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	if (skb->mac_len < ETH_HLEN)
80		goto out;
81
82	/* The test request command is type U (llc_len = 3) */
83	data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
84	nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
85
86	if (!nskb)
87		goto out;
88	llc_pdu_decode_sa(skb, mac_da);
89	llc_pdu_decode_ssap(skb, &dsap);
90	llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
91	llc_pdu_init_as_test_rsp(nskb, skb);
92	rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
93	if (unlikely(rc))
94		goto free;
95	dev_queue_xmit(nskb);
96out:
97	return rc;
98free:
99	kfree_skb(nskb);
100	goto out;
101}
102
103/**
104 *	llc_station_rcv - send received pdu to the station state machine
105 *	@skb: received frame.
106 *
107 *	Sends data unit to station state machine.
108 */
109static void llc_station_rcv(struct sk_buff *skb)
110{
111	if (llc_stat_ev_rx_null_dsap_xid_c(skb))
112		llc_station_ac_send_xid_r(skb);
113	else if (llc_stat_ev_rx_null_dsap_test_c(skb))
114		llc_station_ac_send_test_r(skb);
115	kfree_skb(skb);
116}
117
118void __init llc_station_init(void)
119{
120	llc_set_station_handler(llc_station_rcv);
121}
122
123void llc_station_exit(void)
124{
125	llc_set_station_handler(NULL);
126}
127