Re: [CFR] reflect resolv.conf update to running application

From: Doug Barton (dougb_at_FreeBSD.org)
Date: 09/15/05

  • Next message: Matthew N. Dodd: "Re: [CFR] reflect resolv.conf update to running application" 
    Date: Thu, 15 Sep 2005 01:32:09 -0700
To: "Matthew N. Dodd" <mdodd@FreeBSD.ORG>

    Matthew N. Dodd wrote:
    > On Thu, 8 Sep 2005, Brooks Davis wrote:
    >
    >> I've looked this over and while I like the concept, I think the
    >> implementation could be improved. First, it looks like named.conf has
    >> an include directive what is conveniently undocumented in the manpage,
    >> but in the BIND 9 Administrator Reference Manual at:
    >>
    >> http://www.bind9.net/manual/bind/9.3.1/Bv9ARM.ch06.html#AEN1534
    >>
    >> so if it actually works, we should use that instead of rebuiling the
    >> config file each time.

    Yes, include works, but it runs a similar risk to modifying the named.conf
    file, namely if the syntax of the the statements in the include file are not
      right, loading named.conf will fail. So, we should build some caution into
    the process of updating the file, but that's easily done with the
    named-checkconf program that comes with the distribution.

    >> Second, the forwarders file should default to
    >> living in the /var/run of the named chroot since we default to chrooted
    >> operation these day.

    chroot good, yes. :) I'm not sure exactly where the forwarders file should
    live though. I'm leaning towards (the chrooted) /etc/namedb, but I need to
    think about it a little more.

    >> Third, I think we need to kick the server with
    >> "rndc reconfig" once the file is updated.

    Yeah, but we need to work in the test of the new conf file first, as above.

    > Attached.

    Matthew, this is great stuff, thanks! A few comments.

    > + rm -f ${dhclient_script_forwarders_file}.$$
    > + echo " forward only;" > ${dhclient_script_forwarders_file}.$$

    This should really be 'forward first'. That configuration is less likely to
    fail in weird, and hard to diagnose ways. This is wrong in the default
    named.conf file, but it's not enabled by default, and I need to change that.

    > + mv ${dhclient_script_forwarders_file}.$$ ${dhclient_script_forwarders_file}

    This isn't perfect, but something like:

    if [ -f "${dhclient_script_forwarders_file}" ]; then
            if named-checkconf /etc/namedb/named.conf; then
                    rm ${dhclient_script_forwarders_file}. old
                    mv ${dhclient_script_forwarders_file} \
                        ${dhclient_script_forwarders_file}.old &&
                    mv ${dhclient_script_forwarders_file}.$$ \
                        ${dhclient_script_forwarders_file}
                    if named-checkconf /etc/namedb/named.conf; then
                            rm ${dhclient_script_forwarders_file}.old
                    else
                            mv ${dhclient_script_forwarders_file}.old \
                                ${dhclient_script_forwarders_file}
                    fi
            else
                    mv ${dhclient_script_forwarders_file}.$$ \
                        ${dhclient_script_forwarders_file}
            fi
    else
            mv ${dhclient_script_forwarders_file}.$$ \
                ${dhclient_script_forwarders_file}
    fi

    if named-checkconf /etc/namedb/named.conf; then
            rndc reconfig
    fi

    hth,

    Doug 

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