text: /****************************************************************************
   *
   * Copyright 2016 Samsung Electronics All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied. See the License for the specific
   * language governing permissions and limitations under the License.
   *
   ****************************************************************************/
  
  /*****************************************************************************
  * ppp.c - Network Point to Point Protocol program file.
  *
  * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
  * portions Copyright (c) 1997 by Global Election Systems Inc.
  *
  * The authors hereby grant permission to use, copy, modify, distribute,
  * and license this software and its documentation for any purpose, provided
  * that existing copyright notices are retained in all copies and that this
  * notice and the following disclaimer are included verbatim in any
  * distributions. No written agreement, license, or royalty fee is required
  * for any of the authorized uses.
  *
  * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  * REVISION HISTORY
  *
  * 03-01-01 Marc Boucher <marc@mbsi.ca>
  *   Ported to lwIP.
  * 97-11-05 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
  *   Original.
  *****************************************************************************/
  
  /*
   * ppp_defs.h - PPP definitions.
   *
   * if_pppvar.h - private structures and declarations for PPP.
   *
   * Copyright (c) 1994 The Australian National University.
   * All rights reserved.
   *
   * Permission to use, copy, modify, and distribute this software and its
   * documentation is hereby granted, provided that the above copyright
   * notice appears in all copies.  This software is provided without any
   * warranty, express or implied. The Australian National University
   * makes no representations about the suitability of this software for
   * any purpose.
   *
   * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
   * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
   * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
   * THE AUSTRALIAN NATIONAL UNIVERSITY HAVE BEEN ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
   * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
   * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
   * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
   * OR MODIFICATIONS.
   */
  
  /*
   * if_ppp.h - Point-to-Point Protocol definitions.
   *
   * Copyright (c) 1989 Carnegie Mellon University.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms are permitted
   * provided that the above copyright notice and this paragraph are
   * duplicated in all such forms and that any documentation,
   * advertising materials, and other materials related to such
   * distribution and use acknowledge that the software was developed
   * by Carnegie Mellon University.  The name of the
   * University may not be used to endorse or promote products derived
   * from this software without specific prior written permission.
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
   */
  
  #include <net/lwip/opt.h>
  
  #if PPP_SUPPORT					/* don't build if not configured for use in lwipopts.h */
  
  #include "ppp_impl.h"
  #include <net/lwip/ipv4/ip.h>	/* for ip_input() */
  
  #include "pppdebug.h"
  
  #include "randm.h"
  #include "fsm.h"
  #if PAP_SUPPORT
  #include "pap.h"
  #endif							/* PAP_SUPPORT */
  #if CHAP_SUPPORT
  #include "chap.h"
  #endif							/* CHAP_SUPPORT */
  #include "ipcp.h"
  #include "lcp.h"
  #include "magic.h"
  #include "auth.h"
  #if VJ_SUPPORT
  #include "vj.h"
  #endif							/* VJ_SUPPORT */
  #if PPPOE_SUPPORT
  #include <net/lwip/netif/ppp_oe.h>
  #endif							/* PPPOE_SUPPORT */
  
  #include <net/lwip/tcpip.h>
  #include <net/lwip/api.h>
  #include <net/lwip/snmp.h>
  
  #include <string.h>
  
  /*************************/
  /*** LOCAL DEFINITIONS ***/
  /*************************/
  
  /** PPP_INPROC_MULTITHREADED==1 call pppInput using tcpip_callback().
   * Set this to 0 if pppInProc is called inside tcpip_thread or with NO_SYS==1.
   * Default is 1 for NO_SYS==0 (multithreaded) and 0 for NO_SYS==1 (single-threaded).
   */
  #ifndef PPP_INPROC_MULTITHREADED
  #define PPP_INPROC_MULTITHREADED (NO_SYS == 0)
  #endif
  
  /** PPP_INPROC_OWNTHREAD==1: start a dedicated RX thread per PPP session.
   * Default is 0: call pppos_input() for received raw characters, charcater
   * reception is up to the port */
  #ifndef PPP_INPROC_OWNTHREAD
  #define PPP_INPROC_OWNTHREAD      PPP_INPROC_MULTITHREADED
  #endif
  
  #if PPP_INPROC_OWNTHREAD && !PPP_INPROC_MULTITHREADED
  #error "PPP_INPROC_OWNTHREAD needs PPP_INPROC_MULTITHREADED==1"
  #endif
  
  /*
   * The basic PPP frame.
   */
  #define PPP_ADDRESS(p)  (((u_char *)(p))[0])
  #define PPP_CONTROL(p)  (((u_char *)(p))[1])
  #define PPP_PROTOCOL(p) ((((u_char *)(p))[2] << 8) + ((u_char *)(p))[3])
  
  /* PPP packet parser states.  Current state indicates operation yet to be
   * completed. */
  typedef enum {
  	PDIDLE = 0,					/* Idle state - waiting. */
  	PDSTART,					/* Process start flag. */
  	PDADDRESS,					/* Process address field. */
  	PDCONTROL,					/* Process control field. */
  	PDPROTOCOL1,				/* Process protocol field 1. */
  	PDPROTOCOL2,				/* Process protocol field 2. */
  	PDDATA						/* Process data byte. */
  } PPPDevStates;
  
  #define ESCAPE_P(accm, c) ((accm)[(c) >> 3] & pppACCMMask[c & 0x07])
  
  /************************/
  /*** LOCAL DATA TYPES ***/
  /************************/
  
  /** RX buffer size: this may be configured smaller! */
  #ifndef PPPOS_RX_BUFSIZE
  #define PPPOS_RX_BUFSIZE    (PPP_MRU + PPP_HDRLEN)
  #endif
  
  typedef struct PPPControlRx_s {
  	/** unit number / ppp descriptor */
  	int pd;
  	/** the rx file descriptor */
  	sio_fd_t fd;
  	/** receive buffer - encoded data is stored here */
  #if PPP_INPROC_OWNTHREAD
  	u_char rxbuf[PPPOS_RX_BUFSIZE];
  #endif							/* PPP_INPROC_OWNTHREAD */
  
  	/* The input packet. */
  	struct pbuf *inHead, *inTail;
  
  #if PPPOS_SUPPORT
  	u16_t inProtocol;			/* The input protocol code. */
  	u16_t inFCS;				/* Input Frame Check Sequence value. */
  #endif							/* PPPOS_SUPPORT */
  	PPPDevStates inState;		/* The input process state. */
  	char inEscaped;				/* Escape next character. */
  	ext_accm inACCM;			/* Async-Ctl-Char-Map for input. */
  } PPPControlRx;
  
  /*
   * PPP interface control block.
   */
  typedef struct PPPControl_s {
  	PPPControlRx rx;
  	char openFlag;				/* True when in use. */
  #if PPPOE_SUPPORT
  	struct netif *ethif;
  	struct pppoe_softc *pppoe_sc;
  #endif							/* PPPOE_SUPPORT */
  	int if_up;					/* True when the interface is up. */
  	int errCode;				/* Code indicating why interface is down. */
  #if PPPOS_SUPPORT
  	sio_fd_t fd;				/* File device ID of port. */
  #endif							/* PPPOS_SUPPORT */
  	u16_t mtu;					/* Peer's mru */
  	int pcomp;					/* Does peer accept protocol compression? */
  	int accomp;					/* Does peer accept addr/ctl compression? */
  	u_long lastXMit;			/* Time of last transmission. */
  	ext_accm outACCM;			/* Async-Ctl-Char-Map for output. */
  #if PPPOS_SUPPORT && VJ_SUPPORT
  	int vjEnabled;				/* Flag indicating VJ compression enabled. */
  	struct vjcompress vjComp;	/* Van Jacobson compression header. */
  #endif							/* PPPOS_SUPPORT && VJ_SUPPORT */
  
  	struct netif netif;
  
  	struct ppp_addrs addrs;
  
  	void (*linkStatusCB)(void *ctx, int errCode, void *arg);
  	void *linkStatusCtx;
  
  } PPPControl;
  
  /*
   * Ioctl definitions.
   */
  
  struct npioctl {
  	int protocol;				/* PPP procotol, e.g. PPP_IP */
  	enum NPmode mode;
  };
  
  /***********************************/
  /*** LOCAL FUNCTION DECLARATIONS ***/
  /***********************************/
  #if PPPOS_SUPPORT
  #if PPP_INPROC_OWNTHREAD
  static void pppInputThread(void *arg);
  #endif							/* PPP_INPROC_OWNTHREAD */
  static void pppDrop(PPPControlRx *pcrx);
  static void pppInProc(PPPControlRx *pcrx, u_char *s, int l);
  static void pppFreeCurrentInputPacket(PPPControlRx *pcrx);
  #endif							/* PPPOS_SUPPORT */
  
  /******************************/
  /*** PUBLIC DATA STRUCTURES ***/
  /******************************/
  u_long subnetMask;
  
  static PPPControl pppControl[NUM_PPP];	/* The PPP interface control blocks. */
  
  /*
   * PPP Data Link Layer "protocol" table.
   * One entry per supported protocol.
   * The last entry must be NULL.
   */
  struct protent *ppp_protocols[] = {
  	&lcp_protent,
  #if PAP_SUPPORT
  	&pap_protent,
  #endif							/* PAP_SUPPORT */
  #if CHAP_SUPPORT
  	&chap_protent,
  #endif							/* CHAP_SUPPORT */
  #if CBCP_SUPPORT
  	&cbcp_protent,
  #endif							/* CBCP_SUPPORT */
  	&ipcp_protent,
  #if CCP_SUPPORT
  	&ccp_protent,
  #endif							/* CCP_SUPPORT */
  	NULL
  };
  
  /*
   * Buffers for outgoing packets.  This must be accessed only from the appropriate
   * PPP task so that it doesn't need to be protected to avoid collisions.
   */
  u_char outpacket_buf[NUM_PPP][PPP_MRU + PPP_HDRLEN];
  
  /*****************************/
  /*** LOCAL DATA STRUCTURES ***/
  /*****************************/
  
  #if PPPOS_SUPPORT
  /*
   * FCS lookup table as calculated by genfcstab.
   * @todo: smaller, slower implementation for lower memory footprint?
   */
  static const u_short fcstab[256] = {
  	0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
  	0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
  	0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
  	0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
  	0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
  	0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
  	0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
  	0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
  	0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
  	0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
  	0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
  	0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
  	0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
  	0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
  	0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
  	0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
  	0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
  	0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
  	0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
  	0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
  	0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
  	0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
  	0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
  	0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
  	0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
  	0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
  	0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
  	0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
  	0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
  	0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
  	0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
  	0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
  };
  
  /* PPP's Asynchronous-Control-Character-Map.  The mask array is used
   * to select the specific bit for a character. */
  static u_char pppACCMMask[] = {
  	0x01,
  	0x02,
  	0x04,
  	0x08,
  	0x10,
  	0x20,
  	0x40,
  	0x80
  };
  
  #if PPP_INPROC_OWNTHREAD
  /** Wake up the task blocked in reading from serial line (if any) */
  static void pppRecvWakeup(int pd)
  {
  	PPPDEBUG(LOG_DEBUG, ("pppRecvWakeup: unit %d\n", pd));
  	if (pppControl[pd].openFlag != 0) {
  		sio_read_abort(pppControl[pd].fd);
  	}
  }
  #endif							/* PPP_INPROC_OWNTHREAD */
  #endif							/* PPPOS_SUPPORT */
  
  void pppLinkTerminated(int pd)
  {
  	PPPDEBUG(LOG_DEBUG, ("pppLinkTerminated: unit %d\n", pd));
  
  #if PPPOE_SUPPORT
  	if (pppControl[pd].ethif) {
  		pppoe_disconnect(pppControl[pd].pppoe_sc);
  	} else
  #endif							/* PPPOE_SUPPORT */
  	{
  #if PPPOS_SUPPORT
  		PPPControl *pc;
  #if PPP_INPROC_OWNTHREAD
  		pppRecvWakeup(pd);
  #endif							/* PPP_INPROC_OWNTHREAD */
  		pc = &pppControl[pd];
  
  		PPPDEBUG(LOG_DEBUG, ("pppLinkTerminated: unit %d: linkStatusCB=%p 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;
  		/**/
  #endif							/* PPPOS_SUPPORT */
  	}
  	PPPDEBUG(LOG_DEBUG, ("pppLinkTerminated: finished.\n"));
  }
  
  void pppLinkDown(int pd)
  {
  	PPPDEBUG(LOG_DEBUG, ("pppLinkDown: unit %d\n", pd));
  
  #if PPPOE_SUPPORT
  	if (pppControl[pd].ethif) {
  		pppoe_disconnect(pppControl[pd].pppoe_sc);
  	} else
  #endif							/* PPPOE_SUPPORT */
  	{
  #if PPPOS_SUPPORT && PPP_INPROC_OWNTHREAD
  		pppRecvWakeup(pd);
  #endif							/* PPPOS_SUPPORT && PPP_INPROC_OWNTHREAD */
  	}
  }
  
  /** Initiate LCP open request */
  static void pppStart(int pd)
  {
  	PPPDEBUG(LOG_DEBUG, ("pppStart: unit %d\n", pd));
  	lcp_lowerup(pd);
  	lcp_open(pd);				/* Start protocol */
  	PPPDEBUG(LOG_DEBUG, ("pppStart: finished\n"));
  }
  
  /** LCP close request */
  static void pppStop(int pd)
  {
  	PPPDEBUG(LOG_DEBUG, ("pppStop: unit %d\n", pd));
  	lcp_close(pd, "User request");
  }
  
  /** Called when carrier/link is lost */
  static void pppHup(int pd)
  {
  	PPPDEBUG(LOG_DEBUG, ("pppHupCB: unit %d\n", pd));
  	lcp_lowerdown(pd);
  	link_terminated(pd);
  }
  
  /***********************************/
  /*** PUBLIC FUNCTION DEFINITIONS ***/
  /***********************************/
  /* Initialize the PPP subsystem. */
  
  struct ppp_settings ppp_settings;
  
  void pppInit(void)
  {
  	struct protent *protp;
  	int i, j;
  
  	memset(&ppp_settings, 0, sizeof(ppp_settings));
  	ppp_settings.usepeerdns = 1;
  	pppSetAuth(PPPAUTHTYPE_NONE, NULL, NULL);
  
  	magicInit();
  
  	subnetMask = PP_HTONL(0xffffff00UL);
  
  	for (i = 0; i < NUM_PPP; i++) {
  		/* Initialize each protocol to the standard option set. */
  		for (j = 0; (protp = ppp_protocols[j]) != NULL; ++j) {
  			(*protp->init)(i);
  		}
  	}
  }
  
  void pppSetAuth(enum pppAuthType authType, const char *user, const char *passwd)
  {
  	switch (authType) {
  	case PPPAUTHTYPE_NONE:
  	default:
  #ifdef LWIP_PPP_STRICT_PAP_REJECT
  				ppp_settings.refuse_pap = 1;
  #else							/* LWIP_PPP_STRICT_PAP_REJECT */
  				/* some providers request pap and accept an empty login/pw */
  				ppp_settings.refuse_pap = 0;
  #endif							/* LWIP_PPP_STRICT_PAP_REJECT */
  		ppp_settings.refuse_chap = 1;
  		break;
  
  	case PPPAUTHTYPE_ANY:
  		/* Warning: Using PPPAUTHTYPE_ANY might have security consequences.
  		 * RFC 1994 says:
  		 *
  		 * In practice, within or associated with each PPP server, there is a
  		 * database which associates "user" names with authentication
  		 * information ("secrets").  It is not anticipated that a particular
  		 * named user would be authenticated by multiple methods.  This would
  		 * make the user vulnerable to attacks which negotiate the least secure
  		 * method from among a set (such as PAP rather than CHAP).  If the same
  		 * secret was used, PAP would reveal the secret to be used later with
  		 * CHAP.
  		 *
  		 * Instead, for each user name there should be an indication of exactly
  		 * one method used to authenticate that user name.  If a user needs to
  		 * make use of different authentication methods under different
  		 * circumstances, then distinct user names SHOULD be employed, each of
  		 * which identifies exactly one authentication method.
  		 *
  		 */
  		ppp_settings.refuse_pap = 0;
  		ppp_settings.refuse_chap = 0;
  		break;
  
  	case PPPAUTHTYPE_PAP:
  		ppp_settings.refuse_pap = 0;
  		ppp_settings.refuse_chap = 1;
  		break;
  
  	case PPPAUTHTYPE_CHAP:
  		ppp_settings.refuse_pap = 1;
  		ppp_settings.refuse_chap = 0;
  		break;
  	}
  
  	if (user) {
  		strncpy(ppp_settings.user, user, sizeof(ppp_settings.user) - 1);
  		ppp_settings.user[sizeof(ppp_settings.user) - 1] = '\0';
  	} else {
  		ppp_settings.user[0] = '\0';
  	}
  
  	if (passwd) {
  		strncpy(ppp_settings.passwd, passwd, sizeof(ppp_settings.passwd) - 1);
  		ppp_settings.passwd[sizeof(ppp_settings.passwd) - 1] = '\0';
  	} else {
  		ppp_settings.passwd[0] = '\0';
  	}
  }
  
  #if PPPOS_SUPPORT
  /** Open a new PPP connection using the given I/O device.
   * This initializes the PPP control block but does not
   * attempt to negotiate the LCP session.  If this port
   * connects to a modem, the modem connection must be
   * established before calling this.
   * Return a new PPP connection descriptor on success or
   * an error code (negative) on failure.
   *
   * pppOpen() is directly defined to this function.
   */
  int pppOverSerialOpen(sio_fd_t fd, pppLinkStatusCB_fn linkStatusCB, void *linkStatusCtx)
  {
  	PPPControl *pc;
  	int pd;
  
  	if (linkStatusCB == NULL) {
  		/* PPP is single-threaded: without a callback,
  		 * there is no way to know when the link is up. */
  		return PPPERR_PARAM;
  	}
  
  	/* Find a free PPP session descriptor. */
  	for (pd = 0; pd < NUM_PPP && pppControl[pd].openFlag != 0; pd++) ;
  
  	if (pd >= NUM_PPP) {
  		pd = PPPERR_OPEN;
  	} else {
  		pc = &pppControl[pd];
  		/* input pbuf left over from last session? */
  		pppFreeCurrentInputPacket(&pc->rx);
  		/* @todo: is this correct or do I overwrite something? */
  		memset(pc, 0, sizeof(PPPControl));
  		pc->rx.pd = pd;
  		pc->rx.fd = fd;
  
  		pc->openFlag = 1;
  		pc->fd = fd;
  
  #if VJ_SUPPORT
  		vj_compress_init(&pc->vjComp);
  #endif							/* VJ_SUPPORT */
  
  		/*
  		 * Default the in and out accm so that escape and flag characters
  		 * are always escaped.
  		 */
  		pc->rx.inACCM[15] = 0x60;	/* no need to protect since RX is not running */
  		pc->outACCM[15] = 0x60;
  
  		pc->linkStatusCB = linkStatusCB;
  		pc->linkStatusCtx = linkStatusCtx;
  
  		/*
  		 * Start the connection and handle incoming events (packet or timeout).
  		 */
  		PPPDEBUG(LOG_INFO, ("pppOverSerialOpen: unit %d: Connecting\n", pd));
  		pppStart(pd);
  #if PPP_INPROC_OWNTHREAD
  		sys_thread_new(PPP_THREAD_NAME, pppInputThread, (void *)&pc->rx, PPP_THREAD_STACKSIZE, PPP_THREAD_PRIO);
  #endif							/* PPP_INPROC_OWNTHREAD */
  	}
  
  	return pd;
  }
  #endif							/* PPPOS_SUPPORT */
  
  #if PPPOE_SUPPORT
  static void pppOverEthernetLinkStatusCB(int pd, int up);
  
  void pppOverEthernetClose(int pd)
  {
  	PPPControl *pc = &pppControl[pd];
  
  	/* *TJL* There's no lcp_deinit */
  	lcp_close(pd, NULL);
  
  	pppoe_destroy(&pc->netif);
  }
  
  int pppOverEthernetOpen(struct netif *ethif, const char *service_name, const char *concentrator_name, pppLinkStatusCB_fn linkStatusCB, void *linkStatusCtx)
  {
  	PPPControl *pc;
  	int pd;
  
  	LWIP_UNUSED_ARG(service_name);
  	LWIP_UNUSED_ARG(concentrator_name);
  
  	if (linkStatusCB == NULL) {
  		/* PPP is single-threaded: without a callback,
  		 * there is no way to know when the link is up. */
  		return PPPERR_PARAM;
  	}
  
  	/* Find a free PPP session descriptor. Critical region? */
  	for (pd = 0; pd < NUM_PPP && pppControl[pd].openFlag != 0; pd++) ;
  	if (pd >= NUM_PPP) {
  		pd = PPPERR_OPEN;
  	} else {
  		pc = &pppControl[pd];
  		memset(pc, 0, sizeof(PPPControl));
  		pc->openFlag = 1;
  		pc->ethif = ethif;
  
  		pc->linkStatusCB = linkStatusCB;
  		pc->linkStatusCtx = linkStatusCtx;
  
  		lcp_wantoptions[pd].mru = PPPOE_MAXMTU;
  		lcp_wantoptions[pd].neg_asyncmap = 0;
  		lcp_wantoptions[pd].neg_pcompression = 0;
  		lcp_wantoptions[pd].neg_accompression = 0;
  
  		lcp_allowoptions[pd].mru = PPPOE_MAXMTU;
  		lcp_allowoptions[pd].neg_asyncmap = 0;
  		lcp_allowoptions[pd].neg_pcompression = 0;
  		lcp_allowoptions[pd].neg_accompression = 0;
  
  		if (pppoe_create(ethif, pd, pppOverEthernetLinkStatusCB, &pc->pppoe_sc) != ERR_OK) {
  			pc->openFlag = 0;
  			return PPPERR_OPEN;
  		}
  
  		pppoe_connect(pc->pppoe_sc);
  	}
  
  	return pd;
  }
  #endif							/* PPPOE_SUPPORT */
  
  /* Close a PPP connection and release the descriptor.
   * Any outstanding packets in the queues are dropped.
   * Return 0 on success, an error code on failure. */
  int pppClose(int pd)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 0;
  
  	PPPDEBUG(LOG_DEBUG, ("pppClose() called\n"));
  
  	/* Disconnect */
  #if PPPOE_SUPPORT
  	if (pc->ethif) {
  		PPPDEBUG(LOG_DEBUG, ("pppClose: unit %d kill_link -> pppStop\n", pd));
  		pc->errCode = PPPERR_USER;
  		/* This will leave us at PHASE_DEAD. */
  		pppStop(pd);
  	} else
  #endif							/* PPPOE_SUPPORT */
  	{
  #if PPPOS_SUPPORT
  		PPPDEBUG(LOG_DEBUG, ("pppClose: unit %d kill_link -> pppStop\n", pd));
  		pc->errCode = PPPERR_USER;
  		/* This will leave us at PHASE_DEAD. */
  		pppStop(pd);
  #if PPP_INPROC_OWNTHREAD
  		pppRecvWakeup(pd);
  #endif							/* PPP_INPROC_OWNTHREAD */
  #endif							/* PPPOS_SUPPORT */
  	}
  
  	return st;
  }
  
  /* This function is called when carrier is lost on the PPP channel. */
  void pppSigHUP(int pd)
  {
  	PPPDEBUG(LOG_DEBUG, ("pppSigHUP: unit %d sig_hup -> pppHupCB\n", pd));
  	pppHup(pd);
  }
  
  #if PPPOS_SUPPORT
  static void nPut(PPPControl *pc, struct pbuf *nb)
  {
  	struct pbuf *b;
  	int c;
  
  	for (b = nb; b != NULL; b = b->next) {
  		if ((c = sio_write(pc->fd, b->payload, b->len)) != b->len) {
  			PPPDEBUG(LOG_WARNING, ("PPP nPut: incomplete sio_write(fd:%" SZT_F ", len:%d, c: 0x%" X8_F ") c = %d\n", (size_t)pc->fd, b->len, c, c));
  			LINK_STATS_INC(link.err);
  			pc->lastXMit = 0;	/* prepend PPP_FLAG to next packet */
  			snmp_inc_ifoutdiscards(&pc->netif);
  			pbuf_free(nb);
  			return;
  		}
  	}
  
  	snmp_add_ifoutoctets(&pc->netif, nb->tot_len);
  	snmp_inc_ifoutucastpkts(&pc->netif);
  	pbuf_free(nb);
  	LINK_STATS_INC(link.xmit);
  }
  
  /*
   * pppAppend - append given character to end of given pbuf.  If outACCM
   * is not NULL and the character needs to be escaped, do so.
   * If pbuf is full, append another.
   * Return the current pbuf.
   */
  static struct pbuf *pppAppend(u_char c, struct pbuf *nb, ext_accm *outACCM)
  {
  	struct pbuf *tb = nb;
  
  	/* Make sure there is room for the character and an escape code.
  	 * Sure we don't quite fill the buffer if the character doesn't
  	 * get escaped but is one character worth complicating this? */
  	/* Note: We assume no packet header. */
  	if (nb && (PBUF_POOL_BUFSIZE - nb->len) < 2) {
  		tb = pbuf_alloc(PBUF_RAW, 0, PBUF_POOL);
  		if (tb) {
  			nb->next = tb;
  		} else {
  			LINK_STATS_INC(link.memerr);
  		}
  		nb = tb;
  	}
  
  	if (nb) {
  		if (outACCM && ESCAPE_P(*outACCM, c)) {
  			*((u_char *)nb->payload + nb->len++) = PPP_ESCAPE;
  			*((u_char *)nb->payload + nb->len++) = c ^ PPP_TRANS;
  		} else {
  			*((u_char *)nb->payload + nb->len++) = c;
  		}
  	}
  
  	return tb;
  }
  #endif							/* PPPOS_SUPPORT */
  
  #if PPPOE_SUPPORT
  static err_t pppifOutputOverEthernet(int pd, struct pbuf *p)
  {
  	PPPControl *pc = &pppControl[pd];
  	struct pbuf *pb;
  	u_short protocol = PPP_IP;
  	int i = 0;
  	u16_t tot_len;
  
  	/* @todo: try to use pbuf_header() here! */
  	pb = pbuf_alloc(PBUF_LINK, PPPOE_HDRLEN + sizeof(protocol), PBUF_RAM);
  	if (!pb) {
  		LINK_STATS_INC(link.memerr);
  		LINK_STATS_INC(link.proterr);
  		snmp_inc_ifoutdiscards(&pc->netif);
  		return ERR_MEM;
  	}
  
  	pbuf_header(pb, -(s16_t)PPPOE_HDRLEN);
  
  	pc->lastXMit = sys_jiffies();
  
  	if (!pc->pcomp || protocol > 0xFF) {
  		*((u_char *)pb->payload + i++) = (protocol >> 8) & 0xFF;
  	}
  	*((u_char *)pb->payload + i) = protocol & 0xFF;
  
  	pbuf_chain(pb, p);
  	tot_len = pb->tot_len;
  
  	if (pppoe_xmit(pc->pppoe_sc, pb) != ERR_OK) {
  		LINK_STATS_INC(link.err);
  		snmp_inc_ifoutdiscards(&pc->netif);
  		return PPPERR_DEVICE;
  	}
  
  	snmp_add_ifoutoctets(&pc->netif, tot_len);
  	snmp_inc_ifoutucastpkts(&pc->netif);
  	LINK_STATS_INC(link.xmit);
  	return ERR_OK;
  }
  #endif							/* PPPOE_SUPPORT */
  
  /* Send a packet on the given connection. */
  static err_t pppifOutput(struct netif *netif, struct pbuf *pb, ip_addr_t *ipaddr)
  {
  	int pd = (int)(size_t)netif->state;
  	PPPControl *pc = &pppControl[pd];
  #if PPPOS_SUPPORT
  	u_short protocol = PPP_IP;
  	u_int fcsOut = PPP_INITFCS;
  	struct pbuf *headMB = NULL, *tailMB = NULL, *p;
  	u_char c;
  #endif							/* PPPOS_SUPPORT */
  
  	LWIP_UNUSED_ARG(ipaddr);
  
  	/* Validate parameters. */
  	/* We let any protocol value go through - it can't hurt us
  	 * and the peer will just drop it if it's not accepting it. */
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag || !pb) {
  		PPPDEBUG(LOG_WARNING, ("pppifOutput[%d]: bad parms prot=%d pb=%p\n", pd, PPP_IP, pb));
  		LINK_STATS_INC(link.opterr);
  		LINK_STATS_INC(link.drop);
  		snmp_inc_ifoutdiscards(netif);
  		return ERR_ARG;
  	}
  
  	/* Check that the link is up. */
  	if (lcp_phase[pd] == PHASE_DEAD) {
  		PPPDEBUG(LOG_ERR, ("pppifOutput[%d]: link not up\n", pd));
  		LINK_STATS_INC(link.rterr);
  		LINK_STATS_INC(link.drop);
  		snmp_inc_ifoutdiscards(netif);
  		return ERR_RTE;
  	}
  #if PPPOE_SUPPORT
  	if (pc->ethif) {
  		return pppifOutputOverEthernet(pd, pb);
  	}
  #endif							/* PPPOE_SUPPORT */
  
  #if PPPOS_SUPPORT
  	/* Grab an output buffer. */
  	headMB = pbuf_alloc(PBUF_RAW, 0, PBUF_POOL);
  	if (headMB == NULL) {
  		PPPDEBUG(LOG_WARNING, ("pppifOutput[%d]: first alloc fail\n", pd));
  		LINK_STATS_INC(link.memerr);
  		LINK_STATS_INC(link.drop);
  		snmp_inc_ifoutdiscards(netif);
  		return ERR_MEM;
  	}
  #if VJ_SUPPORT
  	/*
  	 * Attempt Van Jacobson header compression if VJ is configured and
  	 * this is an IP packet.
  	 */
  	if (protocol == PPP_IP && pc->vjEnabled) {
  		switch (vj_compress_tcp(&pc->vjComp, pb)) {
  		case TYPE_IP:
  			/* No change...
  			   protocol = PPP_IP_PROTOCOL; */
  			break;
  		case TYPE_COMPRESSED_TCP:
  			protocol = PPP_VJC_COMP;
  			break;
  		case TYPE_UNCOMPRESSED_TCP:
  			protocol = PPP_VJC_UNCOMP;
  			break;
  		default:
  			PPPDEBUG(LOG_WARNING, ("pppifOutput[%d]: bad IP packet\n", pd));
  			LINK_STATS_INC(link.proterr);
  			LINK_STATS_INC(link.drop);
  			snmp_inc_ifoutdiscards(netif);
  			pbuf_free(headMB);
  			return ERR_VAL;
  		}
  	}
  #endif							/* VJ_SUPPORT */
  
  	tailMB = headMB;
  
  	/* Build the PPP header. */
  	if ((sys_jiffies() - pc->lastXMit) >= PPP_MAXIDLEFLAG) {
  		tailMB = pppAppend(PPP_FLAG, tailMB, NULL);
  	}
  
  	pc->lastXMit = sys_jiffies();
  	if (!pc->accomp) {
  		fcsOut = PPP_FCS(fcsOut, PPP_ALLSTATIONS);
  		tailMB = pppAppend(PPP_ALLSTATIONS, tailMB, &pc->outACCM);
  		fcsOut = PPP_FCS(fcsOut, PPP_UI);
  		tailMB = pppAppend(PPP_UI, tailMB, &pc->outACCM);
  	}
  	if (!pc->pcomp || protocol > 0xFF) {
  		c = (protocol >> 8) & 0xFF;
  		fcsOut = PPP_FCS(fcsOut, c);
  		tailMB = pppAppend(c, tailMB, &pc->outACCM);
  	}
  	c = protocol & 0xFF;
  	fcsOut = PPP_FCS(fcsOut, c);
  	tailMB = pppAppend(c, tailMB, &pc->outACCM);
  
  	/* Load packet. */
  	for (p = pb; p; p = p->next) {
  		int n;
  		u_char *sPtr;
  
  		sPtr = (u_char *)p->payload;
  		n = p->len;
  		while (n-- > 0) {
  			c = *sPtr++;
  
  			/* Update FCS before checking for special characters. */
  			fcsOut = PPP_FCS(fcsOut, c);
  
  			/* Copy to output buffer escaping special characters. */
  			tailMB = pppAppend(c, tailMB, &pc->outACCM);
  		}
  	}
  
  	/* Add FCS and trailing flag. */
  	c = ~fcsOut & 0xFF;
  	tailMB = pppAppend(c, tailMB, &pc->outACCM);
  	c = (~fcsOut >> 8) & 0xFF;
  	tailMB = pppAppend(c, tailMB, &pc->outACCM);
  	tailMB = pppAppend(PPP_FLAG, tailMB, NULL);
  
  	/* If we failed to complete the packet, throw it away. */
  	if (!tailMB) {
  		PPPDEBUG(LOG_WARNING, ("pppifOutput[%d]: Alloc err - dropping proto=%d\n", pd, protocol));
  		pbuf_free(headMB);
  		LINK_STATS_INC(link.memerr);
  		LINK_STATS_INC(link.drop);
  		snmp_inc_ifoutdiscards(netif);
  		return ERR_MEM;
  	}
  
  	/* Send it. */
  	PPPDEBUG(LOG_INFO, ("pppifOutput[%d]: proto=0x%" X16_F "\n", pd, protocol));
  
  	nPut(pc, headMB);
  #endif							/* PPPOS_SUPPORT */
  
  	return ERR_OK;
  }
  
  /* Get and set parameters for the given connection.
   * Return 0 on success, an error code on failure. */
  int pppIOCtl(int pd, int cmd, void *arg)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 0;
  
  	if (pd < 0 || pd >= NUM_PPP) {
  		st = PPPERR_PARAM;
  	} else {
  		switch (cmd) {
  		case PPPCTLG_UPSTATUS:	/* Get the PPP up status. */
  			if (arg) {
  				*(int *)arg = (int)(pc->if_up);
  			} else {
  				st = PPPERR_PARAM;
  			}
  			break;
  		case PPPCTLS_ERRCODE:	/* Set the PPP error code. */
  			if (arg) {
  				pc->errCode = *(int *)arg;
  			} else {
  				st = PPPERR_PARAM;
  			}
  			break;
  		case PPPCTLG_ERRCODE:	/* Get the PPP error code. */
  			if (arg) {
  				*(int *)arg = (int)(pc->errCode);
  			} else {
  				st = PPPERR_PARAM;
  			}
  			break;
  #if PPPOS_SUPPORT
  		case PPPCTLG_FD:		/* Get the fd associated with the ppp */
  			if (arg) {
  				*(sio_fd_t *)arg = pc->fd;
  			} else {
  				st = PPPERR_PARAM;
  			}
  			break;
  #endif							/* PPPOS_SUPPORT */
  		default:
  			st = PPPERR_PARAM;
  			break;
  		}
  	}
  
  	return st;
  }
  
  /*
   * Return the Maximum Transmission Unit for the given PPP connection.
   */
  u_short pppMTU(int pd)
  {
  	PPPControl *pc = &pppControl[pd];
  	u_short st;
  
  	/* Validate parameters. */
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag) {
  		st = 0;
  	} else {
  		st = pc->mtu;
  	}
  
  	return st;
  }
  
  #if PPPOE_SUPPORT
  int pppWriteOverEthernet(int pd, const u_char *s, int n)
  {
  	PPPControl *pc = &pppControl[pd];
  	struct pbuf *pb;
  
  	/* skip address & flags */
  	s += 2;
  	n -= 2;
  
  	LWIP_ASSERT("PPPOE_HDRLEN + n <= 0xffff", PPPOE_HDRLEN + n <= 0xffff);
  	pb = pbuf_alloc(PBUF_LINK, (u16_t)(PPPOE_HDRLEN + n), PBUF_RAM);
  	if (!pb) {
  		LINK_STATS_INC(link.memerr);
  		LINK_STATS_INC(link.proterr);
  		snmp_inc_ifoutdiscards(&pc->netif);
  		return PPPERR_ALLOC;
  	}
  
  	pbuf_header(pb, -(s16_t)PPPOE_HDRLEN);
  
  	pc->lastXMit = sys_jiffies();
  
  	MEMCPY(pb->payload, s, n);
  
  	if (pppoe_xmit(pc->pppoe_sc, pb) != ERR_OK) {
  		LINK_STATS_INC(link.err);
  		snmp_inc_ifoutdiscards(&pc->netif);
  		return PPPERR_DEVICE;
  	}
  
  	snmp_add_ifoutoctets(&pc->netif, (u16_t)n);
  	snmp_inc_ifoutucastpkts(&pc->netif);
  	LINK_STATS_INC(link.xmit);
  	return PPPERR_NONE;
  }
  #endif							/* PPPOE_SUPPORT */
  
  /*
   * Write n characters to a ppp link.
   *  RETURN: >= 0 Number of characters written
   *           -1 Failed to write to device
   */
  int pppWrite(int pd, const u_char *s, int n)
  {
  	PPPControl *pc = &pppControl[pd];
  #if PPPOS_SUPPORT
  	u_char c;
  	u_int fcsOut;
  	struct pbuf *headMB, *tailMB;
  #endif							/* PPPOS_SUPPORT */
  
  #if PPPOE_SUPPORT
  	if (pc->ethif) {
  		return pppWriteOverEthernet(pd, s, n);
  	}
  #endif							/* PPPOE_SUPPORT */
  
  #if PPPOS_SUPPORT
  	headMB = pbuf_alloc(PBUF_RAW, 0, PBUF_POOL);
  	if (headMB == NULL) {
  		LINK_STATS_INC(link.memerr);
  		LINK_STATS_INC(link.proterr);
  		snmp_inc_ifoutdiscards(&pc->netif);
  		return PPPERR_ALLOC;
  	}
  
  	tailMB = headMB;
  
  	/* If the link has been idle, we'll send a fresh flag character to
  	 * flush any noise. */
  	if ((sys_jiffies() - pc->lastXMit) >= PPP_MAXIDLEFLAG) {
  		tailMB = pppAppend(PPP_FLAG, tailMB, NULL);
  	}
  	pc->lastXMit = sys_jiffies();
  
  	fcsOut = PPP_INITFCS;
  	/* Load output buffer. */
  	while (n-- > 0) {
  		c = *s++;
  
  		/* Update FCS before checking for special characters. */
  		fcsOut = PPP_FCS(fcsOut, c);
  
  		/* Copy to output buffer escaping special characters. */
  		tailMB = pppAppend(c, tailMB, &pc->outACCM);
  	}
  
  	/* Add FCS and trailing flag. */
  	c = ~fcsOut & 0xFF;
  	tailMB = pppAppend(c, tailMB, &pc->outACCM);
  	c = (~fcsOut >> 8) & 0xFF;
  	tailMB = pppAppend(c, tailMB, &pc->outACCM);
  	tailMB = pppAppend(PPP_FLAG, tailMB, NULL);
  
  	/* If we failed to complete the packet, throw it away.
  	 * Otherwise send it. */
  	if (!tailMB) {
  		PPPDEBUG(LOG_WARNING, ("pppWrite[%d]: Alloc err - dropping pbuf len=%d\n", pd, headMB->len));
  		/*"pppWrite[%d]: Alloc err - dropping %d:%.*H", pd, headMB->len, LWIP_MIN(headMB->len * 2, 40), headMB->payload)); */
  		pbuf_free(headMB);
  		LINK_STATS_INC(link.memerr);
  		LINK_STATS_INC(link.proterr);
  		snmp_inc_ifoutdiscards(&pc->netif);
  		return PPPERR_ALLOC;
  	}
  
  	PPPDEBUG(LOG_INFO, ("pppWrite[%d]: len=%d\n", pd, headMB->len));
  	/* "pppWrite[%d]: %d:%.*H", pd, headMB->len, LWIP_MIN(headMB->len * 2, 40), headMB->payload)); */
  	nPut(pc, headMB);
  #endif							/* PPPOS_SUPPORT */
  
  	return PPPERR_NONE;
  }
  
  /*
   * ppp_send_config - configure the transmit characteristics of
   * the ppp interface.
   */
  void ppp_send_config(int unit, u16_t mtu, u32_t asyncmap, int pcomp, int accomp)
  {
  	PPPControl *pc = &pppControl[unit];
  	int i;
  
  	pc->mtu = mtu;
  	pc->pcomp = pcomp;
  	pc->accomp = accomp;
  
  	/* Load the ACCM bits for the 32 control codes. */
  	for (i = 0; i < 32 / 8; i++) {
  		pc->outACCM[i] = (u_char)((asyncmap >> (8 * i)) & 0xFF);
  	}
  	PPPDEBUG(LOG_INFO, ("ppp_send_config[%d]: outACCM=%X %X %X %X\n", unit, pc->outACCM[0], pc->outACCM[1], pc->outACCM[2], pc->outACCM[3]));
  }
  
  /*
   * ppp_set_xaccm - set the extended transmit ACCM for the interface.
   */
  void ppp_set_xaccm(int unit, ext_accm *accm)
  {
  	SMEMCPY(pppControl[unit].outACCM, accm, sizeof(ext_accm));
  	PPPDEBUG(LOG_INFO, ("ppp_set_xaccm[%d]: outACCM=%X %X %X %X\n", unit, pppControl[unit].outACCM[0], pppControl[unit].outACCM[1], pppControl[unit].outACCM[2], pppControl[unit].outACCM[3]));
  }
  
  /*
   * ppp_recv_config - configure the receive-side characteristics of
   * the ppp interface.
   */
  void ppp_recv_config(int unit, int mru, u32_t asyncmap, int pcomp, int accomp)
  {
  	PPPControl *pc = &pppControl[unit];
  	int i;
  	SYS_ARCH_DECL_PROTECT(lev);
  
  	LWIP_UNUSED_ARG(accomp);
  	LWIP_UNUSED_ARG(pcomp);
  	LWIP_UNUSED_ARG(mru);
  
  	/* Load the ACCM bits for the 32 control codes. */
  	SYS_ARCH_PROTECT(lev);
  	for (i = 0; i < 32 / 8; i++) {
  		/* @todo: does this work? ext_accm has been modified from pppd! */
  		pc->rx.inACCM[i] = (u_char)(asyncmap >> (i * 8));
  	}
  	SYS_ARCH_UNPROTECT(lev);
  	PPPDEBUG(LOG_INFO, ("ppp_recv_config[%d]: inACCM=%X %X %X %X\n", unit, pc->rx.inACCM[0], pc->rx.inACCM[1], pc->rx.inACCM[2], pc->rx.inACCM[3]));
  }
  
  #if 0
  /*
   * ccp_test - ask kernel whether a given compression method
   * is acceptable for use.  Returns 1 if the method and parameters
   * are OK, 0 if the method is known but the parameters are not OK
   * (e.g. code size should be reduced), or -1 if the method is unknown.
   */
  int ccp_test(int unit, int opt_len, int for_transmit, u_char *opt_ptr)
  {
  	return 0;					/* XXX Currently no compression. */
  }
  
  /*
   * ccp_flags_set - inform kernel about the current state of CCP.
   */
  void ccp_flags_set(int unit, int isopen, int isup)
  {
  	/* XXX */
  }
  
  /*
   * ccp_fatal_error - returns 1 if decompression was disabled as a
   * result of an error detected after decompression of a packet,
   * 0 otherwise.  This is necessary because of patent nonsense.
   */
  int ccp_fatal_error(int unit)
  {
  	/* XXX */
  	return 0;
  }
  #endif
  
  /*
   * get_idle_time - return how long the link has been idle.
   */
  int get_idle_time(int u, struct ppp_idle *ip)
  {
  	/* XXX */
  	LWIP_UNUSED_ARG(u);
  	LWIP_UNUSED_ARG(ip);
  
  	return 0;
  }
  
  /*
   * Return user specified netmask, modified by any mask we might determine
   * for address `addr' (in network byte order).
   * Here we scan through the system's list of interfaces, looking for
   * any non-point-to-point interfaces which might appear to be on the same
   * network as `addr'.  If we find any, we OR in their netmask to the
   * user-specified netmask.
   */
  u32_t GetMask(u32_t addr)
  {
  	u32_t mask, nmask;
  
  	addr = htonl(addr);
  	if (IP_CLASSA(addr)) {		/* determine network mask for address class */
  		nmask = IP_CLASSA_NET;
  	} else if (IP_CLASSB(addr)) {
  		nmask = IP_CLASSB_NET;
  	} else {
  		nmask = IP_CLASSC_NET;
  	}
  
  	/* class D nets are disallowed by bad_ip_adrs */
  	mask = subnetMask | htonl(nmask);
  
  	/* XXX
  	 * Scan through the system's network interfaces.
  	 * Get each netmask and OR them into our mask.
  	 */
  
  	return mask;
  }
  
  /*
   * sifvjcomp - config tcp header compression
   */
  int sifvjcomp(int pd, int vjcomp, u8_t cidcomp, u8_t maxcid)
  {
  #if PPPOS_SUPPORT && VJ_SUPPORT
  	PPPControl *pc = &pppControl[pd];
  
  	pc->vjEnabled = vjcomp;
  	pc->vjComp.compressSlot = cidcomp;
  	pc->vjComp.maxSlotIndex = maxcid;
  	PPPDEBUG(LOG_INFO, ("sifvjcomp: VJ compress enable=%d slot=%d max slot=%d\n", vjcomp, cidcomp, maxcid));
  #else							/* PPPOS_SUPPORT && VJ_SUPPORT */
  	LWIP_UNUSED_ARG(pd);
  	LWIP_UNUSED_ARG(vjcomp);
  	LWIP_UNUSED_ARG(cidcomp);
  	LWIP_UNUSED_ARG(maxcid);
  #endif							/* PPPOS_SUPPORT && VJ_SUPPORT */
  
  	return 0;
  }
  
  /*
   * pppifNetifInit - netif init callback
   */
  static err_t pppifNetifInit(struct netif *netif)
  {
  	netif->name[0] = 'p';
  	netif->name[1] = 'p';
  	netif->output = pppifOutput;
  	netif->mtu = pppMTU((int)(size_t)netif->state);
  	netif->flags = NETIF_FLAG_POINTTOPOINT | NETIF_FLAG_LINK_UP;
  #if LWIP_NETIF_HOSTNAME
  	/* @todo: Initialize interface hostname */
  	/* netif_set_hostname(netif, "lwip"); */
  #endif							/* LWIP_NETIF_HOSTNAME */
  	return ERR_OK;
  }
  
  /*
   * sifup - Config the interface up and enable IP packets to pass.
   */
  int sifup(int pd)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 1;
  
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag) {
  		st = 0;
  		PPPDEBUG(LOG_WARNING, ("sifup[%d]: bad parms\n", pd));
  	} else {
  		netif_remove(&pc->netif);
  		if (netif_add(&pc->netif, &pc->addrs.our_ipaddr, &pc->addrs.netmask, &pc->addrs.his_ipaddr, (void *)(size_t)pd, pppifNetifInit, ip_input)) {
  			netif_set_up(&pc->netif);
  			pc->if_up = 1;
  			pc->errCode = PPPERR_NONE;
  
  			PPPDEBUG(LOG_DEBUG, ("sifup: unit %d: linkStatusCB=%p errCode=%d\n", pd, pc->linkStatusCB, pc->errCode));
  			if (pc->linkStatusCB) {
  				pc->linkStatusCB(pc->linkStatusCtx, pc->errCode, &pc->addrs);
  			}
  		} else {
  			st = 0;
  			PPPDEBUG(LOG_ERR, ("sifup[%d]: netif_add failed\n", pd));
  		}
  	}
  
  	return st;
  }
  
  /*
   * sifnpmode - Set the mode for handling packets for a given NP.
   */
  int sifnpmode(int u, int proto, enum NPmode mode)
  {
  	LWIP_UNUSED_ARG(u);
  	LWIP_UNUSED_ARG(proto);
  	LWIP_UNUSED_ARG(mode);
  	return 0;
  }
  
  /*
   * sifdown - Config the interface down and disable IP.
   */
  int sifdown(int pd)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 1;
  
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag) {
  		st = 0;
  		PPPDEBUG(LOG_WARNING, ("sifdown[%d]: bad parms\n", pd));
  	} else {
  		pc->if_up = 0;
  		/* make sure the netif status callback is called */
  		netif_set_down(&pc->netif);
  		netif_remove(&pc->netif);
  		PPPDEBUG(LOG_DEBUG, ("sifdown: unit %d: linkStatusCB=%p errCode=%d\n", pd, pc->linkStatusCB, pc->errCode));
  		if (pc->linkStatusCB) {
  			pc->linkStatusCB(pc->linkStatusCtx, PPPERR_CONNECT, NULL);
  		}
  	}
  	return st;
  }
  
  /**
   * sifaddr - Config the interface IP addresses and netmask.
   * @param pd Interface unit ???
   * @param o Our IP address ???
   * @param h His IP address ???
   * @param m IP subnet mask ???
   * @param ns1 Primary DNS
   * @param ns2 Secondary DNS
   */
  int sifaddr(int pd, u32_t o, u32_t h, u32_t m, u32_t ns1, u32_t ns2)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 1;
  
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag) {
  		st = 0;
  		PPPDEBUG(LOG_WARNING, ("sifup[%d]: bad parms\n", pd));
  	} else {
  		SMEMCPY(&pc->addrs.our_ipaddr, &o, sizeof(o));
  		SMEMCPY(&pc->addrs.his_ipaddr, &h, sizeof(h));
  		SMEMCPY(&pc->addrs.netmask, &m, sizeof(m));
  		SMEMCPY(&pc->addrs.dns1, &ns1, sizeof(ns1));
  		SMEMCPY(&pc->addrs.dns2, &ns2, sizeof(ns2));
  	}
  	return st;
  }
  
  /**
   * cifaddr - Clear the interface IP addresses, and delete routes
   * through the interface if possible.
   * @param pd Interface unit ???
   * @param o Our IP address ???
   * @param h IP broadcast address ???
   */
  int cifaddr(int pd, u32_t o, u32_t h)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 1;
  
  	LWIP_UNUSED_ARG(o);
  	LWIP_UNUSED_ARG(h);
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag) {
  		st = 0;
  		PPPDEBUG(LOG_WARNING, ("sifup[%d]: bad parms\n", pd));
  	} else {
  		IP4_ADDR(&pc->addrs.our_ipaddr, 0, 0, 0, 0);
  		IP4_ADDR(&pc->addrs.his_ipaddr, 0, 0, 0, 0);
  		IP4_ADDR(&pc->addrs.netmask, 255, 255, 255, 0);
  		IP4_ADDR(&pc->addrs.dns1, 0, 0, 0, 0);
  		IP4_ADDR(&pc->addrs.dns2, 0, 0, 0, 0);
  	}
  	return st;
  }
  
  /*
   * sifdefaultroute - assign a default route through the address given.
   */
  int sifdefaultroute(int pd, u32_t l, u32_t g)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 1;
  
  	LWIP_UNUSED_ARG(l);
  	LWIP_UNUSED_ARG(g);
  
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag) {
  		st = 0;
  		PPPDEBUG(LOG_WARNING, ("sifup[%d]: bad parms\n", pd));
  	} else {
  		netif_set_default(&pc->netif);
  	}
  
  	/* TODO: check how PPP handled the netMask, previously not set by ipSetDefault */
  
  	return st;
  }
  
  /*
   * cifdefaultroute - delete a default route through the address given.
   */
  int cifdefaultroute(int pd, u32_t l, u32_t g)
  {
  	PPPControl *pc = &pppControl[pd];
  	int st = 1;
  
  	LWIP_UNUSED_ARG(l);
  	LWIP_UNUSED_ARG(g);
  
  	if (pd < 0 || pd >= NUM_PPP || !pc->openFlag) {
  		st = 0;
  		PPPDEBUG(LOG_WARNING, ("sifup[%d]: bad parms\n", pd));
  	} else {
  		netif_set_default(NULL);
  	}
  
  	return st;
  }
  
  /**********************************/
  /*** LOCAL FUNCTION DEFINITIONS ***/
  /**********************************/
  
  #if PPPOS_SUPPORT && PPP_INPROC_OWNTHREAD
  /* The main PPP process function.  This implements the state machine according
   * to section 4 of RFC 1661: The Point-To-Point Protocol. */
  static void pppInputThread(void *arg)
  {
  	int count;
  	PPPControlRx *pcrx = arg;
  
  	while (lcp_phase[pcrx->pd] != PHASE_DEAD) {
  		count = sio_read(pcrx->fd, pcrx->rxbuf, PPPOS_RX_BUFSIZE);
  		if (count > 0) {
  			pppInProc(pcrx, pcrx->rxbuf, count);
  		} else {
  			/* nothing received, give other tasks a chance to run */
  			sys_msleep(1);
  		}
  	}
  }
  #endif							/* PPPOS_SUPPORT && PPP_INPROC_OWNTHREAD */
  
  #if PPPOE_SUPPORT
  
  void pppOverEthernetInitFailed(int pd)
  {
  	PPPControl *pc;
  
  	pppHup(pd);
  	pppStop(pd);
  
  	pc = &pppControl[pd];
  	pppoe_destroy(&pc->netif);
  	pc->openFlag = 0;
  
  	if (pc->linkStatusCB) {
  		pc->linkStatusCB(pc->linkStatusCtx, pc->errCode ? pc->errCode : PPPERR_PROTOCOL, NULL);
  	}
  }
  
  static void pppOverEthernetLinkStatusCB(int pd, int up)
  {
  	if (up) {
  		PPPDEBUG(LOG_INFO, ("pppOverEthernetLinkStatusCB: unit %d: Connecting\n", pd));
  		pppStart(pd);
  	} else {
  		pppOverEthernetInitFailed(pd);
  	}
  }
  #endif							/* PPPOE_SUPPORT */
  
  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;
  
  	if (pbuf_header(nb, -(int)sizeof(struct pppInputHeader))) {
  		LWIP_ASSERT("pbuf_header failed\n", 0);
  		goto drop;
  	}
  
  	LINK_STATS_INC(link.recv);
  	snmp_inc_ifinucastpkts(&pppControl[pd].netif);
  	snmp_add_ifinoctets(&pppControl[pd].netif, nb->tot_len);
  
  	/*
  	 * 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%" X16_F " in phase %d\n", protocol, lcp_phase[pd]));
  			goto drop;
  		}
  	}
  
  	switch (protocol) {
  	case PPP_VJC_COMP:			/* VJ compressed TCP */
  #if PPPOS_SUPPORT && VJ_SUPPORT
  		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)) {
  			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							/* PPPOS_SUPPORT && VJ_SUPPORT */
  		/* 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							/* PPPOS_SUPPORT && VJ_SUPPORT */
  		break;
  
  	case PPP_VJC_UNCOMP:		/* VJ uncompressed TCP */
  #if PPPOS_SUPPORT && VJ_SUPPORT
  		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) {
  			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							/* PPPOS_SUPPORT && VJ_SUPPORT */
  		/* 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							/* PPPOS_SUPPORT && VJ_SUPPORT */
  		break;
  
  	case PPP_IP:				/* Internet Protocol */
  		PPPDEBUG(LOG_INFO, ("pppInput[%d]: ip in pbuf len=%d\n", pd, nb->len));
  		if (pppControl[pd].netif.input) {
  			pppControl[pd].netif.input(nb, &pppControl[pd].netif);
  			return;
  		}
  		break;
  
  	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);
  				PPPDEBUG(LOG_DETAIL, ("pppInput[%d]: packet processed\n", pd));
  				goto out;
  			}
  		}
  
  		/* No handler for this protocol so reject the packet. */
  		PPPDEBUG(LOG_INFO, ("pppInput[%d]: rejecting unsupported proto 0x%" X16_F " len=%d\n", pd, protocol, nb->len));
  		if (pbuf_header(nb, sizeof(protocol))) {
  			LWIP_ASSERT("pbuf_header failed\n", 0);
  			goto drop;
  		}
  #if BYTE_ORDER == LITTLE_ENDIAN
  		protocol = htons(protocol);
  #endif							/* BYTE_ORDER == LITTLE_ENDIAN */
  		SMEMCPY(nb->payload, &protocol, sizeof(protocol));
  		lcp_sprotrej(pd, nb->payload, nb->len);
  	}
  	break;
  	}
  
  drop:
  	LINK_STATS_INC(link.drop);
  	snmp_inc_ifindiscards(&pppControl[pd].netif);
  
  out:
  	pbuf_free(nb);
  	return;
  }
  
  #if PPPOS_SUPPORT
  /*
   * Drop the input packet.
   */
  static void pppFreeCurrentInputPacket(PPPControlRx *pcrx)
  {
  	if (pcrx->inHead != NULL) {
  		if (pcrx->inTail && (pcrx->inTail != pcrx->inHead)) {
  			pbuf_free(pcrx->inTail);
  		}
  		pbuf_free(pcrx->inHead);
  		pcrx->inHead = NULL;
  	}
  	pcrx->inTail = NULL;
  }
  
  /*
   * Drop the input packet and increase error counters.
   */
  static void pppDrop(PPPControlRx *pcrx)
  {
  	if (pcrx->inHead != NULL) {
  #if 0
  		PPPDEBUG(LOG_INFO, ("pppDrop: %d:%.*H\n", pcrx->inHead->len, min(60, pcrx->inHead->len * 2), pcrx->inHead->payload));
  #endif
  		PPPDEBUG(LOG_INFO, ("pppDrop: pbuf len=%d, addr %p\n", pcrx->inHead->len, (void *)pcrx->inHead));
  	}
  	pppFreeCurrentInputPacket(pcrx);
  #if VJ_SUPPORT
  	vj_uncompress_err(&pppControl[pcrx->pd].vjComp);
  #endif							/* VJ_SUPPORT */
  
  	LINK_STATS_INC(link.drop);
  	snmp_inc_ifindiscards(&pppControl[pcrx->pd].netif);
  }
  
  #if !PPP_INPROC_OWNTHREAD
  /** Pass received raw characters to PPPoS to be decoded. This function is
   * thread-safe and can be called from a dedicated RX-thread or from a main-loop.
   *
   * @param pd PPP descriptor index, returned by pppOpen()
   * @param data received data
   * @param len length of received data
   */
  void pppos_input(int pd, u_char *data, int len)
  {
  	pppInProc(&pppControl[pd].rx, data, len);
  }
  #endif
  
  /**
   * Process a received octet string.
   */
  static void pppInProc(PPPControlRx *pcrx, u_char *s, int l)
  {
  	struct pbuf *nextNBuf;
  	u_char curChar;
  	u_char escaped;
  	SYS_ARCH_DECL_PROTECT(lev);
  
  	PPPDEBUG(LOG_DEBUG, ("pppInProc[%d]: got %d bytes\n", pcrx->pd, l));
  	while (l-- > 0) {
  		curChar = *s++;
  
  		SYS_ARCH_PROTECT(lev);
  		escaped = ESCAPE_P(pcrx->inACCM, curChar);
  		SYS_ARCH_UNPROTECT(lev);
  		/* Handle special characters. */
  		if (escaped) {
  			/* 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) {
  				pcrx->inEscaped = 1;
  				/* Check for the flag character. */
  			} else if (curChar == PPP_FLAG) {
  				/* If this is just an extra flag character, ignore it. */
  				if (pcrx->inState <= PDADDRESS) {
  					/* ignore it */ ;
  					/* If we haven't received the packet header, drop what has come in. */
  				} else if (pcrx->inState < PDDATA) {
  					PPPDEBUG(LOG_WARNING, ("pppInProc[%d]: Dropping incomplete packet %d\n", pcrx->pd, pcrx->inState));
  					LINK_STATS_INC(link.lenerr);
  					pppDrop(pcrx);
  					/* If the fcs is invalid, drop the packet. */
  				} else if (pcrx->inFCS != PPP_GOODFCS) {
  					PPPDEBUG(LOG_INFO, ("pppInProc[%d]: Dropping bad fcs 0x%" X16_F " proto=0x%" X16_F "\n", pcrx->pd, pcrx->inFCS, pcrx->inProtocol));
  					/* Note: If you get lots of these, check for UART frame errors or try different baud rate */
  					LINK_STATS_INC(link.chkerr);
  					pppDrop(pcrx);
  					/* Otherwise it's a good packet so pass it on. */
  				} else {
  					struct pbuf *inp;
  					/* Trim off the checksum. */
  					if (pcrx->inTail->len >= 2) {
  						pcrx->inTail->len -= 2;
  
  						pcrx->inTail->tot_len = pcrx->inTail->len;
  						if (pcrx->inTail != pcrx->inHead) {
  							pbuf_cat(pcrx->inHead, pcrx->inTail);
  						}
  					} else {
  						pcrx->inTail->tot_len = pcrx->inTail->len;
  						if (pcrx->inTail != pcrx->inHead) {
  							pbuf_cat(pcrx->inHead, pcrx->inTail);
  						}
  
  						pbuf_realloc(pcrx->inHead, pcrx->inHead->tot_len - 2);
  					}
  
  					/* Dispatch the packet thereby consuming it. */
  					inp = pcrx->inHead;
  					/* Packet consumed, release our references. */
  					pcrx->inHead = NULL;
  					pcrx->inTail = NULL;
  #if PPP_INPROC_MULTITHREADED
  					if (tcpip_callback_with_block(pppInput, inp, 0) != ERR_OK) {
  						PPPDEBUG(LOG_ERR, ("pppInProc[%d]: tcpip_callback() failed, dropping packet\n", pcrx->pd));
  						pbuf_free(inp);
  						LINK_STATS_INC(link.drop);
  						snmp_inc_ifindiscards(&pppControl[pcrx->pd].netif);
  					}
  #else							/* PPP_INPROC_MULTITHREADED */
  					pppInput(inp);
  #endif							/* PPP_INPROC_MULTITHREADED */
  				}
  
  				/* Prepare for a new packet. */
  				pcrx->inFCS = PPP_INITFCS;
  				pcrx->inState = PDADDRESS;
  				pcrx->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", pcrx->pd, curChar));
  			}
  			/* Process other characters. */
  		} else {
  			/* Unencode escaped characters. */
  			if (pcrx->inEscaped) {
  				pcrx->inEscaped = 0;
  				curChar ^= PPP_TRANS;
  			}
  
  			/* Process character relative to current state. */
  			switch (pcrx->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. */
  				pcrx->inFCS = PPP_INITFCS;
  
  				/* Fall through */
  			case PDADDRESS:	/* Process address field. */
  				if (curChar == PPP_ALLSTATIONS) {
  					pcrx->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) {
  					pcrx->inState = PDPROTOCOL1;
  					break;
  				}
  #if 0
  				else {
  					PPPDEBUG(LOG_WARNING, ("pppInProc[%d]: Invalid control <%d>\n", pcrx->pd, curChar));
  					pcrx->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) {
  					pcrx->inProtocol = curChar;
  					pcrx->inState = PDDATA;
  				} else {
  					pcrx->inProtocol = (u_int) curChar << 8;
  					pcrx->inState = PDPROTOCOL2;
  				}
  				break;
  			case PDPROTOCOL2:	/* Process protocol field 2. */
  				pcrx->inProtocol |= curChar;
  				pcrx->inState = PDDATA;
  				break;
  			case PDDATA:		/* Process data byte. */
  				/* Make space to receive processed data. */
  				if (pcrx->inTail == NULL || pcrx->inTail->len == PBUF_POOL_BUFSIZE) {
  					if (pcrx->inTail != NULL) {
  						pcrx->inTail->tot_len = pcrx->inTail->len;
  						if (pcrx->inTail != pcrx->inHead) {
  							pbuf_cat(pcrx->inHead, pcrx->inTail);
  							/* give up the inTail reference now */
  							pcrx->inTail = NULL;
  						}
  					}
  					/* 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", pcrx->pd));
  						LINK_STATS_INC(link.memerr);
  						pppDrop(pcrx);
  						pcrx->inState = PDSTART;	/* Wait for flag sequence. */
  						break;
  					}
  					if (pcrx->inHead == NULL) {
  						struct pppInputHeader *pih = nextNBuf->payload;
  
  						pih->unit = pcrx->pd;
  						pih->proto = pcrx->inProtocol;
  
  						nextNBuf->len += sizeof(*pih);
  
  						pcrx->inHead = nextNBuf;
  					}
  					pcrx->inTail = nextNBuf;
  				}
  				/* Load character into buffer. */
  				((u_char *)pcrx->inTail->payload)[pcrx->inTail->len++] = curChar;
  				break;
  			}
  
  			/* update the frame check sequence number. */
  			pcrx->inFCS = PPP_FCS(pcrx->inFCS, curChar);
  		}
  	}							/* while (l-- > 0), all bytes processed */
  
  	avRandomize();
  }
  #endif							/* PPPOS_SUPPORT */
  
  #if PPPOE_SUPPORT
  void pppInProcOverEthernet(int pd, struct pbuf *pb)
  {
  	struct pppInputHeader *pih;
  	u16_t inProtocol;
  
  	if (pb->len < sizeof(inProtocol)) {
  		PPPDEBUG(LOG_ERR, ("pppInProcOverEthernet: too small for protocol field\n"));
  		goto drop;
  	}
  
  	inProtocol = (((u8_t *)pb->payload)[0] << 8) | ((u8_t *)pb->payload)[1];
  
  	/* make room for pppInputHeader - should not fail */
  	if (pbuf_header(pb, sizeof(*pih) - sizeof(inProtocol)) != 0) {
  		PPPDEBUG(LOG_ERR, ("pppInProcOverEthernet: could not allocate room for header\n"));
  		goto drop;
  	}
  
  	pih = pb->payload;
  
  	pih->unit = pd;
  	pih->proto = inProtocol;
  
  	/* Dispatch the packet thereby consuming it. */
  	pppInput(pb);
  	return;
  
  drop:
  	LINK_STATS_INC(link.drop);
  	snmp_inc_ifindiscards(&pppControl[pd].netif);
  	pbuf_free(pb);
  	return;
  }
  #endif							/* PPPOE_SUPPORT */
  
  #if LWIP_NETIF_STATUS_CALLBACK
  /** Set the status callback of a PPP's netif
   *
   * @param pd The PPP descriptor returned by pppOpen()
   * @param status_callback pointer to the status callback function
   *
   * @see netif_set_status_callback
   */
  void ppp_set_netif_statuscallback(int pd, netif_status_callback_fn status_callback)
  {
  	netif_set_status_callback(&pppControl[pd].netif, status_callback);
  }
  #endif							/* LWIP_NETIF_STATUS_CALLBACK */
  
  #if LWIP_NETIF_LINK_CALLBACK
  /** Set the link callback of a PPP's netif
   *
   * @param pd The PPP descriptor returned by pppOpen()
   * @param link_callback pointer to the link callback function
   *
   * @see netif_set_link_callback
   */
  void ppp_set_netif_linkcallback(int pd, netif_status_callback_fn link_callback)
  {
  	netif_set_link_callback(&pppControl[pd].netif, link_callback);
  }
  #endif							/* LWIP_NETIF_LINK_CALLBACK */
  
  #endif							/* PPP_SUPPORT */
  