DistRen 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 Affero General Public License for more details.

  You should have received a copy of the GNU Affero General Public License

  along with DistRen.  If not, see <http://www.gnu.org/licenses/>.

*/

#ifndef DISTREN_PROTOCOL_H

#define DISTREN_PROTOCOL_H

#include <openssl/evp.h>

#include <stddef.h>

#include <stdint.h>

/**

 * Server types:

 *

 * It is assumed that any client has at least the functionality of a

 * normal client (i.e., accepts all of the REQUIRED requests). These

 * bitmask values add to the types of requests one may make to a

 * server. After first connecting to a server or receiving a

 * connection, a client shall send a DISTREN_REQUEST_VERSION packet

 * describing its version.

 */

#define DISTREN_SERVERTYPE_SUBMIT (0x1)

#define DISTREN_SERVERTYPE_DISTRIBUTE (0x2)

#define DISTREN_SERVERTYPE_RENDER (0x4)

#define DISTREN_SERVERTYPE_CLIENT (0x8)

/**

 * This file defines the constants and structs that distren clients

 * and server use to converse.

 */

/**

 * List of request types and metadata.

 */

enum distren_request_type

  {

    /**

     * identifies the version of software being used by the sender and

     * tells if it is a client or server. Sends PACKAGE_STRING as well

     * as informing the other server what type of server this is.

     *

     *

     * REQUIRED: ALL

    */

    DISTREN_REQUEST_VERSION = 1,

    /**

     * Test if the end has a live server.

     *

     * Only authenticated clients may use this request. Thus, if a

     * client wants to confirm that a DISTREN_REQUEST_PASS request was

     * successful, that client may send a DISTREN_REQUEST_PING

     * immediately after the DISTREN_REQUEST_PASS and then wait for

     * the PONG.

     *

     * DATA: up to 32 bytes of a PING cookie

     *

     * REQUIRED: ALL

     */

    DISTREN_REQUEST_PING = 2,

    /**

     * Response to DISTREN_REQUEST_PING.

     *

     * Unauthenticated clients may be penalized for responding to PING

     * requests. This is because a newly connecting client should

     * queue a DISTREN_REQUEST_VERSION and DISTREN_REQUEST_PASS

     * back-to-back before checking for and processing data from the

     * remote server.

     *

     * DATA: up to 32 bytes copied from a received PING cookie

     *

     * REQUIRED: ALL

     */

    DISTREN_REQUEST_PONG = 3,

    /**

     * The data is the a reason describing why the one end is

     * disconnecting. The other end should respectfully close()

     * the socket or the sender will timeout shortly.

     *

     * DATA: A string describing the reason for the connection's

     * termination.

     *

     * REQUIRED: ALL

     */

    DISTREN_REQUEST_DISCONNECT = 4,

    /**

     * Allow a client to identify itself using simple password

     * authentication.