lapb_out.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 
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/sched.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 <net/sock.h>
30#include <asm/uaccess.h>
31#include <asm/system.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 procedure is passed a buffer descriptor for an iframe. It builds
39 *  the rest of the control part of the frame and then writes it out.
40 */
41static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
42{
43	unsigned char *frame;
44
45	if (!skb)
46		return;
47
48	if (lapb->mode & LAPB_EXTENDED) {
49		frame = skb_push(skb, 2);
50
51		frame[0] = LAPB_I;
52		frame[0] |= lapb->vs << 1;
53		frame[1] = poll_bit ? LAPB_EPF : 0;
54		frame[1] |= lapb->vr << 1;
55	} else {
56		frame = skb_push(skb, 1);
57
58		*frame = LAPB_I;
59		*frame |= poll_bit ? LAPB_SPF : 0;
60		*frame |= lapb->vr << 5;
61		*frame |= lapb->vs << 1;
62	}
63
64#if LAPB_DEBUG > 1
65	printk(KERN_DEBUG "lapb: (%p) S%d TX I(%d) S%d R%d\n",
66	       lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
67#endif
68
69	lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
70}
71
72void lapb_kick(struct lapb_cb *lapb)
73{
74	struct sk_buff *skb, *skbn;
75	unsigned short modulus, start, end;
76
77	modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
78	start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
79	end   = (lapb->va + lapb->window) % modulus;
80
81	if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
82	    start != end && skb_peek(&lapb->write_queue)) {
83		lapb->vs = start;
84
85		/*
86		 * Dequeue the frame and copy it.
87		 */
88		skb = skb_dequeue(&lapb->write_queue);
89
90		do {
91			if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
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
120void 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#if LAPB_DEBUG > 2
153	printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n",
154	       lapb->dev, lapb->state,
155	       skb->data[0], skb->data[1], skb->data[2]);
156#endif
157
158	if (!lapb_data_transmit(lapb, skb))
159		kfree_skb(skb);
160}
161
162void lapb_establish_data_link(struct lapb_cb *lapb)
163{
164	lapb->condition = 0x00;
165	lapb->n2count   = 0;
166
167	if (lapb->mode & LAPB_EXTENDED) {
168#if LAPB_DEBUG > 1
169		printk(KERN_DEBUG "lapb: (%p) S%d TX SABME(1)\n",
170		       lapb->dev, lapb->state);
171#endif
172		lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
173	} else {
174#if LAPB_DEBUG > 1
175		printk(KERN_DEBUG "lapb: (%p) S%d TX SABM(1)\n",
176		       lapb->dev, lapb->state);
177#endif
178		lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
179	}
180
181	lapb_start_t1timer(lapb);
182	lapb_stop_t2timer(lapb);
183}
184
185void lapb_enquiry_response(struct lapb_cb *lapb)
186{
187#if LAPB_DEBUG > 1
188	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n",
189	       lapb->dev, lapb->state, lapb->vr);
190#endif
191
192	lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
193
194	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
195}
196
197void lapb_timeout_response(struct lapb_cb *lapb)
198{
199#if LAPB_DEBUG > 1
200	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n",
201	       lapb->dev, lapb->state, lapb->vr);
202#endif
203	lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
204
205	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
206}
207
208void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
209{
210	if (lapb->vs == nr) {
211		lapb_frames_acked(lapb, nr);
212		lapb_stop_t1timer(lapb);
213		lapb->n2count = 0;
214	} else if (lapb->va != nr) {
215		lapb_frames_acked(lapb, nr);
216		lapb_start_t1timer(lapb);
217	}
218}
219
220void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
221{
222	if (type == LAPB_COMMAND && pf)
223		lapb_enquiry_response(lapb);
224}
225