Pull request 2027: 6233-ipset-cached-entries

Updates #6233.

Squashed commit of the following:

commit ef7692fb78a287a51a6b50c4ac0f1c33857a9ff0
Merge: b3ef5de41 8b6c260de
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Oct 9 13:07:10 2023 +0300

    Merge branch 'master' into 6233-ipset-cached-entries

commit b3ef5de411d2ebb2f344430daf81e05a33ae4e78
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Mon Oct 9 13:06:23 2023 +0300

    all: fix typo

commit d42a970336d1d7e8a2f7c8459bf862762cdac8f6
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Fri Oct 6 19:26:51 2023 +0300

    all: imp chlog

commit 818931a136c7b851820f8ff8e05ada5360da2090
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Fri Oct 6 18:30:52 2023 +0300

    all: upd chlog

commit af3dc60c038f04690882eca30a6f9c7d23f7c371
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Fri Oct 6 18:03:01 2023 +0300

    ipset: imp docs

commit 2c9d6c0c88ba2c2185b4d29212272ad5d48ae474
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Fri Oct 6 16:53:42 2023 +0300

    all: add tests

commit 0d41eaabf7a275c6a9eb4a1d64aa551d4d8de367
Author: Stanislav Chzhen <s.chzhen@adguard.com>
Date:   Fri Oct 6 15:12:54 2023 +0300

    ipset: rm cache

internal/dnsforward/ipset_internal_test.go

@@ -114,3 +114,74 @@ func TestIpsetCtx_process(t *testing.T) {
 		assert.NoError(t, err)
 	})
 }
+
+func TestIpsetCtx_SkipIpsetProcessing(t *testing.T) {
+	req4 := createTestMessage("example.com")
+	resp4 := &dns.Msg{
+		Answer: []dns.RR{&dns.A{
+			A: net.IP{1, 2, 3, 4},
+		}},
+	}
+
+	m := &fakeIpsetMgr{}
+	ictx := &ipsetCtx{
+		ipsetMgr: m,
+	}
+
+	testCases := []struct {
+		dctx *dnsContext
+		name string
+		want bool
+	}{{
+		name: "basic",
+		want: false,
+		dctx: &dnsContext{
+			proxyCtx: &proxy.DNSContext{
+				Req: req4,
+				Res: resp4,
+			},
+
+			responseFromUpstream: true,
+		},
+	}, {
+		name: "rewrite",
+		want: true,
+		dctx: &dnsContext{
+			proxyCtx: &proxy.DNSContext{
+				Req: req4,
+				Res: resp4,
+			},
+
+			responseFromUpstream: false,
+		},
+	}, {
+		name: "empty_req",
+		want: true,
+		dctx: &dnsContext{
+			proxyCtx: &proxy.DNSContext{
+				Req: nil,
+				Res: resp4,
+			},
+
+			responseFromUpstream: true,
+		},
+	}, {
+		name: "empty_res",
+		want: true,
+		dctx: &dnsContext{
+			proxyCtx: &proxy.DNSContext{
+				Req: req4,
+				Res: nil,
+			},
+
+			responseFromUpstream: true,
+		},
+	}}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := ictx.skipIpsetProcessing(tc.dctx)
+			assert.Equal(t, tc.want, got)
+		})
+	}
+}