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