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 * LAPB 002 Jonathan Naylor New timer architecture.
15 */
16
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/socket.h>
20 #include <linux/in.h>
21 #include <linux/kernel.h>
22 #include <linux/timer.h>
23 #include <linux/string.h>
24 #include <linux/sockios.h>
25 #include <linux/net.h>
26 #include <linux/inet.h>
27 #include <linux/skbuff.h>
28 #include <net/sock.h>
29 #include <asm/uaccess.h>
30 #include <asm/system.h>
31 #include <linux/fcntl.h>
32 #include <linux/mm.h>
33 #include <linux/interrupt.h>
34 #include <net/lapb.h>
35
36 /*
37 * This procedure is passed a buffer descriptor for an iframe. It builds
38 * the rest of the control part of the frame and then writes it out.
39 */
40 static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
41 {
42 unsigned char *frame;
43
44 if (!skb)
45 return;
46
47 if (lapb->mode & LAPB_EXTENDED) {
48 frame = skb_push(skb, 2);
49
50 frame[0] = LAPB_I;
51 frame[0] |= lapb->vs << 1;
52 frame[1] = poll_bit ? LAPB_EPF : 0;
53 frame[1] |= lapb->vr << 1;
54 } else {
55 frame = skb_push(skb, 1);
56
57 *frame = LAPB_I;
58 *frame |= poll_bit ? LAPB_SPF : 0;
59 *frame |= lapb->vr << 5;
60 *frame |= lapb->vs << 1;
61 }
62
63 #if LAPB_DEBUG > 1
64 printk(KERN_DEBUG "lapb: (%p) S%d TX I(%d) S%d R%d\n",
65 lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
66 #endif
67
68 lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
69 }
70
71 void lapb_kick(struct lapb_cb *lapb)
72 {
73 struct sk_buff *skb, *skbn;
74 unsigned short modulus, start, end;
75
76 modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
77 start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
78 end = (lapb->va + lapb->window) % modulus;
79
80 if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
81 start != end && skb_peek(&lapb->write_queue)) {
82 lapb->vs = start;
83
84 /*
85 * Dequeue the frame and copy it.
86 */
87 skb = skb_dequeue(&lapb->write_queue);
88
89 do {
90 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
91 skb_queue_head(&lapb->write_queue, skb);
92 break;
93 }
94
95 if (skb->sk)
96 skb_set_owner_w(skbn, skb->sk);
97
98 /*
99 * Transmit the frame copy.
100 */
101 lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
102
103 lapb->vs = (lapb->vs + 1) % modulus;
104
105 /*
106 * Requeue the original data frame.
107 */
108 skb_queue_tail(&lapb->ack_queue, skb);
109
110 } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
111
112 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
113
114 if (!lapb_t1timer_running(lapb))
115 lapb_start_t1timer(lapb);
116 }
117 }
118
119 void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
120 {
121 unsigned char *ptr;
122
123 ptr = skb_push(skb, 1);
124
125 if (lapb->mode & LAPB_MLP) {
126 if (lapb->mode & LAPB_DCE) {
127 if (type == LAPB_COMMAND)
128 *ptr = LAPB_ADDR_C;
129 if (type == LAPB_RESPONSE)
130 *ptr = LAPB_ADDR_D;
131 } else {
132 if (type == LAPB_COMMAND)
133 *ptr = LAPB_ADDR_D;
134 if (type == LAPB_RESPONSE)
135 *ptr = LAPB_ADDR_C;
136 }
137 } else {
138 if (lapb->mode & LAPB_DCE) {
139 if (type == LAPB_COMMAND)
140 *ptr = LAPB_ADDR_A;
141 if (type == LAPB_RESPONSE)
142 *ptr = LAPB_ADDR_B;
143 } else {
144 if (type == LAPB_COMMAND)
145 *ptr = LAPB_ADDR_B;
146 if (type == LAPB_RESPONSE)
147 *ptr = LAPB_ADDR_A;
148 }
149 }
150
151 #if LAPB_DEBUG > 2
152 printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n",
153 lapb->dev, lapb->state,
154 skb->data[0], skb->data[1], skb->data[2]);
155 #endif
156
157 if (!lapb_data_transmit(lapb, skb))
158 kfree_skb(skb);
159 }
160
161 void lapb_establish_data_link(struct lapb_cb *lapb)
162 {
163 lapb->condition = 0x00;
164 lapb->n2count = 0;
165
166 if (lapb->mode & LAPB_EXTENDED) {
167 #if LAPB_DEBUG > 1
168 printk(KERN_DEBUG "lapb: (%p) S%d TX SABME(1)\n",
169 lapb->dev, lapb->state);
170 #endif
171 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
172 } else {
173 #if LAPB_DEBUG > 1
174 printk(KERN_DEBUG "lapb: (%p) S%d TX SABM(1)\n",
175 lapb->dev, lapb->state);
176 #endif
177 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
178 }
179
180 lapb_start_t1timer(lapb);
181 lapb_stop_t2timer(lapb);
182 }
183
184 void lapb_enquiry_response(struct lapb_cb *lapb)
185 {
186 #if LAPB_DEBUG > 1
187 printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n",
188 lapb->dev, lapb->state, lapb->vr);
189 #endif
190
191 lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
192
193 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
194 }
195
196 void lapb_timeout_response(struct lapb_cb *lapb)
197 {
198 #if LAPB_DEBUG > 1
199 printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n",
200 lapb->dev, lapb->state, lapb->vr);
201 #endif
202 lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
203
204 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
205 }
206
207 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
208 {
209 if (lapb->vs == nr) {
210 lapb_frames_acked(lapb, nr);
211 lapb_stop_t1timer(lapb);
212 lapb->n2count = 0;
213 } else if (lapb->va != nr) {
214 lapb_frames_acked(lapb, nr);
215 lapb_start_t1timer(lapb);
216 }
217 }
218
219 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
220 {
221 if (type == LAPB_COMMAND && pf)
222 lapb_enquiry_response(lapb);
223 }
224
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