ipc/ipc_message.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_message.h"
   6
   7 #include <limits.h>
   8
   9 #include "base/atomic_sequence_num.h"
  10 #include "base/logging.h"
  11 #include "build/build_config.h"
  12 #include "ipc/ipc_message_attachment.h"
  13 #include "ipc/ipc_message_attachment_set.h"
  14
  15 #if defined(OS_POSIX)
  16 #include "base/file_descriptor_posix.h"
  17 #include "ipc/ipc_platform_file_attachment_posix.h"
  18 #endif
  19
  20 namespace {
  21
  22 base::StaticAtomicSequenceNumber g_ref_num;
  23
  24 // Create a reference number for identifying IPC messages in traces. The return
  25 // values has the reference number stored in the upper 24 bits, leaving the low
  26 // 8 bits set to 0 for use as flags.
  27 inline uint32_t GetRefNumUpper24() {
  28   base::trace_event::TraceLog* trace_log =
  29       base::trace_event::TraceLog::GetInstance();
  30   uint32_t pid = trace_log ? trace_log->process_id() : 0;
  31   uint32_t count = g_ref_num.GetNext();
  32   // The 24 bit hash is composed of 14 bits of the count and 10 bits of the
  33   // Process ID. With the current trace event buffer cap, the 14-bit count did
  34   // not appear to wrap during a trace. Note that it is not a big deal if
  35   // collisions occur, as this is only used for debugging and trace analysis.
  36   return ((pid << 14) | (count & 0x3fff)) << 8;
  37 }
  38
  39 }  // namespace
  40
  41 namespace IPC {
  42
  43 //------------------------------------------------------------------------------
  44
  45 Message::~Message() {
  46 }
  47
  48 Message::Message() : base::Pickle(sizeof(Header)) {
  49   header()->routing = header()->type = 0;
  50   header()->flags = GetRefNumUpper24();
  51 #if defined(OS_POSIX)
  52   header()->num_fds = 0;
  53   header()->pad = 0;
  54 #endif
  55   Init();
  56 }
  57
  58 Message::Message(int32_t routing_id, uint32_t type, PriorityValue priority)
  59     : base::Pickle(sizeof(Header)) {
  60   header()->routing = routing_id;
  61   header()->type = type;
  62   DCHECK((priority & 0xffffff00) == 0);
  63   header()->flags = priority | GetRefNumUpper24();
  64 #if defined(OS_POSIX)
  65   header()->num_fds = 0;
  66   header()->pad = 0;
  67 #endif
  68   Init();
  69 }
  70
  71 Message::Message(const char* data, int data_len)
  72     : base::Pickle(data, data_len) {
  73   Init();
  74 }
  75
  76 Message::Message(const Message& other) : base::Pickle(other) {
  77   Init();
  78   attachment_set_ = other.attachment_set_;
  79 }
  80
  81 void Message::Init() {
  82   dispatch_error_ = false;
  83   sender_pid_ = base::kNullProcessId;
  84 #ifdef IPC_MESSAGE_LOG_ENABLED
  85   received_time_ = 0;
  86   dont_log_ = false;
  87   log_data_ = NULL;
  88 #endif
  89 }
  90
  91 Message& Message::operator=(const Message& other) {
  92   *static_cast<base::Pickle*>(this) = other;
  93   attachment_set_ = other.attachment_set_;
  94   return *this;
  95 }
  96
  97 void Message::SetHeaderValues(int32_t routing, uint32_t type, uint32_t flags) {
  98   // This should only be called when the message is already empty.
  99   DCHECK(payload_size() == 0);
 100
 101   header()->routing = routing;
 102   header()->type = type;
 103   header()->flags = flags;
 104 }
 105
 106 void Message::EnsureMessageAttachmentSet() {
 107   if (attachment_set_.get() == NULL)
 108     attachment_set_ = new MessageAttachmentSet;
 109 }
 110
 111 #ifdef IPC_MESSAGE_LOG_ENABLED
 112 void Message::set_sent_time(int64_t time) {
 113   DCHECK((header()->flags & HAS_SENT_TIME_BIT) == 0);
 114   header()->flags |= HAS_SENT_TIME_BIT;
 115   WriteInt64(time);
 116 }
 117
 118 int64_t Message::sent_time() const {
 119   if ((header()->flags & HAS_SENT_TIME_BIT) == 0)
 120     return 0;
 121
 122   const char* data = end_of_payload();
 123   data -= sizeof(int64_t);
 124   return *(reinterpret_cast<const int64_t*>(data));
 125 }
 126
 127 void Message::set_received_time(int64_t time) const {
 128   received_time_ = time;
 129 }
 130 #endif
 131
 132 Message::NextMessageInfo::NextMessageInfo()
 133     : message_found(false), pickle_end(nullptr), message_end(nullptr) {}
 134 Message::NextMessageInfo::~NextMessageInfo() {}
 135
 136 // static
 137 void Message::FindNext(const char* range_start,
 138                        const char* range_end,
 139                        NextMessageInfo* info) {
 140   DCHECK(info);
 141   const char* pickle_end =
 142       base::Pickle::FindNext(sizeof(Header), range_start, range_end);
 143   if (!pickle_end)
 144     return;
 145   info->pickle_end = pickle_end;
 146
 147 #if USE_ATTACHMENT_BROKER
 148   // The data is not copied.
 149   size_t pickle_len = static_cast<size_t>(pickle_end - range_start);
 150   Message message(range_start, static_cast<int>(pickle_len));
 151   int num_attachments = message.header()->num_brokered_attachments;
 152
 153   // Check for possible overflows.
 154   size_t max_size_t = std::numeric_limits<size_t>::max();
 155   if (num_attachments >= max_size_t / BrokerableAttachment::kNonceSize)
 156     return;
 157
 158   size_t attachment_length = num_attachments * BrokerableAttachment::kNonceSize;
 159   if (pickle_len > max_size_t - attachment_length)
 160     return;
 161
 162   // Check whether the range includes the attachments.
 163   size_t buffer_length = static_cast<size_t>(range_end - range_start);
 164   if (buffer_length < attachment_length + pickle_len)
 165     return;
 166
 167   for (int i = 0; i < num_attachments; ++i) {
 168     const char* attachment_start =
 169         pickle_end + i * BrokerableAttachment::kNonceSize;
 170     BrokerableAttachment::AttachmentId id(attachment_start,
 171                                           BrokerableAttachment::kNonceSize);
 172     info->attachment_ids.push_back(id);
 173   }
 174   info->message_end =
 175       pickle_end + num_attachments * BrokerableAttachment::kNonceSize;
 176 #else
 177   info->message_end = pickle_end;
 178 #endif  // USE_ATTACHMENT_BROKER
 179
 180   info->message_found = true;
 181 }
 182
 183 bool Message::WriteAttachment(scoped_refptr<MessageAttachment> attachment) {
 184   // We write the index of the descriptor so that we don't have to
 185   // keep the current descriptor as extra decoding state when deserialising.
 186   WriteInt(attachment_set()->size());
 187   return attachment_set()->AddAttachment(attachment);
 188 }
 189
 190 bool Message::ReadAttachment(
 191     base::PickleIterator* iter,
 192     scoped_refptr<MessageAttachment>* attachment) const {
 193   int descriptor_index;
 194   if (!iter->ReadInt(&descriptor_index))
 195     return false;
 196
 197   MessageAttachmentSet* attachment_set = attachment_set_.get();
 198   if (!attachment_set)
 199     return false;
 200
 201   *attachment = attachment_set->GetAttachmentAt(descriptor_index);
 202   return nullptr != attachment->get();
 203 }
 204
 205 bool Message::HasAttachments() const {
 206   return attachment_set_.get() && !attachment_set_->empty();
 207 }
 208
 209 bool Message::HasMojoHandles() const {
 210   return attachment_set_.get() && attachment_set_->num_mojo_handles() > 0;
 211 }
 212
 213 bool Message::HasBrokerableAttachments() const {
 214   return attachment_set_.get() &&
 215          attachment_set_->num_brokerable_attachments() > 0;
 216 }
 217
 218 }  // namespace IPC