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。

    char *cp3;
    char *key;
    char *val;
    const char *err;

    if (str[0] != '[' || str[strlen(str)-1] != ']') {
        return "RewriteRule: bad flag delimiters";
    }

    cp = str+1;
    str[strlen(str)-1] = ','; /* for simpler parsing */
    for ( ; *cp != '\0'; ) {
        /* skip whitespaces */
        for ( ; (*cp == ' ' || *cp == '\t') && *cp != '\0'; cp++)
            ;
        if (*cp == '\0') {
            break;
        }
        cp1 = cp;
        if ((cp2 = strchr(cp, ',')) != NULL) {
            cp = cp2+1;
            for ( ; (*(cp2-1) == ' ' || *(cp2-1) == '\t'); cp2--)
                ;
            *cp2 = '\0';
            if ((cp3 = strchr(cp1, '=')) != NULL) {
                *cp3 = '\0';
                key = cp1;
                val = cp3+1;
            }
            else {
                key = cp1;
                val = "";
            }
            if ((err = cmd_rewriterule_setflag(p, cfg, key, val)) != NULL) {
                return err;
            }
        }
        else {
            break;
        }
    }

    return NULL;
}

static const char *cmd_rewriterule_setflag(apr_pool_t *p,
                                           rewriterule_entry *cfg,
                                           char *key, char *val)
{
    int status = 0;
    int i;

    if (   strcasecmp(key, "redirect") == 0
        || strcasecmp(key, "R") == 0       ) {
        cfg->flags |= RULEFLAG_FORCEREDIRECT;
        if (strlen(val) > 0) {
            if (strcasecmp(val, "permanent") == 0) {
                status = HTTP_MOVED_PERMANENTLY;
            }
            else if (strcasecmp(val, "temp") == 0) {
                status = HTTP_MOVED_TEMPORARILY;
            }
            else if (strcasecmp(val, "seeother") == 0) {
                status = HTTP_SEE_OTHER;
            }
            else if (apr_isdigit(*val)) {
                status = atoi(val);
            }
            if (!ap_is_HTTP_REDIRECT(status)) {
                return "RewriteRule: invalid HTTP response code "
                       "for flag 'R'";
            }
            cfg->forced_responsecode = status;
        }
    }
    else if (   strcasecmp(key, "noescape") == 0
        || strcasecmp(key, "NE") == 0       ) {
        cfg->flags |= RULEFLAG_NOESCAPE;
    }
    else if (   strcasecmp(key, "last") == 0
             || strcasecmp(key, "L") == 0   ) {
        cfg->flags |= RULEFLAG_LASTRULE;
    }
    else if (   strcasecmp(key, "next") == 0
             || strcasecmp(key, "N") == 0   ) {
        cfg->flags |= RULEFLAG_NEWROUND;
    }
    else if (   strcasecmp(key, "chain") == 0
             || strcasecmp(key, "C") == 0    ) {
        cfg->flags |= RULEFLAG_CHAIN;
    }
    else if (   strcasecmp(key, "type") == 0
             || strcasecmp(key, "T") == 0   ) {
        cfg->forced_mimetype = apr_pstrdup(p, val);
        ap_str_tolower(cfg->forced_mimetype);
    }
    else if (   strcasecmp(key, "env") == 0
             || strcasecmp(key, "E") == 0   ) {
        for (i = 0; (cfg->env[i] != NULL) && (i < MAX_ENV_FLAGS); i++)
            ;
        if (i < MAX_ENV_FLAGS) {
            cfg->env[i] = apr_pstrdup(p, val);
            cfg->env[i+1] = NULL;
        }
        else {
            return "RewriteRule: too many environment flags 'E'";
        }
    }
    else  if ( strcasecmp(key, "cookie") == 0 || strcasecmp(key, "CO") == 0) {
        for (i = 0; (cfg->cookie[i] != NULL) && (i < MAX_COOKIE_FLAGS); i++)
            ;
        if (i < MAX_COOKIE_FLAGS) {
            cfg->cookie[i] = apr_pstrdup(p, val);
            cfg->cookie[i+1] = NULL;
        }
        else {
            return "RewriteRule: too many cookie flags 'CO'";
        }
    }
    else if (   strcasecmp(key, "nosubreq") == 0
             || strcasecmp(key, "NS") == 0      ) {
        cfg->flags |= RULEFLAG_IGNOREONSUBREQ;
    }
    else if (   strcasecmp(key, "proxy") == 0
             || strcasecmp(key, "P") == 0      ) {
        cfg->flags |= RULEFLAG_PROXY;
    }
    else if (   strcasecmp(key, "passthrough") == 0
             || strcasecmp(key, "PT") == 0      ) {
        cfg->flags |= RULEFLAG_PASSTHROUGH;
    }
    else if (   strcasecmp(key, "skip") == 0
             || strcasecmp(key, "S") == 0   ) {
        cfg->skip = atoi(val);
    }
    else if (   strcasecmp(key, "forbidden") == 0
             || strcasecmp(key, "F") == 0   ) {
        cfg->flags |= RULEFLAG_FORBIDDEN;
    }
    else if (   strcasecmp(key, "gone") == 0
             || strcasecmp(key, "G") == 0   ) {
        cfg->flags |= RULEFLAG_GONE;
    }
    else if (   strcasecmp(key, "qsappend") == 0
             || strcasecmp(key, "QSA") == 0   ) {
        cfg->flags |= RULEFLAG_QSAPPEND;
    }
    else if (   strcasecmp(key, "nocase") == 0
             || strcasecmp(key, "NC") == 0    ) {
        cfg->flags |= RULEFLAG_NOCASE;
    }
    else {
        return apr_pstrcat(p, "RewriteRule: unknown flag '", key, "'", NULL);
    }
    return NULL;
}


/*
**
**  Global Module Initialization
**
*/

static int pre_config(apr_pool_t *pconf,
                      apr_pool_t *plog,
                      apr_pool_t *ptemp)
{
    APR_OPTIONAL_FN_TYPE(ap_register_rewrite_mapfunc) *map_pfn_register;

    /* register int: rewritemap handlers */
    mapfunc_hash = apr_hash_make(pconf);
    map_pfn_register = APR_RETRIEVE_OPTIONAL_FN(ap_register_rewrite_mapfunc);
    if (map_pfn_register) {
        map_pfn_register("tolower", rewrite_mapfunc_tolower);
        map_pfn_register("toupper", rewrite_mapfunc_toupper);
        map_pfn_register("escape", rewrite_mapfunc_escape);
        map_pfn_register("unescape", rewrite_mapfunc_unescape);
    }
    return OK;
}

static int post_config(apr_pool_t *p,
                       apr_pool_t *plog,
                       apr_pool_t *ptemp,
                       server_rec *s)
{
    apr_status_t rv;
    void *data;
    int first_time = 0;
    const char *userdata_key = "rewrite_init_module";

    apr_pool_userdata_get(&data, userdata_key, s->process->pool);
    if (!data) {
        first_time = 1;
        apr_pool_userdata_set((const void *)1, userdata_key,
                              apr_pool_cleanup_null, s->process->pool);
    }

    /* check if proxy module is available */
    proxy_available = (ap_find_linked_module("mod_proxy.c") != NULL);

    /* create the rewriting lockfiles in the parent */
    if ((rv = apr_global_mutex_create(&rewrite_log_lock, NULL,
                                      APR_LOCK_DEFAULT, p)) != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s,
                     "mod_rewrite: could not create rewrite_log_lock");
        return HTTP_INTERNAL_SERVER_ERROR;
    }

#ifdef MOD_REWRITE_SET_MUTEX_PERMS
    rv = unixd_set_global_mutex_perms(rewrite_log_lock);
    if (rv != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s,
                     "mod_rewrite: Could not set permissions on "
                     "rewrite_log_lock; check User and Group directives");
        return HTTP_INTERNAL_SERVER_ERROR;
    }
#endif

    rv = rewritelock_create(s, p);
    if (rv != APR_SUCCESS) {
        return HTTP_INTERNAL_SERVER_ERROR;
    }

    apr_pool_cleanup_register(p, (void *)s, rewritelock_remove,
                              apr_pool_cleanup_null);

    /* step through the servers and
     * - open each rewriting logfile
     * - open the RewriteMap prg:xxx programs
     */
    for (; s; s = s->next) {
        if (!open_rewritelog(s, p)) {
            return HTTP_INTERNAL_SERVER_ERROR;
        }

        if (!first_time) {
            if (run_rewritemap_programs(s, p) != APR_SUCCESS) {
                return HTTP_INTERNAL_SERVER_ERROR;
            }
        }
    }

    rewrite_ssl_lookup = APR_RETRIEVE_OPTIONAL_FN(ssl_var_lookup);
    rewrite_is_https = APR_RETRIEVE_OPTIONAL_FN(ssl_is_https);

    return OK;
}


/*
**
**  Per-Child Module Initialization
**  [called after a child process is spawned]
**
*/

static void init_child(apr_pool_t *p, server_rec *s)
{
    apr_status_t rv;

    if (lockname != NULL && *(lockname) != '\0') {
        rv = apr_global_mutex_child_init(&rewrite_mapr_lock_acquire,
                                         lockname, p);
        if (rv != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s,
                         "mod_rewrite: could not init rewrite_mapr_lock_acquire"
                         " in child");
        }
    }

    rv = apr_global_mutex_child_init(&rewrite_log_lock, NULL, p);
    if (rv != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s,
                     "mod_rewrite: could not init rewrite log lock in child");
    }
    
    /* create the lookup cache */
    cachep = init_cache(p);
}


/*
** +-------------------------------------------------------+
** |                                                       |
** |                     runtime hooks
** |                                                       |
** +-------------------------------------------------------+
*/

/*
**
**  URI-to-filename hook
**
**  [used for the rewriting engine triggered by
**  the per-server 'RewriteRule' directives]
**
*/

static int hook_uri2file(request_rec *r)
{
    rewrite_server_conf *conf;
    const char *saved_rulestatus;
    const char *var;
    const char *thisserver;
    char *thisport;
    const char *thisurl;
    char buf[512];
    char docroot[512];
    const char *ccp;
    unsigned int port;
    int rulestatus;
    int n;
    int l;

    /*
     *  retrieve the config structures
     */
    conf = ap_get_module_config(r->server->module_config, &rewrite_module);

    /*
     *  only do something under runtime if the engine is really enabled,
     *  else return immediately!
     */
    if (conf->state == ENGINE_DISABLED) {
        return DECLINED;
    }

    /*
     *  check for the ugly API case of a virtual host section where no
     *  mod_rewrite directives exists. In this situation we became no chance
     *  by the API to setup our default per-server config so we have to
     *  on-the-fly assume we have the default config. But because the default
     *  config has a disabled rewriting engine we are lucky because can
     *  just stop operating now.
     */
    if (conf->server != r->server) {
        return DECLINED;
    }

    /*
     *  add the SCRIPT_URL variable to the env. this is a bit complicated
     *  due to the fact that apache uses subrequests and internal redirects
     */

    if (r->main == NULL) {
         var = apr_pstrcat(r->pool, "REDIRECT_", ENVVAR_SCRIPT_URL, NULL);
         var = apr_table_get(r->subprocess_env, var);
         if (var == NULL) {
             apr_table_setn(r->subprocess_env, ENVVAR_SCRIPT_URL, r->uri);
         }
         else {
             apr_table_setn(r->subprocess_env, ENVVAR_SCRIPT_URL, var);
         }
    }
    else {
         var = apr_table_get(r->main->subprocess_env, ENVVAR_SCRIPT_URL);
         apr_table_setn(r->subprocess_env, ENVVAR_SCRIPT_URL, var);
    }

    /*
     *  create the SCRIPT_URI variable for the env
     */

    /* add the canonical URI of this URL */
    thisserver = ap_get_server_name(r);
    port = ap_get_server_port(r);
    if (ap_is_default_port(port, r)) {
        thisport = "";
    }
    else {
        apr_snprintf(buf, sizeof(buf), ":%u", port);
        thisport = buf;
    }
    thisurl = apr_table_get(r->subprocess_env, ENVVAR_SCRIPT_URL);

    /* set the variable */
    var = apr_pstrcat(r->pool, ap_http_method(r), "://", thisserver, thisport,
                      thisurl, NULL);
    apr_table_setn(r->subprocess_env, ENVVAR_SCRIPT_URI, var);

    if (!(saved_rulestatus = apr_table_get(r->notes,"mod_rewrite_rewritten"))) {
        /* if filename was not initially set,
         * we start with the requested URI
         */
        if (r->filename == NULL) {
            r->filename = apr_pstrdup(r->pool, r->uri);
            rewritelog(r, 2, "init rewrite engine with requested uri %s",
                       r->filename);
        }
        else {
            rewritelog(r, 2, "init rewrite engine with passed filename %s."
                       " Original uri = %s", r->filename, r->uri);
        }