/*
   *	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/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 (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)(const 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;
  
  	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->statistics.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, 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);
  }