/* 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.

 */

/*

 * mod_cern_meta.c

 * version 0.1.0

 * status beta

 *

 * Andrew Wilson <Andrew.Wilson@cm.cf.ac.uk> 25.Jan.96

 *

 * *** IMPORTANT ***

 * This version of mod_cern_meta.c controls Meta File behaviour on a

 * per-directory basis.  Previous versions of the module defined behaviour

 * on a per-server basis.  The upshot is that you'll need to revisit your

 * configuration files in order to make use of the new module.

 * ***

 *

 * Emulate the CERN HTTPD Meta file semantics.  Meta files are HTTP

 * headers that can be output in addition to the normal range of

 * headers for each file accessed.  They appear rather like the Apache

 * .asis files, and are able to provide a crude way of influencing

 * the Expires: header, as well as providing other curiosities.

 * There are many ways to manage meta information, this one was

 * chosen because there is already a large number of CERN users

 * who can exploit this module.  It should be noted that there are probably

 * more sensitive ways of managing the Expires: header specifically.

 *

 * The module obeys the following directives, which can appear

 * in the server's .conf files and in .htaccess files.

 *

 *  MetaFiles <on|off>

 *

 *    turns on|off meta file processing for any directory.

 *    Default value is off

 *

 *        # turn on MetaFiles in this directory

 *        MetaFiles on

 *

 *  MetaDir <directory name>

 *

 *    specifies the name of the directory in which Apache can find

 *    meta information files.  The directory is usually a 'hidden'

 *    subdirectory of the directory that contains the file being

 *    accessed.  eg:

 *

 *        # .meta files are in the *same* directory as the

 *        # file being accessed

 *        MetaDir .

 *

 *    the default is to look in a '.web' subdirectory. This is the

 *    same as for CERN 3.+ webservers and behaviour is the same as

 *    for the directive:

 *

 *        MetaDir .web

 *

 *  MetaSuffix <meta file suffix>

 *

 *    specifies the file name suffix for the file containing the

 *    meta information.  eg:

 *

 *       # our meta files are suffixed with '.cern_meta'

 *       MetaSuffix .cern_meta

 *

 *    the default is to look for files with the suffix '.meta'.  This

 *    behaviour is the same as for the directive:

 *

 *       MetaSuffix .meta

 *

 * When accessing the file

 *

 *   DOCUMENT_ROOT/somedir/index.html

 *

 * this module will look for the file

 *

 *   DOCUMENT_ROOT/somedir/.web/index.html.meta

 *

 * and will use its contents to generate additional MIME header

 * information.

 *

 * For more information on the CERN Meta file semantics see:

 *

 *   http://www.w3.org/hypertext/WWW/Daemon/User/Config/General.html#MetaDir

 *

 * Change-log:

 * 29.Jan.96 pfopen/pfclose instead of fopen/fclose

 *           DECLINE when real file not found, we may be checking each

 *           of the index.html/index.shtml/index.htm variants and don't

 *           need to report missing ones as spurious errors.

 * 31.Jan.96 log_error reports about a malformed .meta file, rather

 *           than a script error.

 * 20.Jun.96 MetaFiles <on|off> default off, added, so that module

 *           can be configured per-directory.  Prior to this the module

 *           was running for each request anywhere on the server, naughty..

 * 29.Jun.96 All directives made per-directory.

 */

#include "apr.h"

#include "apr_strings.h"

#define APR_WANT_STRFUNC

#include "apr_want.h"

#if APR_HAVE_SYS_TYPES_H

#include <sys/types.h>

#endif

#include "ap_config.h"

#include "httpd.h"

#include "http_config.h"

#include "util_script.h"

#include "http_log.h"

#include "http_request.h"

#include "http_protocol.h"

#include "apr_lib.h"

#define DIR_CMD_PERMS OR_INDEXES

#define DEFAULT_METADIR     ".web"

#define DEFAULT_METASUFFIX  ".meta"

#define DEFAULT_METAFILES   0

module AP_MODULE_DECLARE_DATA cern_meta_module;

typedef struct {

    const char *metadir;

    const char *metasuffix;

    int metafiles;

} cern_meta_dir_config;

static void *create_cern_meta_dir_config(apr_pool_t *p, char *dummy)

{

    cern_meta_dir_config *new =

    (cern_meta_dir_config *) apr_palloc(p, sizeof(cern_meta_dir_config));

    new->metadir = NULL;

    new->metasuffix = NULL;

    new->metafiles = DEFAULT_METAFILES;

    return new;

}

static void *merge_cern_meta_dir_configs(apr_pool_t *p, void *basev, void *addv)

{

    cern_meta_dir_config *base = (cern_meta_dir_config *) basev;

    cern_meta_dir_config *add = (cern_meta_dir_config *) addv;

    cern_meta_dir_config *new =

    (cern_meta_dir_config *) apr_palloc(p, sizeof(cern_meta_dir_config));

    new->metadir = add->metadir ? add->metadir : base->metadir;

    new->metasuffix = add->metasuffix ? add->metasuffix : base->metasuffix;

    new->metafiles = add->metafiles;

    return new;

}

static const char *set_metadir(cmd_parms *parms, void *in_dconf, const char *arg)

{

    cern_meta_dir_config *dconf = in_dconf;

    dconf->metadir = arg;

    return NULL;

}

static const char *set_metasuffix(cmd_parms *parms, void *in_dconf, const char *arg)

{

    cern_meta_dir_config *dconf = in_dconf;

    dconf->metasuffix = arg;

    return NULL;

}

static const char *set_metafiles(cmd_parms *parms, void *in_dconf, int arg)

{

    cern_meta_dir_config *dconf = in_dconf;

    dconf->metafiles = arg;

    return NULL;

}

static const command_rec cern_meta_cmds[] =

{

    AP_INIT_FLAG("MetaFiles", set_metafiles, NULL, DIR_CMD_PERMS,

                 "Limited to 'on' or 'off'"),

    AP_INIT_TAKE1("MetaDir", set_metadir, NULL, DIR_CMD_PERMS,

                  "the name of the directory containing meta files"),

    AP_INIT_TAKE1("MetaSuffix", set_metasuffix, NULL, DIR_CMD_PERMS,

                  "the filename suffix for meta files"),

    {NULL}

};

/* XXX: this is very similar to ap_scan_script_header_err_core...

 * are the differences deliberate, or just a result of bit rot?

 */

static int scan_meta_file(request_rec *r, apr_file_t *f)

{

    char w[MAX_STRING_LEN];

    char *l;

    int p;

    apr_table_t *tmp_headers;

    tmp_headers = apr_table_make(r->pool, 5);

    while (apr_file_gets(w, MAX_STRING_LEN - 1, f) == APR_SUCCESS) {

    /* Delete terminal (CR?)LF */

        p = strlen(w);

        if (p > 0 && w[p - 1] == '\n') {

            if (p > 1 && w[p - 2] == '\015')

                w[p - 2] = '\0';

            else

                w[p - 1] = '\0';

        }

        if (w[0] == '\0') {

            return OK;

        }

        /* if we see a bogus header don't ignore it. Shout and scream */

        if (!(l = strchr(w, ':'))) {

            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01560)

                "malformed header in meta file: %s", r->filename);

            return HTTP_INTERNAL_SERVER_ERROR;

        }

        *l++ = '\0';

        while (apr_isspace(*l))

            ++l;

        if (!strcasecmp(w, "Content-type")) {

            char *tmp;

            /* Nuke trailing whitespace */

            char *endp = l + strlen(l) - 1;

            while (endp > l && apr_isspace(*endp))

                *endp-- = '\0';

            tmp = apr_pstrdup(r->pool, l);

            ap_content_type_tolower(tmp);

            ap_set_content_type(r, tmp);

        }

        else if (!strcasecmp(w, "Status")) {

            sscanf(l, "%d", &r->status);

            r->status_line = apr_pstrdup(r->pool, l);

        }

        else {

            apr_table_set(tmp_headers, w, l);

        }

    }

    apr_table_overlap(r->headers_out, tmp_headers, APR_OVERLAP_TABLES_SET);

    return OK;

}

static int add_cern_meta_data(request_rec *r)

{

    char *metafilename;

    char *leading_slash;

    char *last_slash;

    char *real_file;

    char *scrap_book;

    apr_file_t *f = NULL;

    apr_status_t retcode;

    cern_meta_dir_config *dconf;

    int rv;

    request_rec *rr;

    dconf = ap_get_module_config(r->per_dir_config, &cern_meta_module);

    if (!dconf->metafiles) {

        return DECLINED;

    }

    /* if ./.web/$1.meta exists then output 'asis' */

    if (r->finfo.filetype == APR_NOFILE) {

        return DECLINED;

    }

    /* is this a directory? */

    if (r->finfo.filetype == APR_DIR || r->uri[strlen(r->uri) - 1] == '/') {

        return DECLINED;

    }

    /* what directory is this file in? */

    scrap_book = apr_pstrdup(r->pool, r->filename);

    leading_slash = strchr(scrap_book, '/');

    last_slash = strrchr(scrap_book, '/');

    if ((last_slash != NULL) && (last_slash != leading_slash)) {

        /* skip over last slash */

        real_file = last_slash;

        real_file++;

        *last_slash = '\0';

    }

    else {

        /* no last slash, buh?! */

        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01561)

            "internal error in mod_cern_meta: %s", r->filename);

        /* should really barf, but hey, let's be friends... */

        return DECLINED;

    }

    metafilename = apr_pstrcat(r->pool, scrap_book, "/",

               dconf->metadir ? dconf->metadir : DEFAULT_METADIR,

               "/", real_file,

         dconf->metasuffix ? dconf->metasuffix : DEFAULT_METASUFFIX,

               NULL);

    /* It sucks to require this subrequest to complete, because this

     * means people must leave their meta files accessible to the world.

     * A better solution might be a "safe open" feature of pfopen to avoid

     * pipes, symlinks, and crap like that.

     *

     * In fact, this doesn't suck.  Because <Location > blocks are never run

     * against sub_req_lookup_file, the meta can be somewhat protected by

     * either masking it with a <Location > directive or alias, or stowing

     * the file outside of the web document tree, while providing the

     * appropriate directory blocks to allow access to it as a file.

     */

    rr = ap_sub_req_lookup_file(metafilename, r, NULL);

    if (rr->status != HTTP_OK) {

        ap_destroy_sub_req(rr);

        return DECLINED;

    }

    ap_destroy_sub_req(rr);

    retcode = apr_file_open(&f, metafilename, APR_READ, APR_OS_DEFAULT, r->pool);

    if (retcode != APR_SUCCESS) {

        if (APR_STATUS_IS_ENOENT(retcode)) {

            return DECLINED;

        }

        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01562)

            "meta file permissions deny server access: %s", metafilename);

        return HTTP_FORBIDDEN;

    }

    /* read the headers in */

    rv = scan_meta_file(r, f);

    apr_file_close(f);

    return rv;

}

static void register_hooks(apr_pool_t *p)

{

    ap_hook_fixups(add_cern_meta_data,NULL,NULL,APR_HOOK_MIDDLE);

}

AP_DECLARE_MODULE(cern_meta) =

{

    STANDARD20_MODULE_STUFF,

    create_cern_meta_dir_config, /* dir config creater */

    merge_cern_meta_dir_configs, /* dir merger --- default is to override */

    NULL,                        /* server config */

    NULL,                        /* merge server configs */

    cern_meta_cmds,              /* command apr_table_t */

    register_hooks               /* register hooks */

};