Better header value parsing for Server-Timing.

third_party/WebKit/Source/platform/network/HTTPParsers.cpp

 /*
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple 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:
@@ skipping 831 matching lines @@
 
 bool ParseContentRangeHeaderFor206(const String& content_range,
                                    int64_t* first_byte_position,
                                    int64_t* last_byte_position,
                                    int64_t* instance_length) {
   return net::HttpUtil::ParseContentRangeHeaderFor206(
       StringUTF8Adaptor(content_range).AsStringPiece(), first_byte_position,
       last_byte_position, instance_length);
 }
 
-template <typename CharType>
-inline bool IsNotServerTimingHeaderDelimiter(CharType c) {
-  return c != '=' && c != ';' && c != ',';
-}
-
-const LChar* ParseServerTimingToken(const LChar* begin,
-                                    const LChar* end,
-                                    String& result) {
-  const LChar* position = begin;
-  skipWhile<LChar, IsNotServerTimingHeaderDelimiter>(position, end);
-  result = String(begin, position - begin).StripWhiteSpace();
-  return position;
-}
-
-String CheckDoubleQuotedString(const String& value) {
-  if (value.length() < 2 || value[0] != '"' ||
-      value[value.length() - 1] != '"') {
-    return value;
-  }
-
-  StringBuilder out;
-  unsigned pos = 1;                   // Begin after the opening DQUOTE.
-  unsigned len = value.length() - 1;  // End before the closing DQUOTE.
-
-  // Skip past backslashes, but include everything else.
-  while (pos < len) {
-    if (value[pos] == '\\')
-      pos++;
-    if (pos < len)
-      out.Append(value[pos++]);
-  }
-
-  return out.ToString();
-}
-
 std::unique_ptr<ServerTimingHeaderVector> ParseServerTimingHeader(
     const String& headerValue) {
   std::unique_ptr<ServerTimingHeaderVector> headers =
       WTF::MakeUnique<ServerTimingHeaderVector>();
 
   if (!headerValue.IsNull()) {
     DCHECK(headerValue.Is8Bit());
 
-    const LChar* position = headerValue.Characters8();
-    const LChar* end = position + headerValue.length();
-    while (position < end) {
-      String metric, value, description = "";
-      position = ParseServerTimingToken(position, end, metric);
-      if (position != end && *position == '=') {
-        position = ParseServerTimingToken(position + 1, end, value);
+    unsigned index = 0;
+    while (index < headerValue.length()) {
+      StringView metric;
+      if (!ConsumeToken(Mode::kNormal, headerValue, index, metric)) {
+        continue;
       }
-      if (position != end && *position == ';') {
-        position = ParseServerTimingToken(position + 1, end, description);
+
+      StringView duration;
+      String description;
+      if (Consume('=', headerValue, index)) {
+        ConsumeToken(Mode::kNormal, headerValue, index, duration);
       }
-      position++;
+      if (Consume(';', headerValue, index)) {
+        ConsumeTokenOrQuotedString(Mode::kNormal, headerValue, index,
+                                   description);
+      }
 
       headers->push_back(WTF::MakeUnique<ServerTimingHeader>(
-          metric, value.ToDouble(), CheckDoubleQuotedString(description)));
+          metric.ToString(), duration.ToString().ToDouble(),
+          description ? description : ""));
+
+      Consume(',', headerValue, index);
     }
   }
   return headers;
 }
 
 bool IsTokenCharacter(Mode mode, UChar c) {
   if (c >= 128)
     return false;
   if (c < 0x20)
     return false;
@@ skipping 17 matching lines @@
     case '?':
     case '=':
       return mode == Mode::kRelaxed;
     default:
       return true;
   }
 }
 
 bool Consume(char c, const String& input, unsigned& index) {
   DCHECK_NE(c, ' ');
+  // TODO: skip all whitespace, not just spaces

[Yoav Weiss, 2017/05/18 21:45:05]

The format should be `// TODO(cvazac): ...`. Also can you include a link to
https://tools.ietf.org/html/rfc7231#section-3.1.1 in at least the first one.

   while (index < input.length() && input[index] == ' ')
     ++index;
 
   if (index < input.length() && input[index] == c) {
     ++index;
     return true;
   }
   return false;
 }
 
 bool ConsumeToken(Mode mode,
                   const String& input,
                   unsigned& index,
                   StringView& output) {
   DCHECK(output.IsNull());
 
+  // TODO: skip all whitespace, not just spaces
   while (index < input.length() && input[index] == ' ')
     ++index;
 
   auto start = index;
   while (index < input.length() && IsTokenCharacter(mode, input[index]))
     ++index;
 
   if (start == index)
     return false;
 
@@ skipping 22 matching lines @@
     builder.Append(input[index]);
     ++index;
   }
   return false;
 }
 
 bool ConsumeTokenOrQuotedString(Mode mode,
                                 const String& input,
                                 unsigned& index,
                                 String& output) {
+  // TODO: skip all whitespace, not just spaces
   while (index < input.length() && input[index] == ' ')
     ++index;
   if (input.length() == index)
     return false;
   if (input[index] == '"') {
     return ConsumeQuotedString(input, index, output);
   }
   StringView view;
   auto result = ConsumeToken(mode, input, index, view);
   output = view.ToString();
   return result;
 }
 
 bool IsEnd(const String& input, unsigned index) {
   while (index < input.length()) {
+    // TODO: skip all whitespace, not just spaces
     if (input[index] != ' ')
       return false;
     ++index;
   }
   return true;
 }
 
 }  // namespace blink