dissertation-2-code/proxy/packet.go

package proxy

import "mpbl3p/shared"

type Packet interface {
	Marshal() []byte
	Contents() []byte
}

type SimplePacket []byte

// get the raw data of the IP packet
func (p SimplePacket) Marshal() []byte {
	return p
}

func (p SimplePacket) Contents() []byte {
	return p
}

func AppendMac(b []byte, g MacGenerator) []byte {
	mac := g.Generate(b)
	return append(b, mac...)
}

func StripMac(b []byte, v MacVerifier) ([]byte, error) {
	if len(b) < v.CodeLength() {
		return nil, shared.ErrNotEnoughBytes
	}

	data := b[:len(b)-v.CodeLength()]
	sum := b[len(b)-v.CodeLength():]

	if err := v.Verify(data, sum); err != nil {
		return nil, err
	}

	return data, nil
}