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