SSL_pending - obtain number of readable bytes buffered in an SSL object
int SSL_pending(const SSL *ssl);
returns the number of bytes which are available inside
for immediate read.
Data are received in blocks from the peer. Therefore data can be buffered inside
and are ready for immediate retrieval with SSL_read(3)
The number of bytes pending is returned.
takes into account only bytes from the TLS/SSL record that
is currently being processed (if any). If the SSL
flag is set, additional protocol bytes may have been read
containing more TLS/SSL records; these are ignored by SSL_pending()
Up to OpenSSL 0.9.6, SSL_pending()
does not check if the record type of
pending data is application data.