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wgengine/filter: drop multicast packets out, don't log about them

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Eventually we'll probably support multicast. For now it's just log spam.

Fixes #629
This commit is contained in:
Brad Fitzpatrick 2020-09-25 11:06:48 -07:00
parent bbb56f2303
commit 5f807c389e
3 changed files with 24 additions and 0 deletions
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8
wgengine/filter/filter.go
View File

@ -367,6 +367,11 @@ func (f *Filter) pre(q *packet.ParsedPacket, rf RunFlags, dir direction) Respons
f.logRateLimit(rf, q, dir, Drop, "ipv6")
return Drop
}
if q.DstIP.IsMulticast() {
f.logRateLimit(rf, q, dir, Drop, "multicast")
return Drop
}
switch q.IPProto {
case packet.Unknown:
// Unknown packets are dangerous; always drop them.
@ -409,6 +414,9 @@ func omitDropLogging(p *packet.ParsedPacket, dir direction) bool {
if ipProto == packet.IGMP {
return true
}
if p.DstIP.IsMulticast() {
return true
}
case 6:
if len(b) < 40 {
return false

12
wgengine/filter/filter_test.go
View File

@ -379,6 +379,18 @@ func TestOmitDropLogging(t *testing.T) {
dir: out,
want: true,
},
{
name: "v6_multicast_out_low",
pkt: &packet.ParsedPacket{IPVersion: 4, DstIP: packet.NewIP(net.ParseIP("224.0.0.0"))},
dir: out,
want: true,
},
{
name: "v6_multicast_out_high",
pkt: &packet.ParsedPacket{IPVersion: 4, DstIP: packet.NewIP(net.ParseIP("239.255.255.255"))},
dir: out,
want: true,
},
}
for _, tt := range tests {

4
wgengine/packet/ip.go
View File

@ -39,6 +39,10 @@ func (ip IP) String() string {
return fmt.Sprintf("%d.%d.%d.%d", byte(ip>>24), byte(ip>>16), byte(ip>>8), byte(ip))
}
func (ip IP) IsMulticast() bool {
return byte(ip>>24)&0xf0 == 0xe0
}
// IPProto is either a real IP protocol (ITCP, UDP, ...) or an special value like Unknown.
// If it is a real IP protocol, its value corresponds to its IP protocol number.
type IPProto uint8