1 files changed, 40 insertions, 0 deletions

diff --git a/packages/create-turbo/src/utils/isOnline.ts b/packages/create-turbo/src/utils/isOnline.ts
new file mode 100644
index 0000000..f02b2e6
--- /dev/null
+++ b/packages/create-turbo/src/utils/isOnline.ts
@@ -0,0 +1,40 @@
+import { execSync } from "child_process";
+import dns from "dns";
+import url from "url";
+
+function getProxy(): string | undefined {
+  if (process.env.https_proxy) {
+    return process.env.https_proxy;
+  }
+
+  try {
+    const httpsProxy = execSync("npm config get https-proxy").toString().trim();
+    return httpsProxy !== "null" ? httpsProxy : undefined;
+  } catch (e) {
+    return;
+  }
+}
+
+export function isOnline(): Promise<boolean> {
+  return new Promise((resolve) => {
+    dns.lookup("registry.yarnpkg.com", (registryErr) => {
+      if (!registryErr) {
+        return resolve(true);
+      }
+
+      const proxy = getProxy();
+      if (!proxy) {
+        return resolve(false);
+      }
+
+      const { hostname } = url.parse(proxy);
+      if (!hostname) {
+        return resolve(false);
+      }
+
+      dns.lookup(hostname, (proxyErr) => {
+        resolve(proxyErr == null);
+      });
+    });
+  });
+}