?
Solved

Winsock connect() timeout - how to set?

Posted on 1998-10-05
7
Medium Priority
?
1,242 Views
Last Modified: 2008-02-26
Does anyone know how to set the timeout when doing a Windows Socket connect()?

I can set the timeout on send() or recv() by calling select() first, but you need to be connected before select() works.

So how to set the timeout when trying to connect()?

Thanks,
NC
0
Comment
Question by:nchenkin
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
7 Comments
 
LVL 6

Expert Comment

by:snoegler
ID: 1253358
Just a thought:
Perhaps you could create a thread which calls connect(), and then timeout this thread:
(pseudocode):

int mythread()
{
  return connect();
}

myfunc()
{
.
  BeginThread(mythread);
  if(WaitForSingleObject(mythread, TIMEOUT)!=WAIT_OBJECT_0) {
    TerminateThread(mythread);
    // timeout ...
  } else
  {
    SOCKET sock=GetResultCode(mythread);
  }
}
0
 
LVL 3

Expert Comment

by:elfie
ID: 1253359
You can use the alarm call, combined with an interrupt handler.
0
 
LVL 4

Accepted Solution

by:
jos010697 earned 400 total points
ID: 1253360
The funny thing is that one can set read/write timeout values, but no connect
timeout values for a socket. There's a way out though:

-- set the socket to nonblocking:

   int noblock= 1;
   ioctl(socket, FIONBIO, &noblock);

- connect the socket:

   struct sockaddr_in sin;
   int retval= connect(socket,  &sin sizeof(sin));

- if the connect succeeds (immediately, that is), nothing needs to be done;
  otherwise, if connect returned -1 and errno is set to EINPROGRESS,
  the socket is still busy connecting. A select() call can be performed
  (check if it is ready for writing).

The select call _does_ have a user definable timeout value (it's the last parameter)
and voila, there you've got what you want.

kind regards,

Jos aka jos@and.nl

0
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 

Author Comment

by:nchenkin
ID: 1253361
snoegler and elfie,

Thanks for your comments. I had forgot to mention that I was using blocking sockets, but jos realized that. I think his answer is what I was looking for.

jos,

That looks like a good solution. I'll test it out today or tomorrow, but the points are yours for now!

Thanks,
Nelson


0
 

Author Comment

by:nchenkin
ID: 1253362
jos,

Actually, I have one more question if you don't mind. After doing the initial connect, then can you set the socket back in blocking? So the sequence is:

Set to non-blocking with ioctl()
Connect
Set to blocking with iotcl()
Select with timeout
Communicate with client or handle timeout error...

Does that look OK?

Thanks,
NC
0
 
LVL 4

Expert Comment

by:jos010697
ID: 1253363
No, set the socket back to blocking mode _after_ the select has returned
succesfully (you're sure the connect has completed then). I really don't
have any idea what would happen if you'd do it the way you described ...

kind regards,

Jos aka jos@and.nl
0
 

Author Comment

by:nchenkin
ID: 1253364
jos,

Thanks for your now ancient response. The day it arrived I was on a plane heading off for 5 weeks of trekking in the Himalayas. Just back in the office today and wanted to acknowledge your resonse.

Actually, I think I implemented it the way I mentioned above and it <seems> to be working, but will probably change to your suggestion.

NC
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This tutorial is posted by Aaron Wojnowski, administrator at SDKExpert.net.  To view more iPhone tutorials, visit www.sdkexpert.net. This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
Windows programmers of the C/C++ variety, how many of you realise that since Window 9x Microsoft has been lying to you about what constitutes Unicode (http://en.wikipedia.org/wiki/Unicode)? They will have you believe that Unicode requires you to use…
The goal of this video is to provide viewers with basic examples to understand recursion in the C programming language.
The goal of this video is to provide viewers with basic examples to understand and use conditional statements in the C programming language.
Suggested Courses

764 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question