This drops in a copy of a subset of golang.org/x/crypto/poly1305 to implement
Poly1305. Hopefully this will keep them from regression as we rework the record
layer.

Change-Id: Ic1e0d941a0a9e5ec260151ced8acdf9215c4b887
Reviewed-on: https://boringssl-review.googlesource.com/4257
Reviewed-by: Adam Langley <agl@google.com>

Notably, drop all special cases around receiving a message in order and
receiving a full message. It makes things more complicated and was the source
of bugs (the MixCompleteMessageWithFragments tests added in this CL did not
pass before). Instead, every message goes through an hm_fragment, and
dtls1_get_message always checks buffered_messages to see if the next is
complete.

The downside is that we pay one more copy of the message data in the common
case. This is only during connection setup, so I think it's worth the
simplicity. (If we want to optimize later, we could either tighten
ssl3_get_message's interface to allow the handshake data being in the
hm_fragment's backing store rather than s->init_buf or swap out s->init_buf
with the hm_fragment's backing store when a mesasge completes.

This CL does not address ssl_read_bytes being an inappropriate API for DTLS.
Future work will revise the handshake/transport boundary to align better with
DTLS's needs. Also other problems that I've left as TODOs.

Change-Id: Ib4570d45634b5181ecf192894d735e8699b1c86b
Reviewed-on: https://boringssl-review.googlesource.com/3764
Reviewed-by: Adam Langley <agl@google.com>

We actually don't really care about this special-case since we only test client
full handshakes where the runner sends the second Finished not the shim
(otherwise the overlap logic and retransmitting on every fragment would
probably break us), but it should probably live next to the fragmentation
logic.

Change-Id: I54097d84ad8294bc6c42a84d6f22f496e63eb2a8
Reviewed-on: https://boringssl-review.googlesource.com/3763
Reviewed-by: Adam Langley <agl@google.com>

SSL_AEAD_CTX ownership is currently too confusing. Instead, rely on the lack of
renego, so the previous epoch always uses the NULL cipher. (Were we to support
DTLS renego, we could keep track of s->d1->last_aead_write_ctx like
s->d1->last_write_sequence, but it isn't worth it.)

Buffered messages also tracked an old s->session, but this is unnecessary. The
s->session NULL check in tls1_enc dates to the OpenSSL initial commit and is
redundant with the aead NULL check.

Change-Id: I9a510468d95934c65bca4979094551c7536980ae
Reviewed-on: https://boringssl-review.googlesource.com/3234
Reviewed-by: Adam Langley <agl@google.com>

For now, only test reorderings when we always or never fragment messages.
There's a third untested case: when full messages and fragments are mixed. That
will be tested later after making it actually work.

Change-Id: Ic4efb3f5e87b1319baf2d4af31eafa40f6a50fa6
Reviewed-on: https://boringssl-review.googlesource.com/3216
Reviewed-by: Adam Langley <agl@google.com>

No behavior change. This is in preparation for buffering a flight of handshake
messages to reorder vigorously on flush.

Change-Id: Ic348829b340bf58d28f332027646559cb11046ac
Reviewed-on: https://boringssl-review.googlesource.com/3215
Reviewed-by: Adam Langley <agl@google.com>

This reverts commit c67a3ae6ba. With a
deterministic clock, we can now go back to being strict about retransmits. Our
tests will now require that the shim only retransmit when we expect it to.

Change-Id: Iab1deb9665dcd294790c8253d920089e83a9140c
Reviewed-on: https://boringssl-review.googlesource.com/3211
Reviewed-by: Adam Langley <agl@google.com>

BoringSSL currently retransmits non-deterministically on an internal timer
(rather than one supplied externally), so the tests currently fail flakily
depending on timing. Valgrind is a common source for this. We still assume an
in-order and reliable channel, but drop retransmits silently:

- Handshake messages may arrive with old sequence numbers.

- Retransmitted CCS records arrive from the previous epoch.

- We may receive a retransmitted Finished after we believe the handshake has
  completed. (Aside: even in a real implementation, only Finished is possible
  here. Even with out-of-order delivery, retransmitted or reordered messages
  earlier in the handshake come in under a different epoch.)

Note that because DTLS renego and a Finished retransmit are ambiguous at the
record layer[*], this precludes us writing tests for DTLS renego. But DTLS
renego should get removed anyway. As BoringSSL currently implements renego,
this ambiguity is also a source of complexity in the real implementation. (See
the SSL3_MT_FINISHED check in dtls1_read_bytes.)

[*] As a further fun aside, it's also complex if dispatching renego vs Finished
after handshake message reassembly. The spec doesn't directly say the sequence
number is reset across renegos, but it says "The first message each side
transmits in /each/ handshake always has message_seq = 0". This means that such
an implementation needs the handshake message reassembly logic be aware that a
Finished fragment with high sequence number is NOT an out-of-order fragment for
the next handshake.

Change-Id: I35d13560f82bcb5eeda62f4de1571d28c818cc36
Reviewed-on: https://boringssl-review.googlesource.com/2770
Reviewed-by: Adam Langley <agl@google.com>

The minimum MTU (not consistently enforced) is just under 256, so it's
difficult to test everything, but this is a basic test. (E.g., without renego,
the only handshake message with encryption is Finished which fits in the MTU.)
It tests the server side because the Certificate message is large enough to
require fragmentation.

Change-Id: Ida11f1057cebae2b800ad13696f98bb3a7fbbc5e
Reviewed-on: https://boringssl-review.googlesource.com/2824
Reviewed-by: Adam Langley <agl@google.com>

The record-layer version of the ServerHello should match the final version. The
record-layer version of the ClientHello should be the advertised version, but
clamped at TLS 1.0. This is to ensure future rewrites do not regress this.

Change-Id: I96f1f0674944997ff38b562453a322ce61652635
Reviewed-on: https://boringssl-review.googlesource.com/2540
Reviewed-by: Adam Langley <agl@google.com>

At the record layer, DTLS maintains a window of seen sequence numbers to detect
replays. Add tests to cover that case. Test both repeated sequence numbers
within the window and sequence numbers past the window's left edge. Also test
receiving sequence numbers far past the window's right edge.

Change-Id: If6a7a24869db37fdd8fb3c4b3521b730e31f8f86
Reviewed-on: https://boringssl-review.googlesource.com/2221
Reviewed-by: Adam Langley <agl@google.com>

Run against openssl s_client and openssl s_server. This seems to work for a
start, although it may need to become cleverer to stress more of BoringSSL's
implementation for test purposes.

In particular, it assumes a reliable, in-order channel. And it requires that
the peer send handshake fragments in order. Retransmit and whatnot are not
implemented. The peer under test will be expected to handle a lossy channel,
but all loss in the channel will be controlled. MAC errors, etc., are fatal.

Change-Id: I329233cfb0994938fd012667ddf7c6a791ac7164
Reviewed-on: https://boringssl-review.googlesource.com/1390
Reviewed-by: Adam Langley <agl@google.com>