C / C++ / MFC

4-Nov-04 21:13

Hi out there,

I have a strange problem:

I coded a simple Client-Server chat app! It works wonders. The way it works:

The server is a multithreaded app. It waits for incoming connections and if found, start a new thread. There, in an endless loop, it waits for messages.
The Client: It connects to the server, sends its name, so that the server knows who is online. This name will be written down in a lookuptable together with the IP and the socket.
If someone writes a message, the message looks like this: "ToName0FromName: Message". So the server checks if ToName is online, through the lookuptable, and if he is, sending him the Message (after the 0).

Now my problem:

Both clients connect. One starts sending messages. The other one receives them. If the other one sends a message, the first client does receive it. But every following message wont reach the first client. No error messages, nothing. It seems the server doesnt get the message. But, Sending doesnt give any errors, and I checked, and the client is still connected to the server...
If I disconnect this client and connect again, the same thing happens, but the other way around. so the first client cant send, but not the second!

What can this be?
I read alot of papers, and tried alot, but I am still confused!
It would be so nice if you could help me!

DKT

vilmer5-Nov-04 2:25

vilmer

5-Nov-04 2:25

Hi,
I suggest you to try to debug your application with some watches on the receiveing buffer of the server sockets. What do you mean with "in an endless loop the server waits for messages"? Isn't the server app in idle state?
I was wondering if you used CAsyncSocket class...
D'Oh! | :doh:

Anonymous5-Nov-04 2:54

5-Nov-04 2:54

No I am not debugging, changing the active setting to debugging means, I wont be able to debug the app, cause MFC doesnt want to work with threads properly!

With endless loop I mean something like:

while(true)
{
recv(...)
if error break
if done break
else show message
}

No. I am not using this function. I am just listening on a specific port and waiting for incoming connections, if found, start a new thread for it where this loop comes!

DKT

thercio5-Nov-04 8:02

thercio

5-Nov-04 8:02

You may lost some data packets in the server side.

Try to use this thinking:

while(TRUE)
{
select(); // to get socket status
if (SOCKET_ERROR)
{
//deal with the error
//WSAGetLastError() must be called
}
if (TOUT)
{
continue;
}

recv();// after that, you are ready to read some data, because select() was signaled to do something.

}

Anonymous7-Nov-04 21:49

7-Nov-04 21:49

Ok, thats fine. I didnt know about select!

Now I get an error code 10022 which means:

"WSAEINVAL
(10022)
Invalid argument.
Some invalid argument was supplied (for example, specifying an invalid level to the setsockopt function). In some instances, it also refers to the current state of the socket—for instance, calling accept on a socket that is not listening."

Now my question. Where didnt I pass the right arguments? I dont use SetSockOpt. I called the select directly after accepting an incoming conncetion, so, before going into the thread! Accept doesnt give any errors. And I know it works, cause I can send msgs.

This is what my accept looks like, or better the whole code up to accept:

if(WSAStartup(MAKEWORD(1,1),&wsaData)!=0)
MessageBox(TEXT("Initialize"), TEXT("Error!"), MB_OK);
local.sin_addr.s_addr=INADDR_ANY;
local.sin_family=AF_INET;
local.sin_port=htons(20248);

if((server_s=socket(PF_INET, SOCK_STREAM, IPPROTO_TCP))==INVALID_SOCKET)
MessageBox(TEXT("SocketCreation"), TEXT("Error!"), MB_OK);

if(bind(server_s, (PSOCKADDR)&local, sizeof(local))==SOCKET_ERROR)
MessageBox(TEXT("Binding"), TEXT("Error!"), MB_OK);

if(listen(server_s, 10)!=0)
MessageBox(TEXT("Listening"), TEXT("Error!"), MB_OK);
else
{
m_con_s="- Connected -";
UpdateData(false);
connect_b=true;
}

while(true)
{
fromlen=sizeof(from);
if((client_s=accept(server_s, (struct sockaddr*)&from, &fromlen))==INVALID_SOCKET)
{
wsprintf (szError, TEXT("Accepting Connections. Error: %d"),
WSAGetLastError ());
MessageBox(szError, "Accepting Connections:", MB_OK);
break;
}
else
if(select(0,0,0,0,0)==SOCKET_ERROR)
{
wsprintf (szError, TEXT("Error: %d"),
WSAGetLastError ());
MessageBox(szError, "Status of Con.", MB_OK);
break;
}
}

Thanks so far!

DKT

Anonymous7-Nov-04 23:32

Are there any functions fast than sccanf, sprintf, strlen?

7-Nov-04 23:32

Two more questions:

1. How to use Select? I just set all arguments to NULL, is that correct to get the state of the socket?

2. Can the problem be because I am using just one port for everything, although I am using threads? I mean, every client is connecting on the same port, and get its messages on this port.

DKT

mirc chatlogger

stifmeister_ro4-Nov-04 20:52

stifmeister_ro

4-Nov-04 20:52

Does anyone know how can I code a program that logs the mIRC chat window ? Is it possible to code such a program?
I saw that the mIRC chat window class name is "Static" and I tried to get tha handle to the window and I sent a WM_GETTEXT message but it didn't work.

Please help me!!!

Cristian

freehawk4-Nov-04 20:40

freehawk

4-Nov-04 20:40

Hello everyone:

Are there any functions fast than sccanf, sprintf, strlen?
Thanks.

-Freehawk

Re: Are there any functions fast than sccanf, sprintf, strlen?

Henry miller5-Nov-04 2:14

Henry miller

5-Nov-04 2:14

Maybe.

Before you start though I have two questions:

Have you done a profile on your program and determined that you program is really spending a lot of time in those 3 functions. In most cases, despite those functions not being particularly good, they are good enough.

Why are you not using a C++ string class, and the functions they provide to do the same? There are a number of them out there.

Assuming you have good answers to those questions:
strlen is best made faster by making a string class (or structure if you must do pure C) that holds the length of the string. Keeping this up to date can greatly speed up your program if strlen is called often.

The other two are most easily taken care of by careful analysis of what you are doing with them. In most cases just knowing something about the data and how it is used can make solutions obvious. (for instance if you use sprintf to create a string, and sscanf to latter pull it apart, why create the string in the first place, just pass the data)

Not knowing your data I cannot say more. I still suspect that this question is not worth asking.

Explain The #line Directive with example in detail,

Member 5281554-Nov-04 20:04

Member 528155

4-Nov-04 20:04

Hi,
I was just debugging this c file when i encountered this statement
#line 24 "Flex.lex"
the control is transfered to line 25 of the Flex file

Can someone explain it in details also other directive which are frequently used .
Thanx..

lokiz

msvcrt version

shiraztk4-Nov-04 17:53

shiraztk

4-Nov-04 17:53

Hi
I have an application that is to run as a service. That it should run as soon as it is installed without restarting. But the problem is I have created the application as mfc shared. But in some system it doesnt work due to
The version of msvcrt in the system is outdated.

How can I overcome this. I am not able to replace the msvcrt file as the it is used by the current system.

Is there any other option than a static build ? Will static build cause problems. Should I repeat the whole testing process for static build also ?

Regards
zainu

The Best Relligion is Science.
Once you understand it, you will know God.

KaЯl4-Nov-04 23:04

KaЯl

4-Nov-04 23:04

You can try to place the version of the DLL you need in the same directory than your executable. When running it, it should load the one located in its directory before searching for one with the same name from the Path.

The other way is to replace msvcrt.dll by putting the version you want in some directory, setting then a copy command to System32 in the registry key "RunOnce" and reboot the system, but it may be potentially dangerous, it could break other applications who need the version you replace.

HTH,

K.

Fold With Us!
"Military intelligence is a contradiction in terms - Groucho Marx, 1890 - 1977"

shiraztk5-Nov-04 0:22

shiraztk

5-Nov-04 0:22

Hi
Thank you very much for your time and answer.

I have tried both of them.

1. It has the problem that the old version is already in memory, so my application will refer to the one in memory instead of loading the new one from the folder.

2. I want to accomplish it without a restart.

Thanks again
regards

shiraz

The Best Relligion is Science.
Once you understand it, you will know God.

vikramlinux5-Nov-04 0:45

vikramlinux

5-Nov-04 0:45

I think static linking with crt libary? But I dont know how to do it Smile | :)

vikramlinux5-Nov-04 0:52

vikramlinux

5-Nov-04 0:52

Well I got it
Change you project setting , and make MFC statically linked.

shiraztk5-Nov-04 1:39

shiraztk

5-Nov-04 1:39

Hi
Thanks vikram,

Yes I did that but the application crashes in NT 4.

Anyway I did a workaround and did some command line processing in the set up.

Regards
Shiraz

The Best Relligion is Science.
Once you understand it, you will know God.