Initial QSfera import

Server/vendor/github.com/segmentio/kafka-go/sasl/sasl.go

@@ -0,0 +1,65 @@
+package sasl
+
+import "context"
+
+type ctxKey struct{}
+
+// Mechanism implements the SASL state machine for a particular mode of
+// authentication.  It is used by the kafka.Dialer to perform the SASL
+// handshake.
+//
+// A Mechanism must be re-usable and safe for concurrent access by multiple
+// goroutines.
+type Mechanism interface {
+	// Name returns the identifier for this SASL mechanism.  This string will be
+	// passed to the SASL handshake request and much match one of the mechanisms
+	// supported by Kafka.
+	Name() string
+
+	// Start begins SASL authentication. It returns an authentication state
+	// machine and "initial response" data (if required by the selected
+	// mechanism). A non-nil error causes the client to abort the authentication
+	// attempt.
+	//
+	// A nil ir value is different from a zero-length value. The nil value
+	// indicates that the selected mechanism does not use an initial response,
+	// while a zero-length value indicates an empty initial response, which must
+	// be sent to the server.
+	Start(ctx context.Context) (sess StateMachine, ir []byte, err error)
+}
+
+// StateMachine implements the SASL challenge/response flow for a single SASL
+// handshake.  A StateMachine will be created by the Mechanism per connection,
+// so it does not need to be safe for concurrent access by multiple goroutines.
+//
+// Once the StateMachine is created by the Mechanism, the caller loops by
+// passing the server's response into Next and then sending Next's returned
+// bytes to the server.  Eventually either Next will indicate that the
+// authentication has been successfully completed via the done return value, or
+// it will indicate that the authentication failed by returning a non-nil error.
+type StateMachine interface {
+	// Next continues challenge-response authentication. A non-nil error
+	// indicates that the client should abort the authentication attempt.  If
+	// the client has been successfully authenticated, then the done return
+	// value will be true.
+	Next(ctx context.Context, challenge []byte) (done bool, response []byte, err error)
+}
+
+// Metadata contains additional data for performing SASL authentication.
+type Metadata struct {
+	// Host is the address of the broker the authentication will be
+	// performed on.
+	Host string
+	Port int
+}
+
+// WithMetadata returns a copy of the context with associated Metadata.
+func WithMetadata(ctx context.Context, m *Metadata) context.Context {
+	return context.WithValue(ctx, ctxKey{}, m)
+}
+
+// MetadataFromContext retrieves the Metadata from the context.
+func MetadataFromContext(ctx context.Context) *Metadata {
+	m, _ := ctx.Value(ctxKey{}).(*Metadata)
+	return m
+}