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Chat: new settings to prevent spam
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Added the following chat coreside features
* Chat messages length limit
* Message rate limiting
* Message rate kicking

Note:
* handleChat now takes RemotePlayer pointer instead of u16 to remove useless
  lookups
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nerzhul committed Oct 4, 2016
1 parent 1079aea commit d4c7625
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Showing 8 changed files with 125 additions and 11 deletions.
9 changes: 9 additions & 0 deletions builtin/settingtypes.txt
Original file line number Diff line number Diff line change
Expand Up @@ -774,6 +774,15 @@ time_speed (Time speed) int 72
# Interval of saving important changes in the world, stated in seconds.
server_map_save_interval (Map save interval) float 5.3

# Set the maximum character length of a chat message sent by clients.
# chat_message_max_size int 500

# Limit a single player to send X messages per 10 seconds.
# chat_message_limit_per_10sec float 10.0

# Kick player if send more than X messages per 10 seconds.
# chat_message_limit_trigger_kick int 50

[**Physics]

movement_acceleration_default (Default acceleration) float 3
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14 changes: 13 additions & 1 deletion minetest.conf.example
Original file line number Diff line number Diff line change
Expand Up @@ -933,6 +933,18 @@
# type: float
# server_map_save_interval = 5.3

# Set the maximum character length of a chat message sent by clients. (0 to disable)
# type: integer
# chat_message_max_size = 500

# Limit a single player to send X messages per 10 seconds. (0 to disable)
# type: float
# chat_message_limit_per_10sec = 8.0

# Kick player if send more than X messages per 10 seconds. (0 to disable)
# type: integer
# chat_message_limit_trigger_kick = 50

### Physics

# type: float
Expand Down Expand Up @@ -1523,7 +1535,7 @@
# profiler.default_report_format = txt

# The file path relative to your worldpath in which profiles will be saved to.
#
#
# type: string
# profiler.report_path = ""

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3 changes: 3 additions & 0 deletions src/defaultsettings.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,9 @@ void set_default_settings(Settings *settings)
settings->setDefault("server_unload_unused_data_timeout", "29");
settings->setDefault("max_objects_per_block", "49");
settings->setDefault("server_map_save_interval", "5.3");
settings->setDefault("chat_message_max_size", "500");
settings->setDefault("chat_message_limit_per_10sec", "8.0");
settings->setDefault("chat_message_limit_trigger_kick", "50");
settings->setDefault("sqlite_synchronous", "2");
settings->setDefault("full_block_send_enable_min_time_from_building", "2.0");
settings->setDefault("dedicated_server_step", "0.1");
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10 changes: 5 additions & 5 deletions src/network/serverpackethandler.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -1065,7 +1065,7 @@ void Server::handleCommand_ChatMessage(NetworkPacket* pkt)
std::wstring wname = narrow_to_wide(name);

std::wstring answer_to_sender = handleChat(name, wname, message,
true, pkt->getPeerId());
true, dynamic_cast<RemotePlayer *>(player));
if (!answer_to_sender.empty()) {
// Send the answer to sender
SendChatMessage(pkt->getPeerId(), answer_to_sender);
Expand Down Expand Up @@ -1656,16 +1656,16 @@ void Server::handleCommand_Interact(NetworkPacket* pkt)
}

} // action == 4

/*
5: rightclick air
*/
else if (action == 5) {
ItemStack item = playersao->getWieldedItem();
actionstream << player->getName() << " activates "

actionstream << player->getName() << " activates "
<< item.name << std::endl;

if (m_script->item_OnSecondaryUse(
item, playersao)) {
if( playersao->setWieldedItem(item)) {
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56 changes: 55 additions & 1 deletion src/player.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -227,10 +227,25 @@ void Player::clearHud()
}
}

// static config cache for remoteplayer
bool RemotePlayer::m_setting_cache_loaded = false;
float RemotePlayer::m_setting_chat_message_limit_per_10sec = 0.0f;
u16 RemotePlayer::m_setting_chat_message_limit_trigger_kick = 0;

RemotePlayer::RemotePlayer(IGameDef *gamedef, const char *name):
Player(gamedef, name),
m_sao(NULL)
m_sao(NULL),
m_last_chat_message_sent(time(NULL)),
m_chat_message_allowance(5.0f),
m_message_rate_overhead(0)
{
if (!RemotePlayer::m_setting_cache_loaded) {
RemotePlayer::m_setting_chat_message_limit_per_10sec =
g_settings->getFloat("chat_message_limit_per_10sec");
RemotePlayer::m_setting_chat_message_limit_trigger_kick =
g_settings->getU16("chat_message_limit_trigger_kick");
RemotePlayer::m_setting_cache_loaded = true;
}
movement_acceleration_default = g_settings->getFloat("movement_acceleration_default") * BS;
movement_acceleration_air = g_settings->getFloat("movement_acceleration_air") * BS;
movement_acceleration_fast = g_settings->getFloat("movement_acceleration_fast") * BS;
Expand Down Expand Up @@ -304,3 +319,42 @@ void RemotePlayer::setPosition(const v3f &position)
m_sao->setBasePosition(position);
}

const RemotePlayerChatResult RemotePlayer::canSendChatMessage()
{
// Rate limit messages
u32 now = time(NULL);
float time_passed = now - m_last_chat_message_sent;
m_last_chat_message_sent = now;

// If this feature is disabled
if (m_setting_chat_message_limit_per_10sec <= 0.0) {
return RPLAYER_CHATRESULT_OK;
}

m_chat_message_allowance += time_passed * (m_setting_chat_message_limit_per_10sec / 8.0f);
if (m_chat_message_allowance > m_setting_chat_message_limit_per_10sec) {
m_chat_message_allowance = m_setting_chat_message_limit_per_10sec;
}

if (m_chat_message_allowance < 1.0f) {
infostream << "Player " << m_name
<< " chat limited due to excessive message amount." << std::endl;

// Kick player if flooding is too intensive
m_message_rate_overhead++;
if (m_message_rate_overhead > RemotePlayer::m_setting_chat_message_limit_trigger_kick) {
return RPLAYER_CHATRESULT_KICK;
}

return RPLAYER_CHATRESULT_FLOODING;
}

// Reinit message overhead
if (m_message_rate_overhead > 0) {
m_message_rate_overhead = 0;
}

m_chat_message_allowance -= 1.0f;
return RPLAYER_CHATRESULT_OK;
}

16 changes: 15 additions & 1 deletion src/player.h
Original file line number Diff line number Diff line change
Expand Up @@ -439,7 +439,11 @@ class Player
Mutex m_mutex;
};


enum RemotePlayerChatResult {
RPLAYER_CHATRESULT_OK,
RPLAYER_CHATRESULT_FLOODING,
RPLAYER_CHATRESULT_KICK,
};
/*
Player on the server
*/
Expand All @@ -457,8 +461,18 @@ class RemotePlayer : public Player
{ m_sao = sao; }
void setPosition(const v3f &position);

const RemotePlayerChatResult canSendChatMessage();

private:
PlayerSAO *m_sao;

static bool m_setting_cache_loaded;
static float m_setting_chat_message_limit_per_10sec;
static u16 m_setting_chat_message_limit_trigger_kick;

u32 m_last_chat_message_sent;
float m_chat_message_allowance;
u16 m_message_rate_overhead;
};

#endif
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25 changes: 23 additions & 2 deletions src/server.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,7 @@ Server::Server(
add_legacy_abms(m_env, m_nodedef);

m_liquid_transform_every = g_settings->getFloat("liquid_update");
m_max_chatmessage_length = g_settings->getU16("chat_message_max_size");
}

Server::~Server()
Expand Down Expand Up @@ -2734,8 +2735,7 @@ void Server::handleChatInterfaceEvent(ChatEvent *evt)
}

std::wstring Server::handleChat(const std::string &name, const std::wstring &wname,
const std::wstring &wmessage, bool check_shout_priv,
u16 peer_id_to_avoid_sending)
const std::wstring &wmessage, bool check_shout_priv, RemotePlayer *player)
{
// If something goes wrong, this player is to blame
RollbackScopeActor rollback_scope(m_rollback,
Expand All @@ -2753,6 +2753,26 @@ std::wstring Server::handleChat(const std::string &name, const std::wstring &wna
if (ate)
return L"";

switch (player->canSendChatMessage()) {
case RPLAYER_CHATRESULT_FLOODING: {
std::wstringstream ws;
ws << L"You cannot send more messages. You are limited to "
<< g_settings->getFloat("chat_message_limit_per_10sec")
<< " messages per 10 seconds.";
return ws.str();
}
case RPLAYER_CHATRESULT_KICK:
DenyAccess_Legacy(player->peer_id, L"You have been kicked due to message flooding.");
return L"";
case RPLAYER_CHATRESULT_OK: break;
default: FATAL_ERROR("Unhandled chat filtering result found.");
}

if (m_max_chatmessage_length > 0 && wmessage.length() > m_max_chatmessage_length) {
return L"Your message exceed the maximum chat message limit set on the server. "
"It was refused. Send a shorter message";
}

// Commands are implemented in Lua, so only catch invalid
// commands that were not "eaten" and send an error back
if (wmessage[0] == L'/') {
Expand Down Expand Up @@ -2787,6 +2807,7 @@ std::wstring Server::handleChat(const std::string &name, const std::wstring &wna

std::vector<u16> clients = m_clients.getClientIDs();

u16 peer_id_to_avoid_sending = (player ? player->peer_id : PEER_ID_INEXISTENT);
for (u16 i = 0; i < clients.size(); i++) {
u16 cid = clients[i];
if (cid != peer_id_to_avoid_sending)
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3 changes: 2 additions & 1 deletion src/server.h
Original file line number Diff line number Diff line change
Expand Up @@ -487,7 +487,7 @@ class Server : public con::PeerHandler, public MapEventReceiver,
std::wstring handleChat(const std::string &name, const std::wstring &wname,
const std::wstring &wmessage,
bool check_shout_priv = false,
u16 peer_id_to_avoid_sending = PEER_ID_INEXISTENT);
RemotePlayer *player = NULL);
void handleAdminChat(const ChatEventChat *evt);

v3f findSpawnPos();
Expand Down Expand Up @@ -522,6 +522,7 @@ class Server : public con::PeerHandler, public MapEventReceiver,
// If true, do not allow multiple players and hide some multiplayer
// functionality
bool m_simple_singleplayer_mode;
u16 m_max_chatmessage_length;

// Thread can set; step() will throw as ServerError
MutexedVariable<std::string> m_async_fatal_error;
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