LXR linux/net/llc/llc

   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;                              /* 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;                              /* 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        llc_pdu_decode_sa(skb, mac_da);
  58        llc_pdu_decode_ssap(skb, &dsap);
  59        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
  60        llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
  61        rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
  62        if (unlikely(rc))
  63                goto free;
  64        dev_queue_xmit(nskb);
  65out:
  66        return rc;
  67free:
  68        kfree_skb(nskb);
  69        goto out;
  70}
  71
  72static int llc_station_ac_send_test_r(struct sk_buff *skb)
  73{
  74        u8 mac_da[ETH_ALEN], dsap;
  75        int rc = 1;
  76        u32 data_size;
  77        struct sk_buff *nskb;
  78
  79        /* The test request command is type U (llc_len = 3) */
  80        data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
  81        nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
  82
  83        if (!nskb)
  84                goto out;
  85        llc_pdu_decode_sa(skb, mac_da);
  86        llc_pdu_decode_ssap(skb, &dsap);
  87        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
  88        llc_pdu_init_as_test_rsp(nskb, skb);
  89        rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
  90        if (unlikely(rc))
  91                goto free;
  92        dev_queue_xmit(nskb);
  93out:
  94        return rc;
  95free:
  96        kfree_skb(nskb);
  97        goto out;
  98}
  99
 100/**
 101 *      llc_station_rcv - send received pdu to the station state machine
 102 *      @skb: received frame.
 103 *
 104 *      Sends data unit to station state machine.
 105 */
 106static void llc_station_rcv(struct sk_buff *skb)
 107{
 108        if (llc_stat_ev_rx_null_dsap_xid_c(skb))
 109                llc_station_ac_send_xid_r(skb);
 110        else if (llc_stat_ev_rx_null_dsap_test_c(skb))
 111                llc_station_ac_send_test_r(skb);
 112        kfree_skb(skb);
 113}
 114
 115void __init llc_station_init(void)
 116{
 117        llc_set_station_handler(llc_station_rcv);
 118}
 119
 120void llc_station_exit(void)
 121{
 122        llc_set_station_handler(NULL);
 123}
 124