httpd/server/util_filter.c

	util_filter.c revision 8c664b071856c6aa5ed0ff16e0dcd2428acaf97a
/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

#include "httpd.h"
#include "util_filter.h"

/*
 * ap_filter_rec_t:
 *
 * This (internal) structure is used for recording information about the
 * registered filters. It associates a name with the filter's callback
 * and filter type.
 *
 * At the moment, these are simply linked in a chain, so a ->next pointer
 * is available.
 */
typedef struct ap_filter_rec_t {
    const char *name;
    ap_filter_func filter_func;
    ap_filter_type ftype;

    struct ap_filter_rec_t *next;
} ap_filter_rec_t;

/* ### make this visible for direct manipulation?
 * ### use a hash table
 */
static ap_filter_rec_t *registered_filters = NULL;

/* NOTE: Apache's current design doesn't allow a pool to be passed thu,
   so we depend on a global to hold the correct pool
*/
#define FILTER_POOL     ap_global_hook_pool
#include "ap_hooks.h"   /* for ap_global_hook_pool */

/*
** This macro returns true/false if a given filter should be inserted BEFORE
** another filter. This will happen when one of: 1) there isn't another
** filter; 2) that filter has a higher filter type (class); 3) that filter
** corresponds to a different request.
*/
#define INSERT_BEFORE(f, before_this) ((before_this) == NULL \
                                       || (before_this)->ftype > (f)->ftype \
                                       || (before_this)->r != (f)->r)


static apr_status_t filter_cleanup(void *ctx)
{
    registered_filters = NULL;
    return APR_SUCCESS;
}

API_EXPORT(void) ap_register_filter(const char *name,
                                    ap_filter_func filter_func,
                                    ap_filter_type ftype)
{
    ap_filter_rec_t *frec = apr_palloc(FILTER_POOL, sizeof(*frec));

    frec->name = name;
    frec->filter_func = filter_func;
    frec->ftype = ftype;

    frec->next = registered_filters;
    registered_filters = frec;

    apr_register_cleanup(FILTER_POOL, NULL, filter_cleanup, apr_null_cleanup);
}

API_EXPORT(void) ap_add_filter(const char *name, request_rec *r)
{
    ap_filter_rec_t *frec = registered_filters;

    for (; frec != NULL; frec = frec->next) {
        if (!strcasecmp(name, frec->name)) {
            ap_filter_t *f = apr_pcalloc(r->pool, sizeof(*f));

            f->filter_func = frec->filter_func;
            f->ctx = NULL;
            f->ftype = frec->ftype;
            f->r = r;

            if (INSERT_BEFORE(f, r->filters)) {
                f->next = r->filters;
                r->filters = f;
            }
            else {
                ap_filter_t *fscan = r->filters;
                while (!INSERT_BEFORE(f, fscan->next))
                    fscan = fscan->next;
                f->next = fscan->next;
                fscan->next = f;
            }

            break;
        }
    }
}

/* Pass the buckets to the next filter in the filter stack.  If the
 * current filter is a handler, we should get NULL passed in instead of
 * the current filter.  At that point, we can just call the first filter in
 * the stack, or r->filters.
 */
API_EXPORT(apr_status_t) ap_pass_brigade(ap_filter_t *next, ap_bucket_brigade *bb)
{
    if (next) {
        if (AP_BRIGADE_LAST(bb)->type == AP_BUCKET_EOS) {
            next->r->eos_sent = 1;
        }
        return next->filter_func(next, bb);
    }
    return AP_NOBODY_WROTE;
}

API_EXPORT(ap_bucket_brigade *) ap_get_saved_data(ap_filter_t *f,
                                                  ap_bucket_brigade **b)
{
    ap_bucket_brigade *bb = (ap_bucket_brigade *)f->ctx;

    /* If we have never stored any data in the filter, then we had better
     * create an empty bucket brigade so that we can concat.
     */
    if (!bb) {
        bb = ap_brigade_create(f->r->pool);
    }

    /* join the two brigades together.  *b is now empty so we can
     * safely destroy it.
     */
    AP_BRIGADE_CONCAT(bb, *b);
    ap_brigade_destroy(*b);
    /* clear out the filter's context pointer.  If we don't do this, then
     * when we save more data to the filter, we will be appended to what is
     * currently there.  This will mean repeating data.... BAD!  :-)
     */
    f->ctx = NULL;

    return bb;
}

API_EXPORT(void) ap_save_data_to_filter(ap_filter_t *f, ap_bucket_brigade **b)
{
    ap_bucket_brigade *bb = (ap_bucket_brigade *)f->ctx;
    ap_bucket *e;

    /* If have never stored any data in the filter, then we had better
     * create an empty bucket brigade so that we can concat.
     */
    if (!bb) {
        bb = ap_brigade_create(f->r->pool);
    }

    AP_RING_FOREACH(e, &bb->list, ap_bucket, link) {
    e->setaside(e);
    }
    AP_BRIGADE_CONCAT(bb, *b);
    f->ctx = bb;
}