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wgengine/router: fix Windows route sorting that caused de-dup to not work (#727)

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Updates #725

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
2020-09-01 13:24:58 -07:00
committed by GitHub
parent 74ee374667
commit 09d56f54a7
2 changed files with 120 additions and 9 deletions
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32
wgengine/router/ifconfig_windows.go
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@@ -315,15 +315,7 @@ func configureInterface(cfg *Config, tun *tun.NativeTun) error {
return err
}
sort.Slice(routes, func(i, j int) bool {
return (bytes.Compare(routes[i].Destination.IP, routes[j].Destination.IP) == -1 ||
// Narrower masks first
bytes.Compare(routes[i].Destination.Mask, routes[j].Destination.Mask) == 1 ||
// No nexthop before non-empty nexthop
bytes.Compare(routes[i].NextHop, routes[j].NextHop) == -1 ||
// Lower metrics first
routes[i].Metric < routes[j].Metric)
})
sort.Slice(routes, func(i, j int) bool { return routeLess(&routes[i], &routes[j]) })
deduplicatedRoutes := []*winipcfg.RouteData{}
for i := 0; i < len(routes); i++ {
@@ -387,3 +379,25 @@ func configureInterface(cfg *Config, tun *tun.NativeTun) error {
return errAcc
}
// routeLess reports whether ri should sort before rj.
// The actual sort order doesn't appear to matter. The caller just
// wants them sorted to be able to de-dup.
func routeLess(ri, rj *winipcfg.RouteData) bool {
if v := bytes.Compare(ri.Destination.IP, rj.Destination.IP); v != 0 {
return v == -1
}
if v := bytes.Compare(ri.Destination.Mask, rj.Destination.Mask); v != 0 {
// Narrower masks first
return v == 1
}
if ri.Metric != rj.Metric {
// Lower metrics first
return ri.Metric < rj.Metric
}
if v := bytes.Compare(ri.NextHop, rj.NextHop); v != 0 {
// No nexthop before non-empty nexthop.
return v == -1
}
return false
}