// return a free acknum and copy netbuffer in the ackpak table
static boolean GetFreeAcknum(UINT8 *freeack, boolean lowtimer)
{
node_t *node = &nodes[doomcom->remotenode];
INT32 i, numfreeslote = 0;
if (cmpack((UINT8)((node->remotefirstack + MAXACKTOSEND) % 256), node->nextacknum) < 0)
{
DEBFILE(va("too fast %d %d\n",node->remotefirstack,node->nextacknum));
return false;
}
for (i = 0; i < MAXACKPACKETS; i++)
if (!ackpak[i].acknum)
{
// for low priority packet, make sure let freeslotes so urgents packets can be sent
numfreeslote++;
if (netbuffer->packettype >= PT_CANFAIL && numfreeslote < URGENTFREESLOTENUM)
continue;
ackpak[i].acknum = node->nextacknum;
ackpak[i].nextacknum = node->nextacknum;
node->nextacknum++;
if (!node->nextacknum)
node->nextacknum++;
ackpak[i].destinationnode = (UINT8)(node - nodes);
ackpak[i].length = doomcom->datalength;
if (lowtimer)
{
// lowtime mean can't be sent now so try it soon as possible
ackpak[i].senttime = 0;
ackpak[i].resentnum = 1;
}
else
{
ackpak[i].senttime = I_GetTime();
ackpak[i].resentnum = 0;
}
M_Memcpy(ackpak[i].pak.raw, netbuffer, ackpak[i].length);
*freeack = ackpak[i].acknum;
sendackpacket++; // for stat
return true;
}
#ifdef PARANOIA
if (devparm)
I_OutputMsg("No more free ackpacket\n");
#endif
if (netbuffer->packettype < PT_CANFAIL)
I_Error("Connection lost\n");
return false;
}
static void GotAcks(void)
{
INT32 i, j;
for (j = 0; j < MAXACKTOSEND; j++)
if (netbuffer->u.textcmd[j])
for (i = 0; i < MAXACKPACKETS; i++)
if (ackpak[i].acknum && ackpak[i].destinationnode == doomcom->remotenode)
{
if (ackpak[i].acknum == netbuffer->u.textcmd[j])
Removeack(i);
else
// nextacknum is first equal to acknum, then when receiving bigger ack
// there is big chance the packet is lost
// when resent, nextacknum = nodes[node].nextacknum
// will redo the same but with different value
if (cmpack(ackpak[i].nextacknum, netbuffer->u.textcmd[j]) <= 0
&& ackpak[i].senttime > 0)
{
ackpak[i].senttime--; // hurry up
}
}
}
// we have got a packet proceed the ack request and ack return
static boolean Processackpak(void)
{
INT32 i;
boolean goodpacket = true;
node_t *node = &nodes[doomcom->remotenode];
// received an ack return, so remove the ack in the list
if (netbuffer->ackreturn && cmpack(node->remotefirstack, netbuffer->ackreturn) < 0)
{
node->remotefirstack = netbuffer->ackreturn;
// search the ackbuffer and free it
for (i = 0; i < MAXACKPACKETS; i++)
if (ackpak[i].acknum && ackpak[i].destinationnode == node - nodes
&& cmpack(ackpak[i].acknum, netbuffer->ackreturn) <= 0)
{
Removeack(i);
}
}
// received a packet with ack, queue it to send the ack back
if (netbuffer->ack)
{
UINT8 ack = netbuffer->ack;
getackpacket++;
if (cmpack(ack, node->firstacktosend) <= 0)
{
DEBFILE(va("Discard(1) ack %d (duplicated)\n", ack));
duppacket++;
goodpacket = false; // discard packet (duplicate)
}
else
{
// check if it is not already in the queue
for (i = node->acktosend_tail; i != node->acktosend_head; i = (i+1) % MAXACKTOSEND)
if (node->acktosend[i] == ack)
{
DEBFILE(va("Discard(2) ack %d (duplicated)\n", ack));
duppacket++;
goodpacket = false; // discard packet (duplicate)
break;
}
if (goodpacket)
{
// is a good packet so increment the acknowledge number,
// then search for a "hole" in the queue
UINT8 nextfirstack = (UINT8)(node->firstacktosend + 1);
if (!nextfirstack)
nextfirstack = 1;
if (ack == nextfirstack)
{
UINT8 hm1; // head - 1
boolean change = true;
node->firstacktosend = nextfirstack++;
if (!nextfirstack)
nextfirstack = 1;
hm1 = (UINT8)((node->acktosend_head-1+MAXACKTOSEND) % MAXACKTOSEND);
while (change)
{
change = false;
for (i = node->acktosend_tail; i != node->acktosend_head;
i = (i+1) % MAXACKTOSEND)
{
if (cmpack(node->acktosend[i], nextfirstack) <= 0)
{
if (node->acktosend[i] == nextfirstack)
{
node->firstacktosend = nextfirstack++;
if (!nextfirstack)
nextfirstack = 1;
change = true;
}
if (i == node->acktosend_tail)
{
node->acktosend[node->acktosend_tail] = 0;
node->acktosend_tail = (UINT8)((i+1) % MAXACKTOSEND);
}
else if (i == hm1)
{
node->acktosend[hm1] = 0;
node->acktosend_head = hm1;
hm1 = (UINT8)((hm1-1+MAXACKTOSEND) % MAXACKTOSEND);
}
}
}
}
}
else // out of order packet
{
// don't increment firsacktosend, put it in asktosend queue
// will be incremented when the nextfirstack comes (code above)
UINT8 newhead = (UINT8)((node->acktosend_head+1) % MAXACKTOSEND);
DEBFILE(va("out of order packet (%d expected)\n", nextfirstack));
if (newhead != node->acktosend_tail)
{
node->acktosend[node->acktosend_head] = ack;
node->acktosend_head = newhead;
}
else // buffer full discard packet, sender will resend it
{ // we can admit the packet but we will not detect the duplication after :(
DEBFILE("no more freeackret\n");
goodpacket = false;
}
}
}
}
}
return goodpacket;
}