Merge commit 'b1e7e97d3b60469b243b3b2e22c7d8cbd11c7c90'

[unleashed.git] / usr / src / cmd / mailx / optim.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1998 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */


#pragma ident   "%Z%%M% %I%     %E% SMI"

/*
 * mailx -- a modified version of a University of California at Berkeley
 *      mail program
 *
 * Network name modification routines.
 */

#include "rcv.h"
#include "configdefs.h"
#include <locale.h>

static char             *arpafix(char name[], char from[]);
static char             *lasthost(char *addr);
static char             *makeremote(char name[], char from[]);
static int              mstash(char name[], int attnet);
static int              mtype(int mid);
static int              netlook(char machine[], int attnet);
static int              nettype(int mid);
static int              ntype(register int nc);
static void             stradd(register char *str, int n, register int c);
static char             *tackon(char *sys, char *rest);
static struct xtrahash  *xlocate(char name[]);
#ifdef OPTIM
static char             best(int src, int dest);
static char             *mlook(int mid);
static int              netkind(register int nt);
static void             optiboth(char net[]);
static void             optim(char net[], char name[]);
static void             optim1(char netstr[], char name[]);
static int              optimex(char net[], char name[]);
static int              optimimp(char net[], char name[]);
static void             prefer(char name[]);
static char             *rpair(char str[], int mach);
#endif

/*
 * Map a name into the correct network "view" of the
 * name.  This is done by prepending the name with the
 * network address of the sender, then optimizing away
 * nonsense.
 */

char *
netmap(char name[], char from[])
{
        char nbuf[BUFSIZ], ret[BUFSIZ];
        register char *cp, *oname;

        if (debug) fprintf(stderr, "netmap(name '%s', from '%s')\n", name, from);
        if (strlen(from) == 0)
                return(name);   /* "from" is empty - can't do anything */

        if (strcmp(from, name) == 0)
                return(name);   /* "from" and "name" are the same, do nothing */

        /*
         * If the name contains an "@" or a "%", remove it and the host
         * following it if that host is "known".
         */
        if (any('@', name) || any('%', name))
                return(arpafix(name, from));

        /*
         * If the sender contains a "@" or a "%", make "name" into an
         * address on that host, on the presumption that it should
         * really have read "name@from" when we received the message
         * rather than just "name".
         */
        if (any('@', from) || any('%', from))
                return(unuucp(makeremote(name, from)));
        if (value("onehop") && (cp = strchr(name, '!')) && cp > name) {
                /*
                 * "onehop" is set, meaning all machines are one UUCP
                 * hop away (fat chance, in this day and age), and "name"
                 * is a UUCP path rather than just a name.  Leave it alone.
                 */
                nstrcpy(nbuf, sizeof (nbuf), name);
        } else {
                from = tackon(host, from);
                *strrchr(from, '!') = 0;
                name = tackon(lasthost(from), name);
                while (((cp = lasthost(from)) != 0) && ishost(cp, name)) {
                        oname = name;
                        name = strchr(name, '!') + 1;
                        if (cp == from) {
                                from[strlen(from)] = '!';
                                if (value("mustbang") && !strchr(name, '!'))
                                        name = oname;
                                return(unuucp(name));
                        }
                        *--cp = 0;
                }
                from[strlen(from)] = '!';
                from = strchr(from, '!') + 1;
                snprintf(nbuf, sizeof (nbuf), "%s!%s", from, name);
        }
        if (debug) fprintf(stderr, "before optim, nbuf '%s'\n", name);
#ifdef  OPTIM
        if ((cp = value("conv"))==NOSTR || strcmp(cp, "optimize") != 0)
                nstrcpy(ret, sizeof (ret), nbuf);
        else
                optim(nbuf, ret);
#else
        nstrcpy(ret, sizeof (ret), nbuf);
#endif  /* OPTIM */
        if (debug) fprintf(stderr, "after  optim, nbuf '%s', ret '%s'\n", nbuf, ret);
        cp = ret;
        if (debug) fprintf(stderr, "wind up with '%s'\n", name);
        if (!icequal(name, cp))
                return(unuucp((char *) savestr(cp)));
        return(unuucp(name));
}

/*
 * Stick a host on the beginning of a uucp
 * address if it isn't there already.
 */
static char *
tackon(char *sys, char *rest)
{
        while (*rest == '!')
                rest++;
        if (!ishost(sys, rest)) {
                char *r = (char *)salloc(strlen(sys) + strlen(rest) + 2);
                sprintf(r, "%s!%s", sys, rest);
                rest = r;
        }
        return rest;
}

/*
 * Check equality of the first host in a uucp address.
 */
int 
ishost(char *sys, char *rest)
{
        while (*sys && *sys == *rest)
                sys++, rest++;
        return(*sys == 0 && *rest == '!');
}

/*
 * Return last host in a uucp address.
 */
static char *
lasthost(char *addr)
{
        char *r = strrchr(addr, '!');
        return r ? ++r : addr;
}

/*
 * Optionally translate an old format uucp name into a new one, e.g.
 * "mach1!mach2!user" becomes "user@mach2.UUCP".  This optional because
 * some information is necessarily lost (e.g. the route it got here
 * via) and if we don't have the host in our routing tables, we lose.
 * XXX THIS IS NO LONGER VALID WITH THE NEW UUCP PROJECT PLANS TO
 * REGISTER UUCP HOSTS IN THE STANDARD INTERNET NAMESPACE, E.G.
 * ihnp4 BECOMES "ihnp4.att.com".
 */
char *
unuucp(char *name)
{
        register char *np, *hp, *cp;
        char result[100];
        char tname[300];

        if (UnUUCP==0 &&
            ((cp = value("conv"))==NOSTR || strcmp(cp, "internet")))
                return name;
        if (debug) fprintf(stderr, "unuucp(%s)\n", name);
        nstrcpy(tname, sizeof (tname), name);
        np = strrchr(tname, '!');
        if (np == NOSTR)
                return name;
        *np++ = 0;
        hp = strrchr(tname, '!');
        if (hp == NOSTR)
                hp = tname;
        else
                *hp++ = 0;
        cp = strchr(np, '@');
        if (cp == NOSTR)
                cp = strchr(np, '%');
        if (cp)
                *cp = 0;
        if (debug) fprintf(stderr, "host %s, name %s\n", hp, np);
        snprintf(result, sizeof (result), "%s@%s.UUCP", np, hp);
        if (debug) fprintf(stderr, "unuucp returns %s\n", result);
        return savestr(result);
}

/*
 * Turn a network machine name into a unique character
 */
static int 
netlook(char machine[], int attnet)
{
        register struct netmach *np;
        register char *cp, *cp2;
        char nbuf[BUFSIZ];

        /*
         * Make into lower case.
         */
        for (cp = machine, cp2 = nbuf;
             *cp && cp2 < &nbuf[BUFSIZ-1];
             *cp2++ = tolower(*cp++))
                /*nothing*/;
        *cp2 = 0;

        /*
         * If a single letter machine, look through those first.
         */

        if (strlen(nbuf) == 1)
                for (np = netmach; np->nt_mid != 0; np++)
                        if (np->nt_mid == nbuf[0])
                                return(nbuf[0]);

        /*
         * Look for usual name
         */

        for (np = netmach; np->nt_mid != 0; np++)
                if (strcmp(np->nt_machine, nbuf) == 0)
                        return(np->nt_mid);

        /*
         * Look in side hash table.
         */

        return(mstash(nbuf, attnet));
}

#ifdef OPTIM
/*
 * Turn a network unique character identifier into a network name.
 */

static char *
netname(int mid)
{
        register struct netmach *np;

        if (mid & 0200)
                return(mlook(mid));
        for (np = netmach; np->nt_mid != 0; np++)
                if (np->nt_mid == mid)
                        return(np->nt_machine);
        return(NOSTR);
}
#endif

/*
 * Deal with arpa net addresses.  The way this is done is strange.
 * name contains an "@" or "%".  Look up the machine after it in
 * the hash table.  If it isn't found, return name unmolested.
 * If ???, return name unmolested.
 * Otherwise, delete the "@" or "%" and the machine after it from
 * name, and return the new string.
 */
static char *
arpafix(char name[], char from[])
{
        register char *cp;
        register int arpamach;
        char newname[BUFSIZ];

        if (debug) {
                fprintf(stderr, "arpafix(%s, %s)\n", name, from);
        }
        cp = strrchr(name, '@');
        if (cp == NOSTR)
                cp = strrchr(name, '%');
        if (cp == NOSTR) {
                fprintf(stderr,
                    gettext("Something's amiss -- no @ or %% in arpafix\n"));
                return(name);
        }
        cp++;
        arpamach = netlook(cp, '@');
        if (debug)
                fprintf(stderr,
                    "cp '%s', arpamach %o, nettypes arpamach %o LOCAL %o\n",
                    cp, arpamach, nettype(arpamach), nettype(LOCAL));
        if (arpamach == 0) {
                if (debug)
                        fprintf(stderr, "machine %s unknown, uses: %s\n",
                            cp, name);
                return(name);
        }
        if (((nettype(arpamach) & nettype(LOCAL)) & ~AN) == 0) {
                if (debug)
                        fprintf(stderr, "machine %s known but remote, uses: %s\n",
                            cp, name);
                return(name);
        }
        nstrcpy(newname, sizeof (newname), name);
        cp = strrchr(newname, '@');
        if (cp == NOSTR)
                cp = strrchr(newname, '%');
        *cp = 0;
        if (debug) fprintf(stderr, "local address, return '%s'\n", newname);
        return(savestr(newname));
}

/*
 * We have name with no @'s in it, and from with @'s.
 * Assume that name is meaningful only on the site in from,
 * and return "name@site_in_from".
 */
static char *
makeremote(char name[], char from[])
{
        register char *cp;
        char rbuf[BUFSIZ];

        if (!value("makeremote"))
                return(name);
        if (debug) fprintf(stderr, "makeremote(%s, %s) returns ", name, from);
        cp = strrchr(from, '@');
        if (cp == NOSTR)
                cp = strrchr(from, '%');
        snprintf(rbuf, sizeof (rbuf), "%s%s", name, cp);
        if (debug) fprintf(stderr, "%s\n", rbuf);
        return(savestr(rbuf));
}

/*
 * Take a network machine descriptor and find the types of connected
 * nets and return it.
 */
static int 
nettype(int mid)
{
        register struct netmach *np;

        if (mid & 0200)
                return(mtype(mid));
        for (np = netmach; np->nt_mid != 0; np++)
                if (np->nt_mid == mid)
                        return(np->nt_type);
        return(0);
}

/*
 * Hashing routines to salt away machines seen scanning
 * networks paths that we don't know about.
 */

#define XHSIZE          97              /* Size of extra hash table */
#define NXMID           (XHSIZE*3/4)    /* Max extra machines */

struct xtrahash {
        char    *xh_name;               /* Name of machine */
        short   xh_mid;                 /* Machine ID */
        short   xh_attnet;              /* Attached networks */
} xtrahash[XHSIZE];

static struct xtrahash  *xtab[XHSIZE];          /* F: mid-->machine name */

static short    midfree;                        /* Next free machine id */

/*
 * Initialize the extra host hash table.
 * Called by sreset.
 */
void 
minit(void)
{
        register struct xtrahash *xp, **tp;

        midfree = 0;
        tp = &xtab[0];
        for (xp = &xtrahash[0]; xp < &xtrahash[XHSIZE]; xp++) {
                xp->xh_name = NOSTR;
                xp->xh_mid = 0;
                xp->xh_attnet = 0;
                *tp++ = NULL;
        }
}

/*
 * Stash a net name in the extra host hash table.
 * If a new entry is put in the hash table, deduce what
 * net the machine is attached to from the net character.
 *
 * If the machine is already known, add the given attached
 * net to those already known.
 */
static int 
mstash(char name[], int attnet)
{
        register struct xtrahash *xp;
        int x;

        xp = xlocate(name);
        if (xp == NULL) {
                printf(gettext("Ran out of machine id spots\n"));
                return(0);
        }
        if (xp->xh_name == NOSTR) {
                if (midfree >= XHSIZE) {
                        printf(gettext("Out of machine ids\n"));
                        return(0);
                }
                xtab[midfree] = xp;
                xp->xh_name = savestr(name);
                xp->xh_mid = 0200 + midfree++;
        }
        x = ntype(attnet);
        if (x == 0)
                xp->xh_attnet |= AN;
        else
                xp->xh_attnet |= x;
        return(xp->xh_mid);
}

/*
 * Search for the given name in the hash table
 * and return the pointer to it if found, or to the first
 * empty slot if not found.
 *
 * If no free slots can be found, return 0.
 */

static struct xtrahash *
xlocate(char name[])
{
        register int h, q, i;
        register char *cp;
        register struct xtrahash *xp;

        for (h = 0, cp = name; *cp; h = (h << 2) + *cp++)
                ;
        if (h < 0 && (h = -h) < 0)
                h = 0;
        h = h % XHSIZE;
        cp = name;
        for (i = 0, q = 0; q < XHSIZE; i++, q = i * i) {
                xp = &xtrahash[(h + q) % XHSIZE];
                if (xp->xh_name == NOSTR)
                        return(xp);
                if (strcmp(cp, xp->xh_name) == 0)
                        return(xp);
                if (h - q < 0)
                        h += XHSIZE;
                xp = &xtrahash[(h - q) % XHSIZE];
                if (xp->xh_name == NOSTR)
                        return(xp);
                if (strcmp(cp, xp->xh_name) == 0)
                        return(xp);
        }
        return(NULL);
}

#ifdef OPTIM
/*
 * Return the name from the extra host hash table corresponding
 * to the passed machine id.
 */

static char *
mlook(int mid)
{
        register int m;

        if ((mid & 0200) == 0)
                return(NOSTR);
        m = mid & 0177;
        if (m >= midfree) {
                printf(gettext("Use made of undefined machine id\n"));
                return(NOSTR);
        }
        return(xtab[m]->xh_name);
}
#endif

/*
 * Return the bit mask of net's that the given extra host machine
 * id has so far.
 */
static int 
mtype(int mid)
{
        register int m;

        if ((mid & 0200) == 0)
                return(0);
        m = mid & 0177;
        if (m >= midfree) {
                printf(gettext("Use made of undefined machine id\n"));
                return(0);
        }
        return(xtab[m]->xh_attnet);
}

#ifdef  OPTIM
/*
 * Take a network name and optimize it.  This gloriously messy
 * operation takes place as follows:  the name with machine names
 * in it is tokenized by mapping each machine name into a single
 * character machine id (netlook).  The separator characters (network
 * metacharacters) are left intact.  The last component of the network
 * name is stripped off and assumed to be the destination user name --
 * it does not participate in the optimization.  As an example, the
 * name "res!vax!res!uvax!bill" becomes, tokenized,
 * "r!x!r!v!" and "bill"  A low level routine, optim1, fixes up the
 * network part (eg, "r!x!r!v!"), then we convert back to network
 * machine names and tack the user name on the end.
 *
 * The result of this is copied into the parameter "name"
 */

static void
optim(char net[], char name[])
{
        char netcomp[BUFSIZ], netstr[STSIZ], xfstr[STSIZ];
        register char *cp, *cp2;
        register int c;

        if (debug) fprintf(stderr, "optim(%s, %s) called\n", net, name);
        *netstr = '\0';
        cp = net;
        for (;;) {
                /*
                 * Rip off next path component into netcomp
                 */
                cp2 = netcomp;
                while (*cp && !any(*cp, metanet))
                        *cp2++ = *cp++;
                *cp2 = 0;
                /*
                 * If we hit null byte, then we just scanned
                 * the destination user name.  Go off and optimize
                 * if its so.
                 */
                if (*cp == 0)
                        break;
                if ((c = netlook(netcomp, *cp)) == 0) {
                        printf(gettext("No host named \"%s\"\n"), netcomp);
err:
                        nstrcpy(name, BUFSIZ, net);
                        return;
                }
                stradd(name, BUFSIZ, c);
                stradd(name, BUFSIZ, *cp++);
                /*
                 * If multiple network separators given,
                 * throw away the extras.
                 */
                while (any(*cp, metanet))
                        cp++;
        }
        if (strlen(netcomp) == 0) {
                printf(gettext("net name syntax\n"));
                goto err;
        }
        if (debug) fprintf(stderr, "optim1(%s,%s) called\n", netstr, xfstr);
        optim1(netstr, xfstr);
        if (debug) fprintf(stderr, "optim1(%s,%s) returns\n", netstr, xfstr);

        /*
         * Convert back to machine names.
         */

        cp = xfstr;
        *name = '\0';
        while (*cp) {
                if ((cp2 = netname(*cp++)) == NOSTR) {
                        printf(gettext("Made up bad net name\n"));
                        printf(gettext("Machine code %c (0%o)\n"), cp[-1],
cp[-1]);
                        printf(gettext("Sorry.\n"));
                        goto err;
                }
                nstrcat(name, BUFSIZ, cp2);
                stradd(name, BUFSIZ, *cp++);
        }
        nstrcat(name, BUFSIZ, netcomp);
        if (debug) fprintf(stderr, "optim returns %s in name\n", name);
}

/*
 * Take a string of network machine id's and separators and
 * optimize them.  We process these by pulling off maximal
 * leading strings of the same type, passing these to the appropriate
 * optimizer and concatenating the results.
 */

static void 
optim1(char netstr[], char name[])
{
        char path[STSIZ], rpath[STSIZ];
        register char *cp, *cp2;
        register int tp, nc;
        
        cp = netstr;
        prefer(cp);
        *name  = '\0';
        /*
         * If the address ultimately points back to us,
         * just return a null network path.
         */
        if ((int)strlen(cp) > 1 && cp[strlen(cp) - 2] == LOCAL)
                return;
        while (*cp != 0) {
                *path = '\0';

                tp = ntype(cp[1]);
                nc = cp[1];
                while (*cp && tp == ntype(cp[1])) {
                        stradd(path, sizeof (path), *cp++);
                        cp++;
                }
                switch (netkind(tp)) {
                default:
                        nstrcpy(rpath, sizeof (rpath), path);
                        break;

                case IMPLICIT:
                        optimimp(path, rpath);
                        break;

                case EXPLICIT:
                        optimex(path, rpath);
                        break;
                }
                for (cp2 = rpath; *cp2 != 0; cp2++) {
                        stradd(name, BUFSIZ, *cp2);
                        stradd(name, BUFSIZ, nc);
                }
        }
        optiboth(name);
        prefer(name);
}
#endif  /* OPTIM */

/*
 * Return the network of the separator --
 *      AN for arpa net
 *      BN for Bell labs net    (e.g. UUCP, NOT Berknet)
 *      SN for Schmidt net      (Berknet)
 *      0 if we don't know.
 */
static int 
ntype(register int nc)
{
        register struct ntypetab *np;

        for (np = ntypetab; np->nt_char != 0; np++)
                if (np->nt_char == nc)
                        return(np->nt_bcode);
        return(0);
}

#ifdef  OPTIM
/*
 * Return the kind of routing used for the particular net
 * EXPLICIT means explicitly routed
 * IMPLICIT means implicitly routed
 * 0 means don't know
 */

static int 
netkind(register int nt)
{
        register struct nkindtab *np;

        for (np = nkindtab; np->nk_type != 0; np++)
                if (np->nk_type == nt)
                        return(np->nk_kind);
        return(0);
}

/*
 * Do name optimization for an explicitly routed network (eg uucp).
 */

static int 
optimex(char net[], char name[])
{
        register char *cp, *rp;
        register int m;

        nstrcpy(name, STSIZ, net);
        cp = name;
        if (strlen(cp) == 0)
                return(-1);
        if (cp[strlen(cp)-1] == LOCAL) {
                name[0] = 0;
                return(0);
        }
        for (cp = name; *cp; cp++) {
                m = *cp;
                rp = strrchr(cp+1, m);
                if (rp != NOSTR)
                        strcpy(cp, rp);
        }
        return(0);
}

/*
 * Do name optimization for implicitly routed network (eg, arpanet).
 */

static int 
optimimp(char net[], char name[])
{
        register char *cp;
        register char m;

        cp = net;
        if (strlen(cp) == 0)
                return(-1);
        m = cp[strlen(cp) - 1];
        if (m == LOCAL) {
                *name = '\0';
                return(0);
        }
        name[0] = m;
        name[1] = 0;
        return(0);
}

/*
 * Perform global optimization on the given network path.
 * The trick here is to look ahead to see if there are any loops
 * in the path and remove them.  The interpretation of loops is
 * more strict here than in optimex since both the machine and net
 * type must match.
 */

static void 
optiboth(char net[])
{
        register char *cp, *cp2;

        cp = net;
        if (strlen(cp) == 0)
                return;
        if (((int)strlen(cp) % 2) != 0) {
                printf(gettext("Strange arg to optiboth\n"));
                return;
        }
        while (*cp) {
                cp2 = rpair(cp+2, *cp);
                if (cp2 != NOSTR)
                        strcpy(cp, cp2);
                cp += 2;
        }
}

/*
 * Find the rightmost instance of the given (machine, type) pair.
 */

static char *
rpair(char str[], int mach)
{
        register char *cp, *last;

        cp = str;
        last = NOSTR;
        while (*cp) {
                if (*cp == mach)
                        last = cp;
                cp += 2;
        }
        return(last);
}

/*
 * Change the network separators in the given network path
 * to the preferred network transmission means.
 */

static void 
prefer(char name[])
{
        register char *cp, n;
        register int state;

        state = LOCAL;
        for (cp = name; *cp; cp += 2) {
                n = best(state, *cp);
                if (n)
                        cp[1] = n;
                state = *cp;
        }
}

/*
 * Return the best network separator for the given machine pair.
 */

static char 
best(int src, int dest)
{
        register int dtype, stype;
        register struct netorder *np;

        stype = nettype(src);
        dtype = nettype(dest);
        fflush(stdout);
        if (stype == 0 || dtype == 0) {
                printf(gettext("ERROR:  unknown internal machine id\n"));
                return(0);
        }
        if ((stype & dtype) == 0)
                return(0);
        np = &netorder[0];
        while ((np->no_stat & stype & dtype) == 0)
                np++;
        return(np->no_char);
}
#endif  /* OPTIM */

#ifdef notdef
/*
 * Code to twist around arpa net names.
 */

#define WORD 257                        /* Token for a string */

static  char netbuf[256];
static  char *yylval;

/*
 * Reverse all of the arpa net addresses in the given name to
 * be of the form "host @ user" instead of "user @ host"
 * This function is its own inverse.
 */

char *
revarpa(char str[])
{

        if (yyinit(str) < 0)
                return(NOSTR);
        if (name())
                return(NOSTR);
        if (strcmp(str, netbuf) == 0)
                return(str);
        return(savestr(netbuf));
}

/*
 * Parse (by recursive descent) network names, using the following grammar:
 *      name:
 *              term {':' term}
 *              term {'^' term}
 *              term {'!' term}
 *              term '@' name
 *              term '%' name
 *
 *      term:
 *              string of characters.
 */

static int 
name(void)
{
        register int t;
        register char *cp;

        for (;;) {
                t = yylex();
                if (t != WORD)
                        return(-1);
                cp = yylval;
                t = yylex();
                switch (t) {
                case 0:
                        nstrcat(netbuf, sizeof (netbuf), cp);
                        return(0);

                case '@':
                case '%':
                        if (name())
                                return(-1);
                        stradd(netbuf, sizeof (netbuf), '@');
                        nstrcat(netbuf, sizeof (netbuf), cp);
                        return(0);      
                case WORD:
                        return(-1);

                default:
                        nstrcat(netbuf, sizeof (netbuf), cp);
                        stradd(netbuf, sizeof (netbuf), t);
                }
        }
}

/*
 * Scanner for network names.
 */

static  char *charp;                    /* Current input pointer */
static  int nexttok;                    /* Salted away next token */

/*
 * Initialize the network name scanner.
 */

int 
yyinit(char str[])
{
        static char lexbuf[BUFSIZ];

        netbuf[0] = 0;
        if (strlen(str) >= sizeof lexbuf - 1)
                return(-1);
        nexttok = 0;
        nstrcpy(lexbuf, sizeof (lexbuf), str);
        charp = lexbuf;
        return(0);
}

/*
 * Scan and return a single token.
 * yylval is set to point to a scanned string.
 */

int 
yylex(void)
{
        register char *cp, *dotp;
        register int s;

        if (nexttok) {
                s = nexttok;
                nexttok = 0;
                return(s);
        }
        cp = charp;
        while (*cp && isspace(*cp))
                cp++;
        if (*cp == 0)
                return(0);
        if (any(*cp, metanet)) {
                charp = cp+1;
                return(*cp);
        }
        dotp = cp;
        while (*cp && !any(*cp, metanet) && !any(*cp, " \t"))
                cp++;
        if (any(*cp, metanet))
                nexttok = *cp;
        if (*cp == 0)
                charp = cp;
        else
                charp = cp+1;
        *cp = 0;
        yylval = dotp;
        return(WORD);
}
#endif

/*
 * Add a single character onto a string. Here dstsize is the size of the 
 * destnation buffer.
 */

static void 
stradd(register char *dst, int dstsize, register int c)
{
        while (*dst != '\0') {
                dst++;
                dstsize--;
        }
        if (--dstsize > 0)
                *dst++ = (char)c;
        *dst = '\0';
}