/*
Copyright 2014 The Kubernetes Authors.
Copyright 2020 Authors of Arktos - file modified.

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 cni

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"math"
	"sort"
	"strings"
	"sync"
	"time"

	"github.com/containernetworking/cni/libcni"
	cnitypes "github.com/containernetworking/cni/pkg/types"
	"k8s.io/apimachinery/pkg/util/wait"
	runtimeapi "k8s.io/cri-api/pkg/apis/runtime/v1alpha2"
	"k8s.io/klog"
	kubeletconfig "k8s.io/kubernetes/pkg/kubelet/apis/config"
	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
	"k8s.io/kubernetes/pkg/kubelet/dockershim/network"
	"k8s.io/kubernetes/pkg/util/bandwidth"
	utilexec "k8s.io/utils/exec"
)

const (
	CNIPluginName = "cni"

	// defaultSyncConfigPeriod is the default period to sync CNI config
	// TODO: consider making this value configurable or to be a more appropriate value.
	defaultSyncConfigPeriod = time.Second * 5
)

type cniNetworkPlugin struct {
	network.NoopNetworkPlugin

	loNetwork *cniNetwork

	sync.RWMutex
	defaultNetwork *cniNetwork

	host        network.Host
	execer      utilexec.Interface
	nsenterPath string
	confDir     string
	binDirs     []string
	cacheDir    string
	podCidr     string
}

type cniNetwork struct {
	name          string
	NetworkConfig *libcni.NetworkConfigList
	CNIConfig     libcni.CNI
}

// cniPortMapping maps to the standard CNI portmapping Capability
// see: https://github.com/containernetworking/cni/blob/master/CONVENTIONS.md
type cniPortMapping struct {
	HostPort      int32  `json:"hostPort"`
	ContainerPort int32  `json:"containerPort"`
	Protocol      string `json:"protocol"`
	HostIP        string `json:"hostIP"`
}

// cniBandwidthEntry maps to the standard CNI bandwidth Capability
// see: https://github.com/containernetworking/cni/blob/master/CONVENTIONS.md and
// https://github.com/containernetworking/plugins/blob/master/plugins/meta/bandwidth/README.md
type cniBandwidthEntry struct {
	// IngressRate is the bandwidth rate in bits per second for traffic through container. 0 for no limit. If ingressRate is set, ingressBurst must also be set
	IngressRate int `json:"ingressRate,omitempty"`
	// IngressBurst is the bandwidth burst in bits for traffic through container. 0 for no limit. If ingressBurst is set, ingressRate must also be set
	// NOTE: it's not used for now and default to 0.
	IngressBurst int `json:"ingressBurst,omitempty"`
	// EgressRate is the bandwidth is the bandwidth rate in bits per second for traffic through container. 0 for no limit. If egressRate is set, egressBurst must also be set
	EgressRate int `json:"egressRate,omitempty"`
	// EgressBurst is the bandwidth burst in bits for traffic through container. 0 for no limit. If egressBurst is set, egressRate must also be set
	// NOTE: it's not used for now and default to 0.
	EgressBurst int `json:"egressBurst,omitempty"`
}

// cniIpRange maps to the standard CNI ip range Capability
type cniIpRange struct {
	Subnet string `json:"subnet"`
}

// cniDNSConfig maps to the windows CNI dns Capability.
// see: https://github.com/containernetworking/cni/blob/master/CONVENTIONS.md
// Note that dns capability is only used for Windows containers.
type cniDNSConfig struct {
	// List of DNS servers of the cluster.
	Servers []string `json:"servers,omitempty"`
	// List of DNS search domains of the cluster.
	Searches []string `json:"searches,omitempty"`
	// List of DNS options.
	Options []string `json:"options,omitempty"`
}

func SplitDirs(dirs string) []string {
	// Use comma rather than colon to work better with Windows too
	return strings.Split(dirs, ",")
}

func ProbeNetworkPlugins(confDir, cacheDir string, binDirs []string) []network.NetworkPlugin {
	old := binDirs
	binDirs = make([]string, 0, len(binDirs))
	for _, dir := range old {
		if dir != "" {
			binDirs = append(binDirs, dir)
		}
	}

	plugin := &cniNetworkPlugin{
		defaultNetwork: nil,
		loNetwork:      getLoNetwork(binDirs),
		execer:         utilexec.New(),
		confDir:        confDir,
		binDirs:        binDirs,
		cacheDir:       cacheDir,
	}

	// sync NetworkConfig in best effort during probing.
	plugin.syncNetworkConfig()
	return []network.NetworkPlugin{plugin}
}

func getDefaultCNINetwork(confDir string, binDirs []string) (*cniNetwork, error) {
	files, err := libcni.ConfFiles(confDir, []string{".conf", ".conflist", ".json"})
	switch {
	case err != nil:
		return nil, err
	case len(files) == 0:
		return nil, fmt.Errorf("No networks found in %s", confDir)
	}

	sort.Strings(files)
	for _, confFile := range files {
		var confList *libcni.NetworkConfigList
		if strings.HasSuffix(confFile, ".conflist") {
			confList, err = libcni.ConfListFromFile(confFile)
			if err != nil {
				klog.Warningf("Error loading CNI config list file %s: %v", confFile, err)
				continue
			}
		} else {
			conf, err := libcni.ConfFromFile(confFile)
			if err != nil {
				klog.Warningf("Error loading CNI config file %s: %v", confFile, err)
				continue
			}
			// Ensure the config has a "type" so we know what plugin to run.
			// Also catches the case where somebody put a conflist into a conf file.
			if conf.Network.Type == "" {
				klog.Warningf("Error loading CNI config file %s: no 'type'; perhaps this is a .conflist?", confFile)
				continue
			}

			confList, err = libcni.ConfListFromConf(conf)
			if err != nil {
				klog.Warningf("Error converting CNI config file %s to list: %v", confFile, err)
				continue
			}
		}
		if len(confList.Plugins) == 0 {
			klog.Warningf("CNI config list %s has no networks, skipping", confFile)
			continue
		}

		klog.V(4).Infof("Using CNI configuration file %s", confFile)

		network := &cniNetwork{
			name:          confList.Name,
			NetworkConfig: confList,
			CNIConfig:     &libcni.CNIConfig{Path: binDirs},
		}
		return network, nil
	}
	return nil, fmt.Errorf("No valid networks found in %s", confDir)
}

func (plugin *cniNetworkPlugin) Init(host network.Host, hairpinMode kubeletconfig.HairpinMode, nonMasqueradeCIDR string, mtu int) error {
	err := plugin.platformInit()
	if err != nil {
		return err
	}

	plugin.host = host

	plugin.syncNetworkConfig()

	// start a goroutine to sync network config from confDir periodically to detect network config updates in every 5 seconds
	go wait.Forever(plugin.syncNetworkConfig, defaultSyncConfigPeriod)

	return nil
}

func (plugin *cniNetworkPlugin) syncNetworkConfig() {
	network, err := getDefaultCNINetwork(plugin.confDir, plugin.binDirs)
	if err != nil {
		klog.Warningf("Unable to update cni config: %s", err)
		return
	}
	plugin.setDefaultNetwork(network)
}

func (plugin *cniNetworkPlugin) getDefaultNetwork() *cniNetwork {
	plugin.RLock()
	defer plugin.RUnlock()
	return plugin.defaultNetwork
}

func (plugin *cniNetworkPlugin) setDefaultNetwork(n *cniNetwork) {
	plugin.Lock()
	defer plugin.Unlock()
	plugin.defaultNetwork = n
}

func (plugin *cniNetworkPlugin) checkInitialized() error {
	if plugin.getDefaultNetwork() == nil {
		return errors.New("cni config uninitialized")
	}

	// If the CNI configuration has the ipRanges capability, we need a PodCIDR assigned
	for _, p := range plugin.getDefaultNetwork().NetworkConfig.Plugins {
		if p.Network.Capabilities["ipRanges"] {
			if plugin.podCidr == "" {
				return errors.New("no PodCIDR set")
			}
			break
		}
	}
	return nil
}

// Event handles any change events. The only event ever sent is the PodCIDR change.
// No network plugins support changing an already-set PodCIDR
func (plugin *cniNetworkPlugin) Event(name string, details map[string]interface{}) {
	if name != network.NET_PLUGIN_EVENT_POD_CIDR_CHANGE {
		return
	}

	plugin.Lock()
	defer plugin.Unlock()

	podCIDR, ok := details[network.NET_PLUGIN_EVENT_POD_CIDR_CHANGE_DETAIL_CIDR].(string)
	if !ok {
		klog.Warningf("%s event didn't contain pod CIDR", network.NET_PLUGIN_EVENT_POD_CIDR_CHANGE)
		return
	}

	if plugin.podCidr != "" {
		klog.Warningf("Ignoring subsequent pod CIDR update to %s", podCIDR)
		return
	}

	plugin.podCidr = podCIDR
}

func (plugin *cniNetworkPlugin) Name() string {
	return CNIPluginName
}

func (plugin *cniNetworkPlugin) Status() error {
	// Can't set up pods if we don't have any CNI network configs yet
	return plugin.checkInitialized()
}

func (plugin *cniNetworkPlugin) SetUpPod(tenant, namespace string, name string, id kubecontainer.ContainerID, annotations, options map[string]string) error {
	if err := plugin.checkInitialized(); err != nil {
		return err
	}
	netnsPath, err := plugin.host.GetNetNS(id.ID)
	if err != nil {
		return fmt.Errorf("CNI failed to retrieve network namespace path: %v", err)
	}

	// Windows doesn't have loNetwork. It comes only with Linux
	if plugin.loNetwork != nil {
		if _, err = plugin.addToNetwork(plugin.loNetwork, name, namespace, tenant, id, netnsPath, annotations, options); err != nil {
			return err
		}
	}

	_, err = plugin.addToNetwork(plugin.getDefaultNetwork(), name, namespace, tenant, id, netnsPath, annotations, options)
	return err
}

func (plugin *cniNetworkPlugin) TearDownPod(tenant, namespace string, name string, id kubecontainer.ContainerID) error {
	if err := plugin.checkInitialized(); err != nil {
		return err
	}

	// Lack of namespace should not be fatal on teardown
	netnsPath, err := plugin.host.GetNetNS(id.ID)
	if err != nil {
		klog.Warningf("CNI failed to retrieve network namespace path: %v", err)
	}

	return plugin.deleteFromNetwork(plugin.getDefaultNetwork(), name, namespace, tenant, id, netnsPath, nil)
}

func podDesc(tenant, namespace, name string, id kubecontainer.ContainerID) string {
	return fmt.Sprintf("%s_%s_%s/%s", tenant, namespace, name, id.ID)
}

func (plugin *cniNetworkPlugin) addToNetwork(network *cniNetwork, podName string, podNamespace string, podTenant string, podSandboxID kubecontainer.ContainerID, podNetnsPath string, annotations, options map[string]string) (cnitypes.Result, error) {
	rt, err := plugin.buildCNIRuntimeConf(podName, podNamespace, podTenant, podSandboxID, podNetnsPath, annotations, options)
	if err != nil {
		klog.Errorf("Error adding network when building cni runtime conf: %v", err)
		return nil, err
	}

	pdesc := podDesc(podTenant, podNamespace, podName, podSandboxID)
	netConf, cniNet := network.NetworkConfig, network.CNIConfig
	klog.V(4).Infof("Adding %s to network %s/%s netns %q", pdesc, netConf.Plugins[0].Network.Type, netConf.Name, podNetnsPath)
	res, err := cniNet.AddNetworkList(context.TODO(), netConf, rt)
	if err != nil {
		klog.Errorf("Error adding %s to network %s/%s: %v", pdesc, netConf.Plugins[0].Network.Type, netConf.Name, err)
		return nil, err
	}
	klog.V(4).Infof("Added %s to network %s: %v", pdesc, netConf.Name, res)
	return res, nil
}

func (plugin *cniNetworkPlugin) deleteFromNetwork(network *cniNetwork, podName string, podNamespace string, podTenant string, podSandboxID kubecontainer.ContainerID, podNetnsPath string, annotations map[string]string) error {
	rt, err := plugin.buildCNIRuntimeConf(podName, podNamespace, podTenant, podSandboxID, podNetnsPath, annotations, nil)
	if err != nil {
		klog.Errorf("Error deleting network when building cni runtime conf: %v", err)
		return err
	}

	pdesc := podDesc(podTenant, podNamespace, podName, podSandboxID)
	netConf, cniNet := network.NetworkConfig, network.CNIConfig
	klog.V(4).Infof("Deleting %s from network %s/%s netns %q", pdesc, netConf.Plugins[0].Network.Type, netConf.Name, podNetnsPath)
	err = cniNet.DelNetworkList(context.TODO(), netConf, rt)
	// The pod may not get deleted successfully at the first time.
	// Ignore "no such file or directory" error in case the network has already been deleted in previous attempts.
	if err != nil && !strings.Contains(err.Error(), "no such file or directory") {
		klog.Errorf("Error deleting %s from network %s/%s: %v", pdesc, netConf.Plugins[0].Network.Type, netConf.Name, err)
		return err
	}
	klog.V(4).Infof("Deleted %s from network %s/%s", pdesc, netConf.Plugins[0].Network.Type, netConf.Name)
	return nil
}

func (plugin *cniNetworkPlugin) buildCNIRuntimeConf(podName string, podNs string, podTenant string, podSandboxID kubecontainer.ContainerID, podNetnsPath string, annotations, options map[string]string) (*libcni.RuntimeConf, error) {
	rt := &libcni.RuntimeConf{
		ContainerID: podSandboxID.ID,
		NetNS:       podNetnsPath,
		IfName:      network.DefaultInterfaceName,
		CacheDir:    plugin.cacheDir,
		Args: [][2]string{
			{"IgnoreUnknown", "1"},
			{"K8S_POD_TENANT", podTenant},
			{"K8S_POD_NAMESPACE", podNs},
			{"K8S_POD_NAME", podName},
			{"K8S_POD_INFRA_CONTAINER_ID", podSandboxID.ID},
		},
	}

	// port mappings are a cni capability-based args, rather than parameters
	// to a specific plugin
	portMappings, err := plugin.host.GetPodPortMappings(podSandboxID.ID)
	if err != nil {
		return nil, fmt.Errorf("could not retrieve port mappings: %v", err)
	}
	portMappingsParam := make([]cniPortMapping, 0, len(portMappings))
	for _, p := range portMappings {
		if p.HostPort <= 0 {
			continue
		}
		portMappingsParam = append(portMappingsParam, cniPortMapping{
			HostPort:      p.HostPort,
			ContainerPort: p.ContainerPort,
			Protocol:      strings.ToLower(string(p.Protocol)),
			HostIP:        p.HostIP,
		})
	}
	rt.CapabilityArgs = map[string]interface{}{
		"portMappings": portMappingsParam,
	}

	ingress, egress, err := bandwidth.ExtractPodBandwidthResources(annotations)
	if err != nil {
		return nil, fmt.Errorf("Error reading pod bandwidth annotations: %v", err)
	}
	if ingress != nil || egress != nil {
		bandwidthParam := cniBandwidthEntry{}
		if ingress != nil {
			// see: https://github.com/containernetworking/cni/blob/master/CONVENTIONS.md and
			// https://github.com/containernetworking/plugins/blob/master/plugins/meta/bandwidth/README.md
			// Rates are in bits per second, burst values are in bits.
			bandwidthParam.IngressRate = int(ingress.Value())
			bandwidthParam.IngressBurst = math.MaxInt32 // no limit
		}
		if egress != nil {
			bandwidthParam.EgressRate = int(egress.Value())
			bandwidthParam.EgressBurst = math.MaxInt32 // no limit
		}
		rt.CapabilityArgs["bandwidth"] = bandwidthParam
	}

	// Set the PodCIDR
	rt.CapabilityArgs["ipRanges"] = [][]cniIpRange{{{Subnet: plugin.podCidr}}}

	// Set dns capability args.
	if dnsOptions, ok := options["dns"]; ok {
		dnsConfig := runtimeapi.DNSConfig{}
		err := json.Unmarshal([]byte(dnsOptions), &dnsConfig)
		if err != nil {
			return nil, fmt.Errorf("failed to unmarshal dns config %q: %v", dnsOptions, err)
		}
		if dnsParam := buildDNSCapabilities(&dnsConfig); dnsParam != nil {
			rt.CapabilityArgs["dns"] = *dnsParam
		}
	}

	return rt, nil
}
