Fix Link header parsing bug with extension parameter parsing.

Source/core/loader/LinkHeader.cpp

 // 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 "config.h"
 #include "core/loader/LinkHeader.h"
 
 #include "platform/ParsingUtilities.h"
 
 namespace blink {
 
 // LWSP definition in https://www.ietf.org/rfc/rfc0822.txt
 template <typename CharType>
 static bool isWhitespace(CharType chr)
 {
     return (chr == ' ') || (chr == '\t');
 }
 
 template <typename CharType>
 static bool isValidURLChar(CharType chr)
 {
     return !isWhitespace(chr) && chr != '>';
 }
 
 template <typename CharType>
 static bool isValidParameterNameChar(CharType chr)
 {
-    return !isWhitespace(chr) && chr != '=';
+    // Alpha-numeric is a valid char.
+    // This is likely the common case - bailing early.
+    if ((chr >= 'a' && chr <= 'z') || (chr >= 'A' && chr <= 'Z') || (chr >= '0' && chr <= '9'))

[Nate Chapin, 2015/08/27 23:11:48]

Can we simplify some of this function by reusing helpers in wtf/ASCIICType.h or
similar?

+        return true;
+    // A separator or CTL or '%', '*' or '\'' means the char is not valid.
+    if (chr <= ' ' || chr > '|' || chr == '{' || chr == ']' || chr == '['
+        || chr == '/' || chr == '\\' || (chr <= '@' && chr >= ':') || chr == ','
+        || (chr >= '(' && chr <= '*') || chr == '\'' || chr == '"' || chr == '%')

[Nate Chapin, 2015/08/27 23:11:48]

Nit: add {}

+        return false;
+    return true;
 }
 
 template <typename CharType>
 static bool isValidParameterValueEnd(CharType chr)
 {
     return chr == ';' || chr == ',';
 }
 
 template <typename CharType>
 static bool isValidParameterValueChar(CharType chr)
 {
     return !isWhitespace(chr) && !isValidParameterValueEnd(chr);
 }
 
+// Verify that the parameter is a link-extension which according to spec doesn't have to have a value.
 static bool isExtensionParameter(LinkHeader::LinkParameterName name)
 {
     return name > LinkHeader::LinkParameterAnchor;
 }
 
 // Before:
 //
 // <cat.jpg>; rel=preload
 // ^                     ^
 // position              end
@@ skipping 232 matching lines @@
 template <typename CharType>
 void LinkHeaderSet::init(CharType* headerValue, unsigned len)
 {
     CharType* position = headerValue;
     CharType* end = headerValue + len;
     while (position < end)
         m_headerSet.append(LinkHeader(position, end));
 }
 
 }