net/netrom/nr_subr.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *
0004  * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
0005  */
0006 #include <linux/errno.h>
0007 #include <linux/types.h>
0008 #include <linux/socket.h>
0009 #include <linux/in.h>
0010 #include <linux/kernel.h>
0011 #include <linux/timer.h>
0012 #include <linux/string.h>
0013 #include <linux/sockios.h>
0014 #include <linux/net.h>
0015 #include <linux/slab.h>
0016 #include <net/ax25.h>
0017 #include <linux/inet.h>
0018 #include <linux/netdevice.h>
0019 #include <linux/skbuff.h>
0020 #include <net/sock.h>
0021 #include <net/tcp_states.h>
0022 #include <linux/uaccess.h>
0023 #include <linux/fcntl.h>
0024 #include <linux/mm.h>
0025 #include <linux/interrupt.h>
0026 #include <net/netrom.h>
0027
0028 /*
0029  *  This routine purges all of the queues of frames.
0030  */
0031 void nr_clear_queues(struct sock *sk)
0032 {
0033     struct nr_sock *nr = nr_sk(sk);
0034
0035     skb_queue_purge(&sk->sk_write_queue);
0036     skb_queue_purge(&nr->ack_queue);
0037     skb_queue_purge(&nr->reseq_queue);
0038     skb_queue_purge(&nr->frag_queue);
0039 }
0040
0041 /*
0042  * This routine purges the input queue of those frames that have been
0043  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
0044  * SDL diagram.
0045  */
0046 void nr_frames_acked(struct sock *sk, unsigned short nr)
0047 {
0048     struct nr_sock *nrom = nr_sk(sk);
0049     struct sk_buff *skb;
0050
0051     /*
0052      * Remove all the ack-ed frames from the ack queue.
0053      */
0054     if (nrom->va != nr) {
0055         while (skb_peek(&nrom->ack_queue) != NULL && nrom->va != nr) {
0056             skb = skb_dequeue(&nrom->ack_queue);
0057             kfree_skb(skb);
0058             nrom->va = (nrom->va + 1) % NR_MODULUS;
0059         }
0060     }
0061 }
0062
0063 /*
0064  * Requeue all the un-ack-ed frames on the output queue to be picked
0065  * up by nr_kick called from the timer. This arrangement handles the
0066  * possibility of an empty output queue.
0067  */
0068 void nr_requeue_frames(struct sock *sk)
0069 {
0070     struct sk_buff *skb, *skb_prev = NULL;
0071
0072     while ((skb = skb_dequeue(&nr_sk(sk)->ack_queue)) != NULL) {
0073         if (skb_prev == NULL)
0074             skb_queue_head(&sk->sk_write_queue, skb);
0075         else
0076             skb_append(skb_prev, skb, &sk->sk_write_queue);
0077         skb_prev = skb;
0078     }
0079 }
0080
0081 /*
0082  *  Validate that the value of nr is between va and vs. Return true or
0083  *  false for testing.
0084  */
0085 int nr_validate_nr(struct sock *sk, unsigned short nr)
0086 {
0087     struct nr_sock *nrom = nr_sk(sk);
0088     unsigned short vc = nrom->va;
0089
0090     while (vc != nrom->vs) {
0091         if (nr == vc) return 1;
0092         vc = (vc + 1) % NR_MODULUS;
0093     }
0094
0095     return nr == nrom->vs;
0096 }
0097
0098 /*
0099  *  Check that ns is within the receive window.
0100  */
0101 int nr_in_rx_window(struct sock *sk, unsigned short ns)
0102 {
0103     struct nr_sock *nr = nr_sk(sk);
0104     unsigned short vc = nr->vr;
0105     unsigned short vt = (nr->vl + nr->window) % NR_MODULUS;
0106
0107     while (vc != vt) {
0108         if (ns == vc) return 1;
0109         vc = (vc + 1) % NR_MODULUS;
0110     }
0111
0112     return 0;
0113 }
0114
0115 /*
0116  *  This routine is called when the HDLC layer internally generates a
0117  *  control frame.
0118  */
0119 void nr_write_internal(struct sock *sk, int frametype)
0120 {
0121     struct nr_sock *nr = nr_sk(sk);
0122     struct sk_buff *skb;
0123     unsigned char  *dptr;
0124     int len, timeout;
0125
0126     len = NR_NETWORK_LEN + NR_TRANSPORT_LEN;
0127
0128     switch (frametype & 0x0F) {
0129     case NR_CONNREQ:
0130         len += 17;
0131         break;
0132     case NR_CONNACK:
0133         len += (nr->bpqext) ? 2 : 1;
0134         break;
0135     case NR_DISCREQ:
0136     case NR_DISCACK:
0137     case NR_INFOACK:
0138         break;
0139     default:
0140         printk(KERN_ERR "NET/ROM: nr_write_internal - invalid frame type %d\n", frametype);
0141         return;
0142     }
0143
0144     if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
0145         return;
0146
0147     /*
0148      *  Space for AX.25 and NET/ROM network header
0149      */
0150     skb_reserve(skb, NR_NETWORK_LEN);
0151
0152     dptr = skb_put(skb, skb_tailroom(skb));
0153
0154     switch (frametype & 0x0F) {
0155     case NR_CONNREQ:
0156         timeout  = nr->t1 / HZ;
0157         *dptr++  = nr->my_index;
0158         *dptr++  = nr->my_id;
0159         *dptr++  = 0;
0160         *dptr++  = 0;
0161         *dptr++  = frametype;
0162         *dptr++  = nr->window;
0163         memcpy(dptr, &nr->user_addr, AX25_ADDR_LEN);
0164         dptr[6] &= ~AX25_CBIT;
0165         dptr[6] &= ~AX25_EBIT;
0166         dptr[6] |= AX25_SSSID_SPARE;
0167         dptr    += AX25_ADDR_LEN;
0168         memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
0169         dptr[6] &= ~AX25_CBIT;
0170         dptr[6] &= ~AX25_EBIT;
0171         dptr[6] |= AX25_SSSID_SPARE;
0172         dptr    += AX25_ADDR_LEN;
0173         *dptr++  = timeout % 256;
0174         *dptr++  = timeout / 256;
0175         break;
0176
0177     case NR_CONNACK:
0178         *dptr++ = nr->your_index;
0179         *dptr++ = nr->your_id;
0180         *dptr++ = nr->my_index;
0181         *dptr++ = nr->my_id;
0182         *dptr++ = frametype;
0183         *dptr++ = nr->window;
0184         if (nr->bpqext) *dptr++ = sysctl_netrom_network_ttl_initialiser;
0185         break;
0186
0187     case NR_DISCREQ:
0188     case NR_DISCACK:
0189         *dptr++ = nr->your_index;
0190         *dptr++ = nr->your_id;
0191         *dptr++ = 0;
0192         *dptr++ = 0;
0193         *dptr++ = frametype;
0194         break;
0195
0196     case NR_INFOACK:
0197         *dptr++ = nr->your_index;
0198         *dptr++ = nr->your_id;
0199         *dptr++ = 0;
0200         *dptr++ = nr->vr;
0201         *dptr++ = frametype;
0202         break;
0203     }
0204
0205     nr_transmit_buffer(sk, skb);
0206 }
0207
0208 /*
0209  * This routine is called to send an error reply.
0210  */
0211 void __nr_transmit_reply(struct sk_buff *skb, int mine, unsigned char cmdflags)
0212 {
0213     struct sk_buff *skbn;
0214     unsigned char *dptr;
0215     int len;
0216
0217     len = NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1;
0218
0219     if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL)
0220         return;
0221
0222     skb_reserve(skbn, 0);
0223
0224     dptr = skb_put(skbn, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
0225
0226     skb_copy_from_linear_data_offset(skb, 7, dptr, AX25_ADDR_LEN);
0227     dptr[6] &= ~AX25_CBIT;
0228     dptr[6] &= ~AX25_EBIT;
0229     dptr[6] |= AX25_SSSID_SPARE;
0230     dptr += AX25_ADDR_LEN;
0231
0232     skb_copy_from_linear_data(skb, dptr, AX25_ADDR_LEN);
0233     dptr[6] &= ~AX25_CBIT;
0234     dptr[6] |= AX25_EBIT;
0235     dptr[6] |= AX25_SSSID_SPARE;
0236     dptr += AX25_ADDR_LEN;
0237
0238     *dptr++ = sysctl_netrom_network_ttl_initialiser;
0239
0240     if (mine) {
0241         *dptr++ = 0;
0242         *dptr++ = 0;
0243         *dptr++ = skb->data[15];
0244         *dptr++ = skb->data[16];
0245     } else {
0246         *dptr++ = skb->data[15];
0247         *dptr++ = skb->data[16];
0248         *dptr++ = 0;
0249         *dptr++ = 0;
0250     }
0251
0252     *dptr++ = cmdflags;
0253     *dptr++ = 0;
0254
0255     if (!nr_route_frame(skbn, NULL))
0256         kfree_skb(skbn);
0257 }
0258
0259 void nr_disconnect(struct sock *sk, int reason)
0260 {
0261     nr_stop_t1timer(sk);
0262     nr_stop_t2timer(sk);
0263     nr_stop_t4timer(sk);
0264     nr_stop_idletimer(sk);
0265
0266     nr_clear_queues(sk);
0267
0268     nr_sk(sk)->state = NR_STATE_0;
0269
0270     sk->sk_state     = TCP_CLOSE;
0271     sk->sk_err       = reason;
0272     sk->sk_shutdown |= SEND_SHUTDOWN;
0273
0274     if (!sock_flag(sk, SOCK_DEAD)) {
0275         sk->sk_state_change(sk);
0276         sock_set_flag(sk, SOCK_DEAD);
0277     }
0278 }