Retry DHCP option 57 default value when failure happens

Signed-off-by: Jian Wang <jian.wang@suse.com>

pkg/console/install_panels.go

@@ -2615,7 +2615,6 @@ func configureInstallModeDHCP(c *Console) {
 		c.config.Vip = vip.ipv4Addr
 		c.config.VipHwAddr = vip.hwAddr
 	}
-
 }
 
 func checkDHCPHostname(c *config.HarvesterConfig, generate bool) {

pkg/console/vip.go

@@ -2,17 +2,21 @@ package console
 
 import (
 	"context"
+	"fmt"
 	"net"
 	"strconv"
+	"time"
 
 	gocommon "github.com/harvester/go-common"
+	"github.com/insomniacslk/dhcp/dhcpv4"
 	"github.com/insomniacslk/dhcp/dhcpv4/nclient4"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/vishvananda/netlink"
 )
 
 const tempMacvlanPrefix = "macvlan-"
+const DhcpOption57DefaultValue = 576
 
 type vipAddr struct {
 	hwAddr   string
@@ -80,6 +84,23 @@ func getVipThroughDHCP(iface string) (*vipAddr, error) {
 }
 
 func getIPThroughDHCP(iface string) (net.IP, error) {
+	// original solution, with option57 1500
+	ip, err1 := getIPThroughDHCPOriginal(iface)
+	if err1 == nil {
+		return ip, nil
+	}
+
+	// some DHCP servers may fail with the above option, try again with the default value
+	ip, err2 := getIPThroughDHCPWithOption57(iface, DhcpOption57DefaultValue)
+	if err2 == nil {
+		return ip, nil
+	}
+	logrus.Infof("dhcp from %s option57 value max %s default %s", iface, err1.Error(), err2.Error())
+	return nil, fmt.Errorf("dhcp from %s option57 value max %w default %w", iface, err1, err2)
+}
+
+// original code
+func getIPThroughDHCPOriginal(iface string) (net.IP, error) {
 	broadcast, err := nclient4.New(iface)
 	if err != nil {
 		return nil, err
@@ -95,3 +116,92 @@ func getIPThroughDHCP(iface string) (net.IP, error) {
 
 	return lease.Offer.YourIPAddr, nil
 }
+
+func getIPThroughDHCPWithOption57(iface string, msz uint16) (net.IP, error) {
+	broadcast, err := nclient4.New(iface)
+	if err != nil {
+		return nil, err
+	}
+	defer broadcast.Close()
+
+	// if this param is not set, use the original default value
+	if msz == 0 || msz > nclient4.MaxMessageSize {
+		msz = nclient4.MaxMessageSize
+	} else if msz < DhcpOption57DefaultValue {
+		msz = DhcpOption57DefaultValue
+	}
+
+	lease, err := request(broadcast, context.TODO(), uint16(msz))
+	if err != nil {
+		return nil, err
+	}
+
+	logrus.Info(lease)
+
+	return lease.Offer.YourIPAddr, nil
+}
+
+// below code is copied from
+// https://github.com/insomniacslk/dhcp/blob/master/dhcpv4/nclient4/client.go#L38
+// but use a smaller OptMaxMessageSize
+
+func request(c *nclient4.Client, ctx context.Context, msz uint16, modifiers ...dhcpv4.Modifier) (lease *nclient4.Lease, err error) {
+
+	offer, err := discoverOffer(c, ctx, msz, modifiers...)
+	if err != nil {
+		err = fmt.Errorf("unable to receive an offer: %w", err)
+		return
+	}
+	return requestFromOffer(c, ctx, msz, offer, modifiers...)
+}
+
+// DiscoverOffer sends a DHCPDiscover message and returns the first valid offer
+// received.
+func discoverOffer(c *nclient4.Client, ctx context.Context, msz uint16, modifiers ...dhcpv4.Modifier) (offer *dhcpv4.DHCPv4, err error) {
+	// RFC 2131, Section 4.4.1, Table 5 details what a DISCOVER packet should
+	// contain.
+	discover, err := dhcpv4.NewDiscovery(c.InterfaceAddr(), dhcpv4.PrependModifiers(modifiers,
+		dhcpv4.WithOption(dhcpv4.OptMaxMessageSize(msz)))...)
+	if err != nil {
+		return nil, fmt.Errorf("unable to create a DHCP discovery request: %w", err)
+	}
+
+	offer, err = c.SendAndRead(ctx, c.RemoteAddr(), discover, nclient4.IsMessageType(dhcpv4.MessageTypeOffer))
+	if err != nil {
+		return nil, fmt.Errorf("got an error while the DHCP discovery request: %w", err)
+	}
+	return offer, nil
+}
+
+// RequestFromOffer sends a Request message and waits for an response.
+// It assumes the SELECTING state by default, see Section 4.3.2 in RFC 2131 for more details.
+func requestFromOffer(c *nclient4.Client, ctx context.Context, msz uint16, offer *dhcpv4.DHCPv4, modifiers ...dhcpv4.Modifier) (*nclient4.Lease, error) {
+	// TODO(chrisko): should this be unicast to the server?
+	request, err := dhcpv4.NewRequestFromOffer(offer, dhcpv4.PrependModifiers(modifiers,
+		dhcpv4.WithOption(dhcpv4.OptMaxMessageSize(msz)))...)
+	if err != nil {
+		return nil, fmt.Errorf("unable to create a DHCP request: %w", err)
+	}
+
+	// Servers are supposed to only respond to Requests containing their server identifier,
+	// but sometimes non-compliant servers respond anyway.
+	// Clients are not required to validate this field, but servers are required to
+	// include the server identifier in their Offer per RFC 2131 Section 4.3.1 Table 3.
+	response, err := c.SendAndRead(ctx, c.RemoteAddr(), request, nclient4.IsAll(
+		nclient4.IsCorrectServer(offer.ServerIdentifier()),
+		nclient4.IsMessageType(dhcpv4.MessageTypeAck, dhcpv4.MessageTypeNak)))
+	if err != nil {
+		return nil, fmt.Errorf("got an error while processing the DHCP request: %w", err)
+	}
+	if response.MessageType() == dhcpv4.MessageTypeNak {
+		return nil, &nclient4.ErrNak{
+			Offer: offer,
+			Nak:   response,
+		}
+	}
+	lease := &nclient4.Lease{}
+	lease.ACK = response
+	lease.Offer = offer
+	lease.CreationTime = time.Now()
+	return lease, nil
+}