mod_rewrite.c

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                                                  char *str)
{
    char *cp;
    char *cp1;
    char *cp2;
    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(pool *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 (ap_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 = ap_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] = ap_pstrdup(p, val);
            cfg->env[i+1] = NULL;
        }
        else {
            return "RewriteRule: too many environment flags 'E'";
        }
    }
    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 ap_pstrcat(p, "RewriteRule: unknown flag '", key, "'\n", NULL);
    }
    return NULL;
}


/*
**
**  Global Module Initialization
**  [called from read_config() after all
**  config commands were already called]
**
*/

static void init_module(server_rec *s, pool *p)
{
    /* check if proxy module is available */
    proxy_available = (ap_find_linked_module("mod_proxy.c") != NULL);

    /* create the rewriting lockfile in the parent */
    rewritelock_create(s, p);
    ap_register_cleanup(p, (void *)s, rewritelock_remove, ap_null_cleanup);

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


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

static void init_child(server_rec *s, pool *p)
{
     /* open the rewriting lockfile */
     rewritelock_open(s, p);

     /* 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)
{
    void *sconf;
    rewrite_server_conf *conf;
    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
     */
    sconf = r->server->module_config;
    conf  = (rewrite_server_conf *)ap_get_module_config(sconf,
                                                        &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 = ap_pstrcat(r->pool, "REDIRECT_", ENVVAR_SCRIPT_URL, NULL);
         var = ap_table_get(r->subprocess_env, var);
         if (var == NULL) {
             ap_table_setn(r->subprocess_env, ENVVAR_SCRIPT_URL, r->uri);
         }
         else {
             ap_table_setn(r->subprocess_env, ENVVAR_SCRIPT_URL, var);
         }
    }
    else {
         var = ap_table_get(r->main->subprocess_env, ENVVAR_SCRIPT_URL);
         ap_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 {
        ap_snprintf(buf, sizeof(buf), ":%u", port);
        thisport = buf;
    }
    thisurl = ap_table_get(r->subprocess_env, ENVVAR_SCRIPT_URL);

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

    /* if filename was not initially set,
     * we start with the requested URI
     */
    if (r->filename == NULL) {
        r->filename = ap_pstrdup(r->pool, r->uri);
        rewritelog(r, 2, "init rewrite engine with requested uri %s",
                   r->filename);
    }

    /*
     *  now apply the rules ...
     */
    rulestatus = apply_rewrite_list(r, conf->rewriterules, NULL);
    if (rulestatus) {
        unsigned skip;

        if (strlen(r->filename) > 6 &&
            strncmp(r->filename, "proxy:", 6) == 0) {
            /* it should be go on as an internal proxy request */

            /* check if the proxy module is enabled, so
             * we can actually use it!
             */
            if (!proxy_available) {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
                             "attempt to make remote request from mod_rewrite "
                             "without proxy enabled: %s", r->filename);
                return FORBIDDEN;
            }

            /* make sure the QUERY_STRING and
             * PATH_INFO parts get incorporated
             */
            if (r->path_info != NULL) {
                r->filename = ap_pstrcat(r->pool, r->filename,
                                         r->path_info, NULL);
            }
            if (r->args != NULL &&
                r->uri == r->unparsed_uri) {
                /* see proxy_http:proxy_http_canon() */
                r->filename = ap_pstrcat(r->pool, r->filename,
                                         "?", r->args, NULL);
            }

            /* now make sure the request gets handled by the proxy handler */
            r->proxyreq = PROXY_PASS;
            r->handler  = "proxy-server";

            rewritelog(r, 1, "go-ahead with proxy request %s [OK]",
                       r->filename);
            return OK;
        }
        else if ((skip = is_absolute_uri(r->filename)) > 0) {
            /* it was finally rewritten to a remote URL */

            if (rulestatus != ACTION_NOESCAPE) {
                rewritelog(r, 1, "escaping %s for redirect", r->filename);
                r->filename = escape_absolute_uri(r->pool, r->filename, skip);
            }

            /* append the QUERY_STRING part */
            if (r->args) {
                r->filename = ap_pstrcat(r->pool, r->filename, "?",
                                         (rulestatus == ACTION_NOESCAPE)
                                           ? r->args
                                           : ap_escape_uri(r->pool, r->args),
                                         NULL);
            }

            /* determine HTTP redirect response code */
            if (ap_is_HTTP_REDIRECT(r->status)) {
                n = r->status;
                r->status = HTTP_OK; /* make Apache kernel happy */
            }
            else {
                n = REDIRECT;
            }

            /* now do the redirection */
            ap_table_setn(r->headers_out, "Location", r->filename);
            rewritelog(r, 1, "redirect to %s [REDIRECT/%d]", r->filename, n);
            return n;
        }
        else if (strlen(r->filename) > 10 &&
                 strncmp(r->filename, "forbidden:", 10) == 0) {
            /* This URLs is forced to be forbidden for the requester */
            return FORBIDDEN;
        }
        else if (strlen(r->filename) > 5 &&
                 strncmp(r->filename, "gone:", 5) == 0) {
            /* This URLs is forced to be gone */
            return HTTP_GONE;
        }
        else if (strlen(r->filename) > 12 &&
                 strncmp(r->filename, "passthrough:", 12) == 0) {