tunnel: add gRPC over unix domain socket to the go backend

With gRPC it will be easier to extend the go backend API.
In this commit the Version function is reimplemented in gRPC.

Gitignore generated protobuf files.

5 files changed, 142 insertions, 6 deletions

diff --git a/tunnel/tools/libwg-go/.gitignore b/tunnel/tools/libwg-go/.gitignore
index d1638636..d69ee823 100644
--- a/tunnel/tools/libwg-go/.gitignore
+++ b/tunnel/tools/libwg-go/.gitignore
@@ -1 +1,2 @@
-build/
\ No newline at end of file
+build/
+/gen/
diff --git a/tunnel/tools/libwg-go/Makefile b/tunnel/tools/libwg-go/Makefile
index f1936e1d..ff907fdf 100644
--- a/tunnel/tools/libwg-go/Makefile
+++ b/tunnel/tools/libwg-go/Makefile
@@ -19,6 +19,7 @@ export CGO_LDFLAGS := $(CLANG_FLAGS) $(patsubst -Wl$(comma)--build-id=%,-Wl$(com
 export GOARCH := $(NDK_GO_ARCH_MAP_$(ANDROID_ARCH_NAME))
 export GOOS := android
 export CGO_ENABLED := 1
+export GOPATH ?= $(HOME)/go
 
 GO_VERSION := 1.20.3
 GO_PLATFORM := $(shell uname -s | tr '[:upper:]' '[:lower:]')-$(NDK_GO_ARCH_MAP_$(shell uname -m))
@@ -27,6 +28,13 @@ GO_HASH_darwin-amd64 := c1e1161d6d859deb576e6cfabeb40e3d042ceb1c6f444f617c3c9d76
 GO_HASH_darwin-arm64 := 86b0ed0f2b2df50fa8036eea875d1cf2d76cefdacf247c44639a1464b7e36b95
 GO_HASH_linux-amd64 := 979694c2c25c735755bf26f4f45e19e64e4811d661dd07b8c010f7a8e18adfca
 
+PROTOC_VERSION := 3.22.4
+PROTOC_GEN_GO := $(GOPATH)/bin/protoc-gen-go
+PROTOC := $(GRADLE_USER_HOME)/caches/protoc-bin-$(PROTOC_VERSION)/protoc
+PROTODIR = $(CURDIR)/../../src/main/proto
+PROTO_INCLUDEDIR = $(CURDIR)/../../build/extracted-include-protos/debug
+PBDIR = $(GOPATH)/pkg/mod
+
 default: $(DESTDIR)/libwg-go.so
 
 $(GRADLE_USER_HOME)/caches/golang/$(GO_TARBALL):
@@ -45,8 +53,25 @@ $(BUILDDIR)/go-$(GO_VERSION)/.prepared: $(GRADLE_USER_HOME)/caches/golang/$(GO_T
 	patch -p1 -f -N -r- -d "$(dir $@)" < goruntime-boottime-over-monotonic.diff && \
 	touch "$@"'
 
+$(PROTOC_GEN_GO): export GOARCH :=
+$(PROTOC_GEN_GO): export GOOS :=
+$(PROTOC_GEN_GO): export PATH := $(BUILDDIR)/go-$(GO_VERSION)/bin/:$(PATH)
+$(PROTOC_GEN_GO): $(BUILDDIR)/go-$(GO_VERSION)/.prepared Makefile
+	go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.28
+	go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.2
+
+gen/%.pb.go: export PATH := $(GOPATH)/bin:$(PATH)
+gen/%.pb.go: $(PROTODIR)/%.proto $(BUILDDIR)/go-$(GO_VERSION)/.prepared $(PROTOC_GEN_GO)
+	test -d gen || mkdir gen
+	$(PROTOC) -I $(PROTODIR) -I $(PROTO_INCLUDEDIR) --go_out=paths=source_relative:./gen $<
+
+gen/%_grpc.pb.go: export PATH := $(GOPATH)/bin:$(PATH)
+gen/%_grpc.pb.go: $(PROTODIR)/%.proto $(BUILDDIR)/go-$(GO_VERSION)/.prepared $(PROTOC_GEN_GO)
+	test -d gen || mkdir gen
+	$(PROTOC) -I $(PROTODIR) -I $(PROTO_INCLUDEDIR) --go-grpc_out=./gen --go-grpc_opt=paths=source_relative $<
+
 $(DESTDIR)/libwg-go.so: export PATH := $(BUILDDIR)/go-$(GO_VERSION)/bin/:$(PATH)
-$(DESTDIR)/libwg-go.so: $(BUILDDIR)/go-$(GO_VERSION)/.prepared go.mod
+$(DESTDIR)/libwg-go.so: $(BUILDDIR)/go-$(GO_VERSION)/.prepared go.mod api-android.go service.go gen/libwg.pb.go gen/libwg_grpc.pb.go jni.c
 	go build -tags linux -ldflags="-X golang.zx2c4.com/wireguard/ipc.socketDirectory=/data/data/$(ANDROID_PACKAGE_NAME)/cache/wireguard -buildid=" -v -trimpath -buildvcs=false -o "$@" -buildmode c-shared
 
 .DELETE_ON_ERROR:
diff --git a/tunnel/tools/libwg-go/api-android.go b/tunnel/tools/libwg-go/api-android.go
index d4e36480..484a89b0 100644
--- a/tunnel/tools/libwg-go/api-android.go
+++ b/tunnel/tools/libwg-go/api-android.go
@@ -48,6 +48,7 @@ func (l AndroidLogger) Printf(format string, args ...interface{}) {
 type TunnelHandle struct {
 	device *device.Device
 	uapi   net.Listener
+	logger *device.Logger
 }
 
 var tunnelHandles map[int32]TunnelHandle
@@ -208,20 +209,40 @@ func wgGetConfig(tunnelHandle int32) *C.char {
 
 //export wgVersion
 func wgVersion() *C.char {
+	return C.CString(Version())
+}
+
+func Version() string {
 	info, ok := debug.ReadBuildInfo()
 	if !ok {
-		return C.CString("unknown")
+		return "unknown"
 	}
 	for _, dep := range info.Deps {
 		if dep.Path == "golang.zx2c4.com/wireguard" {
 			parts := strings.Split(dep.Version, "-")
 			if len(parts) == 3 && len(parts[2]) == 12 {
-				return C.CString(parts[2][:7])
+				return parts[2][:7]
 			}
-			return C.CString(dep.Version)
+			return dep.Version
 		}
 	}
-	return C.CString("unknown")
+	return "unknown"
+}
+
+//export wgStartGrpc
+func wgStartGrpc(sock_path string) C.int{
+	tag := cstring("WireGuard/GoBackend/gRPC")
+	logger := &device.Logger{
+		Verbosef: AndroidLogger{level: C.ANDROID_LOG_DEBUG, tag: tag}.Printf,
+		Errorf:   AndroidLogger{level: C.ANDROID_LOG_ERROR, tag: tag}.Printf,
+	}
+
+	res, errmsg := StartGrpc(sock_path, logger)
+	if res < 0 {
+		logger.Verbosef("wgStartGrpc: %v (%v)", errmsg, res)
+	}
+
+	return C.int(res)
 }
 
 //export wgSetConfig
diff --git a/tunnel/tools/libwg-go/jni.c b/tunnel/tools/libwg-go/jni.c
index e47b0be5..b386579c 100644
--- a/tunnel/tools/libwg-go/jni.c
+++ b/tunnel/tools/libwg-go/jni.c
@@ -15,6 +15,7 @@ extern int wgGetSocketV6(int handle);
 extern char *wgGetConfig(int handle);
 extern char *wgVersion();
 extern int wgSetConfig(int handle, struct go_string settings);
+extern int wgStartGrpc();
 
 JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jstring settings)
 {
@@ -82,3 +83,15 @@ JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgSetConfig(
 	(*env)->ReleaseStringUTFChars(env, settings, settings_str);
 	return ret;
 }
+
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgStartGrpc(JNIEnv *env, jclass c, jstring sockname)
+{
+	const char *sockname_str = (*env)->GetStringUTFChars(env, sockname, 0);
+	size_t sockname_len = (*env)->GetStringUTFLength(env, sockname);
+	jint res = wgStartGrpc((struct go_string){
+		.str = sockname_str,
+		.n = sockname_len
+	});
+	(*env)->ReleaseStringUTFChars(env, sockname, sockname_str);
+	return res;
+}
diff --git a/tunnel/tools/libwg-go/service.go b/tunnel/tools/libwg-go/service.go
new file mode 100644
index 00000000..2a0dfb2d
--- /dev/null
+++ b/tunnel/tools/libwg-go/service.go
@@ -0,0 +1,76 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"os"
+
+	"google.golang.org/grpc"
+
+	gen "golang.zx2c4.com/wireguard/android/gen"
+	"golang.zx2c4.com/wireguard/device"
+)
+
+type LibwgServiceImpl struct {
+	gen.UnimplementedLibwgServer
+	logger *device.Logger
+}
+
+var _ gen.LibwgServer = (*LibwgServiceImpl)(nil)
+var server *grpc.Server
+
+func NewLibwgService(logger *device.Logger) gen.LibwgServer {
+	return &LibwgServiceImpl{logger: logger}
+}
+
+func StartGrpc(sock_path string, logger *device.Logger) (int, string) {
+	if server != nil {
+		return -1, "Already started"
+	}
+
+	if _, err := os.Stat(sock_path); err == nil {
+		if err := os.RemoveAll(sock_path); err != nil {
+			return -1, fmt.Sprintf("Cleanup failed: %v %v", sock_path, err)
+		}
+	}
+
+	listener, err := net.Listen("unix", sock_path)
+	if err != nil {
+		return -1, fmt.Sprintf("Listen failed: %v %v", sock_path, err)
+	}
+
+	server = grpc.NewServer()
+	service := NewLibwgService(logger)
+
+	gen.RegisterLibwgServer(server, service)
+
+	go func() {
+		server.Serve(listener)
+	}()
+
+	logger.Verbosef("gRPC started")
+
+	return 0, ""
+}
+
+func (e *LibwgServiceImpl) Version(ctx context.Context, req *gen.VersionRequest) (*gen.VersionResponse, error) {
+
+	r := &gen.VersionResponse{
+		Version: Version(),
+	}
+
+	return r, nil
+}
+
+func (e *LibwgServiceImpl) StopGrpc(ctx context.Context, req *gen.StopGrpcRequest) (*gen.StopGrpcResponse, error) {
+	if server != nil {
+		server.Stop()
+		server = nil
+	}
+
+	r := &gen.StopGrpcResponse{
+	}
+
+	return r, nil
+}