From 7ca70894765db8cb6f696a57c81b34389880b57e Mon Sep 17 00:00:00 2001 From: Toni Date: Tue, 21 Jul 2026 21:19:50 +0200 Subject: [PATCH] send captured packets to server --- client/main.go | 85 +++++++++++++++++++++++++++++++++++++++---------- server/main.go | 46 ++++++++------------------ shared/proto.go | 1 + 3 files changed, 84 insertions(+), 48 deletions(-) diff --git a/client/main.go b/client/main.go index ef4cf47..997d4d8 100644 --- a/client/main.go +++ b/client/main.go @@ -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) + } + } +} diff --git a/server/main.go b/server/main.go index d6fe41b..e34f3c3 100644 --- a/server/main.go +++ b/server/main.go @@ -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") } diff --git a/shared/proto.go b/shared/proto.go index a7d7276..c488023 100644 --- a/shared/proto.go +++ b/shared/proto.go @@ -8,6 +8,7 @@ const ( unused uint16 = iota REQ_REGISTER RESP_REGISTER + REQ_DATA ) func Uint16(v uint16) []byte {