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TOMOYO Linux Cross Reference
Linux/net/netrom/nr_in.c

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  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 <net/tcp_states.h>
 26 #include <linux/uaccess.h>
 27 #include <linux/fcntl.h>
 28 #include <linux/mm.h>
 29 #include <linux/interrupt.h>
 30 #include <net/netrom.h>
 31 
 32 static int nr_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
 33 {
 34         struct sk_buff *skbo, *skbn = skb;
 35         struct nr_sock *nr = nr_sk(sk);
 36 
 37         skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
 38 
 39         nr_start_idletimer(sk);
 40 
 41         if (more) {
 42                 nr->fraglen += skb->len;
 43                 skb_queue_tail(&nr->frag_queue, skb);
 44                 return 0;
 45         }
 46 
 47         if (!more && nr->fraglen > 0) { /* End of fragment */
 48                 nr->fraglen += skb->len;
 49                 skb_queue_tail(&nr->frag_queue, skb);
 50 
 51                 if ((skbn = alloc_skb(nr->fraglen, GFP_ATOMIC)) == NULL)
 52                         return 1;
 53 
 54                 skb_reset_transport_header(skbn);
 55 
 56                 while ((skbo = skb_dequeue(&nr->frag_queue)) != NULL) {
 57                         skb_copy_from_linear_data(skbo,
 58                                                   skb_put(skbn, skbo->len),
 59                                                   skbo->len);
 60                         kfree_skb(skbo);
 61                 }
 62 
 63                 nr->fraglen = 0;
 64         }
 65 
 66         return sock_queue_rcv_skb(sk, skbn);
 67 }
 68 
 69 /*
 70  * State machine for state 1, Awaiting Connection State.
 71  * The handling of the timer(s) is in file nr_timer.c.
 72  * Handling of state 0 and connection release is in netrom.c.
 73  */
 74 static int nr_state1_machine(struct sock *sk, struct sk_buff *skb,
 75         int frametype)
 76 {
 77         switch (frametype) {
 78         case NR_CONNACK: {
 79                 struct nr_sock *nr = nr_sk(sk);
 80 
 81                 nr_stop_t1timer(sk);
 82                 nr_start_idletimer(sk);
 83                 nr->your_index = skb->data[17];
 84                 nr->your_id    = skb->data[18];
 85                 nr->vs         = 0;
 86                 nr->va         = 0;
 87                 nr->vr         = 0;
 88                 nr->vl         = 0;
 89                 nr->state      = NR_STATE_3;
 90                 nr->n2count    = 0;
 91                 nr->window     = skb->data[20];
 92                 sk->sk_state   = TCP_ESTABLISHED;
 93                 if (!sock_flag(sk, SOCK_DEAD))
 94                         sk->sk_state_change(sk);
 95                 break;
 96         }
 97 
 98         case NR_CONNACK | NR_CHOKE_FLAG:
 99                 nr_disconnect(sk, ECONNREFUSED);
100                 break;
101 
102         case NR_RESET:
103                 if (sysctl_netrom_reset_circuit)
104                         nr_disconnect(sk, ECONNRESET);
105                 break;
106 
107         default:
108                 break;
109         }
110         return 0;
111 }
112 
113 /*
114  * State machine for state 2, Awaiting Release State.
115  * The handling of the timer(s) is in file nr_timer.c
116  * Handling of state 0 and connection release is in netrom.c.
117  */
118 static int nr_state2_machine(struct sock *sk, struct sk_buff *skb,
119         int frametype)
120 {
121         switch (frametype) {
122         case NR_CONNACK | NR_CHOKE_FLAG:
123                 nr_disconnect(sk, ECONNRESET);
124                 break;
125 
126         case NR_DISCREQ:
127                 nr_write_internal(sk, NR_DISCACK);
128 
129         case NR_DISCACK:
130                 nr_disconnect(sk, 0);
131                 break;
132 
133         case NR_RESET:
134                 if (sysctl_netrom_reset_circuit)
135                         nr_disconnect(sk, ECONNRESET);
136                 break;
137 
138         default:
139                 break;
140         }
141         return 0;
142 }
143 
144 /*
145  * State machine for state 3, Connected State.
146  * The handling of the timer(s) is in file nr_timer.c
147  * Handling of state 0 and connection release is in netrom.c.
148  */
149 static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype)
150 {
151         struct nr_sock *nrom = nr_sk(sk);
152         struct sk_buff_head temp_queue;
153         struct sk_buff *skbn;
154         unsigned short save_vr;
155         unsigned short nr, ns;
156         int queued = 0;
157 
158         nr = skb->data[18];
159         ns = skb->data[17];
160 
161         switch (frametype) {
162         case NR_CONNREQ:
163                 nr_write_internal(sk, NR_CONNACK);
164                 break;
165 
166         case NR_DISCREQ:
167                 nr_write_internal(sk, NR_DISCACK);
168                 nr_disconnect(sk, 0);
169                 break;
170 
171         case NR_CONNACK | NR_CHOKE_FLAG:
172         case NR_DISCACK:
173                 nr_disconnect(sk, ECONNRESET);
174                 break;
175 
176         case NR_INFOACK:
177         case NR_INFOACK | NR_CHOKE_FLAG:
178         case NR_INFOACK | NR_NAK_FLAG:
179         case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
180                 if (frametype & NR_CHOKE_FLAG) {
181                         nrom->condition |= NR_COND_PEER_RX_BUSY;
182                         nr_start_t4timer(sk);
183                 } else {
184                         nrom->condition &= ~NR_COND_PEER_RX_BUSY;
185                         nr_stop_t4timer(sk);
186                 }
187                 if (!nr_validate_nr(sk, nr)) {
188                         break;
189                 }
190                 if (frametype & NR_NAK_FLAG) {
191                         nr_frames_acked(sk, nr);
192                         nr_send_nak_frame(sk);
193                 } else {
194                         if (nrom->condition & NR_COND_PEER_RX_BUSY) {
195                                 nr_frames_acked(sk, nr);
196                         } else {
197                                 nr_check_iframes_acked(sk, nr);
198                         }
199                 }
200                 break;
201 
202         case NR_INFO:
203         case NR_INFO | NR_NAK_FLAG:
204         case NR_INFO | NR_CHOKE_FLAG:
205         case NR_INFO | NR_MORE_FLAG:
206         case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
207         case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
208         case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
209         case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
210                 if (frametype & NR_CHOKE_FLAG) {
211                         nrom->condition |= NR_COND_PEER_RX_BUSY;
212                         nr_start_t4timer(sk);
213                 } else {
214                         nrom->condition &= ~NR_COND_PEER_RX_BUSY;
215                         nr_stop_t4timer(sk);
216                 }
217                 if (nr_validate_nr(sk, nr)) {
218                         if (frametype & NR_NAK_FLAG) {
219                                 nr_frames_acked(sk, nr);
220                                 nr_send_nak_frame(sk);
221                         } else {
222                                 if (nrom->condition & NR_COND_PEER_RX_BUSY) {
223                                         nr_frames_acked(sk, nr);
224                                 } else {
225                                         nr_check_iframes_acked(sk, nr);
226                                 }
227                         }
228                 }
229                 queued = 1;
230                 skb_queue_head(&nrom->reseq_queue, skb);
231                 if (nrom->condition & NR_COND_OWN_RX_BUSY)
232                         break;
233                 skb_queue_head_init(&temp_queue);
234                 do {
235                         save_vr = nrom->vr;
236                         while ((skbn = skb_dequeue(&nrom->reseq_queue)) != NULL) {
237                                 ns = skbn->data[17];
238                                 if (ns == nrom->vr) {
239                                         if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
240                                                 nrom->vr = (nrom->vr + 1) % NR_MODULUS;
241                                         } else {
242                                                 nrom->condition |= NR_COND_OWN_RX_BUSY;
243                                                 skb_queue_tail(&temp_queue, skbn);
244                                         }
245                                 } else if (nr_in_rx_window(sk, ns)) {
246                                         skb_queue_tail(&temp_queue, skbn);
247                                 } else {
248                                         kfree_skb(skbn);
249                                 }
250                         }
251                         while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
252                                 skb_queue_tail(&nrom->reseq_queue, skbn);
253                         }
254                 } while (save_vr != nrom->vr);
255                 /*
256                  * Window is full, ack it immediately.
257                  */
258                 if (((nrom->vl + nrom->window) % NR_MODULUS) == nrom->vr) {
259                         nr_enquiry_response(sk);
260                 } else {
261                         if (!(nrom->condition & NR_COND_ACK_PENDING)) {
262                                 nrom->condition |= NR_COND_ACK_PENDING;
263                                 nr_start_t2timer(sk);
264                         }
265                 }
266                 break;
267 
268         case NR_RESET:
269                 if (sysctl_netrom_reset_circuit)
270                         nr_disconnect(sk, ECONNRESET);
271                 break;
272 
273         default:
274                 break;
275         }
276         return queued;
277 }
278 
279 /* Higher level upcall for a LAPB frame - called with sk locked */
280 int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
281 {
282         struct nr_sock *nr = nr_sk(sk);
283         int queued = 0, frametype;
284 
285         if (nr->state == NR_STATE_0)
286                 return 0;
287 
288         frametype = skb->data[19];
289 
290         switch (nr->state) {
291         case NR_STATE_1:
292                 queued = nr_state1_machine(sk, skb, frametype);
293                 break;
294         case NR_STATE_2:
295                 queued = nr_state2_machine(sk, skb, frametype);
296                 break;
297         case NR_STATE_3:
298                 queued = nr_state3_machine(sk, skb, frametype);
299                 break;
300         }
301 
302         nr_kick(sk);
303 
304         return queued;
305 }
306 

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