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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 | // SPDX-License-Identifier: GPL-2.0-or-later /* * LAPB release 002 * * This code REQUIRES 2.1.15 or higher/ NET3.038 * * History * LAPB 001 Jonathan Naylor Started Coding */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/errno.h> #include <linux/types.h> #include <linux/socket.h> #include <linux/in.h> #include <linux/kernel.h> #include <linux/timer.h> #include <linux/string.h> #include <linux/sockios.h> #include <linux/net.h> #include <linux/inet.h> #include <linux/skbuff.h> #include <linux/slab.h> #include <net/sock.h> #include <linux/uaccess.h> #include <linux/fcntl.h> #include <linux/mm.h> #include <linux/interrupt.h> #include <net/lapb.h> /* * This routine purges all the queues of frames. */ void lapb_clear_queues(struct lapb_cb *lapb) { skb_queue_purge(&lapb->write_queue); skb_queue_purge(&lapb->ack_queue); } /* * This routine purges the input queue of those frames that have been * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the * SDL diagram. */ void lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr) { struct sk_buff *skb; int modulus; modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; /* * Remove all the ack-ed frames from the ack queue. */ if (lapb->va != nr) while (skb_peek(&lapb->ack_queue) && lapb->va != nr) { skb = skb_dequeue(&lapb->ack_queue); kfree_skb(skb); lapb->va = (lapb->va + 1) % modulus; } } void lapb_requeue_frames(struct lapb_cb *lapb) { struct sk_buff *skb, *skb_prev = NULL; /* * Requeue all the un-ack-ed frames on the output queue to be picked * up by lapb_kick called from the timer. This arrangement handles the * possibility of an empty output queue. */ while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) { if (!skb_prev) skb_queue_head(&lapb->write_queue, skb); else skb_append(skb_prev, skb, &lapb->write_queue); skb_prev = skb; } } /* * Validate that the value of nr is between va and vs. Return true or * false for testing. */ int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr) { unsigned short vc = lapb->va; int modulus; modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS; while (vc != lapb->vs) { if (nr == vc) return 1; vc = (vc + 1) % modulus; } return nr == lapb->vs; } /* * This routine is the centralised routine for parsing the control * information for the different frame formats. */ int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb, struct lapb_frame *frame) { frame->type = LAPB_ILLEGAL; lapb_dbg(2, "(%p) S%d RX %3ph\n", lapb->dev, lapb->state, skb->data); /* We always need to look at 2 bytes, sometimes we need * to look at 3 and those cases are handled below. */ if (!pskb_may_pull(skb, 2)) return -1; if (lapb->mode & LAPB_MLP) { if (lapb->mode & LAPB_DCE) { if (skb->data[0] == LAPB_ADDR_D) frame->cr = LAPB_COMMAND; if (skb->data[0] == LAPB_ADDR_C) frame->cr = LAPB_RESPONSE; } else { if (skb->data[0] == LAPB_ADDR_C) frame->cr = LAPB_COMMAND; if (skb->data[0] == LAPB_ADDR_D) frame->cr = LAPB_RESPONSE; } } else { if (lapb->mode & LAPB_DCE) { if (skb->data[0] == LAPB_ADDR_B) frame->cr = LAPB_COMMAND; if (skb->data[0] == LAPB_ADDR_A) frame->cr = LAPB_RESPONSE; } else { if (skb->data[0] == LAPB_ADDR_A) frame->cr = LAPB_COMMAND; if (skb->data[0] == LAPB_ADDR_B) frame->cr = LAPB_RESPONSE; } } skb_pull(skb, 1); if (lapb->mode & LAPB_EXTENDED) { if (!(skb->data[0] & LAPB_S)) { if (!pskb_may_pull(skb, 2)) return -1; /* * I frame - carries NR/NS/PF */ frame->type = LAPB_I; frame->ns = (skb->data[0] >> 1) & 0x7F; frame->nr = (skb->data[1] >> 1) & 0x7F; frame->pf = skb->data[1] & LAPB_EPF; frame->control[0] = skb->data[0]; frame->control[1] = skb->data[1]; skb_pull(skb, 2); } else if ((skb->data[0] & LAPB_U) == 1) { if (!pskb_may_pull(skb, 2)) return -1; /* * S frame - take out PF/NR */ frame->type = skb->data[0] & 0x0F; frame->nr = (skb->data[1] >> 1) & 0x7F; frame->pf = skb->data[1] & LAPB_EPF; frame->control[0] = skb->data[0]; frame->control[1] = skb->data[1]; skb_pull(skb, 2); } else if ((skb->data[0] & LAPB_U) == 3) { /* * U frame - take out PF */ frame->type = skb->data[0] & ~LAPB_SPF; frame->pf = skb->data[0] & LAPB_SPF; frame->control[0] = skb->data[0]; frame->control[1] = 0x00; skb_pull(skb, 1); } } else { if (!(skb->data[0] & LAPB_S)) { /* * I frame - carries NR/NS/PF */ frame->type = LAPB_I; frame->ns = (skb->data[0] >> 1) & 0x07; frame->nr = (skb->data[0] >> 5) & 0x07; frame->pf = skb->data[0] & LAPB_SPF; } else if ((skb->data[0] & LAPB_U) == 1) { /* * S frame - take out PF/NR */ frame->type = skb->data[0] & 0x0F; frame->nr = (skb->data[0] >> 5) & 0x07; frame->pf = skb->data[0] & LAPB_SPF; } else if ((skb->data[0] & LAPB_U) == 3) { /* * U frame - take out PF */ frame->type = skb->data[0] & ~LAPB_SPF; frame->pf = skb->data[0] & LAPB_SPF; } frame->control[0] = skb->data[0]; skb_pull(skb, 1); } return 0; } /* * This routine is called when the HDLC layer internally generates a * command or response for the remote machine ( eg. RR, UA etc. ). * Only supervisory or unnumbered frames are processed, FRMRs are handled * by lapb_transmit_frmr below. */ void lapb_send_control(struct lapb_cb *lapb, int frametype, int poll_bit, int type) { struct sk_buff *skb; unsigned char *dptr; if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL) return; skb_reserve(skb, LAPB_HEADER_LEN + 1); if (lapb->mode & LAPB_EXTENDED) { if ((frametype & LAPB_U) == LAPB_U) { dptr = skb_put(skb, 1); *dptr = frametype; *dptr |= poll_bit ? LAPB_SPF : 0; } else { dptr = skb_put(skb, 2); dptr[0] = frametype; dptr[1] = (lapb->vr << 1); dptr[1] |= poll_bit ? LAPB_EPF : 0; } } else { dptr = skb_put(skb, 1); *dptr = frametype; *dptr |= poll_bit ? LAPB_SPF : 0; if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */ *dptr |= (lapb->vr << 5); } lapb_transmit_buffer(lapb, skb, type); } /* * This routine generates FRMRs based on information previously stored in * the LAPB control block. */ void lapb_transmit_frmr(struct lapb_cb *lapb) { struct sk_buff *skb; unsigned char *dptr; if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL) return; skb_reserve(skb, LAPB_HEADER_LEN + 1); if (lapb->mode & LAPB_EXTENDED) { dptr = skb_put(skb, 6); *dptr++ = LAPB_FRMR; *dptr++ = lapb->frmr_data.control[0]; *dptr++ = lapb->frmr_data.control[1]; *dptr++ = (lapb->vs << 1) & 0xFE; *dptr = (lapb->vr << 1) & 0xFE; if (lapb->frmr_data.cr == LAPB_RESPONSE) *dptr |= 0x01; dptr++; *dptr++ = lapb->frmr_type; lapb_dbg(1, "(%p) S%d TX FRMR %5ph\n", lapb->dev, lapb->state, &skb->data[1]); } else { dptr = skb_put(skb, 4); *dptr++ = LAPB_FRMR; *dptr++ = lapb->frmr_data.control[0]; *dptr = (lapb->vs << 1) & 0x0E; *dptr |= (lapb->vr << 5) & 0xE0; if (lapb->frmr_data.cr == LAPB_RESPONSE) *dptr |= 0x10; dptr++; *dptr++ = lapb->frmr_type; lapb_dbg(1, "(%p) S%d TX FRMR %3ph\n", lapb->dev, lapb->state, &skb->data[1]); } lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE); } |