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

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

+// Copyright 2016 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 "modules/fetch/MultipartParser.h"
+
+#include "platform/HTTPNames.h"
+#include "public/platform/Platform.h"
+
+#include <algorithm>
+#include <utility>
+
+namespace blink {
+
+namespace {
+
+constexpr char kCloseDelimiterSuffix[] = "--\r\n";
+constexpr size_t kCloseDelimiterSuffixSize = WTF_ARRAY_LENGTH(kCloseDelimiterSuffix) - 1u;
+constexpr size_t kDashBoundaryOffset = 2u; // The length of "--".
+constexpr char kDelimiterSuffix[] = "\r\n";
+constexpr size_t kDelimiterSuffixSize = WTF_ARRAY_LENGTH(kDelimiterSuffix) - 1u;
+
+bool octetsNeedDecoding(const WebURLResponse& response)
+{
+    const AtomicString& encoding = response.toResourceResponse().httpHeaderField(HTTPNames::Content_Transfer_Encoding);
+
+    // Decoding is not needed if a transfer encoding is not used.
+    if (encoding.isNull())
+        return false;
+
+    // Decoding is not needed if a no-op transfer encoding is used.
+    if (equalIgnoringCase(encoding, "binary")
+        || equalIgnoringCase(encoding, "7bit")
+        || equalIgnoringCase(encoding, "8bit")) {
+        return false;
+    }
+
+    return true;
+}
+
+} // namespace
+
+MultipartParser::Matcher::Matcher() = default;
+
+MultipartParser::Matcher::Matcher(const char* data, size_t numMatchedBytes, size_t size)
+    : m_data(data), m_numMatchedBytes(numMatchedBytes), m_size(size) {}
+
+bool MultipartParser::Matcher::match(char value)
+{
+    DCHECK_LT(m_numMatchedBytes, m_size);
+    if (value != m_data[m_numMatchedBytes])
+        return false;
+    ++m_numMatchedBytes;
+    return true;
+}
+
+bool MultipartParser::Matcher::match(const char* first, const char* last)
+{
+    while (first < last) {
+        if (!match(*first++))
+            return false;
+    }
+    return true;
+}
+
+void MultipartParser::Matcher::setNumMatchedBytes(size_t numMatchedBytes)
+{
+    DCHECK_LE(numMatchedBytes, m_size);
+    m_numMatchedBytes = numMatchedBytes;
+}
+
+MultipartParser::MultipartParser(Vector<char> boundary, Client* client)
+    : m_client(client)
+    , m_delimiter(std::move(boundary))
+    , m_state(ParsingPreamble)
+{
+    // The delimiter consists of "\r\n" and a dash boundary which consists of
+    // "--" and a boundary.
+    m_delimiter.prepend("\r\n--", 4u);
+    m_matcher = delimiterMatcher(kDashBoundaryOffset);
+}
+
+bool MultipartParser::appendData(const char* bytes, size_t size)
+{
+    DCHECK_NE(Finished, m_state);
+    DCHECK_NE(Cancelled, m_state);
+
+    const char* bytesEnd = bytes + size;
+
+    while (bytes < bytesEnd) {
+        switch (m_state) {
+        case ParsingPreamble:
+            // Parse either a preamble and a delimiter or a dash boundary.
+            parseDelimiter(&bytes, bytesEnd);
+            if (!m_matcher.isMatchComplete() && bytes < bytesEnd) {
+                // Parse a preamble data (by ignoring it) and then a delimiter.
+                m_matcher.setNumMatchedBytes(0u);
+                parseDataAndDelimiter(&bytes, bytesEnd);
+            }
+            if (m_matcher.isMatchComplete()) {
+                // Prepare for a delimiter suffix.
+                m_matcher = delimiterSuffixMatcher();
+                m_state = ParsingDelimiterSuffix;
+            }
+            break;
+
+        case ParsingDelimiterSuffix:
+            // Parse transport padding and "\r\n" after a delimiter.
+            // This state can be reached after either a preamble or part
+            // octets are parsed.
+            if (m_matcher.numMatchedBytes() == 0u)
+                parseTransportPadding(&bytes, bytesEnd);
+            while (bytes < bytesEnd) {
+                if (!m_matcher.match(*bytes++))
+                    return false;
+                if (m_matcher.isMatchComplete()) {
+                    // Prepare for part header fields.
+                    m_state = ParsingPartHeaderFields;
+                    break;
+                }
+            }
+            break;
+
+        case ParsingPartHeaderFields: {
+            // Parse part header fields (which ends with "\r\n") and an empty
+            // line (which also ends with "\r\n").
+            // This state can be reached after a delimiter and a delimiter
+            // suffix after either a preamble or part octets are parsed.
+            WebURLResponse response;
+            if (parseHeaderFields(&bytes, bytesEnd, &response)) {
+                // Decoding is not implemented.
+                if (octetsNeedDecoding(response))
+                    return false;
+                // Prepare for part octets.
+                m_matcher = delimiterMatcher();
+                m_state = ParsingPartOctets;
+                m_client->partHeaderFieldsInMultipartReceived(response.toResourceResponse());
+            }
+            break;
+        }
+
+        case ParsingPartOctets: {
+            // Parse part octets and a delimiter.
+            // This state can be reached only after part header fields are
+            // parsed.
+            size_t numInitiallyMatchedBytes = m_matcher.numMatchedBytes();

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

nit: const

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

Done.

+            const char* octetsBegin = bytes;
+            parseDelimiter(&bytes, bytesEnd);
+            if (!m_matcher.isMatchComplete() && bytes < bytesEnd) {
+                if (m_matcher.numMatchedBytes() >= numInitiallyMatchedBytes && numInitiallyMatchedBytes > 0u) {
+                    // Since the matched bytes did not form a complete
+                    // delimiter, the matched bytes turned out to be octet
+                    // bytes instead of being delimiter bytes. Additionally,
+                    // some of the matched bytes are from the previous call and
+                    // are therefore not in the range [octetsBegin, bytesEnd[.
+                    m_client->partDataInMultipartReceived(m_matcher.data(), m_matcher.numMatchedBytes());
+                    if (m_state != ParsingPartOctets)
+                        break;
+                    octetsBegin = bytes;
+                }
+                m_matcher.setNumMatchedBytes(0u);
+                parseDataAndDelimiter(&bytes, bytesEnd);
+                const char* octetsEnd = bytes - m_matcher.numMatchedBytes();
+                if (octetsBegin < octetsEnd) {
+                    m_client->partDataInMultipartReceived(octetsBegin, static_cast<size_t>(octetsEnd - octetsBegin));
+                    if (m_state != ParsingPartOctets)
+                        break;
+                }
+            }
+            if (m_matcher.isMatchComplete()) {
+                m_state = ParsingDelimiterOrCloseDelimiterSuffix;
+                m_client->partDataInMultipartFullyReceived();
+            }
+            break;
+        }
+
+        case ParsingDelimiterOrCloseDelimiterSuffix:
+            // Determine whether this is a delimiter suffix or a close
+            // delimiter suffix.
+            // This state can be reached only after part octets are parsed.
+            if (*bytes == '-') {
+                // Prepare for a close delimiter suffix.
+                m_matcher = closeDelimiterSuffixMatcher();
+                m_state = ParsingCloseDelimiterSuffix;
+            } else {
+                // Prepare for a delimiter suffix.
+                m_matcher = delimiterSuffixMatcher();
+                m_state = ParsingDelimiterSuffix;
+            }
+            break;
+
+        case ParsingCloseDelimiterSuffix:
+            // Parse "--", transport padding and "\r\n" after a delimiter
+            // (a delimiter and "--" constitute a close delimiter).
+            // This state can be reached only after part octets are parsed.
+            for (;;) {
+                if (m_matcher.numMatchedBytes() == 2u)
+                    parseTransportPadding(&bytes, bytesEnd);
+                if (bytes >= bytesEnd)
+                    break;
+                if (!m_matcher.match(*bytes++))
+                    return false;
+                if (m_matcher.isMatchComplete()) {
+                    // Prepare for an epilogue.
+                    m_state = ParsingEpilogue;
+                    break;
+                }
+            }
+            break;
+
+        case ParsingEpilogue:
+            // Parse an epilogue (by ignoring it).
+            // This state can be reached only after a delimiter and a close
+            // delimiter suffix after part octets are parsed.
+            return true;
+
+        case Cancelled:
+        case Finished:
+            // The client changed the state.
+            return false;
+        }
+    }
+
+    DCHECK_EQ(bytesEnd, bytes);
+
+    return true;
+}
+
+void MultipartParser::cancel()
+{
+    m_state = Cancelled;
+}
+
+bool MultipartParser::finish()
+{
+    DCHECK_NE(Cancelled, m_state);
+

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

Is it allowed to call MultipartParser::finish() multiple times?
If not, please add "DCHECK_NE(Finished, m_state);" and remove line 255.

[e_hakkinen, 2016/09/28 15:15:05]

Maybe it is easier to find the success path correct if it is not allowed to be
called multiple times. So let's enforce that.

In contrast to MultipartParser::finish(), MultipartParser::cancel() is part of a
failure path which might be quite difficult to implement if it were not allowed
to call MultipartParser::cancel() multiple times. So let's not change that.
Done.

+    State initialState = m_state;

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

nit: const

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

Done.

+    m_state = Finished;
+
+    switch (initialState) {
+    case ParsingPartOctets:
+        if (m_matcher.numMatchedBytes() > 0u) {
+            // Since the matched bytes did not form a complete delimiter,
+            // the matched bytes turned out to be octet bytes instead of being
+            // delimiter bytes.
+            m_client->partDataInMultipartReceived(m_matcher.data(), m_matcher.numMatchedBytes());
+        }
+        return false;
+    case ParsingCloseDelimiterSuffix:
+        // Require a full close delimiter consisting of a delimiter and "--"
+        // but ignore missing or partial "\r\n" after that.
+        return m_matcher.numMatchedBytes() >= 2u;
+    case ParsingEpilogue:
+    case Finished:
+        return true;
+    default:
+        return false;
+    }
+}
+
+MultipartParser::Matcher MultipartParser::closeDelimiterSuffixMatcher() const
+{
+    return Matcher(kCloseDelimiterSuffix, 0u, kCloseDelimiterSuffixSize);
+}
+
+MultipartParser::Matcher MultipartParser::delimiterMatcher(size_t numAlreadyMatchedBytes) const
+{
+    return Matcher(m_delimiter.data(), numAlreadyMatchedBytes, m_delimiter.size());
+}
+
+MultipartParser::Matcher MultipartParser::delimiterSuffixMatcher() const
+{
+    return Matcher(kDelimiterSuffix, 0u, kDelimiterSuffixSize);
+}
+
+void MultipartParser::parseDataAndDelimiter(const char** bytesPointer, const char* bytesEnd)
+{
+    DCHECK_EQ(0u, m_matcher.numMatchedBytes());
+
+    // Search for a complete delimiter within the bytes.
+    const char* delimiterBegin = std::search(*bytesPointer, bytesEnd, m_delimiter.begin(), m_delimiter.end());
+    if (delimiterBegin != bytesEnd) {
+        // A complete delimiter was found. The bytes before that are octet
+        // bytes.
+        const char* delimiterEnd = delimiterBegin + m_delimiter.size();
+        bool matched = m_matcher.match(delimiterBegin, delimiterEnd);

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

nit: const

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

Done.

+        DCHECK(matched);
+        DCHECK(m_matcher.isMatchComplete());
+        *bytesPointer = delimiterEnd;
+    } else {
+        // Search for a partial delimiter in the end of the bytes.
+        size_t size = static_cast<size_t>(bytesEnd - *bytesPointer);
+        for (delimiterBegin = bytesEnd - std::min(m_delimiter.size() - 1u, size); delimiterBegin < bytesEnd; ++delimiterBegin) {
+            if (m_matcher.match(delimiterBegin, bytesEnd))
+                break;
+            m_matcher.setNumMatchedBytes(0u);
+        }
+        // If a partial delimiter was found in the end of bytes, the bytes
+        // before the partial delimiter are definitely octets bytes and
+        // the partial delimiter bytes are buffered for now.
+        // If a partial delimiter was not found in the end of bytes, all bytes
+        // are definitely octets bytes.
+        // In all cases, all bytes are parsed now.
+        *bytesPointer = bytesEnd;
+    }
+
+    DCHECK(m_matcher.isMatchComplete() || *bytesPointer == bytesEnd);
+}
+
+void MultipartParser::parseDelimiter(const char** bytesPointer, const char* bytesEnd)
+{
+    DCHECK(!m_matcher.isMatchComplete());
+    while (*bytesPointer < bytesEnd && m_matcher.match(*(*bytesPointer))) {
+        ++(*bytesPointer);
+        if (m_matcher.isMatchComplete())
+            break;
+    }
+}
+
+bool MultipartParser::parseHeaderFields(const char** bytesPointer, const char* bytesEnd, WebURLResponse* response)
+{
+    // Combine the current bytes with buffered header bytes if needed.
+    const char* headerBytes = *bytesPointer;
+    size_t headerSize = static_cast<size_t>(bytesEnd - *bytesPointer);
+    if (!m_bufferedHeaderBytes.isEmpty()) {
+        m_bufferedHeaderBytes.append(headerBytes, headerSize);
+        headerBytes = m_bufferedHeaderBytes.data();
+        headerSize = m_bufferedHeaderBytes.size();
+    }
+
+    size_t end = 0u;
+    if (!Platform::current()->parseMultipartHeadersFromBody(headerBytes, headerSize, response, &end)) {
+        // Store the current header bytes for the next call unless that has
+        // already been done.
+        if (m_bufferedHeaderBytes.isEmpty())
+            m_bufferedHeaderBytes.append(headerBytes, headerSize);
+        *bytesPointer = bytesEnd;
+        return false;
+    }
+    m_bufferedHeaderBytes.clear();
+    *bytesPointer = bytesEnd - (headerSize - end);
+
+    return true;
+}
+
+void MultipartParser::parseTransportPadding(const char** bytesPointer, const char* bytesEnd) const
+{
+    while (*bytesPointer < bytesEnd && (*(*bytesPointer) == '\t' || *(*bytesPointer) == ' '))
+        ++(*bytesPointer);
+}
+
+DEFINE_TRACE(MultipartParser)
+{
+    visitor->trace(m_client);
+}
+
+} // namespace blink