// SPDX-License-Identifier: GPL-2.0-only
/*
 *      IEEE 802.1Q Multiple Registration Protocol (MRP)
 *
 *      Copyright (c) 2012 Massachusetts Institute of Technology
 *
 *      Adapted from code in net/802/garp.c
 *      Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
 */
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <net/mrp.h>
#include <linux/unaligned.h>

static unsigned int mrp_join_time __read_mostly = 200;
module_param(mrp_join_time, uint, 0644);
MODULE_PARM_DESC(mrp_join_time, "Join time in ms (default 200ms)");

static unsigned int mrp_periodic_time __read_mostly = 1000;
module_param(mrp_periodic_time, uint, 0644);
MODULE_PARM_DESC(mrp_periodic_time, "Periodic time in ms (default 1s)");

MODULE_DESCRIPTION("IEEE 802.1Q Multiple Registration Protocol (MRP)");
MODULE_LICENSE("GPL");

static const u8
mrp_applicant_state_table[MRP_APPLICANT_MAX + 1][MRP_EVENT_MAX + 1] = {
        [MRP_APPLICANT_VO] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_VP,
                [MRP_EVENT_LV]          = MRP_APPLICANT_VO,
                [MRP_EVENT_TX]          = MRP_APPLICANT_VO,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_VO,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_AO,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_VO,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_VO,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_VO,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VO,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VO,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VO,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_VO,
        },
        [MRP_APPLICANT_VP] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_VP,
                [MRP_EVENT_LV]          = MRP_APPLICANT_VO,
                [MRP_EVENT_TX]          = MRP_APPLICANT_AA,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_VP,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_AP,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_VP,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_VP,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_VP,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VP,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VP,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VP,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_VP,
        },
        [MRP_APPLICANT_VN] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_VN,
                [MRP_EVENT_LV]          = MRP_APPLICANT_LA,
                [MRP_EVENT_TX]          = MRP_APPLICANT_AN,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_VN,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_VN,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_VN,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_VN,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_VN,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VN,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VN,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VN,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_VN,
        },
        [MRP_APPLICANT_AN] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_AN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_AN,
                [MRP_EVENT_LV]          = MRP_APPLICANT_LA,
                [MRP_EVENT_TX]          = MRP_APPLICANT_QA,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_AN,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_AN,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_AN,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_AN,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_AN,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VN,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VN,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VN,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_AN,
        },
        [MRP_APPLICANT_AA] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_AA,
                [MRP_EVENT_LV]          = MRP_APPLICANT_LA,
                [MRP_EVENT_TX]          = MRP_APPLICANT_QA,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_AA,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_QA,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_AA,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_AA,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_AA,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VP,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VP,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VP,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_AA,
        },
        [MRP_APPLICANT_QA] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_QA,
                [MRP_EVENT_LV]          = MRP_APPLICANT_LA,
                [MRP_EVENT_TX]          = MRP_APPLICANT_QA,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_QA,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_QA,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_QA,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_AA,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_AA,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VP,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VP,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VP,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_AA,
        },
        [MRP_APPLICANT_LA] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_AA,
                [MRP_EVENT_LV]          = MRP_APPLICANT_LA,
                [MRP_EVENT_TX]          = MRP_APPLICANT_VO,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_LA,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_LA,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_LA,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_LA,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_LA,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_LA,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_LA,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_LA,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_LA,
        },
        [MRP_APPLICANT_AO] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_AP,
                [MRP_EVENT_LV]          = MRP_APPLICANT_AO,
                [MRP_EVENT_TX]          = MRP_APPLICANT_AO,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_AO,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_QO,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_AO,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_AO,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_AO,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VO,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VO,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VO,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_AO,
        },
        [MRP_APPLICANT_QO] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_QP,
                [MRP_EVENT_LV]          = MRP_APPLICANT_QO,
                [MRP_EVENT_TX]          = MRP_APPLICANT_QO,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_QO,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_QO,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_QO,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_AO,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_AO,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VO,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VO,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VO,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_QO,
        },
        [MRP_APPLICANT_AP] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_AP,
                [MRP_EVENT_LV]          = MRP_APPLICANT_AO,
                [MRP_EVENT_TX]          = MRP_APPLICANT_QA,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_AP,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_QP,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_AP,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_AP,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_AP,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VP,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VP,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VP,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_AP,
        },
        [MRP_APPLICANT_QP] = {
                [MRP_EVENT_NEW]         = MRP_APPLICANT_VN,
                [MRP_EVENT_JOIN]        = MRP_APPLICANT_QP,
                [MRP_EVENT_LV]          = MRP_APPLICANT_QO,
                [MRP_EVENT_TX]          = MRP_APPLICANT_QP,
                [MRP_EVENT_R_NEW]       = MRP_APPLICANT_QP,
                [MRP_EVENT_R_JOIN_IN]   = MRP_APPLICANT_QP,
                [MRP_EVENT_R_IN]        = MRP_APPLICANT_QP,
                [MRP_EVENT_R_JOIN_MT]   = MRP_APPLICANT_AP,
                [MRP_EVENT_R_MT]        = MRP_APPLICANT_AP,
                [MRP_EVENT_R_LV]        = MRP_APPLICANT_VP,
                [MRP_EVENT_R_LA]        = MRP_APPLICANT_VP,
                [MRP_EVENT_REDECLARE]   = MRP_APPLICANT_VP,
                [MRP_EVENT_PERIODIC]    = MRP_APPLICANT_AP,
        },
};

static const u8
mrp_tx_action_table[MRP_APPLICANT_MAX + 1] = {
        [MRP_APPLICANT_VO] = MRP_TX_ACTION_S_IN_OPTIONAL,
        [MRP_APPLICANT_VP] = MRP_TX_ACTION_S_JOIN_IN,
        [MRP_APPLICANT_VN] = MRP_TX_ACTION_S_NEW,
        [MRP_APPLICANT_AN] = MRP_TX_ACTION_S_NEW,
        [MRP_APPLICANT_AA] = MRP_TX_ACTION_S_JOIN_IN,
        [MRP_APPLICANT_QA] = MRP_TX_ACTION_S_JOIN_IN_OPTIONAL,
        [MRP_APPLICANT_LA] = MRP_TX_ACTION_S_LV,
        [MRP_APPLICANT_AO] = MRP_TX_ACTION_S_IN_OPTIONAL,
        [MRP_APPLICANT_QO] = MRP_TX_ACTION_S_IN_OPTIONAL,
        [MRP_APPLICANT_AP] = MRP_TX_ACTION_S_JOIN_IN,
        [MRP_APPLICANT_QP] = MRP_TX_ACTION_S_IN_OPTIONAL,
};

static void mrp_attrvalue_inc(void *value, u8 len)
{
        u8 *v = (u8 *)value;

        /* Add 1 to the last byte. If it becomes zero,
         * go to the previous byte and repeat.
         */
        while (len > 0 && !++v[--len])
                ;
}

static int mrp_attr_cmp(const struct mrp_attr *attr,
                         const void *value, u8 len, u8 type)
{
        if (attr->type != type)
                return attr->type - type;
        if (attr->len != len)
                return attr->len - len;
        return memcmp(attr->value, value, len);
}

static struct mrp_attr *mrp_attr_lookup(const struct mrp_applicant *app,
                                        const void *value, u8 len, u8 type)
{
        struct rb_node *parent = app->mad.rb_node;
        struct mrp_attr *attr;
        int d;

        while (parent) {
                attr = rb_entry(parent, struct mrp_attr, node);
                d = mrp_attr_cmp(attr, value, len, type);
                if (d > 0)
                        parent = parent->rb_left;
                else if (d < 0)
                        parent = parent->rb_right;
                else
                        return attr;
        }
        return NULL;
}

static struct mrp_attr *mrp_attr_create(struct mrp_applicant *app,
                                        const void *value, u8 len, u8 type)
{
        struct rb_node *parent = NULL, **p = &app->mad.rb_node;
        struct mrp_attr *attr;
        int d;

        while (*p) {
                parent = *p;
                attr = rb_entry(parent, struct mrp_attr, node);
                d = mrp_attr_cmp(attr, value, len, type);
                if (d > 0)
                        p = &parent->rb_left;
                else if (d < 0)
                        p = &parent->rb_right;
                else {
                        /* The attribute already exists; re-use it. */
                        return attr;
                }
        }
        attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
        if (!attr)
                return attr;
        attr->state = MRP_APPLICANT_VO;
        attr->type  = type;
        attr->len   = len;
        memcpy(attr->value, value, len);

        rb_link_node(&attr->node, parent, p);
        rb_insert_color(&attr->node, &app->mad);
        return attr;
}

static void mrp_attr_destroy(struct mrp_applicant *app, struct mrp_attr *attr)
{
        rb_erase(&attr->node, &app->mad);
        kfree(attr);
}

static void mrp_attr_destroy_all(struct mrp_applicant *app)
{
        struct rb_node *node, *next;
        struct mrp_attr *attr;

        for (node = rb_first(&app->mad);
             next = node ? rb_next(node) : NULL, node != NULL;
             node = next) {
                attr = rb_entry(node, struct mrp_attr, node);
                mrp_attr_destroy(app, attr);
        }
}

static int mrp_pdu_init(struct mrp_applicant *app)
{
        struct sk_buff *skb;
        struct mrp_pdu_hdr *ph;

        skb = alloc_skb(app->dev->mtu + LL_RESERVED_SPACE(app->dev),
                        GFP_ATOMIC);
        if (!skb)
                return -ENOMEM;

        skb->dev = app->dev;
        skb->protocol = app->app->pkttype.type;
        skb_reserve(skb, LL_RESERVED_SPACE(app->dev));
        skb_reset_network_header(skb);
        skb_reset_transport_header(skb);

        ph = __skb_put(skb, sizeof(*ph));
        ph->version = app->app->version;

        app->pdu = skb;
        return 0;
}

static int mrp_pdu_append_end_mark(struct mrp_applicant *app)
{
        __be16 *endmark;

        if (skb_tailroom(app->pdu) < sizeof(*endmark))
                return -1;
        endmark = __skb_put(app->pdu, sizeof(*endmark));
        put_unaligned(MRP_END_MARK, endmark);
        return 0;
}

static void mrp_pdu_queue(struct mrp_applicant *app)
{
        if (!app->pdu)
                return;

        if (mrp_cb(app->pdu)->mh)
                mrp_pdu_append_end_mark(app);
        mrp_pdu_append_end_mark(app);

        dev_hard_header(app->pdu, app->dev, ntohs(app->app->pkttype.type),
                        app->app->group_address, app->dev->dev_addr,
                        app->pdu->len);

        skb_queue_tail(&app->queue, app->pdu);
        app->pdu = NULL;
}

static void mrp_queue_xmit(struct mrp_applicant *app)
{
        struct sk_buff *skb;

        while ((skb = skb_dequeue(&app->queue)))
                dev_queue_xmit(skb);
}

static int mrp_pdu_append_msg_hdr(struct mrp_applicant *app,
                                  u8 attrtype, u8 attrlen)
{
        struct mrp_msg_hdr *mh;

        if (mrp_cb(app->pdu)->mh) {
                if (mrp_pdu_append_end_mark(app) < 0)
                        return -1;
                mrp_cb(app->pdu)->mh = NULL;
                mrp_cb(app->pdu)->vah = NULL;
        }

        if (skb_tailroom(app->pdu) < sizeof(*mh))
                return -1;
        mh = __skb_put(app->pdu, sizeof(*mh));
        mh->attrtype = attrtype;
        mh->attrlen = attrlen;
        mrp_cb(app->pdu)->mh = mh;
        return 0;
}

static int mrp_pdu_append_vecattr_hdr(struct mrp_applicant *app,
                                      const void *firstattrvalue, u8 attrlen)
{
        struct mrp_vecattr_hdr *vah;

        if (skb_tailroom(app->pdu) < sizeof(*vah) + attrlen)
                return -1;
        vah = __skb_put(app->pdu, sizeof(*vah) + attrlen);
        put_unaligned(0, &vah->lenflags);
        memcpy(vah->firstattrvalue, firstattrvalue, attrlen);
        mrp_cb(app->pdu)->vah = vah;
        memcpy(mrp_cb(app->pdu)->attrvalue, firstattrvalue, attrlen);
        return 0;
}

static int mrp_pdu_append_vecattr_event(struct mrp_applicant *app,
                                        const struct mrp_attr *attr,
                                        enum mrp_vecattr_event vaevent)
{
        u16 len, pos;
        u8 *vaevents;
        int err;
again:
        if (!app->pdu) {
                err = mrp_pdu_init(app);
                if (err < 0)
                        return err;
        }

        /* If there is no Message header in the PDU, or the Message header is
         * for a different attribute type, add an EndMark (if necessary) and a
         * new Message header to the PDU.
         */
        if (!mrp_cb(app->pdu)->mh ||
            mrp_cb(app->pdu)->mh->attrtype != attr->type ||
            mrp_cb(app->pdu)->mh->attrlen != attr->len) {
                if (mrp_pdu_append_msg_hdr(app, attr->type, attr->len) < 0)
                        goto queue;
        }

        /* If there is no VectorAttribute header for this Message in the PDU,
         * or this attribute's value does not sequentially follow the previous
         * attribute's value, add a new VectorAttribute header to the PDU.
         */
        if (!mrp_cb(app->pdu)->vah ||
            memcmp(mrp_cb(app->pdu)->attrvalue, attr->value, attr->len)) {
                if (mrp_pdu_append_vecattr_hdr(app, attr->value, attr->len) < 0)
                        goto queue;
        }

        len = be16_to_cpu(get_unaligned(&mrp_cb(app->pdu)->vah->lenflags));
        pos = len % 3;

        /* Events are packed into Vectors in the PDU, three to a byte. Add a
         * byte to the end of the Vector if necessary.
         */
        if (!pos) {
                if (skb_tailroom(app->pdu) < sizeof(u8))
                        goto queue;
                vaevents = __skb_put(app->pdu, sizeof(u8));
        } else {
                vaevents = (u8 *)(skb_tail_pointer(app->pdu) - sizeof(u8));
        }

        switch (pos) {
        case 0:
                *vaevents = vaevent * (__MRP_VECATTR_EVENT_MAX *
                                       __MRP_VECATTR_EVENT_MAX);
                break;
        case 1:
                *vaevents += vaevent * __MRP_VECATTR_EVENT_MAX;
                break;
        case 2:
                *vaevents += vaevent;
                break;
        default:
                WARN_ON(1);
        }

        /* Increment the length of the VectorAttribute in the PDU, as well as
         * the value of the next attribute that would continue its Vector.
         */
        put_unaligned(cpu_to_be16(++len), &mrp_cb(app->pdu)->vah->lenflags);
        mrp_attrvalue_inc(mrp_cb(app->pdu)->attrvalue, attr->len);

        return 0;

queue:
        mrp_pdu_queue(app);
        goto again;
}

static void mrp_attr_event(struct mrp_applicant *app,
                           struct mrp_attr *attr, enum mrp_event event)
{
        enum mrp_applicant_state state;

        state = mrp_applicant_state_table[attr->state][event];
        if (state == MRP_APPLICANT_INVALID) {
                WARN_ON(1);
                return;
        }

        if (event == MRP_EVENT_TX) {
                /* When appending the attribute fails, don't update its state
                 * in order to retry at the next TX event.
                 */

                switch (mrp_tx_action_table[attr->state]) {
                case MRP_TX_ACTION_NONE:
                case MRP_TX_ACTION_S_JOIN_IN_OPTIONAL:
                case MRP_TX_ACTION_S_IN_OPTIONAL:
                        break;
                case MRP_TX_ACTION_S_NEW:
                        if (mrp_pdu_append_vecattr_event(
                                    app, attr, MRP_VECATTR_EVENT_NEW) < 0)
                                return;
                        break;
                case MRP_TX_ACTION_S_JOIN_IN:
                        if (mrp_pdu_append_vecattr_event(
                                    app, attr, MRP_VECATTR_EVENT_JOIN_IN) < 0)
                                return;
                        break;
                case MRP_TX_ACTION_S_LV:
                        if (mrp_pdu_append_vecattr_event(
                                    app, attr, MRP_VECATTR_EVENT_LV) < 0)
                                return;
                        /* As a pure applicant, sending a leave message
                         * implies that the attribute was unregistered and
                         * can be destroyed.
                         */
                        mrp_attr_destroy(app, attr);
                        return;
                default:
                        WARN_ON(1);
                }
        }

        attr->state = state;
}

int mrp_request_join(const struct net_device *dev,
                     const struct mrp_application *appl,
                     const void *value, u8 len, u8 type)
{
        struct mrp_port *port = rtnl_dereference(dev->mrp_port);
        struct mrp_applicant *app = rtnl_dereference(
                port->applicants[appl->type]);
        struct mrp_attr *attr;

        if (sizeof(struct mrp_skb_cb) + len >
            sizeof_field(struct sk_buff, cb))
                return -ENOMEM;

        spin_lock_bh(&app->lock);
        attr = mrp_attr_create(app, value, len, type);
        if (!attr) {
                spin_unlock_bh(&app->lock);
                return -ENOMEM;
        }
        mrp_attr_event(app, attr, MRP_EVENT_JOIN);
        spin_unlock_bh(&app->lock);
        return 0;
}
EXPORT_SYMBOL_GPL(mrp_request_join);

void mrp_request_leave(const struct net_device *dev,
                       const struct mrp_application *appl,
                       const void *value, u8 len, u8 type)
{
        struct mrp_port *port = rtnl_dereference(dev->mrp_port);
        struct mrp_applicant *app = rtnl_dereference(
                port->applicants[appl->type]);
        struct mrp_attr *attr;

        if (sizeof(struct mrp_skb_cb) + len >
            sizeof_field(struct sk_buff, cb))
                return;

        spin_lock_bh(&app->lock);
        attr = mrp_attr_lookup(app, value, len, type);
        if (!attr) {
                spin_unlock_bh(&app->lock);
                return;
        }
        mrp_attr_event(app, attr, MRP_EVENT_LV);
        spin_unlock_bh(&app->lock);
}
EXPORT_SYMBOL_GPL(mrp_request_leave);

static void mrp_mad_event(struct mrp_applicant *app, enum mrp_event event)
{
        struct rb_node *node, *next;
        struct mrp_attr *attr;

        for (node = rb_first(&app->mad);
             next = node ? rb_next(node) : NULL, node != NULL;
             node = next) {
                attr = rb_entry(node, struct mrp_attr, node);
                mrp_attr_event(app, attr, event);
        }
}

static void mrp_join_timer_arm(struct mrp_applicant *app)
{
        unsigned long delay;

        delay = get_random_u32_below(msecs_to_jiffies(mrp_join_time));
        mod_timer(&app->join_timer, jiffies + delay);
}

static void mrp_join_timer(struct timer_list *t)
{
        struct mrp_applicant *app = timer_container_of(app, t, join_timer);

        spin_lock(&app->lock);
        mrp_mad_event(app, MRP_EVENT_TX);
        mrp_pdu_queue(app);
        spin_unlock(&app->lock);

        mrp_queue_xmit(app);
        spin_lock(&app->lock);
        if (likely(app->active))
                mrp_join_timer_arm(app);
        spin_unlock(&app->lock);
}

static void mrp_periodic_timer_arm(struct mrp_applicant *app)
{
        mod_timer(&app->periodic_timer,
                  jiffies + msecs_to_jiffies(mrp_periodic_time));
}

static void mrp_periodic_timer(struct timer_list *t)
{
        struct mrp_applicant *app = timer_container_of(app, t, periodic_timer);

        spin_lock(&app->lock);
        if (likely(app->active)) {
                mrp_mad_event(app, MRP_EVENT_PERIODIC);
                mrp_pdu_queue(app);
                mrp_periodic_timer_arm(app);
        }
        spin_unlock(&app->lock);
}

static int mrp_pdu_parse_end_mark(struct sk_buff *skb, int *offset)
{
        __be16 endmark;

        if (skb_copy_bits(skb, *offset, &endmark, sizeof(endmark)) < 0)
                return -1;
        if (endmark == MRP_END_MARK) {
                *offset += sizeof(endmark);
                return -1;
        }
        return 0;
}

static void mrp_pdu_parse_vecattr_event(struct mrp_applicant *app,
                                        struct sk_buff *skb,
                                        enum mrp_vecattr_event vaevent)
{
        struct mrp_attr *attr;
        enum mrp_event event;

        attr = mrp_attr_lookup(app, mrp_cb(skb)->attrvalue,
                               mrp_cb(skb)->mh->attrlen,
                               mrp_cb(skb)->mh->attrtype);
        if (attr == NULL)
                return;

        switch (vaevent) {
        case MRP_VECATTR_EVENT_NEW:
                event = MRP_EVENT_R_NEW;
                break;
        case MRP_VECATTR_EVENT_JOIN_IN:
                event = MRP_EVENT_R_JOIN_IN;
                break;
        case MRP_VECATTR_EVENT_IN:
                event = MRP_EVENT_R_IN;
                break;
        case MRP_VECATTR_EVENT_JOIN_MT:
                event = MRP_EVENT_R_JOIN_MT;
                break;
        case MRP_VECATTR_EVENT_MT:
                event = MRP_EVENT_R_MT;
                break;
        case MRP_VECATTR_EVENT_LV:
                event = MRP_EVENT_R_LV;
                break;
        default:
                return;
        }

        mrp_attr_event(app, attr, event);
}

static int mrp_pdu_parse_vecattr(struct mrp_applicant *app,
                                 struct sk_buff *skb, int *offset)
{
        struct mrp_vecattr_hdr _vah;
        u16 valen;
        u8 vaevents, vaevent;

        mrp_cb(skb)->vah = skb_header_pointer(skb, *offset, sizeof(_vah),
                                              &_vah);
        if (!mrp_cb(skb)->vah)
                return -1;
        *offset += sizeof(_vah);

        if (get_unaligned(&mrp_cb(skb)->vah->lenflags) &
            MRP_VECATTR_HDR_FLAG_LA)
                mrp_mad_event(app, MRP_EVENT_R_LA);
        valen = be16_to_cpu(get_unaligned(&mrp_cb(skb)->vah->lenflags) &
                            MRP_VECATTR_HDR_LEN_MASK);

        /* The VectorAttribute structure in a PDU carries event information
         * about one or more attributes having consecutive values. Only the
         * value for the first attribute is contained in the structure. So
         * we make a copy of that value, and then increment it each time we
         * advance to the next event in its Vector.
         */
        if (sizeof(struct mrp_skb_cb) + mrp_cb(skb)->mh->attrlen >
            sizeof_field(struct sk_buff, cb))
                return -1;
        if (skb_copy_bits(skb, *offset, mrp_cb(skb)->attrvalue,
                          mrp_cb(skb)->mh->attrlen) < 0)
                return -1;
        *offset += mrp_cb(skb)->mh->attrlen;

        /* In a VectorAttribute, the Vector contains events which are packed
         * three to a byte. We process one byte of the Vector at a time.
         */
        while (valen > 0) {
                if (skb_copy_bits(skb, *offset, &vaevents,
                                  sizeof(vaevents)) < 0)
                        return -1;
                *offset += sizeof(vaevents);

                /* Extract and process the first event. */
                vaevent = vaevents / (__MRP_VECATTR_EVENT_MAX *
                                      __MRP_VECATTR_EVENT_MAX);
                if (vaevent >= __MRP_VECATTR_EVENT_MAX) {
                        /* The byte is malformed; stop processing. */
                        return -1;
                }
                mrp_pdu_parse_vecattr_event(app, skb, vaevent);

                /* If present, extract and process the second event. */
                if (!--valen)
                        break;
                mrp_attrvalue_inc(mrp_cb(skb)->attrvalue,
                                  mrp_cb(skb)->mh->attrlen);
                vaevents %= (__MRP_VECATTR_EVENT_MAX *
                             __MRP_VECATTR_EVENT_MAX);
                vaevent = vaevents / __MRP_VECATTR_EVENT_MAX;
                mrp_pdu_parse_vecattr_event(app, skb, vaevent);

                /* If present, extract and process the third event. */
                if (!--valen)
                        break;
                mrp_attrvalue_inc(mrp_cb(skb)->attrvalue,
                                  mrp_cb(skb)->mh->attrlen);
                vaevents %= __MRP_VECATTR_EVENT_MAX;
                vaevent = vaevents;
                mrp_pdu_parse_vecattr_event(app, skb, vaevent);
        }
        return 0;
}

static int mrp_pdu_parse_msg(struct mrp_applicant *app, struct sk_buff *skb,
                             int *offset)
{
        struct mrp_msg_hdr _mh;

        mrp_cb(skb)->mh = skb_header_pointer(skb, *offset, sizeof(_mh), &_mh);
        if (!mrp_cb(skb)->mh)
                return -1;
        *offset += sizeof(_mh);

        if (mrp_cb(skb)->mh->attrtype == 0 ||
            mrp_cb(skb)->mh->attrtype > app->app->maxattr ||
            mrp_cb(skb)->mh->attrlen == 0)
                return -1;

        while (skb->len > *offset) {
                if (mrp_pdu_parse_end_mark(skb, offset) < 0)
                        break;
                if (mrp_pdu_parse_vecattr(app, skb, offset) < 0)
                        return -1;
        }
        return 0;
}

static int mrp_rcv(struct sk_buff *skb, struct net_device *dev,
                   struct packet_type *pt, struct net_device *orig_dev)
{
        struct mrp_application *appl = container_of(pt, struct mrp_application,
                                                    pkttype);
        struct mrp_port *port;
        struct mrp_applicant *app;
        struct mrp_pdu_hdr _ph;
        const struct mrp_pdu_hdr *ph;
        int offset = skb_network_offset(skb);

        /* If the interface is in promiscuous mode, drop the packet if
         * it was unicast to another host.
         */
        if (unlikely(skb->pkt_type == PACKET_OTHERHOST))
                goto out;
        skb = skb_share_check(skb, GFP_ATOMIC);
        if (unlikely(!skb))
                goto out;
        port = rcu_dereference(dev->mrp_port);
        if (unlikely(!port))
                goto out;
        app = rcu_dereference(port->applicants[appl->type]);
        if (unlikely(!app))
                goto out;

        ph = skb_header_pointer(skb, offset, sizeof(_ph), &_ph);
        if (!ph)
                goto out;
        offset += sizeof(_ph);

        if (ph->version != app->app->version)
                goto out;

        spin_lock(&app->lock);
        while (skb->len > offset) {
                if (mrp_pdu_parse_end_mark(skb, &offset) < 0)
                        break;
                if (mrp_pdu_parse_msg(app, skb, &offset) < 0)
                        break;
        }
        spin_unlock(&app->lock);
out:
        kfree_skb(skb);
        return 0;
}

static int mrp_init_port(struct net_device *dev)
{
        struct mrp_port *port;

        port = kzalloc_obj(*port);
        if (!port)
                return -ENOMEM;
        rcu_assign_pointer(dev->mrp_port, port);
        return 0;
}

static void mrp_release_port(struct net_device *dev)
{
        struct mrp_port *port = rtnl_dereference(dev->mrp_port);
        unsigned int i;

        for (i = 0; i <= MRP_APPLICATION_MAX; i++) {
                if (rtnl_dereference(port->applicants[i]))
                        return;
        }
        RCU_INIT_POINTER(dev->mrp_port, NULL);
        kfree_rcu(port, rcu);
}

int mrp_init_applicant(struct net_device *dev, struct mrp_application *appl)
{
        struct mrp_applicant *app;
        int err;

        ASSERT_RTNL();

        if (!rtnl_dereference(dev->mrp_port)) {
                err = mrp_init_port(dev);
                if (err < 0)
                        goto err1;
        }

        err = -ENOMEM;
        app = kzalloc_obj(*app);
        if (!app)
                goto err2;

        err = dev_mc_add(dev, appl->group_address);
        if (err < 0)
                goto err3;

        app->dev = dev;
        app->app = appl;
        app->mad = RB_ROOT;
        app->active = true;
        spin_lock_init(&app->lock);
        skb_queue_head_init(&app->queue);
        rcu_assign_pointer(dev->mrp_port->applicants[appl->type], app);
        timer_setup(&app->join_timer, mrp_join_timer, 0);
        mrp_join_timer_arm(app);
        timer_setup(&app->periodic_timer, mrp_periodic_timer, 0);
        mrp_periodic_timer_arm(app);
        return 0;

err3:
        kfree(app);
err2:
        mrp_release_port(dev);
err1:
        return err;
}
EXPORT_SYMBOL_GPL(mrp_init_applicant);

void mrp_uninit_applicant(struct net_device *dev, struct mrp_application *appl)
{
        struct mrp_port *port = rtnl_dereference(dev->mrp_port);
        struct mrp_applicant *app = rtnl_dereference(
                port->applicants[appl->type]);

        ASSERT_RTNL();

        RCU_INIT_POINTER(port->applicants[appl->type], NULL);

        spin_lock_bh(&app->lock);
        app->active = false;
        spin_unlock_bh(&app->lock);
        /* Delete timer and generate a final TX event to flush out
         * all pending messages before the applicant is gone.
         */
        timer_shutdown_sync(&app->join_timer);
        timer_shutdown_sync(&app->periodic_timer);

        spin_lock_bh(&app->lock);
        mrp_mad_event(app, MRP_EVENT_TX);
        mrp_attr_destroy_all(app);
        mrp_pdu_queue(app);
        spin_unlock_bh(&app->lock);

        mrp_queue_xmit(app);

        dev_mc_del(dev, appl->group_address);
        kfree_rcu(app, rcu);
        mrp_release_port(dev);
}
EXPORT_SYMBOL_GPL(mrp_uninit_applicant);

int mrp_register_application(struct mrp_application *appl)
{
        appl->pkttype.func = mrp_rcv;
        dev_add_pack(&appl->pkttype);
        return 0;
}
EXPORT_SYMBOL_GPL(mrp_register_application);

void mrp_unregister_application(struct mrp_application *appl)
{
        dev_remove_pack(&appl->pkttype);
}
EXPORT_SYMBOL_GPL(mrp_unregister_application);