[LEDE-DEV] netifd: l2tp connections no longer working

[Alin Năstac]

Hi Felix,

A setup using an l2tp interface that connects to an on-link L2TP
server stopped working after cherry picking this netifd commit:
    author    Felix Fietkau <nbd at nbd.name>
    Thu, 8 Mar 2018 00:14:57 +0200 (23:14 +0100)
    commit    1f5a29c3de6e3fec5883796ee772e25d56db6a69
    ip: do not add local routes for host dependencies

    This avoids creating invalid routes in cases where another daemon is
    handling local routes for an interface, e.g. on mesh interfaces

I've found that l2tp connection fails to start in 2 different
scenarios. In both cases the IP addresses and routes are configured
entirely through netifd.

1) l2tp server is reachable through wan interface, configured as follows:
uci set network.wan.proto=dhcp
uci set network.wan.ifname=eth4
uci set network.wan.reqopts='1 33 121'
uci set network.wan.iface6rd='0'
uci set network.wan.release='1'
uci set network.wan.metric=10
uci set network.wan.ipv6='0'
uci set network.l2tp=interface
uci set network.l2tp.proto='l2tp'
uci set network.l2tp.server='l2tp.domain.com'
uci set network.l2tp.username='qacafe'
uci set network.l2tp.password='qacafe123'
uci set network.l2tp.checkup_interval='20'
In this case CDROUTER host connected to the wan interface play roles
of DHCP, DNS and L2TP server.

2) l2tp server is reachable through the lan interface:
uci set network.lan=interface
uci set network.lan.type='bridge'
uci set network.lan.proto='static'
uci set network.lan.ipaddr='192.168.1.1'
uci set network.lan.netmask='255.255.255.0'
uci set network.lan.ifname='eth0 eth1 eth2 eth3'
uci set network.l2tp=interface
uci set network.l2tp.proto='l2tp'
uci set network.l2tp.server='192.168.1.10'
uci set network.l2tp.username='qacafe'
uci set network.l2tp.password='qacafe123'
uci set network.l2tp.checkup_interval='20'