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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "chrome/browser/net/preconnect.h"
      6 
      7 #include "base/bind.h"
      8 #include "base/logging.h"
      9 #include "base/metrics/histogram.h"
     10 #include "content/public/browser/browser_thread.h"
     11 #include "net/base/net_log.h"
     12 #include "net/http/http_network_session.h"
     13 #include "net/http/http_request_info.h"
     14 #include "net/http/http_stream_factory.h"
     15 #include "net/http/http_transaction_factory.h"
     16 #include "net/ssl/ssl_config_service.h"
     17 #include "net/url_request/url_request_context.h"
     18 #include "net/url_request/url_request_context_getter.h"
     19 
     20 using content::BrowserThread;
     21 
     22 namespace chrome_browser_net {
     23 
     24 void PreconnectOnUIThread(
     25     const GURL& url,
     26     const GURL& first_party_for_cookies,
     27     UrlInfo::ResolutionMotivation motivation,
     28     int count,
     29     net::URLRequestContextGetter* getter) {
     30   // Prewarm connection to Search URL.
     31   BrowserThread::PostTask(
     32       BrowserThread::IO,
     33       FROM_HERE,
     34       base::Bind(&PreconnectOnIOThread, url, first_party_for_cookies,
     35                  motivation, count, make_scoped_refptr(getter)));
     36   return;
     37 }
     38 
     39 
     40 void PreconnectOnIOThread(
     41     const GURL& url,
     42     const GURL& first_party_for_cookies,
     43     UrlInfo::ResolutionMotivation motivation,
     44     int count,
     45     net::URLRequestContextGetter* getter) {
     46   if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
     47     LOG(DFATAL) << "This must be run only on the IO thread.";
     48     return;
     49   }
     50   if (!getter)
     51     return;
     52   // We are now commited to doing the async preconnection call.
     53   UMA_HISTOGRAM_ENUMERATION("Net.PreconnectMotivation", motivation,
     54                             UrlInfo::MAX_MOTIVATED);
     55 
     56   net::URLRequestContext* context = getter->GetURLRequestContext();
     57   net::HttpTransactionFactory* factory = context->http_transaction_factory();
     58   net::HttpNetworkSession* session = factory->GetSession();
     59 
     60   net::HttpRequestInfo request_info;
     61   request_info.url = url;
     62   request_info.method = "GET";
     63   request_info.extra_headers.SetHeader(net::HttpRequestHeaders::kUserAgent,
     64                                        context->GetUserAgent(url));
     65 
     66   net::NetworkDelegate* delegate = context->network_delegate();
     67   if (delegate->CanEnablePrivacyMode(url, first_party_for_cookies))
     68     request_info.privacy_mode = net::kPrivacyModeEnabled;
     69 
     70   // It almost doesn't matter whether we use net::LOWEST or net::HIGHEST
     71   // priority here, as we won't make a request, and will surrender the created
     72   // socket to the pool as soon as we can.  However, we would like to mark the
     73   // speculative socket as such, and IF we use a net::LOWEST priority, and if
     74   // a navigation asked for a socket (after us) then it would get our socket,
     75   // and we'd get its later-arriving socket, which might make us record that
     76   // the speculation didn't help :-/.  By using net::HIGHEST, we ensure that
     77   // a socket is given to us if "we asked first" and this allows us to mark it
     78   // as speculative, and better detect stats (if it gets used).
     79   // TODO(jar): histogram to see how often we accidentally use a previously-
     80   // unused socket, when a previously used socket was available.
     81   net::RequestPriority priority = net::HIGHEST;
     82 
     83   // Translate the motivation from UrlRequest motivations to HttpRequest
     84   // motivations.
     85   switch (motivation) {
     86     case UrlInfo::OMNIBOX_MOTIVATED:
     87       request_info.motivation = net::HttpRequestInfo::OMNIBOX_MOTIVATED;
     88       break;
     89     case UrlInfo::LEARNED_REFERAL_MOTIVATED:
     90       request_info.motivation = net::HttpRequestInfo::PRECONNECT_MOTIVATED;
     91       break;
     92     case UrlInfo::MOUSE_OVER_MOTIVATED:
     93     case UrlInfo::SELF_REFERAL_MOTIVATED:
     94     case UrlInfo::EARLY_LOAD_MOTIVATED:
     95       request_info.motivation = net::HttpRequestInfo::EARLY_LOAD_MOTIVATED;
     96       break;
     97     default:
     98       // Other motivations should never happen here.
     99       NOTREACHED();
    100       break;
    101   }
    102 
    103   // Setup the SSL Configuration.
    104   net::SSLConfig ssl_config;
    105   session->ssl_config_service()->GetSSLConfig(&ssl_config);
    106   if (session->http_stream_factory()->has_next_protos())
    107     ssl_config.next_protos = session->http_stream_factory()->next_protos();
    108 
    109   // All preconnects should perform EV certificate verification.
    110   ssl_config.verify_ev_cert = true;
    111 
    112   net::HttpStreamFactory* http_stream_factory = session->http_stream_factory();
    113   http_stream_factory->PreconnectStreams(count, request_info, priority,
    114                                          ssl_config, ssl_config);
    115 }
    116 
    117 }  // namespace chrome_browser_net
    118