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Added resend functionality and preparations for RSA / Encrpyption

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This commit is contained in:
Pablu23
2023-11-09 17:25:02 +01:00
parent 6d9221d951
commit cbf0054394
5 changed files with 142 additions and 91 deletions
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1
.gitignore vendored
View File

@@ -2,3 +2,4 @@ bin/
testFile
testFile.recv
testFile2
out/

118
client.go
View File

@@ -1,16 +1,19 @@
package main
import (
"encoding/hex"
"fmt"
"net"
"os"
"sort"
"time"
)
func GetFile(path string) {
request := NewRequest(path)
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)
@@ -31,7 +34,7 @@ func GetFile(path string) {
}
bytes := make([]byte, PacketSize)
file, err := os.Create(path + ".recv")
file, err := os.Create("out/" + hex.EncodeToString(request.sid[:]) + ".recv")
if err != nil {
panic(err)
}
@@ -88,61 +91,72 @@ func GetFile(path string) {
})
lostPackets := make([]uint32, 0)
lastSync := ackPck.sync
needResend := false
for _, i := range recvPackets {
if lastSync+1 != i {
for i := ackPck.sync + 1; i < endPacket.sync; i++ {
if b, _ := contains(recvPackets, i); !b {
lostPackets = append(lostPackets, i)
needResend = true
}
lastSync = i
}
if !needResend {
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)
conn.Write(resend.ToBytes())
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)
conn.Write(ack.ToBytes())
}
// sort.Slice(recvPackets, func(i, j int) bool {
// pckI := recvPackets[i]
// pckJ := recvPackets[j]
// return pckI.sync < pckJ.sync
// })
// endPacketFound := false
// needResend := false
// lastSync := request.sync
// fmt.Println(lastSync)
// endPacketSync, err := endPacket.GetSync()
// if err != nil {
// panic(err)
// }
// for _, packet := range recvPackets {
// // fmt.Println(packet.sync)
// // offset := (int64(packet.sync)-1)*PacketSize - int64(HeaderSize)
// // data := packet.data
// // fmt.Printf("Data: %v Offset: %v\n", data, offset)
// if lastSync+1 != packet.sync {
// fmt.Printf("Need Packet %v resend\n", lastSync+1)
// // Add to slice
// needResend = true
// continue
// }
// fmt.Printf("Writing Packet %v to file\n", packet.sync)
// _, err = file.Write(packet.data)
// if err != nil {
// panic(err)
// }
// if packet.sync == endPacketSync {
// endPacketFound = true
// }
// lastSync = packet.sync
// }
}
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
}

5
main.go
View File

@@ -8,7 +8,10 @@ const PacketSize = 504
func main() {
if os.Args[1] == "server" {
server := New()
server, err := New()
if err != nil {
panic(err)
}
server.Serve()
} else {
GetFile(os.Args[2])

51
packets.go
View File

@@ -21,8 +21,8 @@ type Packet struct {
}
func PacketFromBytes(bytes []byte) Packet {
sid := SessionID(bytes[0:32])
flag := HeaderFlag(bytes[32])
flag := HeaderFlag(bytes[0])
sid := SessionID(bytes[1:33])
sync := binary.LittleEndian.Uint32(bytes[33:37])
dataLength := binary.LittleEndian.Uint32(bytes[37:41])
pck := Packet{
@@ -30,7 +30,7 @@ func PacketFromBytes(bytes []byte) Packet {
flag: flag,
sync: sync,
dataLength: dataLength,
data: bytes[41 : 41+dataLength],
data: bytes[HeaderSize : HeaderSize+int(dataLength)],
}
return pck
}
@@ -64,6 +64,32 @@ func NewRequest(path string) *Packet {
}
}
func (pck *Packet) GetUint32Payload() (uint32, error) {
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
}
func (pck *Packet) GetFilePath() (string, error) {
if pck.flag != Request {
return "", errors.New("Can not get FilePath from Packet that is not Request")
}
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,
}
}
func NewFile(lastPck *Packet, data []byte) *Packet {
return &Packet{
sid: lastPck.sid,
@@ -110,25 +136,10 @@ func NewPte(fileSize uint32, lastPck *Packet) *Packet {
}
}
func (pck *Packet) GetUint32Payload() (uint32, error) {
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
}
func (pck *Packet) GetFilePath() (string, error) {
if pck.flag != Request {
return "", errors.New("Can not get FilePath from Packet that is not Request")
}
return string(pck.data), nil
}
func (pck *Packet) ToBytes() []byte {
arr := make([]byte, HeaderSize+int(pck.dataLength))
copy(arr[0:32], pck.sid[:])
arr[32] = byte(pck.flag)
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)

72
server.go
View File

@@ -1,6 +1,8 @@
package main
import (
"crypto/rand"
"crypto/rsa"
"encoding/hex"
"errors"
"fmt"
@@ -13,16 +15,25 @@ type info struct {
path string
lastSync uint32
lastPckSend HeaderFlag
key [32]byte
}
type Server struct {
sessions map[SessionID]*info
rsa *rsa.PrivateKey
}
func New() *Server {
func New() (*Server, error) {
key, err := rsa.GenerateKey(rand.Reader, 4096)
if err != nil {
return nil, err
}
return &Server{
sessions: make(map[SessionID]*info),
}
rsa: key,
}, nil
}
func (server *Server) handlePacket(conn *net.UDPConn, addr *net.UDPAddr, rPacket *Packet) {
@@ -33,9 +44,42 @@ func (server *Server) handlePacket(conn *net.UDPConn, addr *net.UDPAddr, rPacket
case Ack:
server.handleAck(conn, addr, rPacket)
break
case Resend:
server.resend(conn, addr, rPacket)
}
}
func (server *Server) resend(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
resend, err := pck.GetUint32Payload()
if err != nil {
panic(err)
}
path := server.sessions[pck.sid].path
file, err := os.Open(path)
if err != nil {
panic(err)
}
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)
_, 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)
}
func (server *Server) handleAck(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
ack, err := pck.GetUint32Payload()
if err != nil {
@@ -88,11 +132,7 @@ func (server *Server) sendData(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet
if err != nil {
panic(err)
}
// // ONLY FOR TEST
// firstPacket := true
// var firstFilePckt Packet
// // END TEST
defer file.Close()
buf := make([]byte, PacketSize-HeaderSize)
filePck := pck
@@ -107,27 +147,9 @@ func (server *Server) sendData(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet
filePck = NewFile(filePck, buf[:r])
fmt.Printf("Sending File Packet %v\n", filePck.sync)
// // ONLY FOR TEST
// if firstPacket {
// firstPacket = false
// firstFilePckt = Packet{
// sid: filePck.sid,
// flag: File,
// sync: filePck.sync,
// dataLength: filePck.dataLength,
// data: make([]byte, filePck.dataLength),
// }
// copy(firstFilePckt.data, filePck.data)
// } else {
// // END
conn.WriteToUDP(filePck.ToBytes(), addr)
// }
}
// conn.WriteToUDP(firstFilePckt.ToBytes(), addr)
eodPck := NewEnd(filePck)
server.sessions[pck.sid].lastSync = eodPck.sync
server.sessions[pck.sid].lastPckSend = eodPck.flag