mutualVersion takes a maximum version, but skips TLS 1.3 because this
version is not negotiated via ClientHello.legacy_version. The server
however still uses its ServerHello.version field to select a version
from the supported_versions extension and the client must do the same.
A new getSupportedVersions method is introduced to have a single place
to handle the mapping of VersionTLS13 to the draft values.
Remove the MaxVersion override to TLS 1.3, users must set MaxVersion if
they intent to use the experimental TLS 1.3 functionality.
Fixes: ("crypto/tls: make 1.3 version negotiation more robust")
To allow clients to advertise both TLS 1.2 and TLS 1.3 cipher suites,
remove the distinction between both suites. TLS 1.3 suites are now
always included in the default cipher list (and the client will send it
if MaxVersion allows for it).
Since TLS 1.3 is expected to become the default MaxVersion and
applications might have set only TLS 1.2 cipher suites in their
configuration, TLS 1.3 cipher suites are added when none are present.
Alternatively, I considered disallowing overriding the TLS 1.3 suites,
but that requires more complexity and has not much benefits. Provide a
mechanism and do not dictate policy, application developers might want
to fix a cipher suite for testing other implementations for example.
Fixes https://github.com/cloudflare/tls-tris/pull/22
Use the new keySchedule13 type instead of hash.Hash to avoid tracking
the hashContext and intermediate secrets manually.
checkPSK is modified not to return the calculated early secret, this is
internal to keySchedule13 now. The caller just learns whether it was
resumed using a PSK or not.
In order to reduce repetitive complexity (extract handshake context,
pass the right secrets around to calculate a secret and build a cipher),
create a new type that tracks the hash type, the handshake context and
intermediate secrets.
Advantages: facilitates reuse between client and server code, makes it
easier to update labels for draft-19, makes it easier to add central
KeyLogWriter functionality.
There should be no data in the Handshake buffer on encryption state
changes (including implicit 1.3 transitions). Checking that also blocks
all Handshake messages fragmented across CCS.
BoGo: PartialClientFinishedWithClientHello
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.
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
