net/rose/rose_in.c

   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 (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   8  *
   9  * Most of this code is based on the SDL diagrams published in the 7th ARRL
  10  * Computer Networking Conference papers. The diagrams have mistakes in them,
  11  * but are mostly correct. Before you modify the code could you read the SDL
  12  * diagrams as the code is not obvious and probably very easy to break.
  13  */
  14 #include <linux/errno.h>
  15 #include <linux/types.h>
  16 #include <linux/socket.h>
  17 #include <linux/in.h>
  18 #include <linux/kernel.h>
  19 #include <linux/sched.h>
  20 #include <linux/timer.h>
  21 #include <linux/string.h>
  22 #include <linux/sockios.h>
  23 #include <linux/net.h>
  24 #include <net/ax25.h>
  25 #include <linux/inet.h>
  26 #include <linux/netdevice.h>
  27 #include <linux/skbuff.h>
  28 #include <net/sock.h>
  29 #include <net/ip.h>                     /* For ip_rcv */
  30 #include <net/tcp.h>
  31 #include <asm/system.h>
  32 #include <linux/fcntl.h>
  33 #include <linux/mm.h>
  34 #include <linux/interrupt.h>
  35 #include <net/rose.h>
  36
  37 /*
  38  * State machine for state 1, Awaiting Call Accepted State.
  39  * The handling of the timer(s) is in file rose_timer.c.
  40  * Handling of state 0 and connection release is in af_rose.c.
  41  */
  42 static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  43 {
  44         rose_cb *rose = rose_sk(sk);
  45
  46         switch (frametype) {
  47         case ROSE_CALL_ACCEPTED:
  48                 rose_stop_timer(sk);
  49                 rose_start_idletimer(sk);
  50                 rose->condition = 0x00;
  51                 rose->vs        = 0;
  52                 rose->va        = 0;
  53                 rose->vr        = 0;
  54                 rose->vl        = 0;
  55                 rose->state     = ROSE_STATE_3;
  56                 sk->sk_state    = TCP_ESTABLISHED;
  57                 if (!sock_flag(sk, SOCK_DEAD))
  58                         sk->sk_state_change(sk);
  59                 break;
  60
  61         case ROSE_CLEAR_REQUEST:
  62                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
  63                 rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
  64                 rose->neighbour->use--;
  65                 break;
  66
  67         default:
  68                 break;
  69         }
  70
  71         return 0;
  72 }
  73
  74 /*
  75  * State machine for state 2, Awaiting Clear Confirmation State.
  76  * The handling of the timer(s) is in file rose_timer.c
  77  * Handling of state 0 and connection release is in af_rose.c.
  78  */
  79 static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  80 {
  81         rose_cb *rose = rose_sk(sk);
  82
  83         switch (frametype) {
  84         case ROSE_CLEAR_REQUEST:
  85                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
  86                 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
  87                 rose->neighbour->use--;
  88                 break;
  89
  90         case ROSE_CLEAR_CONFIRMATION:
  91                 rose_disconnect(sk, 0, -1, -1);
  92                 rose->neighbour->use--;
  93                 break;
  94
  95         default:
  96                 break;
  97         }
  98
  99         return 0;
 100 }
 101
 102 /*
 103  * State machine for state 3, Connected State.
 104  * The handling of the timer(s) is in file rose_timer.c
 105  * Handling of state 0 and connection release is in af_rose.c.
 106  */
 107 static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 108 {
 109         rose_cb *rose = rose_sk(sk);
 110         int queued = 0;
 111
 112         switch (frametype) {
 113         case ROSE_RESET_REQUEST:
 114                 rose_stop_timer(sk);
 115                 rose_start_idletimer(sk);
 116                 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
 117                 rose->condition = 0x00;
 118                 rose->vs        = 0;
 119                 rose->vr        = 0;
 120                 rose->va        = 0;
 121                 rose->vl        = 0;
 122                 rose_requeue_frames(sk);
 123                 break;
 124
 125         case ROSE_CLEAR_REQUEST:
 126                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 127                 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 128                 rose->neighbour->use--;
 129                 break;
 130
 131         case ROSE_RR:
 132         case ROSE_RNR:
 133                 if (!rose_validate_nr(sk, nr)) {
 134                         rose_write_internal(sk, ROSE_RESET_REQUEST);
 135                         rose->condition = 0x00;
 136                         rose->vs        = 0;
 137                         rose->vr        = 0;
 138                         rose->va        = 0;
 139                         rose->vl        = 0;
 140                         rose->state     = ROSE_STATE_4;
 141                         rose_start_t2timer(sk);
 142                         rose_stop_idletimer(sk);
 143                 } else {
 144                         rose_frames_acked(sk, nr);
 145                         if (frametype == ROSE_RNR) {
 146                                 rose->condition |= ROSE_COND_PEER_RX_BUSY;
 147                         } else {
 148                                 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
 149                         }
 150                 }
 151                 break;
 152
 153         case ROSE_DATA: /* XXX */
 154                 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
 155                 if (!rose_validate_nr(sk, nr)) {
 156                         rose_write_internal(sk, ROSE_RESET_REQUEST);
 157                         rose->condition = 0x00;
 158                         rose->vs        = 0;
 159                         rose->vr        = 0;
 160                         rose->va        = 0;
 161                         rose->vl        = 0;
 162                         rose->state     = ROSE_STATE_4;
 163                         rose_start_t2timer(sk);
 164                         rose_stop_idletimer(sk);
 165                         break;
 166                 }
 167                 rose_frames_acked(sk, nr);
 168                 if (ns == rose->vr) {
 169                         rose_start_idletimer(sk);
 170                         if (sock_queue_rcv_skb(sk, skb) == 0) {
 171                                 rose->vr = (rose->vr + 1) % ROSE_MODULUS;
 172                                 queued = 1;
 173                         } else {
 174                                 /* Should never happen ! */
 175                                 rose_write_internal(sk, ROSE_RESET_REQUEST);
 176                                 rose->condition = 0x00;
 177                                 rose->vs        = 0;
 178                                 rose->vr        = 0;
 179                                 rose->va        = 0;
 180                                 rose->vl        = 0;
 181                                 rose->state     = ROSE_STATE_4;
 182                                 rose_start_t2timer(sk);
 183                                 rose_stop_idletimer(sk);
 184                                 break;
 185                         }
 186                         if (atomic_read(&sk->sk_rmem_alloc) >
 187                             (sk->sk_rcvbuf / 2))
 188                                 rose->condition |= ROSE_COND_OWN_RX_BUSY;
 189                 }
 190                 /*
 191                  * If the window is full, ack the frame, else start the
 192                  * acknowledge hold back timer.
 193                  */
 194                 if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
 195                         rose->condition &= ~ROSE_COND_ACK_PENDING;
 196                         rose_stop_timer(sk);
 197                         rose_enquiry_response(sk);
 198                 } else {
 199                         rose->condition |= ROSE_COND_ACK_PENDING;
 200                         rose_start_hbtimer(sk);
 201                 }
 202                 break;
 203
 204         default:
 205                 printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
 206                 break;
 207         }
 208
 209         return queued;
 210 }
 211
 212 /*
 213  * State machine for state 4, Awaiting Reset Confirmation State.
 214  * The handling of the timer(s) is in file rose_timer.c
 215  * Handling of state 0 and connection release is in af_rose.c.
 216  */
 217 static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 218 {
 219         rose_cb *rose = rose_sk(sk);
 220
 221         switch (frametype) {
 222         case ROSE_RESET_REQUEST:
 223                 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
 224         case ROSE_RESET_CONFIRMATION:
 225                 rose_stop_timer(sk);
 226                 rose_start_idletimer(sk);
 227                 rose->condition = 0x00;
 228                 rose->va        = 0;
 229                 rose->vr        = 0;
 230                 rose->vs        = 0;
 231                 rose->vl        = 0;
 232                 rose->state     = ROSE_STATE_3;
 233                 rose_requeue_frames(sk);
 234                 break;
 235
 236         case ROSE_CLEAR_REQUEST:
 237                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 238                 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 239                 rose->neighbour->use--;
 240                 break;
 241
 242         default:
 243                 break;
 244         }
 245
 246         return 0;
 247 }
 248
 249 /*
 250  * State machine for state 5, Awaiting Call Acceptance State.
 251  * The handling of the timer(s) is in file rose_timer.c
 252  * Handling of state 0 and connection release is in af_rose.c.
 253  */
 254 static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 255 {
 256         if (frametype == ROSE_CLEAR_REQUEST) {
 257                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 258                 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 259                 rose_sk(sk)->neighbour->use--;
 260         }
 261
 262         return 0;
 263 }
 264
 265 /* Higher level upcall for a LAPB frame */
 266 int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 267 {
 268         rose_cb *rose = rose_sk(sk);
 269         int queued = 0, frametype, ns, nr, q, d, m;
 270
 271         if (rose->state == ROSE_STATE_0)
 272                 return 0;
 273
 274         frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
 275
 276         switch (rose->state) {
 277         case ROSE_STATE_1:
 278                 queued = rose_state1_machine(sk, skb, frametype);
 279                 break;
 280         case ROSE_STATE_2:
 281                 queued = rose_state2_machine(sk, skb, frametype);
 282                 break;
 283         case ROSE_STATE_3:
 284                 queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 285                 break;
 286         case ROSE_STATE_4:
 287                 queued = rose_state4_machine(sk, skb, frametype);
 288                 break;
 289         case ROSE_STATE_5:
 290                 queued = rose_state5_machine(sk, skb, frametype);
 291                 break;
 292         }
 293
 294         rose_kick(sk);
 295
 296         return queued;
 297 }