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443 lines
11 KiB
443 lines
11 KiB
// 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 ([email protected]) |
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* Copyright (C) Jonathan Naylor G4KLX ([email protected]) |
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* Copyright (C) Joerg Reuter DL1BKE ([email protected]) |
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* Copyright (C) Hans-Joachim Hetscher DD8NE ([email protected]) |
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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; |
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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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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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ax25_frames_acked(ax25, nr); |
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if (ax25->condition & AX25_COND_OWN_RX_BUSY) { |
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if (pf) |
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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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* Higher level upcall for a LAPB frame |
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*/ |
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int ax25_std_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type) |
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{ |
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int queued = 0, frametype, ns, nr, pf; |
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frametype = ax25_decode(ax25, skb, &ns, &nr, &pf); |
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switch (ax25->state) { |
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case AX25_STATE_1: |
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queued = ax25_std_state1_machine(ax25, skb, frametype, pf, type); |
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break; |
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case AX25_STATE_2: |
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queued = ax25_std_state2_machine(ax25, skb, frametype, pf, type); |
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break; |
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case AX25_STATE_3: |
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queued = ax25_std_state3_machine(ax25, skb, frametype, ns, nr, pf, type); |
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break; |
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case AX25_STATE_4: |
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queued = ax25_std_state4_machine(ax25, skb, frametype, ns, nr, pf, type); |
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break; |
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} |
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ax25_kick(ax25); |
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return queued; |
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}
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