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package main
import (
"context"
"net"
"net/netip"
"time"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/insomniacslk/dhcp/dhcpv6"
"github.com/insomniacslk/dhcp/dhcpv6/nclient6"
"github.com/insomniacslk/dhcp/iana"
gen "golang.zx2c4.com/wireguard/android/gen"
)
const (
ENABLE_PD = true
)
type dhcp struct {
fqdn string
hwAddr net.HardwareAddr
conn *net.UDPConn
serverAddr net.UDPAddr
client *nclient6.Client
linkAddr net.IP
peerAddr net.IP
}
func newClientIDOpt(duid dhcpv6.DUID) dhcpv4.Option {
iaid := []byte{0, 0, 0, 3}
ident := []byte{255} // Type IAID+DUID
ident = append(ident, iaid...) // IAID
ident = append(ident, duid.ToBytes()...) // DUID
return dhcpv4.OptClientIdentifier(ident)
}
func getDuid(hwAddr net.HardwareAddr) dhcpv6.DUID {
duid := &dhcpv6.DUIDLLT{
HWType: iana.HWTypeEthernet,
Time: uint32(time.Now().Unix()),
LinkLayerAddr: hwAddr,
}
return duid
}
func (d *dhcp) encapSendAndRead(ctx context.Context, msg *dhcpv6.Message, match nclient6.Matcher) (*dhcpv6.Message, error) {
packet, err := dhcpv6.EncapsulateRelay(msg, dhcpv6.MessageTypeRelayForward, d.linkAddr, d.peerAddr)
if err != nil {
return nil, err
}
relay, err := d.client.SendAndReadRelay(ctx, &d.serverAddr, packet, match)
if err != nil {
return nil, err
}
inner, err := relay.GetInnerMessage()
if err != nil {
return nil, err
}
return inner, nil
}
// isRelayMessageType returns a matcher that checks for the message type.
func isRelayMessageType(t dhcpv6.MessageType, tt ...dhcpv6.MessageType) nclient6.Matcher {
return func(p dhcpv6.DHCPv6) bool {
inner, err := p.GetInnerMessage()
if err != nil {
return false
}
if inner.Type() == t {
return true
}
for _, mt := range tt {
if inner.Type() == mt {
return true
}
}
return false
}
}
// func New() *dhcp {
// }
func RunDhcp(ctx context.Context, laddr, raddr netip.Addr) ([]*gen.Lease, error) {
d := &dhcp{}
d.linkAddr = net.ParseIP("fe80::101")
d.peerAddr = net.ParseIP("::1")
// TODO generate hostname and hwAddr from public key
hostName := "foobar"
d.fqdn = hostName + ".m7n.se"
d.hwAddr = []byte{41, 42, 43, 44, 45, 46}
src := net.UDPAddr{IP: laddr.AsSlice(),
Port: 0, // Use non-restrict UDP source port
}
d.serverAddr = net.UDPAddr{IP: raddr.AsSlice(),
Port: 547,
}
err := d.Start(&src)
if err != nil {
return nil, err
}
defer d.Close()
reply, err := d.ObtainLease(ctx) // Use reply
if err != nil {
return nil, err
}
return getAddressesFromReply(reply), nil
}
func getAddressesFromReply(reply *dhcpv6.Message) []*gen.Lease{
var leases []*gen.Lease = make([]*gen.Lease, 0, 4)
if opt := reply.GetOneOption(dhcpv6.OptionIANA); opt != nil {
iana := opt.(*dhcpv6.OptIANA)
ianaOpts := iana.Options.Get(dhcpv6.OptionIAAddr)
for _, opt := range ianaOpts {
addr :=opt.(*dhcpv6.OptIAAddress).IPv6Addr
lease := &gen.Lease{
Address: &gen.InetAddress{
Address: addr,
},
// PreferredLifetime: ,
// ValidLifetime: ,
}
leases = append(leases, lease)
}
}
return leases
}
func (d *dhcp) Start(localAddr *net.UDPAddr) error {
conn, err := net.ListenUDP("udp6", localAddr)
if err != nil {
return err
}
d.client, err = nclient6.NewWithConn(conn, d.hwAddr, nclient6.WithDebugLogger())
return err
}
func (d *dhcp) Close() error {
err := d.client.Close()
d.client = nil
return err
}
func (d *dhcp) ObtainLease(ctx context.Context) (*dhcpv6.Message, error){
duidOpt := dhcpv6.WithClientID(getDuid(d.hwAddr))
fqdnOpt := dhcpv6.WithFQDN(0x1, d.fqdn)
solicit, err := dhcpv6.NewSolicit(d.hwAddr, duidOpt, fqdnOpt, dhcpv6.WithRapidCommit)
if err != nil {
return nil, err
}
msg, err := d.encapSendAndRead(ctx, solicit, isRelayMessageType(dhcpv6.MessageTypeReply, dhcpv6.MessageTypeAdvertise))
if err != nil {
return nil, err
}
if msg.Type() == dhcpv6.MessageTypeReply {
// We got RapidCommitted.
return msg, nil
}
// We didn't get RapidCommitted. Request regular lease.
req, err := dhcpv6.NewRequestFromAdvertise(msg, fqdnOpt)
if err != nil {
return nil, err
}
return d.encapSendAndRead(ctx, req, nil)
}
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