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 DTLS record header parsing, different client hello format and add
HelloVerifyRequest message type.

Add code to d1_pkt.c to send message headers to the message callback.

Revert is appropriate because binary compatibility is not an issue
in 1.1.

Kludge alert. This is arranged by passing padding length in unused
bits of SSL3_RECORD->type, so that orig_len can be reconstructed.
(cherry picked from commit 8bfd4c659f180a6ce34f21c0e62956b362067fba)

This change updates the DTLS code to match the constant-time CBC
behaviour in the TLS.
(cherry picked from commit 9f27de170d1b7bef3d46d41382dc4dafde8b3900)

The previous CBC patch was bugged in that there was a path through enc()
in s3_pkt.c/d1_pkt.c which didn't set orig_len. orig_len would be left
at the previous value which could suggest that the packet was a
sufficient length when it wasn't.
(cherry picked from commit 6cb19b7681f600b2f165e4adc57547b097b475fd)

This change adds CRYPTO_memcmp, which compares two vectors of bytes in
an amount of time that's independent of their contents. It also changes
several MAC compares in the code to use this over the standard memcmp,
which may leak information about the size of a matching prefix.
(cherry picked from commit 2ee798880a246d648ecddadc5b91367bee4a5d98)

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

Fix DTLS timeout handling.

Thanks to Antonio Martin, Enterprise Secure Access Research and
Development, Cisco Systems, Inc. for discovering this bug and
preparing a fix. (CVE-2012-0050)

Reviewed by: steve

Fix for DTLS plaintext recovery attack discovered by Nadhem Alfardan and
Kenny Paterson.

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 buffering and decryption bug.

alert.

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

Support for abbreviated handshakes when renegotiating.

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

Don't drop DTLS connection if mac or decryption failed.

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

Fix DTLS buffer record MAC failure bug.

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

Fixes for DTLS replay bug.

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

Fixes for DTLS buffering bug.

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

DTLS listen bug fix,

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

Do not use multiple DTLS records for a single user message

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

DTLS timeout handling fix.

Fix from 0.9.8-stable.

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

DTLS record header bugfix.

test for them!

(Coverity ID 140).