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SOURCE.ARC
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SLIP.C
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C/C++ Source or Header
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1990-07-22
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7KB
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308 lines
/* Send and receive IP datagrams on serial lines. Compatible with SLIP
* under Berkeley Unix.
*/
#include <stdio.h>
#include "global.h"
#include "mbuf.h"
#include "iface.h"
#include "ax25.h"
#include "slip.h"
#include "asy.h"
#include "combios.h"
#include "trace.h"
/* Slip level control structure */
struct slip slip[ASY_MAX];
static int asy_start();
/* Send routine for point-to-point slip
* This is a trivial function since there is no slip link-level header
*/
int
slip_send(data,interface,gateway,precedence,delay,throughput,reliability)
struct mbuf *data; /* Buffer to send */
struct interface *interface; /* Pointer to interface control block */
int32 gateway; /* Ignored (SLIP is point-to-point) */
char precedence;
char delay;
char throughput;
char reliability;
{
if(interface == NULLIF){
free_p(data);
return -1;
}
dump(interface,IF_TRACE_OUT,TRACE_IP,data);
return (*interface->raw)(interface,data);
}
/* Send a raw slip frame -- also trivial */
int
slip_raw(interface,data)
struct interface *interface;
struct mbuf *data;
{
/* Queue a frame on the slip output queue and start transmitter */
return slipq(interface->dev,data);
}
/* Encode a raw packet in slip framing, put on link output queue, and kick
* transmitter
*/
static int
slipq(dev,data)
int16 dev; /* Serial line number */
struct mbuf *data; /* Buffer to be sent */
{
register struct slip *sp;
struct mbuf *slip_encode(),*bp;
if((bp = slip_encode(data)) == NULLBUF)
return -1;
sp = &slip[dev];
enqueue(&sp->sndq,bp);
sp->sndcnt++;
if(sp->tbp == NULLBUF)
asy_start(dev);
return 0;
}
/* Start output, if possible, on asynch device dev */
static int
asy_start(dev)
int16 dev;
{
register struct slip *sp;
int asy_output();
#ifdef COMBIOS
struct com *cp;
unsigned char c;
unsigned stat;
int numsend;
#endif
#ifdef COMBIOS
com[dev].stat |= (stat = combios(0x0300,dev));
if(!(stat & 0x2000))
#else
if(!stxrdy(dev))
#endif
return -1; /* Transmitter not ready */
sp = &slip[dev];
if(sp->tbp != NULLBUF){
#ifdef COMBIOS
goto comsend; /* still something to send */
#else
/* transmission just completed */
free_p(sp->tbp);
sp->tbp = NULLBUF;
#endif
}
if(sp->sndq == NULLBUF)
return 0; /* No work */
sp->tbp = dequeue(&sp->sndq);
sp->sndcnt--;
#ifdef COMBIOS
comsend:
cp = &com[dev]; /* quick ptr to our com */
if ((numsend = cp->txbuf) == 0)
numsend = cp->speed; /* enough for 10 seconds */
while(--numsend && pullup(&sp->tbp,&c,1) == 1) {
cp->stat |= (stat = combios(0x0100 | c,dev)) & 0x7f00;
if (cp->txbuf == 0 && /* no explicit tx buffer max */
(stat & 0xa000) != 0x2000) /* timeout or full */
break;
}
#else
asy_output(dev,sp->tbp->data,sp->tbp->cnt);
#endif
return 1;
}
/* Encode a packet in SLIP format */
struct mbuf *
slip_encode(bp)
struct mbuf *bp;
{
struct mbuf *lbp; /* Mbuf containing line-ready packet */
register char *cp;
char c;
/* Allocate output mbuf that's twice as long as the packet.
* This is a worst-case guess (consider a packet full of FR_ENDs!)
*/
lbp = alloc_mbuf(2*len_mbuf(bp) + 2);
if(lbp == NULLBUF){
/* No space; drop */
free_p(bp);
return NULLBUF;
}
cp = lbp->data;
/* Flush out any line garbage */
*cp++ = FR_END;
/* Copy input to output, escaping special characters */
while(pullup(&bp,&c,1) == 1){
switch(uchar(c)){
case FR_ESC:
*cp++ = FR_ESC;
*cp++ = T_FR_ESC;
break;
case FR_END:
*cp++ = FR_ESC;
*cp++ = T_FR_END;
break;
default:
*cp++ = c;
}
}
*cp++ = FR_END;
lbp->cnt = cp - lbp->data;
return lbp;
}
/* Process incoming bytes in SLIP format
* When a buffer is complete, return it; otherwise NULLBUF
*/
struct mbuf *
slip_decode(sp,c)
register struct slip *sp; /* Slip level control struct */
char c; /* Incoming character */
{
struct mbuf *bp;
switch(uchar(c)){
case FR_END:
bp = sp->rbp;
sp->rbp = NULLBUF;
sp->rcnt = 0;
return bp; /* Will be NULLBUF if empty frame */
case FR_ESC:
sp->escaped = 1;
return NULLBUF;
}
if(sp->escaped){
/* Translate 2-char escape sequence back to original char */
sp->escaped = 0;
switch(uchar(c)){
case T_FR_ESC:
c = FR_ESC;
break;
case T_FR_END:
c = FR_END;
break;
default:
sp->errors++;
break;
}
}
/* We reach here with a character for the buffer;
* make sure there's space for it
*/
if(sp->rbp == NULLBUF){
/* Allocate first mbuf for new packet */
if((sp->rbp1 = sp->rbp = alloc_mbuf(SLIP_ALLOC)) == NULLBUF)
return NULLBUF; /* No memory, drop */
sp->rcp = sp->rbp->data;
} else if(sp->rbp1->cnt == SLIP_ALLOC){
/* Current mbuf is full; link in another */
if((sp->rbp1->next = alloc_mbuf(SLIP_ALLOC)) == NULLBUF){
/* No memory, drop whole thing */
free_p(sp->rbp);
sp->rbp = NULLBUF;
sp->rcnt = 0;
return NULLBUF;
}
sp->rbp1 = sp->rbp1->next;
sp->rcp = sp->rbp1->data;
}
/* Store the character, increment fragment and total
* byte counts
*/
*sp->rcp++ = c;
sp->rbp1->cnt++;
sp->rcnt++;
return NULLBUF;
}
/* Process SLIP line I/O */
int
doslip(interface)
struct interface *interface;
{
#ifdef COMBIOS
unsigned stat;
#else
char c;
#endif
struct mbuf *bp;
register struct slip *sp;
int16 dev;
int rv = 0;
int16 asy_recv();
dev = interface->dev;
sp = &slip[dev];
#ifdef COMBIOS
/* Process any pending input */
fossil:
com[dev].stat |= (stat = combios(0x0300,dev));
while(stat & 0x0100) {
com[dev].stat |= (stat = combios(0x0200,dev));
if((bp = slip_decode(sp,stat & 0xff)) != NULLBUF) {
if (com[dev].stat & 0x1a00) /* error detected? */
free(bp); /* discard frame */
else
(*sp->recv)(interface,bp);
com[dev].stat = 0;
rv++;
}
if(com[dev].drtype == 3)
goto fossil; /* FOSSIL needs new status */
}
/* Kick the transmitter if it's idle */
if(stat & 0x2000)
if (asy_start(dev))
rv++;
#else
/* Process any pending input */
while(asy_recv(dev,&c,1) != 0)
if((bp = slip_decode(sp,c)) != NULLBUF){
(*sp->recv)(interface,bp);
rv++;
}
/* Kick the transmitter if it's idle */
if(sp->sndq != NULLBUF){
asy_start(dev);
rv++;
}
#endif
return rv; /* processed packets */
}
/* Unwrap incoming SLIP packets -- trivial operation since there's no
* link level header
*/
void
slip_recv(interface,bp)
struct interface *interface;
struct mbuf *bp;
{
int ip_route();
/* By definition, all incoming packets are "addressed" to us */
dump(interface,IF_TRACE_IN,TRACE_IP,bp);
ip_route(bp,0);
}