text: /*
   * ipcp.c - PPP IP Control Protocol.
   *
   * Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The name "Carnegie Mellon University" must not be used to
   *    endorse or promote products derived from this software without
   *    prior written permission. For permission or any legal
   *    details, please contact
   *      Office of Technology Transfer
   *      Carnegie Mellon University
   *      5000 Forbes Avenue
   *      Pittsburgh, PA  15213-3890
   *      (412) 268-4387, fax: (412) 268-7395
   *      tech-transfer@andrew.cmu.edu
   *
   * 4. Redistributions of any form whatsoever must retain the following
   *    acknowledgment:
   *    "This product includes software developed by Computing Services
   *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
   *
   * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
   * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
   * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
   * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
   * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
   * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include "netif/ppp/ppp_opts.h"
  #if PPP_SUPPORT && PPP_IPV4_SUPPORT /* don't build if not configured for use in lwipopts.h */
  
  /*
   * @todo:
   */
  
  #if 0 /* UNUSED */
  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>
  #include <netdb.h>
  #include <sys/param.h>
  #include <sys/types.h>
  #include <sys/socket.h>
  #include <netinet/in.h>
  #include <arpa/inet.h>
  #endif /* UNUSED */
  
  #include "netif/ppp/ppp_impl.h"
  
  #include "netif/ppp/fsm.h"
  #include "netif/ppp/ipcp.h"
  
  #if 0 /* UNUSED */
  /* global vars */
  u32_t netmask = 0;        /* IP netmask to set on interface */
  #endif /* UNUSED */
  
  #if 0 /* UNUSED */
  bool    disable_defaultip = 0;    /* Don't use hostname for default IP adrs */
  #endif /* UNUSED */
  
  #if 0 /* moved to ppp_settings */
  bool    noremoteip = 0;        /* Let him have no IP address */
  #endif /* moved to ppp_setting */
  
  #if 0 /* UNUSED */
  /* Hook for a plugin to know when IP protocol has come up */
  void (*ip_up_hook) (void) = NULL;
  
  /* Hook for a plugin to know when IP protocol has come down */
  void (*ip_down_hook) (void) = NULL;
  
  /* Hook for a plugin to choose the remote IP address */
  void (*ip_choose_hook) (u32_t *) = NULL;
  #endif /* UNUSED */
  
  #if PPP_NOTIFY
  /* Notifiers for when IPCP goes up and down */
  struct notifier *ip_up_notifier = NULL;
  struct notifier *ip_down_notifier = NULL;
  #endif /* PPP_NOTIFY */
  
  /* local vars */
  #if 0 /* moved to ppp_pcb */
  static int default_route_set[NUM_PPP];    /* Have set up a default route */
  static int proxy_arp_set[NUM_PPP];    /* Have created proxy arp entry */
  static int ipcp_is_up;            /* have called np_up() */
  static int ipcp_is_open;        /* haven't called np_finished() */
  static bool ask_for_local;        /* request our address from peer */
  #endif /* moved to ppp_pcb */
  #if 0 /* UNUSED */
  static char vj_value[8];        /* string form of vj option value */
  static char netmask_str[20];        /* string form of netmask value */
  #endif /* UNUSED */
  
  /*
   * Callbacks for fsm code.  (CI = Configuration Information)
   */
  static void ipcp_resetci(fsm *f);    /* Reset our CI */
  static int  ipcp_cilen(fsm *f);            /* Return length of our CI */
  static void ipcp_addci(fsm *f, u_char *ucp, int *lenp); /* Add our CI */
  static int  ipcp_ackci(fsm *f, u_char *p, int len);    /* Peer ack'd our CI */
  static int  ipcp_nakci(fsm *f, u_char *p, int len, int treat_as_reject);/* Peer nak'd our CI */
  static int  ipcp_rejci(fsm *f, u_char *p, int len);    /* Peer rej'd our CI */
  static int  ipcp_reqci(fsm *f, u_char *inp, int *len, int reject_if_disagree); /* Rcv CI */
  static void ipcp_up(fsm *f);        /* We're UP */
  static void ipcp_down(fsm *f);        /* We're DOWN */
  static void ipcp_finished(fsm *f);    /* Don't need lower layer */
  
  static const fsm_callbacks ipcp_callbacks = { /* IPCP callback routines */
      ipcp_resetci,        /* Reset our Configuration Information */
      ipcp_cilen,            /* Length of our Configuration Information */
      ipcp_addci,            /* Add our Configuration Information */
      ipcp_ackci,            /* ACK our Configuration Information */
      ipcp_nakci,            /* NAK our Configuration Information */
      ipcp_rejci,            /* Reject our Configuration Information */
      ipcp_reqci,            /* Request peer's Configuration Information */
      ipcp_up,            /* Called when fsm reaches OPENED state */
      ipcp_down,            /* Called when fsm leaves OPENED state */
      NULL,            /* Called when we want the lower layer up */
      ipcp_finished,        /* Called when we want the lower layer down */
      NULL,            /* Called when Protocol-Reject received */
      NULL,            /* Retransmission is necessary */
      NULL,            /* Called to handle protocol-specific codes */
      "IPCP"            /* String name of protocol */
  };
  
  /*
   * Command-line options.
   */
  #if PPP_OPTIONS
  static int setvjslots (char **);
  static int setdnsaddr (char **);
  static int setwinsaddr (char **);
  static int setnetmask (char **);
  int setipaddr (char *, char **, int);
  
  static void printipaddr (option_t *, void (*)(void *, char *,...),void *);
  
  static option_t ipcp_option_list[] = {
      { "noip", o_bool, &ipcp_protent.enabled_flag,
        "Disable IP and IPCP" },
      { "-ip", o_bool, &ipcp_protent.enabled_flag,
        "Disable IP and IPCP", OPT_ALIAS },
  
      { "novj", o_bool, &ipcp_wantoptions[0].neg_vj,
        "Disable VJ compression", OPT_A2CLR, &ipcp_allowoptions[0].neg_vj },
      { "-vj", o_bool, &ipcp_wantoptions[0].neg_vj,
        "Disable VJ compression", OPT_ALIAS | OPT_A2CLR,
        &ipcp_allowoptions[0].neg_vj },
  
      { "novjccomp", o_bool, &ipcp_wantoptions[0].cflag,
        "Disable VJ connection-ID compression", OPT_A2CLR,
        &ipcp_allowoptions[0].cflag },
      { "-vjccomp", o_bool, &ipcp_wantoptions[0].cflag,
        "Disable VJ connection-ID compression", OPT_ALIAS | OPT_A2CLR,
        &ipcp_allowoptions[0].cflag },
  
      { "vj-max-slots", o_special, (void *)setvjslots,
        "Set maximum VJ header slots",
        OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, vj_value },
  
      { "ipcp-accept-local", o_bool, &ipcp_wantoptions[0].accept_local,
        "Accept peer's address for us", 1 },
      { "ipcp-accept-remote", o_bool, &ipcp_wantoptions[0].accept_remote,
        "Accept peer's address for it", 1 },
  
      { "ipparam", o_string, &ipparam,
        "Set ip script parameter", OPT_PRIO },
  
      { "noipdefault", o_bool, &disable_defaultip,
        "Don't use name for default IP adrs", 1 },
  
      { "ms-dns", 1, (void *)setdnsaddr,
        "DNS address for the peer's use" },
      { "ms-wins", 1, (void *)setwinsaddr,
        "Nameserver for SMB over TCP/IP for peer" },
  
      { "ipcp-restart", o_int, &ipcp_fsm[0].timeouttime,
        "Set timeout for IPCP", OPT_PRIO },
      { "ipcp-max-terminate", o_int, &ipcp_fsm[0].maxtermtransmits,
        "Set max #xmits for term-reqs", OPT_PRIO },
      { "ipcp-max-configure", o_int, &ipcp_fsm[0].maxconfreqtransmits,
        "Set max #xmits for conf-reqs", OPT_PRIO },
      { "ipcp-max-failure", o_int, &ipcp_fsm[0].maxnakloops,
        "Set max #conf-naks for IPCP", OPT_PRIO },
  
      { "defaultroute", o_bool, &ipcp_wantoptions[0].default_route,
        "Add default route", OPT_ENABLE|1, &ipcp_allowoptions[0].default_route },
      { "nodefaultroute", o_bool, &ipcp_allowoptions[0].default_route,
        "disable defaultroute option", OPT_A2CLR,
        &ipcp_wantoptions[0].default_route },
      { "-defaultroute", o_bool, &ipcp_allowoptions[0].default_route,
        "disable defaultroute option", OPT_ALIAS | OPT_A2CLR,
        &ipcp_wantoptions[0].default_route },
  
      { "replacedefaultroute", o_bool,
                  &ipcp_wantoptions[0].replace_default_route,
        "Replace default route", 1
      },
      { "noreplacedefaultroute", o_bool,
                  &ipcp_allowoptions[0].replace_default_route,
        "Never replace default route", OPT_A2COPY,
                  &ipcp_wantoptions[0].replace_default_route },
      { "proxyarp", o_bool, &ipcp_wantoptions[0].proxy_arp,
        "Add proxy ARP entry", OPT_ENABLE|1, &ipcp_allowoptions[0].proxy_arp },
      { "noproxyarp", o_bool, &ipcp_allowoptions[0].proxy_arp,
        "disable proxyarp option", OPT_A2CLR,
        &ipcp_wantoptions[0].proxy_arp },
      { "-proxyarp", o_bool, &ipcp_allowoptions[0].proxy_arp,
        "disable proxyarp option", OPT_ALIAS | OPT_A2CLR,
        &ipcp_wantoptions[0].proxy_arp },
  
      { "usepeerdns", o_bool, &usepeerdns,
        "Ask peer for DNS address(es)", 1 },
  
      { "netmask", o_special, (void *)setnetmask,
        "set netmask", OPT_PRIO | OPT_A2STRVAL | OPT_STATIC, netmask_str },
  
      { "ipcp-no-addresses", o_bool, &ipcp_wantoptions[0].old_addrs,
        "Disable old-style IP-Addresses usage", OPT_A2CLR,
        &ipcp_allowoptions[0].old_addrs },
      { "ipcp-no-address", o_bool, &ipcp_wantoptions[0].neg_addr,
        "Disable IP-Address usage", OPT_A2CLR,
        &ipcp_allowoptions[0].neg_addr },
  
      { "noremoteip", o_bool, &noremoteip,
        "Allow peer to have no IP address", 1 },
  
      { "nosendip", o_bool, &ipcp_wantoptions[0].neg_addr,
        "Don't send our IP address to peer", OPT_A2CLR,
        &ipcp_wantoptions[0].old_addrs},
  
      { "IP addresses", o_wild, (void *) &setipaddr,
        "set local and remote IP addresses",
        OPT_NOARG | OPT_A2PRINTER, (void *) &printipaddr },
  
      { NULL }
  };
  #endif /* PPP_OPTIONS */
  
  /*
   * Protocol entry points from main code.
   */
  static void ipcp_init(ppp_pcb *pcb);
  static void ipcp_open(ppp_pcb *pcb);
  static void ipcp_close(ppp_pcb *pcb, const char *reason);
  static void ipcp_lowerup(ppp_pcb *pcb);
  static void ipcp_lowerdown(ppp_pcb *pcb);
  static void ipcp_input(ppp_pcb *pcb, u_char *p, int len);
  static void ipcp_protrej(ppp_pcb *pcb);
  #if PRINTPKT_SUPPORT
  static int ipcp_printpkt(const u_char *p, int plen,
          void (*printer) (void *, const char *, ...), void *arg);
  #endif /* PRINTPKT_SUPPORT */
  #if PPP_OPTIONS
  static void ip_check_options (void);
  #endif /* PPP_OPTIONS */
  #if DEMAND_SUPPORT
  static int  ip_demand_conf (int);
  static int  ip_active_pkt (u_char *, int);
  #endif /* DEMAND_SUPPORT */
  #if 0 /* UNUSED */
  static void create_resolv (u32_t, u32_t);
  #endif /* UNUSED */
  
  const struct protent ipcp_protent = {
      PPP_IPCP,
      ipcp_init,
      ipcp_input,
      ipcp_protrej,
      ipcp_lowerup,
      ipcp_lowerdown,
      ipcp_open,
      ipcp_close,
  #if PRINTPKT_SUPPORT
      ipcp_printpkt,
  #endif /* PRINTPKT_SUPPORT */
  #if PPP_DATAINPUT
      NULL,
  #endif /* PPP_DATAINPUT */
  #if PRINTPKT_SUPPORT
      "IPCP",
      "IP",
  #endif /* PRINTPKT_SUPPORT */
  #if PPP_OPTIONS
      ipcp_option_list,
      ip_check_options,
  #endif /* PPP_OPTIONS */
  #if DEMAND_SUPPORT
      ip_demand_conf,
      ip_active_pkt
  #endif /* DEMAND_SUPPORT */
  };
  
  static void ipcp_clear_addrs(ppp_pcb *pcb, u32_t ouraddr, u32_t hisaddr, u8_t replacedefaultroute);
  
  /*
   * Lengths of configuration options.
   */
  #define CILEN_VOID    2
  #define CILEN_COMPRESS    4    /* min length for compression protocol opt. */
  #define CILEN_VJ    6    /* length for RFC1332 Van-Jacobson opt. */
  #define CILEN_ADDR    6    /* new-style single address option */
  #define CILEN_ADDRS    10    /* old-style dual address option */
  
  
  #define CODENAME(x)    ((x) == CONFACK ? "ACK" : \
               (x) == CONFNAK ? "NAK" : "REJ")
  
  #if 0 /* UNUSED, already defined by lwIP */
  /*
   * Make a string representation of a network IP address.
   */
  char *
  ip_ntoa(ipaddr)
  u32_t ipaddr;
  {
      static char b[64];
  
      slprintf(b, sizeof(b), "%I", ipaddr);
      return b;
  }
  #endif /* UNUSED, already defined by lwIP */
  
  /*
   * Option parsing.
   */
  #if PPP_OPTIONS
  /*
   * setvjslots - set maximum number of connection slots for VJ compression
   */
  static int
  setvjslots(argv)
      char **argv;
  {
      int value;
  
      if (!int_option(*argv, &value))
      return 0;
  
      if (value < 2 || value > 16) {
      option_error("vj-max-slots value must be between 2 and 16");
      return 0;
      }
      ipcp_wantoptions [0].maxslotindex =
          ipcp_allowoptions[0].maxslotindex = value - 1;
      slprintf(vj_value, sizeof(vj_value), "%d", value);
      return 1;
  }
  
  /*
   * setdnsaddr - set the dns address(es)
   */
  static int
  setdnsaddr(argv)
      char **argv;
  {
      u32_t dns;
      struct hostent *hp;
  
      dns = inet_addr(*argv);
      if (dns == (u32_t) -1) {
      if ((hp = gethostbyname(*argv)) == NULL) {
          option_error("invalid address parameter '%s' for ms-dns option",
               *argv);
          return 0;
      }
      dns = *(u32_t *)hp->h_addr;
      }
  
      /* We take the last 2 values given, the 2nd-last as the primary
         and the last as the secondary.  If only one is given it
         becomes both primary and secondary. */
      if (ipcp_allowoptions[0].dnsaddr[1] == 0)
      ipcp_allowoptions[0].dnsaddr[0] = dns;
      else
      ipcp_allowoptions[0].dnsaddr[0] = ipcp_allowoptions[0].dnsaddr[1];
  
      /* always set the secondary address value. */
      ipcp_allowoptions[0].dnsaddr[1] = dns;
  
      return (1);
  }
  
  /*
   * setwinsaddr - set the wins address(es)
   * This is primrarly used with the Samba package under UNIX or for pointing
   * the caller to the existing WINS server on a Windows NT platform.
   */
  static int
  setwinsaddr(argv)
      char **argv;
  {
      u32_t wins;
      struct hostent *hp;
  
      wins = inet_addr(*argv);
      if (wins == (u32_t) -1) {
      if ((hp = gethostbyname(*argv)) == NULL) {
          option_error("invalid address parameter '%s' for ms-wins option",
               *argv);
          return 0;
      }
      wins = *(u32_t *)hp->h_addr;
      }
  
      /* We take the last 2 values given, the 2nd-last as the primary
         and the last as the secondary.  If only one is given it
         becomes both primary and secondary. */
      if (ipcp_allowoptions[0].winsaddr[1] == 0)
      ipcp_allowoptions[0].winsaddr[0] = wins;
      else
      ipcp_allowoptions[0].winsaddr[0] = ipcp_allowoptions[0].winsaddr[1];
  
      /* always set the secondary address value. */
      ipcp_allowoptions[0].winsaddr[1] = wins;
  
      return (1);
  }
  
  /*
   * setipaddr - Set the IP address
   * If doit is 0, the call is to check whether this option is
   * potentially an IP address specification.
   * Not static so that plugins can call it to set the addresses
   */
  int
  setipaddr(arg, argv, doit)
      char *arg;
      char **argv;
      int doit;
  {
      struct hostent *hp;
      char *colon;
      u32_t local, remote;
      ipcp_options *wo = &ipcp_wantoptions[0];
      static int prio_local = 0, prio_remote = 0;
  
      /*
       * IP address pair separated by ":".
       */
      if ((colon = strchr(arg, ':')) == NULL)
      return 0;
      if (!doit)
      return 1;
    
      /*
       * If colon first character, then no local addr.
       */
      if (colon != arg && option_priority >= prio_local) {
      *colon = '\0';
      if ((local = inet_addr(arg)) == (u32_t) -1) {
          if ((hp = gethostbyname(arg)) == NULL) {
          option_error("unknown host: %s", arg);
          return 0;
          }
          local = *(u32_t *)hp->h_addr;
      }
      if (bad_ip_adrs(local)) {
          option_error("bad local IP address %s", ip_ntoa(local));
          return 0;
      }
      if (local != 0)
          wo->ouraddr = local;
      *colon = ':';
      prio_local = option_priority;
      }
    
      /*
       * If colon last character, then no remote addr.
       */
      if (*++colon != '\0' && option_priority >= prio_remote) {
      if ((remote = inet_addr(colon)) == (u32_t) -1) {
          if ((hp = gethostbyname(colon)) == NULL) {
          option_error("unknown host: %s", colon);
          return 0;
          }
          remote = *(u32_t *)hp->h_addr;
          if (remote_name[0] == 0)
          strlcpy(remote_name, colon, sizeof(remote_name));
      }
      if (bad_ip_adrs(remote)) {
          option_error("bad remote IP address %s", ip_ntoa(remote));
          return 0;
      }
      if (remote != 0)
          wo->hisaddr = remote;
      prio_remote = option_priority;
      }
  
      return 1;
  }
  
  static void
  printipaddr(opt, printer, arg)
      option_t *opt;
      void (*printer) (void *, char *, ...);
      void *arg;
  {
      ipcp_options *wo = &ipcp_wantoptions[0];
  
      if (wo->ouraddr != 0)
          printer(arg, "%I", wo->ouraddr);
      printer(arg, ":");
      if (wo->hisaddr != 0)
          printer(arg, "%I", wo->hisaddr);
  }
  
  /*
   * setnetmask - set the netmask to be used on the interface.
   */
  static int
  setnetmask(argv)
      char **argv;
  {
      u32_t mask;
      int n;
      char *p;
  
      /*
       * Unfortunately, if we use inet_addr, we can't tell whether
       * a result of all 1s is an error or a valid 255.255.255.255.
       */
      p = *argv;
      n = parse_dotted_ip(p, &mask);
  
      mask = lwip_htonl(mask);
  
      if (n == 0 || p[n] != 0 || (netmask & ~mask) != 0) {
      option_error("invalid netmask value '%s'", *argv);
      return 0;
      }
  
      netmask = mask;
      slprintf(netmask_str, sizeof(netmask_str), "%I", mask);
  
      return (1);
  }
  
  int
  parse_dotted_ip(p, vp)
      char *p;
      u32_t *vp;
  {
      int n;
      u32_t v, b;
      char *endp, *p0 = p;
  
      v = 0;
      for (n = 3;; --n) {
      b = strtoul(p, &endp, 0);
      if (endp == p)
          return 0;
      if (b > 255) {
          if (n < 3)
          return 0;
          /* accept e.g. 0xffffff00 */
          *vp = b;
          return endp - p0;
      }
      v |= b << (n * 8);
      p = endp;
      if (n == 0)
          break;
      if (*p != '.')
          return 0;
      ++p;
      }
      *vp = v;
      return p - p0;
  }
  #endif /* PPP_OPTIONS */
  
  /*
   * ipcp_init - Initialize IPCP.
   */
  static void ipcp_init(ppp_pcb *pcb) {
      fsm *f = &pcb->ipcp_fsm;
  
      ipcp_options *wo = &pcb->ipcp_wantoptions;
      ipcp_options *ao = &pcb->ipcp_allowoptions;
  
      f->pcb = pcb;
      f->protocol = PPP_IPCP;
      f->callbacks = &ipcp_callbacks;
      fsm_init(f);
  
      /*
       * Some 3G modems use repeated IPCP NAKs as a way of stalling
       * until they can contact a server on the network, so we increase
       * the default number of NAKs we accept before we start treating
       * them as rejects.
       */
      f->maxnakloops = 100;
  
  #if 0 /* Not necessary, everything is cleared in ppp_new() */
      memset(wo, 0, sizeof(*wo));
      memset(ao, 0, sizeof(*ao));
  #endif /* 0 */
  
      wo->neg_addr = wo->old_addrs = 1;
  #if VJ_SUPPORT
      wo->neg_vj = 1;
      wo->vj_protocol = IPCP_VJ_COMP;
      wo->maxslotindex = MAX_STATES - 1; /* really max index */
      wo->cflag = 1;
  #endif /* VJ_SUPPORT */
  
  #if 0 /* UNUSED */
      /* wanting default route by default */
      wo->default_route = 1;
  #endif /* UNUSED */
  
      ao->neg_addr = ao->old_addrs = 1;
  #if VJ_SUPPORT
      /* max slots and slot-id compression are currently hardwired in */
      /* ppp_if.c to 16 and 1, this needs to be changed (among other */
      /* things) gmc */
  
      ao->neg_vj = 1;
      ao->maxslotindex = MAX_STATES - 1;
      ao->cflag = 1;
  #endif /* #if VJ_SUPPORT */
  
  #if 0 /* UNUSED */
      /*
       * XXX These control whether the user may use the proxyarp
       * and defaultroute options.
       */
      ao->proxy_arp = 1;
      ao->default_route = 1;
  #endif /* UNUSED */
  }
  
  
  /*
   * ipcp_open - IPCP is allowed to come up.
   */
  static void ipcp_open(ppp_pcb *pcb) {
      fsm *f = &pcb->ipcp_fsm;
      fsm_open(f);
      pcb->ipcp_is_open = 1;
  }
  
  
  /*
   * ipcp_close - Take IPCP down.
   */
  static void ipcp_close(ppp_pcb *pcb, const char *reason) {
      fsm *f = &pcb->ipcp_fsm;
      fsm_close(f, reason);
  }
  
  
  /*
   * ipcp_lowerup - The lower layer is up.
   */
  static void ipcp_lowerup(ppp_pcb *pcb) {
      fsm *f = &pcb->ipcp_fsm;
      fsm_lowerup(f);
  }
  
  
  /*
   * ipcp_lowerdown - The lower layer is down.
   */
  static void ipcp_lowerdown(ppp_pcb *pcb) {
      fsm *f = &pcb->ipcp_fsm;
      fsm_lowerdown(f);
  }
  
  
  /*
   * ipcp_input - Input IPCP packet.
   */
  static void ipcp_input(ppp_pcb *pcb, u_char *p, int len) {
      fsm *f = &pcb->ipcp_fsm;
      fsm_input(f, p, len);
  }
  
  
  /*
   * ipcp_protrej - A Protocol-Reject was received for IPCP.
   *
   * Pretend the lower layer went down, so we shut up.
   */
  static void ipcp_protrej(ppp_pcb *pcb) {
      fsm *f = &pcb->ipcp_fsm;
      fsm_lowerdown(f);
  }
  
  
  /*
   * ipcp_resetci - Reset our CI.
   * Called by fsm_sconfreq, Send Configure Request.
   */
  static void ipcp_resetci(fsm *f) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *wo = &pcb->ipcp_wantoptions;
      ipcp_options *go = &pcb->ipcp_gotoptions;
      ipcp_options *ao = &pcb->ipcp_allowoptions;
  
      wo->req_addr = (wo->neg_addr || wo->old_addrs) &&
      (ao->neg_addr || ao->old_addrs);
      if (wo->ouraddr == 0)
      wo->accept_local = 1;
      if (wo->hisaddr == 0)
      wo->accept_remote = 1;
  #if LWIP_DNS
      wo->req_dns1 = wo->req_dns2 = pcb->settings.usepeerdns;    /* Request DNS addresses from the peer */
  #endif /* LWIP_DNS */
      *go = *wo;
      if (!pcb->ask_for_local)
      go->ouraddr = 0;
  #if 0 /* UNUSED */
      if (ip_choose_hook) {
      ip_choose_hook(&wo->hisaddr);
      if (wo->hisaddr) {
          wo->accept_remote = 0;
      }
      }
  #endif /* UNUSED */
      BZERO(&pcb->ipcp_hisoptions, sizeof(ipcp_options));
  }
  
  
  /*
   * ipcp_cilen - Return length of our CI.
   * Called by fsm_sconfreq, Send Configure Request.
   */
  static int ipcp_cilen(fsm *f) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *go = &pcb->ipcp_gotoptions;
  #if VJ_SUPPORT
      ipcp_options *wo = &pcb->ipcp_wantoptions;
  #endif /* VJ_SUPPORT */
      ipcp_options *ho = &pcb->ipcp_hisoptions;
  
  #define LENCIADDRS(neg)        (neg ? CILEN_ADDRS : 0)
  #if VJ_SUPPORT
  #define LENCIVJ(neg, old)    (neg ? (old? CILEN_COMPRESS : CILEN_VJ) : 0)
  #endif /* VJ_SUPPORT */
  #define LENCIADDR(neg)        (neg ? CILEN_ADDR : 0)
  #if LWIP_DNS
  #define LENCIDNS(neg)        LENCIADDR(neg)
  #endif /* LWIP_DNS */
  #if 0 /* UNUSED - WINS */
  #define LENCIWINS(neg)        LENCIADDR(neg)
  #endif /* UNUSED - WINS */
  
      /*
       * First see if we want to change our options to the old
       * forms because we have received old forms from the peer.
       */
      if (go->neg_addr && go->old_addrs && !ho->neg_addr && ho->old_addrs)
      go->neg_addr = 0;
  
  #if VJ_SUPPORT
      if (wo->neg_vj && !go->neg_vj && !go->old_vj) {
      /* try an older style of VJ negotiation */
      /* use the old style only if the peer did */
      if (ho->neg_vj && ho->old_vj) {
          go->neg_vj = 1;
          go->old_vj = 1;
          go->vj_protocol = ho->vj_protocol;
      }
      }
  #endif /* VJ_SUPPORT */
  
      return (LENCIADDRS(!go->neg_addr && go->old_addrs) +
  #if VJ_SUPPORT
          LENCIVJ(go->neg_vj, go->old_vj) +
  #endif /* VJ_SUPPORT */
          LENCIADDR(go->neg_addr) +
  #if LWIP_DNS
          LENCIDNS(go->req_dns1) +
          LENCIDNS(go->req_dns2) +
  #endif /* LWIP_DNS */
  #if 0 /* UNUSED - WINS */
          LENCIWINS(go->winsaddr[0]) +
          LENCIWINS(go->winsaddr[1]) +
  #endif /* UNUSED - WINS */
          0);
  }
  
  
  /*
   * ipcp_addci - Add our desired CIs to a packet.
   * Called by fsm_sconfreq, Send Configure Request.
   */
  static void ipcp_addci(fsm *f, u_char *ucp, int *lenp) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *go = &pcb->ipcp_gotoptions;
      int len = *lenp;
  
  #define ADDCIADDRS(opt, neg, val1, val2) \
      if (neg) { \
      if (len >= CILEN_ADDRS) { \
          u32_t l; \
          PUTCHAR(opt, ucp); \
          PUTCHAR(CILEN_ADDRS, ucp); \
          l = lwip_ntohl(val1); \
          PUTLONG(l, ucp); \
          l = lwip_ntohl(val2); \
          PUTLONG(l, ucp); \
          len -= CILEN_ADDRS; \
      } else \
          go->old_addrs = 0; \
      }
  
  #if VJ_SUPPORT
  #define ADDCIVJ(opt, neg, val, old, maxslotindex, cflag) \
      if (neg) { \
      int vjlen = old? CILEN_COMPRESS : CILEN_VJ; \
      if (len >= vjlen) { \
          PUTCHAR(opt, ucp); \
          PUTCHAR(vjlen, ucp); \
          PUTSHORT(val, ucp); \
          if (!old) { \
          PUTCHAR(maxslotindex, ucp); \
          PUTCHAR(cflag, ucp); \
          } \
          len -= vjlen; \
      } else \
          neg = 0; \
      }
  #endif /* VJ_SUPPORT */
  
  #define ADDCIADDR(opt, neg, val) \
      if (neg) { \
      if (len >= CILEN_ADDR) { \
          u32_t l; \
          PUTCHAR(opt, ucp); \
          PUTCHAR(CILEN_ADDR, ucp); \
          l = lwip_ntohl(val); \
          PUTLONG(l, ucp); \
          len -= CILEN_ADDR; \
      } else \
          neg = 0; \
      }
  
  #if LWIP_DNS
  #define ADDCIDNS(opt, neg, addr) \
      if (neg) { \
      if (len >= CILEN_ADDR) { \
          u32_t l; \
          PUTCHAR(opt, ucp); \
          PUTCHAR(CILEN_ADDR, ucp); \
          l = lwip_ntohl(addr); \
          PUTLONG(l, ucp); \
          len -= CILEN_ADDR; \
      } else \
          neg = 0; \
      }
  #endif /* LWIP_DNS */
  
  #if 0 /* UNUSED - WINS */
  #define ADDCIWINS(opt, addr) \
      if (addr) { \
      if (len >= CILEN_ADDR) { \
          u32_t l; \
          PUTCHAR(opt, ucp); \
          PUTCHAR(CILEN_ADDR, ucp); \
          l = lwip_ntohl(addr); \
          PUTLONG(l, ucp); \
          len -= CILEN_ADDR; \
      } else \
          addr = 0; \
      }
  #endif /* UNUSED - WINS */
  
      ADDCIADDRS(CI_ADDRS, !go->neg_addr && go->old_addrs, go->ouraddr,
             go->hisaddr);
  
  #if VJ_SUPPORT
      ADDCIVJ(CI_COMPRESSTYPE, go->neg_vj, go->vj_protocol, go->old_vj,
          go->maxslotindex, go->cflag);
  #endif /* VJ_SUPPORT */
  
      ADDCIADDR(CI_ADDR, go->neg_addr, go->ouraddr);
  
  #if LWIP_DNS
      ADDCIDNS(CI_MS_DNS1, go->req_dns1, go->dnsaddr[0]);
  
      ADDCIDNS(CI_MS_DNS2, go->req_dns2, go->dnsaddr[1]);
  #endif /* LWIP_DNS */
  
  #if 0 /* UNUSED - WINS */
      ADDCIWINS(CI_MS_WINS1, go->winsaddr[0]);
  
      ADDCIWINS(CI_MS_WINS2, go->winsaddr[1]);
  #endif /* UNUSED - WINS */
      
      *lenp -= len;
  }
  
  
  /*
   * ipcp_ackci - Ack our CIs.
   * Called by fsm_rconfack, Receive Configure ACK.
   *
   * Returns:
   *    0 - Ack was bad.
   *    1 - Ack was good.
   */
  static int ipcp_ackci(fsm *f, u_char *p, int len) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *go = &pcb->ipcp_gotoptions;
      u_short cilen, citype;
      u32_t cilong;
  #if VJ_SUPPORT
      u_short cishort;
      u_char cimaxslotindex, cicflag;
  #endif /* VJ_SUPPORT */
  
      /*
       * 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 ACKCIADDRS(opt, neg, val1, val2) \
      if (neg) { \
      u32_t l; \
      if ((len -= CILEN_ADDRS) < 0) \
          goto bad; \
      GETCHAR(citype, p); \
      GETCHAR(cilen, p); \
      if (cilen != CILEN_ADDRS || \
          citype != opt) \
          goto bad; \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      if (val1 != cilong) \
          goto bad; \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      if (val2 != cilong) \
          goto bad; \
      }
  
  #if VJ_SUPPORT
  #define ACKCIVJ(opt, neg, val, old, maxslotindex, cflag) \
      if (neg) { \
      int vjlen = old? CILEN_COMPRESS : CILEN_VJ; \
      if ((len -= vjlen) < 0) \
          goto bad; \
      GETCHAR(citype, p); \
      GETCHAR(cilen, p); \
      if (cilen != vjlen || \
          citype != opt)  \
          goto bad; \
      GETSHORT(cishort, p); \
      if (cishort != val) \
          goto bad; \
      if (!old) { \
          GETCHAR(cimaxslotindex, p); \
          if (cimaxslotindex != maxslotindex) \
          goto bad; \
          GETCHAR(cicflag, p); \
          if (cicflag != cflag) \
          goto bad; \
      } \
      }
  #endif /* VJ_SUPPORT */
  
  #define ACKCIADDR(opt, neg, val) \
      if (neg) { \
      u32_t l; \
      if ((len -= CILEN_ADDR) < 0) \
          goto bad; \
      GETCHAR(citype, p); \
      GETCHAR(cilen, p); \
      if (cilen != CILEN_ADDR || \
          citype != opt) \
          goto bad; \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      if (val != cilong) \
          goto bad; \
      }
  
  #if LWIP_DNS
  #define ACKCIDNS(opt, neg, addr) \
      if (neg) { \
      u32_t l; \
      if ((len -= CILEN_ADDR) < 0) \
          goto bad; \
      GETCHAR(citype, p); \
      GETCHAR(cilen, p); \
      if (cilen != CILEN_ADDR || citype != opt) \
          goto bad; \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      if (addr != cilong) \
          goto bad; \
      }
  #endif /* LWIP_DNS */
  
  #if 0 /* UNUSED - WINS */
  #define ACKCIWINS(opt, addr) \
      if (addr) { \
      u32_t l; \
      if ((len -= CILEN_ADDR) < 0) \
          goto bad; \
      GETCHAR(citype, p); \
      GETCHAR(cilen, p); \
      if (cilen != CILEN_ADDR || citype != opt) \
          goto bad; \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      if (addr != cilong) \
          goto bad; \
      }
  #endif /* UNUSED - WINS */
  
      ACKCIADDRS(CI_ADDRS, !go->neg_addr && go->old_addrs, go->ouraddr,
             go->hisaddr);
  
  #if VJ_SUPPORT
      ACKCIVJ(CI_COMPRESSTYPE, go->neg_vj, go->vj_protocol, go->old_vj,
          go->maxslotindex, go->cflag);
  #endif /* VJ_SUPPORT */
  
      ACKCIADDR(CI_ADDR, go->neg_addr, go->ouraddr);
  
  #if LWIP_DNS
      ACKCIDNS(CI_MS_DNS1, go->req_dns1, go->dnsaddr[0]);
  
      ACKCIDNS(CI_MS_DNS2, go->req_dns2, go->dnsaddr[1]);
  #endif /* LWIP_DNS */
  
  #if 0 /* UNUSED - WINS */
      ACKCIWINS(CI_MS_WINS1, go->winsaddr[0]);
  
      ACKCIWINS(CI_MS_WINS2, go->winsaddr[1]);
  #endif /* UNUSED - WINS */
  
      /*
       * If there are any remaining CIs, then this packet is bad.
       */
      if (len != 0)
      goto bad;
      return (1);
  
  bad:
      IPCPDEBUG(("ipcp_ackci: received bad Ack!"));
      return (0);
  }
  
  /*
   * ipcp_nakci - Peer has sent a NAK for some of our CIs.
   * This should not modify any state if the Nak is bad
   * or if IPCP is in the OPENED state.
   * Calback from fsm_rconfnakrej - Receive Configure-Nak or Configure-Reject.
   *
   * Returns:
   *    0 - Nak was bad.
   *    1 - Nak was good.
   */
  static int ipcp_nakci(fsm *f, u_char *p, int len, int treat_as_reject) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *go = &pcb->ipcp_gotoptions;
      u_char citype, cilen, *next;
  #if VJ_SUPPORT
      u_char cimaxslotindex, cicflag;
      u_short cishort;
  #endif /* VJ_SUPPORT */
      u32_t ciaddr1, ciaddr2, l;
  #if LWIP_DNS
      u32_t cidnsaddr;
  #endif /* LWIP_DNS */
      ipcp_options no;        /* options we've seen Naks for */
      ipcp_options try_;        /* options to request next time */
  
      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 NAKCIADDRS(opt, neg, code) \
      if ((neg) && \
      (cilen = p[1]) == CILEN_ADDRS && \
      len >= cilen && \
      p[0] == opt) { \
      len -= cilen; \
      INCPTR(2, p); \
      GETLONG(l, p); \
      ciaddr1 = lwip_htonl(l); \
      GETLONG(l, p); \
      ciaddr2 = lwip_htonl(l); \
      no.old_addrs = 1; \
      code \
      }
  
  #if VJ_SUPPORT
  #define NAKCIVJ(opt, neg, code) \
      if (go->neg && \
      ((cilen = p[1]) == CILEN_COMPRESS || cilen == CILEN_VJ) && \
      len >= cilen && \
      p[0] == opt) { \
      len -= cilen; \
      INCPTR(2, p); \
      GETSHORT(cishort, p); \
      no.neg = 1; \
          code \
      }
  #endif /* VJ_SUPPORT */
  
  #define NAKCIADDR(opt, neg, code) \
      if (go->neg && \
      (cilen = p[1]) == CILEN_ADDR && \
      len >= cilen && \
      p[0] == opt) { \
      len -= cilen; \
      INCPTR(2, p); \
      GETLONG(l, p); \
      ciaddr1 = lwip_htonl(l); \
      no.neg = 1; \
      code \
      }
  
  #if LWIP_DNS
  #define NAKCIDNS(opt, neg, code) \
      if (go->neg && \
      ((cilen = p[1]) == CILEN_ADDR) && \
      len >= cilen && \
      p[0] == opt) { \
      len -= cilen; \
      INCPTR(2, p); \
      GETLONG(l, p); \
      cidnsaddr = lwip_htonl(l); \
      no.neg = 1; \
      code \
      }
  #endif /* LWIP_DNS */
  
      /*
       * Accept the peer's idea of {our,his} address, if different
       * from our idea, only if the accept_{local,remote} flag is set.
       */
      NAKCIADDRS(CI_ADDRS, !go->neg_addr && go->old_addrs,
             if (treat_as_reject) {
             try_.old_addrs = 0;
             } else {
             if (go->accept_local && ciaddr1) {
                 /* take his idea of our address */
                 try_.ouraddr = ciaddr1;
             }
             if (go->accept_remote && ciaddr2) {
                 /* take his idea of his address */
                 try_.hisaddr = ciaddr2;
             }
             }
      );
  
  #if VJ_SUPPORT
      /*
       * Accept the peer's value of maxslotindex provided that it
       * is less than what we asked for.  Turn off slot-ID compression
       * if the peer wants.  Send old-style compress-type option if
       * the peer wants.
       */
      NAKCIVJ(CI_COMPRESSTYPE, neg_vj,
          if (treat_as_reject) {
          try_.neg_vj = 0;
          } else if (cilen == CILEN_VJ) {
          GETCHAR(cimaxslotindex, p);
          GETCHAR(cicflag, p);
          if (cishort == IPCP_VJ_COMP) {
              try_.old_vj = 0;
              if (cimaxslotindex < go->maxslotindex)
              try_.maxslotindex = cimaxslotindex;
              if (!cicflag)
              try_.cflag = 0;
          } else {
              try_.neg_vj = 0;
          }
          } else {
          if (cishort == IPCP_VJ_COMP || cishort == IPCP_VJ_COMP_OLD) {
              try_.old_vj = 1;
              try_.vj_protocol = cishort;
          } else {
              try_.neg_vj = 0;
          }
          }
          );
  #endif /* VJ_SUPPORT */
  
      NAKCIADDR(CI_ADDR, neg_addr,
            if (treat_as_reject) {
            try_.neg_addr = 0;
            try_.old_addrs = 0;
            } else if (go->accept_local && ciaddr1) {
            /* take his idea of our address */
            try_.ouraddr = ciaddr1;
            }
            );
  
  #if LWIP_DNS
      NAKCIDNS(CI_MS_DNS1, req_dns1,
           if (treat_as_reject) {
           try_.req_dns1 = 0;
           } else {
           try_.dnsaddr[0] = cidnsaddr;
           }
           );
  
      NAKCIDNS(CI_MS_DNS2, req_dns2,
           if (treat_as_reject) {
           try_.req_dns2 = 0;
           } else {
           try_.dnsaddr[1] = cidnsaddr;
           }
           );
  #endif /* #if LWIP_DNS */
  
      /*
       * There may be remaining CIs, if the peer is requesting negotiation
       * on an option that we didn't include in our request packet.
       * If they want to negotiate about IP addresses, we comply.
       * If they want us to ask for compression, we refuse.
       * If they want us to ask for ms-dns, we do that, since some
       * peers get huffy if we don't.
       */
      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) {
  #if VJ_SUPPORT
      case CI_COMPRESSTYPE:
          if (go->neg_vj || no.neg_vj ||
          (cilen != CILEN_VJ && cilen != CILEN_COMPRESS))
          goto bad;
          no.neg_vj = 1;
          break;
  #endif /* VJ_SUPPORT */
      case CI_ADDRS:
          if ((!go->neg_addr && go->old_addrs) || no.old_addrs
          || cilen != CILEN_ADDRS)
          goto bad;
          try_.neg_addr = 0;
          GETLONG(l, p);
          ciaddr1 = lwip_htonl(l);
          if (ciaddr1 && go->accept_local)
          try_.ouraddr = ciaddr1;
          GETLONG(l, p);
          ciaddr2 = lwip_htonl(l);
          if (ciaddr2 && go->accept_remote)
          try_.hisaddr = ciaddr2;
          no.old_addrs = 1;
          break;
      case CI_ADDR:
          if (go->neg_addr || no.neg_addr || cilen != CILEN_ADDR)
          goto bad;
          try_.old_addrs = 0;
          GETLONG(l, p);
          ciaddr1 = lwip_htonl(l);
          if (ciaddr1 && go->accept_local)
          try_.ouraddr = ciaddr1;
          if (try_.ouraddr != 0)
          try_.neg_addr = 1;
          no.neg_addr = 1;
          break;
  #if LWIP_DNS
      case CI_MS_DNS1:
          if (go->req_dns1 || no.req_dns1 || cilen != CILEN_ADDR)
          goto bad;
          GETLONG(l, p);
          try_.dnsaddr[0] = lwip_htonl(l);
          try_.req_dns1 = 1;
          no.req_dns1 = 1;
          break;
      case CI_MS_DNS2:
          if (go->req_dns2 || no.req_dns2 || cilen != CILEN_ADDR)
          goto bad;
          GETLONG(l, p);
          try_.dnsaddr[1] = lwip_htonl(l);
          try_.req_dns2 = 1;
          no.req_dns2 = 1;
          break;
  #endif /* LWIP_DNS */
  #if 0 /* UNUSED - WINS */
      case CI_MS_WINS1:
      case CI_MS_WINS2:
          if (cilen != CILEN_ADDR)
          goto bad;
          GETLONG(l, p);
          ciaddr1 = lwip_htonl(l);
          if (ciaddr1)
          try_.winsaddr[citype == CI_MS_WINS2] = ciaddr1;
          break;
  #endif /* UNUSED - WINS */
      default:
          break;
      }
      p = next;
      }
  
      /*
       * OK, the Nak is good.  Now we can update state.
       * If there are any remaining options, we ignore them.
       */
      if (f->state != PPP_FSM_OPENED)
      *go = try_;
  
      return 1;
  
  bad:
      IPCPDEBUG(("ipcp_nakci: received bad Nak!"));
      return 0;
  }
  
  
  /*
   * ipcp_rejci - Reject some of our CIs.
   * Callback from fsm_rconfnakrej.
   */
  static int ipcp_rejci(fsm *f, u_char *p, int len) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *go = &pcb->ipcp_gotoptions;
      u_char cilen;
  #if VJ_SUPPORT
      u_char cimaxslotindex, ciflag;
      u_short cishort;
  #endif /* VJ_SUPPORT */
      u32_t cilong;
      ipcp_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 REJCIADDRS(opt, neg, val1, val2) \
      if ((neg) && \
      (cilen = p[1]) == CILEN_ADDRS && \
      len >= cilen && \
      p[0] == opt) { \
      u32_t l; \
      len -= cilen; \
      INCPTR(2, p); \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      /* Check rejected value. */ \
      if (cilong != val1) \
          goto bad; \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      /* Check rejected value. */ \
      if (cilong != val2) \
          goto bad; \
      try_.old_addrs = 0; \
      }
  
  #if VJ_SUPPORT
  #define REJCIVJ(opt, neg, val, old, maxslot, cflag) \
      if (go->neg && \
      p[1] == (old? CILEN_COMPRESS : CILEN_VJ) && \
      len >= p[1] && \
      p[0] == opt) { \
      len -= p[1]; \
      INCPTR(2, p); \
      GETSHORT(cishort, p); \
      /* Check rejected value. */  \
      if (cishort != val) \
          goto bad; \
      if (!old) { \
         GETCHAR(cimaxslotindex, p); \
         if (cimaxslotindex != maxslot) \
           goto bad; \
         GETCHAR(ciflag, p); \
         if (ciflag != cflag) \
           goto bad; \
          } \
      try_.neg = 0; \
       }
  #endif /* VJ_SUPPORT */
  
  #define REJCIADDR(opt, neg, val) \
      if (go->neg && \
      (cilen = p[1]) == CILEN_ADDR && \
      len >= cilen && \
      p[0] == opt) { \
      u32_t l; \
      len -= cilen; \
      INCPTR(2, p); \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      /* Check rejected value. */ \
      if (cilong != val) \
          goto bad; \
      try_.neg = 0; \
      }
  
  #if LWIP_DNS
  #define REJCIDNS(opt, neg, dnsaddr) \
      if (go->neg && \
      ((cilen = p[1]) == CILEN_ADDR) && \
      len >= cilen && \
      p[0] == opt) { \
      u32_t l; \
      len -= cilen; \
      INCPTR(2, p); \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      /* Check rejected value. */ \
      if (cilong != dnsaddr) \
          goto bad; \
      try_.neg = 0; \
      }
  #endif /* LWIP_DNS */
  
  #if 0 /* UNUSED - WINS */
  #define REJCIWINS(opt, addr) \
      if (addr && \
      ((cilen = p[1]) == CILEN_ADDR) && \
      len >= cilen && \
      p[0] == opt) { \
      u32_t l; \
      len -= cilen; \
      INCPTR(2, p); \
      GETLONG(l, p); \
      cilong = lwip_htonl(l); \
      /* Check rejected value. */ \
      if (cilong != addr) \
          goto bad; \
      try_.winsaddr[opt == CI_MS_WINS2] = 0; \
      }
  #endif /* UNUSED - WINS */
  
      REJCIADDRS(CI_ADDRS, !go->neg_addr && go->old_addrs,
             go->ouraddr, go->hisaddr);
  
  #if VJ_SUPPORT
      REJCIVJ(CI_COMPRESSTYPE, neg_vj, go->vj_protocol, go->old_vj,
          go->maxslotindex, go->cflag);
  #endif /* VJ_SUPPORT */
  
      REJCIADDR(CI_ADDR, neg_addr, go->ouraddr);
  
  #if LWIP_DNS
      REJCIDNS(CI_MS_DNS1, req_dns1, go->dnsaddr[0]);
  
      REJCIDNS(CI_MS_DNS2, req_dns2, go->dnsaddr[1]);
  #endif /* LWIP_DNS */
  
  #if 0 /* UNUSED - WINS */
      REJCIWINS(CI_MS_WINS1, go->winsaddr[0]);
  
      REJCIWINS(CI_MS_WINS2, go->winsaddr[1]);
  #endif /* UNUSED - WINS */
  
      /*
       * If there are any remaining CIs, then this packet is bad.
       */
      if (len != 0)
      goto bad;
      /*
       * Now we can update state.
       */
      if (f->state != PPP_FSM_OPENED)
      *go = try_;
      return 1;
  
  bad:
      IPCPDEBUG(("ipcp_rejci: received bad Reject!"));
      return 0;
  }
  
  
  /*
   * ipcp_reqci - Check the peer's requested CIs and send appropriate response.
   * Callback from fsm_rconfreq, Receive Configure Request
   *
   * 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.
   *
   * inp = Requested CIs
   * len = Length of requested CIs
   */
  static int ipcp_reqci(fsm *f, u_char *inp, int *len, int reject_if_disagree) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *wo = &pcb->ipcp_wantoptions;
      ipcp_options *ho = &pcb->ipcp_hisoptions;
      ipcp_options *ao = &pcb->ipcp_allowoptions;
      u_char *cip, *next;        /* Pointer to current and next CIs */
      u_short cilen, citype;    /* Parsed len, type */
  #if VJ_SUPPORT
      u_short cishort;        /* Parsed short value */
  #endif /* VJ_SUPPORT */
      u32_t tl, ciaddr1, ciaddr2;/* Parsed address values */
      int rc = CONFACK;        /* Final packet return code */
      int orc;            /* Individual option return code */
      u_char *p;            /* Pointer to next char to parse */
      u_char *ucp = inp;        /* Pointer to current output char */
      int l = *len;        /* Length left */
  #if VJ_SUPPORT
      u_char maxslotindex, cflag;
  #endif /* VJ_SUPPORT */
  #if LWIP_DNS
      int d;
  #endif /* LWIP_DNS */
  
      /*
       * Reset all his options.
       */
      BZERO(ho, sizeof(*ho));
      
      /*
       * Process all his options.
       */
      next = 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? */
          IPCPDEBUG(("ipcp_reqci: bad CI length!"));
          orc = CONFREJ;        /* Reject bad CI */
          cilen = l;            /* Reject till end of packet */
          l = 0;            /* Don't loop again */
          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_ADDRS:
          if (!ao->old_addrs || ho->neg_addr ||
          cilen != CILEN_ADDRS) {    /* Check CI length */
          orc = CONFREJ;        /* Reject CI */
          break;
          }
  
          /*
           * If he has no address, or if we both have his address but
           * disagree about it, then NAK it with our idea.
           * In particular, if we don't know his address, but he does,
           * then accept it.
           */
          GETLONG(tl, p);        /* Parse source address (his) */
          ciaddr1 = lwip_htonl(tl);
          if (ciaddr1 != wo->hisaddr
          && (ciaddr1 == 0 || !wo->accept_remote)) {
          orc = CONFNAK;
          if (!reject_if_disagree) {
              DECPTR(sizeof(u32_t), p);
              tl = lwip_ntohl(wo->hisaddr);
              PUTLONG(tl, p);
          }
          } else if (ciaddr1 == 0 && wo->hisaddr == 0) {
          /*
           * If neither we nor he knows his address, reject the option.
           */
          orc = CONFREJ;
          wo->req_addr = 0;    /* don't NAK with 0.0.0.0 later */
          break;
          }
  
          /*
           * If he doesn't know our address, or if we both have our address
           * but disagree about it, then NAK it with our idea.
           */
          GETLONG(tl, p);        /* Parse desination address (ours) */
          ciaddr2 = lwip_htonl(tl);
          if (ciaddr2 != wo->ouraddr) {
          if (ciaddr2 == 0 || !wo->accept_local) {
              orc = CONFNAK;
              if (!reject_if_disagree) {
              DECPTR(sizeof(u32_t), p);
              tl = lwip_ntohl(wo->ouraddr);
              PUTLONG(tl, p);
              }
          } else {
              wo->ouraddr = ciaddr2;    /* accept peer's idea */
          }
          }
  
          ho->old_addrs = 1;
          ho->hisaddr = ciaddr1;
          ho->ouraddr = ciaddr2;
          break;
  
      case CI_ADDR:
          if (!ao->neg_addr || ho->old_addrs ||
          cilen != CILEN_ADDR) {    /* Check CI length */
          orc = CONFREJ;        /* Reject CI */
          break;
          }
  
          /*
           * If he has no address, or if we both have his address but
           * disagree about it, then NAK it with our idea.
           * In particular, if we don't know his address, but he does,
           * then accept it.
           */
          GETLONG(tl, p);    /* Parse source address (his) */
          ciaddr1 = lwip_htonl(tl);
          if (ciaddr1 != wo->hisaddr
          && (ciaddr1 == 0 || !wo->accept_remote)) {
          orc = CONFNAK;
          if (!reject_if_disagree) {
              DECPTR(sizeof(u32_t), p);
              tl = lwip_ntohl(wo->hisaddr);
              PUTLONG(tl, p);
          }
          } else if (ciaddr1 == 0 && wo->hisaddr == 0) {
          /*
           * Don't ACK an address of 0.0.0.0 - reject it instead.
           */
          orc = CONFREJ;
          wo->req_addr = 0;    /* don't NAK with 0.0.0.0 later */
          break;
          }
      
          ho->neg_addr = 1;
          ho->hisaddr = ciaddr1;
          break;
  
  #if LWIP_DNS
      case CI_MS_DNS1:
      case CI_MS_DNS2:
          /* Microsoft primary or secondary DNS request */
          d = citype == CI_MS_DNS2;
  
          /* If we do not have a DNS address then we cannot send it */
          if (ao->dnsaddr[d] == 0 ||
          cilen != CILEN_ADDR) {    /* Check CI length */
          orc = CONFREJ;        /* Reject CI */
          break;
          }
          GETLONG(tl, p);
          if (lwip_htonl(tl) != ao->dnsaddr[d]) {
                  DECPTR(sizeof(u32_t), p);
          tl = lwip_ntohl(ao->dnsaddr[d]);
          PUTLONG(tl, p);
          orc = CONFNAK;
              }
              break;
  #endif /* LWIP_DNS */
  
  #if 0 /* UNUSED - WINS */
      case CI_MS_WINS1:
      case CI_MS_WINS2:
          /* Microsoft primary or secondary WINS request */
          d = citype == CI_MS_WINS2;
  
          /* If we do not have a DNS address then we cannot send it */
          if (ao->winsaddr[d] == 0 ||
          cilen != CILEN_ADDR) {    /* Check CI length */
          orc = CONFREJ;        /* Reject CI */
          break;
          }
          GETLONG(tl, p);
          if (lwip_htonl(tl) != ao->winsaddr[d]) {
                  DECPTR(sizeof(u32_t), p);
          tl = lwip_ntohl(ao->winsaddr[d]);
          PUTLONG(tl, p);
          orc = CONFNAK;
              }
              break;
  #endif /* UNUSED - WINS */
  
  #if VJ_SUPPORT
      case CI_COMPRESSTYPE:
          if (!ao->neg_vj ||
          (cilen != CILEN_VJ && cilen != CILEN_COMPRESS)) {
          orc = CONFREJ;
          break;
          }
          GETSHORT(cishort, p);
  
          if (!(cishort == IPCP_VJ_COMP ||
            (cishort == IPCP_VJ_COMP_OLD && cilen == CILEN_COMPRESS))) {
          orc = CONFREJ;
          break;
          }
  
          ho->neg_vj = 1;
          ho->vj_protocol = cishort;
          if (cilen == CILEN_VJ) {
          GETCHAR(maxslotindex, p);
          if (maxslotindex > ao->maxslotindex) { 
              orc = CONFNAK;
              if (!reject_if_disagree){
              DECPTR(1, p);
              PUTCHAR(ao->maxslotindex, p);
              }
          }
          GETCHAR(cflag, p);
          if (cflag && !ao->cflag) {
              orc = CONFNAK;
              if (!reject_if_disagree){
              DECPTR(1, p);
              PUTCHAR(wo->cflag, p);
              }
          }
          ho->maxslotindex = maxslotindex;
          ho->cflag = cflag;
          } else {
          ho->old_vj = 1;
          ho->maxslotindex = MAX_STATES - 1;
          ho->cflag = 1;
          }
          break;
  #endif /* VJ_SUPPORT */
  
      default:
          orc = CONFREJ;
          break;
      }
  endswitch:
      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? */
          orc = CONFREJ;        /* Get tough if so */
          else {
          if (rc == CONFREJ)    /* Rejecting prior CI? */
              continue;        /* Don't send this one */
          if (rc == CONFACK) {    /* Ack'd all prior CIs? */
              rc = CONFNAK;    /* Not anymore... */
              ucp = inp;        /* Backup */
          }
          }
      }
  
      if (orc == CONFREJ &&        /* Reject this CI */
          rc != CONFREJ) {        /*  but no prior ones? */
          rc = CONFREJ;
          ucp = inp;            /* Backup */
      }
  
      /* Need to move CI? */
      if (ucp != cip)
          MEMCPY(ucp, cip, cilen);    /* Move it */
  
      /* Update output pointer */
      INCPTR(cilen, ucp);
      }
  
      /*
       * If we aren't rejecting this packet, and we want to negotiate
       * their address, and they didn't send their address, then we
       * send a NAK with a CI_ADDR option appended.  We assume the
       * input buffer is long enough that we can append the extra
       * option safely.
       */
      if (rc != CONFREJ && !ho->neg_addr && !ho->old_addrs &&
      wo->req_addr && !reject_if_disagree && !pcb->settings.noremoteip) {
      if (rc == CONFACK) {
          rc = CONFNAK;
          ucp = inp;            /* reset pointer */
          wo->req_addr = 0;        /* don't ask again */
      }
      PUTCHAR(CI_ADDR, ucp);
      PUTCHAR(CILEN_ADDR, ucp);
      tl = lwip_ntohl(wo->hisaddr);
      PUTLONG(tl, ucp);
      }
  
      *len = ucp - inp;            /* Compute output length */
      IPCPDEBUG(("ipcp: returning Configure-%s", CODENAME(rc)));
      return (rc);            /* Return final code */
  }
  
  
  #if 0 /* UNUSED */
  /*
   * ip_check_options - check that any IP-related options are OK,
   * and assign appropriate defaults.
   */
  static void
  ip_check_options()
  {
      struct hostent *hp;
      u32_t local;
      ipcp_options *wo = &ipcp_wantoptions[0];
  
      /*
       * Default our local IP address based on our hostname.
       * If local IP address already given, don't bother.
       */
      if (wo->ouraddr == 0 && !disable_defaultip) {
      /*
       * Look up our hostname (possibly with domain name appended)
       * and take the first IP address as our local IP address.
       * If there isn't an IP address for our hostname, too bad.
       */
      wo->accept_local = 1;    /* don't insist on this default value */
      if ((hp = gethostbyname(hostname)) != NULL) {
          local = *(u32_t *)hp->h_addr;
          if (local != 0 && !bad_ip_adrs(local))
          wo->ouraddr = local;
      }
      }
      ask_for_local = wo->ouraddr != 0 || !disable_defaultip;
  }
  #endif /* UNUSED */
  
  #if DEMAND_SUPPORT
  /*
   * ip_demand_conf - configure the interface as though
   * IPCP were up, for use with dial-on-demand.
   */
  static int
  ip_demand_conf(u)
      int u;
  {
      ppp_pcb *pcb = &ppp_pcb_list[u];
      ipcp_options *wo = &ipcp_wantoptions[u];
  
      if (wo->hisaddr == 0 && !pcb->settings.noremoteip) {
      /* make up an arbitrary address for the peer */
      wo->hisaddr = lwip_htonl(0x0a707070 + ifunit);
      wo->accept_remote = 1;
      }
      if (wo->ouraddr == 0) {
      /* make up an arbitrary address for us */
      wo->ouraddr = lwip_htonl(0x0a404040 + ifunit);
      wo->accept_local = 1;
      ask_for_local = 0;    /* don't tell the peer this address */
      }
      if (!sifaddr(pcb, wo->ouraddr, wo->hisaddr, get_mask(wo->ouraddr)))
      return 0;
      if (!sifup(pcb))
      return 0;
      if (!sifnpmode(pcb, PPP_IP, NPMODE_QUEUE))
      return 0;
  #if 0 /* UNUSED */
      if (wo->default_route)
      if (sifdefaultroute(pcb, wo->ouraddr, wo->hisaddr,
          wo->replace_default_route))
          default_route_set[u] = 1;
  #endif /* UNUSED */
  #if 0 /* UNUSED - PROXY ARP */
      if (wo->proxy_arp)
      if (sifproxyarp(pcb, wo->hisaddr))
          proxy_arp_set[u] = 1;
  #endif /* UNUSED - PROXY ARP */
  
      ppp_notice("local  IP address %I", wo->ouraddr);
      if (wo->hisaddr)
      ppp_notice("remote IP address %I", wo->hisaddr);
  
      return 1;
  }
  #endif /* DEMAND_SUPPORT */
  
  /*
   * ipcp_up - IPCP has come UP.
   *
   * Configure the IP network interface appropriately and bring it up.
   */
  static void ipcp_up(fsm *f) {
      ppp_pcb *pcb = f->pcb;
      u32_t mask;
      ipcp_options *ho = &pcb->ipcp_hisoptions;
      ipcp_options *go = &pcb->ipcp_gotoptions;
      ipcp_options *wo = &pcb->ipcp_wantoptions;
  
      IPCPDEBUG(("ipcp: up"));
  
      /*
       * We must have a non-zero IP address for both ends of the link.
       */
      if (!ho->neg_addr && !ho->old_addrs)
      ho->hisaddr = wo->hisaddr;
  
      if (!(go->neg_addr || go->old_addrs) && (wo->neg_addr || wo->old_addrs)
      && wo->ouraddr != 0) {
      ppp_error("Peer refused to agree to our IP address");
      ipcp_close(f->pcb, "Refused our IP address");
      return;
      }
      if (go->ouraddr == 0) {
      ppp_error("Could not determine local IP address");
      ipcp_close(f->pcb, "Could not determine local IP address");
      return;
      }
      if (ho->hisaddr == 0 && !pcb->settings.noremoteip) {
      ho->hisaddr = lwip_htonl(0x0a404040);
      ppp_warn("Could not determine remote IP address: defaulting to %I",
           ho->hisaddr);
      }
  #if 0 /* UNUSED */
      script_setenv("IPLOCAL", ip_ntoa(go->ouraddr), 0);
      if (ho->hisaddr != 0)
      script_setenv("IPREMOTE", ip_ntoa(ho->hisaddr), 1);
  #endif /* UNUSED */
  
  #if LWIP_DNS
      if (!go->req_dns1)
          go->dnsaddr[0] = 0;
      if (!go->req_dns2)
          go->dnsaddr[1] = 0;
  #if 0 /* UNUSED */
      if (go->dnsaddr[0])
      script_setenv("DNS1", ip_ntoa(go->dnsaddr[0]), 0);
      if (go->dnsaddr[1])
      script_setenv("DNS2", ip_ntoa(go->dnsaddr[1]), 0);
  #endif /* UNUSED */
      if (pcb->settings.usepeerdns && (go->dnsaddr[0] || go->dnsaddr[1])) {
      sdns(pcb, go->dnsaddr[0], go->dnsaddr[1]);
  #if 0 /* UNUSED */
      script_setenv("USEPEERDNS", "1", 0);
      create_resolv(go->dnsaddr[0], go->dnsaddr[1]);
  #endif /* UNUSED */
      }
  #endif /* LWIP_DNS */
  
      /*
       * Check that the peer is allowed to use the IP address it wants.
       */
      if (ho->hisaddr != 0) {
      u32_t addr = lwip_ntohl(ho->hisaddr);
      if ((addr >> IP_CLASSA_NSHIFT) == IP_LOOPBACKNET
          || IP_MULTICAST(addr) || IP_BADCLASS(addr)
          /*
           * For now, consider that PPP in server mode with peer required
           * to authenticate must provide the peer IP address, reject any
           * IP address wanted by peer different than the one we wanted.
           */
  #if PPP_SERVER && PPP_AUTH_SUPPORT
          || (pcb->settings.auth_required && wo->hisaddr != ho->hisaddr)
  #endif /* PPP_SERVER && PPP_AUTH_SUPPORT */
          ) {
          ppp_error("Peer is not authorized to use remote address %I", ho->hisaddr);
          ipcp_close(pcb, "Unauthorized remote IP address");
          return;
      }
      }
  #if 0 /* Unused */
      /* Upstream checking code */
      if (ho->hisaddr != 0 && !auth_ip_addr(f->unit, ho->hisaddr)) {
      ppp_error("Peer is not authorized to use remote address %I", ho->hisaddr);
      ipcp_close(f->unit, "Unauthorized remote IP address");
      return;
      }
  #endif /* Unused */
  
  #if VJ_SUPPORT
      /* set tcp compression */
      sifvjcomp(pcb, ho->neg_vj, ho->cflag, ho->maxslotindex);
  #endif /* VJ_SUPPORT */
  
  #if DEMAND_SUPPORT
      /*
       * If we are doing dial-on-demand, the interface is already
       * configured, so we put out any saved-up packets, then set the
       * interface to pass IP packets.
       */
      if (demand) {
      if (go->ouraddr != wo->ouraddr || ho->hisaddr != wo->hisaddr) {
          ipcp_clear_addrs(f->unit, wo->ouraddr, wo->hisaddr,
                        wo->replace_default_route);
          if (go->ouraddr != wo->ouraddr) {
          ppp_warn("Local IP address changed to %I", go->ouraddr);
          script_setenv("OLDIPLOCAL", ip_ntoa(wo->ouraddr), 0);
          wo->ouraddr = go->ouraddr;
          } else
          script_unsetenv("OLDIPLOCAL");
          if (ho->hisaddr != wo->hisaddr && wo->hisaddr != 0) {
          ppp_warn("Remote IP address changed to %I", ho->hisaddr);
          script_setenv("OLDIPREMOTE", ip_ntoa(wo->hisaddr), 0);
          wo->hisaddr = ho->hisaddr;
          } else
          script_unsetenv("OLDIPREMOTE");
  
          /* Set the interface to the new addresses */
          mask = get_mask(go->ouraddr);
          if (!sifaddr(pcb, go->ouraddr, ho->hisaddr, mask)) {
  #if PPP_DEBUG
          ppp_warn("Interface configuration failed");
  #endif /* PPP_DEBUG */
          ipcp_close(f->unit, "Interface configuration failed");
          return;
          }
  
          /* assign a default route through the interface if required */
          if (ipcp_wantoptions[f->unit].default_route) 
          if (sifdefaultroute(pcb, go->ouraddr, ho->hisaddr,
              wo->replace_default_route))
              default_route_set[f->unit] = 1;
  
  #if 0 /* UNUSED - PROXY ARP */
          /* Make a proxy ARP entry if requested. */
          if (ho->hisaddr != 0 && ipcp_wantoptions[f->unit].proxy_arp)
          if (sifproxyarp(pcb, ho->hisaddr))
              proxy_arp_set[f->unit] = 1;
  #endif /* UNUSED - PROXY ARP */
  
      }
      demand_rexmit(PPP_IP,go->ouraddr);
      sifnpmode(pcb, PPP_IP, NPMODE_PASS);
  
      } else
  #endif /* DEMAND_SUPPORT */
      {
      /*
       * Set IP addresses and (if specified) netmask.
       */
      mask = get_mask(go->ouraddr);
  
  #if !(defined(SVR4) && (defined(SNI) || defined(__USLC__)))
      if (!sifaddr(pcb, go->ouraddr, ho->hisaddr, mask)) {
  #if PPP_DEBUG
          ppp_warn("Interface configuration failed");
  #endif /* PPP_DEBUG */
          ipcp_close(f->pcb, "Interface configuration failed");
          return;
      }
  #endif
  
      /* bring the interface up for IP */
      if (!sifup(pcb)) {
  #if PPP_DEBUG
          ppp_warn("Interface failed to come up");
  #endif /* PPP_DEBUG */
          ipcp_close(f->pcb, "Interface configuration failed");
          return;
      }
  
  #if (defined(SVR4) && (defined(SNI) || defined(__USLC__)))
      if (!sifaddr(pcb, go->ouraddr, ho->hisaddr, mask)) {
  #if PPP_DEBUG
          ppp_warn("Interface configuration failed");
  #endif /* PPP_DEBUG */
          ipcp_close(f->unit, "Interface configuration failed");
          return;
      }
  #endif
  #if DEMAND_SUPPORT
      sifnpmode(pcb, PPP_IP, NPMODE_PASS);
  #endif /* DEMAND_SUPPORT */
  
  #if 0 /* UNUSED */
      /* assign a default route through the interface if required */
      if (wo->default_route)
          if (sifdefaultroute(pcb, go->ouraddr, ho->hisaddr,
              wo->replace_default_route))
              pcb->default_route_set = 1;
  #endif /* UNUSED */
  
  #if 0 /* UNUSED - PROXY ARP */
      /* Make a proxy ARP entry if requested. */
      if (ho->hisaddr != 0 && wo->proxy_arp)
          if (sifproxyarp(pcb, ho->hisaddr))
          pcb->proxy_arp_set = 1;
  #endif /* UNUSED - PROXY ARP */
  
      wo->ouraddr = go->ouraddr;
  
      ppp_notice("local  IP address %I", go->ouraddr);
      if (ho->hisaddr != 0)
          ppp_notice("remote IP address %I", ho->hisaddr);
  #if LWIP_DNS
      if (go->dnsaddr[0])
          ppp_notice("primary   DNS address %I", go->dnsaddr[0]);
      if (go->dnsaddr[1])
          ppp_notice("secondary DNS address %I", go->dnsaddr[1]);
  #endif /* LWIP_DNS */
      }
  
  #if PPP_STATS_SUPPORT
      reset_link_stats(f->unit);
  #endif /* PPP_STATS_SUPPORT */
  
      np_up(pcb, PPP_IP);
      pcb->ipcp_is_up = 1;
  
  #if PPP_NOTIFY
      notify(ip_up_notifier, 0);
  #endif /* PPP_NOTIFY */
  #if 0 /* UNUSED */
      if (ip_up_hook)
      ip_up_hook();
  #endif /* UNUSED */
  }
  
  
  /*
   * ipcp_down - IPCP has gone DOWN.
   *
   * Take the IP network interface down, clear its addresses
   * and delete routes through it.
   */
  static void ipcp_down(fsm *f) {
      ppp_pcb *pcb = f->pcb;
      ipcp_options *ho = &pcb->ipcp_hisoptions;
      ipcp_options *go = &pcb->ipcp_gotoptions;
  
      IPCPDEBUG(("ipcp: down"));
  #if PPP_STATS_SUPPORT
      /* XXX a bit IPv4-centric here, we only need to get the stats
       * before the interface is marked down. */
      /* XXX more correct: we must get the stats before running the notifiers,
       * at least for the radius plugin */
      update_link_stats(f->unit);
  #endif /* PPP_STATS_SUPPORT */
  #if PPP_NOTIFY
      notify(ip_down_notifier, 0);
  #endif /* PPP_NOTIFY */
  #if 0 /* UNUSED */
      if (ip_down_hook)
      ip_down_hook();
  #endif /* UNUSED */
      if (pcb->ipcp_is_up) {
      pcb->ipcp_is_up = 0;
      np_down(pcb, PPP_IP);
      }
  #if VJ_SUPPORT
      sifvjcomp(pcb, 0, 0, 0);
  #endif /* VJ_SUPPORT */
  
  #if PPP_STATS_SUPPORT
      print_link_stats(); /* _after_ running the notifiers and ip_down_hook(),
               * because print_link_stats() sets link_stats_valid
               * to 0 (zero) */
  #endif /* PPP_STATS_SUPPORT */
  
  #if DEMAND_SUPPORT
      /*
       * If we are doing dial-on-demand, set the interface
       * to queue up outgoing packets (for now).
       */
      if (demand) {
      sifnpmode(pcb, PPP_IP, NPMODE_QUEUE);
      } else
  #endif /* DEMAND_SUPPORT */
      {
  #if DEMAND_SUPPORT
      sifnpmode(pcb, PPP_IP, NPMODE_DROP);
  #endif /* DEMAND_SUPPORT */
      sifdown(pcb);
      ipcp_clear_addrs(pcb, go->ouraddr,
               ho->hisaddr, 0);
  #if LWIP_DNS
      cdns(pcb, go->dnsaddr[0], go->dnsaddr[1]);
  #endif /* LWIP_DNS */
      }
  }
  
  
  /*
   * ipcp_clear_addrs() - clear the interface addresses, routes,
   * proxy arp entries, etc.
   */
  static void ipcp_clear_addrs(ppp_pcb *pcb, u32_t ouraddr, u32_t hisaddr, u8_t replacedefaultroute) {
      LWIP_UNUSED_ARG(replacedefaultroute);
  
  #if 0 /* UNUSED - PROXY ARP */
      if (pcb->proxy_arp_set) {
      cifproxyarp(pcb, hisaddr);
      pcb->proxy_arp_set = 0;
      }
  #endif /* UNUSED - PROXY ARP */
  #if 0 /* UNUSED */
      /* If replacedefaultroute, sifdefaultroute will be called soon
       * with replacedefaultroute set and that will overwrite the current
       * default route. This is the case only when doing demand, otherwise
       * during demand, this cifdefaultroute would restore the old default
       * route which is not what we want in this case. In the non-demand
       * case, we'll delete the default route and restore the old if there
       * is one saved by an sifdefaultroute with replacedefaultroute.
       */
      if (!replacedefaultroute && pcb->default_route_set) {
      cifdefaultroute(pcb, ouraddr, hisaddr);
      pcb->default_route_set = 0;
      }
  #endif /* UNUSED */
      cifaddr(pcb, ouraddr, hisaddr);
  }
  
  
  /*
   * ipcp_finished - possibly shut down the lower layers.
   */
  static void ipcp_finished(fsm *f) {
      ppp_pcb *pcb = f->pcb;
      if (pcb->ipcp_is_open) {
          pcb->ipcp_is_open = 0;
          np_finished(pcb, PPP_IP);
      }
  }
  
  
  #if 0 /* UNUSED */
  /*
   * create_resolv - create the replacement resolv.conf file
   */
  static void
  create_resolv(peerdns1, peerdns2)
      u32_t peerdns1, peerdns2;
  {
  
  }
  #endif /* UNUSED */
  
  #if PRINTPKT_SUPPORT
  /*
   * ipcp_printpkt - print the contents of an IPCP packet.
   */
  static const char* const ipcp_codenames[] = {
      "ConfReq", "ConfAck", "ConfNak", "ConfRej",
      "TermReq", "TermAck", "CodeRej"
  };
  
  static int ipcp_printpkt(const u_char *p, int plen,
          void (*printer) (void *, const char *, ...), void *arg) {
      int code, id, len, olen;
      const u_char *pstart, *optend;
  #if VJ_SUPPORT
      u_short cishort;
  #endif /* VJ_SUPPORT */
      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 <= (int)LWIP_ARRAYSIZE(ipcp_codenames))
      printer(arg, " %s", ipcp_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_ADDRS:
          if (olen == CILEN_ADDRS) {
              p += 2;
              GETLONG(cilong, p);
              printer(arg, "addrs %I", lwip_htonl(cilong));
              GETLONG(cilong, p);
              printer(arg, " %I", lwip_htonl(cilong));
          }
          break;
  #if VJ_SUPPORT
          case CI_COMPRESSTYPE:
          if (olen >= CILEN_COMPRESS) {
              p += 2;
              GETSHORT(cishort, p);
              printer(arg, "compress ");
              switch (cishort) {
              case IPCP_VJ_COMP:
              printer(arg, "VJ");
              break;
              case IPCP_VJ_COMP_OLD:
              printer(arg, "old-VJ");
              break;
              default:
              printer(arg, "0x%x", cishort);
              }
          }
          break;
  #endif /* VJ_SUPPORT */
          case CI_ADDR:
          if (olen == CILEN_ADDR) {
              p += 2;
              GETLONG(cilong, p);
              printer(arg, "addr %I", lwip_htonl(cilong));
          }
          break;
  #if LWIP_DNS
          case CI_MS_DNS1:
          case CI_MS_DNS2:
              p += 2;
          GETLONG(cilong, p);
          printer(arg, "ms-dns%d %I", (code == CI_MS_DNS1? 1: 2),
              htonl(cilong));
          break;
  #endif /* LWIP_DNS */
  #if 0 /* UNUSED - WINS */
          case CI_MS_WINS1:
          case CI_MS_WINS2:
              p += 2;
          GETLONG(cilong, p);
          printer(arg, "ms-wins %I", lwip_htonl(cilong));
          break;
  #endif /* UNUSED - WINS */
          default:
          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, " ");
          ppp_print_string(p, len, printer, arg);
          p += len;
          len = 0;
      }
      break;
      default:
      break;
      }
  
      /* print the rest of the bytes in the packet */
      for (; len > 0; --len) {
      GETCHAR(code, p);
      printer(arg, " %.2x", code);
      }
  
      return p - pstart;
  }
  #endif /* PRINTPKT_SUPPORT */
  
  #if DEMAND_SUPPORT
  /*
   * ip_active_pkt - see if this IP packet is worth bringing the link up for.
   * We don't bring the link up for IP fragments or for TCP FIN packets
   * with no data.
   */
  #define IP_HDRLEN    20    /* bytes */
  #define IP_OFFMASK    0x1fff
  #ifndef IPPROTO_TCP
  #define IPPROTO_TCP    6
  #endif
  #define TCP_HDRLEN    20
  #define TH_FIN        0x01
  
  /*
   * We use these macros because the IP header may be at an odd address,
   * and some compilers might use word loads to get th_off or ip_hl.
   */
  
  #define net_short(x)    (((x)[0] << 8) + (x)[1])
  #define get_iphl(x)    (((unsigned char *)(x))[0] & 0xF)
  #define get_ipoff(x)    net_short((unsigned char *)(x) + 6)
  #define get_ipproto(x)    (((unsigned char *)(x))[9])
  #define get_tcpoff(x)    (((unsigned char *)(x))[12] >> 4)
  #define get_tcpflags(x)    (((unsigned char *)(x))[13])
  
  static int
  ip_active_pkt(pkt, len)
      u_char *pkt;
      int len;
  {
      u_char *tcp;
      int hlen;
  
      len -= PPP_HDRLEN;
      pkt += PPP_HDRLEN;
      if (len < IP_HDRLEN)
      return 0;
      if ((get_ipoff(pkt) & IP_OFFMASK) != 0)
      return 0;
      if (get_ipproto(pkt) != IPPROTO_TCP)
      return 1;
      hlen = get_iphl(pkt) * 4;
      if (len < hlen + TCP_HDRLEN)
      return 0;
      tcp = pkt + hlen;
      if ((get_tcpflags(tcp) & TH_FIN) != 0 && len == hlen + get_tcpoff(tcp) * 4)
      return 0;
      return 1;
  }
  #endif /* DEMAND_SUPPORT */
  
  #endif /* PPP_SUPPORT && PPP_IPV4_SUPPORT */
  