Count traffic per client address and report the busiest ones with the port totals

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

traffic_test.go

@@ -0,0 +1,55 @@
+package blacktip
+
+import "testing"
+
+func TestClientIP(t *testing.T) {
+	for in, want := range map[string]string{
+		"203.0.113.9:5000":     "203.0.113.9",
+		"[2001:db8::1]:443":    "2001:db8::1",
+		"[::ffff:192.0.2.7]:1": "192.0.2.7",
+		"198.51.100.2":         "198.51.100.2", // no port, as Traefik reports it
+		"[fe80::1%eth0]:80":    "fe80::1",
+		"not an address":       "",
+		"":                     "",
+	} {
+		if got := clientIP(in); got != want {
+			t.Errorf("clientIP(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+func TestStatsTakeAndRestore(t *testing.T) {
+	ms := &mapState{}
+	ms.record("203.0.113.1:1000", 1, 100, 400)
+	ms.record("203.0.113.1:1001", 1, 10, 40)
+	ms.record("203.0.113.2:2000", 1, 5, 5)
+	ms.record("garbage", 1, 1, 1) // counted in the totals but not named
+
+	st, any := ms.takeStats()
+	if !any || st.Conns != 4 || st.BytesIn != 116 || st.BytesOut != 446 {
+		t.Fatalf("totals: %+v", st)
+	}
+	if len(st.Sources) != 2 || st.Sources[0].IP != "203.0.113.1" || st.Sources[0].Conns != 2 || st.Sources[0].BytesOut != 440 {
+		t.Fatalf("sources: %+v", st.Sources)
+	}
+	if _, any := ms.takeStats(); any {
+		t.Fatal("counters were not reset")
+	}
+
+	ms.record("203.0.113.1:1", 1, 1, 1) // traffic that arrived before the failed report was retried
+	ms.restoreStats(st)
+	again, _ := ms.takeStats()
+	if again.Conns != 5 || again.BytesIn != 117 || again.Sources[0].Conns != 3 {
+		t.Fatalf("after restore: %+v", again)
+	}
+}
+
+func TestSourceTableIsBounded(t *testing.T) {
+	var tb sourceTable
+	for i := 0; i < maxTrackedSources+50; i++ {
+		tb.add(string(rune('a'+i%26))+"."+string(rune('0'+i/26%10))+"."+string(rune(i)), 1, 1, 1)
+	}
+	if n := len(tb.take()); n > maxTrackedSources {
+		t.Fatalf("tracked %d addresses", n)
+	}
+}