/*
* net/tipc/discover.c
*
* Copyright (c) 2003-2006, 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"
#define TIPC_LINK_REQ_INIT 125 /* min delay during bearer start up */
#define TIPC_LINK_REQ_FAST 1000 /* max delay if bearer has no links */
#define TIPC_LINK_REQ_SLOW 60000 /* max delay if bearer has links */
#define TIPC_LINK_REQ_INACTIVE 0xffffffff /* indicates no timer in use */
/**
* struct tipc_link_req - information about an ongoing link setup request
* @bearer: bearer issuing requests
* @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)
* @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 {
struct tipc_bearer *bearer;
struct tipc_media_addr dest;
u32 domain;
int num_nodes;
struct sk_buff *buf;
struct timer_list timer;
unsigned int timer_intv;
};
/**
* tipc_disc_init_msg - initialize a link setup message
* @type: message type (request or response)
* @dest_domain: network domain of node(s) which should respond to message
* @b_ptr: ptr to bearer issuing message
*/
static struct sk_buff *tipc_disc_init_msg(u32 type,
u32 dest_domain,
struct tipc_bearer *b_ptr)
{
struct sk_buff *buf = tipc_buf_acquire(INT_H_SIZE);
struct tipc_msg *msg;
if (buf) {
msg = buf_msg(buf);
tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
msg_set_non_seq(msg, 1);
msg_set_node_sig(msg, tipc_random);
msg_set_dest_domain(msg, dest_domain);
msg_set_bc_netid(msg, tipc_net_id);
b_ptr->media->addr2msg(&b_ptr->addr, msg_media_addr(msg));
}
return buf;
}
/**
* 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_recv_msg - handle incoming link setup message (request or response)
* @buf: buffer containing message
* @b_ptr: bearer that message arrived on
*/
void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
{
struct tipc_node *n_ptr;
struct tipc_link *link;
struct tipc_media_addr media_addr;
struct sk_buff *rbuf;
struct tipc_msg *msg = buf_msg(buf);
u32 dest = msg_dest_domain(msg);
u32 orig = msg_prevnode(msg);
u32 net_id = msg_bc_netid(msg);
u32 type = msg_type(msg);
u32 signature = msg_node_sig(msg);
int addr_mismatch;
int link_fully_up;
media_addr.broadcast = 1;
b_ptr->media->msg2addr(&media_addr, msg_media_addr(msg));
kfree_skb(buf);
/* Ensure message from node is valid and communication is permitted */
if (net_id != tipc_net_id)
return;
if (media_addr.broadcast)
return;
if (!tipc_addr_domain_valid(dest))
return;
if (!tipc_addr_node_valid(orig))
return;
if (orig == tipc_own_addr) {
if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
return;
}
if (!tipc_in_scope(dest, tipc_own_addr))
return;
if (!tipc_in_scope(b_ptr->link_req->domain, orig))
return;
/* Locate structure corresponding to requesting node */
n_ptr = tipc_node_find(orig);
if (!n_ptr) {
n_ptr = tipc_node_create(orig);
if (!n_ptr)
return;
}
tipc_node_lock(n_ptr);
/* Prepare to validate requesting node's signature and media address */
link = n_ptr->links[b_ptr->identity];
addr_mismatch = (link != NULL) &&
memcmp(&link->media_addr, &media_addr, sizeof(media_addr));
/*
* Ensure discovery message's signature is correct
*
* If signature is incorrect and there is no working link to the node,
* accept the new signature but invalidate all existing links to the
* node so they won't re-activate without a new discovery message.
*
* If signature is incorrect and the requested link to the node is
* working, accept the new signature. (This is an instance of delayed
* rediscovery, where a link endpoint was able to re-establish contact
* with its peer endpoint on a node that rebooted before receiving a
* discovery message from that node.)
*
* If signature is incorrect and there is a working link to the node
* that is not the requested link, reject the request (must be from
* a duplicate node).
*/
if (signature != n_ptr->signature) {
if (n_ptr->working_links == 0) {
struct tipc_link *curr_link;
int i;
for (i = 0; i < MAX_BEARERS; i++) {
curr_link = n_ptr->links[i];
if (curr_link) {
memset(&curr_link->media_addr, 0,
sizeof(media_addr));
tipc_link_reset(curr_link);
}
}
addr_mismatch = (link != NULL);
} else if (tipc_link_is_up(link) && !addr_mismatch) {
/* delayed rediscovery */
} else {
disc_dupl_alert(b_ptr, orig, &media_addr);
tipc_node_unlock(n_ptr);
return;
}
n_ptr->signature = signature;
}
/*
* Ensure requesting node's media address is correct
*
* If media address doesn't match and the link is working, reject the
* request (must be from a duplicate node).
*
* If media address doesn't match and the link is not working, accept
* the new media address and reset the link to ensure it starts up
* cleanly.
*/
if (addr_mismatch) {
if (tipc_link_is_up(link)) {
disc_dupl_alert(b_ptr, orig, &media_addr);
tipc_node_unlock(n_ptr);
return;
} else {
memcpy(&link->media_addr, &media_addr,
sizeof(media_addr));
tipc_link_reset(link);
}
}
/* Create a link endpoint for this bearer, if necessary */
if (!link) {
link = tipc_link_create(n_ptr, b_ptr, &media_addr);
if (!link) {
tipc_node_unlock(n_ptr);
return;
}
}
/* Accept discovery message & send response, if necessary */
link_fully_up = link_working_working(link);
if ((type == DSC_REQ_MSG) && !link_fully_up && !b_ptr->blocked) {
rbuf = tipc_disc_init_msg(DSC_RESP_MSG, orig, b_ptr);
if (rbuf) {
b_ptr->media->send_msg(rbuf, b_ptr, &media_addr);
kfree_skb(rbuf);
}
}
tipc_node_unlock(n_ptr);
}
/**
* 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;
k_start_timer(&req->timer, 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)
{
req->num_nodes++;
}
/**
* 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)
{
req->num_nodes--;
disc_update(req);
}
/**
* disc_send_msg - send link setup request message
* @req: ptr to link request structure
*/
static void disc_send_msg(struct tipc_link_req *req)
{
if (!req->bearer->blocked)
tipc_bearer_send(req->bearer, req->buf, &req->dest);
}
/**
* disc_timeout - send a periodic link setup request
* @req: ptr to link request structure
*
* Called whenever a link setup request timer associated with a bearer expires.
*/
static void disc_timeout(struct tipc_link_req *req)
{
int max_delay;
spin_lock_bh(&req->bearer->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
*/
disc_send_msg(req);
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;
k_start_timer(&req->timer, req->timer_intv);
exit:
spin_unlock_bh(&req->bearer->lock);
}
/**
* tipc_disc_create - create object to send periodic link setup requests
* @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 tipc_bearer *b_ptr,
struct tipc_media_addr *dest, u32 dest_domain)
{
struct tipc_link_req *req;
req = kmalloc(sizeof(*req), GFP_ATOMIC);
if (!req)
return -ENOMEM;
req->buf = tipc_disc_init_msg(DSC_REQ_MSG, dest_domain, b_ptr);
if (!req->buf) {
kfree(req);
return -ENOMSG;
}
memcpy(&req->dest, dest, sizeof(*dest));
req->bearer = b_ptr;
req->domain = dest_domain;
req->num_nodes = 0;
req->timer_intv = TIPC_LINK_REQ_INIT;
k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
k_start_timer(&req->timer, req->timer_intv);
b_ptr->link_req = req;
disc_send_msg(req);
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)
{
k_cancel_timer(&req->timer);
k_term_timer(&req->timer);
kfree_skb(req->buf);
kfree(req);
}
