[CSM] Add send_chat_message and run_server_chatcommand API functions (#5747)

* [CSM] Add send_chat_message and run_server_chatcommand API functions

* Add client-side chat message rate limiting

* Limit out chat queue size

* [CSM] Add minetest.clear_out_chat_queue API function and .clear_chat_queue chatcommand

* Last fixes/cleanups before merge

1 files changed, 50 insertions, 4 deletions

diff --git a/src/client.cpp b/src/client.cpp
index a36f5413f..a5228132d 100644
--- a/src/client.cpp
+++ b/src/client.cpp
@@ -104,6 +104,8 @@ Client::Client(
 	m_animation_time(0),
 	m_crack_level(-1),
 	m_crack_pos(0,0,0),
+	m_last_chat_message_sent(time(NULL)),
+	m_chat_message_allowance(5.0f),
 	m_map_seed(0),
 	m_password(password),
 	m_chosen_auth_mech(AUTH_MECHANISM_NONE),
@@ -401,6 +403,14 @@ void Client::step(float dtime)
 	}
 
 	/*
+		Send pending messages on out chat queue
+	*/
+	if (!m_out_chat_queue.empty() && canSendChatMessage()) {
+		sendChatMessage(m_out_chat_queue.front());
+		m_out_chat_queue.pop();
+	}
+
+	/*
 		Handle environment
 	*/
 	// Control local player (0ms)
@@ -1158,13 +1168,50 @@ void Client::sendInventoryAction(InventoryAction *a)
 	Send(&pkt);
 }
 
+bool Client::canSendChatMessage() const
+{
+	u32 now = time(NULL);
+	float time_passed = now - m_last_chat_message_sent;
+
+	float virt_chat_message_allowance = m_chat_message_allowance + time_passed *
+			(CLIENT_CHAT_MESSAGE_LIMIT_PER_10S / 8.0f);
+
+	if (virt_chat_message_allowance < 1.0f)
+		return false;
+
+	return true;
+}
+
 void Client::sendChatMessage(const std::wstring &message)
 {
-	NetworkPacket pkt(TOSERVER_CHAT_MESSAGE, 2 + message.size() * sizeof(u16));
+	const s16 max_queue_size = g_settings->getS16("max_out_chat_queue_size");
+	if (canSendChatMessage()) {
+		u32 now = time(NULL);
+		float time_passed = now - m_last_chat_message_sent;
+		m_last_chat_message_sent = time(NULL);
 
-	pkt << message;
+		m_chat_message_allowance += time_passed * (CLIENT_CHAT_MESSAGE_LIMIT_PER_10S / 8.0f);
+		if (m_chat_message_allowance > CLIENT_CHAT_MESSAGE_LIMIT_PER_10S)
+			m_chat_message_allowance = CLIENT_CHAT_MESSAGE_LIMIT_PER_10S;
 
-	Send(&pkt);
+		m_chat_message_allowance -= 1.0f;
+
+		NetworkPacket pkt(TOSERVER_CHAT_MESSAGE, 2 + message.size() * sizeof(u16));
+
+		pkt << message;
+
+		Send(&pkt);
+	} else if (m_out_chat_queue.size() < (u16) max_queue_size || max_queue_size == -1) {
+		m_out_chat_queue.push(message);
+	} else {
+		infostream << "Could not queue chat message because maximum out chat queue size ("
+				<< max_queue_size << ") is reached." << std::endl;
+	}
+}
+
+void Client::clearOutChatQueue()
+{
+	m_out_chat_queue = std::queue<std::wstring>();
 }
 
 void Client::sendChangePassword(const std::string &oldpassword,
@@ -1924,4 +1971,3 @@ std::string Client::getModStoragePath() const
 {
 	return porting::path_user + DIR_DELIM + "client" + DIR_DELIM + "mod_storage";
 }
-