reordering, formatting, some tests

.gitignore

@@ -1,5 +1,6 @@
 config.ini
 Makefile
+logs/
 
 # Created by https://www.toptal.com/developers/gitignore/api/intellij+all,go
 # Edit at https://www.toptal.com/developers/gitignore?templates=intellij+all,go

config/builder.go

@@ -26,6 +26,14 @@ func (c Configuration) Build() (*proxy.Proxy, error) {
 	p := proxy.Proxy{}
 	p.Generator = UselessMac(false)
 
+	ss, err := tun.NewTun("nc%d", 1500)
+	if err != nil {
+		return nil, err
+	}
+
+	p.Source = ss
+	p.Sink = ss
+
 	for _, peer := range c.Peers {
 		p.Verifiers = append(p.Verifiers, UselessMac(true))
 
@@ -40,14 +48,6 @@ func (c Configuration) Build() (*proxy.Proxy, error) {
 		}
 	}
 
-	ss, err := tun.NewTun("nc%d", 1500)
-	if err != nil {
-		return nil, err
-	}
-
-	p.Source = ss
-	p.Sink = ss
-
 	return &p, nil
 }
 

config/loader.go

@@ -7,8 +7,8 @@ import (
 func LoadConfig(path string) (c Configuration, err error) {
 	var file *ini.File
 	file, err = ini.LoadSources(ini.LoadOptions{
-		AllowShadows:                true,
-		AllowNonUniqueSections:      true,
+		AllowShadows:           true,
+		AllowNonUniqueSections: true,
 	}, path)
 	if err != nil {
 		return

go.mod

@@ -5,5 +5,6 @@ go 1.15
 require (
 	github.com/go-playground/validator/v10 v10.4.1
 	github.com/pkg/taptun v0.0.0-20160424131934-bbbd335672ab
+	github.com/stretchr/testify v1.4.0
 	gopkg.in/ini.v1 v1.62.0
 )

main.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"fmt"
+	"log"
 	"mpbl3p/config"
 	"os"
 	"os/signal"
@@ -9,23 +9,25 @@ import (
 )
 
 func main() {
-	fmt.Println("loading config...")
+	log.SetFlags(log.Ldate | log.Ltime | log.Llongfile)
+
+	log.Println("loading config...")
 
 	c, err := config.LoadConfig("config.ini")
 	if err != nil {
 		panic(err)
 	}
 
-	fmt.Println("building config...")
+	log.Println("building config...")
 	p, err := c.Build()
 	if err != nil {
 		panic(err)
 	}
 
-	fmt.Println("starting...")
+	log.Println("starting...")
 	p.Start()
 
-	fmt.Println("running")
+	log.Println("running")
 
 	signals := make(chan os.Signal)
 	signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT)

proxy/packet.go

@@ -13,7 +13,7 @@ type Packet struct {
 // create a packet from the raw data of an IP packet
 func NewPacket(data []byte) Packet {
 	return Packet{
-		Data: data,
+		Data:      data,
 		timestamp: time.Now(),
 	}
 }
@@ -29,7 +29,7 @@ func UnmarshalPacket(raw []byte, verifier MacVerifier) (Packet, error) {
 	}
 
 	p := Packet{
-		Data: data[:8],
+		Data: data[:len(data)-8],
 	}
 
 	unixTime := int64(binary.LittleEndian.Uint64(data[len(data)-8:]))

proxy/packet_test.go

@@ -0,0 +1,50 @@
+package proxy
+
+import (
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+type AlmostUselessMac bool
+
+func (AlmostUselessMac) CodeLength() int {
+	return 4
+}
+
+func (AlmostUselessMac) Generate([]byte) []byte {
+	return []byte{'a', 'b', 'c', 'd'}
+}
+
+func (u AlmostUselessMac) Verify(_, sum []byte) error {
+	if !(sum[0] == 'a' && sum[1] == 'b' && sum[2] == 'c' && sum[3] == 'd') {
+		return ErrBadChecksum
+	}
+	return nil
+}
+
+func TestPacket_Marshal(t *testing.T) {
+	testContent := []byte("A test string is the content of this packet.")
+	testPacket := NewPacket(testContent)
+	testMac := AlmostUselessMac(false)
+
+	t.Run("Length", func(t *testing.T) {
+		marshalled := testPacket.Marshal(testMac)
+
+		assert.Len(t, marshalled, len(testContent)+8+4)
+	})
+}
+
+func TestUnmarshalPacket(t *testing.T) {
+	testContent := []byte("A test string is the content of this packet.")
+	testPacket := NewPacket(testContent)
+	testMac := AlmostUselessMac(false)
+	testMarshalled := testPacket.Marshal(testMac)
+
+	t.Run("Success", func(t *testing.T) {
+		content, err := UnmarshalPacket(testMarshalled, testMac)
+
+		require.Nil(t, err)
+		assert.Equal(t, testContent, content.Raw())
+	})
+}

proxy/proxy.go

@@ -1,6 +1,8 @@
 package proxy
 
-import "fmt"
+import (
+	"log"
+)
 
 type Producer interface {
 	IsAlive() bool
@@ -44,6 +46,7 @@ func (p *Proxy) Start() {
 				panic(err)
 				return
 			} else {
+				log.Println("proxy received packet from source")
 				p.proxyChan <- packet
 			}
 		}
@@ -55,23 +58,26 @@ func (p *Proxy) Start() {
 		go func() {
 			for c.IsAlive() {
 				if err := c.Consume(<-p.proxyChan, p.Generator); err != nil {
-					fmt.Println(err)
+					log.Println(err)
 					return
+				} else {
+					log.Println("proxy consumed a packet")
 				}
 			}
 		}()
 	}
 
 	for i, prod := range p.Producers {
-		i := i
+		verifier := p.Verifiers[i]
 		prod := prod
 
 		go func() {
 			for prod.IsAlive() {
-				if packet, err := prod.Produce(p.Verifiers[i]); err != nil {
-					fmt.Println(err)
+				if packet, err := prod.Produce(verifier); err != nil {
+					log.Println(err)
 					return
 				} else {
+					log.Println("proxy received a packet from a producer")
 					p.sinkChan <- packet
 				}
 			}
@@ -84,7 +90,9 @@ func (p *Proxy) Start() {
 			if err := p.Sink.Sink(packet); err != nil {
 				panic(err)
 				return
+			} else {
+				log.Println("proxy sent packet via sink")
 			}
 		}
 	}()
-}
+}

tcp/flow.go

@@ -19,7 +19,7 @@ type Flow struct {
 
 func NewFlow(local, remote string) (Flow, error) {
 	f := Flow{
-		Local: local,
+		Local:  local,
 		Remote: remote,
 	}
 
@@ -67,7 +67,7 @@ func (f *Flow) Consume(p proxy.Packet, g proxy.MacGenerator) error {
 func (f *Flow) consumeMarshalled(data []byte) error {
 	prefixedData := make([]byte, len(data)+4)
 	binary.LittleEndian.PutUint32(prefixedData, uint32(len(data)))
-	copy(prefixedData[4:], data)
+	copy(prefixedData[:len(prefixedData)-4], data)
 
 	_, err := f.conn.Write(prefixedData)
 	return err
@@ -82,7 +82,7 @@ func (f *Flow) Produce(v proxy.MacVerifier) (proxy.Packet, error) {
 	return proxy.UnmarshalPacket(data, v)
 }
 
-func (f *Flow) produceMarshalled() ([]byte,error) {
+func (f *Flow) produceMarshalled() ([]byte, error) {
 	lengthBytes := make([]byte, 4)
 	if n, err := io.LimitReader(f.conn, 4).Read(lengthBytes); err != nil {
 		return nil, err
@@ -99,4 +99,4 @@ func (f *Flow) produceMarshalled() ([]byte,error) {
 	}
 
 	return dataBytes, nil
-}
+}

tcp/receiver.go

@@ -1,7 +1,7 @@
 package tcp
 
 import (
-	"fmt"
+	"log"
 	"mpbl3p/proxy"
 	"mpbl3p/utils"
 	"net"
@@ -15,7 +15,7 @@ type Receiver struct {
 }
 
 func NewReceiver(local string) (*Receiver, error) {
-	r := Receiver{}
+	r := Receiver{flows: make(map[int]Flow)}
 
 	laddr, err := net.ResolveTCPAddr("tcp", local)
 	if err != nil {
@@ -70,7 +70,7 @@ func (r *Receiver) addFlow(flow Flow) {
 		for flow.IsAlive() {
 			d, err := flow.produceMarshalled()
 			if err != nil {
-				fmt.Println(err)
+				log.Println(err)
 				continue
 			}
 			r.inPackets <- d
@@ -83,7 +83,7 @@ func (r *Receiver) addFlow(flow Flow) {
 			d := <-r.outPackets
 			err := flow.consumeMarshalled(d)
 			if err != nil {
-				fmt.Println(err)
+				log.Println(err)
 				// continue
 			}
 		}

utils/utils.go

@@ -10,4 +10,4 @@ func init() {
 			i += 1
 		}
 	}()
-}
+}