add client addr for auth plugin

internal/util/auth/key.go

@@ -5,11 +5,14 @@ import (
 )
 
 type idKey struct{}
-
 type ID string
 
+type addrKey struct{}
+type ClientAddr string
+
 var (
-	clientIDKey = &idKey{}
+	clientIDKey   = &idKey{}
+	clientAddrKey = &addrKey{}
 )
 
 func ContextWithID(ctx context.Context, id ID) context.Context {
@@ -20,3 +23,12 @@ func IDFromContext(ctx context.Context) ID {
 	v, _ := ctx.Value(clientIDKey).(ID)
 	return v
 }
+
+func ContextWithClientAddr(ctx context.Context, addr ClientAddr) context.Context {
+	return context.WithValue(ctx, clientAddrKey, addr)
+}
+
+func ClientAddrFromContext(ctx context.Context) ClientAddr {
+	v, _ := ctx.Value(clientAddrKey).(ClientAddr)
+	return v
+}