Quelle mod_speling.c Sprache: C

/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License.  You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

#include "apr.h"
#include "apr_file_io.h"
#include "apr_strings.h"
#include "apr_lib.h"

#define APR_WANT_STRFUNC
#include "apr_want.h"

#include "httpd.h"
#include "http_core.h"
#include "http_config.h"
#include "http_request.h"
#include "http_log.h"

/* mod_speling.c - by Alexei Kosut <akosut@organic.com> June, 1996
*
* This module is transparent, and simple. It attempts to correct
* misspellings of URLs that users might have entered, namely by checking
* capitalizations. If it finds a match, it sends a redirect.
*
* Sep-1999 Hugo Haas <hugo@w3.org>
* o Added a CheckCaseOnly option to check only miscapitalized words.
*
* 08-Aug-1997 <Martin.Kraemer@Mch.SNI.De>
* o Upgraded module interface to apache_1.3a2-dev API (more NULL's in
*   speling_module).
* o Integrated tcsh's "spelling correction" routine which allows one
*   misspelling (character insertion/omission/typo/transposition).
*   Rewrote it to ignore case as well. This ought to catch the majority
*   of misspelled requests.
* o Commented out the second pass where files' suffixes are stripped.
*   Given the better hit rate of the first pass, this rather ugly
*   (request index.html, receive index.db ?!?!) solution can be
*   omitted.
* o wrote a "kind of" html page for mod_speling
*
* Activate it with "CheckSpelling On"
*/

module AP_MODULE_DECLARE_DATA speling_module;

typedef struct {
    int enabled;
    int check_case_only;
    int check_basename_match;
} spconfig;

/*
* Create a configuration specific to this module for a server or directory
* location, and fill it with the default settings.
*
* The API says that in the absence of a merge function, the record for the
* closest ancestor is used exclusively.  That's what we want, so we don't
* bother to have such a function.
*/

static void *mkconfig(apr_pool_t *p)
{
    spconfig *cfg = apr_pcalloc(p, sizeof(spconfig));

    cfg->enabled = 0;
    cfg->check_case_only = 0;
    cfg->check_basename_match = 1;
    return cfg;
}

/*
* Respond to a callback to create configuration record for a server or
* vhost environment.
*/
static void *create_mconfig_for_server(apr_pool_t *p, server_rec *s)
{
    return mkconfig(p);
}

/*
* Respond to a callback to create a config record for a specific directory.
*/
static void *create_mconfig_for_directory(apr_pool_t *p, char *dir)
{
    return mkconfig(p);
}

/*
* Define the directives specific to this module.  This structure is referenced
* later by the 'module' structure.
*/
static const command_rec speling_cmds[] =
{
    AP_INIT_FLAG("CheckSpelling", ap_set_flag_slot,
                  (void*)APR_OFFSETOF(spconfig, enabled), OR_OPTIONS,
                 "whether or not to fix miscapitalized/misspelled requests"),
    AP_INIT_FLAG("CheckCaseOnly", ap_set_flag_slot,
                  (void*)APR_OFFSETOF(spconfig, check_case_only), OR_OPTIONS,
                 "whether or not to fix only miscapitalized requests"),
    AP_INIT_FLAG("CheckBasenameMatch", ap_set_flag_slot,
                  (void*)APR_OFFSETOF(spconfig, check_basename_match), OR_OPTIONS,
                 "whether or not to fix files with the same base name"),
    { NULL }
};

typedef enum {
    SP_IDENTICAL = 0,
    SP_MISCAPITALIZED = 1,
    SP_TRANSPOSITION = 2,
    SP_MISSINGCHAR = 3,
    SP_EXTRACHAR = 4,
    SP_SIMPLETYPO = 5,
    SP_VERYDIFFERENT = 6
} sp_reason;

static const char *sp_reason_str[] =
{
    "identical",
    "miscapitalized",
    "transposed characters",
    "character missing",
    "extra character",
    "mistyped character",
    "common basename",
};

typedef struct {
    const char *name;
    sp_reason quality;
} misspelled_file;

/*
* spdist() is taken from Kernighan & Pike,
*  _The_UNIX_Programming_Environment_
* and adapted somewhat to correspond better to psychological reality.
* (Note the changes to the return values)
*
* According to Pollock and Zamora, CACM April 1984 (V. 27, No. 4),
* page 363, the correct order for this is:
* OMISSION = TRANSPOSITION > INSERTION > SUBSTITUTION
* thus, it was exactly backwards in the old version. -- PWP
*
* This routine was taken out of tcsh's spelling correction code
* (tcsh-6.07.04) and re-converted to apache data types ("char" type
* instead of tcsh's NLS'ed "Char"). Plus it now ignores the case
* during comparisons, so is a "approximate strcasecmp()".
* NOTE that is still allows only _one_ real "typo",
* it does NOT try to correct multiple errors.
*/

static sp_reason spdist(const char *s, const char *t)
{
    for (; apr_tolower(*s) == apr_tolower(*t); t++, s++) {
        if (*t == '\0') {
            return SP_MISCAPITALIZED;   /* exact match (sans case) */
        }
    }
    if (*s) {
        if (*t) {
            if (s[1] && t[1] && apr_tolower(*s) == apr_tolower(t[1])
                && apr_tolower(*t) == apr_tolower(s[1])
                && strcasecmp(s + 2, t + 2) == 0) {
                return SP_TRANSPOSITION;        /* transposition */
            }
            if (strcasecmp(s + 1, t + 1) == 0) {
                return SP_SIMPLETYPO;   /* 1 char mismatch */
            }
        }
        if (strcasecmp(s + 1, t) == 0) {
            return SP_EXTRACHAR;        /* extra character */
        }
    }
    if (*t && strcasecmp(s, t + 1) == 0) {
        return SP_MISSINGCHAR;  /* missing character */
    }
    return SP_VERYDIFFERENT;    /* distance too large to fix. */
}

static int sort_by_quality(const void *left, const void *rite)
{
    return (int) (((misspelled_file *) left)->quality)
        - (int) (((misspelled_file *) rite)->quality);
}

static int check_speling(request_rec *r)
{
    spconfig *cfg;
    char *good, *bad, *postgood, *url;
    apr_finfo_t dirent;
    int filoc, dotloc, urlen, pglen;
    apr_array_header_t *candidates = NULL;
    apr_dir_t          *dir;

    cfg = ap_get_module_config(r->per_dir_config, &speling_module);
    if (!cfg->enabled) {
        return DECLINED;
    }

    /* We only want to worry about GETs */
    if (r->method_number != M_GET) {
        return DECLINED;
    }

    /* We've already got a file of some kind or another */
    if (r->finfo.filetype != APR_NOFILE) {
        return DECLINED;
    }

    /* Not a file request */
    if (r->proxyreq || !r->filename) {
        return DECLINED;
    }

    /* This is a sub request - don't mess with it */
    if (r->main) {
        return DECLINED;
    }

    /*
     * The request should end up looking like this:
     * r->uri: /correct-url/mispelling/more
     * r->filename: /correct-file/mispelling r->path_info: /more
     *
     * So we do this in steps. First break r->filename into two pieces
     */

    filoc = ap_rind(r->filename, '/');
    /*
     * Don't do anything if the request doesn't contain a slash, or
     * requests "/"
     */
    if (filoc == -1 || strcmp(r->uri, "/") == 0) {
        return DECLINED;
    }

    /* good = /correct-file */
    good = apr_pstrndup(r->pool, r->filename, filoc);
    /* bad = mispelling */
    bad = apr_pstrdup(r->pool, r->filename + filoc + 1);
    /* postgood = mispelling/more */
    postgood = apr_pstrcat(r->pool, bad, r->path_info, NULL);

    urlen = strlen(r->uri);
    pglen = strlen(postgood);

    /* Check to see if the URL pieces add up */
    if (strcmp(postgood, r->uri + (urlen - pglen))) {
        return DECLINED;
    }

    /* url = /correct-url */
    url = apr_pstrndup(r->pool, r->uri, (urlen - pglen));

    /* Now open the directory and do ourselves a check... */
    if (apr_dir_open(&dir, good, r->pool) != APR_SUCCESS) {
        /* Oops, not a directory... */
        return DECLINED;
    }

    candidates = apr_array_make(r->pool, 2, sizeof(misspelled_file));

    dotloc = ap_ind(bad, '.');
    if (dotloc == -1) {
        dotloc = strlen(bad);
    }

    while (apr_dir_read(&dirent, APR_FINFO_DIRENT, dir) == APR_SUCCESS) {
        sp_reason q;

        /*
         * If we end up with a "fixed" URL which is identical to the
         * requested one, we must have found a broken symlink or some such.
         * Do _not_ try to redirect this, it causes a loop!
         */
        if (strcmp(bad, dirent.name) == 0) {
            apr_dir_close(dir);
            return OK;
        }

        /*
         * miscapitalization errors are checked first (like, e.g., lower case
         * file, upper case request)
         */
        else if (strcasecmp(bad, dirent.name) == 0) {
            misspelled_file *sp_new;

            sp_new = (misspelled_file *) apr_array_push(candidates);
            sp_new->name = apr_pstrdup(r->pool, dirent.name);
            sp_new->quality = SP_MISCAPITALIZED;
        }

        /*
         * simple typing errors are checked next (like, e.g.,
         * missing/extra/transposed char)
         */
        else if ((cfg->check_case_only == 0)
                 && ((q = spdist(bad, dirent.name)) != SP_VERYDIFFERENT)) {
            misspelled_file *sp_new;

            sp_new = (misspelled_file *) apr_array_push(candidates);
            sp_new->name = apr_pstrdup(r->pool, dirent.name);
            sp_new->quality = q;
        }

        /*
         * The spdist() should have found the majority of the misspelled
         * requests.  It is of questionable use to continue looking for
         * files with the same base name, but potentially of totally wrong
         * type (index.html <-> index.db).
         *
         * If you're using MultiViews, and have a file named foobar.html,
         * which you refer to as "foobar", and someone tried to access
         * "Foobar", without CheckBasenameMatch, mod_speling won't find it,
         * because it won't find anything matching that spelling.
         * With the extension-munging, it would locate "foobar.html".
         */
        else if (cfg->check_basename_match == 1) {
            /*
             * Okay... we didn't find anything. Now we take out the hard-core
             * power tools. There are several cases here. Someone might have
             * entered a wrong extension (.htm instead of .html or vice
             * versa) or the document could be negotiated. At any rate, now
             * we just compare stuff before the first dot. If it matches, we
             * figure we got us a match. This can result in wrong things if
             * there are files of different content types but the same prefix
             * (e.g. foo.gif and foo.html) This code will pick the first one
             * it finds. Better than a Not Found, though.
             */
            int entloc = ap_ind(dirent.name, '.');
            if (entloc == -1) {
                entloc = strlen(dirent.name);
            }

            if ((dotloc == entloc)
                && !strncasecmp(bad, dirent.name, dotloc)) {
                misspelled_file *sp_new;

                sp_new = (misspelled_file *) apr_array_push(candidates);
                sp_new->name = apr_pstrdup(r->pool, dirent.name);
                sp_new->quality = SP_VERYDIFFERENT;
            }
        }
    }
    apr_dir_close(dir);

    if (candidates->nelts != 0) {
        /* Wow... we found us a mispelling. Construct a fixed url */
        char *nuri;
        const char *ref;
        misspelled_file *variant = (misspelled_file *) candidates->elts;
        int i;

        ref = apr_table_get(r->headers_in, "Referer");

        qsort((void *) candidates->elts, candidates->nelts,
              sizeof(misspelled_file), sort_by_quality);

        /*
         * Conditions for immediate redirection:
         *     a) the first candidate was not found by stripping the suffix
         * AND b) there exists only one candidate OR the best match is not
         *        ambiguous
         * then return a redirection right away.
         */
        if (variant[0].quality != SP_VERYDIFFERENT
            && (candidates->nelts == 1
                || variant[0].quality != variant[1].quality)) {

            nuri = ap_escape_uri(r->pool, apr_pstrcat(r->pool, url,
                                                     variant[0].name,
                                                     r->path_info, NULL));
            if (r->parsed_uri.query)
                nuri = apr_pstrcat(r->pool, nuri, "?", r->parsed_uri.query, NULL);

            apr_table_setn(r->headers_out, "Location",
                          ap_construct_url(r->pool, nuri, r));

            ap_log_rerror(APLOG_MARK, APLOG_INFO, APR_SUCCESS,
                          r,
                          ref ? APLOGNO(03224) "Fixed spelling: %s to %s from %s"
                              : APLOGNO(03225) "Fixed spelling: %s to %s%s",
                          r->uri, nuri,
                          (ref ? ref : ""));

            return HTTP_MOVED_PERMANENTLY;
        }
        /*
         * Otherwise, a "[300] Multiple Choices" list with the variants is
         * returned.
         */
        else {
            apr_pool_t *p;
            apr_table_t *notes;
            apr_pool_t *sub_pool;
            apr_array_header_t *t;
            apr_array_header_t *v;

            if (r->main == NULL) {
                p = r->pool;
                notes = r->notes;
            }
            else {
                p = r->main->pool;
                notes = r->main->notes;
            }

            if (apr_pool_create(&sub_pool, p) != APR_SUCCESS)
                return DECLINED;
            apr_pool_tag(sub_pool, "speling_sub");

            t = apr_array_make(sub_pool, candidates->nelts * 8 + 8,
                              sizeof(char *));
            v = apr_array_make(sub_pool, candidates->nelts * 5,
                              sizeof(char *));

            /* Generate the response text. */

            *(const char **)apr_array_push(t) =
                          "The document name you requested ("

;

            *(const char **)apr_array_push(t) = ap_escape_html(sub_pool, r->uri);

            *(const char **)apr_array_push(t) =

                           "

) could not be found on this server.\n"
"However, we found documents with names similar "
"to the one you requested.

"
"Available documents:\n

for

char

const

char

int

/* The format isn't very neat... */

"?"

const

char

"\"

const

char

const

char

"\"

const

char

const

char

"\"

const

char

";
                *(const char **)apr_array_push(t) = ap_escape_uri(sub_pool, vuri);
                *(const char **)apr_array_push(t) = "\">";
                *(const char **)apr_array_push(t) = ap_escape_html(sub_pool, vuri);
                *(const char **)apr_array_push(t) = " (";
                *(const char **)apr_array_push(t) = reason;
                *(const char **)apr_array_push(t) = ")\n";

                /*
                 * when we have printed the "close matches" and there are
                 * more "distant matches" (matched by stripping the suffix),
                 * then we insert an additional separator text to suggest
                 * that the user LOOK CLOSELY whether these are really the
                 * files she wanted.
                 */
                if (i > 0 && i < candidates->nelts - 1
                    && variant[i].quality != SP_VERYDIFFERENT
                    && variant[i + 1].quality == SP_VERYDIFFERENT) {
                    *(const char **)apr_array_push(t) =
                                   "

\nFurthermore, the following related "
"documents were found:\n

const

char

\n";

            /* If we know there was a referring page, add a note: */
            if (ref != NULL) {
                *(const char **)apr_array_push(t) =
                               "Please consider informing the owner of the "
                               "referring page ";                 *(const char **)apr_array_push(t) = ap_escape_html(sub_pool, ref);                 *(const char **)apr_array_push(t) =                                " about the broken link.\n";
            }

            /* Pass our apr_table_t to http_protocol.c (see mod_negotiation): */
            apr_table_setn(notes, "variant-list", apr_array_pstrcat(p, t, 0));

            apr_table_mergen(r->subprocess_env, "VARIANTS",
                            apr_array_pstrcat(p, v, ','));

            apr_pool_destroy(sub_pool);

            ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                         ref ? APLOGNO(03226) "Spelling fix: %s: %d candidates from %s"
                             : APLOGNO(03227) "Spelling fix: %s: %d candidates%s",
                         r->uri, candidates->nelts,
                         (ref ? ref : ""));

            return HTTP_MULTIPLE_CHOICES;
        }
    }

    return OK;
}

static void register_hooks(apr_pool_t *p)
{
    ap_hook_fixups(check_speling,NULL,NULL,APR_HOOK_LAST);
}

AP_DECLARE_MODULE(speling) =
{
    STANDARD20_MODULE_STUFF,
    create_mconfig_for_directory,  /* create per-dir config */
    NULL,                          /* merge per-dir config */
    create_mconfig_for_server,     /* server config */
    NULL,                          /* merge server config */
    speling_cmds,                  /* command apr_table_t */
    register_hooks                 /* register hooks */
};

quality100%

¤ Dauer der Verarbeitung: 0.6 Sekunden ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.