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 <asm/system.h>
25#include <linux/fcntl.h>
26#include <linux/mm.h>
27#include <linux/interrupt.h>
28#include <net/rose.h>
29
30/*
31 *	This procedure is passed a buffer descriptor for an iframe. It builds
32 *	the rest of the control part of the frame and then writes it out.
33 */
34static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
35{
36	struct rose_sock *rose = rose_sk(sk);
37
38	if (skb == NULL)
39		return;
40
41	skb->data[2] |= (rose->vr << 5) & 0xE0;
42	skb->data[2] |= (rose->vs << 1) & 0x0E;
43
44	rose_start_idletimer(sk);
45
46	rose_transmit_link(skb, rose->neighbour);
47}
48
49void rose_kick(struct sock *sk)
50{
51	struct rose_sock *rose = rose_sk(sk);
52	struct sk_buff *skb, *skbn;
53	unsigned short start, end;
54
55	if (rose->state != ROSE_STATE_3)
56		return;
57
58	if (rose->condition & ROSE_COND_PEER_RX_BUSY)
59		return;
60
61	if (!skb_peek(&sk->sk_write_queue))
62		return;
63
64	start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
65	end   = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
66
67	if (start == end)
68		return;
69
70	rose->vs = start;
71
72	/*
73	 * Transmit data until either we're out of data to send or
74	 * the window is full.
75	 */
76
77	skb  = skb_dequeue(&sk->sk_write_queue);
78
79	do {
80		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
81			skb_queue_head(&sk->sk_write_queue, skb);
82			break;
83		}
84
85		skb_set_owner_w(skbn, sk);
86
87		/*
88		 * Transmit the frame copy.
89		 */
90		rose_send_iframe(sk, skbn);
91
92		rose->vs = (rose->vs + 1) % ROSE_MODULUS;
93
94		/*
95		 * Requeue the original data frame.
96		 */
97		skb_queue_tail(&rose->ack_queue, skb);
98
99	} while (rose->vs != end &&
100		 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
101
102	rose->vl         = rose->vr;
103	rose->condition &= ~ROSE_COND_ACK_PENDING;
104
105	rose_stop_timer(sk);
106}
107
108/*
109 * The following routines are taken from page 170 of the 7th ARRL Computer
110 * Networking Conference paper, as is the whole state machine.
111 */
112
113void rose_enquiry_response(struct sock *sk)
114{
115	struct rose_sock *rose = rose_sk(sk);
116
117	if (rose->condition & ROSE_COND_OWN_RX_BUSY)
118		rose_write_internal(sk, ROSE_RNR);
119	else
120		rose_write_internal(sk, ROSE_RR);
121
122	rose->vl         = rose->vr;
123	rose->condition &= ~ROSE_COND_ACK_PENDING;
124
125	rose_stop_timer(sk);
126}
127