network: move ipmasq management into platform-specific files

First part of changes to get flannel building/running on Windows

main.go

@@ -28,7 +28,6 @@ import (
 	"strings"
 	"syscall"
 
-	"github.com/coreos/go-iptables/iptables"
 	"github.com/coreos/pkg/flagutil"
 	log "github.com/golang/glog"
 	"golang.org/x/net/context"
@@ -285,7 +284,7 @@ func main() {
 
 	// Set up ipMasq if needed
 	if opts.ipMasq {
-		go setupIPMasq(config, bn)
+		go network.SetupAndEnsureIPMasq(config.Network, bn.Lease())
 	}
 
 	if err := WriteSubnetFile(opts.subnetFile, config.Network, opts.ipMasq, bn); err != nil {
@@ -553,26 +552,6 @@ func mustRunHealthz() {
 	}
 }
 
-func setupIPMasq(config *subnet.Config, bn backend.Network) {
-	ipt, err := iptables.New()
-	if err != nil {
-		// if we can't find iptables, give up and return
-		log.Errorf("Failed to set up IP Masquerade. iptables was not found: %v", err)
-		return
-	}
-	defer func() {
-		network.TeardownIPMasq(ipt, config.Network, bn.Lease())
-	}()
-	for {
-		// Ensure that all the rules exist every 5 seconds
-		if err := network.EnsureIPMasq(ipt, config.Network, bn.Lease()); err != nil {
-			log.Errorf("Failed to ensure IP Masquerade: %v", err)
-		}
-		time.Sleep(5 * time.Second)
-	}
-
-}
-
 func ReadSubnetFromSubnetFile(path string) ip.IP4Net {
 	var prevSubnet ip.IP4Net
 	if _, err := os.Stat(path); !os.IsNotExist(err) {

network/ipmasq.go

@@ -1,3 +1,5 @@
+// +build linux
+
 // Copyright 2015 flannel authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
@@ -22,6 +24,8 @@ import (
 
 	"github.com/coreos/flannel/pkg/ip"
 	"github.com/coreos/flannel/subnet"
+	"github.com/coreos/go-iptables/iptables"
+	"time"
 )
 
 type IPTablesRules interface {
@@ -61,6 +65,28 @@ func ipMasqRulesExist(ipt IPTablesRules, ipn ip.IP4Net, lease *subnet.Lease) (bo
 	return true, nil
 }
 
+func SetupAndEnsureIPMasq(network ip.IP4Net, lease *subnet.Lease) {
+	ipt, err := iptables.New()
+	if err != nil {
+		// if we can't find iptables, give up and return
+		log.Errorf("Failed to setup IP Masquerade.  IPTables was not found: %v", err)
+		return
+	}
+
+	defer func() {
+		TeardownIPMasq(ipt, network, lease)
+	}()
+
+	for {
+		// Ensure that all the rules exist every 5 seconds
+		if err := EnsureIPMasq(ipt, network, lease); err != nil {
+			log.Errorf("Failed to ensure IP Masquerade: %v", err)
+		}
+
+		time.Sleep(5 * time.Second)
+	}
+}
+
 func EnsureIPMasq(ipt IPTablesRules, ipn ip.IP4Net, lease *subnet.Lease) error {
 	exists, err := ipMasqRulesExist(ipt, ipn, lease)
 	if err != nil {

network/ipmasq_unspecified.go

@@ -0,0 +1,32 @@
+// +build !linux,!windows
+
+// Copyright 2015 flannel authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package network
+
+import (
+	"errors"
+
+	"github.com/coreos/flannel/pkg/ip"
+	"github.com/coreos/flannel/subnet"
+)
+
+func SetupIPMasq(ipt IPTablesRules, ipn ip.IP4Net, lease *subnet.Lease) error {
+	return errors.New("SetupIPMasq not implemented for this platform")
+}
+
+func TeardownIPMasq(ipt IPTablesRules, ipn ip.IP4Net, lease *subnet.Lease) error {
+	return errors.New("TeardownIPMasq not implemented for this platform")
+}

network/ipmasq_windows.go

@@ -0,0 +1,33 @@
+// +build windows
+
+// Copyright 2015 flannel authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package network
+
+import (
+	"github.com/coreos/flannel/pkg/ip"
+	"github.com/coreos/flannel/subnet"
+)
+
+func SetupIPMasq(ipt IPTablesRules, ipn ip.IP4Net, lease *subnet.Lease) error {
+	return nil
+}
+
+func TeardownIPMasq(ipt IPTablesRules, ipn ip.IP4Net, lease *subnet.Lease) error {
+	return nil
+}
+
+func SetupAndEnsureIPMasq(network ip.IP4Net, lease *subnet.Lease) {
+}