[NETFILTER] bridge: code rearrangement for clarity
[linux-2.6.git] / 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 /* Don't forward packets to originating port or forwarding diasabled */
24 static inline int should_deliver(const struct net_bridge_port *p, 
25                                  const struct sk_buff *skb)
26 {
27         return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING);
28 }
29
30 static inline unsigned packet_length(const struct sk_buff *skb)
31 {
32         return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
33 }
34
35 int br_dev_queue_push_xmit(struct sk_buff *skb)
36 {
37         /* drop mtu oversized packets except gso */
38         if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
39                 kfree_skb(skb);
40         else {
41                 /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
42                 if (nf_bridge_maybe_copy_header(skb))
43                         kfree_skb(skb);
44                 else {
45                         skb_push(skb, ETH_HLEN);
46
47                         dev_queue_xmit(skb);
48                 }
49         }
50
51         return 0;
52 }
53
54 int br_forward_finish(struct sk_buff *skb)
55 {
56         return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
57                        br_dev_queue_push_xmit);
58
59 }
60
61 static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
62 {
63         skb->dev = to->dev;
64         NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
65                         br_forward_finish);
66 }
67
68 static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
69 {
70         struct net_device *indev;
71
72         indev = skb->dev;
73         skb->dev = to->dev;
74         skb->ip_summed = CHECKSUM_NONE;
75
76         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
77                         br_forward_finish);
78 }
79
80 /* called with rcu_read_lock */
81 void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
82 {
83         if (should_deliver(to, skb)) {
84                 __br_deliver(to, skb);
85                 return;
86         }
87
88         kfree_skb(skb);
89 }
90
91 /* called with rcu_read_lock */
92 void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
93 {
94         if (should_deliver(to, skb)) {
95                 __br_forward(to, skb);
96                 return;
97         }
98
99         kfree_skb(skb);
100 }
101
102 /* called under bridge lock */
103 static void br_flood(struct net_bridge *br, struct sk_buff *skb, int clone,
104         void (*__packet_hook)(const struct net_bridge_port *p, 
105                               struct sk_buff *skb))
106 {
107         struct net_bridge_port *p;
108         struct net_bridge_port *prev;
109
110         if (clone) {
111                 struct sk_buff *skb2;
112
113                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
114                         br->statistics.tx_dropped++;
115                         return;
116                 }
117
118                 skb = skb2;
119         }
120
121         prev = NULL;
122
123         list_for_each_entry_rcu(p, &br->port_list, list) {
124                 if (should_deliver(p, skb)) {
125                         if (prev != NULL) {
126                                 struct sk_buff *skb2;
127
128                                 if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
129                                         br->statistics.tx_dropped++;
130                                         kfree_skb(skb);
131                                         return;
132                                 }
133
134                                 __packet_hook(prev, skb2);
135                         }
136
137                         prev = p;
138                 }
139         }
140
141         if (prev != NULL) {
142                 __packet_hook(prev, skb);
143                 return;
144         }
145
146         kfree_skb(skb);
147 }
148
149
150 /* called with rcu_read_lock */
151 void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
152 {
153         br_flood(br, skb, clone, __br_deliver);
154 }
155
156 /* called under bridge lock */
157 void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
158 {
159         br_flood(br, skb, clone, __br_forward);
160 }