/* 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" #define WANT_BASENAME_MATCH #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 case_only; } 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->case_only = 0; 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, case_only), OR_OPTIONS, "whether or not to fix only miscapitalized requests"), { 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 != 0) { 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->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). * I would propose to not set the WANT_BASENAME_MATCH define. * 08-Aug-1997 <Martin.Kraemer@Mch.SNI.De> * * However, Alexei replied giving some reasons to add it anyway: * > Oh, by the way, I remembered why having the * > extension-stripping-and-matching stuff is a good idea: * > * > If you're using MultiViews, and have a file named foobar.html, * > which you refer to as "foobar", and someone tried to access * > "Foobar", mod_speling won't find it, because it won't find * > anything matching that spelling. With the extension-munging, * > it would locate "foobar.html". Not perfect, but I ran into * > that problem when I first wrote the module. */ else { #ifdef WANT_BASENAME_MATCH /* * 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; } #endif } } 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 ? "Fixed spelling: %s to %s from %s" : "Fixed spelling: %s to %s", r->uri, nuri, 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; 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 (<code>"; *(const char **)apr_array_push(t) = ap_escape_html(sub_pool, r->uri); *(const char **)apr_array_push(t) = "</code>) could not be found on this server.\n" "However, we found documents with names similar " "to the one you requested.<p>" "Available documents:\n<ul>\n"; for (i = 0; i < candidates->nelts; ++i) { char *vuri; const char *reason; reason = sp_reason_str[(int) (variant[i].quality)]; /* The format isn't very neat... */ vuri = apr_pstrcat(sub_pool, url, variant[i].name, r->path_info, (r->parsed_uri.query != NULL) ? "?" : "", (r->parsed_uri.query != NULL) ? r->parsed_uri.query : "", NULL); *(const char **)apr_array_push(v) = "\""; *(const char **)apr_array_push(v) = ap_escape_uri(sub_pool, vuri); *(const char **)apr_array_push(v) = "\";\""; *(const char **)apr_array_push(v) = reason; *(const char **)apr_array_push(v) = "\""; *(const char **)apr_array_push(t) = "<li><a href=\""; *(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) = "</a> ("; *(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) = "</ul>\nFurthermore, the following related " "documents were found:\n<ul>\n"; } } *(const char **)apr_array_push(t) = "</ul>\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 " "<a href=\""; *(const char **)apr_array_push(t) = ap_escape_uri(sub_pool, ref); *(const char **)apr_array_push(t) = "\">referring page</a> " "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 ? "Spelling fix: %s: %d candidates from %s" : "Spelling fix: %s: %d candidates", r->uri, candidates->nelts, 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); } module AP_MODULE_DECLARE_DATA speling_module = { 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 */ };
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