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 */ 33 static 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 48 void 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 */ 111 112 void 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