Add BlimpEngineConfig to verify command line switches and store config

Initially this has the shared secret between the client and the engine.

BUG=575421

Review URL: https://codereview.chromium.org/1489413005

Cr-Commit-Position: refs/heads/master@{#369861}

11 files changed, 274 insertions, 5 deletions

diff --git a/blimp/docs/container.md b/blimp/docs/container.md
index b817072..36a5cee 100644
--- a/blimp/docs/container.md
+++ b/blimp/docs/container.md
@@ -75,3 +75,15 @@ docker run blimp_engine --with-my-flags
 
 See the [blimp engine `Dockerfile`](../engine/Dockerfile) to find out what flags
 are passed by default.
+
+### Mapping Volumes into the Docker Container
+
+If you need to map a directory into the Docker container (eg. for necessary
+files):
+
+```bash
+docker run -v /path/to/srcdir:/path/to/docker/destdir blimp_engine
+```
+
+NB: The permissions of the directory and the files outside of the Docker
+container will be carried over into the container.
diff --git a/blimp/docs/running.md b/blimp/docs/running.md
index b8bba0f..9678a09 100644
--- a/blimp/docs/running.md
+++ b/blimp/docs/running.md
@@ -42,3 +42,7 @@ client device via USB, you'll need remote port forwarding to allow the Blimp
 client to talk to your computer. Follow the instructions
 [here](https://developer.chrome.com/devtools/docs/remote-debugging) to get
 started. You'll probably want to remap 25467 to "localhost:25467".
+
+### Required flags
+*   `--blimp-client-token-path=$PATH`: Path to a file containing a nonempty
+token string. If this is not present, the engine will fail to boot.
diff --git a/blimp/engine/Dockerfile b/blimp/engine/Dockerfile
index d939115..732ceae 100644
--- a/blimp/engine/Dockerfile
+++ b/blimp/engine/Dockerfile
@@ -18,8 +18,9 @@ RUN chown -R blimp_user /engine
 USER blimp_user
 WORKDIR "/engine"
 
-ENTRYPOINT ["/engine/blimp_engine_app", "--disable-gpu", \
-                                        "--use-remote-compositing", \
-                                        # Retains display items for
-                                        # serialization on the engine.
-                                        "--disable-cached-picture-raster"]
+ENTRYPOINT ["/engine/blimp_engine_app", \
+                "--disable-gpu", \
+                "--use-remote-compositing", \
+                # Retains display items for serialization on the engine.
+                "--disable-cached-picture-raster", \
+                "--blimp-client-token-path=/engine/data/client_token"]
diff --git a/blimp/engine/browser/BUILD.gn b/blimp/engine/browser/BUILD.gn
index 3539896..4fa99ba 100644
--- a/blimp/engine/browser/BUILD.gn
+++ b/blimp/engine/browser/BUILD.gn
@@ -10,6 +10,8 @@ source_set("browser") {
     "blimp_browser_main_parts.h",
     "blimp_content_browser_client.cc",
     "blimp_content_browser_client.h",
+    "blimp_engine_config.cc",
+    "blimp_engine_config.h",
     "blimp_engine_session.cc",
     "blimp_engine_session.h",
     "blimp_network_delegate.cc",
@@ -20,6 +22,8 @@ source_set("browser") {
     "blimp_url_request_context_getter.h",
     "engine_render_widget_feature.cc",
     "engine_render_widget_feature.h",
+    "switches.cc",
+    "switches.h",
   ]
 
   deps = [
@@ -44,6 +48,7 @@ source_set("unit_tests") {
   testonly = true
 
   sources = [
+    "blimp_engine_config_unittest.cc",
     "engine_render_widget_feature_unittest.cc",
   ]
 
diff --git a/blimp/engine/browser/blimp_browser_main_parts.cc b/blimp/engine/browser/blimp_browser_main_parts.cc
index ad20a38..c35d694 100644
--- a/blimp/engine/browser/blimp_browser_main_parts.cc
+++ b/blimp/engine/browser/blimp_browser_main_parts.cc
@@ -4,8 +4,11 @@
 
 #include "blimp/engine/browser/blimp_browser_main_parts.h"
 
+#include "base/command_line.h"
+#include "base/threading/thread_restrictions.h"
 #include "blimp/common/proto/blimp_message.pb.h"
 #include "blimp/engine/browser/blimp_browser_context.h"
+#include "blimp/engine/browser/blimp_engine_config.h"
 #include "blimp/engine/browser/blimp_engine_session.h"
 #include "blimp/net/blimp_connection.h"
 #include "content/public/browser/browser_thread.h"
@@ -30,6 +33,15 @@ void BlimpBrowserMainParts::PreEarlyInitialization() {
   // TODO(haibinlu): Rename the method below. crbug/548330.
   ui::InitializeInputMethodForTesting();
 #endif
+  // Fetch the engine config from the command line, and crash if invalid. Allow
+  // IO operations even though this is not in the FILE thread as this is
+  // necessary for Blimp startup and occurs before any user interaction.
+  {
+    const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    engine_config_ = BlimpEngineConfig::Create(*cmd_line);
+    CHECK(engine_config_);
+  }
 }
 
 void BlimpBrowserMainParts::PreMainMessageLoopRun() {
diff --git a/blimp/engine/browser/blimp_browser_main_parts.h b/blimp/engine/browser/blimp_browser_main_parts.h
index 3e42a3a..803ac79 100644
--- a/blimp/engine/browser/blimp_browser_main_parts.h
+++ b/blimp/engine/browser/blimp_browser_main_parts.h
@@ -22,6 +22,7 @@ namespace blimp {
 namespace engine {
 
 class BlimpBrowserContext;
+class BlimpEngineConfig;
 class BlimpEngineSession;
 
 class BlimpBrowserMainParts : public content::BrowserMainParts {
@@ -37,6 +38,7 @@ class BlimpBrowserMainParts : public content::BrowserMainParts {
   BlimpBrowserContext* GetBrowserContext();
 
  private:
+  scoped_ptr<BlimpEngineConfig> engine_config_;
   scoped_ptr<net::NetLog> net_log_;
   scoped_ptr<BlimpEngineSession> engine_session_;
 
diff --git a/blimp/engine/browser/blimp_engine_config.cc b/blimp/engine/browser/blimp_engine_config.cc
new file mode 100644
index 0000000..da74bb7
--- /dev/null
+++ b/blimp/engine/browser/blimp_engine_config.cc
@@ -0,0 +1,59 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "blimp/engine/browser/blimp_engine_config.h"
+
+#include <string>
+
+#include "base/command_line.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string_util.h"
+#include "blimp/engine/browser/switches.h"
+
+namespace blimp {
+namespace engine {
+
+namespace {
+// Gets the client token from the file provided by the command line. If a read
+// does not succeed, or the switch is malformed, an empty string is returned.
+std::string GetClientToken(const base::CommandLine& cmd_line) {
+  std::string file_contents;
+  const base::FilePath path = cmd_line.GetSwitchValuePath(kClientTokenPath);
+  if (!base::ReadFileToString(path, &file_contents)) {
+    LOG(ERROR) << "Could not read client token file at "
+               << (path.empty() ? "(not provided)" : path.AsUTF8Unsafe());
+  }
+  return base::CollapseWhitespaceASCII(file_contents, true);
+}
+}  // namespace
+
+BlimpEngineConfig::~BlimpEngineConfig() {}
+
+// static
+scoped_ptr<BlimpEngineConfig> BlimpEngineConfig::Create(
+    const base::CommandLine& cmd_line) {
+  const std::string client_token = GetClientToken(cmd_line);
+  if (!client_token.empty()) {
+    return make_scoped_ptr(new BlimpEngineConfig(client_token));
+  }
+  return nullptr;
+}
+
+// static
+scoped_ptr<BlimpEngineConfig> BlimpEngineConfig::CreateForTest(
+    const std::string& client_token) {
+  return make_scoped_ptr(new BlimpEngineConfig(client_token));
+}
+
+const std::string& BlimpEngineConfig::client_token() const {
+  return client_token_;
+}
+
+BlimpEngineConfig::BlimpEngineConfig(const std::string& client_token)
+    : client_token_(client_token) {}
+
+}  // namespace engine
+}  // namespace blimp
diff --git a/blimp/engine/browser/blimp_engine_config.h b/blimp/engine/browser/blimp_engine_config.h
new file mode 100644
index 0000000..0c46b9f
--- /dev/null
+++ b/blimp/engine/browser/blimp_engine_config.h
@@ -0,0 +1,58 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BLIMP_ENGINE_BROWSER_BLIMP_ENGINE_CONFIG_H_
+#define BLIMP_ENGINE_BROWSER_BLIMP_ENGINE_CONFIG_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace base {
+class CommandLine;
+}  // namespace base
+
+namespace blimp {
+namespace engine {
+
+// Class to hold all of the configuration bits necessary for the Blimp engine.
+//
+// The BlimpEngineConfig class is initialized from parameters provided on the
+// command line. For the switches to pass verification:
+//   * A client token filepath must be provided and the file must have a
+//     non-empty token.
+//
+// The BlimpEngineConfig object is intended to live as long as the engine is
+// running. It should also be one of the first things to be set up.
+class BlimpEngineConfig {
+ public:
+  ~BlimpEngineConfig();
+
+  // Attempts to create a BlimpEngineConfig based on the parameters in the
+  // specified CommandLine. This validates all of the command line switches
+  // and parses all files specified. Returns a non-null scoped_ptr on success.
+  static scoped_ptr<BlimpEngineConfig> Create(
+      const base::CommandLine& cmd_line);
+
+  // Creates a BlimpEngineConfig based on individual components. Should only
+  // be used for testing.
+  static scoped_ptr<BlimpEngineConfig> CreateForTest(
+      const std::string& client_token);
+
+  // Returns the client token.
+  const std::string& client_token() const;
+
+ private:
+  explicit BlimpEngineConfig(const std::string& client_token);
+
+  const std::string client_token_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlimpEngineConfig);
+};
+
+}  // namespace engine
+}  // namespace blimp
+
+#endif  // BLIMP_ENGINE_BROWSER_BLIMP_ENGINE_CONFIG_H_
diff --git a/blimp/engine/browser/blimp_engine_config_unittest.cc b/blimp/engine/browser/blimp_engine_config_unittest.cc
new file mode 100644
index 0000000..2268a56
--- /dev/null
+++ b/blimp/engine/browser/blimp_engine_config_unittest.cc
@@ -0,0 +1,86 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "blimp/engine/browser/blimp_engine_config.h"
+
+#include <string>
+#include <vector>
+
+#include "base/command_line.h"
+#include "base/files/file_util.h"
+#include "base/files/scoped_temp_dir.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/stringprintf.h"
+#include "blimp/engine/browser/switches.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blimp {
+namespace engine {
+namespace {
+
+// Reference client token.
+static const char kTestClientToken[] = "Reference client token";
+
+class BlimpEngineConfigTest : public testing::Test {
+ protected:
+  void SetUp() override {
+    // Create a temporary directory and populate it with all of the switches
+    // If a test requires a switch's file to be missing, call
+    // RemoveFileForSwitch().
+    ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
+    CreateFileForSwitch(kClientTokenPath, kTestClientToken);
+  }
+
+  // Creates a file in the temp directory for a given filepath switch.
+  void CreateFileForSwitch(const std::string& filepath_switch,
+                           const std::string& data) const {
+    ASSERT_TRUE(base::WriteFile(GetFilepathForSwitch(filepath_switch),
+                                data.c_str(), data.size()));
+  }
+
+  // Removes the associated file for a given filepath switch.
+  void RemoveFileForSwitch(const std::string& filepath_switch) const {
+    base::DeleteFile(GetFilepathForSwitch(filepath_switch), false);
+  }
+
+  // Creates and returns a CommandLine object with specified filepath switches.
+  base::CommandLine CreateCommandLine(
+      const std::vector<std::string>& filepath_switches) {
+    base::CommandLine::StringVector cmd_vec = {"dummy_program"};
+    for (const std::string& filepath_switch : filepath_switches) {
+      cmd_vec.push_back(base::StringPrintf(
+          "--%s=%s", filepath_switch.c_str(),
+          GetFilepathForSwitch(filepath_switch).AsUTF8Unsafe().c_str()));
+    }
+    return base::CommandLine(cmd_vec);
+  }
+
+  base::FilePath GetFilepathForSwitch(
+      const std::string& filepath_switch) const {
+    return temp_dir_.path().Append(filepath_switch);
+  }
+
+  const std::vector<std::string> all_filepath_switches_ = {kClientTokenPath};
+
+  base::ScopedTempDir temp_dir_;
+};
+
+TEST_F(BlimpEngineConfigTest, ClientTokenCorrect) {
+  auto cmd_line = CreateCommandLine(all_filepath_switches_);
+  auto engine_config = BlimpEngineConfig::Create(cmd_line);
+  EXPECT_NE(nullptr, engine_config);
+  EXPECT_EQ(kTestClientToken, engine_config->client_token());
+}
+
+TEST_F(BlimpEngineConfigTest, ClientTokenEmpty) {
+  RemoveFileForSwitch(kClientTokenPath);
+  CreateFileForSwitch(kClientTokenPath, " ");
+  auto cmd_line = CreateCommandLine(all_filepath_switches_);
+  auto engine_config = BlimpEngineConfig::Create(cmd_line);
+  EXPECT_EQ(nullptr, engine_config);
+}
+
+}  // namespace
+}  // namespace engine
+}  // namespace blimp
diff --git a/blimp/engine/browser/switches.cc b/blimp/engine/browser/switches.cc
new file mode 100644
index 0000000..3aca1f7
--- /dev/null
+++ b/blimp/engine/browser/switches.cc
@@ -0,0 +1,13 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "blimp/engine/browser/switches.h"
+
+namespace blimp {
+namespace engine {
+
+const char kClientTokenPath[] = "blimp-client-token-path";
+
+}  // namespace engine
+}  // namespace blimp
diff --git a/blimp/engine/browser/switches.h b/blimp/engine/browser/switches.h
new file mode 100644
index 0000000..07096ff
--- /dev/null
+++ b/blimp/engine/browser/switches.h
@@ -0,0 +1,17 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BLIMP_ENGINE_BROWSER_SWITCHES_H_
+#define BLIMP_ENGINE_BROWSER_SWITCHES_H_
+
+namespace blimp {
+namespace engine {
+
+// Path to the client token/shared secret between the engine and the client.
+extern const char kClientTokenPath[];
+
+}  // namespace engine
+}  // namespace blimp
+
+#endif  // BLIMP_ENGINE_BROWSER_SWITCHES_H_