Commit Graph

115 Commits

Author SHA1 Message Date
a21fd9c1bc
refactors record encryption code (#122) 2018-08-13 11:45:26 +01:00
e81269b57e Revert "Small refactoring of record encryption code"
This reverts commit 1782162852.
2018-08-10 20:50:12 +01:00
1782162852 Small refactoring of record encryption code 2018-08-10 20:48:54 +01:00
ad86d61c42 Let's use constant instead of hardcoding values (same is done in bssl) 2018-08-10 18:45:48 +01:00
d3e18f99e2
Minimal number of changes needed to udpate to draft-28 (#115)
* includes AD in authentication check of TLS records

As per 5.2 of TLS 1.3 draft-28, the additional data is record header.

* tests: Update tests in order to support draft-28

* Interoperability: Updates NSS and BoringSSL versions to the
  one supporting draft-28
* Bogo: Updates revision number to use tests for draft-28
* FIX: makefile was using test-compat target instead of
  test-interop

* DC test: constify

* Use binary interface to encode in big-endian
2018-08-09 20:47:50 +01:00
Christopher Patton
c5280001a4 Remove delegated credential minting from the API
What's left are the minimal API changes required to use the delegated
credential extension in the TLS handshake.
2018-07-27 19:12:28 +01:00
Christopher Patton
84fe9084cd Implement the delegated_credential extension for TLS
This complies with the standard, currently an Internet draft:
https://tlswg.github.io/tls-subcerts/draft-ietf-tls-subcerts.html

It also adds a minimal interface for generating new delegated
credentials.
2018-07-03 09:57:54 -07:00
6acee69d6b Use certificate_request specific to TLS 1.3 2018-03-27 08:52:44 +01:00
Peter Wu
824987c5ad tris: implement draft-22 middlebox compatibility mode
Send/Skip CCS, set legacy record version to 3,3 and echo session ID.
CCS must be ignored while the handshake is running, but not thereafter:
https://tools.ietf.org/html/draft-ietf-tls-tls13-22#section-5

Unconditionally send CCS as server because bogo requires it, even if no
session ID is included in the Client Hello. TLS 1.3 clients MUST ignore
it anyway, so it should not hurt.

Fixes interop with boringssl and openssl and passes bogo.
2017-12-13 20:16:48 +00:00
Peter Wu
e89292ccbe tris: convert end_of_early_data to a handshake message
Draft 21 changed end_of_early_data from an alert into a handshake
message to allow it to integrate better with the handshake. This change
does that, rather than handling EOD at the record layer, it moves
processing up to the actual readers of (early) application data.
2017-12-13 17:49:25 +00:00
Peter Wu
b1e5feadef tris: prevent sending 0.5-RTT data
Disable 0.5-RTT as it has weaker security properties than 1-RTT. The
same security considerations from TLS False Start (RFC 7918) apply.

Currently the server Handshake method returns as soon as it has sent its
parameters, but it does not wait for the client to authenticate the
handshake via a Finished message. This broke a test that assumed that
the Handshake message performs a full handshake and also
(unintentionally?) enabled the server to send application data before
the handshake is complete ("0.5-RTT data").

Fix this by moving the implicit Finished message check in the handshake
message reader to the server handshake itself (previously readRecord
would process the Finished message as a side-effect of requesting
recordTypeApplicationData). And in the special case where 0-RTT data is
actually desired, process the Finished message in the ConfirmHandshake
and Read functions.

NOTE: 0.5-RTT is not disabled when the server enables 0-RTT. It is the
server responsibility to use ConfirmHandshake before writing anything.

Explicitly panic when ConfirmHandshake is used for client connections,
this is not the intended use of that API.
2017-12-01 19:08:31 +00:00
Peter Wu
8523d7d8e0 tris: ignore NewSessionTicket messages as client
Prevent unexpected_message alert, PSK resumption is not supported so
ignore the received session ticket as client.
2017-12-01 19:08:31 +00:00
Peter Wu
de3ae8f61d tris: accept other post-handshake messages as client
Do not assume that every post-handshake messages are HelloRequests that
try to trigger a renegotiation. This could result in a no_renegotiation
(rather than an unexpected_message) alert even for other message types
(like NewSessionTicket).

This change makes the caller of readRecord(recordTypeApplicationData)
responsible for checking for renegotiation in case of a handshake
message, but that is currently already the case. And the condition
"c.phase == waitingClientFinished" can only be hit by the server, so
that won't have break the handshake either.

Related: https://github.com/cloudflare/tls-tris/issues/50
2017-12-01 19:08:31 +00:00
Peter Wu
4e6ebb63dd tris: unify ServerHello processing in preparation for D22
Merge serverHelloMsg13 into serverHelloMsg in preparation for draft 22.
This will also simplify the client implementation since only one
structure has to be checked.

Also fixed potential out-of-bounds access with keyShare unmarshal.
2017-11-24 19:44:22 +00:00
Peter Wu
0bbbecd894 crypto/tls: accept 2^14+1 TLSInnerPlaintext
The record layer splits application data into chunks of at most 2^14
octets. When record protection is engaged in TLS 1.3, the application
data is serialized into a TLSInnerPlaintext which has an additional byte
for the content type, resulting in a maximum length of 2^14+1.

Fixes LargeMessage, TLS13-AEAD-CHACHA20-POLY1305-LargeRecord,
TLS13-AEAD-AES128-GCM-SHA256-LargeRecord and
TLS13-AEAD-AES256-GCM-SHA384-LargeRecord bogo tests.

Fixes: https://github.com/cloudflare/tls-tris/issues/46
2017-11-16 19:32:56 +00:00
Peter Wu
fa9ccdc8b0 Merge branch 'pwu/go-update/master' into pwu/master-merge-upstream
Merge upstream go post-1.9 crypto/tls changes from master:

d8ee5d11e5 crypto/tls: limit number of consecutive warning alerts
96cd66b266 crypto/tls: advertise support for SHA-512 signatures in 1.2
f265f5db5d archive/zip, crypto/tls: use rand.Read instead of casting ints to bytes
54d04c2fcb crypto/tls: remove bookkeeping code from pHash function
d1bbdbe760 crypto/tls: replace signatureAndHash by SignatureScheme.
cb3b345209 crypto/tls: fix first byte test for 255 CBC padding bytes
d153df8e4b all: revert "all: prefer strings.LastIndexByte over strings.LastIndex"
5e42658fc0 all: prefer bytes.IndexByte over bytes.Index
d2826d3e06 all: prefer strings.LastIndexByte over strings.LastIndex
5a986eca86 all: fix article typos
0f9a2cf2c4 crypto/tls: fix clientHelloMsg fuzzer not to generate the RI SCSV
e7d46cee2f crypto/tls: fix and expand TestVerifyPeerCertificate and TestGetClientCertificate
85deaf6077 crypto/tls: fix docstring of Config.ClientSessionCache
4a5f85babb crypto/tls: disallow handshake messages fragmented across CCS
b3465646ff crypto/tls: add BenchmarkHandshakeServer
d38d357c78 crypto/tls: don't check whether an ec point is on a curve twice
e085a891f0 crypto/tls: split clientHandshake into multiple methods

Conflicts:
 * handshake_client.go: conflict between our ("crypto/tls: allow client to
   pick TLS 1.3, do not enable it by default.") and upstream
   ("crypto/tls: split clientHandshake into multiple methods"), resolve
   by applying the mutualVersion->pickVersion change in pickTLSVersion.
 * handshake_server.go: trivial conflict due to upstreamed patch
   ("crypto/tls: replace signatureAndHash by SignatureScheme.") and
   ("crypto/tls: implement TLS 1.3 server 0-RTT") which added pskBinder.

Other merge changes:
 * tls13.go: signatureAndHashes as added in ("crypto/tls: implement TLS
   1.3 minimal server") was renamed as required by ("crypto/tls: replace
   signatureAndHash by SignatureScheme.").
 * handshake_client.go: moved check from ("crypto/tls: check that client
   cipher suite matches version") to pickCipherSuite as required by
   ("crypto/tls: split clientHandshake into multiple methods").
2017-11-14 14:26:20 +00:00
Peter Wu
9e22da5ecc tris: restore retry logic on warning alerts
Not sure why the retry logic was removed since 0-RTT works even in
presence of the special alerts handling (alertEndOfEarlyData is
processed before the warning alert). To reduce divergence from upstream
code (which adds a restriction on the number of consecutive warnings),
restore the original retry logic.

Do not do anything fancy here, later drafts will remove the special
alert handling since it becomes a special handshake message.

Fixes: ("crypto/tls: implement TLS 1.3 server 0-RTT")
2017-11-14 13:32:40 +00:00
filewalkwithme
ff1bc5469f crypto/tls: limit number of consecutive warning alerts
In the current implementation, it is possible for a client to
continuously send warning alerts, which are just dropped on the floor
inside readRecord.

This can enable scenarios in where someone can try to continuously
send warning alerts to the server just to keep it busy.

This CL implements a simple counter that triggers an error if
we hit the warning alert limit.

Fixes #22543

Change-Id: Ief0ca10308cf5a4dea21a5a67d3e8f6501912da6
Reviewed-on: https://go-review.googlesource.com/75750
Reviewed-by: Adam Langley <agl@golang.org>
Reviewed-by: Filippo Valsorda <hi@filippo.io>
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-11-08 23:18:52 +00:00
Peter Wu
8ae95fd882 crypto/tls: fix first byte test for 255 CBC padding bytes
The BadCBCPadding255 test from bogo failed because at most 255 trailing
bytes were checked, but for a padding of 255 there are 255 padding bytes
plus 1 length byte with value 255.

Change-Id: I7dd237c013d2c7c8599067246e31b7ba93106cf7
Reviewed-on: https://go-review.googlesource.com/68070
Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-10-06 18:07:04 +00:00
Filippo Valsorda
4f7b5988a3 crypto/tls: add ConnectionState.Unique0RTTToken 2017-09-05 21:06:35 +01:00
Filippo Valsorda
44df381ccb crypto/tls: peek at unencrypted alerts to give better errors 2017-09-05 21:06:35 +01:00
Filippo Valsorda
de613b152d crypto/tls: disallow handshake messages fragmented across CCS
BoGo: FragmentAcrossChangeCipherSpec-Server-Packed
2017-09-05 21:06:35 +01:00
Filippo Valsorda
4191962f25 crypto/tls: use correct alerts
BoGo: Resume-Server-PSKBinderFirstExtension
BoGo: Resume-Server-ExtraPSKBinder
BoGo: Resume-Server-ExtraIdentityNoBinder
BoGo: Renegotiate-Server-Forbidden
BoGo: NoNullCompression
BoGo: TrailingMessageData-*
2017-09-05 21:06:35 +01:00
Filippo Valsorda
faefac5f1a crypto/tls: stop ConfirmHandshake from locking on any Read
ConfirmHandshake should block on a Read until the handshakeConfirmed
state is reached, but past that it shouldn't.
2017-09-05 21:06:34 +01:00
Filippo Valsorda
1b03258899 crypto/tls: simplify the Handshake locking
See https://groups.google.com/forum/#!topic/golang-dev/Xxiai-R_jH0

Change-Id: I6052695ece9aff9e3112c2fb176596fde8aa9cb2
2017-09-05 21:06:34 +01:00
Filippo Valsorda
341de96a61 crypto/tls: fix Conn.phase data races
Phase should only be accessed under in.Mutex. Handshake and all Read
operations obtain that lock. However, many functions checking for
handshakeRunning only obtain handshakeMutex: reintroduce
handshakeCompleted for them. ConnectionState and Close check for
handshakeConfirmed, introduce an atomic flag for them.
2017-09-05 21:06:34 +01:00
Filippo Valsorda
f3fe024dc7 crypto/tls: do not drain 0-RTT data on Close
There is no reason a server can't just send a CloseNotify in its first
flight, and then close the connection without reading the 0-RTT data.

Also, it's not expected of Close to block on reading, and interlocking
with a Read can cause a deadlock.

Fixes NCC-2016-001
2017-09-05 21:06:34 +01:00
Filippo Valsorda
180bfdbd68 crypto/tls: finish the session ticket state checks 2017-09-05 21:06:34 +01:00
Filippo Valsorda
f8c15889af crypto/tls: implement TLS 1.3 server 0-RTT 2017-09-05 21:06:34 +01:00
Filippo Valsorda
1117f76fcc crypto/tls: return from Handshake before the Client Finished in 1.3 2017-09-05 21:06:34 +01:00
Filippo Valsorda
453bd6af77 crypto/tls: implement TLS 1.3 PSK messages 2017-09-05 21:06:34 +01:00
Filippo Valsorda
6c3765bb15 tris: add error tracing with CH dumping 2017-09-05 21:06:34 +01:00
Filippo Valsorda
8052dc002f tris: extend ConnectionInfo 2017-09-05 21:06:34 +01:00
Filippo Valsorda
4b0d17eca3 crypto/tls: implement TLS 1.3 minimal server 2017-09-05 21:06:29 +01:00
Filippo Valsorda
9bc837c453 [dev.tls] crypto/tls: implement TLS 1.3 messages
Updates #9671

Change-Id: Ia1b06ae518a4b2821a584a420d99859a2666c8f0
2017-09-05 20:27:04 +01:00
Filippo Valsorda
7743362eba [dev.tls] crypto/tls: implement TLS 1.3 record layer
Opening the 1.3 dances with the record layer because it has been the
most stable through the drafts, has the least dependencies, and has been
tricky in my experience.

Note that the record layer version check is entirely removed according
to https://tools.ietf.org/html/draft-ietf-tls-tls13-18#appendix-C.2.

A test that happened to hit that check (but was not made to test for it)
has changed to the next error in the stack.

There are no 1.3 tests at the moment, and I suspect they will all have to
wait for the patch cycle to reach interoperability.

Using > / <= VersionTLS13 for all conditionals to transparently support
draft versions and hypotetical future versions.

See https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-5.

Updates #9671

Change-Id: I97f0a59439728f194a1c50b48cff041469a0f00b
2017-09-05 20:27:04 +01:00
Filippo Valsorda
d6b90c312b crypto/tls: disallow handshake messages fragmented across CCS
Detected by BoGo test FragmentAcrossChangeCipherSpec-Server-Packed.

Change-Id: I9a76697b9cdeb010642766041971de5c7e533481
Reviewed-on: https://go-review.googlesource.com/48811
Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
2017-08-15 18:45:06 +00:00
Adam Langley
fedcc1ec9c crypto/tls: don't hold lock when closing underlying net.Conn.
There's no need to hold the handshake lock across this call and it can
lead to deadlocks if the net.Conn calls back into the tls.Conn.

Fixes #18426.

Change-Id: Ib1b2813cce385949d970f8ad2e52cfbd1390e624
Reviewed-on: https://go-review.googlesource.com/36561
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-02-09 19:02:55 +00:00
Mikio Hara
d2353f871d crypto/tls: fix a typo
Change-Id: Id0044c45c23c12ee0bca362a9cdd25369ed7776c
Reviewed-on: https://go-review.googlesource.com/34533
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-12-19 06:01:04 +00:00
Dmitri Shuralyov
b8725556fa all: spell "marshal" and "unmarshal" consistently
The tree is inconsistent about single l vs double l in those
words in documentation, test messages, and one error value text.

	$ git grep -E '[Mm]arshall(|s|er|ers|ed|ing)' | wc -l
	      42
	$ git grep -E '[Mm]arshal(|s|er|ers|ed|ing)' | wc -l
	    1694

Make it consistently a single l, per earlier decisions. This means
contributors won't be confused by misleading precedence, and it helps
consistency.

Change the spelling in one error value text in newRawAttributes of
crypto/x509 package to be consistent.

This change was generated with:

	perl -i -npe 's,([Mm]arshal)l(|s|er|ers|ed|ing),$1$2,' $(git grep -l -E '[Mm]arshall' | grep -v AUTHORS | grep -v CONTRIBUTORS)

Updates #12431.
Follows https://golang.org/cl/14150.

Change-Id: I85d28a2d7692862ccb02d6a09f5d18538b6049a2
Reviewed-on: https://go-review.googlesource.com/33017
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-11-12 00:13:35 +00:00
Ben Burkert
54967fbddc crypto/tls: add CloseWrite method to Conn
The CloseWrite method sends a close_notify alert record to the other
side of the connection. This record indicates that the sender has
finished sending on the connection. Unlike the Close method, the sender
may still read from the connection until it recieves a close_notify
record (or the underlying connection is closed). This is analogous to a
TCP half-close.

This is a rework of CL 25159 with fixes for the unstable test.

Updates #8579

Change-Id: I47608d2f82a88baff07a90fd64c280ed16a60d5e
Reviewed-on: https://go-review.googlesource.com/31318
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-10-26 23:05:40 +00:00
Adam Langley
2d346b9207 Revert "crypto/tls: add CloseWrite method to Conn"
This reverts commit c6185aa63217c84a1a73c578c155e7d4dec6cec8. That
commit seems to be causing flaky failures on the builders. See
discussion on the original thread: https://golang.org/cl/25159.

Change-Id: I26e72d962d4efdcee28a0bc61a53f246b046df77
Reviewed-on: https://go-review.googlesource.com/31316
Run-TryBot: Adam Langley <agl@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2016-10-17 21:33:09 +00:00
Adam Langley
41aac6ea44 crypto/tls: support ChaCha20-Poly1305.
This change adds support for the ChaCha20-Poly1305 AEAD to crypto/tls,
as specified in https://tools.ietf.org/html/rfc7905.

Fixes #15499.

Change-Id: Iaa689be90e03f208c40b574eca399e56f3c7ecf1
Reviewed-on: https://go-review.googlesource.com/30957
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2016-10-17 21:05:26 +00:00
Ben Burkert
152328ca0e crypto/tls: add CloseWrite method to Conn
The CloseWrite method sends a close_notify alert record to the other
side of the connection. This record indicates that the sender has
finished sending on the connection. Unlike the Close method, the sender
may still read from the connection until it recieves a close_notify
record (or the underlying connection is closed). This is analogous to a
TCP half-close.

Updates #8579

Change-Id: I9c6bc193efcb25cc187f7735ee07170afa7fdde3
Reviewed-on: https://go-review.googlesource.com/25159
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-10-17 14:26:55 +00:00
Filippo Valsorda
318ec0c21a crypto/tls: implement countermeasures against CBC padding oracles
The aim is to make the decrypt() timing profile constant, irrespective of
the CBC padding length or correctness.  The old algorithm, on valid padding,
would only MAC bytes up to the padding length threshold, making CBC
ciphersuites vulnerable to plaintext recovery attacks as presented in the
"Lucky Thirteen" paper.

The new algorithm Write()s to the MAC all supposed payload, performs a
constant time Sum()---which required implementing a constant time Sum() in
crypto/sha1, see the "Lucky Microseconds" paper---and then Write()s the rest
of the data. This is performed whether the padding is good or not.

This should have no explicit secret-dependent timings, but it does NOT
attempt to normalize memory accesses to prevent cache timing leaks.

Updates #13385

Change-Id: I15d91dc3cc6eefc1d44f317f72ff8feb0a9888f7
Reviewed-on: https://go-review.googlesource.com/18130
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2016-10-04 13:21:02 +00:00
David Benjamin
5716364b9c crypto/tls: Fix c.in.decrypt error handling.
readRecord was not returning early if c.in.decrypt failed and ran
through the rest of the function. It does set c.in.err, so the various
checks in the callers do ultimately notice before acting on the result,
but we should avoid running the rest of the function at all.

Also rename 'err' to 'alertValue' since it isn't actually an error.

Change-Id: I6660924716a85af704bd3fe81521b34766238695
Reviewed-on: https://go-review.googlesource.com/24709
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
2016-09-30 18:44:37 +00:00
Adam Langley
b7ba182f28 crypto/tls: fix deadlock when racing to complete handshake.
After renegotiation support was added (af125a5193c) it's possible for a
Write to block on a Read when racing to complete the handshake:
   1. The Write determines that a handshake is needed and tries to
      take the neccesary locks in the correct order.
   2. The Read also determines that a handshake is needed and wins
      the race to take the locks.
   3. The Read goroutine completes the handshake and wins a race
      to unlock and relock c.in, which it'll hold when waiting for
      more network data.

If the application-level protocol requires the Write to complete before
data can be read then the system as a whole will deadlock.

Unfortunately it doesn't appear possible to reverse the locking order of
c.in and handshakeMutex because we might read a renegotiation request at
any point and need to be able to do a handshake without unlocking.

So this change adds a sync.Cond that indicates that a goroutine has
committed to doing a handshake. Other interested goroutines can wait on
that Cond when needed.

The test for this isn't great. I was able to reproduce the deadlock with
it only when building with -race. (Because -race happened to alter the
timing just enough.)

Fixes #17101.

Change-Id: I4e8757f7b82a84e46c9963a977d089f0fb675495
Reviewed-on: https://go-review.googlesource.com/29164
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2016-09-22 18:36:58 +00:00
Filippo Valsorda
37110e801a crypto/tls: flush the buffer on handshake errors
Since 2a8c81ff handshake messages are not written directly to wire but
buffered.  If an error happens at the wrong time the alert will be
written to the buffer but never flushed, causing an EOF on the client
instead of a more descriptive alert.

Thanks to Brendan McMillion for reporting this.

Fixes #17037

Change-Id: Ie093648aa3f754f4bc61c2e98c79962005dd6aa2
Reviewed-on: https://go-review.googlesource.com/28818
Reviewed-by: Adam Langley <agl@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-09-11 23:29:03 +00:00
Atin M
4b78482c8b crypto/tls: set Conn.ConnectionState.ServerName unconditionally
Moves the state.ServerName assignment to outside the if
statement that checks for handshakeComplete.

Fixes #15571

Change-Id: I6c4131ddb16389aed1c410a975f9aa3b52816965
Reviewed-on: https://go-review.googlesource.com/22862
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
2016-08-17 20:21:08 +00:00
Adam Langley
0d94116736 crypto/tls: buffer handshake messages.
This change causes TLS handshake messages to be buffered and written in
a single Write to the underlying net.Conn.

There are two reasons to want to do this:

Firstly, it's slightly preferable to do this in order to save sending
several, small packets over the network where a single one will do.

Secondly, since 37c28759ca46cf381a466e32168a793165d9c9e9 errors from
Write have been returned from a handshake. This means that, if a peer
closes the connection during a handshake, a “broken pipe” error may
result from tls.Conn.Handshake(). This can mask any, more detailed,
fatal alerts that the peer may have sent because a read will never
happen.

Buffering handshake messages means that the peer will not receive, and
possibly reject, any of a flow while it's still being written.

Fixes #15709

Change-Id: I38dcff1abecc06e52b2de647ea98713ce0fb9a21
Reviewed-on: https://go-review.googlesource.com/23609
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-06-01 23:26:04 +00:00