lib: fix resolve4 usage on node < v6.11.0

.travis.yml

@@ -0,0 +1,6 @@
+sudo: false
+language: node_js
+node_js:
+  - "4"
+  - "6"
+  - "latest"

lib/redns.js

@@ -4,6 +4,9 @@ const dns = require('dns');
 const async = require('async');
 const debug = require('debug')('redns');
 
+// See: https://github.com/nodejs/node/pull/9296
+const isLegacy = require('compare-versions')(process.version, 'v6.11.0') < 0;
+
 // For later monkey-patching in user code
 const dnsLookup = dns.lookup;
 
@@ -169,7 +172,7 @@ ReDNS.prototype._resolve = function _resolve(hostname, family, callback) {
       callback(new Error('DNS query timed out'));
     }, timeout);
 
-    resolver(hostname, options, (err, results) => {
+    const onResults = (err, results) => {
       // Timed out
       if (done)
         return;
@@ -183,9 +186,19 @@ ReDNS.prototype._resolve = function _resolve(hostname, family, callback) {
         if (typeof result === 'string')
           return { address: result, ttl: Infinity, family };
 
+        // Node.js before v6.11.0 has no way to get record's TTL
+        // fallback to `maxTTL` option
+        if (isLegacy)
+          return { address: result.address, ttl: Infinity, family };
+
         return { address: result.address, ttl: result.ttl, family };
       }));
-    });
+    };
+
+    if (isLegacy)
+      resolver(hostname, onResults);
+    else
+      resolver(hostname, options, onResults);
   }, callback);
 };
 

package.json

@@ -24,6 +24,7 @@
   },
   "dependencies": {
     "async": "^2.4.1",
+    "compare-versions": "^3.0.1",
     "debug": "^2.6.8"
   }
 }