ice: add State

ice.go

@@ -9,3 +9,27 @@ import (
 
 // bin is shorthand for BigEndian.
 var bin = binary.BigEndian
+
+// State represents the ICE agent state.
+//
+// As per RFC 8445 Section 6.1.3, the ICE agent has a state determined by the
+// state of the checklists. The state is Completed if all checklists are
+// Completed, Failed if all checklists are Failed, or Running otherwise.
+type State byte
+
+const (
+	// Running if all checklists are nor completed not failed.
+	Running State = iota
+	// Completed if all checklists are completed.
+	Completed
+	// Failed if all checklists are failed.
+	Failed
+)
+
+var stateToStr = map[State]string{
+	Running:   "Running",
+	Completed: "Completed",
+	Failed:    "Failed",
+}
+
+func (s State) String() string { return stateToStr[s] }