Returning an IPv4 Address in an IPv6-Enabled Environment

[cool_yogs]

Hi All,

This is my first post in this forum. I am not sure if this is the right thread for my question. Please direct me the correct post if it's needed.
Q: I have an ASP page (test.asp) that reads Request.ServerVariables("REMOTE_ADDR") and passes it down to c++ dll which then reports in log.

When my service is running on XP/2003, it returns following results when above 4 sites are hit:

1. http://localhost/test.asp reports 127.0.0.1
2. http://servername/test.asp form the server itself reports 127.0.0.1
3. http://IPv4AddressOfserver/test.asp from any client machine reports 10.1.1.12 (client's IP4 address)
4. http://servername/test.asp from any client reports 10.1.1.12 (client's IP4 address)

But if it's running on Vista/Server2008 this function returns different addresses as follows:

1. http://localhost/test.asp returns "::1" (it's IP6 address for localhost, when I do "ping localhost" from cmdline on server I get ::1)
2. http://servername/test.asp from the server "fe80::8998:7ecb:2a73:57f6%10" (it's IP6 address of servername, when I do "ping <server name>" on server I get this address).
3. http://IPv4AddressOfserver/test.asp from any (XP/2003/2008) machine returns IPv4 address of the client machine.
4. http://servername/test.asp from any (XP/2003/2008) machine returns IPv4 address of the client machine.

Is there a way to convert these IPv6 addresses into Ipv4 format as shown in first case? Is there any pure (no managed code) CPP function that can convert/extract IPv4 address from the IPv6 address. Does anyone happen to know the solution or can guide/direct me towards the solutions?

I am currently trying following in my cpp dll where sClientIP is being passed down by test.asp:

get_Init(LPSTR sClientIP) {

struct sockaddr_storage ss;
int sslen = sizeof(ss);
memset(&ss, 0, sslen);
reinterpret_cast<sockaddr_in6*>(&ss)->sin6_family = AF_INET6;
int status = 2;
status = ::WSAStringToAddressA(theClientIP, AF_INET6, NULL, reinterpret_cast<sockaddr*>(&ss), &sslen);
if(status == 0) {

struct in6_addr sin6;
sin6 = ((struct sockaddr_in6 *)&ss)->sin6_addr;

struct in_addr sin4;
sin4.S_un.S_un_b.s_b1 = sin6.u.Byte[12];
sin4.S_un.S_un_b.s_b2 = sin6.u.Byte[13];
sin4.S_un.S_un_b.s_b3 = sin6.u.Byte[14];
sin4.S_un.S_un_b.s_b4 = sin6.u.Byte[15];
theClientIP = inet_ntoa(sin4);

}

}

But this returns me following:

1. http://localhost/test.asp reports 0.0.0.1
2. http://servername/test.asp form the server itself reports 42.115.87.246
3. http://IPv4AddressOfserver/test.asp from any client machine reports 10.1.1.12 (client's IP4 address)
4. http://servername/test.asp from any client reports 10.1.1.12 (client's IP4 address)

Any help is greatly appreciated!!

[marshtric]

The Internet is best described as a "network of networks," and every device which is connected to the Internet is uniquely identified by its Internet Protocol (IP) address