// newIAAddr creates a IAAddr for a IANA using the specified IPv6 address,
// and advertises it to a client.
func newIAAddr(ia *dhcp6.IANA, ip net.IP, w dhcp6.ResponseSender, r *dhcp6.Request) error {
// Send IPv6 address with 60 second preferred lifetime,
// 90 second valid lifetime, no extra options
iaaddr, err := dhcp6.NewIAAddr(ip, 60*time.Second, 90*time.Second, nil)
if err != nil {
return err
}
// Add IAAddr inside IANA, add IANA to options
_ = ia.Options.Add(dhcp6.OptionIAAddr, iaaddr)
_ = w.Options().Add(dhcp6.OptionIANA, ia)
// Advertise address to soliciting clients
log.Printf("advertising IP: %s", ip)
_, err = w.Send(dhcp6.MessageTypeAdvertise)
return err
}
// handle is a handler which assigns IPv6 addresses using DHCPv6.
func handle(ip net.IP, w dhcp6.ResponseSender, r *dhcp6.Request) error {
// Accept only Solicit, Request, or Confirm, since this server
// does not handle Information Request or other message types
valid := map[dhcp6.MessageType]struct{}{
dhcp6.MessageTypeSolicit: struct{}{},
dhcp6.MessageTypeRequest: struct{}{},
dhcp6.MessageTypeConfirm: struct{}{},
}
if _, ok := valid[r.MessageType]; !ok {
return nil
}
// Make sure client sent a client ID
duid, ok := r.Options.Get(dhcp6.OptionClientID)
if !ok {
return nil
}
// Log information about the incoming request.
log.Printf("[%s] id: %s, type: %d, len: %d, tx: %s",
hex.EncodeToString(duid),
r.RemoteAddr,
r.MessageType,
r.Length,
hex.EncodeToString(r.TransactionID[:]),
)
// Print out options the client has requested
if opts, ok, err := r.Options.OptionRequest(); err == nil && ok {
log.Println("\t- requested:")
for _, o := range opts {
log.Printf("\t\t - %s", o)
}
}
// Client must send a IANA to retrieve an IPv6 address
ianas, ok, err := r.Options.IANA()
if err != nil {
return err
}
if !ok {
log.Println("no IANAs provided")
return nil
}
// Only accept one IANA
if len(ianas) > 1 {
log.Println("can only handle one IANA")
return nil
}
ia := ianas[0]
log.Printf("\tIANA: %s (%s, %s), opts: %v",
hex.EncodeToString(ia.IAID[:]),
ia.T1,
ia.T2,
ia.Options,
)
// Instruct client to prefer this server unconditionally
_ = w.Options().Add(dhcp6.OptionPreference, dhcp6.Preference(255))
// IANA may already have an IAAddr if an address was already assigned.
// If not, assign a new one.
iaaddrs, ok, err := ia.Options.IAAddr()
if err != nil {
return err
}
// Client did not indicate a previous address, and is soliciting.
// Advertise a new IPv6 address.
if !ok && r.MessageType == dhcp6.MessageTypeSolicit {
return newIAAddr(ia, ip, w, r)
} else if !ok {
// Client did not indicate an address and is not soliciting. Ignore.
return nil
}
// Confirm or renew an existing IPv6 address
// Must have an IAAddr, but we ignore if more than one is present
if len(iaaddrs) == 0 {
return nil
}
iaa := iaaddrs[0]
log.Printf("\t\tIAAddr: %s (%s, %s), opts: %v",
iaa.IP,
iaa.PreferredLifetime,
iaa.ValidLifetime,
iaa.Options,
)
// Add IAAddr inside IANA, add IANA to options
_ = ia.Options.Add(dhcp6.OptionIAAddr, iaa)
_ = w.Options().Add(dhcp6.OptionIANA, ia)
// Send reply to client
_, err = w.Send(dhcp6.MessageTypeReply)
return err
}
// solicit is a function which can be adapted as a HandlerFunc.
func solicit(w dhcp6.ResponseSender, r *dhcp6.Request) {
w.Send(dhcp6.MessageTypeAdvertise)
}