[OpenWrt-Devel] [PATCH] dnsmasq: prefer localuse over resolvfile guesswork

[Paul Oranje]

> Op 21 feb. 2019, om 04:52 heeft Yousong Zhou <yszhou4tech at gmail.com> het volgende geschreven:
> 
> This makes it clear that localuse when explicitly specified in the
> config will have its final say on whether or not the initscript should
> touch /etc/resolv.conf, no matter whatever the result of previous
> guesswork would be
> 
> Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
> ---
> package/network/services/dnsmasq/Makefile           | 2 +-
> package/network/services/dnsmasq/files/dnsmasq.init | 8 ++++----
> 2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/package/network/services/dnsmasq/Makefile b/package/network/services/dnsmasq/Makefile
> index d874296ea7..8c8427f6c1 100644
> --- a/package/network/services/dnsmasq/Makefile
> +++ b/package/network/services/dnsmasq/Makefile
> @@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
> PKG_NAME:=dnsmasq
> PKG_UPSTREAM_VERSION:=2.80
> PKG_VERSION:=$(subst test,~~test,$(subst rc,~rc,$(PKG_UPSTREAM_VERSION)))
> -PKG_RELEASE:=9
> +PKG_RELEASE:=10
> 
> PKG_SOURCE:=$(PKG_NAME)-$(PKG_UPSTREAM_VERSION).tar.xz
> PKG_SOURCE_URL:=http://thekelleys.org.uk/dnsmasq
> diff --git a/package/network/services/dnsmasq/files/dnsmasq.init b/package/network/services/dnsmasq/files/dnsmasq.init
> index f65736e268..4ae71e438b 100644
> --- a/package/network/services/dnsmasq/files/dnsmasq.init
> +++ b/package/network/services/dnsmasq/files/dnsmasq.init
> @@ -733,7 +733,7 @@ dnsmasq_start()
> {
> 	local cfg="$1"
> 	local disabled user_dhcpscript
> -	local resolvfile localuse
> +	local resolvfile localuse=0
> 
> 	config_get_bool disabled "$cfg" disabled 0
> 	[ "$disabled" -gt 0 ] && return 0
> @@ -884,13 +884,13 @@ dnsmasq_start()
> 	config_get_bool cachelocal "$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
> 		[ -n "$resolvfile" -a ! -e "$resolvfile" ] && touch "$resolvfile"
> 		xappend "--resolv-file=$resolvfile"
> 		[ "$resolvfile" = "/tmp/resolv.conf.auto" ] && localuse=1
> 	fi
> +	config_get_bool localuse "$cfg" localuse "$localuse"
> 
> 	config_get hostsfile "$cfg" dhcphostsfile
> 	[ -e "$hostsfile" ] && xappend "--dhcp-hostsfile=$hostsfile"
> @@ -1040,13 +1040,13 @@ dnsmasq_start()
> dnsmasq_stop()
> {
> 	local cfg="$1"
> -	local noresolv resolvfile localuse
> +	local noresolv resolvfile localuse=0
> 
> 	config_get_bool noresolv "$cfg" noresolv 0
> -	config_get_bool localuse "$cfg" localuse 0
> 	config_get resolvfile "$cfg" "resolvfile"
> 
> 	[ "$noresolv" = 0 -a "$resolvfile" = "/tmp/resolv.conf.auto" ] && localuse=1
> +	config_get_bool localuse "$cfg" localuse "$localuse"
> 	[ "$localuse" -gt 0 ] && ln -sf "/tmp/resolv.conf.auto" /tmp/resolv.conf
> 
> 	rm -f ${BASEDHCPSTAMPFILE}.${cfg}.*.dhcp
> 
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Tested this patch (8f16fba501) and the previous patch (ec2a2a2aea) on top of 18.06.2.

The patches apply cleanly and the patched file works as expected:

- localuse=1 and noresolv and resolvfile not set => dnsmasq writes resolv.conf 
- localuse and noresolv and resolvfile not set => dnsmasq writes resolv.conf
- localuse=0 and noresolv and resolvfile not set => dnsmasq leaves resolv.conf untouched
- localuse not set and noresolv=1 and resolvfile='/tmp/resolv.conf.auto' => dnsmasq leaves resolv.conf untouched.

The latter two scenario's work well with Unbound (where dnsmasq handles DHCP and DNS of lan host names).
Thanks.

Tested-by: Paul Oranje <por at oranjevos.nl>

Sitenotes:
Would also writing "nameserver ::1" to resolv.conf be a good idea ? (Unbound does)
When dnsmasq does not listen on port 53, then it cannot serve as the nameserver for the localhost (resolv.conf does not allow specifying a port) unless some clever DNAT rule is in place.


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