net: make .write() throw on bad input

Passing a non-buffer or non-string argument to Socket.prototype.write triggered
an assert:

  Assertion failed: (Buffer::HasInstance(args[0])), function Write,
  file ../src/stream_wrap.cc, line 289.

Fixes #2532.

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/net.js b/lib/net.js
index 072896b4c4e..85479412b2d 100644
--- a/lib/net.js
+++ b/lib/net.js
@@ -424,8 +424,10 @@ Socket.prototype.write = function(data, arg1, arg2) {
   }
 
   // Change strings to buffers. SLOW
-  if (typeof data == 'string') {
+  if (typeof data === 'string') {
     data = new Buffer(data, encoding);
+  } else if (!Buffer.isBuffer(data)) {
+    throw new TypeError("First argument must be a buffer or a string.");
   }
 
   this.bytesWritten += data.length;