Repo created

TMessagesProj/jni/voip/webrtc/p2p/base/stun_port.cc

@@ -0,0 +1,673 @@
+/*
+ *  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 "p2p/base/stun_port.h"
+
+#include <utility>
+#include <vector>
+
+#include "absl/memory/memory.h"
+#include "absl/strings/string_view.h"
+#include "api/transport/stun.h"
+#include "p2p/base/connection.h"
+#include "p2p/base/p2p_constants.h"
+#include "p2p/base/port_allocator.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/experiments/field_trial_parser.h"
+#include "rtc_base/helpers.h"
+#include "rtc_base/ip_address.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/network/received_packet.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace cricket {
+
+// TODO(?): Move these to a common place (used in relayport too)
+const int RETRY_TIMEOUT = 50 * 1000;  // 50 seconds
+
+// Stop logging errors in UDPPort::SendTo after we have logged
+// `kSendErrorLogLimit` messages. Start again after a successful send.
+const int kSendErrorLogLimit = 5;
+
+// Handles a binding request sent to the STUN server.
+class StunBindingRequest : public StunRequest {
+ public:
+  StunBindingRequest(UDPPort* port,
+                     const rtc::SocketAddress& addr,
+                     int64_t start_time)
+      : StunRequest(port->request_manager(),
+                    std::make_unique<StunMessage>(STUN_BINDING_REQUEST)),
+        port_(port),
+        server_addr_(addr),
+        start_time_(start_time) {
+    SetAuthenticationRequired(false);
+  }
+
+  const rtc::SocketAddress& server_addr() const { return server_addr_; }
+
+  void OnResponse(StunMessage* response) override {
+    const StunAddressAttribute* addr_attr =
+        response->GetAddress(STUN_ATTR_MAPPED_ADDRESS);
+    if (!addr_attr) {
+      RTC_LOG(LS_ERROR) << "Binding response missing mapped address.";
+    } else if (addr_attr->family() != STUN_ADDRESS_IPV4 &&
+               addr_attr->family() != STUN_ADDRESS_IPV6) {
+      RTC_LOG(LS_ERROR) << "Binding address has bad family";
+    } else {
+      rtc::SocketAddress addr(addr_attr->ipaddr(), addr_attr->port());
+      port_->OnStunBindingRequestSucceeded(this->Elapsed(), server_addr_, addr);
+    }
+
+    // The keep-alive requests will be stopped after its lifetime has passed.
+    if (WithinLifetime(rtc::TimeMillis())) {
+      port_->request_manager_.SendDelayed(
+          new StunBindingRequest(port_, server_addr_, start_time_),
+          port_->stun_keepalive_delay());
+    }
+  }
+
+  void OnErrorResponse(StunMessage* response) override {
+    const StunErrorCodeAttribute* attr = response->GetErrorCode();
+    if (!attr) {
+      RTC_LOG(LS_ERROR) << "Missing binding response error code.";
+    } else {
+      RTC_LOG(LS_ERROR) << "Binding error response:"
+                           " class="
+                        << attr->eclass() << " number=" << attr->number()
+                        << " reason=" << attr->reason();
+    }
+
+    port_->OnStunBindingOrResolveRequestFailed(
+        server_addr_, attr ? attr->number() : STUN_ERROR_GLOBAL_FAILURE,
+        attr ? attr->reason()
+             : "STUN binding response with no error code attribute.");
+
+    int64_t now = rtc::TimeMillis();
+    if (WithinLifetime(now) &&
+        rtc::TimeDiff(now, start_time_) < RETRY_TIMEOUT) {
+      port_->request_manager_.SendDelayed(
+          new StunBindingRequest(port_, server_addr_, start_time_),
+          port_->stun_keepalive_delay());
+    }
+  }
+  void OnTimeout() override {
+    RTC_LOG(LS_ERROR) << "Binding request timed out from "
+                      << port_->GetLocalAddress().ToSensitiveString() << " ("
+                      << port_->Network()->name() << ")";
+    port_->OnStunBindingOrResolveRequestFailed(
+        server_addr_, SERVER_NOT_REACHABLE_ERROR,
+        "STUN binding request timed out.");
+  }
+
+ private:
+  // Returns true if `now` is within the lifetime of the request (a negative
+  // lifetime means infinite).
+  bool WithinLifetime(int64_t now) const {
+    int lifetime = port_->stun_keepalive_lifetime();
+    return lifetime < 0 || rtc::TimeDiff(now, start_time_) <= lifetime;
+  }
+
+  UDPPort* port_;
+  const rtc::SocketAddress server_addr_;
+
+  int64_t start_time_;
+};
+
+UDPPort::AddressResolver::AddressResolver(
+    rtc::PacketSocketFactory* factory,
+    std::function<void(const rtc::SocketAddress&, int)> done_callback)
+    : socket_factory_(factory), done_(std::move(done_callback)) {}
+
+void UDPPort::AddressResolver::Resolve(
+    const rtc::SocketAddress& address,
+    int family,
+    const webrtc::FieldTrialsView& field_trials) {
+  if (resolvers_.find(address) != resolvers_.end())
+    return;
+
+  auto resolver = socket_factory_->CreateAsyncDnsResolver();
+  auto resolver_ptr = resolver.get();
+  std::pair<rtc::SocketAddress,
+            std::unique_ptr<webrtc::AsyncDnsResolverInterface>>
+      pair = std::make_pair(address, std::move(resolver));
+
+  resolvers_.insert(std::move(pair));
+  auto callback = [this, address] {
+    ResolverMap::const_iterator it = resolvers_.find(address);
+    if (it != resolvers_.end()) {
+      done_(it->first, it->second->result().GetError());
+    }
+  };
+  resolver_ptr->Start(address, family, std::move(callback));
+}
+
+bool UDPPort::AddressResolver::GetResolvedAddress(
+    const rtc::SocketAddress& input,
+    int family,
+    rtc::SocketAddress* output) const {
+  ResolverMap::const_iterator it = resolvers_.find(input);
+  if (it == resolvers_.end())
+    return false;
+
+  return it->second->result().GetResolvedAddress(family, output);
+}
+
+UDPPort::UDPPort(rtc::Thread* thread,
+                 absl::string_view type,
+                 rtc::PacketSocketFactory* factory,
+                 const rtc::Network* network,
+                 rtc::AsyncPacketSocket* socket,
+                 absl::string_view username,
+                 absl::string_view password,
+                 bool emit_local_for_anyaddress,
+                 const webrtc::FieldTrialsView* field_trials)
+    : Port(thread, type, factory, network, username, password, field_trials),
+      request_manager_(
+          thread,
+          [this](const void* data, size_t size, StunRequest* request) {
+            OnSendPacket(data, size, request);
+          }),
+      socket_(socket),
+      error_(0),
+      ready_(false),
+      stun_keepalive_delay_(STUN_KEEPALIVE_INTERVAL),
+      dscp_(rtc::DSCP_NO_CHANGE),
+      emit_local_for_anyaddress_(emit_local_for_anyaddress) {}
+
+UDPPort::UDPPort(rtc::Thread* thread,
+                 absl::string_view type,
+                 rtc::PacketSocketFactory* factory,
+                 const rtc::Network* network,
+                 uint16_t min_port,
+                 uint16_t max_port,
+                 absl::string_view username,
+                 absl::string_view password,
+                 bool emit_local_for_anyaddress,
+                 const webrtc::FieldTrialsView* field_trials)
+    : Port(thread,
+           type,
+           factory,
+           network,
+           min_port,
+           max_port,
+           username,
+           password,
+           field_trials),
+      request_manager_(
+          thread,
+          [this](const void* data, size_t size, StunRequest* request) {
+            OnSendPacket(data, size, request);
+          }),
+      socket_(nullptr),
+      error_(0),
+      ready_(false),
+      stun_keepalive_delay_(STUN_KEEPALIVE_INTERVAL),
+      dscp_(rtc::DSCP_NO_CHANGE),
+      emit_local_for_anyaddress_(emit_local_for_anyaddress) {}
+
+bool UDPPort::Init() {
+  stun_keepalive_lifetime_ = GetStunKeepaliveLifetime();
+  if (!SharedSocket()) {
+    RTC_DCHECK(socket_ == nullptr);
+    socket_ = socket_factory()->CreateUdpSocket(
+        rtc::SocketAddress(Network()->GetBestIP(), 0), min_port(), max_port());
+    if (!socket_) {
+      RTC_LOG(LS_WARNING) << ToString() << ": UDP socket creation failed";
+      return false;
+    }
+    socket_->RegisterReceivedPacketCallback(
+        [&](rtc::AsyncPacketSocket* socket, const rtc::ReceivedPacket& packet) {
+          OnReadPacket(socket, packet);
+        });
+  }
+  socket_->SignalSentPacket.connect(this, &UDPPort::OnSentPacket);
+  socket_->SignalReadyToSend.connect(this, &UDPPort::OnReadyToSend);
+  socket_->SignalAddressReady.connect(this, &UDPPort::OnLocalAddressReady);
+  return true;
+}
+
+UDPPort::~UDPPort() {
+  if (!SharedSocket())
+    delete socket_;
+}
+
+void UDPPort::PrepareAddress() {
+  RTC_DCHECK(request_manager_.empty());
+  if (socket_->GetState() == rtc::AsyncPacketSocket::STATE_BOUND) {
+    OnLocalAddressReady(socket_, socket_->GetLocalAddress());
+  }
+}
+
+void UDPPort::MaybePrepareStunCandidate() {
+  // Sending binding request to the STUN server if address is available to
+  // prepare STUN candidate.
+  if (!server_addresses_.empty()) {
+    SendStunBindingRequests();
+  } else {
+    // Port is done allocating candidates.
+    MaybeSetPortCompleteOrError();
+  }
+}
+
+Connection* UDPPort::CreateConnection(const Candidate& address,
+                                      CandidateOrigin origin) {
+  if (!SupportsProtocol(address.protocol())) {
+    return nullptr;
+  }
+
+  if (!IsCompatibleAddress(address.address())) {
+    return nullptr;
+  }
+
+  // In addition to DCHECK-ing the non-emptiness of local candidates, we also
+  // skip this Port with null if there are latent bugs to violate it; otherwise
+  // it would lead to a crash when accessing the local candidate of the
+  // connection that would be created below.
+  if (Candidates().empty()) {
+    RTC_DCHECK_NOTREACHED();
+    return nullptr;
+  }
+  // When the socket is shared, the srflx candidate is gathered by the UDPPort.
+  // The assumption here is that
+  //  1) if the IP concealment with mDNS is not enabled, the gathering of the
+  //     host candidate of this port (which is synchronous),
+  //  2) or otherwise if enabled, the start of name registration of the host
+  //     candidate (as the start of asynchronous gathering)
+  // is always before the gathering of a srflx candidate (and any prflx
+  // candidate).
+  //
+  // See also the definition of MdnsNameRegistrationStatus::kNotStarted in
+  // port.h.
+  RTC_DCHECK(!SharedSocket() || Candidates()[0].is_local() ||
+             mdns_name_registration_status() !=
+                 MdnsNameRegistrationStatus::kNotStarted);
+
+  Connection* conn = new ProxyConnection(NewWeakPtr(), 0, address);
+  AddOrReplaceConnection(conn);
+  return conn;
+}
+
+int UDPPort::SendTo(const void* data,
+                    size_t size,
+                    const rtc::SocketAddress& addr,
+                    const rtc::PacketOptions& options,
+                    bool payload) {
+  rtc::PacketOptions modified_options(options);
+  CopyPortInformationToPacketInfo(&modified_options.info_signaled_after_sent);
+  int sent = socket_->SendTo(data, size, addr, modified_options);
+  if (sent < 0) {
+    error_ = socket_->GetError();
+    // Rate limiting added for crbug.com/856088.
+    // TODO(webrtc:9622): Use general rate limiting mechanism once it exists.
+    if (send_error_count_ < kSendErrorLogLimit) {
+      ++send_error_count_;
+      RTC_LOG(LS_ERROR) << ToString() << ": UDP send of " << size
+                        << " bytes to host "
+                        << addr.ToSensitiveNameAndAddressString()
+                        << " failed with error " << error_;
+    }
+  } else {
+    send_error_count_ = 0;
+  }
+  return sent;
+}
+
+void UDPPort::UpdateNetworkCost() {
+  Port::UpdateNetworkCost();
+  stun_keepalive_lifetime_ = GetStunKeepaliveLifetime();
+}
+
+rtc::DiffServCodePoint UDPPort::StunDscpValue() const {
+  return dscp_;
+}
+
+int UDPPort::SetOption(rtc::Socket::Option opt, int value) {
+  if (opt == rtc::Socket::OPT_DSCP) {
+    // Save value for future packets we instantiate.
+    dscp_ = static_cast<rtc::DiffServCodePoint>(value);
+  }
+  return socket_->SetOption(opt, value);
+}
+
+int UDPPort::GetOption(rtc::Socket::Option opt, int* value) {
+  return socket_->GetOption(opt, value);
+}
+
+int UDPPort::GetError() {
+  return error_;
+}
+
+bool UDPPort::HandleIncomingPacket(rtc::AsyncPacketSocket* socket,
+                                   const rtc::ReceivedPacket& packet) {
+  // All packets given to UDP port will be consumed.
+  OnReadPacket(socket, packet);
+  return true;
+}
+
+bool UDPPort::SupportsProtocol(absl::string_view protocol) const {
+  return protocol == UDP_PROTOCOL_NAME;
+}
+
+ProtocolType UDPPort::GetProtocol() const {
+  return PROTO_UDP;
+}
+
+void UDPPort::GetStunStats(absl::optional<StunStats>* stats) {
+  *stats = stats_;
+}
+
+void UDPPort::set_stun_keepalive_delay(const absl::optional<int>& delay) {
+  stun_keepalive_delay_ = delay.value_or(STUN_KEEPALIVE_INTERVAL);
+}
+
+void UDPPort::OnLocalAddressReady(rtc::AsyncPacketSocket* socket,
+                                  const rtc::SocketAddress& address) {
+  // When adapter enumeration is disabled and binding to the any address, the
+  // default local address will be issued as a candidate instead if
+  // `emit_local_for_anyaddress` is true. This is to allow connectivity for
+  // applications which absolutely requires a HOST candidate.
+  rtc::SocketAddress addr = address;
+
+  // If MaybeSetDefaultLocalAddress fails, we keep the "any" IP so that at
+  // least the port is listening.
+  MaybeSetDefaultLocalAddress(&addr);
+
+  AddAddress(addr, addr, rtc::SocketAddress(), UDP_PROTOCOL_NAME, "", "",
+             LOCAL_PORT_TYPE, ICE_TYPE_PREFERENCE_HOST, 0, "", false);
+  MaybePrepareStunCandidate();
+}
+
+void UDPPort::PostAddAddress(bool is_final) {
+  MaybeSetPortCompleteOrError();
+}
+
+void UDPPort::OnReadPacket(rtc::AsyncPacketSocket* socket,
+                           const rtc::ReceivedPacket& packet) {
+  RTC_DCHECK(socket == socket_);
+  RTC_DCHECK(!packet.source_address().IsUnresolvedIP());
+
+  // Look for a response from the STUN server.
+  // Even if the response doesn't match one of our outstanding requests, we
+  // will eat it because it might be a response to a retransmitted packet, and
+  // we already cleared the request when we got the first response.
+  if (server_addresses_.find(packet.source_address()) !=
+      server_addresses_.end()) {
+    request_manager_.CheckResponse(
+        reinterpret_cast<const char*>(packet.payload().data()),
+        packet.payload().size());
+    return;
+  }
+
+  if (Connection* conn = GetConnection(packet.source_address())) {
+    conn->OnReadPacket(packet);
+  } else {
+    Port::OnReadPacket(packet, PROTO_UDP);
+  }
+}
+
+void UDPPort::OnSentPacket(rtc::AsyncPacketSocket* socket,
+                           const rtc::SentPacket& sent_packet) {
+  PortInterface::SignalSentPacket(sent_packet);
+}
+
+void UDPPort::OnReadyToSend(rtc::AsyncPacketSocket* socket) {
+  Port::OnReadyToSend();
+}
+
+void UDPPort::SendStunBindingRequests() {
+  // We will keep pinging the stun server to make sure our NAT pin-hole stays
+  // open until the deadline (specified in SendStunBindingRequest).
+  RTC_DCHECK(request_manager_.empty());
+
+  for (ServerAddresses::const_iterator it = server_addresses_.begin();
+       it != server_addresses_.end();) {
+    // sending a STUN binding request may cause the current SocketAddress to be
+    // erased from the set, invalidating the loop iterator before it is
+    // incremented (even if the SocketAddress itself still exists). So make a
+    // copy of the loop iterator, which may be safely invalidated.
+    ServerAddresses::const_iterator addr = it++;
+    SendStunBindingRequest(*addr);
+  }
+}
+
+void UDPPort::ResolveStunAddress(const rtc::SocketAddress& stun_addr) {
+  if (!resolver_) {
+    resolver_.reset(new AddressResolver(
+        socket_factory(), [&](const rtc::SocketAddress& input, int error) {
+          OnResolveResult(input, error);
+        }));
+  }
+
+  RTC_LOG(LS_INFO) << ToString() << ": Starting STUN host lookup for "
+                   << stun_addr.ToSensitiveString();
+  resolver_->Resolve(stun_addr, Network()->family(), field_trials());
+}
+
+void UDPPort::OnResolveResult(const rtc::SocketAddress& input, int error) {
+  RTC_DCHECK(resolver_.get() != nullptr);
+
+  rtc::SocketAddress resolved;
+  if (error != 0 || !resolver_->GetResolvedAddress(
+                        input, Network()->GetBestIP().family(), &resolved)) {
+    RTC_LOG(LS_WARNING) << ToString()
+                        << ": StunPort: stun host lookup received error "
+                        << error;
+    OnStunBindingOrResolveRequestFailed(input, SERVER_NOT_REACHABLE_ERROR,
+                                        "STUN host lookup received error.");
+    return;
+  }
+
+  server_addresses_.erase(input);
+
+  if (server_addresses_.find(resolved) == server_addresses_.end()) {
+    server_addresses_.insert(resolved);
+    SendStunBindingRequest(resolved);
+  }
+}
+
+void UDPPort::SendStunBindingRequest(const rtc::SocketAddress& stun_addr) {
+  if (stun_addr.IsUnresolvedIP()) {
+    ResolveStunAddress(stun_addr);
+
+  } else if (socket_->GetState() == rtc::AsyncPacketSocket::STATE_BOUND) {
+    // Check if `server_addr_` is compatible with the port's ip.
+    if (IsCompatibleAddress(stun_addr)) {
+      request_manager_.Send(
+          new StunBindingRequest(this, stun_addr, rtc::TimeMillis()));
+    } else {
+      // Since we can't send stun messages to the server, we should mark this
+      // port ready.
+      const char* reason = "STUN server address is incompatible.";
+      RTC_LOG(LS_WARNING) << reason;
+      OnStunBindingOrResolveRequestFailed(stun_addr, SERVER_NOT_REACHABLE_ERROR,
+                                          reason);
+    }
+  }
+}
+
+bool UDPPort::MaybeSetDefaultLocalAddress(rtc::SocketAddress* addr) const {
+  if (!addr->IsAnyIP() || !emit_local_for_anyaddress_ ||
+      !Network()->default_local_address_provider()) {
+    return true;
+  }
+  rtc::IPAddress default_address;
+  bool result =
+      Network()->default_local_address_provider()->GetDefaultLocalAddress(
+          addr->family(), &default_address);
+  if (!result || default_address.IsNil()) {
+    return false;
+  }
+
+  addr->SetIP(default_address);
+  return true;
+}
+
+void UDPPort::OnStunBindingRequestSucceeded(
+    int rtt_ms,
+    const rtc::SocketAddress& stun_server_addr,
+    const rtc::SocketAddress& stun_reflected_addr) {
+  RTC_DCHECK(stats_.stun_binding_responses_received <
+             stats_.stun_binding_requests_sent);
+  stats_.stun_binding_responses_received++;
+  stats_.stun_binding_rtt_ms_total += rtt_ms;
+  stats_.stun_binding_rtt_ms_squared_total += rtt_ms * rtt_ms;
+  if (bind_request_succeeded_servers_.find(stun_server_addr) !=
+      bind_request_succeeded_servers_.end()) {
+    return;
+  }
+  bind_request_succeeded_servers_.insert(stun_server_addr);
+  // If socket is shared and `stun_reflected_addr` is equal to local socket
+  // address and mDNS obfuscation is not enabled, or if the same address has
+  // been added by another STUN server, then discarding the stun address.
+  // For STUN, related address is the local socket address.
+  if ((!SharedSocket() || stun_reflected_addr != socket_->GetLocalAddress() ||
+       Network()->GetMdnsResponder() != nullptr) &&
+      !HasStunCandidateWithAddress(stun_reflected_addr)) {
+    rtc::SocketAddress related_address = socket_->GetLocalAddress();
+    // If we can't stamp the related address correctly, empty it to avoid leak.
+    if (!MaybeSetDefaultLocalAddress(&related_address)) {
+      related_address =
+          rtc::EmptySocketAddressWithFamily(related_address.family());
+    }
+
+    rtc::StringBuilder url;
+    url << "stun:" << stun_server_addr.hostname() << ":"
+        << stun_server_addr.port();
+    AddAddress(stun_reflected_addr, socket_->GetLocalAddress(), related_address,
+               UDP_PROTOCOL_NAME, "", "", STUN_PORT_TYPE,
+               ICE_TYPE_PREFERENCE_SRFLX, 0, url.str(), false);
+  }
+  MaybeSetPortCompleteOrError();
+}
+
+void UDPPort::OnStunBindingOrResolveRequestFailed(
+    const rtc::SocketAddress& stun_server_addr,
+    int error_code,
+    absl::string_view reason) {
+  rtc::StringBuilder url;
+  url << "stun:" << stun_server_addr.ToString();
+  SignalCandidateError(
+      this, IceCandidateErrorEvent(GetLocalAddress().HostAsSensitiveURIString(),
+                                   GetLocalAddress().port(), url.str(),
+                                   error_code, reason));
+  if (bind_request_failed_servers_.find(stun_server_addr) !=
+      bind_request_failed_servers_.end()) {
+    return;
+  }
+  bind_request_failed_servers_.insert(stun_server_addr);
+  MaybeSetPortCompleteOrError();
+}
+
+void UDPPort::MaybeSetPortCompleteOrError() {
+  if (mdns_name_registration_status() ==
+      MdnsNameRegistrationStatus::kInProgress) {
+    return;
+  }
+
+  if (ready_) {
+    return;
+  }
+
+  // Do not set port ready if we are still waiting for bind responses.
+  const size_t servers_done_bind_request =
+      bind_request_failed_servers_.size() +
+      bind_request_succeeded_servers_.size();
+  if (server_addresses_.size() != servers_done_bind_request) {
+    return;
+  }
+
+  // Setting ready status.
+  ready_ = true;
+
+  // The port is "completed" if there is no stun server provided, or the bind
+  // request succeeded for any stun server, or the socket is shared.
+  if (server_addresses_.empty() || bind_request_succeeded_servers_.size() > 0 ||
+      SharedSocket()) {
+    SignalPortComplete(this);
+  } else {
+    SignalPortError(this);
+  }
+}
+
+// TODO(?): merge this with SendTo above.
+void UDPPort::OnSendPacket(const void* data, size_t size, StunRequest* req) {
+  StunBindingRequest* sreq = static_cast<StunBindingRequest*>(req);
+  rtc::PacketOptions options(StunDscpValue());
+  options.info_signaled_after_sent.packet_type = rtc::PacketType::kStunMessage;
+  CopyPortInformationToPacketInfo(&options.info_signaled_after_sent);
+  if (socket_->SendTo(data, size, sreq->server_addr(), options) < 0) {
+    RTC_LOG_ERR_EX(LS_ERROR, socket_->GetError())
+        << "UDP send of " << size << " bytes to host "
+        << sreq->server_addr().ToSensitiveNameAndAddressString()
+        << " failed with error " << error_;
+  }
+  stats_.stun_binding_requests_sent++;
+}
+
+bool UDPPort::HasStunCandidateWithAddress(
+    const rtc::SocketAddress& addr) const {
+  const std::vector<Candidate>& existing_candidates = Candidates();
+  std::vector<Candidate>::const_iterator it = existing_candidates.begin();
+  for (; it != existing_candidates.end(); ++it) {
+    if (it->is_stun() && it->address() == addr)
+      return true;
+  }
+  return false;
+}
+
+std::unique_ptr<StunPort> StunPort::Create(
+    rtc::Thread* thread,
+    rtc::PacketSocketFactory* factory,
+    const rtc::Network* network,
+    uint16_t min_port,
+    uint16_t max_port,
+    absl::string_view username,
+    absl::string_view password,
+    const ServerAddresses& servers,
+    absl::optional<int> stun_keepalive_interval,
+    const webrtc::FieldTrialsView* field_trials) {
+  // Using `new` to access a non-public constructor.
+  auto port = absl::WrapUnique(new StunPort(thread, factory, network, min_port,
+                                            max_port, username, password,
+                                            servers, field_trials));
+  port->set_stun_keepalive_delay(stun_keepalive_interval);
+  if (!port->Init()) {
+    return nullptr;
+  }
+  return port;
+}
+
+StunPort::StunPort(rtc::Thread* thread,
+                   rtc::PacketSocketFactory* factory,
+                   const rtc::Network* network,
+                   uint16_t min_port,
+                   uint16_t max_port,
+                   absl::string_view username,
+                   absl::string_view password,
+                   const ServerAddresses& servers,
+                   const webrtc::FieldTrialsView* field_trials)
+    : UDPPort(thread,
+              STUN_PORT_TYPE,
+              factory,
+              network,
+              min_port,
+              max_port,
+              username,
+              password,
+              false,
+              field_trials) {
+  set_server_addresses(servers);
+}
+
+void StunPort::PrepareAddress() {
+  SendStunBindingRequests();
+}
+
+}  // namespace cricket