gRPC: add gRPC wrapper classes to CMake build (#2015)

* add a C++ equivalent of `FIRFirestoreVersionString`. This eliminates the only Objective-C dependency of `grpc_connection.mm` and allows making it a pure C++ file;
* open-source `binary_to_array.py` script and use it in the build to embed `roots.pem` certificate file from gRPC into the Firestore binary. The embedded char array is then used to load certificate at runtime.

Author: var-const

CMakeLists.txt

@@ -59,6 +59,12 @@ set(
   CACHE PATH "Where to store downloaded files"
 )
 
+set(
+  FIREBASE_EXTERNAL_SOURCE_DIR
+  ${FIREBASE_BINARY_DIR}/external/src
+  CACHE PATH "Root directory of source code of the external dependencies"
+)
+
 download_external_sources()
 
 
@@ -103,8 +109,6 @@ set(gRPC_BUILD_TESTS OFF CACHE BOOL "Disable gRPC tests")
 add_external_subdirectory(grpc)
 
 # Fix up targets included by gRPC's build
-set(external_src_dir ${FIREBASE_BINARY_DIR}/external/src)
-
 if(OPENSSL_FOUND)
   # gRPC's CMakeLists.txt does not account for finding OpenSSL in a directory
   # that's not in the default search path.
@@ -127,14 +131,14 @@ else()
   target_include_directories(
     crypto
     INTERFACE
-      $<BUILD_INTERFACE:${external_src_dir}/grpc/third_party/boringssl/include>
+      $<BUILD_INTERFACE:${FIREBASE_EXTERNAL_SOURCE_DIR}/grpc/third_party/boringssl/include>
   )
 
   add_alias(OpenSSL::SSL ssl)
   target_include_directories(
     ssl
     INTERFACE
-      $<BUILD_INTERFACE:${external_src_dir}/grpc/third_party/boringssl/include>
+      $<BUILD_INTERFACE:${FIREBASE_EXTERNAL_SOURCE_DIR}/grpc/third_party/boringssl/include>
   )
 endif()
 
@@ -156,7 +160,7 @@ endif()
 if(NOT ZLIB_FOUND)
   target_include_directories(
     zlibstatic
-    INTERFACE $<BUILD_INTERFACE:${external_src_dir}/grpc/third_party/zlib>
+    INTERFACE $<BUILD_INTERFACE:${FIREBASE_EXTERNAL_SOURCE_DIR}/grpc/third_party/zlib>
   )
 endif()
 
@@ -186,7 +190,7 @@ target_compile_definitions(
 
 target_include_directories(
   protobuf-nanopb
-  INTERFACE $<BUILD_INTERFACE:${external_src_dir}/nanopb>
+  INTERFACE $<BUILD_INTERFACE:${FIREBASE_EXTERNAL_SOURCE_DIR}/nanopb>
 )
 
 

FirebaseFirestore.podspec

@@ -40,6 +40,7 @@ Google Cloud Firestore is a NoSQL document database built for automatic scaling,
 
     # Exclude alternate implementations for other platforms
     'Firestore/core/src/firebase/firestore/remote/connectivity_monitor_noop.cc',
+    'Firestore/core/src/firebase/firestore/remote/grpc_root_certificate_finder_generated.cc',
     'Firestore/core/src/firebase/firestore/util/filesystem_win.cc',
     'Firestore/core/src/firebase/firestore/util/hard_assert_stdio.cc',
     'Firestore/core/src/firebase/firestore/util/log_stdio.cc',

Firestore/Source/API/FIRFirestoreVersion.mm

@@ -16,16 +16,11 @@
 
 #import "Firestore/Source/API/FIRFirestoreVersion.h"
 
-#ifndef FIRFirestore_VERSION
-#error "FIRFirestore_VERSION is not defined: add -DFIRFirestore_VERSION=... to the build invocation"
-#endif
+#include "Firestore/core/include/firebase/firestore/firestore_version.h"
 
-// The following two macros supply the incantation so that the C
-// preprocessor does not try to parse the version as a floating
-// point number. See
-// https://www.guyrutenberg.com/2008/12/20/expanding-macros-into-string-constants-in-c/
-#define STR(x) STR_EXPAND(x)
-#define STR_EXPAND(x) #x
+using firebase::firestore::kFirestoreVersionString;
 
+// Because `kFirestoreVersionString` is subject to constant initialization, this
+// is not affected by static initialization order fiasco.
 extern "C" const unsigned char *const FIRFirestoreVersionString =
-    (const unsigned char *const)STR(FIRFirestore_VERSION);
+    (const unsigned char *const)kFirestoreVersionString;

Firestore/core/include/firebase/firestore/firestore_version.h

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018 Google
+ *
+ * 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.
+ */
+
+#ifndef FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_VERSION_H_
+#define FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_VERSION_H_
+
+/** Version for Firestore. */
+
+namespace firebase {
+namespace firestore {
+
+/** Version string for the Firebase Firestore SDK. */
+extern const char* const kFirestoreVersionString;
+
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_INCLUDE_FIREBASE_FIRESTORE_FIRESTORE_VERSION_H_

Firestore/core/src/firebase/firestore/CMakeLists.txt

@@ -23,6 +23,18 @@ cc_library(
     firebase_firestore_util
 )
 
+cc_library(
+  firebase_firestore_version
+  SOURCES
+    firestore_version.cc
+)
+
+target_compile_definitions(
+  firebase_firestore_version
+  PRIVATE
+    FIRFirestore_VERSION=0.13.6
+)
+
 # Include the folder with public headers.
 target_include_directories(
   firebase_firestore_types

Firestore/core/src/firebase/firestore/firestore_version.cc

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2018 Google
+ *
+ * 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 "Firestore/core/include/firebase/firestore/firestore_version.h"
+
+#ifndef FIRFirestore_VERSION
+#error \
+    "FIRFirestore_VERSION is not defined: add -DFIRFirestore_VERSION=... to the build invocation"  // NOLINT(whitespace/line_length)
+#endif
+
+namespace firebase {
+namespace firestore {
+
+// The following two macros supply the incantation so that the C
+// preprocessor does not try to parse the version as a floating
+// point number. See
+// https://www.guyrutenberg.com/2008/12/20/expanding-macros-into-string-constants-in-c/
+#define STR(x) STR_EXPAND(x)
+#define STR_EXPAND(x) #x
+
+const char* const kFirestoreVersionString = STR(FIRFirestore_VERSION);
+
+}  // namespace firestore
+}  // namespace firebase

Firestore/core/src/firebase/firestore/remote/CMakeLists.txt

@@ -42,15 +42,62 @@ cc_select(
   DEFAULT firebase_firestore_remote_connectivity_monitor_noop
 )
 
+# `roots.pem` is a file containing root certificates that is distributed
+# alongside gRPC and is necessary to establish SSL connections. Embed this file
+# into the binary by converting it to a char array.
+add_custom_command(
+    OUTPUT grpc_root_certificates_generated.h grpc_root_certificates_generated.cc
+    COMMAND ${FIREBASE_SOURCE_DIR}/scripts/binary_to_array.py
+        --output_header=grpc_root_certificates_generated.h
+        --output_source=grpc_root_certificates_generated.cc
+        --cpp_namespace=firebase::firestore::remote
+        --array=grpc_root_certificates
+        --array_size=grpc_root_certificates_size
+        ${FIREBASE_EXTERNAL_SOURCE_DIR}/grpc/etc/roots.pem
+    DEPENDS
+    ${FIREBASE_EXTERNAL_SOURCE_DIR}/grpc/etc/roots.pem
+)
+
 cc_library(
   firebase_firestore_remote
   SOURCES
-    grpc_util.h
-    grpc_util.cc
-    exponential_backoff.h
     exponential_backoff.cc
+    exponential_backoff.h
+    grpc_call.h
+    grpc_completion.cc
+    grpc_completion.h
+    grpc_connection.cc
+    grpc_connection.h
+    grpc_root_certificate_finder.h
+    grpc_root_certificate_finder_generated.cc
+    grpc_root_certificates_generated.cc
+    grpc_root_certificates_generated.h
+    grpc_stream.cc
+    grpc_stream.h
+    grpc_stream_observer.h
+    grpc_streaming_reader.cc
+    grpc_streaming_reader.h
+    grpc_unary_call.cc
+    grpc_unary_call.h
+    grpc_util.cc
+    grpc_util.cc
+    grpc_util.h
     serializer.h
     serializer.cc
+
+    # TODO(varconst): add these files once they no longer depend on Objective-C
+    # serializer.
+    # datastore.h
+    # datastore.mm
+    # remote_objc_bridge.h
+    # remote_objc_bridge.mm
+    # stream.h
+    # stream.mm
+    # watch_stream.h
+    # watch_stream.mm
+    # write_stream.h
+    # write_stream.mm
+
   DEPENDS
     # TODO(b/111328563) Force nanopb first to work around ODR violations
     protobuf-nanopb
@@ -60,5 +107,7 @@ cc_library(
     firebase_firestore_protos_nanopb
     firebase_firestore_remote_connectivity_monitor
     firebase_firestore_util
-    grpc
+    firebase_firestore_version
+
+    grpc++
 )

Firestore/core/src/firebase/firestore/remote/grpc_connection.mm renamed to Firestore/core/src/firebase/firestore/remote/grpc_connection.cc

@@ -17,23 +17,21 @@
 #include "Firestore/core/src/firebase/firestore/remote/grpc_connection.h"
 
 #include <algorithm>
-#include <fstream>
-#include <sstream>
 #include <string>
 #include <utility>
 
 #include "Firestore/core/include/firebase/firestore/firestore_errors.h"
+#include "Firestore/core/include/firebase/firestore/firestore_version.h"
 #include "Firestore/core/src/firebase/firestore/auth/token.h"
 #include "Firestore/core/src/firebase/firestore/model/database_id.h"
 #include "Firestore/core/src/firebase/firestore/remote/grpc_root_certificate_finder.h"
+#include "Firestore/core/src/firebase/firestore/util/filesystem.h"
 #include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
 #include "Firestore/core/src/firebase/firestore/util/log.h"
 #include "Firestore/core/src/firebase/firestore/util/string_format.h"
 #include "absl/memory/memory.h"
 #include "grpcpp/create_channel.h"
 
-#import "Firestore/Source/API/FIRFirestoreVersion.h"
-
 namespace firebase {
 namespace firestore {
 namespace remote {
@@ -43,6 +41,7 @@
 using model::DatabaseId;
 using util::Path;
 using util::Status;
+using util::StatusOr;
 using util::StringFormat;
 
 namespace {
@@ -54,22 +53,10 @@
   return view.data() ? std::string{view.data(), view.size()} : std::string{};
 }
 
-std::string LoadCertificate(const Path& path) {
-  std::ifstream certificate_file{path.native_value()};
-  HARD_ASSERT(certificate_file.good(),
-              StringFormat("Unable to open root certificates at file path %s",
-                           path.ToUtf8String())
-                  .c_str());
-
-  std::stringstream buffer;
-  buffer << certificate_file.rdbuf();
-  return buffer.str();
-}
-
 std::shared_ptr<grpc::ChannelCredentials> CreateSslCredentials(
-    const Path& certificate_path) {
+    const std::string& certificate) {
   grpc::SslCredentialsOptions options;
-  options.pem_root_certs = LoadCertificate(certificate_path);
+  options.pem_root_certs = certificate;
   return grpc::SslCredentials(options);
 }
 
@@ -132,8 +119,7 @@ bool HasSpecialConfig(const std::string& host) {
   // C++ SDK, etc.).
   context->AddMetadata(
       kXGoogAPIClientHeader,
-      StringFormat("gl-objc/ fire/%s grpc/",
-                   reinterpret_cast<const char*>(FIRFirestoreVersionString)));
+      StringFormat("gl-objc/ fire/%s grpc/", kFirestoreVersionString));
 
   // This header is used to improve routing and project isolation by the
   // backend.
@@ -159,9 +145,8 @@ bool HasSpecialConfig(const std::string& host) {
   const std::string& host = database_info_->host();
 
   if (!HasSpecialConfig(host)) {
-    Path root_certificate_path = FindGrpcRootCertificate();
-    return grpc::CreateChannel(host,
-                               CreateSslCredentials(root_certificate_path));
+    std::string root_certificate = LoadGrpcRootCertificate();
+    return grpc::CreateChannel(host, CreateSslCredentials(root_certificate));
   }
 
   const HostConfig& host_config = Config()[host];
@@ -174,8 +159,15 @@ bool HasSpecialConfig(const std::string& host) {
   // For tests only
   grpc::ChannelArguments args;
   args.SetSslTargetNameOverride(host_config.target_name);
+  Path path = host_config.certificate_path;
+  StatusOr<std::string> test_certificate = ReadFile(path);
+  HARD_ASSERT(test_certificate.ok(),
+              StringFormat("Unable to open root certificates at file path %s",
+                           path.ToUtf8String())
+                  .c_str());
+
   return grpc::CreateCustomChannel(
-      host, CreateSslCredentials(host_config.certificate_path), args);
+      host, CreateSslCredentials(test_certificate.ValueOrDie()), args);
 }
 
 std::unique_ptr<GrpcStream> GrpcConnection::CreateStream(

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

@@ -26,11 +26,11 @@ namespace firestore {
 namespace remote {
 
 /**
- * Finds the file containing gRPC root certificates (`roots.pem`, must be among
- * resources accessible by Firestore) and returns its path. Will trigger
- * assertion failure if the file cannot be found.
+ * Finds the file containing gRPC root certificates (how it is stored differs by
+ * platform) and returns its contents as a string. Will trigger assertion
+ * failure if the file cannot be found or open.
  */
-util::Path FindGrpcRootCertificate();
+std::string LoadGrpcRootCertificate();
 
 }  // namespace remote
 }  // namespace firestore