1// Copyright (c) 2011 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 14namespace net { 15 16class 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. 25class HostResolverProc : public base::RefCountedThreadSafe<HostResolverProc> { 26 public: 27 explicit HostResolverProc(HostResolverProc* previous); 28 29 // Resolves |host| to an address list, restricting the results to addresses 30 // in |address_family|. If successful returns OK and fills |addrlist| with 31 // a list of socket addresses. Otherwise returns a network error code, and 32 // fills |os_error| with a more specific error if it was non-NULL. 33 virtual int Resolve(const std::string& host, 34 AddressFamily address_family, 35 HostResolverFlags host_resolver_flags, 36 AddressList* addrlist, 37 int* os_error) = 0; 38 39 protected: 40 friend class base::RefCountedThreadSafe<HostResolverProc>; 41 42 virtual ~HostResolverProc(); 43 44 // Asks the fallback procedure (if set) to do the resolve. 45 int ResolveUsingPrevious(const std::string& host, 46 AddressFamily address_family, 47 HostResolverFlags host_resolver_flags, 48 AddressList* addrlist, 49 int* os_error); 50 51 private: 52 friend class HostResolverImpl; 53 friend class MockHostResolverBase; 54 friend class ScopedDefaultHostResolverProc; 55 56 // Sets the previous procedure in the chain. Aborts if this would result in a 57 // cycle. 58 void SetPreviousProc(HostResolverProc* proc); 59 60 // Sets the last procedure in the chain, i.e. appends |proc| to the end of the 61 // current chain. Aborts if this would result in a cycle. 62 void SetLastProc(HostResolverProc* proc); 63 64 // Returns the last procedure in the chain starting at |proc|. Will return 65 // NULL iff |proc| is NULL. 66 static HostResolverProc* GetLastProc(HostResolverProc* proc); 67 68 // Sets the default host resolver procedure that is used by HostResolverImpl. 69 // This can be used through ScopedDefaultHostResolverProc to set a catch-all 70 // DNS block in unit-tests (individual tests should use MockHostResolver to 71 // prevent hitting the network). 72 static HostResolverProc* SetDefault(HostResolverProc* proc); 73 static HostResolverProc* GetDefault(); 74 75 scoped_refptr<HostResolverProc> previous_proc_; 76 static HostResolverProc* default_proc_; 77 78 DISALLOW_COPY_AND_ASSIGN(HostResolverProc); 79}; 80 81// Resolves |host| to an address list, using the system's default host resolver. 82// (i.e. this calls out to getaddrinfo()). If successful returns OK and fills 83// |addrlist| with a list of socket addresses. Otherwise returns a 84// network error code, and fills |os_error| with a more specific errir if it 85// was non-NULL. 86int SystemHostResolverProc(const std::string& host, 87 AddressFamily address_family, 88 HostResolverFlags host_resolver_flags, 89 AddressList* addrlist, 90 int* os_error); 91 92} // namespace net 93 94#endif // NET_BASE_HOST_RESOLVER_PROC_H_ 95