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[linux-2.6] / net / bridge / br_forward.c
1 /*
2  *      Forwarding decision
3  *      Linux ethernet bridge
4  *
5  *      Authors:
6  *      Lennert Buytenhek               <buytenh@gnu.org>
7  *
8  *      $Id: br_forward.c,v 1.4 2001/08/14 22:05:57 davem 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/netdevice.h>
18 #include <linux/skbuff.h>
19 #include <linux/if_vlan.h>
20 #include <linux/netfilter_bridge.h>
21 #include "br_private.h"
22
23 static inline int should_deliver(const struct net_bridge_port *p, 
24                                  const struct sk_buff *skb)
25 {
26         if (skb->dev == p->dev ||
27             p->state != BR_STATE_FORWARDING)
28                 return 0;
29
30         return 1;
31 }
32
33 static inline unsigned packet_length(const struct sk_buff *skb)
34 {
35         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
36 }
37
38 int br_dev_queue_push_xmit(struct sk_buff *skb)
39 {
40         /* drop mtu oversized packets except tso */
41         if (packet_length(skb) > skb->dev->mtu && !skb_shinfo(skb)->tso_size)
42                 kfree_skb(skb);
43         else {
44 #ifdef CONFIG_BRIDGE_NETFILTER
45                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
46                 nf_bridge_maybe_copy_header(skb);
47 #endif
48                 skb_push(skb, ETH_HLEN);
49
50                 dev_queue_xmit(skb);
51         }
52
53         return 0;
54 }
55
56 int br_forward_finish(struct sk_buff *skb)
57 {
58         NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
59                         br_dev_queue_push_xmit);
60
61         return 0;
62 }
63
64 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
65 {
66         skb->dev = to->dev;
67         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
68                         br_forward_finish);
69 }
70
71 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
72 {
73         struct net_device *indev;
74
75         indev = skb->dev;
76         skb->dev = to->dev;
77         skb->ip_summed = CHECKSUM_NONE;
78
79         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
80                         br_forward_finish);
81 }
82
83 /* called with rcu_read_lock */
84 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
85 {
86         if (should_deliver(to, skb)) {
87                 __br_deliver(to, skb);
88                 return;
89         }
90
91         kfree_skb(skb);
92 }
93
94 /* called with rcu_read_lock */
95 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
96 {
97         if (should_deliver(to, skb)) {
98                 __br_forward(to, skb);
99                 return;
100         }
101
102         kfree_skb(skb);
103 }
104
105 /* called under bridge lock */
106 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
107         void (*__packet_hook)(const struct net_bridge_port *p, 
108                               struct sk_buff *skb))
109 {
110         struct net_bridge_port *p;
111         struct net_bridge_port *prev;
112
113         if (clone) {
114                 struct sk_buff *skb2;
115
116                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
117                         br->statistics.tx_dropped++;
118                         return;
119                 }
120
121                 skb = skb2;
122         }
123
124         prev = NULL;
125
126         list_for_each_entry_rcu(p, &br->port_list, list) {
127                 if (should_deliver(p, skb)) {
128                         if (prev != NULL) {
129                                 struct sk_buff *skb2;
130
131                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
132                                         br->statistics.tx_dropped++;
133                                         kfree_skb(skb);
134                                         return;
135                                 }
136
137                                 __packet_hook(prev, skb2);
138                         }
139
140                         prev = p;
141                 }
142         }
143
144         if (prev != NULL) {
145                 __packet_hook(prev, skb);
146                 return;
147         }
148
149         kfree_skb(skb);
150 }
151
152
153 /* called with rcu_read_lock */
154 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
155 {
156         br_flood(br, skb, clone, __br_deliver);
157 }
158
159 /* called under bridge lock */
160 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
161 {
162         br_flood(br, skb, clone, __br_forward);
163 }