Added HttpUtils::HasValidators and HttpResponse::HasValidators

net/http/http_util.cc

 // Copyright (c) 2012 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.
 
 // The rules for parsing content-types were borrowed from Firefox:
 // http://lxr.mozilla.org/mozilla/source/netwerk/base/src/nsURLHelper.cpp#834
 
 #include "net/http/http_util.h"
 
 #include <algorithm>
@@ skipping 719 matching lines @@
   if (header_value.empty())
     return;
   if (HttpUtil::HasHeader(*headers, header_name))
     return;
   *headers += std::string(header_name) + ": " + header_value + "\r\n";
 }
 
 bool HttpUtil::HasStrongValidators(HttpVersion version,
                                    const std::string& etag_header,
                                    const std::string& last_modified_header,
                                    const std::string& date_header) {

[gavinp, 2016/02/25 18:56:20]

Could HasStrongValidators call HasValidators?

[jamartin, 2016/02/26 14:47:50]

Sure although it won't make any difference in the current logic. It makes
explicit that HasStrongValidators ⊆ HasValidators, though, which is a
benefit on its own right. Is there any other reason why you want to have this
call?

[gavinp, 2016/02/26 15:32:59]

The documentary purpose was the only one; but it felt compelling to me: I find
the specifications and definitions in this area deeply confusing, and so code
that contains strong unambiguous statements about the presumed relationships is
really good.

   if (version < HttpVersion(1, 1))
     return false;
 
   if (!etag_header.empty()) {
     size_t slash = etag_header.find('/');
     if (slash == std::string::npos || slash == 0)
       return true;
 
     std::string::const_iterator i = etag_header.begin();
     std::string::const_iterator j = etag_header.begin() + slash;
     TrimLWS(&i, &j);
     if (!base::LowerCaseEqualsASCII(base::StringPiece(i, j), "w"))
       return true;
   }
 
   base::Time last_modified;
   if (!base::Time::FromString(last_modified_header.c_str(), &last_modified))
     return false;
 
   base::Time date;
   if (!base::Time::FromString(date_header.c_str(), &date))
     return false;
 
+  // Last-Modified is implicitly weak unless it is at least 60 seconds before
+  // the Date value.
   return ((date - last_modified).InSeconds() >= 60);
 }
 
+bool HttpUtil::HasValidators(HttpVersion version,
+                             const std::string& etag_header,
+                             const std::string& last_modified_header) {
+  if (version < HttpVersion(1, 0))
+    return false;
+
+  base::Time last_modified;
+  if (base::Time::FromString(last_modified_header.c_str(), &last_modified))
+    return true;
+
+  return version >= HttpVersion(1, 1) && !etag_header.empty();
+}
+
 // Functions for histogram initialization.  The code 0 is put in the map to
 // track status codes that are invalid.
 // TODO(gavinp): Greatly prune the collected codes once we learn which
 // ones are not sent in practice, to reduce upload size & memory use.
 
 enum {
   HISTOGRAM_MIN_HTTP_STATUS_CODE = 100,
   HISTOGRAM_MAX_HTTP_STATUS_CODE = 599,
 };
 
@@ skipping 189 matching lines @@
       value_is_quoted_ = true;
       // Do not store iterators into this. See declaration of unquoted_value_.
       unquoted_value_ = HttpUtil::Unquote(value_begin_, value_end_);
     }
   }
 
   return true;
 }
 
 }  // namespace net