/* Send and receive IP datagrams on serial lines. Compatible with SLIP
 * under Berkeley Unix.
 */
#ifdef	TRACE
#include <stdio.h>
#endif
#include "machdep.h"
#ifdef	TRACE
#include "trace.h"
#endif
#include "mbuf.h"
#include "iface.h"
#include "ax25.h"
#include "slip.h"
#ifdef	AMIGA
#include "amiga.h"
#else
#include "pc.h"
#endif

int slip_send();
int doslip();
int asy_output();

/* Slip level control structure */
struct slip slip[ASY_MAX];
unsigned nasy;

/* Send routine for point-to-point slip
 * This is a trivial function since there is no slip link-level header
 */
int
slip_send(bp,interface,gateway,precedence,delay,throughput,reliability)
struct mbuf *bp;		/* 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;
{
	/* Queue a frame on the slip output queue and start transmitter */

	if(interface == NULLIF){
		free_p(bp);
		return;
	}
#ifdef	TRACE
	if(trace & TRACE_SLIP){
		printf("%s sent:\r\n",interface->name);
		if((trace & TRACE_HDR) > 2)
			ip_dump(bp);
		if(trace & TRACE_DUMP)
			hexdump(bp);
		if(trace & TRACE_ASCII)
			asciidump(bp);
		fflush(stdout);
	}
#endif
	slipq(interface->dev,bp);
}
/* Encode a packet in slip framing, put on link output queue, and kick
 * transmitter
 */
slipq(dev,bp)
int16 dev;		/* Serial line number */
struct mbuf *bp;	/* Buffer to be sent */
{
	register struct slip *sp;
	struct mbuf *slip_encode();

	if((bp = slip_encode(bp)) == NULLBUF)
		return;	

	sp = &slip[dev];
	enqueue(&sp->sndq,bp);
	sp->sndcnt++;
	if(sp->tbp == NULLBUF)
		asy_start(dev);
}
/* Start output, if possible, on asynch device dev */
static
asy_start(dev)
int16 dev;
{
	register struct slip *sp;

	if(!stxrdy(dev))
		return;		/* Transmitter not ready */

	sp = &slip[dev];
	if(sp->tbp != NULLBUF){
		/* transmission just completed */
		free_p(sp->tbp);
		sp->tbp = NULLBUF;
	}
	if(sp->sndq == NULLBUF)
		return;	/* No work */

	sp->tbp = dequeue(&sp->sndq);
	sp->sndcnt--;
	asy_output(dev,sp->tbp->data,sp->tbp->cnt);
}
/* Encode a packet in SLIP format */
static
struct mbuf *
slip_encode(bp)
struct mbuf *bp;
{
	struct mbuf *lbp;	/* Mbuf containing line-ready packet */
	register char *cp;
	register int cnt;
	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;
	cnt = 0;

	/* Flush out any line garbage */
	*cp++ = FR_END;
	cnt++;

	/* Copy input to output, escaping special characters */
	while(pullup(&bp,&c,1) == 1){
		switch(c & 0xff){
		case FR_ESC:
			*cp++ = FR_ESC;
			*cp++ = T_FR_ESC;
			cnt += 2;
			break;
		case FR_END:
			*cp++ = FR_ESC;
			*cp++ = T_FR_END;
			cnt += 2;
			break;
		default:
			*cp++ = c;
			cnt++;
		}
	}
	*cp++ = FR_END;
	cnt++;
	lbp->cnt = cnt;
	return lbp;
}
/* Process incoming bytes in SLIP format
 * When a buffer is complete, return it; otherwise NULLBUF
 */
static
struct mbuf *
slip_decode(dev,c)
int dev;	/* Slip unit number */
char c;		/* Incoming character */
{
	struct mbuf *bp,*nbp;
	register struct slip *sp;

	sp = &slip[dev];
	switch(c & 0xff){
	case FR_END:
		if(sp->rbp != NULLBUF){
			/* Kick upstairs */
			bp = sp->rbp;
			sp->rbp = NULLBUF;
			sp->rcnt = 0;
			/* Copy into contiguous buffer, if necessary */
			if(bp->next != NULLBUF){
				nbp = copy_p(bp,len_mbuf(bp));
				free_p(bp);
				bp = nbp;
			}
			return bp;
		}
		return NULLBUF;
	case FR_ESC:
		sp->escaped = 1;
		return NULLBUF;
	}
	if(sp->escaped){
		sp->escaped = 0;
		switch(c & 0xff){
		case T_FR_ESC:
			c = FR_ESC;
			break;
		case T_FR_END:
			c = FR_END;
			break;
		default:
			sp->errors++;
		}
	}
	if(sp->rcnt == SLIP_MTU){
		/* Packet is too large, drop it and start over */
		free_p(sp->rbp);
		sp->rbp = NULLBUF;
		sp->rcnt = 0;
		return NULLBUF;
	}
	/* 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;
{
	char c;
	struct mbuf *bp;
	int16 dev;

	dev = interface->dev;
	/* Process any pending input */
	while(asy_recv(dev,&c,1) != 0)
		if((bp = slip_decode(dev,c)) != NULLBUF)
			(*slip[dev].recv)(interface,bp);

	/* Kick the transmitter if it's idle */
	if(stxrdy(dev))
		asy_start(dev);
}
/* Unwrap incoming SLIP packets -- trivial operation since there's no
 * link level header
 */
slip_recv(interface,bp)
struct interface *interface;
struct mbuf *bp;
{
#ifdef	TRACE
	if(trace & TRACE_SLIP){
		printf("%s recv:\r\n",interface->name);
		if((trace & TRACE_HDR) > 2)
			ip_dump(bp);
		if(trace & TRACE_DUMP)
			hexdump(bp);
		if(trace & TRACE_ASCII)
			asciidump(bp);
		fflush(stdout);
	}
#endif
	ip_route(bp,0);
} 
/* Attach a serial interface to the system
 * argv[0]: hardware type, must be "asy"
 * argv[1]: I/O address, e.g., "0x3f8"
 * argv[2]: vector, e.g., "4"
 * argv[3]: mode, may be:
 *	    "slip" (point-to-point SLIP)
 *	    "ax25" (AX.25 UI frame format in SLIP for raw TNC)
 * argv[4]: interface label, e.g., "sl0"
 * argv[5]: receiver ring buffer size in bytes
 * argv[6]: maximum transmission unit, bytes
 * argv[7]: interface speed, e.g, "9600"
 */
asy_attach(argc,argv)
int argc;
char *argv[];
{
	register struct interface *if_asy;
	extern struct interface *ifaces;
	int dev;
	char *malloc(), *calloc();
	int asy_init();
	int asy_send();
	int doslip();
	int asy_stop();
	int ax_send();
	int kiss_recv();
	int kiss_output();

	if(nasy >= ASY_MAX){
		printf("Too many asynch controllers\r\n");
		return -1;
	}
	dev = nasy++;

	/* Initialize hardware-level control structure */
	asy[dev].addr = htoi(argv[1]);
	asy[dev].vec = htoi(argv[2]);

	/* Create interface structure and fill in details */
	if_asy = (struct interface *)calloc(1, sizeof(struct interface));

	if_asy->name = malloc(strlen(argv[4])+1);
	strcpy(if_asy->name,argv[4]);
	if_asy->mtu = atoi(argv[6]);
	if_asy->dev = dev;
	if_asy->recv = doslip;
	if_asy->stop = asy_stop;

	if(strcmp(argv[3],"slip") == 0){
		if_asy->send = slip_send;
		if_asy->output = NULLFP;
		if_asy->flags = 0;
		slip[dev].recv = slip_recv;
	}
	else if(strcmp(argv[3],"ax25") == 0){
		if_asy->send = ax_send;
		if_asy->output = kiss_output;
		if_asy->flags = IF_BROADCAST;
		if(if_asy->hwaddr == NULLCHAR)
			if_asy->hwaddr = malloc(AXALEN);
		bcopy((char *)&mycall,if_asy->hwaddr,AXALEN);
		slip[dev].recv = kiss_recv;
	}
	else {
		printf("Mode %s unknown for interface %s\r\n",
			argv[3],argv[4]);
		free((char *)if_asy);
		return -1;
	}
	if_asy->next = ifaces;
	ifaces = if_asy;
	asy_init(dev,(unsigned)atoi(argv[5]));
	asy_speed(dev,atoi(argv[7]));
}