After the handshake, the
session
object's recv() and
send() methods may be used to securely exchange
raw data with the peer.
bye() performs an orderly shutdown of the
TLS, after which the underlying network connection
can be closed. The network connection can, of course, be closed without
formally invoking
bye(), however a formal TLS
shutdown process serves a purpose. An unexpected connection
teardown may be interpreted as an attack on the TLS
session.
The session
object also implements the file descriptor
transport interface, so
pubread() and
pubwrite() may be used instead of
recv() and
send(). If a handshake was not previously completed,
the first call to
recv() and
send() transparently calls
handshake() first, before attempting to read or
write. If the underlying file descriptor is non-blocking and the handshake
is incomplete due to pending I/O, its status gets returned, and the
next call to
recv() and
send() invokes handshake()
again.
pubread() and
pubwrite() will also invoke
handshake() if one is needed; however the
file descriptor must be a blocking file descriptor. In a non-blocking
context, the semantics of bi-directional non-blocking I/O required by
handshake cannot be
implemented by
pubread() and
pubwrite(), so an exception gets thrown if
that situation.
The file descriptor transport interface's
getiostream() may be used in place of
send() and recv() also,
but only if the underlying file descriptor blocks:
x::iostream ios(sess->getiostream()); (*ios) << "GET / HTTP/1.0\r\n" << std::flush;
Alternatively, a file descriptor timeout may be initialized on top of a non-blocking file descriptor, and the TLS session object attached to the timeout object. This implements a timeout on the transport level. The TLS session object will propagate the timeout exception, when one gets thrown by the timeout object, passed along to the TLS library as an I/O error, and once the error code gets propagated back up to this library, it gets detected and rethrown.
See the session object class reference for more information on other session object methods. Note that most of them are allowed only before a handshake occurs.
Several x::gnutls::session methods are available that retrieve miscellaneous metadata, such as lists of ciphers, compression methods, and other algorithms that are implemented in the underlying GnuTLS library.