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C/C++ socket recv() problem.

I have a small C++ server and a java client. I send data from the client to the server. The recv() function of the server side does not receive the the data. I receive the size -1. But the otherway about works well (i.e. from server to the client). Here is my scaled down code.

Server.....
Sever users the following read() to read data from the socket...
void read (   )  
    {
        char buffer [ 100 ];
        memset ( buffer, 0, 100 );

        int receiveSize = ::recv ( mSocket, buffer, 100, 0 );

        std::cout << "Received Size : " << receiveSize << std::endl;
}

//The recvSize is -1 above.

Client ......
My Client uses the following simple java function to write the data to the socket:
public void writeValue(Socket requestSocket)
 {
        try{
               DataOutputStream dOut = new DataOutputStream(requestSocket.getOutputStream());
 
              System.out.println("writing a char...");
              dOut.writeChar('p');

              dOut.close();
        }
        catch  (Exception exp)
        {
            exp.printStackTrace();
        }
    }


Again:
1. Connection is perfer
2. Data sending from server to client is perfect
2. Problem is server receiving data from the client.

Can someone throw some light? BTW I work in a UNIX environment.
0
prain
Asked:
prain
2 Solutions
 
jkrCommented:
'-1' indicates an error condition (see http://linux.die.net/man/2/recv) - what is 'errno' in that case, i.e.

#include <errno.h>

void read (   )  
    {
        char buffer [ 100 ];
        memset ( buffer, 0, 100 );

        int receiveSize = ::recv ( mSocket, buffer, 100, 0 );

        std::cout << "Received Size : " << receiveSize << std::endl;

        if (-1 == receiveSize) std::cout << "Error: " << errno << std::endl;
}

Open in new window

0
 
satsumoSoftware DeveloperCommented:
Following on from jkr, the problem is likely to be somewhere else in the code.  The socket setup, connecting, binding and listening process.  Can you post some more code?
0
 
sarabandeCommented:
you know that the server needs a second socket for each client accepted?

means the server would call accept to get a new socket handle and then would use that socket handle for doing communication with the client. you often would do that in a separate thread per client cause otherwise the server was blocked when calling recv. you could set the socket to non-blocking but then the -1 return was ok if errno is EWOULDBLOCK. or you need to do a select with timeout for the client socket and only call recv if select returns 1.

Sara
0
 
prainAuthor Commented:
Actually I found the problem. I was setting nonBlocking as TRUE. But then I wrote a small C++ server. That threw me into a dilema because the C++ server reads the data from the client even if the nonBlocking is TRUE or FALSE. I cannot figure out why the data is not read (and returns -1)only when a Java Server is running.
0
 
sarabandeCommented:
is there anything open where we could help?

Sara
0

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