match.c

   1 /* $OpenBSD: match.c,v 1.27 2008/06/10 23:06:19 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 <sys/types.h>
  41
  42 #include <ctype.h>
  43 #include <string.h>
  44
  45 #include "xmalloc.h"
  46 #include "match.h"
  47
  48 /*
  49  * Returns true if the given string matches the pattern (which may contain ?
  50  * and * as wildcards), and zero if it does not match.
  51  */
  52
  53 int
  54 match_pattern(const char *s, const char *pattern)
  55 {
  56         for (;;) {
  57                 /* If at end of pattern, accept if also at end of string. */
  58                 if (!*pattern)
  59                         return !*s;
  60
  61                 if (*pattern == '*') {
  62                         /* Skip the asterisk. */
  63                         pattern++;
  64
  65                         /* If at end of pattern, accept immediately. */
  66                         if (!*pattern)
  67                                 return 1;
  68
  69                         /* If next character in pattern is known, optimize. */
  70                         if (*pattern != '?' && *pattern != '*') {
  71                                 /*
  72                                  * Look instances of the next character in
  73                                  * pattern, and try to match starting from
  74                                  * those.
  75                                  */
  76                                 for (; *s; s++)
  77                                         if (*s == *pattern &&
  78                                             match_pattern(s + 1, pattern + 1))
  79                                                 return 1;
  80                                 /* Failed. */
  81                                 return 0;
  82                         }
  83                         /*
  84                          * Move ahead one character at a time and try to
  85                          * match at each position.
  86                          */
  87                         for (; *s; s++)
  88                                 if (match_pattern(s, pattern))
  89                                         return 1;
  90                         /* Failed. */
  91                         return 0;
  92                 }
  93                 /*
  94                  * There must be at least one more character in the string.
  95                  * If we are at the end, fail.
  96                  */
  97                 if (!*s)
  98                         return 0;
  99
 100                 /* Check if the next character of the string is acceptable. */
 101                 if (*pattern != '?' && *pattern != *s)
 102                         return 0;
 103
 104                 /* Move to the next character, both in string and in pattern. */
 105                 s++;
 106                 pattern++;
 107         }
 108         /* NOTREACHED */
 109 }
 110
 111 /*
 112  * Tries to match the string against the
 113  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 114  * indicate negation).  Returns -1 if negation matches, 1 if there is
 115  * a positive match, 0 if there is no match at all.
 116  */
 117
 118 int
 119 match_pattern_list(const char *string, const char *pattern, u_int len,
 120     int dolower)
 121 {
 122         char sub[1024];
 123         int negated;
 124         int got_positive;
 125         u_int i, subi;
 126
 127         got_positive = 0;
 128         for (i = 0; i < len;) {
 129                 /* Check if the subpattern is negated. */
 130                 if (pattern[i] == '!') {
 131                         negated = 1;
 132                         i++;
 133                 } else
 134                         negated = 0;
 135
 136                 /*
 137                  * Extract the subpattern up to a comma or end.  Convert the
 138                  * subpattern to lowercase.
 139                  */
 140                 for (subi = 0;
 141                     i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
 142                     subi++, i++)
 143                         sub[subi] = dolower && isupper(pattern[i]) ?
 144                             (char)tolower(pattern[i]) : pattern[i];
 145                 /* If subpattern too long, return failure (no match). */
 146                 if (subi >= sizeof(sub) - 1)
 147                         return 0;
 148
 149                 /* If the subpattern was terminated by a comma, skip the comma. */
 150                 if (i < len && pattern[i] == ',')
 151                         i++;
 152
 153                 /* Null-terminate the subpattern. */
 154                 sub[subi] = '\0';
 155
 156                 /* Try to match the subpattern against the string. */
 157                 if (match_pattern(string, sub)) {
 158                         if (negated)
 159                                 return -1;              /* Negative */
 160                         else
 161                                 got_positive = 1;       /* Positive */
 162                 }
 163         }
 164
 165         /*
 166          * Return success if got a positive match.  If there was a negative
 167          * match, we have already returned -1 and never get here.
 168          */
 169         return got_positive;
 170 }
 171
 172 /*
 173  * Tries to match the host name (which must be in all lowercase) against the
 174  * comma-separated sequence of subpatterns (each possibly preceded by ! to
 175  * indicate negation).  Returns -1 if negation matches, 1 if there is
 176  * a positive match, 0 if there is no match at all.
 177  */
 178 int
 179 match_hostname(const char *host, const char *pattern, u_int len)
 180 {
 181         return match_pattern_list(host, pattern, len, 1);
 182 }
 183
 184 /*
 185  * returns 0 if we get a negative match for the hostname or the ip
 186  * or if we get no match at all.  returns -1 on error, or 1 on
 187  * successful match.
 188  */
 189 int
 190 match_host_and_ip(const char *host, const char *ipaddr,
 191     const char *patterns)
 192 {
 193         int mhost, mip;
 194
 195         /* error in ipaddr match */
 196         if ((mip = addr_match_list(ipaddr, patterns)) == -2)
 197                 return -1;
 198         else if (mip == -1) /* negative ip address match */
 199                 return 0;
 200
 201         /* negative hostname match */
 202         if ((mhost = match_hostname(host, patterns, strlen(patterns))) == -1)
 203                 return 0;
 204         /* no match at all */
 205         if (mhost == 0 && mip == 0)
 206                 return 0;
 207         return 1;
 208 }
 209
 210 /*
 211  * match user, user@host_or_ip, user@host_or_ip_list against pattern
 212  */
 213 int
 214 match_user(const char *user, const char *host, const char *ipaddr,
 215     const char *pattern)
 216 {
 217         char *p, *pat;
 218         int ret;
 219
 220         if ((p = strchr(pattern,'@')) == NULL)
 221                 return match_pattern(user, pattern);
 222
 223         pat = xstrdup(pattern);
 224         p = strchr(pat, '@');
 225         *p++ = '\0';
 226
 227         if ((ret = match_pattern(user, pat)) == 1)
 228                 ret = match_host_and_ip(host, ipaddr, p);
 229         xfree(pat);
 230
 231         return ret;
 232 }
 233
 234 /*
 235  * Returns first item from client-list that is also supported by server-list,
 236  * caller must xfree() returned string.
 237  */
 238 #define MAX_PROP        40
 239 #define SEP     ","
 240 char *
 241 match_list(const char *client, const char *server, u_int *next)
 242 {
 243         char *sproposals[MAX_PROP];
 244         char *c, *s, *p, *ret, *cp, *sp;
 245         int i, j, nproposals;
 246
 247         c = cp = xstrdup(client);
 248         s = sp = xstrdup(server);
 249
 250         for ((p = strsep(&sp, SEP)), i=0; p && *p != '\0';
 251             (p = strsep(&sp, SEP)), i++) {
 252                 if (i < MAX_PROP)
 253                         sproposals[i] = p;
 254                 else
 255                         break;
 256         }
 257         nproposals = i;
 258
 259         for ((p = strsep(&cp, SEP)), i=0; p && *p != '\0';
 260             (p = strsep(&cp, SEP)), i++) {
 261                 for (j = 0; j < nproposals; j++) {
 262                         if (strcmp(p, sproposals[j]) == 0) {
 263                                 ret = xstrdup(p);
 264                                 if (next != NULL)
 265                                         *next = (cp == NULL) ?
 266                                             strlen(c) : (u_int)(cp - c);
 267                                 xfree(c);
 268                                 xfree(s);
 269                                 return ret;
 270                         }
 271                 }
 272         }
 273         if (next != NULL)
 274                 *next = strlen(c);
 275         xfree(c);
 276         xfree(s);
 277         return NULL;
 278 }