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