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 %02X %02X %02X\n", 117 lapb->dev, lapb->state, 118 skb->data[0], skb->data[1], skb->data[2]); 119 120 /* We always need to look at 2 bytes, sometimes we need 121 * to look at 3 and those cases are handled below. 122 */ 123 if (!pskb_may_pull(skb, 2)) 124 return -1; 125 126 if (lapb->mode & LAPB_MLP) { 127 if (lapb->mode & LAPB_DCE) { 128 if (skb->data[0] == LAPB_ADDR_D) 129 frame->cr = LAPB_COMMAND; 130 if (skb->data[0] == LAPB_ADDR_C) 131 frame->cr = LAPB_RESPONSE; 132 } else { 133 if (skb->data[0] == LAPB_ADDR_C) 134 frame->cr = LAPB_COMMAND; 135 if (skb->data[0] == LAPB_ADDR_D) 136 frame->cr = LAPB_RESPONSE; 137 } 138 } else { 139 if (lapb->mode & LAPB_DCE) { 140 if (skb->data[0] == LAPB_ADDR_B) 141 frame->cr = LAPB_COMMAND; 142 if (skb->data[0] == LAPB_ADDR_A) 143 frame->cr = LAPB_RESPONSE; 144 } else { 145 if (skb->data[0] == LAPB_ADDR_A) 146 frame->cr = LAPB_COMMAND; 147 if (skb->data[0] == LAPB_ADDR_B) 148 frame->cr = LAPB_RESPONSE; 149 } 150 } 151 152 skb_pull(skb, 1); 153 154 if (lapb->mode & LAPB_EXTENDED) { 155 if (!(skb->data[0] & LAPB_S)) { 156 if (!pskb_may_pull(skb, 2)) 157 return -1; 158 /* 159 * I frame - carries NR/NS/PF 160 */ 161 frame->type = LAPB_I; 162 frame->ns = (skb->data[0] >> 1) & 0x7F; 163 frame->nr = (skb->data[1] >> 1) & 0x7F; 164 frame->pf = skb->data[1] & LAPB_EPF; 165 frame->control[0] = skb->data[0]; 166 frame->control[1] = skb->data[1]; 167 skb_pull(skb, 2); 168 } else if ((skb->data[0] & LAPB_U) == 1) { 169 if (!pskb_may_pull(skb, 2)) 170 return -1; 171 /* 172 * S frame - take out PF/NR 173 */ 174 frame->type = skb->data[0] & 0x0F; 175 frame->nr = (skb->data[1] >> 1) & 0x7F; 176 frame->pf = skb->data[1] & LAPB_EPF; 177 frame->control[0] = skb->data[0]; 178 frame->control[1] = skb->data[1]; 179 skb_pull(skb, 2); 180 } else if ((skb->data[0] & LAPB_U) == 3) { 181 /* 182 * U frame - take out PF 183 */ 184 frame->type = skb->data[0] & ~LAPB_SPF; 185 frame->pf = skb->data[0] & LAPB_SPF; 186 frame->control[0] = skb->data[0]; 187 frame->control[1] = 0x00; 188 skb_pull(skb, 1); 189 } 190 } else { 191 if (!(skb->data[0] & LAPB_S)) { 192 /* 193 * I frame - carries NR/NS/PF 194 */ 195 frame->type = LAPB_I; 196 frame->ns = (skb->data[0] >> 1) & 0x07; 197 frame->nr = (skb->data[0] >> 5) & 0x07; 198 frame->pf = skb->data[0] & LAPB_SPF; 199 } else if ((skb->data[0] & LAPB_U) == 1) { 200 /* 201 * S frame - take out PF/NR 202 */ 203 frame->type = skb->data[0] & 0x0F; 204 frame->nr = (skb->data[0] >> 5) & 0x07; 205 frame->pf = skb->data[0] & LAPB_SPF; 206 } else if ((skb->data[0] & LAPB_U) == 3) { 207 /* 208 * U frame - take out PF 209 */ 210 frame->type = skb->data[0] & ~LAPB_SPF; 211 frame->pf = skb->data[0] & LAPB_SPF; 212 } 213 214 frame->control[0] = skb->data[0]; 215 216 skb_pull(skb, 1); 217 } 218 219 return 0; 220 } 221 222 /* 223 * This routine is called when the HDLC layer internally generates a 224 * command or response for the remote machine ( eg. RR, UA etc. ). 225 * Only supervisory or unnumbered frames are processed, FRMRs are handled 226 * by lapb_transmit_frmr below. 227 */ 228 void lapb_send_control(struct lapb_cb *lapb, int frametype, 229 int poll_bit, int type) 230 { 231 struct sk_buff *skb; 232 unsigned char *dptr; 233 234 if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL) 235 return; 236 237 skb_reserve(skb, LAPB_HEADER_LEN + 1); 238 239 if (lapb->mode & LAPB_EXTENDED) { 240 if ((frametype & LAPB_U) == LAPB_U) { 241 dptr = skb_put(skb, 1); 242 *dptr = frametype; 243 *dptr |= poll_bit ? LAPB_SPF : 0; 244 } else { 245 dptr = skb_put(skb, 2); 246 dptr[0] = frametype; 247 dptr[1] = (lapb->vr << 1); 248 dptr[1] |= poll_bit ? LAPB_EPF : 0; 249 } 250 } else { 251 dptr = skb_put(skb, 1); 252 *dptr = frametype; 253 *dptr |= poll_bit ? LAPB_SPF : 0; 254 if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */ 255 *dptr |= (lapb->vr << 5); 256 } 257 258 lapb_transmit_buffer(lapb, skb, type); 259 } 260 261 /* 262 * This routine generates FRMRs based on information previously stored in 263 * the LAPB control block. 264 */ 265 void lapb_transmit_frmr(struct lapb_cb *lapb) 266 { 267 struct sk_buff *skb; 268 unsigned char *dptr; 269 270 if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL) 271 return; 272 273 skb_reserve(skb, LAPB_HEADER_LEN + 1); 274 275 if (lapb->mode & LAPB_EXTENDED) { 276 dptr = skb_put(skb, 6); 277 *dptr++ = LAPB_FRMR; 278 *dptr++ = lapb->frmr_data.control[0]; 279 *dptr++ = lapb->frmr_data.control[1]; 280 *dptr++ = (lapb->vs << 1) & 0xFE; 281 *dptr = (lapb->vr << 1) & 0xFE; 282 if (lapb->frmr_data.cr == LAPB_RESPONSE) 283 *dptr |= 0x01; 284 dptr++; 285 *dptr++ = lapb->frmr_type; 286 287 lapb_dbg(1, "(%p) S%d TX FRMR %02X %02X %02X %02X %02X\n", 288 lapb->dev, lapb->state, 289 skb->data[1], skb->data[2], skb->data[3], 290 skb->data[4], skb->data[5]); 291 } else { 292 dptr = skb_put(skb, 4); 293 *dptr++ = LAPB_FRMR; 294 *dptr++ = lapb->frmr_data.control[0]; 295 *dptr = (lapb->vs << 1) & 0x0E; 296 *dptr |= (lapb->vr << 5) & 0xE0; 297 if (lapb->frmr_data.cr == LAPB_RESPONSE) 298 *dptr |= 0x10; 299 dptr++; 300 *dptr++ = lapb->frmr_type; 301 302 lapb_dbg(1, "(%p) S%d TX FRMR %02X %02X %02X\n", 303 lapb->dev, lapb->state, skb->data[1], 304 skb->data[2], skb->data[3]); 305 } 306 307 lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE); 308 } 309