a call to L<SSL_read_ex(3)> or L<SSL_read(3)>. 20 21SSL_pending() returns the number of bytes which have been processed, buffered 22and are available inside B<ssl> for immediate read. 23 24If the B<SSL> object's I<read_ahead> flag is set (see 25L<SSL_CTX_set_read_ahead(3)>), additional protocol bytes (beyond the current 26record) may have been read containing more TLS/SSL records. This also applies to 27DTLS and pipelining (see L<SSL_CTX_set_split_send_fragment(3)>). These 28additional bytes will be buffered by OpenSSL but will remain unprocessed until 29they are needed. As these bytes are still in an unprocessed state SSL_pending() 30will ignore them. Therefore, it is possible for no more bytes to be readable from 31the underlying BIO (because OpenSSL has already read them) and for SSL_pending() 32to return 0, even though readable application data bytes are available (because 33the data is in unprocessed buffered records). 34 35SSL_has_pending() returns 1 if B<s> has buffered data (whether processed or 36unprocessed) and 0 otherwise. Note that it is possible for SSL_has_pending() to 37return 1, and then a subsequent call to SSL_read_ex() or SSL_read() to return no 38data because the unprocessed buffered data when processed yielded no application 39data (for example this can happen during renegotiation). It is also possible in 40this scenario for SSL_has_pending() to continue to return 1 even after an 41SSL_read_ex() or SSL_read() call because the buffered and unprocessed data is 42not yet processable (e.g. because OpenSSL has only received a partial record so 43far). 44 45=head1 RETURN VALUES 46 47SSL_pending() returns the number of buffered and processed application data 48bytes that are pending and are available for immediate read. SSL_has_pending() 49returns 1 if there is buffered record data in the SSL object and 0 otherwise. 50 51=head1 SEE ALSO 52 53L<SSL_read_ex(3)>, L<SSL_read(3)>, L<SSL_CTX_set_read_ahead(3)>, 54L<SSL_CTX_set_split_send_fragment(3)>, L<ssl(7)> 55 56=head1 HISTORY 57 58The SSL_has_pending() function was added in OpenSSL 1.1.0. 59 60=head1 COPYRIGHT 61 62Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved. 63 64Licensed under the OpenSSL license (the "License"). You may not use 65this file except in compliance with the License. You can obtain a copy 66in the file LICENSE in the source distribution or at 67L<https://www.openssl.org/source/license.html>. 68 69=cut 70