1 files changed, 50 insertions, 0 deletions
diff --git a/p2p/protocol.go b/p2p/protocol.go
new file mode 100644
index 000000000..5fa395eda
--- /dev/null
+++ b/p2p/protocol.go
@@ -0,0 +1,50 @@
+package p2p
+
+import "fmt"
+
+// Protocol represents a P2P subprotocol implementation.
+type Protocol struct {
+	// Name should contain the official protocol name,
+	// often a three-letter word.
+	Name string
+
+	// Version should contain the version number of the protocol.
+	Version uint
+
+	// Length should contain the number of message codes used
+	// by the protocol.
+	Length uint64
+
+	// Run is called in a new groutine when the protocol has been
+	// negotiated with a peer. It should read and write messages from
+	// rw. The Payload for each message must be fully consumed.
+	//
+	// The peer connection is closed when Start returns. It should return
+	// any protocol-level error (such as an I/O error) that is
+	// encountered.
+	Run func(peer *Peer, rw MsgReadWriter) error
+}
+
+func (p Protocol) cap() Cap {
+	return Cap{p.Name, p.Version}
+}
+
+// Cap is the structure of a peer capability.
+type Cap struct {
+	Name    string
+	Version uint
+}
+
+func (cap Cap) RlpData() interface{} {
+	return []interface{}{cap.Name, cap.Version}
+}
+
+func (cap Cap) String() string {
+	return fmt.Sprintf("%s/%d", cap.Name, cap.Version)
+}
+
+type capsByName []Cap
+
+func (cs capsByName) Len() int           { return len(cs) }
+func (cs capsByName) Less(i, j int) bool { return cs[i].Name < cs[j].Name }
+func (cs capsByName) Swap(i, j int)      { cs[i], cs[j] = cs[j], cs[i] }