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/sched.h> 15 #include <linux/timer.h> 16 #include <linux/string.h> 17 #include <linux/sockios.h> 18 #include <linux/net.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 */ 34 static 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 49 void 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 */ 112 113 void 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