Generating CIDs in Blink during MHTML serialization.

third_party/WebKit/Source/web/WebPageSerializer.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 27 matching lines @@
 #include "core/html/HTMLAllCollection.h"
 #include "core/html/HTMLFrameElementBase.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLTableElement.h"
 #include "core/loader/DocumentLoader.h"
 #include "core/page/Page.h"
 #include "core/page/PageSerializer.h"
 #include "platform/SerializedResource.h"
 #include "platform/mhtml/MHTMLArchive.h"
+#include "platform/mhtml/MHTMLParser.h"
 #include "platform/weborigin/KURL.h"
 #include "public/platform/WebCString.h"
 #include "public/platform/WebString.h"
 #include "public/platform/WebURL.h"
 #include "public/platform/WebVector.h"
 #include "public/web/WebFrame.h"
 #include "public/web/WebPageSerializerClient.h"
 #include "public/web/WebView.h"
 #include "web/WebLocalFrameImpl.h"
 #include "web/WebPageSerializerImpl.h"
 #include "web/WebViewImpl.h"
+#include "wtf/Assertions.h"
+#include "wtf/HashMap.h"
 #include "wtf/Vector.h"
 #include "wtf/text/StringConcatenate.h"
 
 namespace blink {
 
 namespace {
 
 class MHTMLPageSerializerDelegate final : public PageSerializer::Delegate {
 public:
-    ~MHTMLPageSerializerDelegate() override;
+    MHTMLPageSerializerDelegate(HashMap<Frame*, String>* frameToContentID);
     bool shouldIgnoreAttribute(const Attribute&) override;
+    String rewriteLink(const Element&) override;
+private:
+    HashMap<Frame*, String>* m_frameToContentID;
 };
 
-
-MHTMLPageSerializerDelegate::~MHTMLPageSerializerDelegate()
+MHTMLPageSerializerDelegate::MHTMLPageSerializerDelegate(
+    HashMap<Frame*, String>* frameToContentID)
+    : m_frameToContentID(frameToContentID)
 {
 }
 
 bool MHTMLPageSerializerDelegate::shouldIgnoreAttribute(const Attribute& attribute)
 {
     // TODO(fgorski): Presence of srcset attribute causes MHTML to not display images, as only the value of src
     // is pulled into the archive. Discarding srcset prevents the problem. Long term we should make sure to MHTML
     // plays nicely with srcset.
     return attribute.localName() == HTMLNames::srcsetAttr;
 }
 
+String MHTMLPageSerializerDelegate::rewriteLink(const Element& element)
+{
+    if (!element.isFrameOwnerElement())
+        return String();
+
+    auto* frameOwnerElement = toHTMLFrameOwnerElement(&element);
+    Frame* frame = frameOwnerElement->contentFrame();
+    if (!frame)
+        return String();
+
+    KURL cidURI = MHTMLParser::convertContentIDToURI(m_frameToContentID->get(frame));
+    ASSERT(cidURI.isValid());
+
+    if (isHTMLFrameElementBase(&element))
+        return cidURI.string();
+
+    if (isHTMLObjectElement(&element)) {
+        Document* doc = frameOwnerElement->contentDocument();
+        bool isHandledBySerializer = doc->isHTMLDocument()
+            || doc->isXHTMLDocument() || doc->isImageDocument();
+        if (isHandledBySerializer)
+            return cidURI.string();
+    }
+
+    return String();
+}
+
 } // namespace
 
+static HashMap<Frame*, String> generateFrameContentIDs(Page* page)
+{
+    HashMap<Frame*, String> frameToContentID;
+    int frameID = 0;
+    for (Frame* frame = page->mainFrame(); frame; frame = frame->tree().traverseNext()) {
+        // TODO(lukasza): Move cid generation to the browser + use base/guid.h
+        // (see the draft at crrev.com/1386873003).
+        StringBuilder contentIDBuilder;
+        contentIDBuilder.appendLiteral("<frame");

[dcheng, 2015/11/25 18:41:53]

How about just leaving off the angle brackets here and letting generateMHTMLPart
insert them as needed? That way, convertContentIDToURI doesn't need to strip off
the angle brackets.

[Łukasz Anforowicz, 2015/11/25 19:16:49]

convertContentIDToURI strips the angle brackets, because they are present when
MHTMLParser reads the MHTML/Mime Content-ID headers.  

We could do the stripping in MHTMLParser / outside of convertContentIDToURI, but
it would mean that now we have 3 not 2 forms of content-id floating around:
1. <foo@bar.com>
2. cid:foo@bar.com
3. foo@bar.com

So - I think we might want to leave this aspect of the code as-is?

+        contentIDBuilder.appendNumber(frameID++);
+        contentIDBuilder.appendLiteral("@mhtml.blink>");
+
+        frameToContentID.add(frame, contentIDBuilder.toString());
+    }
+    return frameToContentID;
+}
+
 static PassRefPtr<SharedBuffer> serializePageToMHTML(Page* page, MHTMLArchive::EncodingPolicy encodingPolicy)
 {
     Vector<SerializedResource> resources;
-    PageSerializer serializer(&resources, adoptPtr(new MHTMLPageSerializerDelegate));
+    HashMap<Frame*, String> frameToContentID = generateFrameContentIDs(page);
+    MHTMLPageSerializerDelegate delegate(&frameToContentID);
+    PageSerializer serializer(&resources, &delegate);
 
     RefPtr<SharedBuffer> output = SharedBuffer::create();
     String boundary = MHTMLArchive::generateMHTMLBoundary();
 
     Document* document = page->deprecatedLocalMainFrame()->document();
     MHTMLArchive::generateMHTMLHeader(
         boundary, document->title(), document->suggestedMIMEType(), *output);
 
     for (Frame* frame = page->deprecatedLocalMainFrame(); frame; frame = frame->tree().traverseNext()) {
         // TODO(lukasza): This causes incomplete MHTML for OOPIFs.
         // (crbug.com/538766)
         if (!frame->isLocalFrame())
             continue;
 
         resources.clear();
         serializer.serializeFrame(*toLocalFrame(frame));
 
-        for (const auto& resource : resources) {
+        bool isFirstResource = true;
+        for (const SerializedResource& resource : resources) {
+            // Frame is the 1st resource (see PageSerializer::serializeFrame doc
+            // comment). Frames need a Content-ID header.
+            String contentID = isFirstResource ? frameToContentID.get(frame) : String();
+
             MHTMLArchive::generateMHTMLPart(
-                boundary, encodingPolicy, resource, *output);
+                boundary, contentID, encodingPolicy, resource, *output);
+
+            isFirstResource = false;
         }
     }
 
     MHTMLArchive::generateMHTMLFooter(boundary, *output);
     return output.release();
 }
 
 WebCString WebPageSerializer::serializeToMHTML(WebView* view)
 {
     RefPtr<SharedBuffer> mhtml = serializePageToMHTML(toWebViewImpl(view)->page(), MHTMLArchive::UseDefaultEncoding);
@@ skipping 38 matching lines @@
 WebString WebPageSerializer::generateBaseTagDeclaration(const WebString& baseTarget)
 {
     // TODO(yosin) We should call |PageSerializer::baseTagDeclarationOf()|.
     if (baseTarget.isEmpty())
         return String("<base href=\".\">");
     String baseString = "<base href=\".\" target=\"" + static_cast<const String&>(baseTarget) + "\">";
     return baseString;
 }
 
 } // namespace blink