[改进建议]将dnsmasq修改值保存在mosdns配置文件中，停止mosdns服务时可以恢复dnsmasq设置

[JIZHENQIANG]

1.看了一下初始化文件/etc/init.d/mosdns，现在是直接设置值，并且停止服务时重绑定保护rebind_protection没有恢复。

restore_setting() {
	rm -f /etc/mosdns/redirect.lock
	sed -i "/list server/d" /etc/config/dhcp
	uci set dhcp.@dnsmasq[0].noresolv='0'
	uci del dhcp.@dnsmasq[0].cachesize
	uci commit dhcp
}

redirect_setting() {
	if [ "${CONF}" = "/var/etc/mosdns.json" ]; then
		sed -i "/list server/d" /etc/config/dhcp
		uci add_list dhcp.@dnsmasq[0].server="127.0.0.1#$listen_port"
		uci set dhcp.@dnsmasq[0].rebind_protection='0'
		uci set dhcp.@dnsmasq[0].noresolv="1"
		uci set dhcp.@dnsmasq[0].cachesize='0'
		uci commit dhcp
	else
		sed -i "/list server/d" /etc/config/dhcp
		uci add_list dhcp.@dnsmasq[0].server="127.0.0.1#$(awk -F'[:" ]+' '/^\s+listen:/{for(i=1;i<=NF;i++){if($i~/^[0-9]+$/){print $i;exit}}}' $CONF)"
		uci set dhcp.@dnsmasq[0].rebind_protection='0'
		uci set dhcp.@dnsmasq[0].noresolv="1"
		uci set dhcp.@dnsmasq[0].cachesize='0'
		uci commit dhcp
	fi
	touch /etc/mosdns/redirect.lock
}

2.不同的openwrt的dnsmasq默认值也不同，想要停止mosdns时恢复默认值就需要先将需要修改的默认值保存在配置文件中。新增两个函数save_dnsmasq_server、set_dnsmasq_server修改了restore_setting和redirect_setting两个函数中的逻辑，其余无修改。

save_dnsmasq_server() {
	if [ -z "$1" ] || [ "$1" = "127.0.0.1#$listen_port" ]; then
		return 0
	fi
	uci -q add_list mosdns.config.dnsmasq_server="$1"
}

set_dnsmasq_server() {
	if [ -z "$1" ] || [ "$1" = "127.0.0.1#$listen_port" ]; then
		return 0
	fi
	uci -q add_list dhcp.@dnsmasq[0].server="$1"
}

restore_setting() {
	rm -f /etc/mosdns/redirect.lock
	uci -q del dhcp.@dnsmasq[-1].server
	config_load "mosdns"
	config_list_foreach "config" "dnsmasq_server" set_dnsmasq_server
	if [ -z "$(uci -q get mosdns.config.dnsmasq_rebind_protection)" ]; then
		uci -q del dhcp.@dnsmasq[0].rebind_protection
	else
		uci -q set dhcp.@dnsmasq[0].rebind_protection="$(uci -q get mosdns.config.dnsmasq_rebind_protection)"
	fi
	if [ -z "$(uci -q get mosdns.config.dnsmasq_noresolv)" ]; then
		uci -q del dhcp.@dnsmasq[0].noresolv
	else
		uci -q set dhcp.@dnsmasq[0].noresolv="$(uci -q get mosdns.config.dnsmasq_noresolv)"
	fi
	if [ -z "$(uci -q get mosdns.config.dnsmasq_cachesize)" ]; then
		uci -q del dhcp.@dnsmasq[0].cachesize
	else
		uci -q set dhcp.@dnsmasq[0].cachesize="$(uci -q get mosdns.config.dnsmasq_cachesize)"
	fi
	uci -q del mosdns.config.dnsmasq_server
	uci -q del mosdns.config.dnsmasq_rebind_protection
	uci -q del mosdns.config.dnsmasq_noresolv
	uci -q del mosdns.config.dnsmasq_cachesize
	uci -q commit dhcp && uci -q commit mosdns
}

redirect_setting() {
	if [ "${CONF}" = "/var/etc/mosdns.json" ]; then
		config_load "dhcp"
		config_list_foreach "$(uci -q show dhcp.@dnsmasq[0].server |awk -F '.' '{print $2}')" "server" save_dnsmasq_server
		uci -q set mosdns.config.dnsmasq_rebind_protection="$(uci -q get dhcp.@dnsmasq[0].rebind_protection)"
		uci -q set mosdns.config.dnsmasq_noresolv="$(uci -q get dhcp.@dnsmasq[0].noresolv)"
		uci -q set mosdns.config.dnsmasq_cachesize="$(uci -q get dhcp.@dnsmasq[0].cachesize)"
		uci -q del dhcp.@dnsmasq[-1].server
		uci -q add_list dhcp.@dnsmasq[0].server="127.0.0.1#$listen_port"
		uci -q set dhcp.@dnsmasq[0].rebind_protection='0'
		uci -q set dhcp.@dnsmasq[0].noresolv="1"
		uci -q set dhcp.@dnsmasq[0].cachesize='0'
		uci -q commit dhcp && uci -q commit mosdns
	else
		config_load "dhcp"
		config_list_foreach "$(uci -q show dhcp.@dnsmasq[0].server |awk -F '.' '{print $2}')" "server" save_dnsmasq_server
		uci -q set mosdns.config.dnsmasq_rebind_protection="$(uci -q get dhcp.@dnsmasq[0].rebind_protection)"
		uci -q set mosdns.config.dnsmasq_noresolv="$(uci -q get dhcp.@dnsmasq[0].noresolv)"
		uci -q set mosdns.config.dnsmasq_cachesize="$(uci -q get dhcp.@dnsmasq[0].cachesize)"
		uci -q del dhcp.@dnsmasq[-1].server
		uci -q add_list dhcp.@dnsmasq[0].server="127.0.0.1#$(awk -F'[:" ]+' '/^\s+listen:/{for(i=1;i<=NF;i++){if($i~/^[0-9]+$/){print $i;exit}}}' $CONF)"
		uci -q set dhcp.@dnsmasq[0].rebind_protection='0'
		uci -q set dhcp.@dnsmasq[0].noresolv="1"
		uci -q set dhcp.@dnsmasq[0].cachesize='0'
		uci -q commit dhcp && uci -q commit mosdns
	fi
	touch /etc/mosdns/redirect.lock
}

3.这样修改后dnsmasq被修改的默认值在停止mosdns服务时可以恢复。这是参考了openclash中对dnsmasq的处理，这样可以适配更多不同的openwrt版本。
4.处理逻辑时发现了一个问题。如果设备突然断电重启后会执行redirect_setting，但是这时dnsmasq中的server处于被修改的状态，redirect_setting函数中会将被修改的dnsmasq存储到mosdns配置文件中，这就会导致原本dnsmasq的设置会丢失。为了解决这个问题在有执行redirect_setting函数的地方前先执行restore_setting。查找发现现在只有start_service函数22行中有执行一次redirect_setting

[ "$redirect" -eq 1 ] && redirect_setting

将其修改为

	if [ "$redirect" -eq 1 ]; then
		if [ -f "/etc/mosdns/redirect.lock" ]; then
			restore_setting && redirect_setting
		else
			redirect_setting
		fi
	fi

这里使用if判断[ -f "/etc/mosdns/redirect.lock" ]而不直接使用[ "$redirect" -eq 1 ] && restore_setting && redirect_setting的原因是防止手动停止后再启动时执行restore_setting ，这样会导致修改的dnsmasq会被还原成mosdns配置文件保存的值。
5.我自己使用时每次都会修改此文件，达到想使用的效果。这次分享出来是希望作者可以并入此项目中，代码如果有可以改进的地方还请指正。
6.题外，懒得再提交一个issue。文件/usr/share/mosdns/mosdns.sh，此文件中的v2dat_dump函数18和19行

        # custom config
        v2dat unpack geoip -o /var/mosdns -f cn $v2dat_dir/geoip.dat
        v2dat unpack geosite -o /var/mosdns -f cn -f 'geolocation-!cn' $v2dat_dir/geosite.dat

使用自定义配置的时候v2dat还是默认生成geoip_cn、geosite_cn、geosite_geolocation-!cn这三个文件，感觉不是很合理，可以删除这两行。因为此项目有geodata导出功能，使用自定义配置时需要哪些导出哪些就行了，再默认生成有可能用不到，有点损失性能。