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tinc/src/protocol.h
Etienne Dechamps 7e6b2dd1ea 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.
2015-05-10 21:08:57 +01:00

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/*
protocol.h -- header for protocol.c
Copyright (C) 1999-2005 Ivo Timmermans,
2000-2013 Guus Sliepen <guus@tinc-vpn.org>
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_PROTOCOL_H__
#define __TINC_PROTOCOL_H__
#include "ecdsa.h"
/* Protocol version. Different major versions are incompatible. */
#define PROT_MAJOR 17
#define PROT_MINOR 7 /* Should not exceed 255! */
/* Silly Windows */
#ifdef ERROR
#undef ERROR
#endif
/* Request numbers */
typedef enum request_t {
ALL = -1, /* Guardian for allow_request */
ID = 0, METAKEY, CHALLENGE, CHAL_REPLY, ACK,
STATUS, ERROR, TERMREQ,
PING, PONG,
ADD_SUBNET, DEL_SUBNET,
ADD_EDGE, DEL_EDGE,
KEY_CHANGED, REQ_KEY, ANS_KEY,
PACKET,
/* Tinc 1.1 requests */
CONTROL,
REQ_PUBKEY, ANS_PUBKEY,
SPTPS_PACKET,
UDP_INFO, MTU_INFO,
LAST /* Guardian for the highest request number */
} request_t;
typedef struct past_request_t {
const char *request;
time_t firstseen;
} past_request_t;
extern bool tunnelserver;
extern bool strictsubnets;
extern bool experimental;
extern ecdsa_t *invitation_key;
/* Maximum size of strings in a request.
* scanf terminates %2048s with a NUL character,
* but the NUL character can be written after the 2048th non-NUL character.
*/
#define MAX_STRING_SIZE 2049
#define MAX_STRING "%2048s"
#include "edge.h"
#include "net.h"
#include "node.h"
#include "subnet.h"
/* Basic functions */
extern bool send_request(struct connection_t *, const char *, ...) __attribute__ ((__format__(printf, 2, 3)));
extern void forward_request(struct connection_t *, const char *);
extern bool receive_request(struct connection_t *, const char *);
extern void init_requests(void);
extern void exit_requests(void);
extern bool seen_request(const char *);
/* Requests */
extern bool send_id(struct connection_t *);
extern bool send_metakey(struct connection_t *);
extern bool send_metakey_ec(struct connection_t *);
extern bool send_challenge(struct connection_t *);
extern bool send_chal_reply(struct connection_t *);
extern bool send_ack(struct connection_t *);
extern bool send_status(struct connection_t *, int, const char *);
extern bool send_error(struct connection_t *, int, const char *);
extern bool send_termreq(struct connection_t *);
extern bool send_ping(struct connection_t *);
extern bool send_pong(struct connection_t *);
extern bool send_add_subnet(struct connection_t *, const struct subnet_t *);
extern bool send_del_subnet(struct connection_t *, const struct subnet_t *);
extern bool send_add_edge(struct connection_t *, const struct edge_t *);
extern bool send_del_edge(struct connection_t *, const struct edge_t *);
extern void send_key_changed(void);
extern bool send_req_key(struct node_t *);
extern bool send_ans_key(struct node_t *);
extern bool send_tcppacket(struct connection_t *, const struct vpn_packet_t *);
extern bool send_sptps_tcppacket(struct connection_t *, const char*, int);
extern bool send_udp_info(struct node_t *, struct node_t *);
extern bool send_mtu_info(struct node_t *, struct node_t *, int);
/* Request handlers */
extern bool id_h(struct connection_t *, const char *);
extern bool metakey_h(struct connection_t *, const char *);
extern bool challenge_h(struct connection_t *, const char *);
extern bool chal_reply_h(struct connection_t *, const char *);
extern bool ack_h(struct connection_t *, const char *);
extern bool status_h(struct connection_t *, const char *);
extern bool error_h(struct connection_t *, const char *);
extern bool termreq_h(struct connection_t *, const char *);
extern bool ping_h(struct connection_t *, const char *);
extern bool pong_h(struct connection_t *, const char *);
extern bool add_subnet_h(struct connection_t *, const char *);
extern bool del_subnet_h(struct connection_t *, const char *);
extern bool add_edge_h(struct connection_t *, const char *);
extern bool del_edge_h(struct connection_t *, const char *);
extern bool key_changed_h(struct connection_t *, const char *);
extern bool req_key_h(struct connection_t *, const char *);
extern bool ans_key_h(struct connection_t *, const char *);
extern bool tcppacket_h(struct connection_t *, const char *);
extern bool sptps_tcppacket_h(struct connection_t *, const char *);
extern bool control_h(struct connection_t *, const char *);
extern bool udp_info_h(struct connection_t *, const char *);
extern bool mtu_info_h(struct connection_t *, const char *);
#endif /* __TINC_PROTOCOL_H__ */
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