magic

client/golang/client.go

@@ -1,18 +1,33 @@
 package main
 
 import (
-	"encoding/base64"
+	//"encoding/base64"
 	"encoding/binary"
-	"errors"
 	"fmt"
-	"net"
-	"strings"
+	//"net"
+
+	//"strings"
 	"time"
 
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/pcap"
+
+	"client/utils"
 )
 
+type SaprusHeaderPacket struct {
+	Type		uint16
+	Length		uint16
+}
+
+type SaprusFileTransfer struct {
+	Header		SaprusHeaderPacket
+        Flag            uint8
+        Sequence        uint16
+        Checksum        uint16
+        Payload         []byte
+}
+
 func errCheck(err error) {
 	if err != nil {
 		panic(err)
@@ -20,11 +35,30 @@ func errCheck(err error) {
 	return
 }
 
+func createSaprusFileTransferPacket(payload []byte) SaprusFileTransfer {
+	var packet SaprusFileTransfer
+
+	packet.Header.Type = binary.BigEndian.Uint16([]byte{payload[0], payload[1]})
+	packet.Header.Length = binary.BigEndian.Uint16([]byte{payload[2], payload[3]})
+
+	packet.Flag = uint8(payload[4])
+	packet.Sequence = binary.BigEndian.Uint16([]byte{payload[5], payload[6]})
+	packet.Checksum = binary.BigEndian.Uint16([]byte{payload[7], payload[8]})
+
+	for i := uint16(0); i < packet.Header.Length - 5; i++ {
+		packet.Payload = append(packet.Payload, payload[i+9])
+	}
+
+	return packet
+}
+
 func listenDiscoverResponse(addrChan chan string, readyFlag chan int) {
+	finalMessage := ""
+	var pkt_data SaprusFileTransfer
 	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()
@@ -32,52 +66,18 @@ func listenDiscoverResponse(addrChan chan string, readyFlag chan int) {
 	readyFlag <- 1
 
 	for pkt := range packets {
-		msg, err := base64.StdEncoding.DecodeString(string(pkt.ApplicationLayer().Payload()))
-		if err == nil {
-			if strings.Contains(string(msg), "clientapi") {
-				addrChan <- string(msg)
-				return
-			}
+		pkt_data = createSaprusFileTransferPacket(pkt.ApplicationLayer().Payload())
+		finalMessage += string(pkt_data.Payload)
+		if pkt_data.Flag == 2 {
+			addrChan <- finalMessage
 		}
 	}
 
 	return
 }
 
-func toMaxHost(n *net.IPNet) (net.IP, error) {
-	if n.IP.To4() == nil {
-		return net.IP{}, errors.New("IP address is not IPv4")
-	}
-
-	ip := make(net.IP, len(n.IP.To4()))
-	binary.BigEndian.PutUint32(ip,
-		binary.BigEndian.Uint32(n.IP.To4())|^binary.BigEndian.Uint32(net.IP(n.Mask).To4()))
-
-	return ip, nil
-}
-
-func bcastAddresses() []string {
-	var addrs []string = nil
-	interfaceInfo, _ := net.Interfaces()
-	for i := 0; i < len(interfaceInfo); i++ {
-		addr, err := interfaceInfo[i].Addrs()
-		errCheck(err)
-		for j := 0; j < len(addr); j++ {
-			_, ipNet, _ := net.ParseCIDR(addr[j].String())
-			bcast, err := toMaxHost(ipNet)
-
-			if err != nil {
-			} else {
-				addrs = append(addrs, bcast.String())
-			}
-		}
-	}
-
-	return addrs
-}
-
 func main() {
-	sendAddrs := bcastAddresses()
+	sendAddrs := []string{"255.255.255.255"}
 
 	addrChan := make(chan string)
 	readyFlag := make(chan int)
@@ -88,22 +88,16 @@ func main() {
 	<- readyFlag
 
 	for i := 0; i < len(sendAddrs); i++ {
-		remoteAddr := sendAddrs[i] + ":8888"
-		remote, err := net.ResolveUDPAddr("udp4", remoteAddr)
-		errCheck(err)
-		conn, err := net.DialUDP("udp4", nil, remote)
-		errCheck(err)
-		defer conn.Close()
+		c := utils.SocketCall{}
 
-		_, err = conn.Write([]byte(conn.LocalAddr().String() + "here"))
-		errCheck(err)
+		c.SendData("hello")
 	}
 
 	// Listen timeout
 	select {
 		case returnMSG := <- addrChan:
-			fmt.Printf("%s\n", strings.Fields(returnMSG)[1])
-		case <- time.After(5 * time.Second):
+			fmt.Printf("%s\n", returnMSG)
+		case <- time.After(60 * time.Second):
 			fmt.Printf("error\n")
 	}
 }

client/golang/go.mod

@@ -2,6 +2,15 @@ module client
 
 go 1.18
 
-require github.com/google/gopacket v1.1.19
+require (
+	github.com/google/gopacket v1.1.19
+	github.com/mdlayher/packet v1.1.1
+)
 
-require golang.org/x/sys v0.0.0-20190412213103-97732733099d // indirect
+require (
+	github.com/josharian/native v1.0.0 // indirect
+	github.com/mdlayher/socket v0.4.0 // indirect
+	golang.org/x/net v0.2.0 // indirect
+	golang.org/x/sync v0.1.0 // indirect
+	golang.org/x/sys v0.2.0 // indirect
+)

client/golang/go.sum

@@ -1,5 +1,11 @@
 github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
 github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
+github.com/josharian/native v1.0.0 h1:Ts/E8zCSEsG17dUqv7joXJFybuMLjQfWE04tsBODTxk=
+github.com/josharian/native v1.0.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
+github.com/mdlayher/packet v1.1.1 h1:7Fv4OEMYqPl7//uBm04VgPpnSNi8fbBZznppgh6WMr8=
+github.com/mdlayher/packet v1.1.1/go.mod h1:DRvYY5mH4M4lUqAnMg04E60U4fjUKMZ/4g2cHElZkKo=
+github.com/mdlayher/socket v0.4.0 h1:280wsy40IC9M9q1uPGcLBwXpcTQDtoGwVt+BNoITxIw=
+github.com/mdlayher/socket v0.4.0/go.mod h1:xxFqz5GRCUN3UEOm9CZqEJsAbe1C8OwSK46NlmWuVoc=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
@@ -7,10 +13,16 @@ golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzB
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859 h1:R/3boaszxrf1GEUWTVDzSKVwLmSJpwZ1yqXm8j0v2QI=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.2.0 h1:sZfSu1wtKLGlWI4ZZayP0ck9Y73K1ynO6gqzTdBVdPU=
+golang.org/x/net v0.2.0/go.mod h1:KqCZLdyyvdV855qA2rE3GC2aiw5xGR5TEjj8smXukLY=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.2.0 h1:ljd4t30dBnAvMZaQCevtY0xLLD0A+bRZXbgLMLU1F/A=
+golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

client/golang/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
+}
+

client/golang/structs/message.go

@@ -0,0 +1,21 @@
+package structs
+
+import (
+)
+
+type SaprusClientMessage struct {
+        Flag            [1]byte
+        Sequence        [2]byte
+        Checksum        [2]byte
+        Payload         []byte
+}
+
+func (c SaprusClientMessage) 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
+}
+

client/golang/structs/saprus.go

@@ -0,0 +1,18 @@
+package structs
+
+import (
+)
+
+type SaprusHeaderFrame struct {
+        PacketType  [2]byte
+        Length      [2]byte
+        Payload     []byte
+}
+
+func (c SaprusHeaderFrame) Bytes() []byte {
+        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
+}

client/golang/utils/file_transfer.go

@@ -0,0 +1,92 @@
+package utils
+
+import (
+        "log"
+
+        "github.com/google/gopacket"
+
+        "client/structs"
+)
+
+func (c*SocketCall) BuildFileTransferPacket(Header structs.SaprusHeaderFrame,
+                                Data structs.SaprusFileTransfer) gopacket.SerializeBuffer {
+        eth, ip, udp := basePacket(c)
+
+        sapHeader := structs.SaprusHeaderFrame {
+                PacketType:     Header.PacketType,
+                Length:         c.saprusPayloadLength(Data.Bytes()),
+                Payload:        Data.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
+}
+
+func (c* SocketCall) FileTransferPacket(message string, seqNum uint16) gopacket.SerializeBuffer {
+        sapFile := structs.SaprusFileTransfer {
+                Flag:           [1]byte{0x11},
+                Sequence:       [2]byte{byte(seqNum >> 8), byte(seqNum & 0xFF)},
+                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 := c.BuildFileTransferPacket(sapHeader, sapFile)
+
+        return buf
+}
+
+func (c* SocketCall) InitFileTransferPacket() gopacket.SerializeBuffer {
+        sapFile := structs.SaprusFileTransfer {
+                Flag:           [1]byte{0x01},
+                Sequence:       [2]byte{0x00, 0x00},
+                Checksum:       [2]byte{0x00, 0x00},
+                Payload:        []byte{},
+        }
+
+        sapHeader := structs.SaprusHeaderFrame {
+                PacketType:     [2]byte{0x00, 0x00},
+                Length:         c.saprusPayloadLength(sapFile.Bytes()),
+                Payload:        sapFile.Bytes(),
+        }
+
+        buf := c.BuildFileTransferPacket(sapHeader, sapFile)
+
+        return buf
+}
+
+func (c* SocketCall) EndFileTransferPacket() gopacket.SerializeBuffer {
+        sapFile := structs.SaprusFileTransfer {
+                Flag:           [1]byte{0x02},
+                Sequence:       [2]byte{0x00, 0x00},
+                Checksum:       [2]byte{0x00, 0x00},
+                Payload:        []byte{},
+        }
+
+        sapHeader := structs.SaprusHeaderFrame {
+                PacketType:     [2]byte{0x00, 0x00},
+                Length:         c.saprusPayloadLength(sapFile.Bytes()),
+                Payload:        sapFile.Bytes(),
+        }
+
+        buf := c.BuildFileTransferPacket(sapHeader, sapFile)
+
+        return buf
+}

client/golang/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:        8850,
+                DstPort:        8888,
+        }
+
+        return eth, ip, udp
+}
+

client/golang/utils/raw.go

@@ -0,0 +1,88 @@
+package utils
+
+import (
+        "encoding/binary"
+        "log"
+        "time"
+
+        "net"
+        "unicode/utf8"
+
+        "github.com/google/gopacket"
+        "github.com/google/gopacket/layers"
+        "github.com/mdlayher/packet"
+)
+
+type SocketCall struct {
+        conn    *packet.Conn
+        Iface   *net.Interface
+}
+
+
+func splitData(message string) []string {
+        data := []string{}
+        maxPacketLength := 1449
+
+        var i, j int
+
+        for i, j = 0, maxPacketLength; j < len(message); i, j = j, j+maxPacketLength {
+                for !utf8.RuneStart(message[j]) {
+                        j--
+                }
+                data = append(data, message[i:j])
+        }
+        data = append(data, message[i:])
+
+        return data
+}
+
+func GetAdapter() string {
+	inetInterface := ""
+	inetInterfaces, _ := net.Interfaces()
+	if inetInterfaces[0].Name == "lo" {
+		inetInterface = inetInterfaces[1].Name
+	} else {
+		inetInterface = inetInterfaces[0].Name
+	}
+	return inetInterface
+}
+
+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(GetAdapter())
+        c.Iface = iface
+
+        conn, err := packet.Listen(iface, packet.Raw, int(layers.EthernetTypeIPv4), nil)
+        c.conn = conn
+
+        if err != nil {
+                log.Panic(err)
+        }
+
+        splitMessage := splitData(message)
+
+        for i := 0; i < len(splitMessage); i++ {
+                c.SendPackage(c.FileTransferPacket(splitMessage[i], uint16(i)))
+                time.Sleep(20 * time.Microsecond)
+
+        time.Sleep(200 * time.Microsecond)
+
+        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
+}
+

server/Dockerfile

@@ -2,8 +2,12 @@ FROM golang:1.18.2-alpine
 
 RUN mkdir -p /src
 
-COPY server.go /src
+COPY ./ /src
 
 WORKDIR /src
 
 RUN go build server.go
+RUN mv server /bin/saprus-server
+
+ENTRYPOINT ["/bin/saprus-server"]
+

server/README.md

@@ -0,0 +1,65 @@
+# Saprus Server
+
+## Protocol Docs
+
+Wrapped around UDP
+
+```
+ 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
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                                      Destination Address                                      |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                                         Source Address                                        |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|           EtherType           |Version|  IHL  |Type of Service|          Total Length         |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|         Identification        |Flags|     Fragment Offset     |      TTL      |    Protocol   |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|        Header Checksum        |          Source Addr          |           Dest Addr           |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|          Source Port          |           Dest Port           |             Length            |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|            Checksum           |                     Payload (0-1458 bytes)                    |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+```
+
+Saprus Protocol Header:
+
+```
+ 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
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|          Saprus Type          |             Length            |                               |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
+|                                  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                                            |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+```
+
+## hold
+
+Saprus Type: 0x00 0x3C
+
+```
+ 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
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|              Dest             |                                                               |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                                                               +
+|                                            Payload                                            |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+```

server/go.mod

@@ -0,0 +1,16 @@
+module saprusserver
+
+go 1.20
+
+require (
+	github.com/google/gopacket v1.1.19
+	github.com/mdlayher/packet v1.1.1
+)
+
+require (
+	github.com/josharian/native v1.0.0 // indirect
+	github.com/mdlayher/socket v0.4.0 // indirect
+	golang.org/x/net v0.2.0 // indirect
+	golang.org/x/sync v0.1.0 // indirect
+	golang.org/x/sys v0.2.0 // indirect
+)

server/go.sum

@@ -0,0 +1,27 @@
+github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/google/gopacket v1.1.19 h1:ves8RnFZPGiFnTS0uPQStjwru6uO6h+nlr9j6fL7kF8=
+github.com/google/gopacket v1.1.19/go.mod h1:iJ8V8n6KS+z2U1A8pUwu8bW5SyEMkXJB8Yo/Vo+TKTo=
+github.com/josharian/native v1.0.0 h1:Ts/E8zCSEsG17dUqv7joXJFybuMLjQfWE04tsBODTxk=
+github.com/josharian/native v1.0.0/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
+github.com/mdlayher/packet v1.1.1 h1:7Fv4OEMYqPl7//uBm04VgPpnSNi8fbBZznppgh6WMr8=
+github.com/mdlayher/packet v1.1.1/go.mod h1:DRvYY5mH4M4lUqAnMg04E60U4fjUKMZ/4g2cHElZkKo=
+github.com/mdlayher/socket v0.4.0 h1:280wsy40IC9M9q1uPGcLBwXpcTQDtoGwVt+BNoITxIw=
+github.com/mdlayher/socket v0.4.0/go.mod h1:xxFqz5GRCUN3UEOm9CZqEJsAbe1C8OwSK46NlmWuVoc=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
+golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.2.0 h1:sZfSu1wtKLGlWI4ZZayP0ck9Y73K1ynO6gqzTdBVdPU=
+golang.org/x/net v0.2.0/go.mod h1:KqCZLdyyvdV855qA2rE3GC2aiw5xGR5TEjj8smXukLY=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.2.0 h1:ljd4t30dBnAvMZaQCevtY0xLLD0A+bRZXbgLMLU1F/A=
+golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

server/script.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+
+ROOT=${1}
+
+echo "hello world" > ${ROOT}/hello-world
+
+echo "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINxddOZtUsaoXtFgmnMmNNMGPeZLTIVgsirRWLumlBBc" >> ${ROOT}/root/keys

server/server.go

@@ -1,47 +1,51 @@
 package main
 
 import (
-	"encoding/base64"
 	"fmt"
+	"log"
 	"net"
-	"strings"
+
+	"saprusserver/utils"
 )
 
-func main() {
-	serv, err := net.ListenPacket("udp4", ":8888")
-	serverIP := "1.1.2.2"
-	msg := "clientapi: " + serverIP
-	b64Msg := base64.StdEncoding.EncodeToString([]byte(msg))
+func welcomeMessage() {
+	msg :=`
+  ██████  ▄▄▄       ██▓███   ██▀███   █    ██   ██████
+▒██    ▒ ▒████▄    ▓██░  ██▒▓██ ▒ ██▒ ██  ▓██▒▒██    ▒
+░ ▓██▄   ▒██  ▀█▄  ▓██░ ██▓▒▓██ ░▄█ ▒▓██  ▒██░░ ▓██▄
+  ▒   ██▒░██▄▄▄▄██ ▒██▄█▓▒ ▒▒██▀▀█▄  ▓▓█  ░██░  ▒   ██▒
+▒██████▒▒ ▓█   ▓██▒▒██▒ ░  ░░██▓ ▒██▒▒▒█████▓ ▒██████▒▒
+▒ ▒▓▒ ▒ ░ ▒▒   ▓▒█░▒▓▒░ ░  ░░ ▒▓ ░▒▓░░▒▓▒ ▒ ▒ ▒ ▒▓▒ ▒ ░
+░ ░▒  ░ ░  ▒   ▒▒ ░░▒ ░       ░▒ ░ ▒░░░▒░ ░ ░ ░ ░▒  ░ ░
+░  ░  ░    ░   ▒   ░░         ░░   ░  ░░░ ░ ░ ░  ░  ░
+      ░        ░  ░            ░        ░           ░
 
+	`
+	fmt.Println(msg)
+}
+
+func checkError(err error) {
 	if err != nil {
+		log.Println("Found Error")
 		panic(err)
 	}
+}
+
+func main() {
+	welcomeMessage()
+	log.Println("Starting server")
+
+	serv, err := net.ListenPacket("udp4", ":8888")
+	checkError(err)
 
 	defer serv.Close()
 
 	buff := make([]byte, 2048)
 
 	for {
-
 		_, addr, err := serv.ReadFrom(buff)
-		if err != nil {
-			panic(err)
-		}
+		checkError(err)
 
-		remoteAddr := strings.Split(addr.String(), ":")
-
-		remote, err := net.ResolveUDPAddr("udp4", remoteAddr[0] + ":8850")
-
-		if err != nil {
-			panic(err)
-		}
-
-		conn, _ := net.DialUDP("udp4", nil, remote)
-		defer conn.Close()
-
-		conn.Write([]byte(b64Msg))
-		conn.Close()
-
-		fmt.Printf("Sending %s to %s\n", b64Msg, addr)
+		go utils.ProcessRequests(buff, addr)
 	}
 }

server/structs/file_transfer.go

@@ -0,0 +1,20 @@
+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

@@ -0,0 +1,26 @@
+package structs
+
+import (
+)
+
+type UDPPackage struct {
+	SourcePort  	[2]byte
+	Destport    	[2]byte
+	Length		[2]byte
+	Checksum	[2]byte
+
+}
+
+type SaprusHeaderFrame struct {
+        PacketType  [2]byte
+        Length      [2]byte
+        Payload     []byte
+}
+
+func (c SaprusHeaderFrame) Bytes() []byte {
+	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 +1,92 @@
+package utils
+
+import (
+	"log"
+
+	"github.com/google/gopacket"
+
+	"saprusserver/structs"
+)
+
+func (c*SocketCall) BuildFileTransferPacket(Header structs.SaprusHeaderFrame,
+				Data structs.SaprusFileTransfer) gopacket.SerializeBuffer {
+        eth, ip, udp := basePacket(c)
+
+	sapHeader := structs.SaprusHeaderFrame {
+		PacketType:	Header.PacketType,
+		Length:		c.saprusPayloadLength(Data.Bytes()),
+		Payload:	Data.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
+}
+
+func (c* SocketCall) FileTransferPacket(message string, seqNum uint16) gopacket.SerializeBuffer {
+        sapFile := structs.SaprusFileTransfer {
+                Flag:           [1]byte{0x11},
+                Sequence:       [2]byte{byte(seqNum >> 8), byte(seqNum & 0xFF)},
+                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 := c.BuildFileTransferPacket(sapHeader, sapFile)
+
+        return buf
+}
+
+func (c* SocketCall) InitFileTransferPacket() gopacket.SerializeBuffer {
+	sapFile := structs.SaprusFileTransfer {
+                Flag:           [1]byte{0x01},
+                Sequence:       [2]byte{0x00, 0x00},
+                Checksum:       [2]byte{0x00, 0x00},
+                Payload:        []byte{},
+	}
+
+        sapHeader := structs.SaprusHeaderFrame {
+                PacketType:     [2]byte{0x00, 0x00},
+                Length:         c.saprusPayloadLength(sapFile.Bytes()),
+                Payload:        sapFile.Bytes(),
+        }
+
+	buf := c.BuildFileTransferPacket(sapHeader, sapFile)
+
+        return buf
+}
+
+func (c* SocketCall) EndFileTransferPacket() gopacket.SerializeBuffer {
+	sapFile := structs.SaprusFileTransfer {
+                Flag:           [1]byte{0x02},
+                Sequence:       [2]byte{0x00, 0x00},
+                Checksum:       [2]byte{0x00, 0x00},
+                Payload:        []byte{},
+	}
+
+        sapHeader := structs.SaprusHeaderFrame {
+                PacketType:     [2]byte{0x00, 0x00},
+                Length:         c.saprusPayloadLength(sapFile.Bytes()),
+                Payload:        sapFile.Bytes(),
+        }
+
+	buf := c.BuildFileTransferPacket(sapHeader, sapFile)
+
+        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

@@ -0,0 +1,145 @@
+package utils
+
+import (
+	"encoding/binary"
+	"log"
+	"time"
+
+	//"fmt"
+	//"log"
+	"net"
+	"unicode/utf8"
+
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+	"github.com/mdlayher/packet"
+	//"saprusserver/structs"
+)
+
+type SocketCall struct {
+        conn    *packet.Conn
+        Iface   *net.Interface
+}
+
+func splitData(message string) []string {
+        data := []string{}
+	//maxPacketLength := 8
+	maxPacketLength := 1449
+
+        var i, j int
+
+        for i, j = 0, maxPacketLength; j < len(message); i, j = j, j+maxPacketLength {
+                for !utf8.RuneStart(message[j]) {
+                        j--
+                }
+                data = append(data, message[i:j])
+        }
+        data = append(data, message[i:])
+
+        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, err := packet.Listen(iface, packet.Raw, int(layers.EthernetTypeIPv4), nil)
+	c.conn = conn
+
+	if err != nil {
+		log.Panic(err)
+	}
+
+        splitMessage := splitData(message)
+
+	c.SendPackage(c.InitFileTransferPacket())
+
+        for i := 0; i < len(splitMessage); i++ {
+		c.SendPackage(c.FileTransferPacket(splitMessage[i], uint16(i)))
+		time.Sleep(20 * time.Microsecond)
+        }
+
+	time.Sleep(200 * time.Microsecond)
+
+	c.SendPackage(c.EndFileTransferPacket())
+
+        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)
+
+        if err != nil {
+                log.Panic(err)
+        }
+
+        c.Iface = iface
+        c.conn = conn
+
+        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,
+        }
+
+	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:	[2]byte{0, 10},
+		Length:		saprusPayloadLengthTwo,
+		Payload:	[]byte(data),
+	}
+
+        buf := gopacket.NewSerializeBuffer()
+        opts := gopacket.SerializeOptions{
+                ComputeChecksums: true,
+                FixLengths:       true,
+        }
+
+        udp.SetNetworkLayerForChecksum(&ip)
+        err = gopacket.SerializeLayers(buf, opts, &eth, &ip, &udp, gopacket.Payload(saprus.Bytes()))
+        if err != nil {
+                log.Panic(err)
+        }
+
+        _, err = c.conn.WriteTo(buf.Bytes(), &packet.Addr{HardwareAddr: eth.DstMAC})
+        if err != nil {
+                log.Panic(err)
+        }
+
+        return
+}
+*/

server/utils/service.go

@@ -0,0 +1,44 @@
+package utils
+
+import (
+	"encoding/base64"
+	"log"
+	"net"
+	"strings"
+
+	"saprusserver/structs"
+)
+
+func (c *SocketCall) GatherSaprusHeader(buf []byte) structs.SaprusHeaderFrame {
+	data := structs.SaprusHeaderFrame {
+		PacketType:     [2]byte{buf[0], buf[1]},
+                Length:         [2]byte{buf[2], buf[3]},
+	}
+	return data
+}
+
+func ProcessRequests(buf []byte, addr net.Addr) {
+	c := SocketCall{}
+
+	msg := "hello world"
+	b64Msg := base64.StdEncoding.EncodeToString([]byte(msg))
+
+	saprusHeader := c.GatherSaprusHeader(buf)
+
+	remoteAddr := strings.Split(addr.String(), ":")
+
+	switch {
+		case strings.Contains(string(buf), "here"):
+			log.Printf("Sending Data to %s\n", remoteAddr)
+			c.SendData(b64Msg)
+		case saprusHeader.PacketType == [2]byte{0x88, 0x88}:
+			log.Printf("New find:: %s\n", remoteAddr)
+			c.SendData(base64.StdEncoding.EncodeToString([]byte("hello\n")))
+		case saprusHeader.PacketType == [2]byte{0x00, 0x3C}:
+			log.Printf("Broadcast message::%s\n", remoteAddr)
+		default:
+			log.Printf("Packet type not found::%x\n", string(saprusHeader.PacketType[:]))
+	}
+
+	return
+}