Same codes, different results in REPL and shell environments about UDP socket

[mailto1587]

It was a absolutely strange problem, the codes is quite simple:

```

~  cat main.js 

var dgram = require('dgram'),

    sock = dgram.createSocket('udp4');

sock.bind();

sock.setBroadcast(true);

```

And I first executed in shell environment with `node` command:

```

~ node main.js 

dgram.js:348

    throw errnoException(process._errno, 'setBroadcast');

          ^

Error: setBroadcast EBADF

    at errnoException (dgram.js:457:11)

    at Socket.setBroadcast (dgram.js:348:11)

    at Object.<anonymous> (/Users/mailto1587/main.js:5:6)

    at Module._compile (module.js:456:26)

    at Object.Module._extensions..js (module.js:474:10)

    at Module.load (module.js:356:32)

    at Function.Module._load (module.js:312:12)

    at Function.Module.runMain (module.js:497:10)

    at startup (node.js:119:16)

    at node.js:906:3

```

An exception raised, but what makes me surprised is that the same codes in REPL environment was successfully executed:

```

~  node

> var dgram = require('dgram'),

... sock = dgram.createSocket('udp4');

undefined

> sock.bind();

undefined

> sock.setBroadcast(true);

undefined

> 

```

An abnormal issue, help please!

-- 
mailto1587
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[mscdex]

On Monday, June 23, 2014 6:49:35 PM UTC-4, Xiadong Zhu wrote:

An abnormal issue, help please!

It's most likely a timing issue. The non-REPL code is running within the same tick, so the socket isn't actually bound until some time later, but you try and use a method (setBroadcast) that expects a bound socket. The REPL code works because there is a long enough delay between the `sock.bind()` and `sock.setBroadcast()` such that the socket is bound by the time you press enter after typing `sock.setBroadcast()`.

The solution is to wait for the 'listening' event, either explicitly with `sock.on('listening', ...);` or by passing a callback to `sock.bind();` and calling your `sock.setBroadcast()`, etc. inside that callback/event handler.

[mailto1587]

I got it! Thank you very much!

-- 
mailto1587
Sent with Airmail

开启 2014年6月24日 at 下午5:06:02, mscdex (msc...@gmail.com) 写:

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