alistair23-linux/net/tipc/addr.c
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

124 lines
3.7 KiB
C

/*
* net/tipc/addr.c: TIPC address utility routines
*
* Copyright (c) 2000-2006, 2018, 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.
*/
#include "addr.h"
#include "core.h"
bool tipc_in_scope(bool legacy_format, u32 domain, u32 addr)
{
if (!domain || (domain == addr))
return true;
if (!legacy_format)
return false;
if (domain == tipc_cluster_mask(addr)) /* domain <Z.C.0> */
return true;
if (domain == (addr & TIPC_ZONE_CLUSTER_MASK)) /* domain <Z.C.0> */
return true;
if (domain == (addr & TIPC_ZONE_MASK)) /* domain <Z.0.0> */
return true;
return false;
}
void tipc_set_node_id(struct net *net, u8 *id)
{
struct tipc_net *tn = tipc_net(net);
u32 *tmp = (u32 *)id;
memcpy(tn->node_id, id, NODE_ID_LEN);
tipc_nodeid2string(tn->node_id_string, id);
tn->trial_addr = tmp[0] ^ tmp[1] ^ tmp[2] ^ tmp[3];
pr_info("Own node identity %s, cluster identity %u\n",
tipc_own_id_string(net), tn->net_id);
}
void tipc_set_node_addr(struct net *net, u32 addr)
{
struct tipc_net *tn = tipc_net(net);
u8 node_id[NODE_ID_LEN] = {0,};
tn->node_addr = addr;
if (!tipc_own_id(net)) {
sprintf(node_id, "%x", addr);
tipc_set_node_id(net, node_id);
}
tn->trial_addr = addr;
pr_info("32-bit node address hash set to %x\n", addr);
}
char *tipc_nodeid2string(char *str, u8 *id)
{
int i;
u8 c;
/* Already a string ? */
for (i = 0; i < NODE_ID_LEN; i++) {
c = id[i];
if (c >= '0' && c <= '9')
continue;
if (c >= 'A' && c <= 'Z')
continue;
if (c >= 'a' && c <= 'z')
continue;
if (c == '.')
continue;
if (c == ':')
continue;
if (c == '_')
continue;
if (c == '-')
continue;
if (c == '@')
continue;
if (c != 0)
break;
}
if (i == NODE_ID_LEN) {
memcpy(str, id, NODE_ID_LEN);
str[NODE_ID_LEN] = 0;
return str;
}
/* Translate to hex string */
for (i = 0; i < NODE_ID_LEN; i++)
sprintf(&str[2 * i], "%02x", id[i]);
/* Strip off trailing zeroes */
for (i = NODE_ID_STR_LEN - 2; str[i] == '0'; i--)
str[i] = 0;
return str;
}