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