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