Fix array argument being altered

fixes #10
closes #11

Author: elmigranto

HISTORY.md

@@ -1,6 +1,7 @@
 unreleased
 ==========
 
+  * Fix array argument being altered
   * deps: ipaddr.js@1.4.0
 
 1.1.4 / 2017-03-24

index.js

@@ -86,11 +86,13 @@ function compile(val) {
     throw new TypeError('argument is required');
   }
 
-  var trust = typeof val === 'string'
-    ? [val]
-    : val;
+  var trust;
 
-  if (!Array.isArray(trust)) {
+  if (typeof val === 'string') {
+    trust = [val];
+  } else if (Array.isArray(val)) {
+    trust = val.slice();
+  } else {
     throw new TypeError('unsupported trust argument');
   }
 

test/test.js

@@ -61,6 +61,13 @@ describe('proxyaddr(req, trust)', function () {
         assert.doesNotThrow(proxyaddr.bind(null, req, ['loopback', '10.0.0.1']));
       });
 
+      it('should not alter input array', function () {
+        var arr = ['loopback', '10.0.0.1'];
+        var req = createReq('127.0.0.1');
+        assert.doesNotThrow(proxyaddr.bind(null, req, arr));
+        assert.deepEqual(arr, ['loopback', '10.0.0.1']);
+      });
+
       it('should reject non-IP', function () {
         var req = createReq('127.0.0.1');
         assert.throws(proxyaddr.bind(null, req, 'blargh'), /invalid IP address/);
@@ -481,6 +488,12 @@ describe('proxyaddr.compile(trust)', function () {
         assert.throws(proxyaddr.compile.bind(null, '::ffff:a00:2/136'), /invalid range on address/);
         assert.throws(proxyaddr.compile.bind(null, '::ffff:a00:2/-46'), /invalid range on address/);
       });
+
+      it('should not alter input array', function () {
+        var arr = ['loopback', '10.0.0.1'];
+        assert.equal(typeof proxyaddr.compile(arr), 'function');
+        assert.deepEqual(arr, ['loopback', '10.0.0.1']);
+      });
     });
   });
 });