444 lines
11 KiB
C
444 lines
11 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) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
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* Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de)
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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/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/uaccess.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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/*
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* State machine for state 1, Awaiting Connection State.
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* The handling of the timer(s) is in file ax25_std_timer.c.
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* Handling of state 0 and connection release is in ax25.c.
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*/
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static int ax25_std_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
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{
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switch (frametype) {
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case AX25_SABM:
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ax25->modulus = AX25_MODULUS;
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ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
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ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
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break;
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case AX25_SABME:
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ax25->modulus = AX25_EMODULUS;
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ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
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ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
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break;
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case AX25_DISC:
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ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
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break;
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case AX25_UA:
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if (pf) {
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ax25_calculate_rtt(ax25);
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ax25_stop_t1timer(ax25);
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ax25_start_t3timer(ax25);
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ax25_start_idletimer(ax25);
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ax25->vs = 0;
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ax25->va = 0;
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ax25->vr = 0;
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ax25->state = AX25_STATE_3;
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ax25->n2count = 0;
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if (ax25->sk != NULL) {
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bh_lock_sock(ax25->sk);
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ax25->sk->sk_state = TCP_ESTABLISHED;
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/* For WAIT_SABM connections we will produce an accept ready socket here */
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if (!sock_flag(ax25->sk, SOCK_DEAD))
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ax25->sk->sk_state_change(ax25->sk);
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bh_unlock_sock(ax25->sk);
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}
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}
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break;
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case AX25_DM:
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if (pf) {
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if (ax25->modulus == AX25_MODULUS) {
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ax25_disconnect(ax25, ECONNREFUSED);
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} else {
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ax25->modulus = AX25_MODULUS;
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ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
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}
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}
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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 Release State.
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* The handling of the timer(s) is in file ax25_std_timer.c
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* Handling of state 0 and connection release is in ax25.c.
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*/
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static int ax25_std_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
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{
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switch (frametype) {
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case AX25_SABM:
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case AX25_SABME:
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ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
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break;
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case AX25_DISC:
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ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
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ax25_disconnect(ax25, 0);
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break;
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case AX25_DM:
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case AX25_UA:
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if (pf)
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ax25_disconnect(ax25, 0);
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break;
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case AX25_I:
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case AX25_REJ:
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case AX25_RNR:
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case AX25_RR:
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if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
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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 ax25_std_timer.c
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* Handling of state 0 and connection release is in ax25.c.
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*/
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static int ax25_std_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
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{
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int queued = 0;
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switch (frametype) {
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case AX25_SABM:
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case AX25_SABME:
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if (frametype == AX25_SABM) {
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ax25->modulus = AX25_MODULUS;
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ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
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} else {
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ax25->modulus = AX25_EMODULUS;
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ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
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}
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ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
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ax25_stop_t1timer(ax25);
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ax25_stop_t2timer(ax25);
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ax25_start_t3timer(ax25);
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ax25_start_idletimer(ax25);
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ax25->condition = 0x00;
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ax25->vs = 0;
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ax25->va = 0;
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ax25->vr = 0;
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ax25_requeue_frames(ax25);
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break;
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case AX25_DISC:
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ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
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ax25_disconnect(ax25, 0);
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break;
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case AX25_DM:
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ax25_disconnect(ax25, ECONNRESET);
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break;
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case AX25_RR:
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case AX25_RNR:
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if (frametype == AX25_RR)
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ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
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else
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ax25->condition |= AX25_COND_PEER_RX_BUSY;
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if (type == AX25_COMMAND && pf)
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ax25_std_enquiry_response(ax25);
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if (ax25_validate_nr(ax25, nr)) {
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ax25_check_iframes_acked(ax25, nr);
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} else {
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ax25_std_nr_error_recovery(ax25);
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ax25->state = AX25_STATE_1;
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}
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break;
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case AX25_REJ:
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ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
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if (type == AX25_COMMAND && pf)
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ax25_std_enquiry_response(ax25);
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if (ax25_validate_nr(ax25, nr)) {
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ax25_frames_acked(ax25, nr);
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ax25_calculate_rtt(ax25);
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ax25_stop_t1timer(ax25);
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ax25_start_t3timer(ax25);
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ax25_requeue_frames(ax25);
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} else {
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ax25_std_nr_error_recovery(ax25);
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ax25->state = AX25_STATE_1;
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}
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break;
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case AX25_I:
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if (!ax25_validate_nr(ax25, nr)) {
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ax25_std_nr_error_recovery(ax25);
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ax25->state = AX25_STATE_1;
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break;
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}
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if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
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ax25_frames_acked(ax25, nr);
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} else {
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ax25_check_iframes_acked(ax25, nr);
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}
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if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
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if (pf) ax25_std_enquiry_response(ax25);
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break;
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}
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if (ns == ax25->vr) {
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ax25->vr = (ax25->vr + 1) % ax25->modulus;
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queued = ax25_rx_iframe(ax25, skb);
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if (ax25->condition & AX25_COND_OWN_RX_BUSY)
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ax25->vr = ns; /* ax25->vr - 1 */
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ax25->condition &= ~AX25_COND_REJECT;
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if (pf) {
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ax25_std_enquiry_response(ax25);
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} else {
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if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
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ax25->condition |= AX25_COND_ACK_PENDING;
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ax25_start_t2timer(ax25);
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}
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}
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} else {
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if (ax25->condition & AX25_COND_REJECT) {
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if (pf) ax25_std_enquiry_response(ax25);
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} else {
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ax25->condition |= AX25_COND_REJECT;
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ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
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ax25->condition &= ~AX25_COND_ACK_PENDING;
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}
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}
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break;
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case AX25_FRMR:
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case AX25_ILLEGAL:
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ax25_std_establish_data_link(ax25);
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ax25->state = AX25_STATE_1;
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break;
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default:
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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, Timer Recovery State.
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* The handling of the timer(s) is in file ax25_std_timer.c
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* Handling of state 0 and connection release is in ax25.c.
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*/
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static int ax25_std_state4_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
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{
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int queued = 0;
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switch (frametype) {
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case AX25_SABM:
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case AX25_SABME:
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if (frametype == AX25_SABM) {
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ax25->modulus = AX25_MODULUS;
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ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
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} else {
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ax25->modulus = AX25_EMODULUS;
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ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
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}
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ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
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ax25_stop_t1timer(ax25);
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ax25_stop_t2timer(ax25);
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ax25_start_t3timer(ax25);
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ax25_start_idletimer(ax25);
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ax25->condition = 0x00;
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ax25->vs = 0;
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ax25->va = 0;
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ax25->vr = 0;
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ax25->state = AX25_STATE_3;
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ax25->n2count = 0;
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ax25_requeue_frames(ax25);
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break;
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case AX25_DISC:
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ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
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ax25_disconnect(ax25, 0);
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break;
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case AX25_DM:
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ax25_disconnect(ax25, ECONNRESET);
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break;
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case AX25_RR:
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case AX25_RNR:
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if (frametype == AX25_RR)
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ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
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else
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ax25->condition |= AX25_COND_PEER_RX_BUSY;
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if (type == AX25_RESPONSE && pf) {
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ax25_stop_t1timer(ax25);
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ax25->n2count = 0;
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if (ax25_validate_nr(ax25, nr)) {
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ax25_frames_acked(ax25, nr);
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if (ax25->vs == ax25->va) {
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ax25_start_t3timer(ax25);
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ax25->state = AX25_STATE_3;
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} else {
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ax25_requeue_frames(ax25);
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}
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} else {
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ax25_std_nr_error_recovery(ax25);
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ax25->state = AX25_STATE_1;
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}
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break;
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}
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if (type == AX25_COMMAND && pf)
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ax25_std_enquiry_response(ax25);
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if (ax25_validate_nr(ax25, nr)) {
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ax25_frames_acked(ax25, nr);
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} else {
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ax25_std_nr_error_recovery(ax25);
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ax25->state = AX25_STATE_1;
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}
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break;
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case AX25_REJ:
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ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
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if (pf && type == AX25_RESPONSE) {
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ax25_stop_t1timer(ax25);
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ax25->n2count = 0;
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if (ax25_validate_nr(ax25, nr)) {
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ax25_frames_acked(ax25, nr);
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if (ax25->vs == ax25->va) {
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ax25_start_t3timer(ax25);
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ax25->state = AX25_STATE_3;
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} else {
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ax25_requeue_frames(ax25);
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}
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} else {
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ax25_std_nr_error_recovery(ax25);
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ax25->state = AX25_STATE_1;
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
if (type == AX25_COMMAND && pf)
|
||
|
|
ax25_std_enquiry_response(ax25);
|
||
|
|
if (ax25_validate_nr(ax25, nr)) {
|
||
|
|
ax25_frames_acked(ax25, nr);
|
||
|
|
ax25_requeue_frames(ax25);
|
||
|
|
} else {
|
||
|
|
ax25_std_nr_error_recovery(ax25);
|
||
|
|
ax25->state = AX25_STATE_1;
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
|
||
|
|
case AX25_I:
|
||
|
|
if (!ax25_validate_nr(ax25, nr)) {
|
||
|
|
ax25_std_nr_error_recovery(ax25);
|
||
|
|
ax25->state = AX25_STATE_1;
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
ax25_frames_acked(ax25, nr);
|
||
|
|
if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
|
||
|
|
if (pf)
|
||
|
|
ax25_std_enquiry_response(ax25);
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
if (ns == ax25->vr) {
|
||
|
|
ax25->vr = (ax25->vr + 1) % ax25->modulus;
|
||
|
|
queued = ax25_rx_iframe(ax25, skb);
|
||
|
|
if (ax25->condition & AX25_COND_OWN_RX_BUSY)
|
||
|
|
ax25->vr = ns; /* ax25->vr - 1 */
|
||
|
|
ax25->condition &= ~AX25_COND_REJECT;
|
||
|
|
if (pf) {
|
||
|
|
ax25_std_enquiry_response(ax25);
|
||
|
|
} else {
|
||
|
|
if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
|
||
|
|
ax25->condition |= AX25_COND_ACK_PENDING;
|
||
|
|
ax25_start_t2timer(ax25);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
if (ax25->condition & AX25_COND_REJECT) {
|
||
|
|
if (pf) ax25_std_enquiry_response(ax25);
|
||
|
|
} else {
|
||
|
|
ax25->condition |= AX25_COND_REJECT;
|
||
|
|
ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
|
||
|
|
ax25->condition &= ~AX25_COND_ACK_PENDING;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
break;
|
||
|
|
|
||
|
|
case AX25_FRMR:
|
||
|
|
case AX25_ILLEGAL:
|
||
|
|
ax25_std_establish_data_link(ax25);
|
||
|
|
ax25->state = AX25_STATE_1;
|
||
|
|
break;
|
||
|
|
|
||
|
|
default:
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
return queued;
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Higher level upcall for a LAPB frame
|
||
|
|
*/
|
||
|
|
int ax25_std_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
|
||
|
|
{
|
||
|
|
int queued = 0, frametype, ns, nr, pf;
|
||
|
|
|
||
|
|
frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
|
||
|
|
|
||
|
|
switch (ax25->state) {
|
||
|
|
case AX25_STATE_1:
|
||
|
|
queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type);
|
||
|
|
break;
|
||
|
|
case AX25_STATE_2:
|
||
|
|
queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type);
|
||
|
|
break;
|
||
|
|
case AX25_STATE_3:
|
||
|
|
queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
|
||
|
|
break;
|
||
|
|
case AX25_STATE_4:
|
||
|
|
queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type);
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
|
||
|
|
ax25_kick(ax25);
|
||
|
|
|
||
|
|
return queued;
|
||
|
|
}
|