diff options
Diffstat (limited to 'chromium/net/dns/host_resolver_impl.h')
| -rw-r--r-- | chromium/net/dns/host_resolver_impl.h | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/chromium/net/dns/host_resolver_impl.h b/chromium/net/dns/host_resolver_impl.h new file mode 100644 index 00000000000..928d07af8b8 --- /dev/null +++ b/chromium/net/dns/host_resolver_impl.h @@ -0,0 +1,285 @@ +// Copyright (c) 2012 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef NET_DNS_HOST_RESOLVER_IMPL_H_ +#define NET_DNS_HOST_RESOLVER_IMPL_H_ + +#include <map> + +#include "base/basictypes.h" +#include "base/gtest_prod_util.h" +#include "base/memory/scoped_ptr.h" +#include "base/memory/scoped_vector.h" +#include "base/memory/weak_ptr.h" +#include "base/threading/non_thread_safe.h" +#include "base/time/time.h" +#include "net/base/capturing_net_log.h" +#include "net/base/net_export.h" +#include "net/base/network_change_notifier.h" +#include "net/base/prioritized_dispatcher.h" +#include "net/dns/host_cache.h" +#include "net/dns/host_resolver.h" +#include "net/dns/host_resolver_proc.h" + +namespace net { + +class BoundNetLog; +class DnsClient; +class NetLog; + +// For each hostname that is requested, HostResolver creates a +// HostResolverImpl::Job. When this job gets dispatched it creates a ProcTask +// which runs the given HostResolverProc on a WorkerPool thread. If requests for +// that same host are made during the job's lifetime, they are attached to the +// existing job rather than creating a new one. This avoids doing parallel +// resolves for the same host. +// +// The way these classes fit together is illustrated by: +// +// +// +----------- HostResolverImpl -------------+ +// | | | +// Job Job Job +// (for host1, fam1) (for host2, fam2) (for hostx, famx) +// / | | / | | / | | +// Request ... Request Request ... Request Request ... Request +// (port1) (port2) (port3) (port4) (port5) (portX) +// +// When a HostResolverImpl::Job finishes, the callbacks of each waiting request +// are run on the origin thread. +// +// Thread safety: This class is not threadsafe, and must only be called +// from one thread! +// +// The HostResolverImpl enforces limits on the maximum number of concurrent +// threads using PrioritizedDispatcher::Limits. +// +// Jobs are ordered in the queue based on their priority and order of arrival. +class NET_EXPORT HostResolverImpl + : public HostResolver, + NON_EXPORTED_BASE(public base::NonThreadSafe), + public NetworkChangeNotifier::IPAddressObserver, + public NetworkChangeNotifier::DNSObserver { + public: + // Parameters for ProcTask which resolves hostnames using HostResolveProc. + // + // |resolver_proc| is used to perform the actual resolves; it must be + // thread-safe since it is run from multiple worker threads. If + // |resolver_proc| is NULL then the default host resolver procedure is + // used (which is SystemHostResolverProc except if overridden). + // + // For each attempt, we could start another attempt if host is not resolved + // within |unresponsive_delay| time. We keep attempting to resolve the host + // for |max_retry_attempts|. For every retry attempt, we grow the + // |unresponsive_delay| by the |retry_factor| amount (that is retry interval + // is multiplied by the retry factor each time). Once we have retried + // |max_retry_attempts|, we give up on additional attempts. + // + struct NET_EXPORT_PRIVATE ProcTaskParams { + // Sets up defaults. + ProcTaskParams(HostResolverProc* resolver_proc, size_t max_retry_attempts); + + ~ProcTaskParams(); + + // The procedure to use for resolving host names. This will be NULL, except + // in the case of unit-tests which inject custom host resolving behaviors. + scoped_refptr<HostResolverProc> resolver_proc; + + // Maximum number retry attempts to resolve the hostname. + // Pass HostResolver::kDefaultRetryAttempts to choose a default value. + size_t max_retry_attempts; + + // This is the limit after which we make another attempt to resolve the host + // if the worker thread has not responded yet. + base::TimeDelta unresponsive_delay; + + // Factor to grow |unresponsive_delay| when we re-re-try. + uint32 retry_factor; + }; + + // Creates a HostResolver that first uses the local cache |cache|, and then + // falls back to |proc_params.resolver_proc|. + // + // If |cache| is NULL, then no caching is used. Otherwise we take + // ownership of the |cache| pointer, and will free it during destruction. + // + // |job_limits| specifies the maximum number of jobs that the resolver will + // run at once. This upper-bounds the total number of outstanding + // DNS transactions (not counting retransmissions and retries). + // + // |net_log| must remain valid for the life of the HostResolverImpl. + HostResolverImpl(scoped_ptr<HostCache> cache, + const PrioritizedDispatcher::Limits& job_limits, + const ProcTaskParams& proc_params, + NetLog* net_log); + + // If any completion callbacks are pending when the resolver is destroyed, + // the host resolutions are cancelled, and the completion callbacks will not + // be called. + virtual ~HostResolverImpl(); + + // Configures maximum number of Jobs in the queue. Exposed for testing. + // Only allowed when the queue is empty. + void SetMaxQueuedJobs(size_t value); + + // Set the DnsClient to be used for resolution. In case of failure, the + // HostResolverProc from ProcTaskParams will be queried. If the DnsClient is + // not pre-configured with a valid DnsConfig, a new config is fetched from + // NetworkChangeNotifier. + void SetDnsClient(scoped_ptr<DnsClient> dns_client); + + // HostResolver methods: + virtual int Resolve(const RequestInfo& info, + AddressList* addresses, + const CompletionCallback& callback, + RequestHandle* out_req, + const BoundNetLog& source_net_log) OVERRIDE; + virtual int ResolveFromCache(const RequestInfo& info, + AddressList* addresses, + const BoundNetLog& source_net_log) OVERRIDE; + virtual void CancelRequest(RequestHandle req) OVERRIDE; + virtual void SetDefaultAddressFamily(AddressFamily address_family) OVERRIDE; + virtual AddressFamily GetDefaultAddressFamily() const OVERRIDE; + virtual void SetDnsClientEnabled(bool enabled) OVERRIDE; + virtual HostCache* GetHostCache() OVERRIDE; + virtual base::Value* GetDnsConfigAsValue() const OVERRIDE; + + private: + friend class HostResolverImplTest; + class Job; + class ProcTask; + class LoopbackProbeJob; + class DnsTask; + class Request; + typedef HostCache::Key Key; + typedef std::map<Key, Job*> JobMap; + typedef ScopedVector<Request> RequestsList; + + // Helper used by |Resolve()| and |ResolveFromCache()|. Performs IP + // literal, cache and HOSTS lookup (if enabled), returns OK if successful, + // ERR_NAME_NOT_RESOLVED if either hostname is invalid or IP literal is + // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache and HOSTS. + int ResolveHelper(const Key& key, + const RequestInfo& info, + AddressList* addresses, + const BoundNetLog& request_net_log); + + // Tries to resolve |key| as an IP, returns true and sets |net_error| if + // succeeds, returns false otherwise. + bool ResolveAsIP(const Key& key, + const RequestInfo& info, + int* net_error, + AddressList* addresses); + + // If |key| is not found in cache returns false, otherwise returns + // true, sets |net_error| to the cached error code and fills |addresses| + // if it is a positive entry. + bool ServeFromCache(const Key& key, + const RequestInfo& info, + int* net_error, + AddressList* addresses); + + // If we have a DnsClient with a valid DnsConfig, and |key| is found in the + // HOSTS file, returns true and fills |addresses|. Otherwise returns false. + bool ServeFromHosts(const Key& key, + const RequestInfo& info, + AddressList* addresses); + + // Callback from HaveOnlyLoopbackAddresses probe. + void SetHaveOnlyLoopbackAddresses(bool result); + + // Returns the (hostname, address_family) key to use for |info|, choosing an + // "effective" address family by inheriting the resolver's default address + // family when the request leaves it unspecified. + Key GetEffectiveKeyForRequest(const RequestInfo& info, + const BoundNetLog& net_log) const; + + // Records the result in cache if cache is present. + void CacheResult(const Key& key, + const HostCache::Entry& entry, + base::TimeDelta ttl); + + // Removes |job| from |jobs_|, only if it exists. + void RemoveJob(Job* job); + + // Aborts all in progress jobs with ERR_NETWORK_CHANGED and notifies their + // requests. Might start new jobs. + void AbortAllInProgressJobs(); + + // Attempts to serve each Job in |jobs_| from the HOSTS file if we have + // a DnsClient with a valid DnsConfig. + void TryServingAllJobsFromHosts(); + + // NetworkChangeNotifier::IPAddressObserver: + virtual void OnIPAddressChanged() OVERRIDE; + + // NetworkChangeNotifier::DNSObserver: + virtual void OnDNSChanged() OVERRIDE; + + // True if have a DnsClient with a valid DnsConfig. + bool HaveDnsConfig() const; + + // Called when a host name is successfully resolved and DnsTask was run on it + // and resulted in |net_error|. + void OnDnsTaskResolve(int net_error); + + // Allows the tests to catch slots leaking out of the dispatcher. + size_t num_running_jobs_for_tests() const { + return dispatcher_.num_running_jobs(); + } + + // Cache of host resolution results. + scoped_ptr<HostCache> cache_; + + // Map from HostCache::Key to a Job. + JobMap jobs_; + + // Starts Jobs according to their priority and the configured limits. + PrioritizedDispatcher dispatcher_; + + // Limit on the maximum number of jobs queued in |dispatcher_|. + size_t max_queued_jobs_; + + // Parameters for ProcTask. + ProcTaskParams proc_params_; + + NetLog* net_log_; + + // Address family to use when the request doesn't specify one. + AddressFamily default_address_family_; + + base::WeakPtrFactory<HostResolverImpl> weak_ptr_factory_; + + base::WeakPtrFactory<HostResolverImpl> probe_weak_ptr_factory_; + + // If present, used by DnsTask and ServeFromHosts to resolve requests. + scoped_ptr<DnsClient> dns_client_; + + // True if received valid config from |dns_config_service_|. Temporary, used + // to measure performance of DnsConfigService: http://crbug.com/125599 + bool received_dns_config_; + + // Number of consecutive failures of DnsTask, counted when fallback succeeds. + unsigned num_dns_failures_; + + // True if probing is done for each Request to set address family. When false, + // explicit setting in |default_address_family_| is used. + bool probe_ipv6_support_; + + // True iff ProcTask has successfully resolved a hostname known to have IPv6 + // addresses using ADDRESS_FAMILY_UNSPECIFIED. Reset on IP address change. + bool resolved_known_ipv6_hostname_; + + // Any resolver flags that should be added to a request by default. + HostResolverFlags additional_resolver_flags_; + + // Allow fallback to ProcTask if DnsTask fails. + bool fallback_to_proctask_; + + DISALLOW_COPY_AND_ASSIGN(HostResolverImpl); +}; + +} // namespace net + +#endif // NET_DNS_HOST_RESOLVER_IMPL_H_ |