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refactor and comment

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This commit is contained in:
ridethepig 2023-02-17 16:22:34 +00:00
parent 6dd84564cf
commit b60b909a19
2 changed files with 70 additions and 60 deletions
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70
libsponge/tcp_connection.cc
View File

@ -21,35 +21,30 @@ size_t TCPConnection::unassembled_bytes() const { return _receiver.unassembled_b
size_t TCPConnection::time_since_last_segment_received() const { return _time_last_segment_received; }
void TCPConnection::segment_received(const TCPSegment &seg) {
if (!_active)
return;
// god knows whether it should be active or not initially
_time_last_segment_received = 0;
if (seg.header().rst) {
_sender.stream_in().set_error();
_receiver.stream_out().set_error();
_active = false;
_set_rst();
return;
}
bool send_ack = seg.length_in_sequence_space();
_receiver.segment_received(seg);
if (seg.header().ack && _receiver.ackno().has_value()) {
// filter out acks before syn
_sender.ack_received(seg.header().ackno, seg.header().win);
// _sender.fill_window();
if (!_sender.segments_out().empty()) send_ack = false;
// _sender.fill_window(); !! This should be done in ack_received
}
// std::cerr << seg.header().to_string();
// std::cerr << _receiver.stream_out().bytes_written() << " " << _receiver.unassembled_bytes() << std::endl;
// std::cerr << seg.payload().size() << std::endl;
if (send_ack) {
_sender.fill_window();
// if the inbound seg has len it should be responded
// except that ack_received() has send a seg, so no more is needed
if (seg.length_in_sequence_space() && _sender.segments_out().empty()) {
_sender.fill_window(); // it is necessary to repond to SYN with a SYNACK
if (_sender.segments_out().empty()) {
_sender.send_empty_segment();
}
}
_send_all();
// TODO: Keep-alive but it seems to be use
// recver in FIN_RECV
// sender in SYN_ACKED
if (_receiver.stream_out().input_ended() && !_sender.stream_in().eof()) {
_linger_after_streams_finish = false;
}
@ -70,30 +65,19 @@ void TCPConnection::tick(const size_t ms_since_last_tick) {
_time_last_segment_received += ms_since_last_tick;
_sender.tick(ms_since_last_tick);
if (_sender.consecutive_retransmissions() > TCPConfig::MAX_RETX_ATTEMPTS) {
_sender.send_empty_segment();
auto &seg_queue = _sender.segments_out();
auto seg = seg_queue.front();
seg_queue.pop();
if (_receiver.ackno().has_value()) {
seg.header().ack = true;
seg.header().ackno = _receiver.ackno().value();
}
seg.header().win = _receiver.window_size();
seg.header().rst = true;
_segments_out.push(seg);
_sender.stream_in().set_error();
_receiver.stream_out().set_error();
_active = false;
_send_rst();
_set_rst();
return;
}
_send_all();
if (!_sender.bytes_in_flight() && _sender.stream_in().eof() && _receiver.stream_out().input_ended() &&
!_receiver.unassembled_bytes()) {
if (!_linger_after_streams_finish) {
_active = false;
} else if (_time_last_segment_received >= 10 * _cfg.rt_timeout) {
_active = false;
}
// actually, this long if could be represented by TCP states
// for sender, it is the FIN_ACKED state
// for recver, it is the FIN_RECV state
// and plus linger
if ((!_sender.bytes_in_flight() && _sender.stream_in().eof()) &&
(_receiver.stream_out().input_ended() && !_receiver.unassembled_bytes()) &&
(!_linger_after_streams_finish || _time_last_segment_received >= 10 * _cfg.rt_timeout)) {
_active = false;
}
}
@ -112,20 +96,8 @@ TCPConnection::~TCPConnection() {
try {
if (active()) {
cerr << "Warning: Unclean shutdown of TCPConnection\n";
_sender.send_empty_segment();
auto &seg_queue = _sender.segments_out();
auto seg = seg_queue.front();
seg_queue.pop();
if (_receiver.ackno().has_value()) {
seg.header().ack = true;
seg.header().ackno = _receiver.ackno().value();
}
seg.header().win = _receiver.window_size();
seg.header().rst = true;
_segments_out.push(seg);
_sender.stream_in().set_error();
_receiver.stream_out().set_error();
_active = false;
_send_rst();
_set_rst();
// Your code here: need to send a RST segment to the peer
}
} catch (const exception &e) {

60
libsponge/tcp_connection.hh
View File

@ -5,6 +5,7 @@
#include "tcp_receiver.hh"
#include "tcp_sender.hh"
#include "tcp_state.hh"
#include <algorithm>
#include <limits>
@ -22,21 +23,58 @@ class TCPConnection {
//! for 10 * _cfg.rt_timeout milliseconds after both streams have ended,
//! in case the remote TCPConnection doesn't know we've received its whole stream?
bool _linger_after_streams_finish{true};
//! Private state for time_since_last_segment_received()
size_t _time_last_segment_received{0};
//! Private state for active()
bool _active{true};
//!\name Internal helper procedures
//!@{
//!\brief Send all available outbound segments
void _send_all() {
auto &seg_queue = _sender.segments_out();
while (!seg_queue.empty()) {
auto seg = seg_queue.front();
seg_queue.pop();
if (_receiver.ackno().has_value()) {
seg.header().ack = true;
seg.header().ackno = _receiver.ackno().value();
}
seg.header().win = std::min(_receiver.window_size(), static_cast<size_t>(std::numeric_limits<uint16_t>::max()));
_segments_out.push(seg);
}
auto &seg_queue = _sender.segments_out();
while (!seg_queue.empty()) {
auto seg = seg_queue.front();
seg_queue.pop();
if (_receiver.ackno().has_value()) {
seg.header().ack = true;
seg.header().ackno = _receiver.ackno().value();
}
seg.header().win =
std::min(_receiver.window_size(), static_cast<size_t>(std::numeric_limits<uint16_t>::max()));
_segments_out.push(seg);
}
}
//!\brief Deprecate all other packets in the queue, and send a RST segment
void _send_rst() {
auto &seg_queue = _sender.segments_out();
while (!seg_queue.empty()) {
seg_queue.pop();
}
_sender.send_empty_segment();
auto seg = seg_queue.front();
seg_queue.pop();
if (_receiver.ackno().has_value()) {
seg.header().ack = true;
seg.header().ackno = _receiver.ackno().value();
}
seg.header().win = _receiver.window_size();
seg.header().rst = true;
_segments_out.push(seg);
}
//!\brief Set connection to Dead State
void _set_rst() {
_sender.stream_in().set_error();
_receiver.stream_out().set_error();
_active = false;
}
//!@}
public:
//! \name "Input" interface for the writer
//!@{