text: /*
   *	Forwarding decision
   *	Linux ethernet bridge
   *
   *	Authors:
   *	Lennert Buytenhek		<buytenh@gnu.org>
   *
   *	$Id: br_forward.c,v 1.4 2001/08/14 22:05:57 davem Exp $
   *
   *	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/inetdevice.h>
  #include <linux/skbuff.h>
  #include <linux/if_bridge.h>
  #include <linux/netfilter_bridge.h>
  #include "br_private.h"
  
  static inline int should_deliver(struct net_bridge_port *p, struct sk_buff *skb)
  {
  	if (skb->dev == p->dev ||
  	    p->state != BR_STATE_FORWARDING)
  		return 0;
  
  	return 1;
  }
  
  static int __dev_queue_push_xmit(struct sk_buff *skb)
  {
  	skb_push(skb, ETH_HLEN);
  	dev_queue_xmit(skb);
  
  	return 0;
  }
  
  static int __br_forward_finish(struct sk_buff *skb)
  {
  	NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
  			__dev_queue_push_xmit);
  
  	return 0;
  }
  
  static void __br_deliver(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(struct net_bridge_port *to, struct sk_buff *skb)
  {
  	struct net_device *indev;
  
  	indev = skb->dev;
  	skb->dev = to->dev;
  	skb->ip_summed = CHECKSUM_NONE;
  
  	NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
  			__br_forward_finish);
  }
  
  /* called under bridge lock */
  void br_deliver(struct net_bridge_port *to, struct sk_buff *skb)
  {
  	if (should_deliver(to, skb)) {
  		__br_deliver(to, skb);
  		return;
  	}
  
  	kfree_skb(skb);
  }
  
  /* called under bridge lock */
  void br_forward(struct net_bridge_port *to, struct sk_buff *skb)
  {
  	if (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, int clone,
  	void (*__packet_hook)(struct net_bridge_port *p, struct sk_buff *skb))
  {
  	struct net_bridge_port *p;
  	struct net_bridge_port *prev;
  
  	if (clone) {
  		struct sk_buff *skb2;
  
  		if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  			br->statistics.tx_dropped++;
  			return;
  		}
  
  		skb = skb2;
  	}
  
  	prev = NULL;
  
  	p = br->port_list;
  	while (p != NULL) {
  		if (should_deliver(p, skb)) {
  			if (prev != NULL) {
  				struct sk_buff *skb2;
  
  				if ((skb2 = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  					br->statistics.tx_dropped++;
  					kfree_skb(skb);
  					return;
  				}
  
  				__packet_hook(prev, skb2);
  			}
  
  			prev = p;
  		}
  
  		p = p->next;
  	}
  
  	if (prev != NULL) {
  		__packet_hook(prev, skb);
  		return;
  	}
  
  	kfree_skb(skb);
  }
  
  /* called under bridge lock */
  void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb, int clone)
  {
  	br_flood(br, skb, clone, __br_deliver);
  }
  
  /* called under bridge lock */
  void br_flood_forward(struct net_bridge *br, struct sk_buff *skb, int clone)
  {
  	br_flood(br, skb, clone, __br_forward);
  }
  