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/*
* Copyright 2015 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/stunprober/stun_prober.h"
#include <cstdint>
#include <map>
#include <memory>
#include <set>
#include <string>
#include <utility>
#include "api/array_view.h"
#include "api/packet_socket_factory.h"
#include "api/task_queue/pending_task_safety_flag.h"
#include "api/transport/stun.h"
#include "api/units/time_delta.h"
#include "rtc_base/async_packet_socket.h"
#include "rtc_base/checks.h"
#include "rtc_base/network/received_packet.h"
#include "rtc_base/thread.h"
#include "rtc_base/time_utils.h"
namespace stunprober {
namespace {
using ::webrtc::SafeTask;
using ::webrtc::TimeDelta;
const int THREAD_WAKE_UP_INTERVAL_MS = 5;
template <typename T>
void IncrementCounterByAddress(std::map<T, int>* counter_per_ip, const T& ip) {
counter_per_ip->insert(std::make_pair(ip, 0)).first->second++;
}
} // namespace
// A requester tracks the requests and responses from a single socket to many
// STUN servers
class StunProber::Requester : public sigslot::has_slots<> {
public:
// Each Request maps to a request and response.
struct Request {
// Actual time the STUN bind request was sent.
int64_t sent_time_ms = 0;
// Time the response was received.
int64_t received_time_ms = 0;
// Server reflexive address from STUN response for this given request.
rtc::SocketAddress srflx_addr;
rtc::IPAddress server_addr;
int64_t rtt() { return received_time_ms - sent_time_ms; }
void ProcessResponse(rtc::ArrayView<const uint8_t> payload);
};
// StunProber provides `server_ips` for Requester to probe. For shared
// socket mode, it'll be all the resolved IP addresses. For non-shared mode,
// it'll just be a single address.
Requester(StunProber* prober,
rtc::AsyncPacketSocket* socket,
const std::vector<rtc::SocketAddress>& server_ips);
~Requester() override;
Requester(const Requester&) = delete;
Requester& operator=(const Requester&) = delete;
// There is no callback for SendStunRequest as the underneath socket send is
// expected to be completed immediately. Otherwise, it'll skip this request
// and move to the next one.
void SendStunRequest();
void OnStunResponseReceived(rtc::AsyncPacketSocket* socket,
const rtc::ReceivedPacket& packet);
const std::vector<Request*>& requests() { return requests_; }
// Whether this Requester has completed all requests.
bool Done() {
return static_cast<size_t>(num_request_sent_) == server_ips_.size();
}
private:
Request* GetRequestByAddress(const rtc::IPAddress& ip);
StunProber* prober_;
// The socket for this session.
std::unique_ptr<rtc::AsyncPacketSocket> socket_;
// Temporary SocketAddress and buffer for RecvFrom.
rtc::SocketAddress addr_;
std::unique_ptr<rtc::ByteBufferWriter> response_packet_;
std::vector<Request*> requests_;
std::vector<rtc::SocketAddress> server_ips_;
int16_t num_request_sent_ = 0;
int16_t num_response_received_ = 0;
webrtc::SequenceChecker& thread_checker_;
};
StunProber::Requester::Requester(
StunProber* prober,
rtc::AsyncPacketSocket* socket,
const std::vector<rtc::SocketAddress>& server_ips)
: prober_(prober),
socket_(socket),
response_packet_(new rtc::ByteBufferWriter(nullptr, kMaxUdpBufferSize)),
server_ips_(server_ips),
thread_checker_(prober->thread_checker_) {
socket_->RegisterReceivedPacketCallback(
[&](rtc::AsyncPacketSocket* socket, const rtc::ReceivedPacket& packet) {
OnStunResponseReceived(socket, packet);
});
}
StunProber::Requester::~Requester() {
if (socket_) {
socket_->Close();
}
for (auto* req : requests_) {
if (req) {
delete req;
}
}
}
void StunProber::Requester::SendStunRequest() {
RTC_DCHECK(thread_checker_.IsCurrent());
requests_.push_back(new Request());
Request& request = *(requests_.back());
// Random transaction ID, STUN_BINDING_REQUEST
cricket::StunMessage message(cricket::STUN_BINDING_REQUEST);
std::unique_ptr<rtc::ByteBufferWriter> request_packet(
new rtc::ByteBufferWriter(nullptr, kMaxUdpBufferSize));
if (!message.Write(request_packet.get())) {
prober_->ReportOnFinished(WRITE_FAILED);
return;
}
auto addr = server_ips_[num_request_sent_];
request.server_addr = addr.ipaddr();
// The write must succeed immediately. Otherwise, the calculating of the STUN
// request timing could become too complicated. Callback is ignored by passing
// empty AsyncCallback.
rtc::PacketOptions options;
int rv = socket_->SendTo(request_packet->Data(), request_packet->Length(),
addr, options);
if (rv < 0) {
prober_->ReportOnFinished(WRITE_FAILED);
return;
}
request.sent_time_ms = rtc::TimeMillis();
num_request_sent_++;
RTC_DCHECK(static_cast<size_t>(num_request_sent_) <= server_ips_.size());
}
void StunProber::Requester::Request::ProcessResponse(
rtc::ArrayView<const uint8_t> payload) {
int64_t now = rtc::TimeMillis();
rtc::ByteBufferReader message(payload);
cricket::StunMessage stun_response;
if (!stun_response.Read(&message)) {
// Invalid or incomplete STUN packet.
received_time_ms = 0;
return;
}
// Get external address of the socket.
const cricket::StunAddressAttribute* addr_attr =
stun_response.GetAddress(cricket::STUN_ATTR_MAPPED_ADDRESS);
if (addr_attr == nullptr) {
// Addresses not available to detect whether or not behind a NAT.
return;
}
if (addr_attr->family() != cricket::STUN_ADDRESS_IPV4 &&
addr_attr->family() != cricket::STUN_ADDRESS_IPV6) {
return;
}
received_time_ms = now;
srflx_addr = addr_attr->GetAddress();
}
void StunProber::Requester::OnStunResponseReceived(
rtc::AsyncPacketSocket* socket,
const rtc::ReceivedPacket& packet) {
RTC_DCHECK(thread_checker_.IsCurrent());
RTC_DCHECK(socket_);
Request* request = GetRequestByAddress(packet.source_address().ipaddr());
if (!request) {
// Something is wrong, finish the test.
prober_->ReportOnFinished(GENERIC_FAILURE);
return;
}
num_response_received_++;
request->ProcessResponse(packet.payload());
}
StunProber::Requester::Request* StunProber::Requester::GetRequestByAddress(
const rtc::IPAddress& ipaddr) {
RTC_DCHECK(thread_checker_.IsCurrent());
for (auto* request : requests_) {
if (request->server_addr == ipaddr) {
return request;
}
}
return nullptr;
}
StunProber::Stats::Stats() = default;
StunProber::Stats::~Stats() = default;
StunProber::ObserverAdapter::ObserverAdapter() = default;
StunProber::ObserverAdapter::~ObserverAdapter() = default;
void StunProber::ObserverAdapter::OnPrepared(StunProber* stunprober,
Status status) {
if (status == SUCCESS) {
stunprober->Start(this);
} else {
callback_(stunprober, status);
}
}
void StunProber::ObserverAdapter::OnFinished(StunProber* stunprober,
Status status) {
callback_(stunprober, status);
}
StunProber::StunProber(rtc::PacketSocketFactory* socket_factory,
rtc::Thread* thread,
std::vector<const rtc::Network*> networks)
: interval_ms_(0),
socket_factory_(socket_factory),
thread_(thread),
networks_(std::move(networks)) {}
StunProber::~StunProber() {
RTC_DCHECK(thread_checker_.IsCurrent());
for (auto* req : requesters_) {
if (req) {
delete req;
}
}
for (auto* s : sockets_) {
if (s) {
delete s;
}
}
}
bool StunProber::Start(const std::vector<rtc::SocketAddress>& servers,
bool shared_socket_mode,
int interval_ms,
int num_request_per_ip,
int timeout_ms,
const AsyncCallback callback) {
observer_adapter_.set_callback(callback);
return Prepare(servers, shared_socket_mode, interval_ms, num_request_per_ip,
timeout_ms, &observer_adapter_);
}
bool StunProber::Prepare(const std::vector<rtc::SocketAddress>& servers,
bool shared_socket_mode,
int interval_ms,
int num_request_per_ip,
int timeout_ms,
StunProber::Observer* observer) {
RTC_DCHECK(thread_checker_.IsCurrent());
interval_ms_ = interval_ms;
shared_socket_mode_ = shared_socket_mode;
requests_per_ip_ = num_request_per_ip;
if (requests_per_ip_ == 0 || servers.size() == 0) {
return false;
}
timeout_ms_ = timeout_ms;
servers_ = servers;
observer_ = observer;
// Remove addresses that are already resolved.
for (auto it = servers_.begin(); it != servers_.end();) {
if (it->ipaddr().family() != AF_UNSPEC) {
all_servers_addrs_.push_back(*it);
it = servers_.erase(it);
} else {
++it;
}
}
if (servers_.empty()) {
CreateSockets();
return true;
}
return ResolveServerName(servers_.back());
}
bool StunProber::Start(StunProber::Observer* observer) {
observer_ = observer;
if (total_ready_sockets_ != total_socket_required()) {
return false;
}
MaybeScheduleStunRequests();
return true;
}
bool StunProber::ResolveServerName(const rtc::SocketAddress& addr) {
RTC_DCHECK(!resolver_);
resolver_ = socket_factory_->CreateAsyncDnsResolver();
if (!resolver_) {
return false;
}
resolver_->Start(addr, [this] { OnServerResolved(resolver_->result()); });
return true;
}
void StunProber::OnSocketReady(rtc::AsyncPacketSocket* socket,
const rtc::SocketAddress& addr) {
total_ready_sockets_++;
if (total_ready_sockets_ == total_socket_required()) {
ReportOnPrepared(SUCCESS);
}
}
void StunProber::OnServerResolved(
const webrtc::AsyncDnsResolverResult& result) {
RTC_DCHECK(thread_checker_.IsCurrent());
rtc::SocketAddress received_address;
if (result.GetResolvedAddress(AF_INET, &received_address)) {
// Construct an address without the name in it.
rtc::SocketAddress addr(received_address.ipaddr(), received_address.port());
all_servers_addrs_.push_back(addr);
}
resolver_.reset();
servers_.pop_back();
if (servers_.size()) {
if (!ResolveServerName(servers_.back())) {
ReportOnPrepared(RESOLVE_FAILED);
}
return;
}
if (all_servers_addrs_.size() == 0) {
ReportOnPrepared(RESOLVE_FAILED);
return;
}
CreateSockets();
}
void StunProber::CreateSockets() {
// Dedupe.
std::set<rtc::SocketAddress> addrs(all_servers_addrs_.begin(),
all_servers_addrs_.end());
all_servers_addrs_.assign(addrs.begin(), addrs.end());
// Prepare all the sockets beforehand. All of them will bind to "any" address.
while (sockets_.size() < total_socket_required()) {
std::unique_ptr<rtc::AsyncPacketSocket> socket(
socket_factory_->CreateUdpSocket(rtc::SocketAddress(INADDR_ANY, 0), 0,
0));
if (!socket) {
ReportOnPrepared(GENERIC_FAILURE);
return;
}
// Chrome and WebRTC behave differently in terms of the state of a socket
// once returned from PacketSocketFactory::CreateUdpSocket.
if (socket->GetState() == rtc::AsyncPacketSocket::STATE_BINDING) {
socket->SignalAddressReady.connect(this, &StunProber::OnSocketReady);
} else {
OnSocketReady(socket.get(), rtc::SocketAddress(INADDR_ANY, 0));
}
sockets_.push_back(socket.release());
}
}
StunProber::Requester* StunProber::CreateRequester() {
RTC_DCHECK(thread_checker_.IsCurrent());
if (!sockets_.size()) {
return nullptr;
}
StunProber::Requester* requester;
if (shared_socket_mode_) {
requester = new Requester(this, sockets_.back(), all_servers_addrs_);
} else {
std::vector<rtc::SocketAddress> server_ip;
server_ip.push_back(
all_servers_addrs_[(num_request_sent_ % all_servers_addrs_.size())]);
requester = new Requester(this, sockets_.back(), server_ip);
}
sockets_.pop_back();
return requester;
}
bool StunProber::SendNextRequest() {
if (!current_requester_ || current_requester_->Done()) {
current_requester_ = CreateRequester();
requesters_.push_back(current_requester_);
}
if (!current_requester_) {
return false;
}
current_requester_->SendStunRequest();
num_request_sent_++;
return true;
}
bool StunProber::should_send_next_request(int64_t now) {
if (interval_ms_ < THREAD_WAKE_UP_INTERVAL_MS) {
return now >= next_request_time_ms_;
} else {
return (now + (THREAD_WAKE_UP_INTERVAL_MS / 2)) >= next_request_time_ms_;
}
}
int StunProber::get_wake_up_interval_ms() {
if (interval_ms_ < THREAD_WAKE_UP_INTERVAL_MS) {
return 1;
} else {
return THREAD_WAKE_UP_INTERVAL_MS;
}
}
void StunProber::MaybeScheduleStunRequests() {
RTC_DCHECK_RUN_ON(thread_);
int64_t now = rtc::TimeMillis();
if (Done()) {
thread_->PostDelayedTask(
SafeTask(task_safety_.flag(), [this] { ReportOnFinished(SUCCESS); }),
TimeDelta::Millis(timeout_ms_));
return;
}
if (should_send_next_request(now)) {
if (!SendNextRequest()) {
ReportOnFinished(GENERIC_FAILURE);
return;
}
next_request_time_ms_ = now + interval_ms_;
}
thread_->PostDelayedTask(
SafeTask(task_safety_.flag(), [this] { MaybeScheduleStunRequests(); }),
TimeDelta::Millis(get_wake_up_interval_ms()));
}
bool StunProber::GetStats(StunProber::Stats* prob_stats) const {
// No need to be on the same thread.
if (!prob_stats) {
return false;
}
StunProber::Stats stats;
int rtt_sum = 0;
int64_t first_sent_time = 0;
int64_t last_sent_time = 0;
NatType nat_type = NATTYPE_INVALID;
// Track of how many srflx IP that we have seen.
std::set<rtc::IPAddress> srflx_ips;
// If we're not receiving any response on a given IP, all requests sent to
// that IP should be ignored as this could just be an DNS error.
std::map<rtc::IPAddress, int> num_response_per_server;
std::map<rtc::IPAddress, int> num_request_per_server;
for (auto* requester : requesters_) {
std::map<rtc::SocketAddress, int> num_response_per_srflx_addr;
for (auto* request : requester->requests()) {
if (request->sent_time_ms <= 0) {
continue;
}
++stats.raw_num_request_sent;
IncrementCounterByAddress(&num_request_per_server, request->server_addr);
if (!first_sent_time) {
first_sent_time = request->sent_time_ms;
}
last_sent_time = request->sent_time_ms;
if (request->received_time_ms < request->sent_time_ms) {
continue;
}
IncrementCounterByAddress(&num_response_per_server, request->server_addr);
IncrementCounterByAddress(&num_response_per_srflx_addr,
request->srflx_addr);
rtt_sum += request->rtt();
stats.srflx_addrs.insert(request->srflx_addr.ToString());
srflx_ips.insert(request->srflx_addr.ipaddr());
}
// If we're using shared mode and seeing >1 srflx addresses for a single
// requester, it's symmetric NAT.
if (shared_socket_mode_ && num_response_per_srflx_addr.size() > 1) {
nat_type = NATTYPE_SYMMETRIC;
}
}
// We're probably not behind a regular NAT. We have more than 1 distinct
// server reflexive IPs.
if (srflx_ips.size() > 1) {
return false;
}
int num_sent = 0;
int num_received = 0;
int num_server_ip_with_response = 0;
for (const auto& kv : num_response_per_server) {
RTC_DCHECK_GT(kv.second, 0);
num_server_ip_with_response++;
num_received += kv.second;
num_sent += num_request_per_server[kv.first];
}
// Shared mode is only true if we use the shared socket and there are more
// than 1 responding servers.
stats.shared_socket_mode =
shared_socket_mode_ && (num_server_ip_with_response > 1);
if (stats.shared_socket_mode && nat_type == NATTYPE_INVALID) {
nat_type = NATTYPE_NON_SYMMETRIC;
}
// If we could find a local IP matching srflx, we're not behind a NAT.
rtc::SocketAddress srflx_addr;
if (stats.srflx_addrs.size() &&
!srflx_addr.FromString(*(stats.srflx_addrs.begin()))) {
return false;
}
for (const auto* net : networks_) {
if (srflx_addr.ipaddr() == net->GetBestIP()) {
nat_type = stunprober::NATTYPE_NONE;
stats.host_ip = net->GetBestIP().ToString();
break;
}
}
// Finally, we know we're behind a NAT but can't determine which type it is.
if (nat_type == NATTYPE_INVALID) {
nat_type = NATTYPE_UNKNOWN;
}
stats.nat_type = nat_type;
stats.num_request_sent = num_sent;
stats.num_response_received = num_received;
stats.target_request_interval_ns = interval_ms_ * 1000;
if (num_sent) {
stats.success_percent = static_cast<int>(100 * num_received / num_sent);
}
if (stats.raw_num_request_sent > 1) {
stats.actual_request_interval_ns =
(1000 * (last_sent_time - first_sent_time)) /
(stats.raw_num_request_sent - 1);
}
if (num_received) {
stats.average_rtt_ms = static_cast<int>((rtt_sum / num_received));
}
*prob_stats = stats;
return true;
}
void StunProber::ReportOnPrepared(StunProber::Status status) {
if (observer_) {
observer_->OnPrepared(this, status);
}
}
void StunProber::ReportOnFinished(StunProber::Status status) {
if (observer_) {
observer_->OnFinished(this, status);
}
}
} // namespace stunprober