dnsmasq: prevent upstream resolution of addresses

`list address` entries in /etc/config/dhcp are sometimes (I'm not sure
about the exact conditions) passed to upstream resolver, bypassing local
resolution. Adding them (minus the IP) to --local prevents this. In the
configuration, this means that

    # /etc/config/dhcp
    list address '/hello.com/world.com/1.2.3.4'
    list address '/foo.com/bar.com/4.3.2.1'

which previously translated into

    # /var/etc/dnsmasq.conf.*
    address=/hello.com/world.com/1.2.3.4
    address=/foo.com/bar.com/4.3.2.1

now becomes

    # /var/etc/dnsmasq.conf.*
    address=/hello.com/world.com/1.2.3.4
    local=/hello.com/world.com/
    address=/foo.com/bar.com/4.3.2.1
    local=/foo.com/bar.com/

This behaviour is controlled by the `address_as_local` boolean option, which
defaults to false (old behaviour). openwrt/luci#7957 adds support for this flag
to LuCI.

A workaround for a small list of domains is to add them to `option local`,
but this is very tedious to do for every `list address` entry and dnsmasq
limits this option to 1024 characters.

Signed-off-by: Marko Zajc <marko@zajc.tel>
Link: https://github.com/openwrt/openwrt/pull/18610
Signed-off-by: Robert Marko <robimarko@gmail.com>

diff --git a/package/network/services/dnsmasq/files/dnsmasq.init b/package/network/services/dnsmasq/files/dnsmasq.init
index a0a644fcbd8d33ee4940689705aca6521c20cc14..61dc3967070cc733c70e6bd09e270e04b73b02c9 100755 (executable)
--- a/package/network/services/dnsmasq/files/dnsmasq.init
+++ b/package/network/services/dnsmasq/files/dnsmasq.init
@@ -170,7 +170,9 @@ append_rev_server() {
 }
 
 append_address() {
+       local address_as_local="$2"
        xappend "--address=$1"
+       [ $address_as_local -gt 0 ] && xappend "--local=${1%/*}/"
 }
 
 append_connmark_allowlist() {
@@ -1036,7 +1038,10 @@ dnsmasq_start()
        config_list_foreach "$cfg" "listen_address" append_listenaddress
        config_list_foreach "$cfg" "server" append_server
        config_list_foreach "$cfg" "rev_server" append_rev_server
-       config_list_foreach "$cfg" "address" append_address
+
+       local address_as_local
+       config_get address_as_local "$cfg" address_as_local 0
+       config_list_foreach "$cfg" "address" append_address "$address_as_local"
 
        local connmark_allowlist_enable
        config_get connmark_allowlist_enable "$cfg" connmark_allowlist_enable 0