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Re: misc/39327

On Fri, May 22, 2009 at 05:05:03PM +0000, Jukka Ruohonen wrote:
> The following reply was made to PR misc/39327; it has been noted by GNATS.
> From: Jukka Ruohonen <>
> To:
> Cc: 
> Subject: Re: misc/39327
> Date: Fri, 22 May 2009 20:04:48 +0300
>  5AOn Fri, May 22, 2009 at 11:09:07AM -0400, Martin S. Weber wrote:
>  > Well, it's true that it shouldn't be "the DARPA internet" anylonger, but
>  > what about the other part of the fix suggestion, i.e. document in 
>  > /etc/procotols which domain (by socket(2) parlese) the protocol is for?
>  I am not sure whether I follow you with the other part.
>  1. I think it is not so easy nor reasonable for a single operating system to
>  change '/etc/protocols' because it comes from IANA, a.k.a. the Internet
>  Assigned Numbers Authority. Functions like getprotobyname(3) also use
>  '/etc/protocols' as a lookup; changing it will break a lot of things.

I understand that, but on the other hand even the IANA will not block
an improvement in a file they provide, will they?

>  2. Generally the file is not meant as a reference for the domain-parameter
>  in socket(2), but rather as a reference for the number in the protocol-field
>  of IPv4 header (or next header -field in IPv6), as described also in the
>  file itsef. Even if such change would be made, there is no mapping between
>  the AF_-constants and the file (surely e.g. TCP can be used both with
>  AF_INET and AF_INET6).

I think there's some confusion here. I wasn't talking about the domain
parameter of socket(), but about its protocol parameter:

 socket(int domain, int type, int protocol);

The domain parameter can be PF_INET, PF_INET6 and a lot of others, for
the _protocol_ parameter the manpage says, "The protocol number to use is 
particular to the communication domain in which communication is to 
take place; see protocols(5).".

That makes me think: There exists a mapping of domain parameters to
a set of usable protocol parameters. Look at protocols(5) (and thus
at /etc/protocols) to find out which. But /etc/protocols only documents
the possible protocols at all. Now if /etc/protocols had also a field
for the "communication domain in which communication is to take place",
there would be no doubt about usable protocols. Take "icmp 1 ICMP" for
instance. If it read "icmp 1 ICMP PF_INET" instead, it would be obvious
that icmp is not for PF_INET6. Actually even expanding the comment instead
of adding a new field to improve documentation on where this procotol 
"belongs" would improve the situation in my opinion.

>  3. Moreover, I think the socket(2) manual page does not rightly give any
>  impression that one should look to '/etc/protocols' for the AF_-constants.

AF_ ? The socket(2) man page only talks about PF_ constants (besides, I
personally never understood THEIR distinction but that is outside the scope
of this PR.)


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