common IPv4/IPv6 fields and that being part of the decoder

Are you still saying it's "not efficient"?

Here's my notes:

```
/* TOS

RFC 2474 explains how the byte (octet) used in IPv6 and IPv4 headers is allocated for describing the TOS "value or desire or wish" set by the origin or a router in the path to the destination of the packet

A replacement header field, called the DS field, is defined, which is
intended to supersede the existing definitions of the IPv4 TOS octet
[RFC791] and the IPv6 Traffic Class octet [IPv6].

Gopacket says - https://pkg.go.dev/github.com/google/gopacket/layers#TCP

type TCP struct {
BaseLayer
SrcPort, DstPort TCPPort
Seq uint32
Ack uint32
DataOffset uint8
FIN, SYN, RST, PSH, ACK, URG, ECE, CWR, NS bool
Window uint16
Checksum uint16
Urgent uint16

Options []TCPOption
Padding []byte
// contains filtered or unexported fields
}

I guess they don't know best that we should use RFC 2474 and that "stuff" is like gimme 100 monies or "what is that, are you serious?"

They sure do provide the URG flag though, and that should be important like TOS

// you can get the TOS byte here
// as a uint8, imagine that!

IPv4 - https://github.com/google/gopacket/blob/master/layers/ip4.go#L47

// IPv4 is the header of an IP packet.
type IPv4 struct {
BaseLayer
Version uint8
IHL uint8
TOS uint8
Length uint16
Id uint16
Flags IPv4Flag
FragOffset uint16
TTL uint8
Protocol IPProtocol
Checksum uint16
SrcIP net.IP
DstIP net.IP
Options []IPv4Option
Padding []byte
}

IPv6 - https://github.com/google/gopacket/blob/master/layers/ip6.go#L33
// that well must be pumping for school

type IPv6 struct {
// http://www.networksorcery.com/enp/protocol/ipv6.htm
BaseLayer
Version uint8
TrafficClass uint8
FlowLabel uint32
Length uint16
NextHeader IPProtocol
HopLimit uint8
SrcIP net.IP
DstIP net.IP
HopByHop *IPv6HopByHop
// hbh will be pointed to by HopByHop if that layer exists.
hbh IPv6HopByHop
}

*/

// write the TOS stuff from the IP
```