nr4user.c

嵌入式TCP/IP协议栈。 C 源码

/* net/rom level 4 (transport) protocol user level calls
 */

#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

/* Open a NET/ROM transport connection */
struct nr4cb *
open_nr4(local,remote,mode,r_upcall,t_upcall,s_upcall,user)
struct nr4_addr *local ;	/* local node address */
struct nr4_addr *remote ;	/* destination node address */
int mode ;			/* active/passive/server */
void (*r_upcall)(struct nr4cb *,uint16) ;	/* received data upcall */
void (*t_upcall)(struct nr4cb *,uint16) ;	/* transmit upcall */
void (*s_upcall)(struct nr4cb *,int,int) ;	/* state change upcall */
int user ;			/* user linkage area */
{
	struct nr4cb *cb ;
	struct nr4hdr hdr ;
	struct nr4_addr nr4tmp;

	if ((cb = new_n4circ()) == NULL)
		return NULL ;		/* No circuits available */

	if(remote == NULL){
		remote = &nr4tmp;
		setcall(remote->user," ");
		setcall(remote->node," ");
	}
	
	/* Stuff what info we can into control block */

	ASSIGN(cb->remote,*remote) ;
	/* Save local address for connect retries */
	ASSIGN(cb->local,*local) ;

	cb->r_upcall = r_upcall ;
	cb->t_upcall = t_upcall ;
	cb->s_upcall = s_upcall ;
	cb->user = user ;
	cb->clone = 0 ;

	switch(mode){
	case AX_SERVER:
		cb->clone = 1;
	case AX_PASSIVE:	/* Note fall-thru */
		cb->state = NR4STLISTEN;
		return cb;
	case AX_ACTIVE:
		break;
	}    
	/* Format connect request header */

	hdr.opcode = NR4OPCONRQ ;
	hdr.u.conreq.myindex = cb->mynum ;
	hdr.u.conreq.myid = cb->myid ;
	hdr.u.conreq.window = Nr4window ;
	memcpy(hdr.u.conreq.user,local->user,AXALEN);

	/* If I have a unique callsign per interface, then a layer violation */
	/* will be required to determine the "real" callsign for my */
	/* (virtual) node.  This suggests that callsign-per-interface is not */
	/* desirable, which answers *that* particular open question. */
	
	memcpy(hdr.u.conreq.node,local->node,AXALEN);

	/* Set and start connection retry timer */

	cb->cdtries = 1 ;
	cb->srtt = Nr4irtt ;
	set_timer(&cb->tcd,2 * cb->srtt);
	cb->tcd.func = nr4cdtimeout ;
	cb->tcd.arg = cb ;
	start_timer(&cb->tcd) ;
	
	/* Send connect request packet */

	nr4sframe(remote->node,&hdr,NULL) ;

	/* Set up initial state and signal state change */

	cb->state = NR4STDISC ;
	nr4state(cb, NR4STCPEND) ;

	/* Return control block address */

	return cb ;
}

/* Send a net/rom transport data packet */
int
send_nr4(
struct nr4cb *cb,
struct mbuf **bpp
){
	if(cb == NULL){
		free_p(bpp);
		return -1 ;
	}
	enqueue(&cb->txq,bpp) ;
	return nr4output(cb) ;
}

/* Receive incoming net/rom transport data */
struct mbuf *
recv_nr4(cb,cnt)
struct nr4cb *cb ;
uint16 cnt ;
{
	struct mbuf *bp ;

	if (cb->rxq == NULL)
		return NULL ;

	if (cnt == 0) {
		bp = cb->rxq ;			/* Just give `em everything */
		cb->rxq = NULL ;
	}
	else {
		bp = ambufw(cnt);
		bp->cnt = pullup(&cb->rxq,bp->data,cnt);
	}
	/* If this has un-choked us, reopen the window */
	if (cb->qfull && len_p(cb->rxq) < Nr4qlimit) {
		cb->qfull = 0 ;				/* Choke flag off */
		nr4ackit(cb) ;		/* Get things rolling again */
	}

	return bp ;
}

/* Close a NET/ROM connection */
void
disc_nr4(cb)
struct nr4cb *cb ;
{
	struct nr4hdr hdr ;
	
	if (cb->state == NR4STLISTEN) {
		free_n4circ(cb);
		return;
	}
	/* Format disconnect request packet */
	
	hdr.opcode = NR4OPDISRQ ;
	hdr.yourindex = cb->yournum ;
	hdr.yourid = cb->yourid ;

	/* Set and start timer */
	
	cb->cdtries = 1 ;
	set_timer(&cb->tcd,2 * cb->srtt);
	cb->tcd.func = nr4cdtimeout ;
	cb->tcd.arg = cb ;
	start_timer(&cb->tcd) ;

	/* Send packet */

	nr4sframe(cb->remote.node, &hdr, NULL) ;

	if(cb->state != NR4STCON){
		/* Connection not established; just blow it away */
		reset_nr4(cb);
		return;
	}
	/* Connection established, try to close it gracefully */
	/* Signal state change.  nr4state will take care of stopping */
	/* the appropriate timers and resetting window pointers. */
	nr4state(cb, NR4STDPEND) ;
}

/* Abruptly terminate a NET/ROM transport connection */
void
reset_nr4(cb)
struct nr4cb *cb ;
{
	cb->dreason = NR4RRESET ;
	nr4state(cb,NR4STDISC) ;
}


/* Force retransmission on a NET/ROM transport connection */
int
kick_nr4(cb)
struct nr4cb *cb ;
{
	unsigned seq ;
	struct timer *t ;

	if(!nr4valcb(cb))
		return -1 ;

	switch (cb->state) {
	  case NR4STCPEND:
	  case NR4STDPEND:
	  	stop_timer(&cb->tcd) ;
		nr4cdtimeout(cb) ;
		break ;

	  case NR4STCON:
	    if (cb->nextosend != cb->ackxpected) {	/* if send window is open: */
			for (seq = cb->ackxpected ;
				 nr4between(cb->ackxpected, seq, cb->nextosend) ;
				 seq = (seq + 1) & NR4SEQMASK) {
				t = &cb->txbufs[seq % cb->window].tretry ;
				stop_timer(t) ;
				t->state = TIMER_EXPIRE ;	/* fool retry routine */
			}
			nr4txtimeout(cb) ;
		}
		break ;
	}

	return 0 ;
}