net/netrom/nr_out.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 Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   8  * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
   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 <asm/uaccess.h>
  26 #include <asm/system.h>
  27 #include <linux/fcntl.h>
  28 #include <linux/mm.h>
  29 #include <linux/interrupt.h>
  30 #include <net/netrom.h>
  31
  32 /*
  33  *      This is where all NET/ROM frames pass, except for IP-over-NET/ROM which
  34  *      cannot be fragmented in this manner.
  35  */
  36 void nr_output(struct sock *sk, struct sk_buff *skb)
  37 {
  38         struct sk_buff *skbn;
  39         unsigned char transport[NR_TRANSPORT_LEN];
  40         int err, frontlen, len;
  41
  42         if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
  43                 /* Save a copy of the Transport Header */
  44                 memcpy(transport, skb->data, NR_TRANSPORT_LEN);
  45                 skb_pull(skb, NR_TRANSPORT_LEN);
  46
  47                 frontlen = skb_headroom(skb);
  48
  49                 while (skb->len > 0) {
  50                         if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
  51                                 return;
  52
  53                         skb_reserve(skbn, frontlen);
  54
  55                         len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;
  56
  57                         /* Copy the user data */
  58                         memcpy(skb_put(skbn, len), skb->data, len);
  59                         skb_pull(skb, len);
  60
  61                         /* Duplicate the Transport Header */
  62                         skb_push(skbn, NR_TRANSPORT_LEN);
  63                         memcpy(skbn->data, transport, NR_TRANSPORT_LEN);
  64
  65                         if (skb->len > 0)
  66                                 skbn->data[4] |= NR_MORE_FLAG;
  67
  68                         skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
  69                 }
  70
  71                 kfree_skb(skb);
  72         } else {
  73                 skb_queue_tail(&sk->sk_write_queue, skb);               /* Throw it on the queue */
  74         }
  75
  76         nr_kick(sk);
  77 }
  78
  79 /*
  80  *      This procedure is passed a buffer descriptor for an iframe. It builds
  81  *      the rest of the control part of the frame and then writes it out.
  82  */
  83 static void nr_send_iframe(struct sock *sk, struct sk_buff *skb)
  84 {
  85         struct nr_sock *nr = nr_sk(sk);
  86
  87         if (skb == NULL)
  88                 return;
  89
  90         skb->data[2] = nr->vs;
  91         skb->data[3] = nr->vr;
  92
  93         if (nr->condition & NR_COND_OWN_RX_BUSY)
  94                 skb->data[4] |= NR_CHOKE_FLAG;
  95
  96         nr_start_idletimer(sk);
  97
  98         nr_transmit_buffer(sk, skb);
  99 }
 100
 101 void nr_send_nak_frame(struct sock *sk)
 102 {
 103         struct sk_buff *skb, *skbn;
 104         struct nr_sock *nr = nr_sk(sk);
 105
 106         if ((skb = skb_peek(&nr->ack_queue)) == NULL)
 107                 return;
 108
 109         if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
 110                 return;
 111
 112         skbn->data[2] = nr->va;
 113         skbn->data[3] = nr->vr;
 114
 115         if (nr->condition & NR_COND_OWN_RX_BUSY)
 116                 skbn->data[4] |= NR_CHOKE_FLAG;
 117
 118         nr_transmit_buffer(sk, skbn);
 119
 120         nr->condition &= ~NR_COND_ACK_PENDING;
 121         nr->vl         = nr->vr;
 122
 123         nr_stop_t1timer(sk);
 124 }
 125
 126 void nr_kick(struct sock *sk)
 127 {
 128         struct nr_sock *nr = nr_sk(sk);
 129         struct sk_buff *skb, *skbn;
 130         unsigned short start, end;
 131
 132         if (nr->state != NR_STATE_3)
 133                 return;
 134
 135         if (nr->condition & NR_COND_PEER_RX_BUSY)
 136                 return;
 137
 138         if (!skb_peek(&sk->sk_write_queue))
 139                 return;
 140
 141         start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs;
 142         end   = (nr->va + nr->window) % NR_MODULUS;
 143
 144         if (start == end)
 145                 return;
 146
 147         nr->vs = start;
 148
 149         /*
 150          * Transmit data until either we're out of data to send or
 151          * the window is full.
 152          */
 153
 154         /*
 155          * Dequeue the frame and copy it.
 156          */
 157         skb = skb_dequeue(&sk->sk_write_queue);
 158
 159         do {
 160                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 161                         skb_queue_head(&sk->sk_write_queue, skb);
 162                         break;
 163                 }
 164
 165                 skb_set_owner_w(skbn, sk);
 166
 167                 /*
 168                  * Transmit the frame copy.
 169                  */
 170                 nr_send_iframe(sk, skbn);
 171
 172                 nr->vs = (nr->vs + 1) % NR_MODULUS;
 173
 174                 /*
 175                  * Requeue the original data frame.
 176                  */
 177                 skb_queue_tail(&nr->ack_queue, skb);
 178
 179         } while (nr->vs != end &&
 180                  (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
 181
 182         nr->vl         = nr->vr;
 183         nr->condition &= ~NR_COND_ACK_PENDING;
 184
 185         if (!nr_t1timer_running(sk))
 186                 nr_start_t1timer(sk);
 187 }
 188
 189 void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
 190 {
 191         struct nr_sock *nr = nr_sk(sk);
 192         unsigned char *dptr;
 193
 194         /*
 195          *      Add the protocol byte and network header.
 196          */
 197         dptr = skb_push(skb, NR_NETWORK_LEN);
 198
 199         memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
 200         dptr[6] &= ~AX25_CBIT;
 201         dptr[6] &= ~AX25_EBIT;
 202         dptr[6] |= AX25_SSSID_SPARE;
 203         dptr += AX25_ADDR_LEN;
 204
 205         memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN);
 206         dptr[6] &= ~AX25_CBIT;
 207         dptr[6] |= AX25_EBIT;
 208         dptr[6] |= AX25_SSSID_SPARE;
 209         dptr += AX25_ADDR_LEN;
 210
 211         *dptr++ = sysctl_netrom_network_ttl_initialiser;
 212
 213         if (!nr_route_frame(skb, NULL)) {
 214                 kfree_skb(skb);
 215                 nr_disconnect(sk, ENETUNREACH);
 216         }
 217 }
 218
 219 /*
 220  * The following routines are taken from page 170 of the 7th ARRL Computer
 221  * Networking Conference paper, as is the whole state machine.
 222  */
 223
 224 void nr_establish_data_link(struct sock *sk)
 225 {
 226         struct nr_sock *nr = nr_sk(sk);
 227
 228         nr->condition = 0x00;
 229         nr->n2count   = 0;
 230
 231         nr_write_internal(sk, NR_CONNREQ);
 232
 233         nr_stop_t2timer(sk);
 234         nr_stop_t4timer(sk);
 235         nr_stop_idletimer(sk);
 236         nr_start_t1timer(sk);
 237 }
 238
 239 /*
 240  * Never send a NAK when we are CHOKEd.
 241  */
 242 void nr_enquiry_response(struct sock *sk)
 243 {
 244         struct nr_sock *nr = nr_sk(sk);
 245         int frametype = NR_INFOACK;
 246
 247         if (nr->condition & NR_COND_OWN_RX_BUSY) {
 248                 frametype |= NR_CHOKE_FLAG;
 249         } else {
 250                 if (skb_peek(&nr->reseq_queue) != NULL)
 251                         frametype |= NR_NAK_FLAG;
 252         }
 253
 254         nr_write_internal(sk, frametype);
 255
 256         nr->vl         = nr->vr;
 257         nr->condition &= ~NR_COND_ACK_PENDING;
 258 }
 259
 260 void nr_check_iframes_acked(struct sock *sk, unsigned short nr)
 261 {
 262         struct nr_sock *nrom = nr_sk(sk);
 263
 264         if (nrom->vs == nr) {
 265                 nr_frames_acked(sk, nr);
 266                 nr_stop_t1timer(sk);
 267                 nrom->n2count = 0;
 268         } else {
 269                 if (nrom->va != nr) {
 270                         nr_frames_acked(sk, nr);
 271                         nr_start_t1timer(sk);
 272                 }
 273         }
 274 }