implement part 1 of the multi-protocol functionality: protocols

this contains support for connecting via, and serving simultaneously via, any of the three protocols: latest, GPP and 1.1

alternate-1 means protocol 70 (GPP), alternate-2 means protocol 69 (1.1)

relevant cvars:
- net_alternateProtocols
- net_alt{1|2}port[6]
- sv_alt{1|2}master{1|...|5}
- sv_clAltProto{0|..|63}

1 files changed, 108 insertions, 0 deletions

diff --git a/src/server/sv_net_chan.c b/src/server/sv_net_chan.c
index d7ac326c..7ec27cf9 100644
--- a/src/server/sv_net_chan.c
+++ b/src/server/sv_net_chan.c
@@ -26,6 +26,110 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #include "server.h"
 
 /*
+==============
+SV_Netchan_Encode
+
+	// first four bytes of the data are always:
+	long reliableAcknowledge;
+
+==============
+*/
+static void SV_Netchan_Encode( client_t *client, msg_t *msg ) {
+	long i, index;
+	byte key, *string;
+	int	srdc, sbit;
+	qboolean soob;
+
+	if ( msg->cursize < SV_ENCODE_START ) {
+		return;
+	}
+
+	srdc = msg->readcount;
+	sbit = msg->bit;
+	soob = msg->oob;
+
+	msg->bit = 0;
+	msg->readcount = 0;
+	msg->oob = qfalse;
+
+	/* reliableAcknowledge = */ MSG_ReadLong(msg);
+
+	msg->oob = soob;
+	msg->bit = sbit;
+	msg->readcount = srdc;
+
+	string = (byte *)client->lastClientCommandString;
+	index = 0;
+	// xor the client challenge with the netchan sequence number
+	key = client->challenge ^ client->netchan.outgoingSequence;
+	for (i = SV_ENCODE_START; i < msg->cursize; i++) {
+		// modify the key with the last received and with this message acknowledged client command
+		if (!string[index])
+			index = 0;
+		if (string[index] > 127 || (client->netchan.alternateProtocol == 2 && string[index] == '%')) {
+			key ^= '.' << (i & 1);
+		}
+		else {
+			key ^= string[index] << (i & 1);
+		}
+		index++;
+		// encode the data with this key
+		*(msg->data + i) = *(msg->data + i) ^ key;
+	}
+}
+
+/*
+==============
+SV_Netchan_Decode
+
+	// first 12 bytes of the data are always:
+	long serverId;
+	long messageAcknowledge;
+	long reliableAcknowledge;
+
+==============
+*/
+static void SV_Netchan_Decode( client_t *client, msg_t *msg ) {
+	int serverId, messageAcknowledge, reliableAcknowledge;
+	int i, index, srdc, sbit;
+	qboolean soob;
+	byte key, *string;
+
+	srdc = msg->readcount;
+	sbit = msg->bit;
+	soob = msg->oob;
+
+	msg->oob = qfalse;
+
+	serverId = MSG_ReadLong(msg);
+	messageAcknowledge = MSG_ReadLong(msg);
+	reliableAcknowledge = MSG_ReadLong(msg);
+
+	msg->oob = soob;
+	msg->bit = sbit;
+	msg->readcount = srdc;
+
+	string = (byte *)client->reliableCommands[ reliableAcknowledge & (MAX_RELIABLE_COMMANDS-1) ];
+	index = 0;
+
+	key = client->challenge ^ serverId ^ messageAcknowledge;
+	for (i = msg->readcount + SV_DECODE_START; i < msg->cursize; i++) {
+		// modify the key with the last sent and acknowledged server command
+		if (!string[index])
+			index = 0;
+		if (string[index] > 127 || (client->netchan.alternateProtocol == 2 && string[index] == '%')) {
+			key ^= '.' << (i & 1);
+		}
+		else {
+			key ^= string[index] << (i & 1);
+		}
+		index++;
+		// decode the data with this key
+		*(msg->data + i) = *(msg->data + i) ^ key;
+	}
+}
+
+/*
 =================
 SV_Netchan_FreeQueue
 =================
@@ -126,6 +230,8 @@ void SV_Netchan_Transmit( client_t *client, msg_t *msg)
 	}
 	else
 	{
+		if (client->netchan.alternateProtocol != 0)
+			SV_Netchan_Encode( client, msg );
 		Netchan_Transmit( &client->netchan, msg->cursize, msg->data );
 	}
 }
@@ -140,6 +246,8 @@ qboolean SV_Netchan_Process( client_t *client, msg_t *msg ) {
 	ret = Netchan_Process( &client->netchan, msg );
 	if (!ret)
 		return qfalse;
+	if (client->netchan.alternateProtocol != 0)
+		SV_Netchan_Decode( client, msg );
 
 	return qtrue;
 }