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

		
		default:
#if TRACELCP
			snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " unknown %d", citype);
			traceNdx = strlen(traceBuf);
#endif
			orc = CONFREJ;
			break;
		}
		
	endswitch:
#if TRACELCP
		if (traceNdx >= 80 - 32) {
			LCPDEBUG((LOG_INFO, "lcp_reqci: rcvd%s\n", traceBuf));
			traceNdx = 0;
		}
#endif
		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 = (int)(next - inp);
		break;
	case CONFNAK:
		/*
		 * Copy the Nak'd options from the nak_buffer to the caller's buffer.
		 */
		*lenp = (int)(nakp - nak_buffer);
		BCOPY(nak_buffer, inp, *lenp);
		break;
	case CONFREJ:
		*lenp = (int)(rejp - inp);
		break;
	}
	
#if TRACELCP > 0
	if (traceNdx > 0) {
		LCPDEBUG((LOG_INFO, "lcp_reqci: %s\n", traceBuf));
	}
#endif
	LCPDEBUG((LOG_INFO, "lcp_reqci: returning CONF%s.\n", CODENAME(rc)));
	return (rc);			/* Return final code */
}


/*
 * lcp_up - LCP has come UP.
 */
static void lcp_up(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, LWIP_MIN(ao->mru, (ho->neg_mru? ho->mru: PPP_MRU)),
				(ho->neg_asyncmap? ho->asyncmap: 0xffffffffl),
				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? LWIP_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;
	
	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(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, 0xffffffffl, 0, 0);
	ppp_recv_config(f->unit, PPP_MRU,
				(go->neg_asyncmap? go->asyncmap: 0x00000000),
				go->neg_pcompression, go->neg_accompression);
	peer_mru[f->unit] = PPP_MRU;
}


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


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


#if 0
/*
 * print_string - print a readable representation of a string using
 * printer.
 */
static void print_string(
    char *p,
    int len,
    void (*printer) (void *, char *, ...),
    void *arg
)
{
    int c;
    
    printer(arg, "\"");
    for (; len > 0; --len) {
        c = *p++;
        if (' ' <= c && c <= '~') {
            if (c == '\\' || c == '"')
                printer(arg, "\\");
            printer(arg, "%c", c);
        } else {
            switch (c) {
            case '\n':
                printer(arg, "\\n");
                break;
            case '\r':
                printer(arg, "\\r");
                break;
            case '\t':
                printer(arg, "\\t");
                break;
            default:
                printer(arg, "\\%.3o", c);
            }
        }
    }
    printer(arg, "\"");
}


/*
 * 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(
	u_char *p,
	int plen,
	void (*printer) (void *, char *, ...),
	void *arg
)
{
	int code, id, len, olen;
	u_char *pstart, *optend;
	u_short cishort;
	u32_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%lx", 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");
						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 ");
					GETSHORT(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;
			}
			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 (; len > 0; --len) {
		GETCHAR(code, p);
		printer(arg, " %.2x", code);
	}
	
	return (int)(p - pstart);
}
#endif

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

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

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

static void LcpEchoCheck (fsm *f)
{
	LcpSendEchoRequest (f);
	
	/*
	 * Start the timer for the next interval.
	 */
	LWIP_ASSERT("lcp_echo_timer_running == 0", lcp_echo_timer_running == 0);

	TIMEOUT (LcpEchoTimeout, f, lcp_echo_interval);
	lcp_echo_timer_running = 1;
}

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

static void LcpEchoTimeout (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 (fsm *f, int id, u_char *inp, int len)
{
	u32_t magic;
	
	(void)id;

	/* Check the magic number - don't count replies from ourselves. */
	if (len < 4) {
		LCPDEBUG((LOG_WARNING, "lcp: received short Echo-Reply, length %d\n", len));
		return;
	}
	GETLONG(magic, inp);
	if (lcp_gotoptions[f->unit].neg_magicnumber
			&& magic == lcp_gotoptions[f->unit].magicnumber) {
		LCPDEBUG((LOG_WARNING, "appear to have received our own echo-reply!\n"));
		return;
	}
	
	/* Reset the number of outstanding echo frames */
	lcp_echos_pending = 0;
}

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

static void LcpSendEchoRequest (fsm *f)
{
	u32_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, (u_char)(lcp_echo_number++ & 0xFF), pkt, (int)(pktp - pkt));
	}
}

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

static void lcp_echo_lowerup (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 (int unit)
{
	fsm *f = &lcp_fsm[unit];
	
	if (lcp_echo_timer_running != 0) {
		UNTIMEOUT (LcpEchoTimeout, f);
		lcp_echo_timer_running = 0;
	}
}

#endif /* PPP_SUPPORT */