Enable Windows CI (Appveyor)

- start list of linux_only plugins; ignore them when testing on Windows
- Isolate linux-only code by filename suffix
- Remove stub (NotImplemented) functions
- other misc. fixes for Windows compatibility

pkg/ip/ipmasq_linux.go

@@ -0,0 +1,101 @@
+// Copyright 2015 CNI 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 ip
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/coreos/go-iptables/iptables"
+)
+
+// SetupIPMasq installs iptables rules to masquerade traffic
+// coming from ipn and going outside of it
+func SetupIPMasq(ipn *net.IPNet, chain string, comment string) error {
+	isV6 := ipn.IP.To4() == nil
+
+	var ipt *iptables.IPTables
+	var err error
+	var multicastNet string
+
+	if isV6 {
+		ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv6)
+		multicastNet = "ff00::/8"
+	} else {
+		ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv4)
+		multicastNet = "224.0.0.0/4"
+	}
+	if err != nil {
+		return fmt.Errorf("failed to locate iptables: %v", err)
+	}
+
+	// Create chain if doesn't exist
+	exists := false
+	chains, err := ipt.ListChains("nat")
+	if err != nil {
+		return fmt.Errorf("failed to list chains: %v", err)
+	}
+	for _, ch := range chains {
+		if ch == chain {
+			exists = true
+			break
+		}
+	}
+	if !exists {
+		if err = ipt.NewChain("nat", chain); err != nil {
+			return err
+		}
+	}
+
+	// Packets to this network should not be touched
+	if err := ipt.AppendUnique("nat", chain, "-d", ipn.String(), "-j", "ACCEPT", "-m", "comment", "--comment", comment); err != nil {
+		return err
+	}
+
+	// Don't masquerade multicast - pods should be able to talk to other pods
+	// on the local network via multicast.
+	if err := ipt.AppendUnique("nat", chain, "!", "-d", multicastNet, "-j", "MASQUERADE", "-m", "comment", "--comment", comment); err != nil {
+		return err
+	}
+
+	return ipt.AppendUnique("nat", "POSTROUTING", "-s", ipn.String(), "-j", chain, "-m", "comment", "--comment", comment)
+}
+
+// TeardownIPMasq undoes the effects of SetupIPMasq
+func TeardownIPMasq(ipn *net.IPNet, chain string, comment string) error {
+	isV6 := ipn.IP.To4() == nil
+
+	var ipt *iptables.IPTables
+	var err error
+
+	if isV6 {
+		ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv6)
+	} else {
+		ipt, err = iptables.NewWithProtocol(iptables.ProtocolIPv4)
+	}
+	if err != nil {
+		return fmt.Errorf("failed to locate iptables: %v", err)
+	}
+
+	if err = ipt.Delete("nat", "POSTROUTING", "-s", ipn.String(), "-j", chain, "-m", "comment", "--comment", comment); err != nil {
+		return err
+	}
+
+	if err = ipt.ClearChain("nat", chain); err != nil {
+		return err
+	}
+
+	return ipt.DeleteChain("nat", chain)
+}