BadVPN – Rev 1
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/**
* @file msgproto.h
* @author Ambroz Bizjak <ambrop7@gmail.com>
*
* @section LICENSE
*
* 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. Neither the name of the author nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS 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 AUTHOR 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.
*
* @section DESCRIPTION
*
* MsgProto is used by each pair of VPN peers as messages through the server, in order to
* establish a direct data connection. MsgProto operates on top of the SCProto message
* service, optionally secured with SSL; see {@link scproto.h} for details.
*
* MsgProto is built with BProto, the protocol and code generator for building
* custom message protocols. The BProto specification file is msgproto.bproto.
*
* It goes roughly like that:
*
* We name one peer the master and the other the slave. The master is the one with
* greater ID.
* When the peers get to know about each other, the master starts the binding procedure.
* It binds/listens to an address, and sends the slave the "youconnect" message. It
* contains a list of external addresses for that bind address and additional parameters.
* Each external address includes a string called a scope name. The slave, which receives
* the "youconnect" message, finds the first external address whose scope it recognizes,
* and attempts to establish connection to that address. If it finds an address, buf fails
* at connecting, it sends "youretry", which makes the master restart the binding procedure
* after some time. If it however does not recognize any external address, it sends
* "cannotconnect" back to the master.
* When the master receives the "cannotconnect", it tries the next bind address, as described
* above. When the master runs out of bind addresses, it sends "cannotbind" to the slave.
* When the slave receives the "cannotbind", it starts its own binding procedure, similarly
* to what is described above, with master and slave reversed. First difference is if the
* master fails to connect to a recognized address, it doesn't send "youretry", but rather
* simply restarts the whole procedure after some time. The other difference is when the
* slave runs out of bind addresses, it not only sends "cannotbind" to the master, but
* registers relaying to the master. And in this case, when the master receives the "cannotbind",
* it doesn't start the binding procedure all all over, but registers relaying to the slave.
*/
#ifndef BADVPN_PROTOCOL_MSGPROTO_H
#define BADVPN_PROTOCOL_MSGPROTO_H
#include <generated/bproto_msgproto.h>
#define MSGID_YOUCONNECT 1
#define MSGID_CANNOTCONNECT 2
#define MSGID_CANNOTBIND 3
#define MSGID_YOURETRY 5
#define MSGID_SEED 6
#define MSGID_CONFIRMSEED 7
#define MSG_MAX_PAYLOAD (SC_MAX_MSGLEN - msg_SIZEtype - msg_SIZEpayload(0))
#endif