1/*
2 * llc_pdu.c - access to PDU internals
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 <linux/netdevice.h>
16#include <net/llc_pdu.h>
17
18static void llc_pdu_decode_pdu_type(struct sk_buff *skb, u8 *type);
19static u8 llc_pdu_get_pf_bit(struct llc_pdu_sn *pdu);
20
21void llc_pdu_set_cmd_rsp(struct sk_buff *skb, u8 pdu_type)
22{
23	llc_pdu_un_hdr(skb)->ssap |= pdu_type;
24}
25
26/**
27 *	llc_pdu_set_pf_bit - sets poll/final bit in LLC header
28 *	@skb: Frame to set bit in
29 *	@bit_value: poll/final bit (0 or 1).
30 *
31 *	This function sets poll/final bit in LLC header (based on type of PDU).
32 *	in I or S pdus, p/f bit is right bit of fourth byte in header. in U
33 *	pdus p/f bit is fifth bit of third byte.
34 */
35void llc_pdu_set_pf_bit(struct sk_buff *skb, u8 bit_value)
36{
37	u8 pdu_type;
38	struct llc_pdu_sn *pdu;
39
40	llc_pdu_decode_pdu_type(skb, &pdu_type);
41	pdu = llc_pdu_sn_hdr(skb);
42
43	switch (pdu_type) {
44	case LLC_PDU_TYPE_I:
45	case LLC_PDU_TYPE_S:
46		pdu->ctrl_2 = (pdu->ctrl_2 & 0xFE) | bit_value;
47		break;
48	case LLC_PDU_TYPE_U:
49		pdu->ctrl_1 |= (pdu->ctrl_1 & 0xEF) | (bit_value << 4);
50		break;
51	}
52}
53
54/**
55 *	llc_pdu_decode_pf_bit - extracs poll/final bit from LLC header
56 *	@skb: input skb that p/f bit must be extracted from it
57 *	@pf_bit: poll/final bit (0 or 1)
58 *
59 *	This function extracts poll/final bit from LLC header (based on type of
60 *	PDU). In I or S pdus, p/f bit is right bit of fourth byte in header. In
61 *	U pdus p/f bit is fifth bit of third byte.
62 */
63void llc_pdu_decode_pf_bit(struct sk_buff *skb, u8 *pf_bit)
64{
65	u8 pdu_type;
66	struct llc_pdu_sn *pdu;
67
68	llc_pdu_decode_pdu_type(skb, &pdu_type);
69	pdu = llc_pdu_sn_hdr(skb);
70
71	switch (pdu_type) {
72	case LLC_PDU_TYPE_I:
73	case LLC_PDU_TYPE_S:
74		*pf_bit = pdu->ctrl_2 & LLC_S_PF_BIT_MASK;
75		break;
76	case LLC_PDU_TYPE_U:
77		*pf_bit = (pdu->ctrl_1 & LLC_U_PF_BIT_MASK) >> 4;
78		break;
79	}
80}
81
82/**
83 *	llc_pdu_init_as_disc_cmd - Builds DISC PDU
84 *	@skb: Address of the skb to build
85 *	@p_bit: The P bit to set in the PDU
86 *
87 *	Builds a pdu frame as a DISC command.
88 */
89void llc_pdu_init_as_disc_cmd(struct sk_buff *skb, u8 p_bit)
90{
91	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
92
93	pdu->ctrl_1  = LLC_PDU_TYPE_U;
94	pdu->ctrl_1 |= LLC_2_PDU_CMD_DISC;
95	pdu->ctrl_1 |= ((p_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
96}
97
98/**
99 *	llc_pdu_init_as_i_cmd - builds I pdu
100 *	@skb: Address of the skb to build
101 *	@p_bit: The P bit to set in the PDU
102 *	@ns: The sequence number of the data PDU
103 *	@nr: The seq. number of the expected I PDU from the remote
104 *
105 *	Builds a pdu frame as an I command.
106 */
107void llc_pdu_init_as_i_cmd(struct sk_buff *skb, u8 p_bit, u8 ns, u8 nr)
108{
109	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
110
111	pdu->ctrl_1  = LLC_PDU_TYPE_I;
112	pdu->ctrl_2  = 0;
113	pdu->ctrl_2 |= (p_bit & LLC_I_PF_BIT_MASK); /* p/f bit */
114	pdu->ctrl_1 |= (ns << 1) & 0xFE;   /* set N(S) in bits 2..8 */
115	pdu->ctrl_2 |= (nr << 1) & 0xFE;   /* set N(R) in bits 10..16 */
116}
117
118/**
119 *	llc_pdu_init_as_rej_cmd - builds REJ PDU
120 *	@skb: Address of the skb to build
121 *	@p_bit: The P bit to set in the PDU
122 *	@nr: The seq. number of the expected I PDU from the remote
123 *
124 *	Builds a pdu frame as a REJ command.
125 */
126void llc_pdu_init_as_rej_cmd(struct sk_buff *skb, u8 p_bit, u8 nr)
127{
128	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
129
130	pdu->ctrl_1  = LLC_PDU_TYPE_S;
131	pdu->ctrl_1 |= LLC_2_PDU_CMD_REJ;
132	pdu->ctrl_2  = 0;
133	pdu->ctrl_2 |= p_bit & LLC_S_PF_BIT_MASK;
134	pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
135	pdu->ctrl_2 |= (nr << 1) & 0xFE; /* set N(R) in bits 10..16 */
136}
137
138/**
139 *	llc_pdu_init_as_rnr_cmd - builds RNR pdu
140 *	@skb: Address of the skb to build
141 *	@p_bit: The P bit to set in the PDU
142 *	@nr: The seq. number of the expected I PDU from the remote
143 *
144 *	Builds a pdu frame as an RNR command.
145 */
146void llc_pdu_init_as_rnr_cmd(struct sk_buff *skb, u8 p_bit, u8 nr)
147{
148	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
149
150	pdu->ctrl_1  = LLC_PDU_TYPE_S;
151	pdu->ctrl_1 |= LLC_2_PDU_CMD_RNR;
152	pdu->ctrl_2  = 0;
153	pdu->ctrl_2 |= p_bit & LLC_S_PF_BIT_MASK;
154	pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
155	pdu->ctrl_2 |= (nr << 1) & 0xFE; /* set N(R) in bits 10..16 */
156}
157
158/**
159 *	llc_pdu_init_as_rr_cmd - Builds RR pdu
160 *	@skb: Address of the skb to build
161 *	@p_bit: The P bit to set in the PDU
162 *	@nr: The seq. number of the expected I PDU from the remote
163 *
164 *	Builds a pdu frame as an RR command.
165 */
166void llc_pdu_init_as_rr_cmd(struct sk_buff *skb, u8 p_bit, u8 nr)
167{
168	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
169
170	pdu->ctrl_1  = LLC_PDU_TYPE_S;
171	pdu->ctrl_1 |= LLC_2_PDU_CMD_RR;
172	pdu->ctrl_2  = p_bit & LLC_S_PF_BIT_MASK;
173	pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
174	pdu->ctrl_2 |= (nr << 1) & 0xFE; /* set N(R) in bits 10..16 */
175}
176
177/**
178 *	llc_pdu_init_as_sabme_cmd - builds SABME pdu
179 *	@skb: Address of the skb to build
180 *	@p_bit: The P bit to set in the PDU
181 *
182 *	Builds a pdu frame as an SABME command.
183 */
184void llc_pdu_init_as_sabme_cmd(struct sk_buff *skb, u8 p_bit)
185{
186	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
187
188	pdu->ctrl_1  = LLC_PDU_TYPE_U;
189	pdu->ctrl_1 |= LLC_2_PDU_CMD_SABME;
190	pdu->ctrl_1 |= ((p_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
191}
192
193/**
194 *	llc_pdu_init_as_dm_rsp - builds DM response pdu
195 *	@skb: Address of the skb to build
196 *	@f_bit: The F bit to set in the PDU
197 *
198 *	Builds a pdu frame as a DM response.
199 */
200void llc_pdu_init_as_dm_rsp(struct sk_buff *skb, u8 f_bit)
201{
202	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
203
204	pdu->ctrl_1  = LLC_PDU_TYPE_U;
205	pdu->ctrl_1 |= LLC_2_PDU_RSP_DM;
206	pdu->ctrl_1 |= ((f_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
207}
208
209/**
210 *	llc_pdu_init_as_frmr_rsp - builds FRMR response PDU
211 *	@skb: Address of the frame to build
212 *	@prev_pdu: The rejected PDU frame
213 *	@f_bit: The F bit to set in the PDU
214 *	@vs: tx state vari value for the data link conn at the rejecting LLC
215 *	@vr: rx state var value for the data link conn at the rejecting LLC
216 *	@vzyxw: completely described in the IEEE Std 802.2 document (Pg 55)
217 *
218 *	Builds a pdu frame as a FRMR response.
219 */
220void llc_pdu_init_as_frmr_rsp(struct sk_buff *skb, struct llc_pdu_sn *prev_pdu,
221			      u8 f_bit, u8 vs, u8 vr, u8 vzyxw)
222{
223	struct llc_frmr_info *frmr_info;
224	u8 prev_pf = 0;
225	u8 *ctrl;
226	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
227
228	pdu->ctrl_1  = LLC_PDU_TYPE_U;
229	pdu->ctrl_1 |= LLC_2_PDU_RSP_FRMR;
230	pdu->ctrl_1 |= ((f_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
231
232	frmr_info = (struct llc_frmr_info *)&pdu->ctrl_2;
233	ctrl = (u8 *)&prev_pdu->ctrl_1;
234	FRMR_INFO_SET_REJ_CNTRL(frmr_info,ctrl);
235	FRMR_INFO_SET_Vs(frmr_info, vs);
236	FRMR_INFO_SET_Vr(frmr_info, vr);
237	prev_pf = llc_pdu_get_pf_bit(prev_pdu);
238	FRMR_INFO_SET_C_R_BIT(frmr_info, prev_pf);
239	FRMR_INFO_SET_INVALID_PDU_CTRL_IND(frmr_info, vzyxw);
240	FRMR_INFO_SET_INVALID_PDU_INFO_IND(frmr_info, vzyxw);
241	FRMR_INFO_SET_PDU_INFO_2LONG_IND(frmr_info, vzyxw);
242	FRMR_INFO_SET_PDU_INVALID_Nr_IND(frmr_info, vzyxw);
243	FRMR_INFO_SET_PDU_INVALID_Ns_IND(frmr_info, vzyxw);
244	skb_put(skb, sizeof(struct llc_frmr_info));
245}
246
247/**
248 *	llc_pdu_init_as_rr_rsp - builds RR response pdu
249 *	@skb: Address of the skb to build
250 *	@f_bit: The F bit to set in the PDU
251 *	@nr: The seq. number of the expected data PDU from the remote
252 *
253 *	Builds a pdu frame as an RR response.
254 */
255void llc_pdu_init_as_rr_rsp(struct sk_buff *skb, u8 f_bit, u8 nr)
256{
257	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
258
259	pdu->ctrl_1  = LLC_PDU_TYPE_S;
260	pdu->ctrl_1 |= LLC_2_PDU_RSP_RR;
261	pdu->ctrl_2  = 0;
262	pdu->ctrl_2 |= f_bit & LLC_S_PF_BIT_MASK;
263	pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
264	pdu->ctrl_2 |= (nr << 1) & 0xFE;  /* set N(R) in bits 10..16 */
265}
266
267/**
268 *	llc_pdu_init_as_rej_rsp - builds REJ response pdu
269 *	@skb: Address of the skb to build
270 *	@f_bit: The F bit to set in the PDU
271 *	@nr: The seq. number of the expected data PDU from the remote
272 *
273 *	Builds a pdu frame as a REJ response.
274 */
275void llc_pdu_init_as_rej_rsp(struct sk_buff *skb, u8 f_bit, u8 nr)
276{
277	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
278
279	pdu->ctrl_1  = LLC_PDU_TYPE_S;
280	pdu->ctrl_1 |= LLC_2_PDU_RSP_REJ;
281	pdu->ctrl_2  = 0;
282	pdu->ctrl_2 |= f_bit & LLC_S_PF_BIT_MASK;
283	pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
284	pdu->ctrl_2 |= (nr << 1) & 0xFE;  /* set N(R) in bits 10..16 */
285}
286
287/**
288 *	llc_pdu_init_as_rnr_rsp - builds RNR response pdu
289 *	@skb: Address of the frame to build
290 *	@f_bit: The F bit to set in the PDU
291 *	@nr: The seq. number of the expected data PDU from the remote
292 *
293 *	Builds a pdu frame as an RNR response.
294 */
295void llc_pdu_init_as_rnr_rsp(struct sk_buff *skb, u8 f_bit, u8 nr)
296{
297	struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
298
299	pdu->ctrl_1  = LLC_PDU_TYPE_S;
300	pdu->ctrl_1 |= LLC_2_PDU_RSP_RNR;
301	pdu->ctrl_2  = 0;
302	pdu->ctrl_2 |= f_bit & LLC_S_PF_BIT_MASK;
303	pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
304	pdu->ctrl_2 |= (nr << 1) & 0xFE;  /* set N(R) in bits 10..16 */
305}
306
307/**
308 *	llc_pdu_init_as_ua_rsp - builds UA response pdu
309 *	@skb: Address of the frame to build
310 *	@f_bit: The F bit to set in the PDU
311 *
312 *	Builds a pdu frame as a UA response.
313 */
314void llc_pdu_init_as_ua_rsp(struct sk_buff *skb, u8 f_bit)
315{
316	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
317
318	pdu->ctrl_1  = LLC_PDU_TYPE_U;
319	pdu->ctrl_1 |= LLC_2_PDU_RSP_UA;
320	pdu->ctrl_1 |= ((f_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
321}
322
323/**
324 *	llc_pdu_decode_pdu_type - designates PDU type
325 *	@skb: input skb that type of it must be designated.
326 *	@type: type of PDU (output argument).
327 *
328 *	This function designates type of PDU (I, S or U).
329 */
330static void llc_pdu_decode_pdu_type(struct sk_buff *skb, u8 *type)
331{
332	struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
333
334	if (pdu->ctrl_1 & 1) {
335		if ((pdu->ctrl_1 & LLC_PDU_TYPE_U) == LLC_PDU_TYPE_U)
336			*type = LLC_PDU_TYPE_U;
337		else
338			*type = LLC_PDU_TYPE_S;
339	} else
340		*type = LLC_PDU_TYPE_I;
341}
342
343/**
344 *	llc_pdu_get_pf_bit - extracts p/f bit of input PDU
345 *	@pdu: pointer to LLC header.
346 *
347 *	This function extracts p/f bit of input PDU. at first examines type of
348 *	PDU and then extracts p/f bit. Returns the p/f bit.
349 */
350static u8 llc_pdu_get_pf_bit(struct llc_pdu_sn *pdu)
351{
352	u8 pdu_type;
353	u8 pf_bit = 0;
354
355	if (pdu->ctrl_1 & 1) {
356		if ((pdu->ctrl_1 & LLC_PDU_TYPE_U) == LLC_PDU_TYPE_U)
357			pdu_type = LLC_PDU_TYPE_U;
358		else
359			pdu_type = LLC_PDU_TYPE_S;
360	} else
361		pdu_type = LLC_PDU_TYPE_I;
362	switch (pdu_type) {
363	case LLC_PDU_TYPE_I:
364	case LLC_PDU_TYPE_S:
365		pf_bit = pdu->ctrl_2 & LLC_S_PF_BIT_MASK;
366		break;
367	case LLC_PDU_TYPE_U:
368		pf_bit = (pdu->ctrl_1 & LLC_U_PF_BIT_MASK) >> 4;
369		break;
370	}
371	return pf_bit;
372}
373