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send captured packets to server

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This commit is contained in:
Antoni Piasecki
2026-07-21 21:19:50 +02:00
parent 8a45d91e8d
commit 7ca7089476
3 changed files with 84 additions and 48 deletions
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85
client/main.go
View File

@@ -5,14 +5,24 @@ import (
"log"
"net"
"os"
"os/exec"
"baalvpn/shared"
"github.com/songgao/packets/ethernet"
"github.com/songgao/water"
)
const SERVER_IP = "172.20.12.47"
const (
SERVER_IP = "172.20.12.47"
IFACE_NAME = "baalvpn"
)
var (
internalIP net.IP = nil
serverAddr *net.UDPAddr
iface *water.Interface
conn *net.UDPConn
)
func main() {
@@ -24,34 +34,34 @@ func main() {
if err != nil {
panic(err)
}
listener, err := net.ListenUDP("udp", listenAddr)
conn, err = net.ListenUDP("udp", listenAddr)
if err != nil {
panic(err)
}
defer listener.Close()
defer conn.Close()
go receivePackets(listener)
register(listener)
serverAddr, err = net.ResolveUDPAddr("udp", SERVER_IP+":38000")
if err != nil {
panic(err)
}
go receivePackets()
register()
<-make(chan int) // block forever
}
func register(c *net.UDPConn) {
serverAddr, err := net.ResolveUDPAddr("udp", SERVER_IP+":38000")
if err != nil {
panic(err)
}
func register() {
req := shared.BuildPkt(shared.REQ_REGISTER, []byte{})
if _, err := c.WriteToUDP(req, serverAddr); err != nil {
if _, err := conn.WriteToUDP(req, serverAddr); err != nil {
panic(err)
}
}
func receivePackets(listener *net.UDPConn) {
func receivePackets() {
for {
buffer := make([]byte, 50000)
n, addr, err := listener.ReadFromUDP(buffer)
n, addr, err := conn.ReadFromUDP(buffer)
if err != nil {
log.Println(err)
continue
@@ -59,12 +69,16 @@ func receivePackets(listener *net.UDPConn) {
if n == 0 {
continue
}
if addr.String() != serverAddr.String() {
log.Println("non-server connection rejected")
continue
}
go receivePacket(listener, buffer[:n], addr)
go receivePacket(buffer[:n])
}
}
func receivePacket(c *net.UDPConn, pkt []byte, addr *net.UDPAddr) {
func receivePacket(pkt []byte) {
if len(pkt) < 4 {
log.Println("packet too short")
return
@@ -81,7 +95,46 @@ func receivePacket(c *net.UDPConn, pkt []byte, addr *net.UDPAddr) {
case shared.RESP_REGISTER:
internalIP = net.IP(pkt[4:])
log.Println("Received IP from the server:", internalIP.String())
initInterface()
go sendPackets()
default:
log.Println("unknown packet type")
}
}
func initInterface() {
config := water.Config{DeviceType: water.TAP}
config.Name = IFACE_NAME
var err error
iface, err = water.New(config)
if err != nil {
panic(err)
}
if err := exec.Command("ip", "addr", "add", internalIP.String()+"/24", "dev", IFACE_NAME).Run(); err != nil {
panic(err)
}
if err := exec.Command("ip", "link", "set", "dev", IFACE_NAME, "up").Run(); err != nil {
panic(err)
}
}
func sendPackets() {
log.Println("Listening for packets...")
var frame ethernet.Frame
for {
frame.Resize(1500)
n, err := iface.Read([]byte(frame))
if err != nil {
panic(err)
}
frame = frame[:n]
pkt := shared.BuildPkt(shared.REQ_DATA, frame)
if _, err := conn.WriteToUDP(pkt, serverAddr); err != nil {
log.Println(err)
}
}
}

46
server/main.go
View File

@@ -2,6 +2,7 @@ package main
import (
"encoding/binary"
"encoding/hex"
"fmt"
"log"
"net"
@@ -11,7 +12,6 @@ import (
"baalvpn/shared"
"github.com/songgao/packets/ethernet"
"github.com/songgao/water"
)
@@ -26,6 +26,7 @@ var (
peers = map[string]*Peer{}
peersMutex sync.Mutex
nextIP = 3
iface *water.Interface
)
func main() {
@@ -36,47 +37,25 @@ func main() {
config := water.Config{DeviceType: water.TAP}
config.Name = IFACE_NAME
iface, err := water.New(config)
var err error
iface, err = water.New(config)
if err != nil {
panic(err)
}
if err := exec.Command("ip", "addr", "add", "10.1.0.10/24", "dev", IFACE_NAME).Run(); err != nil {
if err := exec.Command("ip", "addr", "add", "10.1.0.2/24", "dev", IFACE_NAME).Run(); err != nil {
panic(err)
}
if err := exec.Command("ip", "link", "set", "dev", IFACE_NAME, "up").Run(); err != nil {
panic(err)
}
log.Println("Listening...")
go receivePackets()
sendPackets(iface)
}
func sendPackets(iface *water.Interface) {
var frame ethernet.Frame
for {
frame.Resize(1500)
n, err := iface.Read([]byte(frame))
if err != nil {
panic(err)
}
frame = frame[:n]
if frame.Destination()[0]&0x01 == 0x01 {
log.Println("multicast")
continue
}
log.Printf("Dst: %s\n", frame.Destination())
log.Printf("Src: %s\n", frame.Source())
log.Printf("Ethertype: % x\n", frame.Ethertype())
log.Printf("Payload: % x\n", frame.Payload())
}
receivePackets()
}
func receivePackets() {
log.Println("Listening for packets...")
listenAddr, err := net.ResolveUDPAddr("udp", ":38000")
if err != nil {
panic(err)
@@ -102,7 +81,7 @@ func receivePackets() {
}
}
func receivePacket(c *net.UDPConn, pkt []byte, addr *net.UDPAddr) {
func receivePacket(conn *net.UDPConn, pkt []byte, addr *net.UDPAddr) {
if len(pkt) < 4 {
log.Println("packet too short")
return
@@ -135,9 +114,12 @@ func receivePacket(c *net.UDPConn, pkt []byte, addr *net.UDPAddr) {
}
resp := shared.BuildPkt(shared.RESP_REGISTER, net.ParseIP(internalIP).To4())
if _, err := c.WriteToUDP(resp, addr); err != nil {
log.Printf("register WriteToUDP: %v\n", err)
if _, err := conn.WriteToUDP(resp, addr); err != nil {
log.Println(err)
}
case shared.REQ_DATA:
fmt.Println("received packet from " + peerIP + ":")
fmt.Println(hex.EncodeToString(pkt[4:]))
default:
log.Println("unknown packet type")
}

1
shared/proto.go
View File

@@ -8,6 +8,7 @@ const (
unused uint16 = iota
REQ_REGISTER
RESP_REGISTER
REQ_DATA
)
func Uint16(v uint16) []byte {