[Fetch API] Implement Request.formData and Response.formData.

third_party/WebKit/Source/modules/fetch/FetchDataLoader.cpp

Index: third_party/WebKit/Source/modules/fetch/FetchDataLoader.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/FetchDataLoader.cpp b/third_party/WebKit/Source/modules/fetch/FetchDataLoader.cpp
index 1c2e04da558ed62ec689bb10c226fd58dd62e337..566724aa35787f35072ce509316df8d7aa2b1437 100644
--- a/third_party/WebKit/Source/modules/fetch/FetchDataLoader.cpp
+++ b/third_party/WebKit/Source/modules/fetch/FetchDataLoader.cpp
@@ -4,8 +4,13 @@
 
 #include "modules/fetch/FetchDataLoader.h"
 
+#include "core/fileapi/Blob.h"
+#include "core/html/FormData.h"
 #include "core/html/parser/TextResourceDecoder.h"
 #include "modules/fetch/BytesConsumer.h"
+#include "modules/fetch/MultipartParser.h"
+#include "platform/HTTPNames.h"
+#include "platform/network/ParsedContentType.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/text/StringBuilder.h"
 #include "wtf/text/WTFString.h"
@@ -168,6 +173,176 @@ private:
     std::unique_ptr<ArrayBufferBuilder> m_rawData;
 };
 
+class FetchDataLoaderAsFormData final : public FetchDataLoader, public BytesConsumer::Client, public MultipartParser::Client {
+    USING_GARBAGE_COLLECTED_MIXIN(FetchDataLoaderAsFormData);
+
+public:
+    explicit FetchDataLoaderAsFormData(const String& multipartBoundary)
+        : m_multipartBoundary(multipartBoundary)
+    {
+    }
+
+    void start(BytesConsumer* consumer, FetchDataLoader::Client* client) override
+    {
+        DCHECK(!m_client);
+        DCHECK(!m_multipartParser);
+        DCHECK(!m_consumer);
+
+        CString multipartBoundaryCString = m_multipartBoundary.utf8();

[horo, 2016/09/27 10:45:49]

nit: const

[e_hakkinen, 2016/09/28 15:15:04]

Done.

+        Vector<char> multipartBoundaryVector;
+        multipartBoundaryVector.append(multipartBoundaryCString.data(), multipartBoundaryCString.length());
+
+        m_client = client;
+        m_formData = FormData::create();
+        m_multipartParser = new MultipartParser(std::move(multipartBoundaryVector), this);
+        m_consumer = consumer;
+        m_consumer->setClient(this);
+        onStateChange();
+    }
+
+    void onStateChange() override
+    {
+        while (true) {
+            const char* buffer;
+            size_t available;
+            auto result = m_consumer->beginRead(&buffer, &available);
+            if (result == BytesConsumer::Result::ShouldWait)
+                return;
+            if (result == BytesConsumer::Result::Ok) {
+                bool bufferAppended = m_multipartParser->appendData(buffer, available);

[horo, 2016/09/27 10:45:49]

nit: const

[e_hakkinen, 2016/09/28 15:15:04]

Done.

+                bool multipartReceiveFailed = m_multipartParser->isCancelled();

[horo, 2016/09/27 10:45:49]

nit: const

[e_hakkinen, 2016/09/28 15:15:04]

Done.

+                result = m_consumer->endRead(available);
+                if (!bufferAppended || multipartReceiveFailed)
+                    result = BytesConsumer::Result::Error;
+            }
+            if (result == BytesConsumer::Result::Done) {
+                if (m_multipartParser->finish()) {

[yhirano, 2016/09/26 10:59:34]

Why don't you move this section into the below switch?

[e_hakkinen, 2016/09/28 15:15:04]

Maybe done. I am not if I understood correctly what you wanted me to do.

+                    DCHECK(!m_multipartParser->isCancelled());
+                    m_client->didFetchDataLoadedFormData(m_formData);
+                    return;
+                }
+                result = BytesConsumer::Result::Error;
+            }
+            switch (result) {
+            case BytesConsumer::Result::Ok:
+                break;
+            case BytesConsumer::Result::ShouldWait:
+            case BytesConsumer::Result::Done:
+                NOTREACHED();
+                return;
+            case BytesConsumer::Result::Error:
+                cancel();
+                m_client->didFetchDataLoadFailed();
+                return;
+            }
+        }
+    }
+
+    void cancel() override
+    {
+        m_consumer->cancel();
+        m_multipartParser->cancel();
+    }
+
+    DEFINE_INLINE_TRACE()
+    {
+        visitor->trace(m_consumer);
+        visitor->trace(m_client);
+        visitor->trace(m_formData);
+        visitor->trace(m_multipartParser);
+        FetchDataLoader::trace(visitor);
+        BytesConsumer::Client::trace(visitor);
+        MultipartParser::Client::trace(visitor);
+    }
+
+private:
+    void partHeaderFieldsInMultipartReceived(const ResourceResponse& response) override
+    {
+        if (!m_currentEntry.initialize(response))
+            m_multipartParser->cancel();
+    }
+
+    void partDataInMultipartReceived(const char* bytes, size_t size) override
+    {
+        if (!m_currentEntry.appendBytes(bytes, size))
+            m_multipartParser->cancel();
+    }
+
+    void partDataInMultipartFullyReceived() override
+    {
+        if (!m_currentEntry.finish(m_formData))
+            m_multipartParser->cancel();
+    }
+
+    class Entry {
+    public:
+        bool initialize(const ResourceResponse& response)
+        {
+            ParsedContentType disposition(response.httpHeaderField(HTTPNames::Content_Disposition));

[horo, 2016/09/27 10:45:50]

nit: const

[e_hakkinen, 2016/09/28 15:15:04]

Done.

+            String dispositionType = disposition.mimeType();

[horo, 2016/09/27 10:45:49]

nit: const

[e_hakkinen, 2016/09/28 15:15:04]

Done.

+            m_filename = disposition.parameterValueForName("filename");
+            m_name = disposition.parameterValueForName("name");
+            m_blobData.reset();
+            m_stringBuilder.reset();
+            if (dispositionType != "form-data" || m_name.isNull())
+                return false;
+            if (!m_filename.isNull()) {
+                m_blobData = BlobData::create();
+                m_blobData->setContentType(response.httpHeaderField(HTTPNames::Content_Type));
+            } else {

[yhirano, 2016/09/26 10:59:34]

You're assuming that each part which doesn't have a filename parameter is a
string. Is the assumption valid?

[e_hakkinen, 2016/09/28 15:15:04]

I am not sure as https://fetch.spec.whatwg.org/#concept-body-package-data is
missing a detailed parsing specification.

While the parsing is not fully specified, it might make sense to align with
encoding. The https://fetch.spec.whatwg.org/#concept-bodyinit-extract algorithm
refers to
https://html.spec.whatwg.org/multipage/forms.html#multipart/form-data-encodin...
which never creates string parts with a Content-Disposition filename parameter
nor with a Content-Type header field.

So it might make sense to treat each part which have a Content-Disposition
filename parameter or a Content-Type header field as a blob and to treat each
part which have neither as a string.

Changed accordingly.

[yhirano, 2016/09/29 08:30:09]

If the spec is unclear, I think it's a good idea to ask a question at
https://github.com/whatwg/fetch/issues . We should avoid interoperability issues
as much as possible.

+                if (!m_decoder)
+                    m_decoder = TextResourceDecoder::createAlwaysUseUTF8ForText();

[yhirano, 2016/09/26 10:59:34]

Is always using utf-8 appropriate?
https://tools.ietf.org/html/rfc7578#section-5.1.2. says otherwise, I think.

[e_hakkinen, 2016/09/28 15:15:04]

I think so.

The https://fetch.spec.whatwg.org/#concept-body-package-data algorithm specifies
that encoding is utf-8.

A multipart form could include a part with a header field
  Content-Disposition: form-data; name="_charset_"
whose content could be used as a name of a replacement encoding. However, the
package data algorithm for application/x-www-form-urlencoded form data specifies
that decoding algorithm for application/x-www-form-urlencoded form data is
https://url.spec.whatwg.org/#concept-urlencoded-parser with the optional
use_charset_flag implicitly unset i.e. the _charset_ component is not used for
setting decoding encoding for application/x-www-form-urlencoded form data.
Therefore, IMHO it does make sense not to use the _charset_ part for setting
decoding encoding for multipart/form-data form data either.

A multipart form could include parts with Content-Type header fields with
charset parameters. However, I think that whose parts should be parsed as blobs
and not a strings.

Therefore, for strings the encoding seems to be always utf-8.
https://tools.ietf.org/html/rfc7578#section-5.1.2 says that "[s]ome applications
of this pecification will supply a character encoding to be used for
interpretation of the multipart/form-data body". The
https://fetch.spec.whatwg.org/#concept-body-package-data algorithm is such an
applications and it supplies utf-8 as a character encoding.

The rest of the section 5.1.2 paragraph 1 uses HTML 5 as an example so it does
not apply here (and I think that the example is incorrect as HTML 5 does not use
but only ignores and sets the _charset_ field).

The last paragraph of the section 5.1.2 basically says that transfer encoding is
not needed for multipart parts supplied for Fetch API formData.

+                m_stringBuilder.reset(new StringBuilder);
+            }
+            return true;
+        }
+
+        bool appendBytes(const char* bytes, size_t size)
+        {
+            if (m_blobData)
+                m_blobData->appendBytes(bytes, size);
+            if (m_stringBuilder) {
+                m_stringBuilder->append(m_decoder->decode(bytes, size));
+                if (m_decoder->sawError())
+                    return false;
+            }
+            return true;
+        }
+
+        bool finish(FormData* formData)
+        {
+            if (m_blobData) {
+                DCHECK(!m_stringBuilder);
+                auto size = m_blobData->length();

[horo, 2016/09/27 10:45:49]

nit: const

[e_hakkinen, 2016/09/28 15:15:04]

Done.

+                formData->append(m_name, Blob::create(BlobDataHandle::create(std::move(m_blobData), size)), m_filename);
+            }
+            if (m_stringBuilder) {
+                DCHECK(!m_blobData);
+                m_stringBuilder->append(m_decoder->flush());
+                if (m_decoder->sawError())
+                    return false;
+                formData->append(m_name, m_stringBuilder->toString());
+            }
+            return true;
+        }
+
+    private:
+        std::unique_ptr<BlobData> m_blobData;
+        std::unique_ptr<TextResourceDecoder> m_decoder;
+        String m_filename;
+        String m_name;
+        std::unique_ptr<StringBuilder> m_stringBuilder;
+    };
+
+    Member<BytesConsumer> m_consumer;
+    Member<FetchDataLoader::Client> m_client;
+    Member<FormData> m_formData;
+    Member<MultipartParser> m_multipartParser;
+
+    Entry m_currentEntry;
+    String m_multipartBoundary;
+};
+
 class FetchDataLoaderAsString final : public FetchDataLoader, public BytesConsumer::Client {
     USING_GARBAGE_COLLECTED_MIXIN(FetchDataLoaderAsString);
 public:
@@ -319,6 +494,11 @@ FetchDataLoader* FetchDataLoader::createLoaderAsArrayBuffer()
     return new FetchDataLoaderAsArrayBuffer();
 }
 
+FetchDataLoader* FetchDataLoader::createLoaderAsFormData(const String& multipartBoundary)
+{
+    return new FetchDataLoaderAsFormData(multipartBoundary);
+}
+
 FetchDataLoader* FetchDataLoader::createLoaderAsString()
 {
     return new FetchDataLoaderAsString();