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
18 static void llc_pdu_decode_pdu_type(struct sk_buff *skb, u8 *type);
19 static u8 llc_pdu_get_pf_bit(struct llc_pdu_sn *pdu);
20
21 void 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 */
35 void 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 */
63 void 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 */
89 void 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 */
107 void 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 */
126 void 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 */
146 void 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 */
166 void 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 */
184 void 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 */
200 void 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 */
220 void 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 */
255 void 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 */
275 void 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 */
295 void 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 */
314 void 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 */
330 static 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 */
350 static 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
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