// Retrieve the MX records for miek.nl. func ExampleMX() { config, _ := dns.ClientConfigFromFile("/etc/resolv.conf") c := new(dns.Client) m := new(dns.Msg) m.SetQuestion("miek.nl.", dns.TypeMX) m.RecursionDesired = true r, _, err := c.Exchange(m, config.Servers[0]+":"+config.Port) if err != nil { return } if r.Rcode != dns.RcodeSuccess { return } for _, a := range r.Answer { if mx, ok := a.(*dns.MX); ok { fmt.Printf("%s\n", mx.String()) } } }
// Retrieve the DNSKEY records of a zone and convert them // to DS records for SHA1, SHA256 and SHA384. func ExampleDS(zone string) { config, _ := dns.ClientConfigFromFile("/etc/resolv.conf") c := new(dns.Client) m := new(dns.Msg) if zone == "" { zone = "miek.nl" } m.SetQuestion(dns.Fqdn(zone), dns.TypeDNSKEY) m.SetEdns0(4096, true) r, _, err := c.Exchange(m, config.Servers[0]+":"+config.Port) if err != nil { return } if r.Rcode != dns.RcodeSuccess { return } for _, k := range r.Answer { if key, ok := k.(*dns.DNSKEY); ok { for _, alg := range []uint8{dns.SHA1, dns.SHA256, dns.SHA384} { fmt.Printf("%s; %d\n", key.ToDS(alg).String(), key.Flags) } } } }
// ConfigureNetworking is called once during host startup and passed the // strategy and identifier of the networking coordinatior job. Currently the // only strategy implemented uses flannel. func (l *LibvirtLXCBackend) ConfigureNetworking(config *host.NetworkConfig) error { var err error l.bridgeAddr, l.bridgeNet, err = net.ParseCIDR(config.Subnet) if err != nil { return err } l.ipalloc.RequestIP(l.bridgeNet, l.bridgeAddr) err = netlink.CreateBridge(bridgeName, false) bridgeExists := os.IsExist(err) if err != nil && !bridgeExists { return err } bridge, err := net.InterfaceByName(bridgeName) if err != nil { return err } if !bridgeExists { // We need to explicitly assign the MAC address to avoid it changing to a lower value // See: https://github.com/flynn/flynn/issues/223 b := random.Bytes(5) bridgeMAC := fmt.Sprintf("fe:%02x:%02x:%02x:%02x:%02x", b[0], b[1], b[2], b[3], b[4]) if err := netlink.NetworkSetMacAddress(bridge, bridgeMAC); err != nil { return err } } currAddrs, err := bridge.Addrs() if err != nil { return err } setIP := true for _, addr := range currAddrs { ip, net, _ := net.ParseCIDR(addr.String()) if ip.Equal(l.bridgeAddr) && net.String() == l.bridgeNet.String() { setIP = false } else { if err := netlink.NetworkLinkDelIp(bridge, ip, net); err != nil { return err } } } if setIP { if err := netlink.NetworkLinkAddIp(bridge, l.bridgeAddr, l.bridgeNet); err != nil { return err } } if err := netlink.NetworkLinkUp(bridge); err != nil { return err } network, err := l.libvirt.LookupNetworkByName(libvirtNetName) if err != nil { // network doesn't exist networkConfig := <.Network{ Name: libvirtNetName, Bridge: lt.Bridge{Name: bridgeName}, Forward: lt.Forward{Mode: "bridge"}, } network, err = l.libvirt.NetworkDefineXML(string(networkConfig.XML())) if err != nil { return err } } active, err := network.IsActive() if err != nil { return err } if !active { if err := network.Create(); err != nil { return err } } if defaultNet, err := l.libvirt.LookupNetworkByName("default"); err == nil { // The default network causes dnsmasq to run and bind to all interfaces, // including ours. This prevents discoverd from binding its DNS server. // We don't use it, so destroy it if it exists. defaultNet.Destroy() } // enable IP forwarding if err := ioutil.WriteFile("/proc/sys/net/ipv4/ip_forward", []byte("1\n"), 0644); err != nil { return err } // Set up iptables for outbound traffic masquerading from containers to the // rest of the network. if err := iptables.EnableOutboundNAT(bridgeName, l.bridgeNet.String()); err != nil { return err } // Read DNS config, discoverd uses the nameservers dnsConf, err := dns.ClientConfigFromFile("/etc/resolv.conf") if err != nil { return err } config.Resolvers = dnsConf.Servers // Write a resolv.conf to be bind-mounted into containers pointing at the // future discoverd DNS listener if err := os.MkdirAll("/etc/flynn", 0755); err != nil { return err } var resolvSearch string if len(dnsConf.Search) > 0 { resolvSearch = fmt.Sprintf("search %s\n", strings.Join(dnsConf.Search, " ")) } if err := ioutil.WriteFile("/etc/flynn/resolv.conf", []byte(fmt.Sprintf("%snameserver %s\n", resolvSearch, l.bridgeAddr.String())), 0644); err != nil { return err } l.resolvConf = "/etc/flynn/resolv.conf" // Allocate IPs for running jobs for i, container := range l.containers { if !container.job.Config.HostNetwork { var err error l.containers[i].IP, err = l.ipalloc.RequestIP(l.bridgeNet, container.IP) if err != nil { grohl.Log(grohl.Data{"fn": "ConfigureNetworking", "at": "request_ip", "status": "error", "err": err}) } } } close(l.networkConfigured) return nil }