1 files changed, 452 insertions, 0 deletions
diff --git a/QW/client/net_chan.c b/QW/client/net_chan.c
new file mode 100644
index 0000000..bd325a1
--- /dev/null
+++ b/QW/client/net_chan.c
@@ -0,0 +1,452 @@
+/*
+Copyright (C) 1996-1997 Id Software, Inc.
+
+This program 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 Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program 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 this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+*/
+
+#include "quakedef.h"
+
+#ifdef _WIN32
+#include "winquake.h"
+#endif
+
+#define	PACKET_HEADER	8
+
+/*
+
+packet header
+-------------
+31	sequence
+1	does this message contain a reliable payload
+31	acknowledge sequence
+1	acknowledge receipt of even/odd message
+16  qport
+
+The remote connection never knows if it missed a reliable message, the
+local side detects that it has been dropped by seeing a sequence acknowledge
+higher thatn the last reliable sequence, but without the correct evon/odd
+bit for the reliable set.
+
+If the sender notices that a reliable message has been dropped, it will be
+retransmitted.  It will not be retransmitted again until a message after
+the retransmit has been acknowledged and the reliable still failed to get there.
+
+if the sequence number is -1, the packet should be handled without a netcon
+
+The reliable message can be added to at any time by doing
+MSG_Write* (&netchan->message, <data>).
+
+If the message buffer is overflowed, either by a single message, or by
+multiple frames worth piling up while the last reliable transmit goes
+unacknowledged, the netchan signals a fatal error.
+
+Reliable messages are allways placed first in a packet, then the unreliable
+message is included if there is sufficient room.
+
+To the receiver, there is no distinction between the reliable and unreliable
+parts of the message, they are just processed out as a single larger message.
+
+Illogical packet sequence numbers cause the packet to be dropped, but do
+not kill the connection.  This, combined with the tight window of valid
+reliable acknowledgement numbers provides protection against malicious
+address spoofing.
+
+The qport field is a workaround for bad address translating routers that
+sometimes remap the client's source port on a packet during gameplay.
+
+If the base part of the net address matches and the qport matches, then the
+channel matches even if the IP port differs.  The IP port should be updated
+to the new value before sending out any replies.
+
+
+*/
+
+int		net_drop;
+cvar_t	showpackets = {"showpackets", "0"};
+cvar_t	showdrop = {"showdrop", "0"};
+cvar_t	qport = {"qport", "0"};
+
+/*
+===============
+Netchan_Init
+
+===============
+*/
+void Netchan_Init (void)
+{
+	int		port;
+
+	// pick a port value that should be nice and random
+#ifdef _WIN32
+	port = ((int)(timeGetTime()*1000) * time(NULL)) & 0xffff;
+#else
+	port = ((int)(getpid()+getuid()*1000) * time(NULL)) & 0xffff;
+#endif
+
+	Cvar_RegisterVariable (&showpackets);
+	Cvar_RegisterVariable (&showdrop);
+	Cvar_RegisterVariable (&qport);
+	Cvar_SetValue("qport", port);
+}
+
+/*
+===============
+Netchan_OutOfBand
+
+Sends an out-of-band datagram
+================
+*/
+void Netchan_OutOfBand (netadr_t adr, int length, byte *data)
+{
+	sizebuf_t	send;
+	byte		send_buf[MAX_MSGLEN + PACKET_HEADER];
+
+// write the packet header
+	send.data = send_buf;
+	send.maxsize = sizeof(send_buf);
+	send.cursize = 0;
+	
+	MSG_WriteLong (&send, -1);	// -1 sequence means out of band
+	SZ_Write (&send, data, length);
+
+// send the datagram
+	//zoid, no input in demo playback mode
+#ifndef SERVERONLY
+	if (!cls.demoplayback)
+#endif
+		NET_SendPacket (send.cursize, send.data, adr);
+}
+
+/*
+===============
+Netchan_OutOfBandPrint
+
+Sends a text message in an out-of-band datagram
+================
+*/
+void Netchan_OutOfBandPrint (netadr_t adr, char *format, ...)
+{
+	va_list		argptr;
+	static char		string[8192];		// ??? why static?
+	
+	va_start (argptr, format);
+	vsprintf (string, format,argptr);
+	va_end (argptr);
+
+
+	Netchan_OutOfBand (adr, strlen(string), (byte *)string);
+}
+
+
+/*
+==============
+Netchan_Setup
+
+called to open a channel to a remote system
+==============
+*/
+void Netchan_Setup (netchan_t *chan, netadr_t adr, int qport)
+{
+	memset (chan, 0, sizeof(*chan));
+	
+	chan->remote_address = adr;
+	chan->last_received = realtime;
+	
+	chan->message.data = chan->message_buf;
+	chan->message.allowoverflow = true;
+	chan->message.maxsize = sizeof(chan->message_buf);
+
+	chan->qport = qport;
+	
+	chan->rate = 1.0/2500;
+}
+
+
+/*
+===============
+Netchan_CanPacket
+
+Returns true if the bandwidth choke isn't active
+================
+*/
+#define	MAX_BACKUP	200
+qboolean Netchan_CanPacket (netchan_t *chan)
+{
+	if (chan->cleartime < realtime + MAX_BACKUP*chan->rate)
+		return true;
+	return false;
+}
+
+
+/*
+===============
+Netchan_CanReliable
+
+Returns true if the bandwidth choke isn't 
+================
+*/
+qboolean Netchan_CanReliable (netchan_t *chan)
+{
+	if (chan->reliable_length)
+		return false;			// waiting for ack
+	return Netchan_CanPacket (chan);
+}
+
+#ifdef SERVERONLY
+qboolean ServerPaused(void);
+#endif
+
+/*
+===============
+Netchan_Transmit
+
+tries to send an unreliable message to a connection, and handles the
+transmition / retransmition of the reliable messages.
+
+A 0 length will still generate a packet and deal with the reliable messages.
+================
+*/
+void Netchan_Transmit (netchan_t *chan, int length, byte *data)
+{
+	sizebuf_t	send;
+	byte		send_buf[MAX_MSGLEN + PACKET_HEADER];
+	qboolean	send_reliable;
+	unsigned	w1, w2;
+	int			i;
+
+// check for message overflow
+	if (chan->message.overflowed)
+	{
+		chan->fatal_error = true;
+		Con_Printf ("%s:Outgoing message overflow\n"
+			, NET_AdrToString (chan->remote_address));
+		return;
+	}
+
+// if the remote side dropped the last reliable message, resend it
+	send_reliable = false;
+
+	if (chan->incoming_acknowledged > chan->last_reliable_sequence
+	&& chan->incoming_reliable_acknowledged != chan->reliable_sequence)
+		send_reliable = true;
+
+// if the reliable transmit buffer is empty, copy the current message out
+	if (!chan->reliable_length && chan->message.cursize)
+	{
+		memcpy (chan->reliable_buf, chan->message_buf, chan->message.cursize);
+		chan->reliable_length = chan->message.cursize;
+		chan->message.cursize = 0;
+		chan->reliable_sequence ^= 1;
+		send_reliable = true;
+	}
+
+// write the packet header
+	send.data = send_buf;
+	send.maxsize = sizeof(send_buf);
+	send.cursize = 0;
+
+	w1 = chan->outgoing_sequence | (send_reliable<<31);
+	w2 = chan->incoming_sequence | (chan->incoming_reliable_sequence<<31);
+
+	chan->outgoing_sequence++;
+
+	MSG_WriteLong (&send, w1);
+	MSG_WriteLong (&send, w2);
+
+	// send the qport if we are a client
+#ifndef SERVERONLY
+	MSG_WriteShort (&send, cls.qport);
+#endif
+
+// copy the reliable message to the packet first
+	if (send_reliable)
+	{
+		SZ_Write (&send, chan->reliable_buf, chan->reliable_length);
+		chan->last_reliable_sequence = chan->outgoing_sequence;
+	}
+	
+// add the unreliable part if space is available
+	if (send.maxsize - send.cursize >= length)
+		SZ_Write (&send, data, length);
+
+// send the datagram
+	i = chan->outgoing_sequence & (MAX_LATENT-1);
+	chan->outgoing_size[i] = send.cursize;
+	chan->outgoing_time[i] = realtime;
+
+	//zoid, no input in demo playback mode
+#ifndef SERVERONLY
+	if (!cls.demoplayback)
+#endif
+		NET_SendPacket (send.cursize, send.data, chan->remote_address);
+
+	if (chan->cleartime < realtime)
+		chan->cleartime = realtime + send.cursize*chan->rate;
+	else
+		chan->cleartime += send.cursize*chan->rate;
+#ifdef SERVERONLY
+	if (ServerPaused())
+		chan->cleartime = realtime;
+#endif
+
+	if (showpackets.value)
+		Con_Printf ("--> s=%i(%i) a=%i(%i) %i\n"
+			, chan->outgoing_sequence
+			, send_reliable
+			, chan->incoming_sequence
+			, chan->incoming_reliable_sequence
+			, send.cursize);
+
+}
+
+/*
+=================
+Netchan_Process
+
+called when the current net_message is from remote_address
+modifies net_message so that it points to the packet payload
+=================
+*/
+qboolean Netchan_Process (netchan_t *chan)
+{
+	unsigned		sequence, sequence_ack;
+	unsigned		reliable_ack, reliable_message;
+#ifdef SERVERONLY
+	int			qport;
+#endif
+	int i;
+
+	if (
+#ifndef SERVERONLY
+			!cls.demoplayback && 
+#endif
+			!NET_CompareAdr (net_from, chan->remote_address))
+		return false;
+	
+// get sequence numbers		
+	MSG_BeginReading ();
+	sequence = MSG_ReadLong ();
+	sequence_ack = MSG_ReadLong ();
+
+	// read the qport if we are a server
+#ifdef SERVERONLY
+	qport = MSG_ReadShort ();
+#endif
+
+	reliable_message = sequence >> 31;
+	reliable_ack = sequence_ack >> 31;
+
+	sequence &= ~(1<<31);	
+	sequence_ack &= ~(1<<31);	
+
+	if (showpackets.value)
+		Con_Printf ("<-- s=%i(%i) a=%i(%i) %i\n"
+			, sequence
+			, reliable_message
+			, sequence_ack
+			, reliable_ack
+			, net_message.cursize);
+
+// get a rate estimation
+#if 0
+	if (chan->outgoing_sequence - sequence_ack < MAX_LATENT)
+	{
+		int				i;
+		double			time, rate;
+	
+		i = sequence_ack & (MAX_LATENT - 1);
+		time = realtime - chan->outgoing_time[i];
+		time -= 0.1;	// subtract 100 ms
+		if (time <= 0)
+		{	// gotta be a digital link for <100 ms ping
+			if (chan->rate > 1.0/5000)
+				chan->rate = 1.0/5000;
+		}
+		else
+		{
+			if (chan->outgoing_size[i] < 512)
+			{	// only deal with small messages
+				rate = chan->outgoing_size[i]/time;
+				if (rate > 5000)
+					rate = 5000;
+				rate = 1.0/rate;
+				if (chan->rate > rate)
+					chan->rate = rate;
+			}
+		}
+	}
+#endif
+
+//
+// discard stale or duplicated packets
+//
+	if (sequence <= (unsigned)chan->incoming_sequence)
+	{
+		if (showdrop.value)
+			Con_Printf ("%s:Out of order packet %i at %i\n"
+				, NET_AdrToString (chan->remote_address)
+				,  sequence
+				, chan->incoming_sequence);
+		return false;
+	}
+
+//
+// dropped packets don't keep the message from being used
+//
+	net_drop = sequence - (chan->incoming_sequence+1);
+	if (net_drop > 0)
+	{
+		chan->drop_count += 1;
+
+		if (showdrop.value)
+			Con_Printf ("%s:Dropped %i packets at %i\n"
+			, NET_AdrToString (chan->remote_address)
+			, sequence-(chan->incoming_sequence+1)
+			, sequence);
+	}
+
+//
+// if the current outgoing reliable message has been acknowledged
+// clear the buffer to make way for the next
+//
+	if (reliable_ack == (unsigned)chan->reliable_sequence)
+		chan->reliable_length = 0;	// it has been received
+	
+//
+// if this message contains a reliable message, bump incoming_reliable_sequence 
+//
+	chan->incoming_sequence = sequence;
+	chan->incoming_acknowledged = sequence_ack;
+	chan->incoming_reliable_acknowledged = reliable_ack;
+	if (reliable_message)
+		chan->incoming_reliable_sequence ^= 1;
+
+//
+// the message can now be read from the current message pointer
+// update statistics counters
+//
+	chan->frame_latency = chan->frame_latency*OLD_AVG
+		+ (chan->outgoing_sequence-sequence_ack)*(1.0-OLD_AVG);
+	chan->frame_rate = chan->frame_rate*OLD_AVG
+		+ (realtime-chan->last_received)*(1.0-OLD_AVG);		
+	chan->good_count += 1;
+
+	chan->last_received = realtime;
+
+	return true;
+}
+