/* 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.

 */

/*

 * http_alias.c: Stuff for dealing with directory aliases

 *

 * Original by Rob McCool, rewritten in succession by David Robinson

 * and rst.

 *

 */

#include "apr_strings.h"

#include "apr_lib.h"

#define APR_WANT_STRFUNC

#include "apr_want.h"

#include "ap_config.h"

#include "httpd.h"

#include "http_core.h"

#include "http_config.h"

#include "http_request.h"

#include "http_log.h"

#include "ap_expr.h"

typedef struct {

    const char *real;

    const char *fake;

    char *handler;

    ap_regex_t *regexp;

    int redir_status;                /* 301, 302, 303, 410, etc */

} alias_entry;

typedef struct {

    apr_array_header_t *aliases;

    apr_array_header_t *redirects;

} alias_server_conf;

typedef struct {

    unsigned int alias_set:1;

    unsigned int redirect_set:1;

    apr_array_header_t *redirects;

    const ap_expr_info_t *alias;

    char *handler;

    const ap_expr_info_t *redirect;

    int redirect_status;                /* 301, 302, 303, 410, etc */

} alias_dir_conf;

module AP_MODULE_DECLARE_DATA alias_module;

static char magic_error_value;

#define PREGSUB_ERROR      (&magic_error_value)

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

{

    alias_server_conf *a =

    (alias_server_conf *) apr_pcalloc(p, sizeof(alias_server_conf));

    a->aliases = apr_array_make(p, 20, sizeof(alias_entry));

    a->redirects = apr_array_make(p, 20, sizeof(alias_entry));

    return a;

}

static void *create_alias_dir_config(apr_pool_t *p, char *d)

{

    alias_dir_conf *a =

    (alias_dir_conf *) apr_pcalloc(p, sizeof(alias_dir_conf));

    a->redirects = apr_array_make(p, 2, sizeof(alias_entry));

    return a;

}

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

{

    alias_server_conf *a =

    (alias_server_conf *) apr_pcalloc(p, sizeof(alias_server_conf));

    alias_server_conf *base = (alias_server_conf *) basev;

    alias_server_conf *overrides = (alias_server_conf *) overridesv;

    a->aliases = apr_array_append(p, overrides->aliases, base->aliases);

    a->redirects = apr_array_append(p, overrides->redirects, base->redirects);

    return a;

}

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

{

    alias_dir_conf *a =

    (alias_dir_conf *) apr_pcalloc(p, sizeof(alias_dir_conf));

    alias_dir_conf *base = (alias_dir_conf *) basev;

    alias_dir_conf *overrides = (alias_dir_conf *) overridesv;

    a->redirects = apr_array_append(p, overrides->redirects, base->redirects);

    a->alias = (overrides->alias_set == 0) ? base->alias : overrides->alias;

    a->handler = (overrides->alias_set == 0) ? base->handler : overrides->handler;

    a->alias_set = overrides->alias_set || base->alias_set;

    a->redirect = (overrides->redirect_set == 0) ? base->redirect : overrides->redirect;

    a->redirect_status = (overrides->redirect_set == 0) ? base->redirect_status : overrides->redirect_status;

    a->redirect_set = overrides->redirect_set || base->redirect_set;

    return a;

}

/* need prototype for overlap check */

static int alias_matches(const char *uri, const char *alias_fakename);

static const char *add_alias_internal(cmd_parms *cmd, void *dummy,

                                      const char *fake, const char *real,

                                      int use_regex)

{

    server_rec *s = cmd->server;

    alias_server_conf *conf = ap_get_module_config(s->module_config,

                                                   &alias_module);

    alias_entry *new = apr_array_push(conf->aliases);

    alias_entry *entries = (alias_entry *)conf->aliases->elts;

    int i;

    /* XXX: real can NOT be relative to DocumentRoot here... compat bug. */

    const char *err = ap_check_cmd_context(cmd, NOT_IN_DIR_CONTEXT);

    if (err != NULL) {

        return err;

    }

    if (use_regex) {

        new->regexp = ap_pregcomp(cmd->pool, fake, AP_REG_EXTENDED);

        if (new->regexp == NULL)

            return "Regular expression could not be compiled.";

        new->real = real;

    }

    else {

        /* XXX This may be optimized, but we must know that new->real

         * exists.  If so, we can dir merge later, trusing new->real

         * and just canonicalizing the remainder.  Not till I finish

         * cleaning out the old ap_canonical stuff first.

         */

        new->real = real;

    }

    new->fake = fake;

    new->handler = cmd->info;

    /* check for overlapping (Script)Alias directives

     * and throw a warning if found one

     */

    if (!use_regex) {

        for (i = 0; i < conf->aliases->nelts - 1; ++i) {

            alias_entry *alias = &entries[i];

            if (  (!alias->regexp &&  alias_matches(fake, alias->fake) > 0)

                || (alias->regexp && !ap_regexec(alias->regexp, fake, 0, NULL, 0))) {

                ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00671)

                             "The %s directive in %s at line %d will probably "

                             "never match because it overlaps an earlier "

                             "%sAlias%s.",

                             cmd->cmd->name, cmd->directive->filename,

                             cmd->directive->line_num,

                             alias->handler ? "Script" : "",

                             alias->regexp ? "Match" : "");

                break; /* one warning per alias should be sufficient */

            }

        }

    }

    return NULL;

}

static const char *add_alias(cmd_parms *cmd, void *dummy, const char *fake,

        const char *real)

{

    if (real) {

        return add_alias_internal(cmd, dummy, fake, real, 0);

    }

    else {

        alias_dir_conf *dirconf = (alias_dir_conf *) dummy;

        const char *err = ap_check_cmd_context(cmd, NOT_IN_DIRECTORY|NOT_IN_FILES);

        if (err != NULL) {

            return err;

        }

        if (!cmd->path) {

            return "Alias must have two arguments when used globally";

        }

        dirconf->alias =

                ap_expr_parse_cmd(cmd, fake, AP_EXPR_FLAG_STRING_RESULT,

                        &err, NULL);

        if (err) {

            return apr_pstrcat(cmd->temp_pool,

                    "Cannot parse alias expression '", fake, "': ", err,

                    NULL);

        }

        dirconf->handler = cmd->info;

        dirconf->alias_set = 1;

        return NULL;

    }

}

static const char *add_alias_regex(cmd_parms *cmd, void *dummy,

                                   const char *fake, const char *real)

{

    return add_alias_internal(cmd, dummy, fake, real, 1);

}

static const char *add_redirect_internal(cmd_parms *cmd,

                                         alias_dir_conf *dirconf,

                                         const char *arg1, const char *arg2,

                                         const char *arg3, int use_regex)

{

    alias_entry *new;

    server_rec *s = cmd->server;

    alias_server_conf *serverconf = ap_get_module_config(s->module_config,

                                                         &alias_module);

    int status = (int) (long) cmd->info;

    int grokarg1 = 1;

    ap_regex_t *regex = NULL;

    const char *fake = arg2;

    const char *url = arg3;

    /*

     * Logic flow:

     *   Go ahead and try to grok the 1st arg, in case it is a

     *   Redirect status. Now if we have 3 args, we expect that

     *   we were able to understand that 1st argument (it's something

     *   we expected, so if not, then we bail

     */

    if (!strcasecmp(arg1, "permanent"))

        status = HTTP_MOVED_PERMANENTLY;

    else if (!strcasecmp(arg1, "temp"))

        status = HTTP_MOVED_TEMPORARILY;

    else if (!strcasecmp(arg1, "seeother"))

        status = HTTP_SEE_OTHER;

    else if (!strcasecmp(arg1, "gone")) {

        status = HTTP_GONE;

        grokarg1 = -1;

    }

    else if (apr_isdigit(*arg1)) {

        status = atoi(arg1);

        if (!ap_is_HTTP_REDIRECT(status)) {

            grokarg1 = -1;

        }

    }

    else {

        grokarg1 = 0;

    }

    if (arg3 && !grokarg1)

        return "Redirect: invalid first argument (of three)";

    /*

     * if we have the 2nd arg and we understand the 1st one as a redirect

     * status (3xx, but not things like 404 /robots.txt), or if we have the

     * 1st arg but don't understand it, we use the expression syntax assuming

     * a path from the location.

     *

     * if we understand the first arg but have no second arg, we are dealing

     * with a status like "GONE" or a non-redirect status (e.g. 404, 503).

     */

    if (!cmd->path) {

        /* <Location> context only for now */

        ;

    }

    else if ((grokarg1 > 0 && arg2 && !arg3) || (!grokarg1 && !arg2)) {

        const char *expr_err = NULL;

        url = grokarg1 ? arg2 : arg1;

        dirconf->redirect =

                ap_expr_parse_cmd(cmd, url, AP_EXPR_FLAG_STRING_RESULT,

                        &expr_err, NULL);

        if (expr_err) {

            return apr_pstrcat(cmd->temp_pool,

                    "Cannot parse redirect expression '", url, "': ", expr_err,

                    NULL);

        }

        dirconf->redirect_status = status;

        dirconf->redirect_set = 1;

        return NULL;

    }

    else if (grokarg1 < 0 && !arg2) {

        dirconf->redirect_status = status;

        dirconf->redirect_set = 1;

        return NULL;

    }

    /*

     * if we don't have the 3rd arg and we didn't understand the 1st

     * one, then assume URL-path URL. This also handles case, eg, GONE

     * we even though we don't have a 3rd arg, we did understand the 1st

     * one, so we don't want to re-arrange

     */

    if (!arg3 && !grokarg1) {

        fake = arg1;

        url = arg2;

    }

    if (use_regex) {

        regex = ap_pregcomp(cmd->pool, fake, AP_REG_EXTENDED);

        if (regex == NULL)

            return "Regular expression could not be compiled.";

    }

    if (ap_is_HTTP_REDIRECT(status)) {

        if (!url)

            return "URL to redirect to is missing";

        /* PR#35314: we can allow path components here;

         * they get correctly resolved to full URLs.

         */

        if (!use_regex && !ap_is_url(url) && (url[0] != '/'))

            return "Redirect to non-URL";

    }

    else {

        if (url)

            return "Redirect URL not valid for this status";

    }

    if (cmd->path)

        new = apr_array_push(dirconf->redirects);

    else

        new = apr_array_push(serverconf->redirects);

    new->fake = fake;

    new->real = url;

    new->regexp = regex;

    new->redir_status = status;

    return NULL;

}

static const char *add_redirect(cmd_parms *cmd, void *dirconf,

                                const char *arg1, const char *arg2,

                                const char *arg3)

{

    return add_redirect_internal(cmd, dirconf, arg1, arg2, arg3, 0);

}

static const char *add_redirect2(cmd_parms *cmd, void *dirconf,

                                 const char *arg1, const char *arg2)

{

    return add_redirect_internal(cmd, dirconf, arg1, arg2, NULL, 0);

}

static const char *add_redirect_regex(cmd_parms *cmd, void *dirconf,

                                      const char *arg1, const char *arg2,

                                      const char *arg3)

{

    return add_redirect_internal(cmd, dirconf, arg1, arg2, arg3, 1);

}

static const command_rec alias_cmds[] =

{

    AP_INIT_TAKE12("Alias", add_alias, NULL, RSRC_CONF | ACCESS_CONF,

                  "a fakename and a realname, or a realname in a Location"),

    AP_INIT_TAKE12("ScriptAlias", add_alias, "cgi-script", RSRC_CONF | ACCESS_CONF,

                  "a fakename and a realname, or a realname in a Location"),

    AP_INIT_TAKE123("Redirect", add_redirect, (void *) HTTP_MOVED_TEMPORARILY,

                   OR_FILEINFO,

                   "an optional status, then document to be redirected and "

                   "destination URL"),

    AP_INIT_TAKE2("AliasMatch", add_alias_regex, NULL, RSRC_CONF,

                  "a regular expression and a filename"),

    AP_INIT_TAKE2("ScriptAliasMatch", add_alias_regex, "cgi-script", RSRC_CONF,

                  "a regular expression and a filename"),

    AP_INIT_TAKE23("RedirectMatch", add_redirect_regex,

                   (void *) HTTP_MOVED_TEMPORARILY, OR_FILEINFO,

                   "an optional status, then a regular expression and "

                   "destination URL"),

    AP_INIT_TAKE2("RedirectTemp", add_redirect2,

                  (void *) HTTP_MOVED_TEMPORARILY, OR_FILEINFO,

                  "a document to be redirected, then the destination URL"),

    AP_INIT_TAKE2("RedirectPermanent", add_redirect2,

                  (void *) HTTP_MOVED_PERMANENTLY, OR_FILEINFO,

                  "a document to be redirected, then the destination URL"),

    {NULL}

};

static int alias_matches(const char *uri, const char *alias_fakename)

{

    const char *aliasp = alias_fakename, *urip = uri;

    while (*aliasp) {

        if (*aliasp == '/') {

            /* any number of '/' in the alias matches any number in

             * the supplied URI, but there must be at least one...

             */

            if (*urip != '/')

                return 0;

            do {

                ++aliasp;

            } while (*aliasp == '/');

            do {

                ++urip;

            } while (*urip == '/');

        }

        else {

            /* Other characters are compared literally */

            if (*urip++ != *aliasp++)

                return 0;

        }

    }

    /* Check last alias path component matched all the way */

    if (aliasp[-1] != '/' && *urip != '\0' && *urip != '/')

        return 0;

    /* Return number of characters from URI which matched (may be

     * greater than length of alias, since we may have matched

     * doubled slashes)

     */

    return urip - uri;

}

static char *try_alias(request_rec *r)

{

    alias_dir_conf *dirconf =

            (alias_dir_conf *) ap_get_module_config(r->per_dir_config, &alias_module);

    if (dirconf->alias) {

        const char *err = NULL;

        char *found = apr_pstrdup(r->pool,

                ap_expr_str_exec(r, dirconf->alias, &err));

        if (err) {

            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02825)

                          "Can't evaluate alias expression: %s", err);

            return PREGSUB_ERROR;

        }

        if (dirconf->handler) { /* Set handler, and leave a note for mod_cgi */

            r->handler = dirconf->handler;

            apr_table_setn(r->notes, "alias-forced-type", r->handler);

        }

        /* XXX This is as SLOW as can be, next step, we optimize

         * and merge to whatever part of the found path was already

         * canonicalized.  After I finish eliminating os canonical.

         * Better fail test for ap_server_root_relative needed here.

         */

        found = ap_server_root_relative(r->pool, found);

        return found;

    }

    return NULL;

}

static char *try_redirect(request_rec *r, int *status)

{

    alias_dir_conf *dirconf =

            (alias_dir_conf *) ap_get_module_config(r->per_dir_config, &alias_module);

    if (dirconf->redirect_set) {

        apr_uri_t uri;

        const char *err = NULL;

        char *found = "";

        if (dirconf->redirect) {

            found = apr_pstrdup(r->pool,

                    ap_expr_str_exec(r, dirconf->redirect, &err));

            if (err) {

                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02826)

                              "Can't evaluate redirect expression: %s", err);

                return PREGSUB_ERROR;

            }

            apr_uri_parse(r->pool, found, &uri);

            /* Do not escape the query string or fragment. */

            found = apr_uri_unparse(r->pool, &uri, APR_URI_UNP_OMITQUERY);

            found = ap_escape_uri(r->pool, found);

            if (uri.query) {

                found = apr_pstrcat(r->pool, found, "?", uri.query, NULL);

            }

            if (uri.fragment) {

                found = apr_pstrcat(r->pool, found, "#", uri.fragment, NULL);

            }

        }

        *status = dirconf->redirect_status;

        return found;

    }

    return NULL;

}

static char *try_alias_list(request_rec *r, apr_array_header_t *aliases,

                            int is_redir, int *status)

{

    alias_entry *entries = (alias_entry *) aliases->elts;

    ap_regmatch_t regm[AP_MAX_REG_MATCH];

    char *found = NULL;

    int i;

    for (i = 0; i < aliases->nelts; ++i) {

        alias_entry *alias = &entries[i];

        int l;

        if (alias->regexp) {

            if (!ap_regexec(alias->regexp, r->uri, AP_MAX_REG_MATCH, regm, 0)) {

                if (alias->real) {

                    found = ap_pregsub(r->pool, alias->real, r->uri,

                                       AP_MAX_REG_MATCH, regm);

                    if (found) {

                       if (is_redir) {

                            apr_uri_t uri;

                            apr_uri_parse(r->pool, found, &uri);

                            /* Do not escape the query string or fragment. */

                            found = apr_uri_unparse(r->pool, &uri,

                                                    APR_URI_UNP_OMITQUERY);

                            found = ap_escape_uri(r->pool, found);

                            if (uri.query) {

                                found = apr_pstrcat(r->pool, found, "?",

                                                    uri.query, NULL);

                            }

                            if (uri.fragment) {

                                found = apr_pstrcat(r->pool, found, "#",

                                                    uri.fragment, NULL);

                            }

                       }

                    }

                    else {

                        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00672)

                                      "Regex substitution in '%s' failed. "

                                      "Replacement too long?", alias->real);

                        return PREGSUB_ERROR;

                    }

                }

                else {

                    /* need something non-null */

                    found = "";

                }

            }

        }

        else {

            l = alias_matches(r->uri, alias->fake);

            if (l > 0) {

                ap_set_context_info(r, alias->fake, alias->real);

                if (is_redir) {

                    char *escurl;

                    escurl = ap_os_escape_path(r->pool, r->uri + l, 1);

                    found = apr_pstrcat(r->pool, alias->real, escurl, NULL);

                }

                else

                    found = apr_pstrcat(r->pool, alias->real, r->uri + l, NULL);

            }

        }

        if (found) {

            if (alias->handler) {    /* Set handler, and leave a note for mod_cgi */

                r->handler = alias->handler;

                apr_table_setn(r->notes, "alias-forced-type", r->handler);

            }

            /* XXX This is as SLOW as can be, next step, we optimize

             * and merge to whatever part of the found path was already

             * canonicalized.  After I finish eliminating os canonical.

             * Better fail test for ap_server_root_relative needed here.

             */

            if (!is_redir) {

                found = ap_server_root_relative(r->pool, found);

            }

            if (found) {

                *status = alias->redir_status;

            }

            return found;

        }

    }

    return NULL;

}

static int translate_alias_redir(request_rec *r)

{

    ap_conf_vector_t *sconf = r->server->module_config;

    alias_server_conf *serverconf = ap_get_module_config(sconf, &alias_module);

    char *ret;

    int status;

    if (r->uri[0] != '/' && r->uri[0] != '\0') {

        return DECLINED;

    }

    if ((ret = try_redirect(r, &status)) != NULL

            || (ret = try_alias_list(r, serverconf->redirects, 1, &status))

                    != NULL) {

        if (ret == PREGSUB_ERROR)

            return HTTP_INTERNAL_SERVER_ERROR;

        if (ap_is_HTTP_REDIRECT(status)) {

            if (ret[0] == '/') {

                char *orig_target = ret;

                ret = ap_construct_url(r->pool, ret, r);

                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00673)

                              "incomplete redirection target of '%s' for "

                              "URI '%s' modified to '%s'",

                              orig_target, r->uri, ret);

            }

            if (!ap_is_url(ret)) {

                status = HTTP_INTERNAL_SERVER_ERROR;

                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00674)

                              "cannot redirect '%s' to '%s'; "

                              "target is not a valid absoluteURI or abs_path",

                              r->uri, ret);

            }

            else {

                /* append requested query only, if the config didn't

                 * supply its own.

                 */

                if (r->args && !ap_strchr(ret, '?')) {

                    ret = apr_pstrcat(r->pool, ret, "?", r->args, NULL);

                }

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

            }

        }

        return status;

    }

    if ((ret = try_alias(r)) != NULL

            || (ret = try_alias_list(r, serverconf->aliases, 0, &status))

                    != NULL) {

        r->filename = ret;

        return OK;

    }

    return DECLINED;

}

static int fixup_redir(request_rec *r)

{

    void *dconf = r->per_dir_config;

    alias_dir_conf *dirconf =

    (alias_dir_conf *) ap_get_module_config(dconf, &alias_module);

    char *ret;

    int status;

    /* It may have changed since last time, so try again */

    if ((ret = try_redirect(r, &status)) != NULL

            || (ret = try_alias_list(r, dirconf->redirects, 1, &status))

                    != NULL) {

        if (ret == PREGSUB_ERROR)

            return HTTP_INTERNAL_SERVER_ERROR;

        if (ap_is_HTTP_REDIRECT(status)) {

            if (ret[0] == '/') {

                char *orig_target = ret;

                ret = ap_construct_url(r->pool, ret, r);

                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(00675)

                              "incomplete redirection target of '%s' for "

                              "URI '%s' modified to '%s'",

                              orig_target, r->uri, ret);

            }

            if (!ap_is_url(ret)) {

                status = HTTP_INTERNAL_SERVER_ERROR;

                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00676)

                              "cannot redirect '%s' to '%s'; "

                              "target is not a valid absoluteURI or abs_path",

                              r->uri, ret);

            }

            else {

                /* append requested query only, if the config didn't

                 * supply its own.

                 */

                if (r->args && !ap_strchr(ret, '?')) {

                    ret = apr_pstrcat(r->pool, ret, "?", r->args, NULL);

                }

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

            }

        }

        return status;

    }

    return DECLINED;

}

static void register_hooks(apr_pool_t *p)

{

    static const char * const aszSucc[]={ "mod_userdir.c",

                                          "mod_vhost_alias.c",NULL };

    ap_hook_translate_name(translate_alias_redir,NULL,aszSucc,APR_HOOK_MIDDLE);

    ap_hook_fixups(fixup_redir,NULL,NULL,APR_HOOK_MIDDLE);

}

AP_DECLARE_MODULE(alias) =

{

    STANDARD20_MODULE_STUFF,

    create_alias_dir_config,       /* dir config creater */

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

    create_alias_config,           /* server config */

    merge_alias_config,            /* merge server configs */

    alias_cmds,                    /* command apr_table_t */

    register_hooks                 /* register hooks */

};