further updates

client/golang/client.go

@@ -1,12 +1,12 @@
 package main
 
 import (
-	"encoding/base64"
+	//"encoding/base64"
 	"encoding/binary"
 	"errors"
 	"fmt"
 	"net"
-	"strings"
+	//"strings"
 	"time"
 
 	"github.com/google/gopacket"
@@ -21,10 +21,11 @@ func errCheck(err error) {
 }
 
 func listenDiscoverResponse(addrChan chan string, readyFlag chan int) {
+	finalMessage := ""
 	handle, err := pcap.OpenLive("any", int32(1600), true, pcap.BlockForever)
 	errCheck(err)
 
-	err = handle.SetBPFFilter("udp and port 8850")
+	err = handle.SetBPFFilter("udp and port 6767")
 	errCheck(err)
 
 	packets := gopacket.NewPacketSource(handle, handle.LinkType()).Packets()
@@ -32,12 +33,17 @@ func listenDiscoverResponse(addrChan chan string, readyFlag chan int) {
 	readyFlag <- 1
 
 	for pkt := range packets {
-		msg, err := base64.StdEncoding.DecodeString(string(pkt.ApplicationLayer().Payload()))
+		finalMessage = ""
+		payload := pkt.ApplicationLayer().Payload()
+		payloadLength := binary.BigEndian.Uint16([]byte{payload[2], payload[3]})
+
+		for i := uint16(0); i < payloadLength - 5; i++ {
+			finalMessage += string(payload[i+9])
+		}
+		fmt.Println(finalMessage)
 		if err == nil {
-			if strings.Contains(string(msg), "clientapi") {
-				addrChan <- string(msg)
-				return
-			}
+			//addrChan <- finalMessage
+			//return
 		}
 	}
 
@@ -102,7 +108,7 @@ func main() {
 	// Listen timeout
 	select {
 		case returnMSG := <- addrChan:
-			fmt.Printf("%s\n", strings.Fields(returnMSG)[1])
+			fmt.Printf("%s\n", returnMSG)
 		case <- time.After(5 * time.Second):
 			fmt.Printf("error\n")
 	}

server/README.md

@@ -31,8 +31,21 @@ Saprus Protocol Header:
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |          Saprus Type          |             Length            |                               |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +-+-+-+-+-+-+-+-+
-|                          Saprus Type Payload (0-1455)                         |
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
+|                                  Saprus Type Payload (0-1454)                                 |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ```
 
+## File Transfer
+
+Saprus Type: 0x88 0x88
+
+```
+ 0                   1                   2                   3                   4
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|      Flag     |            Sequence           |            Checksum           |               |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+               +
+|                                            Payload                                            |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+```

server/server.go

@@ -38,7 +38,7 @@ func main() {
 	log.Printf("Starting server\n")
 	con := utils.SocketCall{}
 	serv, err := net.ListenPacket("udp4", ":8888")
-	serverIP := "client data being send from the sender"
+	serverIP := "hello world this is saprus"
 	msg := "clientapi: " + serverIP
 	b64Msg := base64.StdEncoding.EncodeToString([]byte(msg))
 

server/structs/file_transfer.go

@@ -0,0 +1,21 @@
+package structs
+
+import (
+)
+
+type SaprusFileTransfer struct {
+        Flag            [1]byte
+        Sequence        [2]byte
+        Checksum        [2]byte
+        Payload         []byte
+}
+
+func (c SaprusFileTransfer) Bytes() []byte {
+        data := []byte{}
+        data = append(data, c.Flag[0])
+        data = append(data, c.Sequence[0], c.Sequence[1])
+        data = append(data, c.Checksum[0], c.Checksum[1])
+        data = append(data, c.Payload...)
+        return data
+}
+

server/structs/saprus.go

@@ -4,13 +4,15 @@ import (
 )
 
 type SaprusHeaderFrame struct {
-        PacketType  uint16
-        Length      uint16
+        PacketType  [2]byte
+        Length      [2]byte
         Payload     []byte
 }
 
 func (c SaprusHeaderFrame) Bytes() []byte {
-	data := []byte{byte(c.PacketType), byte(c.Length)}
+	data := []byte{}
+	data = append(data, c.PacketType[0], c.PacketType[1])
+	data = append(data, c.Length[0], c.Length[1])
 	data = append(data, c.Payload...)
 	return data
 }

server/utils/file_transfer.go

@@ -0,0 +1,39 @@
+package utils
+
+import (
+	"log"
+	"github.com/google/gopacket"
+
+	"saprusserver/structs"
+)
+
+func (c* SocketCall) FileTransferPacket(message string) gopacket.SerializeBuffer {
+        eth, ip, udp := basePacket(c)
+
+        sapFile := structs.SaprusFileTransfer {
+                Flag:           [1]byte{0x11},
+                Sequence:       [2]byte{0x22, 0x33},
+                Checksum:       [2]byte{0x44, 0x44},
+                Payload:        []byte(message),
+        }
+
+        sapHeader := structs.SaprusHeaderFrame {
+                PacketType:     [2]byte{0x88, 0x88},
+                Length:         c.saprusPayloadLength(sapFile.Bytes()),
+                Payload:        sapFile.Bytes(),
+        }
+
+        buf := gopacket.NewSerializeBuffer()
+        opts := gopacket.SerializeOptions {
+                ComputeChecksums:       true,
+                FixLengths:             true,
+        }
+
+        udp.SetNetworkLayerForChecksum(&ip)
+        err := gopacket.SerializeLayers(buf, opts, &eth, &ip, &udp, gopacket.Payload(sapHeader.Bytes()))
+        if err != nil {
+                log.Panic(err)
+        }
+        return buf
+}
+

server/utils/packet_helper.go

@@ -0,0 +1,27 @@
+package utils
+
+import (
+	"github.com/google/gopacket/layers"
+)
+
+func basePacket(c* SocketCall) (layers.Ethernet, layers.IPv4, layers.UDP) {
+        eth := layers.Ethernet {
+                EthernetType:   layers.EthernetTypeIPv4,
+                SrcMAC:         c.Iface.HardwareAddr,
+                DstMAC:         layers.EthernetBroadcast,
+        }
+        ip := layers.IPv4 {
+                Version:        4,
+                TTL:            64,
+                SrcIP:          []byte{0, 0, 0, 0},
+                DstIP:          []byte{255, 255, 255, 255},
+                Protocol:       layers.IPProtocolUDP,
+        }
+        udp := layers.UDP {
+                SrcPort:        6868,
+                DstPort:        6767,
+        }
+
+        return eth, ip, udp
+}
+

server/utils/raw_packet_send.go

@@ -1,8 +1,8 @@
 package utils
 
 import (
-	//"bytes"
-	//"encoding/binary"
+	"encoding/binary"
+	"fmt"
 	"log"
 	"net"
 	"unicode/utf8"
@@ -21,10 +21,12 @@ type SocketCall struct {
 
 func splitData(message string) []string {
         data := []string{}
+	maxPacketLength := 8
+	//maxPacketLength := 1458
 
         var i, j int
 
-        for i, j = 0, 1458; j < len(message); i, j = j, j+1458 {
+        for i, j = 0, maxPacketLength; j < len(message); i, j = j, j+maxPacketLength {
                 for !utf8.RuneStart(message[j]) {
                         j--
                 }
@@ -35,15 +37,38 @@ func splitData(message string) []string {
         return data
 }
 
+func (c* SocketCall) SendPackage(buf gopacket.SerializeBuffer) error {
+	_, err := c.conn.WriteTo(buf.Bytes(), &packet.Addr{HardwareAddr: layers.EthernetBroadcast})
+	return err
+}
+
 func (c* SocketCall)SendData(message string) {
+	iface, _ := net.InterfaceByName("virbr0")
+	c.Iface = iface
+
+        conn, _ := packet.Listen(iface, packet.Raw, int(layers.EthernetTypeIPv4), nil)
+	c.conn = conn
+
         splitMessage := splitData(message)
 
         for i := 0; i < len(splitMessage); i++ {
-                c.init(splitMessage[i])
+		c.SendPackage(c.FileTransferPacket(splitMessage[i]))
         }
         return
 }
 
+func (c* SocketCall) saprusPayloadLength(pkt []byte) [2]byte{
+	payloadLength := make([]byte, 2)
+	var length [2]byte
+	binary.BigEndian.PutUint16(payloadLength, uint16(len(pkt)))
+
+	length[0] = payloadLength[0]
+	length[1] = payloadLength[1]
+
+	return length
+}
+
+/*
 func (c* SocketCall)init(data string) {
         iface, _ := net.InterfaceByName("virbr0")
         conn, err := packet.Listen(iface, packet.Raw, int(layers.EthernetTypeIPv4), nil)
@@ -71,9 +96,16 @@ func (c* SocketCall)init(data string) {
                 SrcPort: 6868,
                 DstPort: 6767,
         }
+
+	saprusPayloadLength := make([]byte, 2)
+	binary.BigEndian.PutUint16(saprusPayloadLength, uint16(len(data)))
+	var saprusPayloadLengthTwo [2]byte
+	saprusPayloadLengthTwo[0] = saprusPayloadLength[0]
+	saprusPayloadLengthTwo[1] = saprusPayloadLength[1]
+
 	saprus := structs.SaprusHeaderFrame{
-		PacketType:	10,
-		Length:		uint16(len(data)),
+		PacketType:	[2]byte{0, 10},
+		Length:		saprusPayloadLengthTwo,
 		Payload:	[]byte(data),
 	}
 
@@ -96,4 +128,4 @@ func (c* SocketCall)init(data string) {
 
         return
 }
-
+*/