net/base/features.h

// Copyright (c) 2018 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_BASE_FEATURES_H_
#define NET_BASE_FEATURES_H_

#include <string>

#include "base/feature_list.h"
#include "base/metrics/field_trial_params.h"
#include "base/strings/string_piece.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "net/base/net_export.h"
#include "net/net_buildflags.h"

namespace net {
namespace features {

// Toggles the `Accept-Language` HTTP request header, which
// https://github.com/WICG/lang-client-hint proposes that we deprecate.
NET_EXPORT extern const base::Feature kAcceptLanguageHeader;

// Enables ALPS extension of TLS 1.3 for HTTP/2, see
// https://vasilvv.github.io/tls-alps/draft-vvv-tls-alps.html and
// https://vasilvv.github.io/httpbis-alps/draft-vvv-httpbis-alps.html.
NET_EXPORT extern const base::Feature kAlpsForHttp2;

// Disable H2 reprioritization, in order to measure its impact.
NET_EXPORT extern const base::Feature kAvoidH2Reprioritization;

// When kCapReferrerToOriginOnCrossOrigin is enabled, HTTP referrers on cross-
// origin requests are restricted to contain at most the source origin.
NET_EXPORT extern const base::Feature kCapReferrerToOriginOnCrossOrigin;

// Support for altering the parameters used for DNS transaction timeout. See
// ResolveContext::SecureTransactionTimeout().
NET_EXPORT extern const base::Feature kDnsTransactionDynamicTimeouts;
// Multiplier applied to current fallback periods in determining a transaction
// timeout.
NET_EXPORT extern const base::FeatureParam<double>
    kDnsTransactionTimeoutMultiplier;
NET_EXPORT extern const base::FeatureParam<base::TimeDelta>
    kDnsMinTransactionTimeout;

// Enables DNS query-only experiments for HTTPSSVC or INTEGRITY records,
// depending on feature parameters. Received responses never affect Chrome
// behavior other than metrics.
//
// Not to be confused with `kUseDnsHttpsSvcb` which is querying HTTPS in order
// to affect Chrome connection behavior.
NET_EXPORT extern const base::Feature kDnsHttpssvc;

// Determine which kind of record should be queried: HTTPSSVC or INTEGRITY. No
// more than one of these feature parameters should be enabled at once. In the
// event that both are enabled, |kDnsHttpssvcUseIntegrity| takes priority, and
// |kDnsHttpssvcUseHttpssvc| will be ignored.
NET_EXPORT extern const base::FeatureParam<bool> kDnsHttpssvcUseHttpssvc;
NET_EXPORT extern const base::FeatureParam<bool> kDnsHttpssvcUseIntegrity;

// Enable HTTPSSVC or INTEGRITY to be queried over insecure DNS.
NET_EXPORT extern const base::FeatureParam<bool>
    kDnsHttpssvcEnableQueryOverInsecure;

// If we are still waiting for an HTTPSSVC or INTEGRITY query after all the
// other queries in a DnsTask have completed, we will compute a timeout for the
// remaining query. The timeout will be the min of:
//   (a) |kDnsHttpssvcExtraTimeMs.Get()|
//   (b) |kDnsHttpssvcExtraTimePercent.Get() / 100 * t|, where |t| is the
//       number of milliseconds since the first query began.
NET_EXPORT extern const base::FeatureParam<int> kDnsHttpssvcExtraTimeMs;
NET_EXPORT extern const base::FeatureParam<int> kDnsHttpssvcExtraTimePercent;

// These parameters, respectively, are the list of experimental and control
// domains for which we will query HTTPSSVC or INTEGRITY records. We expect
// valid INTEGRITY results for experiment domains. We expect no INTEGRITY
// results for control domains.
//
// The format of both parameters is a comma-separated list of domains.
// Whitespace around domain names is permitted. Trailing comma is optional.
//
// See helper functions:
// |dns_httpssvc_experiment::GetDnsHttpssvcExperimentDomains| and
// |dns_httpssvc_experiment::GetDnsHttpssvcControlDomains|.
NET_EXPORT extern const base::FeatureParam<std::string>
    kDnsHttpssvcExperimentDomains;
NET_EXPORT extern const base::FeatureParam<std::string>
    kDnsHttpssvcControlDomains;

// This param controls how we determine whether a domain is an experimental or
// control domain. When false, domains must be in |kDnsHttpssvcControlDomains|
// to be considered a control. When true, we ignore |kDnsHttpssvcControlDomains|
// and any non-experiment domain (not in |kDnsHttpssvcExperimentDomains|) is
// considered a control domain.
NET_EXPORT extern const base::FeatureParam<bool>
    kDnsHttpssvcControlDomainWildcard;

namespace dns_httpssvc_experiment {
// Get the value of |kDnsHttpssvcExtraTimeMs|.
NET_EXPORT base::TimeDelta GetExtraTimeAbsolute();
}  // namespace dns_httpssvc_experiment

// Enables querying HTTPS DNS records that will affect results from HostResolver
// and may be used to affect connection behavior. Whether or not those results
// are used (e.g. to connect via ECH) may be controlled by separate features.
//
// Not to be confused with `kDnsHttpssvc` which is for experiment-only queries
// where received HTTPS results do not affect Chrome behavior and are only used
// for metrics.
NET_EXPORT extern const base::Feature kUseDnsHttpsSvcb;

// Param to control whether or not presence of an HTTPS record for an HTTP
// request will force an HTTP->HTTPS upgrade redirect.
NET_EXPORT extern const base::FeatureParam<bool> kUseDnsHttpsSvcbHttpUpgrade;

// Param to control whether or not HostResolver, when using Secure DNS, will
// fail the entire connection attempt when receiving an inconclusive response to
// an HTTPS query (anything except transport error, timeout, or SERVFAIL). Used
// to prevent certain downgrade attacks against ECH behavior.
NET_EXPORT extern const base::FeatureParam<bool>
    kUseDnsHttpsSvcbEnforceSecureResponse;

// Param to control whether HTTPS queries will be allowed via Insecure DNS
// (instead of just via Secure DNS).
NET_EXPORT extern const base::FeatureParam<bool> kUseDnsHttpsSvcbEnableInsecure;

// If we are still waiting for an HTTPS transaction after all the
// other transactions in a DnsTask have completed, we will compute a timeout for
// the remaining transaction. The timeout will be the min of:
//   (a) `kUseDnsHttpsSvcbExtraTimeAbsolute.Get()`
//   (b) `kUseDnsHttpsSvcbExtraTimePercent.Get() / 100 * t`, where `t` is
//   the
//       time delta since the first query began.
//
// Either param is ignored if zero. If both are zero, there is no timeout
// specific to HTTPS transactions, only the regular DNS query timeout and server
// fallback.
//
// If `kUseDnsHttpsSvcbEnforceSecureResponse` is enabled, the timeouts will not
// be used for secure requests because there is no sense killing a transaction
// early if that will just kill the entire request.
NET_EXPORT extern const base::FeatureParam<base::TimeDelta>
    kUseDnsHttpsSvcbExtraTimeAbsolute;
NET_EXPORT extern const base::FeatureParam<int>
    kUseDnsHttpsSvcbExtraTimePercent;

// Enables TLS 1.3 early data.
NET_EXPORT extern const base::Feature kEnableTLS13EarlyData;

// Enables the TLS Encrypted ClientHello feature.
// https://datatracker.ietf.org/doc/html/draft-ietf-tls-esni-13
//
// TODO(https://crbug.com/1091403): This flag does not currently do much yet.
// ECH is still in development.
NET_EXPORT extern const base::Feature kEncryptedClientHello;

// Enables optimizing the network quality estimation algorithms in network
// quality estimator (NQE).
NET_EXPORT extern const base::Feature kNetworkQualityEstimator;

// Splits cache entries by the request's includeCredentials.
NET_EXPORT extern const base::Feature kSplitCacheByIncludeCredentials;

// Splits cache entries by the request's NetworkIsolationKey if one is
// available.
NET_EXPORT extern const base::Feature kSplitCacheByNetworkIsolationKey;

// Splits host cache entries by the DNS request's NetworkIsolationKey if one is
// available. Also prevents merging live DNS lookups when there is a NIK
// mismatch.
NET_EXPORT extern const base::Feature kSplitHostCacheByNetworkIsolationKey;

// Partitions connections based on the NetworkIsolationKey associated with a
// request.
NET_EXPORT extern const base::Feature
    kPartitionConnectionsByNetworkIsolationKey;

// Partitions HttpServerProperties based on the NetworkIsolationKey associated
// with a request.
NET_EXPORT extern const base::Feature
    kPartitionHttpServerPropertiesByNetworkIsolationKey;

// Partitions TLS sessions and QUIC server configs based on the
// NetworkIsolationKey associated with a request.
//
// This feature requires kPartitionConnectionsByNetworkIsolationKey to be
// enabled to work.
NET_EXPORT extern const base::Feature
    kPartitionSSLSessionsByNetworkIsolationKey;

// Partitions Expect-CT data by NetworkIsolationKey. This only affects the
// Expect-CT data itself. Regardless of this value, reports will be uploaded
// using the associated NetworkIsolationKey, when one's available.
//
// This feature requires kPartitionConnectionsByNetworkIsolationKey,
// kPartitionHttpServerPropertiesByNetworkIsolationKey, and
// kPartitionConnectionsByNetworkIsolationKey to all be enabled to work.
NET_EXPORT extern const base::Feature
    kPartitionExpectCTStateByNetworkIsolationKey;

// Partitions Network Error Logging and Reporting API data by
// NetworkIsolationKey. Also partitions all reports generated by other consumers
// of the reporting API. Applies the NetworkIsolationKey to reports uploads as
// well.
//
// When disabled, the main entry points of the reporting and NEL services ignore
// NetworkIsolationKey parameters, and they're cleared while loading from the
// cache, but internal objects can be created with them (e.g., endpoints), for
// testing.
NET_EXPORT extern const base::Feature
    kPartitionNelAndReportingByNetworkIsolationKey;

// Enables limiting the size of Expect-CT table.
NET_EXPORT extern const base::Feature kExpectCTPruning;

// FeatureParams associated with kExpectCTPruning.

// Expect-CT pruning runs when this many entries are hit.
NET_EXPORT extern const base::FeatureParam<int> kExpectCTPruneMax;
// The Expect-CT pruning logic attempts to reduce entries to at most this many.
NET_EXPORT extern const base::FeatureParam<int> kExpectCTPruneMin;
// Non-transient entries with |enforce| set are safe from being pruned if
// they're less than this many days old, unless the number of entries exceeds
// |kExpectCTMaxEntriesPerNik|.
NET_EXPORT extern const base::FeatureParam<int> kExpectCTSafeFromPruneDays;
// If, after pruning transient, non-enforced, old Expect-CT entries,
// kExpectCTPruneMin is still exceeded, then all NetworkIsolationKeys will be
// capped to this many entries, based on last observation date.
NET_EXPORT extern const base::FeatureParam<int> kExpectCTMaxEntriesPerNik;
// Minimum delay between successive prunings of Expect-CT entries, in seconds.
NET_EXPORT extern const base::FeatureParam<int> kExpectCTPruneDelaySecs;

// Enables sending TLS 1.3 Key Update messages on TLS 1.3 connections in order
// to ensure that this corner of the spec is exercised. This is currently
// disabled by default because we discovered incompatibilities with some
// servers.
NET_EXPORT extern const base::Feature kTLS13KeyUpdate;

// Enables CECPQ2, a post-quantum key-agreement, in TLS 1.3 connections.
NET_EXPORT extern const base::Feature kPostQuantumCECPQ2;

// Enables CECPQ2, a post-quantum key-agreement, in TLS 1.3 connections for a
// subset of domains. (This is intended as Finch kill-switch. For testing
// compatibility with large ClientHello messages, use |kPostQuantumCECPQ2|.)
NET_EXPORT extern const base::Feature kPostQuantumCECPQ2SomeDomains;
NET_EXPORT extern const base::FeatureParam<std::string>
    kPostQuantumCECPQ2Prefix;

// Changes the timeout after which unused sockets idle sockets are cleaned up.
NET_EXPORT extern const base::Feature kNetUnusedIdleSocketTimeout;

// When enabled, the time threshold for Lax-allow-unsafe cookies will be lowered
// from 2 minutes to 10 seconds. This time threshold refers to the age cutoff
// for which cookies that default into SameSite=Lax, which are newer than the
// threshold, will be sent with any top-level cross-site navigation regardless
// of HTTP method (i.e. allowing unsafe methods). This is a convenience for
// integration tests which may want to test behavior of cookies older than the
// threshold, but which would not be practical to run for 2 minutes.
NET_EXPORT extern const base::Feature kShortLaxAllowUnsafeThreshold;

// When enabled, the SameSite by default feature does not add the
// "Lax-allow-unsafe" behavior. Any cookies that do not specify a SameSite
// attribute will be treated as Lax only, i.e. POST and other unsafe HTTP
// methods will not be allowed at all for top-level cross-site navigations.
// This only has an effect if the cookie defaults to SameSite=Lax.
NET_EXPORT extern const base::Feature kSameSiteDefaultChecksMethodRigorously;

#if BUILDFLAG(BUILTIN_CERT_VERIFIER_FEATURE_SUPPORTED)
// When enabled, use the builtin cert verifier instead of the platform verifier.
NET_EXPORT extern const base::Feature kCertVerifierBuiltinFeature;
#if defined(OS_MAC)
NET_EXPORT extern const base::FeatureParam<int> kCertVerifierBuiltinImpl;
NET_EXPORT extern const base::FeatureParam<int> kCertVerifierBuiltinCacheSize;
#endif /* defined(OS_MAC) */
#endif /* BUILDFLAG(BUILTIN_CERT_VERIFIER_FEATURE_SUPPORTED) */

#if BUILDFLAG(TRIAL_COMPARISON_CERT_VERIFIER_SUPPORTED)
NET_EXPORT extern const base::Feature kCertDualVerificationTrialFeature;
#if defined(OS_MAC)
NET_EXPORT extern const base::FeatureParam<int> kCertDualVerificationTrialImpl;
NET_EXPORT extern const base::FeatureParam<int>
    kCertDualVerificationTrialCacheSize;
#endif /* defined(OS_MAC) */
#endif /* BUILDFLAG(TRIAL_COMPARISON_CERT_VERIFIER_SUPPORTED) */

#if BUILDFLAG(CHROME_ROOT_STORE_SUPPORTED)
// When enabled, use the Chrome Root Store instead of the system root store
NET_EXPORT extern const base::Feature kChromeRootStoreUsed;
#endif /* BUILDFLAG(CHROME_ROOT_STORE_SUPPORTED) */

// Turns off streaming media caching to disk when on battery power.
NET_EXPORT extern const base::Feature kTurnOffStreamingMediaCachingOnBattery;

// Turns off streaming media caching to disk always.
NET_EXPORT extern const base::Feature kTurnOffStreamingMediaCachingAlways;

// When enabled this feature will cause same-site calculations to take into
// account the scheme of the site-for-cookies and the request/response url.
NET_EXPORT extern const base::Feature kSchemefulSameSite;

// Enables a process-wide limit on "open" UDP sockets. See
// udp_socket_global_limits.h for details on what constitutes an "open" socket.
NET_EXPORT extern const base::Feature kLimitOpenUDPSockets;

// FeatureParams associated with kLimitOpenUDPSockets.

// Sets the maximum allowed open UDP sockets. Provisioning more sockets than
// this will result in a failure (ERR_INSUFFICIENT_RESOURCES).
NET_EXPORT extern const base::FeatureParam<int> kLimitOpenUDPSocketsMax;

// Enables a timeout on individual TCP connect attempts, based on
// the parameter values.
NET_EXPORT extern const base::Feature kTimeoutTcpConnectAttempt;

// FeatureParams associated with kTimeoutTcpConnectAttempt.

// When there is an estimated RTT available, the experimental TCP connect
// attempt timeout is calculated as:
//
//  clamp(kTimeoutTcpConnectAttemptMin,
//        kTimeoutTcpConnectAttemptMax,
//        <Estimated RTT> * kTimeoutTcpConnectAttemptRTTMultiplier);
//
// Otherwise the TCP connect attempt timeout is set to
// kTimeoutTcpConnectAttemptMax.
NET_EXPORT extern const base::FeatureParam<double>
    kTimeoutTcpConnectAttemptRTTMultiplier;
NET_EXPORT extern const base::FeatureParam<base::TimeDelta>
    kTimeoutTcpConnectAttemptMin;
NET_EXPORT extern const base::FeatureParam<base::TimeDelta>
    kTimeoutTcpConnectAttemptMax;

// Enables usage of First Party Sets to determine cookie availability.
NET_EXPORT extern const base::Feature kFirstPartySets;

// Controls whether the client is considered a dogfooder for the FirstPartySets
// feature.
NET_EXPORT extern const base::FeatureParam<bool> kFirstPartySetsIsDogfooder;

#if BUILDFLAG(ENABLE_REPORTING)
// When enabled this feature will allow a new Reporting-Endpoints header to
// configure reporting endpoints for report delivery. This is used to support
// the new Document Reporting spec.
NET_EXPORT extern const base::Feature kDocumentReporting;
#endif  // BUILDFLAG(ENABLE_REPORTING)

#if defined(OS_POSIX) || defined(OS_FUCHSIA)
// When enabled, UDPSocketPosix increments the global counter of bytes received
// every time bytes are received, instead of using a timer to batch updates.
// This should reduce the number of wake ups and improve battery consumption.
// TODO(https://crbug.com/1189805): Cleanup the feature after verifying that it
// doesn't negatively affect performance.
NET_EXPORT extern const base::Feature kUdpSocketPosixAlwaysUpdateBytesReceived;
#endif  // defined(OS_POSIX) || defined(OS_FUCHSIA)

// When this feature is enabled, redirected requests will be considered
// cross-site for the purpose of SameSite cookies if any redirect hop was
// cross-site to the target URL, even if the original initiator of the
// redirected request was same-site with the target URL (and the
// site-for-cookies).
// See spec changes in https://github.com/httpwg/http-extensions/pull/1348
NET_EXPORT extern const base::Feature kCookieSameSiteConsidersRedirectChain;

// When enabled, cookies with the SameParty attribute are treated as
// "first-party" when in same-party contexts, for the purposes of third-party
// cookie blocking. (Note that as a consequence, some cookies may be blocked
// while others are allowed on a cross-site, same-party request. Additionally,
// privacy mode is disabled in same-party contexts.)
NET_EXPORT extern const base::Feature kSamePartyCookiesConsideredFirstParty;

// When enabled, sites can opt-in to having their cookies partitioned by
// top-level site with the Partitioned attribute. Partitioned cookies will only
// be sent when the browser is on the same top-level site that it was on when
// the cookie was set.
NET_EXPORT extern const base::Feature kPartitionedCookies;

// When enabled, additional cookie-related APIs will perform cookie field size
// and character set validation to enforce stricter conformance with RFC6265bis.
// TODO(crbug.com/1243852) Eventually enable this permanently and remove the
// feature flag, assuming no breakage occurs with it enabled.
NET_EXPORT extern const base::Feature kExtraCookieValidityChecks;

// When enabled, the client will opt in to the V2 component format for the
// First-Party Sets component.
NET_EXPORT extern const base::Feature kFirstPartySetsV2ComponentFormat;

}  // namespace features
}  // namespace net

#endif  // NET_BASE_FEATURES_H_