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/* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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#include "apr_file_io.h"
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#include "apr_strings.h"
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#define APR_WANT_STRFUNC
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#define WANT_BASENAME_MATCH
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#include "http_core.h"
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#include "http_config.h"
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#include "http_request.h"
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/* mod_speling.c - by Alexei Kosut <akosut@organic.com> June, 1996
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* This module is transparent, and simple. It attempts to correct
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* misspellings of URLs that users might have entered, namely by checking
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* capitalizations. If it finds a match, it sends a redirect.
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* Sep-1999 Hugo Haas <hugo@w3.org>
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* o Added a CheckCaseOnly option to check only miscapitalized words.
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* 08-Aug-1997 <Martin.Kraemer@Mch.SNI.De>
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* o Upgraded module interface to apache_1.3a2-dev API (more NULL's in
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* o Integrated tcsh's "spelling correction" routine which allows one
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* misspelling (character insertion/omission/typo/transposition).
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* Rewrote it to ignore case as well. This ought to catch the majority
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* of misspelled requests.
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* o Commented out the second pass where files' suffixes are stripped.
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* Given the better hit rate of the first pass, this rather ugly
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* (request index.html, receive index.db ?!?!) solution can be
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* o wrote a "kind of" html page for mod_speling
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* Activate it with "CheckSpelling On"
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module AP_MODULE_DECLARE_DATA speling_module;
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* Create a configuration specific to this module for a server or directory
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* location, and fill it with the default settings.
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* The API says that in the absence of a merge function, the record for the
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* closest ancestor is used exclusively. That's what we want, so we don't
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* bother to have such a function.
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static void *mkconfig(apr_pool_t *p)
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spconfig *cfg = apr_pcalloc(p, sizeof(spconfig));
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* Respond to a callback to create configuration record for a server or
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static void *create_mconfig_for_server(apr_pool_t *p, server_rec *s)
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* Respond to a callback to create a config record for a specific directory.
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static void *create_mconfig_for_directory(apr_pool_t *p, char *dir)
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* Define the directives specific to this module. This structure is referenced
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* later by the 'module' structure.
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static const command_rec speling_cmds[] =
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AP_INIT_FLAG("CheckSpelling", ap_set_flag_slot,
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(void*)APR_OFFSETOF(spconfig, enabled), OR_OPTIONS,
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"whether or not to fix miscapitalized/misspelled requests"),
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AP_INIT_FLAG("CheckCaseOnly", ap_set_flag_slot,
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(void*)APR_OFFSETOF(spconfig, case_only), OR_OPTIONS,
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"whether or not to fix only miscapitalized requests"),
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SP_MISCAPITALIZED = 1,
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SP_TRANSPOSITION = 2,
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static const char *sp_reason_str[] =
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"transposed characters",
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"mistyped character",
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* spdist() is taken from Kernighan & Pike,
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* _The_UNIX_Programming_Environment_
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* and adapted somewhat to correspond better to psychological reality.
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* (Note the changes to the return values)
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* According to Pollock and Zamora, CACM April 1984 (V. 27, No. 4),
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* page 363, the correct order for this is:
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* OMISSION = TRANSPOSITION > INSERTION > SUBSTITUTION
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* thus, it was exactly backwards in the old version. -- PWP
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* This routine was taken out of tcsh's spelling correction code
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* (tcsh-6.07.04) and re-converted to apache data types ("char" type
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* instead of tcsh's NLS'ed "Char"). Plus it now ignores the case
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* during comparisons, so is a "approximate strcasecmp()".
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* NOTE that is still allows only _one_ real "typo",
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* it does NOT try to correct multiple errors.
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static sp_reason spdist(const char *s, const char *t)
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for (; apr_tolower(*s) == apr_tolower(*t); t++, s++) {
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return SP_MISCAPITALIZED; /* exact match (sans case) */
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if (s[1] && t[1] && apr_tolower(*s) == apr_tolower(t[1])
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&& apr_tolower(*t) == apr_tolower(s[1])
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&& strcasecmp(s + 2, t + 2) == 0) {
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return SP_TRANSPOSITION; /* transposition */
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if (strcasecmp(s + 1, t + 1) == 0) {
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return SP_SIMPLETYPO; /* 1 char mismatch */
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if (strcasecmp(s + 1, t) == 0) {
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return SP_EXTRACHAR; /* extra character */
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if (*t && strcasecmp(s, t + 1) == 0) {
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return SP_MISSINGCHAR; /* missing character */
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return SP_VERYDIFFERENT; /* distance too large to fix. */
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static int sort_by_quality(const void *left, const void *rite)
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return (int) (((misspelled_file *) left)->quality)
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- (int) (((misspelled_file *) rite)->quality);
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static int check_speling(request_rec *r)
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char *good, *bad, *postgood, *url;
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int filoc, dotloc, urlen, pglen;
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apr_array_header_t *candidates = NULL;
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cfg = ap_get_module_config(r->per_dir_config, &speling_module);
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/* We only want to worry about GETs */
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if (r->method_number != M_GET) {
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/* We've already got a file of some kind or another */
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if (r->finfo.filetype != 0) {
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/* Not a file request */
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if (r->proxyreq || !r->filename) {
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/* This is a sub request - don't mess with it */
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/* we default to reject path info (same as core handler) */
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if ((r->used_path_info != AP_REQ_ACCEPT_PATH_INFO) &&
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r->path_info && *r->path_info) {
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* The request should end up looking like this:
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* r->uri: /correct-url/mispelling/more
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* r->filename: /correct-file/mispelling r->path_info: /more
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* So we do this in steps. First break r->filename into two pieces
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filoc = ap_rind(r->filename, '/');
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* Don't do anything if the request doesn't contain a slash, or
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if (filoc == -1 || strcmp(r->uri, "/") == 0) {
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/* good = /correct-file */
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good = apr_pstrndup(r->pool, r->filename, filoc);
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/* bad = mispelling */
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bad = apr_pstrdup(r->pool, r->filename + filoc + 1);
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/* postgood = mispelling/more */
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postgood = apr_pstrcat(r->pool, bad, r->path_info, NULL);
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urlen = strlen(r->uri);
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pglen = strlen(postgood);
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/* Check to see if the URL pieces add up */
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if (strcmp(postgood, r->uri + (urlen - pglen))) {
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/* url = /correct-url */
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url = apr_pstrndup(r->pool, r->uri, (urlen - pglen));
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/* Now open the directory and do ourselves a check... */
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if (apr_dir_open(&dir, good, r->pool) != APR_SUCCESS) {
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/* Oops, not a directory... */
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candidates = apr_array_make(r->pool, 2, sizeof(misspelled_file));
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dotloc = ap_ind(bad, '.');
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dotloc = strlen(bad);
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while (apr_dir_read(&dirent, APR_FINFO_DIRENT, dir) == APR_SUCCESS) {
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* If we end up with a "fixed" URL which is identical to the
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* requested one, we must have found a broken symlink or some such.
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* Do _not_ try to redirect this, it causes a loop!
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if (strcmp(bad, dirent.name) == 0) {
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* miscapitalization errors are checked first (like, e.g., lower case
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* file, upper case request)
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else if (strcasecmp(bad, dirent.name) == 0) {
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misspelled_file *sp_new;
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sp_new = (misspelled_file *) apr_array_push(candidates);
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sp_new->name = apr_pstrdup(r->pool, dirent.name);
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sp_new->quality = SP_MISCAPITALIZED;
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* simple typing errors are checked next (like, e.g.,
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* missing/extra/transposed char)
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else if ((cfg->case_only == 0)
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&& ((q = spdist(bad, dirent.name)) != SP_VERYDIFFERENT)) {
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misspelled_file *sp_new;
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sp_new = (misspelled_file *) apr_array_push(candidates);
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sp_new->name = apr_pstrdup(r->pool, dirent.name);
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* The spdist() should have found the majority of the misspelled
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* requests. It is of questionable use to continue looking for
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* files with the same base name, but potentially of totally wrong
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* type (index.html <-> index.db).
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* I would propose to not set the WANT_BASENAME_MATCH define.
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* 08-Aug-1997 <Martin.Kraemer@Mch.SNI.De>
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* However, Alexei replied giving some reasons to add it anyway:
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* > Oh, by the way, I remembered why having the
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* > extension-stripping-and-matching stuff is a good idea:
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* > If you're using MultiViews, and have a file named foobar.html,
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* > which you refer to as "foobar", and someone tried to access
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* > "Foobar", mod_speling won't find it, because it won't find
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* > anything matching that spelling. With the extension-munging,
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* > it would locate "foobar.html". Not perfect, but I ran into
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* > that problem when I first wrote the module.
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#ifdef WANT_BASENAME_MATCH
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* Okay... we didn't find anything. Now we take out the hard-core
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* power tools. There are several cases here. Someone might have
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* entered a wrong extension (.htm instead of .html or vice
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* versa) or the document could be negotiated. At any rate, now
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* we just compare stuff before the first dot. If it matches, we
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* figure we got us a match. This can result in wrong things if
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* there are files of different content types but the same prefix
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* (e.g. foo.gif and foo.html) This code will pick the first one
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* it finds. Better than a Not Found, though.
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int entloc = ap_ind(dirent.name, '.');
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entloc = strlen(dirent.name);
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if ((dotloc == entloc)
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&& !strncasecmp(bad, dirent.name, dotloc)) {
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misspelled_file *sp_new;
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sp_new = (misspelled_file *) apr_array_push(candidates);
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sp_new->name = apr_pstrdup(r->pool, dirent.name);
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sp_new->quality = SP_VERYDIFFERENT;
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if (candidates->nelts != 0) {
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/* Wow... we found us a mispelling. Construct a fixed url */
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misspelled_file *variant = (misspelled_file *) candidates->elts;
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ref = apr_table_get(r->headers_in, "Referer");
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qsort((void *) candidates->elts, candidates->nelts,
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sizeof(misspelled_file), sort_by_quality);
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* Conditions for immediate redirection:
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* a) the first candidate was not found by stripping the suffix
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* AND b) there exists only one candidate OR the best match is not
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* then return a redirection right away.
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if (variant[0].quality != SP_VERYDIFFERENT
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&& (candidates->nelts == 1
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|| variant[0].quality != variant[1].quality)) {
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nuri = ap_escape_uri(r->pool, apr_pstrcat(r->pool, url,
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r->path_info, NULL));
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if (r->parsed_uri.query)
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nuri = apr_pstrcat(r->pool, nuri, "?", r->parsed_uri.query, NULL);
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apr_table_setn(r->headers_out, "Location",
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ap_construct_url(r->pool, nuri, r));
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ap_log_rerror(APLOG_MARK, APLOG_INFO, APR_SUCCESS,
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ref ? "Fixed spelling: %s to %s from %s"
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: "Fixed spelling: %s to %s",
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return HTTP_MOVED_PERMANENTLY;
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* Otherwise, a "[300] Multiple Choices" list with the variants is
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apr_pool_t *sub_pool;
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apr_array_header_t *t;
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apr_array_header_t *v;
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if (r->main == NULL) {
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notes = r->main->notes;
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if (apr_pool_create(&sub_pool, p) != APR_SUCCESS)
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t = apr_array_make(sub_pool, candidates->nelts * 8 + 8,
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v = apr_array_make(sub_pool, candidates->nelts * 5,
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/* Generate the response text. */
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*(const char **)apr_array_push(t) =
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"The document name you requested (<code>";
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*(const char **)apr_array_push(t) = ap_escape_html(sub_pool, r->uri);
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*(const char **)apr_array_push(t) =
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"</code>) could not be found on this server.\n"
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"However, we found documents with names similar "
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"to the one you requested.<p>"
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"Available documents:\n<ul>\n";
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for (i = 0; i < candidates->nelts; ++i) {
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reason = sp_reason_str[(int) (variant[i].quality)];
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/* The format isn't very neat... */
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vuri = apr_pstrcat(sub_pool, url, variant[i].name, r->path_info,
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(r->parsed_uri.query != NULL) ? "?" : "",
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(r->parsed_uri.query != NULL)
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? r->parsed_uri.query : "",
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*(const char **)apr_array_push(v) = "\"";
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*(const char **)apr_array_push(v) = ap_escape_uri(sub_pool, vuri);
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*(const char **)apr_array_push(v) = "\";\"";
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*(const char **)apr_array_push(v) = reason;
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*(const char **)apr_array_push(v) = "\"";
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*(const char **)apr_array_push(t) = "<li><a href=\"";
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*(const char **)apr_array_push(t) = ap_escape_uri(sub_pool, vuri);
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*(const char **)apr_array_push(t) = "\">";
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*(const char **)apr_array_push(t) = ap_escape_html(sub_pool, vuri);
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*(const char **)apr_array_push(t) = "</a> (";
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*(const char **)apr_array_push(t) = reason;
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*(const char **)apr_array_push(t) = ")\n";
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* when we have printed the "close matches" and there are
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* more "distant matches" (matched by stripping the suffix),
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* then we insert an additional separator text to suggest
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* that the user LOOK CLOSELY whether these are really the
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if (i > 0 && i < candidates->nelts - 1
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&& variant[i].quality != SP_VERYDIFFERENT
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&& variant[i + 1].quality == SP_VERYDIFFERENT) {
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*(const char **)apr_array_push(t) =
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"</ul>\nFurthermore, the following related "
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"documents were found:\n<ul>\n";
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*(const char **)apr_array_push(t) = "</ul>\n";
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/* If we know there was a referring page, add a note: */
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*(const char **)apr_array_push(t) =
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"Please consider informing the owner of the "
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*(const char **)apr_array_push(t) = ap_escape_uri(sub_pool, ref);
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*(const char **)apr_array_push(t) = "\">referring page</a> "
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"about the broken link.\n";
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/* Pass our apr_table_t to http_protocol.c (see mod_negotiation): */
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apr_table_setn(notes, "variant-list", apr_array_pstrcat(p, t, 0));
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apr_table_mergen(r->subprocess_env, "VARIANTS",
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apr_array_pstrcat(p, v, ','));
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apr_pool_destroy(sub_pool);
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ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
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ref ? "Spelling fix: %s: %d candidates from %s"
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: "Spelling fix: %s: %d candidates",
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r->uri, candidates->nelts, ref);
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return HTTP_MULTIPLE_CHOICES;
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static void register_hooks(apr_pool_t *p)
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ap_hook_fixups(check_speling,NULL,NULL,APR_HOOK_LAST);
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module AP_MODULE_DECLARE_DATA speling_module =
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STANDARD20_MODULE_STUFF,
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create_mconfig_for_directory, /* create per-dir config */
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NULL, /* merge per-dir config */
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create_mconfig_for_server, /* server config */
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NULL, /* merge server config */
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speling_cmds, /* command apr_table_t */
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register_hooks /* register hooks */
added
removed
modules/mappers/mod_speling.c
