// Return true if we successfully sent an ARP request, false otherwise
bool IPv4Handler::resolveMac(SwitchState* state, IPAddressV4 dest) {
// need to find out our own IP and MAC addresses so that we can send the
// ARP request out. Since the request will be broadcast, there is no need to
// worry about which port to send the packet out.
// TODO: assume vrf 0 now
auto routeTable = state->getRouteTables()->getRouteTableIf(RouterID(0));
if (!routeTable) {
throw FbossError("No routing tables found");
}
auto route = routeTable->getRibV4()->longestMatch(dest);
if (!route || !route->isResolved()) {
// No way to reach dest
return false;
}
auto intfs = state->getInterfaces();
auto nhs = route->getForwardInfo().getNexthops();
for (auto nh : nhs) {
auto intf = intfs->getInterfaceIf(nh.intf);
if (intf) {
auto source = intf->getAddressToReach(nh.nexthop)->first.asV4();
auto target = route->isConnected() ? dest : nh.nexthop.asV4();
if (source == target) {
// This packet is for us. Don't send ARP requess for our own IP.
continue;
}
auto vlanID = intf->getVlanID();
auto vlan = state->getVlans()->getVlanIf(vlanID);
if (vlan) {
auto entry = vlan->getArpTable()->getEntryIf(target);
if (entry == nullptr) {
// No entry in ARP table, send ARP request
auto mac = intf->getMac();
ArpHandler::sendArpRequest(sw_, vlanID, mac, source, target);
// Notify the updater that we sent an arp request
sw_->getNeighborUpdater()->sentArpRequest(vlanID, target);
} else {
VLOG(4) << "not sending arp for " << target.str() << ", "
<< ((entry->isPending()) ? "pending " : "")
<< "entry already exists";
}
}
}
}
return true;
}
bool Interface::canReachAddress(const folly::IPAddress& dest) const {
return getAddressToReach(dest) != getAddresses().end();
}
