dhcp ipam: support customizing dhcp options from CNI args

plugins/ipam/dhcp/daemon.go

@@ -29,13 +29,10 @@ import (
 	"time"
 
 	"github.com/containernetworking/cni/pkg/skel"
-	"github.com/containernetworking/cni/pkg/types"
 	current "github.com/containernetworking/cni/pkg/types/100"
 	"github.com/coreos/go-systemd/v22/activation"
 )
 
-const listenFdsStart = 3
-
 var errNoMoreTries = errors.New("no more tries")
 
 type DHCP struct {
@@ -55,21 +52,35 @@ func newDHCP(clientTimeout, clientResendMax time.Duration) *DHCP {
 	}
 }
 
+// TODO: current client ID is too long. At least the container ID should not be used directly.
+// A seperate issue is necessary to ensure no breaking change is affecting other users.
 func generateClientID(containerID string, netName string, ifName string) string {
-	return containerID + "/" + netName + "/" + ifName
+	clientID := containerID + "/" + netName + "/" + ifName
+	// defined in RFC 2132, length size can not be larger than 1 octet. So we truncate 254 to make everyone happy.
+	if len(clientID) > 254 {
+		clientID = clientID[0:254]
+	}
+	return clientID
 }
 
 // Allocate acquires an IP from a DHCP server for a specified container.
 // The acquired lease will be maintained until Release() is called.
 func (d *DHCP) Allocate(args *skel.CmdArgs, result *current.Result) error {
-	conf := types.NetConf{}
+	conf := NetConf{}
 	if err := json.Unmarshal(args.StdinData, &conf); err != nil {
 		return fmt.Errorf("error parsing netconf: %v", err)
 	}
 
+	optsRequesting, optsProviding, err := prepareOptions(args.Args, conf.IPAM.ProvideOptions, conf.IPAM.RequestOptions)
+	if err != nil {
+		return err
+	}
+
 	clientID := generateClientID(args.ContainerID, conf.Name, args.IfName)
 	hostNetns := d.hostNetnsPrefix + args.Netns
-	l, err := AcquireLease(clientID, hostNetns, args.IfName, d.clientTimeout, d.clientResendMax, d.broadcast)
+	l, err := AcquireLease(clientID, hostNetns, args.IfName,
+		optsRequesting, optsProviding,
+		d.clientTimeout, d.clientResendMax, d.broadcast)
 	if err != nil {
 		return err
 	}
@@ -94,7 +105,7 @@ func (d *DHCP) Allocate(args *skel.CmdArgs, result *current.Result) error {
 // Release stops maintenance of the lease acquired in Allocate()
 // and sends a release msg to the DHCP server.
 func (d *DHCP) Release(args *skel.CmdArgs, reply *struct{}) error {
-	conf := types.NetConf{}
+	conf := NetConf{}
 	if err := json.Unmarshal(args.StdinData, &conf); err != nil {
 		return fmt.Errorf("error parsing netconf: %v", err)
 	}

plugins/ipam/dhcp/lease.go

@@ -19,6 +19,7 @@ import (
 	"log"
 	"math/rand"
 	"net"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -62,22 +63,93 @@ type DHCPLease struct {
 	stopping      uint32
 	stop          chan struct{}
 	wg            sync.WaitGroup
+	// list of requesting and providing options and if they are necessary / their value
+	optsRequesting map[dhcp4.OptionCode]bool
+	optsProviding  map[dhcp4.OptionCode][]byte
+}
+
+var requestOptionsDefault = map[dhcp4.OptionCode]bool{
+	dhcp4.OptionRouter:     true,
+	dhcp4.OptionSubnetMask: true,
+}
+
+func prepareOptions(cniArgs string, ProvideOptions []ProvideOption, RequestOptions []RequestOption) (
+	optsRequesting map[dhcp4.OptionCode]bool, optsProviding map[dhcp4.OptionCode][]byte, err error) {
+
+	// parse CNI args
+	cniArgsParsed := map[string]string{}
+	for _, argPair := range strings.Split(cniArgs, ";") {
+		args := strings.SplitN(argPair, "=", 2)
+		if len(args) > 1 {
+			cniArgsParsed[args[0]] = args[1]
+		}
+	}
+
+	// parse providing options map
+	var optParsed dhcp4.OptionCode
+	optsProviding = make(map[dhcp4.OptionCode][]byte)
+	for _, opt := range ProvideOptions {
+		optParsed, err = parseOptionName(string(opt.Option))
+		if err != nil {
+			err = fmt.Errorf("Can not parse option %q: %w", opt.Option, err)
+			return
+		}
+		if len(opt.Value) > 0 {
+			if len(opt.Value) > 255 {
+				err = fmt.Errorf("value too long for option %q: %q", opt.Option, opt.Value)
+				return
+			}
+			optsProviding[optParsed] = []byte(opt.Value)
+		}
+		if value, ok := cniArgsParsed[opt.ValueFromCNIArg]; ok {
+			if len(value) > 255 {
+				err = fmt.Errorf("value too long for option %q from CNI_ARGS %q: %q", opt.Option, opt.ValueFromCNIArg, opt.Value)
+				return
+			}
+			optsProviding[optParsed] = []byte(value)
+		}
+	}
+
+	// parse necessary options map
+	optsRequesting = make(map[dhcp4.OptionCode]bool)
+	skipRequireDefault := false
+	for _, opt := range RequestOptions {
+		if opt.SkipDefault {
+			skipRequireDefault = true
+		}
+		optParsed, err = parseOptionName(string(opt.Option))
+		if err != nil {
+			err = fmt.Errorf("Can not parse option %q: %w", opt.Option, err)
+			return
+		}
+		optsRequesting[optParsed] = true
+	}
+	for k, v := range requestOptionsDefault {
+		// only set if not skipping default and this value does not exists
+		if _, ok := optsRequesting[k]; !ok && !skipRequireDefault {
+			optsRequesting[k] = v
+		}
+	}
+	return
 }
 
 // AcquireLease gets an DHCP lease and then maintains it in the background
 // by periodically renewing it. The acquired lease can be released by
 // calling DHCPLease.Stop()
 func AcquireLease(
 	clientID, netns, ifName string,
+	optsRequesting map[dhcp4.OptionCode]bool, optsProviding map[dhcp4.OptionCode][]byte,
 	timeout, resendMax time.Duration, broadcast bool,
 ) (*DHCPLease, error) {
 	errCh := make(chan error, 1)
 	l := &DHCPLease{
-		clientID:  clientID,
-		stop:      make(chan struct{}),
-		timeout:   timeout,
-		resendMax: resendMax,
-		broadcast: broadcast,
+		clientID:       clientID,
+		stop:           make(chan struct{}),
+		timeout:        timeout,
+		resendMax:      resendMax,
+		broadcast:      broadcast,
+		optsRequesting: optsRequesting,
+		optsProviding:  optsProviding,
 	}
 
 	log.Printf("%v: acquiring lease", clientID)
@@ -139,7 +211,17 @@ func (l *DHCPLease) acquire() error {
 
 	opts := make(dhcp4.Options)
 	opts[dhcp4.OptionClientIdentifier] = []byte(l.clientID)
-	opts[dhcp4.OptionParameterRequestList] = []byte{byte(dhcp4.OptionRouter), byte(dhcp4.OptionSubnetMask)}
+	opts[dhcp4.OptionParameterRequestList] = []byte{}
+	for k := range l.optsRequesting {
+		opts[dhcp4.OptionParameterRequestList] = append(opts[dhcp4.OptionParameterRequestList], byte(k))
+	}
+	for k, v := range l.optsProviding {
+		opts[k] = v
+	}
+	// client identifier's first byte is "type"
+	newClientID := []byte{0}
+	newClientID = append(newClientID, opts[dhcp4.OptionClientIdentifier]...)
+	opts[dhcp4.OptionClientIdentifier] = newClientID
 
 	pkt, err := backoffRetry(l.resendMax, func() (*dhcp4.Packet, error) {
 		ok, ack, err := DhcpRequest(c, opts)
@@ -345,6 +427,7 @@ func jitter(span time.Duration) time.Duration {
 func backoffRetry(resendMax time.Duration, f func() (*dhcp4.Packet, error)) (*dhcp4.Packet, error) {
 	var baseDelay time.Duration = resendDelay0
 	var sleepTime time.Duration
+	var fastRetryLimit = 3 // fast retry for 3 times to speed up
 
 	for {
 		pkt, err := f()
@@ -354,7 +437,12 @@ func backoffRetry(resendMax time.Duration, f func() (*dhcp4.Packet, error)) (*dh
 
 		log.Print(err)
 
-		sleepTime = baseDelay + jitter(time.Second)
+		if fastRetryLimit == 0 {
+			sleepTime = baseDelay + jitter(time.Second)
+		} else {
+			sleepTime = jitter(time.Second)
+			fastRetryLimit--
+		}
 
 		log.Printf("retrying in %f seconds", sleepTime.Seconds())
 

plugins/ipam/dhcp/main.go

@@ -33,6 +33,43 @@ import (
 
 const defaultSocketPath = "/run/cni/dhcp.sock"
 
+// The top-level network config - IPAM plugins are passed the full configuration
+// of the calling plugin, not just the IPAM section.
+type NetConf struct {
+	types.NetConf
+	IPAM *IPAMConfig `json:"ipam"`
+}
+
+type IPAMConfig struct {
+	types.IPAM
+	DaemonSocketPath string `json:"daemonSocketPath"`
+	// When requesting IP from DHCP server, carry these options for management purpose.
+	// Some fields have default values, and can be override by setting a new option with the same name at here.
+	ProvideOptions []ProvideOption `json:"provide"`
+	// When requesting IP from DHCP server, claiming these options are necessary. Options are necessary unless `optional`
+	// is set to `false`.
+	// To override default requesting fields, set `skipDefault` to `false`.
+	// If an field is not optional, but the server failed to provide it, error will be raised.
+	RequestOptions []RequestOption `json:"request"`
+}
+
+// DHCPOption represents a DHCP option. It can be a number, or a string defined in manual dhcp-options(5).
+// Note that not all DHCP options are supported at all time. Error will be raised if unsupported options are used.
+type DHCPOption string
+
+type ProvideOption struct {
+	Option DHCPOption `json:"option"`
+
+	Value           string `json:"value"`
+	ValueFromCNIArg string `json:"fromArg"`
+}
+
+type RequestOption struct {
+	SkipDefault bool `json:"skipDefault"`
+
+	Option DHCPOption `json:"option"`
+}
+
 func main() {
 	if len(os.Args) > 1 && os.Args[1] == "daemon" {
 		var pidfilePath string
@@ -55,7 +92,7 @@ func main() {
 		}
 
 		if err := runDaemon(pidfilePath, hostPrefix, socketPath, timeout, resendMax, broadcast); err != nil {
-			log.Printf(err.Error())
+			log.Print(err.Error())
 			os.Exit(1)
 		}
 	} else {
@@ -88,8 +125,6 @@ func cmdDel(args *skel.CmdArgs) error {
 }
 
 func cmdCheck(args *skel.CmdArgs) error {
-	// TODO: implement
-	//return fmt.Errorf("not implemented")
 	// Plugin must return result in same version as specified in netconf
 	versionDecoder := &version.ConfigDecoder{}
 	//confVersion, err := versionDecoder.Decode(args.StdinData)
@@ -106,16 +141,8 @@ func cmdCheck(args *skel.CmdArgs) error {
 	return nil
 }
 
-type SocketPathConf struct {
-	DaemonSocketPath string `json:"daemonSocketPath,omitempty"`
-}
-
-type TempNetConf struct {
-	IPAM SocketPathConf `json:"ipam,omitempty"`
-}
-
 func getSocketPath(stdinData []byte) (string, error) {
-	conf := TempNetConf{}
+	conf := NetConf{}
 	if err := json.Unmarshal(stdinData, &conf); err != nil {
 		return "", fmt.Errorf("error parsing socket path conf: %v", err)
 	}

plugins/ipam/dhcp/options.go

@@ -18,12 +18,33 @@ import (
 	"encoding/binary"
 	"fmt"
 	"net"
+	"strconv"
 	"time"
 
 	"github.com/containernetworking/cni/pkg/types"
 	"github.com/d2g/dhcp4"
 )
 
+var optionNameToID = map[string]dhcp4.OptionCode{
+	"dhcp-client-identifier":  dhcp4.OptionClientIdentifier,
+	"subnet-mask":             dhcp4.OptionSubnetMask,
+	"routers":                 dhcp4.OptionRouter,
+	"host-name":               dhcp4.OptionHostName,
+	"user-class":              dhcp4.OptionUserClass,
+	"vendor-class-identifier": dhcp4.OptionVendorClassIdentifier,
+}
+
+func parseOptionName(option string) (dhcp4.OptionCode, error) {
+	if val, ok := optionNameToID[option]; ok {
+		return val, nil
+	}
+	i, err := strconv.ParseUint(option, 10, 8)
+	if err != nil {
+		return 0, fmt.Errorf("Can not parse option: %w", err)
+	}
+	return dhcp4.OptionCode(i), nil
+}
+
 func parseRouter(opts dhcp4.Options) net.IP {
 	if opts, ok := opts[dhcp4.OptionRouter]; ok {
 		if len(opts) == 4 {

plugins/ipam/dhcp/options_test.go

@@ -16,6 +16,7 @@ package main
 
 import (
 	"net"
+	"reflect"
 	"testing"
 
 	"github.com/containernetworking/cni/pkg/types"
@@ -73,3 +74,34 @@ func TestParseCIDRRoutes(t *testing.T) {
 
 	validateRoutes(t, routes)
 }
+
+func TestParseOptionName(t *testing.T) {
+	tests := []struct {
+		name    string
+		option  string
+		want    dhcp4.OptionCode
+		wantErr bool
+	}{
+		{
+			"hostname", "host-name", dhcp4.OptionHostName, false,
+		},
+		{
+			"hostname in number", "12", dhcp4.OptionHostName, false,
+		},
+		{
+			"random string", "doNotparseMe", 0, true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseOptionName(tt.option)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("parseOptionName() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("parseOptionName() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}