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 2008/10/15 03:27:33 james26_jang 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
25static 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
59static __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
68static __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 */
74void 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 */
119void 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
133static unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
134
135/* called under bridge lock */
136void 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}
194