ipc/ipc_channel.cc

   1 // Copyright (c) 2012 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 "ipc/ipc_channel.h"
   6
   7 #include <limits>
   8
   9 #include "base/atomic_sequence_num.h"
  10 #include "base/rand_util.h"
  11 #include "base/strings/stringprintf.h"
  12
  13 namespace {
  14
  15 // Global atomic used to guarantee channel IDs are unique.
  16 base::StaticAtomicSequenceNumber g_last_id;
  17
  18 }  // namespace
  19
  20 namespace IPC {
  21
  22 // static
  23 std::string Channel::GenerateUniqueRandomChannelID() {
  24   // Note: the string must start with the current process id, this is how
  25   // some child processes determine the pid of the parent.
  26   //
  27   // This is composed of a unique incremental identifier, the process ID of
  28   // the creator, an identifier for the child instance, and a strong random
  29   // component. The strong random component prevents other processes from
  30   // hijacking or squatting on predictable channel names.
  31
  32 #if defined(OS_LINUX) || defined(OS_NACL_NONSFI)
  33   // On Linux platform, PID does not play any security role.
  34   // In nacl_helper_nonsfi, the seccomp sandbox disallows the use of getpid().
  35   // So, for both cases, we provide a dummy PID.
  36   int process_id = -1;
  37 #else
  38   int process_id = base::GetCurrentProcId();
  39 #endif
  40   return base::StringPrintf("%d.%u.%d",
  41       process_id,
  42       g_last_id.GetNext(),
  43       base::RandInt(0, std::numeric_limits<int32>::max()));
  44 }
  45
  46 }  // namespace IPC