net/llc/llc_pdu.c

   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  *      pdu_set_pf_bit - sets poll/final bit in LLC header
  28  *      @pdu_frame: input frame that p/f bit must be set into it.
  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_decode_cr_bit - extracts command response bit from LLC header
  84  *      @skb: input skb that c/r bit must be extracted from it.
  85  *      @cr_bit: command/response bit (0 or 1).
  86  *
  87  *      This function extracts command/response bit from LLC header. this bit
  88  *      is right bit of source SAP.
  89  */
  90 void llc_pdu_decode_cr_bit(struct sk_buff *skb, u8 *cr_bit)
  91 {
  92         *cr_bit = llc_pdu_un_hdr(skb)->ssap & LLC_PDU_CMD_RSP_MASK;
  93 }
  94
  95 /**
  96  *      llc_pdu_init_as_disc_cmd - Builds DISC PDU
  97  *      @skb: Address of the skb to build
  98  *      @p_bit: The P bit to set in the PDU
  99  *
 100  *      Builds a pdu frame as a DISC command.
 101  */
 102 void llc_pdu_init_as_disc_cmd(struct sk_buff *skb, u8 p_bit)
 103 {
 104         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 105
 106         pdu->ctrl_1  = LLC_PDU_TYPE_U;
 107         pdu->ctrl_1 |= LLC_2_PDU_CMD_DISC;
 108         pdu->ctrl_1 |= ((p_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
 109 }
 110
 111 /**
 112  *      llc_pdu_init_as_i_cmd - builds I pdu
 113  *      @skb: Address of the skb to build
 114  *      @p_bit: The P bit to set in the PDU
 115  *      @ns: The sequence number of the data PDU
 116  *      @nr: The seq. number of the expected I PDU from the remote
 117  *
 118  *      Builds a pdu frame as an I command.
 119  */
 120 void llc_pdu_init_as_i_cmd(struct sk_buff *skb, u8 p_bit, u8 ns, u8 nr)
 121 {
 122         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 123
 124         pdu->ctrl_1  = LLC_PDU_TYPE_I;
 125         pdu->ctrl_2  = 0;
 126         pdu->ctrl_2 |= (p_bit & LLC_I_PF_BIT_MASK); /* p/f bit */
 127         pdu->ctrl_1 |= (ns << 1) & 0xFE;   /* set N(S) in bits 2..8 */
 128         pdu->ctrl_2 |= (nr << 1) & 0xFE;   /* set N(R) in bits 10..16 */
 129 }
 130
 131 /**
 132  *      llc_pdu_init_as_rej_cmd - builds REJ PDU
 133  *      @skb: Address of the skb to build
 134  *      @p_bit: The P bit to set in the PDU
 135  *      @nr: The seq. number of the expected I PDU from the remote
 136  *
 137  *      Builds a pdu frame as a REJ command.
 138  */
 139 void llc_pdu_init_as_rej_cmd(struct sk_buff *skb, u8 p_bit, u8 nr)
 140 {
 141         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 142
 143         pdu->ctrl_1  = LLC_PDU_TYPE_S;
 144         pdu->ctrl_1 |= LLC_2_PDU_CMD_REJ;
 145         pdu->ctrl_2  = 0;
 146         pdu->ctrl_2 |= p_bit & LLC_S_PF_BIT_MASK;
 147         pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
 148         pdu->ctrl_2 |= (nr << 1) & 0xFE; /* set N(R) in bits 10..16 */
 149 }
 150
 151 /**
 152  *      llc_pdu_init_as_rnr_cmd - builds RNR pdu
 153  *      @skb: Address of the skb to build
 154  *      @p_bit: The P bit to set in the PDU
 155  *      @nr: The seq. number of the expected I PDU from the remote
 156  *
 157  *      Builds a pdu frame as an RNR command.
 158  */
 159 void llc_pdu_init_as_rnr_cmd(struct sk_buff *skb, u8 p_bit, u8 nr)
 160 {
 161         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 162
 163         pdu->ctrl_1  = LLC_PDU_TYPE_S;
 164         pdu->ctrl_1 |= LLC_2_PDU_CMD_RNR;
 165         pdu->ctrl_2  = 0;
 166         pdu->ctrl_2 |= p_bit & LLC_S_PF_BIT_MASK;
 167         pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
 168         pdu->ctrl_2 |= (nr << 1) & 0xFE; /* set N(R) in bits 10..16 */
 169 }
 170
 171 /**
 172  *      llc_pdu_init_as_rr_cmd - Builds RR pdu
 173  *      @skb: Address of the skb to build
 174  *      @p_bit: The P bit to set in the PDU
 175  *      @nr: The seq. number of the expected I PDU from the remote
 176  *
 177  *      Builds a pdu frame as an RR command.
 178  */
 179 void llc_pdu_init_as_rr_cmd(struct sk_buff *skb, u8 p_bit, u8 nr)
 180 {
 181         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 182
 183         pdu->ctrl_1  = LLC_PDU_TYPE_S;
 184         pdu->ctrl_1 |= LLC_2_PDU_CMD_RR;
 185         pdu->ctrl_2  = p_bit & LLC_S_PF_BIT_MASK;
 186         pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
 187         pdu->ctrl_2 |= (nr << 1) & 0xFE; /* set N(R) in bits 10..16 */
 188 }
 189
 190 /**
 191  *      llc_pdu_init_as_sabme_cmd - builds SABME pdu
 192  *      @skb: Address of the skb to build
 193  *      @p_bit: The P bit to set in the PDU
 194  *
 195  *      Builds a pdu frame as an SABME command.
 196  */
 197 void llc_pdu_init_as_sabme_cmd(struct sk_buff *skb, u8 p_bit)
 198 {
 199         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 200
 201         pdu->ctrl_1  = LLC_PDU_TYPE_U;
 202         pdu->ctrl_1 |= LLC_2_PDU_CMD_SABME;
 203         pdu->ctrl_1 |= ((p_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
 204 }
 205
 206 /**
 207  *      llc_pdu_init_as_dm_rsp - builds DM response pdu
 208  *      @skb: Address of the skb to build
 209  *      @f_bit: The F bit to set in the PDU
 210  *
 211  *      Builds a pdu frame as a DM response.
 212  */
 213 void llc_pdu_init_as_dm_rsp(struct sk_buff *skb, u8 f_bit)
 214 {
 215         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 216
 217         pdu->ctrl_1  = LLC_PDU_TYPE_U;
 218         pdu->ctrl_1 |= LLC_2_PDU_RSP_DM;
 219         pdu->ctrl_1 |= ((f_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
 220 }
 221
 222 /**
 223  *      llc_pdu_init_as_frmr_rsp - builds FRMR response PDU
 224  *      @skb: Address of the frame to build
 225  *      @prev_pdu: The rejected PDU frame
 226  *      @f_bit: The F bit to set in the PDU
 227  *      @vs: tx state vari value for the data link conn at the rejecting LLC
 228  *      @vr: rx state var value for the data link conn at the rejecting LLC
 229  *      @vzyxw: completely described in the IEEE Std 802.2 document (Pg 55)
 230  *
 231  *      Builds a pdu frame as a FRMR response.
 232  */
 233 void llc_pdu_init_as_frmr_rsp(struct sk_buff *skb, struct llc_pdu_sn *prev_pdu,
 234                               u8 f_bit, u8 vs, u8 vr, u8 vzyxw)
 235 {
 236         struct llc_frmr_info *frmr_info;
 237         u8 prev_pf = 0;
 238         u8 *ctrl;
 239         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 240
 241         pdu->ctrl_1  = LLC_PDU_TYPE_U;
 242         pdu->ctrl_1 |= LLC_2_PDU_RSP_FRMR;
 243         pdu->ctrl_1 |= ((f_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
 244
 245         frmr_info = (struct llc_frmr_info *)&pdu->ctrl_2;
 246         ctrl = (u8 *)&prev_pdu->ctrl_1;
 247         FRMR_INFO_SET_REJ_CNTRL(frmr_info,ctrl);
 248         FRMR_INFO_SET_Vs(frmr_info, vs);
 249         FRMR_INFO_SET_Vr(frmr_info, vr);
 250         prev_pf = llc_pdu_get_pf_bit(prev_pdu);
 251         FRMR_INFO_SET_C_R_BIT(frmr_info, prev_pf);
 252         FRMR_INFO_SET_INVALID_PDU_CTRL_IND(frmr_info, vzyxw);
 253         FRMR_INFO_SET_INVALID_PDU_INFO_IND(frmr_info, vzyxw);
 254         FRMR_INFO_SET_PDU_INFO_2LONG_IND(frmr_info, vzyxw);
 255         FRMR_INFO_SET_PDU_INVALID_Nr_IND(frmr_info, vzyxw);
 256         FRMR_INFO_SET_PDU_INVALID_Ns_IND(frmr_info, vzyxw);
 257         skb_put(skb, 5);
 258 }
 259
 260 /**
 261  *      llc_pdu_init_as_rr_rsp - builds RR response pdu
 262  *      @skb: Address of the skb to build
 263  *      @f_bit: The F bit to set in the PDU
 264  *      @nr: The seq. number of the expected data PDU from the remote
 265  *
 266  *      Builds a pdu frame as an RR response.
 267  */
 268 void llc_pdu_init_as_rr_rsp(struct sk_buff *skb, u8 f_bit, u8 nr)
 269 {
 270         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 271
 272         pdu->ctrl_1  = LLC_PDU_TYPE_S;
 273         pdu->ctrl_1 |= LLC_2_PDU_RSP_RR;
 274         pdu->ctrl_2  = 0;
 275         pdu->ctrl_2 |= f_bit & LLC_S_PF_BIT_MASK;
 276         pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
 277         pdu->ctrl_2 |= (nr << 1) & 0xFE;  /* set N(R) in bits 10..16 */
 278 }
 279
 280 /**
 281  *      llc_pdu_init_as_rej_rsp - builds REJ response pdu
 282  *      @skb: Address of the skb to build
 283  *      @f_bit: The F bit to set in the PDU
 284  *      @nr: The seq. number of the expected data PDU from the remote
 285  *
 286  *      Builds a pdu frame as a REJ response.
 287  */
 288 void llc_pdu_init_as_rej_rsp(struct sk_buff *skb, u8 f_bit, u8 nr)
 289 {
 290         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 291
 292         pdu->ctrl_1  = LLC_PDU_TYPE_S;
 293         pdu->ctrl_1 |= LLC_2_PDU_RSP_REJ;
 294         pdu->ctrl_2  = 0;
 295         pdu->ctrl_2 |= f_bit & LLC_S_PF_BIT_MASK;
 296         pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
 297         pdu->ctrl_2 |= (nr << 1) & 0xFE;  /* set N(R) in bits 10..16 */
 298 }
 299
 300 /**
 301  *      llc_pdu_init_as_rnr_rsp - builds RNR response pdu
 302  *      @skb: Address of the frame to build
 303  *      @f_bit: The F bit to set in the PDU
 304  *      @nr: The seq. number of the expected data PDU from the remote
 305  *
 306  *      Builds a pdu frame as an RNR response.
 307  */
 308 void llc_pdu_init_as_rnr_rsp(struct sk_buff *skb, u8 f_bit, u8 nr)
 309 {
 310         struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
 311
 312         pdu->ctrl_1  = LLC_PDU_TYPE_S;
 313         pdu->ctrl_1 |= LLC_2_PDU_RSP_RNR;
 314         pdu->ctrl_2  = 0;
 315         pdu->ctrl_2 |= f_bit & LLC_S_PF_BIT_MASK;
 316         pdu->ctrl_1 &= 0x0F;    /* setting bits 5..8 to zero(reserved) */
 317         pdu->ctrl_2 |= (nr << 1) & 0xFE;  /* set N(R) in bits 10..16 */
 318 }
 319
 320 /**
 321  *      llc_pdu_init_as_ua_rsp - builds UA response pdu
 322  *      @skb: Address of the frame to build
 323  *      @f_bit: The F bit to set in the PDU
 324  *
 325  *      Builds a pdu frame as a UA response.
 326  */
 327 void llc_pdu_init_as_ua_rsp(struct sk_buff *skb, u8 f_bit)
 328 {
 329         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 330
 331         pdu->ctrl_1  = LLC_PDU_TYPE_U;
 332         pdu->ctrl_1 |= LLC_2_PDU_RSP_UA;
 333         pdu->ctrl_1 |= ((f_bit & 1) << 4) & LLC_U_PF_BIT_MASK;
 334 }
 335
 336 /**
 337  *      llc_pdu_decode_pdu_type - designates PDU type
 338  *      @skb: input skb that type of it must be designated.
 339  *      @type: type of PDU (output argument).
 340  *
 341  *      This function designates type of PDU (I, S or U).
 342  */
 343 static void llc_pdu_decode_pdu_type(struct sk_buff *skb, u8 *type)
 344 {
 345         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
 346
 347         if (pdu->ctrl_1 & 1) {
 348                 if ((pdu->ctrl_1 & LLC_PDU_TYPE_U) == LLC_PDU_TYPE_U)
 349                         *type = LLC_PDU_TYPE_U;
 350                 else
 351                         *type = LLC_PDU_TYPE_S;
 352         } else
 353                 *type = LLC_PDU_TYPE_I;
 354 }
 355
 356 /**
 357  *      llc_pdu_get_pf_bit - extracts p/f bit of input PDU
 358  *      @pdu: pointer to LLC header.
 359  *
 360  *      This function extracts p/f bit of input PDU. at first examines type of
 361  *      PDU and then extracts p/f bit. Returns the p/f bit.
 362  */
 363 static u8 llc_pdu_get_pf_bit(struct llc_pdu_sn *pdu)
 364 {
 365         u8 pdu_type;
 366         u8 pf_bit = 0;
 367
 368         if (pdu->ctrl_1 & 1) {
 369                 if ((pdu->ctrl_1 & LLC_PDU_TYPE_U) == LLC_PDU_TYPE_U)
 370                         pdu_type = LLC_PDU_TYPE_U;
 371                 else
 372                         pdu_type = LLC_PDU_TYPE_S;
 373         } else
 374                 pdu_type = LLC_PDU_TYPE_I;
 375         switch (pdu_type) {
 376         case LLC_PDU_TYPE_I:
 377         case LLC_PDU_TYPE_S:
 378                 pf_bit = pdu->ctrl_2 & LLC_S_PF_BIT_MASK;
 379                 break;
 380         case LLC_PDU_TYPE_U:
 381                 pf_bit = (pdu->ctrl_1 & LLC_U_PF_BIT_MASK) >> 4;
 382                 break;
 383         }
 384         return pf_bit;
 385 }