IP address 设置好以后，
对于每一个用户的请求（Internet 请求，由浏览器发出），启动两个
线程，一个把本地用户的请求数据发送到远程的Internet主机，另一个线程把远程主
机的回应数据发送到本地请求用户:
#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;
}
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