make ipv4 and ipv6 settings separate

src/sysinfo/network-interface.js

@@ -3,7 +3,8 @@
 exports = module.exports = {
     getServerIPv4,
     getServerIPv6,
-    testConfig
+    testIPv4Config,
+    testIPv6Config
 };
 
 const assert = require('assert'),
@@ -40,7 +41,7 @@ async function getServerIPv6(config) {
     return addresses[0];
 }
 
-async function testConfig(config) {
+async function testIPv4Config(config) {
     assert.strictEqual(typeof config, 'object');
     assert.strictEqual(typeof callback, 'function');
 
@@ -49,3 +50,13 @@ async function testConfig(config) {
     const [error] = await safe(getServerIPv4(config));
     return error || null;
 }
+
+async function testIPv6Config(config) {
+    assert.strictEqual(typeof config, 'object');
+    assert.strictEqual(typeof callback, 'function');
+
+    if (typeof config.ifname !== 'string') return new BoxError(BoxError.BAD_FIELD, 'ifname is not a string');
+
+    const [error] = await safe(getServerIPv6(config));
+    return error || null;
+}