bootstrap: implement SignedDataSource on Request message

bootstrap/sign.go

@@ -0,0 +1,48 @@
+package bootstrap
+
+import "io"
+
+// SignedData returns payload bytes of the request.
+func (m Request) SignedData() ([]byte, error) {
+	data := make([]byte, m.SignedDataSize())
+
+	if _, err := m.ReadSignedData(data); err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}
+
+// SignedDataSize returns payload size of the request.
+func (m Request) SignedDataSize() (sz int) {
+	sz += m.GetType().Size()
+
+	sz += m.GetState().Size()
+
+	info := m.GetInfo()
+	sz += info.Size()
+
+	return
+}
+
+// ReadSignedData copies payload bytes to passed buffer.
+//
+// If the Request size is insufficient, io.ErrUnexpectedEOF returns.
+func (m Request) ReadSignedData(p []byte) (int, error) {
+	if len(p) < m.SignedDataSize() {
+		return 0, io.ErrUnexpectedEOF
+	}
+
+	var off int
+
+	off += copy(p[off:], m.GetType().Bytes())
+
+	off += copy(p[off:], m.GetState().Bytes())
+
+	info := m.GetInfo()
+	// FIXME: implement and use stable functions
+	n, err := info.MarshalTo(p[off:])
+	off += n
+
+	return off, err
+}