[IPSEC]: Remove run-time encap_type checks in esp4.

This allows us to remove all the per-packet checks on x->encap->encap_type.
I've left the check in esp_input just in case someone adds a non-ESP encap
type in future.

However, printing a warning and then continuing is definitely wrong.
So expect a follow-up patch to drop the packet when encap_type is
unknown in esp_input.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@redhat.com>

net/ipv4/esp4.c

@@ -94,8 +94,9 @@ int esp_output(struct sk_buff **pskb)
 	if (x->props.mode) {
 		top_iph = (struct iphdr*)skb_push(*pskb, x->props.header_len);
 		esph = (struct ip_esp_hdr*)(top_iph+1);
-		if (encap && encap->encap_type) {
+		if (encap) {
 			switch (encap->encap_type) {
+			default:
 			case UDP_ENCAP_ESPINUDP:
 				uh = (struct udphdr*) esph;
 				esph = (struct ip_esp_hdr*)(uh+1);
@@ -108,12 +109,6 @@ int esp_output(struct sk_buff **pskb)
 				esph = (struct ip_esp_hdr*)(udpdata32+2);
 				top_iph->protocol = IPPROTO_UDP;
 				break;
-			default:
-				printk(KERN_INFO
-				       "esp_output(): Unhandled encap: %u\n",
-				       encap->encap_type);
-				top_iph->protocol = IPPROTO_ESP;
-				break;
 			}
 		} else
 			top_iph->protocol = IPPROTO_ESP;
@@ -136,8 +131,9 @@ int esp_output(struct sk_buff **pskb)
 		esph = (struct ip_esp_hdr*)skb_push(*pskb, x->props.header_len);
 		top_iph = (struct iphdr*)skb_push(*pskb, iph->ihl*4);
 		memcpy(top_iph, &tmp_iph, iph->ihl*4);
-		if (encap && encap->encap_type) {
+		if (encap) {
 			switch (encap->encap_type) {
+			default:
 			case UDP_ENCAP_ESPINUDP:
 				uh = (struct udphdr*) esph;
 				esph = (struct ip_esp_hdr*)(uh+1);
@@ -150,12 +146,6 @@ int esp_output(struct sk_buff **pskb)
 				esph = (struct ip_esp_hdr*)(udpdata32+2);
 				top_iph->protocol = IPPROTO_UDP;
 				break;
-			default:
-				printk(KERN_INFO
-				       "esp_output(): Unhandled encap: %u\n",
-				       encap->encap_type);
-				top_iph->protocol = IPPROTO_ESP;
-				break;
 			}
 		} else
 			top_iph->protocol = IPPROTO_ESP;
@@ -365,11 +355,8 @@ int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct
 		if (encap->encap_type != decap->decap_type)
 			return -EINVAL;
 
-		/* Next, if we don't have an encap type, then ignore it */
-		if (!encap->encap_type)
-			return 0;
-
 		switch (encap->encap_type) {
+		default:
 		case UDP_ENCAP_ESPINUDP:
 		case UDP_ENCAP_ESPINUDP_NON_IKE:
 			/*
@@ -406,11 +393,6 @@ int esp_post_input(struct xfrm_state *x, struct xfrm_decap_state *decap, struct
 				skb->ip_summed = CHECKSUM_UNNECESSARY;
 
 			break;
-		default:
-			printk(KERN_INFO
-			       "esp4_post_input(): Unhandled encap type: %u\n",
-			       encap->encap_type);
-			break;
 		}
 	}
 	return 0;
@@ -547,20 +529,14 @@ int esp_init_state(struct xfrm_state *x, void *args)
 	if (x->encap) {
 		struct xfrm_encap_tmpl *encap = x->encap;
 
-		if (encap->encap_type) {
 		switch (encap->encap_type) {
+		default:
 		case UDP_ENCAP_ESPINUDP:
 			x->props.header_len += sizeof(struct udphdr);
 			break;
 		case UDP_ENCAP_ESPINUDP_NON_IKE:
 			x->props.header_len += sizeof(struct udphdr) + 2 * sizeof(u32);
 			break;
-			default:
-				printk (KERN_INFO
-				"esp_init_state(): Unhandled encap type: %u\n",
-					encap->encap_type);
-				break;
-			}
 		}
 	}
 	x->data = esp;