如何使用 Winsock 傳送多位元組帶外資料

本文內容

• 簡介

  • 建立用戶端應用程式

  • 建立伺服器應用程式

  • 顯示用戶端應用程式的範例代碼，Myclient .cpp

  • 顯示伺服器應用程式（Myserver）的範例程式碼。

  • 測試範例

• 參考

建立用戶端應用程式

1. 建立用戶端應用程式。 在此用戶端應用程式中，下列範例程式碼說明如何建立兩個通訊端：

   SOCKET myOOBSocket = INVALID_SOCKET;SOCKET myNormalSocket = INVALID_SOCKET;myOOBSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);myNormalSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);

   MyOOBSocket變數是用來傳送 OOB 資料。 MyNormalSocket變數是用來傳送一般資料。

2. 因為 myOOBSocket 變數所傳送的資料不是真正的 OOB 資料，所以您必須在開始傳送資料之前，告訴伺服器應該要傳送哪一種資料。 下列範例程式碼說明如何傳送初始字元，以通知伺服器要傳送哪種類型的資料。 針對 OOB 資料使用 "U"，並針對一般資料使用 "N"。

   int nErr, nSize;nErr = connect(myNormalSocket, (SOCKADDR *)&remoteIp, sizeof(remoteIp));//Look for a potential error here.//"remoteIp" is the remote address.nSize = send(myNormalSocket, "N",1, 0);//Look for a potential error here.nErr = connect(myOOBSocket, (SOCKADDR *)&remoteIp, sizeof(remoteIp));//Look for a potential error here.nSize = send(myOOBSocket,"U",1, 0);//Look for a potential error here.

3. 下列範例程式碼說明如何讓用戶端應用程式監視來自使用者的輸入。 用戶端應用程式將大寫字元作為 OOB 資料傳送。 重複每個輸入字元以組成多位元組字元串。

   for (;;) {int ch = _getch();_putch( ch );if (ch=='.') {shutdown(myOOBSocket, 2);        shutdown(myNormalSocket,2);break;}        char buf[10];        memset(buf, ch, sizeof(buf));        if (isupper(ch)) {nSize = send(myOOBSocket, buf, sizeof(buf), 0);//Do not use the MSG_OOB flag. Send it as normal data.} else {nSize = send(myNormalSocket, buf, sizeof(buf), 0);}...}

顯示用戶端應用程式的範例代碼，請 Myclient .cpp 回到頂端

建立伺服器應用程式

1. 在伺服器端，下列範例程式碼說明如何建立監聽器通訊端來監視通訊所用的埠：

   int nErr;SOCKET myListener = INVALID_SOCKET;myListener = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);//Look for a potential return error here.nErr = bind(myListener,(SOCKADDR *)&localIp,sizeof(localIp));//Look for a potential return error here.//"localIp" is the local address of the server.nErr = listen(myListener, 5);//Look for a potential return error here.

2. 下列範例程式碼說明如何呼叫 accept 函數，讓監聽器通訊端等待傳入的連線嘗試：

   for (;;) {struct sockaddr_in remoteIp;SOCKET remoteSocket = INVALID_SOCKET;int nAddrLen = sizeof(SOCKADDR);remoteSocket = accept(myListener, (SOCKADDR *)(&remoteIp), &nAddrLen);//"remoteIp" is a pointer to a buffer that receives //the address of the connecting entity.BYTE buffer[1+1];int recv_len=recv(remoteSocket,(char *)&buffer,1,0);//This supposes that the client sockets will send//"U" or "N" as the initial character.    buffer[recv_len] = '\0';if(strcmp((char *)buffer,"U")==0)hThread=CreateThread(0,0,OOBHandler,(LPVOID)remoteSocket, 0, &dwThreadId);//Create a new thread to process incoming OOB data. "OOBHandler" is a //pointer to the OOB data handler. else if(strcmp((char *)buffer,"N")==0)hThread=CreateThread(0,0,NormalHandler,(LPVOID)remoteSocket, 0, &dwThreadId);//Create a new thread to process incoming normal data. "NormalHandler" is //a pointer to the normal data handler....}

3. 若要模擬 OOB 機制，您必須同步處理這兩個執行緒。 在這個範例應用程式中，請使用全域 事件 物件來執行這項作業。 將下列語句放在檔案的頂端。

   //Create a manual-reset event object. hRecvEvent=CreateEvent(NULL,TRUE,TRUE,"RecvEvent");

4. 建立由個別執行緒執行的 OOB 處理常式。 在此處理程式中，您可以使用 select 函數來偵測資料何時到達。 當資料到達時，請遵循下列步驟：

   1. 呼叫 ResetEvent 函數，將 hRecvEvent 事件物件設定為非終止狀態。

      ResetEvent(hRecvEvent);

      這會封鎖在另一個執行緒中執行的一般資料處理程式。

   2. 呼叫 revc 函數來讀取資料。

      recv(remoteSocket,(char *)&buffer,sizeof(buffer) - 1,0);

   3. 因為可能會傳送超過緩衝區所能保留的資料，所以請再次呼叫 接收 函式，並與 MSG_PEEK 旗標一起判斷是否有任何資料可在網路上使用。

      recv(remoteSocket,(char *)&buffer,sizeof(buffer)-1,MSG_PEEK);

      根據是否有要讀取的資料，使用下列其中一種方法：

      • 如果沒有要讀取的資料，請呼叫 SetEvent 函數，將指定的事件物件設定為終止狀態。

        SetEvent(hRecvEvent);

        當您這麼做時，一般的資料處理程式執行緒可以繼續執行。 在正常的資料處理程式執行緒繼續進行之前，一般的資料處理程式執行緒會等待 hRecvEvent 事件物件。

      • 如果仍有要讀取的資料，請再次呼叫 接收 函數，以讀取剩餘的資料。 接著，請再次查看擱置中的資料。

   重複步驟4a 到4c，直到已讀取所有擱置中的資料為止。

5. 建立一般的資料處理程式。 此處理程式與 OOB 資料處理程式類似，不同的是，一般資料處理程式會在一般資料處理程式偵測到已到達資料時，呼叫 WaitForSingleObject 函數。

   WaitForSingleObject(hRecvEvent,INFINITE);//You can set the interval parameter to a specific value if you do not want  //the normal data handler to wait for the OOB handler indefinitely when OOB data arrives continuously.

將伺服器應用程式的範例代碼（Myserver）顯示回到頂端

顯示用戶端應用程式的範例代碼，Myclient .cpp

注意： 您必須包含對 Winsock 文件庫檔案的參照，Ws2_32 .lib，才能編譯器代碼。

#include <stdio.h>#include <stdlib.h>#include <conio.h>#include <assert.h>#include <winsock.h>main(int argc, char *argv[]){int nErr, nSize;WSADATA wsaData;SOCKET myOOBSocket = INVALID_SOCKET;SOCKET myNormalSocket = INVALID_SOCKET;unsigned short nPort; // Listen for the port number.struct sockaddr_in remoteIp;if (argc!=3){printf("TcpDemoC <RemoteIp> <Port>\n");return 0;}// The Init Socket API.nErr = WSAStartup(MAKEWORD(1,1),&wsaData);assert(nErr==0);nPort = (unsigned short)atol(argv[2]);myOOBSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);assert(myOOBSocket!=INVALID_SOCKET);myNormalSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);assert(myNormalSocket!=INVALID_SOCKET);// Connect to the remote address.remoteIp.sin_family = AF_INET;remoteIp.sin_port = htons(nPort);;remoteIp.sin_addr.S_un.S_addr = inet_addr(argv[1]);nErr = connect(myOOBSocket, (SOCKADDR *)&remoteIp, sizeof(remoteIp));if (nErr == SOCKET_ERROR) {printf("Connect failed because of %lX\n",  WSAGetLastError());goto Cleanup;}nSize = send(myOOBSocket,"U",1, 0);if (nSize == SOCKET_ERROR) {printf("Send failed because of %lX\n", WSAGetLastError());        goto Cleanup;}    nErr = connect(myNormalSocket, (SOCKADDR *)&remoteIp, sizeof(remoteIp));if (nErr == SOCKET_ERROR) {int error = WSAGetLastError();printf("Connect failed because of %lX\n", error);goto Cleanup;}    nSize = send(myNormalSocket, "N",1, 0);if (nSize == SOCKET_ERROR) {printf("Send failed because of %lX\n", WSAGetLastError());goto Cleanup;}printf("Read for input:\n");for (;;) {int ch = _getch();_putch( ch );if (ch=='.') {shutdown(myOOBSocket, 2);shutdown(myNormalSocket,2);break;}char buf[10];memset(buf, ch, sizeof(buf));if (isupper(ch)) {nSize = send(myOOBSocket, buf, sizeof(buf), 0);}else{nSize = send(myNormalSocket, buf, sizeof(buf), 0);}if (nSize == SOCKET_ERROR) {printf("Send failed because of %lX\n", WSAGetLastError());break;}}Sleep(1000);Cleanup:if (myOOBSocket!=INVALID_SOCKET)closesocket(myOOBSocket);if (myNormalSocket!=INVALID_SOCKET)closesocket(myNormalSocket);WSACleanup();return 0;}

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顯示伺服器應用程式（Myserver）的範例程式碼。

注意： 您必須包含對 Winsock 文件庫檔案的參照，Ws2_32 .lib，才能編譯器代碼。

#include <windows.h>#include <stdio.h>#include <stdlib.h>#include <winsock.h>#include <assert.h>// Usage: myserver <port>HANDLE hRecvEvent; DWORD WINAPI OOBHandler(LPVOID lpParam){int nErr, nRecv_len;BYTE buffer[10 + 1];BOOL bClosing=FALSE;fd_set fdread;SOCKET remoteSocket=(SOCKET)lpParam;unsigned long ul=1;int nRet = ioctlsocket(remoteSocket, FIONBIO, &ul);if(SOCKET_ERROR==nRet){printf("Socket() failed: %d\n", WSAGetLastError());return 1;}printf("Waiting");for (int i=0; i<10; i++) {printf(".");Sleep(1000);}printf("The OOB handler is ready!\n");while (!bClosing){//Always clear the set before you call the select method.FD_ZERO(&fdread);//Add sockets to the sets.FD_SET(remoteSocket, &fdread);nErr=select(0,&fdread,0,0,0);if(nErr==SOCKET_ERROR){printf("Select() failed: %d\n",WSAGetLastError());return 1;}if(FD_ISSET(remoteSocket,&fdread)){ResetEvent(hRecvEvent);while(1){nRecv_len=recv(remoteSocket,(char *)&buffer,sizeof(buffer) - 1,0);                    if(nRecv_len==0){bClosing=TRUE;printf("The connection is closed!\n");break;}buffer[nRecv_len] = '\0';printf("[OOB]: %s\n", buffer);                    nRecv_len=recv(remoteSocket,(char *)&buffer,sizeof(buffer)-1,MSG_PEEK);if (nRecv_len==SOCKET_ERROR) {if(WSAGetLastError()==WSAEWOULDBLOCK)break;elseprintf("Recv() failed. Win32 error is 0x%lx\n", WSAGetLastError());}}SetEvent(hRecvEvent);} }return 0;}DWORD WINAPI NormalHandler(LPVOID lpParam){int nErr,nRecv_len;BYTE buffer[10 + 1];fd_set fdread;SOCKET remoteSocket=(SOCKET)lpParam;printf("Waiting");for (int i=0; i<10; i++) {        printf("*");Sleep(1000);}printf("Normal handler ready!\n");while(1) {//Always clear the set before you call the select method.FD_ZERO(&fdread);//Add sockets to the sets.FD_SET(remoteSocket, &fdread);nErr=select(0,&fdread,0,0,0);if(nErr==SOCKET_ERROR){printf("Select() failed: %d\n",WSAGetLastError());return 1;}if(FD_ISSET(remoteSocket,&fdread)){WaitForSingleObject(hRecvEvent,INFINITE);nRecv_len=recv(remoteSocket,(char *)&buffer,sizeof(buffer) - 1,0);            if (nRecv_len==SOCKET_ERROR) {printf("Recv() failed. Win32 error is 0x%lx\n", WSAGetLastError());return 1;}            if(nRecv_len==0){printf("Connection Closed!\n");break;}       buffer[nRecv_len] = '\0';printf("[Normal]: %s\n", buffer);}}return 0;}int main(int argc, char *argv[]){WSADATA wsaData;int nErr;SOCKET myListener = INVALID_SOCKET;struct sockaddr_in localIp;unsigned short nPort; DWORD dwThreadId;HANDLE hThread=NULL;if (argc!=2){printf("MyServer <Port>\n");return 0;}nPort = (unsigned short)atol(argv[1]);nErr = WSAStartup(MAKEWORD(2,0),&wsaData);assert(nErr==0);assert(wsaData.wVersion == MAKEWORD(2,0));myListener = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);assert(myListener!=INVALID_SOCKET);// Bind the listen socket to any local IP address.localIp.sin_family = AF_INET;localIp.sin_port = htons(nPort);;localIp.sin_addr.S_un.S_addr = INADDR_ANY;nErr = bind(myListener,(SOCKADDR *)&localIp,sizeof(localIp));assert(nErr!=SOCKET_ERROR);nErr = listen(myListener, 5);assert(nErr==0);//Create a manual-reset event object. hRecvEvent=CreateEvent(NULL,TRUE,TRUE,"RecvEvent");if (hRecvEvent == NULL) { printf("CreateEvent failed with error 0x%lx\n", GetLastError());return 1;}printf("The server is ready!\n");for (;;) {struct sockaddr_in remoteIp;SOCKET remoteSocket = INVALID_SOCKET;int nAddrLen = sizeof(SOCKADDR);remoteSocket = accept(myListener, (SOCKADDR *)(&remoteIp), &nAddrLen);if(remoteSocket == INVALID_SOCKET) {int error = WSAGetLastError();printf("Accept() failed. Win32 error is 0x%lx\n", GetLastError());goto Cleanup;} else {printf("Connected from %d.%d.%d.%d:%d\n", remoteIp.sin_addr.S_un.S_un_b.s_b1,remoteIp.sin_addr.S_un.S_un_b.s_b2,remoteIp.sin_addr.S_un.S_un_b.s_b3,remoteIp.sin_addr.S_un.S_un_b.s_b4,ntohs(remoteIp.sin_port));BYTE buffer[1+1];int nRecv_len=recv(remoteSocket,(char *)&buffer,1,0);if (nRecv_len==SOCKET_ERROR) {printf("Recv() failed. Win32 error is 0x%lx\n", WSAGetLastError());return 1;}    buffer[nRecv_len] = '\0';if(strcmp((char *)buffer,"U")==0)hThread=CreateThread(0,0,OOBHandler,(LPVOID)remoteSocket, 0, &dwThreadId);else if(strcmp((char *)buffer,"N")==0)hThread=CreateThread(0,0,NormalHandler,(LPVOID)remoteSocket, 0, &dwThreadId);           if(hThread==0){printf("CreateThread() failed: %d\n",GetLastError());return 1;}CloseHandle(hThread);}}closesocket(myListener);Cleanup:WSACleanup();return 0;}

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測試範例

1. 在命令提示字元中，輸入 Myserver 4444 來啟動埠4444上的伺服器。伺服器應用程式會顯示下列訊息，然後等待用戶端：

   伺服器已就緒！

2. 在不同的 [命令提示字元] 視窗中，輸入MyClient IPAddress 4444 以啟動用戶端。 注意： 預留位置 [ IPAddress ] 是伺服器 IP 位址的預留位置。

3. 伺服器會顯示如下所示的訊息：

   Waiting.Waiting*..*當您收到前一封郵件時，您必須在用戶端的10秒內輸入 aBcDeFgHi ，然後才能繼續進行。

大約10秒之後，伺服器會顯示下列資訊：

[OOB]： BBBBBBBBBB [OOB]： DDDDDDDDDD [OOB]： FFFFFFFFFF [OOB]： HHHHHHHHHH [Normal]： aaaaaaaaaa [Normal]： cccccccccc [normal]： eeeeeeeeee [Normal]： gggggggggg [normal]： iiiiiiiiii回到頁首