基于Windows Socket的安全通信

图示：红色为控件的ID, 蓝色为映射的变量名

 

下面要添加Socket通信功能了

先了解一下Socket的相关函数原型

 

//加载套接字库
int PASCAL FAR WSAStartup( WORD wVersionRequired, LPWSADATA lpWSAData);
//释放套接字库资源
int PASCAL FAR WSACleanup( void );
//创建套接字
SOCKET PASCAL FAR socket ( int af, int type, int protocol);
//关闭套接字
int PASCAL FAR closesocket (SOCKET s);
//绑定一个IP地址和端口
int PASCAL FAR bind (SOCKET s, const struct sockaddr FAR *addr, int namelen);
//将套接字置为监听状态
int PASCAL FAR listen (SOCKET s, int backlog);
//接受客户端连接请求，并返回新创建的套接字
SOCKET PASCAL FAR accept (SOCKET s, struct sockaddr FAR *addr, int FAR *addrlen);
//尝试将本地套接字连接至服务器
int PASCAL FAR connect (SOCKET s, const struct sockaddr FAR *name, int namelen);
//发送数据
int PASCAL FAR send (SOCKET s, const char FAR * buf, int len, int flags);
//接收数据
int PASCAL FAR recv (SOCKET s, char FAR * buf, int len, int flags);

 

使用Socket的程序在使用Socket之前必须调用WSAStartup函数来绑定Socket库

在Constructor中添加如下代码

 

int error;
WORD wVersionRequested;
WSADATA wsaData;
wVersionRequested = MAKEWORD(2, 1); //加载2.1版本的Socket库
if (error = WSAStartup(wVersionRequested, &wsaData))
{
    AfxMessageBox( "Link Socket Library Failed!" );
    exit (0);
}

应用程序完成对Socket的使用后应当调用WSACleanup函数来释放Socket库占用的系统资源

 

在析构函数冲添加如下代码

 

WSACleanup();

 

 

Socket通信流程

实现安全通信，应采用面向连接的TCP/IP协议来保证连接的可靠性

面向连接的套接字的系统调用时序图

 

添加成员变量及初始化

 

//服务器端：
　　SOCKET Listener,toClient; //用于监听的套接字和连接至客户端的套接字（只是为了实现通信模型，所以不考虑多客户端）
　　 bool listening, connected; //指示监听和连接的状态
　　AES aes; //加密/解密模块

CTestSocketServerDlg::CTestSocketServerDlg(CWnd* pParent):
    CDialog(CTestSocketServerDlg::IDD, pParent),
    aes((unsigned char *) "0123456789abcdef" ),
    listening( false ),
    connected( false )
{
    //Constructor of Server
}

//客户端：
　　SOCKET toServer; //连接至服务器端的套接字
　　 bool connected; //指示连接状态
　　AES aes; //加密/解密模块

CTestSocketClientDlg::CTestSocketClientDlg(CWnd* pParent):
    CDialog(CTestSocketClientDlg::IDD, pParent),
    aes((unsigned char *) "0123456789abcdef" ),
    connected( false )
{
    //Constructor of Client
}

 

为“Start/Stop”按钮注册单击事件处理服务器端初始化及关闭操作

 

void CTestSocketServerDlg::OnBtnStart()
{
    if (connected || listening) //若正在监听或已连接则关闭服务器
    {
        connected = false ;
        listening = false ;
        closesocket(toClient);
        closesocket(Listener);
        m_chat += "Socket Server Stopped!\r\n" ;
        UpdateData( false );
        return ;
    }

    UpdateData( true );
    //创建监听Socket
    struct protoent *ppe;
    ppe = getprotobyname( "tcp" );
    if ((Listener = socket(PF_INET, SOCK_STREAM, ppe->p_proto)) == INVALID_SOCKET)
    {
        m_chat += "Initialize Socket Listener Failed!\r\n" ;
        UpdateData( false );
        return ;
    }

    //绑定IP及端口
    struct sockaddr_in saddr;
    saddr.sin_family = AF_INET;
    saddr.sin_port = htons(m_port);
    saddr.sin_addr.s_addr = htonl(INADDR_ANY);
    if (bind(Listener, ( struct sockaddr *)&saddr, sizeof (saddr)))
    {
        m_chat += "Bind to IPEndPoint Failed! (Port in use?)\r\n" ;
        UpdateData( false );
        return ;
    }
    //开始监听,队列长度1（不考虑多客户端）
    if (listen(Listener, 1))
    {
        m_chat += "Listen Failed!\r\n" ;
        UpdateData( false );
        return ;
    }
    m_chat += "Socket Server Started!\r\n" ;
    UpdateData( false );

    listening = true ;
    AfxBeginThread(Wait4Client, this ); //另起线程等待客户端连接
}

 

接收来自客户端的连接请求

 

UINT Wait4Client( LPVOID pParam)
{
    CTestSocketServerDlg * c = (CTestSocketServerDlg *) pParam;
    struct sockaddr_in caddr;
    int caddrlen = sizeof (caddr);
    c->toClient = accept(c->Listener, ( struct sockaddr *)&caddr, &caddrlen);

    if (c->toClient == INVALID_SOCKET) //异常处理
    {
        if (!c->listening) return 0; //服务器端主动关闭，则直接退出
        c->m_chat += "Connect Failed!\r\n" ;
        c->UpdateData( false );
        return -1;
    }
    else
    {
        c->connected = true ; //连接建立，另起线程用于接收信息
        AfxBeginThread(ReceiveMessage, c);
        c->m_chat += "Client: " ;
        c->m_chat += inet_ntoa(caddr.sin_addr);
        c->m_chat += " Connected!\r\n" ;
        c->m_ip = inet_ntoa(caddr.sin_addr);
        c->UpdateData( false );
    }
    return 0;
}

 

客户端只需要创建Socket并尝试与服务器连接

为“Connect/Disconnect”按钮注册单击事件

 

void CTestSocketClientDlg::OnBtnConnect()
{
    if (connected) //如果已连接，则断开
    {
        connected = false ;
        closesocket(toServer);
        m_chat += "Disconnect to Server!\r\n" ;
        UpdateData( false );
        return ;
    }

    UpdateData( true );
    //创建Socket
    struct protoent *ppe;
    ppe = getprotobyname( "tcp" );
    if ((toServer = socket(PF_INET, SOCK_STREAM, ppe->p_proto)) == INVALID_SOCKET)
    {
        m_chat += "Initialize Socket Listener Failed!\r\n" ;
        UpdateData( false );
        return ;
    }
    //尝试连接服务器
    struct sockaddr_in saddr;
    saddr.sin_family = AF_INET;
    saddr.sin_port = htons(m_port);
    saddr.sin_addr.s_addr = inet_addr(m_ip);
    if (connect(toServer, ( struct sockaddr *)&saddr, sizeof (saddr)))
    {
        m_chat += "Connect Failed!\r\n" ;
        UpdateData( false );
        return ;
    }
    m_chat += "Server: " ;
    m_chat += inet_ntoa(saddr.sin_addr);
    m_chat += " Connected!\r\n" ;
    connected = true ;
    UpdateData( false );
    AfxBeginThread(ReceiveMessage, this ); //连接建立，另起线程用于接收信息
}

 

用于循环接收信息的线程

 

UINT ReceiveMessage( LPVOID pParam)
{
    CTestSocketServerDlg * c = (CTestSocketServerDlg *) pParam;
    char buffer[1024];
    int error; //记录recv函数返回值，即接收的字节数，也作异常代码
    while (error = recv(c->toClient, buffer, 1024, 0))
    {
        if (error == 0 || error == SOCKET_ERROR) break ;
        c->PrintData( "Received Data" , (unsigned char *)buffer, error);
        c->aes.InvCipher(( void *)buffer, error); //解密，恢复明文
        c->PrintData( "Unencrypted Data" , (unsigned char *)buffer, error);
        c->m_chat += "Client:" ;
        c->m_chat += buffer;
        c->m_chat += "\r\n" ;
        c->UpdateData( false );
    }
    c->m_ip = "Not Connected..." ;
    c->UpdateData( false );
    if (!c->connected) return 0; //服务器端主动关闭，直接返回
    closesocket(c->toClient);
    c->connected = false ;
    c->m_chat += "Client Disconnected...\r\n" ;
    c->UpdateData( false );
    AfxBeginThread(Wait4Client, c);
    return 0;
}

 

为“Send”按钮注册单击事件，处理数据的加密发送

 

void CTestSocketServerDlg::OnBtnSend()
{
    if (!connected) return ;
    UpdateData( true );
    if (m_message == "" ) return ;

    int len = m_message.GetLength()+1 >= 1024 ? 1024 : m_message.GetLength()+1;
    len = len%16 ? len+16-len%16 : len;
    char buffer[1024];
    strcpy (buffer,m_message.GetBuffer(0)); //将message拷贝至buffer数组中
    m_message.ReleaseBuffer();
    PrintData( "Input Data" , (unsigned char *)buffer, len);
    aes.Cipher(( void *)buffer); //对数据进行加密
    if (send(toClient, buffer, len, 0) == SOCKET_ERROR) //发送密文
    {
        m_chat += "Send Failed!(Socket Exception?)\r\n" ;
        UpdateData( false );
        return ;
    }
    PrintData( "Encrypted Data" , (unsigned char *)buffer, len);
    m_chat += "Server:" + m_message + "\r\n" ;
    m_message = "" ;
    UpdateData( false );
}

 

发送和接收的时候都用到了一个函数PrintData,用于将明文或密文以16进制输出以便作演示

 

void CTestSocketServerDlg::PrintData( char * title, unsigned char * buffer, int length)
{
    int i;
    CString temp( "" );
    m_chat += "(" ;
    m_chat += title;
    m_chat += ":" ;
    for (i=0; i<length; i++)
    {
        temp.Format( "%s%X " ,*(buffer+i)>15? "" : "0" ,*(buffer+i));
        m_chat += temp;
    }
    m_chat += ")\r\n" ;
}

 

贴出的代码都是服务器端的，客户端代码类似，最大区别就是类名不同，不做赘述

 

运行效果