blob: 9151dec50cc2c70da68b15c1b30eeed17e01f87a [file] [log] [blame]
// 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.
#include <stddef.h>
#include <stdint.h>
#include <deque>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <vector>
#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "net/base/completion_once_callback.h"
#include "net/base/network_change_notifier.h"
#include "net/base/prioritized_dispatcher.h"
#include "net/dns/dns_config.h"
#include "net/dns/dns_config_overrides.h"
#include "net/dns/host_cache.h"
#include "net/dns/host_resolver.h"
#include "net/dns/host_resolver_proc.h"
#include "net/dns/public/dns_query_type.h"
#include "net/dns/resolve_context.h"
#include "net/dns/system_dns_config_change_notifier.h"
#include "url/gurl.h"
namespace base {
class TickClock;
} // namespace base
namespace net {
class AddressList;
class DnsClient;
class DnsProbeRunner;
class HostPortPair;
class IPAddress;
class MDnsClient;
class MDnsSocketFactory;
class NetLog;
class NetLogWithSource;
class NetworkIsolationKey;
// Scheduler and controller of host resolution requests. Because of the global
// nature of host resolutions, this class is generally expected to be singleton
// within the browser and only be interacted with through per-context
// ContextHostResolver objects (which are themselves generally interacted with
// though the HostResolver interface).
// For each hostname that is requested, HostResolver creates a
// HostResolverManager::Job. When this job gets dispatched it creates a task
// (ProcTask for the system resolver or DnsTask for the async resolver) which
// resolves the hostname. 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:
// +----------- HostResolverManager ----------+
// | | |
// 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 HostResolverManager::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 HostResolverManager 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 HostResolverManager
: public NetworkChangeNotifier::IPAddressObserver,
public NetworkChangeNotifier::ConnectionTypeObserver,
public SystemDnsConfigChangeNotifier::Observer {
using MdnsListener = HostResolver::MdnsListener;
using ResolveHostParameters = HostResolver::ResolveHostParameters;
using SecureDnsMode = DnsConfig::SecureDnsMode;
// A request that allows explicit cancellation before destruction. Enables
// callers (e.g. ContextHostResolver) to implement cancellation of requests on
// the callers' destruction.
class CancellableRequest {
CancellableRequest() = default;
CancellableRequest(const CancellableRequest&) = delete;
CancellableRequest& operator=(const CancellableRequest&) = delete;
virtual ~CancellableRequest() = default;
// If running asynchronously, silently cancels the request as if destroyed.
// Callbacks will never be invoked. Noop if request is already complete or
// never started.
virtual void Cancel() = 0;
// CancellableRequest versions of different request types.
class CancellableResolveHostRequest
: public CancellableRequest,
public HostResolver::ResolveHostRequest {};
class CancellableProbeRequest : public CancellableRequest,
public HostResolver::ProbeRequest {};
// Creates a HostResolver as specified by |options|. Blocking tasks are run in
// ThreadPool.
// If Options.enable_caching is true, a cache is created using
// HostCache::CreateDefaultCache(). Otherwise no cache is used.
// Options.GetDispatcherLimits() determines 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| and |system_dns_config_notifier|, if non-null, must remain valid
// for the life of the HostResolverManager.
HostResolverManager(const HostResolver::ManagerOptions& options,
SystemDnsConfigChangeNotifier* system_dns_config_notifier,
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.
~HostResolverManager() override;
// |resolve_context| must have already been added (via
// RegisterResolveContext()). If |optional_parameters| specifies any cache
// usage other than LOCAL_ONLY, there must be a 1:1 correspondence between
// |resolve_context| and |host_cache|, and both should come from the same
// ContextHostResolver.
// TODO( Use the HostCache out of the ResolveContext
// instead of passing it separately.
std::unique_ptr<CancellableResolveHostRequest> CreateRequest(
const HostPortPair& host,
const NetworkIsolationKey& network_isolation_key,
const NetLogWithSource& net_log,
const base::Optional<ResolveHostParameters>& optional_parameters,
ResolveContext* resolve_context,
HostCache* host_cache);
// |resolve_context| is the context to use for the probes, and it is expected
// to be the context of the calling ContextHostResolver.
std::unique_ptr<CancellableProbeRequest> CreateDohProbeRequest(
ResolveContext* resolvet_context);
std::unique_ptr<MdnsListener> CreateMdnsListener(const HostPortPair& host,
DnsQueryType query_type);
// Enables or disables the built-in asynchronous DnsClient. If enabled, by
// default (when no |ResolveHostParameters::source| is specified), the
// DnsClient will be used for resolves and, in case of failure, resolution
// will fallback to the system resolver (HostResolverProc from
// ProcTaskParams). If the DnsClient is not pre-configured with a valid
// DnsConfig, a new config is fetched from NetworkChangeNotifier.
// Setting to |true| has no effect if |ENABLE_BUILT_IN_DNS| not defined.
virtual void SetInsecureDnsClientEnabled(bool enabled);
std::unique_ptr<base::Value> GetDnsConfigAsValue() const;
// Sets overriding configuration that will replace or add to configuration
// read from the system for DnsClient resolution.
void SetDnsConfigOverrides(DnsConfigOverrides overrides);
// Support for invalidating cached per-context data on changes to network or
// DNS configuration. ContextHostResolvers should register/deregister
// themselves here rather than attempting to listen for relevant network
// change signals themselves because HostResolverManager needs to coordinate
// invalidations with in-progress resolves and because some invalidations are
// triggered by changes to manager properties/configuration rather than pure
// network changes.
// Note: Invalidation handling must not call back into HostResolverManager as
// the invalidation is expected to be handled atomically with other clearing
// and aborting actions.
void RegisterResolveContext(ResolveContext* context);
void DeregisterResolveContext(const ResolveContext* context);
void set_proc_params_for_test(const ProcTaskParams& proc_params) {
proc_params_ = proc_params;
void InvalidateCachesForTesting() { InvalidateCaches(); }
void SetTickClockForTesting(const base::TickClock* tick_clock);
// Configures maximum number of Jobs in the queue. Exposed for testing.
// Only allowed when the queue is empty.
void SetMaxQueuedJobsForTesting(size_t value);
void SetMdnsSocketFactoryForTesting(
std::unique_ptr<MDnsSocketFactory> socket_factory);
void SetMdnsClientForTesting(std::unique_ptr<MDnsClient> client);
// To simulate modifications it would have received if |dns_client| had been
// in place before calling this, DnsConfig will be set with the configuration
// from the previous DnsClient being replaced (including system config if
// |dns_client| does not already contain a system config). This means tests do
// not normally need to worry about ordering between setting a test client and
// setting DnsConfig.
void SetDnsClientForTesting(std::unique_ptr<DnsClient> dns_client);
// Sets the last IPv6 probe result for testing. Uses the standard timeout
// duration, so it's up to the test fixture to ensure it doesn't expire by
// mocking time, if expiration would pose a problem.
void SetLastIPv6ProbeResultForTesting(bool last_ipv6_probe_result);
// Allows the tests to catch slots leaking out of the dispatcher. One
// HostResolverManager::Job could occupy multiple PrioritizedDispatcher job
// slots.
size_t num_running_dispatcher_jobs_for_tests() const {
return dispatcher_->num_running_jobs();
size_t num_jobs_for_testing() const { return jobs_.size(); }
bool check_ipv6_on_wifi_for_testing() const { return check_ipv6_on_wifi_; }
// Callback from HaveOnlyLoopbackAddresses probe.
void SetHaveOnlyLoopbackAddresses(bool result);
// Sets the task runner used for HostResolverProc tasks.
void SetTaskRunnerForTesting(scoped_refptr<base::TaskRunner> task_runner);
friend class HostResolverManagerTest;
friend class HostResolverManagerDnsTest;
class Job;
struct JobKey;
class ProcTask;
class LoopbackProbeJob;
class DnsTask;
class RequestImpl;
class ProbeRequestImpl;
using JobMap = std::map<JobKey, std::unique_ptr<Job>>;
// Task types that a Job might run.
enum class TaskType {
// Attempts host resolution for |request|. Generally only expected to be
// called from RequestImpl::Start().
int Resolve(RequestImpl* request);
// Attempts host resolution using fast local sources: IP literal resolution,
// cache lookup, HOSTS lookup (if enabled), and localhost. Returns results
// with error() OK if successful, ERR_NAME_NOT_RESOLVED if input is invalid,
// or ERR_DNS_CACHE_MISS if the host could not be resolved using local
// sources.
// On ERR_DNS_CACHE_MISS and OK, effective request parameters are written to
// |out_effective_query_type|, |out_effective_host_resolver_flags|, and
// |out_effective_secure_dns_mode|. |out_tasks| contains the tentative
// sequence of tasks that a future job should run.
// If results are returned from the host cache, |out_stale_info| will be
// filled in with information on how stale or fresh the result is. Otherwise,
// |out_stale_info| will be set to |base::nullopt|.
// If |cache_usage == ResolveHostParameters::CacheUsage::STALE_ALLOWED|, then
// stale cache entries can be returned.
HostCache::Entry ResolveLocally(
const std::string& hostname,
const NetworkIsolationKey& network_isolation_key,
DnsQueryType requested_address_family,
HostResolverSource source,
HostResolverFlags flags,
base::Optional<SecureDnsMode> secure_dns_mode_override,
ResolveHostParameters::CacheUsage cache_usage,
const NetLogWithSource& request_net_log,
HostCache* cache,
ResolveContext* resolve_context,
DnsQueryType* out_effective_query_type,
HostResolverFlags* out_effective_host_resolver_flags,
DnsConfig::SecureDnsMode* out_effective_secure_dns_mode,
std::deque<TaskType>* out_tasks,
base::Optional<HostCache::EntryStaleness>* out_stale_info);
// Creates and starts a Job to asynchronously attempt to resolve
// |request|.
void CreateAndStartJob(DnsQueryType effective_query_type,
HostResolverFlags effective_host_resolver_flags,
DnsConfig::SecureDnsMode effective_secure_dns_mode,
std::deque<TaskType> tasks,
RequestImpl* request);
// Tries to resolve |key| and its possible IP address representation,
// |ip_address|. Returns a results entry iff the input can be resolved.
base::Optional<HostCache::Entry> ResolveAsIP(DnsQueryType query_type,
bool resolve_canonname,
const IPAddress* ip_address);
// Returns the result iff |cache_usage| permits cache lookups and a positive
// match is found for |key| in |cache|. |out_stale_info| must be non-null, and
// will be filled in with details of the entry's staleness if an entry is
// returned, otherwise it will be set to |base::nullopt|.
base::Optional<HostCache::Entry> MaybeServeFromCache(
HostCache* cache,
const HostCache::Key& key,
ResolveHostParameters::CacheUsage cache_usage,
bool ignore_secure,
const NetLogWithSource& source_net_log,
base::Optional<HostCache::EntryStaleness>* out_stale_info);
// Iff we have a DnsClient with a valid DnsConfig and we're not about to
// attempt a system lookup, then try to resolve the query using the HOSTS
// file.
base::Optional<HostCache::Entry> ServeFromHosts(
base::StringPiece hostname,
DnsQueryType query_type,
bool default_family_due_to_no_ipv6,
const std::deque<TaskType>& tasks);
// Iff |key| is for a localhost name (RFC 6761) and address DNS query type,
// returns a results entry with the loopback IP.
base::Optional<HostCache::Entry> ServeLocalhost(
base::StringPiece hostname,
DnsQueryType query_type,
bool default_family_due_to_no_ipv6);
// Returns the secure dns mode to use for a job, taking into account the
// global DnsConfig mode and any per-request override. Requests matching DoH
// server hostnames are downgraded to off mode to avoid infinite loops.
SecureDnsMode GetEffectiveSecureDnsMode(
const std::string& hostname,
base::Optional<SecureDnsMode> secure_dns_mode_override);
// Returns true if a catch-all DNS block has been set for unit tests. No
// DnsTasks should be issued in this case.
bool HaveTestProcOverride();
// Helper method to add DnsTasks and related tasks based on the SecureDnsMode
// and fallback parameters. If |prioritize_local_lookups| is true, then we
// may push an insecure cache lookup ahead of a secure DnsTask.
void PushDnsTasks(bool proc_task_allowed,
SecureDnsMode secure_dns_mode,
bool insecure_tasks_allowed,
bool allow_cache,
bool prioritize_local_lookups,
ResolveContext* resolve_context,
std::deque<TaskType>* out_tasks);
// Initialized the sequence of tasks to run to resolve a request. The sequence
// may be adjusted later and not all tasks need to be run.
void CreateTaskSequence(
const std::string& hostname,
DnsQueryType dns_query_type,
HostResolverSource source,
HostResolverFlags flags,
base::Optional<SecureDnsMode> secure_dns_mode_override,
ResolveHostParameters::CacheUsage cache_usage,
ResolveContext* resolve_context,
DnsConfig::SecureDnsMode* out_effective_secure_dns_mode,
std::deque<TaskType>* out_tasks);
// Determines "effective" request parameters using manager properties and IPv6
// reachability.
void GetEffectiveParametersForRequest(
const std::string& hostname,
DnsQueryType dns_query_type,
HostResolverSource source,
HostResolverFlags flags,
base::Optional<SecureDnsMode> secure_dns_mode_override,
ResolveHostParameters::CacheUsage cache_usage,
const IPAddress* ip_address,
const NetLogWithSource& net_log,
ResolveContext* resolve_context,
DnsQueryType* out_effective_type,
HostResolverFlags* out_effective_flags,
DnsConfig::SecureDnsMode* out_effective_secure_dns_mode,
std::deque<TaskType>* out_tasks);
// Probes IPv6 support and returns true if IPv6 support is enabled.
// Results are cached, i.e. when called repeatedly this method returns result
// from the first probe for some time before probing again.
bool IsIPv6Reachable(const NetLogWithSource& net_log);
// Sets |last_ipv6_probe_result_| and updates |last_ipv6_probe_time_|.
void SetLastIPv6ProbeResult(bool last_ipv6_probe_result);
// Attempts to connect a UDP socket to |dest|:53. Virtual for testing.
virtual bool IsGloballyReachable(const IPAddress& dest,
const NetLogWithSource& net_log);
// Asynchronously checks if only loopback IPs are available.
virtual void RunLoopbackProbeJob();
// Records the result in cache if cache is present.
void CacheResult(HostCache* cache,
const HostCache::Key& key,
const HostCache::Entry& entry,
base::TimeDelta ttl);
// Record time from Request creation until a valid DNS response.
void RecordTotalTime(bool speculative,
bool from_cache,
DnsConfig::SecureDnsMode secure_dns_mode,
base::TimeDelta duration) const;
// Removes |job_it| from |jobs_| and return.
std::unique_ptr<Job> RemoveJob(JobMap::iterator job_it);
// Aborts both scheduled and running jobs with ERR_NETWORK_CHANGED and
// notifies their requests. Aborts only running jobs if |in_progress_only| is
// true. Might start new jobs.
void AbortAllJobs(bool in_progress_only);
// Aborts all in progress insecure DnsTasks. In-progress jobs will fall back
// to ProcTasks if able and otherwise abort with |error|. Might start new
// jobs, if any jobs were taking up two dispatcher slots.
// If |fallback_only|, insecure DnsTasks will only abort if they can fallback
// to ProcTask.
void AbortInsecureDnsTasks(int error, bool fallback_only);
// Attempts to serve each Job in |jobs_| from the HOSTS file if we have
// a DnsClient with a valid DnsConfig.
void TryServingAllJobsFromHosts();
// NetworkChangeNotifier::IPAddressObserver:
void OnIPAddressChanged() override;
// NetworkChangeNotifier::ConnectionTypeObserver:
void OnConnectionTypeChanged(
NetworkChangeNotifier::ConnectionType type) override;
// SystemDnsConfigChangeNotifier::Observer:
void OnSystemDnsConfigChanged(base::Optional<DnsConfig> config) override;
void UpdateJobsForChangedConfig();
// Called on successful resolve after falling back to ProcTask after a failed
// DnsTask resolve.
void OnFallbackResolve(int dns_task_error);
int GetOrCreateMdnsClient(MDnsClient** out_client);
void InvalidateCaches();
// Returns |nullptr| if DoH probes are currently not allowed (due to
// configuration or current connection state).
std::unique_ptr<DnsProbeRunner> CreateDohProbeRunner(
ResolveContext* resolve_context);
// Used for multicast DNS tasks. Created on first use using
// GetOrCreateMndsClient().
std::unique_ptr<MDnsSocketFactory> mdns_socket_factory_;
std::unique_ptr<MDnsClient> mdns_client_;
// Map from HostCache::Key to a Job.
JobMap jobs_;
// Starts Jobs according to their priority and the configured limits.
std::unique_ptr<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_;
std::set<ProbeRequestImpl*> started_doh_probe_requests_;
// If present, used by DnsTask and ServeFromHosts to resolve requests.
std::unique_ptr<DnsClient> dns_client_;
SystemDnsConfigChangeNotifier* system_dns_config_notifier_;
// False if IPv6 should not be attempted and assumed unreachable when on a
// WiFi connection. See for further context.
bool check_ipv6_on_wifi_;
base::TimeTicks last_ipv6_probe_time_;
bool last_ipv6_probe_result_;
// Any resolver flags that should be added to a request by default.
HostResolverFlags additional_resolver_flags_;
// Allow fallback to ProcTask if DnsTask fails.
bool allow_fallback_to_proctask_;
// Task runner used for DNS lookups using the system resolver. Normally a
// ThreadPool task runner, but can be overridden for tests.
scoped_refptr<base::TaskRunner> proc_task_runner_;
// Shared tick clock, overridden for testing.
const base::TickClock* tick_clock_;
// For per-context cache invalidation notifications.
true /* check_empty */,
false /* allow_reentrancy */>
bool invalidation_in_progress_;
base::WeakPtrFactory<HostResolverManager> weak_ptr_factory_{this};
base::WeakPtrFactory<HostResolverManager> probe_weak_ptr_factory_{this};
// Resolves a local hostname (such as "localhost" or "localhost6") into
// IP endpoints (with port 0). Returns true if |host| is a local
// hostname and false otherwise. Special IPv6 names (e.g. "localhost6")
// will resolve to an IPv6 address only, whereas other names will
// resolve to both IPv4 and IPv6.
// This function is only exposed so it can be unit-tested.
// TODO(tfarina): It would be better to change the tests so this function
// gets exercised indirectly through HostResolverManager.
NET_EXPORT_PRIVATE bool ResolveLocalHostname(base::StringPiece host,
AddressList* address_list);
} // namespace net