//C源代碼：客戶端怎樣通過proxy進行連接，支持https, socks5代理
//版權說明 
//此代碼為遙志軟件版權所有，任何形式的商業行為的使用都必須征得遙志軟件的授權和同意
//base64編碼
static void to64frombits(unsigned char *out, const unsigned char *in, int inlen)
{
const char base64digits[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (; inlen >= 3; inlen -= 3)
{
*out++ = base64digits[in[0] >> 2];
*out++ = base64digits[((in[0] << 4) & 0x30) | (in[1] >> 4)];
*out++ = base64digits[((in[1] << 2) & 0x3c) | (in[2] >> 6)];
*out++ = base64digits[in[2] & 0x3f];
in += 3;
}
if (inlen > 0)
{
unsigned char fragment;

*out++ = base64digits[in[0] >> 2];
fragment = (in[0] << 4) & 0x30;
if (inlen > 1)
fragment |= in[1] >> 4;
*out++ = base64digits[fragment];
*out++ = (inlen < 2) ? '=' : base64digits[(in[1] << 2) & 0x3c];
*out++ = '=';
}
*out = '\0';
};

//-- connect proxy
BOOL ConnectEx(SOCKET sock, const char *lpszDestHost, int nDestPort, const char * lpszProxyAddress, const int nProxyPort, const char * lpszProxyProtocol, BOOL bNeedAuth, const char * lpszUserName, const char * lpszPassword)
{
//connect to proxy
char szBuffer[1024 + 1] = {""};
int nLen = 0;

SOCKADDR_IN saProxy;
saProxy.sin_family = AF_INET;
saProxy.sin_port = nProxyPort;
saProxy.sin_addr.S_un.S_addr= inet_addr(lpszProxyAddress);
if (saProxy.sin_addr.S_un.S_addr == INADDR_NONE)
{
LPHOSTENT lphost;
lphost = gethostbyname(lpszProxyAddress);
if (lphost != NULL)
saProxy.sin_addr.S_un.S_addr = ((LPIN_ADDR)lphost->h_addr)->s_addr;
else
{
return 0;
}
} 

if(connect(sock, (SOCKADDR*)&saProxy, sizeof(SOCKADDR)))
{
return 0;
}

if(stricmp(lpszProxyProtocol, "HTTPS") == 0 || stricmp(lpszProxyProtocol, "HTTP") == 0 )
{
if(bNeedAuth)
{
//Proxy-Authorization: Basic 
char szAuth[1024 + 1] = {""};
char szAuthT[1024 + 1] = {""};
sprintf(szAuthT, "%s:%s", lpszUserName,lpszPassword);
to64frombits((UCHAR *)szAuth, (UCHAR *)szAuthT, strlen(szAuthT));
sprintf(szBuffer, "CONNECT %s:%d HTTP/1.0\r\nProxy-Authorization: Basic %s\r\n\r\n", lpszDestHost, nDestPort, szAuth);
}
else
{
sprintf(szBuffer, "CONNECT %s:%d HTTP/1.0\r\n\r\n", lpszDestHost, nDestPort);
}

nLen = strlen(szBuffer);
send(sock, szBuffer, nLen, 0);
nLen = 1024;
recv(sock, szBuffer, nLen, 0);
if(strnicmp(szBuffer, "HTTP/1.0 200", strlen("HTTP/1.0 200")) == 0 || 
strnicmp(szBuffer, "HTTP/1.1 200", strlen("HTTP/1.1 200")) == 0)
{
return 1;
}
return 0;
}

if(stricmp(lpszProxyProtocol, "SOCKS5") == 0)
{
//auth
nLen = 0;
if(bNeedAuth)
{
szBuffer[0] = 5;
szBuffer[1] = 2;
szBuffer[2] = 0;
szBuffer[3] = 2;
nLen = 4;
send(sock, szBuffer, nLen, 0);
nLen = 2;
recv(sock, szBuffer, nLen, 0);
if(szBuffer[0] == 5)
{
//need auth
if(szBuffer[1] == 2)
{
szBuffer[0] = 1;
nLen = strlen(lpszUserName);
szBuffer[1] = nLen;
strcpy(szBuffer+2, lpszUserName);
nLen += 2;
szBuffer[nLen] = strlen(lpszPassword);
strcpy(szBuffer+nLen+1, lpszPassword);
nLen = nLen + 1 + strlen(lpszPassword);
send(sock, szBuffer, nLen, 0);
nLen = 2;
recv(sock, szBuffer, nLen, 0);
if(szBuffer[1] != 0)
{
return 0;
}
}
else
{
if(szBuffer[1] != 0)
{
return 0;
}
}
}
else
return 0;

}
else
{
szBuffer[0] = 5;
szBuffer[1] = 1;
szBuffer[2] = 0;
nLen = 3;
send(sock, szBuffer, nLen, 0);
nLen = 2;
recv(sock, szBuffer, nLen, 0);
if(szBuffer[0] != 5 || szBuffer[1] != 0)
{
return 0;
}
}
//translate DestAddr
szBuffer[0] = 5;
szBuffer[1] = 1;
szBuffer[2] = 0;
szBuffer[3] = 3;//DOMAIN
szBuffer[4] = strlen(lpszDestHost);//domain len
strcpy(szBuffer+5, lpszDestHost);
unsigned short uPort = htons(nDestPort);
memcpy(szBuffer+5+strlen(lpszDestHost), &uPort, 2);
nLen = 5 + strlen(lpszDestHost) + 2;
send(sock, szBuffer, nLen, 0);
nLen = 10;
recv(sock, szBuffer, nLen, 0);
if(szBuffer[0] != 5 || szBuffer[1] != 0)
{
return 0;
}
return 1;
}
return 0;
}