ctdb-common: Use struct ether_arp to avoid manual offset calculations

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>

diff --git a/ctdb/common/system_socket.c b/ctdb/common/system_socket.c
index c60243e9801e030e4fad3c55df013bbbb324e2f1..a6c5f5c093df331f20249614c74b47f2d838b826 100644 (file)
--- a/ctdb/common/system_socket.c
+++ b/ctdb/common/system_socket.c
@@ -198,8 +198,8 @@ static int arp_build(uint8_t *buffer,
 {
        size_t l = ARP_BUFFER_SIZE;
        struct ether_header *eh;
+       struct ether_arp *ea;
        struct arphdr *ah;
-       char *ptr;
 
        if (addr->sin_family != AF_INET) {
                return EINVAL;
@@ -216,7 +216,8 @@ static int arp_build(uint8_t *buffer,
        memcpy(eh->ether_shost, hwaddr, ETH_ALEN);
        eh->ether_type = htons(ETHERTYPE_ARP);
 
-       ah = (struct arphdr *)&buffer[sizeof(struct ether_header)];
+       ea = (struct ether_arp *)&buffer[sizeof(struct ether_header)];
+       ah = &ea->ea_hdr;
        ah->ar_hrd = htons(ARPHRD_ETHER);
        ah->ar_pro = htons(ETH_P_IP);
        ah->ar_hln = ETH_ALEN;
@@ -224,26 +225,16 @@ static int arp_build(uint8_t *buffer,
 
        if (! reply) {
                ah->ar_op  = htons(ARPOP_REQUEST);
-               ptr = (char *)&ah[1];
-               memcpy(ptr, hwaddr, ETH_ALEN);
-               ptr+=ETH_ALEN;
-               memcpy(ptr, &addr->sin_addr, 4);
-               ptr+=4;
-               memset(ptr, 0, ETH_ALEN);
-               ptr+=ETH_ALEN;
-               memcpy(ptr, &addr->sin_addr, 4);
-               ptr+=4;
+               memcpy(ea->arp_sha, hwaddr, ETH_ALEN);
+               memcpy(ea->arp_spa, &addr->sin_addr, sizeof(ea->arp_spa));
+               memset(ea->arp_tha, 0, ETH_ALEN);
+               memcpy(ea->arp_tpa, &addr->sin_addr, sizeof(ea->arp_tpa));
        } else {
                ah->ar_op  = htons(ARPOP_REPLY);
-               ptr = (char *)&ah[1];
-               memcpy(ptr, hwaddr, ETH_ALEN);
-               ptr+=ETH_ALEN;
-               memcpy(ptr, &addr->sin_addr, 4);
-               ptr+=4;
-               memcpy(ptr, hwaddr, ETH_ALEN);
-               ptr+=ETH_ALEN;
-               memcpy(ptr, &addr->sin_addr, 4);
-               ptr+=4;
+               memcpy(ea->arp_sha, hwaddr, ETH_ALEN);
+               memcpy(ea->arp_spa, &addr->sin_addr, sizeof(ea->arp_spa));
+               memcpy(ea->arp_tha, hwaddr, ETH_ALEN);
+               memcpy(ea->arp_tpa, &addr->sin_addr, sizeof(ea->arp_tpa));
        }
 
        *ether_dhost = (struct ether_addr *)eh->ether_dhost;