/*      $OpenBSD: catopen.c,v 1.21 2017/04/27 23:54:08 millert Exp $ */
/*-
 * Copyright (c) 1996 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by J.T. Conklin.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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.
 */

#define _NLS_PRIVATE

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <nl_types.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define MAXIMUM(a, b)   (((a) > (b)) ? (a) : (b))

#define NLS_DEFAULT_LANG "C"

static nl_catd  load_msgcat(const char *);
static int      verify_msgcat(nl_catd);

nl_catd
catopen(const char *name, int oflag)
{
        char tmppath[PATH_MAX];
        char *nlspath;
        char *lang;
        char *s, *t, *sep, *dot;
        const char *u;
        nl_catd catd;
                
        if (name == NULL || *name == '\0')
                return (nl_catd) -1;

        /* absolute or relative path? */
        if (strchr(name, '/'))
                return load_msgcat(name);

        if (issetugid() != 0 || (nlspath = getenv("NLSPATH")) == NULL)
                return (nl_catd) -1;

        lang = NULL;
        if (oflag & NL_CAT_LOCALE) {
                lang = getenv("LC_ALL");
                if (lang == NULL)
                        lang = getenv("LC_MESSAGES");
        }
        if (lang == NULL)
                lang = getenv("LANG");
        if (lang == NULL)
                lang = NLS_DEFAULT_LANG;
        if (strcmp(lang, "POSIX") == 0)
                lang = NLS_DEFAULT_LANG;

        s = nlspath;
        t = tmppath;

        /*
         * Locale names are of the form language[_territory][.codeset].
         * See POSIX-1-2008 "8.2 Internationalization Variables"
         */
        sep = strchr(lang, '_');
        dot = strrchr(lang, '.');
        if (dot && sep && dot < sep)
                dot = NULL; /* ignore dots preceeding _ */
        if (dot == NULL)
                lang = NLS_DEFAULT_LANG; /* no codeset specified */
        do {
                while (*s && *s != ':') {
                        if (*s == '%') {
                                switch (*(++s)) {
                                case 'L':       /* LANG or LC_MESSAGES */
                                        u = lang;
                                        while (*u && t < tmppath + PATH_MAX-1)
                                                *t++ = *u++;
                                        break;
                                case 'N':       /* value of name parameter */
                                        u = name;
                                        while (*u && t < tmppath + PATH_MAX-1)
                                                *t++ = *u++;
                                        break;
                                case 'l':       /* language part */
                                        u = lang;
                                        while (*u && t < tmppath + PATH_MAX-1) {
                                                *t++ = *u++;
                                                if (sep && u >= sep)
                                                        break;
                                                if (dot && u >= dot)
                                                        break;
                                        }
                                        break;
                                case 't':       /* territory part */
                                        if (sep == NULL)
                                                break;
                                        u = sep + 1;
                                        while (*u && t < tmppath + PATH_MAX-1) {
                                                *t++ = *u++;
                                                if (dot && u >= dot)
                                                        break;
                                        }
                                        break;
                                case 'c':       /* codeset part */
                                        if (dot == NULL)
                                                break;
                                        u = dot + 1;
                                        while (*u && t < tmppath + PATH_MAX-1)
                                                *t++ = *u++;
                                        break;
                                default:
                                        if (t < tmppath + PATH_MAX-1)
                                                *t++ = *s;
                                }
                        } else {
                                if (t < tmppath + PATH_MAX-1)
                                        *t++ = *s;
                        }
                        s++;
                }

                *t = '\0';
                catd = load_msgcat(tmppath);
                if (catd != (nl_catd) -1)
                        return catd;

                if (*s)
                        s++;
                t = tmppath;
        } while (*s);

        return (nl_catd) -1;
}
DEF_WEAK(catopen);

static nl_catd
load_msgcat(const char *path)
{
        struct stat st;
        nl_catd catd;
        void *data;
        int fd;

        catd = NULL;

        if ((fd = open(path, O_RDONLY|O_CLOEXEC)) == -1)
                return (nl_catd) -1;

        if (fstat(fd, &st) != 0) {
                close (fd);
                return (nl_catd) -1;
        }

        if (st.st_size > INT_MAX || st.st_size < sizeof (struct _nls_cat_hdr)) {
                errno = EINVAL;
                close (fd);
                return (nl_catd) -1;
        }

        data = mmap(0, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
        close (fd);

        if (data == MAP_FAILED)
                return (nl_catd) -1;

        if (ntohl(((struct _nls_cat_hdr *) data)->__magic) != _NLS_MAGIC)
                goto invalid;

        if ((catd = malloc(sizeof (*catd))) == 0)
                goto invalid;

        catd->__data = data;
        catd->__size = st.st_size;

        if (verify_msgcat(catd))
                goto invalid;

        return catd;

invalid:
        free(catd);
        munmap(data, st.st_size);
        errno = EINVAL;
        return (nl_catd) -1;
}

static int
verify_msgcat(nl_catd catd)
{
        struct _nls_cat_hdr *cat;
        struct _nls_set_hdr *set;
        struct _nls_msg_hdr *msg;
        size_t remain;
        int hdr_offset, i, index, j, msgs, nmsgs, nsets, off, txt_offset;

        remain = catd->__size;
        cat = (struct _nls_cat_hdr *) catd->__data;

        hdr_offset = ntohl(cat->__msg_hdr_offset);
        nsets = ntohl(cat->__nsets);
        txt_offset = ntohl(cat->__msg_txt_offset);

        /* catalog must contain at least one set and no negative offsets */
        if (nsets < 1 || hdr_offset < 0 || txt_offset < 0)
                return (1);

        remain -= sizeof (*cat);

        /* check if offsets or set size overflow */
        if (remain <= hdr_offset || remain <= ntohl(cat->__msg_txt_offset) ||
            remain / sizeof (*set) < nsets)
                return (1);

        set = (struct _nls_set_hdr *) ((char *) catd->__data + sizeof (*cat));

        /* make sure that msg has space for at least one index */
        if (remain - hdr_offset < sizeof(*msg))
                return (1);

        msg = (struct _nls_msg_hdr *) ((char *) catd->__data + sizeof (*cat)
            + hdr_offset);

        /* validate and retrieve largest string offset from sets */
        off = 0;
        for (i = 0; i < nsets; i++) {
                index = ntohl(set[i].__index);
                nmsgs = ntohl(set[i].__nmsgs);
                /* set must contain at least one message */
                if (index < 0 || nmsgs < 1)
                        return (1);

                if (INT_MAX - nmsgs < index)
                        return (1);
                msgs = index + nmsgs;

                /* avoid msg index overflow */
                if ((remain - hdr_offset) / sizeof(*msg) < msgs)
                        return (1);

                /* retrieve largest string offset */
                for (j = index; j < nmsgs; j++) {
                        if (ntohl(msg[j].__offset) > INT_MAX)
                                return (1);
                        off = MAXIMUM(off, ntohl(msg[j].__offset));
                }
        }

        /* check if largest string offset is nul-terminated */
        if (remain - txt_offset < off ||
            memchr((char *) catd->__data + sizeof(*cat) + txt_offset + off,
            '\0', remain - txt_offset - off) == NULL)
                return (1);

        return (0);
}