From 3771bad14d2423062f8ae6ef8734b52182618e92 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Fri, 27 Aug 2010 21:30:50 +0200
Subject: [PATCH] send gratuitous arp on refresh cycles
---
main.c | 39 ++++++++++++++++++++++++++++++---------
1 file changed, 30 insertions(+), 9 deletions(-)
diff --git a/main.c b/main.c
index c30526e..e677f49 100644
--- a/main.c
+++ b/main.c
@@ -138,7 +138,7 @@ static void del_host(struct relayd_host *host)
free(host);
}
-static void fill_arp_request(struct arp_packet *pkt, struct relayd_interface *rif,
+static void fill_arp_packet(struct arp_packet *pkt, struct relayd_interface *rif,
const uint8_t spa[4], const uint8_t tpa[4])
{
memset(pkt, 0, sizeof(*pkt));
@@ -160,7 +160,7 @@ static void send_arp_request(struct relayd_interface *rif, const uint8_t *ipaddr
{
struct arp_packet pkt;
- fill_arp_request(&pkt, rif, rif->src_ip, ipaddr);
+ fill_arp_packet(&pkt, rif, rif->src_ip, ipaddr);
pkt.arp.arp_op = htons(ARPOP_REQUEST);
memcpy(pkt.arp.arp_spa, rif->src_ip, ETH_ALEN);
@@ -210,15 +210,24 @@ static void send_arp_reply(struct relayd_interface *rif, uint8_t spa[4],
{
struct arp_packet pkt;
- fill_arp_request(&pkt, rif, spa, tpa);
+ fill_arp_packet(&pkt, rif, spa, tpa);
pkt.arp.arp_op = htons(ARPOP_REPLY);
- memcpy(pkt.eth.ether_dhost, tha, ETH_ALEN);
- memcpy(pkt.arp.arp_tha, tha, ETH_ALEN);
+ if (tha) {
+ memcpy(pkt.eth.ether_dhost, tha, ETH_ALEN);
+ memcpy(pkt.arp.arp_tha, tha, ETH_ALEN);
- DPRINTF(2, "%s: sending ARP reply to "IP_FMT", "IP_FMT" is at ("MAC_FMT")\n",
- rif->ifname, IP_BUF(pkt.arp.arp_tpa),
- IP_BUF(pkt.arp.arp_spa), MAC_BUF(pkt.eth.ether_shost));
+ DPRINTF(2, "%s: sending ARP reply to "IP_FMT", "IP_FMT" is at ("MAC_FMT")\n",
+ rif->ifname, IP_BUF(pkt.arp.arp_tpa),
+ IP_BUF(pkt.arp.arp_spa), MAC_BUF(pkt.eth.ether_shost));
+ } else {
+ memset(pkt.eth.ether_dhost, 0xff, ETH_ALEN);
+ memset(pkt.arp.arp_tha, 0, ETH_ALEN);
+
+ DPRINTF(2, "%s: sending gratuitous ARP: "IP_FMT" is at ("MAC_FMT")\n",
+ rif->ifname, IP_BUF(pkt.arp.arp_tpa),
+ MAC_BUF(pkt.eth.ether_shost));
+ }
sendto(rif->fd.fd, &pkt, sizeof(pkt), 0,
(struct sockaddr *) &rif->sll, sizeof(rif->sll));
@@ -369,6 +378,7 @@ static void recv_arp_request(struct relayd_interface *rif, struct arp_packet *pk
static void recv_arp_reply(struct relayd_interface *rif, struct arp_packet *pkt)
{
+ struct relayd_interface *to_rif;
struct relayd_host *host;
DPRINTF(2, "%s: received ARP reply for "IP_FMT" from "MAC_FMT", deliver to "IP_FMT"\n",
@@ -380,8 +390,19 @@ static void recv_arp_reply(struct relayd_interface *rif, struct arp_packet *pkt)
if (memcmp(pkt->arp.arp_sha, rif->sll.sll_addr, ETH_ALEN) != 0)
relayd_refresh_host(rif, pkt->arp.arp_sha, pkt->arp.arp_spa);
- if (!memcmp(pkt->arp.arp_tpa, rif->src_ip, 4))
+ if (!memcmp(pkt->arp.arp_tpa, rif->src_ip, 4)) {
+ /*
+ * locally initiated lookup, relay as gratuitous ARP
+ * to all other interfaces
+ */
+ list_for_each_entry(to_rif, &interfaces, list) {
+ if (rif == to_rif)
+ continue;
+
+ send_arp_reply(to_rif, pkt->arp.arp_spa, NULL, pkt->arp.arp_spa);
+ }
return;
+ }
host = find_host_by_ipaddr(NULL, pkt->arp.arp_tpa);
if (!host)
--
2.25.1