C / C++ / MFC

Dee Veloper26-Jan-07 7:09

Dee Veloper

26-Jan-07 7:09

maxRead is the maximum number of bytes the buffer can store. if recvMsgSize is smaller than maxRead (which is normally the case) I copy the data to additional buffers and combine them as soon as all bytes are received. With my problem the data received is always smaller than maxRead.

Mark Salsbery26-Jan-07 7:21

26-Jan-07 7:21

hmmm From what I've seen there shouldn't be a problem.

You've debugged the code? Examining network packets isn't necessarily the way to debug since the
potocol is free to re-packetize your data as needed.

Have you changed any socket options on either end?

There's a bug in the code somewhere Smile | :)

Mark

Dee Veloper26-Jan-07 7:39

Dee Veloper

26-Jan-07 7:39

I guess I have to think through my code step by step once again. At least I know now, that send() should send after 200ms as long as the connection is established.

Thanks again for your help!

Flo

Mark Salsbery26-Jan-07 7:50

26-Jan-07 7:50

If you'd like to post the send-side code I'd be happy to look at it as well.

Mark

Mike O'Neill26-Jan-07 10:33

Mike O'Neill

26-Jan-07 10:33

I generally agree with Mark's observation that problems like this are almost always caused by code on the receiving side.

Here, you have set the timeout for select() to 5 microseconds. That's way too short.

Your understanding of the send() function is slightly wrong. send() does not actually send bytes out over the wire; that happens later when the winsock TCP stack determines that it's time to send data on the wire, after considertion of things like Nagle, delayed ACK etc. Rather, a successful call to send() only indicates that the winsock stack has successfully transferred data in your user buffer to its internal winsock buffer. The return value from send() tells you exactly how much of your buffer has been accepted; you should therefore inspect the returned value to ensure that winsock transferred everything to its internal buffer.

So, if you are debugging and single-stepping through your code, and you see a successful completion of the call to send(), then it's probably still too early for a sniffer to see the actual data on the wire. That will happen, but it will happen at some indeterminate time in the future.

Mike

Mark Salsbery26-Jan-07 10:42

26-Jan-07 10:42

Thanks Mike!

Maybe you meant to post this to the OP Smile | :)

For some reason I assumed his code was in a loop. If it's not then that 5microsecond timeout is definitely not going to work (well, rarely).

Mark

Mark Salsbery26-Jan-07 10:47

Re: Tcp/Ip send() does sometimes not succeed [modified]

26-Jan-07 10:47

Hi Flo,

Check out Mike O'Neill's reply above.

I asked previously how you're handling it when you don't receive the number of bytes requested.
Are you looping until you get the bytes you're expecting or just trying to recv once after the
5microsecond wait?

Mark

Eytukan26-Jan-07 7:11

Eytukan

26-Jan-07 7:11

If I remember it correctly, If the packet size become too small, very small that it doesnt send it until the successive packets join together to make good "chunk". It's somewhat termed as ~~"Neigile's"~~ Nagle algorithm or so. just check the size of the packets your are sending.

-- modified at 13:16 Friday 26th January, 2007

Code-Frog:So if this is Pumpkinhead. Time for him to run and hide. It's an interesting thought really.

Mark Salsbery26-Jan-07 7:15

26-Jan-07 7:15

Nagle

The data is sent after (by default on Windows Sockets) 200ms though.

Mark

Eytukan26-Jan-07 7:18

Eytukan

26-Jan-07 7:18

Done. Thanks Big Grin | :-D

Code-Frog:So if this is Pumpkinhead. Time for him to run and hide. It's an interesting thought really.

File format [modified]

dellthinker26-Jan-07 5:43

dellthinker

26-Jan-07 5:43

Hi all. Im having trouble making this file read-out look nice.

The code is this:

<br />
#include <fstream><br />
using namespace std;<br />
<br />
int main(){<br />
	char buffer[100];<br />
	ifstream file("file.dat",ios::end);<br />
	if(file.fail()){<br />
	printf("File not found.\n");<br />
	}<br />
	printf("File contents read the following:\n");<br />
	while(file >> buffer){<br />
	printf("\n%s ",buffer);<br />
	}<br />
	file.close();<br />
	system("pause");<br />
	return 0;<br />
}<br />

The file "file.dat" reads "This is only a test" inside. But when i run the program it reads:
File contents read the following:

This
is
only
a
test
-----------------------

So i figured maybe it was a problem with my way of printing the message in the console. So i switched the printf around from this

<br />
printf("\n%s ",buffer);<br />

To this

<br />
printf("%s\n ",buffer);<br />

To this

<br />
printf("%s",buffer); // This putsallthewordstogetherlikeso<br />

And still cant come up with a better looking format. Is there another way i can make it print the way its saved in the file? Thanx in advance!

P.S.

If i made the print like this: printf("%s ",buffer); It would print the first line in the file as its written in the file. But if there were two lines or three etc. It prints it like this

"This is only a test This is only a test This is only a test"

Which isnt what im looking to do. I'd like it look something like

This is only a test
This is only a test
This is only a test

Reagan Conservative26-Jan-07 6:02

Reagan Conservative

26-Jan-07 6:02

I think you may find this link very useful
www.dorota.ecs.fullerton.edu/classes/CS231/lect3-cs.ppt

or Google on "ios:end"

John P.

David Crow26-Jan-07 6:13

26-Jan-07 6:13

jparken wrote:
www.dorota.ecs.fullerton.edu/classes/CS231/lect3-cs.ppt

Is http://www.dorota.ecs.fullerton.edu/ a valid domain?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

David Crow26-Jan-07 6:15

26-Jan-07 6:15

dellthinker wrote:
Is there another way i can make it print the way its saved in the file?

Yes. Either read and print it on a line-by-line basis, or read each word into an array and print the contents of the array as you see fit.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Michał Zalewski26-Jan-07 9:49

Michał Zalewski

26-Jan-07 9:49

Operator >> used with (i/o)fstream read one word from actual position in file to first space or end line. If you want read line you must use getline.
You can read about it there: http://www.cplusplus.com/istream::getline Smile | :)

-----------------------------------------------------------------
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Hence no mourning, no grief, no pain, no misery
No sleepless nights missing the dead... Oh, no more
No more war

[Sleepless - Cradle of Filth]

Select User dialog

Ami Bar26-Jan-07 5:04

26-Jan-07 5:04

I am looking for the Windows API that opens the Select User dialog.
Can anyone give a reference or an example on how to do this ?

Thanks,
Ami

David Crow26-Jan-07 6:10

26-Jan-07 6:10

Ami Bar wrote:
...the Select User dialog.

Where's this?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Ami Bar26-Jan-07 9:01

26-Jan-07 9:01

When you change a security permission for file, registry key, etc. You can choose a user/group to add to the DACL by a Select user dialog.
I am looking for a Windows API that open this dialog.

Ami

David Crow26-Jan-07 9:14

26-Jan-07 9:14

Ami Bar wrote:
I am looking for a Windows API that open this dialog.

I don't know of an API to do this, but you could always populate your own list.

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Ami Bar26-Jan-07 9:19

26-Jan-07 9:19

It has to be a Windows common dialog or something.

Ami

Mark Salsbery26-Jan-07 9:47

26-Jan-07 9:47

It has to be? Smile | :)

Then it will be documented here: Common Dialog Box Library[^]

If you don't find a common dialog you can maybe use NetQueryDisplayInformation to help populate
your own.

Mark

Ami Bar26-Jan-07 9:52

26-Jan-07 9:52

Thanks, but I already found this API and if I won't have a choice I will use it.
I thought that if the API CredUIPromptForCredentials asks for a user name and password, there must be a similar API that does what I need.

Ami

David Crow26-Jan-07 10:28

26-Jan-07 10:28

Ami Bar wrote:
...or something.

Which covers everything else, right? Are you simply wanting a list of domain users?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Ami Bar26-Jan-07 10:36