1 files changed, 118 insertions, 0 deletions
diff --git a/runtime/networkdriver/utils.go b/runtime/networkdriver/utils.go
new file mode 100644
index 0000000000..0a4ef70c95
--- /dev/null
+++ b/runtime/networkdriver/utils.go
@@ -0,0 +1,118 @@
+package networkdriver
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"net"
+
+	"github.com/dotcloud/docker/pkg/netlink"
+)
+
+var (
+	networkGetRoutesFct = netlink.NetworkGetRoutes
+	ErrNoDefaultRoute   = errors.New("no default route")
+)
+
+func CheckNameserverOverlaps(nameservers []string, toCheck *net.IPNet) error {
+	if len(nameservers) > 0 {
+		for _, ns := range nameservers {
+			_, nsNetwork, err := net.ParseCIDR(ns)
+			if err != nil {
+				return err
+			}
+			if NetworkOverlaps(toCheck, nsNetwork) {
+				return ErrNetworkOverlapsWithNameservers
+			}
+		}
+	}
+	return nil
+}
+
+func CheckRouteOverlaps(toCheck *net.IPNet) error {
+	networks, err := networkGetRoutesFct()
+	if err != nil {
+		return err
+	}
+
+	for _, network := range networks {
+		if network.IPNet != nil && NetworkOverlaps(toCheck, network.IPNet) {
+			return ErrNetworkOverlaps
+		}
+	}
+	return nil
+}
+
+// Detects overlap between one IPNet and another
+func NetworkOverlaps(netX *net.IPNet, netY *net.IPNet) bool {
+	if firstIP, _ := NetworkRange(netX); netY.Contains(firstIP) {
+		return true
+	}
+	if firstIP, _ := NetworkRange(netY); netX.Contains(firstIP) {
+		return true
+	}
+	return false
+}
+
+// Calculates the first and last IP addresses in an IPNet
+func NetworkRange(network *net.IPNet) (net.IP, net.IP) {
+	var (
+		netIP   = network.IP.To4()
+		firstIP = netIP.Mask(network.Mask)
+		lastIP  = net.IPv4(0, 0, 0, 0).To4()
+	)
+
+	for i := 0; i < len(lastIP); i++ {
+		lastIP[i] = netIP[i] | ^network.Mask[i]
+	}
+	return firstIP, lastIP
+}
+
+// Given a netmask, calculates the number of available hosts
+func NetworkSize(mask net.IPMask) int32 {
+	m := net.IPv4Mask(0, 0, 0, 0)
+	for i := 0; i < net.IPv4len; i++ {
+		m[i] = ^mask[i]
+	}
+	return int32(binary.BigEndian.Uint32(m)) + 1
+}
+
+// Return the IPv4 address of a network interface
+func GetIfaceAddr(name string) (net.Addr, error) {
+	iface, err := net.InterfaceByName(name)
+	if err != nil {
+		return nil, err
+	}
+	addrs, err := iface.Addrs()
+	if err != nil {
+		return nil, err
+	}
+	var addrs4 []net.Addr
+	for _, addr := range addrs {
+		ip := (addr.(*net.IPNet)).IP
+		if ip4 := ip.To4(); len(ip4) == net.IPv4len {
+			addrs4 = append(addrs4, addr)
+		}
+	}
+	switch {
+	case len(addrs4) == 0:
+		return nil, fmt.Errorf("Interface %v has no IP addresses", name)
+	case len(addrs4) > 1:
+		fmt.Printf("Interface %v has more than 1 IPv4 address. Defaulting to using %v\n",
+			name, (addrs4[0].(*net.IPNet)).IP)
+	}
+	return addrs4[0], nil
+}
+
+func GetDefaultRouteIface() (*net.Interface, error) {
+	rs, err := networkGetRoutesFct()
+	if err != nil {
+		return nil, fmt.Errorf("unable to get routes: %v", err)
+	}
+	for _, r := range rs {
+		if r.Default {
+			return r.Iface, nil
+		}
+	}
+	return nil, ErrNoDefaultRoute
+}