dgram: fix double implicit bind error

bnoordhuis · bnoordhuis · commit 9e32c2ef3ede · 2012-12-31T17:53:00.000+01:00
Calling send() on an unbound socket forces an implicit bind to a random port. 332fea5 made the 'listening' event asynchronous. Unfortunately, it also introduced a bug where the implicit bind was tried more than once if send() was called again before the first bind operation completed. Address that by keeping track of the bind status and making sure that bind() is called only once. Fixes nodejs#4499.
diff --git a/lib/dgram.js b/lib/dgram.js
@@ -24,6 +24,10 @@ var events = require('events');
 
 var UDP = process.binding('udp_wrap').UDP;
 
+var BIND_STATE_UNBOUND = 0;
+var BIND_STATE_BINDING = 1;
+var BIND_STATE_BOUND = 2;
+
 // lazily loaded
 var dns = null;
 var net = null;
@@ -90,7 +94,7 @@ function Socket(type, listener) {
 
   this._handle = handle;
   this._receiving = false;
-  this._bound = false;
+  this._bindState = BIND_STATE_UNBOUND;
   this.type = type;
   this.fd = null; // compatibility hack
 
@@ -116,6 +120,8 @@ Socket.prototype.bind = function(port, address, callback) {
 
   // resolve address first
   self._handle.lookup(address, function(err, ip) {
+    self._bindState = BIND_STATE_UNBOUND;
+
     if (!self._handle)
       return; // handle has been closed in the mean time
 
@@ -132,11 +138,13 @@ Socket.prototype.bind = function(port, address, callback) {
     self._handle.onmessage = onMessage;
     self._handle.recvStart();
     self._receiving = true;
-    self._bound = true;
+    self._bindState = BIND_STATE_BOUND;
     self.fd = -42; // compatibility hack
 
     self.emit('listening');
   });
+
+  self._bindState = BIND_STATE_BINDING;
 };
 
 
@@ -175,8 +183,10 @@ Socket.prototype.send = function(buffer,
 
   self._healthCheck();
 
-  if (!self._bound) {
+  if (self._bindState == BIND_STATE_UNBOUND)
     self.bind(0, null);
+
+  if (self._bindState != BIND_STATE_BOUND) {
     self.once('listening', function() {
       self.send(buffer, offset, length, port, address, callback);
     });
diff --git a/test/simple/test-dgram-implicit-bind.js b/test/simple/test-dgram-implicit-bind.js
@@ -0,0 +1,49 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var dgram = require('dgram');
+
+var source = dgram.createSocket('udp4');
+var target = dgram.createSocket('udp4');
+var messages = 0;
+
+process.on('exit', function() {
+  assert.equal(messages, 2);
+});
+
+target.on('message', function(buf) {
+  if (buf.toString() === 'abc') ++messages;
+  if (buf.toString() === 'def') ++messages;
+  if (messages === 2) {
+    source.close();
+    target.close();
+  }
+});
+
+target.on('listening', function() {
+  // Second .send() call should not throw a bind error.
+  source.send(Buffer('abc'), 0, 3, common.PORT, '127.0.0.1');
+  source.send(Buffer('def'), 0, 3, common.PORT, '127.0.0.1');
+});
+
+target.bind(common.PORT);
