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.

Extend DTLS method creation macros to support version numbers and encryption
methods. Update existing code.

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: John Fitzgibbon <john_fitzgibbon@yahoo.com>

Time is always encoded as 4 bytes, not sizeof(Time).

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

Fix possible DTLS timer deadlock.

certificate chain instead of an X509 structure.

This makes it easier to enhance code in future and the chain
output functions have access to the CERT_PKEY structure being
used.

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 for ECC keys and DTLS.

Submitted by: Adam Langley

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

Fix DTLS sequence number bug

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

Fix DTLS HelloVerifyRequest Timer bug

signature algorithms extension and correct signature format for
server key exchange.

All ciphersuites should now work on the server but no client support and
no client certificate support yet.

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

Don't change state when answering DTLS ClientHello.

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

Support for abbreviated handshakes when renegotiating.

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

Make session tickets work with DTLS.

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

Typo in PR#1949 bug, oops!

Submitted by: steve@openssl.org

More robust fix and workaround for PR#1949. Don't try to work out if there
is any write pending data as this can be unreliable: always flush.

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

Better fix for PR#2144

Submitted by: steve@openssl.org

Fix DTLS connection so new_session is reset if we read second client hello:
new_session is used to detect renegotiation.

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.

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

Fix DTLS cookie management bugs.

Submitted by: Nagendra Modadugu

OPENSSL_NO_DEPRECATED, etc. Steve, please double-check the CMS stuff...

Submitted by: Alex Lam

Submitted by: Victor B. Wagner <vitus@cryptocom.ru>