/*
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Macklem at The University of Guelph.
 *
 * 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. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#)getnetgrent.c    8.2 (Berkeley) 4/27/95
 * $FreeBSD: src/lib/libc/gen/getnetgrent.c,v 1.35 2007/01/09 00:27:54 imp Exp $
 */

#include <ctype.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef YP
/*
 * Notes:
 * We want to be able to use NIS netgroups properly while retaining
 * the ability to use a local /etc/netgroup file. Unfortunately, you
 * can't really do both at the same time - at least, not efficiently.
 * NetBSD deals with this problem by creating a netgroup database
 * using Berkeley DB (just like the password database) that allows
 * for lookups using netgroup, netgroup.byuser or netgroup.byhost
 * searches. This is a neat idea, but I don't have time to implement
 * something like that now. (I think ultimately it would be nice
 * if we DB-fied the group and netgroup stuff all in one shot, but
 * for now I'm satisfied just to have something that works well
 * without requiring massive code changes.)
 * 
 * Therefore, to still permit the use of the local file and maintain
 * optimum NIS performance, we allow for the following conditions:
 *
 * - If /etc/netgroup does not exist and NIS is turned on, we use
 *   NIS netgroups only.
 *
 * - If /etc/netgroup exists but is empty, we use NIS netgroups
 *   only.
 *
 * - If /etc/netgroup exists and contains _only_ a '+', we use
 *   NIS netgroups only.
 *
 * - If /etc/netgroup exists, contains locally defined netgroups
 *   and a '+', we use a mixture of NIS and the local entries.
 *   This method should return the same NIS data as just using
 *   NIS alone, but it will be slower if the NIS netgroup database
 *   is large (innetgr() in particular will suffer since extra
 *   processing has to be done in order to determine memberships
 *   using just the raw netgroup data).
 *
 * - If /etc/netgroup exists and contains only locally defined
 *   netgroup entries, we use just those local entries and ignore
 *   NIS (this is the original, pre-NIS behavior).
 */

#include <rpc/rpc.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/errno.h>
static char *_netgr_yp_domain;
int _use_only_yp;
static int _netgr_yp_enabled;
static int _yp_innetgr;
#endif

#ifndef _PATH_NETGROUP
#define _PATH_NETGROUP "/etc/netgroup"
#endif

/*
 * Static Variables and functions used by setnetgrent(), getnetgrent() and
 * endnetgrent().
 * There are two linked lists:
 * - linelist is just used by setnetgrent() to parse the net group file via.
 *   parse_netgrp()
 * - netgrp is the list of entries for the current netgroup
 */
struct linelist {
        struct linelist *l_next;        /* Chain ptr. */
        int             l_parsed;       /* Flag for cycles */
        char            *l_groupname;   /* Name of netgroup */
        char            *l_line;        /* Netgroup entrie(s) to be parsed */
};

struct netgrp {
        struct netgrp   *ng_next;       /* Chain ptr */
        char            *ng_str[3];     /* Field pointers, see below */
};
#define NG_HOST         0       /* Host name */
#define NG_USER         1       /* User name */
#define NG_DOM          2       /* and Domain name */

static struct linelist  *linehead = NULL;
static struct netgrp    *nextgrp = NULL;
static struct {
        struct netgrp   *gr;
        char            *grname;
} grouphead = {
        NULL,
        NULL,
};
static FILE *netf = NULL;

static int parse_netgrp(const char *);
static struct linelist *read_for_group(const char *);

#define LINSIZ  1024    /* Length of netgroup file line */

/*
 * setnetgrent()
 * Parse the netgroup file looking for the netgroup and build the list
 * of netgrp structures. Let parse_netgrp() and read_for_group() do
 * most of the work.
 */
void
setnetgrent(const char *group)
{
#ifdef YP
        struct stat _yp_statp;
        char _yp_plus;
#endif

        /* Sanity check */

        if (group == NULL || !strlen(group))
                return;

        if (grouphead.gr == NULL ||
                strcmp(group, grouphead.grname)) {
                endnetgrent();
#ifdef YP
                /* Presumed guilty until proven innocent. */
                _use_only_yp = 0;
                /*
                 * If /etc/netgroup doesn't exist or is empty,
                 * use NIS exclusively.
                 */
                if (((stat(_PATH_NETGROUP, &_yp_statp) < 0) &&
                        errno == ENOENT) || _yp_statp.st_size == 0)
                        _use_only_yp = _netgr_yp_enabled = 1;
                if ((netf = fopen(_PATH_NETGROUP,"r")) != NULL ||_use_only_yp){
                /*
                 * Icky: grab the first character of the netgroup file
                 * and turn on NIS if it's a '+'. rewind the stream
                 * afterwards so we don't goof up read_for_group() later.
                 */
                        if (netf) {
                                fscanf(netf, "%c", &_yp_plus);
                                rewind(netf);
                                if (_yp_plus == '+')
                                        _use_only_yp = _netgr_yp_enabled = 1;
                        }
                /*
                 * If we were called specifically for an innetgr()
                 * lookup and we're in NIS-only mode, short-circuit
                 * parse_netgroup() and cut directly to the chase.
                 */
                        if (_use_only_yp && _yp_innetgr) {
                                /* dohw! */
                                if (netf != NULL)
                                        fclose(netf);
                                return;
                        }
#else
                if ((netf = fopen(_PATH_NETGROUP, "r"))) {
#endif
                        if (parse_netgrp(group))
                                endnetgrent();
                        else {
                                grouphead.grname = (char *)
                                        malloc(strlen(group) + 1);
                                strcpy(grouphead.grname, group);
                        }
                        if (netf)
                                fclose(netf);
                }
        }
        nextgrp = grouphead.gr;
}

/*
 * Get the next netgroup off the list.
 */
int
getnetgrent(char **hostp, char **userp, char **domp)
{
#ifdef YP
        _yp_innetgr = 0;
#endif

        if (nextgrp) {
                *hostp = nextgrp->ng_str[NG_HOST];
                *userp = nextgrp->ng_str[NG_USER];
                *domp = nextgrp->ng_str[NG_DOM];
                nextgrp = nextgrp->ng_next;
                return (1);
        }
        return (0);
}

/*
 * endnetgrent() - cleanup
 */
void
endnetgrent(void)
{
        struct linelist *lp, *olp;
        struct netgrp *gp, *ogp;

        lp = linehead;
        while (lp) {
                olp = lp;
                lp = lp->l_next;
                free(olp->l_groupname);
                free(olp->l_line);
                free((char *)olp);
        }
        linehead = NULL;
        if (grouphead.grname) {
                free(grouphead.grname);
                grouphead.grname = NULL;
        }
        gp = grouphead.gr;
        while (gp) {
                ogp = gp;
                gp = gp->ng_next;
                if (ogp->ng_str[NG_HOST])
                        free(ogp->ng_str[NG_HOST]);
                if (ogp->ng_str[NG_USER])
                        free(ogp->ng_str[NG_USER]);
                if (ogp->ng_str[NG_DOM])
                        free(ogp->ng_str[NG_DOM]);
                free((char *)ogp);
        }
        grouphead.gr = NULL;
        nextgrp = NULL;
#ifdef YP
        _netgr_yp_enabled = 0;
#endif
}

#ifdef YP
static int
_listmatch(const char *list, const char *group, int len)
{
        const char *ptr = list;
        const char *cptr;
        int glen = strlen(group);

        /* skip possible leading whitespace */
        while(isspace((unsigned char)*ptr))
                ptr++;

        while (ptr < list + len) {
                cptr = ptr;
                while(*ptr != ','  && *ptr != '\0' && !isspace((unsigned char)*ptr))
                        ptr++;
                if (strncmp(cptr, group, glen) == 0 && glen == (ptr - cptr))
                        return(1);
                while(*ptr == ','  || isspace((unsigned char)*ptr))
                        ptr++;
        }

        return(0);
}

static int
_revnetgr_lookup(char *lookupdom, char *map, const char *str,
                 const char *dom, const char *group)
{
        int y, rv, rot;
        char key[MAXHOSTNAMELEN];
        char *result;
        int resultlen;

        for (rot = 0; ; rot++) {
                switch (rot) {
                        case(0): snprintf(key, MAXHOSTNAMELEN, "%s.%s",
                                          str, dom?dom:lookupdom);
                                 break;
                        case(1): snprintf(key, MAXHOSTNAMELEN, "%s.*",
                                          str);
                                 break;
                        case(2): snprintf(key, MAXHOSTNAMELEN, "*.%s",
                                          dom?dom:lookupdom);
                                 break;
                        case(3): snprintf(key, MAXHOSTNAMELEN, "*.*");
                                 break;
                        default: return(0);
                }
                y = yp_match(lookupdom, map, key, strlen(key), &result,
                             &resultlen);
                if (y == 0) {
                        rv = _listmatch(result, group, resultlen);
                        free(result);
                        if (rv) return(1);
                } else if (y != YPERR_KEY) {
                        /*
                         * If we get an error other than 'no
                         * such key in map' then something is
                         * wrong and we should stop the search.
                         */
                        return(-1);
                }
        }
}
#endif

/*
 * Search for a match in a netgroup.
 */
int
innetgr(const char *group, const char *host, const char *user, const char *dom)
{
        char *hst, *usr, *dm;
        /* Sanity check */
        
        if (group == NULL || !strlen(group))
                return (0);

#ifdef YP
        _yp_innetgr = 1;
#endif
        setnetgrent(group);
#ifdef YP
        _yp_innetgr = 0;
        /*
         * If we're in NIS-only mode, do the search using
         * NIS 'reverse netgroup' lookups.
         *
         * What happens with 'reverse netgroup' lookups:
         *
         * 1) try 'reverse netgroup' lookup
         *    1.a) if host is specified and user is null:
         *         look in netgroup.byhost
         *         (try host.domain, host.*, *.domain or *.*)
         *         if found, return yes
         *    1.b) if user is specified and host is null:
         *         look in netgroup.byuser
         *         (try host.domain, host.*, *.domain or *.*)
         *         if found, return yes
         *    1.c) if both host and user are specified,
         *         don't do 'reverse netgroup' lookup.  It won't work.
         *    1.d) if neither host ane user are specified (why?!?)
         *         don't do 'reverse netgroup' lookup either.
         * 2) if domain is specified and 'reverse lookup' is done:
         *    'reverse lookup' was authoritative.  bye bye.
         * 3) otherwise, too bad, try it the slow way.
         */
        if (_use_only_yp && (host == NULL) != (user == NULL)) {
                int ret;
                if(yp_get_default_domain(&_netgr_yp_domain))
                        return(0);
                ret = _revnetgr_lookup(_netgr_yp_domain,
                                      host?"netgroup.byhost":"netgroup.byuser",
                                      host?host:user, dom, group);
                if (ret == 1)
                        return(1);
                else if (ret == 0 && dom != NULL)
                        return(0);
        }

        setnetgrent(group);
#endif /* YP */

        while (getnetgrent(&hst, &usr, &dm))
                if ((host == NULL || hst == NULL || !strcmp(host, hst)) &&
                    (user == NULL || usr == NULL || !strcmp(user, usr)) &&
                    ( dom == NULL ||  dm == NULL || !strcmp(dom, dm))) {
                        endnetgrent();
                        return (1);
                }
        endnetgrent();
        return (0);
}

/*
 * Parse the netgroup file setting up the linked lists.
 */
static int
parse_netgrp(const char *group)
{
        char *spos, *epos;
        int len, strpos;
#ifdef DEBUG
        int fields;
#endif
        char *pos, *gpos;
        struct netgrp *grp;
        struct linelist *lp = linehead;

        /*
         * First, see if the line has already been read in.
         */
        while (lp) {
                if (!strcmp(group, lp->l_groupname))
                        break;
                lp = lp->l_next;
        }
        if (lp == NULL &&
            (lp = read_for_group(group)) == NULL)
                return (1);
        if (lp->l_parsed) {
#ifdef DEBUG
                /*
                 * This error message is largely superflous since the
                 * code handles the error condition successfully, and
                 * spewing it out from inside libc can actually hose
                 * certain programs.
                 */
                fprintf(stderr, "Cycle in netgroup %s\n", lp->l_groupname);
#endif
                return (1);
        } else
                lp->l_parsed = 1;
        pos = lp->l_line;
        /* Watch for null pointer dereferences, dammit! */
        while (pos != NULL && *pos != '\0') {
                if (*pos == '(') {
                        grp = (struct netgrp *)malloc(sizeof (struct netgrp));
                        bzero((char *)grp, sizeof (struct netgrp));
                        grp->ng_next = grouphead.gr;
                        grouphead.gr = grp;
                        pos++;
                        gpos = strsep(&pos, ")");
#ifdef DEBUG
                        fields = 0;
#endif
                        for (strpos = 0; strpos < 3; strpos++) {
                                if ((spos = strsep(&gpos, ","))) {
#ifdef DEBUG
                                        fields++;
#endif
                                        while (*spos == ' ' || *spos == '\t')
                                                spos++;
                                        if ((epos = strpbrk(spos, " \t"))) {
                                                *epos = '\0';
                                                len = epos - spos;
                                        } else
                                                len = strlen(spos);
                                        if (len > 0) {
                                                grp->ng_str[strpos] =  (char *)
                                                        malloc(len + 1);
                                                bcopy(spos, grp->ng_str[strpos],
                                                        len + 1);
                                        }
                                } else {
                                        /*
                                         * All other systems I've tested
                                         * return NULL for empty netgroup
                                         * fields. It's up to user programs
                                         * to handle the NULLs appropriately.
                                         */
                                        grp->ng_str[strpos] = NULL;
                                }
                        }
#ifdef DEBUG
                        /*
                         * Note: on other platforms, malformed netgroup
                         * entries are not normally flagged. While we
                         * can catch bad entries and report them, we should
                         * stay silent by default for compatibility's sake.
                         */
                        if (fields < 3)
                                        fprintf(stderr, "Bad entry (%s%s%s%s%s) in netgroup \"%s\"\n",
                                                grp->ng_str[NG_HOST] == NULL ? "" : grp->ng_str[NG_HOST],
                                                grp->ng_str[NG_USER] == NULL ? "" : ",",
                                                grp->ng_str[NG_USER] == NULL ? "" : grp->ng_str[NG_USER],
                                                grp->ng_str[NG_DOM] == NULL ? "" : ",",
                                                grp->ng_str[NG_DOM] == NULL ? "" : grp->ng_str[NG_DOM],
                                                lp->l_groupname);
#endif
                } else {
                        spos = strsep(&pos, ", \t");
                        if (parse_netgrp(spos))
                                continue;
                }
                if (pos == NULL)
                        break;
                while (*pos == ' ' || *pos == ',' || *pos == '\t')
                        pos++;
        }
        return (0);
}

/*
 * Read the netgroup file and save lines until the line for the netgroup
 * is found. Return 1 if eof is encountered.
 */
static struct linelist *
read_for_group(const char *group)
{
        char *pos, *spos, *linep = NULL, *olinep = NULL;
        int len, olen;
        int cont;
        struct linelist *lp;
        char line[LINSIZ + 2];
#ifdef YP
        char *result;
        int resultlen;

        while (_netgr_yp_enabled || fgets(line, LINSIZ, netf) != NULL) {
                if (_netgr_yp_enabled) {
                        if(!_netgr_yp_domain)
                                if(yp_get_default_domain(&_netgr_yp_domain))
                                        continue;
                        if (yp_match(_netgr_yp_domain, "netgroup", group,
                                        strlen(group), &result, &resultlen)) {
                                free(result);
                                if (_use_only_yp)
                                        return (NULL);
                                else {
                                        _netgr_yp_enabled = 0;
                                        continue;
                                }
                        }
                        snprintf(line, LINSIZ, "%s %s", group, result);
                        free(result);
                }
#else
        while (fgets(line, LINSIZ, netf) != NULL) {
#endif
                pos = (char *)&line;
#ifdef YP
                if (*pos == '+') {
                        _netgr_yp_enabled = 1;
                        continue;
                }
#endif
                if (*pos == '#')
                        continue;
                while (*pos == ' ' || *pos == '\t')
                        pos++;
                spos = pos;
                while (*pos != ' ' && *pos != '\t' && *pos != '\n' &&
                        *pos != '\0')
                        pos++;
                len = pos - spos;
                while (*pos == ' ' || *pos == '\t')
                        pos++;
                if (*pos != '\n' && *pos != '\0') {
                        lp = (struct linelist *)malloc(sizeof (*lp));
                        lp->l_parsed = 0;
                        lp->l_groupname = (char *)malloc(len + 1);
                        bcopy(spos, lp->l_groupname, len);
                        *(lp->l_groupname + len) = '\0';
                        len = strlen(pos);
                        olen = 0;

                        /*
                         * Loop around handling line continuations.
                         */
                        do {
                                if (*(pos + len - 1) == '\n')
                                        len--;
                                if (*(pos + len - 1) == '\\') {
                                        len--;
                                        cont = 1;
                                } else
                                        cont = 0;
                                if (len > 0) {
                                        linep = (char *)malloc(olen + len + 1);
                                        if (olen > 0) {
                                                bcopy(olinep, linep, olen);
                                                free(olinep);
                                        }
                                        bcopy(pos, linep + olen, len);
                                        olen += len;
                                        *(linep + olen) = '\0';
                                        olinep = linep;
                                }
                                if (cont) {
                                        if (fgets(line, LINSIZ, netf)) {
                                                pos = line;
                                                len = strlen(pos);
                                        } else
                                                cont = 0;
                                }
                        } while (cont);
                        lp->l_line = linep;
                        lp->l_next = linehead;
                        linehead = lp;

                        /*
                         * If this is the one we wanted, we are done.
                         */
                        if (!strcmp(lp->l_groupname, group))
                                return (lp);
                }
        }
#ifdef YP
        /*
         * Yucky. The recursive nature of this whole mess might require
         * us to make more than one pass through the netgroup file.
         * This might be best left outside the #ifdef YP, but YP is
         * defined by default anyway, so I'll leave it like this
         * until I know better.
         */
        rewind(netf);
#endif
        return (NULL);
}