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ax25.c
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1991-08-14
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/* Low level AX.25 code:
* incoming frame processing (including digipeating)
* IP encapsulation
* digipeater routing
*
* Copyright 1991 Phil Karn, KA9Q / 1991 Kevin Hil, G1EMM
*/
/* Mods by PA0GRI */
#include <stdio.h>
#include "global.h"
#include "config.h"
#include "mbuf.h"
#include "iface.h"
#include "arp.h"
#include "slip.h"
#include "ax25.h"
#include "lapb.h"
#include "netrom.h"
#include "ip.h"
#include "devparam.h"
#include "trace.h"
#include "pktdrvr.h"
#include "netuser.h"
#include "commands.h"
#include <ctype.h>
static int axsend __ARGS((struct iface *iface,char *dest,char *source,
int cmdrsp,int ctl,struct mbuf *data));
static int axip_stop __ARGS((struct iface *iface));
static int axip_raw __ARGS((struct iface *iface,struct mbuf *bp));
/* List of AX.25 multicast addresses in network format (shifted ascii).
* Only the first entry is used for transmissions, but any incoming
* packet with any one of these destination addresses is recognized
* as a multicast
*/
char Ax25multi[][AXALEN] = {
'Q'<<1, 'S'<<1, 'T'<<1, ' '<<1, ' '<<1, ' '<<1, '0'<<1, /* QST */
'M'<<1, 'A'<<1, 'I'<<1, 'L'<<1, ' '<<1, ' '<<1, '0'<<1, /* MAIL */
'N'<<1, 'O'<<1, 'D'<<1, 'E'<<1, 'S'<<1, ' '<<1, '0'<<1, /* NODES */
'I'<<1, 'D'<<1, ' '<<1, ' '<<1, ' '<<1, ' '<<1, '0'<<1, /* ID */
'O'<<1, 'P'<<1, 'E'<<1, 'N'<<1, ' '<<1, ' '<<1, '0'<<1, /* OPEN */
'C'<<1, 'Q'<<1, ' '<<1, ' '<<1, ' '<<1, ' '<<1, '0'<<1, /* CQ */
'B'<<1, 'E'<<1, 'A'<<1, 'C'<<1, 'O'<<1, 'N'<<1, '0'<<1, /* BEACON */
'R'<<1, 'M'<<1, 'N'<<1, 'C'<<1, ' '<<1, ' '<<1, '0'<<1, /* RMNC */
'A'<<1, 'L'<<1, 'L'<<1, ' '<<1, ' '<<1, ' '<<1, '0'<<1, /* ALL */
'\0',
};
char Mycall[AXALEN];
struct ax_route *Ax_routes; /* Routing table header */
int Digipeat = 1; /* Controls digipeating */
#ifdef AXIP
static int32 axipaddr[NAX25]; /* table of IP addresses of AX.25 interfaces */
#ifdef PPP
extern int16 fcstab[]; /* table used when calculating FCS */
#else
int16 fcstab[256] = {
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
#endif
#endif
/* Send IP datagrams across an AX.25 link */
int
ax_send(bp,iface,gateway,prec,del,tput,rel)
struct mbuf *bp;
struct iface *iface;
int32 gateway;
int prec;
int del;
int tput;
int rel;
{
char *hw_addr;
struct ax25_cb *axp;
struct mbuf *tbp;
struct ax_route *axr;
char mode = AX_DEFMODE; /* default to interface mode */
if(gateway == iface->broadcast) /* This is a broadcast IP datagram */
return (*iface->output)(iface,Ax25multi[0],iface->hwaddr,PID_IP,bp);
if((hw_addr = res_arp(iface,ARP_AX25,gateway,bp)) == NULLCHAR)
return 0; /* Wait for address resolution */
/* If there's a defined route, get it */
axr = ax_lookup(hw_addr);
if(axr == NULLAXR) {
if(iface->flags == DATAGRAM_MODE){
mode = AX_DATMODE;
} else {
mode = AX_VC_MODE;
}
} else {
mode = axr->mode;
if(mode == AX_DEFMODE) {
if(iface->flags == DATAGRAM_MODE){
mode = AX_DATMODE;
} else {
mode = AX_VC_MODE;
}
}
}
/* UI frames are used for any one of the following three conditions:
* 1. The "low delay" bit is set in the type-of-service field.
* 2. The "reliability" TOS bit is NOT set and the interface is in
* datagram mode.
* 3. The destination is the broadcast address (this is helpful
* when broadcasting on an interface that's in connected mode).
*/
if(del || (!rel && (mode == AX_DATMODE))
|| addreq(hw_addr,Ax25multi[0])){
/* Use UI frame */
return (*iface->output)(iface,hw_addr,iface->hwaddr,PID_IP,bp);
}
/* Reliability is needed; use I-frames in AX.25 connection */
if((axp = find_ax25(hw_addr)) == NULLAX25){
/* Open a new connection */
axp = open_ax25(iface,iface->hwaddr,hw_addr,
AX_ACTIVE,Axwindow,s_arcall,s_atcall,s_ascall,-1);
if(axp == NULLAX25){
free_p(bp);
return -1;
}
}
if(axp->state == LAPB_DISCONNECTED){
est_link(axp);
lapbstate(axp,LAPB_SETUP);
}
/* Insert the PID */
if((tbp = pushdown(bp,1)) == NULLBUF){
free_p(bp);
return -1;
}
bp = tbp;
bp->data[0] = PID_IP;
if((tbp = segmenter(bp,axp->paclen)) == NULLBUF){
free_p(bp);
return -1;
}
return send_ax25(axp,tbp,-1);
}
/* Add header and send connectionless (UI) AX.25 packet.
* Note that the calling order here must match enet_output
* since ARP also uses it.
*/
int
ax_output(iface,dest,source,pid,data)
struct iface *iface; /* Interface to use; overrides routing table */
char *dest; /* Destination AX.25 address (7 bytes, shifted) */
char *source; /* Source AX.25 address (7 bytes, shifted) */
int16 pid; /* Protocol ID */
struct mbuf *data; /* Data field (follows PID) */
{
struct mbuf *bp;
/* Prepend pid to data */
bp = pushdown(data,1);
if(bp == NULLBUF){
free_p(data);
return -1;
}
bp->data[0] = (char)pid;
return axsend(iface,dest,source,LAPB_COMMAND,UI,bp);
}
/* Common subroutine for sendframe() and ax_output() */
static int
axsend(iface,dest,source,cmdrsp,ctl,data)
struct iface *iface; /* Interface to use; overrides routing table */
char *dest; /* Destination AX.25 address (7 bytes, shifted) */
char *source; /* Source AX.25 address (7 bytes, shifted) */
int cmdrsp; /* Command/response indication */
int ctl; /* Control field */
struct mbuf *data; /* Data field (includes PID) */
{
struct mbuf *cbp;
struct ax25 addr;
struct ax_route *axr;
char *idest;
int rval;
/* If the source addr is unspecified, use the interface address */
if(source[0] == '\0')
source = iface->hwaddr;
/* If there's a digipeater route, get it */
axr = ax_lookup(dest);
memcpy(addr.dest,dest,AXALEN);
memcpy(addr.source,source,AXALEN);
addr.cmdrsp = cmdrsp;
if(axr != NULLAXR){
memcpy(addr.digis,axr->digis,axr->ndigis*AXALEN);
addr.ndigis = axr->ndigis;
idest = addr.digis[0];
} else {
addr.ndigis = 0;
idest = dest;
}
addr.nextdigi = 0;
/* Allocate mbuf for control field, and fill in */
if((cbp = pushdown(data,1)) == NULLBUF){
free_p(data);
return -1;
}
cbp->data[0] = ctl;
if((data = htonax25(&addr,cbp)) == NULLBUF){
free_p(cbp); /* Also frees data */
return -1;
}
/* This shouldn't be necessary because redirection has already been
* done at the IP router layer, but just to be safe...
*/
if(iface->forw != NULLIF){
logsrc(iface->forw,iface->forw->hwaddr);
logdest(iface->forw,idest);
rval = (*iface->forw->raw)(iface->forw,data);
} else {
logsrc(iface,iface->hwaddr);
logdest(iface,idest);
rval = (*iface->raw)(iface,data);
}
return rval;
}
#ifdef AXIP
/* Handle AX.25 frames received inside IP according to RFC-1226 */
void
axip_input(iface,ip,bp,rxbroadcast)
struct iface *iface; /* Input interface */
struct ip *ip; /* IP header */
struct mbuf *bp; /* AX.25 frame with FCS */
int rxbroadcast; /* Accepted for now */
{
int i;
struct mbuf *tbp;
int16 len, f, fcs = 0xffff;
/* Since the AX.25 frame arrived on an interface that does
not necessarily support AX.25, we have to find a suitable
AX.25 interface, or drop the packet.
*/
/* Try to find a matching AX.25 pseudo interface */
for(i=0; i < NAX25; ++i)
if(axipaddr[i] == ip->source)
break;
if(i == NAX25) {
/* Here we could still try to pick a real AX.25 interface,
but that would mean that we are accepting AX.25 frames
from unknown IP hosts, so we'd rather drop it.
*/
free_p(bp);
return;
}
iface = Ifaces;
while (iface != NULLIF) {
if(iface->raw == axip_raw && iface->dev == i)
/* found the right AX.25 pseudo interface */
break;
iface = iface->next;
}
if(iface == NULLIF) {
free_p(bp);
return;
}
len = len_p(bp) - sizeof(fcs);
if(dup_p(&tbp,bp,0,len) != len) {
free_p(bp);
return;
}
while(len--)
fcs = (fcs >> 8) ^ fcstab[(fcs ^ PULLCHAR(&bp)) & 0x00ff];
fcs ^= 0xffff;
f = PULLCHAR(&bp);
f |= (PULLCHAR(&bp) << 8);
if(fcs == f){
ax_recv(iface,tbp);
} else
free_p(tbp);
}
#endif
/* Process incoming AX.25 packets.
* After optional tracing, the address field is examined. If it is
* directed to us as a digipeater, repeat it. If it is addressed to
* us or to QST-0, kick it upstairs depending on the protocol ID.
*/
void
ax_recv(iface,bp)
struct iface *iface;
struct mbuf *bp;
{
struct mbuf *hbp;
char control;
struct ax25 hdr;
struct ax25_cb *axp;
struct ax_route *axr;
struct iface *cross;
char (*mpp)[AXALEN];
int mcast;
char *isrc,*idest; /* "immediate" source and destination */
/* Pull header off packet and convert to host structure */
if(ntohax25(&hdr,&bp) < 0){
/* Something wrong with the header */
free_p(bp);
return;
}
/* If there were digis in this packet and at least one has
* been passed, then the last passed digi is the immediate source.
* Otherwise it is the original source.
*/
if(hdr.ndigis != 0 && hdr.nextdigi != 0)
isrc = hdr.digis[hdr.nextdigi-1];
else
isrc = hdr.source;
/* If there are digis in this packet and not all have been passed,
* then the immediate destination is the next digi. Otherwise it
* is the final destination.
*/
cross = NULLIF;
if(hdr.ndigis != 0 && hdr.nextdigi != hdr.ndigis){
idest = hdr.digis[hdr.nextdigi];
if(!addreq(idest,iface->hwaddr)){
/* Check if digi matches callsign of any other
* interface for crossband digipeating.
*/
for(cross = Ifaces; cross != NULLIF; cross = cross->next){
if(cross->type == CL_AX25 &&
addreq(idest,cross->hwaddr)) {
/* Swap callsigns so that the reply
* can be crossband digipeated in
* the other direction.
*/
memcpy(idest,iface->hwaddr,AXALEN);
break;
}
}
}
}
else
idest = hdr.dest;
/* Don't log our own packets if we overhear them, as they're
* already logged by axsend() and by the digipeater code.
*/
if(!addreq(isrc,iface->hwaddr)){
logsrc(iface,isrc);
logdest(iface,idest);
}
/* Examine immediate destination for a multicast address */
mcast = 0;
for(mpp = Ax25multi;(*mpp)[0] != '\0';mpp++){
if(addreq(idest,*mpp)){
mcast = 1;
break;
}
}
if(!mcast && !cross && !addreq(idest,iface->hwaddr)){
/* Not a broadcast, and not addressed to us. Inhibit
* transmitter to avoid colliding with addressed station's
* response, and discard packet.
*/
if(iface->ioctl != NULL){
(*iface->ioctl)(iface,PARAM_MUTE,1,-1L);
}
free_p(bp);
return;
}
if(!mcast && !cross && iface->ioctl != NULL){
/* Packet was sent to us; abort transmit inhibit */
(*iface->ioctl)(iface,PARAM_MUTE,1,0L);
}
/* At this point, packet is either addressed to us, or is
* a multicast.
*/
if(hdr.nextdigi < hdr.ndigis){
/* Packet requests digipeating. See if we can repeat it. */
if(Digipeat && !mcast){
/* Yes, kick it back out. htonax25 will set the
* repeated bit.
*/
hdr.nextdigi++;
if((hbp = htonax25(&hdr,bp)) != NULLBUF){
logsrc(iface,iface->hwaddr);
if(cross) /* Crossband digipeat */
iface = cross;
if(iface->forw != NULLIF){
logdest(iface->forw,hdr.digis[hdr.nextdigi]);
(*iface->forw->raw)(iface->forw,hbp);
} else {
logdest(iface,hdr.digis[hdr.nextdigi]);
(*iface->raw)(iface,hbp);
}
bp = NULLBUF;
}
}
free_p(bp); /* Dispose if not forwarded */
return;
}
/* If we reach this point, then the packet has passed all digis,
* and is either addressed to us or is a multicast
*/
if(bp == NULLBUF){
return; /* Nothing left */
}
/* If there's no locally-set entry in the routing table and
* this packet has digipeaters, create or update it. Leave
* local routes alone.
*/
if(((axr = ax_lookup(hdr.source)) == NULLAXR || axr->type == AX_AUTO)
&& hdr.ndigis > 0){
char digis[MAXDIGIS][AXALEN];
int i,j;
/* Construct reverse digipeater path */
for(i=hdr.ndigis-1,j=0;i >= 0;i--,j++){
memcpy(digis[j],hdr.digis[i],AXALEN);
digis[j][ALEN] &= ~(E|REPEATED);
}
ax_add(hdr.source,AX_AUTO,digis,hdr.ndigis);
}
/* Sneak a peek at the control field. This kludge is necessary because
* AX.25 lacks a proper protocol ID field between the address and LAPB
* sublayers; a control value of UI indicates that LAPB is to be
* bypassed.
*/
control = *bp->data & ~PF;
if(uchar(control) == UI){
int pid;
struct axlink *ipp;
(void) PULLCHAR(&bp);
if((pid = PULLCHAR(&bp)) == -1)
return; /* No PID */
/* Find network level protocol and hand it off */
for(ipp = Axlink;ipp->funct != NULL;ipp++){
if(ipp->pid == pid)
break;
}
if(ipp->funct != NULL)
(*ipp->funct)(iface,NULLAX25,hdr.source,hdr.dest,bp,mcast);
else
free_p(bp);
return;
}
/* Everything from here down is connected-mode LAPB, so ignore
* multicasts
*/
if(mcast){
free_p(bp);
return;
}
/* Find the source address in hash table */
if((axp = find_ax25(hdr.source)) == NULLAX25){
/* Create a new ax25 entry for this guy,
* insert into hash table keyed on his address,
* and initialize table entries
*/
if((axp = cr_ax25(hdr.source)) == NULLAX25){
free_p(bp);
return;
}
/* Swap source and destination */
memcpy(axp->remote,hdr.source,AXALEN);
memcpy(axp->local,hdr.dest,AXALEN);
axp->iface = iface;
}
if(hdr.cmdrsp == LAPB_UNKNOWN)
axp->proto = V1; /* Old protocol in use */
lapb_input(axp,hdr.cmdrsp,bp);
}
/* General purpose AX.25 frame output */
int
sendframe(axp,cmdrsp,ctl,data)
struct ax25_cb *axp;
int cmdrsp;
int ctl;
struct mbuf *data;
{
return axsend(axp->iface,axp->remote,axp->local,cmdrsp,ctl,data);
}
/* Find a route for an AX.25 address */
struct ax_route *
ax_lookup(target)
char *target;
{
register struct ax_route *axr;
struct ax_route *axlast = NULLAXR;
for(axr = Ax_routes; axr != NULLAXR; axlast = axr,axr = axr->next){
if(memcmp(axr->target,target,AXALEN) == 0){
if(axr != Ax_routes){
/* Move entry to top of list to speed
* future searches
*/
axlast->next = axr->next;
axr->next = Ax_routes;
Ax_routes = axr;
}
return axr;
}
}
return axr;
}
/* Add an entry to the AX.25 routing table */
struct ax_route *
ax_add(target,type,digis,ndigis)
char *target;
int type;
char digis[][AXALEN];
int ndigis;
{
register struct ax_route *axr;
if(ndigis < 0 || ndigis > MAXDIGIS)
return NULLAXR;
if((axr = ax_lookup(target)) == NULLAXR){
axr = (struct ax_route *)callocw(1,sizeof(struct ax_route));
axr->next = Ax_routes;
Ax_routes = axr;
memcpy(axr->target,target,AXALEN);
axr->ndigis = ndigis;
}
axr->type = type;
axr->mode = AX_DEFMODE; /* set mode to default */
if(axr->ndigis != ndigis)
axr->ndigis = ndigis;
memcpy(axr->digis,digis[0],ndigis*AXALEN);
return axr;
}
int
ax_drop(target)
char *target;
{
register struct ax_route *axr;
struct ax_route *axlast = NULLAXR;
for(axr = Ax_routes;axr != NULLAXR;axlast=axr,axr = axr->next)
if(memcmp(axr->target,target,AXALEN) == 0)
break;
if(axr == NULLAXR)
return -1; /* Not in table! */
if(axlast != NULLAXR)
axlast->next = axr->next;
else
Ax_routes = axr->next;
free((char *)axr);
return 0;
}
/* Handle ordinary incoming data (no network protocol) */
void
axnl3(iface,axp,src,dest,bp,mcast)
struct iface *iface;
struct ax25_cb *axp;
char *src;
char *dest;
struct mbuf *bp;
int mcast;
{
if(axp == NULLAX25){
beac_input(iface,src,bp);
} else {
append(&axp->rxq,bp);
if(axp->r_upcall != NULLVFP)
(*axp->r_upcall)(axp,len_p(axp->rxq));
}
}
#ifdef AXIP
/* attach a fake AX.25 interface for AX.25 on top of IP */
/* argv[0] == "axip"
* argv[1] == name of new interface
* argv[2] == MTU
* argv[3] == hostname of remote end of wormhole
* argv[4] == optional AX.25 callsign for this interface, must be specified
* and be different from any other interface callsign if crossband
* digipeating is going to work properly
*/
int
axip_attach(argc,argv,p)
int argc;
char *argv[];
void *p;
{
int i;
struct iface *ifp;
if(if_lookup(argv[1]) != NULLIF) {
tprintf("interface %s already attached\n",argv[1]);
return -1;
}
for(i=0; i < NAX25; ++i)
if(axipaddr[i] == 0)
break;
if(i == NAX25) {
tprintf("too many AX25 interfaces attached\n");
return -1;
}
if((axipaddr[i] = resolve(argv[3])) == 0) {
tprintf("invalid address\n");
return -1;
}
if(!Digipeat)
tprintf("Warning: AX.25 Digipeating is still disabeled!\n");
ifp = (struct iface *)callocw(1,sizeof(struct iface));
ifp->dev = i;
ifp->addr = Ip_addr;
ifp->name = strdup(argv[1]);
ifp->hwaddr = mallocw(AXALEN);
memcpy(ifp->hwaddr,Mycall,AXALEN);
ifp->mtu = atoi(argv[2]);
setencap(ifp,"AX25");
if(argc > 4) {
ifp->hwaddr = mallocw(ifp->iftype->hwalen);
(*ifp->iftype->scan)(ifp->hwaddr,argv[4]);
}
ifp->raw = axip_raw;
ifp->stop = axip_stop;
ifp->next = Ifaces;
Ifaces = ifp;
return 0;
}
static int
axip_stop(iface)
struct iface *iface;
{
axipaddr[iface->dev] = 0;
return 0;
}
/* raw routine for sending AX.25 on top of IP */
static int
axip_raw(iface,bp)
struct iface *iface; /* Pointer to interface control block */
struct mbuf *bp; /* Data field */
{
int16 len, fcs = 0xffff;
struct mbuf *bp1;
dump(iface,IF_TRACE_OUT,iface->type,bp);
iface->rawsndcnt++;
iface->lastsent = secclock();
len = len_p(bp);
if(dup_p(&bp1,bp,0,len) != len) {
free_p(bp);
return -1;
}
while (len--) /* calculate FCS */
fcs = (fcs >> 8) ^ fcstab[(fcs ^ PULLCHAR(&bp1)) & 0x00ff];
fcs ^= 0xffff; /* final FCS (is this right?) */
if((bp1 = alloc_mbuf(sizeof (fcs))) == NULLBUF) {
free_p(bp);
return -1;
}
*bp1->data = fcs & 0xff;
*(bp1->data+1) = (fcs >> 8) & 0xff;
bp1->cnt += sizeof(fcs);
append(&bp,bp1);
return ip_send(INADDR_ANY,axipaddr[iface->dev],AX25_PTCL,0,0,bp,0,0,0);
}
#endif