net/dns/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_DNS_HOST_RESOLVER_PROC_H_
   6 #define NET_DNS_HOST_RESOLVER_PROC_H_
   7
   8 #include <string>
   9
  10 #include "base/memory/ref_counted.h"
  11 #include "net/base/address_family.h"
  12 #include "net/base/net_export.h"
  13
  14 namespace net {
  15
  16 class AddressList;
  17
  18 // Interface for a getaddrinfo()-like procedure. This is used by unit-tests
  19 // to control the underlying resolutions in HostResolverImpl. HostResolverProcs
  20 // can be chained together; they fallback to the next procedure in the chain
  21 // by calling ResolveUsingPrevious().
  22 //
  23 // Note that implementations of HostResolverProc *MUST BE THREADSAFE*, since
  24 // the HostResolver implementation using them can be multi-threaded.
  25 class NET_EXPORT HostResolverProc
  26     : public base::RefCountedThreadSafe<HostResolverProc> {
  27  public:
  28   explicit HostResolverProc(HostResolverProc* previous);
  29
  30   // Resolves |host| to an address list, restricting the results to addresses
  31   // in |address_family|. If successful returns OK and fills |addrlist| with
  32   // a list of socket addresses. Otherwise returns a network error code, and
  33   // fills |os_error| with a more specific error if it was non-NULL.
  34   virtual int Resolve(const std::string& host,
  35                       AddressFamily address_family,
  36                       HostResolverFlags host_resolver_flags,
  37                       AddressList* addrlist,
  38                       int* os_error) = 0;
  39
  40  protected:
  41   friend class base::RefCountedThreadSafe<HostResolverProc>;
  42
  43   virtual ~HostResolverProc();
  44
  45   // Asks the fallback procedure (if set) to do the resolve.
  46   int ResolveUsingPrevious(const std::string& host,
  47                            AddressFamily address_family,
  48                            HostResolverFlags host_resolver_flags,
  49                            AddressList* addrlist,
  50                            int* os_error);
  51
  52  private:
  53   friend class HostResolverImpl;
  54   friend class MockHostResolverBase;
  55   friend class ScopedDefaultHostResolverProc;
  56
  57   // Sets the previous procedure in the chain.  Aborts if this would result in a
  58   // cycle.
  59   void SetPreviousProc(HostResolverProc* proc);
  60
  61   // Sets the last procedure in the chain, i.e. appends |proc| to the end of the
  62   // current chain.  Aborts if this would result in a cycle.
  63   void SetLastProc(HostResolverProc* proc);
  64
  65   // Returns the last procedure in the chain starting at |proc|.  Will return
  66   // NULL iff |proc| is NULL.
  67   static HostResolverProc* GetLastProc(HostResolverProc* proc);
  68
  69   // Sets the default host resolver procedure that is used by HostResolverImpl.
  70   // This can be used through ScopedDefaultHostResolverProc to set a catch-all
  71   // DNS block in unit-tests (individual tests should use MockHostResolver to
  72   // prevent hitting the network).
  73   static HostResolverProc* SetDefault(HostResolverProc* proc);
  74   static HostResolverProc* GetDefault();
  75
  76   scoped_refptr<HostResolverProc> previous_proc_;
  77   static HostResolverProc* default_proc_;
  78
  79   DISALLOW_COPY_AND_ASSIGN(HostResolverProc);
  80 };
  81
  82 // Resolves |host| to an address list, using the system's default host resolver.
  83 // (i.e. this calls out to getaddrinfo()). If successful returns OK and fills
  84 // |addrlist| with a list of socket addresses. Otherwise returns a
  85 // network error code, and fills |os_error| with a more specific error if it
  86 // was non-NULL.
  87 NET_EXPORT_PRIVATE int SystemHostResolverCall(
  88     const std::string& host,
  89     AddressFamily address_family,
  90     HostResolverFlags host_resolver_flags,
  91     AddressList* addrlist,
  92     int* os_error);
  93
  94 // Wraps call to SystemHostResolverCall as an instance of HostResolverProc.
  95 class NET_EXPORT_PRIVATE SystemHostResolverProc : public HostResolverProc {
  96  public:
  97   SystemHostResolverProc();
  98   virtual int Resolve(const std::string& hostname,
  99                       AddressFamily address_family,
 100                       HostResolverFlags host_resolver_flags,
 101                       AddressList* addr_list,
 102                       int* os_error) OVERRIDE;
 103  protected:
 104   virtual ~SystemHostResolverProc();
 105
 106   DISALLOW_COPY_AND_ASSIGN(SystemHostResolverProc);
 107 };
 108
 109 }  // namespace net
 110
 111 #endif  // NET_DNS_HOST_RESOLVER_PROC_H_