request.c

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

/* Copyright 2001-2005 The Apache Software Foundation or its licensors, as
 * applicable.
 *
 * Licensed 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_request.c: functions to get and process requests
 *
 * Rob McCool 3/21/93
 *
 * Thoroughly revamped by rst for Apache.  NB this file reads
 * best from the bottom up.
 *
 */

#include "apr_strings.h"
#include "apr_file_io.h"
#include "apr_fnmatch.h"

#define APR_WANT_STRFUNC
#include "apr_want.h"

#define CORE_PRIVATE
#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_request.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_log.h"
#include "http_main.h"
#include "util_filter.h"
#include "util_charset.h"
#include "util_script.h"

#include "mod_core.h"

#if APR_HAVE_STDARG_H
#include <stdarg.h>
#endif

APR_HOOK_STRUCT(
    APR_HOOK_LINK(translate_name)
    APR_HOOK_LINK(map_to_storage)
    APR_HOOK_LINK(check_user_id)
    APR_HOOK_LINK(fixups)
    APR_HOOK_LINK(type_checker)
    APR_HOOK_LINK(access_checker)
    APR_HOOK_LINK(auth_checker)
    APR_HOOK_LINK(insert_filter)
    APR_HOOK_LINK(create_request)
)

AP_IMPLEMENT_HOOK_RUN_FIRST(int,translate_name,
                            (request_rec *r), (r), DECLINED)
AP_IMPLEMENT_HOOK_RUN_FIRST(int,map_to_storage,
                            (request_rec *r), (r), DECLINED)
AP_IMPLEMENT_HOOK_RUN_FIRST(int,check_user_id,
                            (request_rec *r), (r), DECLINED)
AP_IMPLEMENT_HOOK_RUN_ALL(int,fixups,
                          (request_rec *r), (r), OK, DECLINED)
AP_IMPLEMENT_HOOK_RUN_FIRST(int,type_checker,
                            (request_rec *r), (r), DECLINED)
AP_IMPLEMENT_HOOK_RUN_ALL(int,access_checker,
                          (request_rec *r), (r), OK, DECLINED)
AP_IMPLEMENT_HOOK_RUN_FIRST(int,auth_checker,
                            (request_rec *r), (r), DECLINED)
AP_IMPLEMENT_HOOK_VOID(insert_filter, (request_rec *r), (r))
AP_IMPLEMENT_HOOK_RUN_ALL(int, create_request,
                          (request_rec *r), (r), OK, DECLINED)


static int decl_die(int status, char *phase, request_rec *r)
{
    if (status == DECLINED) {
        ap_log_rerror(APLOG_MARK, APLOG_CRIT, 0, r,
                      "configuration error:  couldn't %s: %s", phase, r->uri);
        return HTTP_INTERNAL_SERVER_ERROR;
    }
    else {
        return status;
    }
}

/* This is the master logic for processing requests.  Do NOT duplicate
 * this logic elsewhere, or the security model will be broken by future
 * API changes.  Each phase must be individually optimized to pick up
 * redundant/duplicate calls by subrequests, and redirects.
 */
AP_DECLARE(int) ap_process_request_internal(request_rec *r)
{
    int file_req = (r->main && r->filename);
    int access_status;

    /* Ignore embedded %2F's in path for proxy requests */
    if (!r->proxyreq && r->parsed_uri.path) {
        core_dir_config *d;
        d = ap_get_module_config(r->per_dir_config, &core_module);
        if (d->allow_encoded_slashes) {
            access_status = ap_unescape_url_keep2f(r->parsed_uri.path);
        }
        else {
            access_status = ap_unescape_url(r->parsed_uri.path);
        }
        if (access_status) {
            if (access_status == HTTP_NOT_FOUND) {
                if (! d->allow_encoded_slashes) {
                    ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r,
                                  "found %%2f (encoded '/') in URI "
                                  "(decoded='%s'), returning 404",
                                  r->parsed_uri.path);
                }
            }
            return access_status;
        }
    }

    ap_getparents(r->uri);     /* OK --- shrinking transformations... */

    /* All file subrequests are a huge pain... they cannot bubble through the
     * next several steps.  Only file subrequests are allowed an empty uri,
     * otherwise let translate_name kill the request.
     */
    if (!file_req) {
        if ((access_status = ap_location_walk(r))) {
            return access_status;
        }

        if ((access_status = ap_run_translate_name(r))) {
            return decl_die(access_status, "translate", r);
        }
    }

    /* Reset to the server default config prior to running map_to_storage
     */
    r->per_dir_config = r->server->lookup_defaults;

    if ((access_status = ap_run_map_to_storage(r))) {
        /* This request wasn't in storage (e.g. TRACE) */
        return access_status;
    }

    /* Excluding file-specific requests with no 'true' URI...
     */
    if (!file_req) {
        /* Rerun the location walk, which overrides any map_to_storage config.
         */
        if ((access_status = ap_location_walk(r))) {
            return access_status;
        }
    }

    /* Only on the main request! */
    if (r->main == NULL) {
        if ((access_status = ap_run_header_parser(r))) {
            return access_status;
        }
    }

    /* Skip authn/authz if the parent or prior request passed the authn/authz,
     * and that configuration didn't change (this requires optimized _walk()
     * functions in map_to_storage that use the same merge results given
     * identical input.)  If the config changes, we must re-auth.
     */
    if (r->main && (r->main->per_dir_config == r->per_dir_config)) {
        r->user = r->main->user;
        r->ap_auth_type = r->main->ap_auth_type;
    }
    else if (r->prev && (r->prev->per_dir_config == r->per_dir_config)) {
        r->user = r->prev->user;
        r->ap_auth_type = r->prev->ap_auth_type;
    }
    else {
        switch (ap_satisfies(r)) {
        case SATISFY_ALL:
        case SATISFY_NOSPEC:
            if ((access_status = ap_run_access_checker(r)) != 0) {
                return decl_die(access_status, "check access", r);
            }

            if (ap_some_auth_required(r)) {
                if (((access_status = ap_run_check_user_id(r)) != 0)
                    || !ap_auth_type(r)) {
                    return decl_die(access_status, ap_auth_type(r)
                                  ? "check user.  No user file?"
                                  : "perform authentication. AuthType not set!",
                                  r);
                }

                if (((access_status = ap_run_auth_checker(r)) != 0)
                    || !ap_auth_type(r)) {
                    return decl_die(access_status, ap_auth_type(r)
                                  ? "check access.  No groups file?"
                                  : "perform authentication. AuthType not set!",
                                   r);
                }
            }
            break;

        case SATISFY_ANY:
            if (((access_status = ap_run_access_checker(r)) != 0)) {
                if (!ap_some_auth_required(r)) {
                    return decl_die(access_status, "check access", r);
                }

                if (((access_status = ap_run_check_user_id(r)) != 0)
                    || !ap_auth_type(r)) {
                    return decl_die(access_status, ap_auth_type(r)
                                  ? "check user.  No user file?"
                                  : "perform authentication. AuthType not set!",
                                  r);
                }

                if (((access_status = ap_run_auth_checker(r)) != 0)
                    || !ap_auth_type(r)) {
                    return decl_die(access_status, ap_auth_type(r)
                                  ? "check access.  No groups file?"
                                  : "perform authentication. AuthType not set!",
                                  r);
                }
            }
            break;
        }
    }
    /* XXX Must make certain the ap_run_type_checker short circuits mime
     * in mod-proxy for r->proxyreq && r->parsed_uri.scheme
     *                              && !strcmp(r->parsed_uri.scheme, "http")
     */
    if ((access_status = ap_run_type_checker(r)) != 0) {
        return decl_die(access_status, "find types", r);
    }

    if ((access_status = ap_run_fixups(r)) != 0) {
        return access_status;
    }

    return OK;
}


/* Useful caching structures to repeat _walk/merge sequences as required
 * when a subrequest or redirect reuses substantially the same config.
 *
 * Directive order in the httpd.conf file and its Includes significantly
 * impact this optimization.  Grouping common blocks at the front of the
 * config that are less likely to change between a request and
 * its subrequests, or between a request and its redirects reduced
 * the work of these functions significantly.
 */

typedef struct walk_walked_t {
    ap_conf_vector_t *matched; /* A dir_conf sections we matched */
    ap_conf_vector_t *merged;  /* The dir_conf merged result */
} walk_walked_t;

typedef struct walk_cache_t {
    const char         *cached;          /* The identifier we matched */
    ap_conf_vector_t  **dir_conf_tested; /* The sections we matched against */
    ap_conf_vector_t   *dir_conf_merged; /* Base per_dir_config */
    ap_conf_vector_t   *per_dir_result;  /* per_dir_config += walked result */
    apr_array_header_t *walked;          /* The list of walk_walked_t results */
} walk_cache_t;

static walk_cache_t *prep_walk_cache(apr_size_t t, request_rec *r)
{
    walk_cache_t *cache;
    void **note;

    /* Find the most relevant, recent entry to work from.  That would be
     * this request (on the second call), or the parent request of a
     * subrequest, or the prior request of an internal redirect.  Provide
     * this _walk()er with a copy it is allowed to munge.  If there is no
     * parent or prior cached request, then create a new walk cache.
     */
    note = ap_get_request_note(r, t);
    if (!note) {
        return NULL;
    }

    if (!(cache = *note)) {
        void **inherit_note;

        if ((r->main
             && ((inherit_note = ap_get_request_note(r->main, t)))
             && *inherit_note)
            || (r->prev
                && ((inherit_note = ap_get_request_note(r->prev, t)))
                && *inherit_note)) {
            cache = apr_pmemdup(r->pool, *inherit_note,
                                sizeof(*cache));
            cache->walked = apr_array_copy(r->pool, cache->walked);
        }
        else {
            cache = apr_pcalloc(r->pool, sizeof(*cache));
            cache->walked = apr_array_make(r->pool, 4, sizeof(walk_walked_t));
        }

        *note = cache;
    }
    return cache;
}

/*****************************************************************
 *
 * Getting and checking directory configuration.  Also checks the
 * FollowSymlinks and FollowSymOwner stuff, since this is really the
 * only place that can happen (barring a new mid_dir_walk callout).
 *
 * We can't do it as an access_checker module function which gets
 * called with the final per_dir_config, since we could have a directory
 * with FollowSymLinks disabled, which contains a symlink to another
 * with a .htaccess file which turns FollowSymLinks back on --- and
 * access in such a case must be denied.  So, whatever it is that
 * checks FollowSymLinks needs to know the state of the options as
 * they change, all the way down.
 */


/*
 * resolve_symlink must _always_ be called on an APR_LNK file type!
 * It will resolve the actual target file type, modification date, etc,
 * and provide any processing required for symlink evaluation.
 * Path must already be cleaned, no trailing slash, no multi-slashes,
 * and don't call this on the root!
 *
 * Simply, the number of times we deref a symlink are minimal compared
 * to the number of times we had an extra lstat() since we 'weren't sure'.
 *
 * To optimize, we stat() anything when given (opts & OPT_SYM_LINKS), otherwise
 * we start off with an lstat().  Every lstat() must be dereferenced in case
 * it points at a 'nasty' - we must always rerun check_safe_file (or similar.)
 */
static int resolve_symlink(char *d, apr_finfo_t *lfi, int opts, apr_pool_t *p)
{
    apr_finfo_t fi;
    int res;
    const char *savename;

    if (!(opts & (OPT_SYM_OWNER | OPT_SYM_LINKS))) {
        return HTTP_FORBIDDEN;
    }

    /* Save the name from the valid bits. */
    savename = (lfi->valid & APR_FINFO_NAME) ? lfi->name : NULL;

    if (opts & OPT_SYM_LINKS) {