that bad encryptions are treated like random session keys in constant
time.

Contributed by Trevor Perrin.

Check for Suite B support using method flags instead of version numbers:
anything supporting TLS 1.2 cipher suites will also support Suite B.

Return an error if an attempt to use DTLS 1.0 is made in Suite B mode.

If we successfully match a cookie don't set return value to 2 as this
results in other error conditions returning 2 as well.

Instead set return value to -2 which can be checked later if everything
else is OK.

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.

Since s->method does not reflect the final client version when a client
hello is sent for SSLv23_client_method it can't be relied on to indicate
if TLS 1.2 ciphers should be used. So use the client version instead.

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

The relaxed signing requirements for fixed DH certificates apply to DTLS 1.2
too.

Add DTLS1.2 support for cached records when computing handshake macs
instead of the MD5+SHA1 case for DTLS < 1.2 (this is a port of the
equivalent TLS 1.2 code to DTLS).

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.

Since this is always called from DTLS code it is safe to assume the header
length should be the DTLS value. This avoids the need to check the version
number and should work with any version of DTLS (not just 1.0).

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

Some TLS extensions were disabled for DTLS. Possibly because they caused
problems with the old duplicated code. Enable them again.

The only standard compression method is stateful and is incompatible with
DTLS.

Use the enc_flags field to determine whether we should use explicit IV,
signature algorithms or SHA256 default PRF instead of hard coding which
versions support each requirement.

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.

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.

Not sure why I am getting these now and not before.

The version check for DTLS1_VERSION was redundant as
DTLS1_VERSION > TLS1_1_VERSION, however we do need to
check for DTLS1_BAD_VER for compatibility.

PR:2984

(cherry picked from commit cbf9b4aed3e209fe8a39e1d6f55aaf46d1369dc4)

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

MD5 should use little endian order. Fortunately the only ciphersuite
affected is EXP-RC2-CBC-MD5 (TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5) which
is a rarely used export grade ciphersuite.
(cherry picked from commit f306b87d766e6ecf30824635c7c395b67cff9dbc)

Address CBC decrypt timing issues and reenable the AESNI+SHA1 stitch.
(cherry picked from commit 125093b59f3c2a2d33785b5563d929d0472f1721)

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)

(cherry picked from commit 04e45b52ee3be81121359cc1198fd01e38096e9f)

(cherry picked from commit d5371324d978e4096bf99b9d0fe71b2cb65d9dc8)

RISCs are picky and alignment granted by compiler for md_state can be
insufficient for SHA512.
(cherry picked from commit 36260233e7e3396feed884d3f501283e0453c04f)

Break dependency on uint64_t. It's possible to declare bits as
unsigned int, because TLS packets are limited in size and 32-bit
value can't overflow.
(cherry picked from commit cab13fc8473856a43556d41d8dac5605f4ba1f91)

(cherry picked from commit 34ab3c8c711ff79c2b768f0b17e4b2a78fd1df5d)