linux/net/rose/rose_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 (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 */
  39static 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 */
  76static 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 */
 104static 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 */
 214static 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 */
 251static 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 */
 263int 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}
 295
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