lcp.c

LwIP是瑞士计算机科学院(Swedish Institute of Computer Science)的AdamDunkels等开发的一套用于嵌入式系统的开放源代码TCP/IP协议栈。LwIP的含义

	*/
	return (LENCISHORT(go->neg_mru && go->mru != PPP_DEFMRU) +
		LENCILONG(go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl) +
		LENCICHAP(go->neg_chap) +
		LENCISHORT(!go->neg_chap && go->neg_upap) +
		LENCILQR(go->neg_lqr) +
		LENCICBCP(go->neg_cbcp) +
		LENCILONG(go->neg_magicnumber) +
		LENCIVOID(go->neg_pcompression) +
		LENCIVOID(go->neg_accompression));
}


/*
 * lcp_addci - Add our desired CIs to a packet.
 */
static void lcp_addci(fsm *f, u_char *ucp, int *lenp)
{
	lcp_options *go = &lcp_gotoptions[f->unit];
	u_char *start_ucp = ucp;
	
#define ADDCIVOID(opt, neg) \
	if (neg) { \
	    LCPDEBUG((LOG_INFO, "lcp_addci: opt=%d\n", opt)); \
		PUTCHAR(opt, ucp); \
		PUTCHAR(CILEN_VOID, ucp); \
	}
#define ADDCISHORT(opt, neg, val) \
	if (neg) { \
	    LCPDEBUG((LOG_INFO, "lcp_addci: INT opt=%d %X\n", opt, val)); \
		PUTCHAR(opt, ucp); \
		PUTCHAR(CILEN_SHORT, ucp); \
		PUTSHORT(val, ucp); \
	}
#define ADDCICHAP(opt, neg, val, digest) \
	if (neg) { \
	    LCPDEBUG((LOG_INFO, "lcp_addci: CHAP opt=%d %X\n", opt, val)); \
		PUTCHAR(opt, ucp); \
		PUTCHAR(CILEN_CHAP, ucp); \
		PUTSHORT(val, ucp); \
		PUTCHAR(digest, ucp); \
	}
#define ADDCILONG(opt, neg, val) \
	if (neg) { \
	    LCPDEBUG((LOG_INFO, "lcp_addci: L opt=%d %lX\n", opt, val)); \
		PUTCHAR(opt, ucp); \
		PUTCHAR(CILEN_LONG, ucp); \
		PUTLONG(val, ucp); \
	}
#define ADDCILQR(opt, neg, val) \
	if (neg) { \
	    LCPDEBUG((LOG_INFO, "lcp_addci: LQR opt=%d %lX\n", opt, val)); \
		PUTCHAR(opt, ucp); \
		PUTCHAR(CILEN_LQR, ucp); \
		PUTSHORT(PPP_LQR, ucp); \
		PUTLONG(val, ucp); \
	}
#define ADDCICHAR(opt, neg, val) \
	if (neg) { \
	    LCPDEBUG((LOG_INFO, "lcp_addci: CHAR opt=%d %X '%z'\n", opt, val, val)); \
		PUTCHAR(opt, ucp); \
		PUTCHAR(CILEN_CHAR, ucp); \
		PUTCHAR(val, ucp); \
	}
	
	ADDCISHORT(CI_MRU, go->neg_mru && go->mru != PPP_DEFMRU, go->mru);
	ADDCILONG(CI_ASYNCMAP, go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl,
			go->asyncmap);
	ADDCICHAP(CI_AUTHTYPE, go->neg_chap, PPP_CHAP, go->chap_mdtype);
	ADDCISHORT(CI_AUTHTYPE, !go->neg_chap && go->neg_upap, PPP_PAP);
	ADDCILQR(CI_QUALITY, go->neg_lqr, go->lqr_period);
	ADDCICHAR(CI_CALLBACK, go->neg_cbcp, CBCP_OPT);
	ADDCILONG(CI_MAGICNUMBER, go->neg_magicnumber, go->magicnumber);
	ADDCIVOID(CI_PCOMPRESSION, go->neg_pcompression);
	ADDCIVOID(CI_ACCOMPRESSION, go->neg_accompression);
	
	if (ucp - start_ucp != *lenp) {
		/* this should never happen, because peer_mtu should be 1500 */
		LCPDEBUG((LOG_ERR, "Bug in lcp_addci: wrong length\n"));
	}
}


/*
 * lcp_ackci - Ack our CIs.
 * This should not modify any state if the Ack is bad.
 *
 * Returns:
 *	0 - Ack was bad.
 *	1 - Ack was good.
 */
static int lcp_ackci(fsm *f, u_char *p, int len)
{
	lcp_options *go = &lcp_gotoptions[f->unit];
	u_char cilen, citype, cichar;
	u_short cishort;
	u32_t cilong;
	
	/*
	* 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 ACKCIVOID(opt, neg) \
	if (neg) { \
		if ((len -= CILEN_VOID) < 0) \
			goto bad; \
		GETCHAR(citype, p); \
		GETCHAR(cilen, p); \
		if (cilen != CILEN_VOID || \
				citype != opt) \
			goto bad; \
	}
#define ACKCISHORT(opt, neg, val) \
	if (neg) { \
		if ((len -= CILEN_SHORT) < 0) \
			goto bad; \
		GETCHAR(citype, p); \
		GETCHAR(cilen, p); \
		if (cilen != CILEN_SHORT || \
				citype != opt) \
			goto bad; \
		GETSHORT(cishort, p); \
		if (cishort != val) \
			goto bad; \
	}
#define ACKCICHAR(opt, neg, val) \
	if (neg) { \
		if ((len -= CILEN_CHAR) < 0) \
			goto bad; \
		GETCHAR(citype, p); \
		GETCHAR(cilen, p); \
		if (cilen != CILEN_CHAR || \
				citype != opt) \
			goto bad; \
		GETCHAR(cichar, p); \
		if (cichar != val) \
			goto bad; \
	}
#define ACKCICHAP(opt, neg, val, digest) \
	if (neg) { \
		if ((len -= CILEN_CHAP) < 0) \
			goto bad; \
		GETCHAR(citype, p); \
		GETCHAR(cilen, p); \
		if (cilen != CILEN_CHAP || \
				citype != opt) \
			goto bad; \
		GETSHORT(cishort, p); \
		if (cishort != val) \
			goto bad; \
		GETCHAR(cichar, p); \
		if (cichar != digest) \
			goto bad; \
	}
#define ACKCILONG(opt, neg, val) \
	if (neg) { \
		if ((len -= CILEN_LONG) < 0) \
			goto bad; \
		GETCHAR(citype, p); \
		GETCHAR(cilen, p); \
		if (cilen != CILEN_LONG || \
				citype != opt) \
			goto bad; \
		GETLONG(cilong, p); \
		if (cilong != val) \
			goto bad; \
	}
#define ACKCILQR(opt, neg, val) \
	if (neg) { \
		if ((len -= CILEN_LQR) < 0) \
			goto bad; \
		GETCHAR(citype, p); \
		GETCHAR(cilen, p); \
		if (cilen != CILEN_LQR || \
				citype != opt) \
			goto bad; \
		GETSHORT(cishort, p); \
		if (cishort != PPP_LQR) \
			goto bad; \
		GETLONG(cilong, p); \
		if (cilong != val) \
			goto bad; \
	}
	
	ACKCISHORT(CI_MRU, go->neg_mru && go->mru != PPP_DEFMRU, go->mru);
	ACKCILONG(CI_ASYNCMAP, go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl,
			go->asyncmap);
	ACKCICHAP(CI_AUTHTYPE, go->neg_chap, PPP_CHAP, go->chap_mdtype);
	ACKCISHORT(CI_AUTHTYPE, !go->neg_chap && go->neg_upap, PPP_PAP);
	ACKCILQR(CI_QUALITY, go->neg_lqr, go->lqr_period);
	ACKCICHAR(CI_CALLBACK, go->neg_cbcp, CBCP_OPT);
	ACKCILONG(CI_MAGICNUMBER, go->neg_magicnumber, go->magicnumber);
	ACKCIVOID(CI_PCOMPRESSION, go->neg_pcompression);
	ACKCIVOID(CI_ACCOMPRESSION, go->neg_accompression);
	
	/*
	 * If there are any remaining CIs, then this packet is bad.
	 */
	if (len != 0)
		goto bad;
	LCPDEBUG((LOG_INFO, "lcp_acki: Ack\n"));
	return (1);
bad:
	LCPDEBUG((LOG_WARNING, "lcp_acki: received bad Ack!\n"));
	return (0);
}


/*
 * lcp_nakci - Peer has sent a NAK for some of our CIs.
 * This should not modify any state if the Nak is bad
 * or if LCP is in the OPENED state.
 *
 * Returns:
 *	0 - Nak was bad.
 *	1 - Nak was good.
 */
static int lcp_nakci(fsm *f, u_char *p, int len)
{
	lcp_options *go = &lcp_gotoptions[f->unit];
	lcp_options *wo = &lcp_wantoptions[f->unit];
	u_char citype, cichar, *next;
	u_short cishort;
	u32_t cilong;
	lcp_options no;		/* options we've seen Naks for */
	lcp_options try;		/* options to request next time */
	int looped_back = 0;
	int cilen;
	
	BZERO(&no, sizeof(no));
	try = *go;
	
	/*
	* Any Nak'd 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 NAKCIVOID(opt, neg, code) \
	if (go->neg && \
			len >= CILEN_VOID && \
			p[1] == CILEN_VOID && \
			p[0] == opt) { \
		len -= CILEN_VOID; \
		INCPTR(CILEN_VOID, p); \
		no.neg = 1; \
		code \
	}
#define NAKCICHAP(opt, neg, code) \
	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); \
		no.neg = 1; \
		code \
	}
#define NAKCICHAR(opt, neg, code) \
	if (go->neg && \
			len >= CILEN_CHAR && \
			p[1] == CILEN_CHAR && \
			p[0] == opt) { \
		len -= CILEN_CHAR; \
		INCPTR(2, p); \
		GETCHAR(cichar, p); \
		no.neg = 1; \
		code \
	}
#define NAKCISHORT(opt, neg, code) \
	if (go->neg && \
			len >= CILEN_SHORT && \
			p[1] == CILEN_SHORT && \
			p[0] == opt) { \
		len -= CILEN_SHORT; \
		INCPTR(2, p); \
		GETSHORT(cishort, p); \
		no.neg = 1; \
		code \
	}
#define NAKCILONG(opt, neg, code) \
	if (go->neg && \
			len >= CILEN_LONG && \
			p[1] == CILEN_LONG && \
			p[0] == opt) { \
		len -= CILEN_LONG; \
		INCPTR(2, p); \
		GETLONG(cilong, p); \
		no.neg = 1; \
		code \
	}
#define NAKCILQR(opt, neg, code) \
	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); \
		no.neg = 1; \
		code \
	}
	
	/*
	* We don't care if they want to send us smaller packets than
	* we want.  Therefore, accept any MRU less than what we asked for,
	* but then ignore the new value when setting the MRU in the kernel.
	* If they send us a bigger MRU than what we asked, accept it, up to
	* the limit of the default MRU we'd get if we didn't negotiate.
	*/
	if (go->neg_mru && go->mru != PPP_DEFMRU) {
		NAKCISHORT(CI_MRU, neg_mru,
			if (cishort <= wo->mru || cishort < PPP_DEFMRU)
				try.mru = cishort;
		);
	}
	
	/*
	* Add any characters they want to our (receive-side) asyncmap.
	*/
	if (go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl) {
		NAKCILONG(CI_ASYNCMAP, neg_asyncmap,
			try.asyncmap = go->asyncmap | cilong;
		);
	}
	
	/*
	* If they've nak'd our authentication-protocol, check whether
	* they are proposing a different protocol, or a different
	* hash algorithm for CHAP.
	*/
	if ((go->neg_chap || go->neg_upap)
			&& len >= CILEN_SHORT
			&& p[0] == CI_AUTHTYPE && p[1] >= CILEN_SHORT && p[1] <= len) {
		cilen = p[1];
	len -= cilen;
	no.neg_chap = go->neg_chap;
	no.neg_upap = go->neg_upap;
	INCPTR(2, p);
	GETSHORT(cishort, p);
	if (cishort == PPP_PAP && cilen == CILEN_SHORT) {
		/*
		 * If we were asking for CHAP, they obviously don't want to do it.
		 * If we weren't asking for CHAP, then we were asking for PAP,
		 * in which case this Nak is bad.
		 */
		if (!go->neg_chap)
			goto bad;
		try.neg_chap = 0;
	
	} else if (cishort == PPP_CHAP && cilen == CILEN_CHAP) {
		GETCHAR(cichar, p);
		if (go->neg_chap) {
			/*
			 * We were asking for CHAP/MD5; they must want a different
			 * algorithm.  If they can't do MD5, we'll have to stop
			 * asking for CHAP.
			 */
			if (cichar != go->chap_mdtype)
				try.neg_chap = 0;
		} else {
			/*
			 * Stop asking for PAP if we were asking for it.
			 */
			try.neg_upap = 0;
		}
	
	} else {
		/*
		 * We don't recognize what they're suggesting.
		 * Stop asking for what we were asking for.
		 */
		if (go->neg_chap)
			try.neg_chap = 0;
		else
			try.neg_upap = 0;
		p += cilen - CILEN_SHORT;
	}
	}
	
	/*
	* If they can't cope with our link quality protocol, we'll have
	* to stop asking for LQR.  We haven't got any other protocol.
	* If they Nak the reporting period, take their value XXX ?
	*/
	NAKCILQR(CI_QUALITY, neg_lqr,
		if (cishort != PPP_LQR)
			try.neg_lqr = 0;
		else
			try.lqr_period = cilong;
	);
	
	/*
	* Only implementing CBCP...not the rest of the callback options
	*/
	NAKCICHAR(CI_CALLBACK, neg_cbcp,
		try.neg_cbcp = 0;
	);
	
	/*
	* Check for a looped-back line.
	*/
	NAKCILONG(CI_MAGICNUMBER, neg_magicnumber,
		try.magicnumber = magic();
		looped_back = 1;
	);
	
	/*
	* Peer shouldn't send Nak for protocol compression or
	* address/control compression requests; they should send
	* a Reject instead.  If they send a Nak, treat it as a Reject.
	*/
	NAKCIVOID(CI_PCOMPRESSION, neg_pcompression,
		try.neg_pcompression = 0;
	);
	NAKCIVOID(CI_ACCOMPRESSION, neg_accompression,
		try.neg_accompression = 0;
	);
	
	/*
	* There may be remaining CIs, if the peer is requesting negotiation
	* on an option that we didn't include in our request packet.
	* If we see an option that we requested, or one we've already seen
	* in this packet, then this packet is bad.
	* If we wanted to respond by starting to negotiate on the requested
	* option(s), we could, but we don't, because except for the
	* authentication type and quality protocol, if we are not negotiating
	* an option, it is because we were told not to.
	* For the authentication type, the Nak from the peer means
	* `let me authenticate myself with you' which is a bit pointless.
	* For the quality protocol, the Nak means `ask me to send you quality
	* reports', but if we didn't ask for them, we don't want them.
	* An option we don't recognize represents the peer asking to
	* negotiate some option we don't support, so ignore it.
	*/
	while (len > CILEN_VOID) {
		GETCHAR(citype, p);
		GETCHAR(cilen, p);
		if (cilen < CILEN_VOID || (len -= cilen) < 0)
			goto bad;
		next = p + cilen - 2;
		
		switch (citype) {
		case CI_MRU:
			if ((go->neg_mru && go->mru != PPP_DEFMRU)
					|| no.neg_mru || cilen != CILEN_SHORT)
				goto bad;
			GETSHORT(cishort, p);
			if (cishort < PPP_DEFMRU)
				try.mru = cishort;
			break;
		case CI_ASYNCMAP:
			if ((go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl)
					|| no.neg_asyncmap || cilen != CILEN_LONG)
				goto bad;
			break;
		case CI_AUTHTYPE:
			if (go->neg_chap || no.neg_chap || go->neg_upap || no.neg_upap)
				goto bad;
			break;
		case CI_MAGICNUMBER:
			if (go->neg_magicnumber || no.neg_magicnumber ||
					cilen != CILEN_LONG)
				goto bad;
			break;
		case CI_PCOMPRESSION:
			if (go->neg_pcompression || no.neg_pcompression
					|| cilen != CILEN_VOID)
				goto bad;
			break;
		case CI_ACCOMPRESSION:
			if (go->neg_accompression || no.neg_accompression
					|| cilen != CILEN_VOID)
				goto bad;
			break;
		case CI_QUALITY:
			if (go->neg_lqr || no.neg_lqr || cilen != CILEN_LQR)
				goto bad;
			break;
		}
		p = next;
	}
	
	/* 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");