xref: /openbmc/linux/net/netrom/nr_in.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/sched.h>
16 #include <linux/timer.h>
17 #include <linux/string.h>
18 #include <linux/sockios.h>
19 #include <linux/net.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 <net/tcp_states.h>
26 #include <asm/uaccess.h>
27 #include <asm/system.h>
28 #include <linux/fcntl.h>
29 #include <linux/mm.h>
30 #include <linux/interrupt.h>
31 #include <net/netrom.h>
32 
33 static int nr_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
34 {
35 	struct sk_buff *skbo, *skbn = skb;
36 	struct nr_sock *nr = nr_sk(sk);
37 
38 	skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
39 
40 	nr_start_idletimer(sk);
41 
42 	if (more) {
43 		nr->fraglen += skb->len;
44 		skb_queue_tail(&nr->frag_queue, skb);
45 		return 0;
46 	}
47 
48 	if (!more && nr->fraglen > 0) {	/* End of fragment */
49 		nr->fraglen += skb->len;
50 		skb_queue_tail(&nr->frag_queue, skb);
51 
52 		if ((skbn = alloc_skb(nr->fraglen, GFP_ATOMIC)) == NULL)
53 			return 1;
54 
55 		skbn->h.raw = skbn->data;
56 
57 		while ((skbo = skb_dequeue(&nr->frag_queue)) != NULL) {
58 			memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
59 			kfree_skb(skbo);
60 		}
61 
62 		nr->fraglen = 0;
63 	}
64 
65 	return sock_queue_rcv_skb(sk, skbn);
66 }
67 
68 /*
69  * State machine for state 1, Awaiting Connection State.
70  * The handling of the timer(s) is in file nr_timer.c.
71  * Handling of state 0 and connection release is in netrom.c.
72  */
73 static int nr_state1_machine(struct sock *sk, struct sk_buff *skb,
74 	int frametype)
75 {
76 	switch (frametype) {
77 	case NR_CONNACK: {
78 		struct nr_sock *nr = nr_sk(sk);
79 
80 		nr_stop_t1timer(sk);
81 		nr_start_idletimer(sk);
82 		nr->your_index = skb->data[17];
83 		nr->your_id    = skb->data[18];
84 		nr->vs	       = 0;
85 		nr->va	       = 0;
86 		nr->vr	       = 0;
87 		nr->vl	       = 0;
88 		nr->state      = NR_STATE_3;
89 		nr->n2count    = 0;
90 		nr->window     = skb->data[20];
91 		sk->sk_state   = TCP_ESTABLISHED;
92 		if (!sock_flag(sk, SOCK_DEAD))
93 			sk->sk_state_change(sk);
94 		break;
95 	}
96 
97 	case NR_CONNACK | NR_CHOKE_FLAG:
98 		nr_disconnect(sk, ECONNREFUSED);
99 		break;
100 
101 	case NR_RESET:
102 		if (sysctl_netrom_reset_circuit);
103 			nr_disconnect(sk, ECONNRESET);
104 		break;
105 
106 	default:
107 		break;
108 	}
109 	return 0;
110 }
111 
112 /*
113  * State machine for state 2, Awaiting Release State.
114  * The handling of the timer(s) is in file nr_timer.c
115  * Handling of state 0 and connection release is in netrom.c.
116  */
117 static int nr_state2_machine(struct sock *sk, struct sk_buff *skb,
118 	int frametype)
119 {
120 	switch (frametype) {
121 	case NR_CONNACK | NR_CHOKE_FLAG:
122 		nr_disconnect(sk, ECONNRESET);
123 		break;
124 
125 	case NR_DISCREQ:
126 		nr_write_internal(sk, NR_DISCACK);
127 
128 	case NR_DISCACK:
129 		nr_disconnect(sk, 0);
130 		break;
131 
132 	case NR_RESET:
133 		if (sysctl_netrom_reset_circuit);
134 			nr_disconnect(sk, ECONNRESET);
135 		break;
136 
137 	default:
138 		break;
139 	}
140 	return 0;
141 }
142 
143 /*
144  * State machine for state 3, Connected State.
145  * The handling of the timer(s) is in file nr_timer.c
146  * Handling of state 0 and connection release is in netrom.c.
147  */
148 static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype)
149 {
150 	struct nr_sock *nrom = nr_sk(sk);
151 	struct sk_buff_head temp_queue;
152 	struct sk_buff *skbn;
153 	unsigned short save_vr;
154 	unsigned short nr, ns;
155 	int queued = 0;
156 
157 	nr = skb->data[18];
158 	ns = skb->data[17];
159 
160 	switch (frametype) {
161 	case NR_CONNREQ:
162 		nr_write_internal(sk, NR_CONNACK);
163 		break;
164 
165 	case NR_DISCREQ:
166 		nr_write_internal(sk, NR_DISCACK);
167 		nr_disconnect(sk, 0);
168 		break;
169 
170 	case NR_CONNACK | NR_CHOKE_FLAG:
171 	case NR_DISCACK:
172 		nr_disconnect(sk, ECONNRESET);
173 		break;
174 
175 	case NR_INFOACK:
176 	case NR_INFOACK | NR_CHOKE_FLAG:
177 	case NR_INFOACK | NR_NAK_FLAG:
178 	case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
179 		if (frametype & NR_CHOKE_FLAG) {
180 			nrom->condition |= NR_COND_PEER_RX_BUSY;
181 			nr_start_t4timer(sk);
182 		} else {
183 			nrom->condition &= ~NR_COND_PEER_RX_BUSY;
184 			nr_stop_t4timer(sk);
185 		}
186 		if (!nr_validate_nr(sk, nr)) {
187 			break;
188 		}
189 		if (frametype & NR_NAK_FLAG) {
190 			nr_frames_acked(sk, nr);
191 			nr_send_nak_frame(sk);
192 		} else {
193 			if (nrom->condition & NR_COND_PEER_RX_BUSY) {
194 				nr_frames_acked(sk, nr);
195 			} else {
196 				nr_check_iframes_acked(sk, nr);
197 			}
198 		}
199 		break;
200 
201 	case NR_INFO:
202 	case NR_INFO | NR_NAK_FLAG:
203 	case NR_INFO | NR_CHOKE_FLAG:
204 	case NR_INFO | NR_MORE_FLAG:
205 	case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
206 	case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
207 	case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
208 	case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
209 		if (frametype & NR_CHOKE_FLAG) {
210 			nrom->condition |= NR_COND_PEER_RX_BUSY;
211 			nr_start_t4timer(sk);
212 		} else {
213 			nrom->condition &= ~NR_COND_PEER_RX_BUSY;
214 			nr_stop_t4timer(sk);
215 		}
216 		if (nr_validate_nr(sk, nr)) {
217 			if (frametype & NR_NAK_FLAG) {
218 				nr_frames_acked(sk, nr);
219 				nr_send_nak_frame(sk);
220 			} else {
221 				if (nrom->condition & NR_COND_PEER_RX_BUSY) {
222 					nr_frames_acked(sk, nr);
223 				} else {
224 					nr_check_iframes_acked(sk, nr);
225 				}
226 			}
227 		}
228 		queued = 1;
229 		skb_queue_head(&nrom->reseq_queue, skb);
230 		if (nrom->condition & NR_COND_OWN_RX_BUSY)
231 			break;
232 		skb_queue_head_init(&temp_queue);
233 		do {
234 			save_vr = nrom->vr;
235 			while ((skbn = skb_dequeue(&nrom->reseq_queue)) != NULL) {
236 				ns = skbn->data[17];
237 				if (ns == nrom->vr) {
238 					if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
239 						nrom->vr = (nrom->vr + 1) % NR_MODULUS;
240 					} else {
241 						nrom->condition |= NR_COND_OWN_RX_BUSY;
242 						skb_queue_tail(&temp_queue, skbn);
243 					}
244 				} else if (nr_in_rx_window(sk, ns)) {
245 					skb_queue_tail(&temp_queue, skbn);
246 				} else {
247 					kfree_skb(skbn);
248 				}
249 			}
250 			while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
251 				skb_queue_tail(&nrom->reseq_queue, skbn);
252 			}
253 		} while (save_vr != nrom->vr);
254 		/*
255 		 * Window is full, ack it immediately.
256 		 */
257 		if (((nrom->vl + nrom->window) % NR_MODULUS) == nrom->vr) {
258 			nr_enquiry_response(sk);
259 		} else {
260 			if (!(nrom->condition & NR_COND_ACK_PENDING)) {
261 				nrom->condition |= NR_COND_ACK_PENDING;
262 				nr_start_t2timer(sk);
263 			}
264 		}
265 		break;
266 
267 	case NR_RESET:
268 		if (sysctl_netrom_reset_circuit);
269 			nr_disconnect(sk, ECONNRESET);
270 		break;
271 
272 	default:
273 		break;
274 	}
275 	return queued;
276 }
277 
278 /* Higher level upcall for a LAPB frame - called with sk locked */
279 int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
280 {
281 	struct nr_sock *nr = nr_sk(sk);
282 	int queued = 0, frametype;
283 
284 	if (nr->state == NR_STATE_0)
285 		return 0;
286 
287 	frametype = skb->data[19];
288 
289 	switch (nr->state) {
290 	case NR_STATE_1:
291 		queued = nr_state1_machine(sk, skb, frametype);
292 		break;
293 	case NR_STATE_2:
294 		queued = nr_state2_machine(sk, skb, frametype);
295 		break;
296 	case NR_STATE_3:
297 		queued = nr_state3_machine(sk, skb, frametype);
298 		break;
299 	}
300 
301 	nr_kick(sk);
302 
303 	return queued;
304 }
305