1. Reduce the size of the heap memory 2. Change the TCP segment size 3. Disable UDP + DHCP + DNS 4. Change the configuration of the TCP/IP thread

Dependents:   EthernetInterface

Fork of lwip by mbed official

Revision:
0:51ac1d130fd4
Child:
4:f71f5d9d5846
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/netif/ppp/lcp.c	Fri Jun 22 09:25:39 2012 +0000
@@ -0,0 +1,2066 @@
+/*****************************************************************************
+* lcp.c - Network Link Control 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.
+* 97-12-01 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
+*   Original.
+*****************************************************************************/
+
+/*
+ * lcp.c - PPP Link Control Protocol.
+ *
+ * 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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+ 
+
+#include "lwip/opt.h"
+
+#if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
+
+#include "ppp.h"
+#include "pppdebug.h"
+
+#include "fsm.h"
+#include "chap.h"
+#include "magic.h"
+#include "auth.h"
+#include "lcp.h"
+
+#include <string.h>
+
+#if PPPOE_SUPPORT
+#include "netif/ppp_oe.h"
+#else
+#define PPPOE_MAXMTU PPP_MAXMRU
+#endif
+
+#if 0 /* UNUSED */
+/*
+ * LCP-related command-line options.
+ */
+int lcp_echo_interval = 0;  /* Interval between LCP echo-requests */
+int lcp_echo_fails = 0;     /* Tolerance to unanswered echo-requests */
+bool  lax_recv = 0;         /* accept control chars in asyncmap */
+
+static int setescape (char **);
+
+static option_t lcp_option_list[] = {
+    /* LCP options */
+    /* list stripped for simplicity */
+    {NULL}
+};
+#endif /* UNUSED */
+
+/* options */
+LinkPhase lcp_phase[NUM_PPP];          /* Phase of link session (RFC 1661) */
+static u_int lcp_echo_interval      = LCP_ECHOINTERVAL; /* Interval between LCP echo-requests */
+static u_int lcp_echo_fails         = LCP_MAXECHOFAILS; /* Tolerance to unanswered echo-requests */
+
+/* global vars */
+static fsm lcp_fsm[NUM_PPP];                            /* LCP fsm structure (global)*/
+lcp_options lcp_wantoptions[NUM_PPP];  /* Options that we want to request */
+lcp_options lcp_gotoptions[NUM_PPP];   /* Options that peer ack'd */
+lcp_options lcp_allowoptions[NUM_PPP]; /* Options we allow peer to request */
+lcp_options lcp_hisoptions[NUM_PPP];   /* Options that we ack'd */
+ext_accm xmit_accm[NUM_PPP];           /* extended transmit ACCM */
+
+static u32_t lcp_echos_pending      = 0;                /* Number of outstanding echo msgs */
+static u32_t lcp_echo_number        = 0;                /* ID number of next echo frame */
+static u32_t lcp_echo_timer_running = 0;                /* TRUE if a timer is running */
+
+/* @todo: do we really need such a large buffer? The typical 1500 bytes seem too much. */
+static u_char nak_buffer[PPP_MRU]; /* where we construct a nak packet */ 
+
+/*
+ * Callbacks for fsm code.  (CI = Configuration Information)
+ */
+static void lcp_resetci (fsm*);                   /* Reset our CI */
+static int  lcp_cilen (fsm*);                     /* Return length of our CI */
+static void lcp_addci (fsm*, u_char*, int*);      /* Add our CI to pkt */
+static int  lcp_ackci (fsm*, u_char*, int);       /* Peer ack'd our CI */
+static int  lcp_nakci (fsm*, u_char*, int);       /* Peer nak'd our CI */
+static int  lcp_rejci (fsm*, u_char*, int);       /* Peer rej'd our CI */
+static int  lcp_reqci (fsm*, u_char*, int*, int); /* Rcv peer CI */
+static void lcp_up (fsm*);                        /* We're UP */
+static void lcp_down (fsm*);                      /* We're DOWN */
+static void lcp_starting (fsm*);                  /* We need lower layer up */
+static void lcp_finished (fsm*);                  /* We need lower layer down */
+static int  lcp_extcode (fsm*, int, u_char, u_char*, int);
+static void lcp_rprotrej (fsm*, u_char*, int);
+
+/*
+ * routines to send LCP echos to peer
+ */
+
+static void lcp_echo_lowerup (int);
+static void lcp_echo_lowerdown (int);
+static void LcpEchoTimeout (void*);
+static void lcp_received_echo_reply (fsm*, int, u_char*, int);
+static void LcpSendEchoRequest (fsm*);
+static void LcpLinkFailure (fsm*);
+static void LcpEchoCheck (fsm*);
+
+static fsm_callbacks lcp_callbacks = { /* LCP callback routines */
+  lcp_resetci,  /* Reset our Configuration Information */
+  lcp_cilen,    /* Length of our Configuration Information */
+  lcp_addci,    /* Add our Configuration Information */
+  lcp_ackci,    /* ACK our Configuration Information */
+  lcp_nakci,    /* NAK our Configuration Information */
+  lcp_rejci,    /* Reject our Configuration Information */
+  lcp_reqci,    /* Request peer's Configuration Information */
+  lcp_up,       /* Called when fsm reaches LS_OPENED state */
+  lcp_down,     /* Called when fsm leaves LS_OPENED state */
+  lcp_starting, /* Called when we want the lower layer up */
+  lcp_finished, /* Called when we want the lower layer down */
+  NULL,         /* Called when Protocol-Reject received */
+  NULL,         /* Retransmission is necessary */
+  lcp_extcode,  /* Called to handle LCP-specific codes */
+  "LCP"         /* String name of protocol */
+};
+
+/*
+ * Protocol entry points.
+ * Some of these are called directly.
+ */
+
+static void lcp_input (int, u_char *, int);
+static void lcp_protrej (int);
+
+struct protent lcp_protent = {
+    PPP_LCP,
+    lcp_init,
+    lcp_input,
+    lcp_protrej,
+    lcp_lowerup,
+    lcp_lowerdown,
+    lcp_open,
+    lcp_close,
+#if PPP_ADDITIONAL_CALLBACKS
+    lcp_printpkt,
+    NULL,
+#endif /* PPP_ADDITIONAL_CALLBACKS */
+    1,
+    "LCP",
+#if PPP_ADDITIONAL_CALLBACKS
+    NULL,
+    NULL,
+    NULL
+#endif /* PPP_ADDITIONAL_CALLBACKS */
+};
+
+int lcp_loopbackfail = DEFLOOPBACKFAIL;
+
+/*
+ * Length of each type of configuration option (in octets)
+ */
+#define CILEN_VOID  2
+#define CILEN_CHAR  3
+#define CILEN_SHORT 4 /* CILEN_VOID + sizeof(short) */
+#define CILEN_CHAP  5 /* CILEN_VOID + sizeof(short) + 1 */
+#define CILEN_LONG  6 /* CILEN_VOID + sizeof(long) */
+#define CILEN_LQR   8 /* CILEN_VOID + sizeof(short) + sizeof(long) */
+#define CILEN_CBCP  3
+
+#define CODENAME(x)  ((x) == CONFACK ? "ACK" : (x) == CONFNAK ? "NAK" : "REJ")
+
+#if 0 /* UNUSED */
+/*
+ * setescape - add chars to the set we escape on transmission.
+ */
+static int
+setescape(argv)
+    char **argv;
+{
+    int n, ret;
+    char *p, *endp;
+
+    p = *argv;
+    ret = 1;
+    while (*p) {
+      n = strtol(p, &endp, 16);
+      if (p == endp) {
+        option_error("escape parameter contains invalid hex number '%s'", p);
+        return 0;
+      }
+      p = endp;
+      if (n < 0 || n == 0x5E || n > 0xFF) {
+        option_error("can't escape character 0x%x", n);
+        ret = 0;
+      } else
+        xmit_accm[0][n >> 5] |= 1 << (n & 0x1F);
+      while (*p == ',' || *p == ' ')
+        ++p;
+    }
+    return ret;
+}
+#endif /* UNUSED */
+
+/*
+ * lcp_init - Initialize LCP.
+ */
+void
+lcp_init(int unit)
+{
+  fsm         *f  = &lcp_fsm[unit];
+  lcp_options *wo = &lcp_wantoptions[unit];
+  lcp_options *ao = &lcp_allowoptions[unit];
+
+  f->unit      = unit;
+  f->protocol  = PPP_LCP;
+  f->callbacks = &lcp_callbacks;
+
+  fsm_init(f);
+
+  wo->passive           = 0;
+  wo->silent            = 0;
+  wo->restart           = 0;               /* Set to 1 in kernels or multi-line implementations */
+  wo->neg_mru           = 1;
+  wo->mru               = PPP_DEFMRU;
+  wo->neg_asyncmap      = 1;
+  wo->asyncmap          = 0x00000000l;     /* Assume don't need to escape any ctl chars. */
+  wo->neg_chap          = 0;               /* Set to 1 on server */
+  wo->neg_upap          = 0;               /* Set to 1 on server */
+  wo->chap_mdtype       = CHAP_DIGEST_MD5;
+  wo->neg_magicnumber   = 1;
+  wo->neg_pcompression  = 1;
+  wo->neg_accompression = 1;
+  wo->neg_lqr           = 0;               /* no LQR implementation yet */
+  wo->neg_cbcp          = 0;
+
+  ao->neg_mru           = 1;
+  ao->mru               = PPP_MAXMRU;
+  ao->neg_asyncmap      = 1;
+  ao->asyncmap          = 0x00000000l;     /* Assume don't need to escape any ctl chars. */
+  ao->neg_chap          = (CHAP_SUPPORT != 0);
+  ao->chap_mdtype       = CHAP_DIGEST_MD5;
+  ao->neg_upap          = (PAP_SUPPORT != 0);
+  ao->neg_magicnumber   = 1;
+  ao->neg_pcompression  = 1;
+  ao->neg_accompression = 1;
+  ao->neg_lqr           = 0;               /* no LQR implementation yet */
+  ao->neg_cbcp          = (CBCP_SUPPORT != 0);
+
+  /* 
+   * Set transmit escape for the flag and escape characters plus anything
+   * set for the allowable options.
+   */
+  memset(xmit_accm[unit], 0, sizeof(xmit_accm[0]));
+  xmit_accm[unit][15] = 0x60;
+  xmit_accm[unit][0]  = (u_char)((ao->asyncmap        & 0xFF));
+  xmit_accm[unit][1]  = (u_char)((ao->asyncmap >> 8)  & 0xFF);
+  xmit_accm[unit][2]  = (u_char)((ao->asyncmap >> 16) & 0xFF);
+  xmit_accm[unit][3]  = (u_char)((ao->asyncmap >> 24) & 0xFF);
+  LCPDEBUG(LOG_INFO, ("lcp_init: xmit_accm=%X %X %X %X\n",
+        xmit_accm[unit][0],
+        xmit_accm[unit][1],
+        xmit_accm[unit][2],
+        xmit_accm[unit][3]));
+  
+  lcp_phase[unit] = PHASE_INITIALIZE;
+}
+
+
+/*
+ * lcp_open - LCP is allowed to come up.
+ */
+void
+lcp_open(int unit)
+{
+  fsm         *f  = &lcp_fsm[unit];
+  lcp_options *wo = &lcp_wantoptions[unit];
+
+  f->flags = 0;
+  if (wo->passive) {
+    f->flags |= OPT_PASSIVE;
+  }
+  if (wo->silent) {
+    f->flags |= OPT_SILENT;
+  }
+  fsm_open(f);
+
+  lcp_phase[unit] = PHASE_ESTABLISH;
+}
+
+
+/*
+ * lcp_close - Take LCP down.
+ */
+void
+lcp_close(int unit, char *reason)
+{
+  fsm *f = &lcp_fsm[unit];
+
+  if (lcp_phase[unit] != PHASE_DEAD) {
+    lcp_phase[unit] = PHASE_TERMINATE;
+  }
+  if (f->state == LS_STOPPED && f->flags & (OPT_PASSIVE|OPT_SILENT)) {
+    /*
+     * This action is not strictly according to the FSM in RFC1548,
+     * but it does mean that the program terminates if you do an
+     * lcp_close() in passive/silent mode when a connection hasn't
+     * been established.
+     */
+    f->state = LS_CLOSED;
+    lcp_finished(f);
+  } else {
+    fsm_close(f, reason);
+  }
+}
+
+
+/*
+ * lcp_lowerup - The lower layer is up.
+ */
+void
+lcp_lowerup(int unit)
+{
+  lcp_options *wo = &lcp_wantoptions[unit];
+
+  /*
+   * Don't use A/C or protocol compression on transmission,
+   * but accept A/C and protocol compressed packets
+   * if we are going to ask for A/C and protocol compression.
+   */
+  ppp_set_xaccm(unit, &xmit_accm[unit]);
+  ppp_send_config(unit, PPP_MRU, 0xffffffffl, 0, 0);
+  ppp_recv_config(unit, PPP_MRU, 0x00000000l,
+  wo->neg_pcompression, wo->neg_accompression);
+  peer_mru[unit] = PPP_MRU;
+  lcp_allowoptions[unit].asyncmap = (u_long)xmit_accm[unit][0]
+                                 | ((u_long)xmit_accm[unit][1] << 8)
+                                 | ((u_long)xmit_accm[unit][2] << 16)
+                                 | ((u_long)xmit_accm[unit][3] << 24);
+  LCPDEBUG(LOG_INFO, ("lcp_lowerup: asyncmap=%X %X %X %X\n",
+            xmit_accm[unit][3],
+            xmit_accm[unit][2],
+            xmit_accm[unit][1],
+            xmit_accm[unit][0]));
+
+  fsm_lowerup(&lcp_fsm[unit]);
+}
+
+
+/*
+ * lcp_lowerdown - The lower layer is down.
+ */
+void
+lcp_lowerdown(int unit)
+{
+  fsm_lowerdown(&lcp_fsm[unit]);
+}
+
+
+/*
+ * lcp_input - Input LCP packet.
+ */
+static void
+lcp_input(int unit, u_char *p, int len)
+{
+  fsm *f = &lcp_fsm[unit];
+
+  fsm_input(f, p, len);
+}
+
+
+/*
+ * lcp_extcode - Handle a LCP-specific code.
+ */
+static int
+lcp_extcode(fsm *f, int code, u_char id, u_char *inp, int len)
+{
+  u_char *magp;
+
+  switch( code ){
+    case PROTREJ:
+      lcp_rprotrej(f, inp, len);
+      break;
+  
+    case ECHOREQ:
+      if (f->state != LS_OPENED) {
+        break;
+      }
+      LCPDEBUG(LOG_INFO, ("lcp: Echo-Request, Rcvd id %d\n", id));
+      magp = inp;
+      PUTLONG(lcp_gotoptions[f->unit].magicnumber, magp);
+      fsm_sdata(f, ECHOREP, id, inp, len);
+      break;
+
+    case ECHOREP:
+      lcp_received_echo_reply(f, id, inp, len);
+      break;
+
+    case DISCREQ:
+      break;
+
+    default:
+      return 0;
+  }
+  return 1;
+}
+
+
+/*
+ * lcp_rprotrej - Receive an Protocol-Reject.
+ *
+ * Figure out which protocol is rejected and inform it.
+ */
+static void
+lcp_rprotrej(fsm *f, u_char *inp, int len)
+{
+  int i;
+  struct protent *protp;
+  u_short prot;
+
+  if (len < (int)sizeof (u_short)) {
+    LCPDEBUG(LOG_INFO, ("lcp_rprotrej: Rcvd short Protocol-Reject packet!\n"));
+    return;
+  }
+
+  GETSHORT(prot, inp);
+
+  LCPDEBUG(LOG_INFO, ("lcp_rprotrej: Rcvd Protocol-Reject packet for %x!\n", prot));
+
+  /*
+   * Protocol-Reject packets received in any state other than the LCP
+   * LS_OPENED state SHOULD be silently discarded.
+   */
+  if( f->state != LS_OPENED ) {
+    LCPDEBUG(LOG_INFO, ("Protocol-Reject discarded: LCP in state %d\n", f->state));
+    return;
+  }
+
+  /*
+   * Upcall the proper Protocol-Reject routine.
+   */
+  for (i = 0; (protp = ppp_protocols[i]) != NULL; ++i) {
+    if (protp->protocol == prot && protp->enabled_flag) {
+      (*protp->protrej)(f->unit);
+      return;
+    }
+  }
+
+  LCPDEBUG(LOG_WARNING, ("Protocol-Reject for unsupported protocol 0x%x\n", prot));
+}
+
+
+/*
+ * lcp_protrej - A Protocol-Reject was received.
+ */
+static void
+lcp_protrej(int unit)
+{
+  LWIP_UNUSED_ARG(unit);
+  /*
+   * Can't reject LCP!
+   */
+  LCPDEBUG(LOG_WARNING, ("lcp_protrej: Received Protocol-Reject for LCP!\n"));
+  fsm_protreject(&lcp_fsm[unit]);
+}
+
+
+/*
+ * lcp_sprotrej - Send a Protocol-Reject for some protocol.
+ */
+void
+lcp_sprotrej(int unit, u_char *p, int len)
+{
+  /*
+   * Send back the protocol and the information field of the
+   * rejected packet.  We only get here if LCP is in the LS_OPENED state.
+   */
+
+  fsm_sdata(&lcp_fsm[unit], PROTREJ, ++lcp_fsm[unit].id, p, len);
+}
+
+
+/*
+ * lcp_resetci - Reset our CI.
+ */
+static void
+lcp_resetci(fsm *f)
+{
+  lcp_wantoptions[f->unit].magicnumber = magic();
+  lcp_wantoptions[f->unit].numloops = 0;
+  lcp_gotoptions[f->unit] = lcp_wantoptions[f->unit];
+  peer_mru[f->unit] = PPP_MRU;
+  auth_reset(f->unit);
+}
+
+
+/*
+ * lcp_cilen - Return length of our CI.
+ */
+static int
+lcp_cilen(fsm *f)
+{
+  lcp_options *go = &lcp_gotoptions[f->unit];
+
+#define LENCIVOID(neg)  ((neg) ? CILEN_VOID : 0)
+#define LENCICHAP(neg)  ((neg) ? CILEN_CHAP : 0)
+#define LENCISHORT(neg) ((neg) ? CILEN_SHORT : 0)
+#define LENCILONG(neg)  ((neg) ? CILEN_LONG : 0)
+#define LENCILQR(neg)   ((neg) ? CILEN_LQR: 0)
+#define LENCICBCP(neg)  ((neg) ? CILEN_CBCP: 0)
+  /*
+   * NB: we only ask for one of CHAP and UPAP, even if we will
+   * accept either.
+   */
+  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 LS_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 != LS_OPENED) {
+    if (looped_back) {
+      if (++try.numloops >= lcp_loopbackfail) {
+        LCPDEBUG(LOG_NOTICE, ("Serial line is looped back.\n"));
+        lcp_close(f->unit, "Loopback detected");
+      }
+    } else {
+      try.numloops = 0;
+    }
+    *go = try;
+  }
+
+  return 1;
+
+bad:
+  LCPDEBUG(LOG_WARNING, ("lcp_nakci: received bad Nak!\n"));
+  return 0;
+}
+
+
+/*
+ * lcp_rejci - Peer has Rejected some of our CIs.
+ * This should not modify any state if the Reject is bad
+ * or if LCP is in the LS_OPENED state.
+ *
+ * Returns:
+ *  0 - Reject was bad.
+ *  1 - Reject was good.
+ */
+static int
+lcp_rejci(fsm *f, u_char *p, int len)
+{
+  lcp_options *go = &lcp_gotoptions[f->unit];
+  u_char cichar;
+  u_short cishort;
+  u32_t cilong;
+  lcp_options try; /* options to request next time */
+
+  try = *go;
+
+  /*
+   * Any Rejected CIs must be in exactly the same order that we sent.
+   * Check packet length and CI length at each step.
+   * If we find any deviations, then this packet is bad.
+   */
+#define REJCIVOID(opt, neg) \
+  if (go->neg && \
+      len >= CILEN_VOID && \
+      p[1] == CILEN_VOID && \
+      p[0] == opt) { \
+    len -= CILEN_VOID; \
+    INCPTR(CILEN_VOID, p); \
+    try.neg = 0; \
+    LCPDEBUG(LOG_INFO, ("lcp_rejci: void opt %d rejected\n", opt)); \
+  }
+#define REJCISHORT(opt, neg, val) \
+  if (go->neg && \
+      len >= CILEN_SHORT && \
+      p[1] == CILEN_SHORT && \
+      p[0] == opt) { \
+    len -= CILEN_SHORT; \
+    INCPTR(2, p); \
+    GETSHORT(cishort, p); \
+    /* Check rejected value. */ \
+    if (cishort != val) { \
+      goto bad; \
+    } \
+    try.neg = 0; \
+    LCPDEBUG(LOG_INFO, ("lcp_rejci: short opt %d rejected\n", opt)); \
+  }
+#define REJCICHAP(opt, neg, val, digest) \
+  if (go->neg && \
+      len >= CILEN_CHAP && \
+      p[1] == CILEN_CHAP && \
+      p[0] == opt) { \
+    len -= CILEN_CHAP; \
+    INCPTR(2, p); \
+    GETSHORT(cishort, p); \
+    GETCHAR(cichar, p); \
+    /* Check rejected value. */ \
+    if (cishort != val || cichar != digest) { \
+      goto bad; \
+    } \
+    try.neg = 0; \
+    try.neg_upap = 0; \
+    LCPDEBUG(LOG_INFO, ("lcp_rejci: chap opt %d rejected\n", opt)); \
+  }
+#define REJCILONG(opt, neg, val) \
+  if (go->neg && \
+      len >= CILEN_LONG && \
+      p[1] == CILEN_LONG && \
+      p[0] == opt) { \
+    len -= CILEN_LONG; \
+    INCPTR(2, p); \
+    GETLONG(cilong, p); \
+    /* Check rejected value. */ \
+    if (cilong != val) { \
+      goto bad; \
+    } \
+    try.neg = 0; \
+    LCPDEBUG(LOG_INFO, ("lcp_rejci: long opt %d rejected\n", opt)); \
+  }
+#define REJCILQR(opt, neg, val) \
+  if (go->neg && \
+      len >= CILEN_LQR && \
+      p[1] == CILEN_LQR && \
+      p[0] == opt) { \
+    len -= CILEN_LQR; \
+    INCPTR(2, p); \
+    GETSHORT(cishort, p); \
+    GETLONG(cilong, p); \
+    /* Check rejected value. */ \
+    if (cishort != PPP_LQR || cilong != val) { \
+      goto bad; \
+    } \
+    try.neg = 0; \
+    LCPDEBUG(LOG_INFO, ("lcp_rejci: LQR opt %d rejected\n", opt)); \
+  }
+#define REJCICBCP(opt, neg, val) \
+  if (go->neg && \
+      len >= CILEN_CBCP && \
+      p[1] == CILEN_CBCP && \
+      p[0] == opt) { \
+    len -= CILEN_CBCP; \
+    INCPTR(2, p); \
+    GETCHAR(cichar, p); \
+    /* Check rejected value. */ \
+    if (cichar != val) { \
+      goto bad; \
+    } \
+    try.neg = 0; \
+    LCPDEBUG(LOG_INFO, ("lcp_rejci: Callback opt %d rejected\n", opt)); \
+  }
+  
+  REJCISHORT(CI_MRU, neg_mru, go->mru);
+  REJCILONG(CI_ASYNCMAP, neg_asyncmap, go->asyncmap);
+  REJCICHAP(CI_AUTHTYPE, neg_chap, PPP_CHAP, go->chap_mdtype);
+  if (!go->neg_chap) {
+    REJCISHORT(CI_AUTHTYPE, neg_upap, PPP_PAP);
+  }
+  REJCILQR(CI_QUALITY, neg_lqr, go->lqr_period);
+  REJCICBCP(CI_CALLBACK, neg_cbcp, CBCP_OPT);
+  REJCILONG(CI_MAGICNUMBER, neg_magicnumber, go->magicnumber);
+  REJCIVOID(CI_PCOMPRESSION, neg_pcompression);
+  REJCIVOID(CI_ACCOMPRESSION, neg_accompression);
+  
+  /*
+   * If there are any remaining CIs, then this packet is bad.
+   */
+  if (len != 0) {
+    goto bad;
+  }
+  /*
+   * Now we can update state.
+   */
+  if (f->state != LS_OPENED) {
+    *go = try;
+  }
+  return 1;
+  
+bad:
+  LCPDEBUG(LOG_WARNING, ("lcp_rejci: received bad Reject!\n"));
+  return 0;
+}
+
+
+/*
+ * lcp_reqci - Check the peer's requested CIs and send appropriate response.
+ *
+ * Returns: CONFACK, CONFNAK or CONFREJ and input packet modified
+ * appropriately.  If reject_if_disagree is non-zero, doesn't return
+ * CONFNAK; returns CONFREJ if it can't return CONFACK.
+ */
+static int
+lcp_reqci(fsm *f, 
+          u_char *inp,    /* Requested CIs */
+          int *lenp,      /* Length of requested CIs */
+          int reject_if_disagree)
+{
+  lcp_options *go = &lcp_gotoptions[f->unit];
+  lcp_options *ho = &lcp_hisoptions[f->unit];
+  lcp_options *ao = &lcp_allowoptions[f->unit];
+  u_char *cip, *next;         /* Pointer to current and next CIs */
+  int cilen, citype;          /* Parsed len, type */
+  u_char cichar;              /* Parsed char value */
+  u_short cishort;            /* Parsed short value */
+  u32_t cilong;               /* Parse long value */
+  int rc = CONFACK;           /* Final packet return code */
+  int orc;                    /* Individual option return code */
+  u_char *p;                  /* Pointer to next char to parse */
+  u_char *rejp;               /* Pointer to next char in reject frame */
+  u_char *nakp;               /* Pointer to next char in Nak frame */
+  int l = *lenp;              /* Length left */
+#if TRACELCP > 0
+  char traceBuf[80];
+  size_t traceNdx = 0;
+#endif
+
+  /*
+   * Reset all his options.
+   */
+  BZERO(ho, sizeof(*ho));
+
+  /*
+   * Process all his options.
+   */
+  next = inp;
+  nakp = nak_buffer;
+  rejp = inp;
+  while (l) {
+    orc = CONFACK;      /* Assume success */
+    cip = p = next;     /* Remember begining of CI */
+    if (l < 2 ||        /* Not enough data for CI header or */
+        p[1] < 2 ||     /*  CI length too small or */
+        p[1] > l) {     /*  CI length too big? */
+      LCPDEBUG(LOG_WARNING, ("lcp_reqci: bad CI length!\n"));
+      orc = CONFREJ;    /* Reject bad CI */
+      cilen = l;        /* Reject till end of packet */
+      l = 0;            /* Don't loop again */
+      citype = 0;
+      goto endswitch;
+    }
+    GETCHAR(citype, p); /* Parse CI type */
+    GETCHAR(cilen, p);  /* Parse CI length */
+    l -= cilen;         /* Adjust remaining length */
+    next += cilen;      /* Step to next CI */
+
+    switch (citype) {   /* Check CI type */
+      case CI_MRU:
+        if (!ao->neg_mru) {    /* Allow option? */
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Reject MRU - not allowed\n"));
+          orc = CONFREJ;    /* Reject CI */
+          break;
+        } else if (cilen != CILEN_SHORT) {  /* Check CI length */
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Reject MRU - bad length\n"));
+          orc = CONFREJ;    /* Reject CI */
+          break;
+        }
+        GETSHORT(cishort, p);  /* Parse MRU */
+
+        /*
+         * He must be able to receive at least our minimum.
+         * No need to check a maximum.  If he sends a large number,
+         * we'll just ignore it.
+         */
+        if (cishort < PPP_MINMRU) {
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Nak - MRU too small\n"));
+          orc = CONFNAK;    /* Nak CI */
+          PUTCHAR(CI_MRU, nakp);
+          PUTCHAR(CILEN_SHORT, nakp);
+          PUTSHORT(PPP_MINMRU, nakp);  /* Give him a hint */
+          break;
+        }
+        ho->neg_mru = 1;    /* Remember he sent MRU */
+        ho->mru = cishort;    /* And remember value */
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " MRU %d", cishort);
+        traceNdx = strlen(traceBuf);
+#endif
+        break;
+
+      case CI_ASYNCMAP:
+        if (!ao->neg_asyncmap) {
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Reject ASYNCMAP not allowed\n"));
+          orc = CONFREJ;
+          break;
+        } else if (cilen != CILEN_LONG) {
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Reject ASYNCMAP bad length\n"));
+          orc = CONFREJ;
+          break;
+        }
+        GETLONG(cilong, p);
+        
+        /*
+         * Asyncmap must have set at least the bits
+         * which are set in lcp_allowoptions[unit].asyncmap.
+         */
+        if ((ao->asyncmap & ~cilong) != 0) {
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Nak ASYNCMAP %lX missing %lX\n", 
+                    cilong, ao->asyncmap));
+          orc = CONFNAK;
+          PUTCHAR(CI_ASYNCMAP, nakp);
+          PUTCHAR(CILEN_LONG, nakp);
+          PUTLONG(ao->asyncmap | cilong, nakp);
+          break;
+        }
+        ho->neg_asyncmap = 1;
+        ho->asyncmap = cilong;
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " ASYNCMAP=%lX", cilong);
+        traceNdx = strlen(traceBuf);
+#endif
+        break;
+
+      case CI_AUTHTYPE:
+        if (cilen < CILEN_SHORT) {
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Reject AUTHTYPE missing arg\n"));
+          orc = CONFREJ;
+          break;
+        } else if (!(ao->neg_upap || ao->neg_chap)) {
+          /*
+           * Reject the option if we're not willing to authenticate.
+           */
+          LCPDEBUG(LOG_INFO, ("lcp_reqci: Reject AUTHTYPE not allowed\n"));
+          orc = CONFREJ;
+          break;
+        }
+        GETSHORT(cishort, p);
+        
+        /*
+         * Authtype must be UPAP or CHAP.
+         *
+         * Note: if both ao->neg_upap and ao->neg_chap are set,
+         * and the peer sends a Configure-Request with two
+         * authenticate-protocol requests, one for CHAP and one
+         * for UPAP, then we will reject the second request.
+         * Whether we end up doing CHAP or UPAP depends then on
+         * the ordering of the CIs in the peer's Configure-Request.
+         */
+        
+        if (cishort == PPP_PAP) {
+          if (ho->neg_chap) {  /* we've already accepted CHAP */
+            LCPDEBUG(LOG_WARNING, ("lcp_reqci: Reject AUTHTYPE PAP already accepted\n"));
+            orc = CONFREJ;
+            break;
+          } else if (cilen != CILEN_SHORT) {
+            LCPDEBUG(LOG_WARNING, ("lcp_reqci: Reject AUTHTYPE PAP bad len\n"));
+            orc = CONFREJ;
+            break;
+          }
+          if (!ao->neg_upap) {  /* we don't want to do PAP */
+            LCPDEBUG(LOG_WARNING, ("lcp_reqci: Nak AUTHTYPE PAP not allowed\n"));
+            orc = CONFNAK;  /* NAK it and suggest CHAP */
+            PUTCHAR(CI_AUTHTYPE, nakp);
+            PUTCHAR(CILEN_CHAP, nakp);
+            PUTSHORT(PPP_CHAP, nakp);
+            PUTCHAR(ao->chap_mdtype, nakp);
+            break;
+          }
+          ho->neg_upap = 1;
+#if TRACELCP > 0
+          snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " PAP (%X)", cishort);
+          traceNdx = strlen(traceBuf);
+#endif
+          break;
+        }
+        if (cishort == PPP_CHAP) {
+          if (ho->neg_upap) {  /* we've already accepted PAP */
+            LCPDEBUG(LOG_WARNING, ("lcp_reqci: Reject AUTHTYPE CHAP accepted PAP\n"));
+            orc = CONFREJ;
+            break;
+          } else if (cilen != CILEN_CHAP) {
+            LCPDEBUG(LOG_WARNING, ("lcp_reqci: Reject AUTHTYPE CHAP bad len\n"));
+            orc = CONFREJ;
+            break;
+          }
+          if (!ao->neg_chap) {  /* we don't want to do CHAP */
+            LCPDEBUG(LOG_WARNING, ("lcp_reqci: Nak AUTHTYPE CHAP not allowed\n"));
+            orc = CONFNAK;  /* NAK it and suggest PAP */
+            PUTCHAR(CI_AUTHTYPE, nakp);
+            PUTCHAR(CILEN_SHORT, nakp);
+            PUTSHORT(PPP_PAP, nakp);
+            break;
+          }
+          GETCHAR(cichar, p);  /* get digest type*/
+          if (cichar != CHAP_DIGEST_MD5
+#if MSCHAP_SUPPORT
+              && cichar != CHAP_MICROSOFT
+#endif
+          ) {
+            LCPDEBUG(LOG_WARNING, ("lcp_reqci: Nak AUTHTYPE CHAP digest=%d\n", (int)cichar));
+            orc = CONFNAK;
+            PUTCHAR(CI_AUTHTYPE, nakp);
+            PUTCHAR(CILEN_CHAP, nakp);
+            PUTSHORT(PPP_CHAP, nakp);
+            PUTCHAR(ao->chap_mdtype, nakp);
+            break;
+          }
+#if TRACELCP > 0
+          snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " CHAP %X,%d", cishort, (int)cichar);
+          traceNdx = strlen(traceBuf);
+#endif
+          ho->chap_mdtype = cichar; /* save md type */
+          ho->neg_chap = 1;
+          break;
+        }
+        
+        /*
+         * We don't recognize the protocol they're asking for.
+         * Nak it with something we're willing to do.
+         * (At this point we know ao->neg_upap || ao->neg_chap.)
+         */
+        orc = CONFNAK;
+        PUTCHAR(CI_AUTHTYPE, nakp);
+        if (ao->neg_chap) {
+          LCPDEBUG(LOG_WARNING, ("lcp_reqci: Nak AUTHTYPE %d req CHAP\n", cishort));
+          PUTCHAR(CILEN_CHAP, nakp);
+          PUTSHORT(PPP_CHAP, nakp);
+          PUTCHAR(ao->chap_mdtype, nakp);
+        } else {
+          LCPDEBUG(LOG_WARNING, ("lcp_reqci: Nak AUTHTYPE %d req PAP\n", cishort));
+          PUTCHAR(CILEN_SHORT, nakp);
+          PUTSHORT(PPP_PAP, nakp);
+        }
+        break;
+      
+      case CI_QUALITY:
+        GETSHORT(cishort, p);
+        GETLONG(cilong, p);
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " QUALITY (%x %x)", cishort, (unsigned int) cilong);
+        traceNdx = strlen(traceBuf);
+#endif
+
+        if (!ao->neg_lqr ||
+            cilen != CILEN_LQR) {
+          orc = CONFREJ;
+          break;
+        }
+        
+        /*
+         * Check the protocol and the reporting period.
+         * XXX When should we Nak this, and what with?
+         */
+        if (cishort != PPP_LQR) {
+          orc = CONFNAK;
+          PUTCHAR(CI_QUALITY, nakp);
+          PUTCHAR(CILEN_LQR, nakp);
+          PUTSHORT(PPP_LQR, nakp);
+          PUTLONG(ao->lqr_period, nakp);
+          break;
+        }
+        break;
+      
+      case CI_MAGICNUMBER:
+        if (!(ao->neg_magicnumber || go->neg_magicnumber) ||
+            cilen != CILEN_LONG) {
+          orc = CONFREJ;
+          break;
+        }
+        GETLONG(cilong, p);
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " MAGICNUMBER (%lX)", cilong);
+        traceNdx = strlen(traceBuf);
+#endif
+
+        /*
+         * He must have a different magic number.
+         */
+        if (go->neg_magicnumber &&
+            cilong == go->magicnumber) {
+          cilong = magic();  /* Don't put magic() inside macro! */
+          orc = CONFNAK;
+          PUTCHAR(CI_MAGICNUMBER, nakp);
+          PUTCHAR(CILEN_LONG, nakp);
+          PUTLONG(cilong, nakp);
+          break;
+        }
+        ho->neg_magicnumber = 1;
+        ho->magicnumber = cilong;
+        break;
+      
+      
+      case CI_PCOMPRESSION:
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " PCOMPRESSION");
+        traceNdx = strlen(traceBuf);
+#endif
+        if (!ao->neg_pcompression ||
+            cilen != CILEN_VOID) {
+          orc = CONFREJ;
+          break;
+        }
+        ho->neg_pcompression = 1;
+        break;
+      
+      case CI_ACCOMPRESSION:
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " ACCOMPRESSION");
+        traceNdx = strlen(traceBuf);
+#endif
+        if (!ao->neg_accompression ||
+            cilen != CILEN_VOID) {
+          orc = CONFREJ;
+          break;
+        }
+        ho->neg_accompression = 1;
+        break;
+      
+      case CI_MRRU:
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " CI_MRRU");
+        traceNdx = strlen(traceBuf);
+#endif
+        orc = CONFREJ;
+        break;
+      
+      case CI_SSNHF:
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " CI_SSNHF");
+        traceNdx = strlen(traceBuf);
+#endif
+        orc = CONFREJ;
+        break;
+      
+      case CI_EPDISC:
+#if TRACELCP > 0
+        snprintf(&traceBuf[traceNdx], sizeof(traceBuf), " CI_EPDISC");
+        traceNdx = strlen(traceBuf);
+#endif
+        orc = CONFREJ;
+        break;
+      
+      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); /* The link is up; authenticate now */
+}
+
+
+/*
+ * 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); /* lwip: currently does nothing */
+}
+
+
+/*
+ * lcp_finished - LCP has finished with the lower layer.
+ */
+static void
+lcp_finished(fsm *f)
+{
+  link_terminated(f->unit); /* we are finished with the link */
+}
+
+
+#if PPP_ADDITIONAL_CALLBACKS
+/*
+ * 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 /* PPP_ADDITIONAL_CALLBACKS */
+
+/*
+ * Time to shut down the link because there is nothing out there.
+ */
+static void
+LcpLinkFailure (fsm *f)
+{
+  if (f->state == LS_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;
+
+  LWIP_UNUSED_ARG(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 == LS_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_echos_pending;
+  }
+}
+
+/*
+ * 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 */