/*
 * net/tipc/group.c: TIPC group messaging code
 *
 * Copyright (c) 2017, Ericsson AB
 * 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 "addr.h"
#include "group.h"
#include "bcast.h"
#include "server.h"
#include "msg.h"
#include "socket.h"
#include "node.h"
#include "name_table.h"
#include "subscr.h"

#define ADV_UNIT (((MAX_MSG_SIZE + MAX_H_SIZE) / FLOWCTL_BLK_SZ) + 1)
#define ADV_IDLE ADV_UNIT

enum mbr_state {
	MBR_QUARANTINED,
	MBR_DISCOVERED,
	MBR_JOINING,
	MBR_PUBLISHED,
	MBR_JOINED,
	MBR_LEAVING
};

struct tipc_member {
	struct rb_node tree_node;
	struct list_head list;
	u32 node;
	u32 port;
	enum mbr_state state;
	u16 bc_rcv_nxt;
};

struct tipc_group {
	struct rb_root members;
	struct tipc_nlist dests;
	struct net *net;
	int subid;
	u32 type;
	u32 instance;
	u32 domain;
	u32 scope;
	u32 portid;
	u16 member_cnt;
	u16 bc_snd_nxt;
	bool loopback;
};

static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
				  int mtyp, struct sk_buff_head *xmitq);

u16 tipc_group_bc_snd_nxt(struct tipc_group *grp)
{
	return grp->bc_snd_nxt;
}

static bool tipc_group_is_receiver(struct tipc_member *m)
{
	return m && m->state >= MBR_JOINED;
}

int tipc_group_size(struct tipc_group *grp)
{
	return grp->member_cnt;
}

struct tipc_group *tipc_group_create(struct net *net, u32 portid,
				     struct tipc_group_req *mreq)
{
	struct tipc_group *grp;
	u32 type = mreq->type;

	grp = kzalloc(sizeof(*grp), GFP_ATOMIC);
	if (!grp)
		return NULL;
	tipc_nlist_init(&grp->dests, tipc_own_addr(net));
	grp->members = RB_ROOT;
	grp->net = net;
	grp->portid = portid;
	grp->domain = addr_domain(net, mreq->scope);
	grp->type = type;
	grp->instance = mreq->instance;
	grp->scope = mreq->scope;
	grp->loopback = mreq->flags & TIPC_GROUP_LOOPBACK;
	if (tipc_topsrv_kern_subscr(net, portid, type, 0, ~0, &grp->subid))
		return grp;
	kfree(grp);
	return NULL;
}

void tipc_group_delete(struct net *net, struct tipc_group *grp)
{
	struct rb_root *tree = &grp->members;
	struct tipc_member *m, *tmp;
	struct sk_buff_head xmitq;

	__skb_queue_head_init(&xmitq);

	rbtree_postorder_for_each_entry_safe(m, tmp, tree, tree_node) {
		tipc_group_proto_xmit(grp, m, GRP_LEAVE_MSG, &xmitq);
		list_del(&m->list);
		kfree(m);
	}
	tipc_node_distr_xmit(net, &xmitq);
	tipc_nlist_purge(&grp->dests);
	tipc_topsrv_kern_unsubscr(net, grp->subid);
	kfree(grp);
}

struct tipc_member *tipc_group_find_member(struct tipc_group *grp,
					   u32 node, u32 port)
{
	struct rb_node *n = grp->members.rb_node;
	u64 nkey, key = (u64)node << 32 | port;
	struct tipc_member *m;

	while (n) {
		m = container_of(n, struct tipc_member, tree_node);
		nkey = (u64)m->node << 32 | m->port;
		if (key < nkey)
			n = n->rb_left;
		else if (key > nkey)
			n = n->rb_right;
		else
			return m;
	}
	return NULL;
}

static struct tipc_member *tipc_group_find_node(struct tipc_group *grp,
						u32 node)
{
	struct tipc_member *m;
	struct rb_node *n;

	for (n = rb_first(&grp->members); n; n = rb_next(n)) {
		m = container_of(n, struct tipc_member, tree_node);
		if (m->node == node)
			return m;
	}
	return NULL;
}

static void tipc_group_add_to_tree(struct tipc_group *grp,
				   struct tipc_member *m)
{
	u64 nkey, key = (u64)m->node << 32 | m->port;
	struct rb_node **n, *parent = NULL;
	struct tipc_member *tmp;

	n = &grp->members.rb_node;
	while (*n) {
		tmp = container_of(*n, struct tipc_member, tree_node);
		parent = *n;
		tmp = container_of(parent, struct tipc_member, tree_node);
		nkey = (u64)tmp->node << 32 | tmp->port;
		if (key < nkey)
			n = &(*n)->rb_left;
		else if (key > nkey)
			n = &(*n)->rb_right;
		else
			return;
	}
	rb_link_node(&m->tree_node, parent, n);
	rb_insert_color(&m->tree_node, &grp->members);
}

static struct tipc_member *tipc_group_create_member(struct tipc_group *grp,
						    u32 node, u32 port,
						    int state)
{
	struct tipc_member *m;

	m = kzalloc(sizeof(*m), GFP_ATOMIC);
	if (!m)
		return NULL;
	INIT_LIST_HEAD(&m->list);
	m->node = node;
	m->port = port;
	grp->member_cnt++;
	tipc_group_add_to_tree(grp, m);
	tipc_nlist_add(&grp->dests, m->node);
	m->state = state;
	return m;
}

void tipc_group_add_member(struct tipc_group *grp, u32 node, u32 port)
{
	tipc_group_create_member(grp, node, port, MBR_DISCOVERED);
}

static void tipc_group_delete_member(struct tipc_group *grp,
				     struct tipc_member *m)
{
	rb_erase(&m->tree_node, &grp->members);
	grp->member_cnt--;
	list_del_init(&m->list);

	/* If last member on a node, remove node from dest list */
	if (!tipc_group_find_node(grp, m->node))
		tipc_nlist_del(&grp->dests, m->node);

	kfree(m);
}

struct tipc_nlist *tipc_group_dests(struct tipc_group *grp)
{
	return &grp->dests;
}

void tipc_group_self(struct tipc_group *grp, struct tipc_name_seq *seq,
		     int *scope)
{
	seq->type = grp->type;
	seq->lower = grp->instance;
	seq->upper = grp->instance;
	*scope = grp->scope;
}

void tipc_group_update_bc_members(struct tipc_group *grp)
{
	grp->bc_snd_nxt++;
}

/* tipc_group_filter_msg() - determine if we should accept arriving message
 */
void tipc_group_filter_msg(struct tipc_group *grp, struct sk_buff_head *inputq,
			   struct sk_buff_head *xmitq)
{
	struct sk_buff *skb = __skb_dequeue(inputq);
	struct tipc_member *m;
	struct tipc_msg *hdr;
	u32 node, port;
	int mtyp;

	if (!skb)
		return;

	hdr = buf_msg(skb);
	mtyp = msg_type(hdr);
	node =  msg_orignode(hdr);
	port = msg_origport(hdr);

	if (!msg_in_group(hdr))
		goto drop;

	m = tipc_group_find_member(grp, node, port);
	if (!tipc_group_is_receiver(m))
		goto drop;

	__skb_queue_tail(inputq, skb);

	m->bc_rcv_nxt = msg_grp_bc_seqno(hdr) + 1;
	return;
drop:
	kfree_skb(skb);
}

static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
				  int mtyp, struct sk_buff_head *xmitq)
{
	struct tipc_msg *hdr;
	struct sk_buff *skb;

	skb = tipc_msg_create(GROUP_PROTOCOL, mtyp, INT_H_SIZE, 0,
			      m->node, tipc_own_addr(grp->net),
			      m->port, grp->portid, 0);
	if (!skb)
		return;

	hdr = buf_msg(skb);
	if (mtyp == GRP_JOIN_MSG)
		msg_set_grp_bc_syncpt(hdr, grp->bc_snd_nxt);
	__skb_queue_tail(xmitq, skb);
}

void tipc_group_proto_rcv(struct tipc_group *grp, struct tipc_msg *hdr,
			  struct sk_buff_head *xmitq)
{
	u32 node = msg_orignode(hdr);
	u32 port = msg_origport(hdr);
	struct tipc_member *m;

	if (!grp)
		return;

	m = tipc_group_find_member(grp, node, port);

	switch (msg_type(hdr)) {
	case GRP_JOIN_MSG:
		if (!m)
			m = tipc_group_create_member(grp, node, port,
						     MBR_QUARANTINED);
		if (!m)
			return;
		m->bc_rcv_nxt = msg_grp_bc_syncpt(hdr);

		/* Wait until PUBLISH event is received */
		if (m->state == MBR_DISCOVERED)
			m->state = MBR_JOINING;
		else if (m->state == MBR_PUBLISHED)
			m->state = MBR_JOINED;
		return;
	case GRP_LEAVE_MSG:
		if (!m)
			return;

		/* Wait until WITHDRAW event is received */
		if (m->state != MBR_LEAVING) {
			m->state = MBR_LEAVING;
			return;
		}
		/* Otherwise deliver already received WITHDRAW event */
		tipc_group_delete_member(grp, m);
		return;
	default:
		pr_warn("Received unknown GROUP_PROTO message\n");
	}
}

/* tipc_group_member_evt() - receive and handle a member up/down event
 */
void tipc_group_member_evt(struct tipc_group *grp,
			   struct sk_buff *skb,
			   struct sk_buff_head *xmitq)
{
	struct tipc_msg *hdr = buf_msg(skb);
	struct tipc_event *evt = (void *)msg_data(hdr);
	u32 node = evt->port.node;
	u32 port = evt->port.ref;
	struct tipc_member *m;
	struct net *net;
	u32 self;

	if (!grp)
		goto drop;

	net = grp->net;
	self = tipc_own_addr(net);
	if (!grp->loopback && node == self && port == grp->portid)
		goto drop;

	m = tipc_group_find_member(grp, node, port);

	if (evt->event == TIPC_PUBLISHED) {
		if (!m)
			m = tipc_group_create_member(grp, node, port,
						     MBR_DISCOVERED);
		if (!m)
			goto drop;

		/* Wait if JOIN message not yet received */
		if (m->state == MBR_DISCOVERED)
			m->state = MBR_PUBLISHED;
		else
			m->state = MBR_JOINED;
		tipc_group_proto_xmit(grp, m, GRP_JOIN_MSG, xmitq);
	} else if (evt->event == TIPC_WITHDRAWN) {
		if (!m)
			goto drop;

		/* Keep back event if more messages might be expected */
		if (m->state != MBR_LEAVING && tipc_node_is_up(net, node))
			m->state = MBR_LEAVING;
		else
			tipc_group_delete_member(grp, m);
	}
drop:
	kfree_skb(skb);
}