xref: /illumos-gate/usr/src/cmd/cmd-inet/usr.bin/pppd/ipcp.c (revision 4f62a657)

/*
 * ipcp.c - PPP IP Control Protocol.
 *
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * 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.
 */
/*
 * Copyright (c) 2016 by Delphix. All rights reserved.
 */

#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#if defined(_linux_) || defined(__linux__)
#define	__FAVOR_BSD
#endif
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>

#include "pppd.h"
#include "fsm.h"
#include "ipcp.h"
#include "pathnames.h"

/* global vars */
ipcp_options ipcp_wantoptions[NUM_PPP];	/* Options that we want to request */
ipcp_options ipcp_gotoptions[NUM_PPP];	/* Options that peer ack'd */
ipcp_options ipcp_allowoptions[NUM_PPP]; /* Options we allow peer to request */
ipcp_options ipcp_hisoptions[NUM_PPP];	/* Options that we ack'd */

bool	ipcp_from_hostname = 0;	/* Local IP address is from hostname lookup */

/* Hook for a plugin to know when IP protocol has come up */
void (*ip_up_hook) __P((void)) = NULL;

/* Hook for a plugin to know when IP protocol has come down */
void (*ip_down_hook) __P((void)) = NULL;

/* local vars */
static bool default_route_set[NUM_PPP];	/* Have set up a default route */
static bool proxy_arp_set[NUM_PPP];	/* Have created proxy arp entry */
static bool ipcp_is_up[NUM_PPP];	/* have called np_up() */
static bool proxy_arp_quiet[NUM_PPP];	/* We should be quiet on error */
static bool disable_defaultip = 0;	/* Don't use hostname for IP addr */

/*
 * Callbacks for fsm code.  (CI = Configuration Information)
 */
static void ipcp_resetci __P((fsm *));	/* Reset our CI */
static int  ipcp_cilen __P((fsm *));	        /* Return length of our CI */
static void ipcp_addci __P((fsm *, u_char *, int *)); /* Add our CI */
static int  ipcp_ackci __P((fsm *, u_char *, int));	/* Peer ack'd our CI */
static int  ipcp_nakci __P((fsm *, u_char *, int));	/* Peer nak'd our CI */
static int  ipcp_rejci __P((fsm *, u_char *, int));	/* Peer rej'd our CI */
static int  ipcp_reqci __P((fsm *, u_char *, int *, int)); /* Rcv CI */
static void ipcp_up __P((fsm *));		/* We're UP */
static void ipcp_down __P((fsm *));		/* We're DOWN */
static void ipcp_finished __P((fsm *));	/* Don't need lower layer */
static int  setmsservaddr __P((char *, u_int32_t *));

fsm ipcp_fsm[NUM_PPP];		/* IPCP fsm structure */

static 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,			/* Retransmission is necessary */
    NULL,			/* Called to handle protocol-specific codes */
    "IPCP",			/* String name of protocol */
    NULL			/* Peer rejected a code number */
};

/*
 * Command-line options.
 */
static int setvjslots __P((char **));
static int setdnsaddr __P((char **));
static int setwinsaddr __P((char **));
static int autoproxyarp __P((char **));

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" },
    { "novj", o_bool, &ipcp_wantoptions[0].neg_vj,
      "Disable VJ compression", OPT_A2COPY, &ipcp_allowoptions[0].neg_vj },
    { "-vj", o_bool, &ipcp_wantoptions[0].neg_vj,
      "Disable VJ compression", OPT_A2COPY, &ipcp_allowoptions[0].neg_vj },
    { "novjccomp", o_bool, &ipcp_wantoptions[0].cflag,
      "Disable VJ connection-ID compression", OPT_A2COPY,
      &ipcp_allowoptions[0].cflag },
    { "-vjccomp", o_bool, &ipcp_wantoptions[0].cflag,
      "Disable VJ connection-ID compression", OPT_A2COPY,
      &ipcp_allowoptions[0].cflag },
    { "vj-max-slots", o_special, (void *)setvjslots,
      "Set maximum VJ header slots" },
    { "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" },
    { "noipdefault", o_bool, &disable_defaultip,
      "Don't use name for default IP adrs", 1 },
    { "ms-dns", o_special, (void *)setdnsaddr,
      "DNS address for the peer's use" },
    { "ms-wins", o_special, (void *)setwinsaddr,
      "Nameserver for SMB over TCP/IP for peer" },
    { "ipcp-restart", o_int, &ipcp_fsm[0].timeouttime,
      "Set timeout for IPCP" },
    { "ipcp-max-terminate", o_int, &ipcp_fsm[0].maxtermtransmits,
      "Set max #xmits for term-reqs" },
    { "ipcp-max-configure", o_int, &ipcp_fsm[0].maxconfreqtransmits,
      "Set max #xmits for conf-reqs" },
    { "ipcp-max-failure", o_int, &ipcp_fsm[0].maxnakloops,
      "Set max #conf-naks for IPCP" },
    { "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_A2COPY,
      &ipcp_wantoptions[0].default_route },
    { "-defaultroute", o_bool, &ipcp_allowoptions[0].default_route,
      "disable defaultroute option", OPT_A2COPY,
      &ipcp_wantoptions[0].default_route },
    { "proxyarp", o_bool, &ipcp_wantoptions[0].proxy_arp,
      "Add proxy ARP entry", OPT_ENABLE|1, &ipcp_allowoptions[0].proxy_arp },
    { "autoproxyarp", o_special_noarg, (void *)autoproxyarp,
      "Add proxy ARP entry if needed", OPT_ENABLE,
      &ipcp_allowoptions[0].proxy_arp },
    { "noproxyarp", o_bool, &ipcp_allowoptions[0].proxy_arp,
      "disable proxyarp option", OPT_A2COPY, &ipcp_wantoptions[0].proxy_arp },
    { "-proxyarp", o_bool, &ipcp_allowoptions[0].proxy_arp,
      "disable proxyarp option", OPT_A2COPY, &ipcp_wantoptions[0].proxy_arp },
    { "usepeerdns", o_bool, &ipcp_wantoptions[0].req_dns1,
      "Ask peer for DNS address(es)", OPT_A2COPY|1,
      &ipcp_wantoptions[0].req_dns2 },
    { NULL }
};

/*
 * Protocol entry points from main code.
 */
static void ipcp_init __P((int));
static void ipcp_open __P((int));
static void ipcp_close __P((int, char *));
static void ipcp_lowerup __P((int));
static void ipcp_lowerdown __P((int));
static void ipcp_input __P((int, u_char *, int));
static void ipcp_protrej __P((int));
static int  ipcp_printpkt __P((u_char *, int,
    void (*) __P((void *, const char *, ...)), void *));
static void ip_check_options __P((void));
static int  ip_demand_conf __P((int));
static int  ip_active_pkt __P((u_char *, int));
static void ipcp_print_stat __P((int, FILE *));

static void create_resolv __P((u_int32_t, u_int32_t));

struct protent ipcp_protent = {
    PPP_IPCP,
    ipcp_init,
    ipcp_input,
    ipcp_protrej,
    ipcp_lowerup,
    ipcp_lowerdown,
    ipcp_open,
    ipcp_close,
    ipcp_printpkt,
    NULL,
    1,
    "IPCP",
    "IP",
    ipcp_option_list,
    ip_check_options,
    ip_demand_conf,
    ip_active_pkt,
    ipcp_print_stat
};

static void ipcp_clear_addrs __P((int, u_int32_t, u_int32_t));
static void ipcp_script __P((char *));		/* Run an up/down script */
static void ipcp_script_done __P((void *, int));

/*
 * 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 */


/*
 * This state variable is used to ensure that we don't
 * run an ipcp-up/down script while one is already running.
 */
static enum script_state {
    s_down,
    s_up
} ipcp_script_state;
static pid_t ipcp_script_pid;

/*
 * Make a string representation of a network IP address.
 */
char *
ip_ntoa(ipaddr)
u_int32_t ipaddr;
{
    static char b[64];

    (void) slprintf(b, sizeof(b), "%I", ipaddr);
    return b;
}

/*
 * Option parsing.
 */

/*
 * 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;
    return 1;
}

/*
 * setmsservaddr - Set the primary and secondary server addresses in the
 * array.  setdnsaddr() and setwinsaddr() call this function with either
 * dnsaddr[] or winsaddr[] as the serverarray argument.
 */
static int
setmsservaddr(servname, serverarray)
    char *servname;
    u_int32_t *serverarray;
{
    u_int32_t addr;
    struct hostent *hp = NULL;

    addr = inet_addr(servname);
    if (addr == (u_int32_t) -1) {
	if ((hp = gethostbyname(servname)) == NULL)
	    return 0;
	BCOPY(hp->h_addr, &addr, sizeof (u_int32_t));
    }

    /*
     * If there is no primary then this is the first instance of the
     * option, we must set the primary.  In that case, try to set the
     * secondary to h_addr_list[1].  If the primary is already set, then
     * this is the second instance of the option, and we must set
     * the secondary.
     */
    if (serverarray[0] == 0) {
	serverarray[0] = addr;
	if (hp != NULL && hp->h_addr_list[1] != NULL)
	    BCOPY(hp->h_addr_list[1], &serverarray[1], sizeof (u_int32_t));
	else
	    serverarray[1] = addr;
    } else {
	serverarray[1] = addr;
    }

    return (1);
}

/*
 * setdnsaddr - set the dns address(es)
 */
static int
setdnsaddr(argv)
    char **argv;
{
    if (setmsservaddr(*argv, &(ipcp_allowoptions[0].dnsaddr[0])) == 0) {
	option_error("invalid address parameter '%s' for ms-dns option", *argv);
	return (0);
    }

    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;
{
    if (setmsservaddr(*argv, &(ipcp_allowoptions[0].winsaddr[0])) == 0) {
	option_error("invalid address parameter '%s' for ms-wins option",
	    *argv);
	return (0);
    }

    return (1);
}

/*
 * autoproxyarp -- enable proxy ARP but don't emit error messages if
 * it's not actually needed.
 */
/*ARGSUSED*/
static int
autoproxyarp(argv)
    char **argv;
{
    ipcp_wantoptions[0].proxy_arp = 1;
    proxy_arp_quiet[0] = 1;

    return (1);
}


/*
 * ipcp_init - Initialize IPCP.
 */
static void
ipcp_init(unit)
    int unit;
{
    fsm *f = &ipcp_fsm[unit];
    ipcp_options *wo = &ipcp_wantoptions[unit];
    ipcp_options *ao = &ipcp_allowoptions[unit];

    f->unit = unit;
    f->protocol = PPP_IPCP;
    f->callbacks = &ipcp_callbacks;
    fsm_init(&ipcp_fsm[unit]);

    BZERO(wo, sizeof(*wo));
    BZERO(ao, sizeof(*ao));

    wo->neg_addr = wo->old_addrs = 1;
    wo->neg_vj = 1;
    wo->vj_protocol = IPCP_VJ_COMP;
    wo->maxslotindex = MAX_STATES - 1; /* really max index */
    wo->cflag = 1;

    ao->neg_addr = ao->old_addrs = 1;
    ao->neg_vj = 1;
    ao->maxslotindex = MAX_STATES - 1;
    ao->cflag = 1;

    /*
     * These aren't actually negotiated.  Instead, they control
     * whether the user may use the proxyarp and defaultroute options.
     */
    ao->proxy_arp = 1;
    ao->default_route = 1;
    proxy_arp_quiet[unit] = 0;
}


/*
 * ipcp_open - IPCP is allowed to come up.
 */
static void
ipcp_open(unit)
    int unit;
{
    fsm_open(&ipcp_fsm[unit]);
}


/*
 * ipcp_close - Take IPCP down.
 */
static void
ipcp_close(unit, reason)
    int unit;
    char *reason;
{
    fsm_close(&ipcp_fsm[unit], reason);
}


/*
 * ipcp_lowerup - The lower layer is up.
 */
static void
ipcp_lowerup(unit)
    int unit;
{
    fsm_lowerup(&ipcp_fsm[unit]);
}


/*
 * ipcp_lowerdown - The lower layer is down.
 */
static void
ipcp_lowerdown(unit)
    int unit;
{
    fsm_lowerdown(&ipcp_fsm[unit]);
}


/*
 * ipcp_input - Input IPCP packet.
 */
static void
ipcp_input(unit, p, len)
    int unit;
    u_char *p;
    int len;
{
    fsm_input(&ipcp_fsm[unit], p, len);
}


/*
 * ipcp_protrej - A Protocol-Reject was received for IPCP.
 */
static void
ipcp_protrej(unit)
    int unit;
{
    fsm_protreject(&ipcp_fsm[unit]);
}


/*
 * ipcp_resetci - Reset our CI.
 * Called by fsm_sconfreq, Send Configure Request.
 */
static void
ipcp_resetci(f)
    fsm *f;
{
    ipcp_options *wo = &ipcp_wantoptions[f->unit];
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    ipcp_options *ao = &ipcp_allowoptions[f->unit];

    wo->req_addr = (wo->neg_addr || wo->old_addrs) &&
	(ao->neg_addr || ao->old_addrs);
    if (wo->ouraddr == 0 || disable_defaultip)
	wo->accept_local = 1;
    if (wo->hisaddr == 0)
	wo->accept_remote = 1;
    *go = *wo;
    if (disable_defaultip)
	go->ouraddr = 0;
}


/*
 * ipcp_cilen - Return length of our CI.
 * Called by fsm_sconfreq, Send Configure Request.
 */
static int
ipcp_cilen(f)
    fsm *f;
{
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    ipcp_options *wo = &ipcp_wantoptions[f->unit];
    ipcp_options *ho = &ipcp_hisoptions[f->unit];

#define LENCIADDRS(neg)		(neg ? CILEN_ADDRS : 0)
#define LENCIVJ(neg, old)	(neg ? (old? CILEN_COMPRESS : CILEN_VJ) : 0)
#define LENCIADDR(neg)		(neg ? (CILEN_ADDR) : 0)

    /*
     * 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)
	/* use the old style of address negotiation */
	go->neg_addr = 0;
    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;
	}
    }

    return (LENCIADDRS(!go->neg_addr && go->old_addrs) +
	    LENCIVJ(go->neg_vj, go->old_vj) +
	    LENCIADDR(go->neg_addr) +
	    LENCIADDR(go->req_dns1) +
	    LENCIADDR(go->req_dns2)) ;
}


/*
 * ipcp_addci - Add our desired CIs to a packet.
 * Called by fsm_sconfreq, Send Configure Request.
 */
static void
ipcp_addci(f, ucp, lenp)
    fsm *f;
    u_char *ucp;
    int *lenp;
{
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    int len = *lenp;

#define ADDCIADDRS(opt, neg, val1, val2) \
    if (neg) { \
	if (len >= CILEN_ADDRS) { \
	    PUTCHAR(opt, ucp); \
	    PUTCHAR(CILEN_ADDRS, ucp); \
	    PUTNLONG(val1, ucp); \
	    PUTNLONG(val2, ucp); \
	    len -= CILEN_ADDRS; \
	} else \
	    go->old_addrs = 0; \
    }

#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; \
    }

#define ADDCIADDR(opt, neg, val) \
    if (neg) { \
	if (len >= CILEN_ADDR) { \
	    PUTCHAR(opt, ucp); \
	    PUTCHAR(CILEN_ADDR, ucp); \
	    PUTNLONG(val, ucp); \
	    len -= CILEN_ADDR; \
	} else \
	    neg = 0; \
    }

    ADDCIADDRS(CI_ADDRS, !go->neg_addr && go->old_addrs, go->ouraddr,
	       go->hisaddr);

    ADDCIVJ(CI_COMPRESSTYPE, go->neg_vj, go->vj_protocol, go->old_vj,
	    go->maxslotindex, go->cflag);

    ADDCIADDR(CI_ADDR, go->neg_addr, go->ouraddr);

    ADDCIADDR(CI_MS_DNS1, go->req_dns1, go->dnsaddr[0]);

    ADDCIADDR(CI_MS_DNS2, go->req_dns2, go->dnsaddr[1]);

    *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(f, p, len)
    fsm *f;
    u_char *p;
    int len;
{
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    u_short cilen, citype, cishort;
    u_int32_t cilong;
    u_char cimaxslotindex, cicflag;

    /*
     * 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	ACKCHECK(opt, olen) \
	if ((len -= olen) < 0) \
	    goto bad; \
	GETCHAR(citype, p); \
	GETCHAR(cilen, p); \
	if (cilen != olen || \
	    citype != opt) \
	    goto bad;

#define ACKCIADDRS(opt, neg, val1, val2) \
    if (neg) { \
	ACKCHECK(opt, CILEN_ADDRS) \
	GETNLONG(cilong, p); \
	if (val1 != cilong) \
	    goto bad; \
	GETNLONG(cilong, p); \
	if (val2 != cilong) \
	    goto bad; \
    }

#define ACKCIVJ(opt, neg, val, old, maxslotindex, cflag) \
    if (neg) { \
	int vjlen = old? CILEN_COMPRESS : CILEN_VJ; \
	ACKCHECK(opt, vjlen) \
	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; \
	} \
    }

#define ACKCIADDR(opt, neg, val) \
    if (neg) { \
	ACKCHECK(opt, CILEN_ADDR) \
	GETNLONG(cilong, p); \
	if (val != cilong) \
	    goto bad; \
    }

    ACKCIADDRS(CI_ADDRS, !go->neg_addr && go->old_addrs, go->ouraddr,
	       go->hisaddr);

    ACKCIVJ(CI_COMPRESSTYPE, go->neg_vj, go->vj_protocol, go->old_vj,
	    go->maxslotindex, go->cflag);

    ACKCIADDR(CI_ADDR, go->neg_addr, go->ouraddr);

    ACKCIADDR(CI_MS_DNS1, go->req_dns1, go->dnsaddr[0]);

    ACKCIADDR(CI_MS_DNS2, go->req_dns2, go->dnsaddr[1]);

    /*
     * 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(f, p, len)
    fsm *f;
    u_char *p;
    int len;
{
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    u_char cimaxslotindex, cicflag;
    u_char citype, cilen, *next;
    u_short cishort;
    u_int32_t ciaddr1, ciaddr2;
    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); \
	GETNLONG(ciaddr1, p); \
	GETNLONG(ciaddr2, p); \
	no.old_addrs = 1; \
	code \
    }

#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 \
    }

#define NAKCIADDR(opt, neg, code) \
    if (go->neg && \
	(cilen = p[1]) == CILEN_ADDR && \
	len >= cilen && \
	p[0] == opt) { \
	len -= cilen; \
	INCPTR(2, p); \
	GETNLONG(ciaddr1, p); \
	no.neg = 1; \
	code \
    }

    /*
     * Accept the peer's idea of {our,its} 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 (go->accept_local && ciaddr1) { /* Do we know our address? */
		  try.ouraddr = ciaddr1;
	      }
	      if (go->accept_remote && ciaddr2) { /* Does it know its? */
		  try.hisaddr = ciaddr2;
	      }
	      );

    /*
     * 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 (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;
		}
	    }
	    );

    NAKCIADDR(CI_ADDR, neg_addr,
	      if (go->accept_local && ciaddr1) { /* Do we know our address? */
		  try.ouraddr = ciaddr1;
	      }
	      );

    NAKCIADDR(CI_MS_DNS1, req_dns1,
	      try.dnsaddr[0] = ciaddr1;
	      );

    NAKCIADDR(CI_MS_DNS2, req_dns2,
	      try.dnsaddr[1] = ciaddr1;
	      );

    /*
     * 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.
     */
    while (len > CILEN_VOID) {
	GETCHAR(citype, p);
	GETCHAR(cilen, p);
	if( (len -= cilen) < 0 )
	    goto bad;
	next = p + cilen - 2;

	switch (citype) {
	case CI_COMPRESSTYPE:
	    if (go->neg_vj || no.neg_vj ||
		(cilen != CILEN_VJ && cilen != CILEN_COMPRESS))
		goto bad;
	    no.neg_vj = 1;
	    break;
	case CI_ADDRS:
	    if ((!go->neg_addr && go->old_addrs) || no.old_addrs
		|| cilen != CILEN_ADDRS)
		goto bad;
	    try.neg_addr = 1;
	    try.old_addrs = 1;
	    GETNLONG(ciaddr1, p);
	    if (ciaddr1 && go->accept_local)
		try.ouraddr = ciaddr1;
	    GETNLONG(ciaddr2, p);
	    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;
	    GETNLONG(ciaddr1, p);
	    if (ciaddr1 && go->accept_local)
		try.ouraddr = ciaddr1;
	    if (try.ouraddr != 0)
		try.neg_addr = 1;
	    no.neg_addr = 1;
	    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 != 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(f, p, len)
    fsm *f;
    u_char *p;
    int len;
{
    ipcp_options *go = &ipcp_gotoptions[f->unit];
    u_char cimaxslotindex, ciflag, cilen;
    u_short cishort;
    u_int32_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) { \
	len -= cilen; \
	INCPTR(2, p); \
	GETNLONG(cilong, p); \
	/* Check rejected value. */ \
	if (cilong != val1) \
	    goto bad; \
	GETNLONG(cilong, p); \
	/* Check rejected value. */ \
	if (cilong != val2) \