linux/net/netrom/nr_out.c
<<
>>
Prefs
   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/timer.h>
  16#include <linux/string.h>
  17#include <linux/sockios.h>
  18#include <linux/net.h>
  19#include <linux/slab.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 */
  36void 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                skb_copy_from_linear_data(skb, transport, 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                        skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
  59                        skb_pull(skb, len);
  60
  61                        /* Duplicate the Transport Header */
  62                        skb_push(skbn, NR_TRANSPORT_LEN);
  63                        skb_copy_to_linear_data(skbn, transport,
  64                                                NR_TRANSPORT_LEN);
  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 */
  83static 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
 101void 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
 126void 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
 189void 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
 224void 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 */
 242void 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
 260void 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}
 275
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.