match.c

   1 /* $OpenBSD: match.c,v 1.25 2006/07/22 20:48:23 stevesk 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 #include <string.h>
  42
  43 #include "match.h"
  44 #include "xmalloc.h"
  45
  46 /*
  47  * Returns true if the given string matches the pattern (which may contain ?
  48  * and * as wildcards), and zero if it does not match.
  49  */
  50
  51 int
  52 match_pattern(const char *s, const char *pattern)
  53 {
  54         for (;;) {
  55                 /* If at end of pattern, accept if also at end of string. */
  56                 if (!*pattern)
  57                         return !*s;
  58
  59                 if (*pattern == '*') {
  60                         /* Skip the asterisk. */
  61                         pattern++;
  62
  63                         /* If at end of pattern, accept immediately. */
  64                         if (!*pattern)
  65                                 return 1;
  66
  67                         /* If next character in pattern is known, optimize. */
  68                         if (*pattern != '?' && *pattern != '*') {
  69                                 /*
  70                                  * Look instances of the next character in
  71                                  * pattern, and try to match starting from
  72                                  * those.
  73                                  */
  74                                 for (; *s; s++)
  75                                         if (*s == *pattern &&
  76                                             match_pattern(s + 1, pattern + 1))
  77                                                 return 1;
  78                                 /* Failed. */
  79                                 return 0;
  80                         }
  81                         /*
  82                          * Move ahead one character at a time and try to
  83                          * match at each position.
  84                          */
  85                         for (; *s; s++)
  86                                 if (match_pattern(s, pattern))
  87                                         return 1;
  88                         /* Failed. */
  89                         return 0;
  90                 }
  91                 /*
  92                  * There must be at least one more character in the string.
  93                  * If we are at the end, fail.
  94                  */
  95                 if (!*s)
  96                         return 0;
  97
  98                 /* Check if the next character of the string is acceptable. */
  99                 if (*pattern != '?' && *pattern != *s)
 100                         return 0;
 101
 102                 /* Move to the next character, both in string and in pattern. */
 103                 s++;
 104                 pattern++;
 105         }
 106         /* NOTREACHED */
 107 }
 108
 109 /*
 110  * Tries to match the string against the
 111  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 112  * indicate negation).  Returns -1 if negation matches, 1 if there is
 113  * a positive match, 0 if there is no match at all.
 114  */
 115
 116 int
 117 match_pattern_list(const char *string, const char *pattern, u_int len,
 118     int dolower)
 119 {
 120         char sub[1024];
 121         int negated;
 122         int got_positive;
 123         u_int i, subi;
 124
 125         got_positive = 0;
 126         for (i = 0; i < len;) {
 127                 /* Check if the subpattern is negated. */
 128                 if (pattern[i] == '!') {
 129                         negated = 1;
 130                         i++;
 131                 } else
 132                         negated = 0;
 133
 134                 /*
 135                  * Extract the subpattern up to a comma or end.  Convert the
 136                  * subpattern to lowercase.
 137                  */
 138                 for (subi = 0;
 139                     i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
 140                     subi++, i++)
 141                         sub[subi] = dolower && isupper(pattern[i]) ?
 142                             (char)tolower(pattern[i]) : pattern[i];
 143                 /* If subpattern too long, return failure (no match). */
 144                 if (subi >= sizeof(sub) - 1)
 145                         return 0;
 146
 147                 /* If the subpattern was terminated by a comma, skip the comma. */
 148                 if (i < len && pattern[i] == ',')
 149                         i++;
 150
 151                 /* Null-terminate the subpattern. */
 152                 sub[subi] = '\0';
 153
 154                 /* Try to match the subpattern against the string. */
 155                 if (match_pattern(string, sub)) {
 156                         if (negated)
 157                                 return -1;              /* Negative */
 158                         else
 159                                 got_positive = 1;       /* Positive */
 160                 }
 161         }
 162
 163         /*
 164          * Return success if got a positive match.  If there was a negative
 165          * match, we have already returned -1 and never get here.
 166          */
 167         return got_positive;
 168 }
 169
 170 /*
 171  * Tries to match the host name (which must be in all lowercase) against the
 172  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 173  * indicate negation).  Returns -1 if negation matches, 1 if there is
 174  * a positive match, 0 if there is no match at all.
 175  */
 176 int
 177 match_hostname(const char *host, const char *pattern, u_int len)
 178 {
 179         return match_pattern_list(host, pattern, len, 1);
 180 }
 181
 182 /*
 183  * returns 0 if we get a negative match for the hostname or the ip
 184  * or if we get no match at all.  returns 1 otherwise.
 185  */
 186 int
 187 match_host_and_ip(const char *host, const char *ipaddr,
 188     const char *patterns)
 189 {
 190         int mhost, mip;
 191
 192         /* negative ipaddr match */
 193         if ((mip = match_hostname(ipaddr, patterns, strlen(patterns))) == -1)
 194                 return 0;
 195         /* negative hostname match */
 196         if ((mhost = match_hostname(host, patterns, strlen(patterns))) == -1)
 197                 return 0;
 198         /* no match at all */
 199         if (mhost == 0 && mip == 0)
 200                 return 0;
 201         return 1;
 202 }
 203
 204 /*
 205  * match user, user@host_or_ip, user@host_or_ip_list against pattern
 206  */
 207 int
 208 match_user(const char *user, const char *host, const char *ipaddr,
 209     const char *pattern)
 210 {
 211         char *p, *pat;
 212         int ret;
 213
 214         if ((p = strchr(pattern,'@')) == NULL)
 215                 return match_pattern(user, pattern);
 216
 217         pat = xstrdup(pattern);
 218         p = strchr(pat, '@');
 219         *p++ = '\0';
 220
 221         if ((ret = match_pattern(user, pat)) == 1)
 222                 ret = match_host_and_ip(host, ipaddr, p);
 223         xfree(pat);
 224
 225         return ret;
 226 }
 227
 228 /*
 229  * Returns first item from client-list that is also supported by server-list,
 230  * caller must xfree() returned string.
 231  */
 232 #define MAX_PROP        40
 233 #define SEP     ","
 234 char *
 235 match_list(const char *client, const char *server, u_int *next)
 236 {
 237         char *sproposals[MAX_PROP];
 238         char *c, *s, *p, *ret, *cp, *sp;
 239         int i, j, nproposals;
 240
 241         c = cp = xstrdup(client);
 242         s = sp = xstrdup(server);
 243
 244         for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
 245             (p = strsep(&sp, SEP)), i++) {
 246                 if (i < MAX_PROP)
 247                         sproposals[i] = p;
 248                 else
 249                         break;
 250         }
 251         nproposals = i;
 252
 253         for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
 254             (p = strsep(&cp, SEP)), i++) {
 255                 for (j = 0; j < nproposals; j++) {
 256                         if (strcmp(p, sproposals[j]) == 0) {
 257                                 ret = xstrdup(p);
 258                                 if (next != NULL)
 259                                         *next = (cp == NULL) ?
 260                                             strlen(c) : (u_int)(cp - c);
 261                                 xfree(c);
 262                                 xfree(s);
 263                                 return ret;
 264                         }
 265                 }
 266         }
 267         if (next != NULL)
 268                 *next = strlen(c);
 269         xfree(c);
 270         xfree(s);
 271         return NULL;
 272 }