1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *
4 * Copyright (C) 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/gfp.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 <linux/fcntl.h>
22#include <linux/mm.h>
23#include <linux/interrupt.h>
24#include <net/rose.h>
25
26/*
27 *	This procedure is passed a buffer descriptor for an iframe. It builds
28 *	the rest of the control part of the frame and then writes it out.
29 */
30static void rose_send_iframe(struct sock *sk, struct sk_buff *skb)
31{
32	struct rose_sock *rose = rose_sk(sk);
33
34	if (skb == NULL)
35		return;
36
37	skb->data[2] |= (rose->vr << 5) & 0xE0;
38	skb->data[2] |= (rose->vs << 1) & 0x0E;
39
40	rose_start_idletimer(sk);
41
42	rose_transmit_link(skb, rose->neighbour);
43}
44
45void rose_kick(struct sock *sk)
46{
47	struct rose_sock *rose = rose_sk(sk);
48	struct sk_buff *skb, *skbn;
49	unsigned short start, end;
50
51	if (rose->state != ROSE_STATE_3)
52		return;
53
54	if (rose->condition & ROSE_COND_PEER_RX_BUSY)
55		return;
56
57	if (!skb_peek(&sk->sk_write_queue))
58		return;
59
60	start = (skb_peek(&rose->ack_queue) == NULL) ? rose->va : rose->vs;
61	end   = (rose->va + sysctl_rose_window_size) % ROSE_MODULUS;
62
63	if (start == end)
64		return;
65
66	rose->vs = start;
67
68	/*
69	 * Transmit data until either we're out of data to send or
70	 * the window is full.
71	 */
72
73	skb  = skb_dequeue(&sk->sk_write_queue);
74
75	do {
76		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
77			skb_queue_head(&sk->sk_write_queue, skb);
78			break;
79		}
80
81		skb_set_owner_w(skbn, sk);
82
83		/*
84		 * Transmit the frame copy.
85		 */
86		rose_send_iframe(sk, skbn);
87
88		rose->vs = (rose->vs + 1) % ROSE_MODULUS;
89
90		/*
91		 * Requeue the original data frame.
92		 */
93		skb_queue_tail(&rose->ack_queue, skb);
94
95	} while (rose->vs != end &&
96		 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
97
98	rose->vl         = rose->vr;
99	rose->condition &= ~ROSE_COND_ACK_PENDING;
100
101	rose_stop_timer(sk);
102}
103
104/*
105 * The following routines are taken from page 170 of the 7th ARRL Computer
106 * Networking Conference paper, as is the whole state machine.
107 */
108
109void rose_enquiry_response(struct sock *sk)
110{
111	struct rose_sock *rose = rose_sk(sk);
112
113	if (rose->condition & ROSE_COND_OWN_RX_BUSY)
114		rose_write_internal(sk, ROSE_RNR);
115	else
116		rose_write_internal(sk, ROSE_RR);
117
118	rose->vl         = rose->vr;
119	rose->condition &= ~ROSE_COND_ACK_PENDING;
120
121	rose_stop_timer(sk);
122}
123