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/*
* libjingle
* Copyright 2004--2005, Google Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "talk/p2p/base/p2ptransportchannel.h"
#include <set>
#include "talk/base/common.h"
#include "talk/base/logging.h"
#include "talk/p2p/base/common.h"
namespace {
// messages for queuing up work for ourselves
const uint32 MSG_SORT = 1;
const uint32 MSG_PING = 2;
const uint32 MSG_ALLOCATE = 3;
// When the socket is unwritable, we will use 10 Kbps (ignoring IP+UDP headers)
// for pinging. When the socket is writable, we will use only 1 Kbps because
// we don't want to degrade the quality on a modem. These numbers should work
// well on a 28.8K modem, which is the slowest connection on which the voice
// quality is reasonable at all.
static const uint32 PING_PACKET_SIZE = 60 * 8;
static const uint32 WRITABLE_DELAY = 1000 * PING_PACKET_SIZE / 1000; // 480ms
static const uint32 UNWRITABLE_DELAY = 1000 * PING_PACKET_SIZE / 10000; // 50ms
// If there is a current writable connection, then we will also try hard to
// make sure it is pinged at this rate.
static const uint32 MAX_CURRENT_WRITABLE_DELAY = 900; // 2*WRITABLE_DELAY - bit
// The minimum improvement in RTT that justifies a switch.
static const double kMinImprovement = 10;
// Amount of time that we wait when *losing* writability before we try doing
// another allocation.
static const int kAllocateDelay = 1 * 1000; // 1 second
// We will try creating a new allocator from scratch after a delay of this
// length without becoming writable (or timing out).
static const int kAllocatePeriod = 20 * 1000; // 20 seconds
cricket::Port::CandidateOrigin GetOrigin(cricket::Port* port,
cricket::Port* origin_port) {
if (!origin_port)
return cricket::Port::ORIGIN_MESSAGE;
else if (port == origin_port)
return cricket::Port::ORIGIN_THIS_PORT;
else
return cricket::Port::ORIGIN_OTHER_PORT;
}
// Compares two connections based only on static information about them.
int CompareConnectionCandidates(cricket::Connection* a,
cricket::Connection* b) {
// Combine local and remote preferences
ASSERT(a->local_candidate().preference() == a->port()->preference());
ASSERT(b->local_candidate().preference() == b->port()->preference());
double a_pref = a->local_candidate().preference()
* a->remote_candidate().preference();
double b_pref = b->local_candidate().preference()
* b->remote_candidate().preference();
// Now check combined preferences. Lower values get sorted last.
if (a_pref > b_pref)
return 1;
if (a_pref < b_pref)
return -1;
// If we're still tied at this point, prefer a younger generation.
return (a->remote_candidate().generation() + a->port()->generation()) -
(b->remote_candidate().generation() + b->port()->generation());
}
// Compare two connections based on their writability and static preferences.
int CompareConnections(cricket::Connection *a, cricket::Connection *b) {
// Sort based on write-state. Better states have lower values.
if (a->write_state() < b->write_state())
return 1;
if (a->write_state() > b->write_state())
return -1;
// Compare the candidate information.
return CompareConnectionCandidates(a, b);
}
// Wraps the comparison connection into a less than operator that puts higher
// priority writable connections first.
class ConnectionCompare {
public:
bool operator()(const cricket::Connection *ca,
const cricket::Connection *cb) {
cricket::Connection* a = const_cast<cricket::Connection*>(ca);
cricket::Connection* b = const_cast<cricket::Connection*>(cb);
// Compare first on writability and static preferences.
int cmp = CompareConnections(a, b);
if (cmp > 0)
return true;
if (cmp < 0)
return false;
// Otherwise, sort based on latency estimate.
return a->rtt() < b->rtt();
// Should we bother checking for the last connection that last received
// data? It would help rendezvous on the connection that is also receiving
// packets.
//
// TODO: Yes we should definitely do this. The TCP protocol gains
// efficiency by being used bidirectionally, as opposed to two separate
// unidirectional streams. This test should probably occur before
// comparison of local prefs (assuming combined prefs are the same). We
// need to be careful though, not to bounce back and forth with both sides
// trying to rendevous with the other.
}
};
// Determines whether we should switch between two connections, based first on
// static preferences and then (if those are equal) on latency estimates.
bool ShouldSwitch(cricket::Connection* a_conn, cricket::Connection* b_conn) {
if (a_conn == b_conn)
return false;
if (!a_conn || !b_conn) // don't think the latter should happen
return true;
int prefs_cmp = CompareConnections(a_conn, b_conn);
if (prefs_cmp < 0)
return true;
if (prefs_cmp > 0)
return false;
return b_conn->rtt() <= a_conn->rtt() + kMinImprovement;
}
} // unnamed namespace
namespace cricket {
P2PTransportChannel::P2PTransportChannel(const std::string &name,
const std::string &content_type,
P2PTransport* transport,
PortAllocator *allocator) :
TransportChannelImpl(name, content_type),
transport_(transport),
allocator_(allocator),
worker_thread_(talk_base::Thread::Current()),
incoming_only_(false),
waiting_for_signaling_(false),
error_(0),
best_connection_(NULL),
pinging_started_(false),
sort_dirty_(false),
was_writable_(false),
was_timed_out_(true) {
}
P2PTransportChannel::~P2PTransportChannel() {
ASSERT(worker_thread_ == talk_base::Thread::Current());
for (uint32 i = 0; i < allocator_sessions_.size(); ++i)
delete allocator_sessions_[i];
}
// Add the allocator session to our list so that we know which sessions
// are still active.
void P2PTransportChannel::AddAllocatorSession(PortAllocatorSession* session) {
session->set_generation(static_cast<uint32>(allocator_sessions_.size()));
allocator_sessions_.push_back(session);
// We now only want to apply new candidates that we receive to the ports
// created by this new session because these are replacing those of the
// previous sessions.
ports_.clear();
session->SignalPortReady.connect(this, &P2PTransportChannel::OnPortReady);
session->SignalCandidatesReady.connect(
this, &P2PTransportChannel::OnCandidatesReady);
session->GetInitialPorts();
if (pinging_started_)
session->StartGetAllPorts();
}
// Go into the state of processing candidates, and running in general
void P2PTransportChannel::Connect() {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Kick off an allocator session
Allocate();
// Start pinging as the ports come in.
thread()->Post(this, MSG_PING);
}
// Reset the socket, clear up any previous allocations and start over
void P2PTransportChannel::Reset() {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Get rid of all the old allocators. This should clean up everything.
for (uint32 i = 0; i < allocator_sessions_.size(); ++i)
delete allocator_sessions_[i];
allocator_sessions_.clear();
ports_.clear();
connections_.clear();
best_connection_ = NULL;
// Forget about all of the candidates we got before.
remote_candidates_.clear();
// Revert to the initial state.
set_readable(false);
set_writable(false);
// Reinitialize the rest of our state.
waiting_for_signaling_ = false;
pinging_started_ = false;
sort_dirty_ = false;
was_writable_ = false;
was_timed_out_ = true;
// If we allocated before, start a new one now.
if (transport_->connect_requested())
Allocate();
// Start pinging as the ports come in.
thread()->Clear(this);
thread()->Post(this, MSG_PING);
}
// A new port is available, attempt to make connections for it
void P2PTransportChannel::OnPortReady(PortAllocatorSession *session,
Port* port) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Set in-effect options on the new port
for (OptionMap::const_iterator it = options_.begin();
it != options_.end();
++it) {
int val = port->SetOption(it->first, it->second);
if (val < 0) {
LOG_J(LS_WARNING, port) << "SetOption(" << it->first
<< ", " << it->second
<< ") failed: " << port->GetError();
}
}
// Remember the ports and candidates, and signal that candidates are ready.
// The session will handle this, and send an initiate/accept/modify message
// if one is pending.
ports_.push_back(port);
port->SignalUnknownAddress.connect(
this, &P2PTransportChannel::OnUnknownAddress);
port->SignalDestroyed.connect(this, &P2PTransportChannel::OnPortDestroyed);
// Attempt to create a connection from this new port to all of the remote
// candidates that we were given so far.
std::vector<RemoteCandidate>::iterator iter;
for (iter = remote_candidates_.begin(); iter != remote_candidates_.end();
++iter) {
CreateConnection(port, *iter, iter->origin_port(), false);
}
SortConnections();
}
// A new candidate is available, let listeners know
void P2PTransportChannel::OnCandidatesReady(
PortAllocatorSession *session, const std::vector<Candidate>& candidates) {
for (size_t i = 0; i < candidates.size(); ++i) {
SignalCandidateReady(this, candidates[i]);
}
}
// Handle stun packets
void P2PTransportChannel::OnUnknownAddress(
Port *port, const talk_base::SocketAddress &address, StunMessage *stun_msg,
const std::string &remote_username) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Port has received a valid stun packet from an address that no Connection
// is currently available for. See if the remote user name is in the remote
// candidate list. If it isn't return error to the stun request.
const Candidate *candidate = NULL;
std::vector<RemoteCandidate>::iterator it;
for (it = remote_candidates_.begin(); it != remote_candidates_.end(); ++it) {
if ((*it).username() == remote_username) {
candidate = &(*it);
break;
}
}
if (candidate == NULL) {
// Don't know about this username, the request is bogus
// This sometimes happens if a binding response comes in before the ACCEPT
// message. It is totally valid; the retry state machine will try again.
port->SendBindingErrorResponse(stun_msg, address,
STUN_ERROR_STALE_CREDENTIALS, STUN_ERROR_REASON_STALE_CREDENTIALS);
delete stun_msg;
return;
}
// Check for connectivity to this address. Create connections
// to this address across all local ports. First, add this as a new remote
// address
Candidate new_remote_candidate = *candidate;
new_remote_candidate.set_address(address);
// new_remote_candidate.set_protocol(port->protocol());
// This remote username exists. Now create connections using this candidate,
// and resort
if (CreateConnections(new_remote_candidate, port, true)) {
// Send the pinger a successful stun response.
port->SendBindingResponse(stun_msg, address);
// Update the list of connections since we just added another. We do this
// after sending the response since it could (in principle) delete the
// connection in question.
SortConnections();
} else {
// Hopefully this won't occur, because changing a destination address
// shouldn't cause a new connection to fail
ASSERT(false);
port->SendBindingErrorResponse(stun_msg, address, STUN_ERROR_SERVER_ERROR,
STUN_ERROR_REASON_SERVER_ERROR);
}
delete stun_msg;
}
void P2PTransportChannel::OnCandidate(const Candidate& candidate) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Create connections to this remote candidate.
CreateConnections(candidate, NULL, false);
// Resort the connections list, which may have new elements.
SortConnections();
}
// Creates connections from all of the ports that we care about to the given
// remote candidate. The return value is true if we created a connection from
// the origin port.
bool P2PTransportChannel::CreateConnections(const Candidate &remote_candidate,
Port* origin_port,
bool readable) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Add a new connection for this candidate to every port that allows such a
// connection (i.e., if they have compatible protocols) and that does not
// already have a connection to an equivalent candidate. We must be careful
// to make sure that the origin port is included, even if it was pruned,
// since that may be the only port that can create this connection.
bool created = false;
std::vector<Port *>::reverse_iterator it;
for (it = ports_.rbegin(); it != ports_.rend(); ++it) {
if (CreateConnection(*it, remote_candidate, origin_port, readable)) {
if (*it == origin_port)
created = true;
}
}
if ((origin_port != NULL) &&
std::find(ports_.begin(), ports_.end(), origin_port) == ports_.end()) {
if (CreateConnection(origin_port, remote_candidate, origin_port, readable))
created = true;
}
// Remember this remote candidate so that we can add it to future ports.
RememberRemoteCandidate(remote_candidate, origin_port);
return created;
}
// Setup a connection object for the local and remote candidate combination.
// And then listen to connection object for changes.
bool P2PTransportChannel::CreateConnection(Port* port,
const Candidate& remote_candidate,
Port* origin_port,
bool readable) {
// Look for an existing connection with this remote address. If one is not
// found, then we can create a new connection for this address.
Connection* connection = port->GetConnection(remote_candidate.address());
if (connection != NULL) {
// It is not legal to try to change any of the parameters of an existing
// connection; however, the other side can send a duplicate candidate.
if (!remote_candidate.IsEquivalent(connection->remote_candidate())) {
LOG(INFO) << "Attempt to change a remote candidate";
return false;
}
} else {
Port::CandidateOrigin origin = GetOrigin(port, origin_port);
// Don't create connection if this is a candidate we received in a
// message and we are not allowed to make outgoing connections.
if (origin == cricket::Port::ORIGIN_MESSAGE && incoming_only_)
return false;
connection = port->CreateConnection(remote_candidate, origin);
if (!connection)
return false;
connections_.push_back(connection);
connection->SignalReadPacket.connect(
this, &P2PTransportChannel::OnReadPacket);
connection->SignalStateChange.connect(
this, &P2PTransportChannel::OnConnectionStateChange);
connection->SignalDestroyed.connect(
this, &P2PTransportChannel::OnConnectionDestroyed);
LOG_J(LS_INFO, this) << "Created connection with origin=" << origin << ", ("
<< connections_.size() << " total)";
}
// If we are readable, it is because we are creating this in response to a
// ping from the other side. This will cause the state to become readable.
if (readable)
connection->ReceivedPing();
return true;
}
// Maintain our remote candidate list, adding this new remote one.
void P2PTransportChannel::RememberRemoteCandidate(
const Candidate& remote_candidate, Port* origin_port) {
// Remove any candidates whose generation is older than this one. The
// presence of a new generation indicates that the old ones are not useful.
uint32 i = 0;
while (i < remote_candidates_.size()) {
if (remote_candidates_[i].generation() < remote_candidate.generation()) {
LOG(INFO) << "Pruning candidate from old generation: "
<< remote_candidates_[i].address().ToString();
remote_candidates_.erase(remote_candidates_.begin() + i);
} else {
i += 1;
}
}
// Make sure this candidate is not a duplicate.
for (uint32 i = 0; i < remote_candidates_.size(); ++i) {
if (remote_candidates_[i].IsEquivalent(remote_candidate)) {
LOG(INFO) << "Duplicate candidate: "
<< remote_candidate.address().ToString();
return;
}
}
// Try this candidate for all future ports.
remote_candidates_.push_back(RemoteCandidate(remote_candidate, origin_port));
// We have some candidates from the other side, we are now serious about
// this connection. Let's do the StartGetAllPorts thing.
if (!pinging_started_) {
pinging_started_ = true;
for (size_t i = 0; i < allocator_sessions_.size(); ++i) {
if (!allocator_sessions_[i]->IsGettingAllPorts())
allocator_sessions_[i]->StartGetAllPorts();
}
}
}
// Send data to the other side, using our best connection
int P2PTransportChannel::SendPacket(const char *data, size_t len) {
// This can get called on any thread that is convenient to write from!
if (best_connection_ == NULL) {
error_ = EWOULDBLOCK;
return SOCKET_ERROR;
}
int sent = best_connection_->Send(data, len);
if (sent <= 0) {
ASSERT(sent < 0);
error_ = best_connection_->GetError();
}
return sent;
}
// Begin allocate (or immediately re-allocate, if MSG_ALLOCATE pending)
void P2PTransportChannel::Allocate() {
CancelPendingAllocate();
// Time for a new allocator, lets make sure we have a signalling channel
// to communicate candidates through first.
waiting_for_signaling_ = true;
SignalRequestSignaling();
}
// Cancels the pending allocate, if any.
void P2PTransportChannel::CancelPendingAllocate() {
thread()->Clear(this, MSG_ALLOCATE);
}
// Monitor connection states
void P2PTransportChannel::UpdateConnectionStates() {
uint32 now = talk_base::Time();
// We need to copy the list of connections since some may delete themselves
// when we call UpdateState.
for (uint32 i = 0; i < connections_.size(); ++i)
connections_[i]->UpdateState(now);
}
// Prepare for best candidate sorting
void P2PTransportChannel::RequestSort() {
if (!sort_dirty_) {
worker_thread_->Post(this, MSG_SORT);
sort_dirty_ = true;
}
}
// Sort the available connections to find the best one. We also monitor
// the number of available connections and the current state so that we
// can possibly kick off more allocators (for more connections).
void P2PTransportChannel::SortConnections() {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Make sure the connection states are up-to-date since this affects how they
// will be sorted.
UpdateConnectionStates();
// Any changes after this point will require a re-sort.
sort_dirty_ = false;
// Get a list of the networks that we are using.
std::set<talk_base::Network*> networks;
for (uint32 i = 0; i < connections_.size(); ++i)
networks.insert(connections_[i]->port()->network());
// Find the best alternative connection by sorting. It is important to note
// that amongst equal preference, writable connections, this will choose the
// one whose estimated latency is lowest. So it is the only one that we
// need to consider switching to.
ConnectionCompare cmp;
std::stable_sort(connections_.begin(), connections_.end(), cmp);
LOG(LS_VERBOSE) << "Sorting available connections:";
for (uint32 i = 0; i < connections_.size(); ++i) {
LOG(LS_VERBOSE) << connections_[i]->ToString();
}
Connection* top_connection = NULL;
if (connections_.size() > 0)
top_connection = connections_[0];
// If necessary, switch to the new choice.
if (ShouldSwitch(best_connection_, top_connection))
SwitchBestConnectionTo(top_connection);
// We can prune any connection for which there is a writable connection on
// the same network with better or equal prefences. We leave those with
// better preference just in case they become writable later (at which point,
// we would prune out the current best connection). We leave connections on
// other networks because they may not be using the same resources and they
// may represent very distinct paths over which we can switch.
std::set<talk_base::Network*>::iterator network;
for (network = networks.begin(); network != networks.end(); ++network) {
Connection* primier = GetBestConnectionOnNetwork(*network);
if (!primier || (primier->write_state() != Connection::STATE_WRITABLE))
continue;
for (uint32 i = 0; i < connections_.size(); ++i) {
if ((connections_[i] != primier) &&
(connections_[i]->port()->network() == *network) &&
(CompareConnectionCandidates(primier, connections_[i]) >= 0)) {
connections_[i]->Prune();
}
}
}
// Count the number of connections in the various states.
int writable = 0;
int write_connect = 0;
int write_timeout = 0;
for (uint32 i = 0; i < connections_.size(); ++i) {
switch (connections_[i]->write_state()) {
case Connection::STATE_WRITABLE:
++writable;
break;
case Connection::STATE_WRITE_CONNECT:
++write_connect;
break;
case Connection::STATE_WRITE_TIMEOUT:
++write_timeout;
break;
default:
ASSERT(false);
}
}
if (writable > 0) {
HandleWritable();
} else if (write_connect > 0) {
HandleNotWritable();
} else {
HandleAllTimedOut();
}
// Update the state of this channel. This method is called whenever the
// state of any connection changes, so this is a good place to do this.
UpdateChannelState();
// Notify of connection state change
SignalConnectionMonitor(this);
}
// Track the best connection, and let listeners know
void P2PTransportChannel::SwitchBestConnectionTo(Connection* conn) {
// Note: if conn is NULL, the previous best_connection_ has been destroyed,
// so don't use it.
// use it.
Connection* old_best_connection = best_connection_;
best_connection_ = conn;
if (best_connection_) {
if (old_best_connection) {
LOG_J(LS_INFO, this) << "Previous best connection: "
<< old_best_connection->ToString();
}
LOG_J(LS_INFO, this) << "New best connection: "
<< best_connection_->ToString();
SignalRouteChange(this, best_connection_->remote_candidate());
} else {
LOG_J(LS_INFO, this) << "No best connection";
}
}
void P2PTransportChannel::UpdateChannelState() {
// The Handle* functions already set the writable state. We'll just double-
// check it here.
bool writable = ((best_connection_ != NULL) &&
(best_connection_->write_state() ==
Connection::STATE_WRITABLE));
ASSERT(writable == this->writable());
if (writable != this->writable())
LOG(LS_ERROR) << "UpdateChannelState: writable state mismatch";
bool readable = false;
for (uint32 i = 0; i < connections_.size(); ++i) {
if (connections_[i]->read_state() == Connection::STATE_READABLE)
readable = true;
}
set_readable(readable);
}
// We checked the status of our connections and we had at least one that
// was writable, go into the writable state.
void P2PTransportChannel::HandleWritable() {
//
// One or more connections writable!
//
if (!writable()) {
for (uint32 i = 0; i < allocator_sessions_.size(); ++i) {
if (allocator_sessions_[i]->IsGettingAllPorts()) {
allocator_sessions_[i]->StopGetAllPorts();
}
}
// Stop further allocations.
CancelPendingAllocate();
}
// We're writable, obviously we aren't timed out
was_writable_ = true;
was_timed_out_ = false;
set_writable(true);
}
// We checked the status of our connections and we didn't have any that
// were writable, go into the connecting state (kick off a new allocator
// session).
void P2PTransportChannel::HandleNotWritable() {
//
// No connections are writable but not timed out!
//
if (was_writable_) {
// If we were writable, let's kick off an allocator session immediately
was_writable_ = false;
Allocate();
}
// We were connecting, obviously not ALL timed out.
was_timed_out_ = false;
set_writable(false);
}
// We checked the status of our connections and not only weren't they writable
// but they were also timed out, we really need a new allocator.
void P2PTransportChannel::HandleAllTimedOut() {
//
// No connections... all are timed out!
//
if (!was_timed_out_) {
// We weren't timed out before, so kick off an allocator now (we'll still
// be in the fully timed out state until the allocator actually gives back
// new ports)
Allocate();
}
// NOTE: we start was_timed_out_ in the true state so that we don't get
// another allocator created WHILE we are in the process of building up
// our first allocator.
was_timed_out_ = true;
was_writable_ = false;
set_writable(false);
}
// If we have a best connection, return it, otherwise return top one in the
// list (later we will mark it best).
Connection* P2PTransportChannel::GetBestConnectionOnNetwork(
talk_base::Network* network) {
// If the best connection is on this network, then it wins.
if (best_connection_ && (best_connection_->port()->network() == network))
return best_connection_;
// Otherwise, we return the top-most in sorted order.
for (uint32 i = 0; i < connections_.size(); ++i) {
if (connections_[i]->port()->network() == network)
return connections_[i];
}
return NULL;
}
// Handle any queued up requests
void P2PTransportChannel::OnMessage(talk_base::Message *pmsg) {
if (pmsg->message_id == MSG_SORT)
OnSort();
else if (pmsg->message_id == MSG_PING)
OnPing();
else if (pmsg->message_id == MSG_ALLOCATE)
Allocate();
else
ASSERT(false);
}
// Handle queued up sort request
void P2PTransportChannel::OnSort() {
// Resort the connections based on the new statistics.
SortConnections();
}
// Handle queued up ping request
void P2PTransportChannel::OnPing() {
// Make sure the states of the connections are up-to-date (since this affects
// which ones are pingable).
UpdateConnectionStates();
// Find the oldest pingable connection and have it do a ping.
Connection* conn = FindNextPingableConnection();
if (conn)
conn->Ping(talk_base::Time());
// Post ourselves a message to perform the next ping.
uint32 delay = writable() ? WRITABLE_DELAY : UNWRITABLE_DELAY;
thread()->PostDelayed(delay, this, MSG_PING);
}
// Is the connection in a state for us to even consider pinging the other side?
bool P2PTransportChannel::IsPingable(Connection* conn) {
// An unconnected connection cannot be written to at all, so pinging is out
// of the question.
if (!conn->connected())
return false;
if (writable()) {
// If we are writable, then we only want to ping connections that could be
// better than this one, i.e., the ones that were not pruned.
return (conn->write_state() != Connection::STATE_WRITE_TIMEOUT);
} else {
// If we are not writable, then we need to try everything that might work.
// This includes both connections that do not have write timeout as well as
// ones that do not have read timeout. A connection could be readable but
// be in write-timeout if we pruned it before. Since the other side is
// still pinging it, it very well might still work.
return (conn->write_state() != Connection::STATE_WRITE_TIMEOUT) ||
(conn->read_state() != Connection::STATE_READ_TIMEOUT);
}
}
// Returns the next pingable connection to ping. This will be the oldest
// pingable connection unless we have a writable connection that is past the
// maximum acceptable ping delay.
Connection* P2PTransportChannel::FindNextPingableConnection() {
uint32 now = talk_base::Time();
if (best_connection_ &&
(best_connection_->write_state() == Connection::STATE_WRITABLE) &&
(best_connection_->last_ping_sent()
+ MAX_CURRENT_WRITABLE_DELAY <= now)) {
return best_connection_;
}
Connection* oldest_conn = NULL;
uint32 oldest_time = 0xFFFFFFFF;
for (uint32 i = 0; i < connections_.size(); ++i) {
if (IsPingable(connections_[i])) {
if (connections_[i]->last_ping_sent() < oldest_time) {
oldest_time = connections_[i]->last_ping_sent();
oldest_conn = connections_[i];
}
}
}
return oldest_conn;
}
// return the number of "pingable" connections
uint32 P2PTransportChannel::NumPingableConnections() {
uint32 count = 0;
for (uint32 i = 0; i < connections_.size(); ++i) {
if (IsPingable(connections_[i]))
count += 1;
}
return count;
}
// When a connection's state changes, we need to figure out who to use as
// the best connection again. It could have become usable, or become unusable.
void P2PTransportChannel::OnConnectionStateChange(Connection *connection) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// We have to unroll the stack before doing this because we may be changing
// the state of connections while sorting.
RequestSort();
}
// When a connection is removed, edit it out, and then update our best
// connection.
void P2PTransportChannel::OnConnectionDestroyed(Connection *connection) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Note: the previous best_connection_ may be destroyed by now, so don't
// use it.
// Remove this connection from the list.
std::vector<Connection*>::iterator iter =
std::find(connections_.begin(), connections_.end(), connection);
ASSERT(iter != connections_.end());
connections_.erase(iter);
LOG_J(LS_INFO, this) << "Removed connection ("
<< static_cast<int>(connections_.size()) << " remaining)";
// If this is currently the best connection, then we need to pick a new one.
// The call to SortConnections will pick a new one. It looks at the current
// best connection in order to avoid switching between fairly similar ones.
// Since this connection is no longer an option, we can just set best to NULL
// and re-choose a best assuming that there was no best connection.
if (best_connection_ == connection) {
SwitchBestConnectionTo(NULL);
RequestSort();
}
}
// When a port is destroyed remove it from our list of ports to use for
// connection attempts.
void P2PTransportChannel::OnPortDestroyed(Port* port) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Remove this port from the list (if we didn't drop it already).
std::vector<Port*>::iterator iter =
std::find(ports_.begin(), ports_.end(), port);
if (iter != ports_.end())
ports_.erase(iter);
LOG(INFO) << "Removed port from p2p socket: "
<< static_cast<int>(ports_.size()) << " remaining";
}
// We data is available, let listeners know
void P2PTransportChannel::OnReadPacket(Connection *connection,
const char *data, size_t len) {
ASSERT(worker_thread_ == talk_base::Thread::Current());
// Let the client know of an incoming packet
SignalReadPacket(this, data, len);
}
// Set options on ourselves is simply setting options on all of our available
// port objects.
int P2PTransportChannel::SetOption(talk_base::Socket::Option opt, int value) {
OptionMap::iterator it = options_.find(opt);
if (it == options_.end()) {
options_.insert(std::make_pair(opt, value));
} else if (it->second == value) {
return 0;
} else {
it->second = value;
}
for (uint32 i = 0; i < ports_.size(); ++i) {
int val = ports_[i]->SetOption(opt, value);
if (val < 0) {
// Because this also occurs deferred, probably no point in reporting an
// error
LOG(WARNING) << "SetOption(" << opt << ", " << value << ") failed: "
<< ports_[i]->GetError();
}
}
return 0;
}
// When the signalling channel is ready, we can really kick off the allocator
void P2PTransportChannel::OnSignalingReady() {
if (waiting_for_signaling_) {
waiting_for_signaling_ = false;
AddAllocatorSession(allocator_->CreateSession(name(), content_type()));
thread()->PostDelayed(kAllocatePeriod, this, MSG_ALLOCATE);
}
}
} // namespace cricket