/*
   * net/tipc/node.c: TIPC node management routines
   *
   * Copyright (c) 2000-2006, 2012 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;
  
  	if (unlikely(!in_own_cluster_exact(addr)))
  		return NULL;
  
  	hlist_for_each_entry(node, &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);
  		pr_warn("Node creation failed, no memory
  ");
  		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++;
  
  	pr_info("Established link <%s> on network plane %c
  ",
  		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) {
  		pr_info("New link <%s> becomes standby
  ", l_ptr->name);
  		return;
  	}
  	tipc_link_dup_send_queue(active[0], l_ptr);
  	if (l_ptr->priority == active[0]->priority) {
  		active[0] = l_ptr;
  		return;
  	}
  	pr_info("Old link <%s> becomes standby
  ", active[0]->name);
  	if (active[1] != active[0])
  		pr_info("Old link <%s> becomes standby
  ", 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)) {
  		pr_info("Lost standby link <%s> on network plane %c
  ",
  			l_ptr->name, l_ptr->b_ptr->net_plane);
  		return;
  	}
  	pr_info("Lost link <%s> on network plane %c
  ",
  		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_failover_send_queue(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_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);
  	n_ptr->bclink.oos_state = 0;
  	n_ptr->bclink.acked = tipc_bclink_get_last_sent();
  	tipc_bclink_add_node(n_ptr->addr);
  }
  
  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;
  
  	pr_info("Lost contact with %s
  ",
  		tipc_addr_string_fill(addr_string, n_ptr->addr));
  
  	/* Flush broadcast link info associated with lost node */
  	if (n_ptr->bclink.recv_permitted) {
  		kfree_skb_list(n_ptr->bclink.deferred_head);
  		n_ptr->bclink.deferred_size = 0;
  
  		if (n_ptr->bclink.reasm_head) {
  			kfree_skb(n_ptr->bclink.reasm_head);
  			n_ptr->bclink.reasm_head = NULL;
  			n_ptr->bclink.reasm_tail = NULL;
  		}
  
  		tipc_bclink_remove_node(n_ptr->addr);
  		tipc_bclink_acknowledge(n_ptr, INVALID_LINK_SEQ);
  
  		n_ptr->bclink.recv_permitted = false;
  	}
  
  	/* 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;
  }