支持通过代理服务器连接

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。