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/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 <linux/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  */
  35 void 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  */
  82 static 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
 100 void 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
 125 void 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
 188 void 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
 223 void 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  */
 241 void 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
 259 void 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 }