use bridge interface for arping if interface is in the bridge

In case of bridge kernel uses bridge MAC for regular packets.
Passing of interface source MAC instead of bridge might produce
conflicting ARP entry on other side, because same IP has bridge
MAC and at the same time interface MAC which might differ.

src/arping.c

@@ -99,21 +99,29 @@ int arping_send_arp_request(struct neigh_entry *n, char dip[])
 		return -1;
 	}
 
+	char *sifname = n->ifname;
 	char smac[20] = {0};
 	char sip[46] = {0};
 	char dmac[20] = {0};
 
-	hwaddr_ntoa(iface->macaddr, smac);
-	/* Try to find bridge IP address in order to use as source IP */
-	const char *brifname = DEFAULT_LAN_IFNAME;
-	struct local_interface *briface = hostmngr_ifname_to_interface(priv, brifname);
+	char brifname[16] = {0};
+	struct local_interface *briface = NULL;
 	bool is_brip_find = false;
+	int brifindex;
+
+	/* Try to find bridge IP address in order to use as source IP */
+	brifindex = if_isbridge_interface(n->ifname);
+	if (brifindex > 0 && if_indextoname(brifindex, brifname))
+		briface = hostmngr_ifname_to_interface(priv, brifname);
+
 	if (briface) {
 		for (int i = 0; i < briface->num_ipaddrs; i++) {
 			if (briface->ipaddrs[i].family != AF_INET)
 				continue;
 			inet_ntop(AF_INET/*ipv4 only*/, &briface->ipaddrs[i].addr, sip, sizeof(sip));
 			is_brip_find = true;
+			hwaddr_ntoa(briface->macaddr, smac);
+			sifname = brifname;
 			break;
 		}
 	}
@@ -121,12 +129,13 @@ int arping_send_arp_request(struct neigh_entry *n, char dip[])
 		dbg("Failed to find a valid IP address for brifname %s to use as source IP, "
 				"will be using 0.0.0.0\n", brifname);
 		snprintf(sip, sizeof(sip), "0.0.0.0");
+		hwaddr_ntoa(iface->macaddr, smac);
 	}
 	hwaddr_ntoa(n->macaddr, dmac);
 
 	dbg("arping to {ifname: %s, smac: %s, sip: %s, dmac: %s, dip: %s}\n",
-			n->ifname, smac, sip, dmac, dip);
-	return send_arp_request(n->ifname, smac, sip, dmac, dip);
+			sifname, smac, sip, dmac, dip);
+	return send_arp_request(sifname, smac, sip, dmac, dip);
 }
 #else
 /* Convert \x001122334455 --> "00:11:22:33:44:55" */