[erlang-bugs] ipv6 bug in inet:ntoa

[Raimo Niskanen]

On Fri, Jun 26, 2015 at 08:43:42PM +0000, Rik Ribbers wrote:
> Hello,
> 
> I've been playing around with ipv6 in erlang and came across at first
> strange behaviour in converting string to ipv6 and back
> 
> ~ --> erl
> Erlang/OTP 18 [erts-7.0] [source-4d83b58] [64-bit] [smp:4:4]
> [async-threads:10] [hipe] [kernel-poll:false]
> 
> Eshell V7.0  (abort with ^G)
> 1>inet:parse_address("2a00:d78::147:94:198:152:68").
> {ok,{10752,3448,0,327,148,408,338,104}}
> 2> inet:ntoa({10752,3448,0,327,148,408,338,104}).
> "2A00:D78:0:147:94:198:152:68"
> 
> If you look closely you will see that there is an extra 0 introduced. This
> is actually correct. In IETF RFC5952 section 4.2.2 states that a single 0
> must not be shortened. This however introduces however the question is the
> inet:parse_address is actually correct, however it is being friendly to its
> caller...

There is no ambiguity here so why not.

> 
> The real issue is however that the addresses are displayed in uppercase
> which is simply wrong. As RFC5952 clearly states in section 4.3. There is
> even Errata on this issue that states it must be in lower case.
> 
> The RFC can be found here https://tools.ietf.org/html/rfc5952

Oh dear.  We'll probably have to fix that.

To my defence I will say that the code is from November 2009 which predates
that RFC and that it tries to follow RFC 4291 or maybe RFC 3513.  It also uses
erlang:integer_to_list/2 that produces uppercase, just for the same reasons
that the rejected Errata voices...

Thank you for pointing this out.


> 
> Kind regards,
> Rik Ribbers

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-- 

/ Raimo Niskanen, Erlang/OTP, Ericsson AB