[bug-inetutils] Re: [PATCH] Implement IPv6 capability for the TFTP server.

[Mats Erik Andersson]

onsdag den 29 september 2010 klockan 08:12 skrev Simon Josefsson detta:
> Mats Erik Andersson <address@hidden> writes:
> 
> > tisdag den 28 september 2010 klockan 23:50 skrev Simon Josefsson detta:
> >> Mats Erik Andersson <address@hidden> writes:
> >> 
> >> > My other suggested patching of the TFTP client presently adds
> >> >
> >> >      NI_MAXSERV
> >> >      struct addrinfo
> >> >      getaddrinfo(3)
> >> >      gai_strerror(3)
> >> >      freeaddrinfo(3)
> >> >      strrchr(3)
> >> >
> >> > All these are fulfilled by any decent OS as far as I understand.
> >> 
> >> And if they aren't, gnulib fixes that for us.
> >> 
> >> However, why do you need NI_MAXSERV?  I can't find it in POSIX nor in
> >> the Glibc manual.  I'm not sure it is portable.
> >
> > See getnameinfo(3). The constant ought to be present in <netdb.h>
> > for every decent OS.
> 
> Interesting, it is documented in RFC 2133/2553/4038 and from the man
> page it appears to be intended as a GNU-extension, but it is not
> mentioned in POSIX or the Glibc manual.  I wonder how portable it is?
> An old Solaris host I looked at had it.  Maybe something for the Austin
> group...
> 
> NOTES
>        In  order to assist the programmer in choosing reasonable sizes for the
>        supplied buffers, <netdb.h> defines the constants
> 
>            #define NI_MAXHOST      1025
>            #define NI_MAXSERV      32
> 
>        Since glibc 2.8, these definitions are exposed only if one of the  
> fea???
>        ture test macros _BSD_SOURCE, _SVID_SOURCE, or _GNU_SOURCE is defined.
> 
>        The  former  is  the  constant  MAXDNAME  in  recent versions of BIND's
>        <arpa/nameser.h> header file.  The latter is a guess based on the  
> ser???
>        vices listed in the current Assigned Numbers RFC.

Quoting from OpenBSD, i.e., their libc implementation, and getnameinfo(3):

    The maximum value for _hostlen_ is NI_MAXHOST and the maximum value
    for _servlen_ is NI_MAXSERV, as defined in <netdb.h>.

Once someone begins commenting on the TFTP __client__ patch, I will also
condition the use of NI_MAXHOST for that code, just to be safe. Anyway,
the use of NI_MAXHOST and NI_MAXSERV is commonly considered as the portable
way for OpenBSD and GNU/Linux as far as I understand things.

Mats E A