root/net/bridge/br_forward.c

DEFINITIONS

1. should_deliver
2. packet_length
3. br_dev_queue_push_xmit
4. br_forward_finish
5. __br_deliver
6. __br_forward
7. br_deliver
8. br_forward
9. br_flood
10. br_flood_deliver
11. br_flood_forward

/*
 *      Forwarding decision
 *      Linux ethernet bridge
 *
 *      Authors:
 *      Lennert Buytenhek               <buytenh@gnu.org>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/netfilter_bridge.h>
#include "br_private.h"

/* Don't forward packets to originating port or forwarding diasabled */
static inline int should_deliver(const struct net_bridge_port *p,
                                 const struct sk_buff *skb)
{
        return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING);
}

static inline unsigned packet_length(const struct sk_buff *skb)
{
        return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
}

int br_dev_queue_push_xmit(struct sk_buff *skb)
{
        /* drop mtu oversized packets except gso */
        if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
                kfree_skb(skb);
        else {
                /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
                if (nf_bridge_maybe_copy_header(skb))
                        kfree_skb(skb);
                else {
                        skb_push(skb, ETH_HLEN);

                        dev_queue_xmit(skb);
                }
        }

        return 0;
}

int br_forward_finish(struct sk_buff *skb)
{
        return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
                       br_dev_queue_push_xmit);

}

static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
        skb->dev = to->dev;
        NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
                        br_forward_finish);
}

static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
{
        struct net_device *indev;

        indev = skb->dev;
        skb->dev = to->dev;
        skb_forward_csum(skb);

        NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
                        br_forward_finish);
}

/* called with rcu_read_lock */
void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
        if (should_deliver(to, skb)) {
                __br_deliver(to, skb);
                return;
        }

        kfree_skb(skb);
}

/* called with rcu_read_lock */
void br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
{
        if (!skb_warn_if_lro(skb) && should_deliver(to, skb)) {
                __br_forward(to, skb);
                return;
        }

        kfree_skb(skb);
}

/* called under bridge lock */
static void br_flood(struct net_bridge *br, struct sk_buff *skb,
        void (*__packet_hook)(const struct net_bridge_port *p,
                              struct sk_buff *skb))
{
        struct net_bridge_port *p;
        struct net_bridge_port *prev;

        prev = NULL;

        list_for_each_entry_rcu(p, &br->port_list, list) {
                if (should_deliver(p, skb)) {
                        if (prev != NULL) {
                                struct sk_buff *skb2;

                                if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
                                        br->dev->stats.tx_dropped++;
                                        kfree_skb(skb);
                                        return;
                                }

                                __packet_hook(prev, skb2);
                        }

                        prev = p;
                }
        }

        if (prev != NULL) {
                __packet_hook(prev, skb);
                return;
        }

        kfree_skb(skb);
}


/* called with rcu_read_lock */
void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
{
        br_flood(br, skb, __br_deliver);
}

/* called under bridge lock */
void br_flood_forward(struct net_bridge *br, struct sk_buff *skb)
{
        br_flood(br, skb, __br_forward);
}