Use field names and sizes when accessing ARP packets
Signed-off-by: Joe Hershberger joe.hershberger@ni.com Cc: Joe Hershberger joe.hershberger@gmail.com --- Changes for v2: - Split from "Improve variable names and code readability" Changes for v3:
include/net.h | 6 ++++++ net/arp.c | 34 +++++++++++++++++----------------- 2 files changed, 23 insertions(+), 17 deletions(-)
diff --git a/include/net.h b/include/net.h index 730af4f..3bf0806 100644 --- a/include/net.h +++ b/include/net.h @@ -259,7 +259,9 @@ struct arp_hdr { # define ARP_ETHER 1 /* Ethernet hardware address */ ushort ar_pro; /* Format of protocol address */ uchar ar_hln; /* Length of hardware address */ +# define ARP_HLEN 6 uchar ar_pln; /* Length of protocol address */ +# define ARP_PLEN 4 ushort ar_op; /* Operation */ # define ARPOP_REQUEST 1 /* Request to resolve address */ # define ARPOP_REPLY 2 /* Response to previous request */ @@ -273,6 +275,10 @@ struct arp_hdr { * specific hardware/protocol combinations. */ uchar ar_data[0]; +#define ar_sha ar_data[0] +#define ar_spa ar_data[ARP_HLEN] +#define ar_tha ar_data[ARP_HLEN + ARP_PLEN] +#define ar_tpa ar_data[ARP_HLEN + ARP_PLEN + ARP_HLEN] #if 0 uchar ar_sha[]; /* Sender hardware address */ uchar ar_spa[]; /* Sender protocol address */ diff --git a/net/arp.c b/net/arp.c index d36a642..5ed875c 100644 --- a/net/arp.c +++ b/net/arp.c @@ -63,16 +63,16 @@ void ArpRequest(void)
arp->ar_hrd = htons(ARP_ETHER); arp->ar_pro = htons(PROT_IP); - arp->ar_hln = 6; - arp->ar_pln = 4; + arp->ar_hln = ARP_HLEN; + arp->ar_pln = ARP_PLEN; arp->ar_op = htons(ARPOP_REQUEST);
/* source ET addr */ - memcpy(&arp->ar_data[0], NetOurEther, 6); + memcpy(&arp->ar_sha, NetOurEther, ARP_HLEN); /* source IP addr */ - NetWriteIP((uchar *) &arp->ar_data[6], NetOurIP); + NetWriteIP(&arp->ar_spa, NetOurIP); /* dest ET addr = 0 */ - memset(&arp->ar_data[10], '\0', 6); + memset(&arp->ar_tha, 0, ARP_HLEN); if ((NetArpWaitPacketIP & NetOurSubnetMask) != (NetOurIP & NetOurSubnetMask)) { if (NetOurGatewayIP == 0) { @@ -85,7 +85,7 @@ void ArpRequest(void) NetArpWaitReplyIP = NetArpWaitPacketIP; }
- NetWriteIP((uchar *) &arp->ar_data[16], NetArpWaitReplyIP); + NetWriteIP(&arp->ar_tpa, NetArpWaitReplyIP); (void) eth_send(NetTxPacket, (pkt - NetTxPacket) + ARP_HDR_SIZE); }
@@ -139,15 +139,15 @@ void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len) return; if (ntohs(arp->ar_pro) != PROT_IP) return; - if (arp->ar_hln != 6) + if (arp->ar_hln != ARP_HLEN) return; - if (arp->ar_pln != 4) + if (arp->ar_pln != ARP_PLEN) return;
if (NetOurIP == 0) return;
- if (NetReadIP(&arp->ar_data[16]) != NetOurIP) + if (NetReadIP(&arp->ar_tpa) != NetOurIP) return;
switch (ntohs(arp->ar_op)) { @@ -157,10 +157,10 @@ void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len) pkt = (uchar *)et; pkt += NetSetEther(pkt, et->et_src, PROT_ARP); arp->ar_op = htons(ARPOP_REPLY); - memcpy(&arp->ar_data[10], &arp->ar_data[0], 6); - NetCopyIP(&arp->ar_data[16], &arp->ar_data[6]); - memcpy(&arp->ar_data[0], NetOurEther, 6); - NetCopyIP(&arp->ar_data[6], &NetOurIP); + memcpy(&arp->ar_tha, &arp->ar_sha, ARP_HLEN); + NetCopyIP(&arp->ar_tpa, &arp->ar_spa); + memcpy(&arp->ar_sha, NetOurEther, ARP_HLEN); + NetCopyIP(&arp->ar_spa, &NetOurIP); (void) eth_send((uchar *)et, (pkt - (uchar *)et) + ARP_HDR_SIZE); return; @@ -173,12 +173,12 @@ void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len) #ifdef CONFIG_KEEP_SERVERADDR if (NetServerIP == NetArpWaitPacketIP) { char buf[20]; - sprintf(buf, "%pM", arp->ar_data); + sprintf(buf, "%pM", arp->ar_sha); setenv("serveraddr", buf); } #endif
- reply_ip_addr = NetReadIP(&arp->ar_data[6]); + reply_ip_addr = NetReadIP(&arp->ar_spa);
/* matched waiting packet's address */ if (reply_ip_addr == NetArpWaitReplyIP) { @@ -187,14 +187,14 @@ void ArpReceive(struct ethernet_hdr *et, struct ip_udp_hdr *ip, int len)
/* save address for later use */ memcpy(NetArpWaitPacketMAC, - &arp->ar_data[0], 6); + &arp->ar_sha, ARP_HLEN);
#ifdef CONFIG_NETCONSOLE NetGetHandler()(0, 0, 0, 0, 0); #endif /* modify header, and transmit it */ memcpy(((struct ethernet_hdr *)NetArpWaitTxPacket)-> - et_dest, NetArpWaitPacketMAC, 6); + et_dest, NetArpWaitPacketMAC, ARP_HLEN); (void) eth_send(NetArpWaitTxPacket, NetArpWaitTxPacketSize);