packet.c

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/*
 *   This program is is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or (at
 *   your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: bdf72473a940e88b13b624668bd3e0cb605e88a4 $
 * @file lib/bio/packet.c
 * @brief BIO PACKET handlers
 *
 * @copyright 2024 Network RADIUS SAS (legal@networkradius.com)
 */
 
#include <freeradius-devel/bio/bio_priv.h>
#include <freeradius-devel/bio/packet.h>
 
/** Inform all of the BIOs that the write is blocked.
 *
 *  This function should be set as the BIO layer "write_blocked" callback for all BIOs created as part
 *  of a #fr_bio_packet_t.  The application should also set bio->uctx=bio_packet for all BIOs.
 */
static int fr_bio_packet_write_blocked(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
 
        /*
         *      This function must be callable multiple times, as different portions of the BIOs can block at
         *      different times.
         */
        if (my->write_blocked) return 1;
        my->write_blocked = true;
 
        /*
         *      The application doesn't want to know that it's blocked, so we just return.
         */
        if (!my->cb.write_blocked) return 1;
 
        /*
         *      Tell the application that IO is blocked.
         */
        return my->cb.write_blocked(my);
}
 
static int fr_bio_packet_write_resume(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
        fr_bio_t *next;
        int rcode;
 
        if (!my->write_blocked) return 1;
        my->write_blocked = false;
 
        /*
         *      Inform each underlying BIO that it can be resumed.  Note that we might be called from a
         *      lower-layer BIO, so we have to start from the top of the chain.
         *
         *      Note that if the callback returns 0, saying "I couldn't resume", then the BIO is still marked
         *      as blocked.
         */
        for (next = my->bio;
             next != NULL;
             next = fr_bio_next(next)) {
 
                if (!((fr_bio_common_t *) next)->priv_cb.write_resume) continue;
 
                rcode = ((fr_bio_common_t *) next)->priv_cb.write_resume(next);
                if (rcode < 0) return rcode;
 
                if (rcode == 0) {
                        my->write_blocked = true;
                        return 0;
                }
        }
 
        rcode = my->cb.write_resume(my);
        if (rcode < 0) return rcode;
 
        my->write_blocked = (rcode == 0);
 
        return rcode;
}
 
static int fr_bio_packet_read_blocked(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
 
        my->read_blocked = true;
 
        return my->cb.read_blocked(my);
}
 
static int fr_bio_packet_read_resume(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
 
        my->read_blocked = false;
 
        return my->cb.read_resume(my);
}
 
/** Called when a particular BIO is connected.
 *
 *  We see if we can connect the previous BIOs.
 */
void fr_bio_packet_connected(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
 
        fr_assert(!my->connected);
 
        /*
         *      Run the internal connected callback for previous BIOs.  If one returns "not connected", then
         *      the packet BIO as a whole is not connected.
         */
        while ((bio = fr_bio_prev(bio)) != NULL) {
                if (!((fr_bio_common_t *) bio)->priv_cb.connected) continue;
 
                /*
                 *      Tell this BIO that everything it needs has been connected.
                 */
                if (((fr_bio_common_t *) bio)->priv_cb.connected(bio) == 0) return;
        }
 
        /*
         *      The top-level BIO is connected.  This means that the entire chain is now connected, and is
         *      usable by the application.
         */
        my->connected = true;
 
        /*
         *      Stop any connection timeout.
         */
        if (my->ev) talloc_const_free(&my->ev);
 
        /*
         *      Tell the application that the packet BIO is now usable.
         */
        my->cb.connected(my);
}
 
static void fr_bio_packet_shutdown(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
 
        if (my->cb.shutdown) my->cb.shutdown(my);
        my->cb.shutdown = NULL;
}
 
static void fr_bio_packet_eof(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
 
        if (my->cb.eof) my->cb.eof(my);
        my->cb.eof = NULL;
}
 
static void fr_bio_packet_failed(fr_bio_t *bio)
{
        fr_bio_packet_t *my = bio->uctx;
 
        if (my->cb.failed) my->cb.failed(my);
        my->cb.failed = NULL;
}
 
 
void fr_bio_packet_init(fr_bio_packet_t *my)
{
        fr_bio_t *bio = my->bio;
 
        fr_bio_cb_funcs_t bio_cb = {
                .connected = fr_bio_packet_connected,
                .shutdown = fr_bio_packet_shutdown,
                .eof = fr_bio_packet_eof,
                .failed = fr_bio_packet_failed,
 
                .write_blocked = fr_bio_packet_write_blocked,
                .write_resume = fr_bio_packet_write_resume,
                .read_blocked = fr_bio_packet_read_blocked,
                .read_resume = fr_bio_packet_read_resume,
        };
 
        /*
         *      Every participating BIO has us set as the bio->uctx, and we handle all BIO callbacks.
         *
         *      The application sets its own pointer my->uctx and sets itself via our callbacks.
         */
        while (bio) {
                bio->uctx = my;
 
                fr_bio_cb_set(bio, &bio_cb);
                bio = fr_bio_next(bio);
        }
}