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      1 // Copyright 2014 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "mojo/embedder/platform_channel_pair.h"
      6 
      7 #include <windows.h>
      8 
      9 #include <string>
     10 
     11 #include "base/command_line.h"
     12 #include "base/logging.h"
     13 #include "base/rand_util.h"
     14 #include "base/strings/string_number_conversions.h"
     15 #include "base/strings/stringprintf.h"
     16 #include "base/win/windows_version.h"
     17 #include "mojo/embedder/platform_handle.h"
     18 
     19 namespace mojo {
     20 namespace embedder {
     21 
     22 namespace {
     23 
     24 std::wstring GeneratePipeName() {
     25   return base::StringPrintf(L"\\\\.\\pipe\\mojo.%u.%u.%I64u",
     26                             GetCurrentProcessId(),
     27                             GetCurrentThreadId(),
     28                             base::RandUint64());
     29 }
     30 
     31 }  // namespace
     32 
     33 PlatformChannelPair::PlatformChannelPair() {
     34   std::wstring pipe_name = GeneratePipeName();
     35 
     36   const DWORD kOpenMode =
     37       PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED | FILE_FLAG_FIRST_PIPE_INSTANCE;
     38   const DWORD kPipeMode = PIPE_TYPE_BYTE | PIPE_READMODE_BYTE;
     39   server_handle_.reset(PlatformHandle(
     40       CreateNamedPipeW(pipe_name.c_str(),
     41                        kOpenMode,
     42                        kPipeMode,
     43                        1,           // Max instances.
     44                        4096,        // Out buffer size.
     45                        4096,        // In buffer size.
     46                        5000,        // Timeout in milliseconds.
     47                        nullptr)));  // Default security descriptor.
     48   PCHECK(server_handle_.is_valid());
     49 
     50   const DWORD kDesiredAccess = GENERIC_READ | GENERIC_WRITE;
     51   // The SECURITY_ANONYMOUS flag means that the server side cannot impersonate
     52   // the client.
     53   const DWORD kFlags =
     54       SECURITY_SQOS_PRESENT | SECURITY_ANONYMOUS | FILE_FLAG_OVERLAPPED;
     55   // Allow the handle to be inherited by child processes.
     56   SECURITY_ATTRIBUTES security_attributes = {sizeof(SECURITY_ATTRIBUTES),
     57                                              nullptr, TRUE};
     58   client_handle_.reset(
     59       PlatformHandle(CreateFileW(pipe_name.c_str(),
     60                                  kDesiredAccess,
     61                                  0,  // No sharing.
     62                                  &security_attributes,
     63                                  OPEN_EXISTING,
     64                                  kFlags,
     65                                  nullptr)));  // No template file.
     66   PCHECK(client_handle_.is_valid());
     67 
     68   // Since a client has connected, ConnectNamedPipe() should return zero and
     69   // GetLastError() should return ERROR_PIPE_CONNECTED.
     70   CHECK(!ConnectNamedPipe(server_handle_.get().handle, nullptr));
     71   PCHECK(GetLastError() == ERROR_PIPE_CONNECTED);
     72 }
     73 
     74 // static
     75 ScopedPlatformHandle PlatformChannelPair::PassClientHandleFromParentProcess(
     76     const base::CommandLine& command_line) {
     77   std::string client_handle_string =
     78       command_line.GetSwitchValueASCII(kMojoPlatformChannelHandleSwitch);
     79 
     80   int client_handle_value = 0;
     81   if (client_handle_string.empty() ||
     82       !base::StringToInt(client_handle_string, &client_handle_value)) {
     83     LOG(ERROR) << "Missing or invalid --" << kMojoPlatformChannelHandleSwitch;
     84     return ScopedPlatformHandle();
     85   }
     86 
     87   return ScopedPlatformHandle(
     88       PlatformHandle(LongToHandle(client_handle_value)));
     89 }
     90 
     91 void PlatformChannelPair::PrepareToPassClientHandleToChildProcess(
     92     base::CommandLine* command_line,
     93     base::HandlesToInheritVector* handle_passing_info) const {
     94   DCHECK(command_line);
     95   DCHECK(handle_passing_info);
     96   DCHECK(client_handle_.is_valid());
     97 
     98   CHECK_GE(base::win::GetVersion(), base::win::VERSION_VISTA);
     99 
    100   handle_passing_info->push_back(client_handle_.get().handle);
    101 
    102   // Log a warning if the command line already has the switch, but "clobber" it
    103   // anyway, since it's reasonably likely that all the switches were just copied
    104   // from the parent.
    105   LOG_IF(WARNING, command_line->HasSwitch(kMojoPlatformChannelHandleSwitch))
    106       << "Child command line already has switch --"
    107       << kMojoPlatformChannelHandleSwitch << "="
    108       << command_line->GetSwitchValueASCII(kMojoPlatformChannelHandleSwitch);
    109   // (Any existing switch won't actually be removed from the command line, but
    110   // the last one appended takes precedence.)
    111   command_line->AppendSwitchASCII(
    112       kMojoPlatformChannelHandleSwitch,
    113       base::IntToString(HandleToLong(client_handle_.get().handle)));
    114 }
    115 
    116 }  // namespace embedder
    117 }  // namespace mojo
    118