/*
 * net/tipc/discover.c
 *
 * Copyright (c) 2003-2006, 2014-2018, 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 "node.h"
#include "discover.h"

/* min delay during bearer start up */
#define TIPC_DISC_INIT  msecs_to_jiffies(125)
/* max delay if bearer has no links */
#define TIPC_DISC_FAST  msecs_to_jiffies(1000)
/* max delay if bearer has links */
#define TIPC_DISC_SLOW  msecs_to_jiffies(60000)
/* indicates no timer in use */
#define TIPC_DISC_INACTIVE      0xffffffff

/**
 * struct tipc_discoverer - 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
 * @skb: request message to be (repeatedly) sent
 * @timer: timer governing period between requests
 * @timer_intv: current interval between requests (in ms)
 */
struct tipc_discoverer {
        u32 bearer_id;
        struct tipc_media_addr dest;
        struct net *net;
        u32 domain;
        int num_nodes;
        spinlock_t lock;
        struct sk_buff *skb;
        struct timer_list timer;
        unsigned long timer_intv;
};

/**
 * tipc_disc_init_msg - initialize a link setup message
 * @net: the applicable net namespace
 * @skb: buffer containing message
 * @mtyp: message type (request or response)
 * @b: ptr to bearer issuing message
 */
static void tipc_disc_init_msg(struct net *net, struct sk_buff *skb,
                               u32 mtyp,  struct tipc_bearer *b)
{
        struct tipc_net *tn = tipc_net(net);
        u32 dest_domain = b->domain;
        struct tipc_msg *hdr;

        hdr = buf_msg(skb);
        tipc_msg_init(tn->trial_addr, hdr, LINK_CONFIG, mtyp,
                      MAX_H_SIZE, dest_domain);
        msg_set_size(hdr, MAX_H_SIZE + NODE_ID_LEN);
        msg_set_non_seq(hdr, 1);
        msg_set_node_sig(hdr, tn->random);
        msg_set_node_capabilities(hdr, TIPC_NODE_CAPABILITIES);
        msg_set_dest_domain(hdr, dest_domain);
        msg_set_bc_netid(hdr, tn->net_id);
        b->media->addr2msg(msg_media_addr(hdr), &b->addr);
        msg_set_peer_net_hash(hdr, tipc_net_hash_mixes(net, tn->random));
        msg_set_node_id(hdr, tipc_own_id(net));
}

static void tipc_disc_msg_xmit(struct net *net, u32 mtyp, u32 dst,
                               u32 src, u32 sugg_addr,
                               struct tipc_media_addr *maddr,
                               struct tipc_bearer *b)
{
        struct tipc_msg *hdr;
        struct sk_buff *skb;

        skb = tipc_buf_acquire(MAX_H_SIZE + NODE_ID_LEN, GFP_ATOMIC);
        if (!skb)
                return;
        hdr = buf_msg(skb);
        tipc_disc_init_msg(net, skb, mtyp, b);
        msg_set_sugg_node_addr(hdr, sugg_addr);
        msg_set_dest_domain(hdr, dst);
        tipc_bearer_xmit_skb(net, b->identity, skb, maddr);
}

/**
 * disc_dupl_alert - issue node address duplication alert
 * @b: 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, u32 node_addr,
                            struct tipc_media_addr *media_addr)
{
        char media_addr_str[64];

        tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
                               media_addr);
        pr_warn("Duplicate %x using %s seen on <%s>\n", node_addr,
                media_addr_str, b->name);
}

/* tipc_disc_addr_trial(): - handle an address uniqueness trial from peer
 * Returns true if message should be dropped by caller, i.e., if it is a
 * trial message or we are inside trial period. Otherwise false.
 */
static bool tipc_disc_addr_trial_msg(struct tipc_discoverer *d,
                                     struct tipc_media_addr *maddr,
                                     struct tipc_bearer *b,
                                     u32 dst, u32 src,
                                     u32 sugg_addr,
                                     u8 *peer_id,
                                     int mtyp)
{
        struct net *net = d->net;
        struct tipc_net *tn = tipc_net(net);
        u32 self = tipc_own_addr(net);
        bool trial = time_before(jiffies, tn->addr_trial_end) && !self;

        if (mtyp == DSC_TRIAL_FAIL_MSG) {
                if (!trial)
                        return true;

                /* Ignore if somebody else already gave new suggestion */
                if (dst != tn->trial_addr)
                        return true;

                /* Otherwise update trial address and restart trial period */
                tn->trial_addr = sugg_addr;
                msg_set_prevnode(buf_msg(d->skb), sugg_addr);
                tn->addr_trial_end = jiffies + msecs_to_jiffies(1000);
                return true;
        }

        /* Apply trial address if we just left trial period */
        if (!trial && !self) {
                schedule_work(&tn->work);
                msg_set_prevnode(buf_msg(d->skb), tn->trial_addr);
                msg_set_type(buf_msg(d->skb), DSC_REQ_MSG);
        }

        /* Accept regular link requests/responses only after trial period */
        if (mtyp != DSC_TRIAL_MSG)
                return trial;

        sugg_addr = tipc_node_try_addr(net, peer_id, src);
        if (sugg_addr)
                tipc_disc_msg_xmit(net, DSC_TRIAL_FAIL_MSG, src,
                                   self, sugg_addr, maddr, b);
        return true;
}

/**
 * tipc_disc_rcv - handle incoming discovery message (request or response)
 * @net: applicable net namespace
 * @skb: buffer containing message
 * @b: bearer that message arrived on
 */
void tipc_disc_rcv(struct net *net, struct sk_buff *skb,
                   struct tipc_bearer *b)
{
        struct tipc_net *tn = tipc_net(net);
        struct tipc_msg *hdr = buf_msg(skb);
        u32 pnet_hash = msg_peer_net_hash(hdr);
        u16 caps = msg_node_capabilities(hdr);
        bool legacy = tn->legacy_addr_format;
        u32 sugg = msg_sugg_node_addr(hdr);
        u32 signature = msg_node_sig(hdr);
        u8 peer_id[NODE_ID_LEN] = {0,};
        u32 dst = msg_dest_domain(hdr);
        u32 net_id = msg_bc_netid(hdr);
        struct tipc_media_addr maddr;
        u32 src = msg_prevnode(hdr);
        u32 mtyp = msg_type(hdr);
        bool dupl_addr = false;
        bool respond = false;
        u32 self;
        int err;

        if (skb_linearize(skb)) {
                kfree_skb(skb);
                return;
        }
        hdr = buf_msg(skb);

        if (caps & TIPC_NODE_ID128)
                memcpy(peer_id, msg_node_id(hdr), NODE_ID_LEN);
        else
                sprintf(peer_id, "%x", src);

        err = b->media->msg2addr(b, &maddr, msg_media_addr(hdr));
        kfree_skb(skb);
        if (err || maddr.broadcast) {
                pr_warn_ratelimited("Rcv corrupt discovery message\n");
                return;
        }
        /* Ignore discovery messages from own node */
        if (!memcmp(&maddr, &b->addr, sizeof(maddr)))
                return;
        if (net_id != tn->net_id)
                return;
        if (tipc_disc_addr_trial_msg(b->disc, &maddr, b, dst,
                                     src, sugg, peer_id, mtyp))
                return;
        self = tipc_own_addr(net);

        /* Message from somebody using this node's address */
        if (in_own_node(net, src)) {
                disc_dupl_alert(b, self, &maddr);
                return;
        }
        if (!tipc_in_scope(legacy, dst, self))
                return;
        if (!tipc_in_scope(legacy, b->domain, src))
                return;
        tipc_node_check_dest(net, src, peer_id, b, caps, signature, pnet_hash,
                             &maddr, &respond, &dupl_addr);
        if (dupl_addr)
                disc_dupl_alert(b, src, &maddr);
        if (!respond)
                return;
        if (mtyp != DSC_REQ_MSG)
                return;
        tipc_disc_msg_xmit(net, DSC_RESP_MSG, src, self, 0, &maddr, b);
}

/* tipc_disc_add_dest - increment set of discovered nodes
 */
void tipc_disc_add_dest(struct tipc_discoverer *d)
{
        spin_lock_bh(&d->lock);
        d->num_nodes++;
        spin_unlock_bh(&d->lock);
}

/* tipc_disc_remove_dest - decrement set of discovered nodes
 */
void tipc_disc_remove_dest(struct tipc_discoverer *d)
{
        int intv, num;

        spin_lock_bh(&d->lock);
        d->num_nodes--;
        num = d->num_nodes;
        intv = d->timer_intv;
        if (!num && (intv == TIPC_DISC_INACTIVE || intv > TIPC_DISC_FAST))  {
                d->timer_intv = TIPC_DISC_INIT;
                mod_timer(&d->timer, jiffies + d->timer_intv);
        }
        spin_unlock_bh(&d->lock);
}

/* tipc_disc_timeout - send a periodic link setup request
 * Called whenever a link setup request timer associated with a bearer expires.
 * - Keep doubling time between sent request until limit is reached;
 * - Hold at fast polling rate if we don't have any associated nodes
 * - Otherwise hold at slow polling rate
 */
static void tipc_disc_timeout(struct timer_list *t)
{
        struct tipc_discoverer *d = timer_container_of(d, t, timer);
        struct tipc_net *tn = tipc_net(d->net);
        struct tipc_media_addr maddr;
        struct sk_buff *skb = NULL;
        struct net *net = d->net;
        u32 bearer_id;

        spin_lock_bh(&d->lock);

        /* Stop searching if only desired node has been found */
        if (tipc_node(d->domain) && d->num_nodes) {
                d->timer_intv = TIPC_DISC_INACTIVE;
                goto exit;
        }

        /* Did we just leave trial period ? */
        if (!time_before(jiffies, tn->addr_trial_end) && !tipc_own_addr(net)) {
                mod_timer(&d->timer, jiffies + TIPC_DISC_INIT);
                spin_unlock_bh(&d->lock);
                schedule_work(&tn->work);
                return;
        }

        /* Adjust timeout interval according to discovery phase */
        if (time_before(jiffies, tn->addr_trial_end)) {
                d->timer_intv = TIPC_DISC_INIT;
        } else {
                d->timer_intv *= 2;
                if (d->num_nodes && d->timer_intv > TIPC_DISC_SLOW)
                        d->timer_intv = TIPC_DISC_SLOW;
                else if (!d->num_nodes && d->timer_intv > TIPC_DISC_FAST)
                        d->timer_intv = TIPC_DISC_FAST;
                msg_set_type(buf_msg(d->skb), DSC_REQ_MSG);
                msg_set_prevnode(buf_msg(d->skb), tn->trial_addr);
        }

        mod_timer(&d->timer, jiffies + d->timer_intv);
        memcpy(&maddr, &d->dest, sizeof(maddr));
        skb = skb_clone(d->skb, GFP_ATOMIC);
        bearer_id = d->bearer_id;
exit:
        spin_unlock_bh(&d->lock);
        if (skb)
                tipc_bearer_xmit_skb(net, bearer_id, skb, &maddr);
}

/**
 * tipc_disc_create - create object to send periodic link setup requests
 * @net: the applicable net namespace
 * @b: ptr to bearer issuing requests
 * @dest: destination address for request messages
 * @skb: pointer to created frame
 *
 * Return: 0 if successful, otherwise -errno.
 */
int tipc_disc_create(struct net *net, struct tipc_bearer *b,
                     struct tipc_media_addr *dest, struct sk_buff **skb)
{
        struct tipc_net *tn = tipc_net(net);
        struct tipc_discoverer *d;

        d = kmalloc_obj(*d, GFP_ATOMIC);
        if (!d)
                return -ENOMEM;
        d->skb = tipc_buf_acquire(MAX_H_SIZE + NODE_ID_LEN, GFP_ATOMIC);
        if (!d->skb) {
                kfree(d);
                return -ENOMEM;
        }
        tipc_disc_init_msg(net, d->skb, DSC_REQ_MSG, b);

        /* Do we need an address trial period first ? */
        if (!tipc_own_addr(net)) {
                tn->addr_trial_end = jiffies + msecs_to_jiffies(1000);
                msg_set_type(buf_msg(d->skb), DSC_TRIAL_MSG);
        }
        memcpy(&d->dest, dest, sizeof(*dest));
        d->net = net;
        d->bearer_id = b->identity;
        d->domain = b->domain;
        d->num_nodes = 0;
        d->timer_intv = TIPC_DISC_INIT;
        spin_lock_init(&d->lock);
        timer_setup(&d->timer, tipc_disc_timeout, 0);
        mod_timer(&d->timer, jiffies + d->timer_intv);
        b->disc = d;
        *skb = skb_clone(d->skb, GFP_ATOMIC);
        return 0;
}

/**
 * tipc_disc_delete - destroy object sending periodic link setup requests
 * @d: ptr to link dest structure
 */
void tipc_disc_delete(struct tipc_discoverer *d)
{
        timer_shutdown_sync(&d->timer);
        kfree_skb(d->skb);
        kfree(d);
}

/**
 * tipc_disc_reset - reset object to send periodic link setup requests
 * @net: the applicable net namespace
 * @b: ptr to bearer issuing requests
 */
void tipc_disc_reset(struct net *net, struct tipc_bearer *b)
{
        struct tipc_discoverer *d = b->disc;
        struct tipc_media_addr maddr;
        struct sk_buff *skb;

        spin_lock_bh(&d->lock);
        tipc_disc_init_msg(net, d->skb, DSC_REQ_MSG, b);
        d->net = net;
        d->bearer_id = b->identity;
        d->domain = b->domain;
        d->num_nodes = 0;
        d->timer_intv = TIPC_DISC_INIT;
        memcpy(&maddr, &d->dest, sizeof(maddr));
        mod_timer(&d->timer, jiffies + d->timer_intv);
        skb = skb_clone(d->skb, GFP_ATOMIC);
        spin_unlock_bh(&d->lock);
        if (skb)
                tipc_bearer_xmit_skb(net, b->identity, skb, &maddr);
}