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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 <limits.h>
#include <stdint.h>
#include <algorithm>
#include <string>
#include "absl/base/attributes.h"
#include "absl/strings/string_view.h"
#include "rtc_base/checks.h"
#include "rtc_base/network_constants.h"
#include "rtc_base/socket_address.h"
#include "rtc_base/system/rtc_export.h"
namespace webrtc {
enum class IceCandidateType : int { kHost, kSrflx, kPrflx, kRelay };
RTC_EXPORT absl::string_view IceCandidateTypeToString(IceCandidateType);
} // namespace webrtc
namespace cricket {
// TODO(tommi): These are temporarily here, moved from `port.h` and will
// eventually be removed once we use enums instead of strings for these values.
RTC_EXPORT extern const absl::string_view LOCAL_PORT_TYPE;
RTC_EXPORT extern const absl::string_view STUN_PORT_TYPE;
RTC_EXPORT extern const absl::string_view PRFLX_PORT_TYPE;
RTC_EXPORT extern const absl::string_view RELAY_PORT_TYPE;
// TURN servers are limited to 32 in accordance with
static constexpr size_t kMaxTurnServers = 32;
// Candidate for ICE based connection discovery.
class RTC_EXPORT Candidate {
Candidate(int component,
absl::string_view protocol,
const rtc::SocketAddress& address,
uint32_t priority,
absl::string_view username,
absl::string_view password,
webrtc::IceCandidateType type,
uint32_t generation,
absl::string_view foundation,
uint16_t network_id = 0,
uint16_t network_cost = 0);
// TODO(tommi): Deprecate.
Candidate(int component,
absl::string_view protocol,
const rtc::SocketAddress& address,
uint32_t priority,
absl::string_view username,
absl::string_view password,
absl::string_view type ABSL_ATTRIBUTE_LIFETIME_BOUND,
uint32_t generation,
absl::string_view foundation,
uint16_t network_id = 0,
uint16_t network_cost = 0);
Candidate(const Candidate&);
// 8 character long randomized ID string for logging purposes.
const std::string& id() const { return id_; }
// Generates a new, 8 character long, id.
void generate_id();
// TODO(tommi): Callers should use generate_id(). Remove.
[[deprecated]] void set_id(absl::string_view id) { Assign(id_, id); }
int component() const { return component_; }
void set_component(int component) { component_ = component; }
const std::string& protocol() const { return protocol_; }
// Valid protocol values are:
void set_protocol(absl::string_view protocol) { Assign(protocol_, protocol); }
// The protocol used to talk to relay.
const std::string& relay_protocol() const { return relay_protocol_; }
// Valid protocol values are:
void set_relay_protocol(absl::string_view protocol) {
Assign(relay_protocol_, protocol);
const rtc::SocketAddress& address() const { return address_; }
void set_address(const rtc::SocketAddress& address) { address_ = address; }
uint32_t priority() const { return priority_; }
void set_priority(const uint32_t priority) { priority_ = priority; }
// TODO(honghaiz): Change to usernameFragment or ufrag.
const std::string& username() const { return username_; }
void set_username(absl::string_view username) { Assign(username_, username); }
const std::string& password() const { return password_; }
void set_password(absl::string_view password) { Assign(password_, password); }
webrtc::IceCandidateType type() const { return type_; }
// Returns the name of the candidate type as specified in
absl::string_view type_name() const;
// Setting the type requires a constant string (e.g.
// cricket::LOCAL_PORT_TYPE). The type should really be an enum rather than a
// string, but until we make that change the lifetime attribute helps us lock
// things down. See also the `Port` class.
void set_type(webrtc::IceCandidateType type) { type_ = type; }
// TODO(tommi): Deprecate.
void set_type(absl::string_view type ABSL_ATTRIBUTE_LIFETIME_BOUND);
// Simple checkers for checking the candidate type without dependency on the
// IceCandidateType enum. The `is_local()` and `is_stun()` names are legacy
// names and should now more accurately be `is_host()` and `is_srflx()`.
bool is_local() const;
bool is_stun() const;
bool is_prflx() const;
bool is_relay() const;
// Returns the type preference, a value between 0-126 inclusive, with 0 being
// the lowest preference value, as described in RFC 5245.
int type_preference() const {
// From :
// It is RECOMMENDED that default candidates be chosen based on the
// likelihood of those candidates to work with the peer that is being
// contacted.
// I.e. it is recommended that relayed > reflexive > host.
if (is_local())
return 1; // Host.
if (is_stun())
return 2; // Reflexive.
if (is_relay())
return 3; // Relayed.
return 0; // Unknown, lowest preference.
const std::string& network_name() const { return network_name_; }
void set_network_name(absl::string_view network_name) {
Assign(network_name_, network_name);
rtc::AdapterType network_type() const { return network_type_; }
void set_network_type(rtc::AdapterType network_type) {
network_type_ = network_type;
rtc::AdapterType underlying_type_for_vpn() const {
return underlying_type_for_vpn_;
void set_underlying_type_for_vpn(rtc::AdapterType network_type) {
underlying_type_for_vpn_ = network_type;
// Candidates in a new generation replace those in the old generation.
uint32_t generation() const { return generation_; }
void set_generation(uint32_t generation) { generation_ = generation; }
// `network_cost` measures the cost/penalty of using this candidate. A network
// cost of 0 indicates this candidate can be used freely. A value of
// rtc::kNetworkCostMax indicates it should be used only as the last resort.
void set_network_cost(uint16_t network_cost) {
RTC_DCHECK_LE(network_cost, rtc::kNetworkCostMax);
network_cost_ = network_cost;
uint16_t network_cost() const { return network_cost_; }
// An ID assigned to the network hosting the candidate.
uint16_t network_id() const { return network_id_; }
void set_network_id(uint16_t network_id) { network_id_ = network_id; }
// From RFC 5245, section-
// The foundation of the candidate is set to an arbitrary value, different
// from the foundation for all other remote candidates.
// Note: Use ComputeFoundation to populate this value.
const std::string& foundation() const { return foundation_; }
// TODO(tommi): Deprecate in favor of ComputeFoundation.
// For situations where serializing/deserializing a candidate is needed,
// the constructor can be used to inject a value for the foundation.
void set_foundation(absl::string_view foundation) {
Assign(foundation_, foundation);
const rtc::SocketAddress& related_address() const { return related_address_; }
void set_related_address(const rtc::SocketAddress& related_address) {
related_address_ = related_address;
const std::string& tcptype() const { return tcptype_; }
void set_tcptype(absl::string_view tcptype) { Assign(tcptype_, tcptype); }
// The name of the transport channel of this candidate.
// TODO(phoglund): remove.
const std::string& transport_name() const { return transport_name_; }
void set_transport_name(absl::string_view transport_name) {
Assign(transport_name_, transport_name);
// The URL of the ICE server which this candidate is gathered from.
const std::string& url() const { return url_; }
void set_url(absl::string_view url) { Assign(url_, url); }
// Determines whether this candidate is equivalent to the given one.
bool IsEquivalent(const Candidate& c) const;
// Determines whether this candidate can be considered equivalent to the
// given one when looking for a matching candidate to remove.
bool MatchesForRemoval(const Candidate& c) const;
std::string ToString() const { return ToStringInternal(false); }
std::string ToSensitiveString() const { return ToStringInternal(true); }
uint32_t GetPriority(uint32_t type_preference,
int network_adapter_preference,
int relay_preference,
bool adjust_local_preference) const;
bool operator==(const Candidate& o) const;
bool operator!=(const Candidate& o) const;
// Returns a sanitized copy configured by the given booleans. If
// `use_host_address` is true, the returned copy has its IP removed from
// `address()`, which leads `address()` to be a hostname address. If
// `filter_related_address`, the returned copy has its related address reset
// to the wildcard address (i.e. for IPv4 and :: for IPv6). Note that
// setting both booleans to false returns an identical copy to the original
// candidate.
Candidate ToSanitizedCopy(bool use_hostname_address,
bool filter_related_address) const;
// Computes and populates the `foundation()` field.
// Foundation: An arbitrary string that is the same for two candidates
// that have the same type, base IP address, protocol (UDP, TCP,
// etc.), and STUN or TURN server. If any of these are different,
// then the foundation will be different. Two candidate pairs with
// the same foundation pairs are likely to have similar network
// characteristics. Foundations are used in the frozen algorithm.
// A session wide (peerconnection) tie-breaker is applied to the foundation,
// adds additional randomness and must be the same for all candidates.
void ComputeFoundation(const rtc::SocketAddress& base_address,
uint64_t tie_breaker);
// Call to populate the foundation field for a new peer reflexive remote
// candidate. The type of the candidate must be "prflx".
// The foundation of the candidate is set to an arbitrary value, different
// from the foundation for all other remote candidates.
void ComputePrflxFoundation();
// TODO( With C++17, we get a std::string assignment
// operator accepting any object implicitly convertible to std::string_view,
// and then we don't need this workaround.
static void Assign(std::string& s, absl::string_view view);
std::string ToStringInternal(bool sensitive) const;
std::string id_;
int component_;
std::string protocol_;
std::string relay_protocol_;
rtc::SocketAddress address_;
uint32_t priority_;
std::string username_;
std::string password_;
webrtc::IceCandidateType type_ = webrtc::IceCandidateType::kHost;
std::string network_name_;
rtc::AdapterType network_type_;
rtc::AdapterType underlying_type_for_vpn_;
uint32_t generation_;
std::string foundation_;
rtc::SocketAddress related_address_;
std::string tcptype_;
std::string transport_name_;
uint16_t network_id_;
uint16_t network_cost_;
std::string url_;
} // namespace cricket
#endif // API_CANDIDATE_H_