match.c

   1 /* $OpenBSD: match.c,v 1.24 2006/03/25 13:17:02 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Simple pattern matching, with '*' and '?' as wildcards.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  */
  14 /*
  15  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  * 1. Redistributions of source code must retain the above copyright
  21  *    notice, this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright
  23  *    notice, this list of conditions and the following disclaimer in the
  24  *    documentation and/or other materials provided with the distribution.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #include "includes.h"
  39
  40 #include <ctype.h>
  41
  42 #include "match.h"
  43 #include "xmalloc.h"
  44
  45 /*
  46  * Returns true if the given string matches the pattern (which may contain ?
  47  * and * as wildcards), and zero if it does not match.
  48  */
  49
  50 int
  51 match_pattern(const char *s, const char *pattern)
  52 {
  53         for (;;) {
  54                 /* If at end of pattern, accept if also at end of string. */
  55                 if (!*pattern)
  56                         return !*s;
  57
  58                 if (*pattern == '*') {
  59                         /* Skip the asterisk. */
  60                         pattern++;
  61
  62                         /* If at end of pattern, accept immediately. */
  63                         if (!*pattern)
  64                                 return 1;
  65
  66                         /* If next character in pattern is known, optimize. */
  67                         if (*pattern != '?' && *pattern != '*') {
  68                                 /*
  69                                  * Look instances of the next character in
  70                                  * pattern, and try to match starting from
  71                                  * those.
  72                                  */
  73                                 for (; *s; s++)
  74                                         if (*s == *pattern &&
  75                                             match_pattern(s + 1, pattern + 1))
  76                                                 return 1;
  77                                 /* Failed. */
  78                                 return 0;
  79                         }
  80                         /*
  81                          * Move ahead one character at a time and try to
  82                          * match at each position.
  83                          */
  84                         for (; *s; s++)
  85                                 if (match_pattern(s, pattern))
  86                                         return 1;
  87                         /* Failed. */
  88                         return 0;
  89                 }
  90                 /*
  91                  * There must be at least one more character in the string.
  92                  * If we are at the end, fail.
  93                  */
  94                 if (!*s)
  95                         return 0;
  96
  97                 /* Check if the next character of the string is acceptable. */
  98                 if (*pattern != '?' && *pattern != *s)
  99                         return 0;
 100
 101                 /* Move to the next character, both in string and in pattern. */
 102                 s++;
 103                 pattern++;
 104         }
 105         /* NOTREACHED */
 106 }
 107
 108 /*
 109  * Tries to match the string against the
 110  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 111  * indicate negation).  Returns -1 if negation matches, 1 if there is
 112  * a positive match, 0 if there is no match at all.
 113  */
 114
 115 int
 116 match_pattern_list(const char *string, const char *pattern, u_int len,
 117     int dolower)
 118 {
 119         char sub[1024];
 120         int negated;
 121         int got_positive;
 122         u_int i, subi;
 123
 124         got_positive = 0;
 125         for (i = 0; i < len;) {
 126                 /* Check if the subpattern is negated. */
 127                 if (pattern[i] == '!') {
 128                         negated = 1;
 129                         i++;
 130                 } else
 131                         negated = 0;
 132
 133                 /*
 134                  * Extract the subpattern up to a comma or end.  Convert the
 135                  * subpattern to lowercase.
 136                  */
 137                 for (subi = 0;
 138                     i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
 139                     subi++, i++)
 140                         sub[subi] = dolower && isupper(pattern[i]) ?
 141                             (char)tolower(pattern[i]) : pattern[i];
 142                 /* If subpattern too long, return failure (no match). */
 143                 if (subi >= sizeof(sub) - 1)
 144                         return 0;
 145
 146                 /* If the subpattern was terminated by a comma, skip the comma. */
 147                 if (i < len && pattern[i] == ',')
 148                         i++;
 149
 150                 /* Null-terminate the subpattern. */
 151                 sub[subi] = '\0';
 152
 153                 /* Try to match the subpattern against the string. */
 154                 if (match_pattern(string, sub)) {
 155                         if (negated)
 156                                 return -1;              /* Negative */
 157                         else
 158                                 got_positive = 1;       /* Positive */
 159                 }
 160         }
 161
 162         /*
 163          * Return success if got a positive match.  If there was a negative
 164          * match, we have already returned -1 and never get here.
 165          */
 166         return got_positive;
 167 }
 168
 169 /*
 170  * Tries to match the host name (which must be in all lowercase) against the
 171  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 172  * indicate negation).  Returns -1 if negation matches, 1 if there is
 173  * a positive match, 0 if there is no match at all.
 174  */
 175 int
 176 match_hostname(const char *host, const char *pattern, u_int len)
 177 {
 178         return match_pattern_list(host, pattern, len, 1);
 179 }
 180
 181 /*
 182  * returns 0 if we get a negative match for the hostname or the ip
 183  * or if we get no match at all.  returns 1 otherwise.
 184  */
 185 int
 186 match_host_and_ip(const char *host, const char *ipaddr,
 187     const char *patterns)
 188 {
 189         int mhost, mip;
 190
 191         /* negative ipaddr match */
 192         if ((mip = match_hostname(ipaddr, patterns, strlen(patterns))) == -1)
 193                 return 0;
 194         /* negative hostname match */
 195         if ((mhost = match_hostname(host, patterns, strlen(patterns))) == -1)
 196                 return 0;
 197         /* no match at all */
 198         if (mhost == 0 && mip == 0)
 199                 return 0;
 200         return 1;
 201 }
 202
 203 /*
 204  * match user, user@host_or_ip, user@host_or_ip_list against pattern
 205  */
 206 int
 207 match_user(const char *user, const char *host, const char *ipaddr,
 208     const char *pattern)
 209 {
 210         char *p, *pat;
 211         int ret;
 212
 213         if ((p = strchr(pattern,'@')) == NULL)
 214                 return match_pattern(user, pattern);
 215
 216         pat = xstrdup(pattern);
 217         p = strchr(pat, '@');
 218         *p++ = '\0';
 219
 220         if ((ret = match_pattern(user, pat)) == 1)
 221                 ret = match_host_and_ip(host, ipaddr, p);
 222         xfree(pat);
 223
 224         return ret;
 225 }
 226
 227 /*
 228  * Returns first item from client-list that is also supported by server-list,
 229  * caller must xfree() returned string.
 230  */
 231 #define MAX_PROP        40
 232 #define SEP     ","
 233 char *
 234 match_list(const char *client, const char *server, u_int *next)
 235 {
 236         char *sproposals[MAX_PROP];
 237         char *c, *s, *p, *ret, *cp, *sp;
 238         int i, j, nproposals;
 239
 240         c = cp = xstrdup(client);
 241         s = sp = xstrdup(server);
 242
 243         for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
 244             (p = strsep(&sp, SEP)), i++) {
 245                 if (i < MAX_PROP)
 246                         sproposals[i] = p;
 247                 else
 248                         break;
 249         }
 250         nproposals = i;
 251
 252         for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
 253             (p = strsep(&cp, SEP)), i++) {
 254                 for (j = 0; j < nproposals; j++) {
 255                         if (strcmp(p, sproposals[j]) == 0) {
 256                                 ret = xstrdup(p);
 257                                 if (next != NULL)
 258                                         *next = (cp == NULL) ?
 259                                             strlen(c) : (u_int)(cp - c);
 260                                 xfree(c);
 261                                 xfree(s);
 262                                 return ret;
 263                         }
 264                 }
 265         }
 266         if (next != NULL)
 267                 *next = strlen(c);
 268         xfree(c);
 269         xfree(s);
 270         return NULL;
 271 }