Add new methods DTLS_*_method() which support both DTLS 1.0 and DTLS 1.2 and
pick the highest version the peer supports during negotiation.

As with SSL/TLS options can change this behaviour specifically
SSL_OP_NO_DTLSv1 and SSL_OP_NO_DTLSv1_2.

Port TLS 1.2 GCM code to DTLS. Enable use of TLS 1.2 only ciphers when in
DTLS 1.2 mode too.

Add correct flags for DTLS 1.2, update s_server and s_client to handle
DTLS 1.2 methods.

Currently no support for version negotiation: i.e. if client/server selects
DTLS 1.2 it is that or nothing.

Revise DTLS code. There was a *lot* of code duplication in the
DTLS code that generates records. This makes it harder to maintain and
sometimes a TLS update is omitted by accident from the DTLS code.

Specifically almost all of the record generation functions have code like
this:

some_pointer = buffer + HANDSHAKE_HEADER_LENGTH;
... Record creation stuff ...
set_handshake_header(ssl, SSL_MT_SOMETHING, message_len);

...

write_handshake_message(ssl);

Where the "Record creation stuff" is identical between SSL/TLS and DTLS or
in some cases has very minor differences.

By adding a few fields to SSL3_ENC to include the header length, some flags
and function pointers for handshake header setting and handshake writing the
code can cope with both cases.

Note: although this passes "make test" and some simple DTLS tests there may
be some minor differences in the DTLS code that have to be accounted for.

Submitted by: Pierre Delaage

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>

Fix DTLS timeout handling.

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>

Reduce MTU after failed transmissions.

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Reviewed by: steve

Support for TLS/DTLS heartbeats.

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Reviewed by: steve

Add SCTP support for DTLS (RFC 6083).

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Reviewed by: steve

Fix DTLS bug which prevents manual MTU setting

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Reviewed by: steve

Correctly handle errors in DTLSv1_handle_timeout()

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Reviewed by: steve

Fully implement SSL_clear for DTLS.

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Reviewed by: steve

Fix DTLS Retransmission Buffer Bug

Include proper header files for time functions.
Submitted by Arpadffy Zoltan <Zoltan.Arpadffy@scientificgames.se>

Submitted By: Robin Seggelmann <seggelmann@fh-muenster.de>

Fixes for DTLS timeout bug

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>

Add extension support to DTLS code mainly using existing implementation for
TLS.

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Approved by: steve@openssl.org

Add Renegotiation extension to DTLS, fix DTLS ClientHello processing bug.

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Approved by: steve@openssl.org

DTLS listen support.

Make error name discrepancies a fatal error.
Fix error codes.
make update

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>
Approved by: steve@openssl.org

DTLS timeout handling fix.

for locking code. The CRYPTO_LOCK_SSL_METHOD lock is now no longer used.

have a uniform representation for those over all architectures, so a
little bit of hackery is needed.

Contributed by nagendra modadugu <nagendra@cs.stanford.edu>