Add Nix flake for mciasctl and mciasgrpcctl

Vendor dependencies and expose control program binaries via
nix build. Uses nixpkgs-unstable for Go 1.26 support.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/github.com/google/go-tpm/tpmutil/structures.go

@@ -0,0 +1,195 @@
+// Copyright (c) 2018, Google LLC All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tpmutil
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+// maxBytesBufferSize sets a sane upper bound on the size of a U32Bytes
+// buffer. This limit exists to prevent a maliciously large size prefix
+// from resulting in a massive memory allocation, potentially causing
+// an OOM condition on the system.
+// We expect no buffer from a TPM to approach 1Mb in size.
+const maxBytesBufferSize uint32 = 1024 * 1024 // 1Mb.
+
+// RawBytes is for Pack and RunCommand arguments that are already encoded.
+// Compared to []byte, RawBytes will not be prepended with slice length during
+// encoding.
+type RawBytes []byte
+
+// U16Bytes is a byte slice with a 16-bit header
+type U16Bytes []byte
+
+// TPMMarshal packs U16Bytes
+func (b *U16Bytes) TPMMarshal(out io.Writer) error {
+	size := len([]byte(*b))
+	if err := binary.Write(out, binary.BigEndian, uint16(size)); err != nil {
+		return err
+	}
+
+	n, err := out.Write(*b)
+	if err != nil {
+		return err
+	}
+	if n != size {
+		return fmt.Errorf("unable to write all contents of U16Bytes")
+	}
+	return nil
+}
+
+// TPMUnmarshal unpacks a U16Bytes
+func (b *U16Bytes) TPMUnmarshal(in io.Reader) error {
+	var tmpSize uint16
+	if err := binary.Read(in, binary.BigEndian, &tmpSize); err != nil {
+		return err
+	}
+	size := int(tmpSize)
+
+	if len(*b) >= size {
+		*b = (*b)[:size]
+	} else {
+		*b = append(*b, make([]byte, size-len(*b))...)
+	}
+
+	n, err := in.Read(*b)
+	if err != nil {
+		return err
+	}
+	if n != size {
+		return io.ErrUnexpectedEOF
+	}
+	return nil
+}
+
+// U32Bytes is a byte slice with a 32-bit header
+type U32Bytes []byte
+
+// TPMMarshal packs U32Bytes
+func (b *U32Bytes) TPMMarshal(out io.Writer) error {
+	size := len([]byte(*b))
+	if err := binary.Write(out, binary.BigEndian, uint32(size)); err != nil {
+		return err
+	}
+
+	n, err := out.Write(*b)
+	if err != nil {
+		return err
+	}
+	if n != size {
+		return fmt.Errorf("unable to write all contents of U32Bytes")
+	}
+	return nil
+}
+
+// TPMUnmarshal unpacks a U32Bytes
+func (b *U32Bytes) TPMUnmarshal(in io.Reader) error {
+	var tmpSize uint32
+	if err := binary.Read(in, binary.BigEndian, &tmpSize); err != nil {
+		return err
+	}
+
+	if tmpSize > maxBytesBufferSize {
+		return bytes.ErrTooLarge
+	}
+	// We can now safely cast to an int on 32-bit or 64-bit machines
+	size := int(tmpSize)
+
+	if len(*b) >= size {
+		*b = (*b)[:size]
+	} else {
+		*b = append(*b, make([]byte, size-len(*b))...)
+	}
+
+	n, err := in.Read(*b)
+	if err != nil {
+		return err
+	}
+	if n != size {
+		return fmt.Errorf("unable to read all contents in to U32Bytes")
+	}
+	return nil
+}
+
+// Tag is a command tag.
+type Tag uint16
+
+// Command is an identifier of a TPM command.
+type Command uint32
+
+// A commandHeader is the header for a TPM command.
+type commandHeader struct {
+	Tag  Tag
+	Size uint32
+	Cmd  Command
+}
+
+// ResponseCode is a response code returned by TPM.
+type ResponseCode uint32
+
+// RCSuccess is response code for successful command. Identical for TPM 1.2 and
+// 2.0.
+const RCSuccess ResponseCode = 0x000
+
+// RCRetry is response code for TPM is busy.
+const RCRetry ResponseCode = 0x922
+
+// A responseHeader is a header for TPM responses.
+type responseHeader struct {
+	Tag  Tag
+	Size uint32
+	Res  ResponseCode
+}
+
+// A Handle is a reference to a TPM object.
+type Handle uint32
+
+// HandleValue returns the handle value. This behavior is intended to satisfy
+// an interface that can be implemented by other, more complex types as well.
+func (h Handle) HandleValue() uint32 {
+	return uint32(h)
+}
+
+type handleList []Handle
+
+func (l *handleList) TPMMarshal(_ io.Writer) error {
+	return fmt.Errorf("TPMMarhsal on []Handle is not supported yet")
+}
+
+func (l *handleList) TPMUnmarshal(in io.Reader) error {
+	var numHandles uint16
+	if err := binary.Read(in, binary.BigEndian, &numHandles); err != nil {
+		return err
+	}
+
+	// Make len(e) match size exactly.
+	size := int(numHandles)
+	if len(*l) >= size {
+		*l = (*l)[:size]
+	} else {
+		*l = append(*l, make([]Handle, size-len(*l))...)
+	}
+	return binary.Read(in, binary.BigEndian, *l)
+}
+
+// SelfMarshaler allows custom types to override default encoding/decoding
+// behavior in Pack, Unpack and UnpackBuf.
+type SelfMarshaler interface {
+	TPMMarshal(out io.Writer) error
+	TPMUnmarshal(in io.Reader) error
+}