ppp_tty.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

 * FCS lookup table as calculated by genfcstab.
 */
static u_short 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
};

/*
 * Calculate a new FCS given the current FCS and the new data.
 */
u_short
pppfcs(u_short fcs, u_char *cp, int len)
{
    while (len--)
	fcs = PPP_FCS(fcs, *cp++);
    return (fcs);
}

/*
 * This gets called at splsoftnet from if_ppp.c at various times
 * when there is data ready to be sent.
 */
void pppasyncstart(struct ppp_softc *sc)
{
  /* check to see if output is not active */
  if ( sc->sc_outflag == 0 ) {
    /* mark active and post tx event to daemon */
    sc->sc_outflag |= SC_TX_PENDING;
    rtems_event_send(sc->sc_txtask, TX_PACKET);
  }
}

/*
 * This gets called when a received packet is placed on
 * the inq, at splsoftnet.
 */
static void
pppasyncctlp(sc)
    struct ppp_softc *sc;
{
  /* check to see if task id was set */
  if ( sc->sc_pppdtask != 0 ) {
    /* post event to daemon */
    rtems_event_send(sc->sc_pppdtask, PPPD_EVENT);
  }
}

/*
 * Start output on async tty interface.  If the transmit queue
 * has drained sufficiently, arrange for pppasyncstart to be
 * called later at splsoftnet.
 * Called at spltty or higher.
 */
int
pppstart(struct rtems_termios_tty *tp)
{
  char               *sendBegin;
  u_long              ioffset = (u_long       )0;
  struct mbuf        *m       = (struct mbuf *)0;
  struct ppp_softc   *sc      = tp->t_sc;

  /* ensure input is valid and we are busy */
  if (( sc != NULL ) && ( sc->sc_outflag & SC_TX_BUSY )) {
    /* check to see if we need to get the next buffer */

    /* Ready with PPP_FLAG Character ? */
    if(sc->sc_outflag & SC_TX_LASTCHAR){
        sc->sc_outflag &= ~(SC_TX_BUSY | SC_TX_FCS | SC_TX_LASTCHAR);
        rtems_event_send(sc->sc_txtask, TX_TRANSMIT);	/* Ready for the next Packet */
        return(0);
    }

    if ( sc->sc_outoff >= sc->sc_outlen ) {
      /* loop to get next non-zero length buffer */
      if ( sc->sc_outmc != NULL ) {
        m = sc->sc_outmc->m_next;
      }

      /* check for next mbuf in chain */
      if ( m != NULL ) {
        /* update values to use this mbuf */
        sc->sc_outmc  = m;
        sc->sc_outbuf = mtod(m, u_char *);
        sc->sc_outlen = m->m_len;
        sc->sc_outoff = (short)0;
      }
      else if ( (sc->sc_outflag & SC_TX_FCS) == 0 ) {
        /* setup to use FCS buffer */
        sc->sc_outflag |= SC_TX_FCS;
        sc->sc_outbuf   = sc->sc_outfcsbuf;
        sc->sc_outlen   = sc->sc_outfcslen;
        sc->sc_outoff   = (short)0;
      }
      else {
        /* done with this packet */
        sc->sc_outflag |= SC_TX_LASTCHAR;
        sc->sc_outflag &=~(SC_TX_FCS);
		sc->sc_outchar = (u_char)PPP_FLAG;
        (*tp->device.write)(tp->minor, &sc->sc_outchar, 1);
        return(0);
      }
    }

    /* check to see if there is some data to write out */
    if ( sc->sc_outoff < sc->sc_outlen ) {
      /* check to see if character needs to be escaped */
      sc->sc_outchar = sc->sc_outbuf[sc->sc_outoff];
      if ( ESCAPE_P(sc->sc_outchar) ) {
        if ( sc->sc_outflag & SC_TX_ESCAPE ) {
          /* last sent character was the escape character */
          sc->sc_outchar = sc->sc_outchar ^ PPP_TRANS;

          /* clear the escape flag and increment the offset */
          sc->sc_outflag &= ~SC_TX_ESCAPE;
          ioffset++;
        }
        else {
          /* need to send the escape character */
          sc->sc_outchar = PPP_ESCAPE;

          /* set the escape flag */
          sc->sc_outflag |= SC_TX_ESCAPE;
        }
	sendBegin = &sc->sc_outchar;
      }
      else {
        /* escape not needed - increment the offset as much as possible */
	while ((!ESCAPE_P(sc->sc_outchar)) && ((sc->sc_outoff + ioffset) < sc->sc_outlen)) {
	    ioffset++;
	    sc->sc_outchar = sc->sc_outbuf[sc->sc_outoff + ioffset];
	}
	sendBegin = &sc->sc_outbuf[sc->sc_outoff];
      }

      /* write out the character(s) and update the stats */
      (*tp->device.write)(tp->minor, sendBegin, (ioffset > 0) ? ioffset : 1);
      sc->sc_stats.ppp_obytes += (ioffset > 0) ? ioffset : 1;
      sc->sc_outoff += ioffset;
    }
  }

  return ( 0 );
}

#ifdef XXX_XXX
/*
 * Timeout routine - try to start some more output.
 */
static void
ppp_timeout(x)
    void *x;
{
    struct rtems_termios_tty *tty = (struct rtems_termios_tty *)x;
    struct ppp_softc         *sc  = tty->t_sc;
/*    struct rtems_termios_tty *tp  = (struct rtems_termios_tty *)sc->sc_devp; */

    sc->sc_flags &= ~SC_TIMEOUT;
/*    pppstart(tp); */
}
#endif

/*
 * Allocate enough mbuf to handle current MRU.
 */
#ifdef XXX_XXX
static void
pppgetm(sc)
    register struct ppp_softc *sc;
{
    struct mbuf *m, **mp;
    int len;

    mp = &sc->sc_m;
    for (len = sc->sc_mru + PPP_HDRLEN + PPP_FCSLEN; len > 0; ){
	if ((m = *mp) == NULL) {
	    MGETHDR(m, M_DONTWAIT, MT_DATA);
	    if (m == NULL)
		break;
	    *mp = m;
	    MCLGET(m, M_DONTWAIT);
	}
	len -= M_DATASIZE(m);
	mp = &m->m_next;
    }
}
#endif

void
pppallocmbuf(struct ppp_softc *sc, struct mbuf **mp)
{
  int            ilen;
  struct mbuf   *m;

  /* loop over length value */
  ilen = sc->sc_mru + PPP_HDRLEN + PPP_FCSLEN;
  while ( ilen > 0 ) {
    /* see if this is end of the chain */
    m = *mp;
    if ( m == NULL ) {
      /* get mbuf header */
      MGETHDR(m, M_DONTWAIT, MT_DATA);
      if ( m == NULL ) {
        /* error - set condition to break out */
        printf("pppallocmbuf: MGETHDR failed\n");
        break;
      }
      MCLGET(m, M_DONTWAIT);
      m->m_next = NULL;
      *mp = m;
    }

    /* update loop variables */
    mp    = &m->m_next;
    ilen -= M_DATASIZE(m);
  }
}

/*
 * tty interface receiver interrupt.
 */
static unsigned paritytab[8] = {
    0x96696996, 0x69969669, 0x69969669, 0x96696996,
    0x69969669, 0x96696996, 0x96696996, 0x69969669
};

int
pppinput(int c, struct rtems_termios_tty *tp)
{
    register struct ppp_softc *sc = tp->t_sc;
    struct mbuf *m;
    int ilen;

    if (sc == NULL || tp != (struct rtems_termios_tty *)sc->sc_devp)
	return 0;
    if (sc->sc_m == NULL) {
        rtems_event_send(sc->sc_rxtask, RX_EMPTY);
        IF_DEQUEUE(&sc->sc_freeq, sc->sc_m);
        if ( sc->sc_m == NULL ) {
          return 0;
        }
    }

    ++sc->sc_stats.ppp_ibytes;

    c &= 0xff;
    if (c & 0x80)
	sc->sc_flags |= SC_RCV_B7_1;
    else
	sc->sc_flags |= SC_RCV_B7_0;
    if (paritytab[c >> 5] & (1 << (c & 0x1F)))
	sc->sc_flags |= SC_RCV_ODDP;
    else
	sc->sc_flags |= SC_RCV_EVNP;

    if (c == PPP_FLAG) {
	ilen = sc->sc_ilen;
	sc->sc_ilen = 0;

	/*
	 * If SC_ESCAPED is set, then we've seen the packet
	 * abort sequence "}~".
	 */
	if (sc->sc_flags & (SC_FLUSH | SC_ESCAPED)
	    || (ilen > 0 && sc->sc_fcs != PPP_GOODFCS)) {
	    sc->sc_flags |= SC_PKTLOST;	/* note the dropped packet */
	    if ((sc->sc_flags & (SC_FLUSH | SC_ESCAPED)) == 0){
                /* bad fcs error */
		sc->sc_if.if_ierrors++;
		sc->sc_stats.ppp_ierrors++;
	    } else
		sc->sc_flags &= ~(SC_FLUSH | SC_ESCAPED);
	    return 0;
	}

	if (ilen < PPP_HDRLEN + PPP_FCSLEN) {
	    if (ilen) {
                /* too short error */
		sc->sc_if.if_ierrors++;
		sc->sc_stats.ppp_ierrors++;
		sc->sc_flags |= SC_PKTLOST;
	    }
	    return 0;
	}

	/* Remove FCS trailer.  Somewhat painful... */
	ilen -= 2;
	if (--sc->sc_mc->m_len == 0) {
	    for (m = sc->sc_m; m->m_next != sc->sc_mc; m = m->m_next);
	    sc->sc_mc = m;
	}
	sc->sc_mc->m_len--;

	/* excise this mbuf chain - place on raw queue */
	m = sc->sc_m;
        if ( sc->sc_flags & SC_PKTLOST ) {
          m->m_flags   |= M_ERRMARK;
          sc->sc_flags &= ~SC_PKTLOST;
        }
        IF_ENQUEUE(&sc->sc_rawq, m);

        /* setup next mbuf chain */
        IF_DEQUEUE(&sc->sc_freeq, sc->sc_m);

        /* send rx packet event */
        rtems_event_send(sc->sc_rxtask, RX_PACKET);
	return 0;
    }

    if (c < 0x20 && (sc->sc_rasyncmap & (1 << c)))
	return 0;

    if (sc->sc_flags & SC_ESCAPED) {
	sc->sc_flags &= ~SC_ESCAPED;
	c ^= PPP_TRANS;
    } else if (c == PPP_ESCAPE) {
	sc->sc_flags |= SC_ESCAPED;
	return 0;
    }

    /*
     * Initialize buffer on first octet received.
     * First octet could be address or protocol (when compressing
     * address/control).
     * Second octet is control.
     * Third octet is first or second (when compressing protocol)
     * octet of protocol.
     * Fourth octet is second octet of protocol.
     */
    if (sc->sc_ilen == 0) {
	m = sc->sc_m;
	m->m_len = 0;
	m->m_data = M_DATASTART(sc->sc_m);
	sc->sc_mc = m;
	sc->sc_mp = mtod(m, char *);
	sc->sc_fcs = PPP_INITFCS;
	if (c != PPP_ALLSTATIONS) {
	    if (sc->sc_flags & SC_REJ_COMP_AC) {
                /* garbage received error */
		goto flush;
	    }
	    *sc->sc_mp++ = PPP_ALLSTATIONS;
	    *sc->sc_mp++ = PPP_UI;
	    sc->sc_ilen += 2;
	    m->m_len += 2;
	}
    }
    if (sc->sc_ilen == 1 && c != PPP_UI) {
        /* missing UI error */
	goto flush;
    }
    if (sc->sc_ilen == 2 && (c & 1) == 1) {
	/* a compressed protocol */
	*sc->sc_mp++ = 0;
	sc->sc_ilen++;
	sc->sc_mc->m_len++;
    }
    if (sc->sc_ilen == 3 && (c & 1) == 0) {
        /* bad protocol error */
	goto flush;
    }

    /* packet beyond configured mru? */
    if (++sc->sc_ilen > sc->sc_mru + PPP_HDRLEN + PPP_FCSLEN) {
        /* packet too big error */
	goto flush;
    }

    /* is this mbuf full? */
    m = sc->sc_mc;
    if (M_TRAILINGSPACE(m) <= 0) {
	if (m->m_next == NULL) {
          /* get next available mbuf for the chain */
          IF_DEQUEUE(&sc->sc_freeq, m->m_next);
          if (m->m_next == NULL) {
            /* too few mbufs */
            goto flush;
          }
          else {
            /* send rx mbuf event */
            rtems_event_send(sc->sc_rxtask, RX_MBUF);
          }
	}
	sc->sc_mc = m = m->m_next;
	m->m_len  = 0;
	m->m_next = 0;
	m->m_data = M_DATASTART(m);
	sc->sc_mp = mtod(m, char *);
    }

    ++m->m_len;
    *sc->sc_mp++ = c;
    sc->sc_fcs = PPP_FCS(sc->sc_fcs, c);
    return 0;

 flush:
    if (!(sc->sc_flags & SC_FLUSH)) {
	sc->sc_if.if_ierrors++;
	sc->sc_stats.ppp_ierrors++;
	sc->sc_flags |= SC_FLUSH;
    }
    return 0;
}

#ifdef XXX_XXX
#define MAX_DUMP_BYTES	128

static void
ppplogchar(sc, c)
    struct ppp_softc *sc;
    int c;
{
    if (c >= 0)
	sc->sc_rawin[sc->sc_rawin_count++] = c;
    if (sc->sc_rawin_count >= sizeof(sc->sc_rawin)
	|| (c < 0 && sc->sc_rawin_count > 0)) {
	printf("ppp%d input: ", sc->sc_if.if_unit);
	pppdumpb(sc->sc_rawin, sc->sc_rawin_count);
	sc->sc_rawin_count = 0;
    }
}

static void
pppdumpb(b, l)
    u_char *b;
    int l;
{
    char buf[3*MAX_DUMP_BYTES+4];
    char *bp = buf;
    static char digits[] = "0123456789abcdef";

    while (l--) {
	if (bp >= buf + sizeof(buf) - 3) {
	    *bp++ = '>';
	    break;
	}
	*bp++ = digits[*b >> 4]; /* convert byte to ascii hex */
	*bp++ = digits[*b++ & 0xf];
	*bp++ = ' ';
    }

    *bp = 0;
    printf("%s\n", buf);
}
#endif

#endif	/* NPPP > 0 */