Improve LAN preview network to detect local ip properly (#7170)

newIDE/electron-app/app/Utils/LocalNetworkIpFinder.js

@@ -1,12 +1,31 @@
 const os = require('os');
 
+/**
+ * As defined in RFC 1918, the following IPv4 address ranges are reserved for private networks:
+ * https://datatracker.ietf.org/doc/html/rfc1918#section-3
+ *
+ * @param {string} ip
+ * @returns {boolean}
+ */
+const isPrivateIp = ip => {
+  const [first, second] = ip.split('.').map(Number);
+  return (
+    first === 10 ||
+    (first === 172 && second >= 16 && second <= 31) ||
+    (first === 192 && second === 168)
+  );
+};
+
 /** @returns {string[]} */
 const getLocalNetworkIps = () => {
   return Object.entries(os.networkInterfaces())
     .flatMap(([name, interfaces]) =>
       name.match(/^(VirtualBox|VMware)/) ? [] : interfaces
     )
-    .filter(({ family, internal }) => family === 'IPv4' && !internal)
+    .filter(
+      ({ family, internal, address }) =>
+        family === 'IPv4' && !internal && isPrivateIp(address)
+    )
     .map(({ address }) => address);
 };
 
@@ -19,14 +38,6 @@ const findLocalIp = () => {
 
   if (!ipAddresses.length) return null;
 
-  let firstLocalIp = ipAddresses.find(
-    ipAddress => ipAddress.indexOf('192.168') === 0
-  );
-  if (firstLocalIp) return firstLocalIp;
-
-  firstLocalIp = ipAddresses.find(ipAddress => ipAddress.indexOf('192') === 0);
-  if (firstLocalIp) return firstLocalIp;
-
   return ipAddresses[0];
 };