ios: add string accessor API (#1202)

Description: iOS parallel to #1188
Risk Level: low
Testing: example app. Pending test with assertion filter.
Docs Changes: pending full API docs

Signed-off-by: Jose Nino <jnino@lyft.com>
Signed-off-by: JP Simard <jp@jpsim.com>

mobile/examples/swift/hello_world/ViewController.swift

@@ -26,6 +26,7 @@ final class ViewController: UITableViewController {
                          // swiftlint:disable:next line_length
                          typedConfig: "{\"@type\":\"type.googleapis.com/envoy.extensions.filters.http.buffer.v3.Buffer\",\"max_request_bytes\":5242880}")
         .setOnEngineRunning { NSLog("Envoy async internal setup completed") }
+        .addStringAccessor(name: "string_accessor", accessor: { return "DemoStringAccessor" })
         .build()
       self.streamClient = engine.streamClient()
       self.pulseClient = engine.pulseClient()

mobile/library/common/api/c_types.h

@@ -8,7 +8,7 @@
 extern "C" { // function pointers
 #endif
 
-typedef envoy_data (*envoy_get_string_f)(void* context);
+typedef envoy_data (*envoy_get_string_f)(const void* context);
 
 #ifdef __cplusplus
 } // function pointers
@@ -21,5 +21,5 @@ typedef envoy_data (*envoy_get_string_f)(void* context);
 //       types.
 typedef struct {
   envoy_get_string_f get_string;
-  void* context;
+  const void* context;
 } envoy_string_accessor;

mobile/library/common/api/external.cc

@@ -21,7 +21,7 @@ void registerApi(std::string name, void* api) { registry_[name] = api; }
 // before any reads occur.
 void* retrieveApi(std::string name) {
   void* api = registry_[name];
-  ASSERT(api);
+  ASSERT(api, fmt::format("{} not registered", name));
   return api;
 }
 

mobile/library/common/jni/jni_interface.cc

@@ -654,9 +654,9 @@ static const void* jvm_http_filter_init(const void* context) {
 
 // EnvoyStringAccessor
 
-static envoy_data jvm_get_string(void* context) {
+static envoy_data jvm_get_string(const void* context) {
   JNIEnv* env = get_env();
-  jobject j_context = static_cast<jobject>(context);
+  jobject j_context = static_cast<jobject>(const_cast<void*>(context));
   jclass jcls_JvmStringAccessorContext = env->GetObjectClass(j_context);
   jmethodID jmid_getString =
       env->GetMethodID(jcls_JvmStringAccessorContext, "getString", "()Ljava/nio/ByteBuffer;");

mobile/library/objective-c/BUILD

@@ -19,6 +19,7 @@ objc_library(
         "EnvoyHTTPStreamImpl.m",
         "EnvoyNativeFilterConfig.m",
         "EnvoyNetworkMonitor.m",
+        "EnvoyStringAccessor.m",
     ],
     hdrs = [
         "EnvoyEngine.h",

mobile/library/objective-c/EnvoyConfiguration.m

@@ -14,8 +14,9 @@ - (instancetype)initWithStatsDomain:(NSString *)statsDomain
                               appId:(NSString *)appId
                     virtualClusters:(NSString *)virtualClusters
                   nativeFilterChain:(NSArray<EnvoyNativeFilterConfig *> *)nativeFilterChain
-                platformFilterChain:
-                    (NSArray<EnvoyHTTPFilterFactory *> *)httpPlatformFilterFactories {
+                platformFilterChain:(NSArray<EnvoyHTTPFilterFactory *> *)httpPlatformFilterFactories
+                    stringAccessors:
+                        (NSDictionary<NSString *, EnvoyStringAccessor *> *)stringAccessors {
   self = [super init];
   if (!self) {
     return nil;
@@ -26,12 +27,13 @@ - (instancetype)initWithStatsDomain:(NSString *)statsDomain
   self.dnsRefreshSeconds = dnsRefreshSeconds;
   self.dnsFailureRefreshSecondsBase = dnsFailureRefreshSecondsBase;
   self.dnsFailureRefreshSecondsMax = dnsFailureRefreshSecondsMax;
-  self.httpPlatformFilterFactories = httpPlatformFilterFactories;
   self.statsFlushSeconds = statsFlushSeconds;
   self.appVersion = appVersion;
   self.appId = appId;
   self.virtualClusters = virtualClusters;
   self.nativeFilterChain = nativeFilterChain;
+  self.httpPlatformFilterFactories = httpPlatformFilterFactories;
+  self.stringAccessors = stringAccessors;
   return self;
 }
 

mobile/library/objective-c/EnvoyEngine.h

@@ -225,6 +225,16 @@ extern const int kEnvoyFilterResumeStatusResumeIteration;
 
 @end
 
+#pragma mark - EnvoyStringAccessor
+
+@interface EnvoyStringAccessor : NSObject
+
+@property (nonatomic, copy) NSString * (^getEnvoyString)();
+
+- (instancetype)initWithBlock:(NSString * (^)())block;
+
+@end
+
 #pragma mark - EnvoyNativeFilterConfig
 
 @interface EnvoyNativeFilterConfig : NSObject
@@ -252,6 +262,7 @@ extern const int kEnvoyFilterResumeStatusResumeIteration;
 @property (nonatomic, strong) NSString *virtualClusters;
 @property (nonatomic, strong) NSArray<EnvoyNativeFilterConfig *> *nativeFilterChain;
 @property (nonatomic, strong) NSArray<EnvoyHTTPFilterFactory *> *httpPlatformFilterFactories;
+@property (nonatomic, strong) NSDictionary<NSString *, EnvoyStringAccessor *> *stringAccessors;
 
 /**
  Create a new instance of the configuration.
@@ -266,8 +277,9 @@ extern const int kEnvoyFilterResumeStatusResumeIteration;
                               appId:(NSString *)appId
                     virtualClusters:(NSString *)virtualClusters
                   nativeFilterChain:(NSArray<EnvoyNativeFilterConfig *> *)nativeFilterChain
-                platformFilterChain:
-                    (NSArray<EnvoyHTTPFilterFactory *> *)httpPlatformFilterFactories;
+                platformFilterChain:(NSArray<EnvoyHTTPFilterFactory *> *)httpPlatformFilterFactories
+                    stringAccessors:
+                        (NSDictionary<NSString *, EnvoyStringAccessor *> *)stringAccessors;
 
 /**
  Resolves the provided configuration template using properties on this configuration.

mobile/library/objective-c/EnvoyEngineImpl.m

@@ -2,6 +2,8 @@
 #import "library/objective-c/EnvoyBridgeUtility.h"
 #import "library/objective-c/EnvoyHTTPFilterCallbacksImpl.h"
 
+#include "library/common/api/c_types.h"
+
 #import "library/common/main_interface.h"
 #import "library/common/types/c_types.h"
 
@@ -286,6 +288,11 @@ static void ios_http_filter_release(const void *context) {
   return;
 }
 
+static envoy_data ios_get_string(const void *context) {
+  EnvoyStringAccessor *accessor = (__bridge EnvoyStringAccessor *)context;
+  return toManagedNativeString(accessor.getEnvoyString());
+}
+
 @implementation EnvoyEngineImpl {
   envoy_engine_t _engineHandle;
 }
@@ -330,6 +337,16 @@ - (int)registerFilterFactory:(EnvoyHTTPFilterFactory *)filterFactory {
   return kEnvoySuccess;
 }
 
+- (int)registerStringAccessor:(NSString *)name accessor:(EnvoyStringAccessor *)accessor {
+  // TODO(goaway): Everything here leaks, but it's all be tied to the life of the engine.
+  // This will need to be updated for https://github.com/lyft/envoy-mobile/issues/332
+  envoy_string_accessor *accessorStruct = safe_malloc(sizeof(envoy_string_accessor));
+  accessorStruct->get_string = ios_get_string;
+  accessorStruct->context = CFBridgingRetain(accessor);
+
+  return register_platform_api(name.UTF8String, accessorStruct);
+}
+
 - (int)runWithConfig:(EnvoyConfiguration *)config
             logLevel:(NSString *)logLevel
      onEngineRunning:(nullable void (^)())onEngineRunning {
@@ -343,6 +360,10 @@ - (int)runWithConfig:(EnvoyConfiguration *)config
     [self registerFilterFactory:filterFactory];
   }
 
+  for (NSString *name in config.stringAccessors) {
+    [self registerStringAccessor:name accessor:config.stringAccessors[name]];
+  }
+
   return [self runWithConfigYAML:resolvedYAML logLevel:logLevel onEngineRunning:onEngineRunning];
 }
 
@@ -359,6 +380,10 @@ - (int)runWithTemplate:(NSString *)yaml
     [self registerFilterFactory:filterFactory];
   }
 
+  for (NSString *name in config.stringAccessors) {
+    [self registerStringAccessor:name accessor:config.stringAccessors[name]];
+  }
+
   return [self runWithConfigYAML:resolvedYAML logLevel:logLevel onEngineRunning:onEngineRunning];
 }
 

mobile/library/objective-c/EnvoyStringAccessor.m

@@ -0,0 +1,15 @@
+#import "library/objective-c/EnvoyEngine.h"
+
+@implementation EnvoyStringAccessor
+
+- (instancetype)initWithBlock:(NSString * (^)())block {
+  self = [super init];
+  if (!self) {
+    return nil;
+  }
+
+  self.getEnvoyString = block;
+  return self;
+}
+
+@end

mobile/library/swift/src/EngineBuilder.swift

@@ -21,10 +21,11 @@ public final class EngineBuilder: NSObject {
   private var statsFlushSeconds: UInt32 = 60
   private var appVersion: String = "unspecified"
   private var appId: String = "unspecified"
-  private var platformFilterChain: [EnvoyHTTPFilterFactory] = []
   private var virtualClusters: String = "[]"
   private var onEngineRunning: (() -> Void)?
   private var nativeFilterChain: [EnvoyNativeFilterConfig] = []
+  private var platformFilterChain: [EnvoyHTTPFilterFactory] = []
+  private var stringAccessors: [String: EnvoyStringAccessor] = [:]
 
   // MARK: - Public
 
@@ -142,6 +143,19 @@ public final class EngineBuilder: NSObject {
     return self
   }
 
+  /// Add a string accessor to this Envoy Client.
+  ///
+  /// - parameter name: the name of the accessor.
+  /// - parameter accessor: lambda to access a string from the platform layer.
+  ///
+  /// - returns this builder.
+  @discardableResult
+  public func addStringAccessor(name: String,
+                                accessor: @escaping () -> String) -> EngineBuilder {
+    self.stringAccessors[name] = EnvoyStringAccessor(block: accessor)
+    return self
+  }
+
   /// Set a closure to be called when the engine finishes its async startup and begins running.
   ///
   /// - parameter closure: The closure to be called.
@@ -202,7 +216,8 @@ public final class EngineBuilder: NSObject {
         appId: self.appId,
         virtualClusters: self.virtualClusters,
         nativeFilterChain: self.nativeFilterChain,
-        platformFilterChain: self.platformFilterChain)
+        platformFilterChain: self.platformFilterChain,
+        stringAccessors: self.stringAccessors)
 
     switch self.base {
     case .custom(let yaml):

mobile/library/swift/test/EngineBuilderTests.swift

@@ -199,6 +199,20 @@ final class EngineBuilderTests: XCTestCase {
     self.waitForExpectations(timeout: 0.01)
   }
 
+  func testAddingStringAccessorToConfigurationWhenRunningEnvoy() throws {
+    let expectation = self.expectation(description: "Run called with expected data")
+    MockEnvoyEngine.onRunWithConfig = { config, _ in
+      XCTAssertEqual("hello", config.stringAccessors["name"]?.getEnvoyString())
+      expectation.fulfill()
+    }
+
+    _ = try EngineBuilder()
+      .addEngineType(MockEnvoyEngine.self)
+      .addStringAccessor(name: "name", accessor: { "hello" })
+      .build()
+    self.waitForExpectations(timeout: 0.01)
+  }
+
   func testResolvesYAMLWithIndividuallySetValues() throws {
     let filterFactory = EnvoyHTTPFilterFactory(filterName: "TestFilter", factory: TestFilter.init)
     let config = EnvoyConfiguration(statsDomain: "stats.envoyproxy.io",
@@ -214,7 +228,8 @@ final class EngineBuilderTests: XCTestCase {
                                       [EnvoyNativeFilterConfig(name: "filter_name",
                                                                typedConfig: "test_config"),
                                       ],
-                                    platformFilterChain: [filterFactory])
+                                    platformFilterChain: [filterFactory],
+                                    stringAccessors: [:])
     let resolvedYAML = try XCTUnwrap(config.resolveTemplate(kMockTemplate))
     XCTAssertTrue(resolvedYAML.contains("stats_domain: stats.envoyproxy.io"))
     XCTAssertTrue(resolvedYAML.contains("connect_timeout: 200s"))
@@ -242,7 +257,8 @@ final class EngineBuilderTests: XCTestCase {
                                     appId: "com.envoymobile.ios",
                                     virtualClusters: "[test]",
                                     nativeFilterChain: [],
-                                    platformFilterChain: [])
+                                    platformFilterChain: [],
+                                    stringAccessors: [:])
     XCTAssertNil(config.resolveTemplate("{{ missing }}"))
   }
 }