obtain number of readable bytes
buffered in an SSL object
Data is received in whole blocks known as records from the peer. A whole record is processed, for example decrypted, in one go and is buffered until it is read by the application via a call to SSL_read(3).
returns the number of bytes of application data which are available for
takes into account only bytes from the TLS/SSL record that is currently
being processed (if any).
SSL_pending() returns the number of
buffered and processed application data bytes that are pending and are
available for immediate read.
SSL_pending() appeared in SSLeay 0.4 or
earlier and has been available since OpenBSD
Up to OpenSSL 0.9.6,
SSL_pending() did not
check if the record type of pending data is application data.