flow_dissector: Move ARP dissection into a separate function

Make the main flow_dissect function a bit smaller and move the ARP
dissection into a separate function. Along with that, do the ARP header
processing only in case the flow dissection user requires it.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index c35aae1..d79fb8f 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -113,6 +113,66 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
 }
 EXPORT_SYMBOL(__skb_flow_get_ports);
 
+enum flow_dissect_ret {
+       FLOW_DISSECT_RET_OUT_GOOD,
+       FLOW_DISSECT_RET_OUT_BAD,
+};
+
+static enum flow_dissect_ret
+__skb_flow_dissect_arp(const struct sk_buff *skb,
+                      struct flow_dissector *flow_dissector,
+                      void *target_container, void *data, int nhoff, int hlen)
+{
+       struct flow_dissector_key_arp *key_arp;
+       struct {
+               unsigned char ar_sha[ETH_ALEN];
+               unsigned char ar_sip[4];
+               unsigned char ar_tha[ETH_ALEN];
+               unsigned char ar_tip[4];
+       } *arp_eth, _arp_eth;
+       const struct arphdr *arp;
+       struct arphdr *_arp;
+
+       if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ARP))
+               return FLOW_DISSECT_RET_OUT_GOOD;
+
+       arp = __skb_header_pointer(skb, nhoff, sizeof(_arp), data,
+                                  hlen, &_arp);
+       if (!arp)
+               return FLOW_DISSECT_RET_OUT_BAD;
+
+       if (arp->ar_hrd != htons(ARPHRD_ETHER) ||
+           arp->ar_pro != htons(ETH_P_IP) ||
+           arp->ar_hln != ETH_ALEN ||
+           arp->ar_pln != 4 ||
+           (arp->ar_op != htons(ARPOP_REPLY) &&
+            arp->ar_op != htons(ARPOP_REQUEST)))
+               return FLOW_DISSECT_RET_OUT_BAD;
+
+       arp_eth = __skb_header_pointer(skb, nhoff + sizeof(_arp),
+                                      sizeof(_arp_eth), data,
+                                      hlen, &_arp_eth);
+       if (!arp_eth)
+               return FLOW_DISSECT_RET_OUT_BAD;
+
+       key_arp = skb_flow_dissector_target(flow_dissector,
+                                           FLOW_DISSECTOR_KEY_ARP,
+                                           target_container);
+
+       memcpy(&key_arp->sip, arp_eth->ar_sip, sizeof(key_arp->sip));
+       memcpy(&key_arp->tip, arp_eth->ar_tip, sizeof(key_arp->tip));
+
+       /* Only store the lower byte of the opcode;
+        * this covers ARPOP_REPLY and ARPOP_REQUEST.
+        */
+       key_arp->op = ntohs(arp->ar_op) & 0xff;
+
+       ether_addr_copy(key_arp->sha, arp_eth->ar_sha);
+       ether_addr_copy(key_arp->tha, arp_eth->ar_tha);
+
+       return FLOW_DISSECT_RET_OUT_GOOD;
+}
+
 /**
  * __skb_flow_dissect - extract the flow_keys struct and return it
  * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified
@@ -138,7 +198,6 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
        struct flow_dissector_key_control *key_control;
        struct flow_dissector_key_basic *key_basic;
        struct flow_dissector_key_addrs *key_addrs;
-       struct flow_dissector_key_arp *key_arp;
        struct flow_dissector_key_ports *key_ports;
        struct flow_dissector_key_icmp *key_icmp;
        struct flow_dissector_key_tags *key_tags;
@@ -382,60 +441,15 @@ mpls:
                goto out_good;
 
        case htons(ETH_P_ARP):
-       case htons(ETH_P_RARP): {
-               struct {
-                       unsigned char ar_sha[ETH_ALEN];
-                       unsigned char ar_sip[4];
-                       unsigned char ar_tha[ETH_ALEN];
-                       unsigned char ar_tip[4];
-               } *arp_eth, _arp_eth;
-               const struct arphdr *arp;
-               struct arphdr *_arp;
-
-               arp = __skb_header_pointer(skb, nhoff, sizeof(_arp), data,
-                                          hlen, &_arp);
-               if (!arp)
-                       goto out_bad;
-
-               if (arp->ar_hrd != htons(ARPHRD_ETHER) ||
-                   arp->ar_pro != htons(ETH_P_IP) ||
-                   arp->ar_hln != ETH_ALEN ||
-                   arp->ar_pln != 4 ||
-                   (arp->ar_op != htons(ARPOP_REPLY) &&
-                    arp->ar_op != htons(ARPOP_REQUEST)))
-                       goto out_bad;
-
-               arp_eth = __skb_header_pointer(skb, nhoff + sizeof(_arp),
-                                              sizeof(_arp_eth), data,
-                                              hlen,
-                                              &_arp_eth);
-               if (!arp_eth)
+       case htons(ETH_P_RARP):
+               switch (__skb_flow_dissect_arp(skb, flow_dissector,
+                                              target_container, data,
+                                              nhoff, hlen)) {
+               case FLOW_DISSECT_RET_OUT_GOOD:
+                       goto out_good;
+               case FLOW_DISSECT_RET_OUT_BAD:
                        goto out_bad;
-
-               if (dissector_uses_key(flow_dissector,
-                                      FLOW_DISSECTOR_KEY_ARP)) {
-
-                       key_arp = skb_flow_dissector_target(flow_dissector,
-                                                           FLOW_DISSECTOR_KEY_ARP,
-                                                           target_container);
-
-                       memcpy(&key_arp->sip, arp_eth->ar_sip,
-                              sizeof(key_arp->sip));
-                       memcpy(&key_arp->tip, arp_eth->ar_tip,
-                              sizeof(key_arp->tip));
-
-                       /* Only store the lower byte of the opcode;
-                        * this covers ARPOP_REPLY and ARPOP_REQUEST.
-                        */
-                       key_arp->op = ntohs(arp->ar_op) & 0xff;
-
-                       ether_addr_copy(key_arp->sha, arp_eth->ar_sha);
-                       ether_addr_copy(key_arp->tha, arp_eth->ar_tha);
                }
-
-               goto out_good;
-       }
-
        default:
                goto out_bad;
        }