What exactly does listen() do from winsock 1.1

*DEAD* · 12-10-2007, 03:05 AM

Hi, im designing a login server for a game, and every time the server receives a connection i intend to a launch a new thread. I was playing with the code from another server i made which was only capable of connecting to one client, and basically it does this.

Code:

//define the listening socket above
listen(listenSock, 10)
//define a server socket
serverSock = accept(listenSock, NULL, NULL);
//terminate server thread, as this is just a test

what i was expecting was the server thread to block at listen(), and then continue after the client tried to connect. The client, ofcourse, timed out. however, i then tried running two clients, and both of them found the server (im not sure if they both got "accepted") and then timed out.

So what does listen() actually. Im really confused, as i was intending to make a loop using listen to block until a client tried to connect and then launch a thread. But it would appear as though listen did more than just block. Could someone please explain whats going on there. Thanks.

**CornedBee** · 12-10-2007, 03:26 AM

listen() puts the socket in listening mode. It doesn't wait for an actual connection, though. That's accept()'s job.

**Salem** · 12-10-2007, 03:33 AM

listen() goes in the main thread, then you pass the accept()'ed socket into a new thread to deal with that connection. The main thread loops round for another listen.

*DEAD* · 12-10-2007, 04:03 AM

ok, so accept() will block and should be in the loop, and theres some sort of magical queue created in the background. I hate magic, so confusing.

Thx, im pretty sure i can work from there.

**Bubba** · 12-13-2007, 10:17 PM

There's no queue. Accept will block if the socket is blocking and won't if it's not. Where is this queue you are speaking of?

**CornedBee** · 12-14-2007, 06:35 AM

This queue is internal to the network driver and holds client connections until accept fetches them.

**Bubba** · 12-14-2007, 06:48 PM

Ok there's no queue from a software standpoint.

12-10-2007, 03:05 AM	#1
DEAD Registered User Join Date: Jul 2006 Posts: 63	What exactly does listen() do from winsock 1.1 Hi, im designing a login server for a game, and every time the server receives a connection i intend to a launch a new thread. I was playing with the code from another server i made which was only capable of connecting to one client, and basically it does this. Code: //define the listening socket above listen(listenSock, 10) //define a server socket serverSock = accept(listenSock, NULL, NULL); //terminate server thread, as this is just a test what i was expecting was the server thread to block at listen(), and then continue after the client tried to connect. The client, ofcourse, timed out. however, i then tried running two clients, and both of them found the server (im not sure if they both got "accepted") and then timed out. So what does listen() actually. Im really confused, as i was intending to make a loop using listen to block until a client tried to connect and then launch a thread. But it would appear as though listen did more than just block. Could someone please explain whats going on there. Thanks.
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12-10-2007, 03:26 AM	#2
CornedBee Cat without Hat Join Date: Apr 2003 Posts: 8,439	listen() puts the socket in listening mode. It doesn't wait for an actual connection, though. That's accept()'s job. __________________ All the buzzt! CornedBee "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code." - Flon's Law
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12-10-2007, 03:33 AM	#3
Salem and the hat of vanishing Join Date: Aug 2001 Location: The edge of the known universe Posts: 21,214	listen() goes in the main thread, then you pass the accept()'ed socket into a new thread to deal with that connection. The main thread loops round for another listen. __________________ If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut. Up to 8Mb PlusNet broadband from only £5.99 a month!
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12-10-2007, 04:03 AM	#4
DEAD Registered User Join Date: Jul 2006 Posts: 63	ok, so accept() will block and should be in the loop, and theres some sort of magical queue created in the background. I hate magic, so confusing. Thx, im pretty sure i can work from there.
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12-13-2007, 10:17 PM	#5
Bubba Super Moderator Join Date: Aug 2001 Posts: 7,472	There's no queue. Accept will block if the socket is blocking and won't if it's not. Where is this queue you are speaking of?
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12-14-2007, 06:35 AM	#6
CornedBee Cat without Hat Join Date: Apr 2003 Posts: 8,439	This queue is internal to the network driver and holds client connections until accept fetches them. __________________ All the buzzt! CornedBee "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code." - Flon's Law
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12-14-2007, 06:48 PM	#7
Bubba Super Moderator Join Date: Aug 2001 Posts: 7,472	Ok there's no queue from a software standpoint.
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