Build linux with musl-cross (#1960)

Makefile

@@ -34,21 +34,19 @@ $(BUILDDIR)/apple/Tun2socks.xcframework: $(BUILDDIR)/ios/Tun2socks.xcframework $
 	find $^ -name "Tun2socks.framework" -type d | xargs -I {} echo " -framework {} " | \
 		xargs xcrun xcodebuild -create-xcframework -output "$@"
 
-XGO=$(GOBIN)/xgo
 TUN2SOCKS_VERSION=v1.16.11
-XGO_LDFLAGS='-w -X main.version=$(TUN2SOCKS_VERSION)'
+# -w disable DWARF generation
+LDFLAGS='-static -w -X main.version=$(TUN2SOCKS_VERSION)'
 ELECTRON_PKG="./client/src/tun2socks/outline/electron"
 
 # TODO: build directly when on linux
 LINUX_BUILDDIR=$(BUILDDIR)/linux
 
 linux: $(LINUX_BUILDDIR)/tun2socks
 
-$(LINUX_BUILDDIR)/tun2socks: $(XGO)
-	mkdir -p "$(LINUX_BUILDDIR)/$(IMPORT_PATH)"
-	$(XGO) -ldflags $(XGO_LDFLAGS) --targets=linux/amd64 -dest "$(LINUX_BUILDDIR)" -pkg $(ELECTRON_PKG) .
-	mv "$(LINUX_BUILDDIR)/$(IMPORT_PATH)-linux-amd64" "$@"
-	rm -r "$(LINUX_BUILDDIR)/$(IMPORT_HOST)"
+$(LINUX_BUILDDIR)/tun2socks:
+	mkdir -p "$(@D)"
+	GOOS=linux GOARCH=amd64 CGO_ENABLED=1 CC='zig cc -target x86_64-linux' go build -trimpath -ldflags=--extldflags=$(LDFLAGS) -o "$@" $(ELECTRON_PKG)
 
 # TODO: build directly when on windows
 WINDOWS_BUILDDIR=$(BUILDDIR)/windows
@@ -57,15 +55,12 @@ windows: $(WINDOWS_BUILDDIR)/tun2socks.exe
 
 $(WINDOWS_BUILDDIR)/tun2socks.exe:
 	mkdir -p "$(@D)"
-	GOOS=windows GOARCH=amd64 CGO_ENABLED=1 CC="x86_64-w64-mingw32-gcc" go build --ldflags=--extldflags=$(XGO_LDFLAGS) -o "$@" $(ELECTRON_PKG)
+	GOOS=windows GOARCH=amd64 CGO_ENABLED=1 CC='zig cc -target x86_64-windows' go build -trimpath -ldflags=--extldflags=$(LDFLAGS) -o "$@" $(ELECTRON_PKG)
 
 $(GOMOBILE): go.mod
 	mkdir -p "$(@D)"
 	go build -o "$(@D)" golang.org/x/mobile/cmd/gomobile golang.org/x/mobile/cmd/gobind
 
-$(XGO): go.mod
-	env GOBIN="$(GOBIN)" go install github.com/crazy-max/xgo
-
 go.mod: tools.go
 	go mod tidy
 	touch go.mod

src/electron/README.md

@@ -2,19 +2,6 @@
 
 Unlike the Android and Apple clients, the Windows and Linux clients use the Electron framework, rather than Cordova.
 
-You will need [Docker](https://www.docker.com/) installed to build the Electron clients.
-
-> If you can't use Docker, you can use [podman](https://podman.io) as substitute by running the following (for macOS):
-
-```sh
-podman machine init
-sudo ln -s $(which podman) /usr/local/bin/docker
-sudo /opt/homebrew/Cellar/podman/<podman version>/bin/podman-mac-helper install
-podman machine start
-```
-
-> You may run into the error: `/var/folders/<path>/xgo-cache: no such file or directory`. If so, simply create that directory with `mkdir -p /var/folders/<path>/xgo-cache` and try again.
-
 To build the Electron clients, run (it will also package an installer executable into `build/dist`):
 
 ```sh
@@ -27,28 +14,21 @@ To run the Electron clients, run:
 npm run action electron/start [windows|linux]
 ```
 
-## Windows
+## Cross-Compiling
 
-To build for Windows on a macOS, you need to first install [MinGW-w64](https://www.mingw-w64.org/) v11.0.1+.
+To build the app for a platform target on a different host target, you will need a cross-compiler. We use [zig to cross-compile with cgo](https://dev.to/kristoff/zig-makes-go-cross-compilation-just-work-29ho).
 
-With [MacPorts](https://www.mingw-w64.org/downloads/#macports) (official channel):
+[Install zig](https://ziglang.org/learn/getting-started/#installing-zig) and make sure it's in the PATH.
 
-```sh
-sudo port install x86_64-w64-mingw32-gcc @11.0.1
-```
-
-With Homebrew (unofficial, how to ensure consistent version?):
+You can download the binary tarball, or [use a package manager](https://github.com/ziglang/zig/wiki/Install-Zig-from-a-Package-Manager), like Homebrew:
 
 ```sh
-brew install mingw-w64
+brew install zig 
 ```
 
-You can also build it on Ubuntu. To install MinGW-w64:
-
-```sh
-apt update && apt install -y gcc-mingw-w64-x86-64
-```
+## Release
 
 To build the _release_ version of Windows installer, you'll also need:
 
 - [Java 8+ Runtime](https://www.java.com/en/download/). This is required for the cross-platform Windows executable signing tool [Jsign](https://ebourg.github.io/jsign/). If you don't need to sign the executables, feel free to skip this.
+