modules/metadata/mod_version.c

   1 /* Licensed to the Apache Software Foundation (ASF) under one or more
   2  * contributor license agreements.  See the NOTICE file distributed with
   3  * this work for additional information regarding copyright ownership.
   4  * The ASF licenses this file to You under the Apache License, Version 2.0
   5  * (the "License"); you may not use this file except in compliance with
   6  * the License.  You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 /*
  18  * mod_version.c
  19  * Allow conditional configuration depending on the httpd version
  20  *
  21  * André Malo (nd/perlig.de), January 2004
  22  *
  23  * Some stuff coded here is heavily based on the core <IfModule>
  24  * containers.
  25  *
  26  * The module makes the following confgurations possible:
  27  *
  28  * <IfVersion op major.minor.patch>
  29  *     # conditional config here ...
  30  *</IfVersion>
  31  *
  32  * where "op" is one of:
  33  * = / ==       equal
  34  * >            greater than
  35  * >=           greater or equal
  36  * <            less than
  37  * <=           less or equal
  38  *
  39  * If minor version and patch level are omitted they are assumed to be 0.
  40  *
  41  * Alternatively you can match the whole version (including some vendor-added
  42  * string of the CORE version, see ap_release.h) against a regular expression:
  43  *
  44  * <IfVersion op regex>
  45  *     # conditional config here ...
  46  *</IfVersion>
  47  *
  48  * where "op" is one of:
  49  * = / ==       match; regex must be surrounded by slashes
  50  * ~            match; regex MAY NOT be surrounded by slashes
  51  *
  52  * Note that all operators may be preceeded by an exclamation mark
  53  * (without spaces) in order to reverse their meaning.
  54  *
  55  */
  56
  57 #include "apr.h"
  58 #include "apr_strings.h"
  59 #include "apr_lib.h"
  60
  61 #include "httpd.h"
  62 #include "http_config.h"
  63 #include "http_log.h"
  64
  65
  66 /* module structure */
  67 module AP_MODULE_DECLARE_DATA version_module;
  68
  69 /* queried httpd version */
  70 static ap_version_t httpd_version;
  71
  72
  73 /*
  74  * compare the supplied version with the core one
  75  */
  76 static int compare_version(char *version_string, const char **error)
  77 {
  78     char *p = version_string, *ep;
  79     int version[3] = {0, 0, 0};
  80     int c = 0;
  81
  82     *error = "Version appears to be invalid. It must have the format "
  83              "major[.minor[.patch]] where major, minor and patch are "
  84              "numbers.";
  85
  86     if (!apr_isdigit(*p)) {
  87         return 0;
  88     }
  89
  90     /* parse supplied version */
  91     ep = version_string + strlen(version_string);
  92     while (p <= ep && c < 3) {
  93         if (*p == '.') {
  94             *p = '\0';
  95         }
  96
  97         if (!*p) {
  98             version[c++] = atoi(version_string);
  99             version_string = ++p;
 100             continue;
 101         }
 102
 103         if (!apr_isdigit(*p)) {
 104             break;
 105         }
 106
 107         ++p;
 108     }
 109
 110     if (p < ep) { /* syntax error */
 111         return 0;
 112     }
 113
 114     *error = NULL;
 115
 116     if      (httpd_version.major > version[0]) {
 117         return 1;
 118     }
 119     else if (httpd_version.major < version[0]) {
 120         return -1;
 121     }
 122     else if (httpd_version.minor > version[1]) {
 123         return 1;
 124     }
 125     else if (httpd_version.minor < version[1]) {
 126         return -1;
 127     }
 128     else if (httpd_version.patch > version[2]) {
 129         return 1;
 130     }
 131     else if (httpd_version.patch < version[2]) {
 132         return -1;
 133     }
 134
 135     /* seems to be the same */
 136     return 0;
 137 }
 138
 139 /*
 140  * match version against a regular expression
 141  */
 142 static int match_version(apr_pool_t *pool, char *version_string,
 143                          const char **error)
 144 {
 145     ap_regex_t *compiled;
 146     const char *to_match;
 147     int rc;
 148
 149     compiled = ap_pregcomp(pool, version_string, AP_REG_EXTENDED);
 150     if (!compiled) {
 151         *error = "Unable to compile regular expression";
 152         return 0;
 153     }
 154
 155     *error = NULL;
 156
 157     to_match = apr_psprintf(pool, "%d.%d.%d%s",
 158                             httpd_version.major,
 159                             httpd_version.minor,
 160                             httpd_version.patch,
 161                             httpd_version.add_string);
 162
 163     rc = !ap_regexec(compiled, to_match, 0, NULL, 0);
 164
 165     ap_pregfree(pool, compiled);
 166     return rc;
 167 }
 168
 169 /*
 170  * Implements the <IfVersion> container
 171  */
 172 static const char *start_ifversion(cmd_parms *cmd, void *mconfig,
 173                                    const char *arg1, const char *arg2,
 174                                    const char *arg3)
 175 {
 176     const char *endp;
 177     int reverse = 0, done = 0, match = 0, compare;
 178     const char *p, *error;
 179     char c;
 180
 181     /* supplying one argument is possible, we assume an equality check then */
 182     if (!arg2) {
 183         arg2 = arg1;
 184         arg1 = "=";
 185     }
 186
 187     /* surrounding quotes without operator */
 188     if (!arg3 && *arg2 == '>' && !arg2[1]) {
 189         arg3 = ">";
 190         arg2 = arg1;
 191         arg1 = "=";
 192     }
 193
 194     /* the third argument makes version surrounding quotes plus operator
 195      * possible.
 196      */
 197     endp = arg2 + strlen(arg2);
 198     if (   endp == arg2
 199         || (!(arg3 && *arg3 == '>' && !arg3[1]) && *--endp != '>')) {
 200         return apr_pstrcat(cmd->pool, cmd->cmd->name,
 201                            "> directive missing closing '>'", NULL);
 202     }
 203
 204     p = arg1;
 205     if (*p == '!') {
 206         reverse = 1;
 207         if (p[1]) {
 208             ++p;
 209         }
 210     }
 211
 212     c = *p++;
 213     if (!*p || (*p == '=' && !p[1] && c != '~')) {
 214         if (!httpd_version.major) {
 215             ap_get_server_revision(&httpd_version);
 216         }
 217
 218         done = 1;
 219         switch (c) {
 220         case '=':
 221             /* normal comparison */
 222             if (*arg2 != '/') {
 223                 compare = compare_version(apr_pstrmemdup(cmd->pool, arg2,
 224                                                          endp-arg2),
 225                                           &error);
 226                 if (error) {
 227                     return error;
 228                 }
 229
 230                 match = !compare;
 231                 break;
 232             }
 233
 234             /* regexp otherwise */
 235             if (endp == ++arg2 || *--endp != '/') {
 236                 return "Missing delimiting / of regular expression.";
 237             }
 238
 239         case '~':
 240             /* regular expression */
 241             match = match_version(cmd->pool, apr_pstrmemdup(cmd->pool, arg2,
 242                                                             endp-arg2),
 243                                   &error);
 244             if (error) {
 245                 return error;
 246             }
 247             break;
 248
 249         case '<':
 250             compare = compare_version(apr_pstrmemdup(cmd->pool, arg2,
 251                                                      endp-arg2),
 252                                       &error);
 253             if (error) {
 254                 return error;
 255             }
 256
 257             match = ((-1 == compare) || (*p && !compare));
 258             break;
 259
 260         case '>':
 261             compare = compare_version(apr_pstrmemdup(cmd->pool, arg2,
 262                                                      endp-arg2),
 263                                       &error);
 264             if (error) {
 265                 return error;
 266             }
 267
 268             match = ((1 == compare) || (*p && !compare));
 269             break;
 270
 271         default:
 272             done = 0;
 273             break;
 274         }
 275     }
 276
 277     if (!done) {
 278         return apr_pstrcat(cmd->pool, "unrecognized operator '", arg1, "'",
 279                            NULL);
 280     }
 281
 282     if ((!reverse && match) || (reverse && !match)) {
 283         ap_directive_t *parent = NULL;
 284         ap_directive_t *current = NULL;
 285         const char *retval;
 286
 287         retval = ap_build_cont_config(cmd->pool, cmd->temp_pool, cmd,
 288                                       &current, &parent, "<IfVersion");
 289         *(ap_directive_t **)mconfig = current;
 290         return retval;
 291     }
 292
 293     *(ap_directive_t **)mconfig = NULL;
 294     return ap_soak_end_container(cmd, "<IfVersion");
 295 }
 296
 297 static const command_rec version_cmds[] = {
 298     AP_INIT_TAKE123("<IfVersion", start_ifversion, NULL, EXEC_ON_READ | OR_ALL,
 299                     "a comparison operator, a version (and a delimiter)"),
 300     { NULL }
 301 };
 302
 303 module AP_MODULE_DECLARE_DATA version_module =
 304 {
 305     STANDARD20_MODULE_STUFF,
 306     NULL,             /* dir config creater */
 307     NULL,             /* dir merger --- default is to override */
 308     NULL,             /* server config */
 309     NULL,             /* merge server configs */
 310     version_cmds,     /* command apr_table_t */
 311     NULL,             /* register hooks */
 312 };