/* 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_userdir... implement the UserDir command.  Broken away from the

 * Alias stuff for a couple of good and not-so-good reasons:

 *

 * 1) It shows a real minimal working example of how to do something like

 *    this.

 * 2) I know people who are actually interested in changing this *particular*

 *    aspect of server functionality without changing the rest of it.  That's

 *    what this whole modular arrangement is supposed to be good at...

 *

 * Modified by Alexei Kosut to support the following constructs

 * (server running at www.foo.com, request for /~bar/one/two.html)

 *

 * UserDir public_html      -> ~bar/public_html/one/two.html

 * UserDir /usr/web         -> /usr/web/bar/one/two.html

 * UserDir /home/ * /www     -> /home/bar/www/one/two.html

 *  NOTE: theses ^ ^ space only added allow it to work in a comment, ignore

 * UserDir http://x/users   -> (302) http://x/users/bar/one/two.html

 * UserDir http://x/ * /y     -> (302) http://x/bar/y/one/two.html

 *  NOTE: here also ^ ^

 *

 * In addition, you can use multiple entries, to specify alternate

 * user directories (a la Directory Index). For example:

 *

 * UserDir public_html /usr/web http://www.xyz.com/users

 *

 * Modified by Ken Coar to provide for the following:

 *

 * UserDir disable[d] username ...

 * UserDir enable[d] username ...

 *

 * If "disabled" has no other arguments, *all* ~<username> references are

 * disabled, except those explicitly turned on with the "enabled" keyword.

 */

#include "apr_strings.h"

#include "apr_user.h"

#define APR_WANT_STRFUNC

#include "apr_want.h"

#if APR_HAVE_UNISTD_H

#include <unistd.h>

#endif

#include "ap_config.h"

#include "httpd.h"

#include "http_config.h"

#include "http_request.h"

#if !defined(WIN32) && !defined(OS2) && !defined(NETWARE)

#define HAVE_UNIX_SUEXEC

#endif

#ifdef HAVE_UNIX_SUEXEC

#include "unixd.h"        /* Contains the suexec_identity hook used on Unix */

#endif

/*

 * The default directory in user's home dir

 * In the default install, the module is disabled

 */

#ifndef DEFAULT_USER_DIR

#define DEFAULT_USER_DIR NULL

#endif

#define O_DEFAULT 0

#define O_ENABLE 1

#define O_DISABLE 2

module AP_MODULE_DECLARE_DATA userdir_module;

typedef struct {

    int globally_disabled;

    const char *userdir;

    apr_table_t *enabled_users;

    apr_table_t *disabled_users;

} userdir_config;

/*

 * Server config for this module: global disablement flag, a list of usernames

 * ineligible for UserDir access, a list of those immune to global (but not

 * explicit) disablement, and the replacement string for all others.

 */

static void *create_userdir_config(apr_pool_t *p, server_rec *s)

{

    userdir_config *newcfg = apr_pcalloc(p, sizeof(*newcfg));

    newcfg->globally_disabled = O_DEFAULT;

    newcfg->userdir = DEFAULT_USER_DIR;

    newcfg->enabled_users = apr_table_make(p, 4);

    newcfg->disabled_users = apr_table_make(p, 4);

    return newcfg;

}

static void *merge_userdir_config(apr_pool_t *p, void *basev, void *overridesv)

{

    userdir_config *cfg = apr_pcalloc(p, sizeof(userdir_config));

    userdir_config *base = basev, *overrides = overridesv;

    cfg->globally_disabled = (overrides->globally_disabled != O_DEFAULT) ?

                             overrides->globally_disabled :

                             base->globally_disabled;

    cfg->userdir = (overrides->userdir != DEFAULT_USER_DIR) ?

                   overrides->userdir : base->userdir;

    /* not merged */

    cfg->enabled_users = overrides->enabled_users;

    cfg->disabled_users = overrides->disabled_users;

    return cfg;

}

static const char *set_user_dir(cmd_parms *cmd, void *dummy, const char *arg)

{

    userdir_config *s_cfg = ap_get_module_config(cmd->server->module_config,

                                                 &userdir_module);

    char *username;

    const char *usernames = arg;

    char *kw = ap_getword_conf(cmd->temp_pool, &usernames);

    apr_table_t *usertable;

    /* Since we are a raw argument, it is possible for us to be called with

     * zero arguments.  So that we aren't ambiguous, flat out reject this.

     */

    if (*kw == '\0') {

        return "UserDir requires an argument.";

    }

    /*

     * Let's do the comparisons once.

     */

    if ((!strcasecmp(kw, "disable")) || (!strcasecmp(kw, "disabled"))) {

        /*

         * If there are no usernames specified, this is a global disable - we

         * need do no more at this point than record the fact.

         */

        if (!*usernames) {

            s_cfg->globally_disabled = O_DISABLE;

            return NULL;

        }

        usertable = s_cfg->disabled_users;

    }

    else if ((!strcasecmp(kw, "enable")) || (!strcasecmp(kw, "enabled"))) {

        if (!*usernames) {

            s_cfg->globally_disabled = O_ENABLE;

            return NULL;

        }

        usertable = s_cfg->enabled_users;

    }

    else {

        /*

         * If the first (only?) value isn't one of our keywords, just copy

         * the string to the userdir string.

         */

        s_cfg->userdir = arg;

        return NULL;

    }

    /*

     * Now we just take each word in turn from the command line and add it to

     * the appropriate table.

     */

    while (*usernames) {

        username = ap_getword_conf(cmd->pool, &usernames);

        apr_table_setn(usertable, username, "1");

    }

    return NULL;

}

static const command_rec userdir_cmds[] = {

    AP_INIT_RAW_ARGS("UserDir", set_user_dir, NULL, RSRC_CONF,

                     "the public subdirectory in users' home directories, or "

                     "'disabled', or 'disabled username username...', or "

                     "'enabled username username...'"),

    {NULL}

};

static int translate_userdir(request_rec *r)

{

    ap_conf_vector_t *server_conf;

    const userdir_config *s_cfg;

    const char *userdirs;

    const char *user, *dname;

    char *redirect;

    apr_finfo_t statbuf;

    /*

     * If the URI doesn't match our basic pattern, we've nothing to do with

     * it.

     */

    if (r->uri[0] != '/' || r->uri[1] != '~') {

        return DECLINED;

    }

    server_conf = r->server->module_config;

    s_cfg = ap_get_module_config(server_conf, &userdir_module);

    userdirs = s_cfg->userdir;

    if (userdirs == NULL) {

        return DECLINED;

    }

    dname = r->uri + 2;

    user = ap_getword(r->pool, &dname, '/');

    /*

     * The 'dname' funny business involves backing it up to capture the '/'

     * delimiting the "/~user" part from the rest of the URL, in case there

     * was one (the case where there wasn't being just "GET /~user HTTP/1.0",

     * for which we don't want to tack on a '/' onto the filename).

     */

    if (dname[-1] == '/') {

        --dname;

    }

    /*

     * If there's no username, it's not for us.  Ignore . and .. as well.

     */

    if (user[0] == '\0' ||

        (user[1] == '.' && (user[2] == '\0' ||

                            (user[2] == '.' && user[3] == '\0')))) {

        return DECLINED;

    }

    /*

     * Nor if there's an username but it's in the disabled list.

     */

    if (apr_table_get(s_cfg->disabled_users, user) != NULL) {

        return DECLINED;

    }

    /*

     * If there's a global interdiction on UserDirs, check to see if this

     * name is one of the Blessed.

     */

    if (s_cfg->globally_disabled == O_DISABLE

        && apr_table_get(s_cfg->enabled_users, user) == NULL) {

        return DECLINED;

    }

    /*

     * Special cases all checked, onward to normal substitution processing.

     */

    while (*userdirs) {

        const char *userdir = ap_getword_conf(r->pool, &userdirs);

        char *filename = NULL, *prefix = NULL;

        apr_status_t rv;

        int is_absolute = ap_os_is_path_absolute(r->pool, userdir);

        if (ap_strchr_c(userdir, '*'))

            prefix = ap_getword(r->pool, &userdir, '*');

        if (userdir[0] == '\0' || is_absolute) {

            if (prefix) {

#ifdef HAVE_DRIVE_LETTERS

                /*

                 * Crummy hack. Need to figure out whether we have been

                 * redirected to a URL or to a file on some drive. Since I

                 * know of no protocols that are a single letter, ignore

                 * a : as the first or second character, and assume a file

                 * was specified

                 */

                if (strchr(prefix + 2, ':'))

#else

                if (strchr(prefix, ':') && !is_absolute)

#endif /* HAVE_DRIVE_LETTERS */

                {

                    redirect = apr_pstrcat(r->pool, prefix, user, userdir,

                                           dname, NULL);

                    apr_table_setn(r->headers_out, "Location", redirect);

                    return HTTP_MOVED_TEMPORARILY;

                }

                else

                    filename = apr_pstrcat(r->pool, prefix, user, userdir,

                                           NULL);

            }

            else

                filename = apr_pstrcat(r->pool, userdir, "/", user, NULL);

        }

        else if (prefix && ap_strchr_c(prefix, ':')) {

            redirect = apr_pstrcat(r->pool, prefix, user, dname, NULL);

            apr_table_setn(r->headers_out, "Location", redirect);

            return HTTP_MOVED_TEMPORARILY;

        }

        else {

#if APR_HAS_USER

            char *homedir;

            if (apr_uid_homepath_get(&homedir, user, r->pool) == APR_SUCCESS) {

                filename = apr_pstrcat(r->pool, homedir, "/", userdir, NULL);

            }

#else

            return DECLINED;

#endif

        }

        /*

         * Now see if it exists, or we're at the last entry. If we are at the

         * last entry, then use the filename generated (if there is one)

         * anyway, in the hope that some handler might handle it. This can be

         * used, for example, to run a CGI script for the user.

         */

        if (filename && (!*userdirs

                      || ((rv = apr_stat(&statbuf, filename, APR_FINFO_MIN,

                                         r->pool)) == APR_SUCCESS

                                             || rv == APR_INCOMPLETE))) {

            r->filename = apr_pstrcat(r->pool, filename, dname, NULL);

            ap_set_context_info(r, apr_pstrmemdup(r->pool, r->uri,

                                                  dname - r->uri),

                                filename);

            /* XXX: Does this walk us around FollowSymLink rules?

             * When statbuf contains info on r->filename we can save a syscall

             * by copying it to r->finfo

             */

            if (*userdirs && dname[0] == 0)

                r->finfo = statbuf;

            /* For use in the get_suexec_identity phase */

            apr_table_setn(r->notes, "mod_userdir_user", user);

            return OK;

        }

    }

    return DECLINED;

}

#ifdef HAVE_UNIX_SUEXEC

static ap_unix_identity_t *get_suexec_id_doer(const request_rec *r)

{

    ap_unix_identity_t *ugid = NULL;

#if APR_HAS_USER

    const char *username = apr_table_get(r->notes, "mod_userdir_user");

    if (username == NULL) {

        return NULL;

    }

    if ((ugid = apr_palloc(r->pool, sizeof(*ugid))) == NULL) {

        return NULL;

    }

    if (apr_uid_get(&ugid->uid, &ugid->gid, username, r->pool) != APR_SUCCESS) {

        return NULL;

    }

    ugid->userdir = 1;

#endif

    return ugid;

}

#endif /* HAVE_UNIX_SUEXEC */

static void register_hooks(apr_pool_t *p)

{

    static const char * const aszPre[]={ "mod_alias.c",NULL };

    static const char * const aszSucc[]={ "mod_vhost_alias.c",NULL };

    ap_hook_translate_name(translate_userdir,aszPre,aszSucc,APR_HOOK_MIDDLE);

#ifdef HAVE_UNIX_SUEXEC

    ap_hook_get_suexec_identity(get_suexec_id_doer,NULL,NULL,APR_HOOK_FIRST);

#endif

}

AP_DECLARE_MODULE(userdir) = {

    STANDARD20_MODULE_STUFF,

    NULL,                       /* dir config creater */

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

    create_userdir_config,      /* server config */

    merge_userdir_config,       /* merge server config */

    userdir_cmds,               /* command apr_table_t */

    register_hooks              /* register hooks */

};