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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 <map>
#include <vector>
#include "rtc_base/checks.h"
#include "rtc_base/constructor_magic.h"
#include "rtc_base/event.h"
#include "rtc_base/fake_clock.h"
#include "rtc_base/message_handler.h"
#include "rtc_base/socket_server.h"
#include "rtc_base/synchronization/mutex.h"
namespace rtc {
class Packet;
class VirtualSocket;
class SocketAddressPair;
// Simulates a network in the same manner as a loopback interface. The
// interface can create as many addresses as you want. All of the sockets
// created by this network will be able to communicate with one another, unless
// they are bound to addresses from incompatible families.
class VirtualSocketServer : public SocketServer {
// This constructor needs to be used if the test uses a fake clock and
// ProcessMessagesUntilIdle, since ProcessMessagesUntilIdle needs a way of
// advancing time.
explicit VirtualSocketServer(ThreadProcessingFakeClock* fake_clock);
~VirtualSocketServer() override;
// The default route indicates which local address to use when a socket is
// bound to the 'any' address, e.g.
IPAddress GetDefaultRoute(int family);
void SetDefaultRoute(const IPAddress& from_addr);
// Limits the network bandwidth (maximum bytes per second). Zero means that
// all sends occur instantly. Defaults to 0.
uint32_t bandwidth() const { return bandwidth_; }
void set_bandwidth(uint32_t bandwidth) { bandwidth_ = bandwidth; }
// Limits the amount of data which can be in flight on the network without
// packet loss (on a per sender basis). Defaults to 64 KB.
uint32_t network_capacity() const { return network_capacity_; }
void set_network_capacity(uint32_t capacity) { network_capacity_ = capacity; }
// The amount of data which can be buffered by tcp on the sender's side
uint32_t send_buffer_capacity() const { return send_buffer_capacity_; }
void set_send_buffer_capacity(uint32_t capacity) {
send_buffer_capacity_ = capacity;
// The amount of data which can be buffered by tcp on the receiver's side
uint32_t recv_buffer_capacity() const { return recv_buffer_capacity_; }
void set_recv_buffer_capacity(uint32_t capacity) {
recv_buffer_capacity_ = capacity;
// Controls the (transit) delay for packets sent in the network. This does
// not inclue the time required to sit in the send queue. Both of these
// values are measured in milliseconds. Defaults to no delay.
uint32_t delay_mean() const { return delay_mean_; }
uint32_t delay_stddev() const { return delay_stddev_; }
uint32_t delay_samples() const { return delay_samples_; }
void set_delay_mean(uint32_t delay_mean) { delay_mean_ = delay_mean; }
void set_delay_stddev(uint32_t delay_stddev) { delay_stddev_ = delay_stddev; }
void set_delay_samples(uint32_t delay_samples) {
delay_samples_ = delay_samples;
// If the (transit) delay parameters are modified, this method should be
// called to recompute the new distribution.
void UpdateDelayDistribution();
// Controls the (uniform) probability that any sent packet is dropped. This
// is separate from calculations to drop based on queue size.
double drop_probability() { return drop_prob_; }
void set_drop_probability(double drop_prob) {
RTC_DCHECK_GE(drop_prob, 0.0);
RTC_DCHECK_LE(drop_prob, 1.0);
drop_prob_ = drop_prob;
// Controls the maximum UDP payload for the networks simulated
// by this server. Any UDP payload sent that is larger than this will
// be dropped.
size_t max_udp_payload() { return max_udp_payload_; }
void set_max_udp_payload(size_t payload_size) {
max_udp_payload_ = payload_size;
size_t largest_seen_udp_payload() { return largest_seen_udp_payload_; }
// If |blocked| is true, subsequent attempts to send will result in -1 being
// returned, with the socket error set to EWOULDBLOCK.
// If this method is later called with |blocked| set to false, any sockets
// that previously failed to send with EWOULDBLOCK will emit SignalWriteEvent.
// This can be used to simulate the send buffer on a network interface being
// full, and test functionality related to EWOULDBLOCK/SignalWriteEvent.
void SetSendingBlocked(bool blocked);
// SocketFactory:
Socket* CreateSocket(int family, int type) override;
AsyncSocket* CreateAsyncSocket(int family, int type) override;
// SocketServer:
void SetMessageQueue(Thread* queue) override;
bool Wait(int cms, bool process_io) override;
void WakeUp() override;
void SetDelayOnAddress(const rtc::SocketAddress& address, int delay_ms) {
delay_by_ip_[address.ipaddr()] = delay_ms;
// Used by TurnPortTest and TcpPortTest (for example), to mimic a case where
// a proxy returns the local host address instead of the original one the
// port was bound against. Please see WebRTC issue 3927 for more detail.
// If SetAlternativeLocalAddress(A, B) is called, then when something
// attempts to bind a socket to address A, it will get a socket bound to
// address B instead.
void SetAlternativeLocalAddress(const rtc::IPAddress& address,
const rtc::IPAddress& alternative);
typedef std::pair<double, double> Point;
typedef std::vector<Point> Function;
static std::unique_ptr<Function> CreateDistribution(uint32_t mean,
uint32_t stddev,
uint32_t samples);
// Similar to Thread::ProcessMessages, but it only processes messages until
// there are no immediate messages or pending network traffic. Returns false
// if Thread::Stop() was called.
bool ProcessMessagesUntilIdle();
// Sets the next port number to use for testing.
void SetNextPortForTesting(uint16_t port);
// Close a pair of Tcp connections by addresses. Both connections will have
// its own OnClose invoked.
bool CloseTcpConnections(const SocketAddress& addr_local,
const SocketAddress& addr_remote);
// Number of packets that clients have attempted to send through this virtual
// socket server. Intended to be used for test assertions.
uint32_t sent_packets() const { return sent_packets_; }
// Binds the given socket to addr, assigning and IP and Port if necessary
int Bind(VirtualSocket* socket, SocketAddress* addr);
// Binds the given socket to the given (fully-defined) address.
int Bind(VirtualSocket* socket, const SocketAddress& addr);
int Unbind(const SocketAddress& addr, VirtualSocket* socket);
// Adds a mapping between this socket pair and the socket.
void AddConnection(const SocketAddress& client,
const SocketAddress& server,
VirtualSocket* socket);
// Connects the given socket to the socket at the given address
int Connect(VirtualSocket* socket,
const SocketAddress& remote_addr,
bool use_delay);
// Sends a disconnect message to the socket at the given address
bool Disconnect(VirtualSocket* socket);
// Lookup address, and disconnect corresponding socket.
bool Disconnect(const SocketAddress& addr);
// Lookup connection, close corresponding socket.
bool Disconnect(const SocketAddress& local_addr,
const SocketAddress& remote_addr);
// Sends the given packet to the socket at the given address (if one exists).
int SendUdp(VirtualSocket* socket,
const char* data,
size_t data_size,
const SocketAddress& remote_addr);
// Moves as much data as possible from the sender's buffer to the network
void SendTcp(VirtualSocket* socket);
// Like above, but lookup sender by address.
void SendTcp(const SocketAddress& addr);
// Computes the number of milliseconds required to send a packet of this size.
uint32_t SendDelay(uint32_t size);
// Cancel attempts to connect to a socket that is being closed.
void CancelConnects(VirtualSocket* socket);
// Clear incoming messages for a socket that is being closed.
void Clear(VirtualSocket* socket);
void ProcessOneMessage();
void PostSignalReadEvent(VirtualSocket* socket);
// Sending was previously blocked, but now isn't.
sigslot::signal0<> SignalReadyToSend;
// Returns a new IP not used before in this network.
IPAddress GetNextIP(int family);
// Find the socket bound to the given address
VirtualSocket* LookupBinding(const SocketAddress& addr);
uint16_t GetNextPort();
VirtualSocket* CreateSocketInternal(int family, int type);
// Find the socket pair corresponding to this server address.
VirtualSocket* LookupConnection(const SocketAddress& client,
const SocketAddress& server);
void RemoveConnection(const SocketAddress& client,
const SocketAddress& server);
// Places a packet on the network.
void AddPacketToNetwork(VirtualSocket* socket,
VirtualSocket* recipient,
int64_t cur_time,
const char* data,
size_t data_size,
size_t header_size,
bool ordered);
// If the delay has been set for the address of the socket, returns the set
// delay. Otherwise, returns a random transit delay chosen from the
// appropriate distribution.
uint32_t GetTransitDelay(Socket* socket);
// Basic operations on functions.
static std::unique_ptr<Function> Accumulate(std::unique_ptr<Function> f);
static std::unique_ptr<Function> Invert(std::unique_ptr<Function> f);
static std::unique_ptr<Function> Resample(std::unique_ptr<Function> f,
double x1,
double x2,
uint32_t samples);
static double Evaluate(const Function* f, double x);
// Determine if two sockets should be able to communicate.
// We don't (currently) specify an address family for sockets; instead,
// the currently bound address is used to infer the address family.
// Any socket that is not explicitly bound to an IPv4 address is assumed to be
// dual-stack capable.
// This function tests if two addresses can communicate, as well as the
// sockets to which they may be bound (the addresses may or may not yet be
// bound to the sockets).
// First the addresses are tested (after normalization):
// If both have the same family, then communication is OK.
// If only one is IPv4 then false, unless the other is bound to ::.
// This applies even if the IPv4 address is
// The socket arguments are optional; the sockets are checked to see if they
// were explicitly bound to IPv6-any ('::'), and if so communication is
// permitted.
// NB: This scheme doesn't permit non-dualstack IPv6 sockets.
static bool CanInteractWith(VirtualSocket* local, VirtualSocket* remote);
typedef std::map<SocketAddress, VirtualSocket*> AddressMap;
typedef std::map<SocketAddressPair, VirtualSocket*> ConnectionMap;
// May be null if the test doesn't use a fake clock, or it does but doesn't
// use ProcessMessagesUntilIdle.
ThreadProcessingFakeClock* fake_clock_ = nullptr;
// Used to implement Wait/WakeUp.
Event wakeup_;
Thread* msg_queue_;
bool stop_on_idle_;
in_addr next_ipv4_;
in6_addr next_ipv6_;
uint16_t next_port_;
AddressMap* bindings_;
ConnectionMap* connections_;
IPAddress default_route_v4_;
IPAddress default_route_v6_;
uint32_t bandwidth_;
uint32_t network_capacity_;
uint32_t send_buffer_capacity_;
uint32_t recv_buffer_capacity_;
uint32_t delay_mean_;
uint32_t delay_stddev_;
uint32_t delay_samples_;
// Used for testing.
uint32_t sent_packets_ = 0;
std::map<rtc::IPAddress, int> delay_by_ip_;
std::map<rtc::IPAddress, rtc::IPAddress> alternative_address_mapping_;
std::unique_ptr<Function> delay_dist_;
double drop_prob_;
// The largest UDP payload permitted on this virtual socket server.
// The default is the max size of IPv4 fragmented UDP packet payload:
// 65535 bytes - 8 bytes UDP header - 20 bytes IP header.
size_t max_udp_payload_ = 65507;
// The largest UDP payload seen so far.
size_t largest_seen_udp_payload_ = 0;
bool sending_blocked_ = false;
// Implements the socket interface using the virtual network. Packets are
// passed as messages using the message queue of the socket server.
class VirtualSocket : public AsyncSocket,
public MessageHandler,
public sigslot::has_slots<> {
VirtualSocket(VirtualSocketServer* server, int family, int type, bool async);
~VirtualSocket() override;
SocketAddress GetLocalAddress() const override;
SocketAddress GetRemoteAddress() const override;
int Bind(const SocketAddress& addr) override;
int Connect(const SocketAddress& addr) override;
int Close() override;
int Send(const void* pv, size_t cb) override;
int SendTo(const void* pv, size_t cb, const SocketAddress& addr) override;
int Recv(void* pv, size_t cb, int64_t* timestamp) override;
int RecvFrom(void* pv,
size_t cb,
SocketAddress* paddr,
int64_t* timestamp) override;
int Listen(int backlog) override;
VirtualSocket* Accept(SocketAddress* paddr) override;
int GetError() const override;
void SetError(int error) override;
ConnState GetState() const override;
int GetOption(Option opt, int* value) override;
int SetOption(Option opt, int value) override;
void OnMessage(Message* pmsg) override;
size_t recv_buffer_size() const { return recv_buffer_size_; }
size_t send_buffer_size() const { return send_buffer_.size(); }
const char* send_buffer_data() const { return; }
// Used by server sockets to set the local address without binding.
void SetLocalAddress(const SocketAddress& addr);
bool was_any() { return was_any_; }
void set_was_any(bool was_any) { was_any_ = was_any; }
void SetToBlocked();
void UpdateRecv(size_t data_size);
void UpdateSend(size_t data_size);
void MaybeSignalWriteEvent(size_t capacity);
// Adds a packet to be sent. Returns delay, based on network_size_.
uint32_t AddPacket(int64_t cur_time, size_t packet_size);
int64_t UpdateOrderedDelivery(int64_t ts);
// Removes stale packets from the network. Returns current size.
size_t PurgeNetworkPackets(int64_t cur_time);
struct NetworkEntry {
size_t size;
int64_t done_time;
typedef std::deque<SocketAddress> ListenQueue;
typedef std::deque<NetworkEntry> NetworkQueue;
typedef std::vector<char> SendBuffer;
typedef std::list<Packet*> RecvBuffer;
typedef std::map<Option, int> OptionsMap;
int InitiateConnect(const SocketAddress& addr, bool use_delay);
void CompleteConnect(const SocketAddress& addr);
int SendUdp(const void* pv, size_t cb, const SocketAddress& addr);
int SendTcp(const void* pv, size_t cb);
void OnSocketServerReadyToSend();
VirtualSocketServer* const server_;
const int type_;
const bool async_;
ConnState state_;
int error_;
SocketAddress local_addr_;
SocketAddress remote_addr_;
// Pending sockets which can be Accepted
std::unique_ptr<ListenQueue> listen_queue_ RTC_GUARDED_BY(mutex_)
// Data which tcp has buffered for sending
SendBuffer send_buffer_;
// Set to false if the last attempt to send resulted in EWOULDBLOCK.
// Set back to true when the socket can send again.
bool ready_to_send_ = true;
// Mutex to protect the recv_buffer and listen_queue_
webrtc::Mutex mutex_;
// Network model that enforces bandwidth and capacity constraints
NetworkQueue network_;
size_t network_size_;
// The scheduled delivery time of the last packet sent on this socket.
// It is used to ensure ordered delivery of packets sent on this socket.
int64_t last_delivery_time_ = 0;
// Data which has been received from the network
RecvBuffer recv_buffer_ RTC_GUARDED_BY(mutex_);
// The amount of data which is in flight or in recv_buffer_
size_t recv_buffer_size_;
// Is this socket bound?
bool bound_;
// When we bind a socket to Any, VSS's Bind gives it another address. For
// dual-stack sockets, we want to distinguish between sockets that were
// explicitly given a particular address and sockets that had one picked
// for them by VSS.
bool was_any_;
// Store the options that are set
OptionsMap options_map_;
} // namespace rtc