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 <net/ax25.h>
19#include <linux/inet.h>
20#include <linux/netdevice.h>
21#include <linux/skbuff.h>
22#include <net/sock.h>
23#include <asm/system.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 */
33static 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
48void 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
112void 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