Always receiving WSAEWOULDBLOCK error
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I am trying to receive udp packets which contains video data. I am receiving WSAEWOULDBLOCK error always.Can any one help me The code is WSADATA wsaData; int error = WSAStartup(0x202,&wsaData); if(error) return FALSE; if(wsaData.wVersion != 0x202) { WSACleanup(); return FALSE; } m_UdpSock=(SOCKET)WSASocket(AF_INET,SOCK_DGRAM,0,NULL,NULL,0); if(m_UdpSock==INVALID_SOCKET) return FALSE; sockaddr_in sockAddrServer; sockAddrServer.sin_family=AF_INET; sockAddrServer.sin_port=htons(port_data); sockAddrServer.sin_addr.s_addr=INADDR_ANY; // Bind socket to listener address if(bind(m_UdpSock,(SOCKADDR*)&sockAddrServer,sizeof(sockaddr_in))==SOCKET_ERROR) { int y=WSAGetLastError(); printf("Unable to bind socket\n"); return FALSE; } // Create WinSock Event object WSAEVENT eventWinsock=(WSAEVENT)WSACreateEvent(); if(eventWinsock==WSA_INVALID_EVENT) { printf("Unable to create winsock event\n"); return FALSE; } // Signal WinSock Event on receive packet if(WSAEventSelect(m_UdpSock,eventWinsock,FD_READ)!=NOERROR) { printf("Unable to connect event to socket\n"); return FALSE; } while(m_abort) { Recvbuf=new char[BUFFER_SIZE]; if(WaitForSingleObject(eventWinsock,INFINITE)== WAIT_OBJECT_0) { sockaddr_in sockAddrRecv; int nSockAddrSize=sizeof(sockaddr_in); // Packet received EnterCriticalSection(&m_cs); int nErr=recvfrom(m_UdpSock,Recvbuf,BUFFER_SIZE,0,(sockaddr*)&sockAddrRecv,&nSockAddrSize); LeaveCriticalSection(&m_cs); if(nErr==SOCKET_ERROR) { nErr=WSAGetLastError(); if(nErr==WSAEWOULDBLOCK) { WSANETWORKEVENTS wsevents; WSAEnumNetworkEventsm_UdpSock,eventWinsock,&wsevents); DWORD dwEventId = WaitForSingleObject(eventWinsock,3000); if(dwEventId == WAIT_TIMEOUT) continue; continue; } } else { TRACE("Receive Data Size %d\n",nErr); BYTE init=Recvbuf[0]; TRACE("Packet Size for Init %d =%d and index=%d \n",init, nErr,index); }
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I am trying to receive udp packets which contains video data. I am receiving WSAEWOULDBLOCK error always.Can any one help me The code is WSADATA wsaData; int error = WSAStartup(0x202,&wsaData); if(error) return FALSE; if(wsaData.wVersion != 0x202) { WSACleanup(); return FALSE; } m_UdpSock=(SOCKET)WSASocket(AF_INET,SOCK_DGRAM,0,NULL,NULL,0); if(m_UdpSock==INVALID_SOCKET) return FALSE; sockaddr_in sockAddrServer; sockAddrServer.sin_family=AF_INET; sockAddrServer.sin_port=htons(port_data); sockAddrServer.sin_addr.s_addr=INADDR_ANY; // Bind socket to listener address if(bind(m_UdpSock,(SOCKADDR*)&sockAddrServer,sizeof(sockaddr_in))==SOCKET_ERROR) { int y=WSAGetLastError(); printf("Unable to bind socket\n"); return FALSE; } // Create WinSock Event object WSAEVENT eventWinsock=(WSAEVENT)WSACreateEvent(); if(eventWinsock==WSA_INVALID_EVENT) { printf("Unable to create winsock event\n"); return FALSE; } // Signal WinSock Event on receive packet if(WSAEventSelect(m_UdpSock,eventWinsock,FD_READ)!=NOERROR) { printf("Unable to connect event to socket\n"); return FALSE; } while(m_abort) { Recvbuf=new char[BUFFER_SIZE]; if(WaitForSingleObject(eventWinsock,INFINITE)== WAIT_OBJECT_0) { sockaddr_in sockAddrRecv; int nSockAddrSize=sizeof(sockaddr_in); // Packet received EnterCriticalSection(&m_cs); int nErr=recvfrom(m_UdpSock,Recvbuf,BUFFER_SIZE,0,(sockaddr*)&sockAddrRecv,&nSockAddrSize); LeaveCriticalSection(&m_cs); if(nErr==SOCKET_ERROR) { nErr=WSAGetLastError(); if(nErr==WSAEWOULDBLOCK) { WSANETWORKEVENTS wsevents; WSAEnumNetworkEventsm_UdpSock,eventWinsock,&wsevents); DWORD dwEventId = WaitForSingleObject(eventWinsock,3000); if(dwEventId == WAIT_TIMEOUT) continue; continue; } } else { TRACE("Receive Data Size %d\n",nErr); BYTE init=Recvbuf[0]; TRACE("Packet Size for Init %d =%d and index=%d \n",init, nErr,index); }
WSACreateEvent() creates a manual reset event, but I don't see anywhere that you reset the event after waiting on it. Without resetting it, you end up in a busy loop in between received datagrams.
*edit* Your WSAEnumNetworkEvents() call resets the event, but only every other time through the loop. You'll probably want to fix the logic there :) Either use an auto-rest event or always call WSAEnumNetworkEvents() after the event is signaled, not just if there's a WSAEWOULDBLOCK error.MarkMark Salsbery Microsoft MVP - Visual C++ :java:
modified on Wednesday, April 23, 2008 3:36 AM
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WSACreateEvent() creates a manual reset event, but I don't see anywhere that you reset the event after waiting on it. Without resetting it, you end up in a busy loop in between received datagrams.
*edit* Your WSAEnumNetworkEvents() call resets the event, but only every other time through the loop. You'll probably want to fix the logic there :) Either use an auto-rest event or always call WSAEnumNetworkEvents() after the event is signaled, not just if there's a WSAEWOULDBLOCK error.MarkMark Salsbery Microsoft MVP - Visual C++ :java:
modified on Wednesday, April 23, 2008 3:36 AM
How to reset please explain
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How to reset please explain
See my modified post :) Mark
Mark Salsbery Microsoft MVP - Visual C++ :java: