Question

I am trying to use the SmallSockets library to create a TCP socket connection. Currently, I’m using a button to simply test my connection to a server from my iPhone. Here is what my code looks like:

-(IBAction)btnConnect:(id)sender
{
    bool loopConnection = true;
    while(loopConnection == true)
    {
        Socket *socket;
        int port = 11005;
        NSString *host = @"199.5.83.63";

        socket = [Socket socket];

        @try
        {
            NSMutableData *data;
            [socket connectToHostName:host port:port];
            [socket readData:data];
            //  [socket writeString:@"Hello World!"];

            //** Connection was successful **//
            [socket retain]; // Must retain if want to use out of this action block.
        }
        @catch (NSException* exception) 
        {
            NSString *errMsg = [NSString stringWithFormat:@"%@",[exception reason]];
            NSLog(errMsg);
            socket = nil;
        }
    }
}

When I press the button, my app freezes. It freezes on the following function (which is part of the SmallSockets library):

- (int)readData:(NSMutableData*)data
//
// Append any available data from the socket to the supplied buffer.
// Returns number of bytes received.  (May be 0)
//
{
    ssize_t count;

    // data must not be null ptr

    if ( data == NULL )
    [NSException raise:SOCKET_EX_INVALID_BUFFER 
                    format:SOCKET_EX_INVALID_BUFFER];

    // Socket must be created and connected

    if ( socketfd == SOCKET_INVALID_DESCRIPTOR )
        [NSException raise:SOCKET_EX_BAD_SOCKET_DESCRIPTOR 
                    format:SOCKET_EX_BAD_SOCKET_DESCRIPTOR];

    if ( !connected )
        [NSException raise:SOCKET_EX_NOT_CONNECTED 
                    format:SOCKET_EX_NOT_CONNECTED];

    // Request a read of as much as we can.  Should return immediately if no data.

    count = recv(socketfd, readBuffer, readBufferSize, 0);

    if ( count > 0 )
    {
        // Got some data, append it to user's buffer

        [data appendBytes:readBuffer length:count];
    }
    else if ( count == 0 )
    {
        // Other side has disconnected, so close down our socket

        [self close];
    }
    else if ( count < 0 )
    {
        // recv() returned an error. 

        if ( errno == EAGAIN )
        {
            // No data available to read (and socket is non-blocking)
            count = 0;
        }
        else
            [NSException raise:SOCKET_EX_RECV_FAILED 
                        format:SOCKET_EX_RECV_FAILED_F, strerror(errno)];
    }

    return count;
}

The app freezes on the line: [data appendBytes:readBuffer length:count]; and then it says on the same line: Thread 1:EXC_BAD_ACCESS (code=1, address=0x5d18c48b). All I see in the output is (lldb) in green letters. As soon as a client connects, the server sends a 4 byte packet to the client.

If anyone could shed some light as to why my app is crashing here, I’d really appreciate it. I’ve been banging my head for a couple hours now trying to figure out what the issue is.

Thanks!

Answer 1

I don’t know if this is the right answer or not, but the first thing I would do is retain the socket right away. If you have a problem with the socket, then release it in the exception handler.