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