net/base/host_resolver_proc.h

   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 #ifndef NET_BASE_HOST_RESOLVER_PROC_H_
   6 #define NET_BASE_HOST_RESOLVER_PROC_H_
   7 #pragma once
   8
   9 #include <string>
  10
  11 #include "base/memory/ref_counted.h"
  12 #include "net/base/address_family.h"
  13 #include "net/base/net_export.h"
  14
  15 namespace net {
  16
  17 class AddressList;
  18
  19 // Interface for a getaddrinfo()-like procedure. This is used by unit-tests
  20 // to control the underlying resolutions in HostResolverImpl. HostResolverProcs
  21 // can be chained together; they fallback to the next procedure in the chain
  22 // by calling ResolveUsingPrevious().
  23 //
  24 // Note that implementations of HostResolverProc *MUST BE THREADSAFE*, since
  25 // the HostResolver implementation using them can be multi-threaded.
  26 class NET_EXPORT HostResolverProc
  27     : public base::RefCountedThreadSafe<HostResolverProc> {
  28  public:
  29   explicit HostResolverProc(HostResolverProc* previous);
  30
  31   // Resolves |host| to an address list, restricting the results to addresses
  32   // in |address_family|. If successful returns OK and fills |addrlist| with
  33   // a list of socket addresses. Otherwise returns a network error code, and
  34   // fills |os_error| with a more specific error if it was non-NULL.
  35   virtual int Resolve(const std::string& host,
  36                       AddressFamily address_family,
  37                       HostResolverFlags host_resolver_flags,
  38                       AddressList* addrlist,
  39                       int* os_error) = 0;
  40
  41  protected:
  42   friend class base::RefCountedThreadSafe<HostResolverProc>;
  43
  44   virtual ~HostResolverProc();
  45
  46   // Asks the fallback procedure (if set) to do the resolve.
  47   int ResolveUsingPrevious(const std::string& host,
  48                            AddressFamily address_family,
  49                            HostResolverFlags host_resolver_flags,
  50                            AddressList* addrlist,
  51                            int* os_error);
  52
  53  private:
  54   friend class HostResolverImpl;
  55   friend class MockHostResolverBase;
  56   friend class ScopedDefaultHostResolverProc;
  57
  58   // Sets the previous procedure in the chain.  Aborts if this would result in a
  59   // cycle.
  60   void SetPreviousProc(HostResolverProc* proc);
  61
  62   // Sets the last procedure in the chain, i.e. appends |proc| to the end of the
  63   // current chain.  Aborts if this would result in a cycle.
  64   void SetLastProc(HostResolverProc* proc);
  65
  66   // Returns the last procedure in the chain starting at |proc|.  Will return
  67   // NULL iff |proc| is NULL.
  68   static HostResolverProc* GetLastProc(HostResolverProc* proc);
  69
  70   // Sets the default host resolver procedure that is used by HostResolverImpl.
  71   // This can be used through ScopedDefaultHostResolverProc to set a catch-all
  72   // DNS block in unit-tests (individual tests should use MockHostResolver to
  73   // prevent hitting the network).
  74   static HostResolverProc* SetDefault(HostResolverProc* proc);
  75   static HostResolverProc* GetDefault();
  76
  77   scoped_refptr<HostResolverProc> previous_proc_;
  78   static HostResolverProc* default_proc_;
  79
  80   DISALLOW_COPY_AND_ASSIGN(HostResolverProc);
  81 };
  82
  83 // Resolves |host| to an address list, using the system's default host resolver.
  84 // (i.e. this calls out to getaddrinfo()). If successful returns OK and fills
  85 // |addrlist| with a list of socket addresses. Otherwise returns a
  86 // network error code, and fills |os_error| with a more specific error if it
  87 // was non-NULL.
  88 NET_EXPORT_PRIVATE int SystemHostResolverProc(
  89     const std::string& host,
  90     AddressFamily address_family,
  91     HostResolverFlags host_resolver_flags,
  92     AddressList* addrlist,
  93     int* os_error);
  94
  95 }  // namespace net
  96
  97 #endif  // NET_BASE_HOST_RESOLVER_PROC_H_