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nr4timer.c
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C/C++ Source or Header
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1994-07-11
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4KB
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171 lines
/* net/rom level 4 (transport) protocol timer management.
* Copyright 1989 by Daniel M. Frank, W9NK. Permission granted for
* non-commercial distribution only.
*/
#include <stdio.h>
#include "global.h"
#include "mbuf.h"
#include "timer.h"
#include "ax25.h"
#include "lapb.h"
#include "netrom.h"
#include "nr4.h"
#include <ctype.h>
#undef NR4DEBUG
/* The ACK timer has expired without any data becoming available.
* Go ahead and send an ACK.
*/
void
nr4ackit(p)
char *p ;
{
struct nr4cb *cb = (struct nr4cb *)p ;
struct nr4hdr rhdr ;
#ifdef NR4DEBUG
printf("ACKIT called.\n") ;
#endif
if (cb->qfull) /* Are we choked? */
rhdr.opcode = NR4OPACK | NR4CHOKE ;
else
rhdr.opcode = NR4OPACK ;
rhdr.yourindex = cb->yournum ;
rhdr.yourid = cb->yourid ;
rhdr.u.ack.rxseq = cb->rxpected ;
nr4sframe(&cb->node, &rhdr, NULLBUF) ;
}
/* Called when one of the transmit timers has expired */
void
nr4txtimeout(p)
char *p ;
{
struct nr4cb *cb = (struct nr4cb *)p ;
unsigned seq ;
struct nr4txbuf *t ;
/* Sanity check */
if (cb->state != NR4STCON)
return ;
/* Scan through the send window looking for expired timers */
for (seq = cb->ackxpected ;
nr4between(cb->ackxpected, seq, cb->nextosend) ;
seq = (seq + 1) & NR4SEQMASK) {
t = &cb->txbufs[seq % cb->window] ;
if (t->tretry.state == TIMER_EXPIRE) {
t->tretry.state = TIMER_STOP ; /* So we don't do it again */
if (t->retries == Nr4retries) {
cb->dreason = NR4RTIMEOUT ;
nr4state(cb, NR4STDISC) ;
}
t->retries++ ;
/* We keep track of the highest retry count in the window. */
/* If packet times out and its new retry count exceeds the *
/* max, we update the max and bump the backoff level. This */
/* expedient is to avoid bumping the backoff level for every */
/* expiration, since with more than one timer we would back */
/* off way too fast (and at a rate dependent on the window */
/* size! */
if (t->retries > cb->txmax) {
cb->blevel++ ;
cb->txmax = t->retries ; /* update the max */
}
nr4sbuf(cb,seq) ; /* Resend buffer */
}
}
}
/* Connect/disconnect acknowledgement timeout */
void
nr4cdtimeout(p)
char *p ;
{
struct nr4cb *cb = (struct nr4cb *)p ;
struct nr4hdr hdr ;
switch(cb->state) {
case NR4STCPEND:
if (cb->cdtries == Nr4retries) { /* Have we tried long enough? */
cb->dreason = NR4RTIMEOUT ;
nr4state(cb, NR4STDISC) ; /* Give it up */
} else {
/* Set up header */
hdr.opcode = NR4OPCONRQ ;
hdr.u.conreq.myindex = cb->mynum ;
hdr.u.conreq.myid = cb->myid ;
hdr.u.conreq.window = Nr4window ;
hdr.u.conreq.user = cb->luser ;
hdr.u.conreq.node = mycall ;
/* Bump tries counter and backoff level, and restart timer */
/* We use a binary exponential backoff. */
cb->cdtries++ ;
cb->blevel++ ;
cb->tcd.start *= 2 ;
start_timer(&cb->tcd) ;
/* Send connect request packet */
nr4sframe(&cb->node, &hdr, NULLBUF) ;
}
break ;
case NR4STDPEND:
if (cb->cdtries == Nr4retries) { /* Have we tried long enough? */
cb->dreason = NR4RTIMEOUT ;
nr4state(cb, NR4STDISC) ; /* Give it up */
} else {
/* Format header */
hdr.opcode = NR4OPDISRQ ;
hdr.yourindex = cb->yournum ;
hdr.yourid = cb->yourid ;
/* Bump retry count and start timer */
/* We don't really need to be fancy here, since we */
/* should have a good idea of the round trip time by now. */
cb->cdtries++ ;
start_timer(&cb->tcd) ;
/* Send disconnect request packet */
nr4sframe(&cb->node, &hdr, NULLBUF) ;
}
break ;
}
}
/* The choke timer has expired. Unchoke and kick. */
void
nr4unchoke(p)
char *p ;
{
struct nr4cb *cb = (struct nr4cb *)p ;
cb->choked = 0 ;
nr4output(cb) ;
}