build.sh: auto-install UPX, compress binaries

build.sh

@@ -47,4 +47,44 @@ go build -o bin/implant ./implant/main.go
 echo "Building build-implant..."
 go build -o bin/build-implant ./cmd/build-implant/main.go
 
+install_upx() {
+	local os arch upx_url upx_file
+
+	os="$(uname -s | tr '[:upper:]' '[:lower:]')"
+	arch="$(uname -m)"
+	case "$arch" in
+		x86_64)  arch=amd64 ;;
+		aarch64|arm64) arch=arm64 ;;
+	esac
+
+	echo "UPX not found. Downloading UPX for ${os}/${arch}..."
+
+	upx_url="https://github.com/upx/upx/releases/download/v5.0.0/upx-5.0.0-${arch}_${os}.tar.xz"
+	upx_file="/tmp/$(basename "$upx_url")"
+
+	curl -#Lo "$upx_file" "$upx_url"
+	sudo tar -C /usr/local -xJf "$upx_file" --strip-components=1 upx-5.0.0-${arch}_${os}/upx
+	rm -f "$upx_file"
+
+	export PATH="/usr/local/bin:$PATH"
+	echo "UPX installed: $(upx --version | head -1)"
+}
+
+if ! command -v upx &>/dev/null; then
+	if [ -x /usr/local/bin/upx ]; then
+		export PATH="/usr/local/bin:$PATH"
+	else
+		install_upx
+	fi
+fi
+
+echo "Compressing server..."
+upx --best --lzma bin/server 2>/dev/null || true
+
+echo "Compressing implant..."
+upx --best --lzma bin/implant 2>/dev/null || true
+
+echo "Compressing build-implant..."
+upx --best --lzma bin/build-implant 2>/dev/null || true
+
 echo "Done. Binaries in ./bin/"