/*
   * net/tipc/eth_media.c: Ethernet bearer support for TIPC

   *

   * Copyright (c) 2001-2007, Ericsson AB

   * Copyright (c) 2005-2008, 2011, Wind River Systems

   * All rights reserved.
   *

   * Redistribution and use in source and binary forms, with or without

   * modification, are permitted provided that the following conditions are met:
   *

   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the names of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.

   *

   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

   * POSSIBILITY OF SUCH DAMAGE.
   */

  #include "core.h"
  #include "bearer.h"

  #define MAX_ETH_BEARERS		MAX_BEARERS

  #define ETH_ADDR_OFFSET	4	/* message header offset of MAC address */

  /**
   * struct eth_bearer - Ethernet bearer data structure
   * @bearer: ptr to associated "generic" bearer structure
   * @dev: ptr to associated Ethernet network device
   * @tipc_packet_type: used in binding TIPC to Ethernet driver

   * @cleanup: work item used when disabling bearer

   */

  struct eth_bearer {
  	struct tipc_bearer *bearer;
  	struct net_device *dev;
  	struct packet_type tipc_packet_type;

  	struct work_struct cleanup;

  };

  static struct tipc_media eth_media_info;

  static struct eth_bearer eth_bearers[MAX_ETH_BEARERS];

  static int eth_started;

  static struct notifier_block notifier;
  
  /**

   * eth_media_addr_set - initialize Ethernet media address structure

   *
   * Media-dependent "value" field stores MAC address in first 6 bytes
   * and zeroes out the remaining bytes.

   */
  
  static void eth_media_addr_set(struct tipc_media_addr *a, char *mac)
  {

  	memcpy(a->value, mac, ETH_ALEN);
  	memset(a->value + ETH_ALEN, 0, sizeof(a->value) - ETH_ALEN);
  	a->media_id = TIPC_MEDIA_TYPE_ETH;
  	a->broadcast = !memcmp(mac, eth_media_info.bcast_addr.value, ETH_ALEN);

  }
  
  /**

   * send_msg - send a TIPC message out over an Ethernet interface

   */

  static int send_msg(struct sk_buff *buf, struct tipc_bearer *tb_ptr,

  		    struct tipc_media_addr *dest)
  {
  	struct sk_buff *clone;
  	struct net_device *dev;

  	int delta;

  
  	clone = skb_clone(buf, GFP_ATOMIC);

  	if (!clone)
  		return 0;
  
  	dev = ((struct eth_bearer *)(tb_ptr->usr_handle))->dev;
  	delta = dev->hard_header_len - skb_headroom(buf);
  
  	if ((delta > 0) &&
  	    pskb_expand_head(clone, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) {
  		kfree_skb(clone);
  		return 0;

  	}

  
  	skb_reset_network_header(clone);
  	clone->dev = dev;

  	dev_hard_header(clone, dev, ETH_P_TIPC, dest->value,

  			dev->dev_addr, clone->len);
  	dev_queue_xmit(clone);

  	return 0;

  }
  
  /**
   * recv_msg - handle incoming TIPC message from an Ethernet interface

   *

   * Accept only packets explicitly sent to this node, or broadcast packets;
   * ignores packets sent using Ethernet multicast, and traffic sent to other
   * nodes (which can happen if interface is running in promiscuous mode).

   */

  static int recv_msg(struct sk_buff *buf, struct net_device *dev,

  		    struct packet_type *pt, struct net_device *orig_dev)
  {
  	struct eth_bearer *eb_ptr = (struct eth_bearer *)pt->af_packet_priv;

  	if (!net_eq(dev_net(dev), &init_net)) {

  		kfree_skb(buf);
  		return 0;
  	}

  	if (likely(eb_ptr->bearer)) {

  		if (likely(buf->pkt_type <= PACKET_BROADCAST)) {

  			buf->next = NULL;
  			tipc_recv_msg(buf, eb_ptr->bearer);
  			return 0;

  		}

  	}

  	kfree_skb(buf);

  	return 0;

  }
  
  /**

   * enable_bearer - attach TIPC bearer to an Ethernet interface

   */
  
  static int enable_bearer(struct tipc_bearer *tb_ptr)
  {

  	struct net_device *dev = NULL;
  	struct net_device *pdev = NULL;

  	struct eth_bearer *eb_ptr = &eth_bearers[0];
  	struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];
  	char *driver_name = strchr((const char *)tb_ptr->name, ':') + 1;

  	int pending_dev = 0;
  
  	/* Find unused Ethernet bearer structure */
  
  	while (eb_ptr->dev) {
  		if (!eb_ptr->bearer)
  			pending_dev++;
  		if (++eb_ptr == stop)
  			return pending_dev ? -EAGAIN : -EDQUOT;
  	}

  
  	/* Find device with specified name */

  	read_lock(&dev_base_lock);

  	for_each_netdev(&init_net, pdev) {

  		if (!strncmp(pdev->name, driver_name, IFNAMSIZ)) {

  			dev = pdev;

  			dev_hold(dev);

  			break;
  		}

  	}

  	read_unlock(&dev_base_lock);

  	if (!dev)
  		return -ENODEV;

  	/* Create Ethernet bearer for device */
  
  	eb_ptr->dev = dev;
  	eb_ptr->tipc_packet_type.type = htons(ETH_P_TIPC);
  	eb_ptr->tipc_packet_type.dev = dev;
  	eb_ptr->tipc_packet_type.func = recv_msg;
  	eb_ptr->tipc_packet_type.af_packet_priv = eb_ptr;
  	INIT_LIST_HEAD(&(eb_ptr->tipc_packet_type.list));
  	dev_add_pack(&eb_ptr->tipc_packet_type);

  
  	/* Associate TIPC bearer with Ethernet bearer */
  
  	eb_ptr->bearer = tb_ptr;
  	tb_ptr->usr_handle = (void *)eb_ptr;
  	tb_ptr->mtu = dev->mtu;

  	tb_ptr->blocked = 0;

  	eth_media_addr_set(&tb_ptr->addr, (char *)dev->dev_addr);

  	return 0;
  }
  
  /**

   * cleanup_bearer - break association between Ethernet bearer and interface
   *
   * This routine must be invoked from a work queue because it can sleep.
   */
  
  static void cleanup_bearer(struct work_struct *work)
  {
  	struct eth_bearer *eb_ptr =
  		container_of(work, struct eth_bearer, cleanup);
  
  	dev_remove_pack(&eb_ptr->tipc_packet_type);
  	dev_put(eb_ptr->dev);
  	eb_ptr->dev = NULL;
  }
  
  /**

   * disable_bearer - detach TIPC bearer from an Ethernet interface

   *

   * Mark Ethernet bearer as inactive so that incoming buffers are thrown away,
   * then get worker thread to complete bearer cleanup.  (Can't do cleanup
   * here because cleanup code needs to sleep and caller holds spinlocks.)

   */
  
  static void disable_bearer(struct tipc_bearer *tb_ptr)
  {

  	struct eth_bearer *eb_ptr = (struct eth_bearer *)tb_ptr->usr_handle;
  
  	eb_ptr->bearer = NULL;
  	INIT_WORK(&eb_ptr->cleanup, cleanup_bearer);
  	schedule_work(&eb_ptr->cleanup);

  }
  
  /**
   * recv_notification - handle device updates from OS
   *

   * Change the state of the Ethernet bearer (if any) associated with the

   * specified device.
   */

  static int recv_notification(struct notifier_block *nb, unsigned long evt,

  			     void *dv)
  {
  	struct net_device *dev = (struct net_device *)dv;
  	struct eth_bearer *eb_ptr = &eth_bearers[0];
  	struct eth_bearer *stop = &eth_bearers[MAX_ETH_BEARERS];

  	if (!net_eq(dev_net(dev), &init_net))

  		return NOTIFY_DONE;

  	while ((eb_ptr->dev != dev)) {
  		if (++eb_ptr == stop)
  			return NOTIFY_DONE;	/* couldn't find device */
  	}
  	if (!eb_ptr->bearer)
  		return NOTIFY_DONE;		/* bearer had been disabled */

  	eb_ptr->bearer->mtu = dev->mtu;

  
  	switch (evt) {
  	case NETDEV_CHANGE:
  		if (netif_carrier_ok(dev))
  			tipc_continue(eb_ptr->bearer);
  		else
  			tipc_block_bearer(eb_ptr->bearer->name);
  		break;
  	case NETDEV_UP:
  		tipc_continue(eb_ptr->bearer);
  		break;
  	case NETDEV_DOWN:
  		tipc_block_bearer(eb_ptr->bearer->name);
  		break;
  	case NETDEV_CHANGEMTU:

  	case NETDEV_CHANGEADDR:

  		tipc_block_bearer(eb_ptr->bearer->name);

  		tipc_continue(eb_ptr->bearer);

  		break;
  	case NETDEV_UNREGISTER:

  	case NETDEV_CHANGENAME:

  		tipc_disable_bearer(eb_ptr->bearer->name);
  		break;
  	}
  	return NOTIFY_OK;
  }
  
  /**
   * eth_addr2str - convert Ethernet address to string
   */

  static int eth_addr2str(struct tipc_media_addr *a, char *str_buf, int str_size)

  {

  	if (str_size < 18)	/* 18 = strlen("aa:bb:cc:dd:ee:ff\0") */
  		return 1;

  	sprintf(str_buf, "%pM", a->value);

  	return 0;

  }

  /**
   * eth_str2addr - convert string to Ethernet address
   */
  
  static int eth_str2addr(struct tipc_media_addr *a, char *str_buf)
  {
  	char mac[ETH_ALEN];
  	int r;
  
  	r = sscanf(str_buf, "%02x:%02x:%02x:%02x:%02x:%02x",
  		       (u32 *)&mac[0], (u32 *)&mac[1], (u32 *)&mac[2],
  		       (u32 *)&mac[3], (u32 *)&mac[4], (u32 *)&mac[5]);
  
  	if (r != ETH_ALEN)
  		return 1;
  
  	eth_media_addr_set(a, mac);
  	return 0;
  }
  
  /**
   * eth_str2addr - convert Ethernet address format to message header format
   */
  
  static int eth_addr2msg(struct tipc_media_addr *a, char *msg_area)
  {
  	memset(msg_area, 0, TIPC_MEDIA_ADDR_SIZE);
  	msg_area[TIPC_MEDIA_TYPE_OFFSET] = TIPC_MEDIA_TYPE_ETH;

  	memcpy(msg_area + ETH_ADDR_OFFSET, a->value, ETH_ALEN);

  	return 0;
  }
  
  /**
   * eth_str2addr - convert message header address format to Ethernet format
   */
  
  static int eth_msg2addr(struct tipc_media_addr *a, char *msg_area)
  {
  	if (msg_area[TIPC_MEDIA_TYPE_OFFSET] != TIPC_MEDIA_TYPE_ETH)
  		return 1;
  
  	eth_media_addr_set(a, msg_area + ETH_ADDR_OFFSET);
  	return 0;
  }

  /*
   * Ethernet media registration info
   */

  static struct tipc_media eth_media_info = {

  	.send_msg	= send_msg,
  	.enable_bearer	= enable_bearer,
  	.disable_bearer	= disable_bearer,
  	.addr2str	= eth_addr2str,

  	.str2addr	= eth_str2addr,
  	.addr2msg	= eth_addr2msg,
  	.msg2addr	= eth_msg2addr,

  	.bcast_addr	= { { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
  			    TIPC_MEDIA_TYPE_ETH, 1 },

  	.priority	= TIPC_DEF_LINK_PRI,
  	.tolerance	= TIPC_DEF_LINK_TOL,
  	.window		= TIPC_DEF_LINK_WIN,
  	.type_id	= TIPC_MEDIA_TYPE_ETH,
  	.name		= "eth"
  };

  /**

   * tipc_eth_media_start - activate Ethernet bearer support

   *
   * Register Ethernet media type with TIPC bearer code.  Also register
   * with OS for notifications about device state changes.
   */

  int tipc_eth_media_start(void)

  {

  	int res;
  
  	if (eth_started)
  		return -EINVAL;

  	res = tipc_register_media(&eth_media_info);

  	if (res)
  		return res;
  
  	notifier.notifier_call = &recv_notification;
  	notifier.priority = 0;
  	res = register_netdevice_notifier(&notifier);
  	if (!res)
  		eth_started = 1;
  	return res;
  }
  
  /**

   * tipc_eth_media_stop - deactivate Ethernet bearer support

   */

  void tipc_eth_media_stop(void)

  {

  	if (!eth_started)
  		return;

  	flush_scheduled_work();

  	unregister_netdevice_notifier(&notifier);

  	eth_started = 0;
  }