In NPN and ALPN, the protocol is renegotiated upon resumption. Test that
resumption picks up changes to the extension.
Reviewed-by: NRich Salz <rsalz@openssl.org>

Move custom server and client options from the test dictionary to an
"extra" section of each server/client. Rename test expectations to say
"Expected".

This is a big but straightforward change. Primarily, this allows us to
specify multiple server and client contexts without redefining the
custom options for each of them. For example, instead of
"ServerNPNProtocols", "Server2NPNProtocols", "ResumeServerNPNProtocols",
we now have, "NPNProtocols".

This simplifies writing resumption and SNI tests. The first application
will be resumption tests for NPN and ALPN.

Regrouping the options also makes it clearer which options apply to the
server, which apply to the client, which configure the test, and which
are test expectations.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

Don't emit duplicate server/client sections when they are
identical. Instead, just point to the same section.
Reviewed-by: NRich Salz <rsalz@openssl.org>

Add tests for resuming with a different client version.

This happens in reality when clients persist sessions on disk through
upgrades.
Reviewed-by: NRich Salz <rsalz@openssl.org>

Systematically test every server-side version downgrade or upgrade.

Client version upgrade or downgrade could be tested analogously but will
be done in a later change.
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>

The SNI tests introduced a redundant "server2" section into every test
configuration. Copy this automatically from "server" unless testing SNI,
to reduce noise in the generated confs.

Also remove duplicate SSL_TEST_CTX_create (merge conflict error).
Reviewed-by: NRich Salz <rsalz@openssl.org>

When session tickets are used, it's possible that SNI might swtich the
SSL_CTX on an SSL. Normally, this is not a problem, because the
initial_ctx/session_ctx are used for all session ticket/id processes.

However, when the SNI callback occurs, it's possible that the callback
may update the options in the SSL from the SSL_CTX, and this could
cause SSL_OP_NO_TICKET to be set. If this occurs, then two bad things
can happen:

1. The session ticket TLSEXT may not be written when the ticket expected
flag is set. The state machine transistions to writing the ticket, and
the client responds with an error as its not expecting a ticket.
2. When creating the session ticket, if the ticket key cb returns 0
the crypto/hmac contexts are not initialized, and the code crashes when
trying to encrypt the session ticket.

To fix 1, if the ticket TLSEXT is not written out, clear the expected
ticket flag.
To fix 2, consider a return of 0 from the ticket key cb a recoverable
error, and write a 0 length ticket and continue. The client-side code
can explicitly handle this case.

Fix these two cases, and add unit test code to validate ticket behavior.
Reviewed-by: NEmilia Käsper <emilia@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1098)

Currently, SSL tests are configured via command-line switches to
ssltest.c. This results in a lot of duplication between ssltest.c and
apps, and a complex setup. ssltest.c is also simply old and needs
maintenance.

Instead, we already have a way to configure SSL servers and clients, so
we leverage that. SSL tests can now be configured from a configuration
file. Test servers and clients are configured using the standard
ssl_conf module. Additional test settings are configured via a test
configuration.

Moreover, since the CONF language involves unnecessary boilerplate, the
test conf itself is generated from a shorter Perl syntax.

The generated testcase files are checked in to the repo to make
it easier to verify that the intended test cases are in fact run; and to
simplify debugging failures.

To demonstrate the approach, min/max protocol tests are converted to the
new format. This change also fixes MinProtocol and MaxProtocol
handling. It was previously requested that an SSL_CTX have both the
server and client flags set for these commands; this clearly can never work.

Guide to this PR:
 - test/ssl_test.c - test framework
 - test/ssl_test_ctx.* - test configuration structure
 - test/handshake_helper.* - new SSL test handshaking code
 - test/ssl-tests/ - test configurations
 - test/generate_ssl_tests.pl - script for generating CONF-style test
   configurations from perl inputs
Reviewed-by: NRichard Levitte <levitte@openssl.org>