非阻塞recv上奇怪的win sock bug

如何解决非阻塞recv上奇怪的win sock bug

这是我的非重叠套接字的接收文件功能。

            HANDLE recvfile = CreateFile(fileinfo[0],FILE_APPEND_DATA,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL);
            if (recvfile == INVALID_HANDLE_VALUE) {
                sockprintf(sockfd,"[Error Creating File] : %ld",GetLastError());
            }
            else {
                memset(recvbuf,'\0',BUFFER); // Clear main buffer
                int total = 0; // Total bytes received
                // set_blocking_mode(sockfd,FALSE);
                do{ // IF Total is equal to expected bytes. Break the loop,And stop receiving.
                    fsize = recv(sockfd,recvbuf,BUFFER,0); // Receive file
                    if (fsize == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET)
                    {
                        connected = FALSE;
                        printf("[X] Connection interrupted while receiving file %s for %s size.",fileinfo[0],fileinfo[1]);
                    }
                    write = WriteFile(recvfile,fsize,&dwBytesWritten,NULL); // Write file data to file
                    total += fsize; // Add number of bytes received to total.
                } while(total != expected);
                // set_blocking_mode(sockfd,TRUE);
                if (write == FALSE)
                {
                    sockprintf(sockfd,"[Error Writing file %s of %s size] Error : %ld.",fileinfo[1],GetLastError());
                }
                else {
                    sockprintf(sockfd,"\n[ Received File : %s ]\n[ File Size : %s bytes ]\n[ Bytes written : %ld ]\n",dwBytesWritten);
                }
                CloseHandle(recvfile);
            }

这很好用！文件传输几乎是即时的，没有错误或缓冲区损坏。 我在Visual Studio 2019上。问题是，当我编译可执行文件并将其移至测试虚拟机时。程序崩溃。在Windows 10和Windows 7上进行了测试。

崩溃发生在do while循环上。该程序不会中断。我尝试使用msvc（最新）以及mingw-w64和tdm gcc进行编译。错误是相同的。 该代码只能在我自己的机器上运行，而不能在其他任何机器上运行。

解决方法

您需要检查的不只是WSAECONNRESET。几乎每个错误（在非阻塞状态下保存为“ would block”）都是致命的，指示套接字应中止。不要忘记recv可以并且将0返回，如果远程端优雅地关闭其末端。

整个循环：

            do{ // IF Total is equal to expected bytes. Break the loop,And stop receiving.
                fsize = recv(sockfd,recvbuf,BUFFER,0); // Receive file
                if (fsize == SOCKET_ERROR && WSAGetLastError() == WSAECONNRESET)
                {
                    connected = FALSE;
                    printf("[X] Connection interrupted while receiving file %s for %s size.",fileinfo[0],fileinfo[1]);
                }
                write = WriteFile(recvfile,fsize,&dwBytesWritten,NULL); // Write file data to file
                total += fsize; // Add number of bytes received to total.
            } while(total != expected);

应该是：

            do{ 
                fsize = recv(sockfd,0); // Receive file
                if (fsize == SOCKET_ERROR) {

                    int err = WSAGetLastError();
                    if (err == WSAEWOULDBLOCK) {

                        // ISSUE SELECT CALL HERE TO WAIT FOR MORE DATA

                    }
                    else {
                        // FATAL ERROR - abort
                        break;
                    }

                }
                else if (fsize == 0) {
                    break;  // remote connection terminated cleanly.
                }
                else {
                    write = WriteFile(recvfile,NULL);
                    total += fsize;
                }
            } while(total != expected);

,

我已经解决了该问题，IT似乎是我自己的无知，服务器端提供文件信息的速度过快，因此fileinfo[]混在一起了。因此，循环不会中断。仍然不明白为什么它可以在开发机器上工作。无论如何，正如预期的那样，问题不在我在此问题中发布的代码中。谢谢你们！ 解决方案是在睡眠较少的情况下发送数据。 ：）