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 * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
9 */
10 #include <linux/errno.h>
11 #include <linux/types.h>
12 #include <linux/socket.h>
13 #include <linux/in.h>
14 #include <linux/kernel.h>
15 #include <linux/timer.h>
16 #include <linux/string.h>
17 #include <linux/sockios.h>
18 #include <linux/net.h>
19 #include <linux/slab.h>
20 #include <net/ax25.h>
21 #include <linux/inet.h>
22 #include <linux/netdevice.h>
23 #include <linux/skbuff.h>
24 #include <net/sock.h>
25 #include <asm/uaccess.h>
26 #include <asm/system.h>
27 #include <linux/fcntl.h>
28 #include <linux/mm.h>
29 #include <linux/interrupt.h>
30 #include <net/netrom.h>
31
32 /*
33 * This is where all NET/ROM frames pass, except for IP-over-NET/ROM which
34 * cannot be fragmented in this manner.
35 */
nr_output(struct sock * sk,struct sk_buff * skb)36 void nr_output(struct sock *sk, struct sk_buff *skb)
37 {
38 struct sk_buff *skbn;
39 unsigned char transport[NR_TRANSPORT_LEN];
40 int err, frontlen, len;
41
42 if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
43 /* Save a copy of the Transport Header */
44 skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN);
45 skb_pull(skb, NR_TRANSPORT_LEN);
46
47 frontlen = skb_headroom(skb);
48
49 while (skb->len > 0) {
50 if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
51 return;
52
53 skb_reserve(skbn, frontlen);
54
55 len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;
56
57 /* Copy the user data */
58 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
59 skb_pull(skb, len);
60
61 /* Duplicate the Transport Header */
62 skb_push(skbn, NR_TRANSPORT_LEN);
63 skb_copy_to_linear_data(skbn, transport,
64 NR_TRANSPORT_LEN);
65 if (skb->len > 0)
66 skbn->data[4] |= NR_MORE_FLAG;
67
68 skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
69 }
70
71 kfree_skb(skb);
72 } else {
73 skb_queue_tail(&sk->sk_write_queue, skb); /* Throw it on the queue */
74 }
75
76 nr_kick(sk);
77 }
78
79 /*
80 * This procedure is passed a buffer descriptor for an iframe. It builds
81 * the rest of the control part of the frame and then writes it out.
82 */
nr_send_iframe(struct sock * sk,struct sk_buff * skb)83 static void nr_send_iframe(struct sock *sk, struct sk_buff *skb)
84 {
85 struct nr_sock *nr = nr_sk(sk);
86
87 if (skb == NULL)
88 return;
89
90 skb->data[2] = nr->vs;
91 skb->data[3] = nr->vr;
92
93 if (nr->condition & NR_COND_OWN_RX_BUSY)
94 skb->data[4] |= NR_CHOKE_FLAG;
95
96 nr_start_idletimer(sk);
97
98 nr_transmit_buffer(sk, skb);
99 }
100
nr_send_nak_frame(struct sock * sk)101 void nr_send_nak_frame(struct sock *sk)
102 {
103 struct sk_buff *skb, *skbn;
104 struct nr_sock *nr = nr_sk(sk);
105
106 if ((skb = skb_peek(&nr->ack_queue)) == NULL)
107 return;
108
109 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
110 return;
111
112 skbn->data[2] = nr->va;
113 skbn->data[3] = nr->vr;
114
115 if (nr->condition & NR_COND_OWN_RX_BUSY)
116 skbn->data[4] |= NR_CHOKE_FLAG;
117
118 nr_transmit_buffer(sk, skbn);
119
120 nr->condition &= ~NR_COND_ACK_PENDING;
121 nr->vl = nr->vr;
122
123 nr_stop_t1timer(sk);
124 }
125
nr_kick(struct sock * sk)126 void nr_kick(struct sock *sk)
127 {
128 struct nr_sock *nr = nr_sk(sk);
129 struct sk_buff *skb, *skbn;
130 unsigned short start, end;
131
132 if (nr->state != NR_STATE_3)
133 return;
134
135 if (nr->condition & NR_COND_PEER_RX_BUSY)
136 return;
137
138 if (!skb_peek(&sk->sk_write_queue))
139 return;
140
141 start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs;
142 end = (nr->va + nr->window) % NR_MODULUS;
143
144 if (start == end)
145 return;
146
147 nr->vs = start;
148
149 /*
150 * Transmit data until either we're out of data to send or
151 * the window is full.
152 */
153
154 /*
155 * Dequeue the frame and copy it.
156 */
157 skb = skb_dequeue(&sk->sk_write_queue);
158
159 do {
160 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
161 skb_queue_head(&sk->sk_write_queue, skb);
162 break;
163 }
164
165 skb_set_owner_w(skbn, sk);
166
167 /*
168 * Transmit the frame copy.
169 */
170 nr_send_iframe(sk, skbn);
171
172 nr->vs = (nr->vs + 1) % NR_MODULUS;
173
174 /*
175 * Requeue the original data frame.
176 */
177 skb_queue_tail(&nr->ack_queue, skb);
178
179 } while (nr->vs != end &&
180 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
181
182 nr->vl = nr->vr;
183 nr->condition &= ~NR_COND_ACK_PENDING;
184
185 if (!nr_t1timer_running(sk))
186 nr_start_t1timer(sk);
187 }
188
nr_transmit_buffer(struct sock * sk,struct sk_buff * skb)189 void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
190 {
191 struct nr_sock *nr = nr_sk(sk);
192 unsigned char *dptr;
193
194 /*
195 * Add the protocol byte and network header.
196 */
197 dptr = skb_push(skb, NR_NETWORK_LEN);
198
199 memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
200 dptr[6] &= ~AX25_CBIT;
201 dptr[6] &= ~AX25_EBIT;
202 dptr[6] |= AX25_SSSID_SPARE;
203 dptr += AX25_ADDR_LEN;
204
205 memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN);
206 dptr[6] &= ~AX25_CBIT;
207 dptr[6] |= AX25_EBIT;
208 dptr[6] |= AX25_SSSID_SPARE;
209 dptr += AX25_ADDR_LEN;
210
211 *dptr++ = sysctl_netrom_network_ttl_initialiser;
212
213 if (!nr_route_frame(skb, NULL)) {
214 kfree_skb(skb);
215 nr_disconnect(sk, ENETUNREACH);
216 }
217 }
218
219 /*
220 * The following routines are taken from page 170 of the 7th ARRL Computer
221 * Networking Conference paper, as is the whole state machine.
222 */
223
nr_establish_data_link(struct sock * sk)224 void nr_establish_data_link(struct sock *sk)
225 {
226 struct nr_sock *nr = nr_sk(sk);
227
228 nr->condition = 0x00;
229 nr->n2count = 0;
230
231 nr_write_internal(sk, NR_CONNREQ);
232
233 nr_stop_t2timer(sk);
234 nr_stop_t4timer(sk);
235 nr_stop_idletimer(sk);
236 nr_start_t1timer(sk);
237 }
238
239 /*
240 * Never send a NAK when we are CHOKEd.
241 */
nr_enquiry_response(struct sock * sk)242 void nr_enquiry_response(struct sock *sk)
243 {
244 struct nr_sock *nr = nr_sk(sk);
245 int frametype = NR_INFOACK;
246
247 if (nr->condition & NR_COND_OWN_RX_BUSY) {
248 frametype |= NR_CHOKE_FLAG;
249 } else {
250 if (skb_peek(&nr->reseq_queue) != NULL)
251 frametype |= NR_NAK_FLAG;
252 }
253
254 nr_write_internal(sk, frametype);
255
256 nr->vl = nr->vr;
257 nr->condition &= ~NR_COND_ACK_PENDING;
258 }
259
nr_check_iframes_acked(struct sock * sk,unsigned short nr)260 void nr_check_iframes_acked(struct sock *sk, unsigned short nr)
261 {
262 struct nr_sock *nrom = nr_sk(sk);
263
264 if (nrom->vs == nr) {
265 nr_frames_acked(sk, nr);
266 nr_stop_t1timer(sk);
267 nrom->n2count = 0;
268 } else {
269 if (nrom->va != nr) {
270 nr_frames_acked(sk, nr);
271 nr_start_t1timer(sk);
272 }
273 }
274 }
275