/* If there is still anything left, this packet is bad. */
	if (len != 0)
		goto bad;
	
	/*
	* OK, the Nak is good.  Now we can update state.
	*/
	if (f->state != OPENED) {
		if (looped_back) {
			if (++try.numloops >= lcp_loopbackfail) {
				LCPDEBUG((LOG_NOTICE, "Serial line is looped back.\n"));
				lcp_close(f->unit, "Loopback detected");
			}
		} 
		else
			try.numloops = 0;
		*go = try;
	}
	
	return 1;
	
bad:
	LCPDEBUG((LOG_WARNING, "lcp_nakci: received bad Nak!\n"));
	return 0;
}


/*
 * lcp_rejci - Peer has Rejected some of our CIs.
 * This should not modify any state if the Reject is bad
 * or if LCP is in the OPENED state.
 *
 * Returns:
 *	0 - Reject was bad.
 *	1 - Reject was good.
 */
static int lcp_rejci(fsm *f, u_char *p, int len)
{
	lcp_options *go = &lcp_gotoptions[f->unit];
	u_char cichar;
	u_short cishort;
	u32_t cilong;
	lcp_options try;		/* options to request next time */
	
	try = *go;
	
	/*
	* Any Rejected CIs must be in exactly the same order that we sent.
	* Check packet length and CI length at each step.
	* If we find any deviations, then this packet is bad.
	*/
#define REJCIVOID(opt, neg) \
	if (go->neg && \
			len >= CILEN_VOID && \
			p[1] == CILEN_VOID && \
			p[0] == opt) { \
		len -= CILEN_VOID; \
		INCPTR(CILEN_VOID, p); \
		try.neg = 0; \
		LCPDEBUG((LOG_INFO, "lcp_rejci: void opt %d rejected\n", opt)); \
	}
#define REJCISHORT(opt, neg, val) \
	if (go->neg && \
			len >= CILEN_SHORT && \
			p[1] == CILEN_SHORT && \
			p[0] == opt) { \
		len -= CILEN_SHORT; \
		INCPTR(2, p); \
		GETSHORT(cishort, p); \
		/* Check rejected value. */ \
		if (cishort != val) \
			goto bad; \
		try.neg = 0; \
		LCPDEBUG((LOG_INFO,"lcp_rejci: short opt %d rejected\n", opt)); \
	}
#define REJCICHAP(opt, neg, val, digest) \
	if (go->neg && \
			len >= CILEN_CHAP && \
			p[1] == CILEN_CHAP && \
			p[0] == opt) { \
		len -= CILEN_CHAP; \
		INCPTR(2, p); \
		GETSHORT(cishort, p); \
		GETCHAR(cichar, p); \
		/* Check rejected value. */ \
		if (cishort != val || cichar != digest) \
			goto bad; \
		try.neg = 0; \
		try.neg_upap = 0; \
		LCPDEBUG((LOG_INFO,"lcp_rejci: chap opt %d rejected\n", opt)); \
	}
#define REJCILONG(opt, neg, val) \
	if (go->neg && \
			len >= CILEN_LONG && \
			p[1] == CILEN_LONG && \
			p[0] == opt) { \
		len -= CILEN_LONG; \
		INCPTR(2, p); \
		GETLONG(cilong, p); \
		/* Check rejected value. */ \
		if (cilong != val) \
			goto bad; \
		try.neg = 0; \
		LCPDEBUG((LOG_INFO,"lcp_rejci: long opt %d rejected\n", opt)); \
	}
#define REJCILQR(opt, neg, val) \
	if (go->neg && \
			len >= CILEN_LQR && \
			p[1] == CILEN_LQR && \
			p[0] == opt) { \
		len -= CILEN_LQR; \
		INCPTR(2, p); \
		GETSHORT(cishort, p); \
		GETLONG(cilong, p); \
		/* Check rejected value. */ \
		if (cishort != PPP_LQR || cilong != val) \
			goto bad; \
		try.neg = 0; \
		LCPDEBUG((LOG_INFO,"lcp_rejci: LQR opt %d rejected\n", opt)); \
	}
#define REJCICBCP(opt, neg, val) \
	if (go->neg && \
			len >= CILEN_CBCP && \
			p[1] == CILEN_CBCP && \
			p[0] == opt) { \
		len -= CILEN_CBCP; \
		INCPTR(2, p); \
		GETCHAR(cichar, p); \
		/* Check rejected value. */ \
		if (cichar != val) \
			goto bad; \
		try.neg = 0; \
		LCPDEBUG((LOG_INFO,"lcp_rejci: Callback opt %d rejected\n", opt)); \
	}
	
	REJCISHORT(CI_MRU, neg_mru, go->mru);
	REJCILONG(CI_ASYNCMAP, neg_asyncmap, go->asyncmap);
	REJCICHAP(CI_AUTHTYPE, neg_chap, PPP_CHAP, go->chap_mdtype);
	if (!go->neg_chap) {
		REJCISHORT(CI_AUTHTYPE, neg_upap, PPP_PAP);
	}
	REJCILQR(CI_QUALITY, neg_lqr, go->lqr_period);
	REJCICBCP(CI_CALLBACK, neg_cbcp, CBCP_OPT);
	REJCILONG(CI_MAGICNUMBER, neg_magicnumber, go->magicnumber);
	REJCIVOID(CI_PCOMPRESSION, neg_pcompression);
	REJCIVOID(CI_ACCOMPRESSION, neg_accompression);
	
	/*
	* If there are any remaining CIs, then this packet is bad.
	*/
	if (len != 0)
		goto bad;
	/*
	* Now we can update state.
	*/
	if (f->state != OPENED)
		*go = try;
	return 1;
	
bad:
	LCPDEBUG((LOG_WARNING, "lcp_rejci: received bad Reject!\n"));
	return 0;
}


/*
 * lcp_reqci - Check the peer's requested CIs and send appropriate response.
 *
 * Returns: CONFACK, CONFNAK or CONFREJ and input packet modified
 * appropriately.  If reject_if_disagree is non-zero, doesn't return
 * CONFNAK; returns CONFREJ if it can't return CONFACK.
 */
static int lcp_reqci(fsm *f, 
						u_char *inp,		/* Requested CIs */
						int *lenp,			/* Length of requested CIs */
						int reject_if_disagree)
{
	lcp_options *go = &lcp_gotoptions[f->unit];
	lcp_options *ho = &lcp_hisoptions[f->unit];
	lcp_options *ao = &lcp_allowoptions[f->unit];
	u_char *cip, *next;			/* Pointer to current and next CIs */
	int cilen, citype, cichar;	/* Parsed len, type, char value */
	u_short cishort;			/* Parsed short value */
	u32_t cilong;			/* Parse long value */
	int rc = CONFACK;			/* Final packet return code */
	int orc;					/* Individual option return code */
	u_char *p;					/* Pointer to next char to parse */
	u_char *rejp;				/* Pointer to next char in reject frame */
	u_char *nakp;				/* Pointer to next char in Nak frame */
	int l = *lenp;				/* Length left */
#if TRACELCP > 0
	char traceBuf[80];
	int traceNdx = 0;
#endif
	
	/*
	 * Reset all his options.
	 */
	BZERO(ho, sizeof(*ho));
	
	/*
	 * Process all his options.
	 */
	next = inp;
	nakp = nak_buffer;
	rejp = inp;
	while (l) {
		orc = CONFACK;			/* Assume success */
		cip = p = next;			/* Remember begining of CI */
		if (l < 2 ||			/* Not enough data for CI header or */
				p[1] < 2 ||			/*  CI length too small or */
				p[1] > l) {			/*  CI length too big? */
			LCPDEBUG((LOG_WARNING, "lcp_reqci: bad CI length!\n"));
			orc = CONFREJ;		/* Reject bad CI */
			cilen = l;			/* Reject till end of packet */
			l = 0;			/* Don't loop again */
			citype = 0;
			goto endswitch;
		}
		GETCHAR(citype, p);		/* Parse CI type */
		GETCHAR(cilen, p);		/* Parse CI length */
		l -= cilen;			/* Adjust remaining length */
		next += cilen;			/* Step to next CI */
		
		switch (citype) {		/* Check CI type */
		case CI_MRU:
			if (!ao->neg_mru) {		/* Allow option? */
				LCPDEBUG((LOG_INFO, "lcp_reqci: Reject MRU - not allowed\n"));
				orc = CONFREJ;		/* Reject CI */
				break;
			} else if (cilen != CILEN_SHORT) {	/* Check CI length */
				LCPDEBUG((LOG_INFO, "lcp_reqci: Reject MRU - bad length\n"));
				orc = CONFREJ;		/* Reject CI */
				break;
			}
			GETSHORT(cishort, p);	/* Parse MRU */
			
			/*
			 * He must be able to receive at least our minimum.
			 * No need to check a maximum.  If he sends a large number,
			 * we'll just ignore it.
			 */
			if (cishort < PPP_MINMRU) {
				LCPDEBUG((LOG_INFO, "lcp_reqci: Nak - MRU too small\n"));
				orc = CONFNAK;		/* Nak CI */
				PUTCHAR(CI_MRU, nakp);
				PUTCHAR(CILEN_SHORT, nakp);
				PUTSHORT(PPP_MINMRU, nakp);	/* Give him a hint */
				break;
			}
			ho->neg_mru = 1;		/* Remember he sent MRU */
			ho->mru = cishort;		/* And remember value */
#if TRACELCP > 0
			sprintf(&traceBuf[traceNdx], " MRU %d", cishort);
			traceNdx = strlen(traceBuf);
#endif
			break;
		
		case CI_ASYNCMAP:
			if (!ao->neg_asyncmap) {
				LCPDEBUG((LOG_INFO, "lcp_reqci: Reject ASYNCMAP not allowed\n"));
				orc = CONFREJ;
				break;
			} else if (cilen != CILEN_LONG) {
				LCPDEBUG((LOG_INFO, "lcp_reqci: Reject ASYNCMAP bad length\n"));
				orc = CONFREJ;
				break;
			}
			GETLONG(cilong, p);
			
			/*
			 * Asyncmap must have set at least the bits
			 * which are set in lcp_allowoptions[unit].asyncmap.
			 */
			if ((ao->asyncmap & ~cilong) != 0) {
				LCPDEBUG((LOG_INFO, "lcp_reqci: Nak ASYNCMAP %lX missing %lX\n", 
							cilong, ao->asyncmap));
				orc = CONFNAK;
				PUTCHAR(CI_ASYNCMAP, nakp);
				PUTCHAR(CILEN_LONG, nakp);
				PUTLONG(ao->asyncmap | cilong, nakp);
				break;
			}
			ho->neg_asyncmap = 1;
			ho->asyncmap = cilong;
#if TRACELCP > 0
			sprintf(&traceBuf[traceNdx], " ASYNCMAP=%lX", cilong);
			traceNdx = strlen(traceBuf);
#endif
			break;
		
		case CI_AUTHTYPE:
			if (cilen < CILEN_SHORT) {
				LCPDEBUG((LOG_INFO, "lcp_reqci: Reject AUTHTYPE missing arg\n"));
				orc = CONFREJ;
				break;
			} else if (!(ao->neg_upap || ao->neg_chap)) {
				/*
				 * Reject the option if we're not willing to authenticate.
				 */
				LCPDEBUG((LOG_INFO, "lcp_reqci: Reject AUTHTYPE not allowed\n"));
				orc = CONFREJ;
				break;
			}
			GETSHORT(cishort, p);
			
			/*
			 * Authtype must be UPAP or CHAP.
			 *
			 * Note: if both ao->neg_upap and ao->neg_chap are set,
			 * and the peer sends a Configure-Request with two
			 * authenticate-protocol requests, one for CHAP and one
			 * for UPAP, then we will reject the second request.
			 * Whether we end up doing CHAP or UPAP depends then on
			 * the ordering of the CIs in the peer's Configure-Request.
			 */
			
			if (cishort == PPP_PAP) {
				if (ho->neg_chap) {	/* we've already accepted CHAP */
					LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE PAP already accepted\n"));
					orc = CONFREJ;
					break;
				} else if (cilen != CILEN_SHORT) {
					LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE PAP bad len\n"));
					orc = CONFREJ;
					break;
				}
				if (!ao->neg_upap) {	/* we don't want to do PAP */
					LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE PAP not allowed\n"));
					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;
#if TRACELCP > 0
				sprintf(&traceBuf[traceNdx], " PAP (%X)", cishort);
				traceNdx = strlen(traceBuf);
#endif
				break;
			}
			if (cishort == PPP_CHAP) {
				if (ho->neg_upap) {	/* we've already accepted PAP */
					LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE CHAP accepted PAP\n"));
					orc = CONFREJ;
					break;
				} else if (cilen != CILEN_CHAP) {
					LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE CHAP bad len\n"));
					orc = CONFREJ;
					break;
				}
				if (!ao->neg_chap) {	/* we don't want to do CHAP */
					LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE CHAP not allowed\n"));
					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 != CHAP_DIGEST_MD5
#ifdef CHAPMS
						&& cichar != CHAP_MICROSOFT
#endif
				) {
					LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE CHAP digest=%d\n", cichar));
					orc = CONFNAK;
					PUTCHAR(CI_AUTHTYPE, nakp);
					PUTCHAR(CILEN_CHAP, nakp);
					PUTSHORT(PPP_CHAP, nakp);
					PUTCHAR(ao->chap_mdtype, nakp);
					break;
				}
#if TRACELCP > 0
				sprintf(&traceBuf[traceNdx], " CHAP %X,%d", cishort, cichar);
				traceNdx = strlen(traceBuf);
#endif
				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) {
				LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE %d req CHAP\n", cishort));
				PUTCHAR(CILEN_CHAP, nakp);
				PUTSHORT(PPP_CHAP, nakp);
				PUTCHAR(ao->chap_mdtype, nakp);
			} 
			else {
				LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE %d req PAP\n", cishort));
				PUTCHAR(CILEN_SHORT, nakp);
				PUTSHORT(PPP_PAP, nakp);
			}
			break;
		
		case CI_QUALITY:
			GETSHORT(cishort, p);
			GETLONG(cilong, p);
#if TRACELCP > 0
			sprintf(&traceBuf[traceNdx], " QUALITY (%x %x)", cishort, (unsigned int) cilong);
			traceNdx = strlen(traceBuf);
#endif

			if (!ao->neg_lqr ||
					cilen != CILEN_LQR) {
				orc = CONFREJ;
				break;
			}
			
			/*
			 * 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:
			if (!(ao->neg_magicnumber || go->neg_magicnumber) ||
					cilen != CILEN_LONG) {
				orc = CONFREJ;
				break;
			}
			GETLONG(cilong, p);
#if TRACELCP > 0
			sprintf(&traceBuf[traceNdx], " MAGICNUMBER (%lX)", cilong);
			traceNdx = strlen(traceBuf);
#endif

			/*
			 * 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:
#if TRACELCP > 0
			sprintf(&traceBuf[traceNdx], " PCOMPRESSION");
			traceNdx = strlen(traceBuf);
#endif
			if (!ao->neg_pcompression ||
					cilen != CILEN_VOID) {
				orc = CONFREJ;
				break;
			}
			ho->neg_pcompression = 1;
			break;
		
		case CI_ACCOMPRESSION:
#if TRACELCP > 0
			sprintf(&traceBuf[traceNdx], " ACCOMPRESSION");
			traceNdx = strlen(traceBuf);
#endif
			if (!ao->neg_accompression ||
					cilen != CILEN_VOID) {
				orc = CONFREJ;
				break;
			}
			ho->neg_accompression = 1;
			break;
		
		default:
#if TRACELCP
			sprintf(&traceBuf[traceNdx], " unknown %d", citype);
			traceNdx = strlen(traceBuf);
#endif