net/netrom/nr_in.c

   1 /*
   2  *      NET/ROM release 007
   3  *
   4  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   5  *
   6  *      This module:
   7  *              This module is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  *      Most of this code is based on the SDL diagrams published in the 7th
  13  *      ARRL Computer Networking Conference papers. The diagrams have mistakes
  14  *      in them, but are mostly correct. Before you modify the code could you
  15  *      read the SDL diagrams as the code is not obvious and probably very
  16  *      easy to break;
  17  *
  18  *      History
  19  *      NET/ROM 001     Jonathan(G4KLX) Cloned from ax25_in.c
  20  *      NET/ROM 003     Jonathan(G4KLX) Added NET/ROM fragment reception.
  21  *                      Darryl(G7LED)   Added missing INFO with NAK case, optimized
  22  *                                      INFOACK handling, removed reconnect on error.
  23  *      NET/ROM 006     Jonathan(G4KLX) Hdrincl removal changes.
  24  *      NET/ROM 007     Jonathan(G4KLX) New timer architecture.
  25  */
  26
  27 #include <linux/errno.h>
  28 #include <linux/types.h>
  29 #include <linux/socket.h>
  30 #include <linux/in.h>
  31 #include <linux/kernel.h>
  32 #include <linux/sched.h>
  33 #include <linux/timer.h>
  34 #include <linux/string.h>
  35 #include <linux/sockios.h>
  36 #include <linux/net.h>
  37 #include <net/ax25.h>
  38 #include <linux/inet.h>
  39 #include <linux/netdevice.h>
  40 #include <linux/skbuff.h>
  41 #include <net/sock.h>
  42 #include <net/ip.h>                     /* For ip_rcv */
  43 #include <asm/uaccess.h>
  44 #include <asm/system.h>
  45 #include <linux/fcntl.h>
  46 #include <linux/mm.h>
  47 #include <linux/interrupt.h>
  48 #include <net/netrom.h>
  49
  50 static int nr_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
  51 {
  52         struct sk_buff *skbo, *skbn = skb;
  53
  54         skb_pull(skb, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
  55
  56         nr_start_idletimer(sk);
  57
  58         if (more) {
  59                 sk->protinfo.nr->fraglen += skb->len;
  60                 skb_queue_tail(&sk->protinfo.nr->frag_queue, skb);
  61                 return 0;
  62         }
  63
  64         if (!more && sk->protinfo.nr->fraglen > 0) {    /* End of fragment */
  65                 sk->protinfo.nr->fraglen += skb->len;
  66                 skb_queue_tail(&sk->protinfo.nr->frag_queue, skb);
  67
  68                 if ((skbn = alloc_skb(sk->protinfo.nr->fraglen, GFP_ATOMIC)) == NULL)
  69                         return 1;
  70
  71                 skbn->h.raw = skbn->data;
  72
  73                 while ((skbo = skb_dequeue(&sk->protinfo.nr->frag_queue)) != NULL) {
  74                         memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
  75                         kfree_skb(skbo);
  76                 }
  77
  78                 sk->protinfo.nr->fraglen = 0;
  79         }
  80
  81         return sock_queue_rcv_skb(sk, skbn);
  82 }
  83
  84 /*
  85  * State machine for state 1, Awaiting Connection State.
  86  * The handling of the timer(s) is in file nr_timer.c.
  87  * Handling of state 0 and connection release is in netrom.c.
  88  */
  89 static int nr_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  90 {
  91         switch (frametype) {
  92
  93                 case NR_CONNACK:
  94                         nr_stop_t1timer(sk);
  95                         nr_start_idletimer(sk);
  96                         sk->protinfo.nr->your_index = skb->data[17];
  97                         sk->protinfo.nr->your_id    = skb->data[18];
  98                         sk->protinfo.nr->vs         = 0;
  99                         sk->protinfo.nr->va         = 0;
 100                         sk->protinfo.nr->vr         = 0;
 101                         sk->protinfo.nr->vl         = 0;
 102                         sk->protinfo.nr->state      = NR_STATE_3;
 103                         sk->protinfo.nr->n2count    = 0;
 104                         sk->protinfo.nr->window     = skb->data[20];
 105                         sk->state                   = TCP_ESTABLISHED;
 106                         if (!sk->dead)
 107                                 sk->state_change(sk);
 108                         break;
 109
 110                 case NR_CONNACK | NR_CHOKE_FLAG:
 111                         nr_disconnect(sk, ECONNREFUSED);
 112                         break;
 113
 114                 default:
 115                         break;
 116         }
 117
 118         return 0;
 119 }
 120
 121 /*
 122  * State machine for state 2, Awaiting Release State.
 123  * The handling of the timer(s) is in file nr_timer.c
 124  * Handling of state 0 and connection release is in netrom.c.
 125  */
 126 static int nr_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 127 {
 128         switch (frametype) {
 129
 130                 case NR_CONNACK | NR_CHOKE_FLAG:
 131                         nr_disconnect(sk, ECONNRESET);
 132                         break;
 133
 134                 case NR_DISCREQ:
 135                         nr_write_internal(sk, NR_DISCACK);
 136
 137                 case NR_DISCACK:
 138                         nr_disconnect(sk, 0);
 139                         break;
 140
 141                 default:
 142                         break;
 143         }
 144
 145         return 0;
 146 }
 147
 148 /*
 149  * State machine for state 3, Connected State.
 150  * The handling of the timer(s) is in file nr_timer.c
 151  * Handling of state 0 and connection release is in netrom.c.
 152  */
 153 static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 154 {
 155         struct sk_buff_head temp_queue;
 156         struct sk_buff *skbn;
 157         unsigned short save_vr;
 158         unsigned short nr, ns;
 159         int queued = 0;
 160
 161         nr = skb->data[18];
 162         ns = skb->data[17];
 163
 164         switch (frametype) {
 165
 166                 case NR_CONNREQ:
 167                         nr_write_internal(sk, NR_CONNACK);
 168                         break;
 169
 170                 case NR_DISCREQ:
 171                         nr_write_internal(sk, NR_DISCACK);
 172                         nr_disconnect(sk, 0);
 173                         break;
 174
 175                 case NR_CONNACK | NR_CHOKE_FLAG:
 176                 case NR_DISCACK:
 177                         nr_disconnect(sk, ECONNRESET);
 178                         break;
 179
 180                 case NR_INFOACK:
 181                 case NR_INFOACK | NR_CHOKE_FLAG:
 182                 case NR_INFOACK | NR_NAK_FLAG:
 183                 case NR_INFOACK | NR_NAK_FLAG | NR_CHOKE_FLAG:
 184                         if (frametype & NR_CHOKE_FLAG) {
 185                                 sk->protinfo.nr->condition |= NR_COND_PEER_RX_BUSY;
 186                                 nr_start_t4timer(sk);
 187                         } else {
 188                                 sk->protinfo.nr->condition &= ~NR_COND_PEER_RX_BUSY;
 189                                 nr_stop_t4timer(sk);
 190                         }
 191                         if (!nr_validate_nr(sk, nr)) {
 192                                 break;
 193                         }
 194                         if (frametype & NR_NAK_FLAG) {
 195                                 nr_frames_acked(sk, nr);
 196                                 nr_send_nak_frame(sk);
 197                         } else {
 198                                 if (sk->protinfo.nr->condition & NR_COND_PEER_RX_BUSY) {
 199                                         nr_frames_acked(sk, nr);
 200                                 } else {
 201                                         nr_check_iframes_acked(sk, nr);
 202                                 }
 203                         }
 204                         break;
 205
 206                 case NR_INFO:
 207                 case NR_INFO | NR_NAK_FLAG:
 208                 case NR_INFO | NR_CHOKE_FLAG:
 209                 case NR_INFO | NR_MORE_FLAG:
 210                 case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG:
 211                 case NR_INFO | NR_CHOKE_FLAG | NR_MORE_FLAG:
 212                 case NR_INFO | NR_NAK_FLAG | NR_MORE_FLAG:
 213                 case NR_INFO | NR_NAK_FLAG | NR_CHOKE_FLAG | NR_MORE_FLAG:
 214                         if (frametype & NR_CHOKE_FLAG) {
 215                                 sk->protinfo.nr->condition |= NR_COND_PEER_RX_BUSY;
 216                                 nr_start_t4timer(sk);
 217                         } else {
 218                                 sk->protinfo.nr->condition &= ~NR_COND_PEER_RX_BUSY;
 219                                 nr_stop_t4timer(sk);
 220                         }
 221                         if (nr_validate_nr(sk, nr)) {
 222                                 if (frametype & NR_NAK_FLAG) {
 223                                         nr_frames_acked(sk, nr);
 224                                         nr_send_nak_frame(sk);
 225                                 } else {
 226                                         if (sk->protinfo.nr->condition & NR_COND_PEER_RX_BUSY) {
 227                                                 nr_frames_acked(sk, nr);
 228                                         } else {
 229                                                 nr_check_iframes_acked(sk, nr);
 230                                         }
 231                                 }
 232                         }
 233                         queued = 1;
 234                         skb_queue_head(&sk->protinfo.nr->reseq_queue, skb);
 235                         if (sk->protinfo.nr->condition & NR_COND_OWN_RX_BUSY)
 236                                 break;
 237                         skb_queue_head_init(&temp_queue);
 238                         do {
 239                                 save_vr = sk->protinfo.nr->vr;
 240                                 while ((skbn = skb_dequeue(&sk->protinfo.nr->reseq_queue)) != NULL) {
 241                                         ns = skbn->data[17];
 242                                         if (ns == sk->protinfo.nr->vr) {
 243                                                 if (nr_queue_rx_frame(sk, skbn, frametype & NR_MORE_FLAG) == 0) {
 244                                                         sk->protinfo.nr->vr = (sk->protinfo.nr->vr + 1) % NR_MODULUS;
 245                                                 } else {
 246                                                         sk->protinfo.nr->condition |= NR_COND_OWN_RX_BUSY;
 247                                                         skb_queue_tail(&temp_queue, skbn);
 248                                                 }
 249                                         } else if (nr_in_rx_window(sk, ns)) {
 250                                                 skb_queue_tail(&temp_queue, skbn);
 251                                         } else {
 252                                                 kfree_skb(skbn);
 253                                         }
 254                                 }
 255                                 while ((skbn = skb_dequeue(&temp_queue)) != NULL) {
 256                                         skb_queue_tail(&sk->protinfo.nr->reseq_queue, skbn);
 257                                 }
 258                         } while (save_vr != sk->protinfo.nr->vr);
 259                         /*
 260                          * Window is full, ack it immediately.
 261                          */
 262                         if (((sk->protinfo.nr->vl + sk->protinfo.nr->window) % NR_MODULUS) == sk->protinfo.nr->vr) {
 263                                 nr_enquiry_response(sk);
 264                         } else {
 265                                 if (!(sk->protinfo.nr->condition & NR_COND_ACK_PENDING)) {
 266                                         sk->protinfo.nr->condition |= NR_COND_ACK_PENDING;
 267                                         nr_start_t2timer(sk);
 268                                 }
 269                         }
 270                         break;
 271
 272                 default:
 273                         break;
 274         }
 275
 276         return queued;
 277 }
 278
 279 /* Higher level upcall for a LAPB frame */
 280 int nr_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 281 {
 282         int queued = 0, frametype;
 283
 284         if (sk->protinfo.nr->state == NR_STATE_0)
 285                 return 0;
 286
 287         frametype = skb->data[19];
 288
 289         switch (sk->protinfo.nr->state) {
 290                 case NR_STATE_1:
 291                         queued = nr_state1_machine(sk, skb, frametype);
 292                         break;
 293                 case NR_STATE_2:
 294                         queued = nr_state2_machine(sk, skb, frametype);
 295                         break;
 296                 case NR_STATE_3:
 297                         queued = nr_state3_machine(sk, skb, frametype);
 298                         break;
 299         }
 300
 301         nr_kick(sk);
 302
 303         return queued;
 304 }