gRPC: add the ability to use a custom SSL certificate in integration tests

Firestore/Example/Tests/Util/FSTIntegrationTestCase.mm

@@ -36,6 +36,7 @@
 
 #include "Firestore/core/src/firebase/firestore/auth/empty_credentials_provider.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
+#include "Firestore/core/src/firebase/firestore/remote/grpc_connection.h"
 #include "Firestore/core/src/firebase/firestore/util/autoid.h"
 #include "Firestore/core/src/firebase/firestore/util/filesystem.h"
 #include "Firestore/core/src/firebase/firestore/util/path.h"
@@ -57,6 +58,7 @@
 using firebase::firestore::auth::EmptyCredentialsProvider;
 using firebase::firestore::model::DatabaseId;
 using firebase::firestore::testutil::AppForUnitTesting;
+using firebase::firestore::remote::GrpcConnection;
 using firebase::firestore::util::CreateAutoId;
 using firebase::firestore::util::Path;
 using firebase::firestore::util::Status;
@@ -164,6 +166,8 @@ + (void)setUpDefaults {
          "setup_integration_tests.py to properly configure testing SSL certificates.");
   }
   [GRPCCall useTestCertsPath:certsPath testName:@"test_cert_2" forHost:defaultSettings.host];
+  GrpcConnection::UseTestCertificate([certsPath cStringUsingEncoding:NSASCIIStringEncoding],
+                                     "test_cert_2");
 }
 
 + (NSString *)projectID {

Firestore/core/src/firebase/firestore/remote/grpc_connection.h

@@ -18,6 +18,7 @@
 #define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_REMOTE_GRPC_CONNECTION_H_
 
 #include <memory>
+#include <string>
 #include <vector>
 
 #include "Firestore/core/src/firebase/firestore/auth/token.h"
@@ -78,7 +79,27 @@ class GrpcConnection {
   void Register(GrpcCall* call);
   void Unregister(GrpcCall* call);
 
+  /**
+   * For tests only: use a custom root certificate file and the given SSL
+   * target name for all connections. Call before creating any streams or calls.
+   */
+  static void UseTestCertificate(absl::string_view certificate_path,
+                                 absl::string_view target_name);
+
+  /**
+   * For tests only: don't use SSL, send all traffic unencrypted. Call before
+   * creating any streams or calls. Overrides a test certificate.
+   */
+  static void UseInsecureChannel();
+
  private:
+  struct TestCredentials {
+    std::string certificate_path;
+    std::string target_name;
+    bool use_insecure_channel = false;
+  };
+  static TestCredentials* test_credentials_;
+
   std::unique_ptr<grpc::ClientContext> CreateContext(
       const auth::Token& credential) const;
   std::shared_ptr<grpc::Channel> CreateChannel() const;

Firestore/core/src/firebase/firestore/remote/grpc_connection.mm

@@ -17,6 +17,8 @@
 #include "Firestore/core/src/firebase/firestore/remote/grpc_connection.h"
 
 #include <algorithm>
+#include <fstream>
+#include <sstream>
 #include <string>
 #include <utility>
 
@@ -52,6 +54,8 @@
 
 }  // namespace
 
+GrpcConnection::TestCredentials* GrpcConnection::test_credentials_ = nullptr;
+
 GrpcConnection::GrpcConnection(const DatabaseInfo& database_info,
                                util::AsyncQueue* worker_queue,
                                grpc::CompletionQueue* grpc_queue,
@@ -114,9 +118,31 @@
 }
 
 std::shared_ptr<grpc::Channel> GrpcConnection::CreateChannel() const {
-  return grpc::CreateChannel(
-      database_info_->host(),
-      grpc::SslCredentials(grpc::SslCredentialsOptions()));
+  if (!test_credentials_) {
+    return grpc::CreateChannel(
+        database_info_->host(),
+        grpc::SslCredentials(grpc::SslCredentialsOptions()));
+  }
+
+  if (test_credentials_->use_insecure_channel) {
+    return grpc::CreateChannel(database_info_->host(),
+                               grpc::InsecureChannelCredentials());
+  }
+
+  std::ifstream cert_file{test_credentials_->certificate_path};
+  HARD_ASSERT(cert_file.good(),
+              StringFormat("Unable to open root certificates at file path %s",
+                           test_credentials_->certificate_path)
+                  .c_str());
+  std::stringstream cert_buffer;
+  cert_buffer << cert_file.rdbuf();
+  grpc::SslCredentialsOptions options;
+  options.pem_root_certs = cert_buffer.str();
+
+  grpc::ChannelArguments args;
+  args.SetSslTargetNameOverride(test_credentials_->target_name);
+  return grpc::CreateCustomChannel(database_info_->host(),
+                                   grpc::SslCredentials(options), args);
 }
 
 std::unique_ptr<GrpcStream> GrpcConnection::CreateStream(
@@ -181,6 +207,33 @@
   active_calls_.erase(found);
 }
 
+/*static*/ void GrpcConnection::UseTestCertificate(
+    absl::string_view certificate_path, absl::string_view target_name) {
+  HARD_ASSERT(!certificate_path.empty(), "Empty path to test certificate");
+  HARD_ASSERT(!target_name.empty(), "Empty SSL target name");
+
+  if (!test_credentials_) {
+    // Deliberately never deleted.
+    test_credentials_ = new TestCredentials{};
+  }
+
+  test_credentials_->certificate_path =
+      std::string{certificate_path.data(), certificate_path.size()};
+  test_credentials_->target_name =
+      std::string{target_name.data(), target_name.size()};
+  // TODO(varconst): hostname if necessary.
+}
+
+/*static*/ void GrpcConnection::UseInsecureChannel() {
+  if (!test_credentials_) {
+    // Deliberately never deleted.
+    test_credentials_ = new TestCredentials{};
+  }
+
+  test_credentials_->use_insecure_channel = true;
+  // TODO(varconst): hostname if necessary.
+}
+
 }  // namespace remote
 }  // namespace firestore
 }  // namespace firebase