send gratuitous arp on refresh cycles

diff --git a/main.c b/main.c
index c30526ef2cdd9963531f044ceaac09538d5f742d..e677f49ba2a5770e93e79aa0b7ae271fa31e77ff 100644 (file)
--- 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)