/*
 * net/tipc/node.c: TIPC node management routines
 *
 * Copyright (c) 2000-2006, 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 "config.h"
#include "node.h"
#include "name_distr.h"

#define NODE_HTABLE_SIZE 512

static void node_lost_contact(struct tipc_node *n_ptr);
static void node_established_contact(struct tipc_node *n_ptr);

static DEFINE_SPINLOCK(node_create_lock);

static struct hlist_head node_htable[NODE_HTABLE_SIZE];
LIST_HEAD(tipc_node_list);
static u32 tipc_num_nodes;

static atomic_t tipc_num_links = ATOMIC_INIT(0);

/*
 * A trivial power-of-two bitmask technique is used for speed, since this
 * operation is done for every incoming TIPC packet. The number of hash table
 * entries has been chosen so that no hash chain exceeds 8 nodes and will
 * usually be much smaller (typically only a single node).
 */
static unsigned int tipc_hashfn(u32 addr)
{
	return addr & (NODE_HTABLE_SIZE - 1);
}

/*
 * tipc_node_find - locate specified node object, if it exists
 */
struct tipc_node *tipc_node_find(u32 addr)
{
	struct tipc_node *node;
	struct hlist_node *pos;

	if (unlikely(!in_own_cluster_exact(addr)))
		return NULL;

	hlist_for_each_entry(node, pos, &node_htable[tipc_hashfn(addr)], hash) {
		if (node->addr == addr)
			return node;
	}
	return NULL;
}

/**
 * tipc_node_create - create neighboring node
 *
 * Currently, this routine is called by neighbor discovery code, which holds
 * net_lock for reading only.  We must take node_create_lock to ensure a node
 * isn't created twice if two different bearers discover the node at the same
 * time.  (It would be preferable to switch to holding net_lock in write mode,
 * but this is a non-trivial change.)
 */
struct tipc_node *tipc_node_create(u32 addr)
{
	struct tipc_node *n_ptr, *temp_node;

	spin_lock_bh(&node_create_lock);

	n_ptr = tipc_node_find(addr);
	if (n_ptr) {
		spin_unlock_bh(&node_create_lock);
		return n_ptr;
	}

	n_ptr = kzalloc(sizeof(*n_ptr), GFP_ATOMIC);
	if (!n_ptr) {
		spin_unlock_bh(&node_create_lock);
		warn("Node creation failed, no memory\n");
		return NULL;
	}

	n_ptr->addr = addr;
	spin_lock_init(&n_ptr->lock);
	INIT_HLIST_NODE(&n_ptr->hash);
	INIT_LIST_HEAD(&n_ptr->list);
	INIT_LIST_HEAD(&n_ptr->nsub);

	hlist_add_head(&n_ptr->hash, &node_htable[tipc_hashfn(addr)]);

	list_for_each_entry(temp_node, &tipc_node_list, list) {
		if (n_ptr->addr < temp_node->addr)
			break;
	}
	list_add_tail(&n_ptr->list, &temp_node->list);
	n_ptr->block_setup = WAIT_PEER_DOWN;
	n_ptr->signature = INVALID_NODE_SIG;

	tipc_num_nodes++;

	spin_unlock_bh(&node_create_lock);
	return n_ptr;
}

void tipc_node_delete(struct tipc_node *n_ptr)
{
	list_del(&n_ptr->list);
	hlist_del(&n_ptr->hash);
	kfree(n_ptr);

	tipc_num_nodes--;
}

/**
 * tipc_node_link_up - handle addition of link
 *
 * Link becomes active (alone or shared) or standby, depending on its priority.
 */
void tipc_node_link_up(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
{
	struct tipc_link **active = &n_ptr->active_links[0];

	n_ptr->working_links++;

	info("Established link <%s> on network plane %c\n",
	     l_ptr->name, l_ptr->b_ptr->net_plane);

	if (!active[0]) {
		active[0] = active[1] = l_ptr;
		node_established_contact(n_ptr);
		return;
	}
	if (l_ptr->priority < active[0]->priority) {
		info("New link <%s> becomes standby\n", l_ptr->name);
		return;
	}
	tipc_link_send_duplicate(active[0], l_ptr);
	if (l_ptr->priority == active[0]->priority) {
		active[0] = l_ptr;
		return;
	}
	info("Old link <%s> becomes standby\n", active[0]->name);
	if (active[1] != active[0])
		info("Old link <%s> becomes standby\n", active[1]->name);
	active[0] = active[1] = l_ptr;
}

/**
 * node_select_active_links - select active link
 */
static void node_select_active_links(struct tipc_node *n_ptr)
{
	struct tipc_link **active = &n_ptr->active_links[0];
	u32 i;
	u32 highest_prio = 0;

	active[0] = active[1] = NULL;

	for (i = 0; i < MAX_BEARERS; i++) {
		struct tipc_link *l_ptr = n_ptr->links[i];

		if (!l_ptr || !tipc_link_is_up(l_ptr) ||
		    (l_ptr->priority < highest_prio))
			continue;

		if (l_ptr->priority > highest_prio) {
			highest_prio = l_ptr->priority;
			active[0] = active[1] = l_ptr;
		} else {
			active[1] = l_ptr;
		}
	}
}

/**
 * tipc_node_link_down - handle loss of link
 */
void tipc_node_link_down(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
{
	struct tipc_link **active;

	n_ptr->working_links--;

	if (!tipc_link_is_active(l_ptr)) {
		info("Lost standby link <%s> on network plane %c\n",
		     l_ptr->name, l_ptr->b_ptr->net_plane);
		return;
	}
	info("Lost link <%s> on network plane %c\n",
		l_ptr->name, l_ptr->b_ptr->net_plane);

	active = &n_ptr->active_links[0];
	if (active[0] == l_ptr)
		active[0] = active[1];
	if (active[1] == l_ptr)
		active[1] = active[0];
	if (active[0] == l_ptr)
		node_select_active_links(n_ptr);
	if (tipc_node_is_up(n_ptr))
		tipc_link_changeover(l_ptr);
	else
		node_lost_contact(n_ptr);
}

int tipc_node_active_links(struct tipc_node *n_ptr)
{
	return n_ptr->active_links[0] != NULL;
}

int tipc_node_redundant_links(struct tipc_node *n_ptr)
{
	return n_ptr->working_links > 1;
}

int tipc_node_is_up(struct tipc_node *n_ptr)
{
	return tipc_node_active_links(n_ptr);
}

void tipc_node_attach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
{
	n_ptr->links[l_ptr->b_ptr->identity] = l_ptr;
	atomic_inc(&tipc_num_links);
	n_ptr->link_cnt++;
}

void tipc_node_detach_link(struct tipc_node *n_ptr, struct tipc_link *l_ptr)
{
	n_ptr->links[l_ptr->b_ptr->identity] = NULL;
	atomic_dec(&tipc_num_links);
	n_ptr->link_cnt--;
}

static void node_established_contact(struct tipc_node *n_ptr)
{
	tipc_k_signal((Handler)tipc_named_node_up, n_ptr->addr);

	if (n_ptr->bclink.supportable) {
		n_ptr->bclink.acked = tipc_bclink_get_last_sent();
		tipc_bclink_add_node(n_ptr->addr);
		n_ptr->bclink.supported = 1;
	}
}

static void node_name_purge_complete(unsigned long node_addr)
{
	struct tipc_node *n_ptr;

	read_lock_bh(&tipc_net_lock);
	n_ptr = tipc_node_find(node_addr);
	if (n_ptr) {
		tipc_node_lock(n_ptr);
		n_ptr->block_setup &= ~WAIT_NAMES_GONE;
		tipc_node_unlock(n_ptr);
	}
	read_unlock_bh(&tipc_net_lock);
}

static void node_lost_contact(struct tipc_node *n_ptr)
{
	char addr_string[16];
	u32 i;

	info("Lost contact with %s\n",
	     tipc_addr_string_fill(addr_string, n_ptr->addr));

	/* Flush broadcast link info associated with lost node */
	if (n_ptr->bclink.supported) {
		while (n_ptr->bclink.deferred_head) {
			struct sk_buff *buf = n_ptr->bclink.deferred_head;
			n_ptr->bclink.deferred_head = buf->next;
			kfree_skb(buf);
		}
		n_ptr->bclink.deferred_size = 0;

		if (n_ptr->bclink.defragm) {
			kfree_skb(n_ptr->bclink.defragm);
			n_ptr->bclink.defragm = NULL;
		}

		tipc_bclink_remove_node(n_ptr->addr);
		tipc_bclink_acknowledge(n_ptr, INVALID_LINK_SEQ);

		n_ptr->bclink.supported = 0;
	}

	/* Abort link changeover */
	for (i = 0; i < MAX_BEARERS; i++) {
		struct tipc_link *l_ptr = n_ptr->links[i];
		if (!l_ptr)
			continue;
		l_ptr->reset_checkpoint = l_ptr->next_in_no;
		l_ptr->exp_msg_count = 0;
		tipc_link_reset_fragments(l_ptr);
	}

	/* Notify subscribers */
	tipc_nodesub_notify(n_ptr);

	/* Prevent re-contact with node until cleanup is done */
	n_ptr->block_setup = WAIT_PEER_DOWN | WAIT_NAMES_GONE;
	tipc_k_signal((Handler)node_name_purge_complete, n_ptr->addr);
}

struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
{
	u32 domain;
	struct sk_buff *buf;
	struct tipc_node *n_ptr;
	struct tipc_node_info node_info;
	u32 payload_size;

	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);

	domain = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
	if (!tipc_addr_domain_valid(domain))
		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
						   " (network address)");

	read_lock_bh(&tipc_net_lock);
	if (!tipc_num_nodes) {
		read_unlock_bh(&tipc_net_lock);
		return tipc_cfg_reply_none();
	}

	/* For now, get space for all other nodes */
	payload_size = TLV_SPACE(sizeof(node_info)) * tipc_num_nodes;
	if (payload_size > 32768u) {
		read_unlock_bh(&tipc_net_lock);
		return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
						   " (too many nodes)");
	}
	buf = tipc_cfg_reply_alloc(payload_size);
	if (!buf) {
		read_unlock_bh(&tipc_net_lock);
		return NULL;
	}

	/* Add TLVs for all nodes in scope */
	list_for_each_entry(n_ptr, &tipc_node_list, list) {
		if (!tipc_in_scope(domain, n_ptr->addr))
			continue;
		node_info.addr = htonl(n_ptr->addr);
		node_info.up = htonl(tipc_node_is_up(n_ptr));
		tipc_cfg_append_tlv(buf, TIPC_TLV_NODE_INFO,
				    &node_info, sizeof(node_info));
	}

	read_unlock_bh(&tipc_net_lock);
	return buf;
}

struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
{
	u32 domain;
	struct sk_buff *buf;
	struct tipc_node *n_ptr;
	struct tipc_link_info link_info;
	u32 payload_size;

	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);

	domain = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
	if (!tipc_addr_domain_valid(domain))
		return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
						   " (network address)");

	if (!tipc_own_addr)
		return tipc_cfg_reply_none();

	read_lock_bh(&tipc_net_lock);

	/* Get space for all unicast links + broadcast link */
	payload_size = TLV_SPACE(sizeof(link_info)) *
		(atomic_read(&tipc_num_links) + 1);
	if (payload_size > 32768u) {
		read_unlock_bh(&tipc_net_lock);
		return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
						   " (too many links)");
	}
	buf = tipc_cfg_reply_alloc(payload_size);
	if (!buf) {
		read_unlock_bh(&tipc_net_lock);
		return NULL;
	}

	/* Add TLV for broadcast link */
	link_info.dest = htonl(tipc_cluster_mask(tipc_own_addr));
	link_info.up = htonl(1);
	strlcpy(link_info.str, tipc_bclink_name, TIPC_MAX_LINK_NAME);
	tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO, &link_info, sizeof(link_info));

	/* Add TLVs for any other links in scope */
	list_for_each_entry(n_ptr, &tipc_node_list, list) {
		u32 i;

		if (!tipc_in_scope(domain, n_ptr->addr))
			continue;
		tipc_node_lock(n_ptr);
		for (i = 0; i < MAX_BEARERS; i++) {
			if (!n_ptr->links[i])
				continue;
			link_info.dest = htonl(n_ptr->addr);
			link_info.up = htonl(tipc_link_is_up(n_ptr->links[i]));
			strcpy(link_info.str, n_ptr->links[i]->name);
			tipc_cfg_append_tlv(buf, TIPC_TLV_LINK_INFO,
					    &link_info, sizeof(link_info));
		}
		tipc_node_unlock(n_ptr);
	}

	read_unlock_bh(&tipc_net_lock);
	return buf;
}