Improved dns IP resolution

dappnodedev · dappnodedev · commit 778a9a9b1b7b · 2024-01-12T15:58:39.000+01:00
diff --git a/src/src/openvpn/openvpnConfig.ts b/src/src/openvpn/openvpnConfig.ts
@@ -3,7 +3,7 @@ import { shell, shellArgs } from "../utils/shell";
 import { directoryIsEmptyOrEnoent } from "../utils/fs";
 import { PKI_PATH, PROXY_ARP_PATH } from "../params";
 import { logs } from "../logs";
-import { getDockerContainerIP } from "../utils/getDockerContainerIp";
+import { getContainerIP } from "../utils/getDockerContainerIp";
 
 type OvpnGenConfigFlags = {
   c: string; // Enable traffic among the clients connected to the VPN (Boolean, no value)
@@ -20,6 +20,7 @@ type OvpnGenConfigFlags = {
  * This function MUST be called before starting the openvpn binary
  */
 export async function initalizeOpenVpnConfig(hostname: string): Promise<void> {
+  const vpnContainerDomain = "vpn.dappnode";
   // Replicate environment used in entrypoint.sh
   const openVpnEnv = {
     OVPN_CN: hostname,
@@ -30,7 +31,7 @@ export async function initalizeOpenVpnConfig(hostname: string): Promise<void> {
   logs.info("Initializing OpenVPN configuration");
 
   // Check current IP range
-  const containerIp = getDockerContainerIP();
+  const containerIp = await getContainerIP(vpnContainerDomain);
 
   // If container IP is inside 172.33.0.0/16 --> generate credentials A
   if (containerIp && containerIp.startsWith("172.33.")) {
diff --git a/src/src/utils/getDockerContainerIp.ts b/src/src/utils/getDockerContainerIp.ts
@@ -1,24 +1,23 @@
-import os from 'os';
+import { Resolver } from 'dns';
 import { logs } from '../logs';
 
-export function getDockerContainerIP(): string | null {
-    const networkInterfaces = os.networkInterfaces();
+export async function getContainerIP(containerName: string): Promise<string | null> {
 
-    // Docker typically uses eth0 as the first network interface for bridge networks
-    const eth0 = networkInterfaces['eth0'];
+    const resolver = new Resolver();
 
-    if (!eth0) {
-        logs.error('Network interface eth0 not found.');
-        return null;
-    }
+    // Use Docker's DNS server to resolve container name.
+    resolver.setServers(['127.0.0.11']);
 
-    // Filter for IPv4 address
-    const ipv4 = eth0.find(info => info.family === 'IPv4');
-
-    if (!ipv4) {
-        console.error('IPv4 address for eth0 not found.');
-        return null;
-    }
-
-    return ipv4.address;
-}
+    return new Promise((resolve) => {
+        resolver.resolve4(containerName, (err, addresses) => {
+            if (err) {
+                logs.error(`Error resolving ${containerName} IP address: ${err}`);
+                resolve(null);
+            } else {
+                // Resolve with the first address found (if any).
+                logs.info(`Resolved ${containerName} IP addresses: ${addresses}`);
+                resolve(addresses.length > 0 ? addresses[0] : null);
+            }
+        });
+    });
+}
