前言

  這學期的C++課學校用了北理工的一套軟體，大概一兩週就有一次上機考試，軟體的防作弊機制就是每個學號繫結一個IP地址，單學號登入多IP、單IP被多個學號登入都會觸發重修小彩蛋。不過，正所謂時勢造英雄，當人人都在抱怨的時候為什麼不想一個脫離防作弊機制的手段呢？

  本文將介紹我前段時間寫的一個程式，基於TCP的Winsock程式設計實現檔案的傳送。考試時大家埋頭思索，這時候把答案通過IP地址傳送給喜歡的妹子，脫單似乎就近在咫尺了啊。

思路

  Winsock的學習看微軟官網手冊就夠了，一步一步跟著敲下來，基本上就算是入門了。

  下面簡單講一下Winsock程式設計的基本思路：

  Server端：建立巢狀字並初始化，建立socket，初始化socket（將埠號及IP地址繫結），listen監聽，accept不斷接受連線，接受到連線後，捕獲socket，recv獲得內容，通訊完成後關閉socket。

  Client端：建立巢狀字並初始化，建立socket，繫結埠號及目標IP地址，connect連線伺服器，send傳送訊息，通訊結束後關閉socket。

完整程式碼

使用軟體：codeblocks

使用者端：TransferFile-Client.cpp

// TransferFile-Client.cpp:Define the entry point for the console application.
// Program Function : Transfer file by C/S : Part Client
// Author : zhaoyixiang
// E-mail : [email protected]
 

// Date : 2018-5-1

#define _WIN32_WINNT  0x501
#include <winsock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>
#include <stdio.h>
#include <cstring>

#pragma comment(lib, "Ws2_32.lib")

#define DEFAULT_PORT "27015"
#define DEFAULT_BUFLEN 512

using namespace std;

int main(int argc, char const *argv[])
{
    WSADATA wsaData;

    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0)
    {
        printf("WSAStartup failed: %d\n", iResult);
        return 1;
    }


    /*
        Creating a Socket for the Client
        Declare an addrinfo object that contains a sockaddr structure and initialize these values.
        For this application, the Internet address family is unspecified
        so that either an IPv6 or IPv4 address can be returned.
        The application requests the socket type to be a stream socket for the TCP protocol.
    */
    struct addrinfo *result = NULL, *ptr = NULL, hints;
    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    // Resolve the server address and port
    iResult = getaddrinfo(argv[1], DEFAULT_PORT, &hints, &result);
    if (iResult != 0)
    {
        printf("getaddrinfo failed: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    

    char temp[DEFAULT_BUFLEN];
    strcpy(temp, "main.cpp");
    // create file
    FILE * fp = fopen(temp, "rb"); // binary mode for read
    if(fp == NULL)
    {
        printf("open file %s failed\n", temp);
        return -1;
    }

    SOCKET ConnectSocket = INVALID_SOCKET;
    ptr = result;
    ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
    if (ConnectSocket == INVALID_SOCKET)
    {
        printf("Error at socket(): %ld\n", WSAGetLastError());
        freeaddrinfo(result);
        WSACleanup();
        return 1;
    }


    /*
        Connecting to a Socket
        For a client to communicate on a network, it must connect to a server.
    */
    iResult = connect(ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
    if (iResult == SOCKET_ERROR)
    {
        printf("Unable to connect to server!\n");
        WSACleanup();
        return 1;
    }


    /*
        Sending and Receiving Data on the Client
    */
    int recvbuflen = DEFAULT_BUFLEN;
    char recvbuf[DEFAULT_BUFLEN];
    char sendbuf[DEFAULT_BUFLEN];

    int num = 0;
    while(!feof(fp))
    {
        num = fread(temp, 1, DEFAULT_BUFLEN, fp);
        send(ConnectSocket, temp, num, 0);
    }
    printf("server file transfer success\n");

    fclose(fp);
    

    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR)
    {
        printf("Shutdown failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    closesocket(ConnectSocket);


    WSACleanup();
    return 0;
}



 

服務端：TransferFile-Server.cpp

// TranferFile-Server.cpp:Define the entry point for the console application.
// Program Function : Transfer file by C/S : Part Server
// Author : zhaoyixiang
// E-mail : [email protected]
// Date : 2018-5-1

#define _WIN32_WINNT  0x501
#include <winsock2.h>
#include <ws2tcpip.h>
#include <iphlpapi.h>
#include <stdio.h>
#include <cstring>

#pragma comment(lib, "Ws2_32.lib")

#define DEFAULT_PORT "27015"
#define DEFAULT_BUFLEN 512

using namespace std;

int main(int argc, char const *argv[])
{
    WSADATA wsaData;

    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0)
    {
        printf("WSAStartup failed: %d\n", iResult);
        return 1;
    }


    char file_name[DEFAULT_BUFLEN];
    char temp[DEFAULT_BUFLEN];
    strcpy(file_name, "receive test");
    //create file
    FILE *fp = fopen(file_name, "wb");
    if(fp == NULL)
    {
        printf("create file %s failed\n", file_name);
        return -1;
    }


    /*
        Creating a Socket for the Server
    */
    struct addrinfo *result = NULL, hints;

    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;

    iResult = getaddrinfo(NULL, DEFAULT_PORT, &hints, &result);
    if (iResult != 0)
    {
        printf("getaddrinfo failed: %d\n", iResult);
        WSACleanup();
        return 1;
    }
    SOCKET ListenSocket = INVALID_SOCKET;
    ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
    if (ListenSocket == INVALID_SOCKET)
    {
        printf("Error at sock(): %ld\n", WSAGetLastError());
        freeaddrinfo(result);
        WSACleanup();
        return 1;
    }


    /*
        Binding a Socket
        For a server to accept client connections,
        it must be bound to a network address within the system.
    */
    iResult = bind(ListenSocket, result->ai_addr, (int)result->ai_addrlen);
    if (iResult == SOCKET_ERROR)
    {
        printf("bind failed: %d\n", WSAGetLastError());
        freeaddrinfo(result);
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }
    freeaddrinfo(result);



    /*
        Listening on a Socket
        After the socket is bound to an IP address and port on the system,
        the server must then listen on that IP address and port
        for incoming connection requests.
    */
    if (listen(ListenSocket, SOMAXCONN) == SOCKET_ERROR)
    {
        printf("Listen failed with error: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }


    /*
        Accepting a Connection
        Once the socket is listening for a connection,
        the program must handle connection requests on that socket.
    */
    SOCKET ClientSocket;
    ClientSocket = INVALID_SOCKET;
    ClientSocket = accept(ListenSocket, NULL, NULL);
    if (ClientSocket == INVALID_SOCKET)
    {
        printf("accept failed: %d\n", WSAGetLastError());
        closesocket(ListenSocket);
        WSACleanup();
        return 1;
    }


    /*
        Receiving and Sending Data on the Server
    */
    char recvbuf[DEFAULT_BUFLEN];
    int iSendResult;
    int recvbuflen = DEFAULT_BUFLEN;


    //receive data from server
    int num = 0;
    while (1)
    {
        num = recv(ClientSocket, temp, DEFAULT_BUFLEN, 0);
        if(0 == num)
            break;
        fwrite(temp, 1, num, fp);
    }
    printf("transmission done\n");

    fclose(fp);


    // shutdown the connection for sending since no more data will be sent
    // the client can still use the ConnectSocket for receiving data
    iResult = shutdown(ClientSocket, SD_SEND);
    if (iResult == SOCKET_ERROR)
    {
        printf("shutdown failed: %d\n", WSAGetLastError());
        closesocket(ClientSocket);
        WSACleanup();
        return 1;
    }

    // cleanup
    closesocket(ClientSocket);



    WSACleanup();

    return 0;
}

注意事項

  codeblocks呼叫API還是比較麻煩的

  #include <winsock2.h>

  #pragma comment(lib, "Ws2_32.lib")

  以上是常規操作，而cb想編譯成功的話則需進行一下操作：

  選擇project -> Build options

  Linker settings -> other linker options -> 輸入-lws2_32 -> OK

使用方法

  先執行server檔案，再用命令列執行client檔案並輸入接受方的IP地址，事先準備好的main.cpp（可以更換名稱）即可傳送。

  Teamwork時，自己持有Client檔案，給妹子Server檔案，然後趁著月黑風高為所欲為。

補充

  當然了，真正操作的時候不要傻乎乎的將生成的TransferFile-Client.exe / TransferFile-Server.exe檔案直接擺在桌面上，監考老師只要學過英語就能發現你在作弊好吧！！！

  到網上搜一個教程把檔案圖示改了，再把檔名改成常用軟體名，例如notepad++，這樣老師一般不會注意到。

總結

  據說點讚的人一週之內都會脫單。。。（逃