netcheck: STUN less aggressively to known distant servers

If Australia's far away and not going to be used, it's still going to be far away a minute later. No need to send backup just-in-case-UDP-gets-lost STUN packets to the known far away destinations. Those are the ones most likely to trigger retries due to delay anyway (in random 50-250ms, currently). But we'll keep sending 1 packet to them, just in case our airplane landed. Likewise, be less aggressive with IPv6. The main point is just to see whether IPv6 works. No need to send up to 10 packets every round. Max two is enough (except for the first round). This does mean our STUN traffic graphs for IPv4-vs-IPv6 will change shape. Oh well. It was a weird eyeball metric for IPv6 connectivity anyway and we have better metrics. We can tweak this policy over time. It's factored out and has tests now.
2020-05-04 23:22:19 -07:00
parent 828aa6dcb0
commit 44b07aa708
2 changed files with 161 additions and 18 deletions
--- a/netcheck/netcheck_test.go
+++ b/netcheck/netcheck_test.go
@ -211,3 +211,82 @@ func TestAddReportHistoryAndSetPreferredDERP(t *testing.T) {
 		})
 	}
 }
+
+func TestPickSubset(t *testing.T) {
+	derps := derpmap.NewTestWorldWith(
+		&derpmap.Server{
+			ID:    1,
+			STUN4: "d1:4",
+			STUN6: "d1:6",
+		},
+		&derpmap.Server{
+			ID:    2,
+			STUN4: "d2:4",
+			STUN6: "d2:6",
+		},
+		&derpmap.Server{
+			ID:    3,
+			STUN4: "d3:4",
+			STUN6: "d3:6",
+		},
+	)
+	tests := []struct {
+		name      string
+		last      *Report
+		want4     []string
+		want6     []string
+		wantTries map[string]int
+	}{
+		{
+			name:  "fresh",
+			last:  nil,
+			want4: []string{"d1:4", "d2:4", "d3:4"},
+			want6: []string{"d1:6", "d2:6", "d3:6"},
+			wantTries: map[string]int{
+				"d1:4": 2,
+				"d2:4": 2,
+				"d3:4": 2,
+				"d1:6": 1,
+				"d2:6": 1,
+				"d3:6": 1,
+			},
+		},
+		{
+			name: "1_and_3_closest",
+			last: &Report{
+				DERPLatency: map[string]time.Duration{
+					"d1:4": 15 * time.Millisecond,
+					"d2:4": 300 * time.Millisecond,
+					"d3:4": 25 * time.Millisecond,
+				},
+			},
+			want4: []string{"d1:4", "d2:4", "d3:4"},
+			want6: []string{"d1:6", "d3:6"},
+			wantTries: map[string]int{
+				"d1:4": 2,
+				"d3:4": 2,
+				"d2:4": 1,
+				"d1:6": 1,
+				"d3:6": 1,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := &Client{DERP: derps, last: tt.last}
+			got4, got6, gotTries, err := c.pickSubset()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !reflect.DeepEqual(got4, tt.want4) {
+				t.Errorf("stuns4 = %q; want %q", got4, tt.want4)
+			}
+			if !reflect.DeepEqual(got6, tt.want6) {
+				t.Errorf("stuns6 = %q; want %q", got6, tt.want6)
+			}
+			if !reflect.DeepEqual(gotTries, tt.wantTries) {
+				t.Errorf("tries = %v; want %v", gotTries, tt.wantTries)
+			}
+		})
+	}
+}