dissertation-2-code/config/builder.go

package config

import (
	"fmt"
	"mpbl3p/proxy"
	"mpbl3p/tcp"
	"mpbl3p/tun"
	"mpbl3p/udp"
	"mpbl3p/udp/congestion"
	"time"
)

// TODO: Delete this code as soon as an alternative is available
type UselessMac struct{}

func (UselessMac) CodeLength() int {
	return 0
}

func (UselessMac) Generate([]byte) []byte {
	return nil
}

func (u UselessMac) Verify([]byte, []byte) error {
	return nil
}

func (c Configuration) Build() (*proxy.Proxy, error) {
	p := proxy.NewProxy(0)
	p.Generator = UselessMac{}

	if c.Host.InterfaceName == "" {
		c.Host.InterfaceName = "nc%d"
	}

	ss, err := tun.NewTun(c.Host.InterfaceName, 1500)
	if err != nil {
		return nil, err
	}

	p.Source = ss
	p.Sink = ss

	for _, peer := range c.Peers {
		switch peer.Method {
		case "TCP":
			err := buildTcp(p, peer)
			if err != nil {
				return nil, err
			}
		case "UDP":
			err := buildUdp(p, peer)
			if err != nil {
				return nil, err
			}
		}
	}

	return p, nil
}

func buildTcp(p *proxy.Proxy, peer Peer) error {
	if peer.RemoteHost != "" {
		f, err := tcp.InitiateFlow(
			fmt.Sprintf("%s:", peer.LocalHost),
			fmt.Sprintf("%s:%d", peer.RemoteHost, peer.RemotePort),
		)

		if err != nil {
			return err
		}

		p.AddConsumer(f)
		p.AddProducer(f, UselessMac{})

		return nil
	}

	err := tcp.NewListener(p, fmt.Sprintf("%s:%d", peer.LocalHost, peer.LocalPort), UselessMac{})
	if err != nil {
		return err
	}

	return nil
}

func buildUdp(p *proxy.Proxy, peer Peer) error {
	var c func() udp.Congestion
	switch peer.Congestion {
	case "None":
		c = func() udp.Congestion { return congestion.NewNone() }
	default:
		fallthrough
	case "NewReno":
		c = func() udp.Congestion { return congestion.NewNewReno() }
	}

	if peer.RemoteHost != "" {
		f, err := udp.InitiateFlow(
			fmt.Sprintf("%s:", peer.LocalHost),
			fmt.Sprintf("%s:%d", peer.RemoteHost, peer.RemotePort),
			UselessMac{},
			UselessMac{},
			c(),
			time.Duration(peer.KeepAlive)*time.Second,
		)

		if err != nil {
			return err
		}

		p.AddConsumer(f)
		p.AddProducer(f, UselessMac{})

		return nil
	}

	err := udp.NewListener(
		p,
		fmt.Sprintf("%s:%d", peer.LocalHost, peer.LocalPort),
		UselessMac{},
		UselessMac{},
		c,
	)
	if err != nil {
		return err
	}

	return nil
}