1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
8 */
9#include <linux/errno.h>
10#include <linux/types.h>
11#include <linux/socket.h>
12#include <linux/in.h>
13#include <linux/kernel.h>
14#include <linux/timer.h>
15#include <linux/string.h>
16#include <linux/sockios.h>
17#include <linux/net.h>
18#include <linux/slab.h>
19#include <net/ax25.h>
20#include <linux/inet.h>
21#include <linux/netdevice.h>
22#include <linux/skbuff.h>
23#include <net/sock.h>
24#include <net/tcp_states.h>
25#include <linux/uaccess.h>
26#include <linux/fcntl.h>
27#include <linux/mm.h>
28#include <linux/interrupt.h>
29#include <net/netrom.h>
30
31/*
32 *	This routine purges all of the queues of frames.
33 */
34void nr_clear_queues(struct sock *sk)
35{
36	struct nr_sock *nr = nr_sk(sk);
37
38	skb_queue_purge(&sk->sk_write_queue);
39	skb_queue_purge(&nr->ack_queue);
40	skb_queue_purge(&nr->reseq_queue);
41	skb_queue_purge(&nr->frag_queue);
42}
43
44/*
45 * This routine purges the input queue of those frames that have been
46 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
47 * SDL diagram.
48 */
49void nr_frames_acked(struct sock *sk, unsigned short nr)
50{
51	struct nr_sock *nrom = nr_sk(sk);
52	struct sk_buff *skb;
53
54	/*
55	 * Remove all the ack-ed frames from the ack queue.
56	 */
57	if (nrom->va != nr) {
58		while (skb_peek(&nrom->ack_queue) != NULL && nrom->va != nr) {
59			skb = skb_dequeue(&nrom->ack_queue);
60			kfree_skb(skb);
61			nrom->va = (nrom->va + 1) % NR_MODULUS;
62		}
63	}
64}
65
66/*
67 * Requeue all the un-ack-ed frames on the output queue to be picked
68 * up by nr_kick called from the timer. This arrangement handles the
69 * possibility of an empty output queue.
70 */
71void nr_requeue_frames(struct sock *sk)
72{
73	struct sk_buff *skb, *skb_prev = NULL;
74
75	while ((skb = skb_dequeue(&nr_sk(sk)->ack_queue)) != NULL) {
76		if (skb_prev == NULL)
77			skb_queue_head(&sk->sk_write_queue, skb);
78		else
79			skb_append(skb_prev, skb, &sk->sk_write_queue);
80		skb_prev = skb;
81	}
82}
83
84/*
85 *	Validate that the value of nr is between va and vs. Return true or
86 *	false for testing.
87 */
88int nr_validate_nr(struct sock *sk, unsigned short nr)
89{
90	struct nr_sock *nrom = nr_sk(sk);
91	unsigned short vc = nrom->va;
92
93	while (vc != nrom->vs) {
94		if (nr == vc) return 1;
95		vc = (vc + 1) % NR_MODULUS;
96	}
97
98	return nr == nrom->vs;
99}
100
101/*
102 *	Check that ns is within the receive window.
103 */
104int nr_in_rx_window(struct sock *sk, unsigned short ns)
105{
106	struct nr_sock *nr = nr_sk(sk);
107	unsigned short vc = nr->vr;
108	unsigned short vt = (nr->vl + nr->window) % NR_MODULUS;
109
110	while (vc != vt) {
111		if (ns == vc) return 1;
112		vc = (vc + 1) % NR_MODULUS;
113	}
114
115	return 0;
116}
117
118/*
119 *  This routine is called when the HDLC layer internally generates a
120 *  control frame.
121 */
122void nr_write_internal(struct sock *sk, int frametype)
123{
124	struct nr_sock *nr = nr_sk(sk);
125	struct sk_buff *skb;
126	unsigned char  *dptr;
127	int len, timeout;
128
129	len = NR_NETWORK_LEN + NR_TRANSPORT_LEN;
130
131	switch (frametype & 0x0F) {
132	case NR_CONNREQ:
133		len += 17;
134		break;
135	case NR_CONNACK:
136		len += (nr->bpqext) ? 2 : 1;
137		break;
138	case NR_DISCREQ:
139	case NR_DISCACK:
140	case NR_INFOACK:
141		break;
142	default:
143		printk(KERN_ERR "NET/ROM: nr_write_internal - invalid frame type %d\n", frametype);
144		return;
145	}
146
147	if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
148		return;
149
150	/*
151	 *	Space for AX.25 and NET/ROM network header
152	 */
153	skb_reserve(skb, NR_NETWORK_LEN);
154
155	dptr = skb_put(skb, skb_tailroom(skb));
156
157	switch (frametype & 0x0F) {
158	case NR_CONNREQ:
159		timeout  = nr->t1 / HZ;
160		*dptr++  = nr->my_index;
161		*dptr++  = nr->my_id;
162		*dptr++  = 0;
163		*dptr++  = 0;
164		*dptr++  = frametype;
165		*dptr++  = nr->window;
166		memcpy(dptr, &nr->user_addr, AX25_ADDR_LEN);
167		dptr[6] &= ~AX25_CBIT;
168		dptr[6] &= ~AX25_EBIT;
169		dptr[6] |= AX25_SSSID_SPARE;
170		dptr    += AX25_ADDR_LEN;
171		memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
172		dptr[6] &= ~AX25_CBIT;
173		dptr[6] &= ~AX25_EBIT;
174		dptr[6] |= AX25_SSSID_SPARE;
175		dptr    += AX25_ADDR_LEN;
176		*dptr++  = timeout % 256;
177		*dptr++  = timeout / 256;
178		break;
179
180	case NR_CONNACK:
181		*dptr++ = nr->your_index;
182		*dptr++ = nr->your_id;
183		*dptr++ = nr->my_index;
184		*dptr++ = nr->my_id;
185		*dptr++ = frametype;
186		*dptr++ = nr->window;
187		if (nr->bpqext) *dptr++ = sysctl_netrom_network_ttl_initialiser;
188		break;
189
190	case NR_DISCREQ:
191	case NR_DISCACK:
192		*dptr++ = nr->your_index;
193		*dptr++ = nr->your_id;
194		*dptr++ = 0;
195		*dptr++ = 0;
196		*dptr++ = frametype;
197		break;
198
199	case NR_INFOACK:
200		*dptr++ = nr->your_index;
201		*dptr++ = nr->your_id;
202		*dptr++ = 0;
203		*dptr++ = nr->vr;
204		*dptr++ = frametype;
205		break;
206	}
207
208	nr_transmit_buffer(sk, skb);
209}
210
211/*
212 * This routine is called to send an error reply.
213 */
214void __nr_transmit_reply(struct sk_buff *skb, int mine, unsigned char cmdflags)
215{
216	struct sk_buff *skbn;
217	unsigned char *dptr;
218	int len;
219
220	len = NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1;
221
222	if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL)
223		return;
224
225	skb_reserve(skbn, 0);
226
227	dptr = skb_put(skbn, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
228
229	skb_copy_from_linear_data_offset(skb, 7, dptr, AX25_ADDR_LEN);
230	dptr[6] &= ~AX25_CBIT;
231	dptr[6] &= ~AX25_EBIT;
232	dptr[6] |= AX25_SSSID_SPARE;
233	dptr += AX25_ADDR_LEN;
234
235	skb_copy_from_linear_data(skb, dptr, AX25_ADDR_LEN);
236	dptr[6] &= ~AX25_CBIT;
237	dptr[6] |= AX25_EBIT;
238	dptr[6] |= AX25_SSSID_SPARE;
239	dptr += AX25_ADDR_LEN;
240
241	*dptr++ = sysctl_netrom_network_ttl_initialiser;
242
243	if (mine) {
244		*dptr++ = 0;
245		*dptr++ = 0;
246		*dptr++ = skb->data[15];
247		*dptr++ = skb->data[16];
248	} else {
249		*dptr++ = skb->data[15];
250		*dptr++ = skb->data[16];
251		*dptr++ = 0;
252		*dptr++ = 0;
253	}
254
255	*dptr++ = cmdflags;
256	*dptr++ = 0;
257
258	if (!nr_route_frame(skbn, NULL))
259		kfree_skb(skbn);
260}
261
262void nr_disconnect(struct sock *sk, int reason)
263{
264	nr_stop_t1timer(sk);
265	nr_stop_t2timer(sk);
266	nr_stop_t4timer(sk);
267	nr_stop_idletimer(sk);
268
269	nr_clear_queues(sk);
270
271	nr_sk(sk)->state = NR_STATE_0;
272
273	sk->sk_state     = TCP_CLOSE;
274	sk->sk_err       = reason;
275	sk->sk_shutdown |= SEND_SHUTDOWN;
276
277	if (!sock_flag(sk, SOCK_DEAD)) {
278		sk->sk_state_change(sk);
279		sock_set_flag(sk, SOCK_DEAD);
280	}
281}
282