+ /*
+ * Remove encapsulation header.
+ *
+ * The IP header will be moved over the top of the encapsulation
+ * header.
+ *
+ * On entry, the transport header shall point to where the IP header
+ * should be and the network header shall be set to where the IP
+ * header currently is. skb->data shall point to the start of the
+ * payload.
+ */
+ int (*input2)(struct xfrm_state *x, struct sk_buff *skb);
+
+ /*
+ * This is the actual input entry point.
+ *
+ * For transport mode and equivalent this would be identical to
+ * input2 (which does not need to be set). While tunnel mode
+ * and equivalent would set this to the tunnel encapsulation function
+ * xfrm4_prepare_input that would in turn call input2.
+ */