host_resolver_impl.h revision 2a99a7e74a7f215066514fe81d2bfa6639d9eddd
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_IMPL_H_ 6#define NET_DNS_HOST_RESOLVER_IMPL_H_ 7 8#include <map> 9 10#include "base/basictypes.h" 11#include "base/gtest_prod_util.h" 12#include "base/memory/scoped_ptr.h" 13#include "base/memory/scoped_vector.h" 14#include "base/memory/weak_ptr.h" 15#include "base/threading/non_thread_safe.h" 16#include "base/time.h" 17#include "net/base/capturing_net_log.h" 18#include "net/base/host_cache.h" 19#include "net/base/net_export.h" 20#include "net/base/network_change_notifier.h" 21#include "net/base/prioritized_dispatcher.h" 22#include "net/dns/host_resolver.h" 23#include "net/dns/host_resolver_proc.h" 24 25namespace net { 26 27class BoundNetLog; 28class DnsClient; 29class NetLog; 30 31// For each hostname that is requested, HostResolver creates a 32// HostResolverImpl::Job. When this job gets dispatched it creates a ProcTask 33// which runs the given HostResolverProc on a WorkerPool thread. If requests for 34// that same host are made during the job's lifetime, they are attached to the 35// existing job rather than creating a new one. This avoids doing parallel 36// resolves for the same host. 37// 38// The way these classes fit together is illustrated by: 39// 40// 41// +----------- HostResolverImpl -------------+ 42// | | | 43// Job Job Job 44// (for host1, fam1) (for host2, fam2) (for hostx, famx) 45// / | | / | | / | | 46// Request ... Request Request ... Request Request ... Request 47// (port1) (port2) (port3) (port4) (port5) (portX) 48// 49// When a HostResolverImpl::Job finishes, the callbacks of each waiting request 50// are run on the origin thread. 51// 52// Thread safety: This class is not threadsafe, and must only be called 53// from one thread! 54// 55// The HostResolverImpl enforces limits on the maximum number of concurrent 56// threads using PrioritizedDispatcher::Limits. 57// 58// Jobs are ordered in the queue based on their priority and order of arrival. 59class NET_EXPORT HostResolverImpl 60 : public HostResolver, 61 NON_EXPORTED_BASE(public base::NonThreadSafe), 62 public NetworkChangeNotifier::IPAddressObserver, 63 public NetworkChangeNotifier::DNSObserver { 64 public: 65 // Parameters for ProcTask which resolves hostnames using HostResolveProc. 66 // 67 // |resolver_proc| is used to perform the actual resolves; it must be 68 // thread-safe since it is run from multiple worker threads. If 69 // |resolver_proc| is NULL then the default host resolver procedure is 70 // used (which is SystemHostResolverProc except if overridden). 71 // 72 // For each attempt, we could start another attempt if host is not resolved 73 // within |unresponsive_delay| time. We keep attempting to resolve the host 74 // for |max_retry_attempts|. For every retry attempt, we grow the 75 // |unresponsive_delay| by the |retry_factor| amount (that is retry interval 76 // is multiplied by the retry factor each time). Once we have retried 77 // |max_retry_attempts|, we give up on additional attempts. 78 // 79 struct NET_EXPORT_PRIVATE ProcTaskParams { 80 // Sets up defaults. 81 ProcTaskParams(HostResolverProc* resolver_proc, size_t max_retry_attempts); 82 83 ~ProcTaskParams(); 84 85 // The procedure to use for resolving host names. This will be NULL, except 86 // in the case of unit-tests which inject custom host resolving behaviors. 87 scoped_refptr<HostResolverProc> resolver_proc; 88 89 // Maximum number retry attempts to resolve the hostname. 90 // Pass HostResolver::kDefaultRetryAttempts to choose a default value. 91 size_t max_retry_attempts; 92 93 // This is the limit after which we make another attempt to resolve the host 94 // if the worker thread has not responded yet. 95 base::TimeDelta unresponsive_delay; 96 97 // Factor to grow |unresponsive_delay| when we re-re-try. 98 uint32 retry_factor; 99 }; 100 101 // Creates a HostResolver that first uses the local cache |cache|, and then 102 // falls back to |proc_params.resolver_proc|. 103 // 104 // If |cache| is NULL, then no caching is used. Otherwise we take 105 // ownership of the |cache| pointer, and will free it during destruction. 106 // 107 // |job_limits| specifies the maximum number of jobs that the resolver will 108 // run at once. This upper-bounds the total number of outstanding 109 // DNS transactions (not counting retransmissions and retries). 110 // 111 // |net_log| must remain valid for the life of the HostResolverImpl. 112 HostResolverImpl(scoped_ptr<HostCache> cache, 113 const PrioritizedDispatcher::Limits& job_limits, 114 const ProcTaskParams& proc_params, 115 NetLog* net_log); 116 117 // If any completion callbacks are pending when the resolver is destroyed, 118 // the host resolutions are cancelled, and the completion callbacks will not 119 // be called. 120 virtual ~HostResolverImpl(); 121 122 // Configures maximum number of Jobs in the queue. Exposed for testing. 123 // Only allowed when the queue is empty. 124 void SetMaxQueuedJobs(size_t value); 125 126 // Set the DnsClient to be used for resolution. In case of failure, the 127 // HostResolverProc from ProcTaskParams will be queried. If the DnsClient is 128 // not pre-configured with a valid DnsConfig, a new config is fetched from 129 // NetworkChangeNotifier. 130 void SetDnsClient(scoped_ptr<DnsClient> dns_client); 131 132 // HostResolver methods: 133 virtual int Resolve(const RequestInfo& info, 134 AddressList* addresses, 135 const CompletionCallback& callback, 136 RequestHandle* out_req, 137 const BoundNetLog& source_net_log) OVERRIDE; 138 virtual int ResolveFromCache(const RequestInfo& info, 139 AddressList* addresses, 140 const BoundNetLog& source_net_log) OVERRIDE; 141 virtual void CancelRequest(RequestHandle req) OVERRIDE; 142 virtual void SetDefaultAddressFamily(AddressFamily address_family) OVERRIDE; 143 virtual AddressFamily GetDefaultAddressFamily() const OVERRIDE; 144 virtual void ProbeIPv6Support() OVERRIDE; 145 virtual void SetDnsClientEnabled(bool enabled) OVERRIDE; 146 virtual HostCache* GetHostCache() OVERRIDE; 147 virtual base::Value* GetDnsConfigAsValue() const OVERRIDE; 148 149 private: 150 friend class HostResolverImplTest; 151 class Job; 152 class ProcTask; 153 class IPv6ProbeJob; 154 class LoopbackProbeJob; 155 class DnsTask; 156 class Request; 157 typedef HostCache::Key Key; 158 typedef std::map<Key, Job*> JobMap; 159 typedef ScopedVector<Request> RequestsList; 160 161 // Helper used by |Resolve()| and |ResolveFromCache()|. Performs IP 162 // literal, cache and HOSTS lookup (if enabled), returns OK if successful, 163 // ERR_NAME_NOT_RESOLVED if either hostname is invalid or IP literal is 164 // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache and HOSTS. 165 int ResolveHelper(const Key& key, 166 const RequestInfo& info, 167 AddressList* addresses, 168 const BoundNetLog& request_net_log); 169 170 // Tries to resolve |key| as an IP, returns true and sets |net_error| if 171 // succeeds, returns false otherwise. 172 bool ResolveAsIP(const Key& key, 173 const RequestInfo& info, 174 int* net_error, 175 AddressList* addresses); 176 177 // If |key| is not found in cache returns false, otherwise returns 178 // true, sets |net_error| to the cached error code and fills |addresses| 179 // if it is a positive entry. 180 bool ServeFromCache(const Key& key, 181 const RequestInfo& info, 182 int* net_error, 183 AddressList* addresses); 184 185 // If we have a DnsClient with a valid DnsConfig, and |key| is found in the 186 // HOSTS file, returns true and fills |addresses|. Otherwise returns false. 187 bool ServeFromHosts(const Key& key, 188 const RequestInfo& info, 189 AddressList* addresses); 190 191 // Callback from IPv6 probe activity. 192 void IPv6ProbeSetDefaultAddressFamily(AddressFamily address_family); 193 194 // Callback from HaveOnlyLoopbackAddresses probe. 195 void SetHaveOnlyLoopbackAddresses(bool result); 196 197 // Returns the (hostname, address_family) key to use for |info|, choosing an 198 // "effective" address family by inheriting the resolver's default address 199 // family when the request leaves it unspecified. 200 Key GetEffectiveKeyForRequest(const RequestInfo& info) const; 201 202 // Records the result in cache if cache is present. 203 void CacheResult(const Key& key, 204 const HostCache::Entry& entry, 205 base::TimeDelta ttl); 206 207 // Removes |job| from |jobs_|, only if it exists. 208 void RemoveJob(Job* job); 209 210 // Aborts all in progress jobs with ERR_NETWORK_CHANGED and notifies their 211 // requests. Might start new jobs. 212 void AbortAllInProgressJobs(); 213 214 // Attempts to serve each Job in |jobs_| from the HOSTS file if we have 215 // a DnsClient with a valid DnsConfig. 216 void TryServingAllJobsFromHosts(); 217 218 // NetworkChangeNotifier::IPAddressObserver: 219 virtual void OnIPAddressChanged() OVERRIDE; 220 221 // NetworkChangeNotifier::DNSObserver: 222 virtual void OnDNSChanged() OVERRIDE; 223 224 // True if have a DnsClient with a valid DnsConfig. 225 bool HaveDnsConfig() const; 226 227 // Called when a host name is successfully resolved and DnsTask was run on it 228 // and resulted in |net_error|. 229 void OnDnsTaskResolve(int net_error); 230 231 // Allows the tests to catch slots leaking out of the dispatcher. 232 size_t num_running_jobs_for_tests() const { 233 return dispatcher_.num_running_jobs(); 234 } 235 236 // Cache of host resolution results. 237 scoped_ptr<HostCache> cache_; 238 239 // Map from HostCache::Key to a Job. 240 JobMap jobs_; 241 242 // Starts Jobs according to their priority and the configured limits. 243 PrioritizedDispatcher dispatcher_; 244 245 // Limit on the maximum number of jobs queued in |dispatcher_|. 246 size_t max_queued_jobs_; 247 248 // Parameters for ProcTask. 249 ProcTaskParams proc_params_; 250 251 NetLog* net_log_; 252 253 // Address family to use when the request doesn't specify one. 254 AddressFamily default_address_family_; 255 256 base::WeakPtrFactory<HostResolverImpl> weak_ptr_factory_; 257 258 base::WeakPtrFactory<HostResolverImpl> probe_weak_ptr_factory_; 259 260 // If present, used by DnsTask and ServeFromHosts to resolve requests. 261 scoped_ptr<DnsClient> dns_client_; 262 263 // True if received valid config from |dns_config_service_|. Temporary, used 264 // to measure performance of DnsConfigService: http://crbug.com/125599 265 bool received_dns_config_; 266 267 // Number of consecutive failures of DnsTask, counted when fallback succeeds. 268 unsigned num_dns_failures_; 269 270 // Indicate if probing is done after each network change event to set address 271 // family. When false, explicit setting of address family is used and results 272 // of the IPv6 probe job are ignored. 273 bool ipv6_probe_monitoring_; 274 275 // True iff ProcTask has successfully resolved a hostname known to have IPv6 276 // addresses using ADDRESS_FAMILY_UNSPECIFIED. Reset on IP address change. 277 bool resolved_known_ipv6_hostname_; 278 279 // Any resolver flags that should be added to a request by default. 280 HostResolverFlags additional_resolver_flags_; 281 282 DISALLOW_COPY_AND_ASSIGN(HostResolverImpl); 283}; 284 285} // namespace net 286 287#endif // NET_DNS_HOST_RESOLVER_IMPL_H_ 288