From 21cdbbbc66957cf87a7dc4595d1a2838164fbc16 Mon Sep 17 00:00:00 2001 From: Jian Wang Date: Thu, 18 Jul 2024 20:15:59 +0200 Subject: [PATCH] Retry DHCP option 57 default value when failure happens Signed-off-by: Jian Wang --- pkg/console/install_panels.go | 1 - pkg/console/vip.go | 110 ++++++++++++++++++++++++++++++++++ 2 files changed, 110 insertions(+), 1 deletion(-) diff --git a/pkg/console/install_panels.go b/pkg/console/install_panels.go index 1fdcc19af..caca34002 100644 --- a/pkg/console/install_panels.go +++ b/pkg/console/install_panels.go @@ -2608,7 +2608,6 @@ func configureInstallModeDHCP(c *Console) { c.config.Vip = vip.ipv4Addr c.config.VipHwAddr = vip.hwAddr } - } func checkDHCPHostname(c *config.HarvesterConfig, generate bool) { diff --git a/pkg/console/vip.go b/pkg/console/vip.go index e5a60d5b7..05eb86148 100644 --- a/pkg/console/vip.go +++ b/pkg/console/vip.go @@ -2,10 +2,13 @@ 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" @@ -13,6 +16,7 @@ import ( ) 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 := getIPThroughDHCPWithOptin57(iface, DhcpOption57DefaultValue) + if err1 == nil { + return ip, nil + } + logrus.Infof("dhcp from %s error1 %s error2 %s", iface, err1.Error(), err2.Error()) + return nil, fmt.Errorf("dhcp from %s error1 %w error2 %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 getIPThroughDHCPWithOptin57(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 +}