source: trunk/third/openssh/match.c @ 16801

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Simple pattern matching, with '*' and '?' as wildcards.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */
/*
 * Copyright (c) 2000 Markus Friedl.  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#include "includes.h"
RCSID("$OpenBSD: match.c,v 1.14 2001/06/27 04:48:53 markus Exp $");

#include "match.h"
#include "xmalloc.h"

/*
 * Returns true if the given string matches the pattern (which may contain ?
 * and * as wildcards), and zero if it does not match.
 */

int
match_pattern(const char *s, const char *pattern)
{
        for (;;) {
                /* If at end of pattern, accept if also at end of string. */
                if (!*pattern)
                        return !*s;

                if (*pattern == '*') {
                        /* Skip the asterisk. */
                        pattern++;

                        /* If at end of pattern, accept immediately. */
                        if (!*pattern)
                                return 1;

                        /* If next character in pattern is known, optimize. */
                        if (*pattern != '?' && *pattern != '*') {
                                /*
                                 * Look instances of the next character in
                                 * pattern, and try to match starting from
                                 * those.
                                 */
                                for (; *s; s++)
                                        if (*s == *pattern &&
                                            match_pattern(s + 1, pattern + 1))
                                                return 1;
                                /* Failed. */
                                return 0;
                        }
                        /*
                         * Move ahead one character at a time and try to
                         * match at each position.
                         */
                        for (; *s; s++)
                                if (match_pattern(s, pattern))
                                        return 1;
                        /* Failed. */
                        return 0;
                }
                /*
                 * There must be at least one more character in the string.
                 * If we are at the end, fail.
                 */
                if (!*s)
                        return 0;

                /* Check if the next character of the string is acceptable. */
                if (*pattern != '?' && *pattern != *s)
                        return 0;

                /* Move to the next character, both in string and in pattern. */
                s++;
                pattern++;
        }
        /* NOTREACHED */
}

/*
 * Tries to match the host name (which must be in all lowercase) against the
 * comma-separated sequence of subpatterns (each possibly preceded by ! to
 * indicate negation).  Returns -1 if negation matches, 1 if there is
 * a positive match, 0 if there is no match at all.
 */

int
match_hostname(const char *host, const char *pattern, u_int len)
{
        char sub[1024];
        int negated;
        int got_positive;
        u_int i, subi;

        got_positive = 0;
        for (i = 0; i < len;) {
                /* Check if the subpattern is negated. */
                if (pattern[i] == '!') {
                        negated = 1;
                        i++;
                } else
                        negated = 0;

                /*
                 * Extract the subpattern up to a comma or end.  Convert the
                 * subpattern to lowercase.
                 */
                for (subi = 0;
                     i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
                     subi++, i++)
                        sub[subi] = isupper(pattern[i]) ? tolower(pattern[i]) : pattern[i];
                /* If subpattern too long, return failure (no match). */
                if (subi >= sizeof(sub) - 1)
                        return 0;

                /* If the subpattern was terminated by a comma, skip the comma. */
                if (i < len && pattern[i] == ',')
                        i++;

                /* Null-terminate the subpattern. */
                sub[subi] = '\0';

                /* Try to match the subpattern against the host name. */
                if (match_pattern(host, sub)) {
                        if (negated)
                                return -1;              /* Negative */
                        else
                                got_positive = 1;       /* Positive */
                }
        }

        /*
         * Return success if got a positive match.  If there was a negative
         * match, we have already returned -1 and never get here.
         */
        return got_positive;
}

/*
 * returns 0 if we get a negative match for the hostname or the ip
 * or if we get no match at all.  returns 1 otherwise.
 */
int
match_host_and_ip(const char *host, const char *ipaddr,
    const char *patterns)
{
        int mhost, mip;

        /* negative ipaddr match */
        if ((mip = match_hostname(ipaddr, patterns, strlen(patterns))) == -1)
                return 0;
        /* negative hostname match */
        if ((mhost = match_hostname(host, patterns, strlen(patterns))) == -1)
                return 0;
        /* no match at all */
        if (mhost == 0 && mip == 0)
                return 0;
        return 1;
}

/*
 * match user, user@host_or_ip, user@host_or_ip_list against pattern
 */
int
match_user(const char *user, const char *host, const char *ipaddr,
    const char *pattern)
{
        char *p, *pat;
        int ret;

        if ((p = strchr(pattern,'@')) == NULL)
                return match_pattern(user, pattern);

        pat = xstrdup(pattern);
        p = strchr(pat, '@');
        *p++ = '\0';

        if ((ret = match_pattern(user, pat)) == 1)
                ret = match_host_and_ip(host, ipaddr, p);
        xfree(pat);

        return ret;
}

/*
 * Returns first item from client-list that is also supported by server-list,
 * caller must xfree() returned string.
 */
#define MAX_PROP        20
#define SEP     ","
char *
match_list(const char *client, const char *server, u_int *next)
{
        char *sproposals[MAX_PROP];
        char *c, *s, *p, *ret, *cp, *sp;
        int i, j, nproposals;

        c = cp = xstrdup(client);
        s = sp = xstrdup(server);

        for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
             (p = strsep(&sp, SEP)), i++) {
                if (i < MAX_PROP)
                        sproposals[i] = p;
                else
                        break;
        }
        nproposals = i;

        for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
             (p = strsep(&cp, SEP)), i++) {
                for (j = 0; j < nproposals; j++) {
                        if (strcmp(p, sproposals[j]) == 0) {
                                ret = xstrdup(p);
                                if (next != NULL)
                                        *next = (cp == NULL) ?
                                            strlen(c) : cp - c;
                                xfree(c);
                                xfree(s);
                                return ret;
                        }
                }
        }
        if (next != NULL)
                *next = strlen(c);
        xfree(c);
        xfree(s);
        return NULL;
}