[erlang-questions] is inet:gethostbyname( IP ) correct?

Raimo Niskanen <>
Thu Oct 15 14:47:27 CEST 2009


On Wed, Oct 14, 2009 at 03:34:12PM +0200, info wrote:
> For me this function always returns {error,timeout} and I didn't find the reason even with the help of Raimo Niskanen !

Sorry about that, but your problem became a just too spooky
Windows 2003 problem and that is not really my turf, and
you seemed to have a possible workaround through inet_res.
But it has been on my todo list to have a second look
at the whole conversation when I could find the time...

> 
> 
> At the end of my last mail you have the references.
> Regards,
> 
> Roberto Aloi
> Erlang Training and Consulting Ltd.
> http://www.erlang-consulting.com
> http://aloiroberto.wordpress.com
> 
> Robert Raschke wrote:
> > This is part of the IP address spec (not sure where to look to find it,
> > though). I've seen addresses specified like this on and off in various
> > locations on a wide variety of OSes, for example in a /etc/hosts file you
> > can write:
> >
> > localhost  127.1
> >
> > Robby
> >
> > On Tue, Oct 13, 2009 at 8:06 PM, caio ariede  < > wrote:
> >
> >   
> > > Interesting case.
> > >
> > > The result doesn't appear to be an issue, but a feature of the
> > > gethostbyname
> > > original implementation, in C code.
> > >
> > > You get the same result, testing with PHP:
> > >
> > > $ php -r 'var_dump(gethostbyname("12.27"));'
> > > string(9) "12.0.0.27"
> > >
> > > And other interesting results:
> > >
> > > $ php -r 'var_dump(gethostbyname("255.2.256"));'
> > > string(9) "255.2.1.0"
> > >
> > > But I can't see where it's really useful.
> > >
> > > Caio Ariede
> > > http://caioariede.com/
> > >
> > >
> > > On Tue, Oct 13, 2009 at 3:15 PM, Garry Hodgson  <
> > >     
> > > > wrote:
> > > >       
> > > > recently, a bug in my code caused us to pass a string
> > > > representing a floating point number to inet:gethostbyname().
> > > > i would have expected it to return an error, but instead it
> > > > returned an ip address, but one that made no sense to me:
> > > >
> > > > 1 > inet:gethostbyname( '12.27' ).
> > > > {ok,{hostent,"12.27",[],inet,4,[{12,0,0,27}]}}
> > > >
> > > > so my question is, is this behavior correct, and if so, what
> > > > exactly does it mean that a lookup of '12.27' maps to '12.0.0.27'?
> > > >
> > > > thanks
> > > >
> > > > --
> > > > Garry Hodgson
> > > > Lead Member of Technical Staff
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> > > >       
> >
> >   
> 
> 
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-- 

/ Raimo Niskanen, Erlang/OTP, Ericsson AB


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