feat: add android

.github/workflows/build-android.yml

@@ -0,0 +1,91 @@
+name: Build Android
+
+on:
+  release:
+    types: [ published ]
+  push:
+    paths:
+      - "**/*.go"
+      - "go.mod"
+      - "go.sum"
+      - ".github/workflows/*.yml"
+  pull_request:
+    types:
+      - opened
+    paths:
+      - "**/*.go"
+      - "go.mod"
+      - "go.sum"
+
+permissions: write-all
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout codebase
+        uses: actions/checkout@v3
+
+      - name: Set up Go
+        run: |
+          wget https://go.dev/dl/go1.21.3.linux-amd64.tar.gz
+          sudo tar -C /usr/local -xzf go1.21.3.linux-amd64.tar.gz
+          export PATH=$PATH:/usr/local/go/bin
+
+      - name: Get project dependencies
+        run: go mod download
+
+      - name: Build Android AAR
+        run: |
+          go env
+          go install golang.org/x/mobile/cmd/gomobile@latest
+          go get golang.org/x/mobile/bind@latest
+          export PATH="/home/runner/go/bin:${PATH}"
+          mkdir -p build_assets
+          sudo apt update && sudo apt install openjdk-17-jdk
+          export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
+          export NDK_LTS_VERSION=23.2.8568313
+          export SDK_TOOLS_VERSION=10406996
+          export ANDROID_PLATFORM_VERSION=24
+          export ANDROID_HOME="/home/runner/android-sdk"
+          export ANDROID_SDK_ROOT=$ANDROID_HOME
+          export CMDLINE_TOOLS_ROOT="${ANDROID_HOME}/cmdline-tools/latest/bin"
+          export ADB_INSTALL_TIMEOUT=120
+          export PATH="${ANDROID_HOME}/emulator:${ANDROID_HOME}/cmdline-tools/latest/bin:${ANDROID_HOME}/tools:${ANDROID_HOME}/tools/bin:${ANDROID_HOME}/platform-tools:${ANDROID_HOME}/platform-tools/bin:${PATH}"
+          export ANDROID_NDK_HOME="/home/runner/android-sdk/ndk/${NDK_LTS_VERSION}"
+          export ANDROID_NDK_ROOT="${ANDROID_NDK_HOME}"
+          mkdir -p ${ANDROID_HOME}/cmdline-tools 
+          mkdir ${ANDROID_HOME}/platforms
+          mkdir ${ANDROID_HOME}/ndk
+          wget -O /tmp/cmdline-tools.zip -t 5 --no-verbose "https://dl.google.com/android/repository/commandlinetools-linux-${SDK_TOOLS_VERSION}_latest.zip"
+          unzip -q /tmp/cmdline-tools.zip -d ${ANDROID_HOME}/cmdline-tools
+          rm /tmp/cmdline-tools.zip
+          mv ${ANDROID_HOME}/cmdline-tools/cmdline-tools ${ANDROID_HOME}/cmdline-tools/latest
+          echo y | ${CMDLINE_TOOLS_ROOT}/sdkmanager "build-tools;${ANDROID_PLATFORM_VERSION}.0.0"
+          echo y | ${CMDLINE_TOOLS_ROOT}/sdkmanager "platforms;android-${ANDROID_PLATFORM_VERSION}"
+          echo y | ${CMDLINE_TOOLS_ROOT}/sdkmanager "ndk;${NDK_LTS_VERSION}"
+          sudo apt install -y --no-install-recommends g++ libc6-dev
+          gomobile init
+          gomobile bind -target=android -o build_assets/zju-connect.aar ./mobile
+
+      - name: Upload artifact
+        if: github.event_name != 'release'
+        uses: actions/upload-artifact@v3
+        with:
+          name: zju-connect-android-aar
+          path: build_assets/*
+
+      - name: Create ZIP archive
+        if: github.event_name == 'release'
+        run: |
+          pushd build_assets || exit 1
+          zip -9vr ../zju-connect-android-aar.zip .
+          popd || exit 1
+
+      - name: Upload release binary
+        if: github.event_name == 'release'
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+        run: |
+          gh release upload ${{ github.event.release.tag_name }} zju-connect-android-aar.zip

mobile/mobile.go

@@ -0,0 +1,72 @@
+package mobile
+
+import (
+	"github.com/mythologyli/zju-connect/client"
+	"github.com/mythologyli/zju-connect/log"
+	"github.com/mythologyli/zju-connect/stack/tun"
+)
+
+var vpnClient *client.EasyConnectClient
+
+func Login(server string, username string, password string) string {
+	log.Init()
+
+	vpnClient = client.NewEasyConnectClient(
+		server,
+		username,
+		password,
+		"",
+		false,
+		false,
+	)
+	err := vpnClient.Setup()
+	if err != nil {
+		return ""
+	}
+
+	log.Printf("EasyConnect client started")
+
+	clientIP, err := vpnClient.IP()
+	if err != nil {
+		return ""
+	}
+
+	return clientIP.String()
+}
+
+func DebugLogin(server string, username string, password string) string {
+	log.Init()
+	log.EnableDebug()
+
+	vpnClient = client.NewEasyConnectClient(
+		server,
+		username,
+		password,
+		"",
+		false,
+		false,
+	)
+	err := vpnClient.Setup()
+	if err != nil {
+		return ""
+	}
+
+	log.Printf("EasyConnect client started")
+
+	clientIP, err := vpnClient.IP()
+	if err != nil {
+		return ""
+	}
+
+	return clientIP.String()
+}
+
+func StartStack(fd int) {
+	vpnTUNStack, err := tun.NewStack(vpnClient)
+	if err != nil {
+		return
+	}
+
+	vpnTUNStack.SetupTun(fd)
+	vpnTUNStack.Run()
+}

stack/tun/stack.go

@@ -1,3 +1,5 @@
+//go:build !android
+
 package tun
 
 import (

stack/tun/stack_android.go

@@ -0,0 +1,131 @@
+package tun
+
+import (
+	"github.com/mythologyli/zju-connect/client"
+	"github.com/mythologyli/zju-connect/log"
+	"golang.org/x/net/ipv4"
+	"io"
+	"net"
+	"os"
+	"syscall"
+)
+
+const MTU uint32 = 1400
+
+type Stack struct {
+	endpoint *Endpoint
+	rvpnConn io.ReadWriteCloser
+}
+
+func (s *Stack) Run() {
+	var connErr error
+	s.rvpnConn, connErr = client.NewRvpnConn(s.endpoint.easyConnectClient)
+	if connErr != nil {
+		return
+	}
+	// Read from VPN server and send to TUN stack
+	go func() {
+		for {
+			buf := make([]byte, MTU)
+			n, err := s.rvpnConn.Read(buf)
+			if err != nil {
+				log.Printf("Error occurred while reading from VPN server: %v", err)
+				return
+			}
+			log.DebugPrintf("Recv: read %d bytes", n)
+			log.DebugDumpHex(buf[:n])
+
+			err = s.endpoint.Write(buf[:n])
+			if err != nil {
+				log.Printf("Error occurred while writing to TUN stack: %v", err)
+				return
+			}
+		}
+	}()
+
+	// Read from TUN stack and send to VPN server
+	for {
+		buf := make([]byte, MTU)
+		n, err := s.endpoint.Read(buf)
+		if err != nil {
+			log.Printf("Error occurred while reading from TUN stack: %v", err)
+			return
+		}
+
+		header, err := ipv4.ParseHeader(buf[:n])
+		if err != nil {
+			continue
+		}
+
+		// Filter out non-TCP/UDP packets otherwise error may occur
+		if header.Protocol != syscall.IPPROTO_TCP && header.Protocol != syscall.IPPROTO_UDP {
+			continue
+		}
+
+		n, err = s.rvpnConn.Write(buf[:n])
+		if err != nil {
+			log.Printf("Error occurred while writing to VPN server: %v", err)
+			return
+		}
+		log.DebugPrintf("Send: wrote %d bytes", n)
+		log.DebugDumpHex(buf[:n])
+	}
+}
+
+type Endpoint struct {
+	easyConnectClient *client.EasyConnectClient
+
+	readWriteCloser io.ReadWriteCloser
+	ip              net.IP
+
+	tcpDialer *net.Dialer
+	udpDialer *net.Dialer
+}
+
+func (ep *Endpoint) Write(buf []byte) error {
+	_, err := ep.readWriteCloser.Write(buf)
+	return err
+}
+
+func (ep *Endpoint) Read(buf []byte) (int, error) {
+	return ep.readWriteCloser.Read(buf)
+}
+
+func (s *Stack) AddRoute(target string) error {
+	return nil
+}
+
+func NewStack(easyConnectClient *client.EasyConnectClient) (*Stack, error) {
+	s := &Stack{}
+
+	s.endpoint = &Endpoint{
+		easyConnectClient: easyConnectClient,
+	}
+
+	var err error
+	s.endpoint.ip, err = easyConnectClient.IP()
+	if err != nil {
+		return nil, err
+	}
+
+	// We need this dialer to bind to device otherwise packets will not be sent via TUN
+	s.endpoint.tcpDialer = &net.Dialer{
+		LocalAddr: &net.TCPAddr{
+			IP:   s.endpoint.ip,
+			Port: 0,
+		},
+	}
+
+	s.endpoint.udpDialer = &net.Dialer{
+		LocalAddr: &net.UDPAddr{
+			IP:   s.endpoint.ip,
+			Port: 0,
+		},
+	}
+
+	return s, nil
+}
+
+func (s *Stack) SetupTun(fd int) {
+	s.endpoint.readWriteCloser = os.NewFile(uintptr(fd), "tun")
+}

stack/tun/stack_linux.go

@@ -1,3 +1,5 @@
+//go:build !android
+
 package tun
 
 import (