OpenTTD/src/network/network_command.cpp

/* $Id$ */

/** @file network_command.cpp Command handling over network connections. */

#ifdef ENABLE_NETWORK

#include "../stdafx.h"
#include "../debug.h"
#include "network_internal.h"
#include "network_client.h"
#include "../command_func.h"
#include "../callback_table.h"
#include "../core/alloc_func.hpp"
#include "../string_func.h"
#include "../date_func.h"
#include "../company_func.h"

/** Local queue of packets */
static CommandPacket *_local_command_queue = NULL;

/**
 * Add a command to the local or client socket command queue,
 * based on the socket.
 * @param cp the command packet to add
 * @param cs the socket to send to (NULL = locally)
 */
void NetworkAddCommandQueue(CommandPacket cp, NetworkClientSocket *cs)
{
	CommandPacket *new_cp = MallocT<CommandPacket>(1);
	*new_cp = cp;

	CommandPacket **begin = (cs == NULL ? &_local_command_queue : &cs->command_queue);

	if (*begin == NULL) {
		*begin = new_cp;
	} else {
		CommandPacket *c = *begin;
		while (c->next != NULL) c = c->next;
		c->next = new_cp;
	}
}

/**
 * Prepare a DoCommand to be send over the network
 * @param tile The tile to perform a command on (see #CommandProc)
 * @param p1 Additional data for the command (see #CommandProc)
 * @param p2 Additional data for the command (see #CommandProc)
 * @param cmd The command to execute (a CMD_* value)
 * @param callback A callback function to call after the command is finished
 * @param text The text to pass
 */
void NetworkSend_Command(TileIndex tile, uint32 p1, uint32 p2, uint32 cmd, CommandCallback *callback, const char *text)
{
	assert((cmd & CMD_FLAGS_MASK) == 0);

	CommandPacket c;
	c.company = _local_company;
	c.next    = NULL;
	c.tile    = tile;
	c.p1      = p1;
	c.p2      = p2;
	c.cmd     = cmd;

	c.callback = 0;
	while (c.callback < _callback_table_count && _callback_table[c.callback] != callback) {
		c.callback++;
	}

	if (c.callback == _callback_table_count) {
		DEBUG(net, 0, "Unknown callback. (Pointer: %p) No callback sent", callback);
		c.callback = 0; // _callback_table[0] == NULL
	}

	strecpy(c.text, (text != NULL) ? text : "", lastof(c.text));

	if (_network_server) {
		/* If we are the server, we queue the command in our 'special' queue.
		 *   In theory, we could execute the command right away, but then the
		 *   client on the server can do everything 1 tick faster than others.
		 *   So to keep the game fair, we delay the command with 1 tick
		 *   which gives about the same speed as most clients.
		 */
		c.frame = _frame_counter_max + 1;

		NetworkAddCommandQueue(c);

		/* Only the local client (in this case, the server) gets the callback */
		c.callback = 0;
		/* And we queue it for delivery to the clients */
		NetworkClientSocket *cs;
		FOR_ALL_CLIENT_SOCKETS(cs) {
			if (cs->status > STATUS_MAP_WAIT) NetworkAddCommandQueue(c, cs);
		}
		return;
	}

	c.frame = 0; // The client can't tell which frame, so just make it 0

	/* Clients send their command to the server and forget all about the packet */
	SEND_COMMAND(PACKET_CLIENT_COMMAND)(&c);
}

/**
 * Execute a DoCommand we received from the network
 * @param cp the command to execute
 */
static void NetworkExecuteCommand(CommandPacket *cp)
{
	_current_company = cp->company;
	/* cp->callback is unsigned. so we don't need to do lower bounds checking. */
	if (cp->callback > _callback_table_count) {
		DEBUG(net, 0, "Received out-of-bounds callback (%d)", cp->callback);
		cp->callback = 0;
	}

	DoCommandP(cp->tile, cp->p1, cp->p2, cp->cmd | CMD_NETWORK_COMMAND, _callback_table[cp->callback], cp->text, cp->my_cmd);
}

/**
 * Execute all commands on the local command queue that ought to be executed this frame.
 */
void NetworkExecuteLocalCommandQueue()
{
	while (_local_command_queue != NULL) {

		/* The queue is always in order, which means
		 * that the first element will be executed first. */
		if (_frame_counter < _local_command_queue->frame) break;

		if (_frame_counter > _local_command_queue->frame) {
			/* If we reach here, it means for whatever reason, we've already executed
			 * past the command we need to execute. */
			error("[net] Trying to execute a packet in the past!");
		}

		/* We can execute this command */
		NetworkExecuteCommand(_local_command_queue);

		CommandPacket *cp = _local_command_queue;
		_local_command_queue = _local_command_queue->next;
		free(cp);
	}
}

/**
 * Free the local command queue.
 */
void NetworkFreeLocalCommandQueue()
{
	/* Free all queued commands */
	while (_local_command_queue != NULL) {
		CommandPacket *p = _local_command_queue;
		_local_command_queue = _local_command_queue->next;
		free(p);
	}
}

#endif /* ENABLE_NETWORK */