net: Add GARP applicant-only participant
authorPatrick McHardy <kaber@trash.net>
Sun, 6 Jul 2008 04:26:13 +0000 (21:26 -0700)
committerDavid S. Miller <davem@davemloft.net>
Sun, 6 Jul 2008 04:26:13 +0000 (21:26 -0700)
Add an implementation of the GARP (Generic Attribute Registration Protocol)
applicant-only participant. This will be used by the following patch to
add GVRP support to the VLAN code.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/linux/netdevice.h
include/net/garp.h [new file with mode: 0644]
net/802/Kconfig
net/802/Makefile
net/802/garp.c [new file with mode: 0644]

index 56dadb528f6737fcd5f111c100f875288f6b4f0c..e009c6fbf5cdf795bc60760bc39a5c135f248285 100644 (file)
@@ -740,6 +740,8 @@ struct net_device
        struct net_bridge_port  *br_port;
        /* macvlan */
        struct macvlan_port     *macvlan_port;
+       /* GARP */
+       struct garp_port        *garp_port;
 
        /* class/net/name entry */
        struct device           dev;
diff --git a/include/net/garp.h b/include/net/garp.h
new file mode 100644 (file)
index 0000000..73c7723
--- /dev/null
@@ -0,0 +1,127 @@
+#ifndef _NET_GARP_H
+#define _NET_GARP_H
+
+#include <net/stp.h>
+
+#define GARP_PROTOCOL_ID       0x1
+#define GARP_END_MARK          0x0
+
+struct garp_pdu_hdr {
+       __be16  protocol;
+};
+
+struct garp_msg_hdr {
+       u8      attrtype;
+};
+
+enum garp_attr_event {
+       GARP_LEAVE_ALL,
+       GARP_JOIN_EMPTY,
+       GARP_JOIN_IN,
+       GARP_LEAVE_EMPTY,
+       GARP_LEAVE_IN,
+       GARP_EMPTY,
+};
+
+struct garp_attr_hdr {
+       u8      len;
+       u8      event;
+       u8      data[];
+};
+
+struct garp_skb_cb {
+       u8      cur_type;
+};
+
+static inline struct garp_skb_cb *garp_cb(struct sk_buff *skb)
+{
+       BUILD_BUG_ON(sizeof(struct garp_skb_cb) >
+                    FIELD_SIZEOF(struct sk_buff, cb));
+       return (struct garp_skb_cb *)skb->cb;
+}
+
+enum garp_applicant_state {
+       GARP_APPLICANT_INVALID,
+       GARP_APPLICANT_VA,
+       GARP_APPLICANT_AA,
+       GARP_APPLICANT_QA,
+       GARP_APPLICANT_LA,
+       GARP_APPLICANT_VP,
+       GARP_APPLICANT_AP,
+       GARP_APPLICANT_QP,
+       GARP_APPLICANT_VO,
+       GARP_APPLICANT_AO,
+       GARP_APPLICANT_QO,
+       __GARP_APPLICANT_MAX
+};
+#define GARP_APPLICANT_MAX     (__GARP_APPLICANT_MAX - 1)
+
+enum garp_event {
+       GARP_EVENT_REQ_JOIN,
+       GARP_EVENT_REQ_LEAVE,
+       GARP_EVENT_R_JOIN_IN,
+       GARP_EVENT_R_JOIN_EMPTY,
+       GARP_EVENT_R_EMPTY,
+       GARP_EVENT_R_LEAVE_IN,
+       GARP_EVENT_R_LEAVE_EMPTY,
+       GARP_EVENT_TRANSMIT_PDU,
+       __GARP_EVENT_MAX
+};
+#define GARP_EVENT_MAX         (__GARP_EVENT_MAX - 1)
+
+enum garp_action {
+       GARP_ACTION_NONE,
+       GARP_ACTION_S_JOIN_IN,
+       GARP_ACTION_S_LEAVE_EMPTY,
+};
+
+struct garp_attr {
+       struct rb_node                  node;
+       enum garp_applicant_state       state;
+       u8                              type;
+       u8                              dlen;
+       unsigned char                   data[];
+};
+
+enum garp_applications {
+       __GARP_APPLICATION_MAX
+};
+#define GARP_APPLICATION_MAX   (__GARP_APPLICATION_MAX - 1)
+
+struct garp_application {
+       enum garp_applications  type;
+       unsigned int            maxattr;
+       struct stp_proto        proto;
+};
+
+struct garp_applicant {
+       struct garp_application *app;
+       struct net_device       *dev;
+       struct timer_list       join_timer;
+
+       spinlock_t              lock;
+       struct sk_buff_head     queue;
+       struct sk_buff          *pdu;
+       struct rb_root          gid;
+};
+
+struct garp_port {
+       struct garp_applicant   *applicants[GARP_APPLICATION_MAX + 1];
+};
+
+extern int     garp_register_application(struct garp_application *app);
+extern void    garp_unregister_application(struct garp_application *app);
+
+extern int     garp_init_applicant(struct net_device *dev,
+                                   struct garp_application *app);
+extern void    garp_uninit_applicant(struct net_device *dev,
+                                     struct garp_application *app);
+
+extern int     garp_request_join(const struct net_device *dev,
+                                 const struct garp_application *app,
+                                 const void *data, u8 len, u8 type);
+extern void    garp_request_leave(const struct net_device *dev,
+                                  const struct garp_application *app,
+                                  const void *data, u8 len, u8 type);
+
+#endif /* _NET_GARP_H */
index 01cb0943626b1a3c1a588f9d18a9aac61f678fff..be33d27c8e6993404d0f1c1f325312093e3a0776 100644 (file)
@@ -1,3 +1,7 @@
 config STP
        tristate
        select LLC
+
+config GARP
+       tristate
+       select STP
index c441d895ac256ff52c81bc1a567a2301e9b99358..7893d679910cdc1e98fc78f6995839a7e188c1d0 100644 (file)
@@ -11,3 +11,4 @@ obj-$(CONFIG_HIPPI)   +=                 hippi.o
 obj-$(CONFIG_IPX)      += p8022.o psnap.o p8023.o
 obj-$(CONFIG_ATALK)    += p8022.o psnap.o
 obj-$(CONFIG_STP)      += stp.o
+obj-$(CONFIG_GARP)     += garp.o
diff --git a/net/802/garp.c b/net/802/garp.c
new file mode 100644 (file)
index 0000000..3b78f7b
--- /dev/null
@@ -0,0 +1,633 @@
+/*
+ *     IEEE 802.1D Generic Attribute Registration Protocol (GARP)
+ *
+ *     Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
+ *
+ *     This program is free software; you can redistribute it and/or
+ *     modify it under the terms of the GNU General Public License
+ *     version 2 as published by the Free Software Foundation.
+ */
+#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/llc.h>
+#include <net/llc.h>
+#include <net/llc_pdu.h>
+#include <net/garp.h>
+#include <asm/unaligned.h>
+
+static unsigned int garp_join_time __read_mostly = 200;
+module_param(garp_join_time, uint, 0644);
+MODULE_PARM_DESC(garp_join_time, "Join time in ms (default 200ms)");
+MODULE_LICENSE("GPL");
+
+static const struct garp_state_trans {
+       u8      state;
+       u8      action;
+} garp_applicant_state_table[GARP_APPLICANT_MAX + 1][GARP_EVENT_MAX + 1] = {
+       [GARP_APPLICANT_VA] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_AA,
+                                                   .action = GARP_ACTION_S_JOIN_IN },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AA },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
+       },
+       [GARP_APPLICANT_AA] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_QA,
+                                                   .action = GARP_ACTION_S_JOIN_IN },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QA },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
+       },
+       [GARP_APPLICANT_QA] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QA },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_LA },
+       },
+       [GARP_APPLICANT_LA] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_VO,
+                                                   .action = GARP_ACTION_S_LEAVE_EMPTY },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_LA },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_LA },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_LA },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_VA },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
+       },
+       [GARP_APPLICANT_VP] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_AA,
+                                                   .action = GARP_ACTION_S_JOIN_IN },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AP },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_VO },
+       },
+       [GARP_APPLICANT_AP] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_QA,
+                                                   .action = GARP_ACTION_S_JOIN_IN },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QP },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_AO },
+       },
+       [GARP_APPLICANT_QP] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QP },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_QO },
+       },
+       [GARP_APPLICANT_VO] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_AO },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_VP },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
+       },
+       [GARP_APPLICANT_AO] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QO },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_AP },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
+       },
+       [GARP_APPLICANT_QO] = {
+               [GARP_EVENT_TRANSMIT_PDU]       = { .state = GARP_APPLICANT_INVALID },
+               [GARP_EVENT_R_JOIN_IN]          = { .state = GARP_APPLICANT_QO },
+               [GARP_EVENT_R_JOIN_EMPTY]       = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_EMPTY]            = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_LEAVE_IN]         = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_R_LEAVE_EMPTY]      = { .state = GARP_APPLICANT_VO },
+               [GARP_EVENT_REQ_JOIN]           = { .state = GARP_APPLICANT_QP },
+               [GARP_EVENT_REQ_LEAVE]          = { .state = GARP_APPLICANT_INVALID },
+       },
+};
+
+static int garp_attr_cmp(const struct garp_attr *attr,
+                        const void *data, u8 len, u8 type)
+{
+       if (attr->type != type)
+               return attr->type - type;
+       if (attr->dlen != len)
+               return attr->dlen - len;
+       return memcmp(attr->data, data, len);
+}
+
+static struct garp_attr *garp_attr_lookup(const struct garp_applicant *app,
+                                         const void *data, u8 len, u8 type)
+{
+       struct rb_node *parent = app->gid.rb_node;
+       struct garp_attr *attr;
+       int d;
+
+       while (parent) {
+               attr = rb_entry(parent, struct garp_attr, node);
+               d = garp_attr_cmp(attr, data, len, type);
+               if (d < 0)
+                       parent = parent->rb_left;
+               else if (d > 0)
+                       parent = parent->rb_right;
+               else
+                       return attr;
+       }
+       return NULL;
+}
+
+static void garp_attr_insert(struct garp_applicant *app, struct garp_attr *new)
+{
+       struct rb_node *parent = NULL, **p = &app->gid.rb_node;
+       struct garp_attr *attr;
+       int d;
+
+       while (*p) {
+               parent = *p;
+               attr = rb_entry(parent, struct garp_attr, node);
+               d = garp_attr_cmp(attr, new->data, new->dlen, new->type);
+               if (d < 0)
+                       p = &parent->rb_left;
+               else if (d > 0)
+                       p = &parent->rb_right;
+       }
+       rb_link_node(&new->node, parent, p);
+       rb_insert_color(&new->node, &app->gid);
+}
+
+static struct garp_attr *garp_attr_create(struct garp_applicant *app,
+                                         const void *data, u8 len, u8 type)
+{
+       struct garp_attr *attr;
+
+       attr = kmalloc(sizeof(*attr) + len, GFP_ATOMIC);
+       if (!attr)
+               return attr;
+       attr->state = GARP_APPLICANT_VO;
+       attr->type  = type;
+       attr->dlen  = len;
+       memcpy(attr->data, data, len);
+       garp_attr_insert(app, attr);
+       return attr;
+}
+
+static void garp_attr_destroy(struct garp_applicant *app, struct garp_attr *attr)
+{
+       rb_erase(&attr->node, &app->gid);
+       kfree(attr);
+}
+
+static int garp_pdu_init(struct garp_applicant *app)
+{
+       struct sk_buff *skb;
+       struct garp_pdu_hdr *gp;
+
+#define LLC_RESERVE    sizeof(struct llc_pdu_un)
+       skb = alloc_skb(app->dev->mtu + LL_RESERVED_SPACE(app->dev),
+                       GFP_ATOMIC);
+       if (!skb)
+               return -ENOMEM;
+
+       skb->dev = app->dev;
+       skb->protocol = htons(ETH_P_802_2);
+       skb_reserve(skb, LL_RESERVED_SPACE(app->dev) + LLC_RESERVE);
+
+       gp = (struct garp_pdu_hdr *)__skb_put(skb, sizeof(*gp));
+       put_unaligned(htons(GARP_PROTOCOL_ID), &gp->protocol);
+
+       app->pdu = skb;
+       return 0;
+}
+
+static int garp_pdu_append_end_mark(struct garp_applicant *app)
+{
+       if (skb_tailroom(app->pdu) < sizeof(u8))
+               return -1;
+       *(u8 *)__skb_put(app->pdu, sizeof(u8)) = GARP_END_MARK;
+       return 0;
+}
+
+static void garp_pdu_queue(struct garp_applicant *app)
+{
+       if (!app->pdu)
+               return;
+
+       garp_pdu_append_end_mark(app);
+       garp_pdu_append_end_mark(app);
+
+       llc_pdu_header_init(app->pdu, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
+                           LLC_SAP_BSPAN, LLC_PDU_CMD);
+       llc_pdu_init_as_ui_cmd(app->pdu);
+       llc_mac_hdr_init(app->pdu, app->dev->dev_addr,
+                        app->app->proto.group_address);
+
+       skb_queue_tail(&app->queue, app->pdu);
+       app->pdu = NULL;
+}
+
+static void garp_queue_xmit(struct garp_applicant *app)
+{
+       struct sk_buff *skb;
+
+       while ((skb = skb_dequeue(&app->queue)))
+               dev_queue_xmit(skb);
+}
+
+static int garp_pdu_append_msg(struct garp_applicant *app, u8 attrtype)
+{
+       struct garp_msg_hdr *gm;
+
+       if (skb_tailroom(app->pdu) < sizeof(*gm))
+               return -1;
+       gm = (struct garp_msg_hdr *)__skb_put(app->pdu, sizeof(*gm));
+       gm->attrtype = attrtype;
+       garp_cb(app->pdu)->cur_type = attrtype;
+       return 0;
+}
+
+static int garp_pdu_append_attr(struct garp_applicant *app,
+                               const struct garp_attr *attr,
+                               enum garp_attr_event event)
+{
+       struct garp_attr_hdr *ga;
+       unsigned int len;
+       int err;
+again:
+       if (!app->pdu) {
+               err = garp_pdu_init(app);
+               if (err < 0)
+                       return err;
+       }
+
+       if (garp_cb(app->pdu)->cur_type != attr->type) {
+               if (garp_cb(app->pdu)->cur_type &&
+                   garp_pdu_append_end_mark(app) < 0)
+                       goto queue;
+               if (garp_pdu_append_msg(app, attr->type) < 0)
+                       goto queue;
+       }
+
+       len = sizeof(*ga) + attr->dlen;
+       if (skb_tailroom(app->pdu) < len)
+               goto queue;
+       ga = (struct garp_attr_hdr *)__skb_put(app->pdu, len);
+       ga->len   = len;
+       ga->event = event;
+       memcpy(ga->data, attr->data, attr->dlen);
+       return 0;
+
+queue:
+       garp_pdu_queue(app);
+       goto again;
+}
+
+static void garp_attr_event(struct garp_applicant *app,
+                           struct garp_attr *attr, enum garp_event event)
+{
+       enum garp_applicant_state state;
+
+       state = garp_applicant_state_table[attr->state][event].state;
+       if (state == GARP_APPLICANT_INVALID)
+               return;
+
+       switch (garp_applicant_state_table[attr->state][event].action) {
+       case GARP_ACTION_NONE:
+               break;
+       case GARP_ACTION_S_JOIN_IN:
+               garp_pdu_append_attr(app, attr, GARP_JOIN_IN);
+               break;
+       case GARP_ACTION_S_LEAVE_EMPTY:
+               garp_pdu_append_attr(app, attr, GARP_LEAVE_EMPTY);
+               /* As a pure applicant, sending a leave message implies that
+                * the attribute was unregistered and can be destroyed. */
+               garp_attr_destroy(app, attr);
+               return;
+       default:
+               WARN_ON(1);
+       }
+
+       attr->state = state;
+}
+
+int garp_request_join(const struct net_device *dev,
+                     const struct garp_application *appl,
+                     const void *data, u8 len, u8 type)
+{
+       struct garp_port *port = dev->garp_port;
+       struct garp_applicant *app = port->applicants[appl->type];
+       struct garp_attr *attr;
+
+       spin_lock_bh(&app->lock);
+       attr = garp_attr_create(app, data, len, type);
+       if (!attr) {
+               spin_unlock_bh(&app->lock);
+               return -ENOMEM;
+       }
+       garp_attr_event(app, attr, GARP_EVENT_REQ_JOIN);
+       spin_unlock_bh(&app->lock);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(garp_request_join);
+
+void garp_request_leave(const struct net_device *dev,
+                       const struct garp_application *appl,
+                       const void *data, u8 len, u8 type)
+{
+       struct garp_port *port = dev->garp_port;
+       struct garp_applicant *app = port->applicants[appl->type];
+       struct garp_attr *attr;
+
+       spin_lock_bh(&app->lock);
+       attr = garp_attr_lookup(app, data, len, type);
+       if (!attr) {
+               spin_unlock_bh(&app->lock);
+               return;
+       }
+       garp_attr_event(app, attr, GARP_EVENT_REQ_LEAVE);
+       spin_unlock_bh(&app->lock);
+}
+EXPORT_SYMBOL_GPL(garp_request_leave);
+
+static void garp_gid_event(struct garp_applicant *app, enum garp_event event)
+{
+       struct rb_node *node, *next;
+       struct garp_attr *attr;
+
+       for (node = rb_first(&app->gid);
+            next = node ? rb_next(node) : NULL, node != NULL;
+            node = next) {
+               attr = rb_entry(node, struct garp_attr, node);
+               garp_attr_event(app, attr, event);
+       }
+}
+
+static void garp_join_timer_arm(struct garp_applicant *app)
+{
+       unsigned long delay;
+
+       delay = (u64)msecs_to_jiffies(garp_join_time) * net_random() >> 32;
+       mod_timer(&app->join_timer, jiffies + delay);
+}
+
+static void garp_join_timer(unsigned long data)
+{
+       struct garp_applicant *app = (struct garp_applicant *)data;
+
+       spin_lock(&app->lock);
+       garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
+       garp_pdu_queue(app);
+       spin_unlock(&app->lock);
+
+       garp_queue_xmit(app);
+       garp_join_timer_arm(app);
+}
+
+static int garp_pdu_parse_end_mark(struct sk_buff *skb)
+{
+       if (!pskb_may_pull(skb, sizeof(u8)))
+               return -1;
+       if (*skb->data == GARP_END_MARK) {
+               skb_pull(skb, sizeof(u8));
+               return -1;
+       }
+       return 0;
+}
+
+static int garp_pdu_parse_attr(struct garp_applicant *app, struct sk_buff *skb,
+                              u8 attrtype)
+{
+       const struct garp_attr_hdr *ga;
+       struct garp_attr *attr;
+       enum garp_event event;
+       unsigned int dlen;
+
+       if (!pskb_may_pull(skb, sizeof(*ga)))
+               return -1;
+       ga = (struct garp_attr_hdr *)skb->data;
+       if (ga->len < sizeof(*ga))
+               return -1;
+
+       if (!pskb_may_pull(skb, ga->len))
+               return -1;
+       skb_pull(skb, ga->len);
+       dlen = sizeof(*ga) - ga->len;
+
+       if (attrtype > app->app->maxattr)
+               return 0;
+
+       switch (ga->event) {
+       case GARP_LEAVE_ALL:
+               if (dlen != 0)
+                       return -1;
+               garp_gid_event(app, GARP_EVENT_R_LEAVE_EMPTY);
+               return 0;
+       case GARP_JOIN_EMPTY:
+               event = GARP_EVENT_R_JOIN_EMPTY;
+               break;
+       case GARP_JOIN_IN:
+               event = GARP_EVENT_R_JOIN_IN;
+               break;
+       case GARP_LEAVE_EMPTY:
+               event = GARP_EVENT_R_LEAVE_EMPTY;
+               break;
+       case GARP_EMPTY:
+               event = GARP_EVENT_R_EMPTY;
+               break;
+       default:
+               return 0;
+       }
+
+       if (dlen == 0)
+               return -1;
+       attr = garp_attr_lookup(app, ga->data, dlen, attrtype);
+       if (attr == NULL)
+               return 0;
+       garp_attr_event(app, attr, event);
+       return 0;
+}
+
+static int garp_pdu_parse_msg(struct garp_applicant *app, struct sk_buff *skb)
+{
+       const struct garp_msg_hdr *gm;
+
+       if (!pskb_may_pull(skb, sizeof(*gm)))
+               return -1;
+       gm = (struct garp_msg_hdr *)skb->data;
+       if (gm->attrtype == 0)
+               return -1;
+       skb_pull(skb, sizeof(*gm));
+
+       while (skb->len > 0) {
+               if (garp_pdu_parse_attr(app, skb, gm->attrtype) < 0)
+                       return -1;
+               if (garp_pdu_parse_end_mark(skb) < 0)
+                       break;
+       }
+       return 0;
+}
+
+static void garp_pdu_rcv(const struct stp_proto *proto, struct sk_buff *skb,
+                        struct net_device *dev)
+{
+       struct garp_application *appl = proto->data;
+       struct garp_port *port;
+       struct garp_applicant *app;
+       const struct garp_pdu_hdr *gp;
+
+       port = rcu_dereference(dev->garp_port);
+       if (!port)
+               goto err;
+       app = rcu_dereference(port->applicants[appl->type]);
+       if (!app)
+               goto err;
+
+       if (!pskb_may_pull(skb, sizeof(*gp)))
+               goto err;
+       gp = (struct garp_pdu_hdr *)skb->data;
+       if (get_unaligned(&gp->protocol) != htons(GARP_PROTOCOL_ID))
+               goto err;
+       skb_pull(skb, sizeof(*gp));
+
+       spin_lock(&app->lock);
+       while (skb->len > 0) {
+               if (garp_pdu_parse_msg(app, skb) < 0)
+                       break;
+               if (garp_pdu_parse_end_mark(skb) < 0)
+                       break;
+       }
+       spin_unlock(&app->lock);
+err:
+       kfree_skb(skb);
+}
+
+static int garp_init_port(struct net_device *dev)
+{
+       struct garp_port *port;
+
+       port = kzalloc(sizeof(*port), GFP_KERNEL);
+       if (!port)
+               return -ENOMEM;
+       rcu_assign_pointer(dev->garp_port, port);
+       return 0;
+}
+
+static void garp_release_port(struct net_device *dev)
+{
+       struct garp_port *port = dev->garp_port;
+       unsigned int i;
+
+       for (i = 0; i <= GARP_APPLICATION_MAX; i++) {
+               if (port->applicants[i])
+                       return;
+       }
+       rcu_assign_pointer(dev->garp_port, NULL);
+       synchronize_rcu();
+       kfree(port);
+}
+
+int garp_init_applicant(struct net_device *dev, struct garp_application *appl)
+{
+       struct garp_applicant *app;
+       int err;
+
+       ASSERT_RTNL();
+
+       if (!dev->garp_port) {
+               err = garp_init_port(dev);
+               if (err < 0)
+                       goto err1;
+       }
+
+       err = -ENOMEM;
+       app = kzalloc(sizeof(*app), GFP_KERNEL);
+       if (!app)
+               goto err2;
+
+       err = dev_mc_add(dev, appl->proto.group_address, ETH_ALEN, 0);
+       if (err < 0)
+               goto err3;
+
+       app->dev = dev;
+       app->app = appl;
+       app->gid = RB_ROOT;
+       spin_lock_init(&app->lock);
+       skb_queue_head_init(&app->queue);
+       rcu_assign_pointer(dev->garp_port->applicants[appl->type], app);
+       setup_timer(&app->join_timer, garp_join_timer, (unsigned long)app);
+       garp_join_timer_arm(app);
+       return 0;
+
+err3:
+       kfree(app);
+err2:
+       garp_release_port(dev);
+err1:
+       return err;
+}
+EXPORT_SYMBOL_GPL(garp_init_applicant);
+
+void garp_uninit_applicant(struct net_device *dev, struct garp_application *appl)
+{
+       struct garp_port *port = dev->garp_port;
+       struct garp_applicant *app = port->applicants[appl->type];
+
+       ASSERT_RTNL();
+
+       rcu_assign_pointer(port->applicants[appl->type], NULL);
+       synchronize_rcu();
+
+       /* Delete timer and generate a final TRANSMIT_PDU event to flush out
+        * all pending messages before the applicant is gone. */
+       del_timer_sync(&app->join_timer);
+       garp_gid_event(app, GARP_EVENT_TRANSMIT_PDU);
+       garp_pdu_queue(app);
+       garp_queue_xmit(app);
+
+       dev_mc_delete(dev, appl->proto.group_address, ETH_ALEN, 0);
+       kfree(app);
+       garp_release_port(dev);
+}
+EXPORT_SYMBOL_GPL(garp_uninit_applicant);
+
+int garp_register_application(struct garp_application *appl)
+{
+       appl->proto.rcv = garp_pdu_rcv;
+       appl->proto.data = appl;
+       return stp_proto_register(&appl->proto);
+}
+EXPORT_SYMBOL_GPL(garp_register_application);
+
+void garp_unregister_application(struct garp_application *appl)
+{
+       stp_proto_unregister(&appl->proto);
+}
+EXPORT_SYMBOL_GPL(garp_unregister_application);