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 (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
8 */
9 #include <linux/errno.h>
10 #include <linux/types.h>
11 #include <linux/socket.h>
12 #include <linux/in.h>
13 #include <linux/kernel.h>
14 #include <linux/timer.h>
15 #include <linux/string.h>
16 #include <linux/sockios.h>
17 #include <linux/net.h>
18 #include <linux/gfp.h>
19 #include <net/ax25.h>
20 #include <linux/inet.h>
21 #include <linux/netdevice.h>
22 #include <linux/skbuff.h>
23 #include <net/sock.h>
24 #include <linux/fcntl.h>
25 #include <linux/mm.h>
26 #include <linux/interrupt.h>
27 #include <net/rose.h>
28
29 /*
30 * This procedure is passed a buffer descriptor for an iframe. It builds
31 * the rest of the control part of the frame and then writes it out.
32 */
rose_send_iframe(struct sock * sk,struct sk_buff * skb)33 static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
34 {
35 struct rose_sock *rose = rose_sk(sk);
36
37 if (skb == NULL)
38 return;
39
40 skb->data[2] |= (rose->vr << 5) & 0xE0;
41 skb->data[2] |= (rose->vs << 1) & 0x0E;
42
43 rose_start_idletimer(sk);
44
45 rose_transmit_link(skb, rose->neighbour);
46 }
47
rose_kick(struct sock * sk)48 void rose_kick(struct sock *sk)
49 {
50 struct rose_sock *rose = rose_sk(sk);
51 struct sk_buff *skb, *skbn;
52 unsigned short start, end;
53
54 if (rose->state != ROSE_STATE_3)
55 return;
56
57 if (rose->condition & ROSE_COND_PEER_RX_BUSY)
58 return;
59
60 if (!skb_peek(&sk->sk_write_queue))
61 return;
62
63 start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
64 end = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
65
66 if (start == end)
67 return;
68
69 rose->vs = start;
70
71 /*
72 * Transmit data until either we're out of data to send or
73 * the window is full.
74 */
75
76 skb = skb_dequeue(&sk->sk_write_queue);
77
78 do {
79 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
80 skb_queue_head(&sk->sk_write_queue, skb);
81 break;
82 }
83
84 skb_set_owner_w(skbn, sk);
85
86 /*
87 * Transmit the frame copy.
88 */
89 rose_send_iframe(sk, skbn);
90
91 rose->vs = (rose->vs + 1) % ROSE_MODULUS;
92
93 /*
94 * Requeue the original data frame.
95 */
96 skb_queue_tail(&rose->ack_queue, skb);
97
98 } while (rose->vs != end &&
99 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
100
101 rose->vl = rose->vr;
102 rose->condition &= ~ROSE_COND_ACK_PENDING;
103
104 rose_stop_timer(sk);
105 }
106
107 /*
108 * The following routines are taken from page 170 of the 7th ARRL Computer
109 * Networking Conference paper, as is the whole state machine.
110 */
111
rose_enquiry_response(struct sock * sk)112 void rose_enquiry_response(struct sock *sk)
113 {
114 struct rose_sock *rose = rose_sk(sk);
115
116 if (rose->condition & ROSE_COND_OWN_RX_BUSY)
117 rose_write_internal(sk, ROSE_RNR);
118 else
119 rose_write_internal(sk, ROSE_RR);
120
121 rose->vl = rose->vr;
122 rose->condition &= ~ROSE_COND_ACK_PENDING;
123
124 rose_stop_timer(sk);
125 }
126