/*
   * llc_station.c - station component of LLC
   *
   * Copyright (c) 1997 by Procom Technology, Inc.
   * 		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   *
   * This program can be redistributed or modified under the terms of the
   * GNU General Public License as published by the Free Software Foundation.
   * This program is distributed without any warranty or implied warranty
   * of merchantability or fitness for a particular purpose.
   *
   * See the GNU General Public License for more details.
   */

  #include <linux/init.h>
  #include <linux/module.h>

  #include <linux/slab.h>

  #include <net/llc.h>
  #include <net/llc_sap.h>
  #include <net/llc_conn.h>
  #include <net/llc_c_ac.h>
  #include <net/llc_s_ac.h>
  #include <net/llc_c_ev.h>
  #include <net/llc_c_st.h>
  #include <net/llc_s_ev.h>
  #include <net/llc_s_st.h>
  #include <net/llc_pdu.h>

  static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
  {

  	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

  	return LLC_PDU_IS_CMD(pdu) &&			/* command PDU */

  	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */
  	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
  	       !pdu->dsap ? 0 : 1;			/* NULL DSAP value */
  }

  static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
  {

  	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

  	return LLC_PDU_IS_CMD(pdu) &&			/* command PDU */

  	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */
  	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
  	       !pdu->dsap ? 0 : 1;			/* NULL DSAP */
  }

  static int llc_station_ac_send_xid_r(struct sk_buff *skb)
  {
  	u8 mac_da[ETH_ALEN], dsap;
  	int rc = 1;

  	struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
  					       sizeof(struct llc_xid_info));

  
  	if (!nskb)
  		goto out;
  	rc = 0;

  	llc_pdu_decode_sa(skb, mac_da);
  	llc_pdu_decode_ssap(skb, &dsap);
  	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
  	llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);

  	rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);

  	if (unlikely(rc))

  		goto free;

  	dev_queue_xmit(nskb);

  out:
  	return rc;
  free:

  	kfree_skb(nskb);

  	goto out;
  }
  
  static int llc_station_ac_send_test_r(struct sk_buff *skb)
  {
  	u8 mac_da[ETH_ALEN], dsap;
  	int rc = 1;

  	u32 data_size;
  	struct sk_buff *nskb;
  
  	/* The test request command is type U (llc_len = 3) */
  	data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
  	nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);

  
  	if (!nskb)
  		goto out;
  	rc = 0;

  	llc_pdu_decode_sa(skb, mac_da);
  	llc_pdu_decode_ssap(skb, &dsap);
  	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);

  	llc_pdu_init_as_test_rsp(nskb, skb);

  	rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);

  	if (unlikely(rc))

  		goto free;

  	dev_queue_xmit(nskb);

  out:
  	return rc;
  free:

  	kfree_skb(nskb);

  	goto out;
  }

  /**

   *	llc_station_rcv - send received pdu to the station state machine
   *	@skb: received frame.
   *
   *	Sends data unit to station state machine.
   */
  static void llc_station_rcv(struct sk_buff *skb)
  {

  	if (llc_stat_ev_rx_null_dsap_xid_c(skb))
  		llc_station_ac_send_xid_r(skb);
  	else if (llc_stat_ev_rx_null_dsap_test_c(skb))
  		llc_station_ac_send_test_r(skb);

  	kfree_skb(skb);

  }

  void __init llc_station_init(void)

  {

  	llc_set_station_handler(llc_station_rcv);

  }

  void llc_station_exit(void)

  {
  	llc_set_station_handler(NULL);
  }