net/rose/rose_in.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *
   4  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   5  *
   6  * Most of this code is based on the SDL diagrams published in the 7th ARRL
   7  * Computer Networking Conference papers. The diagrams have mistakes in them,
   8  * but are mostly correct. Before you modify the code could you read the SDL
   9  * diagrams as the code is not obvious and probably very easy to break.
  10  */
  11 #include <linux/errno.h>
  12 #include <linux/filter.h>
  13 #include <linux/types.h>
  14 #include <linux/socket.h>
  15 #include <linux/in.h>
  16 #include <linux/kernel.h>
  17 #include <linux/timer.h>
  18 #include <linux/string.h>
  19 #include <linux/sockios.h>
  20 #include <linux/net.h>
  21 #include <net/ax25.h>
  22 #include <linux/inet.h>
  23 #include <linux/netdevice.h>
  24 #include <linux/skbuff.h>
  25 #include <net/sock.h>
  26 #include <net/tcp_states.h>
  27 #include <linux/fcntl.h>
  28 #include <linux/mm.h>
  29 #include <linux/interrupt.h>
  30 #include <net/rose.h>
  31
  32 /*
  33  * State machine for state 1, Awaiting Call Accepted State.
  34  * The handling of the timer(s) is in file rose_timer.c.
  35  * Handling of state 0 and connection release is in af_rose.c.
  36  */
  37 static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  38 {
  39         struct rose_sock *rose = rose_sk(sk);
  40
  41         switch (frametype) {
  42         case ROSE_CALL_ACCEPTED:
  43                 rose_stop_timer(sk);
  44                 rose_start_idletimer(sk);
  45                 rose->condition = 0x00;
  46                 rose->vs        = 0;
  47                 rose->va        = 0;
  48                 rose->vr        = 0;
  49                 rose->vl        = 0;
  50                 rose->state     = ROSE_STATE_3;
  51                 sk->sk_state    = TCP_ESTABLISHED;
  52                 if (!sock_flag(sk, SOCK_DEAD))
  53                         sk->sk_state_change(sk);
  54                 break;
  55
  56         case ROSE_CLEAR_REQUEST:
  57                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
  58                 rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
  59                 rose->neighbour->use--;
  60                 break;
  61
  62         default:
  63                 break;
  64         }
  65
  66         return 0;
  67 }
  68
  69 /*
  70  * State machine for state 2, Awaiting Clear Confirmation State.
  71  * The handling of the timer(s) is in file rose_timer.c
  72  * Handling of state 0 and connection release is in af_rose.c.
  73  */
  74 static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  75 {
  76         struct rose_sock *rose = rose_sk(sk);
  77
  78         switch (frametype) {
  79         case ROSE_CLEAR_REQUEST:
  80                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
  81                 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
  82                 rose->neighbour->use--;
  83                 break;
  84
  85         case ROSE_CLEAR_CONFIRMATION:
  86                 rose_disconnect(sk, 0, -1, -1);
  87                 rose->neighbour->use--;
  88                 break;
  89
  90         default:
  91                 break;
  92         }
  93
  94         return 0;
  95 }
  96
  97 /*
  98  * State machine for state 3, Connected State.
  99  * The handling of the timer(s) is in file rose_timer.c
 100  * Handling of state 0 and connection release is in af_rose.c.
 101  */
 102 static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 103 {
 104         struct rose_sock *rose = rose_sk(sk);
 105         int queued = 0;
 106
 107         switch (frametype) {
 108         case ROSE_RESET_REQUEST:
 109                 rose_stop_timer(sk);
 110                 rose_start_idletimer(sk);
 111                 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
 112                 rose->condition = 0x00;
 113                 rose->vs        = 0;
 114                 rose->vr        = 0;
 115                 rose->va        = 0;
 116                 rose->vl        = 0;
 117                 rose_requeue_frames(sk);
 118                 break;
 119
 120         case ROSE_CLEAR_REQUEST:
 121                 rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
 122                 rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
 123                 rose->neighbour->use--;
 124                 break;
 125
 126         case ROSE_RR:
 127         case ROSE_RNR:
 128                 if (!rose_validate_nr(sk, nr)) {
 129                         rose_write_internal(sk, ROSE_RESET_REQUEST);
 130                         rose->condition = 0x00;
 131                         rose->vs        = 0;
 132                         rose->vr        = 0;
 133                         rose->va        = 0;
 134                         rose->vl        = 0;
 135                         rose->state     = ROSE_STATE_4;
 136                         rose_start_t2timer(sk);
 137                         rose_stop_idletimer(sk);
 138                 } else {
 139                         rose_frames_acked(sk, nr);
 140                         if (frametype == ROSE_RNR) {
 141                                 rose->condition |= ROSE_COND_PEER_RX_BUSY;
 142                         } else {
 143                                 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
 144                         }
 145                 }
 146                 break;
 147
 148         case ROSE_DATA: /* XXX */
 149                 rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
 150                 if (!rose_validate_nr(sk, nr)) {
 151                         rose_write_internal(sk, ROSE_RESET_REQUEST);
 152                         rose->condition = 0x00;
 153                         rose->vs        = 0;
 154                         rose->vr        = 0;
 155                         rose->va        = 0;
 156                         rose->vl        = 0;
 157                         rose->state     = ROSE_STATE_4;
 158                         rose_start_t2timer(sk);
 159                         rose_stop_idletimer(sk);
 160                         break;
 161                 }
 162                 rose_frames_acked(sk, nr);
 163                 if (ns == rose->vr) {
 164                         rose_start_idletimer(sk);
 165                         if (sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN) == 0 &&
 166                             __sock_queue_rcv_skb(sk, skb) == 0) {
 167                                 rose->vr = (rose->vr + 1) % ROSE_MODULUS;
 168                                 queued = 1;
 169                         } else {
 170                                 /* Should never happen ! */
 171                                 rose_write_internal(sk, ROSE_RESET_REQUEST);
 172                                 rose->condition = 0x00;
 173                                 rose->vs        = 0;
 174                                 rose->vr        = 0;
 175                                 rose->va        = 0;
 176                                 rose->vl        = 0;
 177                                 rose->state     = ROSE_STATE_4;
 178                                 rose_start_t2timer(sk);
 179                                 rose_stop_idletimer(sk);
 180                                 break;
 181                         }
 182                         if (atomic_read(&sk->sk_rmem_alloc) >
 183                             (sk->sk_rcvbuf >> 1))
 184                                 rose->condition |= ROSE_COND_OWN_RX_BUSY;
 185                 }
 186                 /*
 187                  * If the window is full, ack the frame, else start the
 188                  * acknowledge hold back timer.
 189                  */
 190                 if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
 191                         rose->condition &= ~ROSE_COND_ACK_PENDING;
 192                         rose_stop_timer(sk);
 193                         rose_enquiry_response(sk);
 194                 } else {
 195                         rose->condition |= ROSE_COND_ACK_PENDING;
 196                         rose_start_hbtimer(sk);
 197                 }
 198                 break;
 199
 200         default:
 201                 printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
 202                 break;
 203         }
 204
 205         return queued;
 206 }
 207
 208 /*
 209  * State machine for state 4, Awaiting Reset Confirmation State.
 210  * The handling of the timer(s) is in file rose_timer.c
 211  * Handling of state 0 and connection release is in af_rose.c.
 212  */
 213 static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 214 {
 215         struct rose_sock *rose = rose_sk(sk);
 216
 217         switch (frametype) {
 218         case ROSE_RESET_REQUEST:
 219                 rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
 220                 fallthrough;
 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 }