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 
llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff * skb)28 static 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 
llc_stat_ev_rx_null_dsap_test_c(struct sk_buff * skb)38 static 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 
llc_station_ac_send_xid_r(struct sk_buff * skb)48 static 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);
65 out:
66 	return rc;
67 free:
68 	kfree_skb(nskb);
69 	goto out;
70 }
71 
llc_station_ac_send_test_r(struct sk_buff * skb)72 static 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);
93 out:
94 	return rc;
95 free:
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  */
llc_station_rcv(struct sk_buff * skb)106 static 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 
llc_station_init(void)115 void __init llc_station_init(void)
116 {
117 	llc_set_station_handler(llc_station_rcv);
118 }
119 
llc_station_exit(void)120 void llc_station_exit(void)
121 {
122 	llc_set_station_handler(NULL);
123 }
124