peer_protocol/msg.go     | 4 ++++
 peer_protocol/reqspec.go | 5 +++++

diff --git a/peer_protocol/msg.go b/peer_protocol/msg.go
index 476a54c0f11ce35c3697c53b1b8fc617710ebf93..7d3764b714223cafe832cc73b7a8f708694cf968 100644
--- a/peer_protocol/msg.go
+++ b/peer_protocol/msg.go
@@ -26,6 +26,10 @@ 		Length: length,
 	}
 }
 
+func (msg Message) RequestSpec() RequestSpec {
+	return RequestSpec{msg.Index, msg.Begin, msg.Length}
+}
+
 func (msg Message) MustMarshalBinary() []byte {
 	b, err := msg.MarshalBinary()
 	if err != nil {
diff --git a/peer_protocol/reqspec.go b/peer_protocol/reqspec.go
new file mode 100644
index 0000000000000000000000000000000000000000..f73a66df128e04c97950f990a33ad901d6d5db3a
--- /dev/null
+++ b/peer_protocol/reqspec.go
@@ -0,0 +1,5 @@
+package peer_protocol
+
+type RequestSpec struct {
+	Index, Begin, Length Integer
+}