linux/net/tipc/link.h
Jon Maloy 25b0b9c4e8 tipc: handle collisions of 32-bit node address hash values
When a 32-bit node address is generated from a 128-bit identifier,
there is a risk of collisions which must be discovered and handled.

We do this as follows:
- We don't apply the generated address immediately to the node, but do
  instead initiate a 1 sec trial period to allow other cluster members
  to discover and handle such collisions.

- During the trial period the node periodically sends out a new type
  of message, DSC_TRIAL_MSG, using broadcast or emulated broadcast,
  to all the other nodes in the cluster.

- When a node is receiving such a message, it must check that the
  presented 32-bit identifier either is unused, or was used by the very
  same peer in a previous session. In both cases it accepts the request
  by not responding to it.

- If it finds that the same node has been up before using a different
  address, it responds with a DSC_TRIAL_FAIL_MSG containing that
  address.

- If it finds that the address has already been taken by some other
  node, it generates a new, unused address and returns it to the
  requester.

- During the trial period the requesting node must always be prepared
  to accept a failure message, i.e., a message where a peer suggests a
  different (or equal)  address to the one tried. In those cases it
  must apply the suggested value as trial address and restart the trial
  period.

This algorithm ensures that in the vast majority of cases a node will
have the same address before and after a reboot. If a legacy user
configures the address explicitly, there will be no trial period and
messages, so this protocol addition is completely backwards compatible.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-23 13:12:18 -04:00

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6.1 KiB
C

/*
* net/tipc/link.h: Include file for TIPC link code
*
* Copyright (c) 1995-2006, 2013-2014, Ericsson AB
* Copyright (c) 2004-2005, 2010-2011, Wind River Systems
* All rights reserved.
*
* 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 names of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* 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 COPYRIGHT OWNER OR CONTRIBUTORS 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.
*/
#ifndef _TIPC_LINK_H
#define _TIPC_LINK_H
#include <net/genetlink.h>
#include "msg.h"
#include "node.h"
/* TIPC-specific error codes
*/
#define ELINKCONG EAGAIN /* link congestion <=> resource unavailable */
/* Link FSM events:
*/
enum {
LINK_ESTABLISH_EVT = 0xec1ab1e,
LINK_PEER_RESET_EVT = 0x9eed0e,
LINK_FAILURE_EVT = 0xfa110e,
LINK_RESET_EVT = 0x10ca1d0e,
LINK_FAILOVER_BEGIN_EVT = 0xfa110bee,
LINK_FAILOVER_END_EVT = 0xfa110ede,
LINK_SYNCH_BEGIN_EVT = 0xc1ccbee,
LINK_SYNCH_END_EVT = 0xc1ccede
};
/* Events returned from link at packet reception or at timeout
*/
enum {
TIPC_LINK_UP_EVT = 1,
TIPC_LINK_DOWN_EVT = (1 << 1),
TIPC_LINK_SND_STATE = (1 << 2)
};
/* Starting value for maximum packet size negotiation on unicast links
* (unless bearer MTU is less)
*/
#define MAX_PKT_DEFAULT 1500
bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
int tolerance, char net_plane, u32 mtu, int priority,
int window, u32 session, u32 ownnode,
u32 peer, u8 *peer_id, u16 peer_caps,
struct tipc_link *bc_sndlink,
struct tipc_link *bc_rcvlink,
struct sk_buff_head *inputq,
struct sk_buff_head *namedq,
struct tipc_link **link);
bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer,
int mtu, int window, u16 peer_caps,
struct sk_buff_head *inputq,
struct sk_buff_head *namedq,
struct tipc_link *bc_sndlink,
struct tipc_link **link);
void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
int mtyp, struct sk_buff_head *xmitq);
void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq);
int tipc_link_fsm_evt(struct tipc_link *l, int evt);
bool tipc_link_is_up(struct tipc_link *l);
bool tipc_link_peer_is_down(struct tipc_link *l);
bool tipc_link_is_reset(struct tipc_link *l);
bool tipc_link_is_establishing(struct tipc_link *l);
bool tipc_link_is_synching(struct tipc_link *l);
bool tipc_link_is_failingover(struct tipc_link *l);
bool tipc_link_is_blocked(struct tipc_link *l);
void tipc_link_set_active(struct tipc_link *l, bool active);
void tipc_link_reset(struct tipc_link *l);
void tipc_link_reset_stats(struct tipc_link *l);
int tipc_link_xmit(struct tipc_link *link, struct sk_buff_head *list,
struct sk_buff_head *xmitq);
struct sk_buff_head *tipc_link_inputq(struct tipc_link *l);
u16 tipc_link_rcv_nxt(struct tipc_link *l);
u16 tipc_link_acked(struct tipc_link *l);
u32 tipc_link_id(struct tipc_link *l);
char *tipc_link_name(struct tipc_link *l);
char tipc_link_plane(struct tipc_link *l);
int tipc_link_prio(struct tipc_link *l);
int tipc_link_window(struct tipc_link *l);
unsigned long tipc_link_tolerance(struct tipc_link *l);
void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
struct sk_buff_head *xmitq);
void tipc_link_set_prio(struct tipc_link *l, u32 prio,
struct sk_buff_head *xmitq);
void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit);
void tipc_link_set_queue_limits(struct tipc_link *l, u32 window);
int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
struct tipc_link *link, int nlflags);
int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[]);
int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq);
int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
struct sk_buff_head *xmitq);
int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq);
void tipc_link_add_bc_peer(struct tipc_link *snd_l,
struct tipc_link *uc_l,
struct sk_buff_head *xmitq);
void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
struct tipc_link *rcv_l,
struct sk_buff_head *xmitq);
int tipc_link_bc_peers(struct tipc_link *l);
void tipc_link_set_mtu(struct tipc_link *l, int mtu);
int tipc_link_mtu(struct tipc_link *l);
void tipc_link_bc_ack_rcv(struct tipc_link *l, u16 acked,
struct sk_buff_head *xmitq);
void tipc_link_build_bc_sync_msg(struct tipc_link *l,
struct sk_buff_head *xmitq);
void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr);
int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
struct sk_buff_head *xmitq);
int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
struct sk_buff_head *xmitq);
#endif