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Connect a socket of TCP/IP on the same machine, R2009b and VC++2008 express SP1

I tried to connect a TCP/IP socket. Before connect remote machines, I want to test the communication on the same machine.
I tested the socket program with C++ already. And It works properly.
However, when I test same routines on the C-mex file, it downs Matlab.
I wrote down the socket program as like bellows.
--- Server side ---
// Global variables for TCP/IP
int srcSocket; // this program
int dstSocket; // remote program
// sockaddr_in structure
struct sockaddr_in srcAddr;
struct sockaddr_in dstAddr;
int dstAddrSize = sizeof(dstAddr);
int status;
int numrcv;
char buffer[1024];
#define MDL_START /* Change to #undef to remove function */
#if defined(MDL_START)
static void mdlStart(SimStruct *S) {
// Initialize socket
WSAStartup(MAKEWORD(2,0), &data);
memset(&srcAddr, 0, sizeof(srcAddr));
srcAddr.sin_port = htons(PORT);
srcAddr.sin_family = AF_INET;
srcAddr.sin_addr.s_addr = htonl(INADDR_ANY); // allow any address to receive data
// open socket, stream type
srcSocket = socket(AF_INET, SOCK_STREAM, 0);
// bind sockek
bind(srcSocket, (struct sockaddr *) &srcAddr, sizeof(srcAddr));
// allow connection
listen(srcSocket, 1);
// accept connection
dstSocket = accept(srcSocket, (struct sockaddr *) &dstAddr, &dstAddrSize);
} #endif /* MDL_START */
--- Client side ---
// Global variables for TCP/IP
char destination[] = "";
int dstSocket;
struct sockaddr_in dstAddr;
char buffer[1024];
#define MDL_START /* Change to #undef to remove function */
#if defined(MDL_START)
static void mdlStart(SimStruct *S) {
WSAStartup(MAKEWORD(2,0), &data);
// Set the structure of sockaddr_in
memset( &dstAddr, 0, sizeof(dstAddr));
dstAddr.sin_port = htons(PORT);
dstAddr.sin_family = AF_INET;
dstAddr.sin_addr.s_addr = inet_addr(destination);
// Create a socket
dstSocket = socket( AF_INET, SOCK_STREAM, 0);
if( connect(dstSocket, (struct sockaddr *) &dstAddr, sizeof(dstAddr)))
// Failed to connect
connectCheck = 3;
// Success with connection
connectCheck = 8;
#endif /* MDL_START */
I put the server block and the client block on the same model file. Is it the reason of freezing Matlab? I think this is not the good way to initialize the socket between two blocks.
If someone inform me any clue, it would be great help.


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1 Answer

Answer by Ankit Desai on 21 Jul 2011
 Accepted Answer

This blog post might be helpful in trying to establish a server/client connection using TCPIP.
Remember, once you open (using fopen) the server socket, it will wait indefinitely for a connection. MATLAB will wait until an incoming connection is established.
It is therefore best to keep server and client on separate machines.
Hope this helps

  1 Comment

Now, I separated the server with the different process of execution file, not Matlab.
And, it works without problem. I think I need more practice with the socket programming.
Thanks for your advice.

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