[linux.git] / net / ax25 / ax25_std_in.c

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Copyright (C) Alan Cox GW4PTS ([email protected])
 * Copyright (C) Jonathan Naylor G4KLX ([email protected])
 * Copyright (C) Joerg Reuter DL1BKE ([email protected])
 * Copyright (C) Hans-Joachim Hetscher DD8NE ([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/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 <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>

/*
 *	State machine for state 1, Awaiting Connection State.
 *	The handling of the timer(s) is in file ax25_std_timer.c.
 *	Handling of state 0 and connection release is in ax25.c.
 */
static int ax25_std_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
{
	switch (frametype) {
	case AX25_SABM:
		ax25->modulus = AX25_MODULUS;
		ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
		break;

	case AX25_SABME:
		ax25->modulus = AX25_EMODULUS;
		ax25->window  = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
		break;

	case AX25_DISC:
		ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
		break;

	case AX25_UA:
		if (pf) {
			ax25_calculate_rtt(ax25);
			ax25_stop_t1timer(ax25);
			ax25_start_t3timer(ax25);
			ax25_start_idletimer(ax25);
			ax25->vs      = 0;
			ax25->va      = 0;
			ax25->vr      = 0;
			ax25->state   = AX25_STATE_3;
			ax25->n2count = 0;
			if (ax25->sk != NULL) {
				bh_lock_sock(ax25->sk);
				ax25->sk->sk_state = TCP_ESTABLISHED;
				/* For WAIT_SABM connections we will produce an accept ready socket here */
				if (!sock_flag(ax25->sk, SOCK_DEAD))
					ax25->sk->sk_state_change(ax25->sk);
				bh_unlock_sock(ax25->sk);
			}
		}
		break;

	case AX25_DM:
		if (pf) {
			if (ax25->modulus == AX25_MODULUS) {
				ax25_disconnect(ax25, ECONNREFUSED);
			} else {
				ax25->modulus = AX25_MODULUS;
				ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
			}
		}
		break;

	default:
		break;
	}

	return 0;
}

/*
 *	State machine for state 2, Awaiting Release State.
 *	The handling of the timer(s) is in file ax25_std_timer.c
 *	Handling of state 0 and connection release is in ax25.c.
 */
static int ax25_std_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
{
	switch (frametype) {
	case AX25_SABM:
	case AX25_SABME:
		ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
		break;

	case AX25_DISC:
		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
		ax25_disconnect(ax25, 0);
		break;

	case AX25_DM:
	case AX25_UA:
		if (pf)
			ax25_disconnect(ax25, 0);
		break;

	case AX25_I:
	case AX25_REJ:
	case AX25_RNR:
	case AX25_RR:
		if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
		break;

	default:
		break;
	}

	return 0;
}

/*
 *	State machine for state 3, Connected State.
 *	The handling of the timer(s) is in file ax25_std_timer.c
 *	Handling of state 0 and connection release is in ax25.c.
 */
static int ax25_std_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
{
	int queued = 0;

	switch (frametype) {
	case AX25_SABM:
	case AX25_SABME:
		if (frametype == AX25_SABM) {
			ax25->modulus = AX25_MODULUS;
			ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
		} else {
			ax25->modulus = AX25_EMODULUS;
			ax25->window  = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
		}
		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
		ax25_stop_t1timer(ax25);
		ax25_stop_t2timer(ax25);
		ax25_start_t3timer(ax25);
		ax25_start_idletimer(ax25);
		ax25->condition = 0x00;
		ax25->vs        = 0;
		ax25->va        = 0;
		ax25->vr        = 0;
		ax25_requeue_frames(ax25);
		break;

	case AX25_DISC:
		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
		ax25_disconnect(ax25, 0);
		break;

	case AX25_DM:
		ax25_disconnect(ax25, ECONNRESET);
		break;

	case AX25_RR:
	case AX25_RNR:
		if (frametype == AX25_RR)
			ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
		else
			ax25->condition |= AX25_COND_PEER_RX_BUSY;
		if (type == AX25_COMMAND && pf)
			ax25_std_enquiry_response(ax25);
		if (ax25_validate_nr(ax25, nr)) {
			ax25_check_iframes_acked(ax25, nr);
		} else {
			ax25_std_nr_error_recovery(ax25);
			ax25->state = AX25_STATE_1;
		}
		break;

	case AX25_REJ:
		ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
		if (type == AX25_COMMAND && pf)
			ax25_std_enquiry_response(ax25);
		if (ax25_validate_nr(ax25, nr)) {
			ax25_frames_acked(ax25, nr);
			ax25_calculate_rtt(ax25);
			ax25_stop_t1timer(ax25);
			ax25_start_t3timer(ax25);
			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;
		}
		if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
			ax25_frames_acked(ax25, nr);
		} else {
			ax25_check_iframes_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;
}

/*
 *	State machine for state 4, Timer Recovery State.
 *	The handling of the timer(s) is in file ax25_std_timer.c
 *	Handling of state 0 and connection release is in ax25.c.
 */
static int ax25_std_state4_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
{
	int queued = 0;

	switch (frametype) {
	case AX25_SABM:
	case AX25_SABME:
		if (frametype == AX25_SABM) {
			ax25->modulus = AX25_MODULUS;
			ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
		} else {
			ax25->modulus = AX25_EMODULUS;
			ax25->window  = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
		}
		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
		ax25_stop_t1timer(ax25);
		ax25_stop_t2timer(ax25);
		ax25_start_t3timer(ax25);
		ax25_start_idletimer(ax25);
		ax25->condition = 0x00;
		ax25->vs        = 0;
		ax25->va        = 0;
		ax25->vr        = 0;
		ax25->state     = AX25_STATE_3;
		ax25->n2count   = 0;
		ax25_requeue_frames(ax25);
		break;

	case AX25_DISC:
		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
		ax25_disconnect(ax25, 0);
		break;

	case AX25_DM:
		ax25_disconnect(ax25, ECONNRESET);
		break;

	case AX25_RR:
	case AX25_RNR:
		if (frametype == AX25_RR)
			ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
		else
			ax25->condition |= AX25_COND_PEER_RX_BUSY;
		if (type == AX25_RESPONSE && pf) {
			ax25_stop_t1timer(ax25);
			ax25->n2count = 0;
			if (ax25_validate_nr(ax25, nr)) {
				ax25_frames_acked(ax25, nr);
				if (ax25->vs == ax25->va) {
					ax25_start_t3timer(ax25);
					ax25->state   = AX25_STATE_3;
				} else {
					ax25_requeue_frames(ax25);
				}
			} else {
				ax25_std_nr_error_recovery(ax25);
				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);
		} else {
			ax25_std_nr_error_recovery(ax25);
			ax25->state = AX25_STATE_1;
		}
		break;

	case AX25_REJ:
		ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
		if (pf && type == AX25_RESPONSE) {
			ax25_stop_t1timer(ax25);
			ax25->n2count = 0;
			if (ax25_validate_nr(ax25, nr)) {
				ax25_frames_acked(ax25, nr);
				if (ax25->vs == ax25->va) {
					ax25_start_t3timer(ax25);
					ax25->state   = AX25_STATE_3;
				} else {
					ax25_requeue_frames(ax25);
				}
			} else {
				ax25_std_nr_error_recovery(ax25);
				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;
}
Commit	Line	Data
1da177e4 LT	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) Alan Cox GW4PTS ([email protected])
	8	* Copyright (C) Jonathan Naylor G4KLX ([email protected])
	9	* Copyright (C) Joerg Reuter DL1BKE ([email protected])
	10	* Copyright (C) Hans-Joachim Hetscher DD8NE ([email protected])
	11	*
	12	* Most of this code is based on the SDL diagrams published in the 7th ARRL
	13	* Computer Networking Conference papers. The diagrams have mistakes in them,
	14	* but are mostly correct. Before you modify the code could you read the SDL
	15	* diagrams as the code is not obvious and probably very easy to break.
	16	*/
	17	#include <linux/errno.h>
	18	#include <linux/types.h>
	19	#include <linux/socket.h>
	20	#include <linux/in.h>
	21	#include <linux/kernel.h>
1da177e4 LT	22	#include <linux/timer.h>
	23	#include <linux/string.h>
	24	#include <linux/sockios.h>
	25	#include <linux/net.h>
	26	#include <net/ax25.h>
	27	#include <linux/inet.h>
	28	#include <linux/netdevice.h>
	29	#include <linux/skbuff.h>
	30	#include <net/sock.h>
c752f073	31	#include <net/tcp_states.h>
1da177e4 LT	32	#include <asm/uaccess.h>
	33	#include <asm/system.h>
	34	#include <linux/fcntl.h>
	35	#include <linux/mm.h>
	36	#include <linux/interrupt.h>
	37
	38	/*
	39	* State machine for state 1, Awaiting Connection State.
	40	* The handling of the timer(s) is in file ax25_std_timer.c.
	41	* Handling of state 0 and connection release is in ax25.c.
	42	*/
	43	static int ax25_std_state1_machine(ax25_cb ax25, struct sk_buff skb, int frametype, int pf, int type)
	44	{
	45	switch (frametype) {
	46	case AX25_SABM:
	47	ax25->modulus = AX25_MODULUS;
	48	ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
	49	ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
	50	break;
	51
	52	case AX25_SABME:
	53	ax25->modulus = AX25_EMODULUS;
	54	ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
	55	ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
	56	break;
	57
	58	case AX25_DISC:
	59	ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
	60	break;
	61
	62	case AX25_UA:
	63	if (pf) {
	64	ax25_calculate_rtt(ax25);
	65	ax25_stop_t1timer(ax25);
	66	ax25_start_t3timer(ax25);
	67	ax25_start_idletimer(ax25);
	68	ax25->vs = 0;
	69	ax25->va = 0;
	70	ax25->vr = 0;
	71	ax25->state = AX25_STATE_3;
	72	ax25->n2count = 0;
	73	if (ax25->sk != NULL) {
	74	bh_lock_sock(ax25->sk);
	75	ax25->sk->sk_state = TCP_ESTABLISHED;
	76	/* For WAIT_SABM connections we will produce an accept ready socket here */
	77	if (!sock_flag(ax25->sk, SOCK_DEAD))
	78	ax25->sk->sk_state_change(ax25->sk);
	79	bh_unlock_sock(ax25->sk);
	80	}
	81	}
	82	break;
	83
	84	case AX25_DM:
	85	if (pf) {
	86	if (ax25->modulus == AX25_MODULUS) {
	87	ax25_disconnect(ax25, ECONNREFUSED);
	88	} else {
	89	ax25->modulus = AX25_MODULUS;
	90	ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
	91	}
	92	}
	93	break;
	94
	95	default:
96	break;
97	}
98
99	return 0;
100	}
101
102	/*
103	* State machine for state 2, Awaiting Release State.
104	* The handling of the timer(s) is in file ax25_std_timer.c
105	* Handling of state 0 and connection release is in ax25.c.
106	*/
107	static int ax25_std_state2_machine(ax25_cb ax25, struct sk_buff skb, int frametype, int pf, int type)
108	{
109	switch (frametype) {
110	case AX25_SABM:
111	case AX25_SABME:
112	ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
113	break;
114
115	case AX25_DISC:
116	ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
117	ax25_disconnect(ax25, 0);
118	break;
119
120	case AX25_DM:
121	case AX25_UA:
122	if (pf)
123	ax25_disconnect(ax25, 0);
124	break;
125
126	case AX25_I:
127	case AX25_REJ:
128	case AX25_RNR:
129	case AX25_RR:
130	if (pf) ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
131	break;
132
133	default:
134	break;
135	}
136
137	return 0;
138	}
139
140	/*
141	* State machine for state 3, Connected State.
142	* The handling of the timer(s) is in file ax25_std_timer.c
143	* Handling of state 0 and connection release is in ax25.c.
144	*/
145	static int ax25_std_state3_machine(ax25_cb ax25, struct sk_buff skb, int frametype, int ns, int nr, int pf, int type)
146	{
147	int queued = 0;
148
149	switch (frametype) {
150	case AX25_SABM:
151	case AX25_SABME:
152	if (frametype == AX25_SABM) {
153	ax25->modulus = AX25_MODULUS;
154	ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
155	} else {
156	ax25->modulus = AX25_EMODULUS;
157	ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
158	}
159	ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
160	ax25_stop_t1timer(ax25);
161	ax25_stop_t2timer(ax25);
162	ax25_start_t3timer(ax25);
163	ax25_start_idletimer(ax25);
164	ax25->condition = 0x00;
165	ax25->vs = 0;
166	ax25->va = 0;
167	ax25->vr = 0;
168	ax25_requeue_frames(ax25);
169	break;
170
171	case AX25_DISC:
172	ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
173	ax25_disconnect(ax25, 0);
174	break;
175
176	case AX25_DM:
177	ax25_disconnect(ax25, ECONNRESET);
178	break;
179
180	case AX25_RR:
181	case AX25_RNR:
182	if (frametype == AX25_RR)
183	ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
184	else
185	ax25->condition \|= AX25_COND_PEER_RX_BUSY;
186	if (type == AX25_COMMAND && pf)
187	ax25_std_enquiry_response(ax25);
188	if (ax25_validate_nr(ax25, nr)) {
189	ax25_check_iframes_acked(ax25, nr);
190	} else {
191	ax25_std_nr_error_recovery(ax25);
192	ax25->state = AX25_STATE_1;
193	}
194	break;
195
196	case AX25_REJ:
197	ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
198	if (type == AX25_COMMAND && pf)
199	ax25_std_enquiry_response(ax25);
200	if (ax25_validate_nr(ax25, nr)) {
201	ax25_frames_acked(ax25, nr);
202	ax25_calculate_rtt(ax25);
203	ax25_stop_t1timer(ax25);
204	ax25_start_t3timer(ax25);
205	ax25_requeue_frames(ax25);
206	} else {
207	ax25_std_nr_error_recovery(ax25);
208	ax25->state = AX25_STATE_1;
209	}
210	break;
211
212	case AX25_I:
213	if (!ax25_validate_nr(ax25, nr)) {
214	ax25_std_nr_error_recovery(ax25);
215	ax25->state = AX25_STATE_1;
216	break;
217	}
218	if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
219	ax25_frames_acked(ax25, nr);
220	} else {
221	ax25_check_iframes_acked(ax25, nr);
222	}
223	if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
224	if (pf) ax25_std_enquiry_response(ax25);
225	break;
226	}
227	if (ns == ax25->vr) {
228	ax25->vr = (ax25->vr + 1) % ax25->modulus;
229	queued = ax25_rx_iframe(ax25, skb);
230	if (ax25->condition & AX25_COND_OWN_RX_BUSY)
231	ax25->vr = ns; /* ax25->vr - 1 */
232	ax25->condition &= ~AX25_COND_REJECT;
233	if (pf) {
234	ax25_std_enquiry_response(ax25);
235	} else {
236	if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
237	ax25->condition \|= AX25_COND_ACK_PENDING;
238	ax25_start_t2timer(ax25);
239	}
240	}
241	} else {
242	if (ax25->condition & AX25_COND_REJECT) {
243	if (pf) ax25_std_enquiry_response(ax25);
244	} else {
245	ax25->condition \|= AX25_COND_REJECT;
246	ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
247	ax25->condition &= ~AX25_COND_ACK_PENDING;
248	}
249	}
250	break;
251
252	case AX25_FRMR:
253	case AX25_ILLEGAL:
254	ax25_std_establish_data_link(ax25);
255	ax25->state = AX25_STATE_1;
256	break;
257
258	default:
259	break;
260	}
261
262	return queued;
263	}
264
265	/*
266	* State machine for state 4, Timer Recovery State.
267	* The handling of the timer(s) is in file ax25_std_timer.c
268	* Handling of state 0 and connection release is in ax25.c.
269	*/
270	static int ax25_std_state4_machine(ax25_cb ax25, struct sk_buff skb, int frametype, int ns, int nr, int pf, int type)
271	{
272	int queued = 0;
273
274	switch (frametype) {
275	case AX25_SABM:
276	case AX25_SABME:
277	if (frametype == AX25_SABM) {
278	ax25->modulus = AX25_MODULUS;
279	ax25->window = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
280	} else {
281	ax25->modulus = AX25_EMODULUS;
282	ax25->window = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
283	}
284	ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
285	ax25_stop_t1timer(ax25);
286	ax25_stop_t2timer(ax25);
287	ax25_start_t3timer(ax25);
288	ax25_start_idletimer(ax25);
289	ax25->condition = 0x00;
290	ax25->vs = 0;
291	ax25->va = 0;
292	ax25->vr = 0;
293	ax25->state = AX25_STATE_3;
294	ax25->n2count = 0;
295	ax25_requeue_frames(ax25);
296	break;
297
298	case AX25_DISC:
299	ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
300	ax25_disconnect(ax25, 0);
301	break;
302
303	case AX25_DM:
304	ax25_disconnect(ax25, ECONNRESET);
305	break;
306
307	case AX25_RR:
308	case AX25_RNR:
309	if (frametype == AX25_RR)
310	ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
311	else
312	ax25->condition \|= AX25_COND_PEER_RX_BUSY;
313	if (type == AX25_RESPONSE && pf) {
314	ax25_stop_t1timer(ax25);
315	ax25->n2count = 0;
316	if (ax25_validate_nr(ax25, nr)) {
317	ax25_frames_acked(ax25, nr);
318	if (ax25->vs == ax25->va) {
319	ax25_start_t3timer(ax25);
320	ax25->state = AX25_STATE_3;
321	} else {
322	ax25_requeue_frames(ax25);
323	}
324	} else {
325	ax25_std_nr_error_recovery(ax25);
326	ax25->state = AX25_STATE_1;
327	}
328	break;
329	}
330	if (type == AX25_COMMAND && pf)
331	ax25_std_enquiry_response(ax25);
332	if (ax25_validate_nr(ax25, nr)) {
333	ax25_frames_acked(ax25, nr);
334	} else {
335	ax25_std_nr_error_recovery(ax25);
336	ax25->state = AX25_STATE_1;
337	}
338	break;
339
340	case AX25_REJ:
341	ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
342	if (pf && type == AX25_RESPONSE) {
343	ax25_stop_t1timer(ax25);
344	ax25->n2count = 0;
345	if (ax25_validate_nr(ax25, nr)) {
346	ax25_frames_acked(ax25, nr);
347	if (ax25->vs == ax25->va) {
348	ax25_start_t3timer(ax25);
349	ax25->state = AX25_STATE_3;
350	} else {
351	ax25_requeue_frames(ax25);
352	}
353	} else {
354	ax25_std_nr_error_recovery(ax25);
355	ax25->state = AX25_STATE_1;
356	}
357	break;
358	}
359	if (type == AX25_COMMAND && pf)
360	ax25_std_enquiry_response(ax25);
361	if (ax25_validate_nr(ax25, nr)) {
362	ax25_frames_acked(ax25, nr);
363	ax25_requeue_frames(ax25);
364	} else {
365	ax25_std_nr_error_recovery(ax25);
366	ax25->state = AX25_STATE_1;
367	}
368	break;
369
370	case AX25_I:
371	if (!ax25_validate_nr(ax25, nr)) {
372	ax25_std_nr_error_recovery(ax25);
373	ax25->state = AX25_STATE_1;
374	break;
375	}
376	ax25_frames_acked(ax25, nr);
377	if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
378	if (pf)
379	ax25_std_enquiry_response(ax25);
380	break;
381	}
382	if (ns == ax25->vr) {
383	ax25->vr = (ax25->vr + 1) % ax25->modulus;
384	queued = ax25_rx_iframe(ax25, skb);
385	if (ax25->condition & AX25_COND_OWN_RX_BUSY)
386	ax25->vr = ns; /* ax25->vr - 1 */
387	ax25->condition &= ~AX25_COND_REJECT;
388	if (pf) {
389	ax25_std_enquiry_response(ax25);
390	} else {
391	if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
392	ax25->condition \|= AX25_COND_ACK_PENDING;
393	ax25_start_t2timer(ax25);
394	}
395	}
396	} else {
397	if (ax25->condition & AX25_COND_REJECT) {
398	if (pf) ax25_std_enquiry_response(ax25);
399	} else {
400	ax25->condition \|= AX25_COND_REJECT;
401	ax25_send_control(ax25, AX25_REJ, pf, AX25_RESPONSE);
402	ax25->condition &= ~AX25_COND_ACK_PENDING;
403	}
404	}
405	break;
406
407	case AX25_FRMR:
408	case AX25_ILLEGAL:
409	ax25_std_establish_data_link(ax25);
410	ax25->state = AX25_STATE_1;
411	break;
412
413	default:
414	break;
415	}
416
417	return queued;
418	}
419
420	/*
421	* Higher level upcall for a LAPB frame
422	*/
423	int ax25_std_frame_in(ax25_cb ax25, struct sk_buff skb, int type)
424	{
425	int queued = 0, frametype, ns, nr, pf;
426
427	frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
428
429	switch (ax25->state) {
430	case AX25_STATE_1:
431	queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type);
432	break;
433	case AX25_STATE_2:
434	queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type);
435	break;
436	case AX25_STATE_3:
437	queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
438	break;
439	case AX25_STATE_4:
440	queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type);
441	break;
442	}
443
444	ax25_kick(ax25);
445
446	return queued;
447	}