net/bridge/br_stp_bpdu.c

   1 /*
   2  *      Spanning tree protocol; BPDU handling
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *
   8  *      $Id: br_stp_bpdu.c,v 1.1.1.1 2005/04/11 02:51:12 jack Exp $
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of the GNU General Public License
  12  *      as published by the Free Software Foundation; either version
  13  *      2 of the License, or (at your option) any later version.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/if_ether.h>
  18 #include <linux/if_bridge.h>
  19 #include "br_private.h"
  20 #include "br_private_stp.h"
  21
  22 #define JIFFIES_TO_TICKS(j) (((j) << 8) / HZ)
  23 #define TICKS_TO_JIFFIES(j) (((j) * HZ) >> 8)
  24
  25 static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)
  26 {
  27         struct net_device *dev;
  28         struct sk_buff *skb;
  29         int size;
  30
  31         if (!p->br->stp_enabled)
  32                 return;
  33
  34         size = length + 2*ETH_ALEN + 2;
  35         if (size < 60)
  36                 size = 60;
  37
  38         dev = p->dev;
  39
  40         if ((skb = dev_alloc_skb(size)) == NULL) {
  41                 printk(KERN_INFO "br: memory squeeze!\n");
  42                 return;
  43         }
  44
  45         skb->dev = dev;
  46         skb->protocol = htons(ETH_P_802_2);
  47         skb->mac.raw = skb_put(skb, size);
  48         memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
  49         memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
  50         skb->mac.raw[2*ETH_ALEN] = 0;
  51         skb->mac.raw[2*ETH_ALEN+1] = length;
  52         skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
  53         memcpy(skb->nh.raw, data, length);
  54         memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);
  55
  56         dev_queue_xmit(skb);
  57 }
  58
  59 static __inline__ void br_set_ticks(unsigned char *dest, int jiff)
  60 {
  61         __u16 ticks;
  62
  63         ticks = JIFFIES_TO_TICKS(jiff);
  64         dest[0] = (ticks >> 8) & 0xFF;
  65         dest[1] = ticks & 0xFF;
  66 }
  67
  68 static __inline__ int br_get_ticks(unsigned char *dest)
  69 {
  70         return TICKS_TO_JIFFIES((dest[0] << 8) | dest[1]);
  71 }
  72
  73 /* called under bridge lock */
  74 void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
  75 {
  76         unsigned char buf[38];
  77
  78         buf[0] = 0x42;
  79         buf[1] = 0x42;
  80         buf[2] = 0x03;
  81         buf[3] = 0;
  82         buf[4] = 0;
  83         buf[5] = 0;
  84         buf[6] = BPDU_TYPE_CONFIG;
  85         buf[7] = (bpdu->topology_change ? 0x01 : 0) |
  86                 (bpdu->topology_change_ack ? 0x80 : 0);
  87         buf[8] = bpdu->root.prio[0];
  88         buf[9] = bpdu->root.prio[1];
  89         buf[10] = bpdu->root.addr[0];
  90         buf[11] = bpdu->root.addr[1];
  91         buf[12] = bpdu->root.addr[2];
  92         buf[13] = bpdu->root.addr[3];
  93         buf[14] = bpdu->root.addr[4];
  94         buf[15] = bpdu->root.addr[5];
  95         buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
  96         buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
  97         buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
  98         buf[19] = bpdu->root_path_cost & 0xFF;
  99         buf[20] = bpdu->bridge_id.prio[0];
 100         buf[21] = bpdu->bridge_id.prio[1];
 101         buf[22] = bpdu->bridge_id.addr[0];
 102         buf[23] = bpdu->bridge_id.addr[1];
 103         buf[24] = bpdu->bridge_id.addr[2];
 104         buf[25] = bpdu->bridge_id.addr[3];
 105         buf[26] = bpdu->bridge_id.addr[4];
 106         buf[27] = bpdu->bridge_id.addr[5];
 107         buf[28] = (bpdu->port_id >> 8) & 0xFF;
 108         buf[29] = bpdu->port_id & 0xFF;
 109
 110         br_set_ticks(buf+30, bpdu->message_age);
 111         br_set_ticks(buf+32, bpdu->max_age);
 112         br_set_ticks(buf+34, bpdu->hello_time);
 113         br_set_ticks(buf+36, bpdu->forward_delay);
 114
 115         br_send_bpdu(p, buf, 38);
 116 }
 117
 118 /* called under bridge lock */
 119 void br_send_tcn_bpdu(struct net_bridge_port *p)
 120 {
 121         unsigned char buf[7];
 122
 123         buf[0] = 0x42;
 124         buf[1] = 0x42;
 125         buf[2] = 0x03;
 126         buf[3] = 0;
 127         buf[4] = 0;
 128         buf[5] = 0;
 129         buf[6] = BPDU_TYPE_TCN;
 130         br_send_bpdu(p, buf, 7);
 131 }
 132
 133 static unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
 134
 135 /* called under bridge lock */
 136 void br_stp_handle_bpdu(struct sk_buff *skb)
 137 {
 138         unsigned char *buf;
 139         struct net_bridge_port *p;
 140
 141         buf = skb->mac.raw + 14;
 142         p = skb->dev->br_port;
 143         if (!p->br->stp_enabled || memcmp(buf, header, 6)) {
 144                 kfree_skb(skb);
 145                 return;
 146         }
 147
 148         if (buf[6] == BPDU_TYPE_CONFIG) {
 149                 struct br_config_bpdu bpdu;
 150
 151                 bpdu.topology_change = (buf[7] & 0x01) ? 1 : 0;
 152                 bpdu.topology_change_ack = (buf[7] & 0x80) ? 1 : 0;
 153                 bpdu.root.prio[0] = buf[8];
 154                 bpdu.root.prio[1] = buf[9];
 155                 bpdu.root.addr[0] = buf[10];
 156                 bpdu.root.addr[1] = buf[11];
 157                 bpdu.root.addr[2] = buf[12];
 158                 bpdu.root.addr[3] = buf[13];
 159                 bpdu.root.addr[4] = buf[14];
 160                 bpdu.root.addr[5] = buf[15];
 161                 bpdu.root_path_cost =
 162                         (buf[16] << 24) |
 163                         (buf[17] << 16) |
 164                         (buf[18] << 8) |
 165                         buf[19];
 166                 bpdu.bridge_id.prio[0] = buf[20];
 167                 bpdu.bridge_id.prio[1] = buf[21];
 168                 bpdu.bridge_id.addr[0] = buf[22];
 169                 bpdu.bridge_id.addr[1] = buf[23];
 170                 bpdu.bridge_id.addr[2] = buf[24];
 171                 bpdu.bridge_id.addr[3] = buf[25];
 172                 bpdu.bridge_id.addr[4] = buf[26];
 173                 bpdu.bridge_id.addr[5] = buf[27];
 174                 bpdu.port_id = (buf[28] << 8) | buf[29];
 175
 176                 bpdu.message_age = br_get_ticks(buf+30);
 177                 bpdu.max_age = br_get_ticks(buf+32);
 178                 bpdu.hello_time = br_get_ticks(buf+34);
 179                 bpdu.forward_delay = br_get_ticks(buf+36);
 180
 181                 kfree_skb(skb);
 182                 br_received_config_bpdu(p, &bpdu);
 183                 return;
 184         }
 185
 186         if (buf[6] == BPDU_TYPE_TCN) {
 187                 br_received_tcn_bpdu(p);
 188                 kfree_skb(skb);
 189                 return;
 190         }
 191
 192         kfree_skb(skb);
 193 }