[OpenWrt-Devel] [PATCH v2] dnsmasq: allow using dnsmasq as the sole resolver

[Hans Dedecker]

On Mon, Feb 18, 2019 at 3:18 PM Yousong Zhou <yszhou4tech at gmail.com> wrote:
>
> Currently it seems impossible to configure /etc/config/dhcp to achieve
> the following use case
>
>  - run dnsmasq with no-resolv
>  - re-generate /etc/resolv.conf with "nameserver 127.0.0.1"
>
> Before this change, we have to set resolvfile to /tmp/resolv.conf.auto
> to achive the 2nd effect above, but setting resolvfile requires noresolv
> being false.
>
> A new boolean option "localuse" is added to indicate that we intend to
> use dnsmasq as the local dns resolver.  It's false by default and to
> align with old behaviour it will be true automatically if resolvfile is
> set to /tmp/resolv.conf.auto
>
> Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
Acked-by: Hans Dedecker <dedeckeh at gmail.com>
> ---
> v2 <- v1
>
>  - retain /tmp/resolv.conf.auto as the default value of resolvfile when
>    doing config_get, i.e. 2nd patch in the 1st version is now dropped
>  - retain the old behavior of rewriting /tmp/resolv.conf when resolvfile
>    is /tmp/resolv.conf.auto
>
>  .../services/dnsmasq/files/dnsmasq.init       | 30 +++++++++----------
>  1 file changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/package/network/services/dnsmasq/files/dnsmasq.init b/package/network/services/dnsmasq/files/dnsmasq.init
> index f3066627d6..f65736e268 100644
> --- a/package/network/services/dnsmasq/files/dnsmasq.init
> +++ b/package/network/services/dnsmasq/files/dnsmasq.init
> @@ -731,7 +731,9 @@ dhcp_relay_add() {
>
>  dnsmasq_start()
>  {
> -       local cfg="$1" disabled resolvfile user_dhcpscript
> +       local cfg="$1"
> +       local disabled user_dhcpscript
> +       local resolvfile localuse
>
>         config_get_bool disabled "$cfg" disabled 0
>         [ "$disabled" -gt 0 ] && return 0
> @@ -882,14 +884,14 @@ dnsmasq_start()
>         config_get_bool cachelocal "$cfg" cachelocal 1
>
>         config_get_bool noresolv "$cfg" noresolv 0
> +       config_get_bool localuse "$cfg" localuse 0
>         if [ "$noresolv" != "1" ]; then
> -               config_get resolvfile "$cfg" resolvfile "/tmp/resolv.conf.auto"
> -               # So jail doesn't complain if file missing
> -               [ -n "$resolvfile" -a \! -e "$resolvfile" ] && touch "$resolvfile"
> +               config_get resolvfile "$cfg" resolvfile /tmp/resolv.conf.auto
> +               [ -n "$resolvfile" -a ! -e "$resolvfile" ] && touch "$resolvfile"
> +               xappend "--resolv-file=$resolvfile"
> +               [ "$resolvfile" = "/tmp/resolv.conf.auto" ] && localuse=1
>         fi
>
> -       [ -n "$resolvfile" ] && xappend "--resolv-file=$resolvfile"
> -
>         config_get hostsfile "$cfg" dhcphostsfile
>         [ -e "$hostsfile" ] && xappend "--dhcp-hostsfile=$hostsfile"
>
> @@ -1011,7 +1013,7 @@ dnsmasq_start()
>         mv -f $CONFIGFILE_TMP $CONFIGFILE
>         mv -f $HOSTFILE_TMP $HOSTFILE
>
> -       [ "$resolvfile" = "/tmp/resolv.conf.auto" ] && {
> +       [ "$localuse" -gt 0 ] && {
>                 rm -f /tmp/resolv.conf
>                 [ $ADD_LOCAL_DOMAIN -eq 1 ] && [ -n "$DOMAIN" ] && {
>                         echo "search $DOMAIN" >> /tmp/resolv.conf
> @@ -1037,17 +1039,15 @@ dnsmasq_start()
>
>  dnsmasq_stop()
>  {
> -       local cfg="$1" resolvfile
> +       local cfg="$1"
> +       local noresolv resolvfile localuse
>
> +       config_get_bool noresolv "$cfg" noresolv 0
> +       config_get_bool localuse "$cfg" localuse 0
>         config_get resolvfile "$cfg" "resolvfile"
>
> -       #relink /tmp/resolve.conf only for main instance
> -       [ "$resolvfile" = "/tmp/resolv.conf.auto" ] && {
> -               [ -f /tmp/resolv.conf ] && {
> -                       rm -f /tmp/resolv.conf
> -                       ln -s "$resolvfile" /tmp/resolv.conf
> -               }
> -       }
> +       [ "$noresolv" = 0 -a "$resolvfile" = "/tmp/resolv.conf.auto" ] && localuse=1
> +       [ "$localuse" -gt 0 ] && ln -sf "/tmp/resolv.conf.auto" /tmp/resolv.conf
>
>         rm -f ${BASEDHCPSTAMPFILE}.${cfg}.*.dhcp
>  }

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