[Test] for libcom.android.tethering.dns_helper.so

Exercise the BpfReader::isUidNetworkingBlocked().

Bug: 288340533
Test: atest dns_helper_unit_test
Change-Id: Icc889a6a9649e991cba222427f9b8d4f5ee3b325

DnsResolver/Android.bp

@@ -52,3 +52,32 @@ cc_library {
     apex_available: ["com.android.tethering"],
     min_sdk_version: "30",
 }
+
+cc_test {
+    name: "dns_helper_unit_test",
+    defaults: ["netd_defaults"],
+    test_suites: ["general-tests", "mts-tethering"],
+    test_config_template: ":net_native_test_config_template",
+    header_libs: [
+        "bpf_connectivity_headers",
+    ],
+    srcs: [
+        "DnsBpfHelperTest.cpp",
+    ],
+    static_libs: [
+        "libcom.android.tethering.dns_helper",
+    ],
+    shared_libs: [
+       "libbase",
+       "libcutils",
+    ],
+    compile_multilib: "both",
+    multilib: {
+        lib32: {
+            suffix: "32",
+        },
+        lib64: {
+            suffix: "64",
+        },
+    },
+}

DnsResolver/DnsBpfHelper.h

@@ -36,6 +36,9 @@ class DnsBpfHelper {
  private:
   android::bpf::BpfMapRO<uint32_t, uint32_t> mConfigurationMap;
   android::bpf::BpfMapRO<uint32_t, UidOwnerValue> mUidOwnerMap;
+
+  // For testing
+  friend class DnsBpfHelperTest;
 };
 
 }  // namespace net

DnsResolver/DnsBpfHelperTest.cpp

@@ -0,0 +1,141 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+#include <private/android_filesystem_config.h>
+
+#define BPF_MAP_MAKE_VISIBLE_FOR_TESTING
+#include "DnsBpfHelper.h"
+
+using namespace android::bpf;  // NOLINT(google-build-using-namespace): exempted
+
+namespace android {
+namespace net {
+
+constexpr int TEST_MAP_SIZE = 2;
+
+#define ASSERT_VALID(x) ASSERT_TRUE((x).isValid())
+
+class DnsBpfHelperTest : public ::testing::Test {
+ protected:
+  DnsBpfHelper mDnsBpfHelper;
+  BpfMap<uint32_t, uint32_t> mFakeConfigurationMap;
+  BpfMap<uint32_t, UidOwnerValue> mFakeUidOwnerMap;
+
+  void SetUp() {
+    mFakeConfigurationMap.resetMap(BPF_MAP_TYPE_ARRAY, CONFIGURATION_MAP_SIZE);
+    ASSERT_VALID(mFakeConfigurationMap);
+
+    mFakeUidOwnerMap.resetMap(BPF_MAP_TYPE_HASH, TEST_MAP_SIZE);
+    ASSERT_VALID(mFakeUidOwnerMap);
+
+    mDnsBpfHelper.mConfigurationMap = mFakeConfigurationMap;
+    ASSERT_VALID(mDnsBpfHelper.mConfigurationMap);
+    mDnsBpfHelper.mUidOwnerMap = mFakeUidOwnerMap;
+    ASSERT_VALID(mDnsBpfHelper.mUidOwnerMap);
+  }
+
+  void ResetAllMaps() {
+    mDnsBpfHelper.mConfigurationMap.reset();
+    mDnsBpfHelper.mUidOwnerMap.reset();
+  }
+};
+
+TEST_F(DnsBpfHelperTest, IsUidNetworkingBlocked) {
+  struct TestConfig {
+    const uid_t uid;
+    const uint32_t enabledRules;
+    const uint32_t uidRules;
+    const int expectedResult;
+    std::string toString() const {
+      return fmt::format(
+          "uid: {}, enabledRules: {}, uidRules: {}, expectedResult: {}",
+          uid, enabledRules, uidRules, expectedResult);
+    }
+  } testConfigs[] = {
+    // clang-format off
+    //   No rule enabled:
+    // uid,         enabledRules,                  uidRules,                      expectedResult
+    {AID_APP_START, NO_MATCH,                      NO_MATCH,                      false},
+
+    //   An allowlist rule:
+    {AID_APP_START, NO_MATCH,                      DOZABLE_MATCH,                 false},
+    {AID_APP_START, DOZABLE_MATCH,                 NO_MATCH,                      true},
+    {AID_APP_START, DOZABLE_MATCH,                 DOZABLE_MATCH,                 false},
+    //   A denylist rule
+    {AID_APP_START, NO_MATCH,                      STANDBY_MATCH,                 false},
+    {AID_APP_START, STANDBY_MATCH,                 NO_MATCH,                      false},
+    {AID_APP_START, STANDBY_MATCH,                 STANDBY_MATCH,                 true},
+
+    //   Multiple rules enabled:
+    //     Match only part of the enabled allowlist rules.
+    {AID_APP_START, DOZABLE_MATCH|POWERSAVE_MATCH, DOZABLE_MATCH,                 true},
+    {AID_APP_START, DOZABLE_MATCH|POWERSAVE_MATCH, POWERSAVE_MATCH,               true},
+    //     Match all of the enabled allowlist rules.
+    {AID_APP_START, DOZABLE_MATCH|POWERSAVE_MATCH, DOZABLE_MATCH|POWERSAVE_MATCH, false},
+    //     Match allowlist.
+    {AID_APP_START, DOZABLE_MATCH|STANDBY_MATCH,   DOZABLE_MATCH,                 false},
+    //     Match no rule.
+    {AID_APP_START, DOZABLE_MATCH|STANDBY_MATCH,   NO_MATCH,                      true},
+    {AID_APP_START, DOZABLE_MATCH|POWERSAVE_MATCH, NO_MATCH,                      true},
+
+    // System UID: always unblocked.
+    {AID_SYSTEM,    NO_MATCH,                      NO_MATCH,                      false},
+    {AID_SYSTEM,    NO_MATCH,                      DOZABLE_MATCH,                 false},
+    {AID_SYSTEM,    DOZABLE_MATCH,                 NO_MATCH,                      false},
+    {AID_SYSTEM,    DOZABLE_MATCH,                 DOZABLE_MATCH,                 false},
+    {AID_SYSTEM,    NO_MATCH,                      STANDBY_MATCH,                 false},
+    {AID_SYSTEM,    STANDBY_MATCH,                 NO_MATCH,                      false},
+    {AID_SYSTEM,    STANDBY_MATCH,                 STANDBY_MATCH,                 false},
+    {AID_SYSTEM,    DOZABLE_MATCH|POWERSAVE_MATCH, DOZABLE_MATCH,                 false},
+    {AID_SYSTEM,    DOZABLE_MATCH|POWERSAVE_MATCH, POWERSAVE_MATCH,               false},
+    {AID_SYSTEM,    DOZABLE_MATCH|POWERSAVE_MATCH, DOZABLE_MATCH|POWERSAVE_MATCH, false},
+    {AID_SYSTEM,    DOZABLE_MATCH|STANDBY_MATCH,   DOZABLE_MATCH,                 false},
+    {AID_SYSTEM,    DOZABLE_MATCH|STANDBY_MATCH,   NO_MATCH,                      false},
+    {AID_SYSTEM,    DOZABLE_MATCH|POWERSAVE_MATCH, NO_MATCH,                      false},
+    // clang-format on
+  };
+
+  for (const auto& config : testConfigs) {
+    SCOPED_TRACE(config.toString());
+
+    // Setup maps.
+    EXPECT_RESULT_OK(mFakeConfigurationMap.writeValue(UID_RULES_CONFIGURATION_KEY,
+                                                      config.enabledRules, BPF_EXIST));
+    EXPECT_RESULT_OK(mFakeUidOwnerMap.writeValue(config.uid, {.iif = 0, .rule = config.uidRules},
+                                                 BPF_ANY));
+
+    // Verify the function.
+    auto result = mDnsBpfHelper.isUidNetworkingBlocked(config.uid, /*metered=*/false);
+    EXPECT_TRUE(result.ok());
+    EXPECT_EQ(config.expectedResult, result.value());
+  }
+}
+
+TEST_F(DnsBpfHelperTest, IsUidNetworkingBlocked_uninitialized) {
+  ResetAllMaps();
+
+  auto result = mDnsBpfHelper.isUidNetworkingBlocked(AID_APP_START, /*metered=*/false);
+  EXPECT_FALSE(result.ok());
+  EXPECT_EQ(EUNATCH, result.error().code());
+
+  result = mDnsBpfHelper.isUidNetworkingBlocked(AID_SYSTEM, /*metered=*/false);
+  EXPECT_TRUE(result.ok());
+  EXPECT_FALSE(result.value());
+}
+
+}  // namespace net
+}  // namespace android