llc_station.c

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/*
 * llc_station.c - station component of LLC
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 *       2001-2003 by Arnaldo Carvalho de Melo <[email protected]>
 *
 * 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;
}

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);
}