net/netrom/nr

/* */
This source file includes following definitions.
nr_clear_queues
nr_frames_acked
nr_requeue_frames
nr_validate_nr
nr_in_rx_window
nr_write_internal
nr_transmit_dm
nr_calculate_t1
nr_calculate_rtt
   1 /*
   2  *      NET/ROM release 003
   3  *
   4  *      This is ALPHA test software. This code may break your machine, randomly fail to work with new 
   5  *      releases, misbehave and/or generally screw up. It might even work. 
   6  *
   7  *      This code REQUIRES 1.2.1 or higher/ NET3.029
   8  *
   9  *      This module:
  10  *              This module is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or (at your option) any later version.
  14  *
  15  *      History
  16  *      NET/ROM 001     Jonathan(G4KLX) Cloned from ax25_subr.c
  17  *      NET/ROM 003     Jonathan(G4KLX) Added G8BPQ NET/ROM extensions.
  18  */
  19  
  20 #include <linux/config.h>
  21 #ifdef CONFIG_NETROM
  22 #include <linux/errno.h>
  23 #include <linux/types.h>
  24 #include <linux/socket.h>
  25 #include <linux/in.h>
  26 #include <linux/kernel.h>
  27 #include <linux/sched.h>
  28 #include <linux/timer.h>
  29 #include <linux/string.h>
  30 #include <linux/sockios.h>
  31 #include <linux/net.h>
  32 #include <net/ax25.h>
  33 #include <linux/inet.h>
  34 #include <linux/netdevice.h>
  35 #include <linux/skbuff.h>
  36 #include <net/sock.h>
  37 #include <asm/segment.h>
  38 #include <asm/system.h>
  39 #include <linux/fcntl.h>
  40 #include <linux/mm.h>
  41 #include <linux/interrupt.h>
  42 #include <net/netrom.h>
  43 
  44 /*
  45  *      This routine purges all of the queues of frames.
  46  */
  47 void nr_clear_queues(struct sock *sk)
     /*  */
  48 {
  49         struct sk_buff *skb;
  50 
  51         while ((skb = skb_dequeue(&sk->write_queue)) != NULL) {
  52                 skb->sk   = sk;
  53                 skb->free = 1;
  54                 kfree_skb(skb, FREE_WRITE);
  55         }
  56 
  57         while ((skb = skb_dequeue(&sk->nr->ack_queue)) != NULL) {
  58                 skb->sk   = sk;
  59                 skb->free = 1;
  60                 kfree_skb(skb, FREE_WRITE);
  61         }
  62 
  63         while ((skb = skb_dequeue(&sk->nr->reseq_queue)) != NULL) {
  64                 kfree_skb(skb, FREE_READ);
  65         }
  66 
  67         while ((skb = skb_dequeue(&sk->nr->frag_queue)) != NULL) {
  68                 kfree_skb(skb, FREE_READ);
  69         }
  70 }
  71 
  72 /*
  73  * This routine purges the input queue of those frames that have been
  74  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  75  * SDL diagram.
  76  */
  77 void nr_frames_acked(struct sock *sk, unsigned short nr)
     /*  */
  78 {
  79         struct sk_buff *skb;
  80 
  81         /*
  82          * Remove all the ack-ed frames from the ack queue.
  83          */
  84         if (sk->nr->va != nr) {
  85                 while (skb_peek(&sk->nr->ack_queue) != NULL && sk->nr->va != nr) {
  86                         skb = skb_dequeue(&sk->nr->ack_queue);
  87                         skb->sk   = sk;
  88                         skb->free = 1;
  89                         kfree_skb(skb, FREE_WRITE);
  90                         sk->nr->va = (sk->nr->va + 1) % NR_MODULUS;
  91                 }
  92         }
  93 }
  94 
  95 /*
  96  * Requeue all the un-ack-ed frames on the output queue to be picked
  97  * up by nr_kick called from the timer. This arrangement handles the
  98  * possibility of an empty output queue.
  99  */
 100 void nr_requeue_frames(struct sock *sk)
     /*  */
 101 {
 102         struct sk_buff *skb, *skb_prev = NULL;
 103 
 104         while ((skb = skb_dequeue(&sk->nr->ack_queue)) != NULL) {
 105                 if (skb_prev == NULL)
 106                         skb_queue_head(&sk->write_queue, skb);
 107                 else
 108                         skb_append(skb_prev, skb);
 109                 skb_prev = skb;
 110         }
 111 }
 112 
 113 /*
 114  *      Validate that the value of nr is between va and vs. Return true or
 115  *      false for testing.
 116  */
 117 int nr_validate_nr(struct sock *sk, unsigned short nr)
     /*  */
 118 {
 119         unsigned short vc = sk->nr->va;
 120 
 121         while (vc != sk->nr->vs) {
 122                 if (nr == vc) return 1;
 123                 vc = (vc + 1) % NR_MODULUS;
 124         }
 125         
 126         if (nr == sk->nr->vs) return 1;
 127 
 128         return 0;
 129 }
 130 
 131 /*
 132  *      Check that ns is within the receive window.
 133  */
 134 int nr_in_rx_window(struct sock *sk, unsigned short ns)
     /*  */
 135 {
 136         unsigned short vc = sk->nr->vl;
 137         unsigned short vt = (sk->nr->vl + sk->window) % NR_MODULUS;
 138 
 139         while (vc != vt) {
 140                 if (ns == vc) return 1;
 141                 vc = (vc + 1) % NR_MODULUS;
 142         }
 143         
 144         if (ns == vt) return 1;
 145 
 146         return 0;
 147 }
 148 
 149 /* 
 150  *  This routine is called when the HDLC layer internally generates a
 151  *  control frame.
 152  */
 153 void nr_write_internal(struct sock *sk, int frametype)
     /*  */
 154 {
 155         struct sk_buff *skb;
 156         unsigned char  *dptr;
 157         int len, timeout;
 158 
 159         len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + 3 + NR_NETWORK_LEN + NR_TRANSPORT_LEN;
 160         
 161         switch (frametype & 0x0F) {
 162                 case NR_CONNREQ:
 163                         len += 17;
 164                         break;
 165                 case NR_CONNACK:
 166                         len += (sk->nr->bpqext) ? 2 : 1;
 167                         break;
 168                 case NR_DISCREQ:
 169                 case NR_DISCACK:
 170                 case NR_INFOACK:
 171                         break;
 172                 default:
 173                         printk("nr_write_internal: invalid frame type %d\n", frametype);
 174                         return;
 175         }
 176         
 177         if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
 178                 return;
 179 
 180         /*
 181          *      Space for AX.25 and NET/ROM network header
 182          */
 183         skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + 2 + NR_NETWORK_LEN);
 184         
 185         dptr = skb_put(skb, skb_tailroom(skb));
 186 
 187         switch (frametype & 0x0F) {
 188 
 189                 case NR_CONNREQ:
 190                         timeout  = (sk->nr->rtt / PR_SLOWHZ) * 2;
 191                         *dptr++  = sk->nr->my_index;
 192                         *dptr++  = sk->nr->my_id;
 193                         *dptr++  = 0;
 194                         *dptr++  = 0;
 195                         *dptr++  = frametype;
 196                         *dptr++  = sk->window;
 197                         memcpy(dptr, &sk->nr->user_addr, sizeof(ax25_address));
 198                         dptr[6] &= ~LAPB_C;
 199                         dptr[6] &= ~LAPB_E;
 200                         dptr[6] |= SSSID_SPARE;
 201                         dptr    += AX25_ADDR_LEN;
 202                         memcpy(dptr, &sk->nr->source_addr, sizeof(ax25_address));
 203                         dptr[6] &= ~LAPB_C;
 204                         dptr[6] &= ~LAPB_E;
 205                         dptr[6] |= SSSID_SPARE;
 206                         dptr    += AX25_ADDR_LEN;
 207                         *dptr++  = timeout % 256;
 208                         *dptr++  = timeout / 256;
 209                         break;
 210 
 211                 case NR_CONNACK:
 212                         *dptr++ = sk->nr->your_index;
 213                         *dptr++ = sk->nr->your_id;
 214                         *dptr++ = sk->nr->my_index;
 215                         *dptr++ = sk->nr->my_id;
 216                         *dptr++ = frametype;
 217                         *dptr++ = sk->window;
 218                         if (sk->nr->bpqext) *dptr++ = nr_default.ttl;
 219                         break;
 220 
 221                 case NR_DISCREQ:
 222                 case NR_DISCACK:
 223                         *dptr++ = sk->nr->your_index;
 224                         *dptr++ = sk->nr->your_id;
 225                         *dptr++ = 0;
 226                         *dptr++ = 0;
 227                         *dptr++ = frametype;
 228                         break;
 229 
 230                 case NR_INFOACK:
 231                         *dptr++ = sk->nr->your_index;
 232                         *dptr++ = sk->nr->your_id;
 233                         *dptr++ = 0;
 234                         *dptr++ = sk->nr->vr;
 235                         *dptr++ = frametype;
 236                         break;
 237         }
 238 
 239         skb->free = 1;
 240 
 241         nr_transmit_buffer(sk, skb);
 242 }
 243 
 244 /*
 245  * This routine is called when a Connect Acknowledge with the Choke Flag
 246  * set is needed to refuse a connection.
 247  */
 248 void nr_transmit_dm(struct sk_buff *skb)
     /*  */
 249 {
 250         struct sk_buff *skbn;
 251         unsigned char *dptr;
 252         int len;
 253 
 254         len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + 3 + NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1;
 255 
 256         if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL)
 257                 return;
 258 
 259         skb_reserve(skbn, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + 2);
 260 
 261         dptr = skb_put(skbn, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
 262 
 263         memcpy(dptr, skb->data + 7, AX25_ADDR_LEN);
 264         dptr[6] &= ~LAPB_C;
 265         dptr[6] &= ~LAPB_E;
 266         dptr[6] |= SSSID_SPARE;
 267         dptr += AX25_ADDR_LEN;
 268         
 269         memcpy(dptr, skb->data + 0, AX25_ADDR_LEN);
 270         dptr[6] &= ~LAPB_C;
 271         dptr[6] |= LAPB_E;
 272         dptr[6] |= SSSID_SPARE;
 273         dptr += AX25_ADDR_LEN;
 274 
 275         *dptr++ = nr_default.ttl;
 276 
 277         *dptr++ = skb->data[15];
 278         *dptr++ = skb->data[16];
 279         *dptr++ = 0;
 280         *dptr++ = 0;
 281         *dptr++ = NR_CONNACK | NR_CHOKE_FLAG;
 282         *dptr++ = 0;
 283 
 284         skbn->free = 1;
 285         skbn->sk   = NULL;
 286 
 287         if (!nr_route_frame(skbn, NULL))
 288                 kfree_skb(skbn, FREE_WRITE);
 289 }
 290 
 291 /*
 292  *      Exponential backoff for NET/ROM
 293  */
 294 unsigned short nr_calculate_t1(struct sock *sk)
     /*  */
 295 {
 296         int n, t;
 297         
 298         for (t = 2, n = 0; n < sk->nr->n2count; n++)
 299                 t *= 2;
 300 
 301         if (t > 8) t = 8;
 302 
 303         return t * sk->nr->rtt;
 304 }
 305 
 306 /*
 307  *      Calculate the Round Trip Time
 308  */
 309 void nr_calculate_rtt(struct sock *sk)
     /*  */
 310 {
 311         if (sk->nr->t1timer > 0 && sk->nr->n2count == 0)
 312                 sk->nr->rtt = (9 * sk->nr->rtt + sk->nr->t1 - sk->nr->t1timer) / 10;
 313 
 314         /* Don't go below one second */
 315         if (sk->nr->rtt < 1 * PR_SLOWHZ)
 316                 sk->nr->rtt = 1 * PR_SLOWHZ;
 317 }
 318 
 319 #endif
/* */
root/net/netrom/nr_subr.c

DEFINITIONS
