Parser for signed configuration.

Signed configuration is stored an JSON inside APK meta-data. The format
of the JSON is as follows:

{
  "version": n,
  "config": [
    {
      "minSdk": n,
      "maxSdk": n,
      "values": [
        {
          "key": "global settings key",
          "value": "value for key"
        },
	...
      ],
      ...
    }
  ]
}

Test: atest SignedConfigTest
Bug: 110509075
Change-Id: I4d345b1f03e5c5f5af37de093eb6e5cb2429c42c

3 files changed, 498 insertions, 0 deletions

diff --git a/services/core/java/com/android/server/signedconfig/InvalidConfigException.java b/services/core/java/com/android/server/signedconfig/InvalidConfigException.java
new file mode 100644
index 000000000000..f01baa4b0c5d
--- /dev/null
+++ b/services/core/java/com/android/server/signedconfig/InvalidConfigException.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+package com.android.server.signedconfig;
+
+/**
+ * Thrown when there is a problem parsing the config embedded in an APK.
+ */
+public class InvalidConfigException extends Exception {
+
+    public InvalidConfigException(String message) {
+        super(message);
+    }
+
+    public InvalidConfigException(String message, Exception cause) {
+        super(message, cause);
+    }
+
+
+}
diff --git a/services/core/java/com/android/server/signedconfig/SignedConfig.java b/services/core/java/com/android/server/signedconfig/SignedConfig.java
new file mode 100644
index 000000000000..a3f452c27d13
--- /dev/null
+++ b/services/core/java/com/android/server/signedconfig/SignedConfig.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+package com.android.server.signedconfig;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Represents signed configuration.
+ *
+ * <p>This configuration should only be used if the signature has already been verified.
+ */
+public class SignedConfig {
+
+    private static final String KEY_VERSION = "version";
+    private static final String KEY_CONFIG = "config";
+
+    private static final String CONFIG_KEY_MIN_SDK = "minSdk";
+    private static final String CONFIG_KEY_MAX_SDK = "maxSdk";
+    private static final String CONFIG_KEY_VALUES = "values";
+    // TODO it may be better to use regular key/value pairs in a JSON object, rather than an array
+    // of objects with the 2 keys below.
+    private static final String CONFIG_KEY_KEY = "key";
+    private static final String CONFIG_KEY_VALUE = "value";
+
+    /**
+     * Represents config values targetting to an SDK range.
+     */
+    public static class PerSdkConfig {
+        public final int minSdk;
+        public final int maxSdk;
+        public final Map<String, String> values;
+
+        public PerSdkConfig(int minSdk, int maxSdk, Map<String, String> values) {
+            this.minSdk = minSdk;
+            this.maxSdk = maxSdk;
+            this.values = Collections.unmodifiableMap(values);
+        }
+
+    }
+
+    public final int version;
+    public final List<PerSdkConfig> perSdkConfig;
+
+    public SignedConfig(int version, List<PerSdkConfig> perSdkConfig) {
+        this.version = version;
+        this.perSdkConfig = Collections.unmodifiableList(perSdkConfig);
+    }
+
+    /**
+     * Find matching sdk config for a given SDK level.
+     *
+     * @param sdkVersion SDK version of device.
+     * @return Matching config, of {@code null} if there is none.
+     */
+    public PerSdkConfig getMatchingConfig(int sdkVersion) {
+        for (PerSdkConfig config : perSdkConfig) {
+            if (config.minSdk <= sdkVersion && sdkVersion <= config.maxSdk) {
+                return config;
+            }
+        }
+        // nothing matching
+        return null;
+    }
+
+    /**
+     * Parse configuration from an APK.
+     *
+     * @param config config as read from the APK metadata.
+     * @return Parsed configuration.
+     * @throws InvalidConfigException If there's a problem parsing the config.
+     */
+    public static SignedConfig parse(String config, Set<String> allowedKeys)
+            throws InvalidConfigException {
+        try {
+            JSONObject json = new JSONObject(config);
+            int version = json.getInt(KEY_VERSION);
+
+            JSONArray perSdkConfig = json.getJSONArray(KEY_CONFIG);
+            List<PerSdkConfig> parsedConfigs = new ArrayList<>();
+            for (int i = 0; i < perSdkConfig.length(); ++i) {
+                parsedConfigs.add(parsePerSdkConfig(perSdkConfig.getJSONObject(i), allowedKeys));
+            }
+
+            return new SignedConfig(version, parsedConfigs);
+        } catch (JSONException e) {
+            throw new InvalidConfigException("Could not parse JSON", e);
+        }
+
+    }
+
+    @VisibleForTesting
+    static PerSdkConfig parsePerSdkConfig(JSONObject json, Set<String> allowedKeys)
+            throws JSONException, InvalidConfigException {
+        int minSdk = json.getInt(CONFIG_KEY_MIN_SDK);
+        int maxSdk = json.getInt(CONFIG_KEY_MAX_SDK);
+        JSONArray valueArray = json.getJSONArray(CONFIG_KEY_VALUES);
+        Map<String, String> values = new HashMap<>();
+        for (int i = 0; i < valueArray.length(); ++i) {
+            JSONObject keyValuePair = valueArray.getJSONObject(i);
+            String key = keyValuePair.getString(CONFIG_KEY_KEY);
+            String value = keyValuePair.has(CONFIG_KEY_VALUE)
+                    ? keyValuePair.getString(CONFIG_KEY_VALUE)
+                    : null;
+            if (!allowedKeys.contains(key)) {
+                throw new InvalidConfigException("Config key " + key + " is not allowed");
+            }
+            values.put(key, value);
+        }
+        return new PerSdkConfig(minSdk, maxSdk, values);
+    }
+
+}
diff --git a/services/tests/servicestests/src/com/android/server/signedconfig/SignedConfigTest.java b/services/tests/servicestests/src/com/android/server/signedconfig/SignedConfigTest.java
new file mode 100644
index 000000000000..a9d4519104ba
--- /dev/null
+++ b/services/tests/servicestests/src/com/android/server/signedconfig/SignedConfigTest.java
@@ -0,0 +1,328 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+package com.android.server.signedconfig;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.junit.Assert.fail;
+
+import static java.util.Collections.emptySet;
+
+import androidx.test.runner.AndroidJUnit4;
+
+import com.google.common.collect.Sets;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Set;
+
+
+/**
+ * Tests for {@link SignedConfig}
+ */
+@RunWith(AndroidJUnit4.class)
+public class SignedConfigTest {
+
+    private static Set<String> setOf(String... values) {
+        return Sets.newHashSet(values);
+    }
+
+    @Test
+    public void testParsePerSdkConfigSdkMinMax() throws JSONException, InvalidConfigException {
+        JSONObject json = new JSONObject("{\"minSdk\":2, \"maxSdk\": 3, \"values\": []}");
+        SignedConfig.PerSdkConfig config = SignedConfig.parsePerSdkConfig(json, emptySet());
+        assertThat(config.minSdk).isEqualTo(2);
+        assertThat(config.maxSdk).isEqualTo(3);
+    }
+
+    @Test
+    public void testParsePerSdkConfigNoMinSdk() throws JSONException {
+        JSONObject json = new JSONObject("{\"maxSdk\": 3, \"values\": []}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigNoMaxSdk() throws JSONException {
+        JSONObject json = new JSONObject("{\"minSdk\": 1, \"values\": []}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigNoValues() throws JSONException {
+        JSONObject json = new JSONObject("{\"minSdk\": 1, \"maxSdk\": 3}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigSdkNullMinSdk() throws JSONException, InvalidConfigException {
+        JSONObject json = new JSONObject("{\"minSdk\":null, \"maxSdk\": 3, \"values\": []}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigSdkNullMaxSdk() throws JSONException, InvalidConfigException {
+        JSONObject json = new JSONObject("{\"minSdk\":1, \"maxSdk\": null, \"values\": []}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigNullValues() throws JSONException {
+        JSONObject json = new JSONObject("{\"minSdk\": 1, \"maxSdk\": 3, \"values\": null}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigZeroValues()
+            throws JSONException, InvalidConfigException {
+        JSONObject json = new JSONObject("{\"minSdk\": 1, \"maxSdk\": 3, \"values\": []}");
+        SignedConfig.PerSdkConfig config = SignedConfig.parsePerSdkConfig(json, setOf("a", "b"));
+        assertThat(config.values).hasSize(0);
+    }
+
+    @Test
+    public void testParsePerSdkConfigSingleKey()
+            throws JSONException, InvalidConfigException {
+        JSONObject json = new JSONObject(
+                "{\"minSdk\": 1, \"maxSdk\": 1, \"values\": [{\"key\":\"a\", \"value\": \"1\"}]}");
+        SignedConfig.PerSdkConfig config = SignedConfig.parsePerSdkConfig(json, setOf("a", "b"));
+        assertThat(config.values).containsExactly("a", "1");
+    }
+
+    @Test
+    public void testParsePerSdkConfigMultiKeys()
+            throws JSONException, InvalidConfigException {
+        JSONObject json = new JSONObject(
+                "{\"minSdk\": 1, \"maxSdk\": 1, \"values\": [{\"key\":\"a\", \"value\": \"1\"}, "
+                        + "{\"key\":\"c\", \"value\": \"2\"}]}");
+        SignedConfig.PerSdkConfig config = SignedConfig.parsePerSdkConfig(
+                json, setOf("a", "b", "c"));
+        assertThat(config.values).containsExactly("a", "1", "c", "2");
+    }
+
+    @Test
+    public void testParsePerSdkConfigSingleKeyNotAllowed() throws JSONException {
+        JSONObject json = new JSONObject(
+                "{\"minSdk\": 1, \"maxSdk\": 1, \"values\": [{\"key\":\"a\", \"value\": \"1\"}]}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, setOf("b"));
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigSingleKeyNoValue()
+            throws JSONException, InvalidConfigException {
+        JSONObject json = new JSONObject(
+                "{\"minSdk\": 1, \"maxSdk\": 1, \"values\": [{\"key\":\"a\"}]}");
+        SignedConfig.PerSdkConfig config = SignedConfig.parsePerSdkConfig(json, setOf("a", "b"));
+        assertThat(config.values).containsExactly("a", null);
+    }
+
+    @Test
+    public void testParsePerSdkConfigValuesInvalid() throws JSONException  {
+        JSONObject json = new JSONObject("{\"minSdk\": 1, \"maxSdk\": 1,  \"values\": \"foo\"}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigConfigEntryInvalid() throws JSONException {
+        JSONObject json = new JSONObject("{\"minSdk\": 1, \"maxSdk\": 1,  \"values\": [1, 2]}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParsePerSdkConfigConfigEntryNull() throws JSONException {
+        JSONObject json = new JSONObject("{\"minSdk\": 1, \"maxSdk\": 1,  \"values\": [null]}");
+        try {
+            SignedConfig.parsePerSdkConfig(json, emptySet());
+            fail("Expected InvalidConfigException or JSONException");
+        } catch (JSONException | InvalidConfigException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void testParseVersion() throws InvalidConfigException {
+        SignedConfig config = SignedConfig.parse(
+                "{\"version\": 1, \"config\": []}", emptySet());
+        assertThat(config.version).isEqualTo(1);
+    }
+
+    @Test
+    public void testParseVersionInvalid() {
+        try {
+            SignedConfig.parse("{\"version\": \"notanint\", \"config\": []}", emptySet());
+            fail("Expected InvalidConfigException");
+        } catch (InvalidConfigException e) {
+            //expected
+        }
+    }
+
+    @Test
+    public void testParseNoVersion() {
+        try {
+            SignedConfig.parse("{\"config\": []}", emptySet());
+            fail("Expected InvalidConfigException");
+        } catch (InvalidConfigException e) {
+            //expected
+        }
+    }
+
+    @Test
+    public void testParseNoConfig() {
+        try {
+            SignedConfig.parse("{\"version\": 1}", emptySet());
+            fail("Expected InvalidConfigException");
+        } catch (InvalidConfigException e) {
+            //expected
+        }
+    }
+
+    @Test
+    public void testParseConfigNull() {
+        try {
+            SignedConfig.parse("{\"version\": 1, \"config\": null}", emptySet());
+            fail("Expected InvalidConfigException");
+        } catch (InvalidConfigException e) {
+            //expected
+        }
+    }
+
+    @Test
+    public void testParseVersionNull() {
+        try {
+            SignedConfig.parse("{\"version\": null, \"config\": []}", emptySet());
+            fail("Expected InvalidConfigException");
+        } catch (InvalidConfigException e) {
+            //expected
+        }
+    }
+
+    @Test
+    public void testParseConfigInvalidEntry() {
+        try {
+            SignedConfig.parse("{\"version\": 1, \"config\": [{}]}", emptySet());
+            fail("Expected InvalidConfigException");
+        } catch (InvalidConfigException e) {
+            //expected
+        }
+    }
+
+    @Test
+    public void testParseSdkConfigSingle() throws InvalidConfigException {
+        SignedConfig config = SignedConfig.parse(
+                "{\"version\": 1, \"config\":[{\"minSdk\": 1, \"maxSdk\": 1, \"values\": []}]}",
+                emptySet());
+        assertThat(config.perSdkConfig).hasSize(1);
+    }
+
+    @Test
+    public void testParseSdkConfigMultiple() throws InvalidConfigException {
+        SignedConfig config = SignedConfig.parse(
+                "{\"version\": 1, \"config\":[{\"minSdk\": 1, \"maxSdk\": 1, \"values\": []}, "
+                        + "{\"minSdk\": 2, \"maxSdk\": 2, \"values\": []}]}", emptySet());
+        assertThat(config.perSdkConfig).hasSize(2);
+    }
+
+    @Test
+    public void testGetMatchingConfigFirst() {
+        SignedConfig.PerSdkConfig sdk1 = new SignedConfig.PerSdkConfig(
+                1, 1, Collections.emptyMap());
+        SignedConfig.PerSdkConfig sdk2 = new SignedConfig.PerSdkConfig(
+                2, 2, Collections.emptyMap());
+        SignedConfig config = new SignedConfig(0, Arrays.asList(sdk1, sdk2));
+        assertThat(config.getMatchingConfig(1)).isEqualTo(sdk1);
+    }
+
+    @Test
+    public void testGetMatchingConfigSecond() {
+        SignedConfig.PerSdkConfig sdk1 = new SignedConfig.PerSdkConfig(
+                1, 1, Collections.emptyMap());
+        SignedConfig.PerSdkConfig sdk2 = new SignedConfig.PerSdkConfig(
+                2, 2, Collections.emptyMap());
+        SignedConfig config = new SignedConfig(0, Arrays.asList(sdk1, sdk2));
+        assertThat(config.getMatchingConfig(2)).isEqualTo(sdk2);
+    }
+
+    @Test
+    public void testGetMatchingConfigInRange() {
+        SignedConfig.PerSdkConfig sdk13 = new SignedConfig.PerSdkConfig(
+                1, 3, Collections.emptyMap());
+        SignedConfig.PerSdkConfig sdk46 = new SignedConfig.PerSdkConfig(
+                4, 6, Collections.emptyMap());
+        SignedConfig config = new SignedConfig(0, Arrays.asList(sdk13, sdk46));
+        assertThat(config.getMatchingConfig(2)).isEqualTo(sdk13);
+    }
+
+    @Test
+    public void testGetMatchingConfigNoMatch() {
+        SignedConfig.PerSdkConfig sdk1 = new SignedConfig.PerSdkConfig(
+                1, 1, Collections.emptyMap());
+        SignedConfig.PerSdkConfig sdk2 = new SignedConfig.PerSdkConfig(
+                2, 2, Collections.emptyMap());
+        SignedConfig config = new SignedConfig(0, Arrays.asList(sdk1, sdk2));
+        assertThat(config.getMatchingConfig(3)).isNull();
+    }
+
+}