1 files changed, 336 insertions, 0 deletions

diff --git a/mojo/edk/system/transport_data.cc b/mojo/edk/system/transport_data.cc
new file mode 100644
index 0000000..d751511
--- /dev/null
+++ b/mojo/edk/system/transport_data.cc
@@ -0,0 +1,336 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/edk/system/transport_data.h"
+
+#include "base/logging.h"
+#include "mojo/edk/system/configuration.h"
+#include "mojo/edk/system/message_in_transit.h"
+#include "mojo/edk/system/raw_channel.h"
+
+namespace mojo {
+namespace edk {
+
+// The maximum amount of space needed per platform handle.
+// (|{Channel,RawChannel}::GetSerializedPlatformHandleSize()| should always
+// return a value which is at most this. This is only used to calculate
+// |TransportData::kMaxBufferSize|. This value should be a multiple of the
+// alignment in order to simplify calculations, even though the actual amount of
+// space needed need not be a multiple of the alignment.
+const size_t kMaxSizePerPlatformHandle = 16;
+static_assert(kMaxSizePerPlatformHandle % MessageInTransit::kMessageAlignment ==
+                  0,
+              "kMaxSizePerPlatformHandle not a multiple of alignment");
+
+MOJO_STATIC_CONST_MEMBER_DEFINITION const size_t
+    TransportData::kMaxSerializedDispatcherSize;
+MOJO_STATIC_CONST_MEMBER_DEFINITION const size_t
+    TransportData::kMaxSerializedDispatcherPlatformHandles;
+
+// static
+size_t TransportData::GetMaxBufferSize() {
+  // In additional to the header, for each attached (Mojo) handle there'll be a
+  // handle table entry and serialized dispatcher data.
+  return sizeof(Header) +
+         GetConfiguration().max_message_num_handles *
+             (sizeof(HandleTableEntry) + kMaxSerializedDispatcherSize) +
+         GetMaxPlatformHandles() * kMaxSizePerPlatformHandle;
+}
+
+// static
+size_t TransportData::GetMaxPlatformHandles() {
+  return GetConfiguration().max_message_num_handles *
+         kMaxSerializedDispatcherPlatformHandles;
+}
+
+struct TransportData::PrivateStructForCompileAsserts {
+  static_assert(sizeof(Header) % MessageInTransit::kMessageAlignment == 0,
+                "sizeof(MessageInTransit::Header) not a multiple of alignment");
+  static_assert(kMaxSerializedDispatcherSize %
+                        MessageInTransit::kMessageAlignment ==
+                    0,
+                "kMaxSerializedDispatcherSize not a multiple of alignment");
+  static_assert(sizeof(HandleTableEntry) %
+                        MessageInTransit::kMessageAlignment ==
+                    0,
+                "sizeof(MessageInTransit::HandleTableEntry) not a multiple of "
+                "alignment");
+};
+
+TransportData::TransportData(scoped_ptr<DispatcherVector> dispatchers)
+    : buffer_size_() {
+  DCHECK(dispatchers);
+
+  const size_t num_handles = dispatchers->size();
+  DCHECK_GT(num_handles, 0u);
+
+  // The offset to the start of the (Mojo) handle table.
+  const size_t handle_table_start_offset = sizeof(Header);
+  // The offset to the start of the serialized dispatcher data.
+  const size_t serialized_dispatcher_start_offset =
+      handle_table_start_offset + num_handles * sizeof(HandleTableEntry);
+  // The estimated size of the secondary buffer. We compute this estimate below.
+  // It must be at least as big as the (eventual) actual size.
+  size_t estimated_size = serialized_dispatcher_start_offset;
+  size_t estimated_num_platform_handles = 0;
+#if DCHECK_IS_ON()
+  std::vector<size_t> all_max_sizes(num_handles);
+  std::vector<size_t> all_max_platform_handles(num_handles);
+#endif
+  for (size_t i = 0; i < num_handles; i++) {
+    if (Dispatcher* dispatcher = (*dispatchers)[i].get()) {
+      size_t max_size = 0;
+      size_t max_platform_handles = 0;
+      Dispatcher::TransportDataAccess::StartSerialize(
+          dispatcher, &max_size, &max_platform_handles);
+
+      DCHECK_LE(max_size, kMaxSerializedDispatcherSize);
+      estimated_size += MessageInTransit::RoundUpMessageAlignment(max_size);
+      DCHECK_LE(estimated_size, GetMaxBufferSize());
+
+      DCHECK_LE(max_platform_handles, kMaxSerializedDispatcherPlatformHandles);
+      estimated_num_platform_handles += max_platform_handles;
+      DCHECK_LE(estimated_num_platform_handles, GetMaxPlatformHandles());
+
+#if DCHECK_IS_ON()
+      all_max_sizes[i] = max_size;
+      all_max_platform_handles[i] = max_platform_handles;
+#endif
+    }
+  }
+
+  size_t size_per_platform_handle = 0;
+  if (estimated_num_platform_handles > 0) {
+    size_per_platform_handle = RawChannel::GetSerializedPlatformHandleSize();
+    DCHECK_LE(size_per_platform_handle, kMaxSizePerPlatformHandle);
+    estimated_size += estimated_num_platform_handles * size_per_platform_handle;
+    estimated_size = MessageInTransit::RoundUpMessageAlignment(estimated_size);
+    DCHECK_LE(estimated_size, GetMaxBufferSize());
+  }
+
+  buffer_.reset(static_cast<char*>(
+      base::AlignedAlloc(estimated_size, MessageInTransit::kMessageAlignment)));
+  // Entirely clear out the secondary buffer, since then we won't have to worry
+  // about clearing padding or unused space (e.g., if a dispatcher fails to
+  // serialize).
+  memset(buffer_.get(), 0, estimated_size);
+
+  if (estimated_num_platform_handles > 0) {
+    DCHECK(!platform_handles_);
+    platform_handles_.reset(new PlatformHandleVector());
+  }
+
+  Header* header = reinterpret_cast<Header*>(buffer_.get());
+  header->num_handles = static_cast<uint32_t>(num_handles);
+  // (Okay to leave |platform_handle_table_offset|, |num_platform_handles|, and
+  // |unused| be zero; we'll set the former two later if necessary.)
+
+  HandleTableEntry* handle_table = reinterpret_cast<HandleTableEntry*>(
+      buffer_.get() + handle_table_start_offset);
+  size_t current_offset = serialized_dispatcher_start_offset;
+  for (size_t i = 0; i < num_handles; i++) {
+    Dispatcher* dispatcher = (*dispatchers)[i].get();
+    if (!dispatcher) {
+      static_assert(static_cast<int32_t>(Dispatcher::Type::UNKNOWN) == 0,
+                    "Value of Dispatcher::Type::UNKNOWN must be 0");
+      continue;
+    }
+
+#if DCHECK_IS_ON()
+    size_t old_platform_handles_size =
+        platform_handles_ ? platform_handles_->size() : 0;
+#endif
+
+    void* destination = buffer_.get() + current_offset;
+    size_t actual_size = 0;
+    if (Dispatcher::TransportDataAccess::EndSerializeAndClose(
+            dispatcher, destination, &actual_size,
+            platform_handles_.get())) {
+      handle_table[i].type = static_cast<int32_t>(dispatcher->GetType());
+      handle_table[i].offset = static_cast<uint32_t>(current_offset);
+      handle_table[i].size = static_cast<uint32_t>(actual_size);
+// (Okay to not set |unused| since we cleared the entire buffer.)
+
+#if DCHECK_IS_ON()
+      DCHECK_LE(actual_size, all_max_sizes[i]);
+      DCHECK_LE(platform_handles_
+                    ? (platform_handles_->size() - old_platform_handles_size)
+                    : 0,
+                all_max_platform_handles[i]);
+#endif
+    } else {
+      // Nothing to do on failure, since |buffer_| was cleared, and
+      // |Type::UNKNOWN| is zero. The handle was simply closed.
+      LOG(ERROR) << "Failed to serialize handle to remote message pipe";
+    }
+
+    current_offset += MessageInTransit::RoundUpMessageAlignment(actual_size);
+    DCHECK_LE(current_offset, estimated_size);
+    DCHECK_LE(platform_handles_ ? platform_handles_->size() : 0,
+              estimated_num_platform_handles);
+  }
+
+  if (platform_handles_ && platform_handles_->size() > 0) {
+    header->platform_handle_table_offset =
+        static_cast<uint32_t>(current_offset);
+    header->num_platform_handles =
+        static_cast<uint32_t>(platform_handles_->size());
+    current_offset += platform_handles_->size() * size_per_platform_handle;
+    current_offset = MessageInTransit::RoundUpMessageAlignment(current_offset);
+  }
+
+  // There's no aligned realloc, so it's no good way to release unused space (if
+  // we overshot our estimated space requirements).
+  buffer_size_ = current_offset;
+
+  // |dispatchers_| will be destroyed as it goes out of scope.
+}
+
+TransportData::TransportData(
+    ScopedPlatformHandleVectorPtr platform_handles,
+    size_t serialized_platform_handle_size)
+    : buffer_size_(), platform_handles_(platform_handles.Pass()) {
+  buffer_size_ = MessageInTransit::RoundUpMessageAlignment(
+      sizeof(Header) +
+      platform_handles_->size() * serialized_platform_handle_size);
+  buffer_.reset(static_cast<char*>(
+      base::AlignedAlloc(buffer_size_, MessageInTransit::kMessageAlignment)));
+  memset(buffer_.get(), 0, buffer_size_);
+
+  Header* header = reinterpret_cast<Header*>(buffer_.get());
+  header->platform_handle_table_offset = static_cast<uint32_t>(sizeof(Header));
+  header->num_platform_handles =
+      static_cast<uint32_t>(platform_handles_->size());
+}
+
+TransportData::~TransportData() {
+}
+
+// static
+const char* TransportData::ValidateBuffer(
+    size_t serialized_platform_handle_size,
+    const void* buffer,
+    size_t buffer_size) {
+  DCHECK(buffer);
+  DCHECK_GT(buffer_size, 0u);
+
+  // Always make sure that the buffer size is sane; if it's not, someone's
+  // messing with us.
+  if (buffer_size < sizeof(Header) || buffer_size > GetMaxBufferSize() ||
+      buffer_size % MessageInTransit::kMessageAlignment != 0)
+    return "Invalid message secondary buffer size";
+
+  const Header* header = static_cast<const Header*>(buffer);
+  const size_t num_handles = header->num_handles;
+
+  // Sanity-check |num_handles| (before multiplying it against anything).
+  if (num_handles > GetConfiguration().max_message_num_handles)
+    return "Message handle payload too large";
+
+  if (buffer_size < sizeof(Header) + num_handles * sizeof(HandleTableEntry))
+    return "Message secondary buffer too small";
+
+  if (header->num_platform_handles == 0) {
+    // Then |platform_handle_table_offset| should also be zero.
+    if (header->platform_handle_table_offset != 0) {
+      return "Message has no handles attached, but platform handle table "
+             "present";
+    }
+  } else {
+    if (header->num_platform_handles >
+        GetConfiguration().max_message_num_handles *
+            kMaxSerializedDispatcherPlatformHandles)
+      return "Message has too many platform handles attached";
+
+    static const char kInvalidPlatformHandleTableOffset[] =
+        "Message has invalid platform handle table offset";
+    // This doesn't check that the platform handle table doesn't alias other
+    // stuff, but it doesn't matter, since it's all read-only.
+    if (header->platform_handle_table_offset %
+            MessageInTransit::kMessageAlignment !=
+        0)
+      return kInvalidPlatformHandleTableOffset;
+
+    // ">" instead of ">=" since the size per handle may be zero.
+    if (header->platform_handle_table_offset > buffer_size)
+      return kInvalidPlatformHandleTableOffset;
+
+    // We already checked |platform_handle_table_offset| and
+    // |num_platform_handles|, so the addition and multiplication are okay.
+    if (header->platform_handle_table_offset +
+            header->num_platform_handles * serialized_platform_handle_size >
+        buffer_size)
+      return kInvalidPlatformHandleTableOffset;
+  }
+
+  const HandleTableEntry* handle_table =
+      reinterpret_cast<const HandleTableEntry*>(
+          static_cast<const char*>(buffer) + sizeof(Header));
+  static const char kInvalidSerializedDispatcher[] =
+      "Message contains invalid serialized dispatcher";
+  for (size_t i = 0; i < num_handles; i++) {
+    size_t offset = handle_table[i].offset;
+    if (offset % MessageInTransit::kMessageAlignment != 0)
+      return kInvalidSerializedDispatcher;
+
+    size_t size = handle_table[i].size;
+    if (size > kMaxSerializedDispatcherSize || size > buffer_size)
+      return kInvalidSerializedDispatcher;
+
+    // Note: This is an overflow-safe check for |offset + size > buffer_size|
+    // (we know that |size <= buffer_size| from the previous check).
+    if (offset > buffer_size - size)
+      return kInvalidSerializedDispatcher;
+  }
+
+  return nullptr;
+}
+
+// static
+void TransportData::GetPlatformHandleTable(const void* transport_data_buffer,
+                                           size_t* num_platform_handles,
+                                           const void** platform_handle_table) {
+  DCHECK(transport_data_buffer);
+  DCHECK(num_platform_handles);
+  DCHECK(platform_handle_table);
+
+  const Header* header = static_cast<const Header*>(transport_data_buffer);
+  *num_platform_handles = header->num_platform_handles;
+  *platform_handle_table = static_cast<const char*>(transport_data_buffer) +
+                           header->platform_handle_table_offset;
+}
+
+// static
+scoped_ptr<DispatcherVector> TransportData::DeserializeDispatchers(
+    const void* buffer,
+    size_t buffer_size,
+    ScopedPlatformHandleVectorPtr platform_handles) {
+  DCHECK(buffer);
+  DCHECK_GT(buffer_size, 0u);
+
+  const Header* header = static_cast<const Header*>(buffer);
+  const size_t num_handles = header->num_handles;
+  scoped_ptr<DispatcherVector> dispatchers(new DispatcherVector(num_handles));
+
+  const HandleTableEntry* handle_table =
+      reinterpret_cast<const HandleTableEntry*>(
+          static_cast<const char*>(buffer) + sizeof(Header));
+  for (size_t i = 0; i < num_handles; i++) {
+    size_t offset = handle_table[i].offset;
+    size_t size = handle_table[i].size;
+    // Should already have been checked by |ValidateBuffer()|:
+    DCHECK_EQ(offset % MessageInTransit::kMessageAlignment, 0u);
+    DCHECK_LE(offset, buffer_size);
+    DCHECK_LE(offset + size, buffer_size);
+
+    const void* source = static_cast<const char*>(buffer) + offset;
+    (*dispatchers)[i] = Dispatcher::TransportDataAccess::Deserialize(
+        handle_table[i].type, source, size, platform_handles.get());
+  }
+
+  return dispatchers.Pass();
+}
+
+}  // namespace edk
+}  // namespace mojo