/*
* net/tipc/discover.c
*
* Copyright (c) 2003-2006, 2014-2015, Ericsson AB
* Copyright (c) 2005-2006, 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 "core.h"
#include "link.h"
#include "discover.h"
/* min delay during bearer start up */
#define TIPC_LINK_REQ_INIT msecs_to_jiffies(125)
/* max delay if bearer has no links */
#define TIPC_LINK_REQ_FAST msecs_to_jiffies(1000)
/* max delay if bearer has links */
#define TIPC_LINK_REQ_SLOW msecs_to_jiffies(60000)
/* indicates no timer in use */
#define TIPC_LINK_REQ_INACTIVE 0xffffffff
/**
* struct tipc_link_req - information about an ongoing link setup request
* @bearer_id: identity of bearer issuing requests
* @net: network namespace instance
* @dest: destination address for request messages
* @domain: network domain to which links can be established
* @num_nodes: number of nodes currently discovered (i.e. with an active link)
* @lock: spinlock for controlling access to requests
* @buf: request message to be (repeatedly) sent
* @timer: timer governing period between requests
* @timer_intv: current interval between requests (in ms)
*/
struct tipc_link_req {
u32 bearer_id;
struct tipc_media_addr dest;
struct net *net;
u32 domain;
int num_nodes;
spinlock_t lock;
struct sk_buff *buf;
struct timer_list timer;
unsigned long timer_intv;
};
/**
* tipc_disc_init_msg - initialize a link setup message
* @net: the applicable net namespace
* @type: message type (request or response)
* @b_ptr: ptr to bearer issuing message
*/
static void tipc_disc_init_msg(struct net *net, struct sk_buff *buf, u32 type,
struct tipc_bearer *b_ptr)
{
struct tipc_net *tn = net_generic(net, tipc_net_id);
struct tipc_msg *msg;
u32 dest_domain = b_ptr->domain;
msg = buf_msg(buf);
tipc_msg_init(tn->own_addr, msg, LINK_CONFIG, type,
MAX_H_SIZE, dest_domain);
msg_set_non_seq(msg, 1);
msg_set_node_sig(msg, tn->random);
msg_set_node_capabilities(msg, 0);
msg_set_dest_domain(msg, dest_domain);
msg_set_bc_netid(msg, tn->net_id);
b_ptr->media->addr2msg(msg_media_addr(msg), &b_ptr->addr);
}
/**
* disc_dupl_alert - issue node address duplication alert
* @b_ptr: pointer to bearer detecting duplication
* @node_addr: duplicated node address
* @media_addr: media address advertised by duplicated node
*/
static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
struct tipc_media_addr *media_addr)
{
char node_addr_str[16];
char media_addr_str[64];
tipc_addr_string_fill(node_addr_str, node_addr);
tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
media_addr);
pr_warn("Duplicate %s using %s seen on <%s>\n", node_addr_str,
media_addr_str, b_ptr->name);
}
/**
* tipc_disc_rcv - handle incoming discovery message (request or response)
* @net: the applicable net namespace
* @buf: buffer containing message
* @bearer: bearer that message arrived on
*/
void tipc_disc_rcv(struct net *net, struct sk_buff *buf,
struct tipc_bearer *bearer)
{
struct tipc_net *tn = net_generic(net, tipc_net_id);
struct tipc_node *node;
struct tipc_link *link;
struct tipc_media_addr maddr;
struct sk_buff *rbuf;
struct tipc_msg *msg = buf_msg(buf);
u32 ddom = msg_dest_domain(msg);
u32 onode = msg_prevnode(msg);
u32 net_id = msg_bc_netid(msg);
u32 mtyp = msg_type(msg);
u32 signature = msg_node_sig(msg);
u16 caps = msg_node_capabilities(msg);
bool addr_match = false;
bool sign_match = false;
bool link_up = false;
bool accept_addr = false;
bool accept_sign = false;
bool respond = false;
bearer->media->msg2addr(bearer, &maddr, msg_media_addr(msg));
kfree_skb(buf);
/* Ensure message from node is valid and communication is permitted */
if (net_id != tn->net_id)
return;
if (maddr.broadcast)
return;
if (!tipc_addr_domain_valid(ddom))
return;
if (!tipc_addr_node_valid(onode))
return;
if (in_own_node(net, onode)) {
if (memcmp(&maddr, &bearer->addr, sizeof(maddr)))
disc_dupl_alert(bearer, tn->own_addr, &maddr);
return;
}
if (!tipc_in_scope(ddom, tn->own_addr))
return;
if (!tipc_in_scope(bearer->domain, onode))
return;
node = tipc_node_create(net, onode);
if (!node)
return;
tipc_node_lock(node);
node->capabilities = caps;
link = node->links[bearer->identity];
/* Prepare to validate requesting node's signature and media address */
sign_match = (signature == node->signature);
addr_match = link && !memcmp(&link->media_addr, &maddr, sizeof(maddr));
link_up = link && tipc_link_is_up(link);
/* These three flags give us eight permutations: */
if (sign_match && addr_match && link_up) {
/* All is fine. Do nothing. */
} else if (sign_match && addr_match && !link_up) {
/* Respond. The link will come up in due time */
respond = true;
} else if (sign_match && !addr_match && link_up) {
/* Peer has changed i/f address without rebooting.
* If so, the link will reset soon, and the next
* discovery will be accepted. So we can ignore it.
* It may also be an cloned or malicious peer having
* chosen the same node address and signature as an
* existing one.
* Ignore requests until the link goes down, if ever.
*/
disc_dupl_alert(bearer, onode, &maddr);
} else if (sign_match && !addr_match && !link_up) {
/* Peer link has changed i/f address without rebooting.
* It may also be a cloned or malicious peer; we can't
* distinguish between the two.
* The signature is correct, so we must accept.
*/
accept_addr = true;
respond = true;
} else if (!sign_match && addr_match && link_up) {
/* Peer node rebooted. Two possibilities:
* - Delayed re-discovery; this link endpoint has already
* reset and re-established contact with the peer, before
* receiving a discovery message from that node.
* (The peer happened to receive one from this node first).
* - The peer came back so fast that our side has not
* discovered it yet. Probing from this side will soon
* reset the link, since there can be no working link
* endpoint at the peer end, and the link will re-establish.
* Accept the signature, since it comes from a known peer.
*/
accept_sign = true;
} else if (!sign_match && addr_match && !link_up) {
/* The peer node has rebooted.
* Accept signature, since it is a known peer.
*/
accept_sign = true;
respond = true;
} else if (!sign_match && !addr_match && link_up) {
/* Peer rebooted with new address, or a new/duplicate peer.
* Ignore until the link goes down, if ever.
*/
disc_dupl_alert(bearer, onode, &maddr);
} else if (!sign_match && !addr_match && !link_up) {
/* Peer rebooted with new address, or it is a new peer.
* Accept signature and address.
*/
accept_sign = true;
accept_addr = true;
respond = true;
}
if (accept_sign)
node->signature = signature;
if (accept_addr) {
if (!link)
link = tipc_link_create(node, bearer, &maddr);
if (link) {
memcpy(&link->media_addr, &maddr, sizeof(maddr));
tipc_link_reset(link);
} else {
respond = false;
}
}
/* Send response, if necessary */
if (respond && (mtyp == DSC_REQ_MSG)) {
rbuf = tipc_buf_acquire(MAX_H_SIZE);
if (rbuf) {
tipc_disc_init_msg(net, rbuf, DSC_RESP_MSG, bearer);
tipc_bearer_send(net, bearer->identity, rbuf, &maddr);
kfree_skb(rbuf);
}
}
tipc_node_unlock(node);
tipc_node_put(node);
}
/**
* disc_update - update frequency of periodic link setup requests
* @req: ptr to link request structure
*
* Reinitiates discovery process if discovery object has no associated nodes
* and is either not currently searching or is searching at a slow rate
*/
static void disc_update(struct tipc_link_req *req)
{
if (!req->num_nodes) {
if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
(req->timer_intv > TIPC_LINK_REQ_FAST)) {
req->timer_intv = TIPC_LINK_REQ_INIT;
mod_timer(&req->timer, jiffies + req->timer_intv);
}
}
}
/**
* tipc_disc_add_dest - increment set of discovered nodes
* @req: ptr to link request structure
*/
void tipc_disc_add_dest(struct tipc_link_req *req)
{
spin_lock_bh(&req->lock);
req->num_nodes++;
spin_unlock_bh(&req->lock);
}
/**
* tipc_disc_remove_dest - decrement set of discovered nodes
* @req: ptr to link request structure
*/
void tipc_disc_remove_dest(struct tipc_link_req *req)
{
spin_lock_bh(&req->lock);
req->num_nodes--;
disc_update(req);
spin_unlock_bh(&req->lock);
}
/**
* disc_timeout - send a periodic link setup request
* @data: ptr to link request structure
*
* Called whenever a link setup request timer associated with a bearer expires.
*/
static void disc_timeout(unsigned long data)
{
struct tipc_link_req *req = (struct tipc_link_req *)data;
int max_delay;
spin_lock_bh(&req->lock);
/* Stop searching if only desired node has been found */
if (tipc_node(req->domain) && req->num_nodes) {
req->timer_intv = TIPC_LINK_REQ_INACTIVE;
goto exit;
}
/*
* Send discovery message, then update discovery timer
*
* Keep doubling time between requests until limit is reached;
* hold at fast polling rate if don't have any associated nodes,
* otherwise hold at slow polling rate
*/
tipc_bearer_send(req->net, req->bearer_id, req->buf, &req->dest);
req->timer_intv *= 2;
if (req->num_nodes)
max_delay = TIPC_LINK_REQ_SLOW;
else
max_delay = TIPC_LINK_REQ_FAST;
if (req->timer_intv > max_delay)
req->timer_intv = max_delay;
mod_timer(&req->timer, jiffies + req->timer_intv);
exit:
spin_unlock_bh(&req->lock);
}
/**
* tipc_disc_create - create object to send periodic link setup requests
* @net: the applicable net namespace
* @b_ptr: ptr to bearer issuing requests
* @dest: destination address for request messages
* @dest_domain: network domain to which links can be established
*
* Returns 0 if successful, otherwise -errno.
*/
int tipc_disc_create(struct net *net, struct tipc_bearer *b_ptr,
struct tipc_media_addr *dest)
{
struct tipc_link_req *req;
req = kmalloc(sizeof(*req), GFP_ATOMIC);
if (!req)
return -ENOMEM;
req->buf = tipc_buf_acquire(MAX_H_SIZE);
if (!req->buf) {
kfree(req);
return -ENOMEM;
}
tipc_disc_init_msg(net, req->buf, DSC_REQ_MSG, b_ptr);
memcpy(&req->dest, dest, sizeof(*dest));
req->net = net;
req->bearer_id = b_ptr->identity;
req->domain = b_ptr->domain;
req->num_nodes = 0;
req->timer_intv = TIPC_LINK_REQ_INIT;
spin_lock_init(&req->lock);
setup_timer(&req->timer, disc_timeout, (unsigned long)req);
mod_timer(&req->timer, jiffies + req->timer_intv);
b_ptr->link_req = req;
tipc_bearer_send(net, req->bearer_id, req->buf, &req->dest);
return 0;
}
/**
* tipc_disc_delete - destroy object sending periodic link setup requests
* @req: ptr to link request structure
*/
void tipc_disc_delete(struct tipc_link_req *req)
{
del_timer_sync(&req->timer);
kfree_skb(req->buf);
kfree(req);
}
/**
* tipc_disc_reset - reset object to send periodic link setup requests
* @net: the applicable net namespace
* @b_ptr: ptr to bearer issuing requests
* @dest_domain: network domain to which links can be established
*/
void tipc_disc_reset(struct net *net, struct tipc_bearer *b_ptr)
{
struct tipc_link_req *req = b_ptr->link_req;
spin_lock_bh(&req->lock);
tipc_disc_init_msg(net, req->buf, DSC_REQ_MSG, b_ptr);
req->net = net;
req->bearer_id = b_ptr->identity;
req->domain = b_ptr->domain;
req->num_nodes = 0;
req->timer_intv = TIPC_LINK_REQ_INIT;
mod_timer(&req->timer, jiffies + req->timer_intv);
tipc_bearer_send(net, req->bearer_id, req->buf, &req->dest);
spin_unlock_bh(&req->lock);
}
