Initial skeletal implementation of the PrincipalService. Also, use the Login()/GetUserBlessing()

examples/bank_app/bank.cc

Index: examples/bank_app/bank.cc
diff --git a/examples/bank_app/bank.cc b/examples/bank_app/bank.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a051cfcc6de51f03b840eb3d0f2747431918abfa
--- /dev/null
+++ b/examples/bank_app/bank.cc
@@ -0,0 +1,96 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.

[jamesr, 2015/08/17 21:38:21]

2015

[gautham, 2015/08/18 01:54:21]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "examples/bank_app/bank.mojom.h"
+#include "mojo/common/binding_set.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_connection.h"
+#include "mojo/public/cpp/application/application_delegate.h"
+#include "mojo/public/cpp/application/application_impl.h"
+#include "mojo/public/cpp/application/application_runner.h"
+#include "mojo/public/cpp/application/interface_factory.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "mojo/public/cpp/utility/run_loop.h"
+#include "mojo/services/vanadium/security/public/interfaces/principal.mojom.h"
+
+namespace mojo {
+namespace examples {
+
+class BankImpl : public Bank {
+ public:
+  BankImpl() : balance_(0) {}
+  void Deposit(const int32_t usd) override { balance_ += usd; }

[jamesr, 2015/08/17 21:38:21]

drop the 'const' - the body is trivial enough that you can tell you aren't
modifying it in the body of the function

[gautham, 2015/08/18 01:54:21]

Done.

+  void Withdraw(const int32_t usd) override { balance_ -= usd; }
+  void GetBalance(const GetBalanceCallback& callback) override {
+    callback.Run(balance_);
+  }
+ private:
+  int32_t balance_;
+};
+
+class BankUser {
+ public:
+  BankUser(std::string* user) : user_(user) { }

[jamesr, 2015/08/17 21:38:21]

add explicit keyword to one-argument constructor

[gautham, 2015/08/18 01:54:21]

Done.

+  void Run(const BlessingPtr& b) const {
+    user_->clear();
+    if (b.get()) {
+      for (size_t i = 0; i < b.get()->chain.size(); i++) {
+        user_->append("/");
+        user_->append(b.get()->chain[i].get()->extension);
+      }
+    }
+    RunLoop::current()->Quit();  // All done!
+  }
+ private:
+  mutable std::string *user_;

[jamesr, 2015/08/17 21:38:21]

you aren't modifying the pointer value, just the pointed-to value, so you should
be able to drop the mutable

[gautham, 2015/08/18 01:54:21]

Done.

+};
+
+class BankApp : public mojo::ApplicationDelegate,
+                public mojo::InterfaceFactory<Bank> {
+ public:
+  BankApp() {
+  }
+  void Initialize(ApplicationImpl* app) override {
+    app->ConnectToService("mojo:principal_service", &login_service_);
+  }
+
+  // From ApplicationDelegate
+  bool ConfigureIncomingConnection(
+      mojo::ApplicationConnection* connection) override {
+    std::string url = connection->GetRemoteApplicationURL();
+    if (url.length() > 0) {

[jamesr, 2015/08/17 21:38:21]

what is this branch for?

[gautham, 2015/08/18 01:54:21]

I reject connection requests from customers that have not logged in. Doesn't the
shell also connect to the app through this call and it won't have a user
identity?

+      AppInstanceNamePtr app(AppInstanceName::New());
+      app->url = url;
+      std::string user;
+      login_service_->GetUserBlessing(app.Pass(), BankUser(&user));
+      login_service_.WaitForIncomingResponse();

[jamesr, 2015/08/17 21:38:21]

why is this blocking? you should probably check the return value explicitly and
do something if it returns false (meaning the pipe closed before you got a
response value)

[gautham, 2015/08/18 01:54:21]

I wanted to reject connection requests from customers that don't have a user
identity (ie: have not called Login()). Is there a better way to do this?

+      // Record user access to the bank and reject customers that
+      // don't have a user identity.
+      if (user.length() <= 0) {

[jamesr, 2015/08/17 21:38:21]

std::string::length() returns a size_t, which is unsigned, so this is equivalent
to == 0.  use .empty() instead

[gautham, 2015/08/18 01:54:21]

Done.

+        return false;
+      }
+      MOJO_LOG(INFO) << "Customer " << user << " accessing bank";
+    }
+    connection->AddService<Bank>(this);
+    return true;
+  }
+
+  void Create(mojo::ApplicationConnection* connection,
+              mojo::InterfaceRequest<Bank> request) override {
+    bindings_.AddBinding(&bank_impl_, request.Pass());
+  }
+
+ private:
+  BankImpl bank_impl_;
+  mojo::BindingSet<Bank> bindings_;
+  PrincipalServicePtr login_service_;
+};
+
+}  // namespace examples
+}  // namespace mojo
+
+MojoResult MojoMain(MojoHandle application_request) {
+  mojo::ApplicationRunner runner(new mojo::examples::BankApp());
+  return runner.Run(application_request);
+}