init

comms/comms.go

@@ -0,0 +1,25 @@
+// Package comms validates the data that crosses the wormhole link. The
+// content of uplinks and downlinks is opaque bytes defined by the player's
+// ship program; only sizes are enforced.
+package comms
+
+import "fmt"
+
+func CheckUplink(data []byte, limit int) error {
+	if len(data) > limit {
+		return fmt.Errorf("uplink is %d bytes, limit is %d", len(data), limit)
+	}
+	return nil
+}
+
+func CheckProgram(prog []byte, limit int) error {
+	switch {
+	case len(prog) == 0:
+		return fmt.Errorf("program is empty")
+	case len(prog)%4 != 0:
+		return fmt.Errorf("program length %d is not a multiple of 4", len(prog))
+	case len(prog) > limit:
+		return fmt.Errorf("program is %d bytes, limit is %d", len(prog), limit)
+	}
+	return nil
+}