RE: ioctl always returns 0
RE: ioctl always returns 0
- Subject: RE: ioctl always returns 0
- From: "Mahesh Vyas" <email@hidden>
- Date: Thu, 14 Apr 2005 16:13:42 +0530
- Thread-topic: ioctl always returns 0
We tried following but it failed
int val1 = 1;
setsockopt(socket,SOL_SOCKET,SO_KEEPALIVE,(char*)&val1,sizeof(val1));
Infact we also tried getting the SO_KEEPALIVE value using getsockopt
before and after doing setsockopt
In both the case it is coming out to be 8.
Are we missing something ?
-----Original Message-----
From: Vincent Lubet [mailto:email@hidden]
Sent: Wednesday, April 13, 2005 3:00 AM
To: Mahesh Vyas
Cc: email@hidden; Abhishek Jain
Subject: Re: ioctl always returns 0
This is normal, the TCP protocol has been designed to survive very long
loss of connectivity so there is no idle timer by default.
You should set the socket option SO_KEEPALIVE to force the networking
stack to check the peer is responding -- see man page setsockopt(2).
In addition you may want to use the TCP option TCP_KEEPALIVE to specify
the idle time used when SO_KEEPALIVE is enabled.
Vincent
On Apr 12, 2005, at 6:44 AM, Mahesh Vyas wrote:
> Hi
>
> The code below works fine if the client crashes. However, if there is
> a power failure or a shut down of the client machine, the code doesn't
> yield the desired result and the server machine is not able to detect
> the client disconnect.
> Could you suggest something for this?
>
> Rgds
> Abhishek
>
>
> -----Original Message-----
> From: Vincent Lubet [mailto:email@hidden]
> Sent: Thursday, March 04, 2004 8:57 PM
> To: Mahesh Vyas
> Cc: email@hidden
> Subject: Re: ioctl always returns 0
>
>
>
> On Mar 3, 2004, at 10:59 PM, Mahesh Vyas wrote:
>
>
>> ioctl(mSocket,FIONREAD,&lDgramSize) always returns 0 irrespective of
>> socket is closed or open.
>> Our aim is , when client quits server should find out with above API
>> whethe client still running or not.
>>
>
> This is not the correct way to find out the peer is disconnected.
>
> Rather you should use recv() with the MSG_PEEK flags:
>
> n = recv(mSocket, &buffer, 1, MSG_PEEK);
> if (n == -1)
> if (errno == EWOULDBLOCK)
> no data
> else
> other error handling
> else if (n == 1)
> data is available
> else if (n == 0)
> peer is disconnected
>
> Vincent
>
>
>
>
>
>
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