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Date: Thu, 2 Dec 2010 19:02:08 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Difference in behaviour between getifaddrs() and ioctl(SIOCGIFCONF)
Message-ID: <20101202180208.GP30913@calimero.vinschen.de>
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On Dec  2 17:54, Jason Curl wrote:
> Jason Curl <jcurlnews <at> arcor.de> writes:
> 
> > Corinna Vinschen <corinna-cygwin <at> cygwin.com> writes:
> > > So, for the above interface we get
> > > 
> > >   371D57D9-0FF3-402C-AB69-E88FF9D85BC3:f36e.1
> > > 
> > > as the unique alias name for the given IPv4 address.
> > > 
> > 
> > The solution that I do prefer, is one similar to QNX. QNX behaves differently 
> > to Linux, but could be the simplest implementation for Cygwin. If an interface 
> > has aliases, it simply has multiple records in getifaddrs(). The ioctl() 
> > interface returns the main/preferred address. Cygwin could return the first 
> > AF_INET record in this case.
> > 
> > That is, you might very well see:
> > * en0, AF_INET, 192.168.0.1
> > * en0, AF_INET, 169.254.123.45
> > * en0, AF_INET6, <address>
> > * lo, AF_INET, 127.0.0.1
> 
> On the way home, I realised the current behaviour deviates from Linux also. 
> 
> Linux getifaddrs():
> * eth0 -> AF_INET
> * eth0 -> AF_INET6
> 
> Cygwin getifaddrs():
> * {xxx} -> AF_INET6
> * {xxx}:1 -> AF_INET

That's already fixed in CVS:

  Cygwin getifaddrs():
  * {xxx} -> AF_INET6
  * {xxx} -> AF_INET   (for the first address)
  * {xxx}:x -> AF_INET (for each following address)

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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