mod_rewrite.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 1999-2005 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.
 */

/*                       _                            _ _
**   _ __ ___   ___   __| |    _ __ _____      ___ __(_) |_ ___
**  | '_ ` _ \ / _ \ / _` |   | '__/ _ \ \ /\ / / '__| | __/ _ \
**  | | | | | | (_) | (_| |   | | |  __/\ V  V /| |  | | ||  __/
**  |_| |_| |_|\___/ \__,_|___|_|  \___| \_/\_/ |_|  |_|\__\___|
**                       |_____|
**
**  URL Rewriting Module
**
**  This module uses a rule-based rewriting engine (based on a
**  regular-expression parser) to rewrite requested URLs on the fly.
**
**  It supports an unlimited number of additional rule conditions (which can
**  operate on a lot of variables, even on HTTP headers) for granular
**  matching and even external database lookups (either via plain text
**  tables, DBM hash files or even external processes) for advanced URL
**  substitution.
**
**  It operates on the full URLs (including the PATH_INFO part) both in
**  per-server context (httpd.conf) and per-dir context (.htaccess) and even
**  can generate QUERY_STRING parts on result.   The rewriting result finally
**  can lead to internal subprocessing, external request redirection or even
**  to internal proxy throughput.
**
**  This module was originally written in April 1996 and
**  gifted exclusively to the The Apache Software Foundation in July 1997 by
**
**      Ralf S. Engelschall
**      rse engelschall.com
**      www.engelschall.com
*/

#include "apr.h"
#include "apr_strings.h"
#include "apr_hash.h"
#include "apr_user.h"
#include "apr_lib.h"
#include "apr_signal.h"
#include "apr_global_mutex.h"

#define APR_WANT_STRFUNC
#define APR_WANT_IOVEC
#include "apr_want.h"

#if APR_HAVE_UNISTD_H
#include <unistd.h>
#endif
#if APR_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#include "ap_config.h"
#include "httpd.h"
#include "http_config.h"
#include "http_request.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"
#include "mod_rewrite.h"

/* mod_ssl.h is not safe for inclusion in 2.0, so duplicate the
 * optional function declarations. */
APR_DECLARE_OPTIONAL_FN(char *, ssl_var_lookup,
                        (apr_pool_t *, server_rec *,
                         conn_rec *, request_rec *,
                         char *));
APR_DECLARE_OPTIONAL_FN(int, ssl_is_https, (conn_rec *));

#if !defined(OS2) && !defined(WIN32) && !defined(BEOS)  && !defined(NETWARE)
#include "unixd.h"
#define MOD_REWRITE_SET_MUTEX_PERMS /* XXX Apache should define something */
#endif

/*
** +-------------------------------------------------------+
** |                                                       |
** |             static module configuration
** |                                                       |
** +-------------------------------------------------------+
*/


/*
**  Our interface to the Apache server kernel:
**
**  o  Runtime logic of a request is as following:
**       while(request or subrequest)
**           foreach(stage #0...#9)
**               foreach(module) (**)
**                   try to run hook
**
**  o  the order of modules at (**) is the inverted order as
**     given in the "Configuration" file, i.e. the last module
**     specified is the first one called for each hook!
**     The core module is always the last!
**
**  o  there are two different types of result checking and
**     continue processing:
**     for hook #0,#1,#4,#5,#6,#8:
**         hook run loop stops on first modules which gives
**         back a result != DECLINED, i.e. it usually returns OK
**         which says "OK, module has handled this _stage_" and for #1
**         this have not to mean "Ok, the filename is now valid".
**     for hook #2,#3,#7,#9:
**         all hooks are run, independend of result
**
**  o  at the last stage, the core module always
**       - says "HTTP_BAD_REQUEST" if r->filename does not begin with "/"
**       - prefix URL with document_root or replaced server_root
**         with document_root and sets r->filename
**       - always return a "OK" independed if the file really exists
**         or not!
*/

    /* the module (predeclaration) */
module AP_MODULE_DECLARE_DATA rewrite_module;

    /* rewritemap int: handler function registry */
static apr_hash_t *mapfunc_hash;

    /* the cache */
static cache *cachep;

    /* whether proxy module is available or not */
static int proxy_available;

static const char *lockname;
static apr_global_mutex_t *rewrite_mapr_lock_acquire = NULL;
static apr_global_mutex_t *rewrite_log_lock = NULL;

/* Optional functions imported from mod_ssl when loaded: */
static APR_OPTIONAL_FN_TYPE(ssl_var_lookup) *rewrite_ssl_lookup = NULL;
static APR_OPTIONAL_FN_TYPE(ssl_is_https) *rewrite_is_https = NULL;

/*
** +-------------------------------------------------------+
** |                                                       |
** |           configuration directive handling
** |                                                       |
** +-------------------------------------------------------+
*/

/*
**
**  per-server configuration structure handling
**
*/

static void *config_server_create(apr_pool_t *p, server_rec *s)
{
    rewrite_server_conf *a;

    a = (rewrite_server_conf *)apr_pcalloc(p, sizeof(rewrite_server_conf));

    a->state           = ENGINE_DISABLED;
    a->options         = OPTION_NONE;
    a->rewritelogfile  = NULL;
    a->rewritelogfp    = NULL;
    a->rewriteloglevel = 0;
    a->rewritemaps     = apr_array_make(p, 2, sizeof(rewritemap_entry));
    a->rewriteconds    = apr_array_make(p, 2, sizeof(rewritecond_entry));
    a->rewriterules    = apr_array_make(p, 2, sizeof(rewriterule_entry));
    a->server          = s;
    a->redirect_limit  = 0; /* unset (use default) */

    return (void *)a;
}

static void *config_server_merge(apr_pool_t *p, void *basev, void *overridesv)
{
    rewrite_server_conf *a, *base, *overrides;

    a         = (rewrite_server_conf *)apr_pcalloc(p,
                                                   sizeof(rewrite_server_conf));
    base      = (rewrite_server_conf *)basev;
    overrides = (rewrite_server_conf *)overridesv;

    a->state   = overrides->state;
    a->options = overrides->options;
    a->server  = overrides->server;
    a->redirect_limit = overrides->redirect_limit
                          ? overrides->redirect_limit
                          : base->redirect_limit;

    if (a->options & OPTION_INHERIT) {
        /*
         *  local directives override
         *  and anything else is inherited
         */
        a->rewriteloglevel = overrides->rewriteloglevel != 0
                             ? overrides->rewriteloglevel
                             : base->rewriteloglevel;
        a->rewritelogfile  = overrides->rewritelogfile != NULL
                             ? overrides->rewritelogfile
                             : base->rewritelogfile;
        a->rewritelogfp    = overrides->rewritelogfp != NULL
                             ? overrides->rewritelogfp
                             : base->rewritelogfp;
        a->rewritemaps     = apr_array_append(p, overrides->rewritemaps,
                                              base->rewritemaps);
        a->rewriteconds    = apr_array_append(p, overrides->rewriteconds,
                                              base->rewriteconds);
        a->rewriterules    = apr_array_append(p, overrides->rewriterules,
                                              base->rewriterules);
    }
    else {
        /*
         *  local directives override
         *  and anything else gets defaults
         */
        a->rewriteloglevel = overrides->rewriteloglevel;
        a->rewritelogfile  = overrides->rewritelogfile;
        a->rewritelogfp    = overrides->rewritelogfp;
        a->rewritemaps     = overrides->rewritemaps;
        a->rewriteconds    = overrides->rewriteconds;
        a->rewriterules    = overrides->rewriterules;
    }

    return (void *)a;
}


/*
**
**  per-directory configuration structure handling
**
*/

static void *config_perdir_create(apr_pool_t *p, char *path)
{
    rewrite_perdir_conf *a;

    a = (rewrite_perdir_conf *)apr_pcalloc(p, sizeof(rewrite_perdir_conf));

    a->state           = ENGINE_DISABLED;
    a->options         = OPTION_NONE;
    a->baseurl         = NULL;
    a->rewriteconds    = apr_array_make(p, 2, sizeof(rewritecond_entry));
    a->rewriterules    = apr_array_make(p, 2, sizeof(rewriterule_entry));
    a->redirect_limit  = 0; /* unset (use server config) */

    if (path == NULL) {
        a->directory = NULL;
    }
    else {
        /* make sure it has a trailing slash */
        if (path[strlen(path)-1] == '/') {
            a->directory = apr_pstrdup(p, path);
        }
        else {
            a->directory = apr_pstrcat(p, path, "/", NULL);
        }
    }

    return (void *)a;
}

static void *config_perdir_merge(apr_pool_t *p, void *basev, void *overridesv)
{
    rewrite_perdir_conf *a, *base, *overrides;

    a         = (rewrite_perdir_conf *)apr_pcalloc(p,
                                                  sizeof(rewrite_perdir_conf));
    base      = (rewrite_perdir_conf *)basev;
    overrides = (rewrite_perdir_conf *)overridesv;

    a->state     = overrides->state;
    a->options   = overrides->options;
    a->directory = overrides->directory;
    a->baseurl   = overrides->baseurl;
    a->redirect_limit = overrides->redirect_limit
                          ? overrides->redirect_limit
                          : base->redirect_limit;

    if (a->options & OPTION_INHERIT) {
        a->rewriteconds = apr_array_append(p, overrides->rewriteconds,
                                           base->rewriteconds);
        a->rewriterules = apr_array_append(p, overrides->rewriterules,
                                           base->rewriterules);
    }
    else {
        a->rewriteconds = overrides->rewriteconds;
        a->rewriterules = overrides->rewriterules;
    }

    return (void *)a;
}


/*
**
**  the configuration commands
**
*/

static const char *cmd_rewriteengine(cmd_parms *cmd,
                                     void *in_dconf, int flag)
{
    rewrite_perdir_conf *dconf = in_dconf;
    rewrite_server_conf *sconf;

    sconf = ap_get_module_config(cmd->server->module_config, &rewrite_module);

    if (cmd->path == NULL) { /* is server command */
        sconf->state = (flag ? ENGINE_ENABLED : ENGINE_DISABLED);
    }
    else                   /* is per-directory command */ {
        dconf->state = (flag ? ENGINE_ENABLED : ENGINE_DISABLED);
    }

    return NULL;
}

static const char *cmd_rewriteoptions(cmd_parms *cmd,
                                      void *in_dconf, const char *option)
{
    int options = 0, limit = 0;
    char *w;

    while (*option) {
        w = ap_getword_conf(cmd->pool, &option);

        if (!strcasecmp(w, "inherit")) {
            options |= OPTION_INHERIT;
        }
        else if (!strncasecmp(w, "MaxRedirects=", 13)) {
            limit = atoi(&w[13]);
            if (limit <= 0) {
                return "RewriteOptions: MaxRedirects takes a number greater "
                       "than zero.";
            }
        }
        else if (!strcasecmp(w, "MaxRedirects")) { /* be nice */
            return "RewriteOptions: MaxRedirects has the format MaxRedirects"
                   "=n.";
        }
        else {
            return apr_pstrcat(cmd->pool, "RewriteOptions: unknown option '",
                               w, "'", NULL);
        }
    }

    /* put it into the appropriate config */
    if (cmd->path == NULL) { /* is server command */
        rewrite_server_conf *conf =
            ap_get_module_config(cmd->server->module_config,
                                 &rewrite_module);

        conf->options |= options;
        conf->redirect_limit = limit;
    }
    else {                  /* is per-directory command */
        rewrite_perdir_conf *conf = in_dconf;

        conf->options |= options;
        conf->redirect_limit = limit;
    }

    return NULL;
}

static const char *cmd_rewritelog(cmd_parms *cmd, void *dconf, const char *a1)
{
    rewrite_server_conf *sconf;

    sconf = ap_get_module_config(cmd->server->module_config, &rewrite_module);

    sconf->rewritelogfile = a1;

    return NULL;
}

static const char *cmd_rewriteloglevel(cmd_parms *cmd, void *dconf,
                                       const char *a1)
{
    rewrite_server_conf *sconf;

    sconf = ap_get_module_config(cmd->server->module_config, &rewrite_module);