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.

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.

right response is stapled. Also change SSL_get_certificate() so it
returns the certificate actually sent.  See
http://rt.openssl.org/Ticket/Display.html?id=2836.

that are disabled for this session (as opposed to always disabled by
configuration).

is required by client or server. An application can decide which
certificate chain to present based on arbitrary criteria: for example
supported signature algorithms. Add very simple example to s_server.
This fixes many of the problems and restrictions of the existing client
certificate callback: for example you can now clear existing certificates
and specify the whole chain.

TLS v1.2. These are sent as an extension for clients and during a certificate
request for servers.

TODO: add support for shared signature algorithms, respect shared algorithms
when deciding which ciphersuites and certificates to permit.

Reviewed by: steve
Improved localisation of TLS extension handling and code tidy.

PR: 2538

Localize client hello extension parsing in t1_lib.c

enabled instead of requiring an application to hard code a (possibly
inappropriate) parameter set and delve into EC internals we just
automatically use the preferred curve.

before rejecting multiple SGC restarts.

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.

The cipher definitions of these ciphersuites have been around since SSLeay
but were always disabled. Now OpenSSL supports DH certificates they can be
finally enabled.

Various additional changes were needed to make them work properly: many
unused fixed DH sections of code were untested.

Submitted by: steve

Update maximum message size for certifiate verify messages to support
4096 bit RSA keys again as TLS v1.2 messages is two bytes longer.

Reviewed by: steve

Fix memory leaks.

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

Support for TLS/DTLS heartbeats.

Submitted by: Peter Sylvester <peter.sylvester@edelweb.fr>
Reviewed by: steve

- remove some unncessary SSL_err and permit
an srp user callback to allow a worker to obtain
a user verifier.

- cleanup and comments in s_server and demonstration
for asynchronous srp user lookup

Submitted by: Peter Sylvester <peter.sylvester@edelweb.fr>
Reviewed by: steve

Make SRP conformant to rfc 5054.

Changes are:

- removal of the addition state after client hello
- removal of all pre-rfc srp alert ids
- sending a fatal alert when there is no srp extension but when the
server wants SRP
- removal of unnecessary code in the client.

Submitted by: Adam Langley

Submitted by: Alexei Khlebnikov <alexei.khlebnikov@opera.com>
Reviewed by: steve

OOM checking. Leak in OOM fix. Fall-through comment. Duplicate code
elimination.