lcp.c

Unix/Linux NAPT协议解析源码

		    LCPDEBUG((LOG_WARNING,
			      "lcp_reqci: rcvd AUTHTYPE PAP, rejecting..."));
		    orc = CONFREJ;
		    break;
		}
		if (!ao->neg_upap) {	/* we don't want to do PAP */
		    orc = CONFNAK;	/* NAK it and suggest CHAP */
		    PUTCHAR(CI_AUTHTYPE, nakp);
		    PUTCHAR(CILEN_CHAP, nakp);
		    PUTSHORT(PPP_CHAP, nakp);
		    PUTCHAR(ao->chap_mdtype, nakp);
		    break;
		}
		ho->neg_upap = 1;
		break;
	    }
	    if (cishort == PPP_CHAP) {
		if (ho->neg_upap ||	/* we've already accepted PAP */
		    cilen != CILEN_CHAP) {
		    LCPDEBUG((LOG_INFO,
			      "lcp_reqci: rcvd AUTHTYPE CHAP, rejecting..."));
		    orc = CONFREJ;
		    break;
		}
		if (!ao->neg_chap) {	/* we don't want to do CHAP */
		    orc = CONFNAK;	/* NAK it and suggest PAP */
		    PUTCHAR(CI_AUTHTYPE, nakp);
		    PUTCHAR(CILEN_SHORT, nakp);
		    PUTSHORT(PPP_PAP, nakp);
		    break;
		}
		GETCHAR(cichar, p);	/* get digest type*/
		if (cichar != ao->chap_mdtype) {
		    orc = CONFNAK;
		    PUTCHAR(CI_AUTHTYPE, nakp);
		    PUTCHAR(CILEN_CHAP, nakp);
		    PUTSHORT(PPP_CHAP, nakp);
		    PUTCHAR(ao->chap_mdtype, nakp);
		    break;
		}
		ho->chap_mdtype = cichar; /* save md type */
		ho->neg_chap = 1;
		break;
	    }

	    /*
	     * We don't recognize the protocol they're asking for.
	     * Nak it with something we're willing to do.
	     * (At this point we know ao->neg_upap || ao->neg_chap.)
	     */
	    orc = CONFNAK;
	    PUTCHAR(CI_AUTHTYPE, nakp);
	    if (ao->neg_chap) {
		PUTCHAR(CILEN_CHAP, nakp);
		PUTSHORT(PPP_CHAP, nakp);
		PUTCHAR(ao->chap_mdtype, nakp);
	    } else {
		PUTCHAR(CILEN_SHORT, nakp);
		PUTSHORT(PPP_PAP, nakp);
	    }
	    break;

	case CI_QUALITY:
	    LCPDEBUG((LOG_INFO, "lcp_reqci: rcvd QUALITY"));
	    if (!ao->neg_lqr ||
		cilen != CILEN_LQR) {
		orc = CONFREJ;
		break;
	    }

	    GETSHORT(cishort, p);
	    GETLONG(cilong, p);
	    LCPDEBUG((LOG_INFO, "(%x %x)", cishort, (unsigned int) cilong));

	    /*
	     * Check the protocol and the reporting period.
	     * XXX When should we Nak this, and what with?
	     */
	    if (cishort != PPP_LQR) {
		orc = CONFNAK;
		PUTCHAR(CI_QUALITY, nakp);
		PUTCHAR(CILEN_LQR, nakp);
		PUTSHORT(PPP_LQR, nakp);
		PUTLONG(ao->lqr_period, nakp);
		break;
	    }
	    break;

	case CI_MAGICNUMBER:
	    LCPDEBUG((LOG_INFO, "lcp_reqci: rcvd MAGICNUMBER"));
	    if (!(ao->neg_magicnumber || go->neg_magicnumber) ||
		cilen != CILEN_LONG) {
		orc = CONFREJ;
		break;
	    }
	    GETLONG(cilong, p);
	    LCPDEBUG((LOG_INFO, "(%x)", (unsigned int) cilong));

	    /*
	     * He must have a different magic number.
	     */
	    if (go->neg_magicnumber &&
		cilong == go->magicnumber) {
		cilong = magic();	/* Don't put magic() inside macro! */
		orc = CONFNAK;
		PUTCHAR(CI_MAGICNUMBER, nakp);
		PUTCHAR(CILEN_LONG, nakp);
		PUTLONG(cilong, nakp);
		break;
	    }
	    ho->neg_magicnumber = 1;
	    ho->magicnumber = cilong;
	    break;


	case CI_PCOMPRESSION:
	    LCPDEBUG((LOG_INFO, "lcp_reqci: rcvd PCOMPRESSION"));
	    if (!ao->neg_pcompression ||
		cilen != CILEN_VOID) {
		orc = CONFREJ;
		break;
	    }
	    ho->neg_pcompression = 1;
	    break;

	case CI_ACCOMPRESSION:
	    LCPDEBUG((LOG_INFO, "lcp_reqci: rcvd ACCOMPRESSION"));
	    if (!ao->neg_accompression ||
		cilen != CILEN_VOID) {
		orc = CONFREJ;
		break;
	    }
	    ho->neg_accompression = 1;
	    break;

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

endswitch:
	LCPDEBUG((LOG_INFO, " (%s)", CODENAME(orc)));
	if (orc == CONFACK &&		/* Good CI */
	    rc != CONFACK)		/*  but prior CI wasn't? */
	    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((LOG_INFO, "lcp_reqci: returning CONF%s.", CODENAME(rc)));
    return (rc);			/* Return final code */
}


/*
 * lcp_up - LCP has come UP.
 *
 * Start UPAP, IPCP, etc.
 */
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];

    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.
     */
    ppp_send_config(f->unit, MIN(ao->mru, (ho->neg_mru? ho->mru: PPP_MRU)),
		    (ho->neg_asyncmap? ho->asyncmap: 0xffffffff),
		    ho->neg_pcompression, ho->neg_accompression);
    /*
     * If the asyncmap hasn't been negotiated, we really should
     * set the receive asyncmap to ffffffff, but we set it to 0
     * for backwards contemptibility.
     */
    ppp_recv_config(f->unit, (go->neg_mru? MAX(wo->mru, go->mru): PPP_MRU),
		    (go->neg_asyncmap? go->asyncmap: 0x00000000),
		    go->neg_pcompression, go->neg_accompression);

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

    ChapLowerUp(f->unit);	/* Enable CHAP */
    upap_lowerup(f->unit);	/* Enable UPAP */
    ipcp_lowerup(f->unit);	/* Enable IPCP */
    ccp_lowerup(f->unit);	/* Enable CCP */
    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_echo_lowerdown(f->unit);
    ccp_lowerdown(f->unit);
    ipcp_lowerdown(f->unit);
    ChapLowerDown(f->unit);
    upap_lowerdown(f->unit);

    sifdown(f->unit);
    ppp_send_config(f->unit, PPP_MRU, 0xffffffff, 0, 0);
    ppp_recv_config(f->unit, PPP_MRU, 0x00000000, 0, 0);
    peer_mru[f->unit] = PPP_MRU;

    link_down(f->unit);
}


/*
 * 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.
 */
char *lcp_codenames[] = {
    "ConfReq", "ConfAck", "ConfNak", "ConfRej",
    "TermReq", "TermAck", "CodeRej", "ProtRej",
    "EchoReq", "EchoRep", "DiscReq"
};

int
lcp_printpkt(p, plen, printer, arg)
    u_char *p;
    int plen;
    void (*printer) __P((void *, char *, ...));
    void *arg;
{
    int code, id, len, olen;
    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, "upap");
			break;
		    case PPP_CHAP:
			printer(arg, "chap");
			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_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;
	    }
	    while (p < optend) {
		GETCHAR(code, p);
		printer(arg, " %.2x", code);
	    }
	    printer(arg, ">");
	}
	break;
    }

    /* print the rest of the bytes in the packet */
    for (; len > 0; --len) {
	GETCHAR(code, p);
	printer(arg, " %.2x", code);
    }

    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) {
        do_syslog(LOG_NOTICE, "Excessive lack of response to LCP echo frames.");
        lcp_close(f->unit);		/* Reset connection */
    }
}

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

static void
LcpEchoCheck (f)
    fsm *f;
{
    long int delta;

    LcpSendEchoRequest (f);
    delta = (int) lcp_echo_interval;

/*
 * Start the timer for the next interval.
 */
    assert (lcp_echo_timer_running==0);
    TIMEOUT (LcpEchoTimeout, (caddr_t) f, (u_int32_t) delta);
    lcp_echo_timer_running = 1;
}

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

static void
LcpEchoTimeout (arg)
    caddr_t 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) {
	do_syslog(LOG_DEBUG, "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) {
	do_syslog(LOG_WARNING, "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].neg_magicnumber
	            ? lcp_gotoptions[f->unit].magicnumber
	            : 0L;
	pktp = pkt;
	PUTLONG(lcp_magic, pktp);
      
        fsm_sdata(f, ECHOREQ,
		  lcp_echo_number++ & 0xFF, pkt, pktp - pkt);
    }
}

/*
 * 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, (caddr_t) f);
        lcp_echo_timer_running = 0;
    }
}