田進恩 allfresh@263.net


    關鍵詞：代理服務器、Socks4、Socks5、Http代理  

    在網絡程序設計過程中，我們經常要與各種類型的代理服務器打交道，比如在企業內部網通過代理去訪問Internet網上的服務器等等，一般代理服務器支持幾種常見的代理協議標準，如Socks4,Socks5,Http代理，其中Socks5需要用戶驗證，代理相對復雜。我在查閱RFC文檔和相關資料后，特總結一些TCP協議穿透代理服務器的程序片斷，希望對大家有所幫助。

//使用到的結構
struct sock4req1
{
char VN;
char CD;
unsigned short Port;
unsigned long IPAddr;
char other[1];
};

struct sock4ans1
{
char VN;
char CD;
};

struct sock5req1
{
char Ver;
char nMethods;
char Methods[255];
};

struct sock5ans1
{
char Ver;
char Method;
};

struct sock5req2
{
char Ver;
char Cmd;
char Rsv;
char Atyp;
char other[1];
};

struct sock5ans2
{
char Ver;
char Rep;
char Rsv;
char Atyp;
char other[1];
};

struct authreq
{
char Ver;
char Ulen;
char Name[255];
char PLen;
char Pass[255];
};

struct authans
{
char Ver;
char Status;
};

//通過Socks4方式代理
if( !ClientSock.Connect( g_ProxyInfo.m_strProxyIP,g_ProxyInfo.m_nProxyPort) )
{
m_sError = _T("不能連接到代理服務器!");
ClientSock.Close();
return FALSE;
}
char buff[100];
memset(buff,0,100);
struct sock4req1 *m_proxyreq;
m_proxyreq = (struct sock4req1 *)buff;
m_proxyreq->VN = 4;
m_proxyreq->CD = 1;
m_proxyreq->Port = ntohs(GetPort());
m_proxyreq->IPAddr = inet_addr(GetServerHostName());
ClientSock.Send(buff,9);
struct sock4ans1 *m_proxyans;
m_proxyans = (struct sock4ans1 *)buff;
memset(buff,0,100);
ClientSock.Receive(buff,100);
if(m_proxyans->VN != 0 || m_proxyans->CD != 90)
{
m_sError = _T("通過代理連接主站不成功!");
ClientSock.Close();
return FALSE;
}


  

//通過Socks5方式代理
if( !ClientSock.Connect( g_ProxyInfo.m_strProxyIP,g_ProxyInfo.m_nProxyPort) )
{
m_sError = _T("不能連接到代理服務器!");
ClientSock.Close();
return FALSE;
}
char buff[600];
struct sock5req1 *m_proxyreq1;
m_proxyreq1 = (struct sock5req1 *)buff;
m_proxyreq1->Ver = 5;
m_proxyreq1->nMethods = 2;
m_proxyreq1->Methods[0] = 0;
m_proxyreq1->Methods[1] = 2;
ClientSock.Send(buff,4);
struct sock5ans1 *m_proxyans1;
m_proxyans1 = (struct sock5ans1 *)buff;
memset(buff,0,600);
ClientSock.Receive(buff,600);
if(m_proxyans1->Ver != 5 || (m_proxyans1->Method!=0 && m_proxyans1->Method!=2))
{
m_sError = _T("通過代理連接主站不成功!");
ClientSock.Close();
return FALSE;
}
if(m_proxyans1->Method == 2)
{
int nUserLen = strlen(g_ProxyInfo.m_strProxyUser);
int nPassLen = strlen(g_ProxyInfo.m_strProxyPass);
struct authreq *m_authreq;
m_authreq = (struct authreq *)buff;
m_authreq->Ver = 1;
m_authreq->Ulen = nUserLen;
strcpy(m_authreq->Name,g_ProxyInfo.m_strProxyUser);
m_authreq->PLen = nPassLen;
strcpy(m_authreq->Pass,g_ProxyInfo.m_strProxyPass);
ClientSock.Send(buff,513);
struct authans *m_authans;
m_authans = (struct authans *)buff;
memset(buff,0,600);
ClientSock.Receive(buff,600);
if(m_authans->Ver != 1 || m_authans->Status != 0)
{
m_sError = _T("代理服務器用戶驗證不成功!");
ClientSock.Close();
return FALSE;
}
}
struct sock5req2 *m_proxyreq2;
m_proxyreq2 = (struct sock5req2 *)buff;
m_proxyreq2->Ver = 5;
m_proxyreq2->Cmd = 1;
m_proxyreq2->Rsv = 0;
m_proxyreq2->Atyp = 1;
unsigned long tmpLong = inet_addr(GetServerHostName());
unsigned short port = ntohs(GetPort());
memcpy(m_proxyreq2->other,&tmpLong,4);
memcpy(m_proxyreq2->other+4,&port,2);
ClientSock.Send(buff,sizeof(struct sock5req2)+5);
struct sock5ans2 *m_proxyans2;
memset(buff,0,600);
m_proxyans2 = (struct sock5ans2 *)buff;
ClientSock.Receive(buff,600);
if(m_proxyans2->Ver != 5 || m_proxyans2->Rep != 0)
{
m_sError = _T("通過代理連接主站不成功!");
ClientSock.Close();
return FALSE;
}


  

//通過HTTP方式代理
if( !ClientSock.Connect( g_ProxyInfo.m_strProxyIP,g_ProxyInfo.m_nProxyPort) )
{
m_sError = _T("不能連接到代理服務器!");
ClientSock.Close();
return FALSE;
}
char buff[600];
sprintf( buff, "%s%s:%d%s","CONNECT ",GetServerHostName(),GetPort()," HTTP/1.1\r\nUser-Agent: MyApp/0.1\r\n\r\n");
ClientSock.Send(buff,strlen(buff)); //發送請求
memset(buff,0,600);
ClientSock.Receive(buff,600);
if(strstr(buff, "HTTP/1.0 200 Connection established") == NULL) //連接不成功
{
m_sError = _T("通過代理連接主站不成功!");
ClientSock.Close();
return FALSE;
}


    我們一般先與代理服務器連通，然后向代理服務器發送代理驗證的用戶名和密碼(如果需要,如Socks5代理)，驗證成功后，再向代理服務器發送需要連接的目的地址和端口。以上代碼僅用于TCP連接，如果在內部網偵聽或通過UDP協議發送信息，可查閱RFC1829等文檔資料。