ethernet: use switch instead of 'else if'

This patch uses a switch instead of a 'else if' series. It also
adds a debug message for unsupported ethernet type.

src/decode-ethernet.c

@@ -23,18 +23,30 @@ void DecodeEthernet(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p, uint8_t *p
 
     SCLogDebug("p %p pkt %p ether type %04x", p, pkt, ntohs(ethh->eth_type));
 
-    if (ntohs(ethh->eth_type) == ETHERNET_TYPE_IP) {
+    switch (ntohs(ethh->eth_type)) {
+        case ETHERNET_TYPE_IP:
             //printf("DecodeEthernet ip4\n");
-        DecodeIPV4(tv, dtv, p, pkt + ETHERNET_HEADER_LEN, len - ETHERNET_HEADER_LEN, pq);
-    } else if(ntohs(ethh->eth_type) == ETHERNET_TYPE_IPV6) {
+            DecodeIPV4(tv, dtv, p, pkt + ETHERNET_HEADER_LEN,
+                       len - ETHERNET_HEADER_LEN, pq);
+            break;
+        case ETHERNET_TYPE_IPV6:
             //printf("DecodeEthernet ip6\n");
-        DecodeIPV6(tv, dtv, p, pkt + ETHERNET_HEADER_LEN, len - ETHERNET_HEADER_LEN, pq);
-    } else if(ntohs(ethh->eth_type) == ETHERNET_TYPE_PPPOE_SESS) {
+            DecodeIPV6(tv, dtv, p, pkt + ETHERNET_HEADER_LEN,
+                       len - ETHERNET_HEADER_LEN, pq);
+            break;
+        case ETHERNET_TYPE_PPPOE_SESS:
             //printf("DecodeEthernet PPPOE Session\n");
-        DecodePPPOESession(tv, dtv, p, pkt + ETHERNET_HEADER_LEN, len - ETHERNET_HEADER_LEN, pq);
-    } else if(ntohs(ethh->eth_type) == ETHERNET_TYPE_PPPOE_DISC) {
+            DecodePPPOESession(tv, dtv, p, pkt + ETHERNET_HEADER_LEN,
+                               len - ETHERNET_HEADER_LEN, pq);
+            break;
+        case ETHERNET_TYPE_PPPOE_DISC:
             //printf("DecodeEthernet PPPOE Discovery\n");
-        DecodePPPOEDiscovery(tv, dtv, p, pkt + ETHERNET_HEADER_LEN, len - ETHERNET_HEADER_LEN, pq);
+            DecodePPPOEDiscovery(tv, dtv, p, pkt + ETHERNET_HEADER_LEN,
+                                 len - ETHERNET_HEADER_LEN, pq);
+            break;
+        default:
+            SCLogDebug("p %p pkt %p ether type %04x not supported", p,
+                       pkt, ntohs(ethh->eth_type));
     }
 
     return;