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