Fix IPv6

cmd/udhcpc-handler/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"net"
 	"os"
 
 	log "github.com/sirupsen/logrus"
@@ -22,9 +23,13 @@ func main() {
 	switch event.Type {
 	case "bound", "renew":
 		if v6, ok := os.LookupEnv("ipv6"); ok {
-			event.Data.IP = v6
+			// Clean up the IP (udhcpc6 emits a _lot_ of zeros)
+			_, netV6, err := net.ParseCIDR(v6 + "/128")
+			if err != nil {
+				log.WithError(err).Warn("Failed to parse IPv6 address")
+			}
 
-			// TODO: Sort out router and domain options for IPv6
+			event.Data.IP = netV6.String()
 		} else {
 			event.Data.IP = os.Getenv("ip") + "/" + os.Getenv("mask")
 			event.Data.Gateway = os.Getenv("router")

pkg/plugin/network.go

@@ -204,15 +204,13 @@ func (p *Plugin) CreateEndpoint(ctx context.Context, r CreateEndpointRequest) (C
 				return fmt.Errorf("failed to get initial IP%v address via DHCP%v: %w", v6str, v6str, err)
 			}
 
-			hint := p.gatewayHints[r.EndpointID]
 			if v6 {
 				res.Interface.AddressIPv6 = info.IP
-				hint.V6 = info.Gateway
+				// No gateways in DHCPv6!
 			} else {
 				res.Interface.Address = info.IP
-				hint.V4 = info.Gateway
+				p.gatewayHints[r.EndpointID] = info.Gateway
 			}
-			p.gatewayHints[r.EndpointID] = hint
 
 			return nil
 		}
@@ -290,14 +288,12 @@ func (p *Plugin) Join(ctx context.Context, r JoinRequest) (JoinResponse, error)
 
 	if hint, ok := p.gatewayHints[r.EndpointID]; ok {
 		log.WithFields(log.Fields{
-			"network":    r.NetworkID[:12],
-			"endpoint":   r.EndpointID[:12],
-			"sandbox":    r.SandboxKey,
-			"gateway_v4": hint.V4,
-			"gateway_v6": hint.V6,
-		}).Info("[Join] Setting gateway(s) retrieved from CreateEndpoint")
-		res.Gateway = hint.V4
-		res.GatewayIPv6 = hint.V6
+			"network":  r.NetworkID[:12],
+			"endpoint": r.EndpointID[:12],
+			"sandbox":  r.SandboxKey,
+			"gateway":  hint,
+		}).Info("[Join] Setting IPv4 gateway retrieved from CreateEndpoint")
+		res.Gateway = hint
 
 		delete(p.gatewayHints, r.EndpointID)
 	}

pkg/plugin/plugin.go

@@ -28,8 +28,9 @@ type DHCPNetworkOptions struct {
 func decodeOpts(input interface{}) (DHCPNetworkOptions, error) {
 	var opts DHCPNetworkOptions
 	optsDecoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
-		Result:      &opts,
-		ErrorUnused: true,
+		Result:           &opts,
+		ErrorUnused:      true,
+		WeaklyTypedInput: true,
 		DecodeHook: mapstructure.ComposeDecodeHookFunc(
 			mapstructure.StringToTimeDurationHookFunc(),
 		),
@@ -45,17 +46,12 @@ func decodeOpts(input interface{}) (DHCPNetworkOptions, error) {
 	return opts, nil
 }
 
-type gatewayHint struct {
-	V4 string
-	V6 string
-}
-
 // Plugin is the DHCP network plugin
 type Plugin struct {
 	docker *docker.Client
 	server http.Server
 
-	gatewayHints map[string]gatewayHint
+	gatewayHints map[string]string
 }
 
 // NewPlugin creates a new Plugin
@@ -68,7 +64,7 @@ func NewPlugin() (*Plugin, error) {
 	p := Plugin{
 		docker: client,
 
-		gatewayHints: make(map[string]gatewayHint),
+		gatewayHints: make(map[string]string),
 	}
 
 	mux := http.NewServeMux()

pkg/udhcpc/client.go

@@ -2,7 +2,10 @@ package udhcpc
 
 import (
 	"bufio"
+	"bytes"
 	"context"
+	"encoding/binary"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -74,8 +77,20 @@ func NewDHCPClient(iface string, opts *DHCPClientOptions) (*DHCPClient, error) {
 	}
 
 	if opts.Hostname != "" {
-		// TODO: This used to be broken for udhcpc6, is that still the case?
-		c.cmd.Args = append(c.cmd.Args, "-x", "hostname:"+opts.Hostname)
+		hostnameOpt := "hostname:" + opts.Hostname
+		if opts.V6 {
+			// TODO: We encode the fqdn for DHCPv6 because udhcpc6 seems to be broken
+			var data bytes.Buffer
+
+			// flags: S bit set (see RFC4704)
+			binary.Write(&data, binary.BigEndian, uint8(0b0001))
+			binary.Write(&data, binary.BigEndian, uint8(len(opts.Hostname)))
+			data.WriteString(opts.Hostname)
+
+			hostnameOpt = "0x27:" + hex.EncodeToString(data.Bytes())
+		}
+
+		c.cmd.Args = append(c.cmd.Args, "-x", hostnameOpt)
 	}
 
 	// Vendor ID string option is not available for udhcpc6

test_env.sh

@@ -2,6 +2,8 @@
 BRIDGE=net-dhcp
 BRIDGE_IP="10.123.0.1/24"
 DHCP_RANGE="10.123.0.5,10.123.0.254"
+BRIDGE_IP6="fd69::1/64"
+DHCP6_RANGE="fd69::5,fd69::1000,64"
 DOMAIN=cool-dhcp
 
 quit() {
@@ -14,10 +16,12 @@ trap quit SIGINT SIGTERM
 ip link add "$BRIDGE" type bridge
 ip link set up dev "$BRIDGE"
 ip addr add "$BRIDGE_IP" dev "$BRIDGE"
+ip addr add "$BRIDGE_IP6" dev "$BRIDGE"
 
 dnsmasq --no-daemon --conf-file=/dev/null \
     --port=0 --interface="$BRIDGE" --bind-interfaces \
     --domain="$DOMAIN" \
-    --dhcp-range="$DHCP_RANGE" --dhcp-leasefile=/dev/null
+    --dhcp-range="$DHCP_RANGE" --dhcp-leasefile=/dev/null \
+    --dhcp-range="$DHCP6_RANGE" --enable-ra
 
 quit