IPv6 help (Re: inetutils, r* commands)

Wed Mar 17 08:08:00 GMT 2010

On 2010年3月16日, Charles Wilson wrote:
> That's not really an option. I'm the inetutils (e.g. r* clients and
> daemons, telnet client and daemon, etc) maintainer for cygwin -- I'm
> trying to create the next official cygwin release of those tools.
>> I don't think people would be very happy if they only supported IPv6.

I wasn't suggesting that. AF_INET6 sockets allow IPv4 connectivity. 
Internally, IPv4 addresses are represented as IPv6-mapped addresses. You 
only convert them back to IPv4 text for display purposes (optional).
Done correctly, any single-listener server app should be convertible to 
handle both IPv6 and IPv4 clients without converting it to a 
multi-listener server.
Try googling for writing protocol-independent code.
Your other challenge though is how to handle the address comparisons. 
But if you force the use of mapped addresses for any IPv4 address, things 
should be a little easier.
Antonio Querubin
808-545-5282 x3003
e-mail/xmpp: tony@lava.net
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