netbird/client/internal/routemanager/systemops_bsd.go
Viktor Liu 2475473227
Support client default routes for Linux (#1667)
All routes are now installed in a custom netbird routing table.
Management and wireguard traffic is now marked with a custom fwmark.
When the mark is present the traffic is routed via the main routing table, bypassing the VPN.
When the mark is absent the traffic is routed via the netbird routing table, if:
- there's no match in the main routing table
- it would match the default route in the routing table

IPv6 traffic is blocked when a default route IPv4 route is configured to avoid leakage.
2024-03-21 16:49:28 +01:00

93 lines
1.9 KiB
Go

//go:build darwin || dragonfly || freebsd || netbsd || openbsd
package routemanager
import (
"fmt"
"net"
"net/netip"
"syscall"
"golang.org/x/net/route"
)
// selected BSD Route flags.
const (
RTF_UP = 0x1
RTF_GATEWAY = 0x2
RTF_HOST = 0x4
RTF_REJECT = 0x8
RTF_DYNAMIC = 0x10
RTF_MODIFIED = 0x20
RTF_STATIC = 0x800
RTF_BLACKHOLE = 0x1000
RTF_LOCAL = 0x200000
RTF_BROADCAST = 0x400000
RTF_MULTICAST = 0x800000
)
func getRoutesFromTable() ([]netip.Prefix, error) {
tab, err := route.FetchRIB(syscall.AF_UNSPEC, route.RIBTypeRoute, 0)
if err != nil {
return nil, err
}
msgs, err := route.ParseRIB(route.RIBTypeRoute, tab)
if err != nil {
return nil, err
}
var prefixList []netip.Prefix
for _, msg := range msgs {
m := msg.(*route.RouteMessage)
if m.Version < 3 || m.Version > 5 {
return nil, fmt.Errorf("unexpected RIB message version: %d", m.Version)
}
if m.Type != 4 /* RTM_GET */ {
return nil, fmt.Errorf("unexpected RIB message type: %d", m.Type)
}
if m.Flags&RTF_UP == 0 ||
m.Flags&(RTF_REJECT|RTF_BLACKHOLE) != 0 {
continue
}
addr, ok := toNetIPAddr(m.Addrs[0])
if !ok {
continue
}
mask, ok := toNetIPMASK(m.Addrs[2])
if !ok {
continue
}
cidr, _ := mask.Size()
routePrefix := netip.PrefixFrom(addr, cidr)
if routePrefix.IsValid() {
prefixList = append(prefixList, routePrefix)
}
}
return prefixList, nil
}
func toNetIPAddr(a route.Addr) (netip.Addr, bool) {
switch t := a.(type) {
case *route.Inet4Addr:
ip := net.IPv4(t.IP[0], t.IP[1], t.IP[2], t.IP[3])
addr := netip.MustParseAddr(ip.String())
return addr, true
default:
return netip.Addr{}, false
}
}
func toNetIPMASK(a route.Addr) (net.IPMask, bool) {
switch t := a.(type) {
case *route.Inet4Addr:
mask := net.IPv4Mask(t.IP[0], t.IP[1], t.IP[2], t.IP[3])
return mask, true
default:
return nil, false
}
}