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/*

 *      Spanning tree protocol; BPDU handling

 *      Linux ethernet bridge

 *

 *      Authors:

 *      Lennert Buytenhek               <buytenh@gnu.org>

 *

 *      $Id: br_stp_bpdu.c,v 1.1.1.1 2004-04-15 01:16:27 phoenix Exp $

 *

 *      This program is free software; you can redistribute it and/or

 *      modify it under the terms of the GNU General Public License

 *      as published by the Free Software Foundation; either version

 *      2 of the License, or (at your option) any later version.

 */

#include <linux/kernel.h>

#include <linux/if_ether.h>

#include <linux/if_bridge.h>

#include <linux/netfilter_bridge.h>

#include "br_private.h"

#include "br_private_stp.h"

#define JIFFIES_TO_TICKS(j) (((j) << 8) / HZ)

#define TICKS_TO_JIFFIES(j) (((j) * HZ) >> 8)

static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)

{

        struct net_device *dev;

        struct sk_buff *skb;

        int size;

        if (!p->br->stp_enabled)

                return;

        size = length + 2*ETH_ALEN + 2;

        if (size < 60)

                size = 60;

        dev = p->dev;

        if ((skb = dev_alloc_skb(size)) == NULL) {

                printk(KERN_INFO "br: memory squeeze!\n");

                return;

        }

        skb->dev = dev;

        skb->protocol = htons(ETH_P_802_2);

        skb->mac.raw = skb_put(skb, size);

        memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);

        memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);

        skb->mac.raw[2*ETH_ALEN] = 0;

        skb->mac.raw[2*ETH_ALEN+1] = length;

        skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;

        memcpy(skb->nh.raw, data, length);

        memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);

        NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,

                dev_queue_xmit);

}

static __inline__ void br_set_ticks(unsigned char *dest, int jiff)

{

        __u16 ticks;

        ticks = JIFFIES_TO_TICKS(jiff);

        dest[0] = (ticks >> 8) & 0xFF;

        dest[1] = ticks & 0xFF;

}

static __inline__ int br_get_ticks(unsigned char *dest)

{

        return TICKS_TO_JIFFIES((dest[0] << 8) | dest[1]);

}

/* called under bridge lock */

void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)

{

        unsigned char buf[38];

        buf[0] = 0x42;

        buf[1] = 0x42;

        buf[2] = 0x03;

        buf[3] = 0;

        buf[4] = 0;

        buf[5] = 0;

        buf[6] = BPDU_TYPE_CONFIG;

        buf[7] = (bpdu->topology_change ? 0x01 : 0) |

                (bpdu->topology_change_ack ? 0x80 : 0);

        buf[8] = bpdu->root.prio[0];

        buf[9] = bpdu->root.prio[1];

        buf[10] = bpdu->root.addr[0];

        buf[11] = bpdu->root.addr[1];

        buf[12] = bpdu->root.addr[2];

        buf[13] = bpdu->root.addr[3];

        buf[14] = bpdu->root.addr[4];

        buf[15] = bpdu->root.addr[5];

        buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;

        buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;

        buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;

        buf[19] = bpdu->root_path_cost & 0xFF;

        buf[20] = bpdu->bridge_id.prio[0];

        buf[21] = bpdu->bridge_id.prio[1];

        buf[22] = bpdu->bridge_id.addr[0];

        buf[23] = bpdu->bridge_id.addr[1];

        buf[24] = bpdu->bridge_id.addr[2];

        buf[25] = bpdu->bridge_id.addr[3];

        buf[26] = bpdu->bridge_id.addr[4];

        buf[27] = bpdu->bridge_id.addr[5];

        buf[28] = (bpdu->port_id >> 8) & 0xFF;

        buf[29] = bpdu->port_id & 0xFF;

        br_set_ticks(buf+30, bpdu->message_age);

        br_set_ticks(buf+32, bpdu->max_age);

        br_set_ticks(buf+34, bpdu->hello_time);

        br_set_ticks(buf+36, bpdu->forward_delay);

        br_send_bpdu(p, buf, 38);

}

/* called under bridge lock */

void br_send_tcn_bpdu(struct net_bridge_port *p)

{

        unsigned char buf[7];

        buf[0] = 0x42;

        buf[1] = 0x42;

        buf[2] = 0x03;

        buf[3] = 0;

        buf[4] = 0;

        buf[5] = 0;

        buf[6] = BPDU_TYPE_TCN;

        br_send_bpdu(p, buf, 7);

}

static unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};

/* called under bridge lock */

int br_stp_handle_bpdu(struct sk_buff *skb)

{

        unsigned char *buf;

        struct net_bridge_port *p;

        p = skb->dev->br_port;

        if (!p->br->stp_enabled ||

            !pskb_may_pull(skb, sizeof(header)+1) ||

            memcmp(skb->data, header, sizeof(header)))

                goto err;

        buf = skb_pull(skb, sizeof(header));

        if (buf[0] == BPDU_TYPE_CONFIG) {

                struct br_config_bpdu bpdu;

                if (!pskb_may_pull(skb, 32))

                        goto err;

                buf = skb->data;

                bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;

                bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;

                bpdu.root.prio[0] = buf[2];

                bpdu.root.prio[1] = buf[3];

                bpdu.root.addr[0] = buf[4];

                bpdu.root.addr[1] = buf[5];

                bpdu.root.addr[2] = buf[6];

                bpdu.root.addr[3] = buf[7];

                bpdu.root.addr[4] = buf[8];

                bpdu.root.addr[5] = buf[9];

                bpdu.root_path_cost =

                        (buf[10] << 24) |

                        (buf[11] << 16) |

                        (buf[12] << 8) |

                        buf[13];

                bpdu.bridge_id.prio[0] = buf[14];

                bpdu.bridge_id.prio[1] = buf[15];

                bpdu.bridge_id.addr[0] = buf[16];

                bpdu.bridge_id.addr[1] = buf[17];

                bpdu.bridge_id.addr[2] = buf[18];

                bpdu.bridge_id.addr[3] = buf[19];

                bpdu.bridge_id.addr[4] = buf[20];

                bpdu.bridge_id.addr[5] = buf[21];

                bpdu.port_id = (buf[22] << 8) | buf[23];

                bpdu.message_age = br_get_ticks(buf+24);

                bpdu.max_age = br_get_ticks(buf+26);

                bpdu.hello_time = br_get_ticks(buf+28);

                bpdu.forward_delay = br_get_ticks(buf+30);

                br_received_config_bpdu(p, &bpdu);

        }

        else if (buf[0] == BPDU_TYPE_TCN) {

                br_received_tcn_bpdu(p);

        }

 err:

        kfree_skb(skb);

        return 0;

}