Make ipamutils compile for windows

currently ipamutils package uses apis which are linux
specific and makes windows compile error out. Separated
the OS specific apis into linux and windows files to
diverge the implementation.

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

libnetwork/ipamutils/utils.go

@@ -1,14 +1,7 @@
 // Package ipamutils provides utililty functions for ipam management
 package ipamutils
 
-import (
-	"fmt"
-	"net"
-
-	"github.com/docker/libnetwork/netutils"
-	"github.com/docker/libnetwork/resolvconf"
-	"github.com/vishvananda/netlink"
-)
+import "net"
 
 var (
 	// PredefinedBroadNetworks contains a list of 31 IPv4 private networks with host size 16 and 12
@@ -24,66 +17,6 @@ func init() {
 	PredefinedGranularNetworks = initGranularPredefinedNetworks()
 }
 
-// ElectInterfaceAddresses looks for an interface on the OS with the specified name
-// and returns its IPv4 and IPv6 addresses in CIDR form. If the interface does not exist,
-// it chooses from a predifined list the first IPv4 address which does not conflict
-// with other interfaces on the system.
-func ElectInterfaceAddresses(name string) (*net.IPNet, []*net.IPNet, error) {
-	var (
-		v4Net  *net.IPNet
-		v6Nets []*net.IPNet
-		err    error
-	)
-
-	link, _ := netlink.LinkByName(name)
-	if link != nil {
-		v4addr, err := netlink.AddrList(link, netlink.FAMILY_V4)
-		if err != nil {
-			return nil, nil, err
-		}
-		v6addr, err := netlink.AddrList(link, netlink.FAMILY_V6)
-		if err != nil {
-			return nil, nil, err
-		}
-		if len(v4addr) > 0 {
-			v4Net = v4addr[0].IPNet
-		}
-		for _, nlAddr := range v6addr {
-			v6Nets = append(v6Nets, nlAddr.IPNet)
-		}
-	}
-
-	if link == nil || v4Net == nil {
-		// Choose from predifined broad networks
-		v4Net, err = FindAvailableNetwork(PredefinedBroadNetworks)
-		if err != nil {
-			return nil, nil, err
-		}
-	}
-
-	return v4Net, v6Nets, nil
-}
-
-// FindAvailableNetwork returns a network from the passed list which does not
-// overlap with existing interfaces in the system
-func FindAvailableNetwork(list []*net.IPNet) (*net.IPNet, error) {
-	// 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.
-	var nameservers []string
-	if rc, err := resolvconf.Get(); err == nil {
-		nameservers = resolvconf.GetNameserversAsCIDR(rc.Content)
-	}
-	for _, nw := range list {
-		if err := netutils.CheckNameserverOverlaps(nameservers, nw); err == nil {
-			if err := netutils.CheckRouteOverlaps(nw); err == nil {
-				return nw, nil
-			}
-		}
-	}
-	return nil, fmt.Errorf("no available network")
-}
-
 func initBroadPredefinedNetworks() []*net.IPNet {
 	pl := make([]*net.IPNet, 0, 31)
 	mask := []byte{255, 255, 0, 0}

libnetwork/ipamutils/utils_linux.go

@@ -0,0 +1,71 @@
+// Package ipamutils provides utililty functions for ipam management
+package ipamutils
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/docker/libnetwork/netutils"
+	"github.com/docker/libnetwork/resolvconf"
+	"github.com/vishvananda/netlink"
+)
+
+// ElectInterfaceAddresses looks for an interface on the OS with the specified name
+// and returns its IPv4 and IPv6 addresses in CIDR form. If the interface does not exist,
+// it chooses from a predifined list the first IPv4 address which does not conflict
+// with other interfaces on the system.
+func ElectInterfaceAddresses(name string) (*net.IPNet, []*net.IPNet, error) {
+	var (
+		v4Net  *net.IPNet
+		v6Nets []*net.IPNet
+		err    error
+	)
+
+	link, _ := netlink.LinkByName(name)
+	if link != nil {
+		v4addr, err := netlink.AddrList(link, netlink.FAMILY_V4)
+		if err != nil {
+			return nil, nil, err
+		}
+		v6addr, err := netlink.AddrList(link, netlink.FAMILY_V6)
+		if err != nil {
+			return nil, nil, err
+		}
+		if len(v4addr) > 0 {
+			v4Net = v4addr[0].IPNet
+		}
+		for _, nlAddr := range v6addr {
+			v6Nets = append(v6Nets, nlAddr.IPNet)
+		}
+	}
+
+	if link == nil || v4Net == nil {
+		// Choose from predifined broad networks
+		v4Net, err = FindAvailableNetwork(PredefinedBroadNetworks)
+		if err != nil {
+			return nil, nil, err
+		}
+	}
+
+	return v4Net, v6Nets, nil
+}
+
+// FindAvailableNetwork returns a network from the passed list which does not
+// overlap with existing interfaces in the system
+func FindAvailableNetwork(list []*net.IPNet) (*net.IPNet, error) {
+	// 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.
+	var nameservers []string
+	if rc, err := resolvconf.Get(); err == nil {
+		nameservers = resolvconf.GetNameserversAsCIDR(rc.Content)
+	}
+	for _, nw := range list {
+		if err := netutils.CheckNameserverOverlaps(nameservers, nw); err == nil {
+			if err := netutils.CheckRouteOverlaps(nw); err == nil {
+				return nw, nil
+			}
+		}
+	}
+	return nil, fmt.Errorf("no available network")
+}

libnetwork/ipamutils/utils_windows.go

@@ -0,0 +1,22 @@
+// Package ipamutils provides utililty functions for ipam management
+package ipamutils
+
+import (
+	"net"
+
+	"github.com/docker/libnetwork/types"
+)
+
+// ElectInterfaceAddresses looks for an interface on the OS with the specified name
+// and returns its IPv4 and IPv6 addresses in CIDR form. If the interface does not exist,
+// it chooses from a predifined list the first IPv4 address which does not conflict
+// with other interfaces on the system.
+func ElectInterfaceAddresses(name string) (*net.IPNet, []*net.IPNet, error) {
+	return nil, nil, types.NotImplementedErrorf("not supported on windows")
+}
+
+// FindAvailableNetwork returns a network from the passed list which does not
+// overlap with existing interfaces in the system
+func FindAvailableNetwork(list []*net.IPNet) (*net.IPNet, error) {
+	return nil, types.NotImplementedErrorf("not supported on windows")
+}