size_t Connection::fill_packet(Packet_ptr packet, const char* buffer, size_t n, Seq seq) {
Expects(!packet->has_tcp_data());
auto written = packet->fill(buffer, std::min(n, (size_t)SMSS()));
packet->set_seq(seq).set_ack(cb.RCV.NXT).set_flag(ACK);
Ensures(written <= n);
return written;
}
void Listener::segment_arrived(Packet_ptr packet) {
debug2("<Listener::segment_arrived> Received packet: %s\n",
packet->to_string().c_str());
auto it = std::find_if(syn_queue_.begin(), syn_queue_.end(),
[dest = packet->source()]
(Connection_ptr conn) {
return conn->remote() == dest;
});
// if it's an reply to any of our half-open connections
if(it != syn_queue_.end())
{
auto conn = *it;
debug("<Listener::segment_arrived> Found packet receiver: %s\n",
conn->to_string().c_str());
conn->segment_arrived(std::move(packet));
debug2("<Listener::segment_arrived> Connection done handling segment\n");
return;
}
// if it's a new attempt (SYN)
else
{
// don't waste time if the packet does not have SYN
if(UNLIKELY(not packet->isset(SYN) or packet->has_tcp_data()))
{
host_.send_reset(*packet);
return;
}
// Stat increment number of connection attempts
host_.connection_attempts_++;
// if we don't like this client, do nothing
if(UNLIKELY(on_accept_(packet->source()) == false))
return;
// remove oldest connection if queue is full
debug2("<Listener::segment_arrived> SynQueue: %u\n", syn_queue_.size());
// SYN queue is full
if(syn_queue_.size() >= host_.max_syn_backlog())
{
debug2("<Listener::segment_arrived> Queue is full\n");
Expects(not syn_queue_.empty());
debug("<Listener::segment_arrived> Connection %s dropped to make room for new connection\n",
syn_queue_.back()->to_string().c_str());
syn_queue_.pop_back();
}
auto& conn = *(syn_queue_.emplace(
syn_queue_.cbegin(),
std::make_shared<Connection>(host_, packet->destination(), packet->source(), ConnectCallback{this, &Listener::connected})
)
);
conn->_on_cleanup({this, &Listener::remove});
// Open connection
conn->open(false);
Ensures(conn->is_listening());
debug("<Listener::segment_arrived> Connection %s created\n",
conn->to_string().c_str());
conn->segment_arrived(std::move(packet));
debug2("<Listener::segment_arrived> Connection done handling segment\n");
return;
}
debug2("<Listener::segment_arrived> No receipent\n");
}