I recently updated from node 0.8.xx to 0.10.xx and found out that the following code will create an exception.

dgram.js:381
 throw new errnoException(process._errno, 'addMembership');
 ^
Error: addMembership EBADF

After some searching I found this issue, which shows that they changed bind(port,[addr]) to be asynchronous.   The solution is to change

udpsock.bind(port);
udpsock.addMembership(mcastAddr);

to

udpsock.bind(port,null,function(){
  udpsock.addMembership(mcastAddr);
});

I hope this helps someone else.