-(dnsforward): custom client per-domain upstreams

Closes: https://github.com/AdguardTeam/AdGuardHome/issues/1539

home/clients_test.go

@@ -236,3 +236,31 @@ func TestClientsAddExisting(t *testing.T) {
 	assert.True(t, ok)
 	assert.Nil(t, err)
 }
+
+func TestClientsCustomUpstream(t *testing.T) {
+	clients := clientsContainer{}
+	clients.testing = true
+
+	clients.Init(nil, nil, nil)
+
+	// add client with upstreams
+	client := Client{
+		IDs:  []string{"1.1.1.1", "1:2:3::4", "aa:aa:aa:aa:aa:aa"},
+		Name: "client1",
+		Upstreams: []string{
+			"1.1.1.1",
+			"[/example.org/]8.8.8.8",
+		},
+	}
+	ok, err := clients.Add(client)
+	assert.Nil(t, err)
+	assert.True(t, ok)
+
+	config := clients.FindUpstreams("1.2.3.4")
+	assert.Nil(t, config)
+
+	config = clients.FindUpstreams("1.1.1.1")
+	assert.NotNil(t, config)
+	assert.Equal(t, 1, len(config.Upstreams))
+	assert.Equal(t, 1, len(config.DomainReservedUpstreams))
+}