treewide: Add include guards

...at the moment, just for consistency with packet.h, icmp.h,
tcp.h and udp.h.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/arp.h b/arp.h
index 6ef3736..34b15db 100644
--- a/arp.h
+++ b/arp.h
@@ -3,6 +3,9 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
+#ifndef ARP_H
+#define ARP_H
+
 /**
  * struct arpmsg - 802.2 ARP IPv4 payload
  * @sha:	Sender hardware address
@@ -18,3 +21,5 @@ struct arpmsg {
 } __attribute__((__packed__));
 
 int arp(struct ctx *c, struct pool *p);
+
+#endif /* ARP_H */