incusd/main_forknet: Implement stateful DHCPv6

Signed-off-by: Rahaf Aljerwi <[email protected]>

Author: rahafjrw

cmd/incusd/main_forknet.go

@@ -219,10 +219,13 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/insomniacslk/dhcp/dhcpv4"
 	"github.com/insomniacslk/dhcp/dhcpv4/nclient4"
+	"github.com/insomniacslk/dhcp/dhcpv6"
+	"github.com/insomniacslk/dhcp/dhcpv6/nclient6"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 
@@ -234,7 +237,11 @@ import (
 )
 
 type cmdForknet struct {
-	global *cmdGlobal
+	global      *cmdGlobal
+	dhcpv4Lease *nclient4.Lease
+	dhcpv6Lease *dhcpv6.Message
+	applyDNSMu  sync.Mutex
+	args        []string
 }
 
 func (c *cmdForknet) command() *cobra.Command {
@@ -298,6 +305,7 @@ func (c *cmdForknet) runInfo(_ *cobra.Command, _ []string) error {
 func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
 	logger := logrus.New()
 	logger.Level = logrus.DebugLevel
+	c.args = args
 
 	if C.forknet_dhcp_logfile >= 0 {
 		logger.SetOutput(os.NewFile(uintptr(C.forknet_dhcp_logfile), "incus-dhcp-logfile"))
@@ -317,7 +325,7 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
 	err := link.SetUp()
 	if err != nil {
 		logger.WithField("interface", iface).Error("Giving up on DHCP, couldn't bring up interface")
-		return nil
+		return err
 	}
 
 	// Read the hostname.
@@ -328,67 +336,62 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
 
 	hostname := strings.TrimSpace(string(bb))
 
+	// Create PID file.
+	err = os.WriteFile(filepath.Join(args[0], "dhcp.pid"), []byte(fmt.Sprintf("%d", os.Getpid())), 0o644)
+	if err != nil {
+		logger.WithError(err).Error("Giving up on DHCP, couldn't write PID file")
+		return err
+	}
+
+	errorChannel := make(chan error, 2)
+	go c.dhcpRunV4(errorChannel, iface, hostname, logger)
+	go c.dhcpRunV6(errorChannel, iface, hostname, logger)
+
+	err = <-errorChannel
+	return err
+}
+
+func (c *cmdForknet) dhcpRunV4(errorChannel chan error, iface string, hostname string, logger *logrus.Logger) {
 	// Try to get a lease.
 	client, err := nclient4.New(iface)
 	if err != nil {
-		logger.WithError(err).Error("Giving up on DHCP, couldn't set up client")
-		return nil
+		logger.WithError(err).Error("Giving up on DHCPv4, couldn't set up client")
+		errorChannel <- err
+		return
 	}
 
 	defer func() { _ = client.Close() }()
 
 	lease, err := client.Request(context.Background(), dhcpv4.WithOption(dhcpv4.OptHostName(hostname)))
 	if err != nil {
 		logger.WithError(err).WithField("hostname", hostname).
-			Error("Giving up on DHCP, couldn't get a lease")
-		return nil
+			Error("Giving up on DHCPv4, couldn't get a lease")
+		errorChannel <- err
+		return
 	}
 
 	// Parse the response.
 	if lease.Offer == nil {
 		logger.WithField("hostname", hostname).
 			Error("Giving up on DHCP, couldn't get a lease after 5s")
-		return nil
+		errorChannel <- err
+		return
 	}
 
 	if lease.Offer.YourIPAddr == nil || lease.Offer.YourIPAddr.Equal(net.IPv4zero) || lease.Offer.SubnetMask() == nil || len(lease.Offer.Router()) != 1 {
 		logger.Error("Giving up on DHCP, lease didn't contain required fields")
-		return nil
+		errorChannel <- fmt.Errorf("Giving up on DHCP, lease didn't contain required fields")
+		return
 	}
 
-	if len(lease.Offer.DNS()) > 0 {
-		// DNS configuration.
-		f, err := os.Create(filepath.Join(args[0], "resolv.conf"))
-		if err != nil {
-			logger.WithError(err).Error("Giving up on DHCP, couldn't create resolv.conf")
-			return nil
-		}
-
-		defer f.Close()
-
-		for _, nameserver := range lease.Offer.DNS() {
-			_, err = fmt.Fprintf(f, "nameserver %s\n", nameserver)
-			if err != nil {
-				logger.WithError(err).Error("Giving up on DHCP, couldn't prepare resolv.conf")
-				return nil
-			}
-		}
-
-		if lease.Offer.DomainName() != "" {
-			_, err = fmt.Fprintf(f, "domain %s\n", lease.Offer.DomainName())
-			if err != nil {
-				logger.WithError(err).Error("Giving up on DHCP, couldn't prepare resolv.conf")
-				return nil
-			}
-		}
-
-		if lease.Offer.DomainSearch() != nil && len(lease.Offer.DomainSearch().Labels) > 0 {
-			_, err = fmt.Fprintf(f, "search %s\n", strings.Join(lease.Offer.DomainSearch().Labels, ", "))
-			if err != nil {
-				logger.WithError(err).Error("Giving up on DHCP, couldn't prepare resolv.conf")
-				return nil
-			}
-		}
+	c.applyDNSMu.Lock()
+	c.dhcpv4Lease = lease
+	c.applyDNSMu.Unlock()
+	err = c.dhcpApplyDNS(logger)
+	if err != nil {
+		logger.WithError(err).Error("Giving up on DHCPv4, error applying DNS")
+		errorChannel <- err
+		return
 	}
 
 	// Network configuration.
@@ -402,8 +405,9 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
 
 	err = addr.Add()
 	if err != nil {
-		logger.WithError(err).Error("Giving up on DHCP, couldn't add IP")
-		return nil
+		logger.WithError(err).Error("Giving up on DHCPv4, couldn't add IP")
+		errorChannel <- err
+		return
 	}
 
 	if lease.Offer.Options.Has(dhcpv4.OptionClasslessStaticRoute) {
@@ -421,7 +425,8 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
 			err = route.Add()
 			if err != nil {
 				logger.WithError(err).Error("Giving up on DHCP, couldn't add classless static route")
-				return nil
+				errorChannel <- err
+				return
 			}
 		}
 	} else {
@@ -435,17 +440,11 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
 		err = route.Add()
 		if err != nil {
 			logger.WithError(err).Error("Giving up on DHCP, couldn't add default route")
-			return nil
+			errorChannel <- err
+			return
 		}
 	}
 
-	// Create PID file.
-	err = os.WriteFile(filepath.Join(args[0], "dhcp.pid"), []byte(fmt.Sprintf("%d", os.Getpid())), 0o644)
-	if err != nil {
-		logger.WithError(err).Error("Giving up on DHCP, couldn't write PID file")
-		return nil
-	}
-
 	// Handle DHCP renewal.
 	for {
 		// Wait until it's renewal time.
@@ -454,14 +453,175 @@ func (c *cmdForknet) runDHCP(_ *cobra.Command, args []string) error {
 		// Renew the lease.
 		newLease, err := client.Renew(context.Background(), lease, dhcpv4.WithOption(dhcpv4.OptHostName(hostname)))
 		if err != nil {
-			logger.WithError(err).Error("Giving up on DHCP, couldn't renew the lease")
-			return nil
+			logger.WithError(err).Error("Giving up on DHCPv4, couldn't renew the lease")
+			errorChannel <- err
+			return
 		}
 
 		lease = newLease
 	}
 }
 
+func (c *cmdForknet) dhcpRunV6(errorChannel chan error, iface string, hostname string, logger *logrus.Logger) {
+	// Get a new DHCPv6 client.
+	client, err := nclient6.New(iface)
+	if err != nil {
+		logger.WithError(err).Error("Giving up on DHCPv6, couldn't set up client")
+		errorChannel <- err
+		return
+	}
+
+	defer func() { _ = client.Close() }()
+
+	// Try to get a lease.
+	advertisement, err := client.Solicit(context.Background(), dhcpv6.WithFQDN(0, hostname))
+	if err != nil {
+		logger.WithError(err).Error("Giving up on DHCPv6, error during DHCPv6 Solicit")
+		errorChannel <- err
+		return
+	}
+
+	reply, err := client.Request(context.Background(), advertisement, dhcpv6.WithFQDN(0, hostname))
+	if err != nil {
+		logger.WithError(err).Error("Giving up on DHCPv6, error during DHCPv6 Request")
+		errorChannel <- err
+		return
+	}
+
+	c.applyDNSMu.Lock()
+	c.dhcpv6Lease = reply
+	c.applyDNSMu.Unlock()
+	err = c.dhcpApplyDNS(logger)
+	if err != nil {
+		logger.WithError(err).Error("Giving up on DHCPv6, error applying DNS")
+		errorChannel <- err
+		return
+	}
+
+	// Network configuration.
+	iana := reply.Options.OneIANA()
+	if iana == nil {
+		logger.Error("Giving up on DHCPv6 renewal, reply missing IANA")
+		errorChannel <- fmt.Errorf("Giving up on DHCPv6 renewal, reply missing IANA")
+		return
+	}
+
+	for _, iaaddr := range iana.Options.Addresses() {
+		addr := &ip.Addr{
+			DevName: iface,
+			Address: fmt.Sprintf("%s/%d", iaaddr.IPv6Addr, net.CIDRMask(128, 128)),
+			Family:  ip.FamilyV6,
+		}
+
+		err = addr.Add()
+		if err != nil {
+			logger.WithError(err).Error("Giving up on DHCPv6, couldn't add IP")
+			errorChannel <- err
+			return
+		}
+	}
+
+	// Handle DHCP Renewal.
+	for {
+		// Wait until it's renewal time.
+		t1 := iana.T1
+		time.Sleep(t1)
+
+		// Renew the lease.
+		var optIAAddrs []dhcpv6.OptIAAddress
+		for _, optIAAddr := range iana.Options.Addresses() {
+			optIAAddrs = append(optIAAddrs, *optIAAddr)
+		}
+
+		modifiers := []dhcpv6.Modifier{
+			dhcpv6.WithClientID(reply.Options.ClientID()),
+			dhcpv6.WithServerID(reply.Options.ServerID()),
+			dhcpv6.WithIAID(iana.IaId),
+			dhcpv6.WithIANA(optIAAddrs...),
+		}
+
+		renew, err := dhcpv6.NewMessage(modifiers...)
+		if err != nil {
+			logger.WithError(err).Error("Giving up on DHCv6, couldn't create renew message")
+			errorChannel <- err
+			return
+		}
+
+		renew.MessageType = dhcpv6.MessageTypeRenew
+
+		newReply, err := dhcpv6.NewReplyFromMessage(renew, dhcpv6.WithFQDN(0, hostname))
+		if err != nil {
+			logger.WithError(err).Error("Giving up on DHCPv6, couldn't renew the lease")
+			errorChannel <- err
+			return
+		}
+
+		reply = newReply
+	}
+}
+
+func (c *cmdForknet) dhcpApplyDNS(logger *logrus.Logger) error {
+	c.applyDNSMu.Lock()
+	defer c.applyDNSMu.Unlock()
+
+	f, err := os.Create(filepath.Join(c.args[0], "resolv.conf"))
+	if err != nil {
+		logger.WithError(err).Error("Giving up on DHCP, couldn't create resolv.conf")
+		return err
+	}
+
+	defer f.Close()
+
+	if c.dhcpv4Lease != nil {
+		if len(c.dhcpv4Lease.Offer.DNS()) > 0 {
+			for _, nameserver := range c.dhcpv4Lease.Offer.DNS() {
+				_, err = fmt.Fprintf(f, "nameserver %s\n", nameserver)
+				if err != nil {
+					logger.WithError(err).Error("Giving up on DHCPv4, couldn't prepare resolv.conf")
+					return err
+				}
+			}
+
+			if c.dhcpv4Lease.Offer.DomainName() != "" {
+				_, err = fmt.Fprintf(f, "domain %s\n", c.dhcpv4Lease.Offer.DomainName())
+				if err != nil {
+					logger.WithError(err).Error("Giving up on DHCPv4, couldn't prepare resolv.conf")
+					return err
+				}
+			}
+
+			if c.dhcpv4Lease.Offer.DomainSearch() != nil && len(c.dhcpv4Lease.Offer.DomainSearch().Labels) > 0 {
+				_, err = fmt.Fprintf(f, "search %s\n", strings.Join(c.dhcpv4Lease.Offer.DomainSearch().Labels, ", "))
+				if err != nil {
+					logger.WithError(err).Error("Giving up on DHCPv4, couldn't prepare resolv.conf")
+					return err
+				}
+			}
+		}
+	}
+
+	if c.dhcpv6Lease != nil {
+		if len(c.dhcpv6Lease.Options.DNS()) > 0 {
+			for _, nameserver := range c.dhcpv6Lease.Options.DNS() {
+				_, err = fmt.Fprintf(f, "nameserver %s\n", nameserver)
+				if err != nil {
+					logger.WithError(err).Error("Giving up on DHCPv6, couldn't prepare resolv.conf")
+					return err
+				}
+			}
+
+			if c.dhcpv6Lease.Options.DomainSearchList() != nil && len(c.dhcpv6Lease.Options.DomainSearchList().Labels) > 0 {
+				_, err = fmt.Fprintf(f, "search %s\n", strings.Join(c.dhcpv6Lease.Options.DomainSearchList().Labels, ", "))
+				if err != nil {
+					logger.WithError(err).Error("Giving up on DHCPv6, couldn't prepare resolv.conf")
+					return err
+				}
+			}
+		}
+	}
+	return nil
+}
+
 func (c *cmdForknet) runDetach(_ *cobra.Command, args []string) error {
 	daemonPID := args[1]
 	ifName := args[2]