net/netrom/nr_subr.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *
   4  * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   5  */
   6 #include <linux/errno.h>
   7 #include <linux/types.h>
   8 #include <linux/socket.h>
   9 #include <linux/in.h>
  10 #include <linux/kernel.h>
  11 #include <linux/timer.h>
  12 #include <linux/string.h>
  13 #include <linux/sockios.h>
  14 #include <linux/net.h>
  15 #include <linux/slab.h>
  16 #include <net/ax25.h>
  17 #include <linux/inet.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/skbuff.h>
  20 #include <net/sock.h>
  21 #include <net/tcp_states.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/fcntl.h>
  24 #include <linux/mm.h>
  25 #include <linux/interrupt.h>
  26 #include <net/netrom.h>
  27
  28 /*
  29  *      This routine purges all of the queues of frames.
  30  */
  31 void nr_clear_queues(struct sock *sk)
  32 {
  33         struct nr_sock *nr = nr_sk(sk);
  34
  35         skb_queue_purge(&sk->sk_write_queue);
  36         skb_queue_purge(&nr->ack_queue);
  37         skb_queue_purge(&nr->reseq_queue);
  38         skb_queue_purge(&nr->frag_queue);
  39 }
  40
  41 /*
  42  * This routine purges the input queue of those frames that have been
  43  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  44  * SDL diagram.
  45  */
  46 void nr_frames_acked(struct sock *sk, unsigned short nr)
  47 {
  48         struct nr_sock *nrom = nr_sk(sk);
  49         struct sk_buff *skb;
  50
  51         /*
  52          * Remove all the ack-ed frames from the ack queue.
  53          */
  54         if (nrom->va != nr) {
  55                 while (skb_peek(&nrom->ack_queue) != NULL && nrom->va != nr) {
  56                         skb = skb_dequeue(&nrom->ack_queue);
  57                         kfree_skb(skb);
  58                         nrom->va = (nrom->va + 1) % NR_MODULUS;
  59                 }
  60         }
  61 }
  62
  63 /*
  64  * Requeue all the un-ack-ed frames on the output queue to be picked
  65  * up by nr_kick called from the timer. This arrangement handles the
  66  * possibility of an empty output queue.
  67  */
  68 void nr_requeue_frames(struct sock *sk)
  69 {
  70         struct sk_buff *skb, *skb_prev = NULL;
  71
  72         while ((skb = skb_dequeue(&nr_sk(sk)->ack_queue)) != NULL) {
  73                 if (skb_prev == NULL)
  74                         skb_queue_head(&sk->sk_write_queue, skb);
  75                 else
  76                         skb_append(skb_prev, skb, &sk->sk_write_queue);
  77                 skb_prev = skb;
  78         }
  79 }
  80
  81 /*
  82  *      Validate that the value of nr is between va and vs. Return true or
  83  *      false for testing.
  84  */
  85 int nr_validate_nr(struct sock *sk, unsigned short nr)
  86 {
  87         struct nr_sock *nrom = nr_sk(sk);
  88         unsigned short vc = nrom->va;
  89
  90         while (vc != nrom->vs) {
  91                 if (nr == vc) return 1;
  92                 vc = (vc + 1) % NR_MODULUS;
  93         }
  94
  95         return nr == nrom->vs;
  96 }
  97
  98 /*
  99  *      Check that ns is within the receive window.
 100  */
 101 int nr_in_rx_window(struct sock *sk, unsigned short ns)
 102 {
 103         struct nr_sock *nr = nr_sk(sk);
 104         unsigned short vc = nr->vr;
 105         unsigned short vt = (nr->vl + nr->window) % NR_MODULUS;
 106
 107         while (vc != vt) {
 108                 if (ns == vc) return 1;
 109                 vc = (vc + 1) % NR_MODULUS;
 110         }
 111
 112         return 0;
 113 }
 114
 115 /*
 116  *  This routine is called when the HDLC layer internally generates a
 117  *  control frame.
 118  */
 119 void nr_write_internal(struct sock *sk, int frametype)
 120 {
 121         struct nr_sock *nr = nr_sk(sk);
 122         struct sk_buff *skb;
 123         unsigned char  *dptr;
 124         int len, timeout;
 125
 126         len = NR_NETWORK_LEN + NR_TRANSPORT_LEN;
 127
 128         switch (frametype & 0x0F) {
 129         case NR_CONNREQ:
 130                 len += 17;
 131                 break;
 132         case NR_CONNACK:
 133                 len += (nr->bpqext) ? 2 : 1;
 134                 break;
 135         case NR_DISCREQ:
 136         case NR_DISCACK:
 137         case NR_INFOACK:
 138                 break;
 139         default:
 140                 printk(KERN_ERR "NET/ROM: nr_write_internal - invalid frame type %d\n", frametype);
 141                 return;
 142         }
 143
 144         if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
 145                 return;
 146
 147         /*
 148          *      Space for AX.25 and NET/ROM network header
 149          */
 150         skb_reserve(skb, NR_NETWORK_LEN);
 151
 152         dptr = skb_put(skb, skb_tailroom(skb));
 153
 154         switch (frametype & 0x0F) {
 155         case NR_CONNREQ:
 156                 timeout  = nr->t1 / HZ;
 157                 *dptr++  = nr->my_index;
 158                 *dptr++  = nr->my_id;
 159                 *dptr++  = 0;
 160                 *dptr++  = 0;
 161                 *dptr++  = frametype;
 162                 *dptr++  = nr->window;
 163                 memcpy(dptr, &nr->user_addr, AX25_ADDR_LEN);
 164                 dptr[6] &= ~AX25_CBIT;
 165                 dptr[6] &= ~AX25_EBIT;
 166                 dptr[6] |= AX25_SSSID_SPARE;
 167                 dptr    += AX25_ADDR_LEN;
 168                 memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
 169                 dptr[6] &= ~AX25_CBIT;
 170                 dptr[6] &= ~AX25_EBIT;
 171                 dptr[6] |= AX25_SSSID_SPARE;
 172                 dptr    += AX25_ADDR_LEN;
 173                 *dptr++  = timeout % 256;
 174                 *dptr++  = timeout / 256;
 175                 break;
 176
 177         case NR_CONNACK:
 178                 *dptr++ = nr->your_index;
 179                 *dptr++ = nr->your_id;
 180                 *dptr++ = nr->my_index;
 181                 *dptr++ = nr->my_id;
 182                 *dptr++ = frametype;
 183                 *dptr++ = nr->window;
 184                 if (nr->bpqext) *dptr++ = sysctl_netrom_network_ttl_initialiser;
 185                 break;
 186
 187         case NR_DISCREQ:
 188         case NR_DISCACK:
 189                 *dptr++ = nr->your_index;
 190                 *dptr++ = nr->your_id;
 191                 *dptr++ = 0;
 192                 *dptr++ = 0;
 193                 *dptr++ = frametype;
 194                 break;
 195
 196         case NR_INFOACK:
 197                 *dptr++ = nr->your_index;
 198                 *dptr++ = nr->your_id;
 199                 *dptr++ = 0;
 200                 *dptr++ = nr->vr;
 201                 *dptr++ = frametype;
 202                 break;
 203         }
 204
 205         nr_transmit_buffer(sk, skb);
 206 }
 207
 208 /*
 209  * This routine is called to send an error reply.
 210  */
 211 void __nr_transmit_reply(struct sk_buff *skb, int mine, unsigned char cmdflags)
 212 {
 213         struct sk_buff *skbn;
 214         unsigned char *dptr;
 215         int len;
 216
 217         len = NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1;
 218
 219         if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL)
 220                 return;
 221
 222         skb_reserve(skbn, 0);
 223
 224         dptr = skb_put(skbn, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
 225
 226         skb_copy_from_linear_data_offset(skb, 7, dptr, AX25_ADDR_LEN);
 227         dptr[6] &= ~AX25_CBIT;
 228         dptr[6] &= ~AX25_EBIT;
 229         dptr[6] |= AX25_SSSID_SPARE;
 230         dptr += AX25_ADDR_LEN;
 231
 232         skb_copy_from_linear_data(skb, dptr, AX25_ADDR_LEN);
 233         dptr[6] &= ~AX25_CBIT;
 234         dptr[6] |= AX25_EBIT;
 235         dptr[6] |= AX25_SSSID_SPARE;
 236         dptr += AX25_ADDR_LEN;
 237
 238         *dptr++ = sysctl_netrom_network_ttl_initialiser;
 239
 240         if (mine) {
 241                 *dptr++ = 0;
 242                 *dptr++ = 0;
 243                 *dptr++ = skb->data[15];
 244                 *dptr++ = skb->data[16];
 245         } else {
 246                 *dptr++ = skb->data[15];
 247                 *dptr++ = skb->data[16];
 248                 *dptr++ = 0;
 249                 *dptr++ = 0;
 250         }
 251
 252         *dptr++ = cmdflags;
 253         *dptr++ = 0;
 254
 255         if (!nr_route_frame(skbn, NULL))
 256                 kfree_skb(skbn);
 257 }
 258
 259 void nr_disconnect(struct sock *sk, int reason)
 260 {
 261         nr_stop_t1timer(sk);
 262         nr_stop_t2timer(sk);
 263         nr_stop_t4timer(sk);
 264         nr_stop_idletimer(sk);
 265
 266         nr_clear_queues(sk);
 267
 268         nr_sk(sk)->state = NR_STATE_0;
 269
 270         sk->sk_state     = TCP_CLOSE;
 271         sk->sk_err       = reason;
 272         sk->sk_shutdown |= SEND_SHUTDOWN;
 273
 274         if (!sock_flag(sk, SOCK_DEAD)) {
 275                 sk->sk_state_change(sk);
 276                 sock_set_flag(sk, SOCK_DEAD);
 277         }
 278 }