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(lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
42{
43	unsigned char *frame;
44
45	if (skb == NULL)
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", lapb->token, lapb->state, poll_bit, lapb->vs, lapb->vr);
66#endif
67
68	lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
69}
70
71void lapb_kick(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
78	start = (skb_peek(&lapb->ack_queue) == NULL) ? lapb->va : lapb->vs;
79	end   = (lapb->va + lapb->window) % modulus;
80
81	if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
82	    start != end                                &&
83	    skb_peek(&lapb->write_queue) != NULL) {
84
85		lapb->vs = start;
86
87		/*
88		 * Dequeue the frame and copy it.
89		 */
90		skb  = skb_dequeue(&lapb->write_queue);
91
92		do {
93			if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
94				skb_queue_head(&lapb->write_queue, skb);
95				break;
96			}
97
98			if (skb->sk != NULL)
99				skb_set_owner_w(skbn, skb->sk);
100
101			/*
102			 * Transmit the frame copy.
103			 */
104			lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
105
106			lapb->vs = (lapb->vs + 1) % modulus;
107
108			/*
109			 * Requeue the original data frame.
110			 */
111			skb_queue_tail(&lapb->ack_queue, skb);
112
113		} while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
114
115		lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
116
117		if (!lapb_t1timer_running(lapb))
118			lapb_start_t1timer(lapb);
119	}
120}
121
122void lapb_transmit_buffer(lapb_cb *lapb, struct sk_buff *skb, int type)
123{
124	unsigned char *ptr;
125
126	ptr = skb_push(skb, 1);
127
128	if (lapb->mode & LAPB_MLP) {
129		if (lapb->mode & LAPB_DCE) {
130			if (type == LAPB_COMMAND)
131				*ptr = LAPB_ADDR_C;
132			if (type == LAPB_RESPONSE)
133				*ptr = LAPB_ADDR_D;
134		} else {
135			if (type == LAPB_COMMAND)
136				*ptr = LAPB_ADDR_D;
137			if (type == LAPB_RESPONSE)
138				*ptr = LAPB_ADDR_C;
139		}
140	} else {
141		if (lapb->mode & LAPB_DCE) {
142			if (type == LAPB_COMMAND)
143				*ptr = LAPB_ADDR_A;
144			if (type == LAPB_RESPONSE)
145				*ptr = LAPB_ADDR_B;
146		} else {
147			if (type == LAPB_COMMAND)
148				*ptr = LAPB_ADDR_B;
149			if (type == LAPB_RESPONSE)
150				*ptr = LAPB_ADDR_A;
151		}
152	}
153
154#if LAPB_DEBUG > 2
155	printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n", lapb->token, lapb->state, 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(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", lapb->token, 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", lapb->token, lapb->state);
175#endif
176		lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
177	}
178
179	lapb_start_t1timer(lapb);
180	lapb_stop_t2timer(lapb);
181}
182
183void lapb_enquiry_response(lapb_cb *lapb)
184{
185#if LAPB_DEBUG > 1
186	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n", lapb->token, lapb->state, lapb->vr);
187#endif
188
189	lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
190
191	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
192}
193
194void lapb_timeout_response(lapb_cb *lapb)
195{
196#if LAPB_DEBUG > 1
197	printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n", lapb->token, lapb->state, lapb->vr);
198#endif
199
200	lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
201
202	lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
203}
204
205void lapb_check_iframes_acked(lapb_cb *lapb, unsigned short nr)
206{
207	if (lapb->vs == nr) {
208		lapb_frames_acked(lapb, nr);
209		lapb_stop_t1timer(lapb);
210		lapb->n2count = 0;
211	} else {
212		if (lapb->va != nr) {
213			lapb_frames_acked(lapb, nr);
214			lapb_start_t1timer(lapb);
215		}
216	}
217}
218
219void lapb_check_need_response(lapb_cb *lapb, int type, int pf)
220{
221	if (type == LAPB_COMMAND && pf)
222		lapb_enquiry_response(lapb);
223}
224