[minor] Build-in the fallback

fallback.js

@@ -0,0 +1,52 @@
+'use strict';
+
+/*!
+ * bufferutil: WebSocket buffer utils
+ * Copyright(c) 2015 Einar Otto Stangvik <[email protected]>
+ * MIT Licensed
+ */
+
+module.exports.BufferUtil = {
+  merge: function(mergedBuffer, buffers) {
+    var offset = 0;
+
+    for (var i = 0, l = buffers.length; i < l; ++i) {
+      var buf = buffers[i];
+      buf.copy(mergedBuffer, offset);
+      offset += buf.length;
+    }
+  },
+  mask: function(source, mask, output, offset, length) {
+    var maskNum = mask.readUInt32LE(0, true);
+    var i = 0;
+
+    for (; i < length - 3; i += 4) {
+      var num = maskNum ^ source.readUInt32LE(i, true);
+      if (num < 0) num = 4294967296 + num;
+      output.writeUInt32LE(num, offset + i, true);
+    }
+
+    switch (length % 4) {
+      case 3: output[offset + i + 2] = source[i + 2] ^ mask[2];
+      case 2: output[offset + i + 1] = source[i + 1] ^ mask[1];
+      case 1: output[offset + i] = source[i] ^ mask[0];
+    }
+  },
+  unmask: function(data, mask) {
+    var maskNum = mask.readUInt32LE(0, true);
+    var length = data.length;
+    var i = 0;
+
+    for (; i < length - 3; i += 4) {
+      var num = maskNum ^ data.readUInt32LE(i, true);
+      if (num < 0) num = 4294967296 + num;
+      data.writeUInt32LE(num, i, true);
+    }
+
+    switch (length % 4) {
+      case 3: data[i + 2] = data[i + 2] ^ mask[2];
+      case 2: data[i + 1] = data[i + 1] ^ mask[1];
+      case 1: data[i] = data[i] ^ mask[0];
+    }
+  }
+};

index.js

@@ -1 +1,7 @@
-module.exports = require('bindings')('bufferutil');
+'use strict';
+
+try {
+  module.exports = require('bindings')('bufferutil');
+} catch (e) {
+  module.exports = require('./fallback');
+}