SOCKET通过代理连接服务器

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 代理方式包括：HTTP代理、SOCKET5代理。RFC参考文档：http://oss.org.cn/man/develop/rfc/default.htm
 一、通过HTTP代理

 int CProxy_TestDlg::HttpConnect(const char *proxy_ip,int proxy_port,const char *svr_ip,int svr_port)
 {
     SOCKET socket_ = ::socket(AF_INET,SOCK_STREAM,0);
     sockaddr_in sa;
     sa.sin_addr.s_addr = inet_addr(proxy_ip);
     sa.sin_port = htons(proxy_port);
     sa.sin_family = AF_INET;

     int error_code = ::connect(socket_,(SOCKADDR*)&sa,sizeof(sa));
     if(error_code == SOCKET_ERROR)
     {
         ::closesocket(socket_);
         return 1;
     }
     char tmpBuffer[128] = {0};
     ::sprintf(tmpBuffer,"CONNECT %s:%d HTTP/1.1\r\nUser-Agent: Mozilla/4.0\r\nConnection: Keep-Alive\r\n\r\n",svr_ip,svr_port);
     ::send(socket_,tmpBuffer,strlen(tmpBuffer),0);
     memset(tmpBuffer,0,128);
     ::recv(socket_,tmpBuffer,128,0);
     int mj, mi, code;
     ::sscanf(tmpBuffer, "HTTP/%d.%d %d", &mj, &mi, &code);
     if (code != 200)
     {
         ::closesocket(socket_);
         return 2;
     }
     ::closesocket(socket_);
     return 0;
 }

 HTTP代理方式测试通过。。。
 二、SOCKET5代理
 1、使用的结构如下：

 #pragma pack(push,1)
 //请求认证方式
 typedef struct tagSocket5_Requst
 {
     char Ver;            //版本号:05
     char NMethods;
     char Methods[255];
 }Socket5_Request,*LPSocket5_Request;
 //认证方式应答
 typedef struct tagSocket5_Response
 {
     char Ver;
     char Method;//X'00'不需要认证;X'01'GSSAPI;X'02用户名/密码;X'03' -- X'7F'由IANA分配;X'80' -- X'FE'为私人方法所保留的;X'FF'没有可以接受的方法

 }Socket5_Response,*LPSocket5_Response;

 //认证请求
 typedef struct tagSocket5_Auth_Request
 {
     char   Ver;   //1
     char   Ulen;
     char   Name[255];
     char   PLen;
     char   Pass[255];
 }Socket5_Auth_Request,*LPSocket5_Auth_Request;

 typedef struct tagSocket5_Auth_Response
 {
     char   Ver;
     char   Status;
 }Socket5_Auth_Response,*LPSocket5_Auth_Response;
 //连接请求
 typedef struct tagSocket5_Connect_Request
 {
     char Ver;
     char Cmd;//CONNECT：X'01';BIND：X'02';UDP ASSOCIATE：X'03'
     char Rsv;//保留，填0
     char Atyp;//   后面的地址类型,IPV4：X'01';域名：X'03';IPV6：X'04',暂时只支持IPV4
     unsigned long DestAddr;//IPV4是4个字节，IPV6是6个字节;基于域名的地址，地址字段中的第一字节是以字节为单位的该域名的长度，没有结尾的NUL字
     unsigned short DestPort;

 }Sokcet5_Connect_Request,*LPSocket5_Connect_Request;
 //连接应答
 typedef struct tagSokcet5_Connect_Response
 {
     char Ver;
     char Rep;
     char Rsv;
     char Atyp;
     unsigned long DestAddr;
     unsigned short DestPort;
 }Socket5_Connect_Response,*LPSocket5_Connect_Response;
 #pragma pack(pop)
 2、函数定义：
 int CProxy_TestDlg::Socket5Connect(const char *proxy_ip,int proxy_port,const char *user,const char *passwd,const char *svr_ip,int svr_port)
 {
     //首先连接SOCKET5代理服务器
     SOCKET socket_ = ::socket(AF_INET,SOCK_STREAM,0);
     sockaddr_in sa;
     sa.sin_addr.s_addr = inet_addr(proxy_ip);
     sa.sin_port = htons(proxy_port);
     sa.sin_family = AF_INET;

     int error_code = ::connect(socket_,(SOCKADDR*)&sa,sizeof(sa));
     if(error_code == SOCKET_ERROR)
     {
         ::closesocket(socket_);
         return 1;
     }
     char buffer[128] = {0};
     int len = 0;
     //发送认证发送请求Socket5_Request/Socket5_Response
     Socket5_Request req;
     Socket5_Response rep;
     req.Ver = 0x05;
     req.NMethods = 2;
     req.Methods[0] = 0;
     req.Methods[1] = 2;
     if((len = ::send(socket_,(char*)&req,sizeof(req),0)) <=0)
     {
         ::closesocket(socket_);
         return 4;
     }

     if((len = ::recv(socket_,(char*)&rep,sizeof(rep),0)) <=0)
     {
         ::closesocket(socket_);
         return 4;
     }

     if(rep.Ver != 0x05)
     {
         ::closesocket(socket_);
         return 5;
     }

     if(rep.Method != 0x00 && rep.Method != 0x02)
     {
         ::closesocket(socket_);
         return 6;
     }

     if(rep.Method == 0x02)
     {//需要用户名、密码验证

         //进行认证Socket5_Auth_Request/Socket5_Auth_Response
         Socket5_Auth_Request auth_req;
         Socket5_Auth_Response auth_rep;
         memset(&auth_req,0,sizeof(Socket5_Auth_Request));
         memset(&auth_rep,0,sizeof(Socket5_Auth_Response));
         auth_req.Ver = 1;//?
         auth_req.Ulen = strlen(user);
         strcpy(auth_req.Name,user);
         auth_req.PLen = strlen(passwd);
         strcpy(auth_req.Pass,passwd);
         if((len = ::send(socket_,(char*)&auth_req,sizeof(auth_req),0)) <=0)
         {
             ::closesocket(socket_);
             return 4;
         }
         if((len = ::recv(socket_,(char*)&auth_rep,sizeof(auth_rep),0)) <=0)
         {
             ::closesocket(socket_);
             return 4;
         }
         if(auth_rep.Status != 0)
         {
             ::closesocket(socket_);
             return 7;
         }
     }
     //发送连接请求Sokcet5_Connect_Request/Socket5_Connect_Response
     Sokcet5_Connect_Request conn_req;
     Socket5_Connect_Response conn_rep;
     memset(&conn_req,0,sizeof(Sokcet5_Connect_Request));
     memset(&conn_rep,0,sizeof(Socket5_Connect_Response));

     conn_req.Ver = 0x05;
     conn_req.Cmd = 0x01;//
     conn_req.Atyp = 0x01;
     conn_req.DestAddr = inet_addr(svr_ip);
     conn_req.DestPort = htons(svr_port);

     if((len = ::send(socket_,(char*)&conn_req,sizeof(conn_req),0)) <=0)
     {
         ::closesocket(socket_);
         return 4;
     }

     if((len = ::recv(socket_,(char*)&conn_rep,sizeof(conn_rep),0)) <=0)
     {
         ::closesocket(socket_);
         return 4;
     }
     if(conn_rep.Rep != 0)
     {
         ::closesocket(socket_);
         return 8;
     }
     //连接成功

     ::closesocket(socket_);
     return 0;
 }

 SOCKET5还没有测试。。。
 三、根据网址获取该网址的IP地址
 char * URL2IP(const char *url)
 {
     struct hostent * ph;
     struct in_addr in;
     memset( &in, 0x0, sizeof(in) );
     // 传递的域名地址通过 gethostbyname 函数转换成 HOSTENT 结构的指针
     if((ph = gethostbyname(url)) == NULL)
         return NULL;

     memcpy( (char**)&in, ph->h_addr_list[0], sizeof(in) );

     return ::inet_ntoa( in );

 }

转载自：http://blog.csdn.net/educast/article/details/17450951