穿透代理服务器.txt

本文详细介绍了windows环境下,如何截获网络封包的技术.

在网络程序设计过程中，我们经常要与各种类型的代理服务器打交道，比如在企业内部网通过代理去访问Internet网上的服务器等等，一般代理服务器支持几种常见的代理协议标准，如Socks4,Socks5,Http代理，其中Socks5需要用户验证，代理相对复杂。我在查阅RFC文档和相关资料后，特总结一些TCP协议穿透代理服务器的程序片断，希望对大家有所帮助。 

//使用到的结构 
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; 
}; 

//通过Socks4方式代理 
if( !ClientSock.Connect( g_ProxyInfo.m_strProxyIP,g_ProxyInfo.m_nProxyPort) ) 
{ 
m_sError = _T("不能连接到代理服务器!"); 
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("通过代理连接主站不成功!"); 
ClientSock.Close(); 
return FALSE; 
} 




//通过Socks5方式代理 
if( !ClientSock.Connect( g_ProxyInfo.m_strProxyIP,g_ProxyInfo.m_nProxyPort) ) 
{ 
m_sError = _T("不能连接到代理服务器!"); 
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("通过代理连接主站不成功!"); 
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("代理服务器用户验证不成功!"); 
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("通过代理连接主站不成功!"); 
ClientSock.Close(); 
return FALSE; 
} 




//通过HTTP方式代理 
if( !ClientSock.Connect( g_ProxyInfo.m_strProxyIP,g_ProxyInfo.m_nProxyPort) ) 
{ 
m_sError = _T("不能连接到代理服务器!"); 
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)); //发送请求 
memset(buff,0,600); 
ClientSock.Receive(buff,600); 
if(strstr(buff, "HTTP/1.0 200 Connection established") == NULL) //连接不成功 
{ 
m_sError = _T("通过代理连接主站不成功!"); 
ClientSock.Close(); 
return FALSE; 
} 
我们一般先与代理服务器连通，然后向代理服务器发送代理验证的用户名和密码(如果需要,如Socks5代理)，验证成功后，再向代理服务器发送需要连接的目的地址和端口。以上代码仅用于TCP连接，如果在内部网侦听或通过UDP协议发送信息，可查阅RFC1829等文档资料。