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 10c695e4..6c47c2d7 100644
--- a/tunnel/tools/libwg-go/Makefile
+++ b/tunnel/tools/libwg-go/Makefile
@@ -18,6 +18,7 @@ export CGO_LDFLAGS := $(CLANG_FLAGS) $(LDFLAGS) -Wl,-soname=libwg-go.so
 export GOARCH := $(NDK_GO_ARCH_MAP_$(ANDROID_ARCH_NAME))
 export GOOS := android
 export CGO_ENABLED := 1
+export GOPATH ?= $(HOME)/go
 
 GO_VERSION := 1.20.2
 GO_PLATFORM := $(shell uname -s | tr '[:upper:]' '[:lower:]')-$(NDK_GO_ARCH_MAP_$(shell uname -m))
@@ -26,6 +27,13 @@ GO_HASH_darwin-amd64 := c93b8ced9517d07e1cd4c362c6e2d5242cb139e29b417a328fbf19ad
 GO_HASH_darwin-arm64 := 7343c87f19e79c0063532e82e1c4d6f42175a32d99f7a4d15e658e88bf97f885
 GO_HASH_linux-amd64 := 4eaea32f59cde4dc635fbc42161031d13e1c780b87097f4b4234cfce671f1768
 
+PROTOC_VERSION := 3.20.1
+PROTOC_GEN_GO := $(GOPATH)/bin/protoc-gen-go
+PROTOC := $(GRADLE_USER_HOME)/caches/protoc-$(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):
@@ -44,8 +52,25 @@ $(BUILDDIR)/go-$(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/$(ANDROID_PACKAGE_NAME)/cache/wireguard" -v -trimpath -o "$@" -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 d47c5d76..fd0142e1 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)
 }
 
 func main() {}
diff --git a/tunnel/tools/libwg-go/jni.c b/tunnel/tools/libwg-go/jni.c
index 7ad94d35..121729a7 100644
--- a/tunnel/tools/libwg-go/jni.c
+++ b/tunnel/tools/libwg-go/jni.c
@@ -14,6 +14,7 @@ extern int wgGetSocketV4(int handle);
 extern int wgGetSocketV6(int handle);
 extern char *wgGetConfig(int handle);
 extern char *wgVersion();
+extern int wgStartGrpc();
 
 JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jstring settings)
 {
@@ -69,3 +70,15 @@ JNIEXPORT jstring JNICALL Java_com_wireguard_android_backend_GoBackend_wgVersion
 	free(version);
 	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
+}