/* Copyright 2011-2014 Autronica Fire and Security AS
   *
   * 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.
   *
   * Author(s):
   *	2011-2014 Arvid Brodin, arvid.brodin@alten.se
   */
  
  #include "hsr_prp_slave.h"
  #include <linux/etherdevice.h>
  #include <linux/if_arp.h>
  #include "hsr_prp_main.h"
  #include "hsr_prp_device.h"
  #include "hsr_prp_forward.h"
  #include "hsr_prp_framereg.h"
  
  static rx_handler_result_t hsr_prp_handle_frame(struct sk_buff **pskb)
  {
  	struct sk_buff *skb = *pskb;
  	struct hsr_prp_port *port;
  	struct hsr_prp_priv *priv;
  	u16 protocol;
  
  	rcu_read_lock(); /* hsr->node_db, hsr->ports */
  	port = hsr_prp_port_get_rcu(skb->dev);
  	priv = port->priv;
  
  	if (!skb_mac_header_was_set(skb)) {
  		WARN_ONCE(1, "%s: skb invalid", __func__);
  		goto finish_pass;
  	}
  
  	if (hsr_prp_addr_is_self(priv, eth_hdr(skb)->h_source)) {
  		/* Directly kill frames sent by ourselves */
  		INC_CNT_OWN_RX(port->type, priv);
  		kfree_skb(skb);
  		goto finish_consume;
  	}
  
  	/* For HSR, non tagged frames are unexpected, but for PRP
  	 * there could be non tagged frames as well.
  	 */
  	protocol = eth_hdr(skb)->h_proto;
  
  	if (protocol != htons(ETH_P_PRP) &&
  	    protocol != htons(ETH_P_HSR) &&
  	    (port->priv->prot_version <= HSR_V1) &&
  	    (!priv->rx_offloaded))
  		goto finish_pass;
  
  	/* Frame is a HSR or PRP frame or frame form a SAN. For
  	 * PRP, only supervisor frame will have a PRP protocol.
  	 */
  	if (protocol == htons(ETH_P_HSR) || protocol == htons(ETH_P_PRP))
  		skb_push(skb, ETH_HLEN);
  
  	/* HACK: Not sure why we have to do this as some frames
  	 * don't have the skb->data pointing to mac header
  	 */
  	if (skb_mac_header(skb) != skb->data) {
  		skb_push(skb, ETH_HLEN);
  
  		/* do one more check and bail out */
  		if (skb_mac_header(skb) != skb->data) {
  			INC_CNT_RX_ERROR(port->type, priv);
  			goto finish_consume;
  		}
  	}
  
  	INC_CNT_RX(port->type, priv);
  	hsr_prp_forward_skb(skb, port);
  
  finish_consume:
  	rcu_read_unlock(); /* hsr->node_db, hsr->ports */
  	return RX_HANDLER_CONSUMED;
  
  finish_pass:
  	INC_CNT_RX_ERROR(port->type, priv);
  	rcu_read_unlock(); /* hsr->node_db, hsr->ports */
  	return RX_HANDLER_PASS;
  }
  
  bool hsr_prp_port_exists(const struct net_device *dev)
  {
  	return rcu_access_pointer(dev->rx_handler) == hsr_prp_handle_frame;
  }
  
  static int hsr_prp_check_dev_ok(struct net_device *dev)
  {
  	/* Don't allow HSR on non-ethernet like devices */
  	if ((dev->flags & IFF_LOOPBACK) || (dev->type != ARPHRD_ETHER) ||
  	    (dev->addr_len != ETH_ALEN)) {
  		netdev_info(dev, "Cannot use loopback or non-ethernet device as HSR slave.
  ");
  		return -EINVAL;
  	}
  
  	/* Don't allow enslaving hsr devices */
  	if (is_hsr_prp_master(dev)) {
  		netdev_info(dev, "Cannot create trees of HSR devices.
  ");
  		return -EINVAL;
  	}
  
  	if (hsr_prp_port_exists(dev)) {
  		netdev_info(dev, "This device is already a HSR slave.
  ");
  		return -EINVAL;
  	}
  
  	if (dev->priv_flags & IFF_DONT_BRIDGE) {
  		netdev_info(dev, "This device does not support bridging.
  ");
  		return -EOPNOTSUPP;
  	}
  
  	/* HSR over bonded devices has not been tested, but I'm not sure it
  	 * won't work...
  	 */
  
  	return 0;
  }
  
  /* Setup device to be added to the HSR bridge. */
  static int hsr_prp_portdev_setup(struct net_device *dev,
  				 struct hsr_prp_port *port)
  {
  	int res;
  
  	dev_hold(dev);
  	res = dev_set_promiscuity(dev, 1);
  	if (res)
  		goto fail_promiscuity;
  
  	/* FIXME:
  	 * What does net device "adjacency" mean? Should we do
  	 * res = netdev_master_upper_dev_link(port->dev, port->hsr->dev); ?
  	 */
  
  	res = netdev_rx_handler_register(dev, hsr_prp_handle_frame, port);
  	if (res)
  		goto fail_rx_handler;
  	dev_disable_lro(dev);
  
  	return 0;
  
  fail_rx_handler:
  	dev_set_promiscuity(dev, -1);
  fail_promiscuity:
  	dev_put(dev);
  
  	return res;
  }
  
  int hsr_prp_add_port(struct hsr_prp_priv *priv, struct net_device *dev,
  		     enum hsr_prp_port_type type)
  {
  	struct hsr_prp_port *port, *master;
  	int res;
  
  	if (type != HSR_PRP_PT_MASTER) {
  		res = hsr_prp_check_dev_ok(dev);
  		if (res)
  			return res;
  	}
  
  	port = hsr_prp_get_port(priv, type);
  	if (port)
  		return -EBUSY;	/* This port already exists */
  
  	port = kzalloc(sizeof(*port), GFP_KERNEL);
  	if (!port)
  		return -ENOMEM;
  
  	if (type != HSR_PRP_PT_MASTER) {
  		res = hsr_prp_portdev_setup(dev, port);
  		if (res)
  			goto fail_dev_setup;
  	}
  
  	port->priv = priv;
  	port->dev = dev;
  	port->type = type;
  
  	list_add_tail_rcu(&port->port_list, &priv->ports);
  	synchronize_rcu();
  
  	master = hsr_prp_get_port(priv, HSR_PRP_PT_MASTER);
  	netdev_update_features(master->dev);
  	dev_set_mtu(master->dev, hsr_prp_get_max_mtu(priv));
  
  	return 0;
  
  fail_dev_setup:
  	kfree(port);
  	return res;
  }
  
  void hsr_prp_del_port(struct hsr_prp_port *port)
  {
  	struct hsr_prp_priv *priv;
  	struct hsr_prp_port *master;
  
  	priv = port->priv;
  	master = hsr_prp_get_port(priv, HSR_PRP_PT_MASTER);
  	list_del_rcu(&port->port_list);
  
  	if (port != master) {
  		if (master) {
  			netdev_update_features(master->dev);
  			dev_set_mtu(master->dev, hsr_prp_get_max_mtu(priv));
  		}
  		netdev_rx_handler_unregister(port->dev);
  		dev_set_promiscuity(port->dev, -1);
  	}
  
  	/* FIXME?
  	 * netdev_upper_dev_unlink(port->dev, port->priv->dev);
  	 */
  
  	synchronize_rcu();
  
  	if (port != master)
  		dev_put(port->dev);
  }