Update mattermost library (#2152)

* Update mattermost library

* Fix linting

vendor/github.com/hashicorp/yamux/const.go

@@ -0,0 +1,182 @@
+package yamux
+
+import (
+	"encoding/binary"
+	"fmt"
+)
+
+// NetError implements net.Error
+type NetError struct {
+	err       error
+	timeout   bool
+	temporary bool
+}
+
+func (e *NetError) Error() string {
+	return e.err.Error()
+}
+
+func (e *NetError) Timeout() bool {
+	return e.timeout
+}
+
+func (e *NetError) Temporary() bool {
+	return e.temporary
+}
+
+var (
+	// ErrInvalidVersion means we received a frame with an
+	// invalid version
+	ErrInvalidVersion = fmt.Errorf("invalid protocol version")
+
+	// ErrInvalidMsgType means we received a frame with an
+	// invalid message type
+	ErrInvalidMsgType = fmt.Errorf("invalid msg type")
+
+	// ErrSessionShutdown is used if there is a shutdown during
+	// an operation
+	ErrSessionShutdown = fmt.Errorf("session shutdown")
+
+	// ErrStreamsExhausted is returned if we have no more
+	// stream ids to issue
+	ErrStreamsExhausted = fmt.Errorf("streams exhausted")
+
+	// ErrDuplicateStream is used if a duplicate stream is
+	// opened inbound
+	ErrDuplicateStream = fmt.Errorf("duplicate stream initiated")
+
+	// ErrReceiveWindowExceeded indicates the window was exceeded
+	ErrRecvWindowExceeded = fmt.Errorf("recv window exceeded")
+
+	// ErrTimeout is used when we reach an IO deadline
+	ErrTimeout = &NetError{
+		err: fmt.Errorf("i/o deadline reached"),
+
+		// Error should meet net.Error interface for timeouts for compatability
+		// with standard library expectations, such as http servers.
+		timeout: true,
+	}
+
+	// ErrStreamClosed is returned when using a closed stream
+	ErrStreamClosed = fmt.Errorf("stream closed")
+
+	// ErrUnexpectedFlag is set when we get an unexpected flag
+	ErrUnexpectedFlag = fmt.Errorf("unexpected flag")
+
+	// ErrRemoteGoAway is used when we get a go away from the other side
+	ErrRemoteGoAway = fmt.Errorf("remote end is not accepting connections")
+
+	// ErrConnectionReset is sent if a stream is reset. This can happen
+	// if the backlog is exceeded, or if there was a remote GoAway.
+	ErrConnectionReset = fmt.Errorf("connection reset")
+
+	// ErrConnectionWriteTimeout indicates that we hit the "safety valve"
+	// timeout writing to the underlying stream connection.
+	ErrConnectionWriteTimeout = fmt.Errorf("connection write timeout")
+
+	// ErrKeepAliveTimeout is sent if a missed keepalive caused the stream close
+	ErrKeepAliveTimeout = fmt.Errorf("keepalive timeout")
+)
+
+const (
+	// protoVersion is the only version we support
+	protoVersion uint8 = 0
+)
+
+const (
+	// Data is used for data frames. They are followed
+	// by length bytes worth of payload.
+	typeData uint8 = iota
+
+	// WindowUpdate is used to change the window of
+	// a given stream. The length indicates the delta
+	// update to the window.
+	typeWindowUpdate
+
+	// Ping is sent as a keep-alive or to measure
+	// the RTT. The StreamID and Length value are echoed
+	// back in the response.
+	typePing
+
+	// GoAway is sent to terminate a session. The StreamID
+	// should be 0 and the length is an error code.
+	typeGoAway
+)
+
+const (
+	// SYN is sent to signal a new stream. May
+	// be sent with a data payload
+	flagSYN uint16 = 1 << iota
+
+	// ACK is sent to acknowledge a new stream. May
+	// be sent with a data payload
+	flagACK
+
+	// FIN is sent to half-close the given stream.
+	// May be sent with a data payload.
+	flagFIN
+
+	// RST is used to hard close a given stream.
+	flagRST
+)
+
+const (
+	// initialStreamWindow is the initial stream window size
+	initialStreamWindow uint32 = 256 * 1024
+)
+
+const (
+	// goAwayNormal is sent on a normal termination
+	goAwayNormal uint32 = iota
+
+	// goAwayProtoErr sent on a protocol error
+	goAwayProtoErr
+
+	// goAwayInternalErr sent on an internal error
+	goAwayInternalErr
+)
+
+const (
+	sizeOfVersion  = 1
+	sizeOfType     = 1
+	sizeOfFlags    = 2
+	sizeOfStreamID = 4
+	sizeOfLength   = 4
+	headerSize     = sizeOfVersion + sizeOfType + sizeOfFlags +
+		sizeOfStreamID + sizeOfLength
+)
+
+type header []byte
+
+func (h header) Version() uint8 {
+	return h[0]
+}
+
+func (h header) MsgType() uint8 {
+	return h[1]
+}
+
+func (h header) Flags() uint16 {
+	return binary.BigEndian.Uint16(h[2:4])
+}
+
+func (h header) StreamID() uint32 {
+	return binary.BigEndian.Uint32(h[4:8])
+}
+
+func (h header) Length() uint32 {
+	return binary.BigEndian.Uint32(h[8:12])
+}
+
+func (h header) String() string {
+	return fmt.Sprintf("Vsn:%d Type:%d Flags:%d StreamID:%d Length:%d",
+		h.Version(), h.MsgType(), h.Flags(), h.StreamID(), h.Length())
+}
+
+func (h header) encode(msgType uint8, flags uint16, streamID uint32, length uint32) {
+	h[0] = protoVersion
+	h[1] = msgType
+	binary.BigEndian.PutUint16(h[2:4], flags)
+	binary.BigEndian.PutUint32(h[4:8], streamID)
+	binary.BigEndian.PutUint32(h[8:12], length)
+}