building libc

building libc

[Per Jessen]

All,

I'm trying to build a shared libary with a modified getaddrinfo() from
glibc.  getaddrinfo() sorts the results from DNS according to RFC3484,
but this screws up round-robin load-balancing.

Ian Jackson put a fix into ubuntus glibc 2.6.1, and this is what I'm
trying to use.

So, I've got glibc-2.6.1 from ubuntu all built, and I'm now trying to
build my own mygetaddrinfo.so containing just the patched getaddrinfo().
Has anyone attempted something similar, and if so, do you have any hints
for me?
I can build mygetaddrinfo.so, but when I try to use it (with
LD_PRELOAD), it keeps reporting unresolved symbols such as __inet_aton.


cheers
Per Jessen, Zurich

Re: building libc

[Per Jessen]

Per Jessen wrote:
> All,
> 
> I'm trying to build a shared libary with a modified getaddrinfo() from
> glibc.  getaddrinfo() sorts the results from DNS according to RFC3484,
> but this screws up round-robin load-balancing.
> 
> Ian Jackson put a fix into ubuntus glibc 2.6.1, and this is what I'm
> trying to use.
> 
> So, I've got glibc-2.6.1 from ubuntu all built, and I'm now trying to
> build my own mygetaddrinfo.so containing just the patched getaddrinfo().
> Has anyone attempted something similar, and if so, do you have any hints
> for me?

Alright, I realize this was perhaps a little unclear.  What I'm trying
to achieve is actually quite simple:

- to replace the normal getaddrinfo() routine from the default glibc
libary with my own version.

My "own" version just happens to be 2000 lines of getaddrinfo from the
ubuntu glibc which was patched to fix the RFC3484 problem.  I'm just not
very keen on working my way through the 2000 lines and fixing things
such that it will compile outside of the complete glibc tree.


Per Jessen, Zurich

Re: building libc

[Darío Mariani]

On Dec 12, 2007 10:43 PM, Darío Mariani <mariani.dario@gmail.com> wrote:

>
> On Dec 12, 2007 5:15 PM, Per Jessen <per@computer.org> wrote:
>
>
> > Per Jessen wrote:
> > > All,
> > >
> > > I'm trying to build a shared libary with a modified getaddrinfo() from
> > > glibc.  getaddrinfo() sorts the results from DNS according to RFC3484,
> > > but this screws up round-robin load-balancing.
> > >
> > > Ian Jackson put a fix into ubuntus glibc 2.6.1, and this is what I'm
> > > trying to use.
> > >
> > > So, I've got glibc-2.6.1 from ubuntu all built, and I'm now trying to
> > > build my own mygetaddrinfo.so containing just the patched getaddrinfo().
> > > Has anyone attempted something similar, and if so, do you have any hints
> > > for me?
> >
> > Alright, I realize this was perhaps a little unclear.  What I'm trying
> > to achieve is actually quite simple:
> >
> > - to replace the normal getaddrinfo() routine from the default glibc
> > libary with my own version.
> >
> > My "own" version just happens to be 2000 lines of getaddrinfo from the
> > ubuntu glibc which was patched to fix the RFC3484 problem.  I'm just not
> > very keen on working my way through the 2000 lines and fixing things
> > such that it will compile outside of the complete glibc tree.
> >
> >
> > Per Jessen, Zurich
> >
> >
>
> There is a method to replace glibc functions, don't remember how exactly but take a look at Transconnect (http://transconnect.sourceforge.net/ ) and this link: http://www.itworld.com/AppDev/1006/UIR000929interposers/pfindex.html.
>
>

There is a method to replace glibc functions, don't remember how
exactly but take a look at Transconnect
(http://transconnect.sourceforge.net/ ) and this link:
http://www.itworld.com/AppDev/1006/UIR000929interposers/pfindex.html.
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Re: building libc

[Per Jessen]

Darío Mariani wrote:

> http://www.itworld.com/AppDev/1006/UIR000929interposers/pfindex.html.
> 

Yeah, this is exactly what I intend to try.  My problem is in
getaddrinfo() which has been misbehaving (for quite some time). The
glibc code was fixed by Ian Jackson in glibc 2.6.1 for ubuntu, so I
figured I'd just borrow that and stick the getaddrinfo() object-code
into a shared library which I'd preload with LD_PRELOAD.  Sounds simple,
doesn't it?

Well, building the glibc code was no big deal, but as for "just borrow
that", it's not easy.  If I build getaddrinfo.c outside the glibc build
structure, it throws about a million errors.  Option #1 is to attempt to
fix that, but with getaddrinfo.c being about 2000 lines, I'm a little
hesitant about that approach.
Option #2 (I think) is to use the object-code from the built glibc, but
when I try to use the shared library (containing just getaddrinfo.o), it
complains about unresolved symbols - e.g. __inet_ntoa.


/Per Jessen
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