IPC: Add attachment brokering support to the message header.

ipc/brokerable_attachment.cc

 // Copyright 2015 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 "ipc/brokerable_attachment.h"
 
+#include "ipc/attachment_broker.h"
+
+#if USE_ATTACHMENT_BROKER
 #include "crypto/random.h"
+#endif
 
 namespace IPC {
 
 namespace {
 
 // In order to prevent mutually untrusted processes from stealing resources from
 // one another, the nonce must be secret. This generates a 128-bit,
 // cryptographicaly-strong random number.
 BrokerableAttachment::AttachmentId GetRandomId() {
   BrokerableAttachment::AttachmentId id;
+#if USE_ATTACHMENT_BROKER
   crypto::RandBytes(id.nonce, BrokerableAttachment::kNonceSize);
+#endif
   return id;

[Tom Sepez, 2015/08/17 18:29:39]

nit: feels wrong to allow this to return a known key, even if not
USE_ATTACHMENT_BROKER.

[erikchen, 2015/08/18 05:59:46]

I agree. I've changed the no-parameter constructor to return a random nonce when
USE_ATTACHMENT_BROKER is true, and assert with CHECK(false) when
USE_ATTACHMENT_BROKER is false.

 }
 
 }  // namespace
 
-BrokerableAttachment::BrokerableAttachment()
-    : id_(GetRandomId()), needs_brokering_(false) {}
+// The size of the nonce array in AttachmentId must match kNonceSize.
+const size_t BrokerableAttachment::kNonceSize = 16;
 
-BrokerableAttachment::BrokerableAttachment(const AttachmentId& id,
-                                           bool needs_brokering)
-    : id_(id), needs_brokering_(needs_brokering) {}
+BrokerableAttachment::AttachmentId::AttachmentId(const char* start_address,
+                                                 size_t size) {
+  DCHECK_EQ(size, BrokerableAttachment::kNonceSize);
+  for (size_t i = 0; i < BrokerableAttachment::kNonceSize; ++i)
+    nonce[i] = start_address[i];
+}
 
-BrokerableAttachment::~BrokerableAttachment() {
+void BrokerableAttachment::AttachmentId::SerializeToBuffer(char* start_address,
+                                                           size_t size) {
+  DCHECK_EQ(size, BrokerableAttachment::kNonceSize);
+  for (size_t i = 0; i < BrokerableAttachment::kNonceSize; ++i)
+    start_address[i] = nonce[i];
 }
 
+bool BrokerableAttachment::AttachmentId::operator==(
+    const AttachmentId& rhs) const {
+  for (size_t i = 0; i < kNonceSize; ++i) {
+    if (nonce[i] != rhs.nonce[i])
+      return false;
+  }
+  return true;
+}
+
+bool BrokerableAttachment::AttachmentId::operator<(
+    const AttachmentId& rhs) const {
+  for (size_t i = 0; i < kNonceSize; ++i) {
+    if (nonce[i] < rhs.nonce[i])
+      return true;
+    if (nonce[i] > rhs.nonce[i])
+      return false;
+  }
+  return false;
+}
+
+BrokerableAttachment::BrokerableAttachment() : id_(GetRandomId()) {}
+
+BrokerableAttachment::BrokerableAttachment(const AttachmentId& id) : id_(id) {}
+
+BrokerableAttachment::~BrokerableAttachment() {}
+
 BrokerableAttachment::AttachmentId BrokerableAttachment::GetIdentifier() const {
   return id_;
 }
 
 bool BrokerableAttachment::NeedsBrokering() const {
-  return needs_brokering_;
-}
-
-void BrokerableAttachment::SetNeedsBrokering(bool needs_brokering) {
-  needs_brokering_ = needs_brokering;
+  return GetBrokerableType() == PLACEHOLDER;
 }
 
 BrokerableAttachment::Type BrokerableAttachment::GetType() const {
   return TYPE_BROKERABLE_ATTACHMENT;
 }
 
+#if defined(OS_POSIX)
+base::PlatformFile BrokerableAttachment::TakePlatformFile() {
+  NOTREACHED();
+  return base::PlatformFile();
+}
+#endif  // OS_POSIX
+
 }  // namespace IPC