[twsocket] TWSocket.Close() blocks on certain machines after sending UDP
Hi all,
I've been using ICS for a long time, in different environments and on
different machines without problems.
Now I've stumbled upon a problem of which at the moment I don't know how
to find a solution for. It's regarding a snippet which sens data using UDP.
The relevant code boils down to:
with TWSocket.Create(nil) do
begin
Proto := 'udp';
Port := some port;
Addr := some ip;
Connect();
SendStr('some data');
Close();
Free();
end;
Very simple, and works great.
Now on two machines we have an issue while using this code. The call to
Close() will block for 4 to 6 seconds if:
- I'm sending to an IP address within my own subnet
- There is no actual PC at that IP (doesn't have to be running a UDP
server, just a PC with that ip address).
I've tried with different NIC's, and now I have a NIC on USB, which
gives this problem on the 2 machines mentioned before (Win 7 Pro SP1),
but do not have the same issue on another machine (Win 7 Pro SP1).
Obviously there is something with these two machines, but I'd like to
know what is causing this to give me some control over it. These are
brand new machines, firewall is disabled and all pre installed software
is removed. I also have a support call at the manufacturer, but since
there is not much promising result from them I'm hoping anyone here can
give me a pointer in the right direction.
Thanks and regards!
Merijn
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Re: [twsocket] Hang in TIcsWndControl.ProcessMessages
Does anyone have ideas why TIcsWndControl.ProcessMessages could
hang sometimes when socket is used in separate thread?
Have you followed the rules: create TWSocket within the thread's execute
method OR call ThreadAttach ?
Yes socket is created within threads execute method, and it works most of
the time.
I call it after calling shutdown like this, could it be related?
FSocket.Shutdown(SD_BOTH);
What do you mean by I call it after... ?
Actually ProcessMessages probably doesn't hang. ProcessMessages it the place
from where all events are called. It is likely an event handler which is
blocking. You should try to find out where.
I call it like this, the only event that is called is SslShutDownComplete which
sets FSSLShutdownComplete property, I don't have any other event processing here
FSocket.Shutdown(SD_BOTH);
EndTime := GetTickCount + FTimeout;
while {$IFDEF USE_SSL} not FSSLShutdownComplete {$ELSE} False {$ENDIF} do
begin
if GetTickCount EndTime then
break;
Sleep(10);
FSocket.ProcessMessages;
end;
I am now trying to use only main thread with socket, but there is another
problem when I use it directly from main thread it works fine, but when I call
it using Synchronize from another thread after first portion of data is sent
socket closes with 10053 error. Any ideas what could be the problem? It is an
SSL connection.
And how to recover from 10053 error? When I call Socket.Connect again it still
remains closed.
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Re: [twsocket] TWSocket.Close() blocks on certain machines aftersending UDP
Merijn Bosma wrote:
Hi all,
I've been using ICS for a long time, in different environments and on
different machines without problems.
Now I've stumbled upon a problem of which at the moment I don't know
how to find a solution for. It's regarding a snippet which sens data
using UDP. The relevant code boils down to:
with TWSocket.Create(nil) do
begin
Proto := 'udp';
Port := some port;
Addr := some ip;
Connect();
SendStr('some data');
Close();
Free();
end;
Very simple, and works great.
Now on two machines we have an issue while using this code. The call
to Close() will block for 4 to 6 seconds if:
- I'm sending to an IP address within my own subnet
- There is no actual PC at that IP (doesn't have to be running a UDP
server, just a PC with that ip address).
That sounds very similar to an issue Francois reported several months
back and which turned out to be a winsock bug IMO.
In Vista+ winsock repeated the ARP request within a few seconds 2 times
to get the MAC address that accepts packets for the destination if the
request failed because the destination did not exist.
In Win XP there's only one ARP request sent.
The call to WSocket_Synchronized_closesocket(FHSocket) which calls
the native winsock API function doesn't return while winsock is still
trying to get the MAC address of a non-existing host.
--
Arno Garrels
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Re: [twsocket] TWSocket.Close() blocks on certain machines aftersending UDP
I suggest you look at security software which may be installed on those
PC. Some of those software (anti-malware, firewall, proxy,...) are
malfunctionning in their interception of socket communication. So first do a
test with every security software disabled.
It may also be a virus or trojan which intercept socket communication for
malware. So here turn all security on, do an complete malware check (update
your software !). Also try to detect root kits which may be there.
--
francois.pie...@overbyte.be
The author of the freeware multi-tier middleware MidWare
The author of the freeware Internet Component Suite (ICS)
http://www.overbyte.be
- Original Message -
From: Merijn Bosma bo...@xs4all.nl
To: twsocket@elists.org
Sent: Tuesday, July 12, 2011 1:49 PM
Subject: [twsocket] TWSocket.Close() blocks on certain machines aftersending
UDP
Hi all,
I've been using ICS for a long time, in different environments and on
different machines without problems.
Now I've stumbled upon a problem of which at the moment I don't know how
to find a solution for. It's regarding a snippet which sens data using
UDP.
The relevant code boils down to:
with TWSocket.Create(nil) do
begin
Proto := 'udp';
Port := some port;
Addr := some ip;
Connect();
SendStr('some data');
Close();
Free();
end;
Very simple, and works great.
Now on two machines we have an issue while using this code. The call to
Close() will block for 4 to 6 seconds if:
- I'm sending to an IP address within my own subnet
- There is no actual PC at that IP (doesn't have to be running a UDP
server, just a PC with that ip address).
I've tried with different NIC's, and now I have a NIC on USB, which gives
this problem on the 2 machines mentioned before (Win 7 Pro SP1), but do
not have the same issue on another machine (Win 7 Pro SP1).
Obviously there is something with these two machines, but I'd like to know
what is causing this to give me some control over it. These are brand new
machines, firewall is disabled and all pre installed software is removed.
I also have a support call at the manufacturer, but since there is not
much promising result from them I'm hoping anyone here can give me a
pointer in the right direction.
Thanks and regards!
Merijn
--
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Re: [twsocket] Hang in TIcsWndControl.ProcessMessages
Does anyone have ideas why TIcsWndControl.ProcessMessages could
hang sometimes when socket is used in separate thread?
Actually ProcessMessages probably doesn't hang. ProcessMessages it the
place
from where all events are called. It is likely an event handler which is
blocking. You should try to find out where.
I call it like this, the only event that is called is SslShutDownComplete
which
sets FSSLShutdownComplete property, I don't have any other event
processing here
FSocket.Shutdown(SD_BOTH);
EndTime := GetTickCount + FTimeout;
while {$IFDEF USE_SSL} not FSSLShutdownComplete {$ELSE} False {$ENDIF} do
begin
if GetTickCount EndTime then
break;
Sleep(10);
FSocket.ProcessMessages;
end;
I don't know from where this code is called, but it CANNOT be called from an
event handler originating from TWSocket.
ProcessMessage is actually calling the window procedure for all windows
created in the thread context and in turn trigger events at the component
level. If any event hanlder is blocking, the ProcessMessages looks blocking.
Calling Synchronize will actually block the thread until the main thread has
time to process a message.
--
francois.pie...@overbyte.be
The author of the freeware multi-tier middleware MidWare
The author of the freeware Internet Component Suite (ICS)
http://www.overbyte.be
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Re: [twsocket] TWSocket.Close() blocks on certain machines aftersending UDP
New message while I was typing the reply to the previous one :)
Fraincois, I've been able to reproduce this on a fresh installed machine
(no internet connection). Windows firewall is disabled, no extra
software installed. I think that will rule out a external software issue?
Besides, we see exactly the same behavior on two independent machines.
Thanks for the info.
Merijn
On 7/12/2011 19:31, Francois PIETTE wrote:
I suggest you look at security software which may be installed on
those PC. Some of those software (anti-malware, firewall, proxy,...)
are malfunctionning in their interception of socket communication. So
first do a test with every security software disabled.
It may also be a virus or trojan which intercept socket communication
for malware. So here turn all security on, do an complete malware
check (update your software !). Also try to detect root kits which may
be there.
--
francois.pie...@overbyte.be
The author of the freeware multi-tier middleware MidWare
The author of the freeware Internet Component Suite (ICS)
http://www.overbyte.be
- Original Message - From: Merijn Bosma bo...@xs4all.nl
To: twsocket@elists.org
Sent: Tuesday, July 12, 2011 1:49 PM
Subject: [twsocket] TWSocket.Close() blocks on certain machines
aftersending UDP
Hi all,
I've been using ICS for a long time, in different environments and on
different machines without problems.
Now I've stumbled upon a problem of which at the moment I don't know
how to find a solution for. It's regarding a snippet which sens data
using UDP.
The relevant code boils down to:
with TWSocket.Create(nil) do
begin
Proto := 'udp';
Port := some port;
Addr := some ip;
Connect();
SendStr('some data');
Close();
Free();
end;
Very simple, and works great.
Now on two machines we have an issue while using this code. The call
to Close() will block for 4 to 6 seconds if:
- I'm sending to an IP address within my own subnet
- There is no actual PC at that IP (doesn't have to be running a UDP
server, just a PC with that ip address).
I've tried with different NIC's, and now I have a NIC on USB, which
gives this problem on the 2 machines mentioned before (Win 7 Pro
SP1), but do not have the same issue on another machine (Win 7 Pro SP1).
Obviously there is something with these two machines, but I'd like to
know what is causing this to give me some control over it. These are
brand new machines, firewall is disabled and all pre installed
software is removed. I also have a support call at the manufacturer,
but since there is not much promising result from them I'm hoping
anyone here can give me a pointer in the right direction.
Thanks and regards!
Merijn
--
To unsubscribe or change your settings for TWSocket mailing list
please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket
Visit our website at http://www.overbyte.be
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please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket
Visit our website at http://www.overbyte.be
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Re: [twsocket] TWSocket.Close() blocks on certainmachines aftersending UDP
AFAIR the workaround was to do your own ARP request first in order to check whether the destination exists or not, utilizing the IP Helper API. Yes, that what I did. How can I confirm that this is what's happening with me? In my case, the blocking was occuring in the main thread. TO see it it was then easy: using the mouse, I moved continuously the form in small circles. When blocked, the application don't paint the form and the window was stuck. Then using WireShark I was able to see that the blocking was when ARP requests were sent to non existant address. -- francois.pie...@overbyte.be The author of the freeware multi-tier middleware MidWare The author of the freeware Internet Component Suite (ICS) http://www.overbyte.be -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
