First completly working solution

2023-11-09 10:59:55 +01:00
parent edd4a9a760
commit 3f975ab85f
9 changed files with 947 additions and 283 deletions
--- a/server.go
+++ b/server.go
@@ -0,0 +1,164 @@
+package main
+
+import (
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"os"
+)
+
+type info struct {
+	path        string
+	lastSync    uint32
+	lastPckSend HeaderFlag
+}
+
+type Server struct {
+	sessions map[SessionID]*info
+}
+
+func New() *Server {
+	return &Server{
+		sessions: make(map[SessionID]*info),
+	}
+}
+
+func (server *Server) handlePacket(conn *net.UDPConn, addr *net.UDPAddr, rPacket *Packet) {
+	switch rPacket.flag {
+	case Request:
+		server.sendPTE(conn, addr, rPacket)
+		break
+	case Ack:
+		server.handleAck(conn, addr, rPacket)
+		break
+	}
+}
+
+func (server *Server) handleAck(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
+	ack, err := pck.GetUint32Payload()
+	if err != nil {
+		panic(err)
+	}
+	session := server.sessions[pck.sid]
+	if session == nil {
+		panic(err)
+	}
+	if ack != session.lastSync {
+		fmt.Printf("Wrong Ack %v, expected %v\n", ack, session.lastSync)
+		return
+	}
+
+	if session.lastPckSend == 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) {
+	path, err := pck.GetFilePath()
+	if err != nil {
+		panic(err)
+	}
+
+	fi, err := os.Stat(path)
+	if err != nil {
+		panic(err)
+	}
+
+	fileSize := fi.Size()
+
+	ptePck := NewPte(uint32(fileSize), pck)
+	conn.WriteToUDP(ptePck.ToBytes(), addr)
+
+	server.sessions[pck.sid] = &info{
+		path:        path,
+		lastSync:    ptePck.sync,
+		lastPckSend: ptePck.flag,
+	}
+}
+
+func (server *Server) sendData(conn *net.UDPConn, addr *net.UDPAddr, pck *Packet) {
+	path := server.sessions[pck.sid].path
+	file, err := os.Open(path)
+	if err != nil {
+		panic(err)
+	}
+
+	// // ONLY FOR TEST
+	// firstPacket := true
+	// var firstFilePckt Packet
+	// // END TEST
+
+	buf := make([]byte, PacketSize-HeaderSize)
+	filePck := pck
+	for {
+		r, err := file.Read(buf)
+		if err != nil && !errors.Is(err, io.EOF) {
+			panic(err)
+		}
+		if r == 0 {
+			break
+		}
+		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
+
+	fmt.Printf("Sending Eod Packet %v\n", eodPck.sync)
+	conn.WriteToUDP(eodPck.ToBytes(), addr)
+}
+
+func (server *Server) Serve() {
+	udpAddr, err := net.ResolveUDPAddr("udp", "0.0.0.0:13374")
+
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	conn, err := net.ListenUDP("udp", udpAddr)
+
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	for {
+		var buf [PacketSize]byte
+		_, addr, err := conn.ReadFromUDP(buf[0:])
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+		pck := PacketFromBytes(buf[:])
+		go server.handlePacket(conn, addr, &pck)
+	}
+}