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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Arnaldo Carvalho de Meloc752f072005-08-09 20:08:28 -070024#include <net/tcp_states.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/llc.h>
26
27/**
28 * llc_alloc_frame - allocates sk_buff for frame
Arnaldo Carvalho de Melo1d67e652005-09-22 03:27:56 -030029 * @dev: network device this skb will be sent over
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 *
31 * Allocates an sk_buff for frame and initializes sk_buff fields.
32 * Returns allocated skb or %NULL when out of memory.
33 */
Arnaldo Carvalho de Melo1d67e652005-09-22 03:27:56 -030034struct sk_buff *llc_alloc_frame(struct net_device *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -070035{
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);
Arnaldo Carvalho de Melo1d67e652005-09-22 03:27:56 -030042 skb->dev = dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 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}