Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 00fbf1419ec6bd8138b0793a0ada11fedf441a7d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/netrom.h>

/*
 *	This is where all NET/ROM frames pass, except for IP-over-NET/ROM which
 *	cannot be fragmented in this manner.
 */
void nr_output(struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff *skbn;
	unsigned char transport[NR_TRANSPORT_LEN];
	int err, frontlen, len;

	if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
		/* Save a copy of the Transport Header */
		skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN);
		skb_pull(skb, NR_TRANSPORT_LEN);

		frontlen = skb_headroom(skb);

		while (skb->len > 0) {
			if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
				return;

			skb_reserve(skbn, frontlen);

			len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;

			/* Copy the user data */
			skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
			skb_pull(skb, len);

			/* Duplicate the Transport Header */
			skb_push(skbn, NR_TRANSPORT_LEN);
			skb_copy_to_linear_data(skbn, transport,
						NR_TRANSPORT_LEN);
			if (skb->len > 0)
				skbn->data[4] |= NR_MORE_FLAG;

			skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
		}

		kfree_skb(skb);
	} else {
		skb_queue_tail(&sk->sk_write_queue, skb);		/* Throw it on the queue */
	}

	nr_kick(sk);
}

/*
 *	This procedure is passed a buffer descriptor for an iframe. It builds
 *	the rest of the control part of the frame and then writes it out.
 */
static void nr_send_iframe(struct sock *sk, struct sk_buff *skb)
{
	struct nr_sock *nr = nr_sk(sk);

	if (skb == NULL)
		return;

	skb->data[2] = nr->vs;
	skb->data[3] = nr->vr;

	if (nr->condition & NR_COND_OWN_RX_BUSY)
		skb->data[4] |= NR_CHOKE_FLAG;

	nr_start_idletimer(sk);

	nr_transmit_buffer(sk, skb);
}

void nr_send_nak_frame(struct sock *sk)
{
	struct sk_buff *skb, *skbn;
	struct nr_sock *nr = nr_sk(sk);

	if ((skb = skb_peek(&nr->ack_queue)) == NULL)
		return;

	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
		return;

	skbn->data[2] = nr->va;
	skbn->data[3] = nr->vr;

	if (nr->condition & NR_COND_OWN_RX_BUSY)
		skbn->data[4] |= NR_CHOKE_FLAG;

	nr_transmit_buffer(sk, skbn);

	nr->condition &= ~NR_COND_ACK_PENDING;
	nr->vl         = nr->vr;

	nr_stop_t1timer(sk);
}

void nr_kick(struct sock *sk)
{
	struct nr_sock *nr = nr_sk(sk);
	struct sk_buff *skb, *skbn;
	unsigned short start, end;

	if (nr->state != NR_STATE_3)
		return;

	if (nr->condition & NR_COND_PEER_RX_BUSY)
		return;

	if (!skb_peek(&sk->sk_write_queue))
		return;

	start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs;
	end   = (nr->va + nr->window) % NR_MODULUS;

	if (start == end)
		return;

	nr->vs = start;

	/*
	 * Transmit data until either we're out of data to send or
	 * the window is full.
	 */

	/*
	 * Dequeue the frame and copy it.
	 */
	skb = skb_dequeue(&sk->sk_write_queue);

	do {
		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
			skb_queue_head(&sk->sk_write_queue, skb);
			break;
		}

		skb_set_owner_w(skbn, sk);

		/*
		 * Transmit the frame copy.
		 */
		nr_send_iframe(sk, skbn);

		nr->vs = (nr->vs + 1) % NR_MODULUS;

		/*
		 * Requeue the original data frame.
		 */
		skb_queue_tail(&nr->ack_queue, skb);

	} while (nr->vs != end &&
		 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);

	nr->vl         = nr->vr;
	nr->condition &= ~NR_COND_ACK_PENDING;

	if (!nr_t1timer_running(sk))
		nr_start_t1timer(sk);
}

void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
{
	struct nr_sock *nr = nr_sk(sk);
	unsigned char *dptr;

	/*
	 *	Add the protocol byte and network header.
	 */
	dptr = skb_push(skb, NR_NETWORK_LEN);

	memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
	dptr[6] &= ~AX25_CBIT;
	dptr[6] &= ~AX25_EBIT;
	dptr[6] |= AX25_SSSID_SPARE;
	dptr += AX25_ADDR_LEN;

	memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN);
	dptr[6] &= ~AX25_CBIT;
	dptr[6] |= AX25_EBIT;
	dptr[6] |= AX25_SSSID_SPARE;
	dptr += AX25_ADDR_LEN;

	*dptr++ = sysctl_netrom_network_ttl_initialiser;

	if (!nr_route_frame(skb, NULL)) {
		kfree_skb(skb);
		nr_disconnect(sk, ENETUNREACH);
	}
}

/*
 * The following routines are taken from page 170 of the 7th ARRL Computer
 * Networking Conference paper, as is the whole state machine.
 */

void nr_establish_data_link(struct sock *sk)
{
	struct nr_sock *nr = nr_sk(sk);

	nr->condition = 0x00;
	nr->n2count   = 0;

	nr_write_internal(sk, NR_CONNREQ);

	nr_stop_t2timer(sk);
	nr_stop_t4timer(sk);
	nr_stop_idletimer(sk);
	nr_start_t1timer(sk);
}

/*
 * Never send a NAK when we are CHOKEd.
 */
void nr_enquiry_response(struct sock *sk)
{
	struct nr_sock *nr = nr_sk(sk);
	int frametype = NR_INFOACK;

	if (nr->condition & NR_COND_OWN_RX_BUSY) {
		frametype |= NR_CHOKE_FLAG;
	} else {
		if (skb_peek(&nr->reseq_queue) != NULL)
			frametype |= NR_NAK_FLAG;
	}

	nr_write_internal(sk, frametype);

	nr->vl         = nr->vr;
	nr->condition &= ~NR_COND_ACK_PENDING;
}

void nr_check_iframes_acked(struct sock *sk, unsigned short nr)
{
	struct nr_sock *nrom = nr_sk(sk);

	if (nrom->vs == nr) {
		nr_frames_acked(sk, nr);
		nr_stop_t1timer(sk);
		nrom->n2count = 0;
	} else {
		if (nrom->va != nr) {
			nr_frames_acked(sk, nr);
			nr_start_t1timer(sk);
		}
	}
}