net: Add net_update_ether() to handle ARP and Ping replies

When the network is VLAN or SNAP, net_update_ether() will preserve
the original Ethernet packet header and simply replace the src and
dest MACs and the protocol

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Simon Glass <sjg@chromium.org>

include/net.h

@@ -449,6 +449,7 @@ extern int	NetEthHdrSize(void);
 
 /* Set ethernet header; returns the size of the header */
 extern int NetSetEther(uchar *, uchar *, uint);
+extern int net_update_ether(struct ethernet_hdr *et, uchar *addr, uint prot);
 
 /* Set IP header */
 extern void net_set_ip_header(uchar *pkt, IPaddr_t dest, IPaddr_t source);

net/arp.c

@@ -158,7 +158,7 @@ void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 		/* reply with our IP address */
 		debug("Got ARP REQUEST, return our IP\n");
 		pkt = (uchar *)et;
-		eth_hdr_size = NetSetEther(pkt, et->et_src, PROT_ARP);
+		eth_hdr_size = net_update_ether(et, et->et_src, PROT_ARP);
 		pkt += eth_hdr_size;
 		arp->ar_op = htons(ARPOP_REPLY);
 		memcpy(&arp->ar_tha, &arp->ar_sha, ARP_HLEN);

net/net.c

@@ -1276,6 +1276,29 @@ NetSetEther(uchar *xet, uchar * addr, uint prot)
 	}
 }
 
+int net_update_ether(struct ethernet_hdr *et, uchar *addr, uint prot)
+{
+	ushort protlen;
+
+	memcpy(et->et_dest, addr, 6);
+	memcpy(et->et_src, NetOurEther, 6);
+	protlen = ntohs(et->et_protlen);
+	if (protlen == PROT_VLAN) {
+		struct vlan_ethernet_hdr *vet =
+			(struct vlan_ethernet_hdr *)et;
+		vet->vet_type = htons(prot);
+		return VLAN_ETHER_HDR_SIZE;
+	} else if (protlen > 1514) {
+		et->et_protlen = htons(prot);
+		return ETHER_HDR_SIZE;
+	} else {
+		/* 802.2 + SNAP */
+		struct e802_hdr *et802 = (struct e802_hdr *)et;
+		et802->et_prot = htons(prot);
+		return E802_HDR_SIZE;
+	}
+}
+
 void net_set_ip_header(uchar *pkt, IPaddr_t dest, IPaddr_t source)
 {
 	struct ip_udp_hdr *ip = (struct ip_udp_hdr *)pkt;

net/ping.c

@@ -87,6 +87,7 @@ void ping_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 {
 	struct icmp_hdr *icmph = (struct icmp_hdr *)&ip->udp_src;
 	IPaddr_t src_ip;
+	int eth_hdr_size;
 
 	switch (icmph->type) {
 	case ICMP_ECHO_REPLY:
@@ -95,11 +96,10 @@ void ping_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 			net_set_state(NETLOOP_SUCCESS);
 		return;
 	case ICMP_ECHO_REQUEST:
-		debug("Got ICMP ECHO REQUEST, return "
-			"%d bytes\n", ETHER_HDR_SIZE + len);
+		eth_hdr_size = net_update_ether(et, et->et_src, PROT_IP);
 
-		memcpy(&et->et_dest[0], &et->et_src[0], 6);
-		memcpy(&et->et_src[0], NetOurEther, 6);
+		debug("Got ICMP ECHO REQUEST, return "
+			"%d bytes\n", eth_hdr_size + len);
 
 		ip->ip_sum = 0;
 		ip->ip_off = 0;
@@ -112,7 +112,7 @@ void ping_receive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
 		icmph->checksum = 0;
 		icmph->checksum = ~NetCksum((uchar *)icmph,
 			(len - IP_HDR_SIZE) >> 1);
-		NetSendPacket((uchar *)et, ETHER_HDR_SIZE + len);
+		NetSendPacket((uchar *)et, eth_hdr_size + len);
 		return;
 /*	default:
 		return;*/