all: allow configuring default-routes as manual, static routes

Up until now, a default-route (with prefix length zero) could not
be configured directly. The user could only set ipv4.gateway,
ipv4.never-default, ipv4.route-metric and ipv4.route-table to influence
the setting of the default-route (respectively for IPv6).

That is a problematic limitation. For one, whether a route has prefix
length zero or non-zero does not make a fundamental difference. Also,
it makes it impossible to configure all the routing attributes that one can
configure otherwise for static routes. For example, the default-route could
not be configured as "onlink", could not have a special MTU, nor could it be
placed in a dedicated routing table.

Fix that by lifting the restriction. Note that "ipv4.never-default" does
not apply to /0 manual routes. Likewise, the previous manners of
configuring default-routes ("ipv4.gateway") don't conflict with manual
default-routes.

Server-side this all the pieces are already in place to accept a default-route
as static routes. This was done by earlier commits like 5c299454b49b
('core: rework tracking of gateway/default-route in ip-config').

A long time ago, NMIPRoute would assert that the prefix length is
positive. That was relaxed by commit a2e93f2de4ac ('libnm: allow zero
prefix length for NMIPRoute'), already before 1.0.0. Using libnm from
before 1.0.0 would result in assertion failures.

Note that the default-route-metric-penalty based on connectivity
checking applies to all /0 routes, even these static routes. Be they
added due to DHCP, "ipv4.gateway", "ipv4.routes" or "wireguard.peer-routes".
I wonder whether doing that unconditionally is desirable, and maybe
there should be a way to opt-out/opt-in for the entire profile or even
per-routes.

https://bugzilla.redhat.com/show_bug.cgi?id=1714438

1 files changed, 0 insertions, 2 deletions

diff --git a/src/nm-ip4-config.c b/src/nm-ip4-config.c
index 36e75bb2d2..4a620c9569 100644
--- a/src/nm-ip4-config.c
+++ b/src/nm-ip4-config.c
@@ -991,8 +991,6 @@ nm_ip4_config_merge_setting (NMIP4Config *self,
 
 		route.plen = nm_ip_route_get_prefix (s_route);
 		nm_assert (route.plen <= 32);
-		if (route.plen == 0)
-			continue;
 
 		nm_ip_route_get_next_hop_binary (s_route, &route.gateway);
 		if (nm_ip_route_get_metric (s_route) == -1)