multiple concurrent socket connections

i've found quite a bit of articles on sockets, particularly on msdn, but one thing i haven't been able to ascertain, is how multiple concurrent connections are implemented on the server.

i've set up my own one-to-one client/server socket implementation and it works. however, if i close the client application, restart it and attempt to connect, the accept function fails with a WSAEINVAL error. According to msdn, WSAEINVAL - means the listen function was not invoked prior to accept.

this is not true though - the listen function was invoked prior to accept, which is how the first connection attempt was successfull.

any high-level thoughts as to why i might be having this problem? if needs be, i'll post some code, but i don't think it's much different that any other socket code out there..

Actually, it'd be good if you could show us the server and client code.

alright, i stripped this down to the bare essentials, to make getting this up and running as easy as possible if you want to try it out:

Code:

---

SOCKET socketx;
#define WM_SOCKET WM_USER+10
long CALLBACK WndProc(HWND hwnd,UINT msg,WPARAM wParam,LPARAM lParam){
        switch(msg){       
                case WM_CREATE:{                               
                                SetWindowPos(hwnd,HWND_TOPMOST,0,0,0,0,SWP_NOMOVE | SWP_NOSIZE);

                                WSADATA wsaData;       
                                WSAStartup(MAKEWORD(1,1), &wsaData);

                                socketx = socket(AF_INET,SOCK_STREAM,0);                               
                                WSAAsyncSelect(socketx,hwnd,WM_SOCKET,FD_CONNECT|FD_READ|FD_CLOSE|FD_ACCEPT);

                                unsigned short port = 7;
                                struct sockaddr_in addy;
                                  addy.sin_family = AF_INET;
                                addy.sin_port = htons(port);
                                addy.sin_addr.s_addr = INADDR_ANY;
                                  bind(socketx,(struct sockaddr*)&addy,sizeof(addy));
                                listen(socketx,SOMAXCONN);                               
                        }
                        break;               
                case WM_SOCKET:{
                        switch(LOWORD(lParam)){
                                case FD_ACCEPT:  {
                                        struct sockaddr cli_addr;
                                        int clilen = sizeof(cli_addr);
                                        socketx = accept(socketx,(struct sockaddr*)&cli_addr,&clilen);
                                        if(socketx==INVALID_SOCKET){
                                                MessageBox(NULL,"Invalid Socket","",MB_OK);
                                        }
                                }
                                break;
                                case FD_READ:{                                       
                                        char data[1024];
                                        recv(socketx,data,1024,0);

                                        send(socketx,"server: hello",strlen("server: hello"),0);
                                }
                                break;
                        }
                        }
                        break;
                case WM_DESTROY:
                        PostQuitMessage(0);
                        break;       
                default:
                        return DefWindowProc(hwnd,msg,wParam,lParam);
        }
}

---

obviously, this is a win32 app and i'm using the wMsg param in WSAAsyncSelect to pump socket message through my callback proc.

to repro the error, connect to this app, note the "server: hello" response, close the client app, then restart it and accept will fail as mentioned in my previous post.