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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/net/llc/llc_station.c
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/*

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 * llc_station.c - station component of LLC

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 *

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 * Copyright (c) 1997 by Procom Technology, Inc.

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 * 		 2001-2003 by Arnaldo Carvalho de Melo <[email protected]>

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 *

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 * This program can be redistributed or modified under the terms of the

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 * GNU General Public License as published by the Free Software Foundation.

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 * This program is distributed without any warranty or implied warranty

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 * of merchantability or fitness for a particular purpose.

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 *

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 * See the GNU General Public License for more details.

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 */

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#include <linux/init.h>

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#include <linux/module.h>

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#include <linux/slab.h>

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#include <net/llc.h>

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#include <net/llc_sap.h>

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#include <net/llc_conn.h>

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#include <net/llc_c_ac.h>

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#include <net/llc_s_ac.h>

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#include <net/llc_c_ev.h>

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#include <net/llc_c_st.h>

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#include <net/llc_s_ev.h>

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#include <net/llc_s_st.h>

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#include <net/llc_pdu.h>

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static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)

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{

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	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

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

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	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */

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	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&

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	       !pdu->dsap;				/* NULL DSAP value */

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}

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static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)

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{

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	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

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

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	       LLC_PDU_TYPE_IS_U(pdu) &&		/* U type PDU */

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	       LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&

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	       !pdu->dsap;				/* NULL DSAP */

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}

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static int llc_station_ac_send_xid_r(struct sk_buff *skb)

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{

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	u8 mac_da[ETH_ALEN], dsap;

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	int rc = 1;

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	struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,

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					       sizeof(struct llc_xid_info));

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	if (!nskb)

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		goto out;

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	llc_pdu_decode_sa(skb, mac_da);

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	llc_pdu_decode_ssap(skb, &dsap);

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	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);

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	llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);

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

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	if (unlikely(rc))

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		goto free;

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	dev_queue_xmit(nskb);

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out:

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	return rc;

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free:

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	kfree_skb(nskb);

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	goto out;

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}

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static int llc_station_ac_send_test_r(struct sk_buff *skb)

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{

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	u8 mac_da[ETH_ALEN], dsap;

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	int rc = 1;

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	u32 data_size;

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	struct sk_buff *nskb;

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	if (skb->mac_len < ETH_HLEN)

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		goto out;

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	/* The test request command is type U (llc_len = 3) */

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	data_size = ntohs(eth_hdr(skb)->h_proto) - 3;

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	nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);

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	if (!nskb)

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		goto out;

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	llc_pdu_decode_sa(skb, mac_da);

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	llc_pdu_decode_ssap(skb, &dsap);

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	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);

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	llc_pdu_init_as_test_rsp(nskb, skb);

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

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	if (unlikely(rc))

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		goto free;

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	dev_queue_xmit(nskb);

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out:

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	return rc;

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free:

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	kfree_skb(nskb);

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	goto out;

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}

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/**

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 *	llc_station_rcv - send received pdu to the station state machine

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 *	@skb: received frame.

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 *

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 *	Sends data unit to station state machine.

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 */

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static void llc_station_rcv(struct sk_buff *skb)

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{

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	if (llc_stat_ev_rx_null_dsap_xid_c(skb))

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		llc_station_ac_send_xid_r(skb);

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	else if (llc_stat_ev_rx_null_dsap_test_c(skb))

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		llc_station_ac_send_test_r(skb);

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	kfree_skb(skb);

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}

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void __init llc_station_init(void)

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{

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	llc_set_station_handler(llc_station_rcv);

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}

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void llc_station_exit(void)

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{

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	llc_set_station_handler(NULL);

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}

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