func (dp *DhcpPacket) ConstructWithPreAllocatedBuffer(buffer []byte, msgType option.MessageType) (err error) {
if cap(buffer) < 1500 {
buffer = make([]byte, 241, 1500)
} else if len(buffer) != 241 {
buffer = buffer[:241]
}
dp.Raw = buffer
dp.SetHardwareType(byte(1))
dp.SetHardwareLength(byte(6))
dp.SetMagicCookie()
err = dp.ResetAllOptions()
if err != nil {
return err
}
opt53 := new(option.Option53MessageType)
opt53.Construct(msgType)
dp.AddOption(opt53)
switch msgType {
case option.DHCPDISCOVER:
fallthrough
case option.DHCPREQUEST:
fallthrough
case option.DHCPDECLINE:
fallthrough
case option.DHCPRELEASE:
dp.SetOpCode(OP_BOOTREQUEST)
// break
case option.DHCPOFFER:
fallthrough
case option.DHCPACK:
fallthrough
case option.DHCPNAK:
dp.SetOpCode(OP_BOOTREPLY)
// break
}
return nil
}
