if (pc->kill_link) {	    	PPPDEBUG((LOG_DEBUG, "pppMainWakeup: unit %d kill_link -> pppStopCB\n", pd));		pc->errCode = PPPERR_USER;		/* This will leave us at PHASE_DEAD. */    		tcpip_callback(pppStopCB, arg);		pc->kill_link = 0;        }        else if (pc->sig_hup) {	    	PPPDEBUG((LOG_DEBUG, "pppMainWakeup: unit %d sig_hup -> pppHupCB\n", pd));		pc->sig_hup = 0;    		tcpip_callback(pppHupCB, arg);        } else {		int c = sio_read(pc->fd, p->payload, p->len);		if(c > 0) {			pppInProc(pd, p->payload, c);		} else {		    PPPDEBUG((LOG_DEBUG, "pppMainWakeup: unit %d sio_read len=%d returned %d\n", pd, p->len, c));		    sys_msleep(250); /* give other tasks a chance to run */		}        }    }	PPPDEBUG((LOG_INFO, "pppMain: unit %d: PHASE_DEAD\n", pd));    pbuf_free(p);out:	PPPDEBUG((LOG_DEBUG, "pppMain: unit %d: linkStatusCB=%lx errCode=%d\n", pd, pc->linkStatusCB, pc->errCode));    if(pc->linkStatusCB)	    pc->linkStatusCB(pc->linkStatusCtx, pc->errCode ? pc->errCode : PPPERR_PROTOCOL, NULL);    pc->openFlag = 0;}static struct pbuf *pppSingleBuf(struct pbuf *p){	struct pbuf *q, *b;	u_char *pl;	if(p->tot_len == p->len)		return p;	q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);	if(!q) {		PPPDEBUG((LOG_ERR,                        "pppSingleBuf: unable to alloc new buf (%d)\n", p->tot_len));		return p; /* live dangerously */	}	for(b = p, pl = q->payload; b != NULL; b = b->next) {		memcpy(pl, b->payload, b->len);		pl += b->len;	}	pbuf_free(p);	return q;}struct pppInputHeader {	int unit;	u16_t proto;};/* * Pass the processed input packet to the appropriate handler. * This function and all handlers run in the context of the tcpip_thread */static void pppInput(void *arg){	struct pbuf *nb = (struct pbuf *)arg;    u16_t protocol;    int pd;	pd = ((struct pppInputHeader *)nb->payload)->unit;	protocol = ((struct pppInputHeader *)nb->payload)->proto;    pbuf_header(nb, -(int)sizeof(struct pppInputHeader));#if LINK_STATS    lwip_stats.link.recv++;#endif /* LINK_STATS */    /*     * Toss all non-LCP packets unless LCP is OPEN.     * Until we get past the authentication phase, toss all packets     * except LCP, LQR and authentication packets.     */    if((lcp_phase[pd] <= PHASE_AUTHENTICATE) && (protocol != PPP_LCP)) {	    if(!((protocol == PPP_LQR) || (protocol == PPP_PAP) || (protocol == PPP_CHAP)) ||			(lcp_phase[pd] != PHASE_AUTHENTICATE)) {		PPPDEBUG((LOG_INFO, "pppInput: discarding proto 0x%04X in phase %d\n", protocol, lcp_phase[pd]));		goto drop;	    }    }    switch(protocol) {    case PPP_VJC_COMP:      /* VJ compressed TCP */#if VJ_SUPPORT > 0        PPPDEBUG((LOG_INFO, "pppInput[%d]: vj_comp in pbuf len=%d\n", pd, nb->len));        /*         * Clip off the VJ header and prepend the rebuilt TCP/IP header and         * pass the result to IP.         */        if (vj_uncompress_tcp(&nb, &pppControl[pd].vjComp) >= 0) {            pppControl[pd].netif.input(nb, &pppControl[pd].netif);			return;        }	/* Something's wrong so drop it. */	PPPDEBUG((LOG_WARNING, "pppInput[%d]: Dropping VJ compressed\n", pd));#else        /* No handler for this protocol so drop the packet. */        PPPDEBUG((LOG_INFO, "pppInput[%d]: drop VJ Comp in %d:%s\n", pd, nb->len, nb->payload));#endif /* VJ_SUPPORT > 0 */	break;    case PPP_VJC_UNCOMP:    /* VJ uncompressed TCP */#if VJ_SUPPORT > 0        PPPDEBUG((LOG_INFO, "pppInput[%d]: vj_un in pbuf len=%d\n", pd, nb->len));        /*         * Process the TCP/IP header for VJ header compression and then pass         * the packet to IP.         */        if (vj_uncompress_uncomp(nb, &pppControl[pd].vjComp) >= 0) {            pppControl[pd].netif.input(nb, &pppControl[pd].netif);			return;        }	/* Something's wrong so drop it. */	PPPDEBUG((LOG_WARNING, "pppInput[%d]: Dropping VJ uncompressed\n", pd));#else        /* No handler for this protocol so drop the packet. */        PPPDEBUG((LOG_INFO,                    "pppInput[%d]: drop VJ UnComp in %d:.*H\n",                     pd, nb->len, LWIP_MIN(nb->len * 2, 40), nb->payload));#endif /* VJ_SUPPORT > 0 */	break;    case PPP_IP:            /* Internet Protocol */        PPPDEBUG((LOG_INFO, "pppInput[%d]: ip in pbuf len=%d\n", pd, nb->len));        pppControl[pd].netif.input(nb, &pppControl[pd].netif);		return;    default:	{		struct protent *protp;		int i;		/*		 * Upcall the proper protocol input routine.		 */		for (i = 0; (protp = ppp_protocols[i]) != NULL; ++i) {			if (protp->protocol == protocol && protp->enabled_flag) {				PPPDEBUG((LOG_INFO, "pppInput[%d]: %s len=%d\n", pd, protp->name, nb->len));				nb = pppSingleBuf(nb);				(*protp->input)(pd, nb->payload, nb->len);				goto out;			}		}		/* No handler for this protocol so reject the packet. */		PPPDEBUG((LOG_INFO, "pppInput[%d]: rejecting unsupported proto 0x%04X len=%d\n", pd, protocol, nb->len));		pbuf_header(nb, sizeof(protocol));#if BYTE_ORDER == LITTLE_ENDIAN		protocol = htons(protocol);		memcpy(nb->payload, &protocol, sizeof(protocol));#endif		lcp_sprotrej(pd, nb->payload, nb->len);	}	break;    }drop:#if LINK_STATS    lwip_stats.link.drop++;#endifout:    pbuf_free(nb);    return;}/* * Drop the input packet. */static void pppDrop(PPPControl *pc){    if (pc->inHead != NULL) {#if 0	            PPPDEBUG((LOG_INFO, "pppDrop: %d:%.*H\n", pc->inHead->len, min(60, pc->inHead->len * 2), pc->inHead->payload));#endif	        PPPDEBUG((LOG_INFO, "pppDrop: pbuf len=%d\n", pc->inHead->len));	if (pc->inTail && (pc->inTail != pc->inHead))	    pbuf_free(pc->inTail);        pbuf_free(pc->inHead);        pc->inHead = NULL;        pc->inTail = NULL;    }#if VJ_SUPPORT > 0    vj_uncompress_err(&pc->vjComp);#endif#if LINK_STATS    lwip_stats.link.drop++;#endif /* LINK_STATS */}/* * Process a received octet string. */static void pppInProc(int pd, u_char *s, int l){    PPPControl *pc = &pppControl[pd];    struct pbuf *nextNBuf;    u_char curChar;    PPPDEBUG((LOG_DEBUG, "pppInProc[%d]: got %d bytes\n", pd, l));    while (l-- > 0) {        curChar = *s++;                /* Handle special characters. */        if (ESCAPE_P(pc->inACCM, curChar)) {            /* Check for escape sequences. */            /* XXX Note that this does not handle an escaped 0x5d character which             * would appear as an escape character.  Since this is an ASCII ']'             * and there is no reason that I know of to escape it, I won't complicate             * the code to handle this case. GLL */            if (curChar == PPP_ESCAPE)                pc->inEscaped = 1;            /* Check for the flag character. */            else if (curChar == PPP_FLAG) {                /* If this is just an extra flag character, ignore it. */                if (pc->inState <= PDADDRESS)                    ;                /* If we haven't received the packet header, drop what has come in. */                else if (pc->inState < PDDATA) {                    PPPDEBUG((LOG_WARNING,                                "pppInProc[%d]: Dropping incomplete packet %d\n",                                 pd, pc->inState));#if LINK_STATS					lwip_stats.link.lenerr++;#endif                    pppDrop(pc);                }                /* If the fcs is invalid, drop the packet. */                else if (pc->inFCS != PPP_GOODFCS) {                    PPPDEBUG((LOG_INFO,                                "pppInProc[%d]: Dropping bad fcs 0x%04X proto=0x%04X\n",                                 pd, pc->inFCS, pc->inProtocol));#if LINK_STATS					lwip_stats.link.chkerr++;#endif                    pppDrop(pc);                }                /* Otherwise it's a good packet so pass it on. */                else {                                        /* Trim off the checksum. */		    if(pc->inTail->len >= 2) {			pc->inTail->len -= 2;			pc->inTail->tot_len = pc->inTail->len;			if (pc->inTail != pc->inHead) {			    pbuf_cat(pc->inHead, pc->inTail);			}		    } else {			pc->inTail->tot_len = pc->inTail->len;			if (pc->inTail != pc->inHead) {			    pbuf_cat(pc->inHead, pc->inTail);			}			pbuf_realloc(pc->inHead, pc->inHead->tot_len - 2);		    }                    /* Dispatch the packet thereby consuming it. */		    if(tcpip_callback(pppInput, pc->inHead) != ERR_OK) {                    	PPPDEBUG((LOG_ERR,				    "pppInProc[%d]: tcpip_callback() failed, dropping packet\n", pd));			pbuf_free(pc->inHead);#if LINK_STATS			lwip_stats.link.drop++;#endif		    }                    pc->inHead = NULL;                    pc->inTail = NULL;                }                                    /* Prepare for a new packet. */                pc->inFCS = PPP_INITFCS;                pc->inState = PDADDRESS;                pc->inEscaped = 0;            }            /* Other characters are usually control characters that may have             * been inserted by the physical layer so here we just drop them. */            else {                PPPDEBUG((LOG_WARNING,                            "pppInProc[%d]: Dropping ACCM char <%d>\n", pd, curChar));            }        }        /* Process other characters. */        else {            /* Unencode escaped characters. */            if (pc->inEscaped) {                pc->inEscaped = 0;                curChar ^= PPP_TRANS;            }                        /* Process character relative to current state. */            switch(pc->inState) {            case PDIDLE:                    /* Idle state - waiting. */                /* Drop the character if it's not 0xff                 * we would have processed a flag character above. */                if (curChar != PPP_ALLSTATIONS) {                	break;				}				/* Fall through */            case PDSTART:                   /* Process start flag. */                /* Prepare for a new packet. */                pc->inFCS = PPP_INITFCS;				/* Fall through */            case PDADDRESS:                 /* Process address field. */                if (curChar == PPP_ALLSTATIONS) {                    pc->inState = PDCONTROL;                    break;                }                /* Else assume compressed address and control fields so                 * fall through to get the protocol... */            case PDCONTROL:                 /* Process control field. */                /* If we don't get a valid control code, restart. */                if (curChar == PPP_UI) {                    pc->inState = PDPROTOCOL1;                	break;                }#if 0                else {                    PPPDEBUG((LOG_WARNING,                                "pppInProc[%d]: Invalid control <%d>\n", pd, curChar));                    pc->inState = PDSTART;                }#endif            case PDPROTOCOL1:               /* Process protocol field 1. */                /* If the lower bit is set, this is the end of the protocol                 * field. */                if (curChar & 1) {                    pc->inProtocol = curChar;                    pc->inState = PDDATA;                }                else {                    pc->inProtocol = (u_int)curChar << 8;                    pc->inState = PDPROTOCOL2;                }                break;            case PDPROTOCOL2:               /* Process protocol field 2. */                pc->inProtocol |= curChar;                pc->inState = PDDATA;                break;            case PDDATA:                    /* Process data byte. */                /* Make space to receive processed data. */                if (pc->inTail == NULL || pc->inTail->len == PBUF_POOL_BUFSIZE) {		    if(pc->inTail) {			pc->inTail->tot_len = pc->inTail->len;			if (pc->inTail != pc->inHead) {			    pbuf_cat(pc->inHead, pc->inTail);			}		    }                    /* If we haven't started a packet, we need a packet header. */                    nextNBuf = pbuf_alloc(PBUF_RAW, 0, PBUF_POOL);                    if (nextNBuf == NULL) {                        /* No free buffers.  Drop the input packet and let the                         * higher layers deal with it.  Continue processing                         * the received pbuf chain in case a new packet starts. */                        PPPDEBUG((LOG_ERR, "pppInProc[%d]: NO FREE MBUFS!\n", pd));#if LINK_STATS						lwip_stats.link.memerr++;#endif /* LINK_STATS */                        pppDrop(pc);                        pc->inState = PDSTART;  /* Wait for flag sequence. */			break;                    }		    if (pc->inHead == NULL) {			struct pppInputHeader *pih = nextNBuf->payload;			pih->unit = pd;			pih->proto = pc->inProtocol;			nextNBuf->len += sizeof(*pih);			pc->inHead = nextNBuf;		    }		    pc->inTail = nextNBuf;                }                /* Load character into buffer. */                ((u_char*)pc->inTail->payload)[pc->inTail->len++] = curChar;                break;            }            /* update the frame check sequence number. */            pc->inFCS = PPP_FCS(pc->inFCS, curChar);        }    }	avRandomize();}#endif /* PPP_SUPPORT */