Move attestation, atls and oid packages to internal directory

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

internal/attestation/simulator/simulator.go

@@ -0,0 +1,43 @@
+//go:build !disable_tpm_simulator
+// +build !disable_tpm_simulator
+
+package simulator
+
+import (
+	"io"
+
+	"github.com/google/go-tpm-tools/simulator"
+)
+
+// OpenSimulatedTPM returns a simulated TPM device.
+func OpenSimulatedTPM() (io.ReadWriteCloser, error) {
+	return simulator.Get()
+}
+
+// NewSimulatedTPMOpenFunc returns a TPMOpenFunc that opens a simulated TPM.
+func NewSimulatedTPMOpenFunc() (func() (io.ReadWriteCloser, error), io.Closer) {
+	tpm, err := OpenSimulatedTPM()
+	if err != nil {
+		panic(err)
+	}
+	return func() (io.ReadWriteCloser, error) {
+		return &simulatedTPM{tpm}, nil
+	}, tpm
+}
+
+type simulatedTPM struct {
+	openSimulatedTPM io.ReadWriteCloser
+}
+
+func (t *simulatedTPM) Read(p []byte) (int, error) {
+	return t.openSimulatedTPM.Read(p)
+}
+
+func (t *simulatedTPM) Write(p []byte) (int, error) {
+	return t.openSimulatedTPM.Write(p)
+}
+
+func (t *simulatedTPM) Close() error {
+	// never close the underlying simulated TPM to allow calling the TPMOpenFunc again
+	return nil
+}