linux/net/llc/llc_station.c
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   1/*
   2 * llc_station.c - station component of LLC
   3 *
   4 * Copyright (c) 1997 by Procom Technology, Inc.
   5 *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6 *
   7 * This program can be redistributed or modified under the terms of the
   8 * GNU General Public License as published by the Free Software Foundation.
   9 * This program is distributed without any warranty or implied warranty
  10 * of merchantability or fitness for a particular purpose.
  11 *
  12 * See the GNU General Public License for more details.
  13 */
  14#include <linux/init.h>
  15#include <linux/module.h>
  16#include <linux/slab.h>
  17#include <net/llc.h>
  18#include <net/llc_sap.h>
  19#include <net/llc_conn.h>
  20#include <net/llc_c_ac.h>
  21#include <net/llc_s_ac.h>
  22#include <net/llc_c_ev.h>
  23#include <net/llc_c_st.h>
  24#include <net/llc_s_ev.h>
  25#include <net/llc_s_st.h>
  26#include <net/llc_pdu.h>
  27
  28static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
  29{
  30        struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  31
  32        return LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
  33               LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
  34               LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
  35               !pdu->dsap ? 0 : 1;                      /* NULL DSAP value */
  36}
  37
  38static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
  39{
  40        struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  41
  42        return LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
  43               LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
  44               LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
  45               !pdu->dsap ? 0 : 1;                      /* NULL DSAP */
  46}
  47
  48static int llc_station_ac_send_xid_r(struct sk_buff *skb)
  49{
  50        u8 mac_da[ETH_ALEN], dsap;
  51        int rc = 1;
  52        struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
  53                                               sizeof(struct llc_xid_info));
  54
  55        if (!nskb)
  56                goto out;
  57        rc = 0;
  58        llc_pdu_decode_sa(skb, mac_da);
  59        llc_pdu_decode_ssap(skb, &dsap);
  60        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
  61        llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
  62        rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
  63        if (unlikely(rc))
  64                goto free;
  65        dev_queue_xmit(nskb);
  66out:
  67        return rc;
  68free:
  69        kfree_skb(nskb);
  70        goto out;
  71}
  72
  73static int llc_station_ac_send_test_r(struct sk_buff *skb)
  74{
  75        u8 mac_da[ETH_ALEN], dsap;
  76        int rc = 1;
  77        u32 data_size;
  78        struct sk_buff *nskb;
  79
  80        /* The test request command is type U (llc_len = 3) */
  81        data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
  82        nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
  83
  84        if (!nskb)
  85                goto out;
  86        rc = 0;
  87        llc_pdu_decode_sa(skb, mac_da);
  88        llc_pdu_decode_ssap(skb, &dsap);
  89        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
  90        llc_pdu_init_as_test_rsp(nskb, skb);
  91        rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
  92        if (unlikely(rc))
  93                goto free;
  94        dev_queue_xmit(nskb);
  95out:
  96        return rc;
  97free:
  98        kfree_skb(nskb);
  99        goto out;
 100}
 101
 102/**
 103 *      llc_station_rcv - send received pdu to the station state machine
 104 *      @skb: received frame.
 105 *
 106 *      Sends data unit to station state machine.
 107 */
 108static void llc_station_rcv(struct sk_buff *skb)
 109{
 110        if (llc_stat_ev_rx_null_dsap_xid_c(skb))
 111                llc_station_ac_send_xid_r(skb);
 112        else if (llc_stat_ev_rx_null_dsap_test_c(skb))
 113                llc_station_ac_send_test_r(skb);
 114        kfree_skb(skb);
 115}
 116
 117void __init llc_station_init(void)
 118{
 119        llc_set_station_handler(llc_station_rcv);
 120}
 121
 122void llc_station_exit(void)
 123{
 124        llc_set_station_handler(NULL);
 125}
 126
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