package netboot import ( "errors" "fmt" "log" "time" "github.com/insomniacslk/dhcp/dhcpv6" ) // RequestNetbootv6 sends a netboot request via DHCPv6 and returns the exchanged packets. Additional modifiers // can be passed to manipulate both solicit and advertise packets. func RequestNetbootv6(ifname string, timeout time.Duration, retries int, modifiers ...dhcpv6.Modifier) ([]dhcpv6.DHCPv6, error) { var ( conversation []dhcpv6.DHCPv6 ) modifiers = append(modifiers, dhcpv6.WithNetboot) delay := 2 * time.Second for i := 0; i <= retries; i++ { log.Printf("sending request, attempt #%d", i+1) solicit, err := dhcpv6.NewSolicitForInterface(ifname, modifiers...) if err != nil { return nil, fmt.Errorf("failed to create SOLICIT for interface %s: %v", ifname, err) } client := dhcpv6.NewClient() client.ReadTimeout = timeout conversation, err = client.Exchange(ifname, solicit, modifiers...) if err != nil { log.Printf("Client.Exchange failed: %v", err) log.Printf("sleeping %v before retrying", delay) if i >= retries { // don't wait at the end of the last attempt break } time.Sleep(delay) // TODO add random splay delay = delay * 2 continue } break } return conversation, nil } // ConversationToNetconf extracts network configuration and boot file URL from a // DHCPv6 4-way conversation and returns them, or an error if any. func ConversationToNetconf(conversation []dhcpv6.DHCPv6) (*NetConf, string, error) { var reply dhcpv6.DHCPv6 for _, m := range conversation { // look for a REPLY if m.Type() == dhcpv6.REPLY { reply = m break } } if reply == nil { return nil, "", errors.New("no REPLY received") } netconf, err := GetNetConfFromPacketv6(reply.(*dhcpv6.DHCPv6Message)) if err != nil { return nil, "", fmt.Errorf("cannot get netconf from packet: %v", err) } // look for boot file var ( opt dhcpv6.Option bootfile string ) opt = reply.GetOneOption(dhcpv6.OPT_BOOTFILE_URL) if opt == nil { log.Printf("no bootfile URL option found in REPLY, looking for it in ADVERTISE") // as a fallback, look for bootfile URL in the advertise var advertise dhcpv6.DHCPv6 for _, m := range conversation { // look for an ADVERTISE if m.Type() == dhcpv6.ADVERTISE { advertise = m break } } if advertise == nil { return nil, "", errors.New("no ADVERTISE found") } opt = advertise.GetOneOption(dhcpv6.OPT_BOOTFILE_URL) if opt == nil { return nil, "", errors.New("no bootfile URL option found in ADVERTISE") } } obf := opt.(*dhcpv6.OptBootFileURL) bootfile = string(obf.BootFileURL) return netconf, bootfile, nil }