Finding all IPv4 addresses associated with INADDR_ANY (?)

[Ronald F. Guilmette]

In message <Pine.NEB.3.96L.1040223233358.13645K-100000 at fledge.watson.org>, you wrote:

>
>On Mon, 23 Feb 2004, Ronald F. Guilmette wrote:
>
>> Given a socket which has been properly created, opened, and then bound
>> to some port and the special INADDR_ANY ``wildcard'' address, I need to
>> be able to them programatically find all of the IPv4 addresses that the
>> socket was just bound to. 
>> 
>> Can anyone suggest a way to do this? 
>> 
>> Can anyone suggest a way to do this easily? 
>> 
>> Can anyone suggest a way to do this portably? 
>
>In another e-mail, it's recommended that you try out getifaddrs().  This
>is almost certainly the best thing to do, but I wanted to point out one
>thing about the question you asked: when you bind a socket to INADDR_ANY,
>you're actually not saying "bind to all addresses available at the moment
>of binding", you're saying "bind to all addresses available at the moment
>of comparison".  I.e., the PCB in kernel retains the value INADDR_ANY, and
>will match new IP addresses added to interfaces at some later time also. 

Thank you for pointing that out.  I certainly did not know that interesting
fact.

For me at least, this distinction is rarely important in practice, because
I personally don't tend to ifconfig new interfaces all that often... like
hardly ever... but it is Good for me to know the implications of what you
just said.