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