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 | */ |
30 | static 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 | |
45 | void 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(list_: &sk->sk_write_queue)) |
58 | return; |
59 | |
60 | start = (skb_peek(list_: &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(list: &sk->sk_write_queue); |
74 | |
75 | do { |
76 | if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { |
77 | skb_queue_head(list: &sk->sk_write_queue, newsk: skb); |
78 | break; |
79 | } |
80 | |
81 | skb_set_owner_w(skb: skbn, sk); |
82 | |
83 | /* |
84 | * Transmit the frame copy. |
85 | */ |
86 | rose_send_iframe(sk, skb: skbn); |
87 | |
88 | rose->vs = (rose->vs + 1) % ROSE_MODULUS; |
89 | |
90 | /* |
91 | * Requeue the original data frame. |
92 | */ |
93 | skb_queue_tail(list: &rose->ack_queue, newsk: skb); |
94 | |
95 | } while (rose->vs != end && |
96 | (skb = skb_dequeue(list: &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 | |
109 | void 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 | |