net/ax25/ax25_ds_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  * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
   9  */
  10 #include <linux/errno.h>
  11 #include <linux/types.h>
  12 #include <linux/socket.h>
  13 #include <linux/in.h>
  14 #include <linux/kernel.h>
  15 #include <linux/sched.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/ip.h>                     /* For ip_rcv */
  26 #include <net/tcp.h>
  27 #include <asm/uaccess.h>
  28 #include <asm/system.h>
  29 #include <linux/fcntl.h>
  30 #include <linux/mm.h>
  31 #include <linux/interrupt.h>
  32
  33 /*
  34  *      State machine for state 1, Awaiting Connection State.
  35  *      The handling of the timer(s) is in file ax25_ds_timer.c.
  36  *      Handling of state 0 and connection release is in ax25.c.
  37  */
  38 static int ax25_ds_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
  39 {
  40         switch (frametype) {
  41         case AX25_SABM:
  42                 ax25->modulus = AX25_MODULUS;
  43                 ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
  44                 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
  45                 break;
  46
  47         case AX25_SABME:
  48                 ax25->modulus = AX25_EMODULUS;
  49                 ax25->window  =  ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
  50                 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
  51                 break;
  52
  53         case AX25_DISC:
  54                 ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
  55                 break;
  56
  57         case AX25_UA:
  58                 ax25_calculate_rtt(ax25);
  59                 ax25_stop_t1timer(ax25);
  60                 ax25_start_t3timer(ax25);
  61                 ax25_start_idletimer(ax25);
  62                 ax25->vs      = 0;
  63                 ax25->va      = 0;
  64                 ax25->vr      = 0;
  65                 ax25->state   = AX25_STATE_3;
  66                 ax25->n2count = 0;
  67                 if (ax25->sk != NULL) {
  68                         bh_lock_sock(ax25->sk);
  69                         ax25->sk->sk_state = TCP_ESTABLISHED;
  70                         /*
  71                          * For WAIT_SABM connections we will produce an accept
  72                          * ready socket here
  73                          */
  74                         if (!sock_flag(ax25->sk, SOCK_DEAD))
  75                                 ax25->sk->sk_state_change(ax25->sk);
  76                         bh_unlock_sock(ax25->sk);
  77                 }
  78                 ax25_dama_on(ax25);
  79
  80                 /* according to DK4EG´s spec we are required to
  81                  * send a RR RESPONSE FINAL NR=0.
  82                  */
  83
  84                 ax25_std_enquiry_response(ax25);
  85                 break;
  86
  87         case AX25_DM:
  88                 if (pf)
  89                         ax25_disconnect(ax25, ECONNREFUSED);
  90                 break;
  91
  92         default:
  93                 if (pf)
  94                         ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
  95                 break;
  96         }
  97
  98         return 0;
  99 }
 100
 101 /*
 102  *      State machine for state 2, Awaiting Release State.
 103  *      The handling of the timer(s) is in file ax25_ds_timer.c
 104  *      Handling of state 0 and connection release is in ax25.c.
 105  */
 106 static int ax25_ds_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
 107 {
 108         switch (frametype) {
 109         case AX25_SABM:
 110         case AX25_SABME:
 111                 ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
 112                 ax25_dama_off(ax25);
 113                 break;
 114
 115         case AX25_DISC:
 116                 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
 117                 ax25_dama_off(ax25);
 118                 ax25_disconnect(ax25, 0);
 119                 break;
 120
 121         case AX25_DM:
 122         case AX25_UA:
 123                 if (pf) {
 124                         ax25_dama_off(ax25);
 125                         ax25_disconnect(ax25, 0);
 126                 }
 127                 break;
 128
 129         case AX25_I:
 130         case AX25_REJ:
 131         case AX25_RNR:
 132         case AX25_RR:
 133                 if (pf) {
 134                         ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
 135                         ax25_dama_off(ax25);
 136                 }
 137                 break;
 138
 139         default:
 140                 break;
 141         }
 142
 143         return 0;
 144 }
 145
 146 /*
 147  *      State machine for state 3, Connected State.
 148  *      The handling of the timer(s) is in file ax25_timer.c
 149  *      Handling of state 0 and connection release is in ax25.c.
 150  */
 151 static int ax25_ds_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
 152 {
 153         int queued = 0;
 154
 155         switch (frametype) {
 156         case AX25_SABM:
 157         case AX25_SABME:
 158                 if (frametype == AX25_SABM) {
 159                         ax25->modulus   = AX25_MODULUS;
 160                         ax25->window    = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
 161                 } else {
 162                         ax25->modulus   = AX25_EMODULUS;
 163                         ax25->window    = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
 164                 }
 165                 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
 166                 ax25_stop_t1timer(ax25);
 167                 ax25_start_t3timer(ax25);
 168                 ax25_start_idletimer(ax25);
 169                 ax25->condition = 0x00;
 170                 ax25->vs        = 0;
 171                 ax25->va        = 0;
 172                 ax25->vr        = 0;
 173                 ax25_requeue_frames(ax25);
 174                 ax25_dama_on(ax25);
 175                 break;
 176
 177         case AX25_DISC:
 178                 ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
 179                 ax25_dama_off(ax25);
 180                 ax25_disconnect(ax25, 0);
 181                 break;
 182
 183         case AX25_DM:
 184                 ax25_dama_off(ax25);
 185                 ax25_disconnect(ax25, ECONNRESET);
 186                 break;
 187
 188         case AX25_RR:
 189         case AX25_RNR:
 190                 if (frametype == AX25_RR)
 191                         ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
 192                 else
 193                         ax25->condition |= AX25_COND_PEER_RX_BUSY;
 194
 195                 if (ax25_validate_nr(ax25, nr)) {
 196                         if (ax25_check_iframes_acked(ax25, nr))
 197                                 ax25->n2count=0;
 198                         if (type == AX25_COMMAND && pf)
 199                                 ax25_ds_enquiry_response(ax25);
 200                 } else {
 201                         ax25_ds_nr_error_recovery(ax25);
 202                         ax25->state = AX25_STATE_1;
 203                 }
 204                 break;
 205
 206         case AX25_REJ:
 207                 ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
 208
 209                 if (ax25_validate_nr(ax25, nr)) {
 210                         if (ax25->va != nr)
 211                                 ax25->n2count=0;
 212
 213                         ax25_frames_acked(ax25, nr);
 214                         ax25_calculate_rtt(ax25);
 215                         ax25_stop_t1timer(ax25);
 216                         ax25_start_t3timer(ax25);
 217                         ax25_requeue_frames(ax25);
 218
 219                         if (type == AX25_COMMAND && pf)
 220                                 ax25_ds_enquiry_response(ax25);
 221                 } else {
 222                         ax25_ds_nr_error_recovery(ax25);
 223                         ax25->state = AX25_STATE_1;
 224                 }
 225                 break;
 226
 227         case AX25_I:
 228                 if (!ax25_validate_nr(ax25, nr)) {
 229                         ax25_ds_nr_error_recovery(ax25);
 230                         ax25->state = AX25_STATE_1;
 231                         break;
 232                 }
 233                 if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
 234                         ax25_frames_acked(ax25, nr);
 235                         ax25->n2count = 0;
 236                 } else {
 237                         if (ax25_check_iframes_acked(ax25, nr))
 238                                 ax25->n2count = 0;
 239                 }
 240                 if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
 241                         if (pf) ax25_ds_enquiry_response(ax25);
 242                         break;
 243                 }
 244                 if (ns == ax25->vr) {
 245                         ax25->vr = (ax25->vr + 1) % ax25->modulus;
 246                         queued = ax25_rx_iframe(ax25, skb);
 247                         if (ax25->condition & AX25_COND_OWN_RX_BUSY)
 248                                 ax25->vr = ns;  /* ax25->vr - 1 */
 249                         ax25->condition &= ~AX25_COND_REJECT;
 250                         if (pf) {
 251                                 ax25_ds_enquiry_response(ax25);
 252                         } else {
 253                                 if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
 254                                         ax25->condition |= AX25_COND_ACK_PENDING;
 255                                         ax25_start_t2timer(ax25);
 256                                 }
 257                         }
 258                 } else {
 259                         if (ax25->condition & AX25_COND_REJECT) {
 260                                 if (pf) ax25_ds_enquiry_response(ax25);
 261                         } else {
 262                                 ax25->condition |= AX25_COND_REJECT;
 263                                 ax25_ds_enquiry_response(ax25);
 264                                 ax25->condition &= ~AX25_COND_ACK_PENDING;
 265                         }
 266                 }
 267                 break;
 268
 269         case AX25_FRMR:
 270         case AX25_ILLEGAL:
 271                 ax25_ds_establish_data_link(ax25);
 272                 ax25->state = AX25_STATE_1;
 273                 break;
 274
 275         default:
 276                 break;
 277         }
 278
 279         return queued;
 280 }
 281
 282 /*
 283  *      Higher level upcall for a LAPB frame
 284  */
 285 int ax25_ds_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
 286 {
 287         int queued = 0, frametype, ns, nr, pf;
 288
 289         frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
 290
 291         switch (ax25->state) {
 292         case AX25_STATE_1:
 293                 queued = ax25_ds_state1_machine(ax25, skb, frametype, pf, type);
 294                 break;
 295         case AX25_STATE_2:
 296                 queued = ax25_ds_state2_machine(ax25, skb, frametype, pf, type);
 297                 break;
 298         case AX25_STATE_3:
 299                 queued = ax25_ds_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
 300                 break;
 301         }
 302
 303         return queued;
 304 }
 305