Alas, we will need a version fallback for TLS 1.3 again.

This deprecates SSL_MODE_SEND_FALLBACK_SCSV. Rather than supplying a
boolean, have BoringSSL be aware of the real maximum version so we can
change the TLS 1.3 anti-downgrade logic to kick in, even when
max_version is set to 1.2.

The fallback version replaces the maximum version when it is set for
almost all purposes, except for downgrade protection purposes.

BUG=chromium:630165

Change-Id: I4c841dcbc6e55a282b223dfe169ac89c83c8a01f
Reviewed-on: https://boringssl-review.googlesource.com/8882
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

This adds three more formats to the SSLKEYLOGFILE format to support TLS
1.3:

    EARLY_TRAFFIC_SECRET <client_random> <early_traffic_secret>
    HANDSHAKE_TRAFFIC_SECRET <client_random> <handshake_traffic_secret>
    TRAFFIC_SECRET_0 <client_random> <traffic_secret_0>

(We don't implement 0-RTT yet, so only the second two are implemented.)

Motivations:

1. If emitted the non-traffic secrets (early, handshake, and master) or
   the IKMs, Wireshark needs to maintain a handshake hash. I don't
   believe they need to do this today.

2. We don't store more than one non-traffic secret at a time and don't
   keep traffic secrets for longer than needed. That suggests three
   separate lines logged at different times rather than one line.

3. If 0-RTT isn't used, we probably won't even compute the early traffic
   secret, so that further suggests three different lines.

4. If the handshake didn't get far enough to complete, we won't have an
   TRAFFIC_SECRET_0 to log at all. That seems like exactly when
   Wireshark would be handy, which means we want to log secrets as they
   are computed.

MT from NSS has ACK'd over email that this format would be acceptable
for them, so let's go with it.

Change-Id: I4d685a1355dff4d4bd200310029d502bb6c511f9
Reviewed-on: https://boringssl-review.googlesource.com/8841
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

This adds the machinery for doing TLS 1.3 1RTT.

Change-Id: I736921ffe9dc6f6e64a08a836df6bb166d20f504
Reviewed-on: https://boringssl-review.googlesource.com/8720
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

This makes custom private keys and EVP_PKEYs symmetric again. There is
no longer a requirement that the caller pre-filter the configured
signing prefs.

Also switch EVP_PKEY_RSA to NID_rsaEncryption. These are identical, but
if some key types are to be NIDs, we should make them all NIDs.

Change-Id: I82ea41c27a3c57f4c4401ffe1ccad406783e4c64
Reviewed-on: https://boringssl-review.googlesource.com/8785
Reviewed-by: David Benjamin <davidben@google.com>

Upstream have added |EVP_PKEY_up_ref|, but their version returns an int.
Having this function with a different signature like that is dangerous
so this change aligns BoringSSL with upstream. Users of this function in
Chromium and internally should already have been updated.

Change-Id: I0a7aeaf1a1ca3b0f0c635e2ee3826aa100b18157
Reviewed-on: https://boringssl-review.googlesource.com/8736
Reviewed-by: David Benjamin <davidben@google.com>

Since they include an ECDHE exchange in them, they are equally-well
suited to False Start.

Change-Id: I75d31493a614a78ccbf337574c359271831d654d
Reviewed-on: https://boringssl-review.googlesource.com/8732
Reviewed-by: David Benjamin <davidben@google.com>

Chromium no longer uses it.

Change-Id: I50cc55bad4124305686d299032a2e8ed2cb9d0d7
Reviewed-on: https://boringssl-review.googlesource.com/8691
Reviewed-by: David Benjamin <davidben@google.com>

Upstream added this in a18a31e49d266. The various *_up_ref functions
return a variety of types, but this one returns int because upstream
appears to be trying to unify around that. (See upstream's c5ebfcab713.)

Change-Id: I7e1cfe78c3a32f5a85b1b3c14428bd91548aba6d
Reviewed-on: https://boringssl-review.googlesource.com/8581
Reviewed-by: Adam Langley <alangley@gmail.com>

This replaces the old key_exchange_info APIs and does not require the
caller be aware of the mess around SSL_SESSION management. They
currently have the same bugs around renegotiation as before, but later
work to fix up SSL_SESSION tracking will fix their internals.

For consistency with the existing functions, I've kept the public API at
'curve' rather than 'group' for now. I think it's probably better to
have only one name with a single explanation in the section header
rather than half and half. (I also wouldn't be surprised if the IETF
ends up renaming 'group' again to 'key exchange' at some point.  We'll
see what happens.)

Change-Id: I8e90a503bc4045d12f30835c86de64ef9f2d07c8
Reviewed-on: https://boringssl-review.googlesource.com/8565
Reviewed-by: Adam Langley <agl@google.com>

OpenSSL's SSL_OP_NO_* flags allow discontinuous version ranges. This is a
nuisance for two reasons. First it makes it unnecessarily difficult to answer
"are any versions below TLS 1.3 enabled?". Second the protocol does not allow
discontinuous version ranges on the client anyway. OpenSSL instead picks the
first continous range of enabled versions on the client, but not the server.

This is bizarrely inconsistent. It also doesn't quite do this as the
ClientHello sending logic does this, but not the ServerHello processing logic.
So we actually break some invariants slightly. The logic is also cumbersome in
DTLS which kindly inverts the comparison logic.

First, switch min_version/max_version's storage to normalized versions. Next
replace all the ad-hoc version-related functions with a single
ssl_get_version_range function. Client and server now consistently pick a
contiguous range of versions. Note this is a slight behavior change for
servers. Version-range-sensitive logic is rewritten to use this new function.

BUG=66

Change-Id: Iad0d64f2b7a917603fc7da54c9fc6656c5fbdb24
Reviewed-on: https://boringssl-review.googlesource.com/8513
Reviewed-by: David Benjamin <davidben@google.com>

As part of the SignatureAlgorithm change in the TLS 1.3 specification,
the existing signature/hash combinations are replaced with a combined
signature algorithm identifier. This change maintains the existing APIs
while fixing the internal representations. The signing code currently
still treats the SignatureAlgorithm as a decomposed value, which will be
fixed as part of a separate CL.

Change-Id: I0cd1660d74ad9bcf55ce5da4449bf2922660be36
Reviewed-on: https://boringssl-review.googlesource.com/8480
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

It doesn't really convey anything useful. Leave ssl_get_message alone for now
since it's called everywhere in the handshake and I'm about to tweak it
further.

Change-Id: I6f3a74c170e818f624be8fbe5cf6b796353406df
Reviewed-on: https://boringssl-review.googlesource.com/8430
Reviewed-by: Adam Langley <agl@google.com>

Saves us some mess if they're never zero. This also fixes a bug in
ssl3_get_max_client_version where it didn't account for all versions being
disabled properly.

Change-Id: I4c95ff57cf8953cb4a528263b252379f252f3e01
Reviewed-on: https://boringssl-review.googlesource.com/8512
Reviewed-by: David Benjamin <davidben@google.com>

That both exist with nearly the same name is unfortunate. This also does away
with cert_req being unnecessarily tri-state.

Change-Id: Id83e13d0249b80700d9258b363d43b15d22898d8
Reviewed-on: https://boringssl-review.googlesource.com/8247
Reviewed-by: Adam Langley <agl@google.com>

SSL_set_bio has some rather complex ownership story because whether rbio/wbio
are both owning depends on whether they are equal. Moreover, whether
SSL_set_bio(ssl, rbio, wbio) frees ssl->rbio depends on whether rbio is the
existing rbio or not. The current logic doesn't even get it right; see tests.

Simplify this. First, rbio and wbio are always owning. All the weird ownership
cases which we're stuck with for compatibility will live in SSL_set_bio. It
will internally BIO_up_ref if necessary and appropriately no-op the left or
right side as needed. It will then call more well-behaved ssl_set_rbio or
ssl_set_wbio functions as necessary.

Change-Id: I6b4b34e23ed01561a8c0aead8bb905363ee413bb
Reviewed-on: https://boringssl-review.googlesource.com/8240
Reviewed-by: Adam Langley <agl@google.com>

This callback is used by BoringSSL tests in order to simulate the time,
so that the tests have repeatable results. This API will allow consumers
of BoringSSL to write the same sort of tests.

Change-Id: I79d72bce5510bbd83c307915cd2cc937579ce948
Reviewed-on: https://boringssl-review.googlesource.com/8200
Reviewed-by: David Benjamin <davidben@google.com>

The separation is purely historical (what happened to use an SSL_ctrl hook), so
put them all in one place. Make a vague attempt to match the order of the
header file, though we're still very far from matching.

Change-Id: Iba003ff4a06684a6be342e438d34bc92cab1cd14
Reviewed-on: https://boringssl-review.googlesource.com/8189
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

Reorder states and functions by where they appear in the handshake. Remove
unnecessary hooks on SSL_PROTOCOL_METHOD.

Change-Id: I78dae9cf70792170abed6f38510ce870707e82ff
Reviewed-on: https://boringssl-review.googlesource.com/8184
Reviewed-by: David Benjamin <davidben@google.com>

This is getting a little repetitive.

Change-Id: Ib0fa8ab10149557c2d728b88648381b9368221d9
Reviewed-on: https://boringssl-review.googlesource.com/8126
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

We've got it in entry points. That should be sufficient. (Do we even need it
there?)

Change-Id: I39b245a08fcde7b57e61b0bfc595c6ff4ce2a07a
Reviewed-on: https://boringssl-review.googlesource.com/8127
Reviewed-by: David Benjamin <davidben@google.com>

Windows SRWLOCK requires you call different functions here. Split
them up in preparation for switching Windows from CRITICAL_SECTION.

BUG=37

Change-Id: I7b5c6a98eab9ae5bb0734b805cfa1ff334918f35
Reviewed-on: https://boringssl-review.googlesource.com/8080
Reviewed-by: Adam Langley <agl@google.com>

This is easier to deploy, and more obvious.  This commit reverts a few
pieces of e25775bc, but keeps most of it.

Change-Id: If8d657a4221c665349c06041bb12fffca1527a2c
Reviewed-on: https://boringssl-review.googlesource.com/8061
Reviewed-by: Adam Langley <agl@google.com>

This reverts commit c7eae5a326. pyOpenSSL
expects to be able to call |SSL_read| after a shutdown and get EOF.

Change-Id: Icc5faa09d644ec29aac99b181dac0db197f283e3
Reviewed-on: https://boringssl-review.googlesource.com/8060
Reviewed-by: Adam Langley <agl@google.com>

Constants representing TLS 1.3 are added to allow for future work to be
flagged on TLS1_3_VERSION. To prevent BoringSSL from negotiating the
non-existent TLS 1.3 version, it is explicitly disabled using
SSL_OP_NO_TLSv1_3.

Change-Id: Ie5258a916f4c19ef21646c4073d5b4a7974d6f3f
Reviewed-on: https://boringssl-review.googlesource.com/8041
Reviewed-by: Adam Langley <agl@google.com>

OpenSSL's bbio logic is kind of crazy. It would be good to eventually do the
buffering in a better way (notably, bbio is fragile, if not outright broken,
for DTLS). In the meantime, this fixes a number of bugs where the existence of
bbio was leaked in the public API and broke things.

- SSL_get_wbio returned the bbio during the handshake. It must always return
  the BIO the consumer configured. In doing so, internal accesses of
  SSL_get_wbio should be switched to ssl->wbio since those want to see bbio.
  For consistency, do the same with rbio.

- The logic in SSL_set_rfd, etc. (which I doubt is quite right since
  SSL_set_bio's lifetime is unclear) would get confused once wbio got wrapped.
  Those want to compare to SSL_get_wbio.

- If SSL_set_bio was called mid-handshake, bbio would get disconnected and lose
  state. It forgets to reattach the bbio afterwards. Unfortunately, Conscrypt
  does this a lot. It just never ended up calling it at a point where the bbio
  would cause problems.

- Make more explicit the invariant that any bbio's which exist are always
  attached. Simplify a few things as part of that.

Change-Id: Ia02d6bdfb9aeb1e3021a8f82dcbd0629f5c7fb8d
Reviewed-on: https://boringssl-review.googlesource.com/8023
Reviewed-by: Kenny Root <kroot@google.com>
Reviewed-by: Adam Langley <agl@google.com>

The 'elliptic_curves' extension is being renamed to 'supported_groups'
in the TLS 1.3 draft, and most of the curve-specific methods are
generalized to groups/group IDs.

Change-Id: Icd1a1cf7365c8a4a64ae601993dc4273802610fb
Reviewed-on: https://boringssl-review.googlesource.com/7955
Reviewed-by: David Benjamin <davidben@google.com>

This explicitly forbids an API pattern which formerly kind of worked, but was
extremely buggy (see preceding commits). Depending on how one interprets
close_notify and our API, one might wish to call SSL_shutdown only once
(morally shutdown(SHUT_WR)) and then SSL_read until EOF.

However, this exposes additional confusing states where we might try to send an
alert post-SHUT_WR, etc. Early commits made us more robust here (whether one is
allowed to touch the SSL* after an operattion failed because it read an alert
is... unclear), so we could support it if we wanted to, but this doesn't seem
worth the additional statespace. See if we can get away with not allowing it.

Change-Id: Ie7a7e5520b464360b1e6316c34ec9854b571782f
Reviewed-on: https://boringssl-review.googlesource.com/7433
Reviewed-by: David Benjamin <davidben@google.com>

The existing logic gets confused in a number of cases around close_notify vs.
fatal alert. SSL_shutdown, while still pushing to the error queue, will fail to
notice alerts. We also get confused if we try to send a fatal alert when we've
already sent something else.

Change-Id: I9b1d217fbf1ee8a9c59efbebba60165b7de9689e
Reviewed-on: https://boringssl-review.googlesource.com/7952
Reviewed-by: David Benjamin <davidben@google.com>

SSL_RECEIVED_SHUTDOWN checks in the record layer happen in two different
places. Some operations (but not all) check it, and so does read_bytes. Move it
to get_record.

This check should be at a low-level since it is otherwise duplicated in every
operation. It is also a signal which originates from around the peer's record
layer, so it makes sense to check it near the same code. (This one's in
get_record which is technically lower-level than read_bytes, but we're trying
to get rid of read_bytes. They're very coupled functions.)

Also, if we've seen a fatal alert, replay an error, not an EOF.

Change-Id: Idec35c5068ddabe5b1a9145016d8f945da2421cf
Reviewed-on: https://boringssl-review.googlesource.com/7436
Reviewed-by: David Benjamin <davidben@google.com>

This allows an application to override the default of 1 second, which
is what's instructed in RFC 6347 but is not an absolute requirement.

Change-Id: I0bbb16e31990fbcab44a29325b6ec7757d5789e5
Reviewed-on: https://boringssl-review.googlesource.com/7930
Reviewed-by: David Benjamin <davidben@google.com>

Having bbio be tri-state (not allocated, allocated but not active, and
allocated and active) is confusing.

The extra state is only used in the client handshake, where ClientHello is
special-cased to not go through the buffer while everything else is. This dates
to OpenSSL's initial commit and doesn't seem to do much. I do not believe it
can affect renego as the buffer only affects writes; although OpenSSL accepted
interleave on read (though this logic predates it slightly), it never sent
application data while it believed a handshake was active. The handshake would
always be driven to completion first.

My guess is this was to save a copy since the ClientHello is a one-message
flight so it wouldn't need to be buffered? This is probably not worth the extra
variation in the state. (Especially with the DTLS state machine going through
ClientHello twice and pushing the BIO in between the two. Though I suspect that
was a mistake in itself. If the optimization guess is correct, there was no
need to do that.)

Change-Id: I6726f866e16ee7213cab0c3e6abb133981444d47
Reviewed-on: https://boringssl-review.googlesource.com/7873
Reviewed-by: Adam Langley <agl@google.com>

The DTLS bbio logic is rather problematic, but this shouldn't make things
worse. In the in-handshake case, the new code merges the per-message
(unchecked) BIO_flush calls into one call at the end but otherwise the BIO is
treated as is. Otherwise any behavior around non-block writes should be
preserved.

In the post-handshake case, we now install the buffer when we didn't
previously. On write error, the buffer will have garbage in it, but it will be
discarded, so that will preserve any existing retry behavior. (Arguably the
existing retry behavior is a bug, but that's another matter.)

Add a test for all this, otherwise it is sure to regress. Testing for
record-packing is a little fuzzy, but we can assert ChangeCipherSpec always
shares a record with something.

BUG=57

Change-Id: I8603f20811d502c71ded2943b0e72a8bdc4e46f2
Reviewed-on: https://boringssl-review.googlesource.com/7871
Reviewed-by: Adam Langley <agl@google.com>

The logic is a little hairy, partly because we used to support multiple
certificate slots.

Change-Id: Iee8503e61f5e0e91b7bcb15f526e9ef7cc7ad860
Reviewed-on: https://boringssl-review.googlesource.com/7823
Reviewed-by: David Benjamin <davidben@google.com>

We reset it to SSL_NOTHING at the start of ever SSL_get_error-using operation.
Then we only set it to a non-NOTHING value in the rest of the stack on error
paths.

Currently, ssl->rwstate is set all over the place. Sometimes the pattern is:

  ssl->rwstate = SSL_WRITING;
  if (BIO_write(...) <= 0) {
    goto err;
  }
  ssl->rwstate = SSL_NOTHING;

Sometimes we only set it to the non-NOTHING value on error.

  if (BIO_write(...) <= 0) {
    ssl->rwstate = SSL_WRITING;
  }
  ssl->rwstate = SSL_NOTHING;

Sometimes we just set it to SSL_NOTHING far from any callback in random places.

The third case is arbitrary and clearly should be removed.

But, in the second case, we sometimes forget to undo it afterwards. This is
largely harmless since an error in the error queue overrides rwstate, but we
don't always put something in the error queue (falling back to
SSL_ERROR_SYSCALL for "I'm not sure why it failed. Perhaps it was one of your
callbacks? Check your errno equivalent."), but in that case a stray rwstate
value will cause it to be wrong.

We could fix the cases where we fail to set SSL_NOTHING on success cases, but
this doesn't account for there being multiple SSL_get_error operations. The
consumer may have an SSL_read and an SSL_write running concurrently. Instead,
it seems the best option is to lift the SSL_NOTHING reset to the operations and
set SSL_WRITING and friends as in the second case.

(Someday hopefully we can fix this to just be an enum that is internally
returned. It can convert to something stateful at the API layer.)

Change-Id: I54665ec066a64eb0e48a06e2fcd0d2681a42df7f
Reviewed-on: https://boringssl-review.googlesource.com/7453
Reviewed-by: David Benjamin <davidben@google.com>

A lot of consumers of obj.h only want the NID values. Others didn't need
it at all. This also removes some OBJ_nid2sn and OBJ_nid2ln calls in EVP
error paths which isn't worth pulling a large table in for.

BUG=chromium:499653

Change-Id: Id6dff578f993012e35b740a13b8e4f9c2edc0744
Reviewed-on: https://boringssl-review.googlesource.com/7563
Reviewed-by: David Benjamin <davidben@google.com>

This removes the final use of in_handshake. Note that there is still a
rentrant call of read_bytes -> handshake_func when we see a
HelloRequest. That will need to be signaled up to ssl_read_impl
separately out of read_app_data.

Change-Id: I823de243f75e6b73eb40c6cf44157b4fc21eb8fb
Reviewed-on: https://boringssl-review.googlesource.com/7439
Reviewed-by: David Benjamin <davidben@google.com>

Change-Id: Id89c982f8f524720f189b528c987c9e58ca06ddf
Reviewed-on: https://boringssl-review.googlesource.com/7438
Reviewed-by: David Benjamin <davidben@google.com>

This removes one use of in_handshake and consolidates some DTLS and TLS
code.

Change-Id: Ibbdd38360a983dabfb7b18c7bd59cb5e316b2adb
Reviewed-on: https://boringssl-review.googlesource.com/7435
Reviewed-by: David Benjamin <davidben@google.com>

fatal_alert isn't read at all right now, and warn_alert is only checked
for close_notify. We only need three states:

 - Not shutdown.
 - Got a fatal alert (don't care which).
 - Got a warning close_notify.

Leave ssl->shutdown alone for now as it's tied up with SSL_set_shutdown
and friends. To distinguish the remaining two, we only need a boolean.

Change-Id: I5877723af82b76965c75cefd67ec1f981242281b
Reviewed-on: https://boringssl-review.googlesource.com/7434
Reviewed-by: David Benjamin <davidben@google.com>

Most code already dereferences it directly.

Change-Id: I227fa91ecbf25a19077f7cfba21b0abd2bc2bd1d
Reviewed-on: https://boringssl-review.googlesource.com/7422
Reviewed-by: David Benjamin <davidben@google.com>

Change-Id: I6267c9bfb66940d0b6fe5368514210a058ebd3cc
Reviewed-on: https://boringssl-review.googlesource.com/7494
Reviewed-by: Emily Stark (Dunn) <estark@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

OpenSSL historically made some poor API decisions. Rather than returning a
status enum in SSL_read, etc., these functions must be paired with
SSL_get_error which determines the cause of the last error's failure. This
requires SSL_read communicate with SSL_get_error with some stateful flag,
rwstate.

Further, probably as workarounds for bugs elsewhere, SSL_get_error does not
trust rwstate. Among other quirks, if the error queue is non-empty,
SSL_get_error overrides rwstate and returns a value based on that. This
requires that SSL_read, etc., be called with an empty error queue. (Or we hit
one of the spurious ERR_clear_error calls in the handshake state machine,
likely added as further self-workarounds.)

Since requiring callers consistently clear the error queue everywhere is
unreasonable (crbug.com/567501), clear ERR_clear_error *once* at the entry
point. Until/unless[*] we make SSL_get_error sane, this is the most reasonable
way to get to the point that clearing the error queue on error is optional.

With those in place, the calls in the handshake state machine are no longer
needed. (I suspect all the ERR_clear_system_error calls can also go, but I'll
investigate and think about that separately.)

[*] I'm not even sure it's possible anymore, thanks to the possibility of
BIO_write pushing to the error queue.

BUG=567501,593963

Change-Id: I564ace199e5a4a74b2554ad3335e99cd17120741
Reviewed-on: https://boringssl-review.googlesource.com/7455
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

In OpenSSL, they create socket BIOs. The distinction isn't important on UNIX.
On Windows, file descriptors are provided by the C runtime, while sockets must
use separate recv and send APIs. Document how these APIs are intended to work.

Also add a TODO to resolve the SOCKET vs int thing. This code assumes that
Windows HANDLEs only use the bottom 32 bits of precision. (Which is currently
true and probably will continue to be true for the foreseeable future[*], but
it'd be nice to do this right.)

Thanks to Gisle Vanem and Daniel Stenberg for reporting the bug.

[*] Both so Windows can continue to run 32-bit programs and because of all the
random UNIX software, like OpenSSL and ourselves, out there which happily
assumes sockets are ints.

Change-Id: I67408c218572228cb1a7d269892513cda4261c82
Reviewed-on: https://boringssl-review.googlesource.com/7333
Reviewed-by: David Benjamin <davidben@google.com>

Node.js calls it but handles it failing. Since we have abstracted this
in the state machine, we mightn't even be using a cipher suite where the
server's key can be expressed as an EVP_PKEY.

Change-Id: Ic3f013dc9bcd7170a9eb2c7535378d478b985849
Reviewed-on: https://boringssl-review.googlesource.com/7272
Reviewed-by: David Benjamin <davidben@google.com>

Sending close_notify during init causes some problems for some
applications so we instead revert to the previous behavior returning an
error instead of silently passing.

(Imported from upstream's 64193c8218)

Change-Id: I5efed1ce152197d291e6c7ece6e5dbb8f3ad867d
Reviewed-on: https://boringssl-review.googlesource.com/7232
Reviewed-by: David Benjamin <davidben@google.com>

This stub returns an empty string rather than NULL (since some callers
might assume that NULL means there are no shared ciphers).

Change-Id: I9537fa0a80c76559b293d8518599b68fd9977dd8
Reviewed-on: https://boringssl-review.googlesource.com/7196
Reviewed-by: David Benjamin <davidben@google.com>

Calling SSL_shutdown while in init previously gave a "1" response,
meaning everything was successfully closed down (even though it
wasn't). Better is to send our close_notify, but fail when trying to
receive one.

The problem with doing a shutdown while in the middle of a handshake
is that once our close_notify is sent we shouldn't really do anything
else (including process handshake/CCS messages) until we've received a
close_notify back from the peer. However the peer might send a CCS
before acting on our close_notify - so we won't be able to read it
because we're not acting on CCS messages!

(Imported from upstream's f73c737c7a)
Change-Id: Iaad5c5e38983456d3697c955522a89919628024b
Reviewed-on: https://boringssl-review.googlesource.com/7207
Reviewed-by: David Benjamin <davidben@google.com>

While it's always safe to read |SSL_MAX_SSL_SESSION_ID_LENGTH| bytes
from an |SSL_SESSION|'s |session_id| array, the hash function would do
so with without considering if all those bytes had been written to.

This change checks |session_id_length| before possibly reading
uninitialised memory. Since the result of the hash function was already
attacker controlled, and since a lookup of a short session ID will
always fail, it doesn't appear that this is anything more than a clean
up.

BUG=586800

Change-Id: I5f59f245b51477d6d4fa2cdc20d40bb6b4a3eae7
Reviewed-on: https://boringssl-review.googlesource.com/7150
Reviewed-by: David Benjamin <davidben@google.com>

I switched up the endianness. Add some tests to make sure those work right.

Also tweak the DTLS semantics. SSL_get_read_sequence should return the highest
sequence number received so far. Include the epoch number in both so we don't
need a second API for it.

Change-Id: I9901a1665b41224c46fadb7ce0b0881dcb466bcc
Reviewed-on: https://boringssl-review.googlesource.com/7141
Reviewed-by: Adam Langley <agl@google.com>

C has implicit conversion of |void *| to other pointer types so these
casts are unnecessary. Clean them up to make the code easier to read
and to make it easier to find dangerous casts.

Change-Id: I26988a672e8ed4d69c75cfbb284413999b475464
Reviewed-on: https://boringssl-review.googlesource.com/7102
Reviewed-by: David Benjamin <davidben@google.com>