linux/net/tipc/core.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

189 lines
5.0 KiB
C

/*
* net/tipc/core.h: Include file for TIPC global declarations
*
* Copyright (c) 2005-2006, 2013-2018 Ericsson AB
* Copyright (c) 2005-2007, 2010-2013, 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_CORE_H
#define _TIPC_CORE_H
#include <linux/tipc.h>
#include <linux/tipc_config.h>
#include <linux/tipc_netlink.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/interrupt.h>
#include <linux/atomic.h>
#include <linux/netdevice.h>
#include <linux/in.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/rtnetlink.h>
#include <linux/etherdevice.h>
#include <net/netns/generic.h>
#include <linux/rhashtable.h>
struct tipc_node;
struct tipc_bearer;
struct tipc_bc_base;
struct tipc_link;
struct tipc_name_table;
struct tipc_topsrv;
struct tipc_monitor;
#define TIPC_MOD_VER "2.0.0"
#define NODE_HTABLE_SIZE 512
#define MAX_BEARERS 3
#define TIPC_DEF_MON_THRESHOLD 32
#define NODE_ID_LEN 16
#define NODE_ID_STR_LEN (NODE_ID_LEN * 2 + 1)
extern unsigned int tipc_net_id __read_mostly;
extern int sysctl_tipc_rmem[3] __read_mostly;
extern int sysctl_tipc_named_timeout __read_mostly;
struct tipc_net {
u8 node_id[NODE_ID_LEN];
u32 node_addr;
u32 trial_addr;
unsigned long addr_trial_end;
char node_id_string[NODE_ID_STR_LEN];
int net_id;
int random;
bool legacy_addr_format;
/* Node table and node list */
spinlock_t node_list_lock;
struct hlist_head node_htable[NODE_HTABLE_SIZE];
struct list_head node_list;
u32 num_nodes;
u32 num_links;
/* Neighbor monitoring list */
struct tipc_monitor *monitors[MAX_BEARERS];
int mon_threshold;
/* Bearer list */
struct tipc_bearer __rcu *bearer_list[MAX_BEARERS + 1];
/* Broadcast link */
spinlock_t bclock;
struct tipc_bc_base *bcbase;
struct tipc_link *bcl;
/* Socket hash table */
struct rhashtable sk_rht;
/* Name table */
spinlock_t nametbl_lock;
struct name_table *nametbl;
/* Name dist queue */
struct list_head dist_queue;
/* Topology subscription server */
struct tipc_topsrv *topsrv;
atomic_t subscription_count;
};
static inline struct tipc_net *tipc_net(struct net *net)
{
return net_generic(net, tipc_net_id);
}
static inline int tipc_netid(struct net *net)
{
return tipc_net(net)->net_id;
}
static inline struct list_head *tipc_nodes(struct net *net)
{
return &tipc_net(net)->node_list;
}
static inline struct name_table *tipc_name_table(struct net *net)
{
return tipc_net(net)->nametbl;
}
static inline struct tipc_topsrv *tipc_topsrv(struct net *net)
{
return tipc_net(net)->topsrv;
}
static inline unsigned int tipc_hashfn(u32 addr)
{
return addr & (NODE_HTABLE_SIZE - 1);
}
static inline u16 mod(u16 x)
{
return x & 0xffffu;
}
static inline int less_eq(u16 left, u16 right)
{
return mod(right - left) < 32768u;
}
static inline int more(u16 left, u16 right)
{
return !less_eq(left, right);
}
static inline int less(u16 left, u16 right)
{
return less_eq(left, right) && (mod(right) != mod(left));
}
static inline int in_range(u16 val, u16 min, u16 max)
{
return !less(val, min) && !more(val, max);
}
#ifdef CONFIG_SYSCTL
int tipc_register_sysctl(void);
void tipc_unregister_sysctl(void);
#else
#define tipc_register_sysctl() 0
#define tipc_unregister_sysctl()
#endif
#endif