From da3b50ad88d75693a80b1203075b531a5c89cdf1 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Sat, 1 Aug 2020 12:40:09 -0700
Subject: [PATCH] wgengine/filter: omit logging for all v6 multicast, remove
 debug panic :(

---
 wgengine/filter/filter.go      | 5 ++++-
 wgengine/filter/filter_test.go | 6 ++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/wgengine/filter/filter.go b/wgengine/filter/filter.go
index d9d721baf..4875b40c2 100644
--- a/wgengine/filter/filter.go
+++ b/wgengine/filter/filter.go
@@ -349,7 +349,10 @@ func omitDropLogging(p *packet.ParsedPacket, dir direction) bool {
 			if string(dst) == ipv6AllMLDv2CapableRouters {
 				return true
 			}
-			panic(fmt.Sprintf("Got proto=%2x; src=%x dst=%x", int(p.IPProto), src, dst))
+			// Actually, just catch all multicast.
+			if dst[0] == 0xff {
+				return true
+			}
 		}
 	}
 	return false
diff --git a/wgengine/filter/filter_test.go b/wgengine/filter/filter_test.go
index 5f8c64f67..c95f43897 100644
--- a/wgengine/filter/filter_test.go
+++ b/wgengine/filter/filter_test.go
@@ -343,6 +343,12 @@ func TestOmitDropLogging(t *testing.T) {
 			dir:  out,
 			want: true,
 		},
+		{
+			name: "v6_udp_multicast",
+			pkt:  parseHexPkt(t, "60 00 00 00 00 00 11 00  fe800000000000007dc6bc04499262a3 ff120000000000000000000000008384"),
+			dir:  out,
+			want: true,
+		},
 	}
 
 	for _, tt := range tests {