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