You need to reset 'TV' and the FD structures every time around the loop.
Winsock - Select's timeout on Listening socket causing every subsequent Select call to fail
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10-10-2022 - |
質問
I would like to preface this by saying my problem is solved completely by removing the timeout option of Select() by setting it to NULL.
But i want to use a timeout, so here is my problem. The server program is very simply&plain, it listens for connections, accepts them and prints to the console.
The problem is that after the first timeout on select, select will return -1 (MSDN gives me little-to-no documentation as to what would cause -1 to be returned from select(), only that it an error signal) and effectively stop any more communication from the program.
Server - main.cpp
int main(){
/* variables */
int iResult, iSendResult;
char recvbuf[DEFAULT_BUFLEN];
int recvbuflen = DEFAULT_BUFLEN;
bool exit=false;
int foundRoom, tempFoundRoom;
fd_set readfds, writefds;
struct timeval tv;
long double counter=0;
int maxfd=0;
/* Server variables */
WSADATA wsaData;
SOCKET ListenSocket = INVALID_SOCKET;
SOCKET ClientSocket = INVALID_SOCKET;
struct addrinfo *result = NULL;
struct addrinfo hints;
printf("~SERVER~\n");
/* Initialize Winsock*/
initialize_winsock(wsaData, hints, &result);
/* Set socket and bind to TCP listening socket */
set_socketandbind(ListenSocket, result, maxfd);
//non-blocking mode
u_long iMode=1;
ioctlsocket(ListenSocket,FIONBIO,&iMode);
ioctlsocket(ClientSocket,FIONBIO,&iMode);
// clear the set ahead of time
FD_ZERO(&readfds);
//FD_ZERO(&writefds);
//add our descriptors to the set
FD_SET(ListenSocket, &readfds);
//wait until either socket has data ready to be recv()d (timeout 5 secs)
tv.tv_sec = 5;
tv.tv_usec = 0;
/* main loop */
for(;;){
cout << "Maxfd: " << ListenSocket << " \ " << maxfd << endl;
//select
int rv = select(ListenSocket+1, &readfds, NULL, NULL, &tv);
cout << "Updateing... rv: " << rv << endl;
if (rv == -1) {
perror("Select: "); // error occurred in select()
}else if (rv == 0){
printf("Timeout occurred! No data after 5 seconds.\n");
}else{
// one or both of the descriptors have data
if (FD_ISSET(ListenSocket, &readfds)) {
// Accept a client socket
ClientSocket=accept(ListenSocket, NULL, NULL);
cout << "Connected a user." << endl;
}
counter++;
}
cout << endl;
Sleep(500);
};
/* Unset server socket */
closesocket(ListenSocket);
system("pause");
return 0;
}
The output should be, timeout, timeout, timeout, because thats how select() is supposed to work, and how it works on my client. Instead the output is timeout, error, error, error:
解決