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      1 //
      2 // Copyright (C) 2010 The Android Open Source Project
      3 //
      4 // Licensed under the Apache License, Version 2.0 (the "License");
      5 // you may not use this file except in compliance with the License.
      6 // You may obtain a copy of the License at
      7 //
      8 //      http://www.apache.org/licenses/LICENSE-2.0
      9 //
     10 // Unless required by applicable law or agreed to in writing, software
     11 // distributed under the License is distributed on an "AS IS" BASIS,
     12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13 // See the License for the specific language governing permissions and
     14 // limitations under the License.
     15 //
     16 
     17 #ifndef UPDATE_ENGINE_PROXY_RESOLVER_H_
     18 #define UPDATE_ENGINE_PROXY_RESOLVER_H_
     19 
     20 #include <deque>
     21 #include <string>
     22 
     23 #include <base/logging.h>
     24 #include <brillo/message_loops/message_loop.h>
     25 
     26 #include "update_engine/common/utils.h"
     27 
     28 namespace chromeos_update_engine {
     29 
     30 extern const char kNoProxy[];
     31 
     32 // Callback for a call to GetProxiesForUrl().
     33 // Resultant proxies are in |out_proxy|. Each will be in one of the
     34 // following forms:
     35 // http://<host>[:<port>] - HTTP proxy
     36 // socks{4,5}://<host>[:<port>] - SOCKS4/5 proxy
     37 // kNoProxy - no proxy
     38 typedef base::Callback<void(const std::deque<std::string>& proxies)>
     39     ProxiesResolvedFn;
     40 
     41 // An id that identifies a proxy request. Used to cancel an ongoing request
     42 // before the callback is called.
     43 typedef brillo::MessageLoop::TaskId ProxyRequestId;
     44 
     45 // A constant identifying an invalid ProxyRequestId.
     46 extern const ProxyRequestId kProxyRequestIdNull;
     47 
     48 class ProxyResolver {
     49  public:
     50   ProxyResolver() {}
     51   virtual ~ProxyResolver() {}
     52 
     53   // Finds proxies for the given URL and returns them via the callback.
     54   // Returns the id of the pending request on success or kProxyRequestIdNull
     55   // otherwise.
     56   virtual ProxyRequestId GetProxiesForUrl(
     57       const std::string& url, const ProxiesResolvedFn& callback) = 0;
     58 
     59   // Cancel the proxy resolution request initiated by GetProxiesForUrl(). The
     60   // |request| value must be the one provided by GetProxiesForUrl().
     61   virtual bool CancelProxyRequest(ProxyRequestId request) = 0;
     62 
     63  private:
     64   DISALLOW_COPY_AND_ASSIGN(ProxyResolver);
     65 };
     66 
     67 // Always says to not use a proxy
     68 class DirectProxyResolver : public ProxyResolver {
     69  public:
     70   DirectProxyResolver() = default;
     71   ~DirectProxyResolver() override;
     72   ProxyRequestId GetProxiesForUrl(const std::string& url,
     73                                   const ProxiesResolvedFn& callback) override;
     74   bool CancelProxyRequest(ProxyRequestId request) override;
     75 
     76   // Set the number of direct (non-) proxies to be returned by resolver.
     77   // The default value is 1; higher numbers are currently used in testing.
     78   inline void set_num_proxies(size_t num_proxies) {
     79     num_proxies_ = num_proxies;
     80   }
     81 
     82  private:
     83   // The ID of the main loop callback.
     84   brillo::MessageLoop::TaskId idle_callback_id_{
     85       brillo::MessageLoop::kTaskIdNull};
     86 
     87   // Number of direct proxies to return on resolved list; currently used for
     88   // testing.
     89   size_t num_proxies_{1};
     90 
     91   // The MainLoop callback, from here we return to the client.
     92   void ReturnCallback(const ProxiesResolvedFn& callback);
     93   DISALLOW_COPY_AND_ASSIGN(DirectProxyResolver);
     94 };
     95 
     96 }  // namespace chromeos_update_engine
     97 
     98 #endif  // UPDATE_ENGINE_PROXY_RESOLVER_H_
     99