2 * Spanning tree protocol; BPDU handling
3 * Linux ethernet bridge
6 * Lennert Buytenhek <buytenh@gnu.org>
8 * $Id: br_stp_bpdu.c,v 1.3 2001/11/10 02:35:25 davem Exp $
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.
16 #include <linux/kernel.h>
17 #include <linux/netfilter_bridge.h>
18 #include <linux/etherdevice.h>
19 #include <linux/llc.h>
20 #include <net/llc_pdu.h>
22 #include "br_private.h"
23 #include "br_private_stp.h"
27 static void br_send_bpdu(struct net_bridge_port
*p
, unsigned char *data
, int length
)
29 struct net_device
*dev
;
33 if (!p
->br
->stp_enabled
)
36 size
= length
+ 2*ETH_ALEN
+ 2;
42 if ((skb
= dev_alloc_skb(size
)) == NULL
) {
43 printk(KERN_INFO
"br: memory squeeze!\n");
48 skb
->protocol
= htons(ETH_P_802_2
);
49 skb
->mac
.raw
= skb_put(skb
, size
);
50 memcpy(skb
->mac
.raw
, p
->br
->group_addr
, ETH_ALEN
);
51 memcpy(skb
->mac
.raw
+ETH_ALEN
, dev
->dev_addr
, ETH_ALEN
);
52 skb
->mac
.raw
[2*ETH_ALEN
] = 0;
53 skb
->mac
.raw
[2*ETH_ALEN
+1] = length
;
54 skb
->nh
.raw
= skb
->mac
.raw
+ 2*ETH_ALEN
+ 2;
55 memcpy(skb
->nh
.raw
, data
, length
);
56 memset(skb
->nh
.raw
+ length
, 0xa5, size
- length
- 2*ETH_ALEN
- 2);
58 NF_HOOK(PF_BRIDGE
, NF_BR_LOCAL_OUT
, skb
, NULL
, skb
->dev
,
62 static inline void br_set_ticks(unsigned char *dest
, int j
)
64 unsigned long ticks
= (STP_HZ
* j
)/ HZ
;
66 *((__be16
*) dest
) = htons(ticks
);
69 static inline int br_get_ticks(const unsigned char *src
)
71 unsigned long ticks
= ntohs(*(__be16
*)src
);
73 return (ticks
* HZ
+ STP_HZ
- 1) / STP_HZ
;
76 /* called under bridge lock */
77 void br_send_config_bpdu(struct net_bridge_port
*p
, struct br_config_bpdu
*bpdu
)
79 unsigned char buf
[38];
87 buf
[6] = BPDU_TYPE_CONFIG
;
88 buf
[7] = (bpdu
->topology_change
? 0x01 : 0) |
89 (bpdu
->topology_change_ack
? 0x80 : 0);
90 buf
[8] = bpdu
->root
.prio
[0];
91 buf
[9] = bpdu
->root
.prio
[1];
92 buf
[10] = bpdu
->root
.addr
[0];
93 buf
[11] = bpdu
->root
.addr
[1];
94 buf
[12] = bpdu
->root
.addr
[2];
95 buf
[13] = bpdu
->root
.addr
[3];
96 buf
[14] = bpdu
->root
.addr
[4];
97 buf
[15] = bpdu
->root
.addr
[5];
98 buf
[16] = (bpdu
->root_path_cost
>> 24) & 0xFF;
99 buf
[17] = (bpdu
->root_path_cost
>> 16) & 0xFF;
100 buf
[18] = (bpdu
->root_path_cost
>> 8) & 0xFF;
101 buf
[19] = bpdu
->root_path_cost
& 0xFF;
102 buf
[20] = bpdu
->bridge_id
.prio
[0];
103 buf
[21] = bpdu
->bridge_id
.prio
[1];
104 buf
[22] = bpdu
->bridge_id
.addr
[0];
105 buf
[23] = bpdu
->bridge_id
.addr
[1];
106 buf
[24] = bpdu
->bridge_id
.addr
[2];
107 buf
[25] = bpdu
->bridge_id
.addr
[3];
108 buf
[26] = bpdu
->bridge_id
.addr
[4];
109 buf
[27] = bpdu
->bridge_id
.addr
[5];
110 buf
[28] = (bpdu
->port_id
>> 8) & 0xFF;
111 buf
[29] = bpdu
->port_id
& 0xFF;
113 br_set_ticks(buf
+30, bpdu
->message_age
);
114 br_set_ticks(buf
+32, bpdu
->max_age
);
115 br_set_ticks(buf
+34, bpdu
->hello_time
);
116 br_set_ticks(buf
+36, bpdu
->forward_delay
);
118 br_send_bpdu(p
, buf
, 38);
121 /* called under bridge lock */
122 void br_send_tcn_bpdu(struct net_bridge_port
*p
)
124 unsigned char buf
[7];
132 buf
[6] = BPDU_TYPE_TCN
;
133 br_send_bpdu(p
, buf
, 7);
139 * NO locks, but rcu_read_lock (preempt_disabled)
141 int br_stp_rcv(struct sk_buff
*skb
, struct net_device
*dev
,
142 struct packet_type
*pt
, struct net_device
*orig_dev
)
144 const struct llc_pdu_un
*pdu
= llc_pdu_un_hdr(skb
);
145 const unsigned char *dest
= eth_hdr(skb
)->h_dest
;
146 struct net_bridge_port
*p
= rcu_dereference(dev
->br_port
);
147 struct net_bridge
*br
;
148 const unsigned char *buf
;
153 if (pdu
->ssap
!= LLC_SAP_BSPAN
154 || pdu
->dsap
!= LLC_SAP_BSPAN
155 || pdu
->ctrl_1
!= LLC_PDU_TYPE_U
)
158 if (!pskb_may_pull(skb
, 4))
161 /* compare of protocol id and version */
163 if (buf
[0] != 0 || buf
[1] != 0 || buf
[2] != 0)
167 spin_lock(&br
->lock
);
169 if (p
->state
== BR_STATE_DISABLED
171 || !(br
->dev
->flags
& IFF_UP
))
174 if (compare_ether_addr(dest
, br
->group_addr
) != 0)
177 buf
= skb_pull(skb
, 3);
179 if (buf
[0] == BPDU_TYPE_CONFIG
) {
180 struct br_config_bpdu bpdu
;
182 if (!pskb_may_pull(skb
, 32))
186 bpdu
.topology_change
= (buf
[1] & 0x01) ? 1 : 0;
187 bpdu
.topology_change_ack
= (buf
[1] & 0x80) ? 1 : 0;
189 bpdu
.root
.prio
[0] = buf
[2];
190 bpdu
.root
.prio
[1] = buf
[3];
191 bpdu
.root
.addr
[0] = buf
[4];
192 bpdu
.root
.addr
[1] = buf
[5];
193 bpdu
.root
.addr
[2] = buf
[6];
194 bpdu
.root
.addr
[3] = buf
[7];
195 bpdu
.root
.addr
[4] = buf
[8];
196 bpdu
.root
.addr
[5] = buf
[9];
197 bpdu
.root_path_cost
=
202 bpdu
.bridge_id
.prio
[0] = buf
[14];
203 bpdu
.bridge_id
.prio
[1] = buf
[15];
204 bpdu
.bridge_id
.addr
[0] = buf
[16];
205 bpdu
.bridge_id
.addr
[1] = buf
[17];
206 bpdu
.bridge_id
.addr
[2] = buf
[18];
207 bpdu
.bridge_id
.addr
[3] = buf
[19];
208 bpdu
.bridge_id
.addr
[4] = buf
[20];
209 bpdu
.bridge_id
.addr
[5] = buf
[21];
210 bpdu
.port_id
= (buf
[22] << 8) | buf
[23];
212 bpdu
.message_age
= br_get_ticks(buf
+24);
213 bpdu
.max_age
= br_get_ticks(buf
+26);
214 bpdu
.hello_time
= br_get_ticks(buf
+28);
215 bpdu
.forward_delay
= br_get_ticks(buf
+30);
217 br_received_config_bpdu(p
, &bpdu
);
220 else if (buf
[0] == BPDU_TYPE_TCN
) {
221 br_received_tcn_bpdu(p
);
224 spin_unlock(&br
->lock
);
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