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* Copyright 2004 The WebRTC Project Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
#include <deque>
#include <memory>
#include <string>
#include <vector>
#include "absl/strings/string_view.h"
#include "api/sequence_checker.h"
#include "api/transport/enums.h"
#include "p2p/base/port.h"
#include "p2p/base/port_interface.h"
#include "rtc_base/helpers.h"
#include "rtc_base/proxy_info.h"
#include "rtc_base/ssl_certificate.h"
#include "rtc_base/system/rtc_export.h"
#include "rtc_base/third_party/sigslot/sigslot.h"
#include "rtc_base/thread.h"
namespace webrtc {
class TurnCustomizer;
} // namespace webrtc
namespace cricket {
// PortAllocator is responsible for allocating Port types for a given
// P2PSocket. It also handles port freeing.
// Clients can override this class to control port allocation, including
// what kinds of ports are allocated.
enum {
// Disable local UDP ports. This doesn't impact how we connect to relay
// servers.
// Disable local TCP ports. This doesn't impact how we connect to relay
// servers.
// When specified, we'll only allocate the STUN candidate for the public
// interface as seen by regular http traffic and the HOST candidate associated
// with the default local interface.
// default local candidate mentioned above will not be allocated. Only the
// STUN candidate will be.
// Disallow use of UDP when connecting to a relay server. Since proxy servers
// usually don't handle UDP, using UDP will leak the IP address.
// When multiple networks exist, do not gather candidates on the ones with
// high cost. So if both Wi-Fi and cellular networks exist, gather only on the
// Wi-Fi network. If a network type is "unknown", it has a cost lower than
// cellular but higher than Wi-Fi/Ethernet. So if an unknown network exists,
// cellular networks will not be used to gather candidates and if a Wi-Fi
// network is present, "unknown" networks will not be usd to gather
// candidates. Doing so ensures that even if a cellular network type was not
// detected initially, it would not be used if a Wi-Fi network is present.
// When specified, do not collect IPv6 ICE candidates on Wi-Fi.
// When this flag is set, ports not bound to any specific network interface
// will be used, in addition to normal ports bound to the enumerated
// interfaces. Without this flag, these "any address" ports would only be
// used when network enumeration fails or is disabled. But under certain
// conditions, these ports may succeed where others fail, so they may allow
// the application to work in a wider variety of environments, at the expense
// of having to allocate additional candidates.
// Exclude link-local network interfaces
// from considertaion after adapter enumeration.
// Defines various reasons that have caused ICE regathering.
enum class IceRegatheringReason {
NETWORK_CHANGE, // Network interfaces on the device changed
NETWORK_FAILURE, // Regather only on networks that have failed
OCCASIONAL_REFRESH, // Periodic regather on all networks
const uint32_t kDefaultPortAllocatorFlags = 0;
const uint32_t kDefaultStepDelay = 1000; // 1 sec step delay.
// As per RFC 5245 Appendix B.1, STUN transactions need to be paced at certain
// internal. Less than 20ms is not acceptable. We choose 50ms as our default.
const uint32_t kMinimumStepDelay = 50;
// Turning on IPv6 could make many IPv6 interfaces available for connectivity
// check and delay the call setup time. kDefaultMaxIPv6Networks is the default
// upper limit of IPv6 networks but could be changed by
// set_max_ipv6_networks().
constexpr int kDefaultMaxIPv6Networks = 5;
enum : uint32_t {
CF_NONE = 0x0,
CF_HOST = 0x1,
CF_RELAY = 0x4,
CF_ALL = 0x7,
// TLS certificate policy.
enum class TlsCertPolicy {
// For TLS based protocols, ensure the connection is secure by not
// circumventing certificate validation.
// For TLS based protocols, disregard security completely by skipping
// certificate validation. This is insecure and should never be used unless
// security is irrelevant in that particular context.
// TODO(deadbeef): Rename to TurnCredentials (and username to ufrag).
struct RelayCredentials {
RelayCredentials() {}
RelayCredentials(absl::string_view username, absl::string_view password)
: username(username), password(password) {}
bool operator==(const RelayCredentials& o) const {
return username == o.username && password == o.password;
bool operator!=(const RelayCredentials& o) const { return !(*this == o); }
std::string username;
std::string password;
typedef std::vector<ProtocolAddress> PortList;
// TODO(deadbeef): Rename to TurnServerConfig.
struct RTC_EXPORT RelayServerConfig {
RelayServerConfig(const rtc::SocketAddress& address,
absl::string_view username,
absl::string_view password,
ProtocolType proto);
RelayServerConfig(absl::string_view address,
int port,
absl::string_view username,
absl::string_view password,
ProtocolType proto);
// Legacy constructor where "secure" and PROTO_TCP implies PROTO_TLS.
RelayServerConfig(absl::string_view address,
int port,
absl::string_view username,
absl::string_view password,
ProtocolType proto,
bool secure);
RelayServerConfig(const RelayServerConfig&);
bool operator==(const RelayServerConfig& o) const {
return ports == o.ports && credentials == o.credentials;
bool operator!=(const RelayServerConfig& o) const { return !(*this == o); }
PortList ports;
RelayCredentials credentials;
TlsCertPolicy tls_cert_policy = TlsCertPolicy::TLS_CERT_POLICY_SECURE;
std::vector<std::string> tls_alpn_protocols;
std::vector<std::string> tls_elliptic_curves;
rtc::SSLCertificateVerifier* tls_cert_verifier = nullptr;
std::string turn_logging_id;
class RTC_EXPORT PortAllocatorSession : public sigslot::has_slots<> {
// Content name passed in mostly for logging and debugging.
PortAllocatorSession(absl::string_view content_name,
int component,
absl::string_view ice_ufrag,
absl::string_view ice_pwd,
uint32_t flags);
// Subclasses should clean up any ports created.
~PortAllocatorSession() override;
uint32_t flags() const { return flags_; }
void set_flags(uint32_t flags) { flags_ = flags; }
std::string content_name() const { return content_name_; }
int component() const { return component_; }
const std::string& ice_ufrag() const { return ice_ufrag_; }
const std::string& ice_pwd() const { return ice_pwd_; }
bool pooled() const { return pooled_; }
// TODO( move this to the constructor
void set_ice_tiebreaker(uint64_t tiebreaker) { tiebreaker_ = tiebreaker; }
uint64_t ice_tiebreaker() const { return tiebreaker_; }
// Setting this filter should affect not only candidates gathered in the
// future, but candidates already gathered and ports already "ready",
// which would be returned by ReadyCandidates() and ReadyPorts().
// Default filter should be CF_ALL.
virtual void SetCandidateFilter(uint32_t filter) = 0;
// Starts gathering ports and ICE candidates.
virtual void StartGettingPorts() = 0;
// Completely stops gathering. Will not gather again unless StartGettingPorts
// is called again.
virtual void StopGettingPorts() = 0;
// Whether the session is actively getting ports.
virtual bool IsGettingPorts() = 0;
// NOTE: The group of methods below is only used for continual gathering.
// ClearGettingPorts should have the same immediate effect as
// StopGettingPorts, but if the implementation supports continual gathering,
// ClearGettingPorts allows additional ports/candidates to be gathered if the
// network conditions change.
virtual void ClearGettingPorts() = 0;
// Whether it is in the state where the existing gathering process is stopped,
// but new ones may be started (basically after calling ClearGettingPorts).
virtual bool IsCleared() const;
// Whether the session has completely stopped.
virtual bool IsStopped() const;
// Re-gathers candidates on networks that do not have any connections. More
// precisely, a network interface may have more than one IP addresses (e.g.,
// IPv4 and IPv6 addresses). Each address subnet will be used to create a
// network. Only if all networks of an interface have no connection, the
// implementation should start re-gathering on all networks of that interface.
virtual void RegatherOnFailedNetworks() {}
// Get candidate-level stats from all candidates on the ready ports and return
// the stats to the given list.
virtual void GetCandidateStatsFromReadyPorts(
CandidateStatsList* candidate_stats_list) const {}
// Set the interval at which STUN candidates will resend STUN binding requests
// on the underlying ports to keep NAT bindings open.
// The default value of the interval in implementation is restored if a null
// optional value is passed.
virtual void SetStunKeepaliveIntervalForReadyPorts(
const absl::optional<int>& stun_keepalive_interval) {}
// Another way of getting the information provided by the signals below.
// Ports and candidates are not guaranteed to be in the same order as the
// signals were emitted in.
virtual std::vector<PortInterface*> ReadyPorts() const = 0;
virtual std::vector<Candidate> ReadyCandidates() const = 0;
virtual bool CandidatesAllocationDone() const = 0;
// Marks all ports in the current session as "pruned" so that they may be
// destroyed if no connection is using them.
virtual void PruneAllPorts() {}
sigslot::signal2<PortAllocatorSession*, PortInterface*> SignalPortReady;
// Fires this signal when the network of the ports failed (either because the
// interface is down, or because there is no connection on the interface),
// or when TURN ports are pruned because a higher-priority TURN port becomes
// ready(pairable).
sigslot::signal2<PortAllocatorSession*, const std::vector<PortInterface*>&>
sigslot::signal2<PortAllocatorSession*, const std::vector<Candidate>&>
sigslot::signal2<PortAllocatorSession*, const IceCandidateErrorEvent&>
// Candidates should be signaled to be removed when the port that generated
// the candidates is removed.
sigslot::signal2<PortAllocatorSession*, const std::vector<Candidate>&>
sigslot::signal1<PortAllocatorSession*> SignalCandidatesAllocationDone;
sigslot::signal2<PortAllocatorSession*, IceRegatheringReason>
virtual uint32_t generation();
virtual void set_generation(uint32_t generation);
// This method is called when a pooled session (which doesn't have these
// properties initially) is returned by PortAllocator::TakePooledSession,
// and the content name, component, and ICE ufrag/pwd are updated.
// A subclass may need to override this method to perform additional actions,
// such as applying the updated information to ports and candidates.
virtual void UpdateIceParametersInternal() {}
// TODO(deadbeef): Get rid of these when everyone switches to ice_ufrag and
// ice_pwd.
const std::string& username() const { return ice_ufrag_; }
const std::string& password() const { return ice_pwd_; }
void SetIceParameters(absl::string_view content_name,
int component,
absl::string_view ice_ufrag,
absl::string_view ice_pwd) {
content_name_ = std::string(content_name);
component_ = component;
ice_ufrag_ = std::string(ice_ufrag);
ice_pwd_ = std::string(ice_pwd);
void set_pooled(bool value) { pooled_ = value; }
uint32_t flags_;
uint32_t generation_;
std::string content_name_;
int component_;
std::string ice_ufrag_;
std::string ice_pwd_;
bool pooled_ = false;
// TODO( move this to the constructor
uint64_t tiebreaker_;
// SetIceParameters is an implementation detail which only PortAllocator
// should be able to call.
friend class PortAllocator;
// Every method of PortAllocator (including the destructor) must be called on
// the same thread after Initialize is called.
// This allows a PortAllocator subclass to be constructed and configured on one
// thread, and passed into an object that uses it on a different thread.
class RTC_EXPORT PortAllocator : public sigslot::has_slots<> {
~PortAllocator() override;
// This MUST be called on the PortAllocator's thread after finishing
// constructing and configuring the PortAllocator subclasses.
virtual void Initialize();
// Set to true if some Ports need to know the ICE credentials when they are
// created. This will ensure that the PortAllocator will only match pooled
// allocator sessions to the ICE transport with the same credentials.
virtual void set_restrict_ice_credentials_change(bool value);
// Set STUN and TURN servers to be used in future sessions, and set
// candidate pool size, as described in JSEP.
// If the servers are changing, and the candidate pool size is nonzero, and
// FreezeCandidatePool hasn't been called, existing pooled sessions will be
// destroyed and new ones created.
// If the servers are not changing but the candidate pool size is, and
// FreezeCandidatePool hasn't been called, pooled sessions will be either
// created or destroyed as necessary.
// Returns true if the configuration could successfully be changed.
// Deprecated
bool SetConfiguration(const ServerAddresses& stun_servers,
const std::vector<RelayServerConfig>& turn_servers,
int candidate_pool_size,
bool prune_turn_ports,
webrtc::TurnCustomizer* turn_customizer = nullptr,
const absl::optional<int>&
stun_candidate_keepalive_interval = absl::nullopt);
bool SetConfiguration(const ServerAddresses& stun_servers,
const std::vector<RelayServerConfig>& turn_servers,
int candidate_pool_size,
webrtc::PortPrunePolicy turn_port_prune_policy,
webrtc::TurnCustomizer* turn_customizer = nullptr,
const absl::optional<int>&
stun_candidate_keepalive_interval = absl::nullopt);
void SetIceTiebreaker(uint64_t tiebreaker);
uint64_t IceTiebreaker() const { return tiebreaker_; }
const ServerAddresses& stun_servers() const {
return stun_servers_;
const std::vector<RelayServerConfig>& turn_servers() const {
return turn_servers_;
int candidate_pool_size() const {
return candidate_pool_size_;
const absl::optional<int>& stun_candidate_keepalive_interval() const {
return stun_candidate_keepalive_interval_;
// Sets the network types to ignore.
// Values are defined by the AdapterType enum.
// For instance, calling this with
// loopback interfaces.
virtual void SetNetworkIgnoreMask(int network_ignore_mask) = 0;
// Set whether VPN connections should be preferred, avoided, mandated or
// blocked.
virtual void SetVpnPreference(webrtc::VpnPreference preference) {
vpn_preference_ = preference;
// Set list of <ipaddress, mask> that shall be categorized as VPN.
// Implemented by BasicPortAllocator.
virtual void SetVpnList(const std::vector<rtc::NetworkMask>& vpn_list) {}
std::unique_ptr<PortAllocatorSession> CreateSession(
absl::string_view content_name,
int component,
absl::string_view ice_ufrag,
absl::string_view ice_pwd);
// Get an available pooled session and set the transport information on it.
// Caller takes ownership of the returned session.
// If restrict_ice_credentials_change is TRUE, then it will only
// return a pooled session with matching ice credentials.
// If no pooled sessions are available, returns null.
std::unique_ptr<PortAllocatorSession> TakePooledSession(
absl::string_view content_name,
int component,
absl::string_view ice_ufrag,
absl::string_view ice_pwd);
// Returns the next session that would be returned by TakePooledSession
// optionally restricting it to sessions with specified ice credentials.
const PortAllocatorSession* GetPooledSession(
const IceParameters* ice_credentials = nullptr) const;
// Discard any remaining pooled sessions.
void DiscardCandidatePool();
// Clears the address and the related address fields of a local candidate to
// avoid IP leakage. This is applicable in several scenarios:
// 1. Sanitization is configured via the candidate filter.
// 2. Sanitization is configured via the port allocator flags.
// 3. mDNS concealment of private IPs is enabled.
Candidate SanitizeCandidate(const Candidate& c) const;
uint32_t flags() const {
return flags_;
void set_flags(uint32_t flags) {
flags_ = flags;
// These three methods are deprecated. If connections need to go through a
// proxy, the application should create a BasicPortAllocator given a custom
// PacketSocketFactory that creates proxy sockets.
const std::string& user_agent() const {
return agent_;
const rtc::ProxyInfo& proxy() const {
return proxy_;
void set_proxy(absl::string_view agent, const rtc::ProxyInfo& proxy) {
agent_ = std::string(agent);
proxy_ = proxy;
// Gets/Sets the port range to use when choosing client ports.
int min_port() const {
return min_port_;
int max_port() const {
return max_port_;
bool SetPortRange(int min_port, int max_port) {
if (min_port > max_port) {
return false;
min_port_ = min_port;
max_port_ = max_port;
return true;
// Can be used to change the default numer of IPv6 network interfaces used
// (5). Can set to INT_MAX to effectively disable the limit.
// TODO(deadbeef): Applications shouldn't have to arbitrarily limit the
// number of available IPv6 network interfaces just because they could slow
// ICE down. We should work on making our ICE logic smarter (for example,
// prioritizing pinging connections that are most likely to work) so that
// every network interface can be used without impacting ICE's speed.
void set_max_ipv6_networks(int networks) {
max_ipv6_networks_ = networks;
int max_ipv6_networks() {
return max_ipv6_networks_;
// Delay between different candidate gathering phases (UDP, TURN, TCP).
// Defaults to 1 second, but PeerConnection sets it to 50ms.
// TODO(deadbeef): Get rid of this. Its purpose is to avoid sending too many
// STUN transactions at once, but that's already happening if you configure
// multiple STUN servers or have multiple network interfaces. We should
// implement some global pacing logic instead if that's our goal.
uint32_t step_delay() const {
return step_delay_;
void set_step_delay(uint32_t delay) {
step_delay_ = delay;
bool allow_tcp_listen() const {
return allow_tcp_listen_;
void set_allow_tcp_listen(bool allow_tcp_listen) {
allow_tcp_listen_ = allow_tcp_listen;
uint32_t candidate_filter() {
return candidate_filter_;
// The new filter value will be populated to future allocation sessions, when
// they are created via CreateSession, and also pooled sessions when one is
// taken via TakePooledSession.
// A change in the candidate filter also fires a signal
// `SignalCandidateFilterChanged`, so that objects subscribed to this signal
// can, for example, update the candidate filter for sessions created by this
// allocator and already taken by the object.
// Specifically for the session taken by the ICE transport, we currently do
// not support removing candidate pairs formed with local candidates from this
// session that are disabled by the new candidate filter.
void SetCandidateFilter(uint32_t filter);
// Deprecated.
// TODO(qingsi): Remove this after Chromium migrates to the new method.
void set_candidate_filter(uint32_t filter) { SetCandidateFilter(filter); }
// Deprecated (by the next method).
bool prune_turn_ports() const {
return turn_port_prune_policy_ == webrtc::PRUNE_BASED_ON_PRIORITY;
webrtc::PortPrunePolicy turn_port_prune_policy() const {
return turn_port_prune_policy_;
webrtc::TurnCustomizer* turn_customizer() {
return turn_customizer_;
// Collect candidate stats from pooled allocator sessions. This can be used to
// collect candidate stats without creating an offer/answer or setting local
// description. After the local description is set, the ownership of the
// pooled session is taken by P2PTransportChannel, and the
// candidate stats can be collected from P2PTransportChannel::GetStats.
virtual void GetCandidateStatsFromPooledSessions(
CandidateStatsList* candidate_stats_list);
// Return IceParameters of the pooled sessions.
std::vector<IceParameters> GetPooledIceCredentials();
// Fired when `candidate_filter_` changes.
sigslot::signal2<uint32_t /* prev_filter */, uint32_t /* cur_filter */>
// TODO(webrtc::13579): Remove std::string version once downstream users have
// migrated to the absl::string_view version.
virtual PortAllocatorSession* CreateSessionInternal(
absl::string_view content_name,
int component,
absl::string_view ice_ufrag,
absl::string_view ice_pwd) = 0;
const std::vector<std::unique_ptr<PortAllocatorSession>>& pooled_sessions() {
return pooled_sessions_;
// Returns true if there is an mDNS responder attached to the network manager.
virtual bool MdnsObfuscationEnabled() const { return false; }
// The following thread checks are only done in DCHECK for the consistency
// with the exsiting thread checks.
void CheckRunOnValidThreadIfInitialized() const {
RTC_DCHECK(!initialized_ || thread_checker_.IsCurrent());
void CheckRunOnValidThreadAndInitialized() const {
RTC_DCHECK(initialized_ && thread_checker_.IsCurrent());
bool initialized_ = false;
uint32_t flags_;
std::string agent_;
rtc::ProxyInfo proxy_;
int min_port_;
int max_port_;
int max_ipv6_networks_;
uint32_t step_delay_;
bool allow_tcp_listen_;
uint32_t candidate_filter_;
std::string origin_;
webrtc::SequenceChecker thread_checker_;
webrtc::VpnPreference vpn_preference_ = webrtc::VpnPreference::kDefault;
ServerAddresses stun_servers_;
std::vector<RelayServerConfig> turn_servers_;
int candidate_pool_size_ = 0; // Last value passed into SetConfiguration.
std::vector<std::unique_ptr<PortAllocatorSession>> pooled_sessions_;
webrtc::PortPrunePolicy turn_port_prune_policy_ = webrtc::NO_PRUNE;
// Customizer for TURN messages.
// The instance is owned by application and will be shared among
// all TurnPort(s) created.
webrtc::TurnCustomizer* turn_customizer_ = nullptr;
absl::optional<int> stun_candidate_keepalive_interval_;
// If true, TakePooledSession() will only return sessions that has same ice
// credentials as requested.
bool restrict_ice_credentials_change_ = false;
// Returns iterator to pooled session with specified ice_credentials or first
// if ice_credentials is nullptr.
FindPooledSession(const IceParameters* ice_credentials = nullptr) const;
// ICE tie breaker.
uint64_t tiebreaker_;
} // namespace cricket