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 <stdint.h>
   8
   9 #include <limits>
  10
  11 #include "base/atomic_sequence_num.h"
  12 #include "base/rand_util.h"
  13 #include "base/strings/stringprintf.h"
  14
  15 namespace {
  16
  17 // Global atomic used to guarantee channel IDs are unique.
  18 base::StaticAtomicSequenceNumber g_last_id;
  19
  20 }  // namespace
  21
  22 namespace IPC {
  23
  24 // static
  25 std::string Channel::GenerateUniqueRandomChannelID() {
  26   // Note: the string must start with the current process id, this is how
  27   // some child processes determine the pid of the parent.
  28   //
  29   // This is composed of a unique incremental identifier, the process ID of
  30   // the creator, an identifier for the child instance, and a strong random
  31   // component. The strong random component prevents other processes from
  32   // hijacking or squatting on predictable channel names.
  33 #if defined(OS_NACL_NONSFI)
  34   // The seccomp sandbox disallows use of getpid(), so we provide a
  35   // 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_t>::max()));
  44 }
  45
  46 Channel::OutputElement::OutputElement(Message* message)
  47     : message_(message), buffer_(nullptr), length_(0) {}
  48
  49 Channel::OutputElement::OutputElement(void* buffer, size_t length)
  50     : message_(nullptr), buffer_(buffer), length_(length) {}
  51
  52 Channel::OutputElement::~OutputElement() {
  53   free(buffer_);
  54 }
  55
  56 }  // namespace IPC