llc_sap.c revision 1d67e6501b8dba54ef8dcabebe2ad049b8ad0d67 
1/*
2 * llc_sap.c - driver routines for SAP component.
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
15#include <net/llc.h>
16#include <net/llc_if.h>
17#include <net/llc_conn.h>
18#include <net/llc_pdu.h>
19#include <net/llc_sap.h>
20#include <net/llc_s_ac.h>
21#include <net/llc_s_ev.h>
22#include <net/llc_s_st.h>
23#include <net/sock.h>
24#include <net/tcp_states.h>
25#include <linux/llc.h>
26
27/**
28 *	llc_alloc_frame - allocates sk_buff for frame
29 *	@dev: network device this skb will be sent over
30 *
31 *	Allocates an sk_buff for frame and initializes sk_buff fields.
32 *	Returns allocated skb or %NULL when out of memory.
33 */
34struct sk_buff *llc_alloc_frame(struct net_device *dev)
35{
36	struct sk_buff *skb = alloc_skb(128, GFP_ATOMIC);
37
38	if (skb) {
39		skb_reserve(skb, 50);
40		skb->nh.raw   = skb->h.raw = skb->data;
41		skb->protocol = htons(ETH_P_802_2);
42		skb->dev      = dev;
43		skb->mac.raw  = skb->head;
44	}
45	return skb;
46}
47
48void llc_save_primitive(struct sk_buff* skb, u8 prim)
49{
50	struct sockaddr_llc *addr = llc_ui_skb_cb(skb);
51
52       /* save primitive for use by the user. */
53	addr->sllc_family = skb->sk->sk_family;
54	addr->sllc_arphrd = skb->dev->type;
55	addr->sllc_test   = prim == LLC_TEST_PRIM;
56	addr->sllc_xid    = prim == LLC_XID_PRIM;
57	addr->sllc_ua     = prim == LLC_DATAUNIT_PRIM;
58	llc_pdu_decode_sa(skb, addr->sllc_mac);
59	llc_pdu_decode_ssap(skb, &addr->sllc_sap);
60}
61
62/**
63 *	llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
64 *	@sap: pointer to SAP
65 *	@skb: received pdu
66 */
67void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
68{
69	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
70	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
71
72	switch (LLC_U_PDU_RSP(pdu)) {
73	case LLC_1_PDU_CMD_TEST:
74		ev->prim = LLC_TEST_PRIM;	break;
75	case LLC_1_PDU_CMD_XID:
76		ev->prim = LLC_XID_PRIM;	break;
77	case LLC_1_PDU_CMD_UI:
78		ev->prim = LLC_DATAUNIT_PRIM;	break;
79	}
80	ev->ind_cfm_flag = LLC_IND;
81}
82
83/**
84 *	llc_find_sap_trans - finds transition for event
85 *	@sap: pointer to SAP
86 *	@skb: happened event
87 *
88 *	This function finds transition that matches with happened event.
89 *	Returns the pointer to found transition on success or %NULL for
90 *	failure.
91 */
92static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
93						      struct sk_buff* skb)
94{
95	int i = 0;
96	struct llc_sap_state_trans *rc = NULL;
97	struct llc_sap_state_trans **next_trans;
98	struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
99	/*
100	 * Search thru events for this state until list exhausted or until
101	 * its obvious the event is not valid for the current state
102	 */
103	for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
104		if (!next_trans[i]->ev(sap, skb)) {
105			rc = next_trans[i]; /* got event match; return it */
106			break;
107		}
108	return rc;
109}
110
111/**
112 *	llc_exec_sap_trans_actions - execute actions related to event
113 *	@sap: pointer to SAP
114 *	@trans: pointer to transition that it's actions must be performed
115 *	@skb: happened event.
116 *
117 *	This function executes actions that is related to happened event.
118 *	Returns 0 for success and 1 for failure of at least one action.
119 */
120static int llc_exec_sap_trans_actions(struct llc_sap *sap,
121				      struct llc_sap_state_trans *trans,
122				      struct sk_buff *skb)
123{
124	int rc = 0;
125	llc_sap_action_t *next_action = trans->ev_actions;
126
127	for (; next_action && *next_action; next_action++)
128		if ((*next_action)(sap, skb))
129			rc = 1;
130	return rc;
131}
132
133/**
134 *	llc_sap_next_state - finds transition, execs actions & change SAP state
135 *	@sap: pointer to SAP
136 *	@skb: happened event
137 *
138 *	This function finds transition that matches with happened event, then
139 *	executes related actions and finally changes state of SAP. It returns
140 *	0 on success and 1 for failure.
141 */
142static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
143{
144	int rc = 1;
145	struct llc_sap_state_trans *trans;
146
147	if (sap->state > LLC_NR_SAP_STATES)
148		goto out;
149	trans = llc_find_sap_trans(sap, skb);
150	if (!trans)
151		goto out;
152	/*
153	 * Got the state to which we next transition; perform the actions
154	 * associated with this transition before actually transitioning to the
155	 * next state
156	 */
157	rc = llc_exec_sap_trans_actions(sap, trans, skb);
158	if (rc)
159		goto out;
160	/*
161	 * Transition SAP to next state if all actions execute successfully
162	 */
163	sap->state = trans->next_state;
164out:
165	return rc;
166}
167
168/**
169 *	llc_sap_state_process - sends event to SAP state machine
170 *	@sap: sap to use
171 *	@skb: pointer to occurred event
172 *
173 *	After executing actions of the event, upper layer will be indicated
174 *	if needed(on receiving an UI frame). sk can be null for the
175 *	datalink_proto case.
176 */
177static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
178{
179	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
180
181	/*
182	 * We have to hold the skb, because llc_sap_next_state
183	 * will kfree it in the sending path and we need to
184	 * look at the skb->cb, where we encode llc_sap_state_ev.
185	 */
186	skb_get(skb);
187	ev->ind_cfm_flag = 0;
188	llc_sap_next_state(sap, skb);
189	if (ev->ind_cfm_flag == LLC_IND) {
190		if (skb->sk->sk_state == TCP_LISTEN)
191			kfree_skb(skb);
192		else {
193			llc_save_primitive(skb, ev->prim);
194
195			/* queue skb to the user. */
196			if (sock_queue_rcv_skb(skb->sk, skb))
197				kfree_skb(skb);
198		}
199	}
200	kfree_skb(skb);
201}
202
203/**
204 *	llc_build_and_send_test_pkt - TEST interface for upper layers.
205 *	@sap: sap to use
206 *	@skb: packet to send
207 *	@dmac: destination mac address
208 *	@dsap: destination sap
209 *
210 *	This function is called when upper layer wants to send a TEST pdu.
211 *	Returns 0 for success, 1 otherwise.
212 */
213void llc_build_and_send_test_pkt(struct llc_sap *sap,
214				 struct sk_buff *skb, u8 *dmac, u8 dsap)
215{
216	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
217
218	ev->saddr.lsap = sap->laddr.lsap;
219	ev->daddr.lsap = dsap;
220	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
221	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
222
223	ev->type      = LLC_SAP_EV_TYPE_PRIM;
224	ev->prim      = LLC_TEST_PRIM;
225	ev->prim_type = LLC_PRIM_TYPE_REQ;
226	llc_sap_state_process(sap, skb);
227}
228
229/**
230 *	llc_build_and_send_xid_pkt - XID interface for upper layers
231 *	@sap: sap to use
232 *	@skb: packet to send
233 *	@dmac: destination mac address
234 *	@dsap: destination sap
235 *
236 *	This function is called when upper layer wants to send a XID pdu.
237 *	Returns 0 for success, 1 otherwise.
238 */
239void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
240				u8 *dmac, u8 dsap)
241{
242	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
243
244	ev->saddr.lsap = sap->laddr.lsap;
245	ev->daddr.lsap = dsap;
246	memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
247	memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
248
249	ev->type      = LLC_SAP_EV_TYPE_PRIM;
250	ev->prim      = LLC_XID_PRIM;
251	ev->prim_type = LLC_PRIM_TYPE_REQ;
252	llc_sap_state_process(sap, skb);
253}
254
255/**
256 *	llc_sap_rcv - sends received pdus to the sap state machine
257 *	@sap: current sap component structure.
258 *	@skb: received frame.
259 *
260 *	Sends received pdus to the sap state machine.
261 */
262static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb)
263{
264	struct llc_sap_state_ev *ev = llc_sap_ev(skb);
265
266	ev->type   = LLC_SAP_EV_TYPE_PDU;
267	ev->reason = 0;
268	llc_sap_state_process(sap, skb);
269}
270
271/**
272 *	llc_lookup_dgram - Finds dgram socket for the local sap/mac
273 *	@sap: SAP
274 *	@laddr: address of local LLC (MAC + SAP)
275 *
276 *	Search socket list of the SAP and finds connection using the local
277 *	mac, and local sap. Returns pointer for socket found, %NULL otherwise.
278 */
279static struct sock *llc_lookup_dgram(struct llc_sap *sap,
280				     struct llc_addr *laddr)
281{
282	struct sock *rc;
283	struct hlist_node *node;
284
285	read_lock_bh(&sap->sk_list.lock);
286	sk_for_each(rc, node, &sap->sk_list.list) {
287		struct llc_sock *llc = llc_sk(rc);
288
289		if (rc->sk_type == SOCK_DGRAM &&
290		    llc->laddr.lsap == laddr->lsap &&
291		    llc_mac_match(llc->laddr.mac, laddr->mac)) {
292			sock_hold(rc);
293			goto found;
294		}
295	}
296	rc = NULL;
297found:
298	read_unlock_bh(&sap->sk_list.lock);
299	return rc;
300}
301
302void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
303{
304	struct llc_addr laddr;
305	struct sock *sk;
306
307	llc_pdu_decode_da(skb, laddr.mac);
308	llc_pdu_decode_dsap(skb, &laddr.lsap);
309
310	sk = llc_lookup_dgram(sap, &laddr);
311	if (sk) {
312		skb->sk = sk;
313		llc_sap_rcv(sap, skb);
314		sock_put(sk);
315	} else
316		kfree_skb(skb);
317}
318