| /* |
| * 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 (alan@lxorguk.ukuu.org.uk) |
| * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) |
| * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) |
| * Copyright (C) Hans-Joachim Hetscher DD8NE (dd8ne@bnv-bamberg.de) |
| * |
| * 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; |
| } |