bridge: add register string accessor functionality plus expose on And…

…roid (#1188)

Description: this PR adds the ability to register string accessors from the platform to the engine. This allows the core layer to access strings from the platform at runtime. Two highlights:

    Eventually this mechanism should be made generic to be able to access and set arbitrary types from the platform. This is very type-specific as a POC. #1192
    This PR only wires up Android's platform layer all the way. A subsequent PR will do the same for iOS.

Risk Level: low - new API
Testing: using the example app.
Signed-off-by: Jose Nino <jnino@lyft.com>
Signed-off-by: JP Simard <jp@jpsim.com>

mobile/examples/kotlin/hello_world/BUILD

@@ -21,6 +21,7 @@ kt_android_library(
         "AsyncDemoFilter.kt",
         "BufferDemoFilter.kt",
         "DemoFilter.kt",
+        "DemoStringAccessor.kt",
         "MainActivity.kt",
     ],
     custom_package = "io.envoyproxy.envoymobile.helloenvoykotlin",

mobile/examples/kotlin/hello_world/DemoStringAccessor.kt

@@ -0,0 +1,10 @@
+package io.envoyproxy.envoymobile.helloenvoykotlin
+
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor
+import java.nio.ByteBuffer
+
+class DemoStringAccessor : EnvoyStringAccessor {
+  override fun getString(): ByteBuffer {
+    return ByteBuffer.wrap("PlatformString".toByteArray(Charsets.UTF_8))
+  }
+}

mobile/examples/kotlin/hello_world/MainActivity.kt

@@ -47,6 +47,7 @@ class MainActivity : Activity() {
       .addFilter { DemoFilter() }
       .addFilter { BufferDemoFilter() }
       .addFilter { AsyncDemoFilter() }
+      .addStringAccessor("demo-accessor", DemoStringAccessor())
       .setOnEngineRunning { Log.d("MainActivity", "Envoy async internal setup completed") }
       .build()
 

mobile/library/common/api/BUILD

@@ -18,3 +18,12 @@ envoy_cc_library(
         "@envoy//source/common/common:assert_lib",
     ],
 )
+
+envoy_cc_library(
+    name = "c_types",
+    hdrs = ["c_types.h"],
+    repository = "@envoy",
+    deps = [
+        "//library/common/types:c_types_lib",
+    ],
+)

mobile/library/common/api/c_types.h

@@ -0,0 +1,25 @@
+#pragma once
+
+#include "library/common/types/c_types.h"
+
+// NOLINT(namespace-envoy)
+
+#ifdef __cplusplus
+extern "C" { // function pointers
+#endif
+
+typedef envoy_data (*envoy_get_string_f)(void* context);
+
+#ifdef __cplusplus
+} // function pointers
+#endif
+
+/**
+ * Datatype used to access strings from the platform layer. This accessor is read-only.
+ */
+// TODO: https://github.com/envoyproxy/envoy-mobile/issues/1192 generalize to access arbitrary
+//       types.
+typedef struct {
+  envoy_get_string_f get_string;
+  void* context;
+} envoy_string_accessor;

mobile/library/common/jni/BUILD

@@ -37,5 +37,6 @@ cc_binary(
     deps = [
         ":jni_utility_lib",
         "//library/common:envoy_main_interface_lib",
+        "//library/common/api:c_types",
     ],
 )

mobile/library/common/jni/jni_interface.cc

@@ -4,6 +4,7 @@
 
 #include <string>
 
+#include "library/common/api/c_types.h"
 #include "library/common/extensions/filters/http/platform_bridge/c_types.h"
 #include "library/common/jni/jni_utility.h"
 #include "library/common/jni/jni_version.h"
@@ -610,6 +611,24 @@ static const void* jvm_http_filter_init(const void* context) {
   return retained_filter;
 }
 
+// EnvoyStringAccessor
+
+static envoy_data jvm_get_string(void* context) {
+  JNIEnv* env = get_env();
+  jobject j_context = static_cast<jobject>(context);
+  jclass jcls_JvmStringAccessorContext = env->GetObjectClass(j_context);
+  jmethodID jmid_getString =
+      env->GetMethodID(jcls_JvmStringAccessorContext, "getString", "()Ljava/nio/ByteBuffer;");
+  // Passed as a java.nio.ByteBuffer.
+  jobject j_data = env->CallObjectMethod(j_context, jmid_getString);
+  envoy_data native_data = buffer_to_native_data(env, j_data);
+
+  env->DeleteLocalRef(jcls_JvmStringAccessorContext);
+  env->DeleteLocalRef(j_data);
+
+  return native_data;
+}
+
 // EnvoyHTTPStream
 
 extern "C" JNIEXPORT jlong JNICALL Java_io_envoyproxy_envoymobile_engine_JniLibrary_initStream(
@@ -672,9 +691,9 @@ Java_io_envoyproxy_envoymobile_engine_JniLibrary_registerFilterFactory(JNIEnv* e
   api->static_context = retained_context;
   api->instance_context = NULL;
 
-  register_platform_api(env->GetStringUTFChars(filter_name, nullptr), api);
+  envoy_status_t result = register_platform_api(env->GetStringUTFChars(filter_name, nullptr), api);
   env->DeleteLocalRef(jcls_JvmFilterFactoryContext);
-  return ENVOY_SUCCESS;
+  return result;
 }
 
 extern "C" JNIEXPORT void JNICALL
@@ -742,3 +761,26 @@ extern "C" JNIEXPORT jint JNICALL Java_io_envoyproxy_envoymobile_engine_JniLibra
 
   return reset_stream(static_cast<envoy_stream_t>(stream_handle));
 }
+
+// EnvoyStringAccessor
+
+extern "C" JNIEXPORT jint JNICALL
+Java_io_envoyproxy_envoymobile_engine_JniLibrary_registerStringAccessor(JNIEnv* env, jclass,
+                                                                        jstring accessor_name,
+                                                                        jobject j_context) {
+
+  // TODO(goaway): The retained_context leaks, but it's tied to the life of the engine.
+  // This will need to be updated for https://github.com/lyft/envoy-mobile/issues/332.
+  jclass jcls_JvmStringAccessorContext = env->GetObjectClass(j_context);
+  jobject retained_context = env->NewGlobalRef(j_context);
+
+  envoy_string_accessor* string_accessor =
+      (envoy_string_accessor*)safe_malloc(sizeof(envoy_string_accessor));
+  string_accessor->get_string = jvm_get_string;
+  string_accessor->context = retained_context;
+
+  envoy_status_t result =
+      register_platform_api(env->GetStringUTFChars(accessor_name, nullptr), string_accessor);
+  env->DeleteLocalRef(jcls_JvmStringAccessorContext);
+  return result;
+}

mobile/library/java/src/io/envoyproxy/envoymobile/engine/AndroidEngineImpl.java

@@ -3,6 +3,7 @@
 import android.app.Application;
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPCallbacks;
 import io.envoyproxy.envoymobile.engine.types.EnvoyOnEngineRunning;
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor;
 
 /* Android-specific implementation of the `EnvoyEngine` interface. */
 public class AndroidEngineImpl implements EnvoyEngine {
@@ -58,4 +59,9 @@ public int recordGaugeAdd(String elements, int amount) {
   public int recordGaugeSub(String elements, int amount) {
     return envoyEngine.recordGaugeSub(elements, amount);
   }
+
+  @Override
+  public int registerStringAccessor(String accessorName, EnvoyStringAccessor accessor) {
+    return envoyEngine.registerStringAccessor(accessorName, accessor);
+  }
 }

mobile/library/java/src/io/envoyproxy/envoymobile/engine/BUILD

@@ -37,6 +37,7 @@ java_library(
         "JvmCallbackContext.java",
         "JvmFilterContext.java",
         "JvmFilterFactoryContext.java",
+        "JvmStringAccessorContext.java",
     ],
     visibility = ["//visibility:public"],
     deps = [

mobile/library/java/src/io/envoyproxy/envoymobile/engine/EnvoyConfiguration.java

@@ -1,10 +1,12 @@
 package io.envoyproxy.envoymobile.engine;
 
 import java.util.List;
+import java.util.Map;
 import java.util.regex.Pattern;
 import java.util.regex.Matcher;
 
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPFilterFactory;
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor;
 
 /* Typed configuration that may be used for starting Envoy. */
 public class EnvoyConfiguration {
@@ -18,6 +20,7 @@ public class EnvoyConfiguration {
   public final String appVersion;
   public final String appId;
   public final String virtualClusters;
+  public final Map<String, EnvoyStringAccessor> stringAccessors;
 
   private static final Pattern UNRESOLVED_KEY_PATTERN = Pattern.compile("\\{\\{ (.+) \\}\\}");
 
@@ -34,11 +37,13 @@ public class EnvoyConfiguration {
    * @param appVersion                   the App Version of the App using this Envoy Client.
    * @param appId                        the App ID of the App using this Envoy Client.
    * @param virtualClusters              the JSON list of virtual cluster configs.
+   * @param stringAccesssors             platform string accessors to register.
    */
   public EnvoyConfiguration(String statsDomain, int connectTimeoutSeconds, int dnsRefreshSeconds,
                             int dnsFailureRefreshSecondsBase, int dnsFailureRefreshSecondsMax,
                             List<EnvoyHTTPFilterFactory> httpFilterFactories, int statsFlushSeconds,
-                            String appVersion, String appId, String virtualClusters) {
+                            String appVersion, String appId, String virtualClusters,
+                            Map<String, EnvoyStringAccessor> stringAccessors) {
     this.statsDomain = statsDomain;
     this.connectTimeoutSeconds = connectTimeoutSeconds;
     this.dnsRefreshSeconds = dnsRefreshSeconds;
@@ -49,6 +54,7 @@ public EnvoyConfiguration(String statsDomain, int connectTimeoutSeconds, int dns
     this.appVersion = appVersion;
     this.appId = appId;
     this.virtualClusters = virtualClusters;
+    this.stringAccessors = stringAccessors;
   }
 
   /**

mobile/library/java/src/io/envoyproxy/envoymobile/engine/EnvoyEngine.java

@@ -2,6 +2,7 @@
 
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPCallbacks;
 import io.envoyproxy.envoymobile.engine.types.EnvoyOnEngineRunning;
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor;
 
 /* Wrapper layer for calling into Envoy's C/++ API. */
 public interface EnvoyEngine {
@@ -70,4 +71,6 @@ int runWithConfig(EnvoyConfiguration envoyConfiguration, String logLevel,
    * @return A status indicating if the action was successful.
    */
   int recordGaugeSub(String elements, int amount);
+
+  int registerStringAccessor(String accessor_name, EnvoyStringAccessor accessor);
 }

mobile/library/java/src/io/envoyproxy/envoymobile/engine/EnvoyEngineImpl.java

@@ -1,8 +1,11 @@
 package io.envoyproxy.envoymobile.engine;
 
+import java.util.Map;
+
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPCallbacks;
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPFilterFactory;
 import io.envoyproxy.envoymobile.engine.types.EnvoyOnEngineRunning;
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor;
 
 /* Concrete implementation of the `EnvoyEngine` interface. */
 public class EnvoyEngineImpl implements EnvoyEngine {
@@ -69,6 +72,12 @@ public int runWithConfig(EnvoyConfiguration envoyConfiguration, String logLevel,
                                        new JvmFilterFactoryContext(filterFactory));
     }
 
+    for (Map.Entry<String, EnvoyStringAccessor> entry :
+         envoyConfiguration.stringAccessors.entrySet()) {
+      JniLibrary.registerStringAccessor(entry.getKey(),
+                                        new JvmStringAccessorContext(entry.getValue()));
+    }
+
     return runWithConfig(envoyConfiguration.resolveTemplate(JniLibrary.templateString(),
                                                             JniLibrary.filterTemplateString()),
                          logLevel, onEngineRunning);
@@ -121,4 +130,9 @@ public int recordGaugeAdd(String elements, int amount) {
   public int recordGaugeSub(String elements, int amount) {
     return JniLibrary.recordGaugeSub(engineHandle, elements, amount);
   }
+
+  @Override
+  public int registerStringAccessor(String accessor_name, EnvoyStringAccessor accessor) {
+    return JniLibrary.registerStringAccessor(accessor_name, new JvmStringAccessorContext(accessor));
+  }
 }

mobile/library/java/src/io/envoyproxy/envoymobile/engine/JniLibrary.java

@@ -201,4 +201,14 @@ protected static native int runEngine(long engine, String config, String logLeve
    *         filter platform filter configuration.
    */
   public static native String filterTemplateString();
+
+  /**
+   * Register a string accessor to get strings from the platform.
+   *
+   * @param accessorName, unique name identifying this accessor.
+   * @param context,    context containing logic necessary to invoke the accessor.
+   * @return int, the resulting status of the operation.
+   */
+  protected static native int registerStringAccessor(String accessorName,
+                                                     JvmStringAccessorContext context);
 }

mobile/library/java/src/io/envoyproxy/envoymobile/engine/JvmStringAccessorContext.java

@@ -0,0 +1,18 @@
+package io.envoyproxy.envoymobile.engine;
+
+import java.nio.ByteBuffer;
+
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor;
+
+class JvmStringAccessorContext {
+  private final EnvoyStringAccessor accessor;
+
+  public JvmStringAccessorContext(EnvoyStringAccessor accessor) { this.accessor = accessor; }
+
+  /**
+   * Invokes getString callback.
+   *
+   * @return ByteBuffer, the string retrieved from the platform.
+   */
+  public ByteBuffer getString() { return accessor.getString(); }
+}

mobile/library/java/src/io/envoyproxy/envoymobile/engine/types/BUILD

@@ -11,6 +11,7 @@ java_library(
         "EnvoyHTTPFilterFactory.java",
         "EnvoyOnEngineRunning.java",
         "EnvoyStatus.java",
+        "EnvoyStringAccessor.java",
     ],
     visibility = ["//visibility:public"],
 )

mobile/library/java/src/io/envoyproxy/envoymobile/engine/types/EnvoyStringAccessor.java

@@ -0,0 +1,11 @@
+package io.envoyproxy.envoymobile.engine.types;
+
+import java.nio.ByteBuffer;
+
+public interface EnvoyStringAccessor {
+
+  /**
+   * Called to retrieve a string from the Application
+   */
+  ByteBuffer getString();
+}

mobile/library/java/test/io/envoyproxy/envoymobile/engine/EnvoyConfigurationTest.kt

@@ -32,7 +32,7 @@ class EnvoyConfigurationTest {
 
   @Test
   fun `resolving with default configuration resolves with values`() {
-    val envoyConfiguration = EnvoyConfiguration("stats.foo.com", 123, 234, 345, 456, emptyList(), 567, "v1.2.3", "com.mydomain.myapp", "[test]")
+    val envoyConfiguration = EnvoyConfiguration("stats.foo.com", 123, 234, 345, 456, emptyList(), 567, "v1.2.3", "com.mydomain.myapp", "[test]", emptyMap())
 
     val resolvedTemplate = envoyConfiguration.resolveTemplate(TEST_CONFIG, FILTER_CONFIG)
     assertThat(resolvedTemplate).contains("stats_domain: stats.foo.com")
@@ -49,7 +49,7 @@ class EnvoyConfigurationTest {
 
   @Test
   fun `resolve templates with invalid templates will throw on build`() {
-    val envoyConfiguration = EnvoyConfiguration("stats.foo.com", 123, 234, 345, 456, emptyList(), 567, "v1.2.3", "com.mydomain.myapp", "[test]")
+    val envoyConfiguration = EnvoyConfiguration("stats.foo.com", 123, 234, 345, 456, emptyList(), 567, "v1.2.3", "com.mydomain.myapp", "[test]", emptyMap())
 
     try {
       envoyConfiguration.resolveTemplate("{{ missing }}", "")

mobile/library/kotlin/src/io/envoyproxy/envoymobile/EngineBuilder.kt

@@ -4,6 +4,7 @@ import io.envoyproxy.envoymobile.engine.EnvoyConfiguration
 import io.envoyproxy.envoymobile.engine.EnvoyEngine
 import io.envoyproxy.envoymobile.engine.EnvoyEngineImpl
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPFilterFactory
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor
 import java.util.UUID
 
 sealed class BaseConfiguration
@@ -31,6 +32,7 @@ open class EngineBuilder(
   private var appVersion = "unspecified"
   private var appId = "unspecified"
   private var virtualClusters = "[]"
+  private var stringAccessors = mutableMapOf<String, EnvoyStringAccessor>()
 
   /**
    * Add a log level to use with Envoy.
@@ -134,6 +136,19 @@ open class EngineBuilder(
     return this
   }
 
+  /**
+   * Add a string accessor to this Envoy Client.
+   *
+   * @param name the name of the accessor.
+   * @param accessor the string accessor.
+   *
+   * @return this builder.
+   */
+  fun addStringAccessor(name: String, accessor: EnvoyStringAccessor): EngineBuilder {
+    this.stringAccessors.put(name, accessor)
+    return this
+  }
+
   /**
    * Add the App Version of the App using this Envoy Client.
    *
@@ -186,7 +201,7 @@ open class EngineBuilder(
           EnvoyConfiguration(
             statsDomain, connectTimeoutSeconds,
             dnsRefreshSeconds, dnsFailureRefreshSecondsBase, dnsFailureRefreshSecondsMax,
-            filterChain, statsFlushSeconds, appVersion, appId, virtualClusters
+            filterChain, statsFlushSeconds, appVersion, appId, virtualClusters, stringAccessors
           ),
           logLevel, onEngineRunning
         )

mobile/library/kotlin/src/io/envoyproxy/envoymobile/mocks/MockEnvoyEngine.kt

@@ -5,6 +5,7 @@ import io.envoyproxy.envoymobile.engine.EnvoyEngine
 import io.envoyproxy.envoymobile.engine.EnvoyHTTPStream
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPCallbacks
 import io.envoyproxy.envoymobile.engine.types.EnvoyOnEngineRunning
+import io.envoyproxy.envoymobile.engine.types.EnvoyStringAccessor
 
 /**
  * Mock implementation of `EnvoyEngine`. Used internally for testing the bridging layer & mocking.
@@ -23,4 +24,6 @@ internal class MockEnvoyEngine : EnvoyEngine {
   override fun recordGaugeAdd(elements: String, amount: Int): Int = 0
 
   override fun recordGaugeSub(elements: String, amount: Int): Int = 0
+
+  override fun registerStringAccessor(accessorName: String, accessor: EnvoyStringAccessor): Int = 0
 }