State on s3 gets freed in both ssl3_clear and ssl3_free. Considate to just
ssl3_free. This replaces the (SSL,ssl,ssl3)_clear calls in (SSL,ssl,ssl3)_new
with the state that was initialized. This results in a little code duplication
between SSL_new and SSL_clear because state is on the wrong object. I've just
left TODOs for now; some of it will need disentangling.

We're far from it, but going forward, separate state between s and s->s3 as:

- s contains configuration state, DTLS or TLS. It is initialized from SSL_CTX,
  configurable directly afterwards, and preserved across SSL_clear calls.
  (Including when it's implicitly set as part of a handshake callback.)

- Connection state hangs off s->s3 (TLS) and s->d1 (DTLS). It is reset across
  SSL_clear. This should happen naturally out of a ssl_free/ssl_new pair.

The goal is to avoid needing separate initialize and reset code for anything;
the point any particular state is reset is the point its owning context is
destroyed and recreated.

Change-Id: I5d779010778109f8c339c07433a0777feaf94d1f
Reviewed-on: https://boringssl-review.googlesource.com/2822
Reviewed-by: Adam Langley <agl@google.com>

This makes SSLv23_method go through DTLS_ANY_VERSION's version negotiation
logic. This allows us to get rid of duplicate ClientHello logic. For
compatibility, SSL_METHOD is now split into SSL_PROTOCOL_METHOD and a version.
The legacy version-locked methods set min_version and max_version based this
version field to emulate the original semantics.

As a bonus, we can now handle fragmented ClientHello versions now.

Because SSLv23_method is a silly name, deprecate that too and introduce
TLS_method.

Change-Id: I8b3df2b427ae34c44ecf972f466ad64dc3dbb171

SSL3_ENC_METHOD will remain version-specific while SSL_METHOD will become
protocol-specific. This finally removes all the version-specific portions of
SSL_METHOD but the version tag itself.

(SSL3_ENC_METHOD's version-specific bits themselves can probably be handled by
tracking a canonicalized protocol version. It would simplify version
comparisons anyway. The one catch is SSLv3 has a very different table. But
that's a cleanup for future. Then again, perhaps a version-specific method
table swap somewhere will be useful later for TLS 1.3.)

Much of this commit was generated with sed invocation:
    s/method->ssl3_enc/enc_method/g

Change-Id: I2b192507876aadd4f9310240687e562e56e6c0b1
Reviewed-on: https://boringssl-review.googlesource.com/2581
Reviewed-by: Adam Langley <agl@google.com>

They're always known now. Also fix the SSLv23_{client,server}_method
definitions still had their own macro invocations.

Change-Id: Ia13f29a27f2331d25a4051e83f2d5abc62fab981
Reviewed-on: https://boringssl-review.googlesource.com/2562
Reviewed-by: Adam Langley <agl@google.com>

Supporting both schemes seems pointless. Now that s->server and s->state are
set appropriately late and get_ssl_method is gone, the only difference is that
the client/server ones have non-functional ssl_accept or ssl_connect hooks. We
can't lose the generic ones, so let's unify on that.

Note: this means a static linker will no longer drop the client or server
handshake code if unused by a consumer linking statically. However, Chromium
needs the server half anyway for DTLS and WebRTC, so that's probably a lost
cause. Android also exposes server APIs.

Change-Id: I290f5fb4ed558f59fadb5d1f84e9d9c405004c23
Reviewed-on: https://boringssl-review.googlesource.com/2440
Reviewed-by: Adam Langley <agl@google.com>

This is a bit of cleanup that probably should have been done at the same time
as 30ddb434bf.

For now, version negotiation is implemented with a method swap. It also
performs this swap on SSL_set_session, but this was neutered in
30ddb434bf. Rather than hackishly neuter it,
remove it outright.  In addition, remove SSL_set_ssl_method. Now all method
swaps are internal: SSLv23_method switch to a version-specific method and
SSL_clear undoing it.

Note that this does change behavior: if an SSL* is created with one
version-specific method and we SSL_set_session to a session from a /different/
version, we would switch to the /other/ version-specific method. This is
extremely confusing, so it's unlikely anyone was actually expecting it.
Version-specific methods in general don't work well.

Change-Id: I72a5c1f321ca9aeb1b52ebe0317072950ba25092
Reviewed-on: https://boringssl-review.googlesource.com/2390
Reviewed-by: Adam Langley <agl@google.com>

Remove one more difference to worry about switching between TLS and SSLv3
method tables.

Although this does change the get_ssl_method hook for the version-specific
tables (before TLS and SSLv3 would be somewhat partitioned), it does not appear
to do anything. get_ssl_method is only ever called in SSL_set_session for
client session resumption. Either you're using the version-specific method
tables and don't know about other versions anyway or you're using SSLv23 and
don't partition TLS vs SSL3 anyway.

BUG=chromium:403378

Change-Id: I8cbdf02847653a01b04dbbcaf61fcb3fa4753a99
Reviewed-on: https://boringssl-review.googlesource.com/1842
Reviewed-by: Adam Langley <agl@google.com>

The TLS-specific hooks have been removed. We aim to no longer perform version
negotiation as a pre-processing step, so ensure the only differences to worry
about are the version, get_method hook, and the enc_data.

BUG=chromium:403378

Change-Id: I628ec6f4c50ceed01d7af8f4110b6dc95cfbe023
Reviewed-on: https://boringssl-review.googlesource.com/1841
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)