Make HRH::IsKeepAlive() look past the first header

net/http/http_response_headers.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 header parsing were borrowed from Firefox:
 // http://lxr.mozilla.org/seamonkey/source/netwerk/protocol/http/src/nsHttpResponseHead.cpp
 // The rules for parsing content-types were also borrowed from Firefox:
 // http://lxr.mozilla.org/mozilla/source/netwerk/base/src/nsURLHelper.cpp#834
 
 #include "net/http/http_response_headers.h"
@@ skipping 1151 matching lines @@
   //    (crbug.com/135131) this better matches our cookie expiration
   //    time parser which ignores timezone specifiers and assumes GMT.
   // 4. This is exactly what Firefox does.
   // TODO(pauljensen): The ideal solution would be to return false if the
   // timezone could not be understood so as to avoid makeing other calculations
   // based on an incorrect time.  This would require modifying the time
   // library or duplicating the code. (http://crbug.com/158327)
   return Time::FromUTCString(value.c_str(), result);
 }
 
+// We accept the first value of "close" or "keep-alive" in a Connection or
+// Proxy-Connection header, in that order. Obeying "keep-alive" in HTTP/1.1 or
+// "close" in 1.0 is not strictly standards-compliant, but we'd like to
+// avoid looking at the Proxy-Connection header whenever it is reasonable to do
+// so.
+// TODO(ricea): Measure real-world usage of the "Proxy-Connection" header,
+// with a view to reducing support for it in order to make our Connection header
+// handling more RFC 7230 compliant.
 bool HttpResponseHeaders::IsKeepAlive() const {
+  // NOTE: It is perhaps risky to assume that a Proxy-Connection header is
+  // meaningful when we don't know that this response was from a proxy, but
+  // Mozilla also does this, so we'll do the same.
+  static const char* kConnectionHeaders[] = {"connection", "proxy-connection"};
+  struct KeepAliveToken {
+    const char* token;
+    bool keep_alive;
+  };
+  static const KeepAliveToken kKeepAliveTokens[] = {{"keep-alive", true},
+                                                    {"close", false}};
+
   if (http_version_ < HttpVersion(1, 0))
     return false;
 
-  // NOTE: It is perhaps risky to assume that a Proxy-Connection header is
-  // meaningful when we don't know that this response was from a proxy, but
-  // Mozilla also does this, so we'll do the same.
-  std::string connection_val;
-  if (!EnumerateHeader(NULL, "connection", &connection_val))
-    EnumerateHeader(NULL, "proxy-connection", &connection_val);
-
-  bool keep_alive;
-
-  if (http_version_ == HttpVersion(1, 0)) {
-    // HTTP/1.0 responses default to NOT keep-alive
-    keep_alive = LowerCaseEqualsASCII(connection_val, "keep-alive");
-  } else {
-    // HTTP/1.1 responses default to keep-alive
-    keep_alive = !LowerCaseEqualsASCII(connection_val, "close");
+  for (const char* header : kConnectionHeaders) {
+    void* iterator = nullptr;
+    std::string token;
+    while (EnumerateHeader(&iterator, header, &token)) {
+      for (const KeepAliveToken& keep_alive_token : kKeepAliveTokens) {
+        if (LowerCaseEqualsASCII(token, keep_alive_token.token))
+          return keep_alive_token.keep_alive;
+      }
+    }
   }
-
-  return keep_alive;
+  return http_version_ != HttpVersion(1, 0);
 }
 
 bool HttpResponseHeaders::HasStrongValidators() const {
   std::string etag_header;
   EnumerateHeader(NULL, "etag", &etag_header);
   std::string last_modified_header;
   EnumerateHeader(NULL, "Last-Modified", &last_modified_header);
   std::string date_header;
   EnumerateHeader(NULL, "Date", &date_header);
   return HttpUtil::HasStrongValidators(GetHttpVersion(),
@@ skipping 193 matching lines @@
   return true;
 }
 
 bool HttpResponseHeaders::IsChunkEncoded() const {
   // Ignore spurious chunked responses from HTTP/1.0 servers and proxies.
   return GetHttpVersion() >= HttpVersion(1, 1) &&
       HasHeaderValue("Transfer-Encoding", "chunked");
 }
 
 }  // namespace net