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RetroArch/network/netplay/netplay_sync.c
Gregor Richards fb3c35dc9f Handle forwarding of netplay state demotions correctly. 
Netplay state demotions, i.e. changes from playing to spectating or
disconnected states, could cause chain disconnections of all other
clients. This was due to a bug in when MODE change messages were sent.
Clients rely on the server sending all messages in its own order, and as
a consequence, the server typically holds messages for retransmission
until they can be retransmitted at the correct time. MODE messages were
not held, so could be sent early. When they were sent early, this caused
other clients to panic and disconnect.

A smaller but much stupider secondary bug was also fixed, in which the
first connection could be dropped due simply to writing connections[0]
instead of connections[i] somewhere.
2017-06-06 21:35:09 -04:00

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/* RetroArch - A frontend for libretro.
* Copyright (C) 2010-2014 - Hans-Kristian Arntzen
* Copyright (C) 2011-2017 - Daniel De Matteis
* Copyright (C) 2016-2017 - Gregor Richards
*
* RetroArch is free software: you can redistribute it and/or modify it under the terms
* of the GNU General Public License as published by the Free Software Found-
* ation, either version 3 of the License, or (at your option) any later version.
*
* RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with RetroArch.
* If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <boolean.h>
#include "netplay_private.h"
#include "../../autosave.h"
#include "../../driver.h"
#include "../../input/input_driver.h"
#if 0
#define DEBUG_NONDETERMINISTIC_CORES
#endif
/**
* netplay_update_unread_ptr
*
* Update the global unread_ptr and unread_frame_count to correspond to the
* earliest unread frame count of any connected player
*/
void netplay_update_unread_ptr(netplay_t *netplay)
{
if (netplay->is_server && !netplay->connected_players)
{
/* Nothing at all to read! */
netplay->unread_ptr = netplay->self_ptr;
netplay->unread_frame_count = netplay->self_frame_count;
}
else
{
size_t new_unread_ptr = 0;
uint32_t new_unread_frame_count = (uint32_t) -1;
uint32_t player;
for (player = 0; player < MAX_USERS; player++)
{
if (!(netplay->connected_players & (1<<player))) continue;
if ((netplay->connected_slaves & (1<<player))) continue;
if (netplay->read_frame_count[player] < new_unread_frame_count)
{
new_unread_ptr = netplay->read_ptr[player];
new_unread_frame_count = netplay->read_frame_count[player];
}
}
if (!netplay->is_server && netplay->server_frame_count < new_unread_frame_count)
{
new_unread_ptr = netplay->server_ptr;
new_unread_frame_count = netplay->server_frame_count;
}
if (new_unread_frame_count != (uint32_t) -1)
{
netplay->unread_ptr = new_unread_ptr;
netplay->unread_frame_count = new_unread_frame_count;
}
else
{
netplay->unread_ptr = netplay->self_ptr;
netplay->unread_frame_count = netplay->self_frame_count;
}
}
}
/**
* netplay_simulate_input
* @netplay : pointer to netplay object
* @sim_ptr : frame index for which to simulate input
* @resim : are we resimulating, or simulating this frame for the
* first time?
*
* "Simulate" input by assuming it hasn't changed since the last read input.
*/
void netplay_simulate_input(netplay_t *netplay, size_t sim_ptr, bool resim)
{
uint32_t player;
size_t prev;
struct delta_frame *simframe, *pframe;
simframe = &netplay->buffer[sim_ptr];
for (player = 0; player < MAX_USERS; player++)
{
if (!(netplay->connected_players & (1<<player))) continue;
if (simframe->have_real[player]) continue;
prev = PREV_PTR(netplay->read_ptr[player]);
pframe = &netplay->buffer[prev];
if (resim)
{
/* In resimulation mode, we only copy the buttons. The reason for this
* is nonobvious:
*
* If we resimulated nothing, then the /duration/ with which any input
* was pressed would be approximately correct, since the original
* simulation came in as the input came in, but the /number of times/
* the input was pressed would be wrong, as there would be an
* advancing wavefront of real data overtaking the simulated data
* (which is really just real data offset by some frames).
*
* That's acceptable for arrows in most situations, since the amount
* you move is tied to the duration, but unacceptable for buttons,
* which will seem to jerkily be pressed numerous times with those
* wavefronts.
*/
const uint32_t keep = (1U<<RETRO_DEVICE_ID_JOYPAD_UP) |
(1U<<RETRO_DEVICE_ID_JOYPAD_DOWN) |
(1U<<RETRO_DEVICE_ID_JOYPAD_LEFT) |
(1U<<RETRO_DEVICE_ID_JOYPAD_RIGHT);
uint32_t sim_state = simframe->simulated_input_state[player][0] & keep;
sim_state |= pframe->real_input_state[player][0] & ~keep;
simframe->simulated_input_state[player][0] = sim_state;
}
else
{
memcpy(simframe->simulated_input_state[player],
pframe->real_input_state[player],
WORDS_PER_INPUT * sizeof(uint32_t));
}
}
}
static void netplay_handle_frame_hash(netplay_t *netplay, struct delta_frame *delta)
{
if (netplay->is_server)
{
if (netplay->check_frames &&
delta->frame % abs(netplay->check_frames) == 0)
{
delta->crc = netplay_delta_frame_crc(netplay, delta);
netplay_cmd_crc(netplay, delta);
}
}
else if (delta->crc && netplay->crcs_valid)
{
/* We have a remote CRC, so check it */
uint32_t local_crc = netplay_delta_frame_crc(netplay, delta);
if (local_crc != delta->crc)
{
if (!netplay->crc_validity_checked)
{
/* If the very first check frame is wrong, they probably just don't
* work */
netplay->crcs_valid = false;
}
else if (netplay->crcs_valid)
{
/* Fix this! */
if (netplay->check_frames < 0)
{
/* Just report */
RARCH_ERR("Netplay CRCs mismatch!\n");
}
else
{
netplay_cmd_request_savestate(netplay);
}
}
}
else if (!netplay->crc_validity_checked)
{
netplay->crc_validity_checked = true;
}
}
}
/**
* netplay_sync_pre_frame
* @netplay : pointer to netplay object
*
* Pre-frame for Netplay synchronization.
*/
bool netplay_sync_pre_frame(netplay_t *netplay)
{
retro_ctx_serialize_info_t serial_info;
if (netplay_delta_frame_ready(netplay, &netplay->buffer[netplay->run_ptr], netplay->run_frame_count))
{
serial_info.data_const = NULL;
serial_info.data = netplay->buffer[netplay->run_ptr].state;
serial_info.size = netplay->state_size;
memset(serial_info.data, 0, serial_info.size);
if ((netplay->quirks & NETPLAY_QUIRK_INITIALIZATION) || netplay->run_frame_count == 0)
{
/* Don't serialize until it's safe */
}
else if (!(netplay->quirks & NETPLAY_QUIRK_NO_SAVESTATES) && core_serialize(&serial_info))
{
if (netplay->force_send_savestate && !netplay->stall && !netplay->remote_paused)
{
/* Bring our running frame and input frames into parity so we don't
* send old info */
if (netplay->run_ptr != netplay->self_ptr)
{
memcpy(netplay->buffer[netplay->self_ptr].state,
netplay->buffer[netplay->run_ptr].state,
netplay->state_size);
netplay->run_ptr = netplay->self_ptr;
netplay->run_frame_count = netplay->self_frame_count;
}
/* Send this along to the other side */
serial_info.data_const = netplay->buffer[netplay->run_ptr].state;
netplay_load_savestate(netplay, &serial_info, false);
netplay->force_send_savestate = false;
}
}
else
{
/* If the core can't serialize properly, we must stall for the
* remote input on EVERY frame, because we can't recover */
netplay->quirks |= NETPLAY_QUIRK_NO_SAVESTATES;
netplay->stateless_mode = true;
}
/* If we can't transmit savestates, we must stall until the client is ready */
if (netplay->run_frame_count > 0 &&
(netplay->quirks & (NETPLAY_QUIRK_NO_SAVESTATES|NETPLAY_QUIRK_NO_TRANSMISSION)) &&
(netplay->connections_size == 0 || !netplay->connections[0].active ||
netplay->connections[0].mode < NETPLAY_CONNECTION_CONNECTED))
netplay->stall = NETPLAY_STALL_NO_CONNECTION;
}
if (netplay->is_server)
{
fd_set fds;
struct timeval tmp_tv = {0};
int new_fd;
struct sockaddr_storage their_addr;
socklen_t addr_size;
struct netplay_connection *connection;
size_t connection_num;
/* Check for a connection */
FD_ZERO(&fds);
FD_SET(netplay->listen_fd, &fds);
if (socket_select(netplay->listen_fd + 1, &fds, NULL, NULL, &tmp_tv) > 0 &&
FD_ISSET(netplay->listen_fd, &fds))
{
addr_size = sizeof(their_addr);
new_fd = accept(netplay->listen_fd, (struct sockaddr*)&their_addr, &addr_size);
if (new_fd < 0)
{
RARCH_ERR("%s\n", msg_hash_to_str(MSG_NETPLAY_FAILED));
goto process;
}
/* Set the socket nonblocking */
if (!socket_nonblock(new_fd))
{
/* Catastrophe! */
socket_close(new_fd);
goto process;
}
#if defined(IPPROTO_TCP) && defined(TCP_NODELAY)
{
int flag = 1;
if (setsockopt(new_fd, IPPROTO_TCP, TCP_NODELAY,
#ifdef _WIN32
(const char*)
#else
(const void*)
#endif
&flag,
sizeof(int)) < 0)
RARCH_WARN("Could not set netplay TCP socket to nodelay. Expect jitter.\n");
}
#endif
#if defined(F_SETFD) && defined(FD_CLOEXEC)
/* Don't let any inherited processes keep open our port */
if (fcntl(new_fd, F_SETFD, FD_CLOEXEC) < 0)
RARCH_WARN("Cannot set Netplay port to close-on-exec. It may fail to reopen if the client disconnects.\n");
#endif
/* Allocate a connection */
for (connection_num = 0; connection_num < netplay->connections_size; connection_num++)
if (!netplay->connections[connection_num].active &&
netplay->connections[connection_num].mode != NETPLAY_CONNECTION_DELAYED_DISCONNECT) break;
if (connection_num == netplay->connections_size)
{
if (connection_num == 0)
{
netplay->connections = (struct netplay_connection*)malloc(sizeof(struct netplay_connection));
if (netplay->connections == NULL)
{
socket_close(new_fd);
goto process;
}
netplay->connections_size = 1;
}
else
{
size_t new_connections_size = netplay->connections_size * 2;
struct netplay_connection *new_connections = (struct netplay_connection*)
realloc(netplay->connections,
new_connections_size*sizeof(struct netplay_connection));
if (new_connections == NULL)
{
socket_close(new_fd);
goto process;
}
memset(new_connections + netplay->connections_size, 0,
netplay->connections_size * sizeof(struct netplay_connection));
netplay->connections = new_connections;
netplay->connections_size = new_connections_size;
}
}
connection = &netplay->connections[connection_num];
/* Set it up */
memset(connection, 0, sizeof(*connection));
connection->active = true;
connection->fd = new_fd;
connection->mode = NETPLAY_CONNECTION_INIT;
if (!netplay_init_socket_buffer(&connection->send_packet_buffer,
netplay->packet_buffer_size) ||
!netplay_init_socket_buffer(&connection->recv_packet_buffer,
netplay->packet_buffer_size))
{
if (connection->send_packet_buffer.data)
netplay_deinit_socket_buffer(&connection->send_packet_buffer);
connection->active = false;
socket_close(new_fd);
goto process;
}
netplay_handshake_init_send(netplay, connection);
}
}
process:
netplay->can_poll = true;
input_poll_net();
return (netplay->stall != NETPLAY_STALL_NO_CONNECTION);
}
/**
* netplay_sync_post_frame
* @netplay : pointer to netplay object
*
* Post-frame for Netplay synchronization.
* We check if we have new input and replay from recorded input.
*/
void netplay_sync_post_frame(netplay_t *netplay, bool stalled)
{
uint32_t lo_frame_count, hi_frame_count;
/* Unless we're stalling, we've just finished running a frame */
if (!stalled)
{
netplay->run_ptr = NEXT_PTR(netplay->run_ptr);
netplay->run_frame_count++;
}
/* We've finished an input frame even if we're stalling */
if ((!stalled || netplay->stall == NETPLAY_STALL_INPUT_LATENCY) &&
netplay->self_frame_count < netplay->run_frame_count + netplay->input_latency_frames)
{
netplay->self_ptr = NEXT_PTR(netplay->self_ptr);
netplay->self_frame_count++;
}
/* Only relevant if we're connected and not in a desynching operation */
if ((netplay->is_server && !netplay->connected_players) ||
(netplay->self_mode < NETPLAY_CONNECTION_CONNECTED) ||
(netplay->desync))
{
netplay->other_frame_count = netplay->self_frame_count;
netplay->other_ptr = netplay->self_ptr;
/* FIXME: Duplication */
if (netplay->catch_up)
{
netplay->catch_up = false;
input_driver_unset_nonblock_state();
driver_set_nonblock_state();
}
return;
}
/* Reset if it was requested */
if (netplay->force_reset)
{
core_reset();
netplay->force_reset = false;
}
#ifndef DEBUG_NONDETERMINISTIC_CORES
if (!netplay->force_rewind)
{
/* Skip ahead if we predicted correctly.
* Skip until our simulation failed. */
while (netplay->other_frame_count < netplay->unread_frame_count &&
netplay->other_frame_count < netplay->run_frame_count)
{
struct delta_frame *ptr = &netplay->buffer[netplay->other_ptr];
size_t i;
for (i = 0; i < MAX_USERS; i++)
{
if (memcmp(ptr->simulated_input_state[i], ptr->real_input_state[i],
sizeof(ptr->real_input_state[i])) != 0
&& !ptr->used_real[i])
break;
}
if (i != MAX_USERS) break;
netplay_handle_frame_hash(netplay, ptr);
netplay->other_ptr = NEXT_PTR(netplay->other_ptr);
netplay->other_frame_count++;
}
}
#endif
/* Now replay the real input if we've gotten ahead of it */
if (netplay->force_rewind ||
(netplay->other_frame_count < netplay->unread_frame_count &&
netplay->other_frame_count < netplay->run_frame_count))
{
retro_ctx_serialize_info_t serial_info;
/* Replay frames. */
netplay->is_replay = true;
netplay->replay_ptr = netplay->other_ptr;
netplay->replay_frame_count = netplay->other_frame_count;
if (netplay->quirks & NETPLAY_QUIRK_INITIALIZATION)
/* Make sure we're initialized before we start loading things */
netplay_wait_and_init_serialization(netplay);
serial_info.data = NULL;
serial_info.data_const = netplay->buffer[netplay->replay_ptr].state;
serial_info.size = netplay->state_size;
if (!core_unserialize(&serial_info))
{
RARCH_ERR("Netplay savestate loading failed: Prepare for desync!\n");
}
while (netplay->replay_frame_count < netplay->run_frame_count)
{
retro_time_t start, tm;
struct delta_frame *ptr = &netplay->buffer[netplay->replay_ptr];
serial_info.data = ptr->state;
serial_info.size = netplay->state_size;
serial_info.data_const = NULL;
start = cpu_features_get_time_usec();
/* Remember the current state */
memset(serial_info.data, 0, serial_info.size);
core_serialize(&serial_info);
if (netplay->replay_frame_count < netplay->unread_frame_count)
netplay_handle_frame_hash(netplay, ptr);
/* Re-simulate this frame's input */
netplay_simulate_input(netplay, netplay->replay_ptr, true);
autosave_lock();
core_run();
autosave_unlock();
netplay->replay_ptr = NEXT_PTR(netplay->replay_ptr);
netplay->replay_frame_count++;
#ifdef DEBUG_NONDETERMINISTIC_CORES
if (ptr->have_remote && netplay_delta_frame_ready(netplay, &netplay->buffer[netplay->replay_ptr], netplay->replay_frame_count))
{
RARCH_LOG("PRE %u: %X\n", netplay->replay_frame_count-1, netplay_delta_frame_crc(netplay, ptr));
if (netplay->is_server)
RARCH_LOG("INP %X %X\n", ptr->real_input_state[0], ptr->self_state[0]);
else
RARCH_LOG("INP %X %X\n", ptr->self_state[0], ptr->real_input_state[0]);
ptr = &netplay->buffer[netplay->replay_ptr];
serial_info.data = ptr->state;
memset(serial_info.data, 0, serial_info.size);
core_serialize(&serial_info);
RARCH_LOG("POST %u: %X\n", netplay->replay_frame_count-1, netplay_delta_frame_crc(netplay, ptr));
}
#endif
/* Get our time window */
tm = cpu_features_get_time_usec() - start;
netplay->frame_run_time_sum -= netplay->frame_run_time[netplay->frame_run_time_ptr];
netplay->frame_run_time[netplay->frame_run_time_ptr] = tm;
netplay->frame_run_time_sum += tm;
netplay->frame_run_time_ptr++;
if (netplay->frame_run_time_ptr >= NETPLAY_FRAME_RUN_TIME_WINDOW)
netplay->frame_run_time_ptr = 0;
}
/* Average our time */
netplay->frame_run_time_avg = netplay->frame_run_time_sum / NETPLAY_FRAME_RUN_TIME_WINDOW;
if (netplay->unread_frame_count < netplay->run_frame_count)
{
netplay->other_ptr = netplay->unread_ptr;
netplay->other_frame_count = netplay->unread_frame_count;
}
else
{
netplay->other_ptr = netplay->run_ptr;
netplay->other_frame_count = netplay->run_frame_count;
}
netplay->is_replay = false;
netplay->force_rewind = false;
}
if (netplay->is_server)
{
uint32_t player;
lo_frame_count = hi_frame_count = netplay->unread_frame_count;
/* Look for players that are ahead of us */
for (player = 0; player < MAX_USERS; player++)
{
if (!(netplay->connected_players & (1<<player))) continue;
if (netplay->read_frame_count[player] > hi_frame_count)
hi_frame_count = netplay->read_frame_count[player];
}
}
else
{
lo_frame_count = hi_frame_count = netplay->server_frame_count;
}
/* If we're behind, try to catch up */
if (netplay->catch_up)
{
/* Are we caught up? */
if (netplay->self_frame_count + 1 >= lo_frame_count)
{
netplay->catch_up = false;
input_driver_unset_nonblock_state();
driver_set_nonblock_state();
}
}
else if (!stalled)
{
if (netplay->self_frame_count + 3 < lo_frame_count)
{
retro_time_t cur_time = cpu_features_get_time_usec();
uint32_t cur_behind = lo_frame_count - netplay->self_frame_count;
/* We're behind, but we'll only try to catch up if we're actually
* falling behind, i.e. if we're more behind after some time */
if (netplay->catch_up_time == 0)
{
/* Record our current time to check for catch-up later */
netplay->catch_up_time = cur_time;
netplay->catch_up_behind = cur_behind;
}
else if (cur_time - netplay->catch_up_time > CATCH_UP_CHECK_TIME_USEC)
{
/* Time to check how far behind we are */
if (netplay->catch_up_behind <= cur_behind)
{
/* We're definitely falling behind! */
netplay->catch_up = true;
netplay->catch_up_time = 0;
input_driver_set_nonblock_state();
driver_set_nonblock_state();
}
else
{
/* Check again in another period */
netplay->catch_up_time = cur_time;
netplay->catch_up_behind = cur_behind;
}
}
}
else if (netplay->self_frame_count + 3 < hi_frame_count)
{
size_t i;
netplay->catch_up_time = 0;
/* We're falling behind some clients but not others, so request that
* clients ahead of us stall */
for (i = 0; i < netplay->connections_size; i++)
{
struct netplay_connection *connection = &netplay->connections[i];
int player;
if (!connection->active ||
connection->mode != NETPLAY_CONNECTION_PLAYING)
continue;
player = connection->player;
/* Are they ahead? */
if (netplay->self_frame_count + 3 < netplay->read_frame_count[player])
{
/* Tell them to stall */
if (connection->stall_frame + NETPLAY_MAX_REQ_STALL_FREQUENCY <
netplay->self_frame_count)
{
connection->stall_frame = netplay->self_frame_count;
netplay_cmd_stall(netplay, connection,
netplay->read_frame_count[player] -
netplay->self_frame_count + 1);
}
}
}
}
else
netplay->catch_up_time = 0;
}
else
netplay->catch_up_time = 0;
}
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