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_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, 5);
 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 }