Introduce RegistrationServer.

handler/win/registration_server.cc

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// 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 "handler/win/registration_server.h"
+
+#include <string.h>
+#include <vector>
+
+#include "base/logging.h"
+#include "base/strings/utf_string_conversions.h"
+#include "client/registration_protocol_win.h"
+#include "util/stdlib/pointer_container.h"
+
+namespace crashpad {
+
+namespace {
+
+// Invokes GetNamedPipeClientProcessId if available (Vista+). Returns true if
+// the method is unavailable or completes successfully. Returns false if an
+// error occurs.
+// If the method is unavailable process_id will be set to 0.
+bool TryGetNamedPipeClientProcessId(HANDLE pipe, DWORD* process_id) {
+  bool result = false;
+
+  HMODULE kernel_dll = LoadLibrary(L"kernel32.dll");
+  if (kernel_dll) {
+    decltype(GetNamedPipeClientProcessId)* proc =
+        reinterpret_cast<decltype(GetNamedPipeClientProcessId)*>(
+            GetProcAddress(kernel_dll, "GetNamedPipeClientProcessId"));
+    if (!proc) {
+      *process_id = 0;
+      result = true;
+    } else {
+      result = proc(pipe, process_id);
+    }
+    FreeLibrary(kernel_dll);
+  }
+  return result;
+}
+
+// Implements the state and state transitions for a single pipe instance.
+class PipeState {
+ public:
+  // Instantiates an instance that will operate on |pipe| and handle requests
+  // using |delegate|. The client must call Start() before clients may connect
+  // to this pipe.
+  PipeState(ScopedFileHANDLE pipe, RegistrationServer::Delegate* delegate);
+  ~PipeState();
+
+  // Places the pipe in the running state, ready to receive and process client
+  // connections. Returns true if successful, in which case the client must
+  // observe completion_event() and invoke OnCompletion() whenever it is
+  // signaled.
+  // Before destroying a running PipeState instance you must invoke Stop() and
+  // then wait for completion_event() to be signaled one last time.
+  bool Start();

[scottmg, 2015/05/21 02:32:36]

Consider if you prefer Initialize() for this function instead of Start() --
Initialize is commonly used in Crashpad, but I understand the desire for
symmetry with Stop() too.

[erikwright (departed), 2015/05/21 15:12:38]

Done.

+
+  // Cancels any pending asynchronous operations. After invoking this method you
+  // must wait for completion_event() to be signaled before destroying the
+  // instance.
+  void Stop();
+
+  // Returns an event handle that will be signaled whenever an asynchronous
+  // operation associated with this instance completes.
+  HANDLE completion_event() { return event_.get(); }
+
+  // Must be called by the client whenever completion_event() is signaled.
+  // Returns true if the pipe is still in the running state. Otherwise, a
+  // permanent failure has occurred and the instance may be immediately
+  // destroyed.
+  bool OnCompletion();
+
+ private:
+  typedef bool (PipeState::*AsyncCompletionHandler)(DWORD bytes_transferred);
+
+  // State transition handlers. Return true if the pipe is still valid.
+  bool OnConnectComplete(DWORD /* bytes_transferred */);
+  bool OnReadComplete(DWORD bytes_transferred);
+  bool OnWriteComplete(DWORD bytes_transferred);
+
+  // Pipe operations. Return true if the pipe is still valid.
+  bool IssueConnect();
+  bool IssueRead();
+  bool IssueWrite();
+  bool HandleRequest();
+  bool ResetConnection();
+
+  RegistrationRequest request_;
+  RegistrationResponse response_;
+  // The state transition handler to be invoked when the active asynchronous
+  // operation completes.
+  AsyncCompletionHandler completion_handler_;
+  OVERLAPPED overlapped_;
+  ScopedKernelHANDLE event_;
+  ScopedFileHANDLE pipe_;
+  RegistrationServer::Delegate* delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(PipeState);
+};
+
+PipeState::PipeState(ScopedFileHANDLE pipe,
+                     RegistrationServer::Delegate* delegate)
+    : request_(),
+      response_(),
+      completion_handler_(nullptr),
+      overlapped_(),
+      event_(),
+      pipe_(pipe.Pass()),
+      delegate_(delegate) {
+}
+
+PipeState::~PipeState() {
+}
+
+bool PipeState::Start() {
+  DCHECK(!event_.is_valid());
+  DCHECK(pipe_.is_valid());
+
+  event_.reset(CreateEvent(nullptr, true, false, nullptr));
+
+  if (!event_.is_valid()) {
+    PLOG(ERROR);
+  } else {
+    overlapped_.hEvent = event_.get();
+    if (IssueConnect())
+      return true;
+  }
+
+  overlapped_.hEvent = nullptr;
+  event_.reset();
+  pipe_.reset();
+  completion_handler_ = nullptr;
+
+  return false;
+}
+
+void PipeState::Stop() {
+  DCHECK(pipe_.is_valid());
+  if (!CancelIo(pipe_.get()))
+    PLOG(FATAL);
+}
+
+bool PipeState::OnCompletion() {
+  AsyncCompletionHandler completion_handler = completion_handler_;
+  completion_handler_ = nullptr;
+
+  DWORD bytes_transferred = 0;
+  BOOL success = GetOverlappedResult(pipe_.get(),
+                                     &overlapped_,
+                                     &bytes_transferred,
+                                     false);  // do not wait

[scottmg, 2015/05/21 02:32:36]

"Do not wait."

[erikwright (departed), 2015/05/21 15:12:37]

Done.

+  ResetEvent(event_.get());
+  bool still_running = false;
+  if (!completion_handler) {
+    NOTREACHED();
+    still_running = ResetConnection();
+  } else if (!success) {
+    PLOG(ERROR);
+    still_running = ResetConnection();
+  } else {
+    still_running = (this->*completion_handler)(bytes_transferred);
+  }
+
+  if (!still_running) {
+    overlapped_.hEvent = nullptr;
+    event_.reset();
+    pipe_.reset();
+    completion_handler_ = nullptr;
+  } else {
+    DCHECK(completion_handler_);
+  }
+
+  return still_running;
+}
+
+bool PipeState::OnConnectComplete(DWORD /* bytes_transferred */) {
+  return IssueRead();
+}
+
+bool PipeState::OnReadComplete(DWORD bytes_transferred) {
+  if (bytes_transferred != sizeof(request_)) {
+    LOG(ERROR) << "Invalid message size: " << bytes_transferred;
+    return ResetConnection();
+  } else {
+    return HandleRequest();
+  }
+}
+
+bool PipeState::OnWriteComplete(DWORD bytes_transferred) {
+  if (bytes_transferred != sizeof(response_)) {
+    LOG(ERROR) << "Incomplete write operation. Bytes written: "
+               << bytes_transferred;
+  }
+  return ResetConnection();
+}
+
+bool PipeState::IssueConnect() {
+  if (ConnectNamedPipe(pipe_.get(), &overlapped_)) {
+    return OnConnectComplete(0);  // bytes_transferred (ignored)
+  } else {
+    DWORD result = GetLastError();
+    if (result == ERROR_PIPE_CONNECTED) {
+      return OnConnectComplete(0);  // bytes_transferred (ignored)
+    } else if (result == ERROR_IO_PENDING) {
+      completion_handler_ = &PipeState::OnConnectComplete;
+      return true;
+    } else {
+      PLOG(ERROR);
+      return false;
+    }
+  }
+}
+
+bool PipeState::IssueRead() {
+  DWORD bytes_read = 0;
+  if (ReadFile(pipe_.get(),
+               &request_,
+               sizeof(request_),
+               &bytes_read,
+               &overlapped_)) {
+    return OnReadComplete(bytes_read);
+  } else if (GetLastError() == ERROR_IO_PENDING) {
+    completion_handler_ = &PipeState::OnReadComplete;
+    return true;
+  } else {
+    PLOG(ERROR);
+    return ResetConnection();
+  }
+}
+
+bool PipeState::IssueWrite() {
+  DWORD bytes_written = 0;
+  if (WriteFile(pipe_.get(),
+                &response_,
+                sizeof(response_),
+                &bytes_written,
+                &overlapped_)) {
+    return OnWriteComplete(bytes_written);
+  } else if (GetLastError() == ERROR_IO_PENDING) {
+    completion_handler_ = &PipeState::OnWriteComplete;
+    return true;
+  } else {
+    PLOG(ERROR);
+    return ResetConnection();
+  }
+}
+
+bool PipeState::HandleRequest() {
+  // On Vista+ we can verify that the client is who they claim to be, thus
+  // preventing arbitrary processes from having us duplicate handles into other
+  // processes.
+  DWORD real_client_process_id = 0;
+  if (TryGetNamedPipeClientProcessId(pipe_.get(), &real_client_process_id)) {
+    if (real_client_process_id != 0 &&
+        real_client_process_id != request_.client_process_id) {
+      LOG(ERROR) << "Client process ID from request ("
+                 << request_.client_process_id
+                 << ") does not match pipe client process ID ("
+                 << real_client_process_id << ").";
+      return ResetConnection();
+    }
+  }
+
+  ScopedKernelHANDLE client_process(
+      OpenProcess(PROCESS_ALL_ACCESS, false, request_.client_process_id));
+  if (!client_process.is_valid()) {
+    if (ImpersonateNamedPipeClient(pipe_.get())) {
+      client_process.reset(
+          OpenProcess(PROCESS_ALL_ACCESS, false, request_.client_process_id));
+      RevertToSelf();
+    }
+  }
+
+  if (!client_process.is_valid()) {
+    LOG(ERROR) << "Failed to open client process.";
+    return ResetConnection();
+  }
+
+  memset(&response_, 0, sizeof(response_));
+
+  // Go through these temporaries to deal with the fact that
+  // RegistrationResponse members may not be aligned (which complicates passing
+  // pointers to them to RegisterClient).

[scottmg, 2015/05/21 02:32:36]

Good thought. I'm not sure it's necessary in a win/ file though.

[erikwright (departed), 2015/05/21 15:12:37]

I get compilation warnings if I pass the unaligned values, which would require
the use of __unaligned (https://msdn.microsoft.com/en-us/library/ms177389.aspx)

Potentially it makes sense to disable the warnings?

[scottmg, 2015/05/21 16:17:35]

Interesting, I didn't know that! What you have seems good then.

+  HANDLE request_report_event = nullptr;
+  HANDLE report_complete_event = nullptr;
+
+  if (!delegate_->RegisterClient(client_process.Pass(),
+                                 request_.crashpad_info_address,
+                                 &request_report_event,
+                                 &report_complete_event)) {
+    return ResetConnection();
+  }
+  response_.request_report_event = request_report_event;
+  response_.report_complete_event = report_complete_event;
+  return IssueWrite();
+}
+
+bool PipeState::ResetConnection() {
+  memset(&request_, 0, sizeof(request_));
+
+  if (!DisconnectNamedPipe(pipe_.get())) {
+    PLOG(ERROR);
+    return false;
+  } else {
+    return IssueConnect();
+  }
+}
+
+}  // namespace
+
+RegistrationServer::RegistrationServer() : stop_event_() {
+  stop_event_.reset(CreateEvent(nullptr, false, false, nullptr));
+  DPCHECK(stop_event_.is_valid());
+}
+
+RegistrationServer::~RegistrationServer() {
+}
+
+void RegistrationServer::Run(const base::string16& pipe_name,
+                             Delegate* delegate) {
+  PointerVector<PipeState> pipes;
+  std::vector<HANDLE> handles;
+
+  const int kNumPipes = 3;
+
+  // Create the named pipes.
+  for (int i = 0; i < kNumPipes; ++i) {
+    DWORD open_mode = PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED;
+    if (pipes.size() == 0)
+      open_mode |= FILE_FLAG_FIRST_PIPE_INSTANCE;
+    ScopedFileHANDLE pipe(
+        CreateNamedPipe(pipe_name.c_str(),
+                        open_mode,
+                        PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
+                        kNumPipes,
+                        512,  // nOutBufferSize
+                        512,  // nInBufferSize
+                        20,  // nDefaultTimeOut
+                        nullptr));  // lpSecurityAttributes
+    if (pipe.is_valid()) {
+      scoped_ptr<PipeState> pipe_state(new PipeState(pipe.Pass(), delegate));
+      if (pipe_state->Start()) {
+        pipes.push_back(pipe_state.release());
+        handles.push_back(pipes.back()->completion_event());
+      }
+    } else {
+      PLOG(ERROR);
+    }
+  }
+
+  if (pipes.size() == 0)
+    return;
+
+  delegate->OnStarted();
+
+  // Add stop_event_ to the list of events we will observe.
+  handles.push_back(stop_event_.get());
+
+  // Run the main loop, dispatching completion event signals to the pipe
+  // instances.
+  while (true) {
+    DWORD wait_result = WaitForMultipleObjects(
+        static_cast<DWORD>(handles.size()), handles.data(), false, INFINITE);
+    if (wait_result >= WAIT_OBJECT_0 &&
+        wait_result < WAIT_OBJECT_0 + pipes.size()) {
+      int index = wait_result - WAIT_OBJECT_0;
+      // Handle a completion event.
+      if (!pipes[index]->OnCompletion()) {
+        pipes.erase(pipes.begin() + index);
+        handles.erase(handles.begin() + index);
+      }
+      if (pipes.size())
+        continue;
+      // Exit due to all pipes having failed.
+    } else if (wait_result == WAIT_OBJECT_0 + pipes.size()) {
+      // Exit due to stop_event_.
+    } else if (wait_result == WAIT_FAILED) {
+      // Exit due to error.
+      PLOG(ERROR);
+    } else {
+      // Exit due to unexpected return code.
+      NOTREACHED();
+    }
+    break;
+  }
+
+  // Remove |stop_event_| from the wait list.
+  handles.pop_back();
+
+  // Cancel any ongoing asynchronous operations.
+  for (auto& pipe : pipes) {
+    pipe->Stop();
+  }
+
+  // Wait until all of the pipe instances are ready to be destroyed.
+  DWORD wait_result = WaitForMultipleObjects(
+      static_cast<DWORD>(handles.size()), handles.data(), true, INFINITE);
+  PCHECK(wait_result != WAIT_FAILED);
+  DCHECK_GE(wait_result, WAIT_OBJECT_0);
+  DCHECK_LT(wait_result, WAIT_OBJECT_0 + handles.size());
+}
+
+void RegistrationServer::Stop() {
+  if (!SetEvent(stop_event_.get()))
+    PLOG(FATAL);
+}
+
+}  // namespace crashpad