Golang utils.GetNameserversAsCIDR函數代碼示例

// CreateBridgeIface creates a network bridge interface on the host system with the name `ifaceName`,
// and attempts to configure it with an address which doesn't conflict with any other interface on the host.
// If it can't find an address which doesn't conflict, it will return an error.
func CreateBridgeIface(config *DaemonConfig) error {
	addrs := []string{
		// Here we don't follow the convention of using the 1st IP of the range for the gateway.
		// This is to use the same gateway IPs as the /24 ranges, which predate the /16 ranges.
		// In theory this shouldn't matter - in practice there's bound to be a few scripts relying
		// on the internal addressing or other stupid things like that.
		// The shouldn't, but hey, let's not break them unless we really have to.
		"172.17.42.1/16", // Don't use 172.16.0.0/16, it conflicts with EC2 DNS 172.16.0.23
		"10.0.42.1/16",   // Don't even try using the entire /8, that's too intrusive
		"10.1.42.1/16",
		"10.42.42.1/16",
		"172.16.42.1/24",
		"172.16.43.1/24",
		"172.16.44.1/24",
		"10.0.42.1/24",
		"10.0.43.1/24",
		"192.168.42.1/24",
		"192.168.43.1/24",
		"192.168.44.1/24",
	}

	nameservers := []string{}
	resolvConf, _ := utils.GetResolvConf()
	// we don't check for an error here, because we don't really care
	// if we can't read /etc/resolv.conf. So instead we skip the append
	// if resolvConf is nil. It either doesn't exist, or we can't read it
	// for some reason.
	if resolvConf != nil {
		nameservers = append(nameservers, utils.GetNameserversAsCIDR(resolvConf)...)
	}

	var ifaceAddr string
	if len(config.BridgeIp) != 0 {
		_, _, err := net.ParseCIDR(config.BridgeIp)
		if err != nil {
			return err
		}
		ifaceAddr = config.BridgeIp
	} else {
		for _, addr := range addrs {
			_, dockerNetwork, err := net.ParseCIDR(addr)
			if err != nil {
				return err
			}
			routes, err := netlink.NetworkGetRoutes()
			if err != nil {
				return err
			}
			if err := checkRouteOverlaps(routes, dockerNetwork); err == nil {
				if err := checkNameserverOverlaps(nameservers, dockerNetwork); err == nil {
					ifaceAddr = addr
					break
				}
			} else {
				utils.Debugf("%s: %s", addr, err)
			}
		}
	}
	if ifaceAddr == "" {
		return fmt.Errorf("Could not find a free IP address range for interface '%s'. Please configure its address manually and run 'docker -b %s'", config.BridgeIface, config.BridgeIface)
	}
	utils.Debugf("Creating bridge %s with network %s", config.BridgeIface, ifaceAddr)

	if err := createBridgeIface(config.BridgeIface); err != nil {
		return err
	}
	iface, err := net.InterfaceByName(config.BridgeIface)
	if err != nil {
		return err
	}
	ipAddr, ipNet, err := net.ParseCIDR(ifaceAddr)
	if err != nil {
		return err
	}
	if netlink.NetworkLinkAddIp(iface, ipAddr, ipNet); err != nil {
		return fmt.Errorf("Unable to add private network: %s", err)
	}
	if err := netlink.NetworkLinkUp(iface); err != nil {
		return fmt.Errorf("Unable to start network bridge: %s", err)
	}

	return nil
}

// CreateBridgeIface creates a network bridge interface on the host system with the name `ifaceName`,
// and attempts to configure it with an address which doesn't conflict with any other interface on the host.
// If it can't find an address which doesn't conflict, it will return an error.
func CreateBridgeIface(config *DaemonConfig) error {
	addrs := []string{
		// Here we don't follow the convention of using the 1st IP of the range for the gateway.
		// This is to use the same gateway IPs as the /24 ranges, which predate the /16 ranges.
		// In theory this shouldn't matter - in practice there's bound to be a few scripts relying
		// on the internal addressing or other stupid things like that.
		// The shouldn't, but hey, let's not break them unless we really have to.
		"172.17.42.1/16", // Don't use 172.16.0.0/16, it conflicts with EC2 DNS 172.16.0.23
		"10.0.42.1/16",   // Don't even try using the entire /8, that's too intrusive
		"10.1.42.1/16",
		"10.42.42.1/16",
		"172.16.42.1/24",
		"172.16.43.1/24",
		"172.16.44.1/24",
		"10.0.42.1/24",
		"10.0.43.1/24",
		"192.168.42.1/24",
		"192.168.43.1/24",
		"192.168.44.1/24",
	}

	nameservers := []string{}
	resolvConf, _ := utils.GetResolvConf()
	// we don't check for an error here, because we don't really care
	// if we can't read /etc/resolv.conf. So instead we skip the append
	// if resolvConf is nil. It either doesn't exist, or we can't read it
	// for some reason.
	if resolvConf != nil {
		nameservers = append(nameservers, utils.GetNameserversAsCIDR(resolvConf)...)
	}

	var ifaceAddr string
	for _, addr := range addrs {
		_, dockerNetwork, err := net.ParseCIDR(addr)
		if err != nil {
			return err
		}
		routes, err := netlink.NetworkGetRoutes()
		if err != nil {
			return err
		}
		if err := checkRouteOverlaps(routes, dockerNetwork); err == nil {
			if err := checkNameserverOverlaps(nameservers, dockerNetwork); err == nil {
				ifaceAddr = addr
				break
			}
		} else {
			utils.Debugf("%s: %s", addr, err)
		}
	}
	if ifaceAddr == "" {
		return fmt.Errorf("Could not find a free IP address range for interface '%s'. Please configure its address manually and run 'docker -b %s'", config.BridgeIface, config.BridgeIface)
	}
	utils.Debugf("Creating bridge %s with network %s", config.BridgeIface, ifaceAddr)

	if err := netlink.NetworkLinkAdd(config.BridgeIface, "bridge"); err != nil {
		return fmt.Errorf("Error creating bridge: %s", err)
	}
	iface, err := net.InterfaceByName(config.BridgeIface)
	if err != nil {
		return err
	}
	ipAddr, ipNet, err := net.ParseCIDR(ifaceAddr)
	if err != nil {
		return err
	}
	if netlink.NetworkLinkAddIp(iface, ipAddr, ipNet); err != nil {
		return fmt.Errorf("Unable to add private network: %s", err)
	}
	if err := netlink.NetworkLinkUp(iface); err != nil {
		return fmt.Errorf("Unable to start network bridge: %s", err)
	}

	if config.EnableIptables {
		// Enable NAT
		if output, err := iptables.Raw("-t", "nat", "-A", "POSTROUTING", "-s", ifaceAddr,
			"!", "-d", ifaceAddr, "-j", "MASQUERADE"); err != nil {
			return fmt.Errorf("Unable to enable network bridge NAT: %s", err)
		} else if len(output) != 0 {
			return fmt.Errorf("Error iptables postrouting: %s", output)
		}

		// Accept incoming packets for existing connections
		if output, err := iptables.Raw("-I", "FORWARD", "-o", config.BridgeIface, "-m", "conntrack", "--ctstate", "RELATED,ESTABLISHED", "-j", "ACCEPT"); err != nil {
			return fmt.Errorf("Unable to allow incoming packets: %s", err)
		} else if len(output) != 0 {
			return fmt.Errorf("Error iptables allow incoming: %s", output)
		}

		// Accept all non-intercontainer outgoing packets
		if output, err := iptables.Raw("-I", "FORWARD", "-i", config.BridgeIface, "!", "-o", config.BridgeIface, "-j", "ACCEPT"); err != nil {
			return fmt.Errorf("Unable to allow outgoing packets: %s", err)
		} else if len(output) != 0 {
			return fmt.Errorf("Error iptables allow outgoing: %s", output)
		}

	}
//.........這裏部分代碼省略.........

// CreateBridgeIface creates a network bridge interface on the host system with the name `ifaceName`,
// and attempts to configure it with an address which doesn't conflict with any other interface on the host.
// If it can't find an address which doesn't conflict, it will return an error.
func createBridge(bridgeIP string) error {
	nameservers := []string{}
	resolvConf, _ := utils.GetResolvConf()
	// we don't check for an error here, because we don't really care
	// if we can't read /etc/resolv.conf. So instead we skip the append
	// if resolvConf is nil. It either doesn't exist, or we can't read it
	// for some reason.
	if resolvConf != nil {
		nameservers = append(nameservers, utils.GetNameserversAsCIDR(resolvConf)...)
	}

	var ifaceAddr string
	if len(bridgeIP) != 0 {
		_, _, err := net.ParseCIDR(bridgeIP)
		if err != nil {
			return err
		}
		ifaceAddr = bridgeIP
	} else {
		for _, addr := range addrs {
			_, dockerNetwork, err := net.ParseCIDR(addr)
			if err != nil {
				return err
			}
			if err := networkdriver.CheckNameserverOverlaps(nameservers, dockerNetwork); err == nil {
				if err := networkdriver.CheckRouteOverlaps(dockerNetwork); err == nil {
					ifaceAddr = addr
					break
				} else {
					utils.Debugf("%s %s", addr, err)
				}
			}
		}
	}

	if ifaceAddr == "" {
		return fmt.Errorf("Could not find a free IP address range for interface '%s'. Please configure its address manually and run 'docker -b %s'", bridgeIface, bridgeIface)
	}
	utils.Debugf("Creating bridge %s with network %s", bridgeIface, ifaceAddr)

	if err := createBridgeIface(bridgeIface); err != nil {
		return err
	}

	iface, err := net.InterfaceByName(bridgeIface)
	if err != nil {
		return err
	}

	ipAddr, ipNet, err := net.ParseCIDR(ifaceAddr)
	if err != nil {
		return err
	}

	if netlink.NetworkLinkAddIp(iface, ipAddr, ipNet); err != nil {
		return fmt.Errorf("Unable to add private network: %s", err)
	}
	if err := netlink.NetworkLinkUp(iface); err != nil {
		return fmt.Errorf("Unable to start network bridge: %s", err)
	}
	return nil
}