I am trying to run a simple program to read ethernet using UDP. Here is the code, but it always receives -1 for 'error', but I did it by the book. Do you guys see the problem? Thanks.
//enum specifying the current status of the comm port.
enum e_PortStatus
{
PORT_BUSY, //port is currently in use
PORT_READY, //port is setup and ready for communication
PORT_ERROR //an error has occured somewhere
};
e_PortStatus myPortStatus;
//methods
void InitializeDevice(); //method which sets up this class, called at startup
void SetupPort(); //method which readies the port for communications
void SendCommandToDevice(); //method which passes in parameters defining a message to be sent to the device on the port
static struct sockaddr_in mySocketAddress; //used to keep track of the connector's address
static struct sockaddr_in theirSocketAddress; //used to keep track of the connector's address
static int socket_fd; //Socket File Descriptor
void StartDevice(); //Initializes the WINSOCK API
void CloseDevice(); //Close the WINSOCK API
void InitializeDevice()
{
SetupPort();
}
void SetupPort()
{
int yes = 1;
StartDevice();
if (myPortStatus != PORT_READY)
CloseDevice();
// create a UDP-based socket
socket_fd = socket(PF_INET, SOCK_DGRAM, 0);
if (socket_fd == -1)
{
myPortStatus = PORT_ERROR;
cout << "CANNOT CREATE SOCKET" << endl;
CloseDevice();
}
if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, (char* )&yes, sizeof(int)) == -1)
{
cout << "setsockopt" << endl;
CloseDevice();
}
// set up the local address
mySocketAddress.sin_family = AF_INET;
mySocketAddress.sin_port = htons(2010); //My_Port_Number
mySocketAddress.sin_addr.s_addr = htonl(INADDR_ANY); //automatically fills in the IP address of the machine the process is running on
// bind in socket to local address (sockaddr)
if (bind(socket_fd, (sockaddr *) &mySocketAddress, sizeof (mySocketAddress)) == -1)
{
myPortStatus = PORT_ERROR;
cout << "CANNOT BIND SOCKET" << endl;
int error = WSAGetLastError();
CloseDevice();
}
}
char* ReceiveCommandFromDevice()
{
char* messageBuf = NULL;
int size_received;
int dwtheirSocketAddressSize;
/*Start of broadcast
//Only use if you want to broadcast to every address on the network
//So change theirSocketAddress.sin_addr.s_addr to INADDR_BROADCAST and uncomment
if (setsockopt(socket_fd, SOL_SOCKET, SO_BROADCAST, (char* )&broadcast, sizeof(broadcast)) == -1)
{
myPortStatus = PORT_ERROR;
perror("setsockopt (SO_BROADCAST)");
CloseDevice();
}
//end of broadcast
*/
//make sure Port is set to Ready Mode
if ( myPortStatus == PORT_READY)
{
myPortStatus = PORT_BUSY;
size_received = recvfrom(socket_fd, messageBuf, sizeof(messageBuf), MSG_WAITALL, (SOCKADDR*) &theirSocketAddress, &dwtheirSocketAddressSize);
//check for error
if (size_received == -1)
{
myPortStatus = PORT_ERROR;
//cout << "CANNOT RECEIVE FROM PORT" << endl;
CloseDevice();
messageBuf = 'FAILURE';
}
else
myPortStatus = PORT_READY;
}
return messageBuf;
}
void CloseDevice()
{
closesocket(socket_fd);
WSACleanup();
}
void StartDevice()
{
WSADATA wsaData;
int iResult;
iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
if (iResult != 0)
{
myPortStatus = PORT_ERROR;
cout << "WSAStartup failed" << endl;
CloseDevice();
}
else
myPortStatus = PORT_READY;
}
int _tmain(int argc, _TCHAR* argv[])
{
InitializeDevice();
char* message;
while(1)
{
message = ReceiveCommandFromDevice();
cout << "Received: " << message << endl << endl;
Sleep(2000);
}
return 0;
}
