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