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