Port networking to CNI

Replaced netns utility with CNI plugins to create a bridge network
and allow communication between containers with firewall plugin.

Overwrite the CNI config in case it exists. Allow updating the config
on new versions.

Signed-off-by: Carlos de Paula <me@carlosedp.com>

vendor/github.com/containernetworking/cni/pkg/version/plugin.go

@@ -0,0 +1,144 @@
+// Copyright 2016 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 version
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+// PluginInfo reports information about CNI versioning
+type PluginInfo interface {
+	// SupportedVersions returns one or more CNI spec versions that the plugin
+	// supports.  If input is provided in one of these versions, then the plugin
+	// promises to use the same CNI version in its response
+	SupportedVersions() []string
+
+	// Encode writes this CNI version information as JSON to the given Writer
+	Encode(io.Writer) error
+}
+
+type pluginInfo struct {
+	CNIVersion_        string   `json:"cniVersion"`
+	SupportedVersions_ []string `json:"supportedVersions,omitempty"`
+}
+
+// pluginInfo implements the PluginInfo interface
+var _ PluginInfo = &pluginInfo{}
+
+func (p *pluginInfo) Encode(w io.Writer) error {
+	return json.NewEncoder(w).Encode(p)
+}
+
+func (p *pluginInfo) SupportedVersions() []string {
+	return p.SupportedVersions_
+}
+
+// PluginSupports returns a new PluginInfo that will report the given versions
+// as supported
+func PluginSupports(supportedVersions ...string) PluginInfo {
+	if len(supportedVersions) < 1 {
+		panic("programmer error: you must support at least one version")
+	}
+	return &pluginInfo{
+		CNIVersion_:        Current(),
+		SupportedVersions_: supportedVersions,
+	}
+}
+
+// PluginDecoder can decode the response returned by a plugin's VERSION command
+type PluginDecoder struct{}
+
+func (*PluginDecoder) Decode(jsonBytes []byte) (PluginInfo, error) {
+	var info pluginInfo
+	err := json.Unmarshal(jsonBytes, &info)
+	if err != nil {
+		return nil, fmt.Errorf("decoding version info: %s", err)
+	}
+	if info.CNIVersion_ == "" {
+		return nil, fmt.Errorf("decoding version info: missing field cniVersion")
+	}
+	if len(info.SupportedVersions_) == 0 {
+		if info.CNIVersion_ == "0.2.0" {
+			return PluginSupports("0.1.0", "0.2.0"), nil
+		}
+		return nil, fmt.Errorf("decoding version info: missing field supportedVersions")
+	}
+	return &info, nil
+}
+
+// ParseVersion parses a version string like "3.0.1" or "0.4.5" into major,
+// minor, and micro numbers or returns an error
+func ParseVersion(version string) (int, int, int, error) {
+	var major, minor, micro int
+	if version == "" {
+		return -1, -1, -1, fmt.Errorf("invalid version %q: the version is empty", version)
+	}
+
+	parts := strings.Split(version, ".")
+	if len(parts) >= 4 {
+		return -1, -1, -1, fmt.Errorf("invalid version %q: too many parts", version)
+	}
+
+	major, err := strconv.Atoi(parts[0])
+	if err != nil {
+		return -1, -1, -1, fmt.Errorf("failed to convert major version part %q: %v", parts[0], err)
+	}
+
+	if len(parts) >= 2 {
+		minor, err = strconv.Atoi(parts[1])
+		if err != nil {
+			return -1, -1, -1, fmt.Errorf("failed to convert minor version part %q: %v", parts[1], err)
+		}
+	}
+
+	if len(parts) >= 3 {
+		micro, err = strconv.Atoi(parts[2])
+		if err != nil {
+			return -1, -1, -1, fmt.Errorf("failed to convert micro version part %q: %v", parts[2], err)
+		}
+	}
+
+	return major, minor, micro, nil
+}
+
+// GreaterThanOrEqualTo takes two string versions, parses them into major/minor/micro
+// numbers, and compares them to determine whether the first version is greater
+// than or equal to the second
+func GreaterThanOrEqualTo(version, otherVersion string) (bool, error) {
+	firstMajor, firstMinor, firstMicro, err := ParseVersion(version)
+	if err != nil {
+		return false, err
+	}
+
+	secondMajor, secondMinor, secondMicro, err := ParseVersion(otherVersion)
+	if err != nil {
+		return false, err
+	}
+
+	if firstMajor > secondMajor {
+		return true, nil
+	} else if firstMajor == secondMajor {
+		if firstMinor > secondMinor {
+			return true, nil
+		} else if firstMinor == secondMinor && firstMicro >= secondMicro {
+			return true, nil
+		}
+	}
+	return false, nil
+}