tinc/src/meta.h

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/*
meta.h -- header for meta.c
Copyright (C) 2000-2014 Guus Sliepen <guus@tinc-vpn.org>,
2000-2005 Ivo Timmermans
This program 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 Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef __TINC_META_H__
#define __TINC_META_H__
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#include "connection.h"
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extern bool send_meta(struct connection_t *, const char *, int);
Introduce raw TCP SPTPS packet transport. Currently, SPTPS packets are transported over TCP metaconnections using extended REQ_KEY requests, in order for the packets to pass through tinc-1.0 nodes unaltered. Unfortunately, this method presents two significant downsides: - An already encrypted SPTPS packet is decrypted and then encrypted again every time it passes through a node, since it is transported over the SPTPS channels of the metaconnections. This double-encryption is unnecessary and wastes CPU cycles. - More importantly, the only way to transport binary data over standard metaconnection messages such as REQ_KEY is to encode it in base64, which has a 33% encoding overhead. This wastes 25% of the network bandwidth. This commit introduces a new protocol message, SPTPS_PACKET, which can be used to transport SPTPS packets over a TCP metaconnection in an efficient way. The new message is appropriately protected through a minor protocol version increment, and extended REQ_KEY messages are still used with nodes that do not support the new message, as well as for the intial handshake packets, for which efficiency is not a concern. The way SPTPS_PACKET works is very similar to how the traditional PACKET message works: after the SPTPS_PACKET message, the raw binary packet is sent directly over the metaconnection. There is one important difference, however: in the case of SPTPS_PACKET, the packet is sent directly over the TCP stream completely bypassing the SPTPS channel of the metaconnection itself for maximum efficiency. This is secure because the SPTPS packet that is being sent is already encrypted with an end-to-end key.
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extern void send_meta_raw(struct connection_t *, const char *, int);
extern bool send_meta_sptps(void *, uint8_t, const void *, size_t);
extern bool receive_meta_sptps(void *, uint8_t, const void *, uint16_t);
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extern void broadcast_meta(struct connection_t *, const char *, int);
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extern bool receive_meta(struct connection_t *);
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#endif /* __TINC_META_H__ */