WinSock 重叠I/O模型

 

//服务端/*。在程序清单7-8 中，我们向大家展示了如何构建一个简单的服务器应用，令其采用前述的方法，通过完成例程，来实现对一个套接字请求的管理。该程序的编码主要按下述步骤进行：① 新建一个套接字，开始在指定端口上，监听一个进入的连接。② 接受一个进入的连接请求。③ 为接受的套接字创建一个WSAOVERLAPPED 结构。④ 在套接字上投递一个异步WSARecv 请求，方法是将WSAOVERLAPPED 指定成为参数，同时提供一个完成例程。⑤ 在将fAlertable 参数设为TRUE 的前提下，调用WSAWaitForMultipleEvents，并等待一个重叠I/O 请求完成。重叠请求完成后，完成例程会自动执行，而且WSAWaitForMultipleEvents 会返回一个WSA_IO_COMPLETION。在完成例程内，可随一个完成例程一道，投递另一个重叠WSARecv 请求。⑥ 检查WSAWaitForMultipleEvents 是否返回WSA_IO_COMPLETION。⑦ 重复第⑤步和第⑥步。程序清单7-8 采用完成例程的简单重叠I/O 处理示例// 说明：该例介绍了如何使用重叠I/O 模型开发简单的回显服务器应用，该例也是简单的控制台程序，  */// 它会在连接从服务器建立和移除时打印消息。该应用会在5150 端口监听和接收进入的TCP 连//接，// 收到客户端发送的数据时，会把收到的数据按照原来的格式发送回去// 编译：cl -o overlap overlap.cpp ws2_32.lib#include <winsock2.h>#include <windows.h>#include <stdio.h>#pragma comment(lib,"ws2_32.lib") #define PORT 5150#define DATA_BUFSIZE 8192typedef struct _SOCKET_INFORMATION {CHAR Buffer[DATA_BUFSIZE];   WSABUF DataBuf;SOCKET Socket;WSAOVERLAPPED Overlapped;DWORD BytesSEND;DWORD BytesRECV;} SOCKET_INFORMATION, * LPSOCKET_INFORMATION;DWORD EventTotal = 0;   //事件对象总数DWORD WINAPI ProcessIO(LPVOID lpParameter);WSAEVENT EventArray[WSA_MAXIMUM_WAIT_EVENTS];LPSOCKET_INFORMATION SocketArray[WSA_MAXIMUM_WAIT_EVENTS];   CRITICAL_SECTION CriticalSection;int main(void){WSADATA wsaData;SOCKET ListenSocket, AcceptSocket;SOCKADDR_IN InternetAddr;DWORD Flags;DWORD ThreadId;DWORD RecvBytes;INT Ret;InitializeCriticalSection(&CriticalSection);   //初始化临界区printf("主函数开始执行\n") ;if ((Ret = WSAStartup(0x0202,&wsaData)) != 0){printf("WSAStartup failed with error %d\n", Ret);WSACleanup();return 0 ;}if ((ListenSocket = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0,WSA_FLAG_OVERLAPPED)) == INVALID_SOCKET)  //创建监听端口{printf("Failed to get a socket %d\n", WSAGetLastError());return 0 ;}InternetAddr.sin_family = AF_INET;InternetAddr.sin_addr.s_addr = htonl(INADDR_ANY);InternetAddr.sin_port = htons(PORT);if (bind(ListenSocket, (PSOCKADDR) &InternetAddr, sizeof(InternetAddr)) ==SOCKET_ERROR)  //绑定端口{printf("bind() failed with error %d\n", WSAGetLastError());return 0 ;}if (listen(ListenSocket, 5)){printf("listen() failed with error %d\n", WSAGetLastError());return  0 ;}// 建立连接的监听套接字if ((AcceptSocket = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0,WSA_FLAG_OVERLAPPED)) == INVALID_SOCKET)   //这里创建了一个异步的{printf("Failed to get a socket %d\n", WSAGetLastError());return  0 ;}if ((EventArray[0] = WSACreateEvent()) == WSA_INVALID_EVENT)  //第一个事件对象{printf("WSACreateEvent failed with error %d\n", WSAGetLastError());return  0 ;}// 创建服务重叠请求的线程printf("创建线程\n") ;if (CreateThread(NULL, 0, ProcessIO, NULL, 0, &ThreadId) == NULL)  //为什么不叫ThreadIO,也叫ProcessIO咧？{printf("CreateThread failed with error %d\n", GetLastError());return  0 ;}EventTotal = 1;  //突然间冒出来int i = 0 ;while(TRUE){// 接收进入的连接printf("Main第%d次循环\n",i+1) ;i++ ;printf("等待连接,兼进入临界区\n") ;if ((AcceptSocket = accept(ListenSocket, NULL, NULL)) == INVALID_SOCKET){printf("accept failed with error %d\n", WSAGetLastError());return 0 ;}EnterCriticalSection(&CriticalSection);   //临界区？？// 创建同接收的套接字相关的套接字信息结构体if ((SocketArray[EventTotal] = (LPSOCKET_INFORMATION) GlobalAlloc(GPTR,sizeof(SOCKET_INFORMATION))) == NULL){printf("GlobalAlloc() failed with error %d\n", GetLastError());return 0 ;}// 填充接收套接字的细节SocketArray[EventTotal]->Socket = AcceptSocket;  //新套接字的？ZeroMemory(&(SocketArray[EventTotal]->Overlapped), sizeof(OVERLAPPED)); SocketArray[EventTotal]->BytesSEND = 0;SocketArray[EventTotal]->BytesRECV = 0;SocketArray[EventTotal]->DataBuf.len = DATA_BUFSIZE;SocketArray[EventTotal]->DataBuf.buf = SocketArray[EventTotal]->Buffer;if ((SocketArray[EventTotal]->Overlapped.hEvent = EventArray[EventTotal] =WSACreateEvent()) == WSA_INVALID_EVENT)    //将第几个事件对象赋给{printf("WSACreateEvent() failed with error %d\n", WSAGetLastError());return  0;}// 发布WSARecv 请求开始在套接字上接收数据Flags = 0;if (WSARecv(SocketArray[EventTotal]->Socket,&(SocketArray[EventTotal]->DataBuf), 1, &RecvBytes, &Flags,&(SocketArray[EventTotal]->Overlapped), NULL) == SOCKET_ERROR){if (WSAGetLastError() != ERROR_IO_PENDING){printf("WSARecv() failed with error %d\n", WSAGetLastError());return 0;}}EventTotal++;printf("离开临界区\n") ;LeaveCriticalSection(&CriticalSection);// 信号通知事件数组中的第一个事件，让工作线程服务事件数组中的其它事件if (WSASetEvent(EventArray[0]) == FALSE){printf("WSASetEvent failed with error %d\n", WSAGetLastError());return  0 ;}}//whilereturn 0 ;}DWORD WINAPI ProcessIO(LPVOID lpParameter){DWORD Index;DWORD Flags;LPSOCKET_INFORMATION SI;DWORD BytesTransferred;DWORD i;DWORD RecvBytes, SendBytes;printf("进入ProcessIO\n") ;int j = 0 ;// 处理异步WSASend、WSARecv 请求while(TRUE){printf("ProcessIO第%d次循环\n",j+1) ;j++ ;if ((Index = WSAWaitForMultipleEvents(EventTotal, EventArray, FALSE,WSA_INFINITE, FALSE)) == WSA_WAIT_FAILED){printf("WSAWaitForMultipleEvents failed %d\n", WSAGetLastError());return 0;}// 如果触发的事件为零，然后会在我们的监听套接字上进行连接尝试if ((Index - WSA_WAIT_EVENT_0) == 0)  //如果是0的话，就直接跳到下一个循环？什么回事？{WSAResetEvent(EventArray[0]);continue;}SI = SocketArray[Index - WSA_WAIT_EVENT_0];WSAResetEvent(EventArray[Index - WSA_WAIT_EVENT_0]);if (WSAGetOverlappedResult(SI->Socket, &(SI->Overlapped), &BytesTransferred,FALSE, &Flags) == FALSE || BytesTransferred == 0){printf("Closing socket %d\n", SI->Socket);if (closesocket(SI->Socket) == SOCKET_ERROR){printf("closesocket() failed with error %d\n", WSAGetLastError());}GlobalFree(SI);WSACloseEvent(EventArray[Index - WSA_WAIT_EVENT_0]);// 通过删除事件句柄和套接字信息结构体来清除SocketArray 和EventArrayEnterCriticalSection(&CriticalSection);  //临界区。。if ((Index - WSA_WAIT_EVENT_0) + 1 != EventTotal)for (i = Index - WSA_WAIT_EVENT_0; i < EventTotal; i++){EventArray[i] = EventArray[i + 1];SocketArray[i] = SocketArray[i + 1];}EventTotal--;LeaveCriticalSection(&CriticalSection);  //离开临界区continue;}// 查看BytesRECV 域是否为0，然后这意味着WSARecv 调用刚刚完成，因此可以用从已完//成// 的WSARecv 调用中获得的BytesTransferred 值来更新 BytesRECV 域if (SI->BytesRECV == 0){SI->BytesRECV = BytesTransferred;SI->BytesSEND = 0;}else{SI->BytesSEND += BytesTransferred;}if (SI->BytesRECV > SI->BytesSEND){// 发布另一个WSASend()请求，因为WSASend()不能确保发送所以请求的字节，继续//发布// WSASend()调用直到所以收到的字节被发送ZeroMemory(&(SI->Overlapped), sizeof(WSAOVERLAPPED));SI->Overlapped.hEvent = EventArray[Index - WSA_WAIT_EVENT_0];SI->DataBuf.buf = SI->Buffer + SI->BytesSEND;SI->DataBuf.len = SI->BytesRECV - SI->BytesSEND;if (WSASend(SI->Socket, &(SI->DataBuf), 1, &SendBytes, 0,&(SI->Overlapped), NULL) == SOCKET_ERROR)  //这里发出去{if (WSAGetLastError() != ERROR_IO_PENDING){printf("WSASend() failed with error %d\n", WSAGetLastError());return 0;}}}else{SI->BytesRECV = 0;// 现在不在需要发布WSARecv 请求来发送其余的数据Flags = 0;ZeroMemory(&(SI->Overlapped), sizeof(WSAOVERLAPPED));SI->Overlapped.hEvent = EventArray[Index - WSA_WAIT_EVENT_0];SI->DataBuf.len = DATA_BUFSIZE;SI->DataBuf.buf = SI->Buffer;if (WSARecv(SI->Socket, &(SI->DataBuf), 1, &RecvBytes, &Flags,&(SI->Overlapped), NULL) == SOCKET_ERROR)  //接收事件{if (WSAGetLastError() != ERROR_IO_PENDING){printf("WSARecv() failed with error %d\n", WSAGetLastError());return 0;}}else{//printf("接收: %s",SI->DataBuf ) ; 一次是接收不完的}}}printf("离开ProcessIO\n") ;}

 

 

 

//客户端/*程序清单6-2 是客户端代码，客户端建立一个套接字，并对投入应用的服务器名进行解析，然后与服务器建立连接。连接一旦建成，就可发送大量的消息了。每次发送数据之后，客户端都会等待服务器发回的回应。客户端把得自套接字的数据打印出来。回应客户端和服务器不能完全说明TCP 协议的流式传输。这是因为读取操作是在写操作之后进行的，至少客户端这一端是这样的。当然，对服务器来说，还有另一种方式。因此，服务器每次调用读取函数，一般都会返回客户端发出的整条消息。但不要误会，如果客户端的消息大到超过了TCP 的最大传输单元，在线上，它会被分成几个小的数据包，这种情况下，接收端需要多次执行接收调用，才能收完整条消息。为了更好地说明流式传输，运行客户端和服务器时带上-O 选项即可。这样，客户端便只管发送数据，接收端只管读取数据。  服务器如下执行：server -p:5150 -o而客户端如下执行：client -p:5150 -s:IP -n:10 -o大家最可能见到的是客户端进行了10 次send 调用，而服务器在一次或两次recv 调用中，就读取了10 条消息。*///程序清单6-2 回应客户端代码// 说明：回显客户端，连接TCP 服务器，发送数据，并且读服务器返回的数据// 编译命令：cl -o Client Client.c ws2_32.lib//// 命令行参数：// client [-p:x] [-s:IP] [-n:x] [-o]// -p:x 发送的远程端口// -s:IP 服务器IP 地址或主机名// -n:x 发送消息次数// -o 只发送消息，不接收//#include <winsock2.h>#include <stdio.h>#include <stdlib.h>#pragma  comment(lib, "Ws2_32.lib ")#define DEFAULT_COUNT 10#define DEFAULT_PORT 5150#define DEFAULT_BUFFER 2048#define DEFAULT_MESSAGE "This is a test of the emergency \broadcasting system"char szServer[128], // 连接的服务器szMessage[1024]; // 发送给服务器的消息int iPort = DEFAULT_PORT; // 连接到服务器的端口DWORD dwCount = DEFAULT_COUNT; // 发送消息次数BOOL bSendOnly = FALSE; // 只发送数据，不接收 void usage() ; void ValidateArgs(int argc, char **argv) ;// 函数：main// 说明：执行主线程，初始化Winsock，解释命令行参数，创建套接字，连接服务器，然后发送//和接// 收数据int main(int argc, char **argv){WSADATA wsd;SOCKET sClient;char szBuffer[DEFAULT_BUFFER];int ret,i;struct sockaddr_in server;struct hostent *host = NULL;// 解释命令行并且载入WinsockValidateArgs(argc, argv);if (WSAStartup(MAKEWORD(2,2), &wsd) != 0){printf("Failed to load Winsock library!\n");return 1;}strcpy(szMessage, DEFAULT_MESSAGE);// 创建套接字，并且尝试连接服务器sClient = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);if (sClient == INVALID_SOCKET){printf("socket() failed: %d\n", WSAGetLastError());return 1;}server.sin_family = AF_INET;server.sin_port = htons(iPort);server.sin_addr.s_addr = inet_addr(szServer);// 如果提供的服务器地址不是形如"aaa.bbb.ccc.ddd"，则为主机名，尝试解析它if (server.sin_addr.s_addr == INADDR_NONE){host = gethostbyname(szServer);if (host == NULL){printf("Unable to resolve server: %s\n", szServer);return 1;}CopyMemory(&server.sin_addr, host->h_addr_list[0],host->h_length);}if (connect(sClient, (struct sockaddr *)&server,sizeof(server)) == SOCKET_ERROR){printf("connect() failed: %d\n", WSAGetLastError());return 1;}// 发送和接收数据for(i = 0; i < dwCount; i++){ret = send(sClient, szMessage, strlen(szMessage), 0);if (ret == 0)break;else if (ret == SOCKET_ERROR){printf("send() failed: %d\n", WSAGetLastError());break;}printf("Send %d bytes\n", ret);if (!bSendOnly){ret = recv(sClient, szBuffer, DEFAULT_BUFFER, 0);if (ret == 0) // Graceful closebreak;else if (ret == SOCKET_ERROR){printf("recv() failed: %d\n", WSAGetLastError());break;}szBuffer[ret] = '\0';printf("RECV [%d bytes]: '%s'\n", ret, szBuffer);}}closesocket(sClient);WSACleanup();return 0;} void usage(){printf("usage: client [-p:x] [-s:IP] [-n:x] [-o]\n\n");printf(" -p:x Remote port to send to\n");printf(" -s:IP Server's IP address or hostname\n");printf(" -n:x Number of times to send message\n");printf(" -o Send messages only; don't receive\n");ExitProcess(1);}// 函数：ValidateArgs// 说明：解释命令行参数，设置全局变量void ValidateArgs(int argc, char **argv){int i;for(i = 1; i < argc; i++){if ((argv[i][0] == '-') || (argv[i][0] == '/')){switch (tolower(argv[i][1])){case 'p': // Remote portif (strlen(argv[i]) > 3)iPort = atoi(&argv[i][3]);break;case 's': // Serverif (strlen(argv[i]) > 3)strcpy(szServer, &argv[i][3]);break;case 'n': // Number of times to send messageif (strlen(argv[i]) > 3)dwCount = atol(&argv[i][3]);break;case 'o': // Only send message; don't receivebSendOnly = TRUE;break;default:usage();break;}}}}