楊冶軍
本人在用Oicq聊天時,經常收到一些好友發給我的用文本符號描繪的圖像,覺得好羨慕啊,于是一想何 我們一般常用的Internet代理服務器是用微軟的Proxy Server 2.0 。但我們可以自己動手編寫一個簡 單、小型的Proxy Server 。下面介紹具體的實現方法。
一. 原理 本程序的結構原理如下: 對于每一個用戶的請求(Internet 請求,由瀏覽器發出),本程序將啟動兩個線程,一個把本地用戶的請求 數據發送到遠程的Internet主機,另一個線程把遠程主機的回應數據發送到本地請求用戶。
二. 主要函數 UserToProxyThread ( void * pParam ) :它是用來把本地用戶請求數據發送到遠程主機的,起服務器線 程角色。當接到本地(局域網)用戶的請求,它就啟動另一個自身線程,以偵聽別的用戶的請求,并讀出已接 收到的請求數據,接著啟動第二個線程ProxyToServer()(這個線程用來連接遠程主機),當遠程主機連接成 功后,它把已讀出的本地用戶請求數據發送到遠程主機。 ProxyToServer ( void * pParam) ,可以被當作是客戶端服務,它把遠程主機發送來的數據分發給本地請 求用戶。
三. 開發運行環境 本程序是在VC++6.0環境下開發的,在Win95 和 WinNT4.0下運行正常。
四. 詳細代碼 #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 //緩沖區大小
CWinApp theApp; using namespace std; UINT ProxyToServer(LPVOID pParam); UINT UserToProxyThread(void *pParam); struct SocketPair{ SOCKET user_proxy; //socket : 本地機器到PROXY 服務機 SOCKET proxy_server; //socket : PROXY 服務機到遠程主機 BOOL IsUser_ProxyClosed; // 本地機器到PROXY 服務機狀態 BOOL IsProxy_ServerClosed; // PROXY 服務機到遠程主機狀態 };
struct ProxyParam{ char Address[256]; // 遠程主機地址 HANDLE User_SvrOK; // PROXY 服務機到遠程主機的聯結狀態 SocketPair *pPair; // 維護一組SOCKET的指針 int Port; // 用來聯結遠程主機的端口 }; file://這個結構用來PROXY SERVER與遠程主機的信息交換. SOCKET gListen_Socket; file://用來偵聽的SOCKET。 int StartServer() //啟動服務 { 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); //啟動偵聽 return 1; } int CloseServer() //關閉服務 { closesocket(gListen_Socket); WSACleanup(); return 1; } file://分析接收到的字符,得到遠程主機地址 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++) *(p+j)=` `; //去掉遠程主機名: GET http://www.njust.edu.cn/ HTTP1.1 == > GET / HTTP1.1 *port=80; //缺省的 http 端口 } else {//FTP, 不支持, 下面的代碼可以省略. 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; } // 取到本地的數據,發往遠程主機 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); //啟動另一偵聽. if( msg_socket==INVALID_SOCKET) { printf( "\nError in accept "); return -5;} //讀客戶的第一行數據 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); //等待聯結 ::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; } // 讀取遠程主機數據,并發往本地客戶機 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); /* 打開一個 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)) { // 錯誤處理 cerr < < _T("Fatal Error: MFC initialization failed") < < endl; nRetCode = 1; } else { // 主程序開始. StartServer(); while(1) if(getchar()==`q`) break; CloseServer(); } return nRetCode; }
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