New Project Structure - Encryption From and to Server

.gitignore

@@ -1,5 +1,3 @@
 bin/
-testFile
-testFile.recv
-testFile2
+testFiles/
 out/

Makefile

@@ -2,4 +2,7 @@ build:
 	go build -o bin/helloGo main.go client.go packets.go server.go
 
 server:
-	go run main.go server.go client.go packets.go server 
+	go run main.go server 
+
+test:
+	go run main.go client testFiles/testFile

client.go

@@ -1,181 +0,0 @@
-package main
-
-import (
-	"crypto/rand"
-	"encoding/hex"
-	"fmt"
-	"net"
-	"os"
-	"sort"
-	"time"
-)
-
-func SendPacket(pck *Packet, key [32]byte, conn *net.UDPConn) {
-	secPck := NewSymetricSecurePacket(key, pck)
-	fmt.Println(secPck)
-	if _, err := conn.Write(secPck.ToBytes()); err != nil {
-		panic(err)
-	}
-}
-
-func GetFile(path string) {
-	request := NewRequest(path)
-
-	k := make([]byte, 32)
-	_, err := rand.Read(k)
-	if err != nil {
-		panic(err)
-	}
-	key := [32]byte(k)
-	keyExchangePck := NewRsaPacket(request.sid, key)
-
-	udpAddr, err := net.ResolveUDPAddr("udp", "0.0.0.0:13374")
-	// udpAddr, err := net.ResolveUDPAddr("udp", "192.168.2.145:13374")
-
-	if err != nil {
-		fmt.Println(err)
-		os.Exit(1)
-	}
-
-	// Dial to the address with UDP
-	conn, err := net.DialUDP("udp", nil, udpAddr)
-
-	if err != nil {
-		fmt.Println(err)
-		os.Exit(1)
-	}
-
-	_, err = conn.Write(keyExchangePck.ToBytes())
-	if err != nil {
-		panic(err)
-	}
-
-	SendPacket(request, key, conn)
-
-	bytes := make([]byte, PacketSize)
-	file, err := os.Create("out/" + hex.EncodeToString(request.sid[:]) + ".recv")
-	if err != nil {
-		panic(err)
-	}
-
-	_, _, err = conn.ReadFrom(bytes)
-	if err != nil {
-		panic(err)
-	}
-
-	pck := PacketFromBytes(bytes)
-	if pck.flag != PTE {
-		panic("Header flag was supposed to be PTE")
-	}
-
-	size, err := pck.GetUint32Payload()
-	if err != nil {
-		panic(err)
-	}
-
-	file.Truncate(int64(size))
-
-	ackPck := NewAck(&pck)
-	SendPacket(ackPck, key, conn)
-
-	recvPackets := make([]uint32, 0)
-	var endPacket Packet
-
-	for {
-		_, _, err = conn.ReadFrom(bytes)
-		if err != nil {
-			panic(err)
-		}
-
-		pck := PacketFromBytes(bytes)
-		if pck.flag == End {
-			endPacket = pck
-			break
-		}
-		recvPackets = append(recvPackets, pck.sync)
-
-		offset := (int64(pck.sync) - int64(ackPck.sync+1)) * (PacketSize - int64(HeaderSize))
-		fmt.Printf("Sync: %v, Offset: %v\n", pck.sync, offset)
-
-		_, err = file.WriteAt(pck.data, offset)
-		if err != nil {
-			panic(err)
-		}
-	}
-
-	sort.Slice(recvPackets, func(i, j int) bool {
-		pckI := recvPackets[i]
-		pckJ := recvPackets[j]
-		return pckI < pckJ
-	})
-
-	lostPackets := make([]uint32, 0)
-
-	for i := ackPck.sync + 1; i < endPacket.sync; i++ {
-		if b, _ := contains(recvPackets, i); !b {
-			lostPackets = append(lostPackets, i)
-		}
-	}
-
-	for _, i := range lostPackets {
-		fmt.Println(i)
-	}
-
-	lastPacket := ackPck
-
-	for {
-		if len(lostPackets) == 0 {
-			break
-		}
-
-		for _, sync := range lostPackets {
-
-			fmt.Printf("Request resend for %v\n", sync)
-			resend := NewResend(uint32(sync), lastPacket)
-			SendPacket(resend, key, conn)
-			lastPacket = resend
-
-			conn.SetReadDeadline(time.Now().Add(10 * time.Second))
-
-			_, _, err = conn.ReadFrom(bytes)
-			if err != nil {
-				if e, ok := err.(net.Error); !ok || !e.Timeout() {
-					// If it's not a timeout, log the error as usual
-					panic(err)
-				}
-				continue
-			}
-
-			pck := PacketFromBytes(bytes)
-			offset := (int64(pck.sync) - int64(ackPck.sync+1)) * (PacketSize - int64(HeaderSize))
-			// fmt.Printf("Sync: %v, Offset: %v\n", pck.sync, offset)
-
-			_, err = file.WriteAt(pck.data, offset)
-			if err != nil {
-				panic(err)
-			}
-
-			_, index := contains(lostPackets, pck.sync)
-			fmt.Printf("Removing sync %v from LostPackets\n", pck.sync)
-			lostPackets = remove(lostPackets, index)
-
-		}
-	}
-
-	ack := NewAck(&endPacket)
-	SendPacket(ack, key, conn)
-}
-
-func remove(s []uint32, i int) []uint32 {
-	s[i] = s[len(s)-1]
-	return s[:len(s)-1]
-}
-
-func contains(s []uint32, e uint32) (bool, int) {
-	for i, a := range s {
-		if a == e {
-			return true, i
-		}
-	}
-	return false, 0
-}

go.mod

@@ -2,6 +2,8 @@ module pablu/uftp
 
 go 1.21.1
 
-require golang.org/x/crypto v0.15.0
+replace internal/common => ./internal/common
 
-require golang.org/x/sys v0.14.0 // indirect
+replace internal/client => ./internal/client
+
+replace internal/server => ./internal/server

go.sum

@@ -1,4 +0,0 @@
-golang.org/x/crypto v0.15.0 h1:frVn1TEaCEaZcn3Tmd7Y2b5KKPaZ+I32Q2OA3kYp5TA=
-golang.org/x/crypto v0.15.0/go.mod h1:4ChreQoLWfG3xLDer1WdlH5NdlQ3+mwnQq1YTKY+72g=
-golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
-golang.org/x/sys v0.14.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

go.work

@@ -0,0 +1,8 @@
+go 1.21.1
+
+use (
+	.
+	./internal/client
+	./internal/common
+	./internal/server
+)

internal/client/client.go

@@ -0,0 +1,211 @@
+package client
+
+import (
+	"common"
+	"crypto/rand"
+	"encoding/hex"
+	"fmt"
+	"net"
+	"os"
+	"sort"
+	"time"
+)
+
+func SendPacket(pck *common.Packet, key [32]byte, conn *net.UDPConn) {
+	secPck := common.NewSymetricSecurePacket(key, pck)
+	if _, err := conn.Write(secPck.ToBytes()); err != nil {
+		panic(err)
+	}
+}
+
+func ReceivePacket(key [32]byte, conn *net.UDPConn) common.Packet {
+	bytes := make([]byte, common.PacketSize+common.SecureHeaderSize)
+	_, _, err := conn.ReadFrom(bytes)
+	if err != nil {
+		panic(err)
+	}
+
+	secPck := common.SecurePacketFromBytes(bytes)
+	pck, err := secPck.ExtractPacket(key)
+
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Printf("Decrypted Packet, Sync: %v, Type: %v\n", pck.Sync, pck.Flag)
+
+	return pck
+}
+
+func ReceivePacketWithTimeout(key [32]byte, conn *net.UDPConn) (common.Packet, bool) {
+	conn.SetReadDeadline(time.Now().Add(10 * time.Second))
+
+	bytes := make([]byte, common.PacketSize)
+
+	_, _, err := conn.ReadFrom(bytes)
+	if err != nil {
+		if e, ok := err.(net.Error); !ok || !e.Timeout() {
+			// If it's not a timeout, log the error as usual
+			panic(err)
+		}
+
+		return common.Packet{}, false
+	}
+
+	secPck := common.SecurePacketFromBytes(bytes)
+	pck, err := secPck.ExtractPacket(key)
+	if err != nil {
+		panic(err)
+	}
+
+	return pck, true
+}
+
+func GetFile(path string) {
+	request := common.NewRequest(path)
+
+	k := make([]byte, 32)
+	_, err := rand.Read(k)
+	if err != nil {
+		panic(err)
+	}
+	key := [32]byte(k)
+	keyExchangePck := common.NewRsaPacket(request.Sid, key)
+
+	udpAddr, err := net.ResolveUDPAddr("udp", "0.0.0.0:13374")
+	// udpAddr, err := net.ResolveUDPAddr("udp", "192.168.2.145:13374")
+
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	// Dial to the address with UDP
+	conn, err := net.DialUDP("udp", nil, udpAddr)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	_, err = conn.Write(keyExchangePck.ToBytes())
+	if err != nil {
+		panic(err)
+	}
+
+	SendPacket(request, key, conn)
+
+	file, err := os.Create("out/" + hex.EncodeToString(request.Sid[:]) + ".recv")
+	if err != nil {
+		panic(err)
+	}
+
+	pck := ReceivePacket(key, conn)
+	if pck.Flag != common.PTE {
+		panic("Header flag was supposed to be PTE")
+	}
+
+	size, err := pck.GetUint32Payload()
+	if err != nil {
+		panic(err)
+	}
+
+	file.Truncate(int64(size))
+
+	ackPck := common.NewAck(&pck)
+	SendPacket(ackPck, key, conn)
+
+	recvPackets := make([]uint32, 0)
+	var endPacket common.Packet
+
+	for {
+		pck := ReceivePacket(key, conn)
+		if pck.Flag == common.End {
+			endPacket = pck
+			break
+		}
+		if pck.Flag != common.File {
+			fmt.Printf("Received %v Packet, but expected File Packet\n", pck.Flag)
+			continue
+		}
+
+		recvPackets = append(recvPackets, pck.Sync)
+
+		offset := (int64(pck.Sync) - int64(ackPck.Sync+1)) * (common.PacketSize - int64(common.HeaderSize))
+		// fmt.Printf("Sync: %v, Offset: %v\n", pck.Sync, offset)
+
+		_, err = file.WriteAt(pck.Data, offset)
+		if err != nil {
+			panic(err)
+		}
+	}
+
+	sort.Slice(recvPackets, func(i, j int) bool {
+		pckI := recvPackets[i]
+		pckJ := recvPackets[j]
+		return pckI < pckJ
+	})
+
+	lostPackets := make([]uint32, 0)
+
+	for i := ackPck.Sync + 1; i < endPacket.Sync; i++ {
+		if b, _ := contains(recvPackets, i); !b {
+			lostPackets = append(lostPackets, i)
+		}
+	}
+
+	for _, i := range lostPackets {
+		fmt.Println(i)
+	}
+
+	lastPacket := ackPck
+
+	for {
+		if len(lostPackets) == 0 {
+			break
+		}
+
+		for _, sync := range lostPackets {
+
+			fmt.Printf("Request resend for %v\n", sync)
+			resend := common.NewResend(uint32(sync), lastPacket)
+			SendPacket(resend, key, conn)
+			lastPacket = resend
+
+			pck, received := ReceivePacketWithTimeout(key, conn)
+
+			if !received {
+				continue
+			}
+
+			offset := (int64(pck.Sync) - int64(ackPck.Sync+1)) * (common.PacketSize - int64(common.HeaderSize))
+			// fmt.Printf("Sync: %v, Offset: %v\n", pck.sync, offset)
+
+			_, err = file.WriteAt(pck.Data, offset)
+			if err != nil {
+				panic(err)
+			}
+
+			_, index := contains(lostPackets, pck.Sync)
+			fmt.Printf("Removing sync %v from LostPackets\n", pck.Sync)
+			lostPackets = remove(lostPackets, index)
+
+		}
+	}
+
+	ack := common.NewAck(&endPacket)
+	SendPacket(ack, key, conn)
+}
+
+func remove(s []uint32, i int) []uint32 {
+	s[i] = s[len(s)-1]
+	return s[:len(s)-1]
+}
+
+func contains(s []uint32, e uint32) (bool, int) {
+	for i, a := range s {
+		if a == e {
+			return true, i
+		}
+	}
+	return false, 0
+}

internal/client/go.mod

@@ -0,0 +1,3 @@
+module client
+
+go 1.21.1

internal/common/go.mod

@@ -0,0 +1,7 @@
+module common
+
+go 1.21.1
+
+require golang.org/x/crypto v0.15.0
+
+require golang.org/x/sys v0.14.0 // indirect

internal/common/go.sum

@@ -0,0 +1,4 @@
+golang.org/x/crypto v0.15.0 h1:frVn1TEaCEaZcn3Tmd7Y2b5KKPaZ+I32Q2OA3kYp5TA=
+golang.org/x/crypto v0.15.0/go.mod h1:4ChreQoLWfG3xLDer1WdlH5NdlQ3+mwnQq1YTKY+72g=
+golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
+golang.org/x/sys v0.14.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

internal/common/packets.go

@@ -1,4 +1,4 @@
-package main
+package common
 
 import (
 	"crypto/rand"
@@ -9,30 +9,32 @@ import (
 	"golang.org/x/crypto/chacha20poly1305"
 )
 
+const PacketSize = 504
+
 const HeaderSize int = 32 + 1 + 4 + 4
 const SecureHeaderSize int = 1 + 42 + 32 + 4
 
 type SessionID [32]byte
 
 type SecurePacket struct {
-	isRsa         byte // 0 = false everything else is true
-	nonce         [24]byte
-	sid           SessionID
-	dataLength    uint32
-	encryptedData []byte
+	IsRsa         byte // 0 = false everything else is true
+	Nonce         [24]byte
+	Sid           SessionID
+	DataLength    uint32
+	EncryptedData []byte
 }
 
 type Packet struct {
 	// headerLength uint32
-	sid        SessionID
-	flag       HeaderFlag
-	sync       uint32
-	dataLength uint32
-	data       []byte
+	Sid        SessionID
+	Flag       HeaderFlag
+	Sync       uint32
+	DataLength uint32
+	Data       []byte
 }
 
 func NewSymetricSecurePacket(key [32]byte, pck *Packet) *SecurePacket {
-	sid := pck.sid
+	sid := pck.Sid
 	data := pck.ToBytes()
 	aead, err := chacha20poly1305.NewX(key[:])
 	if err != nil {
@@ -48,11 +50,11 @@ func NewSymetricSecurePacket(key [32]byte, pck *Packet) *SecurePacket {
 	encrypted = aead.Seal(nil, nonce, data, nil)
 
 	return &SecurePacket{
-		isRsa:         0,
-		nonce:         [24]byte(nonce),
-		sid:           sid,
-		dataLength:    uint32(len(encrypted)),
-		encryptedData: encrypted,
+		IsRsa:         0,
+		Nonce:         [24]byte(nonce),
+		Sid:           sid,
+		DataLength:    uint32(len(encrypted)),
+		EncryptedData: encrypted,
 	}
 }
 
@@ -64,49 +66,50 @@ func SecurePacketFromBytes(bytes []byte) SecurePacket {
 	enc := bytes[61 : 61+length]
 
 	return SecurePacket{
-		isRsa:         isRsa,
-		nonce:         [24]byte(nonce),
-		sid:           sid,
-		encryptedData: enc,
-		dataLength:    length,
+		IsRsa:         isRsa,
+		Nonce:         [24]byte(nonce),
+		Sid:           sid,
+		DataLength:    length,
+		EncryptedData: enc,
 	}
 }
 
 func (secPck *SecurePacket) ToBytes() []byte {
-	arr := make([]byte, SecureHeaderSize+len(secPck.encryptedData))
-	arr[0] = secPck.isRsa
-	copy(arr[1:25], secPck.nonce[:])
-	copy(arr[25:57], secPck.sid[:])
-	binary.LittleEndian.PutUint32(arr[57:61], secPck.dataLength)
-	copy(arr[61:], secPck.encryptedData)
+	arr := make([]byte, SecureHeaderSize+len(secPck.EncryptedData))
+	arr[0] = secPck.IsRsa
+	copy(arr[1:25], secPck.Nonce[:])
+	copy(arr[25:57], secPck.Sid[:])
+	binary.LittleEndian.PutUint32(arr[57:61], secPck.DataLength)
+	copy(arr[61:], secPck.EncryptedData)
 
 	return arr
 }
 
-func (secPck *SecurePacket) ExtractPacket(key [32]byte) (*Packet, error) {
+func (secPck *SecurePacket) ExtractPacket(key [32]byte) (Packet, error) {
 	aead, err := chacha20poly1305.NewX(key[:])
 	if err != nil {
 		panic(err)
 	}
-	data, err := aead.Open(nil, secPck.nonce[:], secPck.encryptedData, nil)
+	data, err := aead.Open(nil, secPck.Nonce[:], secPck.EncryptedData, nil)
 	if err != nil {
-		return nil, err
+		return Packet{}, err
 	}
+	// fmt.Println(data)
 	packet := PacketFromBytes(data)
-	return &packet, nil
+	return packet, nil
 }
 
 func NewRsaPacket(sid SessionID, key [32]byte) *SecurePacket {
 	return &SecurePacket{
-		isRsa:         1,
-		nonce:         [24]byte(make([]byte, 24)),
-		sid:           sid,
-		encryptedData: key[:],
+		IsRsa:         1,
+		Nonce:         [24]byte(make([]byte, 24)),
+		Sid:           sid,
+		EncryptedData: key[:],
 	}
 }
 
 func (secPck *SecurePacket) ExtractKey( /*RSA HERE LATER*/ ) []byte {
-	return secPck.encryptedData[:32]
+	return secPck.EncryptedData[:32]
 }
 
 func PacketFromBytes(bytes []byte) Packet {
@@ -115,24 +118,24 @@ func PacketFromBytes(bytes []byte) Packet {
 	sync := binary.LittleEndian.Uint32(bytes[33:37])
 	dataLength := binary.LittleEndian.Uint32(bytes[37:41])
 	pck := Packet{
-		sid:        sid,
-		flag:       flag,
-		sync:       sync,
-		dataLength: dataLength,
-		data:       bytes[HeaderSize : HeaderSize+int(dataLength)],
+		Sid:        sid,
+		Flag:       flag,
+		Sync:       sync,
+		DataLength: dataLength,
+		Data:       bytes[HeaderSize : HeaderSize+int(dataLength)],
 	}
 	return pck
 }
 
 func NewAck(pckToAck *Packet) *Packet {
 	data := make([]byte, 4)
-	binary.LittleEndian.PutUint32(data, pckToAck.sync)
+	binary.LittleEndian.PutUint32(data, pckToAck.Sync)
 	return &Packet{
-		sid:        pckToAck.sid,
-		flag:       Ack,
-		sync:       pckToAck.sync + 1,
-		dataLength: uint32(4),
-		data:       data,
+		Sid:        pckToAck.Sid,
+		Flag:       Ack,
+		Sync:       pckToAck.Sync + 1,
+		DataLength: uint32(4),
+		Data:       data,
 	}
 }
 
@@ -145,59 +148,59 @@ func NewRequest(path string) *Packet {
 	}
 
 	return &Packet{
-		sid:        SessionID(buf),
-		flag:       Request,
-		sync:       0,
-		dataLength: uint32(len(data)),
-		data:       data,
+		Sid:        SessionID(buf),
+		Flag:       Request,
+		Sync:       0,
+		DataLength: uint32(len(data)),
+		Data:       data,
 	}
 }
 
 func (pck *Packet) GetUint32Payload() (uint32, error) {
-	flag := pck.flag
+	flag := pck.Flag
 	if flag != PTE && flag != Ack && flag != End && flag != Resend {
 		return 0, errors.New(fmt.Sprintf("Can not get Sync from Packet Type with flag: %v", flag))
 	}
-	return binary.LittleEndian.Uint32(pck.data), nil
+	return binary.LittleEndian.Uint32(pck.Data), nil
 }
 
 func (pck *Packet) GetFilePath() (string, error) {
-	if pck.flag != Request {
+	if pck.Flag != Request {
 		return "", errors.New("Can not get FilePath from Packet that is not Request")
 	}
-	return string(pck.data), nil
+	return string(pck.Data), nil
 }
 
 func NewResendFile(resendPck *Packet, data []byte) *Packet {
 	sync, _ := resendPck.GetUint32Payload()
 	return &Packet{
-		sid:        resendPck.sid,
-		flag:       File,
-		sync:       sync,
-		dataLength: uint32(len(data)),
-		data:       data,
+		Sid:        resendPck.Sid,
+		Flag:       File,
+		Sync:       sync,
+		DataLength: uint32(len(data)),
+		Data:       data,
 	}
 }
 
 func NewFile(lastPck *Packet, data []byte) *Packet {
 	return &Packet{
-		sid:        lastPck.sid,
-		flag:       File,
-		sync:       lastPck.sync + 1,
-		dataLength: uint32(len(data)),
-		data:       data,
+		Sid:        lastPck.Sid,
+		Flag:       File,
+		Sync:       lastPck.Sync + 1,
+		DataLength: uint32(len(data)),
+		Data:       data,
 	}
 }
 
 func NewEnd(lastFilePck *Packet) *Packet {
 	data := make([]byte, 4)
-	binary.LittleEndian.PutUint32(data, lastFilePck.sync)
+	binary.LittleEndian.PutUint32(data, lastFilePck.Sync)
 	return &Packet{
-		sid:        lastFilePck.sid,
-		flag:       End,
-		sync:       lastFilePck.sync + 1,
-		dataLength: uint32(4),
-		data:       data,
+		Sid:        lastFilePck.Sid,
+		Flag:       End,
+		Sync:       lastFilePck.Sync + 1,
+		DataLength: uint32(4),
+		Data:       data,
 	}
 }
 
@@ -205,11 +208,11 @@ func NewResend(sync uint32, lastPck *Packet) *Packet {
 	data := make([]byte, 4)
 	binary.LittleEndian.PutUint32(data, sync)
 	return &Packet{
-		sid:        lastPck.sid,
-		flag:       Resend,
-		sync:       lastPck.sync + 1,
-		dataLength: uint32(4),
-		data:       data,
+		Sid:        lastPck.Sid,
+		Flag:       Resend,
+		Sync:       lastPck.Sync + 1,
+		DataLength: uint32(4),
+		Data:       data,
 	}
 }
 
@@ -217,21 +220,21 @@ func NewPte(fileSize uint32, lastPck *Packet) *Packet {
 	data := make([]byte, 4)
 	binary.LittleEndian.PutUint32(data, fileSize)
 	return &Packet{
-		sid:        lastPck.sid,
-		flag:       PTE,
-		sync:       lastPck.sync + 1,
-		dataLength: uint32(4),
-		data:       data,
+		Sid:        lastPck.Sid,
+		Flag:       PTE,
+		Sync:       lastPck.Sync + 1,
+		DataLength: uint32(4),
+		Data:       data,
 	}
 }
 
 func (pck *Packet) ToBytes() []byte {
-	arr := make([]byte, HeaderSize+int(pck.dataLength))
-	arr[0] = byte(pck.flag)
-	copy(arr[1:33], pck.sid[:])
-	binary.LittleEndian.PutUint32(arr[33:37], pck.sync)
-	binary.LittleEndian.PutUint32(arr[37:41], pck.dataLength)
-	copy(arr[41:], pck.data)
+	arr := make([]byte, HeaderSize+int(pck.DataLength))
+	arr[0] = byte(pck.Flag)
+	copy(arr[1:33], pck.Sid[:])
+	binary.LittleEndian.PutUint32(arr[33:37], pck.Sync)
+	binary.LittleEndian.PutUint32(arr[37:41], pck.DataLength)
+	copy(arr[41:], pck.Data)
 
 	return arr
 }

internal/server/go.mod

@@ -0,0 +1,3 @@
+module server
+
+go 1.21.1

internal/server/server.go

@@ -1,6 +1,7 @@
-package main
+package server
 
 import (
+	"common"
 	"crypto/rand"
 	"crypto/rsa"
 	"encoding/hex"
@@ -14,12 +15,12 @@ import (
 type info struct {
 	path        string
 	lastSync    uint32
-	lastPckSend HeaderFlag
+	lastPckSend common.HeaderFlag
 	key         [32]byte
 }
 
 type Server struct {
-	sessions map[SessionID]*info
+	sessions map[common.SessionID]*info
 	rsa      *rsa.PrivateKey
 }
 
@@ -31,31 +32,43 @@ func New() (*Server, error) {
 	}
 
 	return &Server{
-		sessions: make(map[SessionID]*info),
+		sessions: make(map[common.SessionID]*info),
 		rsa:      key,
 	}, nil
 }
 
-func (server *Server) handlePacket(conn *net.UDPConn, addr *net.UDPAddr, rPacket *Packet) {
-	switch rPacket.flag {
-	case Request:
+func (server *Server) sendPacket(conn *net.UDPConn, addr *net.UDPAddr, pck *common.Packet) {
+	key := server.sessions[pck.Sid].key
+
+	fmt.Printf("Sending Packet, Sync: %v, Type: %v\n", pck.Sync, pck.Flag)
+
+	secPck := common.NewSymetricSecurePacket(key, pck)
+	if _, err := conn.WriteToUDP(secPck.ToBytes(), addr); err != nil {
+		panic(err)
+	}
+	conn.WriteToUDP(secPck.ToBytes(), addr)
+}
+
+func (server *Server) handlePacket(conn *net.UDPConn, addr *net.UDPAddr, rPacket *common.Packet) {
+	switch rPacket.Flag {
+	case common.Request:
 		server.sendPTE(conn, addr, rPacket)
 		break
-	case Ack:
+	case common.Ack:
 		server.handleAck(conn, addr, rPacket)
 		break
-	case Resend:
+	case common.Resend:
 		server.resend(conn, addr, rPacket)
 	}
 }
 
-func (server *Server) resend(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
+func (server *Server) resend(conn *net.UDPConn, addr *net.UDPAddr, pck *common.Packet) {
 	resend, err := pck.GetUint32Payload()
 	if err != nil {
 		panic(err)
 	}
 
-	path := server.sessions[pck.sid].path
+	path := server.sessions[pck.Sid].path
 	file, err := os.Open(path)
 	if err != nil {
 		panic(err)
@@ -63,29 +76,24 @@ func (server *Server) resend(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet)
 	defer file.Close()
 
 	// This should be different
-	offset := (int64(resend) - 3) * (PacketSize - int64(HeaderSize))
-	// fmt.Printf("Requested Sync: %v, Calculated Offset: %v\n", resend, offset)
-	buf := make([]byte, PacketSize-HeaderSize)
+	offset := (int64(resend) - 3) * (common.PacketSize - int64(common.HeaderSize))
+	buf := make([]byte, common.PacketSize-common.HeaderSize)
 
 	_, err = file.ReadAt(buf, offset)
 	if err != nil && !errors.Is(err, io.EOF) {
 		panic(err)
 	}
 
-	fmt.Printf("Resending Packet %v\n", resend)
-
-	resendPck := NewResendFile(pck, buf)
-
-	conn.WriteToUDP(resendPck.ToBytes(), addr)
-
+	resendPck := common.NewResendFile(pck, buf)
+	server.sendPacket(conn, addr, resendPck)
 }
 
-func (server *Server) handleAck(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
+func (server *Server) handleAck(conn *net.UDPConn, addr *net.UDPAddr, pck *common.Packet) {
 	ack, err := pck.GetUint32Payload()
 	if err != nil {
 		panic(err)
 	}
-	session := server.sessions[pck.sid]
+	session := server.sessions[pck.Sid]
 	if session == nil {
 		panic(err)
 	}
@@ -94,16 +102,15 @@ func (server *Server) handleAck(conn *net.UDPConn, addr *net.UDPAddr, pck *Packe
 		return
 	}
 
-	if session.lastPckSend == End {
-		fmt.Printf("Deleting Session %v\n", hex.EncodeToString(pck.sid[:]))
-		delete(server.sessions, pck.sid)
+	if session.lastPckSend == common.End {
+		fmt.Printf("Deleting Session %v\n", hex.EncodeToString(pck.Sid[:]))
+		delete(server.sessions, pck.Sid)
 	} else {
-		fmt.Printf("Sending Data for Session %v\n", hex.EncodeToString(pck.sid[:]))
 		server.sendData(conn, addr, pck)
 	}
 }
 
-func (server *Server) sendPTE(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
+func (server *Server) sendPTE(conn *net.UDPConn, addr *net.UDPAddr, pck *common.Packet) {
 	path, err := pck.GetFilePath()
 	if err != nil {
 		panic(err)
@@ -116,23 +123,23 @@ func (server *Server) sendPTE(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet)
 
 	fileSize := fi.Size()
 
-	ptePck := NewPte(uint32(fileSize), pck)
-	conn.WriteToUDP(ptePck.ToBytes(), addr)
+	ptePck := common.NewPte(uint32(fileSize), pck)
+	server.sendPacket(conn, addr, ptePck)
 
-	server.sessions[pck.sid].path = path
-	server.sessions[pck.sid].lastSync = ptePck.sync
-	server.sessions[pck.sid].lastPckSend = ptePck.flag
+	server.sessions[pck.Sid].path = path
+	server.sessions[pck.Sid].lastSync = ptePck.Sync
+	server.sessions[pck.Sid].lastPckSend = ptePck.Flag
 }
 
-func (server *Server) sendData(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
-	path := server.sessions[pck.sid].path
+func (server *Server) sendData(conn *net.UDPConn, addr *net.UDPAddr, pck *common.Packet) {
+	path := server.sessions[pck.Sid].path
 	file, err := os.Open(path)
 	if err != nil {
 		panic(err)
 	}
 	defer file.Close()
 
-	buf := make([]byte, PacketSize-HeaderSize)
+	buf := make([]byte, common.PacketSize-common.HeaderSize)
 	filePck := pck
 	for {
 		r, err := file.Read(buf)
@@ -142,18 +149,15 @@ func (server *Server) sendData(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet
 		if r == 0 {
 			break
 		}
-		filePck = NewFile(filePck, buf[:r])
-		fmt.Printf("Sending File Packet %v\n", filePck.sync)
+		filePck = common.NewFile(filePck, buf[:r])
 
-		conn.WriteToUDP(filePck.ToBytes(), addr)
+		server.sendPacket(conn, addr, filePck)
 	}
 
-	eodPck := NewEnd(filePck)
-	server.sessions[pck.sid].lastSync = eodPck.sync
-	server.sessions[pck.sid].lastPckSend = eodPck.flag
-
-	fmt.Printf("Sending Eod Packet %v\n", eodPck.sync)
-	conn.WriteToUDP(eodPck.ToBytes(), addr)
+	eodPck := common.NewEnd(filePck)
+	server.sessions[pck.Sid].lastSync = eodPck.Sync
+	server.sessions[pck.Sid].lastPckSend = eodPck.Flag
+	server.sendPacket(conn, addr, eodPck)
 }
 
 func (server *Server) Serve() {
@@ -172,33 +176,28 @@ func (server *Server) Serve() {
 	}
 
 	for {
-		var buf [PacketSize]byte
+		var buf [common.PacketSize]byte
 		_, addr, err := conn.ReadFromUDP(buf[0:])
 		if err != nil {
 			fmt.Println(err)
 			return
 		}
 
-		secPck := SecurePacketFromBytes(buf[:])
+		secPck := common.SecurePacketFromBytes(buf[:])
 
-		fmt.Println(secPck)
-
-		if secPck.isRsa == 0 {
-			key := server.sessions[secPck.sid].key
+		if secPck.IsRsa == 0 {
+			key := server.sessions[secPck.Sid].key
 			pck, err := secPck.ExtractPacket(key)
 			if err != nil {
 				fmt.Println(err)
-				//fmt.Println("Could not establish secure connection")
 			}
-			go server.handlePacket(conn, addr, pck)
+			go server.handlePacket(conn, addr, &pck)
 		} else {
 			key := secPck.ExtractKey()
-			fmt.Println(key)
-			fmt.Println(secPck.sid)
-			server.sessions[secPck.sid] = &info{
+			fmt.Printf("Session: %v, Key: %v\n", hex.EncodeToString(secPck.Sid[:]), hex.EncodeToString(key))
+			server.sessions[secPck.Sid] = &info{
 				key: [32]byte(key),
 			}
-
 		}
 	}
 }

main.go

@@ -1,19 +1,19 @@
 package main
 
 import (
+	"client"
 	"os"
+	"server"
 )
 
-const PacketSize = 504
-
 func main() {
 	if os.Args[1] == "server" {
-		server, err := New()
+		server, err := server.New()
 		if err != nil {
 			panic(err)
 		}
 		server.Serve()
 	} else {
-		GetFile(os.Args[2])
+		client.GetFile(os.Args[2])
 	}
 }