func Run(sm *subnet.SubnetManager, tepIface *net.Interface, tepIP net.IP, port int, ipMasq bool, ready backend.ReadyFunc) {
sn, err := acquireLease(sm, tepIP)
if err != nil {
log.Error("Failed to acquire lease: ", err)
return
}
tun, tunName, err := ip.OpenTun("rudder%d")
if err != nil {
log.Error("Failed to open TUN device: ", err)
return
}
localAddr := net.UDPAddr{
Port: port,
}
conn, err := net.ListenUDP("udp4", &localAddr)
if err != nil {
log.Error("Failed to start listening on UDP socket: ", err)
return
}
// Interface's subnet is that of the whole overlay network (e.g. /16)
// and not that of the individual host (e.g. /24)
tunNet := ip.IP4Net{
IP: sn.IP,
PrefixLen: sm.GetConfig().Network.PrefixLen,
}
// TUN MTU will be smaller b/c of encap (IP+UDP hdrs)
var mtu int
if tepIface.MTU > 0 {
mtu = tepIface.MTU - encapOverhead
} else {
log.Errorf("Failed to determine MTU for %s interface", tepIP)
return
}
err = configureIface(tunName, tunNet, mtu)
if err != nil {
return
}
if ipMasq {
err = setupIpMasq(tunNet.Network(), tunName)
if err != nil {
return
}
}
// all initialized and ready for business
log.Info("UDP encapsulation initialized")
ready(sn, mtu)
fastProxy(sm, tun, conn, tunNet.IP, uint(mtu), port)
}
func (sm *SubnetManager) allocateSubnet() (ip.IP4Net, error) {
log.Infof("Picking subnet in range %s ... %s", sm.config.SubnetMin, sm.config.SubnetMax)
var bag []ip.IP4
sn := ip.IP4Net{IP: sm.config.SubnetMin, PrefixLen: sm.config.SubnetLen}
OuterLoop:
for ; sn.IP <= sm.config.SubnetMax && len(bag) < 100; sn = sn.Next() {
for _, l := range sm.leases {
if sn.Overlaps(l.Network) {
continue OuterLoop
}
}
bag = append(bag, sn.IP)
}
if len(bag) == 0 {
return ip.IP4Net{}, errors.New("out of subnets")
} else {
i := randInt(0, len(bag))
return ip.IP4Net{IP: bag[i], PrefixLen: sm.config.SubnetLen}, nil
}
}
func setupIpMasq(ipn ip.IP4Net, iface string) error {
ipt, err := ip.NewIPTables()
if err != nil {
log.Error("Failed to setup IP Masquerade. iptables was not found")
return err
}
err = ipt.ClearChain("nat", "RUDDER")
if err != nil {
log.Error("Failed to create/clear RUDDER chain in NAT table: ", err)
return err
}
rules := [][]string{
// This rule makes sure we don't NAT traffic within overlay network (e.g. coming out of docker0)
[]string{"RUDDER", "-d", ipn.String(), "-j", "ACCEPT"},
// This rule makes sure we don't NAT multicast traffic within overlay network
[]string{"RUDDER", "-d", "224.0.0.0/4", "-j", "ACCEPT"},
// This rule will NAT everything originating from our overlay network and
[]string{"RUDDER", "!", "-o", iface, "-j", "MASQUERADE"},
// This rule will take everything coming from overlay and sent it to RUDDER chain
[]string{"POSTROUTING", "-s", ipn.String(), "-j", "RUDDER"},
}
for _, args := range rules {
log.Info("Adding iptables rule: ", strings.Join(args, " "))
err = ipt.AppendUnique("nat", args...)
if err != nil {
log.Error("Failed to insert IP masquerade rule: ", err)
return err
}
}
return nil
}
func writeSubnet(sn ip.IP4Net, mtu int) error {
// Write out the first usable IP by incrementing
// sn.IP by one
sn.IP += 1
dir, _ := path.Split(opts.subnetFile)
os.MkdirAll(dir, 0755)
f, err := os.Create(opts.subnetFile)
if err != nil {
return err
}
defer f.Close()
fmt.Fprintf(f, "RUDDER_SUBNET=%s\n", sn)
fmt.Fprintf(f, "RUDDER_MTU=%d\n", mtu)
return nil
}
func configureIface(ifname string, ipn ip.IP4Net, mtu int) error {
iface, err := net.InterfaceByName(ifname)
if err != nil {
log.Error("Failed to lookup interface ", ifname)
return err
}
n := ipn.ToIPNet()
err = netlink.NetworkLinkAddIp(iface, n.IP, n)
if err != nil {
log.Errorf("Failed to add IP address %s to %s: %s", n.IP, ifname, err)
return err
}
err = netlink.NetworkSetMTU(iface, mtu)
if err != nil {
log.Errorf("Failed to set MTU for %s: %v", ifname, err)
return err
}
err = netlink.NetworkLinkUp(iface)
if err != nil {
log.Errorf("Failed to set interface %s to UP state: %s", ifname, err)
return err
}
// explicitly add a route since there might be a route for a subnet already
// installed by Docker and then it won't get auto added
err = netlink.AddRoute(ipn.Network().String(), "", "", ifname)
if err != nil && err != syscall.EEXIST {
log.Errorf("Failed to add route (%s -> %s): %v", ipn.Network().String(), ifname, err)
return err
}
return nil
}