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发信人: scanf (carefully), 信区: Visual
标  题: [zz]用visual c++6.0编写proxy代理
发信站: 荔园晨风BBS站 (Tue Oct 28 22:39:47 2003), 站内信件

用VC++6.0编写Proxy服务器
山东济南 齐鲁晚报
万捷

---- 我们一般常用的Internet代理服务器是用微软的Proxy Server 2.0 。但我们

以自己动手编写一个简单、小型的Proxy Server 。下面介绍具体的实现方法。
---- 一. 原理
---- 本程序的结构原理如下:
---- 对于每一个用户的请求(Internet 请求,由浏览器发出),本程序将启动两

线程,一个把本地用户的请求数据发送到远程的Internet主机,另一个线程把远程

机的回应数据发送到本地请求用户。
---- 二. 主要函数
UserToProxyThread ( void * pParam ) :它是用来把本地用户请求数据发送到远

主机的,起服务器线程角色。当接到本地(局域网)用户的请求,它就启动另一个

身线程,以侦听别的用户的请求,并读出已接收到的请求数据,接着启动第二个线

ProxyToServer()(这个线程用来连接远程主机),当远程主机连接成功后,它把

读出的本地用户请求数据发送到远程主机。
ProxyToServer ( void * pParam) ,可以被当作是客户端服务,它把远程主机发

来的数据分发给本地请求用户。
---- 三. 开发运行环境
---- 本程序是在VC++6.0环境下开发的,在Win95 和 WinNT4.0下运行正常。
#include "stdafx.h"
#include "Proxy.h"
#include < winsock2.h >  //WINSOCKET  API 2。0
#include < stdlib.h >
#include < stdio.h >
#include < string.h >
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
////////////////////////////////////////////////////////////////////////
/////
#define HTTP  "http://"
#define FTP   "ftp://"
#define PROXYPORT    5001    //Proxy 端口
#define BUFSIZE   10240      //缓冲区大小

CWinApp theApp;
using namespace std;
UINT ProxyToServer(LPVOID pParam);
UINT UserToProxyThread(void *pParam);
struct SocketPair{
    SOCKET  user_proxy;      //socket : 本地机器到PROXY 服务机
        SOCKET  proxy_server;    //socket : PROXY 服务机到远程主机
        BOOL    IsUser_ProxyClosed; // 本地机器到PROXY 服务机状态
        BOOL    IsProxy_ServerClosed; // PROXY 服务机到远程主机状态
};

struct ProxyParam{
        char Address[256];    // 远程主机地址
        HANDLE User_SvrOK;    // PROXY 服务机到远程主机的联结状态
        SocketPair *pPair;    // 维护一组SOCKET的指针
        int     Port;         // 用来联结远程主机的端口
};                   //这个结构用来PROXY SERVER与远程主机的信息交换.
SOCKET    gListen_Socket;   //用来侦听的SOCKET。
int StartServer()  //启动服务
{
     WSADATA wsaData;
     sockaddr_in local;
     SOCKET listen_socket;
     if(::WSAStartup(0x202,&wsaData)!=0)
     {
           printf("\nError in Startup session.\n");WSACleanup();
           return -1;
     }
     local.sin_family=AF_INET;
     local.sin_addr.s_addr=INADDR_ANY;
     local.sin_port=htons(PROXYPORT);
      listen_socket=socket(AF_INET,SOCK_STREAM,0);
      if(listen_socket==INVALID_SOCKET)
      {
        printf("\nError in New a Socket.");WSACleanup();
        return -2;
      }
      if(::bind(listen_socket,(sockaddr *)&local,sizeof(local))!=0)
      {
        printf("\n Error in Binding socket.");
        WSACleanup();
        return -3;
       }
       if(::listen(listen_socket,5)!=0)
       {
        printf("\n Error in Listen.");
        WSACleanup();
        return -4;
       }
       gListen_Socket=listen_socket;
       AfxBeginThread(UserToProxyThread,NULL);   //启动侦听
       return 1;
}
int CloseServer()  //关闭服务
{
        closesocket(gListen_Socket);
        WSACleanup();
        return 1;
}
//分析接收到的字符,得到远程主机地址
int GetAddressAndPort( char * str, char *address, int * port)
{
        char buf[BUFSIZE], command[512], proto[128], *p;
        int j;
        sscanf(str,"%s%s%s",command,buf,proto);
        p=strstr(buf,HTTP);
        //HTTP
        if(p)
        {
                p+=strlen(HTTP);
                for(int i=0;i< strlen(p);i++)
                        if( *(p+i)=='/') break;
                *(p+i)=0;
                strcpy(address,p);
                p=strstr(str,HTTP);
                for(int j=0;j< i+strlen(HTTP);j++)
                        //去掉远程主机名:
                        //GET http://www.njust.edu.cn/ HTTP1.1  == > GET /
HTTP1.1
                        *(p+j)=' ';
                *port=80;      //缺省的 http 端口
        }
        else
        {
                //FTP, 不支持, 下面的代码可以省略.
                p=strstr(buf,FTP);
                if(!p) return 0;
                p+=strlen(FTP);
                for(int i=0;i< strlen(p);i++)
                        if( *(p+i)=='/') break;      //Get The Remote Host
                *(p+i)=0;
                for(j=0;j< strlen(p);j++)
                        if(*(p+j)==':')
                        {
                                *port=atoi(p+j+1);    //Get The Port
                                *(p+j)=0;
                        }
                        else *port=21;

                strcpy(address,p);
                p=strstr(str,FTP);
                for(j=0;j< i+strlen(FTP);j++)
                        *(p+j)=' ';
        }
        return 1;
}
// 取到本地的数据,发往远程主机
UINT UserToProxyThread(void *pParam)
{
        char Buffer[BUFSIZE];
        int  Len;
        sockaddr_in from;
        SOCKET msg_socket;
        int fromlen,retval;
        SocketPair SPair;
        ProxyParam ProxyP;
        CWinThread *pChildThread;
        fromlen=sizeof(from);
        msg_socket=accept(gListen_Socket,(struct sockaddr*)&from,&fromlen);
        AfxBeginThread(UserToProxyThread,pParam); //启动另一侦听.
        if( msg_socket==INVALID_SOCKET)
        {
                printf( "\nError  in accept ");
                return -5;
        }

        //读客户的第一行数据
        SPair.IsUser_ProxyClosed=FALSE;
        SPair.IsProxy_ServerClosed=TRUE;
        SPair.user_proxy=msg_socket;
        retval=recv(SPair.user_proxy,Buffer,sizeof(Buffer),0);

        if(retval==SOCKET_ERROR)
        {
                printf("\nError Recv");
                if(SPair.IsUser_ProxyClosed==FALSE)
                {
                        closesocket(SPair.user_proxy);
                        SPair.IsUser_ProxyClosed=TRUE;
                }
        }
        if(retval==0)
        {
                printf("Client Close connection\n");
                if(SPair.IsUser_ProxyClosed==FALSE)
                {
                        closesocket(SPair.user_proxy);
                        SPair.IsUser_ProxyClosed=TRUE;
                }
        }
        Len=retval;
        #ifdef _DEBUG
                Buffer[Len]=0;
                printf("\n Received %d bytes,data[%s]from client\n",retval,
Buffer);
        #endif
        //
        SPair.IsUser_ProxyClosed=FALSE;
        SPair.IsProxy_ServerClosed=TRUE;
        SPair.user_proxy=msg_socket;
        ProxyP.pPair=&SPair;
        ProxyP.User_SvrOK=CreateEvent(NULL,TRUE,FALSE,NULL);
        GetAddressAndPort( Buffer,ProxyP.Address,&ProxyP.Port);
        pChildThread=AfxBeginThread(ProxyToServer,(LPVOID)&ProxyP);
        ::WaitForSingleObject(ProxyP.User_SvrOK,60000);  //等待联结
        ::CloseHandle(ProxyP.User_SvrOK);
        while(SPair.IsProxy_ServerClosed ==FALSE && SPair.
IsUser_ProxyClosed==FALSE)
        {
                retval=send(SPair.proxy_server,Buffer,Len,0);
                if(retval==SOCKET_ERROR)
                {
                        printf("\n send() failed:error%d\n",WSAGetLastError());
                        if(SPair.IsProxy_ServerClosed==FALSE)
                        {
                                closesocket(SPair.proxy_server);
                                SPair.IsProxy_ServerClosed=TRUE;
                        }
                        continue;
                }
            retval=recv(SPair.user_proxy,Buffer,sizeof(Buffer),0);

                if(retval==SOCKET_ERROR)
                {
                        printf("\nError Recv");
                        if(SPair.IsUser_ProxyClosed==FALSE)
                        {
                                closesocket(SPair.user_proxy);
                                SPair.IsUser_ProxyClosed=TRUE;
                        }
                        continue;
                }
                if(retval==0)
                {
                        printf("Client Close connection\n");
                    if(SPair.IsUser_ProxyClosed==FALSE)
                        {
                                closesocket(SPair.user_proxy);
                                SPair.IsUser_ProxyClosed=TRUE;
                        }
                        break;
                }
                Len=retval;
                #ifdef _DEBUG
                        Buffer[Len]=0;
                        printf("\n Received %d bytes,data[%s]from client\n",
retval,Buffer);
                #endif
        } //End While
        if(SPair.IsProxy_ServerClosed==FALSE)
        {
                closesocket(SPair.proxy_server);
                SPair.IsProxy_ServerClosed=TRUE;
        }
        if(SPair.IsUser_ProxyClosed==FALSE)
        {
                closesocket(SPair.user_proxy);
                SPair.IsUser_ProxyClosed=TRUE;
        }
        ::WaitForSingleObject(pChildThread- >m_hThread,20000);  //Should
check the return value
        return 0;
}
// 读取远程主机数据,并发往本地客户机
UINT ProxyToServer(LPVOID pParam)
{
    ProxyParam * pPar=(ProxyParam*)pParam;
        char Buffer[BUFSIZE];
        char *server_name= "localhost";
        unsigned short port ;
        int retval,Len;
        unsigned int addr;
        int socket_type ;
        struct sockaddr_in server;
        struct hostent *hp;
        SOCKET  conn_socket;
        socket_type = SOCK_STREAM;
        server_name = pPar- >Address;
        port = pPar- >Port;
        if (isalpha(server_name[0]))
        {
                /* server address is a name */
                hp = gethostbyname(server_name);
        }
        else
        {
                /* Convert nnn.nnn address to a usable one */
                addr = inet_addr(server_name);
                hp = gethostbyaddr((char *)&addr,4,AF_INET);
        }
        if (hp == NULL )
        {
                fprintf(stderr,
                                "Client: Cannot resolve address [%s]: Error
%d\n",
                                server_name,
                                WSAGetLastError());
                ::SetEvent(pPar- >User_SvrOK);
                return 0;
        }
        //
        // Copy the resolved information into the sockaddr_in structure
        //
        memset(&server,0,sizeof(server));
        memcpy(&(server.sin_addr),hp- >h_addr,hp- >h_length);
        server.sin_family = hp- >h_addrtype;
        server.sin_port = htons(port);
        conn_socket = socket(AF_INET,socket_type,0); /* 打开一个 socket */
        if (conn_socket < 0 )
        {
                fprintf(stderr,
                                "Client: Error Opening socket: Error %d\n",
                                WSAGetLastError());
                pPar- >pPair- >IsProxy_ServerClosed=TRUE;
                ::SetEvent(pPar- >User_SvrOK);
                return -1;
        }
        #ifdef _DEBUG
                printf("Client connecting to: %s\n",hp- >h_name);
        #endif
        if (connect(conn_socket,(struct sockaddr*)&server,sizeof(server))
                == SOCKET_ERROR)
        {
                fprintf(stderr,"connect() failed: %d\n",WSAGetLastError());
                pPar- >pPair- >IsProxy_ServerClosed=TRUE;
                ::SetEvent(pPar- >User_SvrOK);
                return -1;
        }
        pPar- >pPair- >proxy_server=conn_socket;
        pPar- >pPair- >IsProxy_ServerClosed=FALSE;
    ::SetEvent(pPar- >User_SvrOK);
        // cook up a string to send
        while(!pPar- >pPair- >IsProxy_ServerClosed &&!pPar- >pPair-
>IsUser_ProxyClosed)
        {
                retval = recv(conn_socket,Buffer,sizeof (Buffer),0 );
                if (retval == SOCKET_ERROR )
                {
                        fprintf(stderr,"recv() failed: error %d\n",
WSAGetLastError());
                        closesocket(conn_socket);
                        pPar- >pPair- >IsProxy_ServerClosed=TRUE;
                        break;
                }
                Len=retval;
                if (retval == 0)
                {
                        printf("Server closed connection\n");
                        closesocket(conn_socket);
                        pPar- >pPair- >IsProxy_ServerClosed=TRUE;
                        break;
                }
                retval = send(pPar- >pPair- >user_proxy,Buffer,Len,0);
                if (retval == SOCKET_ERROR)
                {
                        fprintf(stderr,"send() failed: error %d\n",
WSAGetLastError());
                        closesocket(pPar- >pPair- >user_proxy);
                        pPar- >pPair- >IsUser_ProxyClosed=TRUE;
                        break;
                }
                #ifdef _DEBUG
                        Buffer[Len]=0;
                        printf("Received %d bytes, data [%s] from server\n",
retval,Buffer);
                #endif
        }
        if(pPar- >pPair- >IsProxy_ServerClosed==FALSE)
        {
                closesocket(pPar- >pPair- >proxy_server);
                pPar- >pPair- >IsProxy_ServerClosed=TRUE;
        }
        if(pPar- >pPair- >IsUser_ProxyClosed==FALSE)
        {
                closesocket(pPar- >pPair- >user_proxy);
                pPar- >pPair- >IsUser_ProxyClosed=TRUE;
        }
        return 1;
}
int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
{
        int nRetCode = 0;
        // 初始化SOCKET
        if (!AfxWinInit(::GetModuleHandle(NULL), NULL, ::GetCommandLine(),
0))
        {
                // 错误处理
                cerr < <  _T("Fatal Error: MFC initialization failed") < <
endl;
                nRetCode = 1;
        }
        else
        {
                // 主程序开始.
                StartServer();
                while(1)
                        if(getchar()=='q') break;
                CloseServer();
        }
        return nRetCode;
}


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