blob: 798a7e578e00855dda2b206b59cf1221badc50dd [file] [log] [blame]
// Copyright (c) 2011 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 <list>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <vector>
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/synchronization/lock.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/thread_checker.h"
#include "net/base/completion_once_callback.h"
#include "net/dns/host_resolver.h"
#include "net/dns/host_resolver_proc.h"
#include "net/dns/host_resolver_source.h"
#include "net/dns/public/dns_query_type.h"
namespace base {
class TickClock;
} // namespace base
namespace net {
class HostCache;
class HostPortPair;
class IPEndPoint;
class RuleBasedHostResolverProc;
// Fills |*addrlist| with a socket address for |host_list| which should be a
// comma-separated list of IPv4 or IPv6 literal(s) without enclosing brackets.
// If |canonical_name| is non-empty it is used as the DNS canonical name for
// the host. Returns OK on success, ERR_UNEXPECTED otherwise.
int ParseAddressList(const std::string& host_list,
const std::string& canonical_name,
AddressList* addrlist);
// In most cases, it is important that unit tests avoid relying on making actual
// DNS queries since the resulting tests can be flaky, especially if the network
// is unreliable for some reason. To simplify writing tests that avoid making
// actual DNS queries, pass a MockHostResolver as the HostResolver dependency.
// The socket addresses returned can be configured using the
// RuleBasedHostResolverProc:
// host_resolver->rules()->AddRule("", "");
// host_resolver->rules()->AddRule("", "");
// The above rules define a static mapping from hostnames to IP address
// literals. The first parameter to AddRule specifies a host pattern to match
// against, and the second parameter indicates what value should be used to
// replace the given hostname. So, the following is also supported:
// host_mapper->AddRule("*.com", "");
// Replacement doesn't have to be string representing an IP address. It can
// re-map one hostname to another as well.
// By default, MockHostResolvers include a single rule that maps all hosts to
// Separate rules are used for separate HostResolverSource (eg
// HostResolverSource::SYSTEM for requests that should only be resolved using
// the system resolver). Use rules_map() to access the separate rules if tests
// involve requests specifying sources:
// host_resolver->rules_map()[HostResolverSource::DNS]->AddRule("",
// "");
// Base class shared by MockHostResolver and MockCachingHostResolver.
class MockHostResolverBase
: public HostResolver,
public base::SupportsWeakPtr<MockHostResolverBase> {
class RequestImpl;
class MdnsListenerImpl;
~MockHostResolverBase() override;
RuleBasedHostResolverProc* rules() {
return rules_map_[HostResolverSource::ANY].get();
void set_rules(RuleBasedHostResolverProc* rules) {
rules_map_[HostResolverSource::ANY] = rules;
std::map<HostResolverSource, scoped_refptr<RuleBasedHostResolverProc>>
rules_map() {
return rules_map_;
// Controls whether resolutions complete synchronously or asynchronously.
void set_synchronous_mode(bool is_synchronous) {
synchronous_mode_ = is_synchronous;
// Asynchronous requests are automatically resolved by default.
// If set_ondemand_mode() is set then Resolve() returns IO_PENDING and
// ResolveAllPending() must be explicitly invoked to resolve all requests
// that are pending.
void set_ondemand_mode(bool is_ondemand) {
ondemand_mode_ = is_ondemand;
// HostResolver methods:
std::unique_ptr<ResolveHostRequest> CreateRequest(
const HostPortPair& host,
const NetLogWithSource& net_log,
const base::Optional<ResolveHostParameters>& optional_parameters)
std::unique_ptr<MdnsListener> CreateMdnsListener(
const HostPortPair& host,
DnsQueryType query_type) override;
HostCache* GetHostCache() override;
bool HasCached(base::StringPiece hostname,
HostCache::Entry::Source* source_out,
HostCache::EntryStaleness* stale_out,
bool* secure_out) const override;
void SetDnsConfigOverrides(const DnsConfigOverrides& overrides) override {}
// Preloads the cache with what would currently be the result of a request
// with the given parameters. Returns the net error of the cached result.
int LoadIntoCache(
const HostPortPair& host,
const base::Optional<ResolveHostParameters>& optional_parameters);
// Returns true if there are pending requests that can be resolved by invoking
// ResolveAllPending().
bool has_pending_requests() const { return !requests_.empty(); }
// Resolves all pending requests. It is only valid to invoke this if
// set_ondemand_mode was set before. The requests are resolved asynchronously,
// after this call returns.
void ResolveAllPending();
// Each request is assigned an ID when started and stored with the resolver
// for async resolution, starting with 1. IDs are not reused. Once a request
// completes, it is destroyed, and can no longer be accessed.
// Returns the ID of the most recently started still-active request. Zero if
// no requests are currently active.
size_t last_id();
// Resolve request stored in |requests_|. Pass rv to callback.
void ResolveNow(size_t id);
// Detach cancelled request.
void DetachRequest(size_t id);
// Returns the request with the given id.
RequestImpl* request(size_t id);
// Returns the priority of the request with the given id.
RequestPriority request_priority(size_t id);
// Like ResolveNow, but doesn't take an ID. DCHECKs if there's more than one
// pending request.
void ResolveOnlyRequestNow();
// The number of times that Resolve() has been called.
size_t num_resolve() const {
return num_resolve_;
// The number of times that ResolveFromCache() has been called.
size_t num_resolve_from_cache() const {
return num_resolve_from_cache_;
// The number of times resolve was attempted non-locally.
size_t num_non_local_resolves() const { return num_non_local_resolves_; }
// Returns the RequestPriority of the last call to Resolve() (or
// DEFAULT_PRIORITY if Resolve() hasn't been called yet).
RequestPriority last_request_priority() const {
return last_request_priority_;
void TriggerMdnsListeners(const HostPortPair& host,
DnsQueryType query_type,
MdnsListener::Delegate::UpdateType update_type,
const IPEndPoint& address_result);
void TriggerMdnsListeners(const HostPortPair& host,
DnsQueryType query_type,
MdnsListener::Delegate::UpdateType update_type,
const std::vector<std::string>& text_result);
void TriggerMdnsListeners(const HostPortPair& host,
DnsQueryType query_type,
MdnsListener::Delegate::UpdateType update_type,
const HostPortPair& host_result);
void TriggerMdnsListeners(const HostPortPair& host,
DnsQueryType query_type,
MdnsListener::Delegate::UpdateType update_type);
void set_tick_clock(const base::TickClock* tick_clock) {
tick_clock_ = tick_clock;
friend class MockHostResolver;
friend class MockCachingHostResolver;
typedef std::map<size_t, RequestImpl*> RequestMap;
// If > 0, |cache_invalidation_num| is the number of times a cached entry can
// be read before it invalidates itself. Useful to force cache expiration
// scenarios.
explicit MockHostResolverBase(bool use_caching, int cache_invalidation_num);
// Handle resolution for |request|. Expected to be called only the RequestImpl
// object itself.
int Resolve(RequestImpl* request);
// Resolve as IP or from |cache_| return cached error or
// DNS_CACHE_MISS if failed.
int ResolveFromIPLiteralOrCache(
const HostPortPair& host,
DnsQueryType dns_query_type,
HostResolverFlags flags,
HostResolverSource source,
HostResolver::ResolveHostParameters::CacheUsage cache_usage,
AddressList* addresses,
base::Optional<HostCache::EntryStaleness>* stale_info);
// Resolve via |proc_|.
int ResolveProc(const HostPortPair& host,
AddressFamily requested_address_family,
HostResolverFlags flags,
HostResolverSource source,
AddressList* addresses);
void AddListener(MdnsListenerImpl* listener);
void RemoveCancelledListener(MdnsListenerImpl* listener);
RequestPriority last_request_priority_;
bool synchronous_mode_;
bool ondemand_mode_;
std::map<HostResolverSource, scoped_refptr<RuleBasedHostResolverProc>>
std::unique_ptr<HostCache> cache_;
const int initial_cache_invalidation_num_;
std::map<HostCache::Key, int> cache_invalidation_nums_;
// Maintain non-owning pointers to outstanding requests and listeners to allow
// completing/notifying them. The objects are owned by callers, and should be
// removed from |this| on destruction by calling DetachRequest() or
// RemoveCancelledListener().
RequestMap requests_;
size_t next_request_id_;
std::set<MdnsListenerImpl*> listeners_;
size_t num_resolve_;
size_t num_resolve_from_cache_;
size_t num_non_local_resolves_;
const base::TickClock* tick_clock_;
class MockHostResolver : public MockHostResolverBase {
: MockHostResolverBase(false /*use_caching*/,
0 /* cache_invalidation_num */) {}
~MockHostResolver() override {}
// Same as MockHostResolver, except internally it uses a host-cache.
// Note that tests are advised to use MockHostResolver instead, since it is
// more predictable. (MockHostResolver also can be put into synchronous
// operation mode in case that is what you needed from the caching version).
class MockCachingHostResolver : public MockHostResolverBase {
// If > 0, |cache_invalidation_num| is the number of times a cached entry can
// be read before it invalidates itself. Useful to force cache expiration
// scenarios.
explicit MockCachingHostResolver(int cache_invalidation_num = 0)
: MockHostResolverBase(true /*use_caching*/, cache_invalidation_num) {}
~MockCachingHostResolver() override {}
// RuleBasedHostResolverProc applies a set of rules to map a host string to
// a replacement host string. It then uses the system host resolver to return
// a socket address. Generally the replacement should be an IPv4 literal so
// there is no network dependency.
// RuleBasedHostResolverProc is thread-safe, to a limited degree. Rules can be
// added or removed on any thread.
class RuleBasedHostResolverProc : public HostResolverProc {
explicit RuleBasedHostResolverProc(HostResolverProc* previous);
// Any hostname matching the given pattern will be replaced with the given
// |ip_literal|.
void AddRule(const std::string& host_pattern, const std::string& ip_literal);
// Same as AddRule(), but further restricts to |address_family|.
void AddRuleForAddressFamily(const std::string& host_pattern,
AddressFamily address_family,
const std::string& ip_literal);
void AddRuleWithFlags(const std::string& host_pattern,
const std::string& ip_literal,
HostResolverFlags flags,
const std::string& canonical_name = "");
// Same as AddRule(), but the replacement is expected to be an IPv4 or IPv6
// literal. This can be used in place of AddRule() to bypass the system's
// host resolver (the address list will be constructed manually).
// If |canonical_name| is non-empty, it is copied to the resulting AddressList
// but does not impact DNS resolution.
// |ip_literal| can be a single IP address like "" or a comma
// separated list of IP addresses, like "::1,192:168.1.2".
void AddIPLiteralRule(const std::string& host_pattern,
const std::string& ip_literal,
const std::string& canonical_name);
void AddRuleWithLatency(const std::string& host_pattern,
const std::string& replacement,
int latency_ms);
// Make sure that |host| will not be re-mapped or even processed by underlying
// host resolver procedures. It can also be a pattern.
void AllowDirectLookup(const std::string& host);
// Simulate a lookup failure for |host| (it also can be a pattern).
void AddSimulatedFailure(const std::string& host);
// Deletes all the rules that have been added.
void ClearRules();
// Causes method calls that add or delete rules to assert.
// TODO(jam): once this class isn't used by tests that use an out of process
// network service, remove this method and make Rule private.
void DisableModifications();
// HostResolverProc methods:
int Resolve(const std::string& host,
AddressFamily address_family,
HostResolverFlags host_resolver_flags,
AddressList* addrlist,
int* os_error) override;
struct Rule {
enum ResolverType {
// TODO(mmenke): Is it really reasonable for a "mock" host resolver to
// fall back to the system resolver?
Rule(ResolverType resolver_type,
const std::string& host_pattern,
AddressFamily address_family,
HostResolverFlags host_resolver_flags,
const std::string& replacement,
const std::string& canonical_name,
int latency_ms);
Rule(const Rule& other);
ResolverType resolver_type;
std::string host_pattern;
AddressFamily address_family;
HostResolverFlags host_resolver_flags;
std::string replacement;
std::string canonical_name;
int latency_ms; // In milliseconds.
typedef std::list<Rule> RuleList;
RuleList GetRules();
~RuleBasedHostResolverProc() override;
void AddRuleInternal(const Rule& rule);
RuleList rules_;
// Must be obtained before writing to or reading from |rules_|.
base::Lock rule_lock_;
// Whether changes are allowed.
bool modifications_allowed_;
// Create rules that map all requests to localhost.
RuleBasedHostResolverProc* CreateCatchAllHostResolverProc();
// HangingHostResolver never completes its |Resolve| request. As LOCAL_ONLY
// requests are not allowed to complete asynchronously, they will always result
class HangingHostResolver : public HostResolver {
~HangingHostResolver() override;
std::unique_ptr<ResolveHostRequest> CreateRequest(
const HostPortPair& host,
const NetLogWithSource& net_log,
const base::Optional<ResolveHostParameters>& optional_parameters)
bool HasCached(base::StringPiece hostname,
HostCache::Entry::Source* source_out,
HostCache::EntryStaleness* stale_out,
bool* secure_out) const override;
// Use to detect cancellations since there's otherwise no externally-visible
// differentiation between a cancelled and a hung task.
int num_cancellations() const { return num_cancellations_; }
class RequestImpl;
int num_cancellations_ = 0;
base::WeakPtrFactory<HangingHostResolver> weak_ptr_factory_{this};
// This class sets the default HostResolverProc for a particular scope. The
// chain of resolver procs starting at |proc| is placed in front of any existing
// default resolver proc(s). This means that if multiple
// ScopedDefaultHostResolverProcs are declared, then resolving will start with
// the procs given to the last-allocated one, then fall back to the procs given
// to the previously-allocated one, and so forth.
// NOTE: Only use this as a catch-all safety net. Individual tests should use
// MockHostResolver.
class ScopedDefaultHostResolverProc {
explicit ScopedDefaultHostResolverProc(HostResolverProc* proc);
void Init(HostResolverProc* proc);
scoped_refptr<HostResolverProc> current_proc_;
scoped_refptr<HostResolverProc> previous_proc_;
} // namespace net