4 * This code REQUIRES 2.1.15 or higher/ NET3.038
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.
13 * LAPB 001 Jonathan Naylor Started Coding
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 #include <linux/errno.h>
19 #include <linux/types.h>
20 #include <linux/socket.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>
31 #include <asm/uaccess.h>
32 #include <linux/fcntl.h>
34 #include <linux/interrupt.h>
38 * This routine purges all the queues of frames.
40 void lapb_clear_queues(struct lapb_cb *lapb)
42 skb_queue_purge(&lapb->write_queue);
43 skb_queue_purge(&lapb->ack_queue);
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
51 void lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr)
56 modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
59 * Remove all the ack-ed frames from the ack queue.
62 while (skb_peek(&lapb->ack_queue) && lapb->va != nr) {
63 skb = skb_dequeue(&lapb->ack_queue);
65 lapb->va = (lapb->va + 1) % modulus;
69 void lapb_requeue_frames(struct lapb_cb *lapb)
71 struct sk_buff *skb, *skb_prev = NULL;
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.
78 while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
80 skb_queue_head(&lapb->write_queue, skb);
82 skb_append(skb_prev, skb, &lapb->write_queue);
88 * Validate that the value of nr is between va and vs. Return true or
91 int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr)
93 unsigned short vc = lapb->va;
96 modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
98 while (vc != lapb->vs) {
101 vc = (vc + 1) % modulus;
104 return nr == lapb->vs;
108 * This routine is the centralised routine for parsing the control
109 * information for the different frame formats.
111 int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb,
112 struct lapb_frame *frame)
114 frame->type = LAPB_ILLEGAL;
116 lapb_dbg(2, "(%p) S%d RX %3ph\n", lapb->dev, lapb->state, skb->data);
118 /* We always need to look at 2 bytes, sometimes we need
119 * to look at 3 and those cases are handled below.
121 if (!pskb_may_pull(skb, 2))
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;
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;
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;
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;
152 if (lapb->mode & LAPB_EXTENDED) {
153 if (!(skb->data[0] & LAPB_S)) {
154 if (!pskb_may_pull(skb, 2))
157 * I frame - carries NR/NS/PF
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];
166 } else if ((skb->data[0] & LAPB_U) == 1) {
167 if (!pskb_may_pull(skb, 2))
170 * S frame - take out PF/NR
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];
178 } else if ((skb->data[0] & LAPB_U) == 3) {
180 * U frame - take out PF
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;
189 if (!(skb->data[0] & LAPB_S)) {
191 * I frame - carries NR/NS/PF
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) {
199 * S frame - take out PF/NR
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) {
206 * U frame - take out PF
208 frame->type = skb->data[0] & ~LAPB_SPF;
209 frame->pf = skb->data[0] & LAPB_SPF;
212 frame->control[0] = skb->data[0];
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.
226 void lapb_send_control(struct lapb_cb *lapb, int frametype,
227 int poll_bit, int type)
232 if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
235 skb_reserve(skb, LAPB_HEADER_LEN + 1);
237 if (lapb->mode & LAPB_EXTENDED) {
238 if ((frametype & LAPB_U) == LAPB_U) {
239 dptr = skb_put(skb, 1);
241 *dptr |= poll_bit ? LAPB_SPF : 0;
243 dptr = skb_put(skb, 2);
245 dptr[1] = (lapb->vr << 1);
246 dptr[1] |= poll_bit ? LAPB_EPF : 0;
249 dptr = skb_put(skb, 1);
251 *dptr |= poll_bit ? LAPB_SPF : 0;
252 if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */
253 *dptr |= (lapb->vr << 5);
256 lapb_transmit_buffer(lapb, skb, type);
260 * This routine generates FRMRs based on information previously stored in
261 * the LAPB control block.
263 void lapb_transmit_frmr(struct lapb_cb *lapb)
268 if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL)
271 skb_reserve(skb, LAPB_HEADER_LEN + 1);
273 if (lapb->mode & LAPB_EXTENDED) {
274 dptr = skb_put(skb, 6);
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)
283 *dptr++ = lapb->frmr_type;
285 lapb_dbg(1, "(%p) S%d TX FRMR %5ph\n",
286 lapb->dev, lapb->state,
289 dptr = skb_put(skb, 4);
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)
297 *dptr++ = lapb->frmr_type;
299 lapb_dbg(1, "(%p) S%d TX FRMR %3ph\n",
300 lapb->dev, lapb->state, &skb->data[1]);
303 lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE);