net: Provide better error when writing after FIN

The stock writable stream "write after end" message is overly vague, if
you have clearly not called end() yourself yet.

When we receive a FIN from the other side, and call destroySoon() as a
result, then generate an EPIPE error (which is what would happen if you
did actually write to the socket), with a message explaining what
actually happened.

1 files changed, 27 insertions, 1 deletions

diff --git a/lib/net.js b/lib/net.js
index 934f9f2ea2..023d30b173 100644
--- a/lib/net.js
+++ b/lib/net.js
@@ -240,8 +240,31 @@ function onSocketEnd() {
     this.read(0);
   }
 
-  if (!this.allowHalfOpen)
+  if (!this.allowHalfOpen) {
+    this.write = writeAfterFIN;
     this.destroySoon();
+  }
+}
+
+// Provide a better error message when we call end() as a result
+// of the other side sending a FIN.  The standard 'write after end'
+// is overly vague, and makes it seem like the user's code is to blame.
+function writeAfterFIN(chunk, encoding, cb) {
+  if (typeof encoding === 'function') {
+    cb = encoding;
+    encoding = null;
+  }
+
+  var er = new Error('This socket has been closed by the other party');
+  er.code = 'EPIPE';
+  var self = this;
+  // TODO: defer error events consistently everywhere, not just the cb
+  self.emit('error', er);
+  if (typeof cb === 'function') {
+    process.nextTick(function() {
+      cb(er);
+    });
+  }
 }
 
 exports.Socket = Socket;
@@ -708,6 +731,9 @@ function connect(self, address, port, addressType, localAddress) {
 
 
 Socket.prototype.connect = function(options, cb) {
+  if (this.write !== Socket.prototype.write)
+    this.write = Socket.prototype.write;
+
   if (typeof options !== 'object') {
     // Old API:
     // connect(port, [host], [cb])