lcp.c

经典的ppp程序

		break;
	    }

	    GETSHORT(cishort, p);
	    /* possibly should insist on a minimum/maximum MRRU here */
	    ho->neg_mrru = 1;
	    ho->mrru = cishort;
	    break;

	case CI_SSNHF:
	    if (!ao->neg_ssnhf || !multilink ||
		cilen != CILEN_VOID) {
		orc = CONFREJ;
		break;
	    }
	    ho->neg_ssnhf = 1;
	    break;

	case CI_EPDISC:
	    if (!ao->neg_endpoint ||
		cilen < CILEN_CHAR ||
		cilen > CILEN_CHAR + MAX_ENDP_LEN) {
		orc = CONFREJ;
		break;
	    }
	    GETCHAR(cichar, p);
	    cilen -= CILEN_CHAR;
	    ho->neg_endpoint = 1;
	    ho->endpoint.class = cichar;
	    ho->endpoint.length = cilen;
	    BCOPY(p, ho->endpoint.value, cilen);
	    INCPTR(cilen, p);
	    break;

	default:
	    LCPDEBUG(("lcp_reqci: rcvd unknown option %d", citype));
	    orc = CONFREJ;
	    break;
	}

endswitch:
	if (orc == CONFACK &&		/* Good CI */
	    rc != CONFACK)		/*  but prior CI wasnt? */
	    continue;			/* Don't send this one */

	if (orc == CONFNAK) {		/* Nak this CI? */
	    if (reject_if_disagree	/* Getting fed up with sending NAKs? */
		&& citype != CI_MAGICNUMBER) {
		orc = CONFREJ;		/* Get tough if so */
	    } else {
		if (rc == CONFREJ)	/* Rejecting prior CI? */
		    continue;		/* Don't send this one */
		rc = CONFNAK;
	    }
	}
	if (orc == CONFREJ) {		/* Reject this CI */
	    rc = CONFREJ;
	    if (cip != rejp)		/* Need to move rejected CI? */
		BCOPY(cip, rejp, cilen); /* Move it */
	    INCPTR(cilen, rejp);	/* Update output pointer */
	}
    }

    /*
     * If we wanted to send additional NAKs (for unsent CIs), the
     * code would go here.  The extra NAKs would go at *nakp.
     * At present there are no cases where we want to ask the
     * peer to negotiate an option.
     */

    switch (rc) {
    case CONFACK:
	*lenp = next - inp;
	break;
    case CONFNAK:
	/*
	 * Copy the Nak'd options from the nak_buffer to the caller's buffer.
	 */
	*lenp = nakp - nak_buffer;
	BCOPY(nak_buffer, inp, *lenp);
	break;
    case CONFREJ:
	*lenp = rejp - inp;
	break;
    }

    LCPDEBUG(("lcp_reqci: returning CONF%s.", CODENAME(rc)));
    return (rc);			/* Return final code */
}


/*
 * lcp_up - LCP has come UP.
 */
static void
lcp_up(f)
    fsm *f;
{
    lcp_options *wo = &lcp_wantoptions[f->unit];
    lcp_options *ho = &lcp_hisoptions[f->unit];
    lcp_options *go = &lcp_gotoptions[f->unit];
    lcp_options *ao = &lcp_allowoptions[f->unit];
    int mtu;

    if (!go->neg_magicnumber)
	go->magicnumber = 0;
    if (!ho->neg_magicnumber)
	ho->magicnumber = 0;

    /*
     * Set our MTU to the smaller of the MTU we wanted and
     * the MRU our peer wanted.  If we negotiated an MRU,
     * set our MRU to the larger of value we wanted and
     * the value we got in the negotiation.
     * Note on the MTU: the link MTU can be the MRU the peer wanted,
     * the interface MTU is set to the lower of that and the
     * MTU we want to use.
     */
    mtu = ho->neg_mru? ho->mru: PPP_MRU;
#ifdef HAVE_MULTILINK
    if (!(multilink && go->neg_mrru && ho->neg_mrru))
#endif /* HAVE_MULTILINK */
	netif_set_mtu(f->unit, MIN(mtu, ao->mru));
    ppp_send_config(f->unit, mtu,
		    (ho->neg_asyncmap? ho->asyncmap: 0xffffffff),
		    ho->neg_pcompression, ho->neg_accompression);
    ppp_recv_config(f->unit, (go->neg_mru? MAX(wo->mru, go->mru): PPP_MRU),
		    (lax_recv? 0: go->neg_asyncmap? go->asyncmap: 0xffffffff),
		    go->neg_pcompression, go->neg_accompression);

    if (ho->neg_mru)
	peer_mru[f->unit] = ho->mru;

    lcp_echo_lowerup(f->unit);  /* Enable echo messages */

    link_established(f->unit);
}


/*
 * lcp_down - LCP has gone DOWN.
 *
 * Alert other protocols.
 */
static void
lcp_down(f)
    fsm *f;
{
    lcp_options *go = &lcp_gotoptions[f->unit];

    lcp_echo_lowerdown(f->unit);

    link_down(f->unit);

    ppp_send_config(f->unit, PPP_MRU, 0xffffffff, 0, 0);
    ppp_recv_config(f->unit, PPP_MRU,
		    (go->neg_asyncmap? go->asyncmap: 0xffffffff),
		    go->neg_pcompression, go->neg_accompression);
    peer_mru[f->unit] = PPP_MRU;
}


/*
 * lcp_starting - LCP needs the lower layer up.
 */
static void
lcp_starting(f)
    fsm *f;
{
    link_required(f->unit);
}


/*
 * lcp_finished - LCP has finished with the lower layer.
 */
static void
lcp_finished(f)
    fsm *f;
{
    link_terminated(f->unit);
}


/*
 * lcp_printpkt - print the contents of an LCP packet.
 */
static char *lcp_codenames[] = {
    "ConfReq", "ConfAck", "ConfNak", "ConfRej",
    "TermReq", "TermAck", "CodeRej", "ProtRej",
    "EchoReq", "EchoRep", "DiscReq"
};

static int
lcp_printpkt(p, plen, printer, arg)
    u_char *p;
    int plen;
    void (*printer) __P((void *, char *, ...));
    void *arg;
{
    int code, id, len, olen, i;
    u_char *pstart, *optend;
    u_short cishort;
    u_int32_t cilong;

    if (plen < HEADERLEN)
	return 0;
    pstart = p;
    GETCHAR(code, p);
    GETCHAR(id, p);
    GETSHORT(len, p);
    if (len < HEADERLEN || len > plen)
	return 0;

    if (code >= 1 && code <= sizeof(lcp_codenames) / sizeof(char *))
	printer(arg, " %s", lcp_codenames[code-1]);
    else
	printer(arg, " code=0x%x", code);
    printer(arg, " id=0x%x", id);
    len -= HEADERLEN;
    switch (code) {
    case CONFREQ:
    case CONFACK:
    case CONFNAK:
    case CONFREJ:
	/* print option list */
	while (len >= 2) {
	    GETCHAR(code, p);
	    GETCHAR(olen, p);
	    p -= 2;
	    if (olen < 2 || olen > len) {
		break;
	    }
	    printer(arg, " <");
	    len -= olen;
	    optend = p + olen;
	    switch (code) {
	    case CI_MRU:
		if (olen == CILEN_SHORT) {
		    p += 2;
		    GETSHORT(cishort, p);
		    printer(arg, "mru %d", cishort);
		}
		break;
	    case CI_ASYNCMAP:
		if (olen == CILEN_LONG) {
		    p += 2;
		    GETLONG(cilong, p);
		    printer(arg, "asyncmap 0x%x", cilong);
		}
		break;
	    case CI_AUTHTYPE:
		if (olen >= CILEN_SHORT) {
		    p += 2;
		    printer(arg, "auth ");
		    GETSHORT(cishort, p);
		    switch (cishort) {
		    case PPP_PAP:
			printer(arg, "pap");
			break;
		    case PPP_CHAP:
			printer(arg, "chap");
			if (p < optend) {
			    switch (*p) {
			    case CHAP_DIGEST_MD5:
				printer(arg, " MD5");
				++p;
				break;
#ifdef CHAPMS
			    case CHAP_MICROSOFT:
				printer(arg, " m$oft");
				++p;
				break;
#endif
			    }
			}
			break;
		    default:
			printer(arg, "0x%x", cishort);
		    }
		}
		break;
	    case CI_QUALITY:
		if (olen >= CILEN_SHORT) {
		    p += 2;
		    printer(arg, "quality ");
		    GETSHORT(cishort, p);
		    switch (cishort) {
		    case PPP_LQR:
			printer(arg, "lqr");
			break;
		    default:
			printer(arg, "0x%x", cishort);
		    }
		}
		break;
	    case CI_CALLBACK:
		if (olen >= CILEN_CHAR) {
		    p += 2;
		    printer(arg, "callback ");
		    GETCHAR(cishort, p);
		    switch (cishort) {
		    case CBCP_OPT:
			printer(arg, "CBCP");
			break;
		    default:
			printer(arg, "0x%x", cishort);
		    }
		}
		break;
	    case CI_MAGICNUMBER:
		if (olen == CILEN_LONG) {
		    p += 2;
		    GETLONG(cilong, p);
		    printer(arg, "magic 0x%x", cilong);
		}
		break;
	    case CI_PCOMPRESSION:
		if (olen == CILEN_VOID) {
		    p += 2;
		    printer(arg, "pcomp");
		}
		break;
	    case CI_ACCOMPRESSION:
		if (olen == CILEN_VOID) {
		    p += 2;
		    printer(arg, "accomp");
		}
		break;
	    case CI_MRRU:
		if (olen == CILEN_SHORT) {
		    p += 2;
		    GETSHORT(cishort, p);
		    printer(arg, "mrru %d", cishort);
		}
		break;
	    case CI_SSNHF:
		if (olen == CILEN_VOID) {
		    p += 2;
		    printer(arg, "ssnhf");
		}
		break;
	    case CI_EPDISC:
#ifdef HAVE_MULTILINK
		if (olen >= CILEN_CHAR) {
		    struct epdisc epd;
		    p += 2;
		    GETCHAR(epd.class, p);
		    epd.length = olen - CILEN_CHAR;
		    if (epd.length > MAX_ENDP_LEN)
			epd.length = MAX_ENDP_LEN;
		    if (epd.length > 0) {
			BCOPY(p, epd.value, epd.length);
			p += epd.length;
		    }
		    printer(arg, "endpoint [%s]", epdisc_to_str(&epd));
		}
#else
		printer(arg, "endpoint");
#endif
		break;
	    }
	    while (p < optend) {
		GETCHAR(code, p);
		printer(arg, " %.2x", code);
	    }
	    printer(arg, ">");
	}
	break;

    case TERMACK:
    case TERMREQ:
	if (len > 0 && *p >= ' ' && *p < 0x7f) {
	    printer(arg, " ");
	    print_string((char *)p, len, printer, arg);
	    p += len;
	    len = 0;
	}
	break;

    case ECHOREQ:
    case ECHOREP:
    case DISCREQ:
	if (len >= 4) {
	    GETLONG(cilong, p);
	    printer(arg, " magic=0x%x", cilong);
	    p += 4;
	    len -= 4;
	}
	break;
    }

    /* print the rest of the bytes in the packet */
    for (i = 0; i < len && i < 32; ++i) {
	GETCHAR(code, p);
	printer(arg, " %.2x", code);
    }
    if (i < len) {
	printer(arg, " ...");
	p += len - i;
    }

    return p - pstart;
}

/*
 * Time to shut down the link because there is nothing out there.
 */

static
void LcpLinkFailure (f)
    fsm *f;
{
    if (f->state == OPENED) {
	info("No response to %d echo-requests", lcp_echos_pending);
        notice("Serial link appears to be disconnected.");
        lcp_close(f->unit, "Peer not responding");
	status = EXIT_PEER_DEAD;
    }
}

/*
 * Timer expired for the LCP echo requests from this process.
 */

static void
LcpEchoCheck (f)
    fsm *f;
{
    LcpSendEchoRequest (f);
    if (f->state != OPENED)
	return;

    /*
     * Start the timer for the next interval.
     */
    if (lcp_echo_timer_running)
	warn("assertion lcp_echo_timer_running==0 failed");
    TIMEOUT (LcpEchoTimeout, f, lcp_echo_interval);
    lcp_echo_timer_running = 1;
}

/*
 * LcpEchoTimeout - Timer expired on the LCP echo
 */

static void
LcpEchoTimeout (arg)
    void *arg;
{
    if (lcp_echo_timer_running != 0) {
        lcp_echo_timer_running = 0;
        LcpEchoCheck ((fsm *) arg);
    }
}

/*
 * LcpEchoReply - LCP has received a reply to the echo
 */

static void
lcp_received_echo_reply (f, id, inp, len)
    fsm *f;
    int id;
    u_char *inp;
    int len;
{
    u_int32_t magic;

    /* Check the magic number - don't count replies from ourselves. */
    if (len < 4) {
	dbglog("lcp: received short Echo-Reply, length %d", len);
	return;
    }
    GETLONG(magic, inp);
    if (lcp_gotoptions[f->unit].neg_magicnumber
	&& magic == lcp_gotoptions[f->unit].magicnumber) {
	warn("appear to have received our own echo-reply!");
	return;
    }

    /* Reset the number of outstanding echo frames */
    lcp_echos_pending = 0;
}

/*
 * LcpSendEchoRequest - Send an echo request frame to the peer
 */

static void
LcpSendEchoRequest (f)
    fsm *f;
{
    u_int32_t lcp_magic;
    u_char pkt[4], *pktp;

    /*
     * Detect the failure of the peer at this point.
     */
    if (lcp_echo_fails != 0) {
        if (lcp_echos_pending >= lcp_echo_fails) {
            LcpLinkFailure(f);
	    lcp_echos_pending = 0;
	}
    }

    /*
     * Make and send the echo request frame.
     */
    if (f->state == OPENED) {
        lcp_magic = lcp_gotoptions[f->unit].magicnumber;
	pktp = pkt;
	PUTLONG(lcp_magic, pktp);
        fsm_sdata(f, ECHOREQ, lcp_echo_number++ & 0xFF, pkt, pktp - pkt);
	++lcp_echos_pending;
    }
}

/*
 * lcp_echo_lowerup - Start the timer for the LCP frame
 */

static void
lcp_echo_lowerup (unit)
    int unit;
{
    fsm *f = &lcp_fsm[unit];

    /* Clear the parameters for generating echo frames */
    lcp_echos_pending      = 0;
    lcp_echo_number        = 0;
    lcp_echo_timer_running = 0;
  
    /* If a timeout interval is specified then start the timer */
    if (lcp_echo_interval != 0)
        LcpEchoCheck (f);
}

/*
 * lcp_echo_lowerdown - Stop the timer for the LCP frame
 */

static void
lcp_echo_lowerdown (unit)
    int unit;
{
    fsm *f = &lcp_fsm[unit];

    if (lcp_echo_timer_running != 0) {
        UNTIMEOUT (LcpEchoTimeout, f);
        lcp_echo_timer_running = 0;
    }
}