1 /* 2 * LAPB release 002 3 * 4 * This code REQUIRES 2.1.15 or higher/ NET3.038 5 * 6 * This module: 7 * This module is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 * 12 * History 13 * LAPB 001 Jonathan Naylor Started Coding 14 */ 15 16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 17 18 #include <linux/errno.h> 19 #include <linux/types.h> 20 #include <linux/socket.h> 21 #include <linux/in.h> 22 #include <linux/kernel.h> 23 #include <linux/timer.h> 24 #include <linux/string.h> 25 #include <linux/sockios.h> 26 #include <linux/net.h> 27 #include <linux/inet.h> 28 #include <linux/skbuff.h> 29 #include <linux/slab.h> 30 #include <net/sock.h> 31 #include <asm/uaccess.h> 32 #include <linux/fcntl.h> 33 #include <linux/mm.h> 34 #include <linux/interrupt.h> 35 #include <net/lapb.h> 36 37 /* 38 * This routine purges all the queues of frames. 39 */ 40 void lapb_clear_queues(struct lapb_cb *lapb) 41 { 42 skb_queue_purge(&lapb->write_queue); 43 skb_queue_purge(&lapb->ack_queue); 44 } 45 46 /* 47 * This routine purges the input queue of those frames that have been 48 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the 49 * SDL diagram. 50 */ 51 void lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr) 52 { 53 struct sk_buff *skb; 54 int modulus; 55 56 modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; 57 58 /* 59 * Remove all the ack-ed frames from the ack queue. 60 */ 61 if (lapb->va != nr) 62 while (skb_peek(&lapb->ack_queue) && lapb->va != nr) { 63 skb = skb_dequeue(&lapb->ack_queue); 64 kfree_skb(skb); 65 lapb->va = (lapb->va + 1) % modulus; 66 } 67 } 68 69 void lapb_requeue_frames(struct lapb_cb *lapb) 70 { 71 struct sk_buff *skb, *skb_prev = NULL; 72 73 /* 74 * Requeue all the un-ack-ed frames on the output queue to be picked 75 * up by lapb_kick called from the timer. This arrangement handles the 76 * possibility of an empty output queue. 77 */ 78 while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) { 79 if (!skb_prev) 80 skb_queue_head(&lapb->write_queue, skb); 81 else 82 skb_append(skb_prev, skb, &lapb->write_queue); 83 skb_prev = skb; 84 } 85 } 86 87 /* 88 * Validate that the value of nr is between va and vs. Return true or 89 * false for testing. 90 */ 91 int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr) 92 { 93 unsigned short vc = lapb->va; 94 int modulus; 95 96 modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; 97 98 while (vc != lapb->vs) { 99 if (nr == vc) 100 return 1; 101 vc = (vc + 1) % modulus; 102 } 103 104 return nr == lapb->vs; 105 } 106 107 /* 108 * This routine is the centralised routine for parsing the control 109 * information for the different frame formats. 110 */ 111 int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb, 112 struct lapb_frame *frame) 113 { 114 frame->type = LAPB_ILLEGAL; 115 116 lapb_dbg(2, "(%p) S%d RX %3ph\n", lapb->dev, lapb->state, skb->data); 117 118 /* We always need to look at 2 bytes, sometimes we need 119 * to look at 3 and those cases are handled below. 120 */ 121 if (!pskb_may_pull(skb, 2)) 122 return -1; 123 124 if (lapb->mode & LAPB_MLP) { 125 if (lapb->mode & LAPB_DCE) { 126 if (skb->data[0] == LAPB_ADDR_D) 127 frame->cr = LAPB_COMMAND; 128 if (skb->data[0] == LAPB_ADDR_C) 129 frame->cr = LAPB_RESPONSE; 130 } else { 131 if (skb->data[0] == LAPB_ADDR_C) 132 frame->cr = LAPB_COMMAND; 133 if (skb->data[0] == LAPB_ADDR_D) 134 frame->cr = LAPB_RESPONSE; 135 } 136 } else { 137 if (lapb->mode & LAPB_DCE) { 138 if (skb->data[0] == LAPB_ADDR_B) 139 frame->cr = LAPB_COMMAND; 140 if (skb->data[0] == LAPB_ADDR_A) 141 frame->cr = LAPB_RESPONSE; 142 } else { 143 if (skb->data[0] == LAPB_ADDR_A) 144 frame->cr = LAPB_COMMAND; 145 if (skb->data[0] == LAPB_ADDR_B) 146 frame->cr = LAPB_RESPONSE; 147 } 148 } 149 150 skb_pull(skb, 1); 151 152 if (lapb->mode & LAPB_EXTENDED) { 153 if (!(skb->data[0] & LAPB_S)) { 154 if (!pskb_may_pull(skb, 2)) 155 return -1; 156 /* 157 * I frame - carries NR/NS/PF 158 */ 159 frame->type = LAPB_I; 160 frame->ns = (skb->data[0] >> 1) & 0x7F; 161 frame->nr = (skb->data[1] >> 1) & 0x7F; 162 frame->pf = skb->data[1] & LAPB_EPF; 163 frame->control[0] = skb->data[0]; 164 frame->control[1] = skb->data[1]; 165 skb_pull(skb, 2); 166 } else if ((skb->data[0] & LAPB_U) == 1) { 167 if (!pskb_may_pull(skb, 2)) 168 return -1; 169 /* 170 * S frame - take out PF/NR 171 */ 172 frame->type = skb->data[0] & 0x0F; 173 frame->nr = (skb->data[1] >> 1) & 0x7F; 174 frame->pf = skb->data[1] & LAPB_EPF; 175 frame->control[0] = skb->data[0]; 176 frame->control[1] = skb->data[1]; 177 skb_pull(skb, 2); 178 } else if ((skb->data[0] & LAPB_U) == 3) { 179 /* 180 * U frame - take out PF 181 */ 182 frame->type = skb->data[0] & ~LAPB_SPF; 183 frame->pf = skb->data[0] & LAPB_SPF; 184 frame->control[0] = skb->data[0]; 185 frame->control[1] = 0x00; 186 skb_pull(skb, 1); 187 } 188 } else { 189 if (!(skb->data[0] & LAPB_S)) { 190 /* 191 * I frame - carries NR/NS/PF 192 */ 193 frame->type = LAPB_I; 194 frame->ns = (skb->data[0] >> 1) & 0x07; 195 frame->nr = (skb->data[0] >> 5) & 0x07; 196 frame->pf = skb->data[0] & LAPB_SPF; 197 } else if ((skb->data[0] & LAPB_U) == 1) { 198 /* 199 * S frame - take out PF/NR 200 */ 201 frame->type = skb->data[0] & 0x0F; 202 frame->nr = (skb->data[0] >> 5) & 0x07; 203 frame->pf = skb->data[0] & LAPB_SPF; 204 } else if ((skb->data[0] & LAPB_U) == 3) { 205 /* 206 * U frame - take out PF 207 */ 208 frame->type = skb->data[0] & ~LAPB_SPF; 209 frame->pf = skb->data[0] & LAPB_SPF; 210 } 211 212 frame->control[0] = skb->data[0]; 213 214 skb_pull(skb, 1); 215 } 216 217 return 0; 218 } 219 220 /* 221 * This routine is called when the HDLC layer internally generates a 222 * command or response for the remote machine ( eg. RR, UA etc. ). 223 * Only supervisory or unnumbered frames are processed, FRMRs are handled 224 * by lapb_transmit_frmr below. 225 */ 226 void lapb_send_control(struct lapb_cb *lapb, int frametype, 227 int poll_bit, int type) 228 { 229 struct sk_buff *skb; 230 unsigned char *dptr; 231 232 if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL) 233 return; 234 235 skb_reserve(skb, LAPB_HEADER_LEN + 1); 236 237 if (lapb->mode & LAPB_EXTENDED) { 238 if ((frametype & LAPB_U) == LAPB_U) { 239 dptr = skb_put(skb, 1); 240 *dptr = frametype; 241 *dptr |= poll_bit ? LAPB_SPF : 0; 242 } else { 243 dptr = skb_put(skb, 2); 244 dptr[0] = frametype; 245 dptr[1] = (lapb->vr << 1); 246 dptr[1] |= poll_bit ? LAPB_EPF : 0; 247 } 248 } else { 249 dptr = skb_put(skb, 1); 250 *dptr = frametype; 251 *dptr |= poll_bit ? LAPB_SPF : 0; 252 if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */ 253 *dptr |= (lapb->vr << 5); 254 } 255 256 lapb_transmit_buffer(lapb, skb, type); 257 } 258 259 /* 260 * This routine generates FRMRs based on information previously stored in 261 * the LAPB control block. 262 */ 263 void lapb_transmit_frmr(struct lapb_cb *lapb) 264 { 265 struct sk_buff *skb; 266 unsigned char *dptr; 267 268 if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL) 269 return; 270 271 skb_reserve(skb, LAPB_HEADER_LEN + 1); 272 273 if (lapb->mode & LAPB_EXTENDED) { 274 dptr = skb_put(skb, 6); 275 *dptr++ = LAPB_FRMR; 276 *dptr++ = lapb->frmr_data.control[0]; 277 *dptr++ = lapb->frmr_data.control[1]; 278 *dptr++ = (lapb->vs << 1) & 0xFE; 279 *dptr = (lapb->vr << 1) & 0xFE; 280 if (lapb->frmr_data.cr == LAPB_RESPONSE) 281 *dptr |= 0x01; 282 dptr++; 283 *dptr++ = lapb->frmr_type; 284 285 lapb_dbg(1, "(%p) S%d TX FRMR %5ph\n", 286 lapb->dev, lapb->state, 287 &skb->data[1]); 288 } else { 289 dptr = skb_put(skb, 4); 290 *dptr++ = LAPB_FRMR; 291 *dptr++ = lapb->frmr_data.control[0]; 292 *dptr = (lapb->vs << 1) & 0x0E; 293 *dptr |= (lapb->vr << 5) & 0xE0; 294 if (lapb->frmr_data.cr == LAPB_RESPONSE) 295 *dptr |= 0x10; 296 dptr++; 297 *dptr++ = lapb->frmr_type; 298 299 lapb_dbg(1, "(%p) S%d TX FRMR %3ph\n", 300 lapb->dev, lapb->state, &skb->data[1]); 301 } 302 303 lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE); 304 } 305