/* 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" #else #include "unistd.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, ). 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 = (time(NULL)) & 0xffff; #else port = ((int)(getpid()+getuid()*1000) * time(NULL)) & 0xffff; #endif Cvar_Register (&showpackets, "Networking"); Cvar_Register (&showdrop, "Networking"); Cvar_Register (&qport, "Networking"); Cvar_SetValue(&qport, port); } /* =============== Netchan_OutOfBand Sends an out-of-band datagram ================ */ void Netchan_OutOfBand (netsrc_t sock, netadr_t adr, int length, qbyte *data) { sizebuf_t send; qbyte send_buf[MAX_QWMSGLEN + 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 (sock, send.cursize, send.data, adr); } /* =============== Netchan_OutOfBandPrint Sends a text message in an out-of-band datagram ================ */ void VARGS Netchan_OutOfBandPrint (netsrc_t sock, netadr_t adr, char *format, ...) { va_list argptr; static char string[8192]; // ??? why static? va_start (argptr, format); _vsnprintf (string,sizeof(string)-1, format,argptr); va_end (argptr); Netchan_OutOfBand (sock, adr, strlen(string), (qbyte *)string); } #ifndef CLIENTONLY void VARGS Netchan_OutOfBandTPrintf (netsrc_t sock, netadr_t adr, int language, translation_t text, ...) { va_list argptr; static char string[8192]; // ??? why static? char *format = langtext(text, language); string[0] = A2C_PRINT; va_start (argptr, text); _vsnprintf (string+1,sizeof(string)-2, format,argptr); va_end (argptr); Netchan_OutOfBand (sock, adr, strlen(string), (qbyte *)string); } #endif /* ============== Netchan_Setup called to open a channel to a remote system ============== */ void Netchan_Setup (netsrc_t sock, netchan_t *chan, netadr_t adr, int qport) { memset (chan, 0, sizeof(*chan)); #ifdef NQPROT chan->qsocket = NULL; #endif chan->sock = sock; chan->remote_address = adr; chan->last_received = realtime; chan->message.data = chan->message_buf; chan->message.allowoverflow = true; chan->message.maxsize = MAX_QWMSGLEN;//sizeof(chan->message_buf); chan->qport = qport; } /* =============== Netchan_CanPacket Returns true if the bandwidth choke isn't active ================ */ #define MAX_BACKUP 200 qboolean Netchan_CanPacket (netchan_t *chan, int rate) { if (chan->remote_address.type == NA_LOOPBACK) return true; //don't ever drop packets due to possible routing problems when there is no routing. if (chan->cleartime < realtime + MAX_BACKUP/(float)rate) return true; return false; } /* =============== Netchan_CanReliable Returns true if the bandwidth choke isn't ================ */ qboolean Netchan_CanReliable (netchan_t *chan, int rate) { if (chan->reliable_length) return false; // waiting for ack return Netchan_CanPacket (chan, rate); } #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, qbyte *data, int rate) { sizebuf_t send; qbyte send_buf[MAX_OVERALLMSGLEN + PACKET_HEADER]; qboolean send_reliable; unsigned w1, w2; int i; #ifdef NQPROT if (chan->qsocket && !chan->qsocket->qwprotocol) { if (!NET_CanSendMessage (chan->qsocket)) return; 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; } send.data = send_buf; send.maxsize = MAX_NQMSGLEN + PACKET_HEADER; send.cursize = 0; chan->outgoing_sequence++; chan->last_reliable_sequence = chan->outgoing_sequence; SZ_Write (&send, chan->reliable_buf, chan->reliable_length); SZ_Write (&send, data, length); NET_SendMessage(chan->qsocket, &send); chan->message.cursize = 0; chan->reliable_length = 0; return; } #endif // check for message overflow if (chan->message.overflowed) { chan->fatal_error = true; Con_TPrintf (TL_OUTMESSAGEOVERFLOW , 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 = MAX_QWMSGLEN + PACKET_HEADER; //dmw: wasn't quite true. 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 if (chan->sock == NS_CLIENT) 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; #ifdef HUFFNETWORK if (chan->compress) { int oldsize = send.cursize; Huff_CompressPacket(&send, (chan->sock == NS_CLIENT)?10:8); Con_Printf("%i becomes %i\n", oldsize, send.cursize); // Huff_DecompressPacket(&send, (chan->sock == NS_CLIENT)?10:8); } #endif //zoid, no input in demo playback mode #ifndef SERVERONLY if (!cls.demoplayback) #endif { #ifdef NQPROT if (chan->qsocket) NET_SendUnreliableMessage(chan->qsocket, &send); //qw protocol adds it's own reliability. else #endif NET_SendPacket (chan->sock, send.cursize, send.data, chan->remote_address); } if (chan->cleartime < realtime) chan->cleartime = realtime + send.cursize/(float)rate; else chan->cleartime += send.cursize/(float)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; #ifndef CLIENTONLY int qport; #endif 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 #ifndef CLIENTONLY if (chan->sock == NS_SERVER) 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_TPrintf (TL_OUTOFORDERPACKET , 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_TPrintf (TL_DROPPEDPACKETCOUNT , 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; #ifdef HUFFNETWORK if (chan->compress) { // Huff_CompressPacket(&net_message, (chan->sock == NS_SERVER)?10:8); Huff_DecompressPacket(&net_message, (chan->sock == NS_SERVER)?10:8); } #endif return true; }