295 lines
7.4 KiB
C
295 lines
7.4 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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*
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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*
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* Most of this code is based on the SDL diagrams published in the 7th ARRL
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* Computer Networking Conference papers. The diagrams have mistakes in them,
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* but are mostly correct. Before you modify the code could you read the SDL
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* diagrams as the code is not obvious and probably very easy to break.
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*/
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#include <linux/errno.h>
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#include <linux/filter.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <net/ax25.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <linux/fcntl.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <net/rose.h>
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/*
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* State machine for state 1, Awaiting Call Accepted State.
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* The handling of the timer(s) is in file rose_timer.c.
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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struct rose_sock *rose = rose_sk(sk);
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switch (frametype) {
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case ROSE_CALL_ACCEPTED:
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rose_stop_timer(sk);
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rose_start_idletimer(sk);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->va = 0;
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rose->vr = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_3;
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sk->sk_state = TCP_ESTABLISHED;
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if (!sock_flag(sk, SOCK_DEAD))
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sk->sk_state_change(sk);
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break;
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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default:
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break;
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}
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return 0;
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}
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/*
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* State machine for state 2, Awaiting Clear Confirmation State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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struct rose_sock *rose = rose_sk(sk);
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switch (frametype) {
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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case ROSE_CLEAR_CONFIRMATION:
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rose_disconnect(sk, 0, -1, -1);
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rose->neighbour->use--;
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break;
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default:
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break;
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}
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return 0;
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}
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/*
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* State machine for state 3, Connected State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
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{
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struct rose_sock *rose = rose_sk(sk);
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int queued = 0;
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switch (frametype) {
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case ROSE_RESET_REQUEST:
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rose_stop_timer(sk);
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rose_start_idletimer(sk);
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rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose_requeue_frames(sk);
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break;
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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case ROSE_RR:
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case ROSE_RNR:
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if (!rose_validate_nr(sk, nr)) {
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rose_write_internal(sk, ROSE_RESET_REQUEST);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_4;
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rose_start_t2timer(sk);
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rose_stop_idletimer(sk);
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} else {
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rose_frames_acked(sk, nr);
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if (frametype == ROSE_RNR) {
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rose->condition |= ROSE_COND_PEER_RX_BUSY;
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} else {
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rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
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}
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}
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break;
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case ROSE_DATA: /* XXX */
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rose->condition &= ~ROSE_COND_PEER_RX_BUSY;
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if (!rose_validate_nr(sk, nr)) {
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rose_write_internal(sk, ROSE_RESET_REQUEST);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_4;
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rose_start_t2timer(sk);
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rose_stop_idletimer(sk);
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break;
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}
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rose_frames_acked(sk, nr);
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if (ns == rose->vr) {
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rose_start_idletimer(sk);
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if (sk_filter_trim_cap(sk, skb, ROSE_MIN_LEN) == 0 &&
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__sock_queue_rcv_skb(sk, skb) == 0) {
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rose->vr = (rose->vr + 1) % ROSE_MODULUS;
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queued = 1;
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} else {
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/* Should never happen ! */
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rose_write_internal(sk, ROSE_RESET_REQUEST);
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rose->condition = 0x00;
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rose->vs = 0;
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rose->vr = 0;
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rose->va = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_4;
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rose_start_t2timer(sk);
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rose_stop_idletimer(sk);
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break;
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}
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if (atomic_read(&sk->sk_rmem_alloc) >
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(sk->sk_rcvbuf >> 1))
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rose->condition |= ROSE_COND_OWN_RX_BUSY;
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}
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/*
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* If the window is full, ack the frame, else start the
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* acknowledge hold back timer.
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*/
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if (((rose->vl + sysctl_rose_window_size) % ROSE_MODULUS) == rose->vr) {
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rose->condition &= ~ROSE_COND_ACK_PENDING;
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rose_stop_timer(sk);
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rose_enquiry_response(sk);
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} else {
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rose->condition |= ROSE_COND_ACK_PENDING;
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rose_start_hbtimer(sk);
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}
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break;
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default:
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printk(KERN_WARNING "ROSE: unknown %02X in state 3\n", frametype);
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break;
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}
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return queued;
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}
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/*
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* State machine for state 4, Awaiting Reset Confirmation State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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struct rose_sock *rose = rose_sk(sk);
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switch (frametype) {
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case ROSE_RESET_REQUEST:
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rose_write_internal(sk, ROSE_RESET_CONFIRMATION);
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fallthrough;
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case ROSE_RESET_CONFIRMATION:
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rose_stop_timer(sk);
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rose_start_idletimer(sk);
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rose->condition = 0x00;
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rose->va = 0;
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rose->vr = 0;
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rose->vs = 0;
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rose->vl = 0;
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rose->state = ROSE_STATE_3;
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rose_requeue_frames(sk);
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break;
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case ROSE_CLEAR_REQUEST:
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose->neighbour->use--;
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break;
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default:
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break;
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}
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return 0;
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}
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/*
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* State machine for state 5, Awaiting Call Acceptance State.
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* The handling of the timer(s) is in file rose_timer.c
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* Handling of state 0 and connection release is in af_rose.c.
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*/
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static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int frametype)
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{
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if (frametype == ROSE_CLEAR_REQUEST) {
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rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION);
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rose_disconnect(sk, 0, skb->data[3], skb->data[4]);
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rose_sk(sk)->neighbour->use--;
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}
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return 0;
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}
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/* Higher level upcall for a LAPB frame */
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int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb)
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{
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struct rose_sock *rose = rose_sk(sk);
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int queued = 0, frametype, ns, nr, q, d, m;
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if (rose->state == ROSE_STATE_0)
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return 0;
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frametype = rose_decode(skb, &ns, &nr, &q, &d, &m);
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switch (rose->state) {
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case ROSE_STATE_1:
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queued = rose_state1_machine(sk, skb, frametype);
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break;
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case ROSE_STATE_2:
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queued = rose_state2_machine(sk, skb, frametype);
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break;
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case ROSE_STATE_3:
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queued = rose_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
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break;
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case ROSE_STATE_4:
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queued = rose_state4_machine(sk, skb, frametype);
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break;
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case ROSE_STATE_5:
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queued = rose_state5_machine(sk, skb, frametype);
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break;
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}
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rose_kick(sk);
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return queued;
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}
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