Re: [gentoo-dev] init.d net scripts & Bash wierdness

[Stroller]

Many thanks to the list for the excellent help with my
/etc/init.d/net.br0 script.

I'm disproportionately proud of myself for implementing the list's
suggestions successfully. Many thanks to Sylvain for teaching me how to
traverse lists in Bash scripts. I'm sure my script could do with error
trapping (and a little tidying, see below), but I'm wondering if it would
be worth distributing something like this as part of the bridge-utils
ebuild. Is it worth me getting in touch with the maintainer..?


On Saturday, March 22, 2003, at 10:54  pm, Martin Schlemmer wrote:
> On Sat, 2003-03-22 at 23:35, Stroller wrote:
>
>> Unfortunately, for some reason my new script doesn't seem to read the
>> gateway="br0/192.168.1.1" line from the config.d file, and I can't
>> work
>> out why not. If I use my dumb script the gateway is allocated
>> correctly,
>> but not when I try to read parameters from file.
>
> My best bet from looking at it quickly, is that you still have
> 'gateway'
> set in /etc/conf.d/net.  If you look at /sbin/runscript.sh, you will
> see:
> ---------------------------------------------------------------- #
> Source configuration files.
> # (1) Source /etc/conf.d/basic to get common configuration.
> # (2) Source /etc/conf.d/${myservice} to get initscript-specific #
> configuration (if it exists).
> # (3) Source /etc/conf.d/net if it is a net.* service
> # (4) Source /etc/rc.conf to pick up potentially overriding
> #     configuration, if the system administrator chose to put it #
> there (if it exists).
>
> [ -e /etc/conf.d/basic ]                  && source /etc/conf.d/basic
>
> [ -e "/etc/conf.d/${myservice}" ]         && source
> "/etc/conf.d/${myservice}"
>
> [ -e /etc/conf.d/net ]                    && \
> [ "${myservice%%.*}" = "net" ]            && \
> [ "${myservice##*.}" != "${myservice}" ]  && source /etc/conf.d/net
>
> [ -e /etc/rc.conf ]                       && source /etc/rc.conf
> -----------------------------------------------------------------
>
> Thus, it sources your /etc/conf.d/net.br0, and then sources
> /etc/conf.d/net, which resets 'gateway' again, and makes the
> '[ "${gateway%/*}" = "${IFACE}" ]' bit always fail.
>
> As I see it, you have two simple choices (other than hacking
> things to pieces):
>
> 1)  Use something other than 'gateway' for the br0 script.
>
> 2)  Do not set gateway in /etc/conf.d/net

Well, I've hacked things to pieces    ;-]

Then I reread you posting, and I see how I could have done things
differently.

You see, I've done this:
   for gateway in ${gateways}
      do
      if [ -n "${gateway}" ] && [ "${gateway%/*}" = "${IFACE}" ]
        then
          ebegin "  Setting default gateway"
          /sbin/route add default gw ${gateway#*/} dev ${gateway%/*} \
                     netmask 0.0.0.0 metric 1 >/dev/null || {
                     local error=$?
                     ifconfig ${IFACE} down &>/dev/null
                     eend ${error} "Failed to bring ${IFACE} up"
                     stop
                     return ${error}
                 }
                 eend 0
       fi
       done

Then changed /etc/conf.d/net :
   # For setting the default gateway
   #gateway="eth0/192.168.1.1"
   #gateway="br0/192.168.1.1"
   # The above settings don't work, because Gentoo's init.d scripts will
   # only read the last default gateway entry hence this naffs up the
   # eth0 entry
   gateways="br0/192.168.1.1 eth0/192.168.1.1"

Now, as I understand it, it would probably be tidier if I had proceeded
differently:
- rename the standard /etc/conf.d/net to /etc/conf.d/net.eth0
- symlink that to /etc/conf.d/net.eth1
- create a new file called conf.d/net.br0 & put the `gateway="br0/...`
  line (and IP address &c for br0) in there.

That way the two  `gateway="ethX/...` lines can co-exist without
interfering with each other. I'll probably rearrange this shortly, as
that seems neater than rewriting Gentoo's default rc-srcipts & because
I want to diverge from the Gentoo out-of-the-box configuration as
little as possible.

Now, I can see (although I had to think about it) that init.d/net.*
files only read one default gateway for a Good Reason (tm). What I
don't understand is why not make the default configuration file to be
/etc/conf.d/net.eth0 in the first place..? Why have a /etc/conf.d/net
at all..?

As I understand it (someone will undoubtedly correct me if I'm wrong
B-] ), the naming convention of ethX is strictly arbitrary - you could
name your first interface as eth7. There's been some talk here recently
of folks having one network configuration for home, and another for
work: as I understand it you could have ethX & ethY as different
run-levels for the same physical network card, each with a different
set of settings in /etc/conf.d/. In this case the same problem would be
encountered as I have, and the user would have to configure
/etc/conf.d/net.ethX & /etc/conf.d/net.ethY and have no /etc/conf.d/net.

This probably sounds like I'm whinging because it took me a while to
figure it out: "it was a hassle for me, so you should change the whole
Gentoo distribution!" I don't mean it like that, but I'd be interested
to hear if there's a really good reason for having /etc/conf.d/net out
of the box, instead of /etc/conf.d/net.eth0. The default configuration
is slightly easier if you add a 2nd NIC & want to use both together on
different subnets (admittedly the common way), but users could easily
copy conf.d/net.eth0 to conf.d/net.eth1 & edit, the same as they copy
/init.d/net.eth0.

At present there aren't even any comments in the header to say that
conf.d/net overrides any conf.d/net.XXX scripts. Am I just being
dumb..? Should users know that the source lines in /sbin/runscript.sh
behave this way..?

Many thanks to anyone who can aid my understanding. Sorry for such a
long posting - I seem to have the -v flag permanently set.

Stroller.




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